Effects of gravity on supersolid order in bubble-trapped bosons

TL;DR

This study investigates how gravity influences supersolid order in strongly-interacting bubble-trapped bosons, revealing that supersolidity persists under weak gravity but diminishes with stronger gravitational effects, with implications for terrestrial experiments.

Contribution

The paper introduces a theoretical analysis of gravity's impact on supersolid phases in bubble-trapped bosons using path integral Monte Carlo simulations, highlighting conditions for observable supersolidity on Earth.

Findings

Supersolid order is maintained under weak gravity conditions.

Strong gravity causes particles to cluster at the trap's bottom.

Clues of supersolidity may be detectable in Earth-based experiments.

Abstract

Unveiling the principles behind self-organization in quantum systems is of paramount importance, both intrinsically and practically, in view of foreseeable technological applications. Recently, increasing attention is being paid to atomic systems in curved geometries, which are a promising platform for the discovery of new emergent phenomena. A notable example is that of a gas of ultracold atoms loaded into a thin spherical shell, according to a protocol introduced by Zobay and Garraway more than twenty years ago. However, gravity prevents a dilute assembly of atoms from uniformly spreading throughout the shell, which explains why experiments on the condensation and superfluidity of bubble-trapped gases are usually conducted in space under microgravity conditions. In this paper, we focus instead on strongly-interacting quantum particles in a bubble trap, choosing the cluster supersolid of soft-core bosons as testbed. To study the impact of gravity on supersolid order, we consider a gedanken experiment in which the strength of gravity relative to the core repulsion is gradually enhanced. Using path integral Monte Carlo simulations, we trace the parallel evolution of system structure and superfluidity at low temperature, finding that the latter is sizeable only when gravity is a small perturbation or, at the other extreme, so strong that particles are all gathered in one cluster at the bottom of the trap. Finally, we assess the relevance of gravity for the equilibrium behavior of ultracold Rydberg-dressed atoms in a bubble trap, concluding that in some cases clues of the supersolid phase in the absence of gravity could be found even in a laboratory on Earth.