Estimating strong correlations in optical lattices

TL;DR

This paper introduces a method to detect strong correlations in optical lattice quantum states using noise correlation measurements, aiding the understanding of complex many-body phenomena without full state tomography.

Contribution

It presents a novel technique to quantify deviations from Gaussian states in cold atom systems based on accessible noise correlation data.

Findings

Effective detection of non-Gaussian correlations in experimental data

Numerical simulations support the method's validity

Insights into localization and transport suppression in disordered systems

Abstract

Ultra-cold atoms in optical lattices provide one of the most promising platforms for analog quantum simulations of complex quantum many-body systems. Large-size systems can now routinely be reached and are already used to probe a large variety of different physical situations, ranging from quantum phase transitions to artificial gauge theories. At the same time, measurement techniques are still limited and full tomography for these systems seems out of reach. Motivated by this observation, we present a method to directly detect and quantify to what extent a quantum state deviates from a local Gaussian description, based on available noise correlation measurements from in-situ and time-of-flight measurements. This is an indicator of the significance of strong correlations in ground and thermal states, as Gaussian states are precisely the ground and thermal states of non-interacting models. We connect our findings, augmented by numerical tensor network simulations, to notions of equilibration, disordered systems and the suppression of transport in Anderson insulators.