Open Quantum Systems

The behaviour of quantum mechanical systems is often strongly influenced by the coupling to their surroundings. While a complete microscopic description or control of the environment is not feasible in many cases, an open system's approach, which aims at a description in terms of a reduced set of dynamical variables, has proved to be extremely useful. The physics of open quantum systems plays a major role in experimental and theoretical developments of quantum mechanics. It allows numerous applications which range over many branches of modern physics, from fundamental question of quantum mechanics to technological applications in quantum information processing.

1. Decaying Systems

A simple example of an open quantum system is an atom which can ionise owing to the interaction with an external static or time-dependent field. Ionisation processes lead to decay within the state space of all bound states of the atom in this case. Ionisation can be triggered by tunnelling and also be enhance by underlying complex dynamics in classical phase space. We treat the decay of internal (electronic) degrees of freedoms as well as external (centre-of-mass) degrees of freedom. A useful technique to compute decay rates of open systems is complex scaling, which we applied to single-particle and mean-field problems.

Phase space of driven Rydberg atom Tunnelling rates of nondispersive wave packets


Resonance-assisted (a 5:1 resonance is marked by the arrow) tunnelling out of a regular phase-space island (left) and the corresponding ionisation rates as a function of the principal quantum number of the initial Rydberg state of a microwave-driven hydrogen atom (right).

2. Decoherence, Dissipation, and Noise

Decoherence plays a crucial role in many of our research areas. Decoherence is conceived as one way to make quantum objects behave classically, it (so far) protects cats from being instrumentalised for testing weird ideas of theoretical physicists, it is one of the fundamental problems to overcome before quantum computers will develop. Controlled decoherence and its impact on the particle dynamics in clean cut cold atom experiments is our main focus of research.

Phase space of driven Rydberg atom

















Publications

  • R. Labouvie, B. Santra, S. Heun, S. Wimberger, and H. Ott
    Negative differential conductivity in an interacting quantum gas, Phys. Rev. Lett. 115, 050601 (2015)
  • S. Micciche, A. Buchleitner, F. Lillo, R. Mantegna, T. Paul, and S. Wimberger
    Scale-free relaxation of a wave packet in a quantum well with power-law tails, NJP 15, 033033 (2013)
  • G. Kordas, S. Wimberger, and D. Witthaut
    Decay and fragmentation in an open Bose-Hubbard chain, Phys. Rev. A 87, 043618 (2013)
  • G. Kordas, S. Wimberger, and D. Witthaut
    Dissipation induced macroscopic entanglement in an open optical lattice, EPL 100, 30007 (2012)
  • N. Lörch, F. Pepe, H. Lignier, D. Ciampini, R. Mannella, O. Morsch, E. Arimondo, P. Facchi, G. Florio, S. Pascazio, and S. Wimberger
    Wave function renormalization effects in resonantly enhanced tunneling, Phys. Rev. A 85, 053602 (2012)
  • G. Tayebirad, R. Mannella, and S. Wimberger
    Engineering interband transport by time-dependent disorder, Phys. Rev. A 84, 031605(R) (2011)
  • D. Witthaut, F. Trimborn, H. Hennig, G. Kordas, T. Geisel, and S. Wimberger
    Beyond mean-field dynamics in open Bose-Hubbard chains, Phys. Rev. A 83, 063608 (2011)
  • K. Rapedius, C. Elsen, D. Witthaut, S. Wimberger, and K.-J. Korsch
    Nonlinear resonant tunneling of Bose-Einstein condensates in tilted optical lattices, Phys. Rev. A 82, 063601 (2010)
  • G. Tayebirad, A. Zenesini, D. Ciampini, R. Mannella, O. Morsch, E. Arimondo, N. Lörch, and S. Wimberger
    Time-resolved measurement of Landau--Zener tunneling in different bases, Phys. Rev. A 82, 013633 (2010)
  • A. Zenesini, H. Lignier, G. Tayebirad, J. Radogostowicz, D. Ciampini, R. Mannella, S. Wimberger, O. Morsch, and E. Arimondo
    Time-resolved measurement of Landau-Zener tunneling in periodic potentials, Phys. Rev. Lett. 103, 090403 (2009)
  • D. Witthaut, F. Trimborn, and S. Wimberger
    Dissipation-induced coherence and stochastic resonance of an open two-mode Bose-Einstein condensate, Phys. Rev. A 79, 033621 (2009)
  • D. Witthaut, F. Trimborn, and S. Wimberger
    Dissipation induced coherence of a two-mode Bose-Einstein condensate, Phys. Rev. Lett. 101, 200402 (2008)
  • M. Sadgrove, S. Wimberger, S. Parkins, and R. Leonhardt
    Scaling law and stability for a noisy quantum system, Phys. Rev. E 78, 025206(R) (2008)
  • F. Trimborn, D. Witthaut, and S. Wimberger
    Mean-field dynamics of a two-mode Bose-Einstein condensate subject to noise and dissipation, J. Phys. B 41, 171001(FTC) (2008)
  • A. Zenesini, C. Sias, H. Lignier, Y. Singh, D. Ciampini, O. Morsch, R. Mannella, E. Arimondo, A. Tomadin, and S. Wimberger
    Resonant tunneling of Bose-Einstein condensates in optical lattices, New J. Phys. 10, 053038 (2008)
  • A. Tomadin, R. Mannella, and S. Wimberger
    Many-body Landau-Zener tunneling in the Bose-Hubbard model, Phys. Rev. A 77, 013606 (2008)
  • A. Tomadin, R. Mannella, and S. Wimberger
    Many-body interband tunneling as a witness for complex dynamics in the Bose-Hubbard model, Phys. Rev. Lett. 98, 130402 (2007)
  • C. Sias, A. Zenesini, H. Lignier, S. Wimberger, D. Ciampini, O. Morsch, and E. Arimondo
    Resonantly enhanced tunneling of Bose-Einstein condensates in periodic potentials, Phys. Rev. Lett. 98, 120403 (2007)
  • D. Witthaut, E. M. Graefe, S. Wimberger, and H. J. Korsch
    Bose-Einstein condensates in accelerated double-periodic optical lattices: Coupling and Crossing of resonances, Phys. Rev. A 75, 013617 (2007)
  • P. Schlagheck and S. Wimberger
    Nonexponential decay of Bose-Einstein condensates: a numerical study based on the complex scaling method, Appl. Phys. B 86, 385-390 (2007)
  • A. Facchini, S. Wimberger, and A. Tomadin
    Multifractal fluctuations in the survival probability of an open quantum system, Physica A 376, 266-274 (2007)
  • E. Persson, S. Fuhrthauer, S. Wimberger, and J. Burgdörfer
    Transient localization in the kicked Rydberg atom , Phys. Rev. A 74, 053417 (2006)
  • G. Carlo, G. Benenti, G. Casati, S. Wimberger, O. Morsch, R. Mannella, and E. Arimondo
    Chaotic ratchet dynamics with cold atoms in a pair of pulsed optical lattices, Phys. Rev. A 74, 033617 (2006)
  • S. Wimberger, P. Schlagheck, Ch. Eltschka, and A. Buchleitner
    Resonance-Assisted Decay of Nondispersive Wave Packets, Phys. Rev. Lett. 97, 043001 (2006)
  • A. Tomadin, R. Mannella, and S. Wimberger
    Can quantum fractal fluctuations be observed in an atom-optics kicked rotor experiment?, J. Phys. A: Math. Gen. 39, 2477-2491 (2006)
  • S. Wimberger, P. Schlagheck, and R. Mannella
    Tunnelling rates for the nonlinear Wannier-Stark problem, J. Phys. B: At. Mol. Opt. Phys. 39, 729 (2006)
  • S. Wimberger, R. Mannella, O. Morsch, E. Arimondo, A.R. Kolovsky, and A. Buchleitner
    Nonlinearity induced destruction of resonant tunneling in the Wannier-Stark problem, Phys. Rev. A 72, 063610 (2005)
  • M.B. d'Arcy, R.M. Godun, G. S. Summy, I. Guarneri, S. Wimberger, S. Fishman, and A. Buchleitner
    Decoherence as a probe of coherent quantum dynamics, Phys. Rev. E 69, 027201 (2004)
  • S. Wimberger, I. Guarneri, and S. Fishman
    Quantum resonances and decoherence for delta-kicked atoms, Nonlinearity 16, 1381 (2003)

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