Title: Observation of critical phenomena in parity-time-symmetric quantum dynamics Show Chinese title

Title: 在宇称-时间对称量子动力学中的临界现象观测

Abstract: We experimentally simulate non-unitary quantum dynamics using a single-photon interferometric network and study the information flow 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 flow near the exceptional point separating the PT-unbroken and -broken regimes, and demonstrate power-law behavior in key quantities such as the distinguishability and the recurrence time. We also reveal how the critical phenomena are affected by symmetry and initial conditions. Finally, 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. Our work constitutes the first experimental characterization of critical phenomena in PT-symmetric non-unitary quantum dynamics. Show Chinese abstract

Abstract: 我们使用单光子干涉网络实验模拟非幺正量子动力学，并研究宇称-时间（PT）对称的非厄米系统与其环境之间的信息流。 我们在PT对称性未被破坏的区域内观察到量子态可区分性的振荡以及信息的完全恢复。 随后，我们详细表征了在分隔PT未被破坏和被破坏区域的异常点附近的信息流临界现象，并展示了关键量如可区分性和重现实时间中的幂律行为。 我们还揭示了临界现象如何受到对称性和初始条件的影响。 最后，引入一个辅助系统作为环境，并探测系统与环境之间的量子纠缠，我们确认所观察到的信息恢复是由环境中有限维的纠缠伙伴引起的。 我们的工作构成了对PT对称非幺正量子动力学中临界现象的首次实验表征。