Spatial coherence of spin-orbit-coupled Bose gases

TL;DR

This paper investigates the spatial coherence and density modulations in spin-orbit-coupled Bose-Einstein condensates, revealing long-range coherence in both stripe and phase-separated phases through optical Bragg scattering and Talbot effect analogues.

Contribution

It demonstrates the existence of long-range coherence in both stripe and phase-separated phases of SOBECs using optical Bragg scattering and Talbot effect analogues.

Findings

Density modulations are observed in overlapping regions.

Long-range coherence exists in both stripe and phase-separated phases.

Bragg scattering drops as the overlapping region shrinks.

Abstract

Spin-orbit-coupled Bose-Einstein condensates (SOBECs) exhibit two new phases of matter, now known as the stripe and plane-wave phases. When two interacting spin components of a SOBEC spatially overlap, density modulations with periodicity given by the spin-orbit coupling strength appear. In equilibrium, these components fully overlap in the miscible stripe phase, and overlap only in a domain wall in the immiscible plane-wave phase. Here we probe the density modulation present in any overlapping region with optical Bragg scattering, and observe the sudden drop of Bragg scattering as the overlapping region shrinks. Using an atomic analogue of the Talbot effect, we demonstrate the existence of long-range coherence between the different spin components in the stripe phase and surprisingly even in the phase-separated plane-wave phase.