Asymmetric Landau-Zener tunneling in a periodic potential

TL;DR

This paper investigates asymmetric nonlinear Landau-Zener tunneling in a Bose-Einstein condensate within a periodic potential, revealing direction-dependent tunneling rates enhanced or suppressed by nonlinearity, supported by simulations and experimental evidence.

Contribution

It introduces a simple model demonstrating asymmetric tunneling rates in nonlinear Landau-Zener processes, confirmed through numerical simulations and experimental measurements.

Findings

Tunneling from ground to excited state is enhanced by nonlinearity.

Tunneling in the opposite direction is suppressed.

Experimental evidence supports the asymmetry in tunneling rates.

Abstract

Using a simple model for nonlinear Landau-Zener tunneling between two energy bands of a Bose-Einstein condensate in a periodic potential, we find that the tunneling rates for the two directions of tunneling are not the same. Tunneling from the ground state to the excited state is enhanced by the nonlinearity, whereas in the opposite direction it is suppressed. These findings are confirmed by numerical simulations of the condensate dynamics. Measuring the tunneling rates for a condensate of rubidium atoms in an optical lattice, we have found experimental evidence for this asymmetry.