Creating and melting a supersolid by heating a quantum dipolar system

Abstract

Recent experiments have shown that rising the temperature of a dipolar gas under certain conditions leads to a transition to a supersolid state. Here, we employ the path integral Monte Carlo method, which exactly accounts for both thermal and correlation effects, to study that phenomenology in a system of $^{162}$Dy atoms in the canonical ensemble. Our microscopic description allows to quantitatively characterize the emergence of spatial order and superfluidity, the two ingredients that define a supersolid state. Our calculations prove that temperature on its own can promote the formation of a supersolid in a dipolar system. Furthermore, we bridge this exotic phenomenology with the more usual melting of the supersolid at a higher temperature. Our results offer insight into the interplay between thermal excitations, the dipole-dipole interaction, quantum statistics and supersolidity.

Figures (4)

• Figure 1: Snapshots corresponding to the formation and melting of supersolid states with increasing temperature, obtained from the PIMC simulations. The plot in the bottom right displays the corresponding symmetrized column densities along the $x$-axis, which have been computed by averaging several realizations at fixed temperature for a scattering length value $a_s = 70 a_0$.
• Figure 2: Superfluid fraction along the $x$-$y$ plane as a function of the temperature for three different values of the scattering length. The blue and red regions correspond to unmodulated and modulated equilibrium configurations, respectively.
• Figure 3: Emergence of the modulations (top) and melting (bottom) for two values of the scattering length: $a_s = 61 a_0$ (left) and $a_s = 70 a_0$ (right). The column densities are symmetrized around the origin. The plots show the result of averaging several realizations yielding two-droplets.
• Figure 4: Symmetrized column densities at different temperatures for the system assuming bosonic (left) and Maxwell-Boltzmann (right) statistics, for a scattering length $a_s = 70 a_0$. The distributions are obtained from averages of several PIMC simulations producing two droplets as the lowest free-energy state.