Superglass phase of interaction-blockaded gases on a triangular lattice

TL;DR

This paper explores the quantum phases of bosonic gases on a triangular lattice with soft-shoulder interactions, revealing a superglass phase where glassy behavior coexists with superfluidity, driven by quantum fluctuations and cluster formation.

Contribution

It demonstrates the existence of a superglass phase in a simple model without frustration or disorder, highlighting the role of quantum fluctuations and cluster formation.

Findings

Homogeneous superfluid at weak interactions

Glass phase at strong interactions

Superglass phase at intermediate interactions

Abstract

We investigate the quantum phases of monodispersed bosonic gases confined to a triangular lattice and interacting via a class of soft-shoulder potentials. The latter correspond to soft-core potentials with an additional hard-core onsite interaction. Using exact quantum Monte Carlo simulations, we show that the low temperature phases for weak and strong interactions following a temperature quench are a homogeneous superfluid and a glass, respectively. The latter is an insulating phase characterized by inhomogeneity in the density distribution and structural disorder. Remarkably, we find that for intermediate interaction strengths a {\it superglass} occurs in an extended region of the phase diagram, where glassy behavior coexists with a sizable finite superfluid fraction. This glass phase is obtained in the absence of geometrical frustration or external disorder and is a result of the competition of quantum fluctuations and cluster formation in the corresponding classical ground state. For high enough temperature, the glass and superglass turn into a floating stripe solid and a supersolid, respectively. Given the simplicity and generality of the model, these phases should be directly relevant for state-of-the-art experiments with Rydberg-dressed atoms in optical lattices.