Interference between independent fluctuating condensates

TL;DR

This paper investigates how interference patterns between independent, fluctuating condensates reveal internal correlation functions, providing insights into quantum many-body physics and phase transitions.

Contribution

It demonstrates that interference patterns encode correlation functions, analyzes universal scaling in 1D Bose liquids, and proposes using interference to probe the Kosterlitz-Thouless transition.

Findings

Universal scaling of fringe contrast with system size and temperature.

Full distribution of fringe contrast reveals interaction strength and high-order correlations.

Interference patterns can probe phase transitions like Kosterlitz-Thouless.

Abstract

We consider a problem of interference between two independent condensates, which lack true long range order. We show that their interference pattern contains information about correlation functions within each condensate. As an example we analyze the interference between a pair of one dimensional interacting Bose liquids. We find universal scaling of the average fringe contrast with system size and temperature that depends only on the Luttinger parameter. Moreover the full distribution of the fringe contrast, which is also equivalent to the full counting statistics of the interfering atoms, changes with interaction strength and lends information on high order correlation functions. We also demonstrate that the interference between two-dimensional condensates at finite temperature can be used as a direct probe of the Kosterlitz-Thouless transition. Finally, we discuss generalization of our results to describe the intereference of a periodic array of independent fluctuating condensates.