Ground-state properties of unitary bosons: from clusters to matter

TL;DR

This paper investigates the universal properties of unitary Bose gases, demonstrating energy saturation in clusters and bulk matter, and providing detailed measurements of their physical characteristics.

Contribution

It introduces a comprehensive analysis of finite Bose clusters up to 60 particles and compares their properties with bulk matter at unitarity, highlighting saturation effects.

Findings

Energy and density saturate with particle number in clusters and bulk

Bulk matter is significantly more bound than clusters

Condensate fraction exceeds 90% in saturated systems

Abstract

The properties of cold Bose gases at unitarity have been extensively investigated in the last few years both theoretically and experimentally. In this paper we use a family of interactions tuned to two-body unitarity and very weak three-body binding to demonstrate the universal properties of both clusters and matter. We determine the universal properties of finite clusters up to 60 particles and, for the first time, explicitly demonstrate the saturation of energy and density with particle number and compare with bulk properties. At saturation in the bulk we determine the energy, density, two- and three-body contacts and the condensate fraction. We find that uniform matter is more bound than three-body clusters by nearly two orders of magnitude, the two-body contact is very large in absolute terms, and yet the condensate fraction is also very large, greater than 90%. Equilibrium properties of these systems may be experimentally accessible through rapid quenching of weakly-interacting boson superfluids.