Non-equilibrium and local detection of the normal fraction of a trapped two-dimensional Bose gas

TL;DR

This paper introduces a novel method to locally measure the normal fraction of a 2D Bose gas using artificial gauge fields, enabling spatial profiling without requiring thermal equilibrium.

Contribution

It presents a new non-equilibrium, local measurement technique for the normal fraction in 2D Bose gases using artificial gauge fields and classical field simulations.

Findings

The method can reconstruct the spatial profile of the superfluid component.

It does not require the gas to be in thermal equilibrium with the gauge field.

Classical simulations demonstrate the effectiveness of the measurement scheme.

Abstract

We propose a method to measure the normal fraction of a two-dimensional Bose gas, a quantity that generally differs from the non-condensed fraction. The idea is based on applying a spatially oscillating artificial gauge field to the atoms. The response of the atoms to the gauge field can be read out either mechanically from the deposited energy into the cloud, or optically from the macroscopic optical properties of the atomic gas. The local nature of the proposed scheme allows one to reconstruct the spatial profile of the superfluid component; furthermore, the proposed method does not require having established thermal equilibrium in the gas in the presence of the gauge field. The theoretical description of the system is based on a generalization of the Dum-Olshanii theory of artificial gauge fields to the interacting many-body context. The efficiency of the proposed measurement scheme is assessed by means of classical field numerical simulations. An explicit atomic level scheme minimizing disturbing effects such as spontaneous emission and light-shifts is proposed for Rb 87 atoms.