Chaotic dynamics of a Bose-Einstein condensate coupled to a qubit

TL;DR

This paper investigates how a qubit can control the chaotic dynamics of a Bose-Einstein condensate in an optical lattice, demonstrating potential for sensitive quantum control and decoherence effects.

Contribution

It introduces a numerical study of a coupled qubit-BEC system showing control of chaos and coherence preservation in nonlinear regimes.

Findings

Qubit state effectively controls BEC chaos.

Strong nonlinearity preserves qubit coherence.

Weak nonlinearity causes rapid qubit decoherence.

Abstract

We study numerically the coupling between a qubit and a Bose-Einstein condensate (BEC) moving in a kicked optical lattice, using Gross-Pitaevskii equation. In the regime where the BEC size is smaller than the lattice period, the chaotic dynamics of the BEC is effectively controlled by the qubit state. The feedback effects of the nonlinear chaotic BEC dynamics preserve the coherence and purity of the qubit in the regime of strong BEC nonlinearity. This gives an example of an exponentially sensitive control over a macroscopic state by internal qubit states. At weak nonlinearity quantum chaos leads to rapid dynamical decoherence of the qubit. The realization of such coupled systems is within reach of current experimental techniques.