Towards the observation of Hawking radiation in Bose--Einstein condensates

TL;DR

This paper explores the potential for observing Hawking radiation in Bose--Einstein condensates by proposing an experimental setup with a measurable Hawking temperature of about 70 nK, close to the condensate temperature.

Contribution

It identifies a feasible experimental configuration in a BEC that could magnify Hawking radiation effects for detection.

Findings

Hawking temperature estimated at 70 nK in proposed setup

Configuration feasible with current BEC technology

Hawking radiation signal close to condensate temperature

Abstract

Acoustic analogues of black holes (dumb holes) are generated when a supersonic fluid flow entrains sound waves and forms a trapped region from which sound cannot escape. The surface of no return, the acoustic horizon, is qualitatively very similar to the event horizon of a general relativity black hole. In particular Hawking radiation (a thermal bath of phonons with temperature proportional to the ``surface gravity'') is expected to occur. In this note we consider quasi-one-dimensional supersonic flow of a Bose--Einstein condensate (BEC) in a Laval nozzle (converging-diverging nozzle), with a view to finding which experimental settings could magnify this effect and provide an observable signal. We identify an experimentally plausible configuration with a Hawking temperature of order 70 n K; to be contrasted with a condensation temperature of the order of 90 n K.