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TT: Fachverband Tiefe Temperaturen
TT 69: Other Low Temperature Topics: Cold Atomic Gases
TT 69.4: Vortrag
Mittwoch, 18. März 2015, 15:45–16:00, A 053
Thermalization of a Quenched Bose-Josephson Junction. — •Anna Posazhennikova1, Mauricio Trujillo-Martinez2, and Johann Kroha2 — 1Royal Holloway University of London, UK — 2Universitaet Bonn, Germany
The experimental realization and control of quantum systems isolated from the environment, in ultracold atomic gases relaunched the interest in the fundamental non-equilibrium problem of how a finite system approaches thermal equilibrium. Despite intensive research there is still no conclusive answer to this question. We investigate theoretically how a quenched Bose-Josephson junction, where the Josephson coupling is switched on instantaneously, approaches its stationary state. We use the field theoretical approach for bosons out of equilibrium in a trap with discrete levels, developed by us previously [1,2]. In this approach the operators for Bose-Einstein condensate (BEC) particles are treated on mean-field level, while excitations of the Bose gas in higher trap levels are treated fully quantum-mechanically. This leads to coupled equations of motion for the BEC amplitudes (Gross-Pitaevskii equation) and the quasiparticle propagators. The inelastic quasiparticle collisions responsible for the system relaxation during the time-dependent evolution are described within self-consistent second-order approximation.
[1] M. Trujillo-Martinez, A. Posazhennikova, J. Kroha,
Phys. Rev. Lett. 103, 105302 (2009).
[2] M. Trujillo-Martinez, A. Posazhennikova, J. Kroha,
New J. Phys. in press; arXiv:1406.5536v2.