2020-10-20T16:19:20Zhttp://edoc.mpg.de/ac_p_oai.ploai:edoc.mpg.de:80282011-01-1734:200
Astrophysical and inertial-confinement-fusion plasmas generated with millijoule femtosecond laser pulses
Andiel, U.
Eidmann, K.
Witte, K.
Mancini, R.
Hakel, P.
expertsonly
By irradiating a target consisting of a thin aluminum slab buried in carbon with blue pedestal-free millijoule femtosecond laser pulses, it is shown that the aluminum slab can be isochorically (at constant volume) heated and thereby converted into a hot dense plasma. By analysing its K-shell emission, temperatures up to 500 eV are found. The experimentally observed increase in line-width with density is in accordance with theory. The long-standing issue of line shifting is resolved by demonstrating that there exists a real line shift increasing with increasing electron density as predicted by a recent theoretical investigation, and blending is a minor effect only.
2002
Article
http://edoc.mpg.de/8028
urn:ISSN:0950-0340
Journal of Modern Optics, v.49, 2615-2628 (2002)
en
oai:edoc.mpg.de:80322011-01-1934:199
Characterization of nonlocal gates
Hammerer, K.
Vidal, G.
Cirac, J. Ignacio
expertsonly
A nonlocal unitary transformation of two-qubits occurs when some Hamiltonian interaction couples them. Here we characterize the amount, as measured by time, of interaction required to perform two-qubit gates, when also arbitrarily fast, local unitary transformations can be applied on each qubit. The minimal required time of interaction, or interaction cost, defines an operational notion of the degree of nonlocality of gates. We characterize a partial order structure based on this notion. We also investigate the interaction cost of several communication tasks, and determine which gates are able to accomplish them. This classifies two-qubit gates into four categories, differing in their capability to transmit classical, as well as quantum, bits of information.
2002
Article
http://edoc.mpg.de/8032
urn:ISSN:1050-2947
Physical Review A, v.66, 062321-1-062321-13 (2002)
en
oai:edoc.mpg.de:80712011-01-1934:199
Characterization of Gaussian operations and distillation of Gaussian states
Giedke, Géza
Cirac, J. Ignacio
expertsonly
We characterize the class of all physical operations that transform Gaussian states to Gaussian states. We show that this class coincides with that of all operations that can be performed on Gaussian states using linear optical elements and homodyne measurements. For bipartite systems we characterize the processes that can be implemented by local operations and classical communication, as well as those that can be implemented using positive partial transpose preserving maps. As an application, we show that Gaussian states cannot be distilled by local Gaussian operations and classical communication. We also define and characterize positive (but not completely positive) Gaussian maps.
2002
Article
http://edoc.mpg.de/8071
urn:ISSN:1050-2947
Physical Review A, v.66, 032316 (2002)
en
oai:edoc.mpg.de:80762011-07-1134:196
A Nd:YAG Laser with short-term frequency stability at the Hertz-level
Nevsky, A. Y.
Eichenseer, M.
von Zanthier, J.
Walther, H.
expertsonly
We report on the frequency stabilisation of a Nd:YAG laser at 946 nm to the Hertz-level. The laser will be used for ultra- high resolution spectroscopy of the 5s(2) S-1(0) - 5s5p P-3(0) transition in In+ and will ultimately serve as a local oscillator of an optical frequency standard based on a single trapped indium ion. To resolve the extremely narrow S-1(0) - P- 3(0) resonance (natural linewidth 0.82 Hz) at 237 nm, the frequency-quadrupled Nd:YAG laser radiation has to be frequency stable at the Hertz-scale for measurement times up to several tens of seconds. We obtain the frequency stability of the laser by locking it onto an external reference cavity of high finesse, placed on an active vibration isolation platform. (C) 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/8076
urn:ISSN:0030-4018
Optics Communications, v.210, 91-100 (2002)
en
oai:edoc.mpg.de:80782005-02-2134:195
Amplification of tailored white-light continuum
Zeidler, Dirk
Witte, Thomas
Proch, Detlev
Motzkus, Marcus
expertsonly
The transfer of phase and amplitude modulation of the seed continuum in an optical parametric amplification process is investigated. A white-light continuum serves as the seed in non-collinear optical parametric amplification in the visible and is tailored by a liquid-crystal modulator (LCM) in a pulse shaper. The central wavelength of the output is tunable by about 75 nm with suitable LCM transmission functions. Two-color double pulses each with sub-40 fs duration are demonstrated. The relative carrier phase between the pulses is conserved during the amplification process and can be adjusted. Chirp can be imposed onto the sub-pulses. The control of the properties of the output pulses is achieved purely electronically within a few milliseconds and does not require mechanical readjustments.
2002
Article
http://edoc.mpg.de/8078
urn:ISSN:0946-2171
Applied Physics B-Lasers and Optics, v.74, S51-S56 (2002)
en
oai:edoc.mpg.de:80852011-01-1934:199
Controlling dynamical phases in quantum optics
Calarco, T
Jaksch, D
Cirac, J. Ignacio
Zoller, P
expertsonly
quantum information processing; quantum optical implementations
We review and compare several schemes for inducing precisely controlled quantum phases in quantum optical systems, We focus in particular on conditional dynamical phases, i.e. phases obtained via state- and time-dependent interactions between trapped two-level atoms and ions, We describe different possibilities for the kind of interaction to be exploited, including cold controlled collisions, electrostatic forces, and dipole-dipole interactions.
2002
Article
http://edoc.mpg.de/8085
urn:ISSN:1464-4266
Journal of Optics B-Quantum and Semiclassical Optics, v.4, S430-S436 (2002)
en
oai:edoc.mpg.de:81012005-02-2134:195
Ultrafast charge transfer via a conical intersection in dimethylaminobenzonitrile
Fuß, Werner
Pushpa, Kumbil Kutta
Rettig, Wolfgang
Schmid, Wolfram E.
Trushin, Sergei A.
expertsonly
The La-like S2 state (2A) of 4-(dimethylamino)benzonitrile was pumped at 267 nm in the gas phase at 130 degrees C. Nonresonant multiphoton ionization at 800 nm with mass-selective detection then probed the subsequent processes. Whereas ionization at the Franck-Condon geometry only gave rise to the parent ion, fragmentation increased on motion towards the charge-transfer (CT) state. This useful difference is ascribed to a geometry-dependent resonance in the ion. The time constants found are interpreted by ultrafast (approximate to 68 fs) relaxation through a conical intersection to both the CT and the Lb-type S1 state (1B). Then the population equilibrates between these two states within 1 ps. From there the molecule relaxes within 90 ps to a lower excited state which can only be a triplet state (T-n) and then decomposes within 300 ps. Previous experiments either investigated only 1B-->CT relaxation-which does not take place in the gas phase or nonpolar solvents for energetic reasons-or, starting from S2 excitation, typically had insufficient time resolution (>1 ps) to detect the temporary charge transfer. Only recently temporary population of the CT state was found in a nonpolar solvent (Kwok et al., J Phys. Chem. A, 2000, 104, 4188), a result fully consistent with our mechanism. We also show that S2-->S1 relaxation does not occur vertically but involves an intermediate strong geometrical distortion, passing through a conical intersection.
2002
Article
http://edoc.mpg.de/8101
urn:ISSN:1474-905X
Photochemical & Photobiological Sciences, v.1, 255-262 (2002)
en
oai:edoc.mpg.de:81322011-08-0434:200
A dispersionless Michelson interferometer for the characterization of attosecond pulses
Goulielmakis, E.
Nersisyan, G.
Papadogiannis, N. A.
Charalambidis, D.
Tsakiris, G. D.
Witte, K.
expertsonly
A novel application of a free-standing transmission grating as a beam splitter in a Michelson-type interferometer is described. The arrangement can operate in the XUV and soft X-ray spectral region and, therefore, it is well suited for the characterization of attosecond pulses. Using ray-tracing codes, we have analyzed three different setups in which spherical mirrors are employed in conjunction with the transmission grating and have investigated in detail their dispersive characteristics. It is shown that such an arrangement can be made to exhibit group-delay dispersion of similar to1 as(2) while it provides two co-propagating and converging beams.
2002
Article
http://edoc.mpg.de/8132
urn:ISSN:0946-2171
Applied Physics B-Lasers and Optics, v.74, 197-206 (2002)
en
oai:edoc.mpg.de:81662005-02-2134:195
Carbon isotopomers of tetrafluoroethylene: laser-induced synthesis and NMR spectroscopic characterization
Kühn-Velten, J. H.
Hägele, G.
Fuss, Werner
Hering, Peter
Ivanenko, Michail M.
expertsonly
NMR; C-13 NMR; 19F NMR; C-12/C-13 isotopomers; tetrafluoroethylene; spectral analysis; lineshape; peak top; WIN-DAISY; LAO-PC
Isotopically selective multiphoton dissociation of CHClF2 produced a mixture of C-12/C-13 isotopomeric tetrafluoroethylenes. Specific NMR parameters for each isotopomer and the composition of this mixture were obtained from C-13 and F-19 NMR spectra by spectral analysis using consecutively lineshape and peak top iteration methods. Copyright (C) 2001 John Wiley Sons, Ltd.
2002
Article
http://edoc.mpg.de/8166
urn:ISSN:0749-1581
Magnetic Resonance in Chemistry, v.40, 77-80 (2002)
en
oai:edoc.mpg.de:146302005-02-2134:199
Three-dimensional theory for interaction between atomic ensembles and free-space light
Duan, L. M.
Cirac, J. Ignacio
Zoller, P.
expertsonly
Atomic ensembles have shown to be a promising candidate for implementations of quantum information processing by many recently discovered schemes. All these schemes are based on the interaction between optical beams and atomic ensembles. For description of these interactions, one assumed either a cavity- QED model or a one-dimensional light propagation model, which is still inadequate for a full prediction and understanding of most of the current experimental efforts that are actually taken in the three-dimensional free space. Here, we propose a perturbative theory to describe the three-dimensional effects in interaction between atomic ensembles and free-space light with a level configuration important for several applications. The calculations reveal some significant effects that were not known before from the other approaches, such as the inherent mode-mismatching noise and the optimal mode-matching conditions. The three-dimensional theory confirms the collective enhancement of the signal-to-noise ratio which is believed to be one of the main advantages of the ensemble-based quantum information processing schemes, however, it also shows that this enhancement needs to be understood in a more subtle way with an appropriate mode-matching method.
2002
Article
http://edoc.mpg.de/14630
urn:ISSN:1050-2947
Physical Review A, v.66, 023818 (2002)
en
oai:edoc.mpg.de:146372005-03-0734:198
Optical kaleidoscope using a single atom
Horak, P.
Ritsch, H.
Fischer, Thomas
Maunz, Peter
Puppe, Thomas
Pinkse, Pepijn W. H.
Rempe, Gerhard
expertsonly
A new method to track the motion of a single particle in the field of a high-finesse optical resonator is analyzed. It exploits sets of near-degenerate higher-order Gaussian cavity modes, whose symmetry is broken by the position dependent phase shifts induced by the particle. Observation of the spatial intensity distribution outside the cavity allows direct determination of the particle's position. This is demonstrated by numerically generating a realistic atomic trajectory using a semiclassical simulation and comparing it to the reconstructed path. The path reconstruction itself requires no knowledge about the forces on the particle. Experimental realization strategies are discussed.
2002
Article
http://edoc.mpg.de/14637
urn:ISSN:0031-9007
Physical Review Letters, v.88, 043601 (2002)
en
oai:edoc.mpg.de:157032005-03-0734:196
Five Lectures on Dissipative Master Equations
Englert, Berthold-Georg
Morigi, Giovanna
expertsonly
After giving a heuristic derivation of the master equation that is commonly employed for modeling the dynamics of a damped harmonic oscillator, we focus on the algebraic properties of this master equation. In particular, we report the eigenvalues of its Liouville operator and the corresponding right and left eigenvectors. These tools are then used for a study of micromaser dynamics, where the harmonic oscillator is a privileged cavity mode of the radiation field. In addition to being damped, the mode is also driven by atoms that traverse the cavity one by one and interact strongly with the quantized radiation. The most important statistical properties of the exiting atoms are derived. For the sake of pedagogy, the treatment advances from the simple to the complicated, and the reader may benefit from numerous homework assignments.
Springer
2002
InBook
http://edoc.mpg.de/15703
Coherent Evolution in Noisy Environments, 55-106 (2002)
en
oai:edoc.mpg.de:157172005-02-2134:197
A Mercury-Ion Optical Clock
Bergquist, J. C.
Tanaka, U.
Drullinger, R. E.
Itano, W. M.
Wineland, D. J.
Diddams, S. A.
Hollberg, L.
Curtis, E. A.
Oates, C. W.
Udem, Th.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15717
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 99-106 (2002)
en
oai:edoc.mpg.de:157182011-07-1134:196
High Resolution Spectroscopy of a Single In+ Ion
Becker, Thomas
Eichenseer, Mario
Nevsky, Alexander Y.
Peik, Ekkehard
Schwedes, Christian
Skvortsov, M. N.
von Zanthier, Joachim
Walther, Herbert
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15718
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 107-114 (2002)
en
oai:edoc.mpg.de:157212005-02-2134:197
Optical Frequency Synthesis with Ultrashort Pulses
Udem, Thomas
Holzwarth, Ronald
Zimmermann, Marcus
Hänsch, Theodor W.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15721
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 125-133 (2002)
en
oai:edoc.mpg.de:157252011-07-1134:196
Narrow Linewidth Laser System for Precise Spectroscopy of the Indium Clock Transition
Nevsky, Alexander Y.
Eichenseer, Mario
von Zanthier, Joachim
Walther, Herbert
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15725
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 409-416 (2002)
en
oai:edoc.mpg.de:157282005-02-2134:197
Absolute Frequency Measurements of a Methane-Stabilized Transportable He-Ne Laser at 3.39 µm
Pokasov, Pavel V.
Holzwarth, Ronald
Udem, Thomas
Zimmermann, Marcus
Reichert, Jörg
Niering, Markus
Hänsch, Theodor W.
Dmitriyev, A. K.
Bagayev, S. N.
Lemonde, P.
Santarelli, G.
Laurent, P.
Abgrall, M.
Clairon, A.
Salomon, C.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15728
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 510-512 (2002)
en
oai:edoc.mpg.de:157302011-07-1134:197
Frequency Comparison of I2 Stabilized Lasers at 532 nm and Absolute Frequency Measurement of I2 Absorption Lines
Nevsky, Alexander Y.
Holzwarth, Ronald
Zimmermann, Marcus
Udem, Thomas
Hänsch, Theodor W.
von Zanthier, Joachim
Walther, Herbert
Pokasov, Pavel V.
Skvortsov, M. N.
Bagayev, S. N.
Schnatz, H.
Riehle, F.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/15730
Gill, P.: Proceedings of the 6th Symposium on Frequency Standards and Metrology, World Scientific, 521-523 (2002)
en
oai:edoc.mpg.de:169062005-04-0934:195
Programmable amplitude- and phase-modulated femtosecond laser pulses in the mid-infrared
Witte, Thomas
Zeidler, Dirk
Proch, Detlev
Kompa, Karl-Ludwig
Motzkus, Marcus
expertsonly
We present a scheme to produce programmable phase- and amplitude-modulated femtosecond laser pulses in the mid- infrared regime of 3-10 μm by difference frequency mixing. The 80-fs signal output of an optical parametric amplifier is shaped with a liquid-crystal mask and mixed in an AgGaS2 crystal with a temporally stretched idler pulse. Without changing the mechanical alignment, we produce programmable amplitude modulations and chirped pulses at λ = 3 μm with energy as high has thas 1 μJ. This scheme, further, allows the generation of controllable pulse sequences. The results are in good agreement with theoretical simulations. (C) 2002 Optical Society of America.
2002
Article
http://edoc.mpg.de/16906
urn:ISSN:0146-9592
Optics Letters, v.27, 131-133 (2002)
en
oai:edoc.mpg.de:169192005-02-2134:197
Continuous detection of an atom laser beam
Köhl, Michael
Hänsch, Theodor W.
Esslinger, Tilman
expertsonly
We have demonstrated a detection scheme for atom laser beams that allows for a continuous measurement of the atom density and readout of the data in real time. The atoms in the atom laser beam are transferred locally from the lower to the upper hyperfine ground state of 87Rb by coherent coupling and are subsequently detected by an absorption measurement. The detection does not affect the Bose-Einstein condensate in the magnetic trap or the atom laser beam outside the detection region.
2002
Article
http://edoc.mpg.de/16919
urn:ISSN:1050-2947
Physical Review A, v.65, 021606 (2002)
en
oai:edoc.mpg.de:169342005-02-2134:195
Teaching optimal control theory to distill robust pulses even under experimental constraints
Hornung, Thomas
Motzkus, Marcus
de Vivie-Riedle, Regina
expertsonly
Optimal control theory (OCT) has wide applicability in the quest for seeking optimal laser pulses in coherent control of quantum phenomena. We have revised OCT making it possible to distill robust electric fields realizable via femtosecond pulse-shaping technology. The simple pulse structures offer direct physical insight into the control mechanism and selectively isolate the most stable pathways involving only few frequencies. Moreover, a generalized functional makes a vital extension in including the laser system used in control experiments.
2002
Article
http://edoc.mpg.de/16934
urn:ISSN:1050-2947
Physical Review A, v.65, 021403 (2002)
en
oai:edoc.mpg.de:169442005-02-2134:199
Pair and γ-photon production from a thin foil confined by two laser pulses
Shen, Baifei F.
Meyer-ter-Vehn, Jürgen
expertsonly
Electron-positron and γ-photon production by high-intensity laser pulses is investigated for a special target geometry, in which two pulses irradiate a very thin foil (10-100 mn < skin depth) with same intensity from opposite sides. A stationary solution is derived describing foil compression between the two pulses. Circular polarization is chosen such that all electrons and positions rotate in the plane of the foil. We discuss the laser and target parameters required in order to optimize the γ photon and pair production rate. We find a γ- photon intensity of 7 x 1027/sr s and a positron density of 5 x 1022/cm3 when using two 330 fs, 7 x 1021W/cm2 laser pulses.
2002
Article
http://edoc.mpg.de/16944
urn:ISSN:1063-651X
Physical Review E, v.65, 016405 (2002)
en
oai:edoc.mpg.de:169452005-03-0734:200
Influence of laser pulse duration on relativistic channels
Delfin, C.
Lokhnygin, V.
Mauritsson, J.
Sjögren, A.
Wahlström, C. G.
Pukhov, Alexander
Tsakiris, George D.
expertsonly
A high-power (10 TW) laser is employed to generate relativistic channels in an underdense plasma. The lengths of the channels are measured by imaging the Thomson-scattered light, and the gas densities are determined through the forward Raman scattered light. The laser-pulse parameters are varied and their impact on the channel formation is studied. It is found that increasing the laser pulse duration in many cases produces longer channels, even as this implies reducing the laser peak power. A theoretical discussion is presented, proposing an explanation of the experimental results. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/16945
urn:ISSN:1070-664X
Physics of Plasmas, v.9, 937-940 (2002)
en
oai:edoc.mpg.de:169472005-03-0734:198
Deterministic single-photon source for distributed quantum networking
Kuhn, Axel
Hennrich, Markus
Rempe, Gerhard
expertsonly
A sequence of single photons is emitted on demand from a single three-level atom strongly coupled to a high-finesse optical cavity. The photons are generated by an adiabatically driven stimulated Raman transition between two atomic ground states, with the vacuum field of the cavity stimulating one branch of the transition, and laser pulses deterministically driving the other branch. This process is unitary and therefore intrinsically reversible, which is essential for quantum communication and networking, and the photons should be appropriate for all-optical quantum information processing.
2002
Article
http://edoc.mpg.de/16947
urn:ISSN:0031-9007
Physical Review Letters, v.89, 067901 (2002)
en
oai:edoc.mpg.de:169482011-08-0334:196
Sharpening accepted thermodynamic wisdom via quantum control: or cooling to an internal temperature of zero by external coherent control fields without spontaneous emission
Scully, Marlan O.
Aharonov, Yakir
Kapale, Kishore T.
Tannor, David J.
Süßmann, Georg
Walther, Herbert
expertsonly
Cooling of internal atomic and molecular states via optical pumping and laser cooling of the atomic velocity distribution, rely on spontaneous emission. The outstanding success of such examples, taken together with general arguments, has led to the widely held notion that radiative cooling requires spontaneous emission. We here show by specific examples and direct calculation, based primarily on breaking emission-absorption symmetry as in lasing without inversion, that cooling of internal states by external coherent control fields is possible. We also show that such coherent schemes allow us to practically reach absolute zero in a finite number of steps, in contrast to some statements of the third law of thermodynamics.
2002
Article
http://edoc.mpg.de/16948
urn:ISSN:0950-0340
Journal of Modern Optics, v.49, 2297-2307 (2002)
en
oai:edoc.mpg.de:169492005-03-0734:196
Quantum phenomena of single atoms
Walther, Herbert
expertsonly
JOHN WILEY & SONS INC
2002
Conference-Paper
http://edoc.mpg.de/16949
urn:ISSN:0065-2385
urn:ISBN:0-471-22291-7
Antoniou, I.: Dynamical Systems and Irreversibility: Proceedings of the XXI Solvay Conference on Physics, JOHN WILEY & SONS INC, 167-197 (2002)
en
oai:edoc.mpg.de:173632005-02-2134:199
Creation of a molecular condensate by dynamically melting a Mott insulator
Jaksch, D.
Venturi, V.
Cirac, J. Ignacio
Williams, C. J.
Zoller, P.
expertsonly
We propose the creation of a molecular Bose-Einstein condensate by loading an atomic condensate into an optical lattice and driving it into a Mott insulator with exactly two atoms per site. Molecules in a Mott insulator state are then created under well defined conditions by photoassociation with essentially unit efficiency. Finally, the Mott insulator is melted and a superfluid state of the molecules is created. We study the dynamics of this process and photoassociation of tightly trapped atoms.
2002
Article
http://edoc.mpg.de/17363
urn:ISSN:0031-9007
Physical Review Letters, v.89, 040402 (2002)
en
oai:edoc.mpg.de:173682005-03-0734:196
Narrowing of electromagnetically induced transparency resonance in a Doppler-broadened medium
Javan, Ali
Kocharovskaya, Olga
Lee, Hwang
Scully, Marlan O.
expertsonly
We derive an analytic expression for the linewidth of electromagnetically induced transparency (EIT) resonance in a Doppler-broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser-induced line narrowing effect described by Feld and Javan. In the limit of high intensity we recover the usual power-broadening case where the EIT linewidth is proportional to the intensity and inversely proportional to the Doppler width.
2002
Article
http://edoc.mpg.de/17368
urn:ISSN:1050-2947
Physical Review A, v.66, 013805 (2002)
en
oai:edoc.mpg.de:173722005-02-2134:199
Long-range interactions between two 2s excited hydrogen atoms
Jonsell, S.
Saenz, Alejandro
Froelich, P.
Forrey, R. C.
Côté, R.
Dalgarno, A.
expertsonly
The doubly excited 1Σg+ and 3Σu+ states of the H2 molecule converging to the H(n=2)+H(n'=2) limit have been calculated using explicitly correlated basis functions, giving accurate results out to a nuclear separation sufficiently large to apply asymptotic expansions for the potential energy. The autoionization widths have been obtained using the complex-scaling method. For nuclear separations larger than 22 a.u., asymptotic expressions for the interaction energies have been obtained from perturbation theory.
2002
Article
http://edoc.mpg.de/17372
urn:ISSN:1050-2947
Physical Review A, v.65, 042501 (2002)
en
oai:edoc.mpg.de:174112005-02-2134:197
Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
Greiner, M.
Mandel, O.
Esslinger, T.
Hänsch, T. W.
Bloch, I.
notspecified
For a system at a temperature of absolute zero, all thermal fluctuations are frozen out, while quantum fluctuations prevail. These microscopic quantum fluctuations can induce a macroscopic phase transition in the ground state of a many-body system when the relative strength of two competing energy terms is varied across a critical value. Here we observe such a quantum phase transition in a Bose-Einstein condensate with repulsive interactions, held in a three-dimensional optical lattice potential. As the potential depth of the lattice is increased, a transition is observed from a superfluid to a Mott insulator phase. In the superfluid phase, each atom is spread out over the entire lattice, with long-range phase coherence. But in the insulating phase, exact numbers of atoms are localized at individual lattice sites, with no phase coherence across the lattice; this phase is characterized by a gap in the excitation spectrum. We can induce reversible changes between the two ground states of the system.
2002
Article
http://edoc.mpg.de/17411
urn:ISSN:0028-0836
Nature, v.415, 39-44 (2002)
en
oai:edoc.mpg.de:174262005-02-2134:197
New determination of the electron's mass
Beier, T.
Haffner, H.
Hermanspahn, N.
Karshenboim, Savely G.
Kluge, H. J.
Quint, W.
Stahl, S.
Verdu, J.
Werth, G.
expertsonly
A new independent value for the electron's mass in units of the atomic mass unit is presented, m e = 0.0005485799092(4) u. The value is obtained from our recent measurement of the g factor of the electron in 12C5+ in combination with the most recent quantum electrodynamical (QED) predictions. In the QED corrections, terms of order α² were included by a perturbation expansion in Zα. Our total precision is three times better than that of the accepted value for the electron's mass.
2002
Article
http://edoc.mpg.de/17426
urn:ISSN:0031-9007
Physical Review Letters, v.88, 011603 (2002)
en
oai:edoc.mpg.de:175942005-02-2134:195
Direct Observation of Collisions by Laser Excitation of the Collision Complex
Rebentrost, Frank
Grosser, Joachim
expertsonly
AIP
2002
Conference-Paper
http://edoc.mpg.de/17594
Back, Christina A.: Spectral Line Shapes. 16th International Conference on Spectral Line Shapes, Volume 12, Berkeley, California 3-7 June 2002, AIP, 206-210 (2002)
en
oai:edoc.mpg.de:176132005-02-2134:197
Dissociation Dynamics of a H2+ Ionic Beam in Intense Laser Fields - High Resolution on the Fragments' Kinetic Energy
Figger, Hartmut
Pavičić, Domagoj
Hänsch, Theodor W.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17613
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 329-332 (2002)
en
oai:edoc.mpg.de:176142005-03-0734:198
Single-Atom Motion in Optical Cavity QED
Rempe, Gerhard
Fischer, Thomas
Maunz, Peter
Pinkse, Pepijn W. H.
Puppe, Thomas
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17614
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 176-183 (2002)
en
oai:edoc.mpg.de:176202011-07-2134:197
Speedy BEC in a Tiny Trap: Coherent Matter Waves on a Microchip
Reichel, Jakob
Hänsel, Wolfgang
Hommelhoff, Peter
Long, Romain
Rom, Tim
Steinmetz, Tilo
Hänsch, Theodor W.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17620
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 289-292 (2002)
en
oai:edoc.mpg.de:176262011-02-2834:197
Continuous Coherent Lyman-α Excitation of Atomic Hydrogen
Eikema, Kjeld S. E.
Pahl, Anette
Schatz, Birgit
Walz, Jochen
Hänsch, Theodor W.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17626
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 124-132 (2002)
en
oai:edoc.mpg.de:176292005-02-2134:197
Measuring the Frequency of Light with Ultra Short Pulses
Hänsch, Theodor W.
Holzwarth, Ronald
Zimmermann, Marcus
Udem, Thomas
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17629
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 88-96 (2002)
en
oai:edoc.mpg.de:176312005-03-0734:196
Cavity-QED with a Single Trapped 40Ca+-ion
Guthöhrlein, Gerhard R.
Keller, Matthias
Lange, Wolfgang
Walther, Herbert
Hayasaka, Kazuhiro
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/17631
Chu, Steven; Vuletić, Vladan; Kerman, Andrew J.; Chin, Cheng: Proceedings of the XV International Conference on Laser Spectroscopy, World Scientific, 349-352 (2002)
en
oai:edoc.mpg.de:176712005-02-2134:197
Laser Physics at the Limits
Figger, Hartmut
Meschede, Dieter
Zimmermann, Claus
expertsonly
Laser spectroscopy, atomic physics, frequency standards, metrology, optics, quantum optics
Springer
2002
Book
http://edoc.mpg.de/17671
urn:ISBN:3-540-42418-0
en
oai:edoc.mpg.de:181672005-03-0734:200
Comparative study of time-resolved K-shell spectra from aluminum plasmas generated by ultrashort laser pulses at 395 and 790 nm
Andiel, Ulrich
Eidmann, Klaus
Witte, Klaus
Uschmann, I.
Förster, E.
expertsonly
A comparative study of temporally and spectrally resolved K- shell emission from aluminum targets heated with 150 fs Ti:sapphire laser pulses at 790 and 395 nm is presented at an intensity of 5x1017 W/cm2. Whereas at 395 nm spectrally broad intense plasma lines and a weak K α line with durations (full width at half maximum) of 1-2 ps are observed, the spectrum at 790 nm shows weak narrow plasma lines and an intense K α line with durations of 3-5 ps. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/18167
urn:ISSN:0003-6951
Applied Physics Letters, v.80, 198-200 (2002)
en
oai:edoc.mpg.de:181942005-02-2134:195
White-light-induced fragmentation of toluene
Müller, Astrid M.
Witzel, Bernd
Uiterwaal, C. J. G. J.
Wanner, Jochen
Kompa, Karl-Ludwig
expertsonly
We investigate the influence of continuum generation on the photofragmentation dynamics of the toluene molecule. By sending an 80-fs Ti:sapphire laser beam through a 2-mm-thick CaF2 plate we show that even moderately broadened laser frequency spectra considerably increase the degree of fragmentation, while it is nearly absent without continuum generation. The measured broadening of the frequency spectra and the known Raman-active vibrational modes of toluene afford an explanation in terms of a stimulated Raman scattering scheme, in which the molecule absorbs large amounts of vibrational energy.
2002
Article
http://edoc.mpg.de/18194
urn:ISSN:0031-9007
Physical Review Letters, v.88, 023001 (2002)
en
oai:edoc.mpg.de:182232005-02-2134:195
Quantitative laser mass spectroscopy of sputtered versus evaporated metal atoms
Varoucha, Eftihia V.
Papadogiannis, Nektarios A.
Charalambidis, Dimitrios
Saenz, Alejandro
Schröder, Hartmut
Witzel, Bernd
expertsonly
We demonstrate that the presence of excited states in sputtered surface atoms after ion bombardment affects the measured ion yield of a subsequent post multiphoton-ionization processes. This effect was investigated using an advanced time-of-flight mass-spectroscopic technique. This work reports a comparison of two-photon ionization spectra of metallic atoms obtained from solid samples via sputtering and thermal evaporation that reveals the role of excited states. Furthermore we experimentally determine the cross sections for the two photon ionization processes of evaporated Mg, Zn, and In through quantitative ion yield measurement. Numerical configuration interaction calculations for Mg and Zn are presented and the resulting theoretical two-photon ionization cross sections are compared with the measured ones.
2002
Article
http://edoc.mpg.de/18223
urn:ISSN:1050-2947
Physical Review A, v.65, 012901 (2002)
en
oai:edoc.mpg.de:182452011-06-2734:196
Lasing without inversion via decay-induced coherence
Kocharovskaya, Olga
Matsko, Andrew B.
Rostovtsev, Yuri
expertsonly
Continuous wave lasing without population inversion based on interference of the spontaneous emission is shown to be possible in a closed four-level system coupled with field reservoir, in the absence of any coherent driving fields. Practical implementation of the scheme based on a pseudophotonic band-gap structure doped by three-level ions or semiconductor quantum dots is suggested.
2002
Article
http://edoc.mpg.de/18245
urn:ISSN:1050-2947
Physical Review A, v.65, 013803-013803 (2002)
en
oai:edoc.mpg.de:182552005-03-0734:200
L-band x-ray absorption of radiatively heated nickel
Chenais-Popovics, C.
Fajardo, M.
Gilleron, F.
Teubner, U.
Gauthier, J. C.
Bauche-Arnoult, C.
Bachelier, A.
Bauche, J.
Blenski, T.
Thais, F.
Perrot, F.
Benuzzi, A.
Turck-Chieze, S.
Chieze, J. P.
Dorchies, F.
Andiel, U.
Fölsner, W.
Eidmann, K.
expertsonly
Absorption of L-M and L-N transitions of nickel has been measured using point projection spectroscopy. The x-ray radiation from laser-irradiated gold cavities was used to heat volumetrically nickel foils "tamped with carbon" up to 20 eV. Experimental spectra have been analyzed with calculations based on the spin-orbit split arrays statistical approach and performed for each ionic species Ni5+ to Ni11+. Using a least- squares fit, this method provides an ion distribution broader than at local thermodynamic equilibrium, which is explained by spatial and temporal temperature gradients. A major improvement in the simulation of the absolute value of transmission is obtained with a resolved transition array statistical calculation that reproduces the experimental spectrum with the nominal areal mass density by taking into account the saturation of narrow lines.
2002
Article
http://edoc.mpg.de/18255
urn:ISSN:1063-651X
Physical Review E, v.65, 016413 (2002)
en
oai:edoc.mpg.de:182842005-02-2134:197
Hyperfine structure in hydrogen and helium ion
Karshenboim, Savely G.
Ivanov, Vladimir G.
expertsonly
QED theory of the hyperfine splitting of the 1s and 2s state in hydrogen isotopes and helium-3 ion is considered. We develop an accurate theory of a specific difference 8EHFS(2s) - EHFS(1s). We take into account higher-order QED and nuclear structure effects. In particular, we found the vacuum polarization contribution in order α(Zα)3 EF and examined the recoil contribution in order (Zα)3m/M and thus completed a calculation of the fourth order QED corrections. The higher-order nuclear structure contributions were also analysed. The theoretical predictions reported here are now of a higher accuracy than the experiment. The study of the difference provides the most accurate test (at a level of a part in 108) of the QED theory of its HFS up to date. The theory agrees with most of the experimental data. (C) 2002 Published by Elsevier Science B.V.
2002
Article
http://edoc.mpg.de/18284
urn:ISSN:0370-2693
Physics Letters B, v.524, 259-264 (2002)
en
oai:edoc.mpg.de:183002011-07-1134:197
Hydrogen atom interferometer with short light pulses
Heupel, T.
Mei, M.
Niering, M.
Gross, B.
Weitz, M.
Hänsch, T. W.
Borde, C. J.
expertsonly
We report the realization of a hydrogen atom interferometer experiment using light as the atomic beam splitter. The wave packets of hydrogen atoms excited to the metastable 2S state are coherently split up and later recombined with the help of intense nanosecond light pulses. The pulses are generated by a novel phase-coherent source. These experiments can be seen as a step towards a precision measurement of the recoil energy of a hydrogen atom when absorbing a photon and thus of ħ/mhydrogen.
2002
Article
http://edoc.mpg.de/18300
urn:ISSN:0295-5075
Europhysics Letters, v.57, 158-163 (2002)
en
oai:edoc.mpg.de:183182011-06-2734:199
Stochastic heating and acceleration of electrons in colliding laser fields in plasma
Sheng, Z. M.
Mima, K.
Sentoku, Y.
Jovanovic, M. S.
Taguchi, T.
Zhang, J.
Meyer-ter-Vehn, J.
expertsonly
We propose a mechanism that leads to efficient acceleration of electrons in plasma by two counterpropagating laser pulses. It is triggered by stochastic motion of electrons when the laser fields exceed some threshold amplitudes, as found in single- electron dynamics. It is further confirmed in particle-in-cell simulations. In vacuum or tenuous plasma, electron acceleration in the case with two colliding laser pulses can be much more efficient than with one laser pulse only. In plasma at moderate densities, such as a few percent of the critical density, the amplitude of the Raman-backscattered wave is high enough to serve as the second counterpropagating pulse to trigger the electron stochastic motion. As a result, even with one intense laser pulse only, electrons can be heated up to a temperature much higher than the corresponding laser ponderomotive potential.
2002
Article
http://edoc.mpg.de/18318
urn:ISSN:0031-9007
Physical Review Letters, v.88, 055004 (2002)
en
oai:edoc.mpg.de:185622011-03-2534:196
Probing an Optical Field with Atomic Resolution
Guthöhrlein, Gerhard R.
Keller, Matthias
Lange, Wulfhard
Walther, Herbert
expertsonly
Springer
2002
InBook
http://edoc.mpg.de/18562
Laser Physics at the Limits, 225-232 (2002)
oai:edoc.mpg.de:185642005-03-0734:200
MeV Electrons and Positrons from a Femtosecond Table-Top Laser system
Witte, Klaus J.
Tsakiris, George D.
Gahn, Christoph
Pretzler, Georg
expertsonly
Springer
2002
InBook
http://edoc.mpg.de/18564
Laser Physics at the Limits, 381-393 (2002)
oai:edoc.mpg.de:185662005-02-2134:197
Small Molecules in Intense Laser Fields - Dissociation and Stabilisation
Figger, Hartmut
Pavicic, Domagoj
Sändig, Karsten
expertsonly
Springer
2002
InBook
http://edoc.mpg.de/18566
Laser Physics at the Limits, 395-408 (2002)
oai:edoc.mpg.de:185722005-04-1334:197
Atomic Looping
Reichel, Jakob
Hänsel, Wolfgang
expertsonly
Springer
2002
InBook
http://edoc.mpg.de/18572
Laser Physics at the Limits, 471-475 (2002)
oai:edoc.mpg.de:186242005-02-2134:195
Two aspects of ultrafast photodynamics: molecular photo- ionization and coherent control of molecular fragmentation and photoreactions involving conical intersections
Müller, Astrid M.
Kompa, Karl-Ludwig
expertsonly
2002
Article
http://edoc.mpg.de/18624
urn:ISSN:0950-0340
Journal of Modern Optics, v.49, 627-633 (2002)
en
oai:edoc.mpg.de:186282005-02-2134:195
Single-shot femtosecond coherent anti-Stokes Raman-scattering thermometry
Lang, Tobias
Motzkus, Marcus
expertsonly
A new time-domain single-shot detection technique based on nonresonant femtosecond coherent anti-Stokes Raman scattering is introduced for the determination of temperatures in flames and combustion processes, Chirped probe pulses are used to map the time evolution of the molecular dynamics initiated by a pump and a Stokes pulse onto the spectrum of the coherent anti- Stokes Raman-scattering signal pulses. An analytical description of this mapping process is given, which specifies ranges of linear and nonlinear time-frequency mapping, and an experimental realization is presented for single-shot thermometry on H2. (C) 2002 Optical Society of America.
2002
Article
http://edoc.mpg.de/18628
urn:ISSN:0740-3224
Journal of the Optical Society of America B-Optical Physics, v.19, 340-344 (2002)
en
oai:edoc.mpg.de:186332005-02-2134:197
Optical frequency metrology
Udem, Thomas
Holzwarth, Ronald
Hänsch, Theodor W.
expertsonly
2002
Article
http://edoc.mpg.de/18633
urn:ISSN:0028-0836
Nature, v.416, 233-237 (2002)
en
oai:edoc.mpg.de:186912005-02-2134:197
Growth of Bose-Einstein condensates from thermal vapor
Köhl, Michael
Davis, M. J.
Gardiner, C. W.
Hänsch, Theodor W.
Esslinger, Tilman
expertsonly
We report on a quantitative study of the growth process of 87Rb Bose-Einstein condensates. By continuous evaporative cooling we directly control the thermal cloud from which the condensate grows. We compare the experimental data with the results of a theoretical model based on quantum kinetic theory. We find quantitative agreement with theory for the situation of strong cooling, whereas in the weak cooling regime a distinctly different behavior is found in the experiment.
2002
Article
http://edoc.mpg.de/18691
urn:ISSN:0031-9007
Physical Review Letters, v.88, 080402 (2002)
en
oai:edoc.mpg.de:189202005-03-0734:200
Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system
Gahn, C.
Tsakiris, G. D.
Pretzler, G.
Witte, K. J.
Thirolf, P.
Habs, D.
Delfin, C.
Wahlstrom, C. G.
expertsonly
In experiments, the feasibility was demonstrated of generating multi-MeV electrons in a form of a collimated beam utilizing a table-top laser system delivering 200 fs pulses with PL=1.2 TW and 10 Hz capability. The method uses the process of relativistic self-channeling in a high-density gas jet producing electron densities in the range of 3x1019-6x1020 cm-3. In a thorough investigation, angularly resolved and absolutely calibrated electron spectra were measured and their dependence on the plasma density, laser intensity, and gas medium was studied. For the optimum electron density of ne=2x1020cm-3 the effective temperature of the electron energy distribution and the channel length exhibit a maximum of 5 MeV and 400 μm respectively. The laser-energy to-MeV- electron efficiency is estimated to be 5%. In a second step, utilizing the multi-MeV electron beam anti-particles, namely positrons, were successfully generated in a 2 mm Pb converter. The average intensity of this new source of positrons is estimated to be equivalent to a radioactivity of 2x108 Bq and it exhibits a very favorable scaling for higher laser intensities. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/18920
urn:ISSN:1070-664X
Physics of Plasmas, v.9, 987-999 (2002)
en
oai:edoc.mpg.de:189222005-03-0734:196
Identification and application of quantum trajectories in above-threshold ionization
Paulus, G. G.
Grasbon, F.
Walther, H.
Kopold, R.
Becker, W.
expertsonly
We discuss two recent photoionization experiments with atoms in intense laser fields: First we study the dependence of photoelectron spectra on the intensity of the laser pulse. In a second experiment a photoelectron spectrum for elliptical polarization is discussed. With a quantum mechanical model the contribution of specific electron trajectories to the photoelectron spectra can be analyzed. In the presented cases, trajectories with long travel times are of significant importance. Despite of the distinctive quantum nature of the effects, some key features can be explained by classical electron trajectories.
2002
Article
http://edoc.mpg.de/18922
urn:ISSN:1054-660X
Laser Physics, v.12, 262-267 (2002)
en
oai:edoc.mpg.de:189232005-03-0734:196
The mapping of surface plasmons with an apertureless scanning near-field optical microscope
Krieger, Wolfgang
expertsonly
Surface plasmon polaritons on thin Ag films are imaged using a simple apertureless scanning nearfield optical microscope based on a scanning-tunneling-microscope setup. The surface plasmons are excited in the Kretschmann configuration using He-Ne-laser radiation at 633 nm. The reflection of surface plasmons from differently shaped surface steps is investigated by studying the interference patterns formed by the incident and reflected waves. Reflection from rising and falling steps is compared, and reflection coefficients are determined. Plasmon reflection from a corner mirror and focusing from a concave mirror are demonstrated.
2002
Article
http://edoc.mpg.de/18923
urn:ISSN:1054-660X
Laser Physics, v.12, 287-291 (2002)
en
oai:edoc.mpg.de:196702005-02-2134:199
Fermionizing a small gas of ultracold bosons
Paredes, Belen
Zoller, P.
Cirac, J. Ignacio
expertsonly
We study the physics of a rapidly rotating gas of ultracold atomic bosons, with an internal degree of freedom. We show that in the limit of rapid rotation of the trap the problem exactly maps onto that of noninteracting fermions with spin in the lowest Landau level. The spectrum of the real bosonic system is identical to the one of the effective fermions, with the same eigenvalues and the same density of states. When the ratio of the number of atoms to the spin degeneracy is an integer number, the ground state for the effective fermions is an integer quantum Hall state. The corresponding bosonic state is a fractional quantum Hall liquid whose filling factor ranges in the sequence ν=1/2,2/3,3/4,..., as the spin degeneracy increases. Anyons with 1/2,1/3,1/4,... statistics can be created by inserting lasers with the appropriate polarizations. A special situation appears when the spin degeneracy equals the number of atoms in the gas. The ground state is then the product of a completely antisymmetric spin state and a ν=1 Laughlin state. In this case the system exhibits fermionic excitations with fermionic statistics although the real components are bosonic atoms.
2002
Article
http://edoc.mpg.de/19670
urn:ISSN:1050-2947
Physical Review A, v.66, 033609 (2002)
en
oai:edoc.mpg.de:196712005-02-2134:197
Condensed-matter physics - Rabi flopping sees the light
Udem, Thomas
expertsonly
2002
Article
http://edoc.mpg.de/19671
urn:ISSN:0028-0836
Nature, v.420, 469-472 (2002)
en
oai:edoc.mpg.de:196722005-03-0734:198
Optical Cavity QED: Fundamentals and application as a single-photon light source
Kuhn, Axel
Rempe, Gerhard
expertsonly
IOS Press
2002
Conference-Paper
http://edoc.mpg.de/19672
De Martini, F.; Monroe, C.: Experimental Quantum Computation and Information. Proceedings of the International School of Physics "Enrico Fermi" Course CXLVIII, IOS Press, 37-66 (2002)
en
oai:edoc.mpg.de:196922005-02-2134:195
Ultrafast [2+2]-cyclo addition in norbornadiene
Fuß, Werner
Pushpa, Kumbil Kutta
Schmid, Wolfram E.
Trushin, Sergei A.
expertsonly
Excitation of norbornadiene (bicyclo[2.2.1]hepta-2,5-diene) at 200 nm populates two States in parallel, the second ππ* state and a Rydberg state. We monitored both populations by transient nonresonant ionization. From the ππ* state the molecule relaxes in consecutive steps with time constants 5, 31 and 55 fs down to the ground-state surface, whereas the Rydberg population merges to the other path oil the ππ* surface within 420 fs. The relaxation steps are discussed in terms of conical intersections (Coins) between different surfaces. Information on them is inferred from known spectroscopy and, for the last Coln, from published calculations on Dewar benzene-->prismane conversion and on ethylene photodimerization for which norbornadiene with its two nonconjugated double bonds is a model. The calculation predicts symmetry breaking for this Coln, the two ethylenes forming a rhombus. Although this distortion is hindered in norbornadiene by ring strain, this Coln seems easily accessible as indicated by the short time (<55 fs) found for passing through it.
2002
Article
http://edoc.mpg.de/19692
urn:ISSN:1474-905X
Photochemical & Photobiological Sciences, v.1, 60-66 (2002)
en
oai:edoc.mpg.de:197782005-02-2134:197
Collapse and revival of the matter wave field of a Bose- Einstein condensate
Greiner, Markus
Mandel, Olaf
Hänsch, Theodor W.
Bloch, Immanuel
expertsonly
A Bose-Einstein condensate represents the most 'classical' form of a matter wave, just as an optical laser emits the most classical form of an electromagnetic wave. Nevertheless, the matter wave field has a quantized structure owing to the granularity of the discrete underlying atoms. Although such a field is usually assumed to be intrinsically stable (apart from incoherent loss processes), this is no longer true when the condensate is in a coherent superposition of different atom number states(1-6). For example, in a Bose-Einstein condensate confined by a three-dimensional optical lattice, each potential well can be prepared in a coherent superposition of different atom number states, with constant relative phases between neighbouring lattice sites. It is then natural to ask how the individual matter wave fields and their relative phases evolve. Here we use such a set-up to investigate these questions experimentally, observing that the matter wave field of the Bose-Einstein condensate undergoes a periodic series of collapses and revivals; this behaviour is directly demonstrated in the dynamical evolution of the multiple matter wave interference pattern. We attribute the oscillations to the quantized structure of the matter wave field and the collisions between individual atoms.
2002
Article
http://edoc.mpg.de/19778
urn:ISSN:0028-0836
Nature, v.419, 51-54 (2002)
en
oai:edoc.mpg.de:197802005-03-0734:200
The use of high energy laser-plasma sources in soft X-ray contact microscopy of living biological samples
Batani, D.
Botto, C.
Moret, M.
Milani, M.
Lucchini, G.
Eidmann, Klaus
Cotelli, F.
Donin, C. L. L.
Poletti, G.
Ford, T.
Stead, A.
expertsonly
In this paper the results of an experiment on soft X-ray contact microscopy using a laser-plasma source are presented. A resolution of 50 nm has been achieved imaging pig sperm cells, while other specimens, such as algae and yeast cells, showed internal details, proving the technique to be a powerful tool for biological investigations. Original biological information has been obtained and the conditions for optimal image formation have been studied.
2002
Article
http://edoc.mpg.de/19780
urn:ISSN:1434-6060
European Physical Journal D, v.21, 167-179 (2002)
en
oai:edoc.mpg.de:198462005-03-0734:196
Generation of lattice structures of optical vortices
Dreischuh, Alexander
Chervenkov, Sotir
Neshev, Dragomir
Paulus, Gerhard G.
Walther, Herbert
expertsonly
We demonstrate experimentally the generation of square and hexagonal lattices of optical vortices and reveal their propagation in a saturable nonlinear medium. If the topological charges of the vortices have identical signs, the lattice exhibits rotation, whereas if their signs alternate between being the same and being opposite to each other, we observe stable propagation of the structures. In the nonlinear medium the lattices induce periodic modulation of the refractive index. Diffraction of a probe beam by this nonlinearity-induced periodic structure is observed. (C) 2002 Optical Society of America.
2002
Article
http://edoc.mpg.de/19846
urn:ISSN:0740-3224
Journal of the Optical Society of America B-Optical Physics, v.19, 550-556 (2002)
en
oai:edoc.mpg.de:198522005-02-2134:195
Optimal control of ground-state dynamics in polymers
Zeidler, D.
Frey, S.
Wohlleben, W.
Motzkus, M.
Busch, F.
Chen, T.
Kiefer, W.
Materny, A.
expertsonly
Coherent control of the vibrational dynamics in crystalline polydiacetylene is demonstrated by tailoring the Stokes pulse of a coherent anti-Stokes Raman scattering (CARS) setup in a feedback-controlled self-learning loop. The feedback signal is derived from the spectral distribution of the CARS signal. Controlled excitation of one mode and simultaneous extinction of all other modes with high efficiency is demonstrated. In addition, the relative phases of the three normal modes have been controlled allowing excitations of local modes and suggesting the possibility of ground state reaction control. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/19852
urn:ISSN:0021-9606
Journal of Chemical Physics, v.116, 5231-5235 (2002)
en
oai:edoc.mpg.de:198532005-02-2134:197
Muonium hyperfine structure and hadronic effects
Czarnecki, Andrzej
Eidelman, Simon I.
Karshenboim, Savely G.
expertsonly
A new result for the hadronic vacuum polarization correction to the muonium hyperfine splitting (HFS) is presented: Δν(had-vp)=(0.233±0.003) kHz. Compared with previous calculations, the accuracy is improved by using the latest data on e+ e- --> hadrons. The status of the QED prediction for HFS is discussed.
2002
Article
http://edoc.mpg.de/19853
urn:ISSN:0556-2821
Physical Review D, v.65, 053004 (2002)
en
oai:edoc.mpg.de:198562005-02-2134:199
Laser wake field acceleration: the highly non-linear broken- wave regime
Pukhov, A.
Meyer-ter-Vehn, J.
expertsonly
We use three-dimensional particle-in-cell simulations to study laser wake field acceleration (LWFA) at highly relativistic laser intensities. We observe ultra-short electron bunches emerging from laser wake fields driven above the wave-breaking threshold by few-cycle laser pulses shorter than the plasma wavelength. We find a new regime in which the laser wake takes the shape of a solitary plasma cavity. It traps background electrons continuously and accelerates them. We show that 12-J, 33-fs laser pulses may produce bunches of 3 x 1010 electrons with energy sharply peaked around 300 MeV. These electrons emerge as low-emittance beams from plasma layers just 700-µm thick. We also address a regime intermediate between direct laser acceleration and LWFA, when the laser-pulse duration is comparable with the plasma period.
2002
Article
http://edoc.mpg.de/19856
urn:ISSN:0946-2171
Applied Physics B-Lasers and Optics, v.74, 355-361 (2002)
en
oai:edoc.mpg.de:198592005-03-0734:196
Secure communication with a publicly known key
Beige, Almut
Englert, Berthold-Georg
Kurtsiefer, Christian
Weinfurter, Harald
expertsonly
We present a scheme for direct and confidential communication between Alice and Bob, where there is no need for establishing a shared secret key first, and where the key used by Alice even will become known publicly. The communication is based on the exchange of single photons and each and every photon transmits one bit of Alice's message without revealing any information to a potential eavesdropper.
2002
Article
http://edoc.mpg.de/19859
urn:ISSN:0587-4246
Acta Physica Polonica A, v.101, 357-368 (2002)
en
oai:edoc.mpg.de:198672005-03-0734:196
Measuring irreversible dynamics of a quantum harmonic oscillator
Morigi, Giovanna
Solano, Enrique
Englert, Berthold-Georg
Walther, Herbert
expertsonly
We show that the unitary evolution of a harmonic oscillator coupled to a two-level system can be undone by a suitable manipulation of the two-level system-more specifically, by a quasi-instantaneous phase change. This enables us to isolate the dissipative evolution to which the oscillator may be exposed in addition. With this method we study the decoherence time of a photon mode in cavity QED, and that of the quantized harmonic motion of trapped ions. We comment on the relation to spin echoes and multipath interferometry.
2002
Article
http://edoc.mpg.de/19867
urn:ISSN:1050-2947
Physical Review A, v.65, 040102 (2002)
en
oai:edoc.mpg.de:198682011-01-2034:196
Reversing the Jaynes-Cummings dynamics to measure decoherence
Morigi, Giovanna
Solano, Enrique
Englert, Berthold-Georg
Walther, Herbert
expertsonly
decoherence; atoms interacting with light
We show that the Jaynes-Cummings dynamics can be undone by a Suitable manipulation of the two-level system-more specifically, by a quasi-instantaneous phase change. We discuss this effect in relation to decoherence measurements of a photon mode in cavity quantum electrodynamics and those of the quantized harmonic motion of trapped ions. We comment on the relation to spin echoes.
2002
Article
http://edoc.mpg.de/19868
urn:ISSN:1464-4266
Journal of Optics B-Quantum and Semiclassical Optics, v.4, S310-S312 (2002)
en
oai:edoc.mpg.de:198692005-03-0734:196
Phase-dependent interaction in a four-level atomic configuration
Morigi, Giovanna
Franke-Arnold, Sonja
Oppo, Gian-Luca
expertsonly
We study a four-level atomic scheme interacting with four lasers in a closed-loop configuration with a ◊ (diamond) geometry. We investigate the influence of the laser phases on the steady state. We show that, depending on the phases and the decay characteristic, the system can exhibit a variety of behaviors, including population inversion and complete depletion of an atomic state. We explain the phenomena in terms of multiphoton interference, and compare our results with the phase-dependent phenomena in the double-Λ scheme. This investigation may be useful for developing nonlinear optical devices, and for the spectroscopy and laser cooling of alkali- earth atoms.
2002
Article
http://edoc.mpg.de/19869
urn:ISSN:1050-2947
Physical Review A, v.66, 053409 (2002)
en
oai:edoc.mpg.de:198752005-02-2134:195
Mode-Selective Excitation of Polydiacetylene by Feedback-Controlled Pulse Shaping
Zeidler, Dirk
Frey, Susanne
Wohlleben, Wendel
Motzkus, Marcus
Busch, F.
Chen, T.
Kiefer, W.
Materny, A.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/19875
Douhal, A.; Santamaria, J.: Femtochemistry and Femtobiology: Ultrafast Dynamics in Molecular Science, World Scientific, 531-538 (2002)
en
oai:edoc.mpg.de:198762005-02-2134:195
IR Multiphoton Dissociation of Gas-Phase Metal Carbonyls by Femtosecond Pulses at 5 µm
Windhorn, Lars
Witte, Thomas
Proch, Detlev
Motzkus, Marcus
Kompa, Karl-Ludwig
Fuß, Werner
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/19876
Douhal, A.; Santamaria, J.: Femtochemistry and Femtobiology: Ultrafast Dynamics in Molecular Science, World Scientific, 53-60 (2002)
en
oai:edoc.mpg.de:198772005-02-2134:195
High Resolution Femtosecond CARS Spectroscopy
Frey, Hans M.
Beaud, Paul
Lang, Tobias
Motzkus, Marcus
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/19877
Douhal, A.; Santamaria, J.: Femtochemistry and Femtobiology: Ultrafast Dynamics in Molecular Science, World Scientific, 99-104 (2002)
en
oai:edoc.mpg.de:198802005-02-2134:195
Performance of Evolutionary Strategies in Coherent Control Studies
Zeidler, Dirk
Frey, Susanne
Kompa, Karl-Ludwig
Motzkus, Marcus
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/19880
Douhal, A.; Santamaria, J.: Femtochemistry and Femtobiology: Ultrafast Dynamics in Molecular Science, World Scientific, 524-530 (2002)
en
oai:edoc.mpg.de:198822005-02-2134:195
Molecular dissociation by mid-IR femtosecond pulses
Windhorn, Lars
Witte, Thomas
Yeston, Jake S.
Proch, Detlev
Motzkus, Marcus
Kompa, Karl-Ludwig
Fuß, Werner
expertsonly
By focusing a MIR femtosecond laser in a cell containing gas- phase metal carbonyls, the resonant infrared multiphoton dissociation of molecules was observed, Cr(CO)6, Mo(CO)6,W(CO)6, and Fe(CO)5 could easily be dissociated, which requires an excitation to at least v = 7 or 8 of the CO stretch vibration. After irradiation with ~150 fs pulses at 5 µm the metal carbonyl practically disappears in favor of free CO, as detected by the IR spectrum. By comparing the power dependence of the total conversion with a model, we can infer that only few vibrational degrees of freedom are involved in the excitation process. (C) 2002 Published by Elsevier Science B.V.
2002
Article
http://edoc.mpg.de/19882
urn:ISSN:0009-2614
Chemical Physics Letters, v.357, 85-90 (2002)
en
oai:edoc.mpg.de:203922005-03-0734:196
Generation and detection of Fock states of the radiation field
Walther, Herbert
expertsonly
quantum optics; nonclassical field states; entanglement and quantum nonlocality; foundation of quantum mechanics
Recent widely discussed applications in quantum information and quantum cryptography require radiation sources able to produce a fixed number of photons. In this paper we review the work performed in our laboratory to produce such fields on demand. Two different methods are described. The first one is based on the micromaser operating under the conditions of a trapping state. The second device uses a single ion in an optical cavity. The latter setup was recently realized in our laboratory.
2002
Article
http://edoc.mpg.de/20392
urn:ISSN:1464-4266
Journal of Optics B-Quantum and Semiclassical Optics, v.4, S418-S425 (2002)
en
oai:edoc.mpg.de:209892005-03-0734:196
Above-threshold ionization: From classical features to quantum effects
Becker, W.
Grasbon, Felix
Kopold, R.
Milošević, D. B.
Paulus, G. G.
Walther, Herbert
expertsonly
ACADEMIC PRESS INC
2002
InBook
http://edoc.mpg.de/20989
urn:ISSN:0065-2199
ADVANCES IN ATOMIC, MOLECULAR, AND OPTICAL PHYSICS, VOL 48, 35-98 (2002)
en
oai:edoc.mpg.de:210002005-03-0734:196
Ring dark solitary waves: Experiment versus theory
Dreischuh, Alexander
Neshev, D.
Paulus, Gerhard Georg
Grasbon, Felix
Walther, Herbert
expertsonly
Experimental results on optical ring dark solitary wave dynamics are presented, emphasizing the interplay between initial dark beam contrast, total phase shift, background-beam intensity, and saturation of the nonlinearity. The results are found to confirm qualitatively the existing analytical theory and are in agreement with the numerical simulations carried out.
2002
Article
http://edoc.mpg.de/21000
urn:ISSN:1063-651X
Physical Review E, v.66 (2002)
en
oai:edoc.mpg.de:210062005-03-0734:196
Dispersion Control in a 100-kHz-Repetition-Rate 35-fs Ti: Sapphire Regenerative Amplifier System
Lindner, Fabrizio
Paulus, Gerhard Georg
Grasbon, Felix
Dreischuh, Alexander
Walther, Herbert
expertsonly
dispersion control; femtosecond laser; high repetition rate; pulse shaping; regenerative amplifier; ultrafast optics
This paper presents a 100-kHz femtosecond amplifier system delivering pulses with a duration of 35 fs and an energy of 7 μJ. The system does not include a stretcher, since the large amount of dispersion accumulated during the amplification process is sufficient to prevent self-focusing. Compensation in approximately all orders is achieved through a combination of a prism compressor, chirped mirrors, and a liquid-crystal modulator, allowing the amplified pulses to be shortened to nearly the bandwidth limit.
2002
Article
http://edoc.mpg.de/21006
urn:ISSN:0018-9197
IEEE Journal of Quantum Electronics, v.38, 1465-1470 (2002)
en
oai:edoc.mpg.de:210352005-03-0734:196
Auf Feynmans Quantenpfaden: Atome im intensiven Laserfeld
Paulus, Gerhard G.
Grasbon, Felix
Walther, Herbert
Kopold, Richard
Becker, Wilhelm
expertsonly
Heute kann man Laserpulse erzeugen, deren Feldstärken diejenigen übertreffen, welche die Atome zusammen halten. In den letzten Jahren gelangen mithilfe des Feynmanschen Pfadintegrals große Fortschritte im Verständnis der Effekte, die durch die Wechselwirkung intensiver Laserpulse mit Atomen entstehen. Die begriffliche Nähe des Pfadintegralformalismus zu klassischen Trajektorien erlaubt in vielen Fällen sogar ein intuitives Verständnis des physikalischen Mechanismus.
2002
Article
http://edoc.mpg.de/21035
urn:ISSN:0031-9252
Physik in unserer Zeit, v.33, 74-81 (2002)
oai:edoc.mpg.de:210952005-03-0734:196
Cavity QED - experiments with atoms and ions
Walther, Herbert
expertsonly
IOS Press
2002
Conference-Paper
http://edoc.mpg.de/21095
urn:ISBN:1-58603-270-4
De Martini, F.; Monroe, C.: Experimental Quantum Computation and Information. Proceedings of the International School of Physics "Enrico Fermi", Course CXLVIII, IOS Press, 87-100 (2002)
en
oai:edoc.mpg.de:242092005-03-0734:196
Unsere heutige Zeitmessung - Wege zu einem neuen Standard
Walther, Herbert
expertsonly
2002
Article
http://edoc.mpg.de/24209
urn:ISSN:1617-5689
Praxis der Naturwissenschaften - Physik in der Schule, v.51, 8-15 (2002)
de
oai:edoc.mpg.de:242102005-03-0734:196
Quantenphysik und die Technologie im 21. Jahrhundert
Walther, Herbert
expertsonly
Verlag C. H. Beck
2002
InBook
http://edoc.mpg.de/24210
urn:ISSN:0084-6090
Bayerische Akademie der Wissenschaften, München: Jahrbuch der Bayerischen Akademie der Wissenschaften 2001, 93-126 (2002)
de
oai:edoc.mpg.de:242752005-03-0734:196
Quantenphänomene einzelner Photonen und Atome
Walther, Herbert
expertsonly
Kosmos
2002
InBook
http://edoc.mpg.de/24275
urn:ISBN:3-440-09583-5
Deutsches Museum, München: Von Zwergen und Quanten - Struktur und Technik des Kleinsten, 9-39 (2002)
de
oai:edoc.mpg.de:242772005-02-2134:197
Räderwerke für optische Uhren
Hänsch, Theodor W.
expertsonly
Kosmos
2002
InBook
http://edoc.mpg.de/24277
urn:ISBN:3-440-09583-5
Deutsches Museum, München: Von Zwergen und Quanten - Struktur und Technik des Kleinsten, 63-71 (2002)
de
oai:edoc.mpg.de:242782005-02-2134:197
Ultrafast Mode-locked Lasers for the Measurement of Laser Frequencies and as Optical Clockworks
Holzwarth, Ronald
Udem, Thomas
Hänsch, Theodor W.
expertsonly
SPIE
2002
InBook
http://edoc.mpg.de/24278
urn:ISBN:0-8194-4510-X
International Trends in Applied Optics, 23-43 (2002)
oai:edoc.mpg.de:242892011-07-2134:197
Microchip traps and Bose-Einstein condensation
Reichel, Jakob
expertsonly
The article gives an overview of the rapidly evolving field of magnetic microchip traps (also called 'atom chips') for neutral atoms. Special attention is given to Bose-Einstein condensation in such traps, to the particular properties of microchip trap potentials, and to practical considerations in their design. Scaling laws are developed, which lead to an estimate of the ultimate confinement that chip traps can provide. Future applications such as integrated atom interferometers are discussed.
2002
Article
http://edoc.mpg.de/24289
urn:ISSN:0946-2171
Applied Physics B-Lasers and Optics, v.74, 469-487 (2002)
en
oai:edoc.mpg.de:242902005-02-2134:197
Precision study of positronium and precision tests of the bound state quantum electrodynamics
Karshenboim, Savely G.
expertsonly
positronium; QED theory; atomic system
Despite its very short lifetime positronium provides us with a number of accurate tests of the bound state quantum electrodynamics (QED). In this note a brief overview of QED theory and precision experiments on the spectrum and annihilation decay of the positronium atom is presented. Special attention is paid to the accuracy of theoretical predictions. (C) 2002 Elsevier Science B.V. All rights reserved.
2002
Article
http://edoc.mpg.de/24290
urn:ISSN:0169-4332
Applied Surface Science, v.194, 307-311 (2002)
en
oai:edoc.mpg.de:242912005-03-0734:196
Quantum computation with trapped ions in an optical cavity
Pachos, Jiannis
Walther, Herbert
expertsonly
Two-qubit logical gates are proposed on the basis of two atoms trapped in a cavity setup and commonly addressed by laser fields. Losses in the interaction by spontaneous transitions are efficiently suppressed by employing adiabatic transitions and the quantum Zeno effect. Dynamical and geometrical conditional phase gates are suggested. This method provides fidelity and a success rate of its gates very close to unity. Hence, it is suitable for performing quantum computation.
2002
Article
http://edoc.mpg.de/24291
urn:ISSN:0031-9007
Physical Review Letters, v.89, 187903 (2002)
en
oai:edoc.mpg.de:242922005-02-2134:195
Realization of a time-domain Fresnel lens with coherent control
Degert, Jérôme
Wohlleben, Wendel
Chatel, Béatrice
Motzkus, Marcus
Girard, Bertrand
expertsonly
Perturbative chirped pulse excitation leads to oscillations of the excited state amplitude. These coherent transients are governed by interferences between resonant and off-resonant contributions. Control mechanisms in both frequency and time domain are used to modify these dynamics. First, by applying a phase step in the spectrum, we manipulate the phase of the oscillations. By direct analogy with Fresnel zone lenses, we then conceive highly phase-amplitude modulated pulse shapes that slice destructive interferences out of the excitation time structure and enhance the final population.
2002
Article
http://edoc.mpg.de/24292
urn:ISSN:0031-9007
Physical Review Letters, v.89, 203003 (2002)
en
oai:edoc.mpg.de:242932005-02-2134:195
Structure of the conical intersections driving the cis-trans photoisomerization of conjugated molecules
Sampedro Ruiz, Diego
Cembran, Alessandro
Garavelli, Marco
Olivucci, Massimo
Fuß, Werner
expertsonly
High-level ab initio calculations show that the singlet photochemical cis-trans isomerization of organic molecules under isolated conditions can occur according to two distinct mechanisms. These mechanisms are characterized by the different structures of the conical intersection funnels controlling photoproduct formation. In nonpolar (e.g. hydrocarbon) polyenes the lowest-lying funnel corresponds to a (CH)3 kink with both double and adjacent single bonds twisted, which may initiate hula-twist (HT) isomerization. On the other hand, in polar conjugated systems such as protonated. Schiff bases (PSB) the funnel shows a structure with just one twisted double bond. The ground-state relaxation paths departing from the funnels indicate that the HT motion may take place in nonpolar conjugated systems but also that the single-bond twist may be turned back, whereas in free conjugated polar molecules such as PSB a one-bond flip mechanism dominates from the beginning. The available experimental evidence either supports these predictions or is at least consistent with them.
2002
Article
http://edoc.mpg.de/24293
urn:ISSN:0031-8655
Photochemistry and Photobiology, v.76, 622-633 (2002)
en
oai:edoc.mpg.de:243902005-03-0734:198
Feedback on the motion of a single atom in an optical cavity
Fischer, T.
Maunz, P.
Pinkse, P. W. H.
Puppe, T.
Rempe, G.
expertsonly
We demonstrate feedback on the motion of a single neutral atom trapped in the light field of a high-finesse cavity. Information on the atomic motion is obtained from the transmittance of the cavity. This is used to implement a feedback loop in analog electronics that influences the atom's motion by controlling the optical dipole force exerted by the same light that is used to observe the atom. In spite of intrinsic limitations, the time the atom stays within the cavity could be extended by almost 30% beyond that of a comparable constant-intensity dipole trap.
2002
Article
http://edoc.mpg.de/24390
urn:ISSN:0031-9007
Physical Review Letters, v.88, 163002 (2002)
en
oai:edoc.mpg.de:244962005-02-2134:197
Uhrenvergleich auf der Femtosekundenskala
Udem, Thomas
Holzwarth, Ronald
Hänsch, Theodor W.
expertsonly
2002
Article
http://edoc.mpg.de/24496
urn:ISSN:1617-9439
Physik Journal, v.1, 39-45 (2002)
de
oai:edoc.mpg.de:245102005-02-2134:197
Precision Optical Frequency Metrology Using Pulsed Lasers
Udem, Thomas
Holzwarth, Ronald
Zimmermann, Marcus
Hänsch, Theodor W.
expertsonly
World Scientific
2002
Conference-Paper
http://edoc.mpg.de/24510
urn:ISBN:981-238-130-9
Ono, Yoshimasa A.; Fujikawa, Kazuo: Foundations of Quantum Mechanics in the Light of New Technology: Proceedings of the 7th International Symposium, World Scientific, 253-258 (2002)
en
oai:edoc.mpg.de:245112005-03-0734:196
Secure communication with single-photon two-qubit states
Beige, Almut
Englert, Berthold-Georg
Kurtsiefer, Christian
Weinfurter, Harald
expertsonly
We propose a cryptographic scheme that is deterministic: Alice sends single photons to Bob, and each and every photon detected supplies one key bit-no photon is wasted. This is in marked contrast to other schemes in which a random process decides whether the next photon sent will contribute to the key or not. The determinism is achieved by preparing the photons in two- qubit states, rather than the one-qubit states used in conventional schemes. In particular, we consider the realistic situation in which one qubit is the photon polarization and the other a spatial alternative. Further, we show how one can exploit the deterministic nature for direct secure communication, that is without the need-for establishing A shared key first.
2002
Article
http://edoc.mpg.de/24511
urn:ISSN:0305-4470
Journal of Physics A-Mathematical and General, v.35, L407-L413 (2002)
en
oai:edoc.mpg.de:245122005-03-0734:196
Communicating with Qubit Pairs
Beige, Almut
Englert, Berthold-Georg
Kurtsiefer, Christian
Weinfurter, Harald
expertsonly
CRC Press
2002
InBook
http://edoc.mpg.de/24512
urn:ISBN:1-58488-282-4
Mathematics of Quantum Computation, 359-401 (2002)
en
oai:edoc.mpg.de:245212005-03-0734:200
A novel tape target for use with repetitively pulsed lasers
Fill, Ernst
Bayerl, Josef
Tommasini, Riccardo
expertsonly
A compact tape drive applicable in experiments with repetitively pulsed lasers is described. By exposing fresh material to the laser pulse at each shot, it is possible to obtain up to 104 shots in a single run. A particular tape can be used many times. The tape target provides stable output, is easy to adjust, and is low cost in operation. The possibility of illuminating samples with the rear-side emission is a further advantage for many applications. Experiments are described in which a copper tape, 10 m long, 12 mm wide, and 25 μm thick, is used to generate Cu K α radiation. Applying 2 TW titanium-sapphire laser pulses, yields 2.7x109 K α photons/Sr per shot. Bragg and powder spectra generated with this radiation are shown. (C) 2002 American Institute of Physics.
2002
Article
http://edoc.mpg.de/24521
urn:ISSN:0034-6748
Review of Scientific Instruments, v.73, 2190-2192 (2002)
en
oai:edoc.mpg.de:245222005-02-2134:195
Collision photography: Imaging of ultrafast atomic processes
Grosser, J.
Hoffmann, O.
Rebentrost, F.
expertsonly
We study the laser excitation of atomic collision pairs in a differential scattering experiment. The interference structure in the differential cross-section is resolved and shows a considerable variation with the linear polarization of the laser light. A systematic analysis allows the accurate determination of the Condon vectors characterizing the optical transition. The method is thus capable to directly visualize geometric aspects of the collision event, very much like an everyday photography.
2002
Article
http://edoc.mpg.de/24522
urn:ISSN:0295-5075
Europhysics Letters, v.58, 209-214 (2002)
en
ResultSet_8Hnq38cDeTP_range_100-199