Macroscopic Quantum Coherence in a repulsive Bose-Einstein condensate

TL;DR

This paper investigates macroscopic quantum coherence in a Bose-Einstein condensate of rubidium-87 with two internal states, demonstrating symmetry breaking, bistability, and tunneling phenomena influenced by losses.

Contribution

It introduces a novel setup for observing macroscopic quantum coherence in a bicondensate with symmetry breaking and analyzes tunneling dynamics and coherence effects.

Findings

Evidence of symmetry breaking in momentum space

Observation of bistability in the condensate states

Quantitative analysis of tunneling rates and loss effects

Abstract

We consider a Bose-Einstein bicondensate (BEC) of $^{87}Rb$, trapped in two different internal levels, in a situation where the density undergoes a symmetry breaking in momentum space. This occurs for a suitable number of condensed atoms within a double well dispersion curve, obtained by Raman coupling two internal states with two tilted and detuned light fields. Evidence of bistability results from the Gross-Pitaevskii equation. By second quantization, we evaluate the tunneling rate between the two asymmetric states; the effects of losses on coherence are also considered.