Discontinuities in the First and Second Sound Velocities at the Berezinskii-Kosterlitz-Thouless Transition

Year: 2014

Authors: Ozawa T., Stringari S.

Autors Affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy

Abstract: We calculate the temperature dependence of the first and second sound velocities in the superfluid phase of a 2D dilute Bose gas by solving Landau’s two fluid hydrodynamic equations. We predict the occurrence of a significant discontinuity in both velocities at the critical temperature, as a consequence of the jump of the superfluid density characterizing the Berezinskii-Kosterlitz-Thouless transition. The key role of the thermal expansion coefficient is discussed. We find that second sound in this dilute Bose gas can be easily excited through a density perturbation, thereby, making the perspective of the measurement of the superfluid density particularly favorable.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 112 (2)      Pages from: 25302-1  to: 25302-5

More Information: We are grateful to stimulating discussions with Lev P. Pitaevskii. Useful discussions with Yan-Hua Hou, Iacopo Carusotto, and Jean Dalibard are also acknowledged. This work was supported by the ERC through the QGBE grant and by Provincia Autonoma di Trento.
KeyWords: Long-range Order; 2-dimensional Systems; He-4 Films; Density; Gas
DOI: 10.1103/PhysRevLett.112.025302

ImpactFactor: 7.512
Citations: 26
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