Thermal effects on density-modulated phases in a dipolar Bose--Einstein condensate

Abstract

Density-modulated phases in dipolar Bose--Einstein condensates arise from the competition between contact repulsion, long-range dipole--dipole interactions, and beyond-mean-field fluctuations. We examine finite-temperature stationary states of a harmonically trapped dipolar Bose gas using a temperature-dependent extended Gross--Pitaevskii equation within the local-density approximation. In this framework, the thermal correction shifts some structural boundaries toward larger scattering lengths and changes the parameter region in which connected density-modulated states are obtained. The density contrast changes sharply at $T=0$, whereas at finite temperature it varies more gradually, consistent with a smooth crossover-like evolution in the finite trapped system. We also use Leggett's bound to estimate a geometric upper limit on the possible superfluid response for representative density profiles. These results suggest that finite-temperature corrections can reshape pattern formation in dipolar quantum gases.

9 pages, 4 figures