Rotational superradiance with Bogoliubov dispersion

TL;DR

This paper investigates how dispersion in Bose-Einstein condensates modifies rotational superradiance, showing that dispersion suppresses energy and angular momentum extraction by narrowing the superradiant bandwidth and blocking high-angular momentum modes.

Contribution

It provides the first analysis of superradiance with Bogoliubov dispersion in a Bose-Einstein condensate, revealing how dispersion alters superradiant behavior.

Findings

Dispersion reduces the superradiant bandwidth.

High-angular momentum modes are prevented from superradiating.

Dispersion suppresses energy and angular momentum extraction.

Abstract

Rotational superradiance affects the dynamics of many rotating systems in nature, through either stimulated or spontaneous extraction of energy and angular momentum. By now, this process is well-studied in the relativistic setting, where systems are intrinsically dispersion-free. In many condensed matter systems, however, dispersion is an unavoidable aspect of the description for the short wavelength modes. For these systems, how might one expect superradiance to be modified? In this work, an answer to this question is provided using an illustrative example. The scattering of linear excitations of a Bose-Einstein condensate are studied in the presence of a rotating, draining vortex flow using the full Bogoliubov dispersion relation. It is shown that dispersion suppresses the extraction of energy and angular momentum, firstly, by decreasing the superradiant bandwidth, and secondly, by preventing high-angular momentum modes from superradiating.