Probing strongly interacting atomic gases with energetic atoms

TL;DR

This paper uses operator product expansion to analyze energetic atoms in strongly interacting gases, providing a new method to measure contact density and understand quasiparticle properties in atomic gases.

Contribution

It introduces a systematic large-momentum expansion approach to compute quasiparticle energy and scattering rates, and proposes a novel experimental probe for contact density in atomic gases.

Findings

Agreement with quantum Monte Carlo simulations at high momentum

Identification of contact density as key to backward scattering

Proposal of a new local measurement technique for atomic gases

Abstract

We investigate properties of an energetic atom propagating through strongly interacting atomic gases. The operator product expansion is used to systematically compute a quasiparticle energy and its scattering rate both in a spin-1/2 Fermi gas and in a spinless Bose gas. Reasonable agreement with recent quantum Monte Carlo simulations even at a relatively small momentum k/kF>1.5 indicates that our large-momentum expansions are valid in a wide range of momentum. We also study a differential scattering rate when a probe atom is shot into atomic gases. Because the number density and current density of the target atomic gas contribute to the forward scattering only, its contact density (measure of short-range pair correlation) gives the leading contribution to the backward scattering. Therefore, such an experiment can be used to measure the contact density and thus provides a new local probe of strongly interacting atomic gases.