Abstract
Non-Hermitian systems with parity-time () symmetry give rise to exceptional points (EPs) with exceptional properties that arise due to the coalescence of eigenvectors. Such systems have been extensively explored in the classical domain, where second- or higher-order EPs have been proposed or realized. In contrast, quantum information studies of -symmetric systems have been confined to systems with a two-dimensional Hilbert space. Here, by using a single-photon interferometry setup, we simulate the quantum dynamics of a four-dimensional -symmetric system across a fourth-order exceptional point. By tracking the coherent, nonunitary evolution of the density matrix of the system in -symmetry unbroken and broken regions, we observe the entropy dynamics for both the entire system, and the gain and loss subsystems. Our setup is scalable to the higher-dimensional -symmetric systems, and our results point towards the rich dynamics and critical properties.
- Received 30 April 2020
- Accepted 18 August 2020
DOI:https://doi.org/10.1103/PhysRevA.102.030201
©2020 American Physical Society