Les gaz superfluides de fermions de spin , condensés par paires, sont censés présenter à vecteur d’onde non nul un mode d’excitation collectif encore inobservé dans leur continuum de paire brisée. À l’aide de la théorie BCS à température nulle et dans la limite des grandes longueurs d’onde, nous prédisons que ce mode est quantitativement observable (en fréquence, largeur et poids spectral) dans la réponse d’un gaz d’atomes froids à une excitation de Bragg par laser, si l’on mesure la perturbation induite sur le module du paramètre d’ordre plutôt que sur la densité.
The superfluid, pair condensed spin- Fermi gases are supposed to exhibit at nonzero wave vector a still unobserved collective excitation mode in their pair-breaking continuum. Using BCS theory at zero temperature and in the long wavelength limit, we predict that this mode is quantitatively observable (in frequency, width and spectral weight) in the response of a cold atom gas to a laser Bragg excitation, if one measures the perturbation induced on the order parameter modulus rather than on the density.
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Keywords: Fermi gases, Pair condensate, Collective modes, Dynamic structure factor, Pair-breaking excitation, Ultracold atoms, BCS theory
CC-BY 4.0
@article{CRPHYS_2020__21_3_203_0,
author = {Yvan Castin},
title = {Spectroscopie de {Bragg} et mode du continuum de paire bris\'ee dans un gaz de fermions superfluide},
journal = {Comptes Rendus. Physique},
pages = {203--219},
publisher = {Acad\'emie des sciences, Paris},
volume = {21},
number = {3},
year = {2020},
doi = {10.5802/crphys.33},
language = {fr},
}
Yvan Castin. Spectroscopie de Bragg et mode du continuum de paire brisée dans un gaz de fermions superfluide. Comptes Rendus. Physique, Volume 21 (2020) no. 3, pp. 203-219. doi : 10.5802/crphys.33. https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.33/
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