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Q: Fachverband Quantenoptik und Photonik

Q 24: Ultra-cold Atoms, Ions and BEC I (joint session A/Q)

Q 24.4: Vortrag

Dienstag, 3. März 2026, 11:45–12:00, N 1

Paramagnetic Phases of Strongly Correlated Lattice 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

We investigated the steady-state paramagnetic phases of a Fermi-Hubbard model on a square lattice coupled to a transversely pumped optical cavity, using real-space dynamical mean-field theory (RDMFT) [1]. The cavity mediates long-range interactions [2] which compete with the onsite Hubbard interactions. This system exhibits a transition into a superradiant checkerboard density-wave (DW) phase with finite occupation imbalance. At quarter filling, we find that increasing temperature leads to the crystallization of a homogeneous Fermi-liquid (FL) phase into a DW phase. At half filling, we find regions of metastability between different RDMFT solutions where the occupation imbalance shows a hysteretic behavior characteristic of first order phase transitions. In those regions, the DW solution coexists with either the homogeneous FL or the Mott insulating solution. We obtain the thermodynamic phase transition by comparing the energies of the different solutions in the region of metastability.

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

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

Keywords: Fermi-Hubbard Model; Optical Cavity; Long-range Interactions