Controlled quantum stirring of Bose-Einstein condensates

TL;DR

This paper explores how cyclic adiabatic changes in an optical trap can induce controlled circulating currents in Bose-Einstein condensates, revealing interaction-dependent behaviors and employing the Kubo approach for analysis.

Contribution

It introduces a method to control and analyze quantum stirring in BECs using adiabatic cycles and the Kubo approach, highlighting interaction effects.

Findings

Current depends on cycle radius and interaction strength.

Strong interactions lead to Landau-Zener crossing behavior.

Attractive interactions cause particles to behave like a classical ball.

Abstract

By cyclic adiabatic change of two control parameters of an optical trap one can induce a circulating current of condensed bosons. The amount of particles that are transported per period depends on the "radius" of the cycle, and this dependence can be utilized in order to probe the interatomic interactions. For strong repulsive interaction the current can be regarded as arising from a sequence of Landau-Zener crossings. For weaker interaction one observes either gradual or coherent mega crossings, while for attractive interaction the particles are glued together and behave like a classical ball. For the analysis we use the Kubo approach to quantum pumping with the associated Dirac monopoles picture of parameter space.