Observation of Spin Superfluidity in a Bose Gas Mixture

Year: 2018

Authors: Fava E., Bienaimé T., Mordini C., Colzi G., Qu C., Stringari S., Lamporesi G., Ferrari G.

Autors Affiliation: Univ Trento, INO, CNR, BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, I-38123 Povo, Italy; Ist Nazl Fis Nucl, Trento Inst Fundamental Phys & Applicat, I-38123 Povo, Italy.

Abstract: The spin dynamics of a harmonically trapped Bose-Einstein condensed binary mixture of sodium atoms is experimentally investigated at finite temperature. In the collisional regime the motion of the thermal component is shown to be damped because of spin drag, while the two condensates exhibit a counterflow oscillation without friction, thereby providing direct evidence for spin superfluidity. Results are also reported in the collisionless regime where the spin components of both the condensate and thermal part oscillate without damping, their relative motion being driven by a mean-field effect. We also measure the static polarizability of the condensed and thermal parts and we find a large increase of the condensate polarizability with respect to the T=0 value, in agreement with the predictions of theory.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 120 (17)      Pages from: 170401-1  to: 170401-6

More Information: We thank L. Pitaevskii, A. Recati, C. Fort, F. Minardi, F. Gerbier, N. Proukakis, and E. Sonin for useful comments and discussions. We acknowledge funding by the Provincia Autonoma di Trento, EC-H2020 Grant QUIC No. 641122, and Istituto Nazionale di Fisica Nucleare under the FISH project.
KeyWords: Collective Oscillations; Fermi Gas; Dynamics
DOI: 10.1103/PhysRevLett.120.170401

Citations: 48
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