Light-induced quantum droplet phases of lattice bosons in multimode cavities

TL;DR

This paper explores how light-induced, finite-range interactions in multimode cavities lead to the emergence of quantum droplet phases in lattice bosons, revealing a complex phase diagram with various self-bound states.

Contribution

It demonstrates that finite-range cavity-mediated interactions induce quantum droplet phases in lattice bosons, expanding the understanding of phase behavior beyond infinite-range models.

Findings

Quantum droplets dominate the ground state for finite-range interactions.

Droplet size and density emerge from local interactions, not fixed externally.

Rich phase diagram includes superfluid, supersolid, Mott insulator, and various droplet phases.

Abstract

Multimode optical cavities can be used to implement interatomic interactions which are highly tunable in strength and range. For bosonic atoms trapped in an optical lattice, cavity-mediated interactions compete with the short-range interatomic repulsion, which we study using an extended Bose-Hubbard model. Already in a single-mode cavity, where the corresponding interaction has an infinite range, a rich phase diagram has been experimentally observed, featuring density-wave and supersolid self-organized phases in addition to the usual superfluid and Mott insulator. Here we show that, for any finite range of the cavity-mediated interaction, quantum self-bound droplets dominate the ground state phase diagram. Their size and in turn density is not externally fixed but rather emerges from the competition between local repulsion and finite-range attraction. Therefore, the phase diagram becomes very rich, featuring both compressible superfluid/supersolid as well as incompressible Mott and density-wave droplets. Additionally, we observe droplets with a compressible core and incompressible outer shells.