Observation of critical phenomena in parity-time-symmetric quantum dynamics

Abstract: In this talk, I will present an experimental simulation of non-unitary quantum dynamics using a single-photon interferometric network and study the information ow between a parity-time (PT)-symmetric non-Hermitian system and its environment. We observe oscillations of quantum-state distinguishability and complete information retrieval in the PT-symmetry-unbroken regime. We then characterize in detail critical phenomena of the information ow near the exceptional point separating the PT-unbroken and-broken regimes, and demonstrate the expected power-law behavior in key quantities such as the distinguishability and the recurrence time. Finally, by introducing an ancilla as an environment and probing quantum entanglement between the system and the environment, we confirm that the observed information retrieval is induced by a finite-dimensional entanglement partner in the environment.