Excitation spectrum of a supersolid

TL;DR

This paper uses first-principles simulations to analyze the excitation spectrum of a predicted supersolid phase in ultracold bosonic systems, revealing two distinct collective modes associated with broken symmetries.

Contribution

It provides the first detailed computational study of the elementary excitation spectrum of a supersolid, identifying two key modes linked to broken translation and gauge symmetries.

Findings

Identification of a solid-like phonon mode

Discovery of a softer collective excitation

Evidence of broken symmetries in the excitation spectrum

Abstract

Conclusive experimental evidence of a supersolid phase in any known condensed matter system is presently lacking. On the other hand, a supersolid phase has been recently predicted for a system of spinless bosons in continuous space, interacting via a broad class of soft-core, repulsive potentials. Such an interaction can be engineered in assemblies of ultracold atoms, providing a well-defined pathway to the unambiguous observation of this fascinating phase of matter. In this article, we study by first principle computer simulations the elementary excitation spectrum of the supersolid, and show that it features two distinct modes, namely a solid-like phonon and a softer collective excitation, related to broken translation and gauge symmetry respectively.