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arXiv · 2508.04398

Anomalous Doppler effect in two-component Bose-Einstein condensates

Tomasz Zawiślak·Sandro Stringari·Alessio Recati
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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.

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Tomasz Zawiślak, Sandro Stringari, Alessio Recati. 2025-08-06. Anomalous Doppler effect in two-component Bose-Einstein condensates. https://doi.org/10.1103/yc6t-13d4

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