Single-atom-resolved probing of lattice gases in momentum space

TL;DR

This paper presents a method to reconstruct the momentum-space distribution of 3D interacting lattice gases at the single-atom level, enabling detailed analysis of quantum phases and transitions.

Contribution

It introduces a novel technique for atom-by-atom detection of momentum distributions in lattice gases, validated against Quantum Monte-Carlo simulations.

Findings

Resolved momentum distributions of superfluids over 10^5 lattice sites.

Able to measure the condensed fraction across phase transitions.

Demonstrated detection of momentum correlations in interacting gases.

Abstract

Measuring the full distribution of individual particles is of fundamental importance to characterize many-body quantum systems through correlation functions at any order. Here we demonstrate the possibility to reconstruct the momentum-space distribution of three-dimensional interacting lattice gases atom-by-atom. This is achieved by detecting individual metastable Helium atoms in the far-field regime of expansion, when released from an optical lattice. We benchmark our technique with Quantum Monte-Carlo calculations, demonstrating the ability to resolve momentum distributions of superfluids occupying $10^5$ lattice sites. It permits a direct measure of the condensed fraction across phase transitions, as we illustrate on the superfluid-to-normal transition. Our single-atom-resolved approach opens a new route to investigate interacting lattice gases through momentum correlations.