Boson Core Compressibility

TL;DR

This paper introduces boson core compressibility and core superfluid stiffness as new measures derived from double occupancy to effectively probe phase transitions in trapped atomic systems, overcoming edge effects.

Contribution

It proposes novel observables based on double occupancy that eliminate trapping inhomogeneity effects, enabling clearer detection of phase transitions in Hubbard models.

Findings

Quantum Monte Carlo simulations confirm these measures remove edge effects.

These measures can be used to experimentally map phase transitions.

They provide a new tool for studying strongly correlated bosonic systems.

Abstract

Strongly interacting atoms trapped in optical lattices can be used to explore phase diagrams of Hubbard models. Spatial inhomogeneity due to trapping typically obscures distinguishing observables. We propose that measures using boson double occupancy avoid trapping effects to reveal key correlation functions. We define a boson core compressibility and core superfluid stiffness in terms of double occupancy. We use quantum Monte Carlo on the Bose-Hubbard model to empirically show that these quantities intrinsically eliminate edge effects to reveal correlations near the trap center. The boson core compressibility offers a generally applicable tool that can be used to experimentally map out phase transitions between compressible and incompressible states.