Supersolid crystals of dipolar excitons in a lattice

TL;DR

This paper proposes a new way to create supersolid crystals using dipolar excitons in a lattice, demonstrating both crystalline order and superfluidity through numerical simulations.

Contribution

It introduces a novel framework for realizing supersolid phases in strongly interacting dipolar bosons confined in a lattice with long-range hopping.

Findings

Observation of mesoscopic quantum solids at fractional lattice fillings.

Demonstration of coexistence of crystalline order and superfluidity in exciton systems.

Numerical confirmation of supersolidity in the ground state of the lattice Hamiltonian.

Abstract

In condensed-matter physics, long-range correlations introduce quantum states of matter that challenge intuition. For instance, supersolids combine symmetry-breaking crystalline structure, i.e. density order, and frictionless superfluid flow. Envisioned over fifty years ago, supersolids have proven to only exist under very stringent conditions, with experimental evidence limited to few observations. Many-body phases with supersolid properties in fact reduce to a few recent observations for weakly interacting Bose gases. Here, we demonstrate a new framework to realize supersolid crystals in the strong interaction regime, by confining dipolar bosons in a lattice with long-range hopping. We study dipolar excitons that genuinely realize this lattice model. At fractional lattice fillings - 1/4, 1/3 and 1/2 - we report mesoscopic quantum solids, across over 100 sites, spontaneously breaking translational symmetry. At the same time, we show that off-diagonal long-range order is induced by long-range hopping, such that exciton solids are superfluids. State-of-the-art numerical methods quantitatively confirm that supersolidity builds up in the ground-state of the lattice Hamiltonian. Our studies of strongly-correlated supersolid crystals open new frontiers for exploration in condensed matter physics.