2025/04/01 by H. Z. Shen, X. C. Zhang, X.-C. Zhang +11
Physics and Astronomy · #Quantum Mechanics and Non-Hermitian Physics #Quantum chaos and dynamical systems #Nonlinear Waves and Solitons
paper · pdf · doi:10.1002/lpor.71535
ABSTRACT Exceptional points (EPs) are central to non‐Hermitian physics because of their unique properties and broad application prospects. While extensively studied in parity‐time ()‐symmetric systems and under Markovian dynamics, their exploration in broader pseudo‐Hermitian settings, particularly in those involving non‐Markovian environments, remains largely unexplored. In this study, we investigate a pseudo‐Hermitian system consisting of three coupled optical cavities interacting with non‐Markovian environments. Compared to the Markovian baseline, we demonstrate that the emergence of non‐Markovian memory effects enlarges the dimensionality of the parameter space of the system, thereby giving rise to higher‐order EPs. Furthermore, we show that these non‐Markovianity‐induced higher‐order EPs admit a topological characterization as defects in the relevant pseudo‐Hermitian parameter space, with quantized charges described by resultant winding numbers. Moreover, we observe that the pseudo‐Hermitian system with an effective gain induced by coherent perfect absorption enables the higher‐order EPs to be directly read out from the output spectrum. We also note that the non‐Markovian mechanism for generating higher‐order EPs is not restricted to pseudo‐Hermitian systems, but can be extended to generic non‐Hermitian quantum systems. Additionally, possible experimental implementations based on superconducting circuits are also discussed.