2020-10-22T04:59:41Zhttp://edoc.mpg.de/ac_p_oai.ploai:edoc.mpg.de:2048802005-07-0837:954
Article
Two-Loop Bethe logarithms for higher excited S levels
2004-11-15
052108
Physical Review A
Phys. Rev. A
70
Processes mediated by two virtual low-energy photons contribute quite significantly to the energy of hydrogenic S states. The corresponding level shift is of the order of (alpha/pi)2 (Zalpha)6 mec2 and may be ascribed to a two-loop generalization of the Bethe logarithm. For 1S and 2S states, the correction has recently been evaluated by Pachucki and Jentschura [Phys. Rev. Lett. 91, 113005 (2003)]. Here, we generalize the approach to higher excited S states, which in contrast to the 1S and 2S states can decay to P states via the electric-dipole (E1) channel. The more complex structure of the excited-state wave functions and the necessity to subtract P-state poles lead to additional calculational problems. In addition to the calculation of the excited-state two-loop energy shift, we investigate the ambiguity in the energy level definition due to squared decay rates.
expertsonly
published
notspecified
U. D.
Jentschura
Ulrich David
http://link.aps.org/abstract/PRA/v70/e052108
Two-Loop Bethe logarithms for higher excited S levels
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2005
2005-07-08 10:30:54.584279
©2004 The American Physical Society
oai:edoc.mpg.de:2048812005-07-0837:954
Article
Nonrelativistic QED Approach to the Bound-Electron g Factor
2004-10-06
150401
Physical Review Letters
Phys. Rev. Lett.
15
93
Within a systematic approach based on nonrelativistic quantum electrodynamics, we derive the one-loop self-energy correction of order alpha(Zalpha)4 to the bound-electron g factor. In combination with numerical data, this analytic result improves theoretical predictions for the self-energy correction for carbon and oxygen by an order of magnitude. Basing on one-loop calculations, we obtain the logarithmic two-loop contribution of order alpha2(Zalpha)4ln[(Zalpha)–2] and the dominant part of the corresponding constant term. The results obtained improve the accuracy of the theoretical predictions for the 1S bound-electron g factor and influence the value of the electron mass determined from g-factor measurements.
expertsonly
published
notspecified
K.
Pachucki
Krzysztof
U. D.
Jentschura
Ulrich David
V. A.
Yerokhin
Vladimir A.
http://link.aps.org/abstract/PRL/v93/e150401
Institute of Theoretical Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw, Poland
Physics Department, St. Petersburg State University, Oulianovskaya 1, Petrodvorets, St. Petersburg 198504, Russia
Nonrelativistic QED Approach to the Bound-Electron g Factor
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2005
2005-07-08 10:30:27.910491
©2004 The American Physical Society
oai:edoc.mpg.de:2048822006-08-2137:954
Article
Magnetic and thermal influences on collective resonance fluorescence
2004-10-01
391
397
Europhysics Letters
Europhys. Lett.
3
68
The quantum properties of a collection of dipole-interacting three-level V- and $\Lambda$-type atoms are investigated in the presence of external coherent sources and a thermal bath. It is demonstrated that both the steady-state collective populations and the spectral features of these samples can be manipulated by varying the temperature or especially the atomic-level spacings by, e.g., static magnetic fields.
expertsonly
published
notspecified
M.
Macovei
Mihai
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
http://www.edpsciences.org/articles/epl/abs/2004/21/epl8421/epl8421.html
Magnetic and thermal influences on collective resonance fluorescence
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2005
2006-08-21 14:07:52.213294
© EDP Sciences 2004
oai:edoc.mpg.de:2048832005-07-0837:954
Article
Double-EIT ground-state laser cooling without blue-sideband heating
2004-10-01
370
376
Europhysics Letters
Europhys. Lett.
3
68
We discuss a laser cooling scheme for trapped atoms or ions which is based on double electromagnetically induced transparency (EIT) and makes use of a four-level atom in tripod configuration. The additional fourth atomic state is coupled by a strong-coupling laser field to the upper state of the usual three-level setup of single-EIT cooling. This effectively allows to create two EIT structures in the absorption spectrum of the system to be cooled, which may be controlled by the coupling laser field parameters to cancel both the carrier- and the blue-sideband excitations. In leading order of the Lamb-Dicke expansion, this suppresses all heating processes. As a consequence, the double-EIT scheme can be used to lower the cooling limit by a factor of order of the Lamb-Dicke parameter squared as compared to single-EIT cooling.
expertsonly
published
notspecified
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
http://www.edpsciences.org/articles/epl/abs/2004/21/epl8427/epl8427.html
Double-EIT ground-state laser cooling without blue-sideband heating
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2005
2005-07-08 10:29:04.532967
© EDP Sciences 2004
oai:edoc.mpg.de:2048842005-07-0837:954
Article
Positronium in Intense Laser Fields
2004-07-02
013601
Physical Review Letters
Phys. Rev. Lett.
1
93
The dynamics and radiation of positronium are investigated in intense laser fields. Our two-body quantum mechanical treatment displays the tunneling, free-evolution, and recollision dynamics of electron and positron in both the oscillating laser electric and laser magnetic field components. In spite of significant momentum transfer of the numerous incoming laser photons, recollisions of both particles are shown to occur automatically after tunneling ionization, along with substantial x-ray and gamma-ray emission during recombination and annihilation processes.
expertsonly
published
notspecified
B.
Henrich
Björn
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
http://link.aps.org/abstract/PRL/v93/e013601
Physikalisches Institut der Universität, Hermann-Herder Strasse 3, 79104 Freiburg, Germany
Positronium in Intense Laser Fields
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2005
2005-07-08 10:28:30.658928
©2004 The American Physical Society
oai:edoc.mpg.de:2048852005-07-0837:954
Article
Spontaneous-emission suppression via multiphoton quantum interference
2004-07-14
2771
2796
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B: At. Mol. Opt. Phys.
13
37
The spontaneous emission is investigated for an effective atomic two-level system in an intense coherent field with frequency lower than the vacuum-induced decay width. As this additional low-frequency field is assumed to be intense, multiphoton processes may be induced, which can be seen as alternative transition pathways in addition to the simple spontaneous decay. The interplay of the various interfering transition pathways influences the decay dynamics of the two-level system and may be used to slow down the spontaneous decay considerably. We derive from first principles an expression for the Hamiltonian including up to three-photon processes. This Hamiltonian is then applied to a quantum mechanical simulation of the decay dynamics of the two-level system. Finally, we discuss numerical results of this simulation based on a rubidium atom and show that the spontaneous emission in this system may be suppressed substantially.
expertsonly
published
notspecified
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
http://stacks.iop.org/0953-4075/37/2771
Spontaneous-emission suppression via multiphoton quantum interference
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2005
2005-07-08 10:28:04.332991
oai:edoc.mpg.de:2048862006-08-2137:954
Article
Bound atomic dynamics in the MeV regime
2004-07-14
L275
L283
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B: At. Mol. Opt. Phys.
13
37
The relativistic quantum dynamics of highly accelerated hydrogenic ions is investigated in the presence of a super intense counter-propagating laser pulse. Due to the large Doppler blue shift, collisions between electron and ionic core are shown to be possible in the MeV regime. This renders nuclear reactions feasible in the near future with single laser-driven ions.
expertsonly
published
notspecified
G. R.
Mocken
Guido Rudolf
C. H.
Keitel
Christoph Helmut
http://stacks.iop.org/0953-4075/37/L275
Bound atomic dynamics in the MeV regime
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2005
2006-08-21 14:07:16.040532
oai:edoc.mpg.de:2049252006-08-2137:954
Article
New Limits on the Drift of Fundamental Constants from Laboratory Measurements
2004-06-10
230802
Physical Review Letters
Phys. Rev. Lett.
23
92
We have remeasured the absolute 1S-2S transition frequency H in atomic hydrogen. A comparison with the result of the previous measurement performed in 1999 sets a limit of (–29±57) Hz for the drift of H with respect to the ground state hyperfine splitting Cs in 133Cs. Combining this result with the recently published optical transition frequency in 199Hg+ against Cs and a microwave 87Rb and 133Cs clock comparison, we deduce separate limits on /= (–0.9±2.9)×10–15 yr–1 and the fractional time variation of the ratio of Rb and Cs nuclear magnetic moments µRb/µCs equal to (–0.5±1.7)×10–15 yr–1. The latter provides information on the temporal behavior of the constant of strong interaction.
expertsonly
published
notspecified
M.
Fischer
M.
N.
Kolachevsky
Nikolai
M.
Zimmermann
Marcus
R.
Holzwarth
Ronald
T.
Udem
Thomas
T. W.
Hänsch
Theodor W.
M.
Abgrall
M.
J.
Grünert
J.
I.
Maksimovic
I.
S.
Bize
S.
H.
Marion
H.
F.
Pereira Dos Santos
F.
P.
Lemonde
P.
G.
Santarelli
G.
P.
Laurent
P.
A.
Clairon
A.
C.
Salomon
C.
M.
Haas
Martin
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
http://link.aps.org/abstract/PRL/v92/e230802
BNM-SYRTE, Observatoire de Paris, 61 Avenue de l'Observatoire, 75014 Paris, France
Laboratoire Kastler Brossel, ENS, 24 rue Lhomond, 75005 Paris, France
New Limits on the Drift of Fundamental Constants from Laboratory Measurements
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
MPI für Quantenoptik
2005
2006-08-21 14:06:32.380781
©2004 The American Physical Society
oai:edoc.mpg.de:2070852006-08-1837:954
Article
Relativistic and radiative corrections to the Mollow spectrum
English
2004-12-28
1
20
062111
Physical Review A
Phys. Rev. A
70
The incoherent inelastic part of the resonance fluorescence spectrum of a laser-driven atom is known as the Mollow spectrum [B. R. Mollow, Phys. Rev. 188, 1969 (1969)]. Starting from this level of description, we discuss theoretical foundations of high-precision spectroscopy using the resonance fluorescence light of strongly laser-driven atoms. Specifically, we evaluate the leading relativistic and radiative corrections to the Mollow spectrum, up to the relative orders of (Z)2 and (Z)2, respectively, and Bloch-Siegert shifts as well as stimulated radiative corrections involving off-resonant virtual states. Complete results are provided for the hydrogen 1S-2P1/2 and 1S-2P3/2 transitions; these include all relevant correction terms up to the specified order of approximation and could directly be compared to experimental data. As an application, the outcome of such experiments would allow for a sensitive test of the validity of the dressed-state basis as the natural description of the combined atom-laser system.
expertsonly
published
notspecified
J.
Evers
Jörg
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
http://link.aps.org/abstract/PRA/v70/e062111
Theoretische Quantendynamik, Physikalisches Institut der Albert-Ludwigs-Universität, Hermann-Herder-Straße 3, 79104 Freiburg im Breisgau, Germany
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2005
2006-08-18 16:59:44.318131
©2004 The American Physical Society
oai:edoc.mpg.de:2077022005-07-0837:954
Article
Time Reversal and Exceptional Points
English
2004-04-15
429
432
The European Physical Journal D
Eur. Phys. J. D
3
F. A. Gianturco and J.-M. Raimond
29
Eigenvectors of decaying quantum systems are studied at exceptional points of the Hamiltonian. Special attention is paid to the properties of the system under time reversal symmetry breaking. At the exceptional point the chiral character of the system - found for time reversal symmetry - generically persists. It is, however, no longer circular but rather elliptic.
expertsonly
published
notspecified
http://edoc.mpg.de/get.epl?fid=9978&did=207702&ver=0
H. L.
Harney
H. L.
W. D.
Heiss
W. D.
10.1140/epjd/e2004-00049-7
Department of Physics, University of Stellenbosch, 7602 Matieland, Südafrika
MPI für Kernphysik
Guest Groups and Emeriti
Theory of Chaos, Fields and Statistical Inference (H.A. Weidenmüller et al.)
2005
2005-07-08 10:27:29.467647
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2004
oai:edoc.mpg.de:2495302006-08-2137:954
Article
Relativistic and radiative energy shifts for Rydberg states
English
2005-01-05
S97
S105
Journal of Physics B
J. Phys. B
2
38
We investigate relativistic and quantum electrodynamic effects for highlyexcited bound states in hydrogen-like systems (Rydberg states). In particular, hydrogenic one-loop Bethe logarithms are calculated for all circular states
(l = n − 1) in the range 20 ≤ n ≤ 60 and successfully compared to an existing asymptotic expansion for large principal quantum number n. We provide accurate expansions of the Bethe logarithm for large values of n, for S, P and circular Rydberg states. These three expansions are expected to give any Bethe logarithm for principal quantum number n > 20 to an accuracy of five to seven decimal digits, within the specified manifolds of atomic states. Within the numerical accuracy, the results constitute unified, general formulae for quantum electrodynamic corrections whose validity is not restricted to a single atomic state. The results are relevant for accurate predictions of radiative shifts of Rydberg states and for the description of the recently investigatedlaser-dressed Lamb shift, which is observable in a strong coherent-wave light field
expertsonly
published
notspecified
U. D.
Jentschura
Ulrich David
E.-O.
Le Bigot
Eric-Olivier
J.
Evers
Jörg
P. J.
Mohr
Peter J.
C. H.
Keitel
Christoph Helmut
10.1088/0953-4075/38/2/008
Laboratoire Kastler Brossel, École Normale Supérieure et Université Pierre et Marie Curie, Case 74, 75005 Paris, France
National Institute of Standards and Technology, Mail Stop 8401, Gaithersburg, MD 20899-8401, USA
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-08-21 14:09:02.710047
IOP Publishing Ltd.
oai:edoc.mpg.de:2495332006-08-2137:954
Article
Coherent manipulation of collective three-level systems
English
2005-03-04
1
16
033802
Physical Review A
Phys. Rev. A
71
We investigate control schemes for the dynamics of a collection of dipole-interacting three-level atoms in V- or Λ- configuration. For this, we discuss the strong-field steady-state behavior of these systems under the influence of external parameters such as the relative phase between the two applied strong driving laser fields, the ratio of spontaneous decay and incoherent pumping rates, the splitting frequency between closely spaced atomic states, or a surrounding thermal bath. We show that these may act as convenient tools to sensitively control the collective dynamics of the atoms. As applications, we analyze the fluorescence and absorption properties of the atomic samples. Finally, we discuss the transient behavior to show that the presented schemes feature a rapid system evolution as required for many applications.
expertsonly
published
notspecified
M.
Macovei
Mihai
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.71.033802
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-08-21 14:09:34.648611
The American Physical Society
oai:edoc.mpg.de:2495642006-01-3137:954
Article
Emergence of Classical Orbits in Few-Cycle Above-Threshold Ionization of Atomic Hydrogen
English
2005-03-22
1
4
113001
Physical Review Letters
Phys. Rev. Lett.
11
94
The time-dependent Schrödinger equation for atomic hydrogen in few-cycle laser pulses is solved numerically. Introducing a positive definite quantum distribution function in energy-position space, a straightforward comparison of the numerical ab initio results with classical orbit theory is facilitated. Integration over position space yields directly the photoelectron spectra so that the various pathways contributing to a certain energy in the photoelectron spectra can be established in an unprecedented direct and transparent way.
expertsonly
published
notspecified
D.
Bauer
Dieter
10.1103/PhysRevLett.94.113001
MPI für Kernphysik
Group C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2006
2006-01-31 10:33:04.037392
The American Physical Society
oai:edoc.mpg.de:2495702006-01-3137:954
Article
Attosecond Probing of Vibrational Dynamics with High-Harmonic Generation
English
2005-02-11
1
4
053004
Physical Review Letters
Phys. Rev. Lett.
5
94
The numerical solution of the time-dependent Schrödinger equation for vibrating hydrogen molecules in few-cycle laser pulses shows that high-harmonic generation is sensitive to the laser-induced vibrational motion. More intense harmonics are generated in heavier isotopes, the difference increasing with the harmonic frequency. Analytical theory reveals a dependence of the harmonics on the vibrational autocorrelation function. With the help of a genetic algorithm, the nuclear motion can be reconstructed from the harmonic spectra with sub-fs time resolution.
expertsonly
published
notspecified
M.
Lein
Manfred
10.1103/PhysRevLett.94.053004
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
MPI für Physik Komplexer Systeme
2006
2006-01-31 10:39:32.950631
The American Physical Society
oai:edoc.mpg.de:2496492006-08-1837:954
Article
Radiative Corrections to Multi-Level Mollow-Type Spectra
English
37
45
Laser Physics
Las. Phys.
1
15
This paper is concerned with two rather basic phenomena: the incoherent fluorescence spectrum of an atom driven by an intense laser field and the coupling of the atom to the (empty) modes of the radiation field. The sum of the many-photon processes gives rise to the inelastic part of the atomic fluorescence, which, for a two-level system, has a well-known characteristic three-peak structure that is known as the Mollow spectrum. From a theoretical point of view, the Mollow spectrum finds a natural interpretation in terms of transitions among laser-dressed states that are the energy eigenstates of a second-quantized two-level system strongly coupled to a driving laser field. As was recently shown, the quasi-energies of the laser-dressed states receive radiative corrections, which are nontrivially different from the results that one would expect from an investigation of the coupling of the bare states to the vacuum modes. In this article, we briefly review the basic elements required for an analysis of the dynamic radiative corrections, and we generalize the treatment of the radiative corrections to the incoherent part of the steady-state fluorescence to a three-level system consisting of 1S, 3P, and 2S states.
published
notspecified
U. D.
Jentschura
Ulrich David
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
http://arxiv.org/abs/quant-ph/0501118
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006-08-18 17:14:43.917439
oai:edoc.mpg.de:2554112006-04-2637:954
Article
Radiation spectra of laser-driven quantum relativistic electrons
English
2005-01-18
171
190
Computer Physics Communications
Comp. Phys. Comm.
3
166
A procedure to calculate the radiation spectrum emitted by an arbitrarily prepared Dirac wave packet is developed. It is based on the Dirac charge current and classical electrodynamic theory. Apart from giving absolute intensity values, it is exact in terms of relativistic retardation effects and angular dependence. We employ a laser driven free electron to demonstrate the advantages of our method as compared to traditional ones that merely rely on the Fourier transform of the dipole operator's expectation value. Classical reference calculations confirm the results obtained for the low-frequency part of the spectrum, especially in terms of the observed red-shifts, which clearly deviate from non-relativistic calculations. In the high-frequency part of the spectrum, we note appreciable deviations to the purely classical calculations which may be linked to quantum averaging effects.
expertsonly
published
notspecified
G. R.
Mocken
Guido Rudolf
C. H.
Keitel
Christoph Helmut
10.1016/j.cpc.2004.12.002
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2006
2006-04-26 11:39:49.449827
Elsevier B.V.
oai:edoc.mpg.de:2554132006-04-2637:954
Article
Above-threshold ionization beyond the dipole approximation
English
2005-03-17
1
7
033408
Physical Review A
Phys. Rev. A
71
A generalization of the analytical theory of above-threshold ionization in the single active electron approximation is developed while taking into account leading non-dipole and relativistic corrections in the starting Hamiltonian. Special interest is placed on the high energy part of the photoelectron spectrum which consists of a plateau and a characteristic cutoff. It is shown that the correction due to the magnetic component of the laser field gives rise to a decrease of the plateau height, an increase of the maximal cutoff energy, and a drift of the emitted electrons in propagation direction of the laser field. Furthermore, the influence of the relativistic mass shift may become non-neglible by reducing the cutoff energy significantly. Spin effects or the Zitterbewegung play a comparably minor role in the investigated parameter regime of suboptical frequencies and high but not ultra-high laser intensities.
expertsonly
published
notspecified
M.
Klaiber
Michael
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.71.033408
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2006
2006-04-26 11:42:25.383436
The American Physical Society
oai:edoc.mpg.de:2554162006-04-2637:954
Article
Multiphoton quantum interference on a dipole-forbidden transition
English
2005-02-07
L69
L77
Journal of Physics B
J. Phys. B
4
38
We investigate the effect of an intense low-frequency field on the population decay of an excited two-level atom, where the two states are connected by a dipole-forbidden transition. In addition to the natural two-photon spontaneous decay, the low-frequency field gives rise to induced two-photon processes, where one of the two photons is spontaneous. Due to the low frequency of the applied field, the induced decay pathways may interfere with each other. We show how varying the parameters of the applied field allows switching between constructive and destructive interference, thereby increasing or decreasing the induced transition rate as compared to the rate without interference. As all relevant competing transitions are of the same multiphoton order, the system is a promising candidate to verify the idea of spontaneous-emission interference induced by multiphoton pathways experimentally.
expertsonly
published
notspecified
U.
Akram
Uzma
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1088/0953-4075/38/4/L01
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006-04-26 11:45:10.414215
© 2005 IOP Publishing Ltd
oai:edoc.mpg.de:2554232006-08-2137:954
Article
Analytical Approach to Wave Packet Dynamics of Laser-Driven Particles beyond the Dipole Approximation
English
2005
529
535
Laser Physics
Las. Phys.
4
15
An analytical approach to quantum mechanical wave packet dynamics of laser-driven particles is presented. The time-dependent Schroedinger equation is solved for an electron exposed to a linearly polarized plane wave of arbitrary shape. The calculation goes beyond the dipole approximation, such that magnetic field effects like wave packet shearing are included. Analytical expressions for the time-dependent widths of the wave packet and its orientation are established. These allow for a simple understanding of the wave packet dynamics.
expertsonly
published
notspecified
M.
Verschl
Mario
C. H.
Keitel
Christoph Helmut
http://arxiv.org/abs/quant-ph/0504181
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2006
2006-08-21 11:45:01.786725
oai:edoc.mpg.de:2554302006-08-2137:954
Article
Some recent advances in bound-state quantum electrodynamics
English
2005-05-12
375
386
Canadian Journal of Physics
Can. J. Phys.
4
83
We discuss recent progress in various problems related to bound-state quantum electrodynamics: the bound-electron g factor, two-loop self-energy corrections, and the laser-dressed Lamb shift. The progress relies on various advances in the bound-state formalism, including ideas inspired by effective field theories such as nonrelativistic quantum electrodynamics. Radiative corrections in dynamical processes represent a promising field for further investigations.
expertsonly
published
notspecified
U. D.
Jentschura
Ulrich David
J.
Evers
Jörg
10.1139/P05-018
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-08-21 14:10:15.320078
© 2005 NRC Canada
oai:edoc.mpg.de:2555672006-04-2737:954
Article
Low-frequency-field-induced spontaneous-emission interference in a two-level atom placed in an anisotropic photonic crystal
English
2005-05-03
1435
1451
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B-At. Mol. Opt. Phys.
10
38
We investigate the spontaneous-emission properties of a two-level atom embedded in a three-dimensional anisotropic photonic crystal. In addition to the modified density of states, the atom is driven by a coherent intense low-frequency field (LFF), which creates additional multiphoton decay channels with the exchange of two low-frequency photons and one spontaneous photon during an atomic transition. Due to the low frequency of the applied field, the various transition pathways may interfere with each other and thus give rise to a modified system dynamics. We find that even if all the atomic (bare and induced) transition frequencies are in the conducting band of the photonic crystal, there still may exist a photon–atom bound state in coexistence with propagating modes. The system also allows us to generate narrow lines in the spontaneous-emission spectrum. This spectrum is a function of the distance of the observer from the atom due to the band gap in the photonic crystal. The system properties depend on three characteristic frequencies, which are influenced by quantum interference effects. Thus these results can be attributed to a combination of interference and band-gap effects.
expertsonly
published
joureview
G.-x.
Li
Gao-xiang
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
000230374500012
0953-4075
Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-04-27 10:48:06.330968
IOP Publ.
oai:edoc.mpg.de:2555772006-04-2737:954
Article
Self-energy values for P states in hydrogen and low-Z hydrogenlike ions
English
2005-07
1
3
014103
Physical Review A
Phys. Rev. A
1
72
We describe a nonperturbative (in Zalpha) numerical evaluation of the one-photon electron self-energy for 3P1/2, 3P3/2, 4P1/2, and 4P3/2 states in hydrogenlike atomic systems with charge numbers Z=1 to 5. The numerical results are found to be in agreement with known terms in the expansion of the self-energy in powers of Zalpha and lead to improved theoretical predictions for the self-energy shift of these states.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
P. J.
Mohr
Peter J.
000230887300158
1050-2947
Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 10:50:28.813085
©2005 The American Physical Society
oai:edoc.mpg.de:2557852006-04-2737:954
Article
Calculation of hydrogenic Bethe logarithms for Rydberg states
English
2005-07
1
9
012110
Physical Review A
Phys. Rev. A
1
72
We describe the calculation of hydrogenic (one-loop) Bethe logarithms for all states with principal quantum numbers n<=200. While, in principle, the calculation of the Bethe logarithm is a rather easy computational problem involving only the nonrelativistic (Schrödinger) theory of the hydrogen atom, certain calculational difficulties affect highly excited states, and in particular states for which the principal quantum number is much larger than the orbital angular momentum quantum number. Two evaluation methods are contrasted. One of these is based on the calculation of the principal value of a specific integral over a virtual photon energy. The other method relies directly on the spectral representation of the Schrödinger–Coulomb propagator. Selected numerical results are presented. The full set of values is available at arXiv.org/quant-ph/0504002.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
P. J.
Mohr
Peter J.
000230887300023
1050-2947
Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 10:52:56.454004
APS
oai:edoc.mpg.de:2557872006-04-2737:954
Article
Thin crystal layers in superstrong laser fields: Dynamics and coherent x-ray generation
English
2005-08
1
15
023812
Physical Review A
Phys. Rev. A
2
72
Coherent x-ray generation is investigated for a thin solid layer or any other periodic atomic structure with limited dimensions exposed to a short, superintense laser pulse. We single out a selective range of parameters at which the impact of nonlinear collective processes on ion dynamics is reduced. This allows us to consider an ionic structure that is quasiregular during the brief interaction, which we prove also by particle-in-cell simulations. In the relativistic regimes of the interaction, when the transversal oscillation amplitude of the electron in the laser field exceeds the layer transversal width, the multiphoton scattering of electrons dominates over recombination to bound states. Electrons accelerated by the laser field penetrate through the periodic ionic structure, emitting coherent bremsstrahlung. Hard x rays are shown to amplify along the interaction length due to stimulated coherent bremsstrahlung. The high gain of the scheme compensates for the short interaction length, yielding a gain-length product competitive with other coherent x-ray sources. Limitations on the gain due to the energy spread of the electrons and the short time of the interaction are estimated.
expertsonly
published
joureview
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
000231564200184
1050-2947
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2006
2006-04-27 10:55:40.852261
APS
oai:edoc.mpg.de:2557882006-04-2737:954
Article
Strong-field approximation for intense-laser-atom processes: The choice of gauge
English
2005-08
1
5
023415
Physical Review A
Phys. Rev. A
2
72
The strong-field approximation (SFA) can be and has been applied in both length gauge and velocity gauge with quantitatively conflicting answers. For ionization of negative ions with a ground state of odd parity, the predictions of the two gauges differ qualitatively: in the envelope of the angular-resolved energy spectrum, dips in one gauge correspond to humps in the other. We show that the length-gauge SFA matches the exact numerical solution of the time-dependent Schrödinger equation.
expertsonly
published
joureview
D.
Bauer
Dieter
D. B.
Milosevic
D. B.
W.
Becker
W.
000231564200144
1050-2947
Univ Sarajevo, Fac Sci, Sarajevo 71000, Bosnia & Herceg.; Max Born Inst, D-12489 Berlin, Germany.
MPI für Kernphysik
Group C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2006
2006-04-27 10:57:23.173735
APS
oai:edoc.mpg.de:2557892006-04-2737:954
Article
Renormalization-group analysis of layered sine-Gordon type models
English
2005-10-10
467
492
Nuclear Physics B
Nucl. Phys. B
3
725
We analyze the phase structure and the renormalization group (RG) flow of the generalized sine-Gordon models with nonvanishing mass terms, using the Wegner–Houghton RG method in the local potential approximation. Particular emphasis is laid upon the layered sine-Gordon (LSG) model, which is the bosonized version of the multi-flavour Schwinger model and approaches the sum of two “normal”, massless sine-Gordon (SG) models in the limit of a vanishing interlayer coupling J. Another model of interest is the massive sine-Gordon (MSG) model. The leading-order approximation to the UV (ultraviolet) RG flow predicts two phases for the LSG as well as for the MSG, just as it would be expected for the SG model, where the two phases are known to be separated by the Coleman fixed point. The presence of finite mass terms (for the LSG and the MSG) leads to corrections to the UV RG flow, which are naturally identified as the “mass corrections”. The leading-order mass corrections are shown to have the following consequences: (i) for the MSG model, only one phase persists, and (ii) for the LSG model, the transition temperature is modified. Within the mass-corrected UV scaling laws, the limit of J→0 is thus nonuniform with respect to the phase structure of the model. The modified phase structure of general massive sine-Gordon models is connected with the breaking of symmetries in the internal space spanned by the field variables. For the LSG, the second-order subleading mass corrections suggest that there exists a cross-over regime before the IR scaling sets in, and the nonlinear terms show explicitly that higher-order Fourier modes appear in the periodic blocked potential.
renormalization group evolution of parameters; renormalization
expertsonly
published
joureview
I.
Nandori
István
S.
Nagy
S.
K.
Sailer
K.
U. D.
Jentschura
Ulrich David
000232183500002
0550-3213
Hungarian Acad Sci, Inst Nucl Res, H-4001 Debrecen, Hungary.; Debrecen Univ Med, Dept Theoret Phys, H-4012 Debrecen, Hungary.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 11:01:22.660158
Elsevier
oai:edoc.mpg.de:2559722006-04-2737:954
Article
Techniques in analytic Lamb shift calculations
English
2005-09-28
2261
2276
Modern Physics Letters A
Mod. Phys. Lett. A
30
20
Quantum electrodynamics has been the first theory to emerge from the ideas of regularization and renormalization, and the coupling of the fermions to the virtual excitations of the electromagnetic field. Today, bound-state quantum electrodynamics provides us with accurate theoretical predictions for the transition energies relevant to simple atomic systems, and steady theoretical progress relies on advances in calculational techniques, as well as numerical algorithms. In this brief review, we discuss one particular aspect connected with the recent progress: the evaluation of relativistic corrections to the one-loop bound-state self-energy in a hydrogenlike ion of low nuclear charge number, for excited non-S states, up to the order of alpha (Zalpha)^6 in units of the electron mass. A few details of calculations formerly reported in the literature are discussed, and results for 6F, 7F, 6G and 7G states are given.
quantum electrodynamics; bound states; atomic physics
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
000232501500001
0217-7323
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 13:26:56.475225
oai:edoc.mpg.de:2559732006-04-2737:954
Article
Isospin dependence in the odd-even staggering of nuclear binding energies
English
2005-07-22
1
4
042501
Physical Review Letters
Phys. Rev. Lett.
4
95
The FRS-ESR facility at GSI provides unique conditions for precision measurements of large areas on the nuclear mass surface in a single experiment. Values for masses of 604 neutron-deficient nuclides (30<=Z<=92) were obtained with a typical uncertainty of 30 µu. The masses of 114 nuclides were determined for the first time. The odd-even staggering (OES) of nuclear masses was systematically investigated for isotopic chains between the proton shell closures at Z=50 and Z=82. The results were compared with predictions of modern nuclear models. The comparison revealed that the measured trend of OES is not reproduced by the theories fitted to masses only. The spectral pairing gaps extracted from models adjusted to both masses, and density related observables of nuclei agree better with the experimental data.
expertsonly
published
joureview
Y. A.
Litvinov
Y. A.
T. J.
Burvenich
Thomas Josef
H.
Geissel
H.
Y. N.
Novikov
Y. N.
Z.
Patyk
Z.
C.
Scheidenberger
C.
F.
Attallah
F.
G.
Audi
G.
K.
Beckert
K.
F.
Bosch
F.
M.
Falch
M.
B.
Franzke
B.
M.
Hausmann
M.
T.
Kerscher
T.
O.
Klepper
O.
H. J.
Kluge
H. J.
C.
Kozhuharov
C.
K. E. G.
Lobner
K. E. G.
D. G.
Madland
D. G.
J. A.
Maruhn
J. A.
G.
Munzenberg
G.
F.
Nolden
F.
T.
Radon
T.
M.
Steck
M.
S.
Typel
S.
H.
Wollnik
H.
000230680000022
0031-9007
Gesell Schwerionenforsch GSI, D-64291 Darmstadt, Germany.; JLU Giessen, Inst Phys 2, D-35392 Giessen, Germany.; Los Alamos Natl Lab, Los Alamos, NM 87545 USA.; St Petersburg Nucl Phys Inst, Gatchina 188350, Russia.; Soltan Inst Nucl Studies, PL-00681 Warsaw, Poland.; CNRS, IN2P3, CSNSM, F-91405 Orsay, France.; LMU Munchen, Sekt Phys, D-85748 Garching, Germany.; JWGU Frankfurt, Inst Theoret Phys, D-60054 Frankfurt, Germany.
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-04-27 13:30:33.159439
The American Physical Society
oai:edoc.mpg.de:2559822006-04-2737:954
Article
Rapid refractive index enhancements via laser-mediated collectivity
English
2005-10-14
L315
L321
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B-At. Mol. Opt. Phys.
19
38
The collective interaction via the environmental vacuum is investigated for a mixture of two different multi-atom ensembles in a moderately intense laser field. Due to the numerous inter-atomic couplings, the laser-dressed system may react sensitively and rapidly with respect to changes in the atomic and laser parameters. We show for weak probe fields that in the absence of absorption both the index of refraction and the group velocity may be modified strongly and rapidly due to the collectivity.
expertsonly
published
joureview
M.
Macovei
Mihai
C. H.
Keitel
Christoph Helmut
000233812600002
0953-4075
Tech Univ Moldova, Dept Phys, MD-2004 Kishinev, Moldova.
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-04-27 13:35:08.711811
IOP
oai:edoc.mpg.de:2559982006-04-2737:954
Article
Attosecond double-slit experiment
English
2005-07-22
1
4
040401
Physical Review Letters
Phys. Rev. Lett.
4
95
A new scheme for a double-slit experiment in the time domain is presented. Phase-stabilized few-cycle laser pulses open one to two windows (slits) of attosecond duration for photoionization. Fringes in the angle-resolved energy spectrum of varying visibility depending on the degree of which-way information are measured. A situation in which one and the same electron encounters a single and a double slit at the same time is observed. The investigation of the fringes makes possible interferometry on the attosecond time scale. From the number of visible fringes, for example, one derives that the slits are extended over about 500 as.
expertsonly
published
joureview
F.
Lindner
F.
M. G.
Schatzel
M. G.
H.
Walther
H.
A.
Baltuska
A.
E.
Goulielmakis
E.
F.
Krausz
F.
D. B.
Milosevic
D. B.
D.
Bauer
Dieter
W.
Becker
W.
G. G.
Paulus
G. G.
000230680000001
0031-9007
Univ Munich, D-85748 Garching, Germany.; Tech Univ Vienna, Inst Photon, A-1040 Vienna, Austria.; Univ Sarajevo, Fac Sci, Sarajevo 71000, Bosnia & Herceg.; Max Born Inst, D-12489 Berlin, Germany.; Texas A&M Univ, Dept Phys, College Stn, TX 77843 USA.
MPI für Kernphysik
Group C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
MPI für Quantenoptik
2006
2006-04-27 13:38:11.229981
The American Physical Society
oai:edoc.mpg.de:2560032006-04-2737:954
Article
Complete two-loop correction to the bound-electron g factor
English
2005-08
1
11
022108
Physical Review A
Phys. Rev. A
2
72
Within a systematic approach based on dimensionally regularized nonrelativistic quantum electrodynamics, we derive a complete result for the two-loop correction to order (alpha/pi)2(Zalpha)4 for the g factor of an electron bound in an nS state of a hydrogenlike ion. The results obtained significantly improve the accuracy of the theoretical predictions for the hydrogenlike carbon and oxygen ions and influence the value of the electron mass inferred from g-factor measurements.
expertsonly
published
joureview
K.
Pachucki
K.
A.
Czarnecki
A.
U. D.
Jentschura
Ulrich David
V. A.
Yerokhin
Vladimir A.
000231564200027
1050-2947
Univ Warsaw, Inst Theoret Phys, PL-00681 Warsaw, Poland.; Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada.; St Petersburg State Univ, Dept Phys, St Petersburg 198504, Russia.; St Petersburg State Polytech Univ, Ctr Adv Studies, St Petersburg 195251, Russia.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 13:42:37.64618
The American Physical Society
oai:edoc.mpg.de:2566542006-04-2737:954
Article
Precise calculation of transition frequencies of hydrogen and deuterium based on a least-squares analysis
English
2005-10-14
1
4
163003
Physical Review Letters
Phys. Rev. Lett.
16
95
We combine a limited number of accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics (QED) calculations, and, as an essential additional ingredient, a generalized least-squares analysis, to obtain precise and optimal predictions for hydrogen and deuterium transition frequencies. Some of the predicted transition frequencies have relative uncertainties more than an order of magnitude smaller than that of the g factor of the electron, which was previously the most accurate prediction of QED.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
S.
Kotochigova
Svetlana
E.-O.
Le Bigot
Eric-Olivier
P. J.
Mohr
Peter J.
B. N.
Taylor
Barry N.
000232558400020
0031-9007
NIST, Gaithersburg, MD 20899 USA.; Univ Paris 06, Lab Kastler Brossel, Ecole Normale Super, F-75005 Paris, France.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 13:44:37.782682
The American Physical Society
oai:edoc.mpg.de:2566562006-04-2737:954
Article
Calculation of the one- and two-loop lamb shift for arbitrary excited hydrogenic states
English
2005-10-28
1
4
180404
Physical Review Letters
Phys. Rev. Lett.
18
95
General expressions for quantum electrodynamic corrections to the one-loop self-energy [of order alpha(Zalpha)6] and for the two-loop Lamb shift [of order alpha2(Zalpha)6] are derived. The latter includes all diagrams with closed fermion loops. The general results are valid for arbitrary excited non-S hydrogenic states and for the normalized Lamb shift difference of S states, defined as Deltan=n3DeltaE(nS)-DeltaE(1S). We present numerical results for one-loop and two-loop corrections for excited S, P, and D states. In particular, the normalized Lamb shift difference of S states is calculated with an uncertainty of order 0.1 kHz.
expertsonly
published
joureview
A.
Czarnecki
A.
U. D.
Jentschura
Ulrich David
K.
Pachucki
K.
000232887400004
0031-9007
Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada.; Univ Warsaw, Inst Theoret Phys, PL-00681 Warsaw, Poland.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-04-27 13:47:00.388508
The American Physical Society
oai:edoc.mpg.de:2566622006-05-0237:954
Article
Laser-dressed vacuum polarization in a Coulomb field
English
2005-11
1
12
052104
Physical Review A
Phys. Rev. A
5
72
We investigate quantum electrodynamic effects under the influence of an external, time-dependent electromagnetic field, which mediates dynamic modifications of the radiative corrections. Specifically, we consider the quantum electrodynamic vacuum-polarization tensor under the influence of two external background fields: a strong laser field and a nuclear Coulomb field. We calculate the charge and current densities induced by a nuclear Coulomb field in the presence of a laser field. We find the corresponding induced scalar and vector potentials. The induced potential, in first-order perturbation theory, leads to a correction to atomic energy levels. The external laser field breaks the rotational symmetry of the system. Consequently, the induced charge density is not spherically symmetric, and the energy correction therefore leads to a "polarized Lamb shift." In particular, the laser generates an additional potential with a quadrupole moment. The corresponding laser-dressed vacuum-polarization potential behaves like 1/r3 at large distances, unlike the Uehling potential, which vanishes exponentially for large r. The energy corrections are of the same order of magnitude for hydrogenic levels, irrespective of the angular momentum quantum number. The induced current leads to a transition dipole moment which oscillates at the second harmonic of the laser frequency and is mediated by second-order harmonic generation in the vacuum-polarization loop. In the far field, at distances r>>1/omega from the nucleus (omega is the laser frequency), the laser induces mutually perpendicular electric and magnetic fields, which give rise to an energy flux that corresponds to photon fusion leading to the generation of real photons, again at the second harmonic of the laser. Our investigation might be useful for other situations where quantum field theoretic phenomena are subjected to external fields of a rather involved structure.
expertsonly
published
joureview
A. I.
Milstein
Alexander I.
I. S.
Terekhov
Ivan S.
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
000233603400027
1050-2947
Budker Inst Nucl Phys, Novosibirsk 630090, Russia.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-05-02 14:06:26.592876
©2005 The American Physical Society
oai:edoc.mpg.de:2566652006-05-0237:954
Article
Relativistic electron correlation, quantum electrodynamics, and the lifetime of the 1s(2)2s(2)2p P-2(3/2)o level in boronlike argon
English
2005-10-28
1
4
183001
Physical Review Letters
Phys. Rev. Lett.
18
95
The lifetime of the Ar13+ 1s22s22p 2P<sub>3/2</sub><sup>o</sup> metastable level was determined at the Heidelberg Electron Beam Ion Trap to be 9.573(4)(5) ms(stat)(syst). The accuracy level of one per thousand makes this measurement sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM) and to relativistic electron-electron correlation effects like the frequency-dependent Breit interaction. Theoretical predictions, adjusted for the EAMM, cluster about a lifetime that is approximately 3sigma shorter than our experimental result.
expertsonly
published
joureview
A.
Lapierre
Alain
U. D.
Jentschura
Ulrich David
J. R.
Crespo Lopez-Urrutia
José R.
J.
Braun
Johannes
G.
Brenner
Günter
H.
Bruhns
Hjalmar
D.
Fischer
Daniel
A. J.
Gonzalez Martinez
Antonio J.
Z.
Harman
Zoltan
W. R.
Johnson
W. R.
C. H.
Keitel
Christoph Helmut
V.
Mironov
Vladimir
C. J.
Osborne
Christopher J.
G.
Sikler
Günter
R.
Soria Orts
Rosario
V.
Shabaev
V.
H.
Tawara
Hiroyuki
I. I.
Tupitsyn
Ilya I.
J.
Ullrich
Joachim
A.
Volotka
A.
000232887400023
0031-9007
Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA.; Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA.; St Petersburg State Univ, Dept Phys, St Petersburg 198504, Russia.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006-05-02 14:09:55.144151
©2005 The American Physical Society
oai:edoc.mpg.de:2566722006-05-0237:954
Article
Harmonic generation from laser-driven vacuum
English
2005-10
1
23
085005
Physical Review D
Phys. Rev. D
8
72
We investigate the feasibility that, in the field of a superstrong standing laser wave, high-order harmonics of the pumping laser are generated from vacuum. Analytical calculations employing adiabatic perturbation theory show that, for laser electric fields larger than Ecr=m2c3/[h-bar]e=1.3×1016 V/cm, high-order harmonics are generated. The harmonic spectrum shows a wide plateau followed by a cutoff. The cutoff starts approximately at photon energies [h-bar]omegaM~sqrt([h-bar]ecE[sub L]), with EL being the amplitude of the laser field. In the opposite limit EL<<Ecr, the emission of high harmonics is very unlikely. In this case, a feasibility analysis for the experimental observation of the photon-photon scattering process using x-ray free electron lasers shows that the requirements are much less restrictive than those required to observe electron-positron pair creation.
notspecified
published
joureview
A.
Di Piazza
Antonino
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
000232936700068
1550-7998
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2006
2006-05-02 14:11:36.310038
©2005 The American Physical Society
oai:edoc.mpg.de:2566732006-08-2137:954
Article
Free-electron quantum signatures in intense laser fields
English
2005-09
1
7
033402
Physical Review A
Phys. Rev. A
3
72
Quantum signatures of a free electron in interaction with a continuous-wave radiation field are investigated by looking for negativities in the Wigner function of the system. The free-electron wave function in the radiation field is calculated fully analytically by solving the appropriate Schrödinger equation in the Krammers-Henneberger frame. It is found that pronounced quantum signatures show up already for a laser peak field of magnitude E0=1–2 a.u. and a frequency omega=1 a.u. However, the nonclassical behavior gets lost if the interaction with the radiation field is taken in the dipole approximation.
expertsonly
published
joureview
M.
Mahmoudi
Mohammad
Y. I.
Salamin
Yousef I.
C. H.
Keitel
Christoph Helmut
000232228300113
1050-2947
Univ Freiberg, Phys Inst, D-79104 Freiberg, Germany.; Zanjan Univ, Phys Dept, Zanjan, Iran.; American Univ, Phys Dept, Sharjah, U Arab Emirates.
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006
2006-08-21 14:10:50.834201
©2005 The American Physical Society
oai:edoc.mpg.de:2566752006-03-2037:954
Article
Phase-dependent interference mechanisms in a three-level Lambda system driven by a quantized laser field
English
2005-12-15
2699
2712
Journal of Modern Optics
J. Mod. Opt.
18
52
The dynamics of an atomic few-level system can depend on the phase of driving fields coupled to the atom if certain conditions are satisfied. This is of particular interest to control interference effects, which can alter the system properties considerably. In this article, we discuss the mechanisms of such phase control and interference effects in an atomic three-level system in the ? configuration, where the upper state spontaneously decays into the two lower states. The lower states are coupled by a driving field, which we treat as quantized. This allows for an interpretation on the single photon level for both the vacuum and the driving field. By analysing the system behaviour for a driving field initially in non-classical states with only a few Fock number states populated, we find that even though the driving field is coupled to the lower states only, it induces a multiplet of upper states. Then interference occurs independently in three-level subsystems in the V configuration, each formed by two adjacent upper states and a single dressed lower state.
Automatic journal name synchronization
notspecified
published
joureview
J.
Evers
Jörg
000234126700008
0950-0340
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-03-20 12:03:26.339433
© 2005 Taylor & Francis
oai:edoc.mpg.de:2566772006-05-0237:954
Article
Mechanisms of ultrahigh-order harmonic generation
English
2005-11
1
4
053816
Physical Review A
Phys. Rev. A
5
72
We analyze mechanisms of high-order harmonic generation from two-center molecules at large internuclear separations in linearly polarized laser fields. Since laser-driven electrons acquire instantaneous kinetic energies of up to 8 times the ponderomotive potential Up, recombination at an appropriately placed nucleus leads to ultrahigh-order harmonic emission [P. Moreno, L. Plaja, and L. Roso, Phys. Rev. A 55, R1593 (1997)]. By solving the time-dependent Schrödinger equation for model systems, we show that this mechanism is only efficient if the single-particle orbital of the electron is coherently delocalized over the two potential wells. This is realized in the ground state of a one-electron molecular ion. In a neutral molecule or in a molecular ion created by ionization of a neutral molecule at large internuclear distance, the coherence is destroyed by electron-electron correlation.
expertsonly
published
joureview
M.
Lein
Manfred
000233603400182
1050-2947
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2006
2006-05-02 14:22:58.992814
©2005 The American Physical Society
oai:edoc.mpg.de:2566782006-05-0237:954
Article
Quantum correlations of an atomic ensemble via an incoherent bath
English
2005-12
1
5
063809
Physical Review A
Phys. Rev. A
6
72
A rich variety of quantum features can be found in a collection of atoms driven only by an incoherent bath. To demonstrate this, we discuss a sample of three-level atoms in ladder configuration interacting via the surrounding bath, and show that the fluorescence light emitted by this system exhibits nonclassical properties. Realizations could be thermal baths for microwave transitions, or incoherent broadband fields for optical transitions. In a small sample of atoms, the emitted light can be switched from sub- to super-Poissonian and from antibunching to superbunching controlled by the mean number of atoms in the sample. Larger samples allow us to generate superbunched light over a wide range of bath parameters and thus fluorescence light intensities. We also identify parameter ranges where the fields emitted on the two transitions are strongly correlated or anticorrelated, such that the Cauchy-Schwarz inequality is violated. As in a moderately strong bath this violation occurs also for larger numbers of atoms, such samples exhibit macroscopic quantum effects.
notspecified
published
joureview
M.
Macovei
Mihai
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
000234334900138
1050-2947
Tech Univ Moldova, Dept Phys, Kishinev, Moldova.
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006
2006-05-02 14:24:16.782315
©2005 The American Physical Society
oai:edoc.mpg.de:2566802008-03-0337:954
Article
Comparison of classical and second quantized description of the dynamic Stark shift
English
2006-01
77
81
American Journal of Physics
Am. J. Phys.
1
74
We compare the derivation of the dynamic Stark shift of hydrogenic energy levels in a classical framework with an adiabatically damped laser-atom interaction, which is equivalent to the Gell-Mann-Low-Sucher formula, and a treatment based on time-independent perturbation theory, with a second-quantized laser-atom dipole interaction Hamiltonian. Our analysis applies to a laser that excites a two-photon transition in atomic hydrogen or in a hydrogenlike ion with low nuclear charge number. Our comparisons serve to demonstrate why the dynamic Stark shift may be interpreted as a stimulated radiative correction and illustrates connections between the two derivations. The simplest of the derivations is the fully quantized approach. The classical and the second-quantized treatment are shown to be equivalent in the limit of large photon numbers.
notspecified
published
joureview
M.
Haas
Martin
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
000234468400013
0002-9505
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 16:09:40.94985
©2006 American Association of Physics Teachers
oai:edoc.mpg.de:2566832006-05-0337:954
Article
High-order harmonic generation in vibrating molecules
English
2006-01-20
113
124
Journal of Modern Optics
J. Mod. Opt.
1-2
53
The generation of high-order harmonics in small diatomic molecules is theoretically investigated with inclusion of the vibrational degree of freedom. The results obtained from the solution of the time-dependent Schrödinger equation for a model H2 molecule are interpreted by analysing the influence of the vibrational motion in the framework of the strong-field approximation. Ionization launches a vibrational wave packet whose motion is correlated with the motion of the continuum electron wave packet. The harmonics are sensitive to a correlation function quantifying the overlap between the vibrational wave packet at the time of recombination and a vibrational target wave packet, i.e. the wave packet for which de-excitation into the ground state is most likely. We show that more intense harmonics are generated in heavier isotopes due to the slower nuclear motion.
expertsonly
published
notspecified
C. C.
Chirila
Ciprian C.
M.
Lein
Manfred
10.1080/09500340500233636
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2006-05-03 13:24:16.463559
oai:edoc.mpg.de:2566842007-09-1937:954
Article
Quantum-orbit theory of high-order atomic processes in intense laser fields
English
2006-01-20
125
134
Journal of Modern Optics
J. Mod. Opt.
1-2
53
The quantum-orbit formalism of high-order atomic processes in a strong laser field is presented starting from the strong-field approximation generalized to include higher-order effects. It is shown how to apply the quantum-orbit theory to various processes such as high-order above-threshold ionization and detachment, high-order harmonic generation, laser-assisted X-ray–atom scattering, laser-assisted electron–ion recombination, laser-assisted electron–atom scattering and non-sequential double ionization. Particular attention is devoted to high-order above-threshold ionization by few-cycle laser pulses. The results obtained using the strong-field approximation and the theory of quantum orbits are compared with the ab initio solution of the time-dependent Schrödinger equation. It is shown that Coulomb effects are important for low-energy electron spectra.
expertsonly
published
notspecified
D. B.
Milosevic
D. B.
D.
Bauer
Dieter
W.
Becker
W.
10.1080/09500340500186099
Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo, Bosnia and Hercegovina
Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-19 13:46:57.166463
oai:edoc.mpg.de:2566912006-05-0337:954
Article
Quantum Interference Enforced by Time-Energy Complementarity
English
2006-03-14
1
4
100403
Physical Review Letters
Phys. Rev. Lett.
10
96
The interplay of the concepts of complementarity and interference in the time-energy domain are studied. In particular, we theoretically investigate the fluorescence light from a J=1/2 to J=1/2 transition that is driven by a monochromatic laser field. We find that the spectrum of resonance fluorescence exhibits a signature of vacuum-mediated interference effects, whereas the total intensity is not affected by interference. We demonstrate that this result is a consequence of the principle of complementarity, applied to time and energy. Since the considered level scheme can be found, e.g., in 198Hg+ ions, our model system turns out to be an ideal candidate to provide evidence for as yet experimentally unconfirmed vacuum-induced atomic coherences.
expertsonly
published
joureview
M.
Kiffner
Martin
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevLett.96.100403
http://link.aps.org/abstract/PRL/v96/e100403
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-05-03 13:27:03.903222
©2006 The American Physical Society
oai:edoc.mpg.de:2567202007-09-1937:954
Article
On the validity of the strong field approximation and simple man's theory
English
2006-01-20
135
147
Journal of Modern Optics
J. Mod. Opt.
1-2
53
Few-cycle above-threshold ionization spectra of atomic hydrogen, calculated via the numerical solution of the time-dependent Schrödinger equation (TDSE), are compared with those predicted by the strong field approximation. Good agreement is obtained for the energetic, rescattered photoelectrons whereas the low-energy part of the electron spectra differ significantly. The latter disagreement is shown to originate from the long-range character of the Coulomb potential. In the second part of the paper a novel quantum distribution function is introduced, which facilitates a direct comparison of the classical electron orbits used in simple man's theory with the exact numerical TDSE result. It is shown that well localized electron wave packets emerge, oriented along the simple man's classical trajectories as the energy resolution in the quantum distribution function is reduced.
expertsonly
published
notspecified
D.
Bauer
Dieter
D. B.
Milosevic
D. B.
W.
Becker
W.
10.1080/09500340500217258
Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo, Bosnia and Herzegovina
Max-Born-Institut, Max-Born-Str. 2a, 12489 Berlin, Germany
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-19 13:48:00.259197
© 2006 Taylor & Francis
oai:edoc.mpg.de:2570752006-05-0337:954
Article
Measurement of the separation between atoms beyond diffraction limit
English
2006-03-10
1
4
031803
Physical Review A
Phys. Rev. A
3
73
Precision measurement of small separations between two atoms or molecules has been of interest since the early days of science. Here, we discuss a scheme which yields spatial information on a system of two identical atoms placed in a standing wave laser field. The information is extracted from the collective resonance fluorescence spectrum, relying entirely on far-field imaging techniques. Both the interatomic separation and the positions of the two particles can be measured with fractional-wavelength precision over a wide range of distances from about λ/550 to λ/2.
expertsonly
published
joureview
J. T.
Chang
Jun Tao
J.
Evers
Jörg
M. O.
Scully
Marlan Orvil
M. S.
Zubairy
Muhammad Suhail
10.1103/PhysRevA.73.031803
http://link.aps.org/abstract/PRA/v73/e031803
Institute for Quantum Studies and Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA
Princeton Institute for Materials Research, Princeton University, Princeton, NJ 08544-1009, USA
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-05-03 13:29:30.009335
©2006 The American Physical Society
oai:edoc.mpg.de:2846472007-09-1837:954
Article
Above-threshold ionization by few-cycle pulses
English
2006-07-06
R203
R262
Journal of Physics B: Atomic, Molecular and Optical Physics
J. Phys. B
14
39
The theoretical description and the experimental methods and results for above-threshold ionization (ATI) by few-cycle pulses are reviewed. A pulse is referred to as a few-cycle pulse if its detailed shape, parametrized by its carrier-envelope phase, affects its interaction with matter. Angular-resolved ATI spectra are analysed with the customary strong-field approximation (SFA) as well as the numerical solution of the time-dependent Schrödinger equation (TDSE). After a general discussion of the characteristics and the description of few-cycle pulses, the behaviour of the ATI spectrum under spatial inversion is related to the shape of the laser field. The ATI spectrum both for the direct and for the rescattered electrons in the context of the SFA is evaluated by numerical integration and by the method of steepest descent (saddle-point integration), and the results are compared. The saddle-point method is modified to avoid the singularity of the dipole transition matrix element at the steepest-descent times. With the help of the saddle-point method and its classical limit, namely the simple-man model, the various features of the ATI spectrum, their behaviour under inversion, the cut-offs and the presence or absence of ATI peaks are analysed as a function of the carrier-envelope phase of the few-cycle laser field. All features observed in the spectra can be explained in terms of a few quantum orbits and their superposition. The validity of the SFA and the concept of quantum orbits are established by comparing the ATI spectra with those obtained numerically from the ab initio solution of the TDSE.
expertsonly
published
joureview
D. B.
Milosevic
D. B.
G. G.
Paulus
G. G.
D.
Bauer
D.
W.
Becker
W.
10.1088/0953-4075/39/14/R01
Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo, Bosnia and Herzegovina
Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
Department of Physics, Texas A&M University, College Station, TX 77843, USA
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-18 13:21:43.409757
© 2006 IOP Publishing Ltd
oai:edoc.mpg.de:2848002008-03-0337:954
Article
Mass measurements and the bound-electron g factor
English
2006-04-01
102
108
International Journal of Mass Spectrometry
Int. J. of Mass Spectr.
251
The accurate determination of atomic masses and the high-precision measurement of the bound-electron g factor are prerequisites for the determination of the electron mass, which is one of the fundamental constants of nature. In the 2002 CODATA adjustment [P.J. Mohr, B.N. Taylor, Rev. Mod. Phys. 77 (2005) 1], the values of the electron mass and the electron–proton mass ratio are mainly based on g factor measurements in combination with atomic mass measurements. In this paper, we briefly discuss the prospects for obtaining other fundamental information from bound-electron g factor measurements, we present some details of a recent investigation of two-loop binding corrections to the g factor, and we also investigate the radiative corrections in the limit of highly excited Rydberg S states with a long lifetime, where the g factor might be explored using a double resonance experiment.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
A.
Czarnecki
A.
K.
Pachucki
K.
V.
Yerokhin
Vladimir
10.1016/j.ijms.2005.12.051
Department of Physics, University of Alberta, Edmonton, Alta., Canada T6G 2J1
Institute of Theoretical Physics, Warsaw University, ul. Hoża 69, 00-681 Warsaw, Poland
Department of Physics, St. Petersburg State University, Oulianovskaya 1, Petrodvorets, St. Petersburg 198504, Russia
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 16:07:21.190498
© 2006 Elsevier B.V.
oai:edoc.mpg.de:2848022006-08-1737:954
Article
Collective coherent population trapping in a thermal field
English
2006-06-22
063821
Physical Review A
Phys. Rev. A
73
We analyze the efficiency of coherent population trapping (CPT) in a superposition of the ground states of three-level atoms under the influence of the decoherence process induced by a broadband thermal field. We show that in a single atom there is no perfect CPT when the atomic transitions are affected by the thermal field. The perfect CPT may occur when only one of the two atomic transitions is affected by the thermal field. In the case when both atomic transitions are affected by the thermal field, we demonstrate that regardless of the intensity of the thermal field the destructive effect on the CPT can be circumvented by the collective behavior of the atoms. An analytic expression was obtained for the populations of the upper atomic levels which can be considered as a measure of the level of thermal decoherence. The results show that the collective interaction between the atoms can significantly enhance the population trapping in that the population of the upper state decreases with an increased number of atoms. The physical origin of this feature is explained by the semiclassical dressed-atom model of the system. We introduce the concept of multiatom collective coherent population trapping by demonstrating the existence of collective (entangled) states whose storage capacity is larger than that of the equivalent states of independent atoms.
expertsonly
published
joureview
M.
Macovei
Mihai
Z.
Ficek
Zbigniew
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.73.063821
Department of Physics, School of Physical Sciences, The University of Queensland, Brisbane, Australia 4072
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-08-17 14:52:58.640946
©2006 The American Physical Society
oai:edoc.mpg.de:2848072006-08-1737:954
Article
Interference in the resonance fluorescence of two incoherently coupled transitions
English
2006-06-16
063814
Physical Review A
Phys. Rev. A
73
The fluorescence light emitted by a four-level system in J=1/2 to J=1/2 configuration driven by a monochromatic laser field and in an external magnetic field is studied. We show that the spectrum of resonance fluorescence emitted on the transitions shows a signature of spontaneously generated interference effects. The degree of interference in the fluorescence spectrum can be controlled by means of the external magnetic field, provided that the Landé g factors of the excited and the ground state doublet are different. For a suitably chosen magnetic field strength, the relative weight of the Rayleigh line can be completely suppressed, even for low intensities of the coherent driving field. The incoherent fluorescence spectrum emitted on the transitions exhibits a very narrow peak whose width and weight depend on the magnetic field strength. We demonstrate that the spectrum of resonance fluorescence emitted on the transitions shows an indirect signature of interference. A measurement of the relative peak heights in the spectrum from the transitions allows us to determine the branching ratio of the spontaneous decay of each excited state into the channel.
expertsonly
published
joureview
M.
Kiffner
Martin
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.73.063814
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-08-17 14:42:18.458878
©2006 The American Physical Society
oai:edoc.mpg.de:2848082008-03-0337:954
Article
Quantum electrodynamic corrections to the hyperfine structure of excited S states
English
2006-06-07
062503
Physical Review A
Phys. Rev. A
73
State-dependent quantum electrodynamic corrections are evaluated for the hyperfine splitting of nS states for arbitrary principal quantum number n. The calculations comprise both the self-energy and the vacuum-polarization correction of order (Z)2EF and the recoil correction of order (Z)2(m/M)EF. Higher-order corrections are summarized and partly reevaluated as well. Accurate predictions for hydrogen hyperfine splitting intervals of nS states with n=2,,8 are presented. The results obtained are important due to steady progress in hydrogen spectroscopy for transitions involving highly excited S states.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
V. A.
Yerokhin
Vladimir A.
10.1103/PhysRevA.73.062503
Polytechnical University, Polytekhnicheskaya 29, St. Petersburg 195251, Russia
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 15:53:05.68198
©2006 The American Physical Society
oai:edoc.mpg.de:2848102006-08-1737:954
Article
Polarization-operator approach to electron-positron pair production in combined laser and Coulomb fields
English
2006-06-09
062106
Physical Review A
Phys. Rev. A
73
The optical theorem is applied to the process of electron-positron pair creation in the superposition of a nuclear Coulomb and a strong laser field. We derive representations for the total production rate as twofold integrals, both for circular laser polarization and for the general case of elliptic polarization. Our approach allows us to obtain, by analytical means, the asymptotic behavior of the pair creation rate for various limits of interest. In particular, we consider pair production by two-photon absorption and show that, close to the energetic threshold of this process, the rate obeys a power law in the laser frequency with different exponents for linear and circular laser polarization. With the help of the upcoming x-ray laser sources, our results could be tested experimentally.
expertsonly
published
joureview
A. I.
Milstein
Alexander I.
C.
Müller
Carsten
K. Z.
Hatsagortsyan
Karen Zaven
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.73.062106
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-08-17 14:35:47.100683
©2006 The American Physical Society
oai:edoc.mpg.de:2848112006-08-1737:954
Article
Gauge-invariant relativistic strong-field approximation
English
2006-05-31
053411
Physical Review A
Phys. Rev. A
73
The problem of the choice of gauge in the relativistic strong-field approximation (SFA) is analyzed. The main motivation is to obtain a relativistic ionization amplitude in the SFA which in the nonrelativistic limit coincides with the conventional well-accepted results of the SFA in the length gauge. A gauge-invariant formulation of the SFA is derived which is applicable both in the nonrelativistic as well as in the relativistic regime of laser-induced strong-field ionization phenomena. The gauge invariance is achieved by means of employment of an eigenstate of the physical energy operator for the initial atomic state. As an example, a comparison of predictions of the gauge-invariant theory with conventional SFA results in the radiation gauge is given for above-threshold ionization in the relativistic regime.
expertsonly
published
joureview
M.
Klaiber
Michael
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
Theoretische Quantendynamik, Physikalisches Institut der Albert-Ludwigs-Universität, Hermann-Herder-Straße 3, D-79104, Freiburg, Germany
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-08-17 14:33:28.297399
©2006 The American Physical Society
oai:edoc.mpg.de:2848142010-05-2537:954
Article
Two-photon excitation dynamics in bound two-body Coulomb systems including ac Stark shift and ionization
English
2006-05-03
052501
Physical Review A
Phys. Rev. A
5
73
One of the dominant systematic effects that shift resonance lines in high-precision measurements of two-photon transitions is the dynamic (ac) Stark shift. For suitable laser frequencies, the ac Stark shift acquires an imaginary part which corresponds to the rate of resonant one-photon ionization of electrons into a continuum state. At the current level of spectroscopic accuracy, the underlying time-dependent quantum dynamics governing the atomic two-photon excitation process must be well understood, and related considerations are the subject of the present paper. In order to illustrate the basic mechanisms in the transient regime, we investigate an analytically solvable model scenario for the population dynamics in the density matrix formalism and describe in detail how to generalize the corresponding equations of motion for individual experimental use. We also calculate the dynamic Stark shift for two-photon S-S and S-D transitions in bound two-body Coulomb systems and the corresponding two-photon transition matrix elements. In particular, we investigate transitions for which the 1S ground state or alternatively the metastable 2S state acts as the lower-energy state, and for which states with n20 represent the upper states. Relativistic and radiative corrections to the excitation dynamics, and the corresponding limitations to the accuracy of the measurements, are briefly discussed. Our considerations suggest the general feasibility of a detection mechanism, offering high quantum efficiency, based on two-step three-photon resonant ionization spectroscopy, for large classes of experimentally relevant two-photon transitions in two-body Coulomb systems.
expertsonly
published
notspecified
M.
Haas
Martin
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
N.
Kolachevsky
N.
M.
Herrmann
M.
P.
Fendel
P.
M.
Fischer
M.
T.
Udem
Thomas
R.
Holzwarth
R.
T. W.
Hänsch
T. W.
M. O.
Scully
M. O.
G. S.
Agarwal
G. S.
10.1103/PhysRevA.73.052501
Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
Institute for Quantum Studies and Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA and Princeton Institute for Materials Research, Princeton University, Princeton, New Jersey 08544-1009, USA
Physics Research Laboratory, Nevrangpura, Ahmedabad-380 009, India and Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2010-05-25 11:01:15.411113
©2006 The American Physical Society
oai:edoc.mpg.de:2848152008-03-0337:954
Article
Anomalous magnetic moments of free and bound leptons
English
2006
1
10
Canadian Journal of Physics
Can. J. Phys.
S2
84
We review the theoretical knowledge of anomalous magnetic moments of free electrons and muons, and of electrons bound in hydrogenlike ions. We discuss applications of these observations in the determination of fundamental physical constants, the fine structure constant, the electron mass, and in searches for new interactions.
expertsonly
published
notspecified
A.
Czarnecki
A.
U. D.
Jentschura
Ulrich David
K.
Pachucki
K.
V.
Yerokhin
Vladimir
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 16:13:04.82365
oai:edoc.mpg.de:2848162006-08-1737:954
Article
Probing Proton Dynamics in Molecules on an Attosecond Time Scale
English
2006-04-21
424
427
Science
5772
312
We demonstrate a technique that uses high-order harmonic generation in molecules to probe nuclear dynamics and structural rearrangement on a subfemtosecond time scale. The chirped nature of the electron wavepacket produced by laser ionization in a strong field gives rise to a similar chirp in the photons emitted upon electron-ion recombination. Use of this chirp in the emitted light allows information about nuclear dynamics to be gained with 100-attosecond temporal resolution, from excitation by an 8-femtosecond pulse, in a single laser shot. Measurements on molecular hydrogen and deuterium agreed well with calculations of ultrafast nuclear dynamics in the H2+ molecule, confirming the validity of the method. We then measured harmonic spectra from CH4 and CD4 to demonstrate a few-femtosecond time scale for the onset of proton rearrangement in methane upon ionization.
expertsonly
published
joureview
S.
Baker
S.
J. S.
Robinson
J. S.
C. A.
Haworth
C. A.
H.
Teng
H.
R. A.
Smith
R. A.
C. C.
Chirila
Ciprian C.
M.
Lein
Manfred
J. W. G.
Tisch
J. W. G.
J. P.
Marangos
J. P.
10.1126/science.1123904
Blackett Laboratory, Imperial College London, Prince Consort Road, South Kensington, London SW7 2BZ, UK
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2006-08-17 14:17:01.556995
© 2006 American Association for the Advancement of Science
oai:edoc.mpg.de:2848172006-08-1737:954
Article
Two-electron ionization and stabilization beyond the dipole approximation
English
2006-04-20
043412
Physical Review A
Phys. Rev. A
73
A two-dimensional model atom is employed to study the ionization behavior of helium subjected to strong laser fields in the high-frequency regime. The evolution of the system is studied by means of numerical integration of the Schrödinger equation beyond the dipole approximation. Ionization probabilities of the two-electron atom in highly intense laser fields have been calculated for different pulse shapes. It is confirmed that the mutual repulsion between the two electrons as well as the length of the laser pulses significantly alter the ionization probabilities of the system. Nondipole effects are shown to lead to a considerable increase of the ionization probabilities. For certain laser pulse shapes, a regime of ionization suppression is investigated which exists in addition to two-electron stabilization. The applicability of our model scheme to the case of heliumlike systems is discussed, and it is shown that stabilization may also occur in these systems, and how it is altered in dependence of the nuclear charge.
expertsonly
published
joureview
A.
Staudt
Andreas
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.73.043412
Theoretische Quantendynamik, Physikalisches Institut, Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-08-17 13:58:02.297683
©2006 The American Physical Society
oai:edoc.mpg.de:2848182006-08-1737:954
Article
Relativistic high-power laser–matter interactions
English
2006-03-02
41
155
Physics Reports
Phys. Rep.
2-3
427
Recent advances in laser technology have pushed the frontier of maximum intensity achieved to about and investigators currently believe even higher intensities may be reached in the near future. This, combined with other breakthroughs on the fronts of short pulse generation and high repetition rates, have stimulated considerable progress, theoretical as well as experimental, in the field of laser–matter interactions. It is now possible to laser-accelerate electrons to a few hundred MeV and laser-induced pair-production and nuclear physics experiments have made significant progress. This article is devoted to a review of the recent advances in the field and stresses quantum phenomena that require laser field intensities in excess of the relativistic threshold of . Interactions with free electrons, with highly-charged ions and with atoms and clusters, are reviewed. Electron laser acceleration, atomic quantum dynamics, high harmonic generation, quantum electrodynamical effects and nuclear interactions in plasmas and ions, are among the important topics covered in the article.
expertsonly
published
joureview
Y. I.
Salamin
Yousef I.
S. X.
Hu
S. X.
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1016/j.physrep.2006.01.002
Physics Department, American University of Sharjah, POB 26666, Sharjah, United Arab Emirates
Group T-4, Theoretical Division, MS B283, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
Department of Quantum Electronics, Yerevan State University, A. Manoukian 1, Yerevan 375025, Armenia
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-08-17 13:55:48.663599
© 2006 Elsevier B.V.
oai:edoc.mpg.de:2852912006-08-1737:954
Article
Nuclear Quantum Optics with X-Ray Laser Pulses
English
2006-04-10
142501
Physical Review Letters
Phys. Rev. Lett.
96
The direct interaction of nuclei with superintense laser fields is studied. We show that present and upcoming high-frequency laser facilities, especially together with a moderate acceleration of the target nuclei to match photon and transition frequency, do allow for resonant laser-nucleus interaction. These direct interactions may be utilized for the model-independent optical measurement of nuclear properties such as the transition frequency and the dipole moment, thus opening the field of nuclear quantum optics. As an ultimate goal, one may hope that direct laser-nucleus interactions could become a versatile tool to enhance preparation, control, and detection in nuclear physics.
expertsonly
published
joureview
T. J.
Bürvenich
Thomas J.
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevLett.96.142501
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-08-17 13:51:05.89518
©2006 The American Physical Society
oai:edoc.mpg.de:2852922007-09-1937:954
Article
Nonlinear Resonance Absorption in the Laser-Cluster Interaction
English
2006-03-27
1
4
123401
Physical Review Letters
Phys. Rev. Lett.
96
Rare-gas or metal clusters are known to absorb laser energy very efficiently. Upon cluster expansion, the Mie plasma frequency may become equal to the laser frequency. This linear resonance has been well studied both experimentally and theoretically employing pump probe schemes. In this work, we focus on the few-cycle regime or the early stage of the cluster dynamics, where linear resonance is not met but, nevertheless, efficient absorption of laser energy persists. By retrieving time-dependent oscillator frequencies from particle-in-cell simulation results, we show that nonlinear resonance is the dominant mechanism behind outer ionization and energy absorption in near infrared laser-driven clusters.
expertsonly
published
joureview
M.
Kundu
Mrityunjay
D.
Bauer
Dieter
10.1103/PhysRevLett.96.123401
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-19 10:46:36.91422
©2006 The American Physical Society
oai:edoc.mpg.de:2852932007-09-1937:954
Article
QPROP: A Schrödinger-solver for intense laser–atom interaction
English
2006-03-01
396
421
Computer Physics Communications
Comp. Phys. Comm.
5
174
The Qprop package is presented. Qprop has been developed to study laser–atom interaction in the nonperturbative regime where nonlinear phenomena such as above-threshold ionization, high order harmonic generation, and dynamic stabilization are known to occur. In the nonrelativistic regime and within the single active electron approximation, these phenomena can be studied with Qprop in the most rigorous way by solving the time-dependent Schrödinger equation in three spatial dimensions. Because Qprop is optimized for the study of quantum systems that are spherically symmetric in their initial, unperturbed configuration, all wavefunctions are expanded in spherical harmonics. Time-propagation of the wavefunctions is performed using a split-operator approach. Photoelectron spectra are calculated employing a window-operator technique. Besides the solution of the time-dependent Schrödinger equation in single active electron approximation, Qprop allows to study many-electron systems via the solution of the time-dependent Kohn–Sham equations.
expertsonly
published
notspecified
D.
Bauer
Dieter
P.
Koval
Peter
10.1016/j.cpc.2005.11.001
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-19 10:55:58.602016
© 2005 Elsevier B.V.
oai:edoc.mpg.de:2852942008-03-0337:954
Article
Radiative electron capture into high-Z few-electron ions: Alignment of the excited ionic states
English
2006-03-17
1
8
032716
Physical Review A
Phys. Rev. A
73
We lay out a unified formalism for the description of radiative electron capture into excited states of heavy, few-electron ions and their subsequent decay, including a full account of many-electron effects and higher-order multipoles of the radiation field. In particular, the density-matrix theory is applied to explore the magnetic sublevel population of the residual ions, as described in terms of alignment parameters. For the electron capture into the initially hydrogenlike U<sup>91+</sup> and lithiumlike U<sup>89+</sup> uranium projectiles, the alignment parameters are calculated, within the multiconfiguration Dirac-Fock approach, as a function of the collision energy and for different ionic states. From these calculations, we find that the many-electron interactions may result in a small enhancement of the alignment, and that this effect becomes more pronounced for highly excited levels.
expertsonly
published
joureview
A.
Surzhykov
Andrey
U. D.
Jentschura
Ulrich David
T.
Stöhlker
Thomas
S.
Fritzsche
Stephan
10.1103/PhysRevA.73.032716
Gesellschaft für Schwerionenforschung (GSI), D-64291 Darmstadt, Germany
Institut für Kernphysik, Universität Frankfurt, D-60486 Frankfurt, Germany
Institut für Physik, Universität Kassel, D-34132 Kassel, Germany
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 16:08:15.51123
©2006 The American Physical Society
oai:edoc.mpg.de:2856902006-08-1737:954
Article
Strong-field approximation for harmonic generation in diatomic molecules
English
2006-02-14
023410
Physical Review A
Phys. Rev. A
73
The generation of high-order harmonics in diatomic molecules is investigated within the framework of the strong-field approximation. We show that the conventional saddle-point approximation is not suitable for large internuclear distances. An adapted saddle-point method that takes into account the molecular structure is presented. We analyze the predictions for the harmonic-generation spectra in both the velocity and length gauges. At large internuclear separations, we compare the resulting cutoffs with the predictions of the three-step semiclassical mechanism. Good agreement is obtained only by using the adapted saddle-point method combined with the velocity gauge.
expertsonly
published
joureview
C. C.
Chirila
Ciprian C.
M.
Lein
Manfred
10.1103/PhysRevA.73.023410
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2006-08-17 13:53:51.149581
©2006 The American Physical Society
oai:edoc.mpg.de:2856912006-08-1737:954
Article
Geometry-dependent dynamics of two Λ-type atoms via vacuum-induced coherences
English
2006-02-06
023804
Physical Review A
Phys. Rev. A
73
The dynamics of a pair of atoms can significantly differ from the single-atom dynamics if the distance of the two atoms is small on a scale given by the relevant transition wavelengths. Here, we discuss two nearby three-level atoms in Λ configuration, and focus on the dependence of the optical properties on the geometry of the setup. We find that in general transitions in the two atoms can be dipole-dipole coupled by interactions via the vacuum field even if their transition dipole moments are orthogonal. We give an interpretation of this effect and show that it may crucially influence the system dynamics. In particular, for a fixed setup of driving fields and detectors, the spatial orientation of the two-atom pair decides if the system reaches a true constant steady state or if it exhibits periodic oscillations in the long-time limit. As an example observable, we study the resonance fluorescence intensity, which is either constant or is modulated periodically in the long-time limit.
expertsonly
published
joureview
J.
Evers
Jörg
M.
Kiffner
Martin
M.
Macovei
Mihai
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.73.023804
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-08-17 14:59:59.546745
©2006 The American Physical Society
oai:edoc.mpg.de:2856942006-08-1737:954
Article
Influence of nuclear vibration on harmonic generation in molecules
English
2006-06-22
437
444
Journal of Physics B
J. Phys. B
13
39
The effect of vibrational motion on harmonic generation in molecules is studied within the strong-field approximation. Simple expressions are given for the cut-off energy and for the ratio of spectral intensities from two isotopes. The latter is based on electronic trajectories from the simple-man's model. The influence of vibration is given by a correlation function that is sensitive to the overlap between the initial vibrational wave packet and the wave packet after the evolution in the Born–Oppenheimer potential of the ionized molecule.
expertsonly
published
joureview
C. C.
Chirila
Ciprian C.
M.
Lein
Manfred
10.1088/0953-4075/39/13/S17
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2006-08-17 15:05:38.399922
© Institute of Physics and IOP Publishing Limited 2006
oai:edoc.mpg.de:2857022006-08-1737:954
Article
Ionization suppression of excited atomic states beyond the stabilization regime
English
2006-01-09
633
639
Journal of Physics B
J. Phys. B
3
39
A two-dimensional model atom is employed to study the ionization behaviour of initially excited atomic states in intense high frequency laser pulses beyond the dipole approximation. An additional regime of ionization suppression is found at laser intensities where the stabilization effect is expected to break down. The appearance of this effect is due to a strong coupling of the initial wavefunction to the ground state of the cycle-averaged space-translated ionic potential, followed by a subsequent population transfer to the ground state during the laser pulse turn-off. Non-dipole effects are found to increase the overall ionization probabilities, but not to suppress or alter this effect substantially.
expertsonly
published
joureview
A.
Staudt
Andreas
C. H.
Keitel
Christoph Helmut
J. S.
Briggs
John S.
10.1088/0953-4075/39/3/016
Theoretische Quantendynamik, Physikalisches Institut, Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-08-17 15:13:45.736681
© Institute of Physics and IOP Publishing Limited 2006
oai:edoc.mpg.de:2857722006-08-2137:954
Conference-Paper
Irreversible energy gain by linear and nonlinear oscillators
English
2005
169
179
Journal of Physics: Conference Series
11
Kinetic theory of nonideal plasmas : workshop in memory of Yuri Klimontovich
Kiel, Germany
2004-09-27
2004-09-29
A particle can gain appreciable irreversible energy ("absorption") from linear or nonlinear oscillations only by ballistic excitation ("collision") or, if excited by an adiabatic pulse of constant frequency, by undergoing resonance. For the linear oscillator it is shown that the transition from ballistic to adiabatic behavior out of resonance occurs for sin2-pulses 2–4 eigenperiod long. In the case of a linear oscillator with time-varying eigenfrequency it is shown that Cornu's double spiral represents an attractor, either for zero energy gain out of resonance or finite gain by transiting through resonance. One of the remarkable properties of nonlinear oscillators is that resonance depends on the level of excitation. It is this property which opens a new access to understanding the dominant heating process at high laser intensities, the so-called collisionless absorption phase in solids, extended cluster media, dusty plasmas, and sprays, well guaranteed by experiments and computer simulations but hitherto not well understood in physical terms.
notspecified
published
notspecified
D.
Bauer
Dieter
P.
Mulser
P.
10.1088/1742-6596/11/1/017
Theoretical Quantum Electronics (TQE), TU Darmstadt, Schlossgartenstr. 7, 64289 Darmstadt, Germany
Kinetic Theory of Nonideal Plasmas
MPI für Kernphysik
Group C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2006-08-21 10:51:21.134725
© Institute of Physics and IOP Publishing Limited 2006
oai:edoc.mpg.de:2857772006-08-2137:954
Conference-Paper
Vacuum-mediated incoherent processes in coherently prepared media
English
SPIE
Bellingham, Wash.
2005
5842
Fluctuations and Noise in Photonics and Quantum Optics III
Austin, Texas, USA
2005-05-24
2005-05-26
Fluctuations and noise in photonics and quantum optics III
Hemmer, Philip R.
Proceedings of SPIE
We discuss various aspects of the incoherent spontaneous emission in atomic few-level systems arising from the coupling of the atom to the surrounding vacuum. First, we consider systems where the decoherence due to spontaneous emission acts as a limiting factor. Here, we combine collective effects in larger samples of atoms with control mechanisms known from single-atom schemes, or modifiy the system dynamics by externally inducing multiphoton quantum interference effects. In the second part, we discuss ground-state laser cooling of trapped atoms and ions. Here, the momentum transfer in the spontaneous emission events is required to cool the particles, but needs to be controlled in order to achieve a low cooling limit. In our scheme, we make use of double electromagnetically induced transparency in order to design the absorption spectrum of the trapped particle. In the final part, we show that the incoherent part of the resonance fluorescence spectrum of a two-level system may serve as an interesting candidate for high-precision spectroscopy. For this, we discuss relativistic and radiative corrections to the resonance fluorescence spectra of laser-driven few-level systems.
expertsonly
XXVIII, 316 S.
published
notspecified
J.
Evers
Jörg
U. D.
Jentschura
Ulrich David
M.
Macovei
Mihai
C. H.
Keitel
Christoph Helmut
10.1117/12.609233
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2006-08-21 11:43:39.565325
© 2005 The Society of Photo-Optical Engineering
oai:edoc.mpg.de:2857962006-08-2137:954
Article
Toward high-precision values of the self energy of non-S states in hydrogen and hydrogen-like ions
English
2005-04-01
447
454
Canadian Journal of Physics
Can. J. Phys.
4
83
The method and status of a study to provide numerical, high-precision values of the self-energy level shift in hydrogen and hydrogen-like ions is described. Graphs of the self energy in hydrogen-like ions with nuclear charge number between 20 and 110 are given for a large number of states. The self-energy is the largest contribution of quantum electrodynamics (QED) to the energy levels of these atomic systems. These results greatly expand the number of levels for which the self energy is known with a controlled and high precision. Applications include the adjustment of the Rydberg constant and atomic calculations that take into account QED effects.
expertsonly
published
notspecified
E.-O.
Le Bigot
E.-O.
U. D.
Jentschura
Ulrich David
P.
Indelicato
P.
P. J.
Mohr
P. J.
10.1139/P04-076
Laboratoire Kastler Brossel, École Normale Supérieure et Université Pierre et Marie Curie, Case 74, 4 place Jussieu, 75005 Paris, France
National Institute of Standards and Technology, Mail Stop 8401, Gaithersburg, MD 20899-8401,USA
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006-08-21 10:16:46.971212
© 2005 NRC Canada
oai:edoc.mpg.de:2857972006-08-2137:954
Article
Nonrelativistic QED approach to the Lamb shift
English
2005-12-01
1
20
062102
Physical Review A
Phys. Rev. A
72
We calculate the one- and two-loop corrections of order (Z)6 and 2(Z)6, respectively, to the Lamb shift in hydrogenlike systems using the formalism of nonrelativistic quantum electrodynamics. We obtain general results valid for all hydrogenic states with nonvanishing orbital angular momentum and for the normalized difference of S states. These results involve the expectation value of local effective operators and relativistic corrections to Bethe logarithms. The one-loop correction is in agreement with previous calculations for the particular cases of S, P, and D states. The two-loop correction in the order 2(Z)6 includes the pure two-loop self-energy and all diagrams with closed fermion loops. The obtained results allow one to obtain improved theoretical predictions for all excited hydrogenic states.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
A.
Czarnecki
Andrzej
K.
Pachucki
Krzysztof
Department of Physics, University of Alberta, Edmonton, Alberta Canada T6G 2J1
Institute of Theoretical Physics, Warsaw University, Hoza 69, 00-681 Warsaw, Poland
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006-08-21 10:59:35.915258
©2005 The American Physical Society
oai:edoc.mpg.de:2857992007-03-1637:954
Conference-Paper
Nonperturbative multiphoton processes and electron-positron pair production
English
AIP
USA
2006-04-07
442
447
827
Third International Conference on Superstrong Fields in Plasmas
Varenna, Italy
2005-09-19
2005-09-24
Superstrong fields in plasmas : Third International Conference on Superstrong Fields in Plasmas, Varenna, Italy, 19 - 24 September 2005 ; [selected papers]
Batani, Dimitri ; Lontano, Maurizio
AIP Conference Proceedings
Various regimes of pair production in laser fields are analyzed. Particularly, the question of the observability of pair production in a nonperturbative multiphoton regime is discussed. A simple heuristic method is employed which gives order-of-magnitude estimates for probabilities of multiphoton processes and allows to describe its main features. The method is initially probed upon the known process of pair production in a Coulomb and a strong laser field. Then it is applied to the nonperturbative multiphoton regime of the pair production process in a standing laser wave.
expertsonly
published
notspecified
K. Z.
Hatsagortsyan
Karen Zaven
C.
Müller
Carsten
C. H.
Keitel
Christoph Helmut
10.1063/1.2195234
MPI für Kernphysik
Group of C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2007-03-16 13:52:36.310128
©2006 American Institute of Physics
oai:edoc.mpg.de:2858002007-03-1637:954
Conference-Paper
Harmonic generation from laser-driven vacuum
English
AIP
USA
2006-04-07
436
441
827
Third International Conference on Superstrong Fields in Plasmas
Varenna, Italy
2005-04-19
2005-04-24
Superstrong fields in plasmas : Third International Conference on Superstrong Fields in Plasmas, Varenna, Italy, 19 - 24 September 2005 ; [selected papers]
Batani, Dimitri ; Lontano, Maurizio
AIP Conference Proceedings
We investigate harmonic generation from vacuum in the field of a superstrong standing laser wave. We show analitycally that for laser electric fields larger than Ecr = m2c3/e = 1.3 · 1016 V/cm high order harmonics of the pumping laser are generated. The harmonic spectrum shows a wide plateau followed by a cut-off at photon energies M ~ with EL the amplitude of the 6laser field. In the weak field limit EL Ecr the emission of high harmonics is very unlikely. This is now the experimentally interesting case and we show that "laser assisted" photon-photon scattering could be observed with optical lasers available today.
expertsonly
published
notspecified
A.
Di Piazza
Antonino
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1063/1.2195233
MPI für Kernphysik
Group of C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2007-03-16 13:54:23.550252
© 2006 American Institute of Physics
oai:edoc.mpg.de:2858012006-08-2137:954
Conference-Paper
QED Corrections to the Dynamic Polarizability
English
AIP
USA
2005-10-26
796
Eighth International Conference on Low Energy Antiproton Physics (LEAP '05)
Bonn, Germany
2005-05-16
2005-05-22
Low energy antiproton physics : Eighth International Conference on Low Energy Antiproton Physics (LEAP '05) Bonn, Germany 13 - 22 May 2005
Grzonka, Dieter
AIP Conference Proceedings
In a relatively weak laser field, atoms interacting with one-photon off-resonant laser fields are dynamically polarized. This perturbation manifests itself in a shift of the atomic energy levels called the "dynamic Stark effect" or "AC-Stark effect", which is intensity dependent. The AC-Stark coefficients are therefore of particular importance for high-precision spectroscopy experiments which rely on two-photon processes like the 1S-2S transition in hydrogen, hydrogenlike ions, antihydrogen or similar composite matter-antimatter systems. In addition, the imaginary part of the dynamic polarizability determines the resonant one-photon ionization width for the excited level.Up to now, the dynamic polarizability has been investigated only up to the level of relativistic corrections. In this contribution, we present results for several experimentally relevant transitions in hydrogenlike systems and the leading-order QED radiative corrections.
expertsonly
XV, 453 S. : Ill., graph. Darst.
published
notspecified
M.
Haas
Martin
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
10.1063/1.2130187
MPI für Kernphysik
Group C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2006-08-21 09:36:59.020943
©2005 American Institute of Physics
oai:edoc.mpg.de:2879662006-10-0537:954
Article
Controlling multiparticle correlations with a strong laser field
English
2006-08-15
407
412
Optics Communications
Opt. Comm.
2
264
The collective interaction via a surrounding thermalized electromagnetic reservoir of a two-level multiatom sample with an external applied strong coherent field is investigated. In a small sample following Dicke’s model, even at the exact resonances, very strong pumping leads to a complete transfer of the population into a particular dressed-state. This way very large Rabi frequencies are shown to modify and control the interatomic correlations in a system of spatially separated atoms of few wavelengths extend.
expertsonly
published
notspecified
M.
Dal Col
Mario
M.
Macovei
Mihai
C. H.
Keitel
Christoph Helmut
10.1016/j.optcom.2006.02.062
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-10-05 13:03:35.846722
© 2006 Elsevier B.V.
oai:edoc.mpg.de:2879672006-10-0537:954
Article
Microscopic laser-driven high-energy colliders
English
2006-08-25
29
35
Europhysics Letters
Europhys. Lett.
1
76
The concept of a laser-guided e<sup>+</sup>e<sup>-</sup> collider in the single-femtosecond and high-energy regime is presented and its feasibility discussed. Ultra-intense laser pulses and strong static magnetic fields are employed to unite in one stage the electron and positron acceleration and their microscopic coherent collision in the GeV regime. We show that such coherent collisions yield a very large enhancement of the luminosity as compared to conventional incoherent colliders.
expertsonly
published
notspecified
K. Z.
Hatsagortsyan
Karen Zaven
C.
Müller
Carsten
C. H.
Keitel
Christoph Helmut
10.1209/epl/i2006-10226-2
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-10-05 13:01:09.667526
© EDP Sciences 2006
oai:edoc.mpg.de:2879682006-10-0537:954
Article
Light Diffraction by a Strong Standing Electromagnetic Wave
English
2006-08-24
1
4
083603
Physical Review Letters
Phys. Rev. Lett.
8
97
The nonlinear quantum interaction of a linearly polarized x-ray probe beam with a focused intense standing laser wave is studied theoretically. Because of the tight focusing of the standing laser pulse, diffraction effects arise for the probe beam as opposed to the corresponding plane wave scenario. A quantitative estimate for realistic experimental conditions of the ellipticity and the rotation of the main polarization plane acquired by the x-ray probe after the interaction shows that the implementation of such vacuum effects is feasible with future X-ray Free Electron Laser light.
expertsonly
published
joureview
A.
Di Piazza
Antonino
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevLett.97.083603
MPI für Kernphysik
Group C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2006-10-05 12:59:17.153153
©2006 The American Physical Society
oai:edoc.mpg.de:2879692008-03-0337:954
Article
Exploring Relativistic Many-Body Recoil Effects in Highly Charged Ions
English
2006-09-06
1
4
103002
Physical Review Letters
Phys. Rev. Lett.
10
97
The relativistic recoil effect has been the object of experimental investigations using highly charged ions at the Heidelberg electron beam ion trap. Its scaling with the nuclear charge Z boosts its contribution to a measurable level in the magnetic-dipole (M1) transitions of B- and Be-like Ar ions. The isotope shifts of <sup>36</sup>Ar versus <sup>40</sup>Ar have been detected with sub-ppm accuracy, and the recoil effect contribution was extracted from the 1s<sup>2</sup>2s<sup>2</sup>2p <sup>2</sup>P1/2-<sup>2</sup>P3/2 transition in Ar<sup>13+</sup> and the 1s<sup>2</sup>2s2p <sup>3</sup>P1-<sup>3</sup>P2 transition in Ar<sup>14+</sup>. The experimental isotope shifts of 0.00123(6) nm (Ar<sup>13+</sup>) and 0.00120(10) nm (Ar<sup>14+</sup>) are in agreement with our present predictions of 0.00123(5) nm (Ar<sup>13+</sup>) and 0.00122(5) nm (Ar<sup>14+</sup>) based on the total relativistic recoil operator, confirming that a thorough understanding of correlated relativistic electron dynamics is necessary even in a region of intermediate nuclear charges.
expertsonly
published
joureview
R.
Soria Orts
Rosario
Z.
Harman
Zoltan
J. R.
Crespo López-Urrutia
José R.
A. N.
Artemyev
Anton N.
H.
Bruhns
Hjalmar
A. J.
González Martínez
Antonio J.
U. D.
Jentschura
Ulrich David
C. H.
Keitel
Christoph Helmut
A.
Lapierre
Alain
V.
Mironov
V.
V. M.
Shabaev
V. M.
H.
Tawara
Hiroyuki
I. I.
Tupitsyn
Ilya I.
J.
Ullrich
Joachim
A. V.
Volotka
A. V.
10.1103/PhysRevLett.97.103002
Department of Physics, St. Petersburg State University, Oulianovskaya 1, Petrodvorets, St. Petersburg 198504, Russia
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
MPI für Kernphysik
Group of J. Ullrich
Electron Beam Ion Trap ( J.R. Crespo Lopez-Urrutia)
2007
2008-03-03 15:52:14.5401
©2006 The American Physical Society
oai:edoc.mpg.de:2879702006-10-0537:954
Article
Enhanced Recollisions for Antisymmetric Molecular Orbitals in Intense Laser Fields
English
2006-10-02
1
4
143901
Physical Review Letters
Phys. Rev. Lett.
14
97
The peculiarities of antisymmetric molecular orbitals are investigated in very intense linearly polarized laser pulses. For this purpose, the ionization-recollision quantum dynamics is evaluated theoretically beyond the dipole approximation. As opposed to the usual situation, the laser magnetic field component is found to strongly enhance recollision probabilities for particularly oriented antisymmetric molecular orbitals. Harmonic generation and related processes are thus allowed at high laser intensities without the common limitations by the laser magnetic field.
expertsonly
published
joureview
R.
Fischer
Robert
M.
Lein
Manfred
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevLett.97.143901
Institut für Physik, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
MPI für Kernphysik
Group C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2006-10-05 12:49:26.147417
©2006 The American Physical Society
oai:edoc.mpg.de:2879712006-10-0537:954
Article
Dynamic nuclear Stark shift in superintense laser fields
English
2006-10-03
1
9
044601
Physical Review C
Phys. Rev. C
4
74
The direct interaction of superintense laser fields in the optical frequency domain with nuclei is studied. As main observable, we consider the nuclear dynamic (AC) Stark shift of low-lying nuclear states due to the off-resonant excitation by the laser field. We include the case of accelerated nuclei to be able to control the frequency and the intensity of the laser field in the nuclear rest frame over a wide range of parameters. We find that AC-Stark shifts of the same order as in typical quantum optical systems relative to the respective transition frequencies are feasible with state-of-the-art or near-future laser field intensities and moderate acceleration of the target nuclei. Along with this shift, but only at intensities above the critical field strength, we find laser-induced modifications to the proton root-mean-square radii and to the proton density distribution. We thus expect direct laser-nucleus interaction to become of relevance together with other super-intense light-matter interaction processes such as pair creation.
expertsonly
published
joureview
T. J.
Bürvenich
Thomas J.
J.
Evers
Jörg
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevC.74.044601
Wolfgang Goethe University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main, Germany
MPI für Kernphysik
Group C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2006-10-05 12:46:53.736097
©2006 The American Physical Society
oai:edoc.mpg.de:2994362007-02-2637:954
Article
Muon pair creation from positronium in a circularly polarized laser field
English
2006-10-23
1
16
074017
Physical Review D
Phys. Rev. D
74
We study elementary particle reactions that result from the interaction of an atomic system with a very intense laser wave of circular polarization. As a specific example, we calculate the rate for the laser-driven reaction e<sup>+</sup>e<sup>-</sup>-->µ<sup>+</sup>µ<sup>-</sup>, where the electron and positron originate from a positronium atom or, alternatively, from a nonrelativistic e<sup>+</sup>e<sup>-</sup> plasma. We distinguish accordingly between the coherent and incoherent channels of the process. Apart from numerical calculations, we derive by analytical means compact formulas for the corresponding reaction rates. The rate for the coherent channel in a laser field of circular polarization is shown to be damped because of the destructive interference of the partial waves that constitute the positronium ground-state wave packet. Conditions for the observation of the process via the dominant incoherent channel in a circularly polarized field are pointed out.
expertsonly
published
joureview
C.
Müller
Carsten
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevD.74.074017
MPI für Kernphysik
Group of C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2007-02-26 13:40:37.991937
©2006 The American Physical Society
oai:edoc.mpg.de:2994442007-02-2637:954
Article
Distilling two-atom distance information from intensity-intensity correlation functions
English
2006-10-31
1
9
043820
Physical Review A
Phys. Rev. A
74
The intensity-intensity correlation function of the resonance fluorescence light of two two-level atoms driven by a resonant standing-wave laser field is examined. Our aim is to gain information on the distance between the two atoms from observables accessible in experiments. For this, we numerically solve the time-evolution equations of the system and calculate the steady-state intensity-intensity correlation by using the Laplace transform and quantum regression theory. By varying the interatomic distance from about half a wavelength down to small fractions of a wavelength, we show that the correlation function exhibits characteristic properties for different distance ranges. Based on these results, we propose a scheme to obtain interatomic distance information from the power spectrum of the correlation function, which allows us to extract the desired distance information over a wide range of distances with high accuracy.
expertsonly
published
joureview
J.-T.
Chang
Jun-Tao
J.
Evers
Jörg
M. S.
Zubairy
M. Suhail
10.1103/PhysRevA.74.043820
Institute for Quantum Studies and Department of Physics, Texas A&M University, College Station, Texas 77843, USA
MPI für Kernphysik
Group of C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2007-02-26 13:39:06.12682
©2006 The American Physical Society
oai:edoc.mpg.de:2994482008-03-0337:954
Article
Effective action and phase structure of multi-layer sine-Gordon type models
English
2006-03-09
2647
2659
Annals of Physics
Ann. Phys.
11
321
We analyze the effective action and the phase structure of Ν-layer sine-Gordon type models, generalizing the results obtained for the two-layer sine-Gordon model found in [I. Nándori, S. Nagy, K. Sailer, U.D. Jentschura, Nucl. Phys. B, 725 (2005) 467–492]. Besides the obvious field theoretical interest, the layered sine-Gordon model has been used to describe the vortex properties of high transition temperature superconductors, and the extension of the previous analysis to a general N-layer model is necessary for a description of the critical behaviour of vortices in realistic multi-layer systems. The distinction of the Lagrangians in terms of mass eigenvalues is found to be the decisive parameter with respect to the phase structure of the N-layer models, with neighboring layers being coupled by quadratic terms in the field variables. By a suitable rotation of the field variables, we identify the periodic modes (without explicit mass terms) in the N-layer structure, calculate the effective action and determine their Kosterlitz–Thouless type phase transitions to occur at a coupling parameter β<sup>2</sup><sub>c,N</sub>=8Nπ, where N is the number of layers (or flavors in terms of the multi-flavor Schwinger model).
expertsonly
published
notspecified
U. D.
Jentschura
Ulrich David
I.
Nándori
István
J.
Zinn-Justin
Jean
10.1016/j.aop.2006.01.005
Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary
DAPNIA/CEA Saclay, F-91191 Gif-sur-Yvette, France
Institut de Mathématiques de Jussieu–Chevaleret, Université de Paris VII, France
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 16:08:54.286294
© 2006 Elsevier Inc.
oai:edoc.mpg.de:2994522008-03-0337:954
Article
Quantum dot potentials: Symanzik scaling, resurgent expansions, and quantum dynamics
English
2006-11-15
1
13
205317
Physical Review B
Phys. Rev. B
74
This article is concerned with a special class of the "double-well-like" potentials that occur naturally in the analysis of finite quantum systems. Special attention is paid, in particular, to the so-called Fokker-Planck potential, which has a particular property: the perturbation series for the ground-state energy vanishes to all orders in the coupling parameter, but the actual ground-state energy is positive and dominated by instanton configurations of the form exp(−a/g), where a is the instanton action. The instanton effects are most naturally taken into account within the modified Bohr-Sommerfeld quantization conditions whose expansion leads to the generalized perturbative expansions (so-called resurgent expansions) for the energy eigenvalues of the Fokker-Planck potential. Until now, these resurgent expansions have been mainly applied for small values of coupling parameter g, while much less attention has been paid to the strong-coupling regime. In this contribution, we compare the energy values, obtained by directly resumming generalized Bohr-Sommerfeld quantization conditions, to the strong-coupling expansion, for which we determine the first few expansion coefficients in powers of g<sup>−2/3</sup>. Detailed calculations are performed for a wide range of coupling parameters g and indicate a considerable overlap between the regions of validity of the weak-coupling resurgent series and of the strong-coupling expansion. Apart from the analysis of the energy spectrum of the Fokker-Planck Hamiltonian, we also briefly discuss the computation of its eigenfunctions. These eigenfunctions may be utilized for the numerical integration of the (single-particle) time-dependent Schrödinger equation and, hence, for studying the dynamical evolution of the wave packets in the double-well-like potentials.
expertsonly
published
joureview
A.
Surzhykov
Andrey
M.
Lubasch
Michael
J.
Zinn-Justin
Jean
U. D.
Jentschura
Ulrich David
10.1103/PhysRevB.74.205317
DAPNIA, Commissariat à l'Énergie Atomique, Centre de Saclay, 91191 Gif-Sur-Yvette, France
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 15:49:15.508195
©2006 The American Physical Society
oai:edoc.mpg.de:2994562007-02-2637:954
Article
High-order above-threshold ionization in stretched molecules
English
2006-11-03
1
4
051401
Physical Review A
Phys. Rev. A
74
By numerical solution of the time-dependent Schrödinger equation, highly accurate electron spectra are calculated for strong-field ionization of a one-dimensional H2<sup>+</sup> molecular ion at large internuclear distances. Compared to the atomic spectra, we find additional cutoffs at high electron energies. The classical model for ionization (simple-man's model) adapted to the molecular geometry predicts cutoffs up to 50Up, where Up is the ponderomotive potential. The cutoffs correspond to various scattering scenarios of the tunneled electron from the molecular sites. For certain internuclear distances the agreement between the classical predictions and the numerical spectra is unsatisfactory. We propose a modified simple-man's model based on complex electron trajectories, allowing for electrons appearing in the continuum with nonzero initial velocity from the tunneling ionization process. Agreement of the resulting cutoffs with the numerical results is recovered.
expertsonly
published
joureview
C. C.
Chirila
Ciprian C.
M.
Lein
Manfred
10.1103/PhysRevA.74.051401
Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
MPI für Kernphysik
Group of C.H. Keitel
Molecular Quantum Dynamics and Attosecond Physics (M. Lein)
2007
2007-02-26 13:34:34.568305
©2006 The American Physical Society
oai:edoc.mpg.de:2994842010-05-2537:954
Article
Photoionization broadening of the 1S-2S transition in a beam of atomic hydrogen
English
2006-11-15
1
9
052504
Physical Review A
Phys. Rev. A
74
We consider the excitation dynamics of the two-photon 1S-2S transition in a beam of atomic hydrogen by 243 nm laser radiation. Specifically, we study the impact of ionization damping on the transition line shape, caused by the possibility of ionization of the 2S level by the same laser field. Using a Monte Carlo simulation, we calculate the line shape of the 1S-2S transition for the experimental geometry used in the two latest absolute frequency measurements [M. Niering et al., Phys. Rev. Lett. 84, 5496 (2000) and M. Fischer et al., Phys. Rev. Lett. 92, 230802 (2004)]. The calculated line shift and linewidth are in excellent agreement with the experimentally observed values. From this comparison we can verify the values of the dynamic Stark shift coefficient for the 1S-2S transition for the first time on a level of 15%. We show that the ionization modifies the velocity distribution of the metastable atoms, the line shape of the 1S-2S transition, and has an influence on the derivation of its absolute frequency.
expertsonly
published
joureview
N.
Kolachevsky
Nikolai
M.
Haas
Martin
U. D.
Jentschura
Ulrich David
M.
Herrmann
Maximilian
P.
Fendel
Peter
M.
Fischer
Marc
R.
Holzwarth
Ronald
T.
Udem
Thomas
C. H.
Keitel
Christoph Helmut
T. W.
Hänsch
Theodor W.
10.1103/PhysRevA.74.052504
P.N. Lebedev Physics Institute, Leninsky prosp. 53, 119991 Moscow, Russia
MenloSystems GmbH, Am Klopferspitz 19, 82152 Martinsried, Germany
Ludwig-Maximilians-University, Munich, Germany
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
MPI für Quantenoptik
2007
2010-05-25 11:01:48.063372
©2006 The American Physical Society
oai:edoc.mpg.de:2994942008-03-0337:954
Article
Kα<sub>1</sub> radiation from heavy, heliumlike ions produced in relativistic collisions
English
2006-11-15
1
5
052710
Physical Review A
Phys. Rev. A
74
Bound-state transitions in few-electron, heavy ions following radiative electron capture are studied within the framework of the density matrix theory and the multiconfiguration Dirac-Fock approach. Special attention is paid to the Kα<sub>1</sub> (1s<sub>1/2</sub>2<sub>p3/2</sub> <sup>1,3</sup>P<sub>J=1,2</sub>-->1s<sub>1/2</sub><sup>2</sup> <sup>1</sup>S<sub>J=0</sub>) radiative decay of heliumlike uranium U<sup>90+</sup> projectiles. This decay has recently been observed at the GSI facility in Darmstadt, giving rise to a surprisingly isotropic angular distribution, which is inconsistent with previous experiments and calculations based on a "one-particle" model. We show that the unexpected isotropy essentially results from the mutual cancellation of the angular distributions of the <sup>1</sup>P<sub>1</sub>-->¹S₀ electric dipole and ³P₂-->¹S₀ magnetic quadrupole transitions, both of which contribute to the Kα₁ radiation. Detailed computations on the anisotropy of the Kα₁ radiation have been carried out for a wide range of projectile energies and are compared to available experimental data.
expertsonly
published
notspecified
A.
Surzhykov
Andrey
U. D.
Jentschura
Ulrich David
T.
Stöhlker
Thomas
S.
Fritzsche
Stephan
10.1103/PhysRevA.74.052710
Gesellschaft für Schwerionenforschung (GSI), D-64291 Darmstadt, Germany
Institut für Physik, Universität Kassel, D-34132 Kassel, Germany
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 15:50:49.830778
©2006 The American Physical Society
oai:edoc.mpg.de:2995012007-09-2037:954
Article
Adiabatic Approximation of the Correlation Function in the Density-Functional Treatment of Ionization Processes
English
2006-11-15
1
4
203001
Physical Review Letters
Phys. Rev. Lett.
97
The ionization of a one-dimensional model helium atom in short laser pulses using time-dependent density-functional theory is investigated. We calculate ionization probabilities as a function of laser intensity by approximating the correlation function of the system adiabatically with an explicit dependence on the fractional number of bound electrons. For the correlation potential we take the derivative discontinuity at integer numbers of bound electrons explicitly into account. This approach reproduces ionization probabilities from the solution of the time-dependent Schrödinger equation, in particular, the so-called knee due to nonsequential ionization.
expertsonly
published
joureview
F.
Wilken
Florian
D.
Bauer
Dieter
10.1103/PhysRevLett.97.203001
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-20 14:05:10.35554
©2006 The American Physical Society
oai:edoc.mpg.de:2995102007-02-2637:954
Article
Relativistic ionization rescattering with tailored laser pulses
English
2006-11-29
1
4
051803
Physical Review A
Phys. Rev. A
74
The interaction of relativistically strong tailored laser pulses with an atomic system is considered. Due to special tailoring of the laser pulse, the suppression of the relativistic drift of the ionized electron and a dramatic enhancement of the rescattering probability is shown to be achievable. The high harmonic generation rate in the relativistic regime is calculated and shown to be increased by several orders of magnitude compared to the case of conventional laser pulses. The energies of the revisiting electron at the atomic core can approach the MeV domain, thus rendering hard x-ray harmonics and nuclear reactions with single atoms feasible.
expertsonly
published
joureview
M.
Klaiber
Michael
K. Z.
Hatsagortsyan
Karen Zaven
C. H.
Keitel
Christoph Helmut
10.1103/PhysRevA.74.051803
Theoretische Quantendynamik, Physikalisches Institut der Albert-Ludwigs-Universität, Hermann-Herder-Strasse 3, D-79104, Freiburg, Germany
MPI für Kernphysik
Group of C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2007
2007-02-26 13:28:04.170021
©2006 The American Physical Society
oai:edoc.mpg.de:2995112007-09-1837:954
Article
Collisionless energy absorption in the short-pulse intense laser-cluster interaction
English
2006-12-11
1
11
063202
Physical Review A
Phys. Rev. A
74
In a previous paper [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by means of three-dimensional particle-in-cell simulations and a simple rigid-sphere model that nonlinear resonance absorption is the dominant collisionless absorption mechanism in the intense, short-pulse laser cluster interaction. In this paper we present a more detailed account of the matter. In particular we show that the absorption efficiency is almost independent of the laser polarization. In the rigid-sphere model, the absorbed energy increases by many orders of magnitude at a certain threshold laser intensity. The particle-in-cell results display maximum fractional absorption around the same intensity. We calculate the threshold intensity and show that it is underestimated by the common overbarrier ionization estimate.
expertsonly
published
joureview
M.
Kundu
Mrityunjay
D.
Bauer
Dieter
10.1103/PhysRevA.74.063202
MPI für Kernphysik
Independent Research Groups
Many-Particle Quantum Dynamics (D. Bauer)
2007
2007-09-18 13:53:38.058836
©2006 The American Physical Society
oai:edoc.mpg.de:2995192007-02-2637:954
Article
Light propagation through closed-loop atomic media beyond the multiphoton resonance condition
English
2006-12-26
1
10
063827
Physical Review A
Phys. Rev. A
74
The light propagation of a probe field pulse in a four-level double-lambda type system driven by laser fields that form a closed interaction loop is studied. The finite frequency width of the probe pulse requires a time-dependent analysis beyond the multiphoton resonance assumption. We apply a Floquet decomposition to the equations of motion to solve this time-dependent problem and to identify the different scattering processes contributing to the medium response. We find that the response oscillating in phase with the probe field is phase-independent. The phase dependence arises from a scattering of the coupling fields into the probe field mode at a frequency which in general differs from the probe field frequency. In particular for short pulses with a large frequency width, inducing a closed loop interaction contour may lead to a distortion of the pulse shape via this phase-sensitive scattering. Finally, we demonstrate that both the closed loop and the nonclosed loop configuration allow for sub- and superluminal light propagation with small absorption or even gain, where one of the coupling field Rabi frequencies acts as a control parameter that enables one to switch between sub- and superluminal light propagation.
expertsonly
published
joureview
M.
Mahmoudi
Mohammad
J.
Evers
Jörg
10.1103/PhysRevA.74.063827
Physics Department, Zanjan University, P.O. Box 45195-313, Zanjan, Iran
MPI für Kernphysik
Group of C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2007
2007-02-26 13:24:14.965583
©2006 The American Physical Society
oai:edoc.mpg.de:2995242008-03-0337:954
Article
Two-loop Bethe logarithms for non-S levels
English
2006-12-29
1
13
062517
Physical Review A
Phys. Rev. A
74
Two-loop Bethe logarithms are calculated for excited P and D states in hydrogenlike systems, and estimates are presented for all states with higher angular momenta. These results complete our knowledge of the P and D energy levels in hydrogen at the order of α⁸m<sub>e</sub>c₂, where m<sub>e</sub> is the electron mass and c is the speed of light, and scale as Z⁶, where Z is the nuclear charge number. Our analytic and numerical calculations are consistent with the complete absence of logarithmic terms of order (α/π)²(Zα)⁶ ln[(Zα)<sup>−2</sup>]m<sub>e</sub>c² for D states and all states with higher angular momenta. For higher excited P and D states, a number of poles from lower-lying levels have to subtracted in the numerical evaluation. We find that, surprisingly, the corrections of the “squared decay-rate type” are the numerically dominant contributions in the order (α/π)²(Zα)⁶m<sub>e</sub>c² for states with large angular momenta, and provide an estimate of the entire B₆₀ coefficient for Rydberg states with high angular momentum quantum numbers. Our results reach the predictive limits of the quantum electrodynamic theory of the Lamb shift.
expertsonly
published
joureview
U. D.
Jentschura
Ulrich David
10.1103/PhysRevA.74.062517
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2007
2008-03-03 15:48:29.411401
©2006 The American Physical Society
oai:edoc.mpg.de:3357122008-03-0137:954
Article
Model calculations of photoemission from a surface-deposited fullerene monolayer
English
2007-12-28
4617
4624
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B-At. Mol. Opt. Phys.
24
40
Automatic journal name synchronization
No
expertsonly
published
joureview
O.
Kidun
O.
D.
Bauer
D.
N.
Fominykh
N.
J.
Berakdar
J.
000251797300006
0953-4075
Univ Halle Wittenberg, Inst Phys, D-06120 Halle, Germany.
MPI für Kernphysik
Group of C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
MPI für Mikrostrukturphysik
2008
2008-03-01 20:08:13.334967
oai:edoc.mpg.de:3358652008-03-0337:954
Article
Applicability of layered sine-Gordon models to layered superconductors: II. The case of magnetic coupling
English
2007-12-12
496211
Journal of Physics-Condensed Matter
J. Phys.-Condes. Matter
49
19
expertsonly
published
joureview
I.
Nandori
I.
K.
Vad
K.
S.
Meszaros
S.
U. D.
Jentschura
U. D.
S.
Nagy
S.
K.
Sailer
K.
000251797700012
0953-8984
Inst Nucl Res, H-4001 Debrecen, Hungary.; NIST, Gaithersburg, MD 20899 USA.; Univ Debrecen, Dept Theoret Phys, Debrecen, Hungary.
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
2008
2008-03-03 15:01:54.278695
oai:edoc.mpg.de:3359712008-03-0137:954
Article
Nonperturbative resonant strong field ionization of atomic hydrogen
English
2007-11-14
4165
4178
Journal of Physics B-Atomic Molecular and Optical Physics
J. Phys. B-At. Mol. Opt. Phys.
21
40
Automatic journal name synchronization
expertsonly
published
joureview
M. G.
Girju
M. G.
K.
Hristov
K.
O.
Kidun
O.
D.
Bauer
D.
000250688100006
0953-4075
MPI für Kernphysik
Group of C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2008
2008-03-01 20:08:13.471313
oai:edoc.mpg.de:3359732008-03-0137:954
Article
Enhancement of entanglement for two-mode fields generated from four-wave mixing with the help of the auxiliary atomic transition
English
2007-11
053827
Physical Review A
Phys. Rev. A
5
76
Automatic journal name synchronization
expertsonly
published
joureview
G. X.
Li
G. X.
H. T.
Tan
H. T.
M.
Macovei
M.
000251326400166
1050-2947
Huazhong Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
MPI für Kernphysik
Group of C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2008
2008-03-01 20:08:13.526267
oai:edoc.mpg.de:3359752010-09-2937:954
Article
Zeeman splitting and g factor of the 1s<sup>2</sup>2s<sup>2</sup>2p <sup>2</sup>P<sub>3/2</sub> and <sup>2</sup>P<sub>1/2</sub> levels in Ar<sup>13+</sup>
English
2007-11
052501
Physical Review A
Phys. Rev. A
5
76
expertsonly
published
joureview
R.
Soria Orts
R.
J. R.
Crespo López-Urrutia
J. R.
H.
Bruhns
H.
A. J. G.
Martinez
A. J. G.
Z.
Harman
Z.
U. D.
Jentschura
U. D.
C. H.
Keitel
C. H.
A.
Lapierre
A.
H.
Tawara
H.
I. I.
Tupitsyn
I. I.
J.
Ullrich
J.
A. V.
Volotka
A. V.
000251326400060
1050-2947
St Petersburg State Univ, Dept Phys, St Petersburg 198504, Russia.
MPI für Kernphysik
Group of C.H. Keitel
Quantum Electrodynamics and High Precision Theory (U. D. Jentschura)
MPI für Kernphysik
Group of J. Ullrich
Electron Beam Ion Trap ( J.R. Crespo Lopez-Urrutia)
2008
2010-09-29 09:28:06.438662
oai:edoc.mpg.de:3359812008-03-0137:954
Article
Isomer triggering via nuclear excitation by electron capture
English
2007-10-26
172502
Physical Review Letters
Phys. Rev. Lett.
17
99
Automatic journal name synchronization
expertsonly
published
joureview
A.
Palffy
A.
J.
Evers
J.
C. H.
Keitel
C. H.
000250506000022
0031-9007
MPI für Kernphysik
Group of C.H. Keitel
Quantum Interferences and Collective Quantum Dynamics (J. Evers)
2008
2008-03-01 20:08:13.649547
oai:edoc.mpg.de:3359842008-03-0137:954
Article
Reconstruction of an arbitrarily polarized few-cycle laser pulse by two-dimensional streaking
English
2007-10
726
733
Laser Physics Letters
Laser Phys. Lett.
10
4
Automatic journal name synchronization
expertsonly
published
joureview
N. I.
Shvetsov-Shilovski
N. I.
S. P.
Goreslavski
S. P.
S. V.
Popruzhenko
S. V.
W.
Becker
W.
G. G.
Paulus
G. G.
000250301700004
1612-2011
Moscow Engn Phys Inst, R-115409 Moscow, Russia.; Max Born Inst, D-12489 Berlin, Germany.; Texas A&M Univ, Dept Phys, Coll Stn, College Stn, TX 77843 USA.
MPI für Kernphysik
Group of C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2008
2008-03-01 20:08:13.703435
oai:edoc.mpg.de:3359872008-03-0137:954
Article
Harmonic generation from laser-irradiated clusters
English
2007-09
033201
Physical Review A
Phys. Rev. A
3
76
Automatic journal name synchronization
expertsonly
published
joureview
M.
Kundu
M.
S. V.
Popruzhenko
S. V.
D.
Bauer
D.
000249786000103
1050-2947
Moscow State Engn Phys Inst, Moscow 115409, Russia.
MPI für Kernphysik
Group of C.H. Keitel
Many-Particle Quantum Dynamics (D. Bauer)
2008
2008-03-01 20:08:13.767323
oai:edoc.mpg.de:3359882008-03-0137:954
Article
Photon splitting in a laser field
English
2007-09
032103
Physical Review A
Phys. Rev. A
3
76
Automatic journal name synchronization
expertsonly
published
joureview
A.
Di Piazza
A.
A. I.
Milstein
A. I.
C. H.
Keitel
C. H.
000249786000028
1050-2947
Budker Inst Nucl Phys, Novosibirsk 630090, Russia.
MPI für Kernphysik
Group of C.H. Keitel
Relativistic Quantum Dynamics and High-Energy Processes (K. Hatsagortsyan)
2008
2008-03-01 20:08:13.831872
ResultSet_9KnPsWzkS8G_range_100-199