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  • 2000-2004  (4)
  • 1985-1989
  • 1980-1984
  • 1920-1924
  • 1870-1879
  • 2001  (4)
  • PACS. 03.75.Fi Phase coherent atomic ensembles; quantum condensation phenomena – 05.30.Jp Boson systems – 32.80.Pj Optical cooling of atoms; trapping  (2)
  • PACS. 31.70.Hq Time-dependent phenomena: excitation and relaxation processes, and reaction rates – 33.80.Wz Other multiphoton processes  (2)
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  • 2000-2004  (4)
  • 1985-1989
  • 1980-1984
  • 1920-1924
  • 1870-1879
Year
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 20 (2001), S. 451-467 
    ISSN: 1434-6036
    Keywords: PACS. 03.75.Fi Phase coherent atomic ensembles; quantum condensation phenomena – 05.30.Jp Boson systems – 32.80.Pj Optical cooling of atoms; trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We discuss the dynamics of two weakly coupled Bose-Einstein condensates in a double-well potential, contrasting the mean-field picture to the exact N-particle evolution. On the mean-field level, a self-trapping transition occurs when the scaled interaction strength exceeds a critical value; this transition essentially persists in small condensates comprising about 1000 atoms. When the double-well is modulated periodically in time, Floquet-type solutions to the nonlinear Schrödinger equation take over the role of the stationary mean-field states. These nonlinear Floquet states can be classified as “unbalanced” or “balanced”, depending on whether or not they entail long-time confinement of most particles to one well. Since the emergence of unbalanced Floquet states depends on the amplitude and frequency of the modulating force, we predict that the onset of self-trapping can efficiently be controlled by varying these parameters. This prediction is verified numerically by both mean-field and N-particle calculations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 17 (2001), S. 351-363 
    ISSN: 1434-6079
    Keywords: PACS. 03.75.Fi Phase coherent atomic ensembles; quantum condensation phenomena – 05.30.Jp Boson systems – 32.80.Pj Optical cooling of atoms; trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: An instanton method is proposed to investigate the quantum tunneling between two weakly-linked Bose-Einstein condensates confined in double-well potential traps. We point out some intrinsic pathologies in the earlier treatments of other authors and make an effort to go beyond these very simple zero order models. The tunneling amplitude may be calculated in the Thomas-Fermi approximation and beyond it; we find it depends on the number of the trapped atoms, through the chemical potential. Some suggestions are given for the observation of the Josephson oscillation and the MQST.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6079
    Keywords: PACS. 31.70.Hq Time-dependent phenomena: excitation and relaxation processes, and reaction rates – 33.80.Wz Other multiphoton processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We present simulations on pump-dump-probe experiments performed on the potassium dimer. The interaction of two time-delayed laser pulses prepares vibrational wave packets in the electronic ground state. The quantum calculations reveal to what extent it is possible to prepare a ground state superposition of states with high versus low vibrational quantum numbers by changing the pump-dump delay time. It is shown that transient signals may exhibit interference effects which are due to characteristics of ground state wave-packets composed of two components showing different vibrational dynamics. In this way the signals are able to yield information about vibrational overtone motion.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 15 (2001), S. 413-422 
    ISSN: 1434-6079
    Keywords: PACS. 31.70.Hq Time-dependent phenomena: excitation and relaxation processes, and reaction rates – 33.80.Wz Other multiphoton processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: A classical approach to simulate femtosecond pump-probe experiments is presented and compared to the quantum mechanical treatment. We restrict the study to gas-phase systems using the I2 molecule as a numerical example. Thus, no relaxation processes are included. This allows for a direct comparison between purely quantum mechanical results and those obtained from classical trajectory calculations. The classical theory is derived from the phase-space representation of quantum mechanics. Various approximate quantum mechanical treatments are compared to their classical counterparts. Thereby it is demonstrated that the representation of the radial density as prepared in the pump-process is most crucial to obtain reliable signals within the classical approach.
    Type of Medium: Electronic Resource
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