Frankfurt 2006 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 2: Quantengase I

Q 2.2: Vortrag

Montag, 13. März 2006, 11:25–11:40, HVI

Exact tunnelling rates for the nonlinear Wannier-Stark problem — •Sandro Wimberger — CNR-INFM and Dipartimento di Fisica E. Fermi, Universita degli Studi di Pisa, Largo Pontecorvo 3, I-56127 Pisa

We present a method to numerically compute exact tunnelling rates for a Bose-Einstein condensate which is described by the nonlinear Gross-Pitaevskii equation. Our method is based on a sophisticated real-time integration of the complex-scaled Gross-Pitaevskii equation, and it is capable of finding the stationary eigenvalues for the Wannier-Stark problem. We show that even weak nonlinearities have significant effects in the vicinity of very sensitive resonant tunnelling peaks, which occur in the rates as a function of the Stark field amplitude. The mean-field interaction induces a broadening and a shift of the peaks, and the latter is explained by analytic perturbation theory. Our results are confronted with a recent experimental proposal to measure the quantum transport processes around the resonant tunnelling peaks, see S. Wimberger et al., preprint cond-mat/0506357.