Probing correlated phases of bosons in optical lattices via trap squeezing

TL;DR

This paper proposes a method to probe the phases of ultracold bosons in optical lattices by measuring density responses to trap squeezing, enabling identification of superfluid, Mott insulator, band insulator, and Bose glass phases.

Contribution

It introduces a theoretical approach linking trap squeezing-induced density variations to bulk properties, facilitating phase detection in optical lattice experiments.

Findings

Density variations reflect bulk compressibility.

Method can distinguish different bosonic phases.

Potential for unambiguous phase identification.

Abstract

We theoretically analyze the response properties of ultracold bosons in optical lattices to the static variation of the trapping potential. We show that, upon an increase of such potential (trap squeezing), the density variations in a central region, with linear size of >~ 10 wavelengths, reflect that of the bulk system upon changing the chemical potential: hence measuring the density variations gives direct access to the bulk compressibility. When combined with standard time-of-flight measurements, this approach has the potential of unambiguously detecting the appearence of the most fundamental phases realized by bosons in optical lattices, with or without further external potentials: superfluid, Mott insulator, band insulator and Bose glass.