Discontinuities in the first and second sound velocities at the Berezinskii-Kosterlitz-Thouless transition.
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.
INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy.
Tomoki
T
Ozawa
INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy.
Sandro
S
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