Excitation spectrum of dipolar Bose gases

We investigate the excitation spectrum of a dipolar Bose gas in the low temperature limit across the superfluid-supersolid-crystal transition. At sufficiently low temperatures, a system of aligned dipolar bosons will undergo a quantum phase transition by tuning the range of the repulsive two-body potential. In one limit, the phase of the system is that of a classical crystal of filaments. At the other limit, the system experiences quantum melting into a superfluid phase. In the intermediate regime, the system exists in a supersolid state. We use Quantum Monte Carlo techniques to compute imaginary time correlation functions at the different regions of the phase diagram, and we use the method of Maximum Entropy to extract the dynamical structure factor, which is then used to obtain the excitation spectrum and its evolution throughout the phase diagram.