Discerning Incompressible and Compressible Phases of Cold Atoms in Optical Lattices

TL;DR

This paper introduces a method to measure the core compressibility of cold atoms in optical lattices, helping to identify different phases despite spatial inhomogeneity, by relating it to double occupancy measurements.

Contribution

It proposes a novel core compressibility measurement technique that isolates phase signatures in inhomogeneous cold atom systems using high temperature series expansion.

Findings

Core compressibility correlates with double occupancy changes.

Method filters out edge effects, providing clearer phase signatures.

Comparison with experiments validates the approach.

Abstract

Experiments with cold atoms trapped in optical lattices offer the potential to realize a variety of novel phases but suffer from severe spatial inhomogeneity that can obscure signatures of new phases of matter and phase boundaries. We use a high temperature series expansion to show that compressibility in the core of a trapped Fermi-Hubbard system is related to measurements of changes in double occupancy. This core compressibility filters out edge effects, offering a direct probe of compressibility independent of inhomogeneity. A comparison with experiments is made.