From a two-level model for nonlinear Landau-Zener tunnelling between two energy bands of a Bose-Einstein condensate in a periodic potential we obtain unequal tunnelling rates for the two directions of tunnelling. With increasing nonlinearity, tunnelling from the ground state to the excited state is enhanced, whereas in the opposite direction it is suppressed. These findings are confirmed by numerical simulations of the condensate dynamics. Measuring the tunnelling rates for a condensate of rubidium atoms in an optical lattice, we have found experimental evidence for this asymmetry. We discuss the limitations of our approach and possible future experiments.

Nonlinear effects in periodic potentials: asymmetric Landau-Zener tunnelling of a Bose-Einstein condensate

MALOSSI, Nicola;
2004

Abstract

From a two-level model for nonlinear Landau-Zener tunnelling between two energy bands of a Bose-Einstein condensate in a periodic potential we obtain unequal tunnelling rates for the two directions of tunnelling. With increasing nonlinearity, tunnelling from the ground state to the excited state is enhanced, whereas in the opposite direction it is suppressed. These findings are confirmed by numerical simulations of the condensate dynamics. Measuring the tunnelling rates for a condensate of rubidium atoms in an optical lattice, we have found experimental evidence for this asymmetry. We discuss the limitations of our approach and possible future experiments.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11581/287023
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