Observing phase jumps of solitons in Bose-Einstein condensates

TL;DR

This paper proposes an interference-based method to directly observe the phase difference of solitons in Bose-Einstein condensates, providing a new tool to study soliton dynamics and decay.

Contribution

It introduces a novel interference technique using Raman and rf pulses to measure the phase jump of solitons in BECs, validated through simulations.

Findings

The density ratio after pulses reproduces the phase jump factor.

The method offers an alternative to density profile measurements.

It enables studying soliton decay and phase breakdown.

Abstract

The phase difference of the macroscopic wave function is a unique structure of the soliton in an atomic Bose--Einstein condensate (BEC). However, experiments on ultracold atoms so far have observed the valley of the density profile to study the dynamics of solitons. We propose a method to observe the phase difference of a soliton in a BEC by using an interference technique with Raman and rf pulses. We introduce a phase jump factor, which is an indicator to measure the phase difference between two points. It is demonstrated by using the projected Gross--Pitaevskii equation that an interference density ratio, the density ratio of two-component BECs after the Raman and rf pulses, reproduces the phase jump factor well. This technique will become an alternative method to study the decay and breakdown of a phase imprinted soliton in atomic BECs.