Coherence of One-Dimensional Spin-Orbit-Coupled Bose Gases at Finite Temperature

Coherence property is a useful tool to characterize the low-dimensional quantum many-body system. One-dimensional Bose gases represent a quasi-long-range order in the one-body correlation function, revealing the existence of the superfluid. Unlike in two-dimensional space, where Bose gases undergo a well-known Berezinskii–Kosterlitz–Thouless transition from superfluid to thermal gas by increasing the temperature, the Bose gases in one-dimensional potential would only smoothly change the superfluid fraction. We experimentally investigate how the thermal fluctuations affect the coherence in one-dimensional spin-orbit coupled Bose gases from low to high temperatures. By tuning the strength of the spin-orbit coupling towards a critical value, we also demonstrate the suppression of the coherence property of superfluid. The comparison between these two results indicates a similar physical mechanism.