Sound propagation in two-dimensional cold atoms

Sound propagation is a macroscopic manifestation of the interplay between the equilibrium thermodynamics and the dynamical transport properties of fluids. It then represents an intriguing diagnostics tool to test microscopic theories and their emergent features condensed matter systems.

Concerning quantum liquids in their superfluid phase, the renowned Landau’s two-fluid theory successfully explained 4He experiments, but it cannot be taken for granted in cold atoms platforms, which usually deal with weakly interacting and much more dilute physical systems. 

In this talk, we present some recent results on both Bose and Fermi systems in two dimensions. Here, second sound measurements are a promising candidate to reveal the onset of the BKT transition, which is somehow more elusive than expected in cold atoms.  Future developments and proposals are discussed in the end.

References

1. A. Cappellaro, F. Toigo and L. Salasnich, Phys. Rev. A. 98, 043605 (2018).

2. A. Tononi, A. Cappellaro, G. Bighin and L. Salasnich, arXiv:2009.06491 (2020).