Dissipation-induced Sachdev-Ye-Kitaev physics in many-body cavity quantum electrodynamics

Can native dissipation in cavity quantum electrodynamics (QED) devices be harnessed to realize and control dissipative quantum chaos (DQC) of the Sachdev-Ye-Kitaev (SYK) type, bypassing the complex time-dependent protocols previously required to achieve unitary SYK dynamics?

The authors investigate a two-dimensional gas of ultracold fermionic atoms coupled to optical cavity modes in the dispersive regime. They examine two distinct setups: single-mode cavities with atomic spontaneous emission and multimode cavities with photon leakage. By tuning control parameters such as the Lamb-Dicke parameter and the cavity-mode spacing, they vary the dissipative rank of the system. Chaos and integrability are diagnosed using singular spectral form factors (sigma SFF), dissipative spectral form factors (DSFF), complex spacing ratios, and the real-time dynamics of orbital occupations and entanglement entropy.

Both single-mode spontaneous emission and multimode cavity loss drive the open quantum system into the same non-Hermitian random-matrix universality class, specifically corresponding to transposition-symmetric matrices (AI symmetry class). In the single-mode setup, increasing atomic spontaneous emission creates quantum chaos from an underlying integrable Hamiltonian. Conversely, decreasing the mode-spacing parameter in multimode cavities transitions the system into chaotic open SYK dynamics. This crossover manifests dynamically as a transition from a long-lived prethermal memory phase to rapid thermalization, observable through single-atom density measurements.

This work establishes cavity QED as a hardware-efficient, natively dissipative platform for generating and controlling quantum chaos and holographic toy models without requiring fine-tuned coherent control protocols.