Anomalous Doppler effect in two-component Bose-Einstein condensates
Abstract
We show that two-component Bose-Einstein condensed mixtures, in presence of a persistent current, exhibit a non trivial Doppler shift of the sound velocities. The peculiarity is due to the inter-species interaction and the possibility of generating a counter-flow persistent current. Analytic predictions are derived by using superfluid hydrodynamics. While the existence of anomalous Doppler shifts at finite temperature has been discussed a long time ago in the case of superfluid Helium-4, an experimental verification of the effect is still missing. For this reason, we also propose a protocol for the measurement of the Doppler shifts, based on the density-density response function. The dynamical protocol is simulated by means of coupled Gross-Pitaevskii equations.
Cite
@article{arxiv.2508.04398,
title = {Anomalous Doppler effect in two-component Bose-Einstein condensates},
author = {Tomasz Zawiślak and Sandro Stringari and Alessio Recati},
journal= {arXiv preprint arXiv:2508.04398},
year = {2025}
}