Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS crossover (14 pages)

By R. Combescot, S. Stringari, M. Kagan. 2006

146 citations recorded by the source corpus.

We perform a detailed study of the collective mode across the whole crossover from the Bose-Einstein condensate (BEC)-to the BCS regime in fermionic gases at zero temperature, covering the whole range of energy beyond the linear regime. This is done on the basis of the dynamical BCS model. We recover first the results of the linear regime in a simple form. Then specific attention is paid to the nonlinear part of the dispersion relation and its interplay with the continuum of single-fermionic excitations. In particular we consider in detail the merging of the collective mode into the continuum of single-fermionic excitations. This occurs not only on the BCS side of the crossover, but also slightly beyond unitarity on the BEC side. Another remarkable feature is the very linear behavior of the dispersion relation in the vicinity of unitarity almost up to merging with the continuum. Finally, while on the BEC side the mode is quite analogous to the Bogoliubov mode, a difference appears at high wave vectors. On the basis of our results we determine the Landau critical velocity in the BEC-BCS crossover which is found to be largest close to unitarity. Our investigation has revealed interesting qualitative features whichmore » deserve experimental exploration as well as further theoretical studies by more sophisticated means.« less

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/085655571d5ab95cf616047420ca5b4b4417fa86

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. M. Zwierlein
2. W. Ketterle
3. G. Strinati
4. P. Schuck
5. G. Roepke
6. M. Urban
7. P. Pieri
8. N. Cooper

In Condensed Matter Physics

1. M. Zwierlein
2. G. Strinati
3. P. Schuck
4. G. Roepke
5. W. Ketterle
6. M. Urban
7. P. Pieri

Citations in the corpus

• The BCS–BEC crossover: From ultra-cold Fermi gases to nuclear systems (2018, methodology): “The QRPA equations were also solved for the collective modes in a uniform gas [71, 394].”
• Making, probing and understanding ultracold Fermi gases (2008, background): “The connection between the BEC and BCS results is smooth, as expected and found by [188, 208, 209].”