Coherence of an Interacting Bose Gas: from a Single to a Double Well

TL;DR

This paper investigates the coherence properties of a trapped Bose gas across various barrier heights, deriving models that unify low and high barrier regimes and analyzing the effects of number squeezing and temperature.

Contribution

It introduces a self-consistent two-mode model that transitions from Bogoliubov to Josephson descriptions, explicitly calculating tunneling and interaction parameters.

Findings

The model accurately describes the low-energy properties across barrier heights.

Number squeezing and temperature significantly affect coherence.

Analytical results clarify the role of these factors in coherence loss.

Abstract

The low energy properties of a trapped bose gas split by a potential barrier are determined over the whole range of barrier heights. We derive a self-consistent two-mode model which reduces, for large $N$, to a Bogoliubov model for low barriers and to a Josephson model for any (asymmetric) double well potential, with explicitly calculated tunneling and pair interaction parameters. We compare the numerical results to analytical results that precisely specify the role of number squeezing and finite temperatures in the loss of coherence.