Two-point phase correlations of a one-dimensional bosonic Josephson junction

TL;DR

This paper investigates the phase correlations in a one-dimensional bosonic Josephson junction, revealing how thermal fluctuations and tunneling influence the phase coherence, using matter wave interferometry and statistical analysis.

Contribution

It introduces a method to directly measure the full statistical distribution of phase correlations in a 1D bosonic Josephson junction, enabling full characterization of coupling and temperature.

Findings

Measured phase correlation distributions match stochastic model predictions.

Quantified the interplay between thermal fluctuations and tunneling.

Provided a new approach for characterizing quantum gases in double well potentials.

Abstract

We realize a one-dimensional Josephson junction using quantum degenerate Bose gases in a tunable double well potential on an atom chip. Matter wave interferometry gives direct access to the relative phase field, which reflects the interplay of thermally driven fluctuations and phase locking due to tunneling. The thermal equilibrium state is characterized by probing the full statistical distribution function of the two-point phase correlation. Comparison to a stochastic model allows to measure the coupling strength and temperature and hence a full characterization of the system.