Quantum Criticality from in-situ Density Imaging

TL;DR

This paper uses large-scale QMC simulations to study quantum criticality in 2D bosonic systems, demonstrating how in-situ density imaging reveals universal scaling near the superfluid-Mott insulator transition, with implications for experimental thermometry.

Contribution

The study provides a comprehensive phase diagram and validates the use of in-situ density profiles to observe quantum critical scaling in strongly interacting bosons.

Findings

Excellent agreement between QMC simulations and experimental density measurements

Identification of temperature scales for observing quantum criticality

Validation of local FDT as a thermometry tool in strongly interacting regimes

Abstract

We perform large-scale Quantum Monte Carlo (QMC) simulations for strongly interacting bosons in a 2D optical lattice trap, and confirm an excellent agreement with the benchmarking in-situ density measurements by the Chicago group [1]. We further present a general finite temperature phase diagram both for the uniform and the trapped systems, and demonstrate how the universal scaling properties near the superfluid(SF)-to-Mott insulator(MI) transition can be observed by analysing the in-situ density profile. The characteristic temperature to find such quantum criticality is estimated to be of the order of the single-particle bandwidth, which should be achievable in the present or near future experiments. Finally, we examine the validity regime of the local fluctuation-dissipation theorem (FDT), which can be a used as a thermometry in the strongly interacting regime.