Over the past decade, composite interacting light-matter systems have emerged as versatile platforms for exploring nonequilibrium phenomena in condensed matter physics. Owing to their driven-dissipative nature, these hybrid systems are subject to both atomic and photonic fluctuations, giving rise to rich dynamical behavior, including the emergence of metastable states. A metastable state is dynamically stable yet distinct from the thermodynamic ground state, and is therefore intrinsically nonequilibrium. This phenomenon is fundamentally different from prethermalization, where long-lived states arise due to approximate conservation laws rather than dynamical stabilization. In this talk, I will present several examples ranging from open photon Bose-Einstein condensates to Dicke superradiance, as well as more recent extensions such as the Dicke-Bose-Hubbard model. In these systems, metastable states can emerge in both atomic and photonic degrees of freedom through different mechanisms of dynamical stabilization.

References
[1] M. Janning, R. Kramer, M. Turaev, S. Ray, and J. Kroha, Emergent thermal fluctuations and non-Hermitian phase transitions in open photon condensates, arXiv:2603.21927 (2026).
[2] A. Abouelela, M. Turaev, R. Kramer, M. Janning, M. Kajan, S. Ray, and J. Kroha, Stabilizing Open Photon Condensates by Ghost-Attractor Dynamics, Phys. Rev. Lett. 135, 053402 (2025).
[3] T. Wu, S. Ray, and J. Kroha, Temporal bistability in the dissipative Dicke-Bose-Hubbard system, Ann. Phys. (Berlin) 536, 2300505 (2024).
[4] S. Ray , A. Vardi, and D. Cohen, Quantum signatures in quench from chaos to superradiance, Phys. Rev. Lett. 128, 130604 (2022),