Coherent single atom shuttle between two Bose-Einstein condensates

TL;DR

This paper investigates how a single hyperfine atom can coherently shuttle particles between two Bose-Einstein condensates, inducing Josephson-like oscillations with a novel two-frequency behavior.

Contribution

It introduces a model of an atomic quantum dot strongly coupled to two condensates, revealing new two-frequency Josephson oscillations and providing analytical solutions for noninteracting cases.

Findings

Quantum dot induces large-amplitude Josephson oscillations.

Oscillations exhibit a two-frequency behavior.

Analytical solutions derived for noninteracting condensates.

Abstract

We study an atomic quantum dot representing a single hyperfine "impurity" atom which is coherently coupled to two well-separated Bose-Einstein condensates, in the limit when the coupling between the dot and the condensates dominates the inter-condensate tunneling coupling. It is demonstrated that the quantum dot by itself can induce large-amplitude Josephson-like oscillations of the particle imbalance between the condensates, which display a two-frequency behavior. For noninteracting condensates, we provide an approximate solution to the coupled nonlinear equations of motion which allows us to obtain these two frequencies analytically.