Spatially inhomogeneous phase evolution of a two-component Bose-Einstein condensate

TL;DR

This study explores how the relative phase of a two-component Bose-Einstein condensate varies spatially, revealing inhomogeneity as the main cause of interferometric contrast loss and proposing methods for detailed phase imaging.

Contribution

It introduces a detailed analysis of spatial phase evolution in a two-component BEC and presents a novel imaging technique for the relative phase distribution.

Findings

Inhomogeneity causes dominant phase contrast decay.

A method for simultaneous state imaging with minimal variation.

Proposal of a spatially sensitive phase imaging technique.

Abstract

We investigate the spatially dependent relative phase evolution of an elongated two-component Bose-Einstein condensate. The pseudospin-1/2 system is comprised of the |F=1,m_F=-1> and |F=2,m_F=+1> hyperfine ground states of 87Rb, which we magnetically trap and interrogate with radio-frequency and microwave fields. We probe the relative phase evolution with Ramsey interferometry and observe a temporal decay of the interferometric contrast well described by a mean-field formalism. Inhomogeneity of the collective relative phase dominates the loss of interferometric contrast, rather than decoherence or phase diffusion. We demonstrate a technique to simultaneously image each state, yielding subpercent variations in the measured relative number while preserving the spatial mode of each component. In addition, we propose a spatially sensitive interferometric technique to image the relative phase.