Li, Jiahui

Dr. Jiahui Li is a Lecturer at the School of Physics, Henan University, China. She obtained her Ph.D. in Optics from Huazhong University of Science and Technology (HUST), Wuhan, in 2017. Following her doctoral studies, she conducted postdoctoral research at the Institute of Theoretical Physics, Chinese Academy of Sciences (ITP-CAS) in Beijing, and later at the Beijing Computational Science Research Center (CSRC). Her core expertise lies in the dynamical evolution of open quantum optical systems, with a sustained focus on dissipative phase transitions, the classical-quantum chaos correspondence, and related nonequilibrium quantum phenomena.

Spin fluctuations in the dissipative phase transitions of the quantum Rabi model

• Speaker: Jiahui Li (Henan University, China)
• Event: Quantum Technology Workshop 2026

We will present our research on dissipative phase transitions in the quantum Rabi model in this report. We highlight that significant spin fluctuations persist in the system’s stationary state, which have important consequences for the phase diagram and critical properties. In the second-order phase transition, there is a significant suppression of the order parameter and the appearance of non-universal factors, which directly reflect the spin populations. Furthermore, upon entering a parameter regime where mean-field theory predicts a tricritical phase, we find a first-order phase transition due to the unexpected collapse of superradiance. An accurate and physically transparent description going beyond mean-field theory is established by combining exact numerical simulations, the cumulant expansion, and analytical approximations based on reduced master equations and an effective equilibrium theory.