Bose-Einstein condensate of magnons in superfluid -B as a tuned resonant quantum amplifier
Phys. Rev. B 114, 214506 – Published 9 October, 2026
DOI: https://doi.org/10.1103/gnbl-5w77
Abstract
We show that the Bose-Einstein condensate (BEC) of magnons in superfluid -B in the form of a homogeneously precessing domain can be used as a new type of tuned resonant quantum amplifier. The underlying physical principle of the resonant amplification is the violation of the U(1) (calibration) symmetry in this coherent magnonic system which opens an energy gap in the spectrum of collective excitations. We demonstrate that the magnon resonance amplifier operates in two reference frames: (i) in the rotating frame without thermal bath, where the signal is detected and (ii) in the laboratory frame, where the signal is measured, as a consequence of the Cooper pairs decay. As the thermal bath is not present in the rotating frame of reference, the amplifier may achieve an extremely low effective noise temperature. The proposed principle of the quantum amplification can be tested in other physical systems, where the BEC of magnons has been observed and these systems exhibit the violation of U(1) symmetry.
