Phase resolution limit in macroscopic interference between Bose-Einstein condensates

TL;DR

This paper investigates the fundamental limits of phase resolution in interference experiments with Bose-Einstein condensates, highlighting the balance between phase definition and quantum fluctuations, and its implications for experimental precision.

Contribution

It introduces a model describing the steady-state phase resolution in BEC interference, accounting for interactions and detection rates, which was not previously characterized.

Findings

Phase resolution saturates at a value depending on interaction strength and detection rate.

Quantum fluctuations cause classical fluctuations in phase and particle number.

The study applies to current and future BEC interference experiments.

Abstract

We study the competition between phase definition and quantum phase fluctuations in interference experiments between independently formed Bose condensates. While phase-sensitive detection of atoms makes the phase progressively better defined, interactions tend to randomize it faster as the uncertainty in the relative particle number grows. A steady state is reached when the two effects cancel each other. Then the phase resolution saturates to a value that grows with the ratio between the interaction strength and the atom detection rate, and the average phase and number begin to fluctuate classically. We discuss how our study applies to both recently performed and possible future experiments.