Finite-temperature phase diagram of dipolar bosons in a cylindrical setup

Abstract

Temperature plays a non-trivial role in dipolar systems, being able to either induce or destroy spatial density modulations. In order to shed light into the interplay between thermal effects and quantum correlations, we employ the path integral Monte Carlo method (PIMC) to obtain the phase diagram of a system of dipolar bosons in an infinite cylindrical geometry and at finite temperatures. For a fixed total density, we vary the scattering length of the interaction and the temperature, and characterize the structure and superfluidity of the emerging phases. The PIMC method accounts for thermal effects and quantum correlations at all orders, and can be used to quantitatively estimate the superfluid fraction of the system. Remarkably, we find a regime of parameters where, starting from a supersolid, the spatial order vanishes with temperature before the superfluidity does. We also find a region of the phase diagram where the superfluid fraction displays a non-monotonous dependence with temperature. Our results extend previous descriptions, relying on Bogoliubov theory, to larger temperatures in the thermodynamic limit and illustrate how spatial modulations and superfluidity are lost as temperature is increased.