Two atomic quantum dots interacting via coupling to BECs

TL;DR

This paper studies how two atomic quantum dots interact indirectly through their coupling to three weakly linked Bose-Einstein condensates, revealing complex magnetic behaviors depending on coupling strengths.

Contribution

It introduces a model of two quantum dots coupled via BECs, analyzing the induced pseudospin interactions and their dependence on system parameters.

Findings

Ferromagnetic pseudospin arrangement remains stable at large T/J.

Antiferromagnetic spins exhibit 'breathing' modes at weak coupling.

Spin behavior becomes uncorrelated at strong coupling.

Abstract

We consider a system of three weakly coupled Bose-Einstein condensates and two atomic quantum dots embedded in the barriers between the condensates. Each dot is coupled to two neighboring condensates by optical transitions and can be described as a two-state system, or a pseudospin 1/2. Although there is no direct coupling between the dots, an effective interaction between the pseudospins is induced due to their coupling to the condensate reservoirs. We investigate this effective interaction, depending on the strengths of the dot-condensate coupling T and the direct coupling J between the condensates. In particular, we show that an initially ferromagnetic arrangement of the two pseudospins stays intact even for large T/J. However, antiferromagnetically aligned spins undergo peculiar "breathing" modes for weak coupling T/J<1, while for strong coupling the behaviour of the spins becomes uncorrelated.