Interplay of Density and Phase Fluctuations in Ultracold One-dimensional Bose Gases

TL;DR

This paper investigates the relative roles of density and phase fluctuations in ultracold one-dimensional Bose gases, revealing a new regime where density fluctuations dominate at lower temperatures, which is accessible with current experimental setups.

Contribution

It introduces a new experimental regime where density fluctuations occur before phase fluctuations in 1D Bose gases, contrasting with previous regimes.

Findings

Density fluctuations set in at lower temperatures than phase fluctuations.

A broad experimental regime for observing dominant density fluctuations is identified.

Current experiments with Na and Rb can access this regime.

Abstract

The relative importance of density and phase fluctuations in ultracold one dimensional atomic Bose gases is investigated. By defining appropriate characteristic temperatures for their respective onset, a broad experimental regime is found, where density fluctuations set in at a lower temperature than phase fluctuations. This is in stark contrast to the usual experimental regime explored up to now, in which phase fluctuations are largely decoupled from density fluctuations, a regime also recovered in this work as a limiting case. Observation of the novel regime of dominant density fluctuations is shown to be well within current experimental capabilities for both $^{23}Na$ and $^{87}Rb$, requiring relatively low temperatures, small atom numbers and moderate aspect ratios.