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A: Fachverband Atomphysik
A 36: Poster – Ultra-cold Atoms, Ions and BEC (joint session A/Q)
A 36.2: Poster
Donnerstag, 5. März 2026, 17:00–19:00, Philo 1. OG
Two-component lattice fermions in an optical cavity: competition between pairing orders — •Loïc Philoxene1, Michele Pini2, Francesco Piazza2, and Walter Hofstetter1 — 1Goethe- Universität, Institut für Theoretische Physik, 60438 Frankfurt am Main, Germany — 2Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
Ultracold atoms dispersively coupled to an optical cavity experience effective long range interactions, leading to a variety of symmetry breaking patterns. On the other hand, spin-1/2 lattice fermions can locally interact via the Hubbard interaction which, when attractive, generally favors pairing. By considering an ultracold gas of two-component fermionic atoms in a static optical square lattice and dispersively coupled to a ring cavity, we analyze the effects of the competition between the cavity-mediated long range interaction and the Hubbard coupling on the pairing instabilities of the Fermi surface. Using a general Hartree-Fock-Bogoliubov mean-field decoupling of the extended Hubbard Hamiltonian describing the low energy physics of the system, we focus on the competition between the Cooper pairing channel and a specific instance of pair density waves that have been shown to be exactly degenerate with the former in a recent study of a similar system with spinless fermions without an underlying lattice. In particular, we show that the Hubbard interaction lifts this degeneracy, and analyze the competition between both types of pairing order.
Keywords: Ultracold fermions in a cavity; Extended Hubbard model; Superconductivity; Pair density waves