Quantum read-out for cold atomic quantum simulators

TL;DR

This paper introduces a novel quantum read-out method for cold atomic quantum simulators that uses coherent dynamics to indirectly measure elusive observables, enhancing the analysis of superfluid properties.

Contribution

It presents a new tomographic recovery technique leveraging non-interacting dynamics to measure second moments of density fluctuations in 1D superfluids, previously inaccessible.

Findings

Successfully reconstructs second moments of density fluctuations.

Analyzes equilibrium states and phonon dynamics.

Predicts quantum recurrences in superfluid systems.

Abstract

Quantum simulators allow to explore static and dynamical properties of otherwise intractable quantum many-body systems. In many instances, however, it is the read-out that limits such quantum simulations. In this work, we introduce a new paradigm of experimental read-out exploiting coherent non-interacting dynamics in order to extract otherwise inaccessible observables. Specifically, we present a novel tomographic recovery method allowing to indirectly measure second moments of relative density fluctuations in one-dimensional superfluids which until now eluded direct measurements. We achieve this by relating second moments of relative phase fluctuations which are measured at different evolution times through known dynamical equations arising from unitary non-interacting multi-mode dynamics. Applying methods from signal processing we reconstruct the full matrix of second moments, including the relative density fluctuations. We employ the method to investigate equilibrium states, the dynamics of phonon occupation numbers and even to predict recurrences. The method opens a new window for quantum simulations with one-dimensional superfluids, enabling a deeper analysis of their equilibration and thermalization dynamics.