Black-hole radiation in Bose-Einstein condensates

TL;DR

This paper investigates phonon emissions in Bose-Einstein condensates mimicking black hole horizons, analyzing spectral properties and correlations to identify signatures of Hawking radiation under realistic conditions.

Contribution

It provides a detailed theoretical and numerical analysis of Hawking-like phonon fluxes and correlations in BECs, including effects of temperature and flow configurations.

Findings

Condensate temperature dominates phonon fluxes, masking spontaneous Hawking emission.

Long-distance correlations are amplified by temperature, serving as a signature of Hawking radiation.

Optimal conditions for observing Hawking-like correlations are identified.

Abstract

We study the phonon fluxes emitted when the condensate velocity crosses the speed of sound, i.e., in backgrounds which are analogous to that of a black hole. We focus on elongated one dimensional condensates and on stationary flows. Our theoretical analysis and numerical results are based on the Bogoliubov-de Gennes equation without further approximation. The spectral properties of the fluxes and of the long distance density-density correlations are obtained, both with and without an initial temperature. In realistic conditions, we show that the condensate temperature dominates the fluxes and thus hides the presence of the spontaneous emission (the Hawking effect). We also explain why the temperature amplifies the long distance correlations which are intrinsic to this effect. This confirms that the correlation pattern offers a neat signature of the Hawking effect. Optimal conditions for observing the pattern are discussed, as well as correlation patterns associated with scattering of classical waves. Flows associated with white holes are also considered.