EMP is funded through the Horizon2020 programme of the European Commission.
Selected Publications

Vortex-mediated relaxation of magnon BEC into light Higgs quasiparticles

S. Autti, P. J. Heikkinen, S. M. Laine, J. T. Mäkinen, E. V. Thuneberg, V. V. Zavjalov, V. B. Eltsov

A magnon Bose-Einstein condensate (BEC) in superfluid 3 He is a fine instrument for studying the surrounding macroscopic quantum system. At zero temperature, the BEC is subject to a few distinct forms of decay into other collective excitations, owing to momentum and energy conservation in a quantum vacuum. We study the vortex-Higgs mechanism: The vortices relax the requirement for momentum conservation, allowing the optical magnons of the BEC to transform into light Higgs quasiparticles. This facilitates a direct measurement of the dimensions of the B -phase double-core vortex, providing experimental access to elusive phenomena, such as the Kelvin wave cascade and core-bound Majorana fermions. Our paper expands the spectrum of possible interactions between magnetic quasiparticles in 3 He − B and lays the groundwork for building magnon-based quantum devices.

Phys. Rev. Research 3, L032002 (2021)

doi: 10.1103/PhysRevResearch.3.L032002