---
res:
  bibo_abstract:
  - We review our theoretical results of the sound propagation in two-dimensional
    (2D) systems of ultracold fermionic and bosonic atoms. In the superfluid phase,
    characterized by the spontaneous symmetry breaking of the U(1) symmetry, there
    is the coexistence of first and second sound. In the case of weakly-interacting
    repulsive bosons, we model the recent measurements of the sound velocities of
    39K atoms in 2D obtained in the weakly-interacting regime and around the Berezinskii–Kosterlitz–Thouless
    (BKT) superfluid-to-normal transition temperature. In particular, we perform a
    quite accurate computation of the superfluid density and show that it is reasonably
    consistent with the experimental results. For superfluid attractive fermions,
    we calculate the first and second sound velocities across the whole BCS-BEC crossover.
    In the low-temperature regime, we reproduce the recent measurements of first-sound
    speed with 6Li atoms. We also predict that there is mixing between sound modes
    only in the finite-temperature BEC regime.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Luca
      foaf_name: Salasnich, Luca
      foaf_surname: Salasnich
  - foaf_Person:
      foaf_givenName: Alberto
      foaf_name: Cappellaro, Alberto
      foaf_surname: Cappellaro
      foaf_workInfoHomepage: http://www.librecat.org/personId=9d13b3cb-30a2-11eb-80dc-f772505e8660
    orcid: 0000-0001-6110-2359
  - foaf_Person:
      foaf_givenName: Koichiro
      foaf_name: Furutani, Koichiro
      foaf_surname: Furutani
  - foaf_Person:
      foaf_givenName: Andrea
      foaf_name: Tononi, Andrea
      foaf_surname: Tononi
  - foaf_Person:
      foaf_givenName: Giacomo
      foaf_name: Bighin, Giacomo
      foaf_surname: Bighin
      foaf_workInfoHomepage: http://www.librecat.org/personId=4CA96FD4-F248-11E8-B48F-1D18A9856A87
    orcid: 0000-0001-8823-9777
  bibo_doi: 10.3390/sym14102182
  bibo_issue: '10'
  bibo_volume: 14
  dct_date: 2022^xs_gYear
  dct_identifier:
  - UT:000875039200001
  dct_isPartOf:
  - http://id.crossref.org/issn/2073-8994
  dct_language: eng
  dct_publisher: MDPI@
  dct_subject:
  - Physics and Astronomy (miscellaneous)
  - General Mathematics
  - Chemistry (miscellaneous)
  - Computer Science (miscellaneous)
  dct_title: First and second sound in two-dimensional bosonic and fermionic superfluids@
...