The fate of the Fermi surface coupled to a single-wave-vector cavity mode

Fuente: arXiv
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Auteurs principaux: Frank, Bernhard, Pini, Michele, Lang, Johannes, Piazza, Francesco
Format: Preprint
Publié: 2025
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author Frank, Bernhard
Pini, Michele
Lang, Johannes
Piazza, Francesco
author_facet Frank, Bernhard
Pini, Michele
Lang, Johannes
Piazza, Francesco
contents The electromagnetic field of standing-wave or ring cavities induces a spatially modulated, infinite-range interaction between atoms in an ultracold Fermi gas, with a single wavelength comparable to the Fermi length. This interaction has no analog in other systems of itinerant particles and has so far been studied only in the regime where it is attractive at zero distance. Here, we fully solve the problem of competing instabilities of the Fermi surface induced by single-wavelength interactions. We find that while the density-wave (superradiant) instability dominates on the attractive side, it is absent for repulsive interactions, where the competition is instead won by non-superradiant superfluid phases at low temperatures, with Fermion pairs forming at both vanishing and finite center-of-mass momentum. Moreover, even in the absence of such symmetry-breaking instabilities, we find the Fermi surface to be always nontrivially deformed from an isotropic shape. We estimate this full phenomenology to be within reach of dedicated state-of-the-art experimental setups.
format Preprint
id arxiv_https___arxiv_org_abs_2505_11452
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The fate of the Fermi surface coupled to a single-wave-vector cavity mode
Frank, Bernhard
Pini, Michele
Lang, Johannes
Piazza, Francesco
Quantum Gases
Atomic Physics
Quantum Physics
The electromagnetic field of standing-wave or ring cavities induces a spatially modulated, infinite-range interaction between atoms in an ultracold Fermi gas, with a single wavelength comparable to the Fermi length. This interaction has no analog in other systems of itinerant particles and has so far been studied only in the regime where it is attractive at zero distance. Here, we fully solve the problem of competing instabilities of the Fermi surface induced by single-wavelength interactions. We find that while the density-wave (superradiant) instability dominates on the attractive side, it is absent for repulsive interactions, where the competition is instead won by non-superradiant superfluid phases at low temperatures, with Fermion pairs forming at both vanishing and finite center-of-mass momentum. Moreover, even in the absence of such symmetry-breaking instabilities, we find the Fermi surface to be always nontrivially deformed from an isotropic shape. We estimate this full phenomenology to be within reach of dedicated state-of-the-art experimental setups.
title The fate of the Fermi surface coupled to a single-wave-vector cavity mode
topic Quantum Gases
Atomic Physics
Quantum Physics
url https://arxiv.org/abs/2505.11452