Bonn 2025 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 27: Poster – Ultra-cold Atoms, Ions and BEC (joint session A/Q)

Q 27.3: Poster

Dienstag, 11. März 2025, 14:00–16:00, Tent

Strongly Correlated Fermions with Cavity-mediated Long-range Interactions — •Renan da Silva Souza, Youjiang Xu, and Walter Hofstetter — Goethe- Universität, Institut für Theoretische Physik, 60438 Frankfurt am Main, Germany

Motivated by the recent experimental realization of the superradiant self-organization phase transition in ultracold Fermi gases [1], we investigate a gas of spin-1/2 fermions in a transversely pumped cavity with a static 2D optical lattice. In the dispersive regime, the system is well described by an extended Hubbard model with cavity-mediated long-range interactions. Using real-space dynamical mean-field theory (DMFT) [2], we study the paramagnetic Mott transition at half-filling. In addition to the expected metallic and Mott insulating phases, characterized respectively by a finite or vanishing quasiparticle residue at the Fermi level, we find a density wave ordered phase marked by an imbalance in the site occupations. By varying short- and long-range interaction strengths, we map the phase boundaries and establish a connection between our findings and the relationship between perfect Fermi surface nesting in the non-interacting Hamiltonian and the critical long-range interaction strength required for density wave instability.

[1] V. Helson et al. Nature 618, 716-720 (2023)

[2] M. Snoek et al. NJP 10, 093008 (2008)

Keywords: Hubbard Model; Long-range Interactions; Density Wave