Interplay of density and phase fluctuations in ultracold one-dimensional Bose gases

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 regime of dominant density fluctuations is shown to be well within current experimental capabilities for both $^{23}\mathrm{Na}$ and $^{87}\mathrm{Rb}$, requiring relatively low temperatures, small atom numbers, and moderate aspect ratios.