Time:12:10, Monday, Feb. 24, 2025
Speaker:Dr. Jhen-Dong Lin
              Dept. of Physics, NCKU
Title: Non-Markovian Quantum Exceptional Points
Place : R36173, 1F, Dept. of Physics, Building of Science College, NCKU
Abstract:
Exceptional points (EPs) are singularities in the spectra of non-Hermitian operators, where eigenvalues and eigenvectors coalesce. Recently, open quantum systems have been increasingly explored as testbeds for quantum EPs due to their natural non-Hermitian nature. However, existing works mostly focus on the Markovian limit, leaving a gap in understanding EPs in the non-Markovian regime. In this work, I will present our new results, where we address this gap by proposing a theoretical framework based on two numerically exact descriptions of non-Markovian dynamics: the pseudomode mapping and the hierarchical equations of motion. We unveil pure non-Markovian EPs that are unobservable in the Markovian limit. Remarkably, the EP aligns with the Markovian-to-non-Markovian transition. Moreover, we show that structured environments can elevate EP order, thereby enhancing the system’s sensitivity.