[Transport quantique dans des gaz de fermions fortement corrélés]
Le transport dans les fermions fortement corrélés ne peut être compris par les seules quasiparticules fermioniques. Nous présentons un cadre théorique pour le transport quantique qui incorpore les fortes corrélations locales des paires de fermions. Ces corrélations de contact ajoutent des contributions essentielles aux coefficients de transport visqueux, thermique et sonore. La viscosité de volume, en particulier, reçoit sa contribution dominante des excitations de paires. En outre, elle peut être mesurée de manière élégante en observant la réponse à une longueur de diffusion dépendant du temps, même lorsque le fluide n’est pas en mouvement. Des changements rapides de la longueur de diffusion éloignent le système de l’équilibre local, et nous montrons comment il retourne à l’équilibre en suivant un attracteur hydrodynamique avant qu’une description de Navier–Stokes ne devienne correcte. Cet article résume un exposé donné au symposium « Open questions in the quantum many-body problem » à l’Institut Henri Poincaré, Paris, en juillet 2024.
Transport in strongly correlated fermions cannot be understood by fermionic quasiparticles alone. We present a theoretical framework for quantum transport that incorporates strong local correlations of fermion pairs. These contact correlations add essential contributions to viscous, thermal and sound transport coefficients. The bulk viscosity, in particular, receives its dominant contribution from pair excitations. Moreover, it can be measured elegantly by observing the response to a time-dependent scattering length even when the fluid is not moving. Rapid changes of the scattering length drive the system far out of local equilibrium, and we show how it relaxes back to equilibrium following a hydrodynamic attractor before a Navier–Stokes description becomes valid. This paper summarizes a talk given at the Symposium “Open questions in the quantum many-body problem” at the Institut Henry Poincaré, Paris, in July 2024.
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Mots-clés : Fermions fortement corrélés, Transport quantique, Viscosité de volume, Hydrodynamique, Attracteur
Tilman Enss 1
CC-BY 4.0
@article{CRPHYS_2025__26_G1_217_0,
author = {Tilman Enss},
title = {Quantum transport in strongly correlated {Fermi} gases},
journal = {Comptes Rendus. Physique},
pages = {217--224},
publisher = {Acad\'emie des sciences, Paris},
volume = {26},
year = {2025},
doi = {10.5802/crphys.237},
language = {en},
}
Tilman Enss. Quantum transport in strongly correlated Fermi gases. Comptes Rendus. Physique, Volume 26 (2025), pp. 217-224. doi : 10.5802/crphys.237. https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.237/
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