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Q: Quantenoptik

Q 311: Bose-Einstein Kondensation I

Q 311.7: Vortrag

Mittwoch, 6. März 2002, 15:30–15:45, HS 22/B01

Numerical simulations of degenerate interacting Bose and Fermi systems: quantum stochastics in imaginary time — •Lev I. Plimak¹, Murray K. Olsen², and Michael Fleischhauer¹ — ¹FB Physik, Univ. Kaiserslautern — ²Instituto de Fisica, Niteroi, Brazil

Methods of quantum stochastics (QS) in real time have been widely used in quantum optics. We proposed [1] an extension of QS to an equilibrium grand-canonical ensemble of interacting bosons, based on Matsubara’s approach and a stochastic differential equation (SDE) in imaginary time. In [2], QS in imaginary time was extended to interacting fermions and applied to the onset of Cooper-pairing in trapped 1D fermions. However closer analyses reveal that the “raw” stochastic representations either diverge (for bosons) or yield huge sampling noise (for fermions). For both systems the imaginary-time SDEs are linear allowing for a deeper analytical insight. In particular, explicit averaging over certain stochastic degrees of freedom turn out to be possible. Noise suppression techniques are demonstrated and applied to the Bose-Hubbard model and cold trapped gases of fermions and bosons. [1] LI Plimak, M Fleischhauer, and DF Walls, Europhys. Lett. 43, 641 (1998) [2] LI Plimak, MJ Collett and MK Olsen, Phys. Rev. A 64, 063409 (2001).