Collisionless sound of bosonic superfluids in lower dimensions

Year: 2021

Authors: Salasnich L.; Sattin F.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; Univ Padua, CNISM, Via Marzolo 8, I-35131 Padua, Italy; Consiglio Nazl Ric CNR, Ist Nazl Ott INO, Via Nello Carrara 1, I-50125 Sesto Fiorentino, Italy; Ist Nazl Fis Nucl INFN, Sez Padova, Via Marzolo 8, I-35131 Padua, Italy; Univ Padua, Consorzio RFX, Acciaierie Venete SpA, Ist Nazl Fis Nucl,CNR ENEA, Corso Stati Uniti 4, I-35127 Padua, Italy.

Abstract: The superfluidity of low-temperature bosons is well established in the collisional regime. In the collisionless regime, however, the presence of superfluidity is not yet fully clarified, in particular in lower spatial dimensions. Here, we compare the Vlasov-Landau equation, which does not take into account the superfluid nature of the bosonic system, with the Andreev-Khalatnikov equations, which instead explicitly contain a superfluid velocity. We show that recent experimental data of the sound mode in a two-dimensional collisionless Bose gas of Rb-87 atoms are in good agreement with both theories, but the sound damping is better reproduced by the Andreev-Khalatnikov equations below the Berezinskii-Kosterlitz-Thouless critical temperature T-c, while above T-c the Vlasov-Landau results are closer to the experimental ones. For one-dimensional bosonic fluids, where experimental data are not yet available, we find larger differences between the sound velocities predicted by the two transport theories and, also in this case, the existence of a superfluid velocity reduces the sound damping.

Journal/Review: PHYSICAL REVIEW A

Volume: 103 (4)      Pages from: 043324-1  to: 043324-6

KeyWords: HELIUM
DOI: 10.1103/PhysRevA.103.043324

Citations: 1
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