2023/06/02 by A. Milner, Milner, Alexander A., Valery Milner +1
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #Quantum Gases (cond-mat.quant-gas) #Quantum Physics (quant-ph) #Quantum, superfluid, helium dynamics #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.2306.01955
openalex publication_date 2023/06/02 · openalex created_date 2023/06/07 · openalex updated_date 2026/07/28
We experimentally demonstrate a controlled transfer of angular momentum to roton pairs in superfluid helium. The control is executed with an optical centrifuge and detected with coherent time- and frequency-resolved Raman scattering. We show that the sign of the Raman shift, and hence the orientation of the angular momentum transferred from the laser field to the rotons, is dictated by the centrifuge. The magnitude of the shift reflects the two-roton energy and indicates that the centrifuge-induced hot roton pairs are far from the equilibrium with the colder quantum bath. The observed decay of the coherent Raman signal suggests that the decoherence is governed by the scattering on thermal rotons and phonons. The demonstrated method offers ways of examining microscopic origins of superfluidity by controlling collective excitations in superfluids.