报告人：郭武中副教授，华中科技大学
邀请人：龚云贵教授
报告时间：2025年6月18日（周三），16:30
报告地点：龙赛理科楼南楼414会议室

报告人简介：
郭武中，2016年在中科院理论物理所获得博士学位，2014.10-2015.10京都大学基础理论物理研究所访问，2016年-2019年在台湾清华大学理论科学中心做博后，目前为华中科技大学物理学院副教授。研究领域为引力理论与场论，研究方向为AdS/CFT、量子纠缠等相关内容。

报告摘要：
Entanglement typically reflects quantum correlations between spacelike-separated subregions. Recent studies suggest that the concept of entanglement can be naturally extended to subregions with causal (timelike) relations. In this talk, I will briefly review the definition and motivation of entanglement in time. In QFT, using the Schwinger–Keldysh path integral formalism and the real-time replica method, one can define and compute physically meaningful quantities related to timelike entanglement, including entanglement entropy, entanglement negativity, and reflected entropy. Timelike entanglement is closely related to causality and the dynamics of the theory. In field theory, we can construct connections between timelike and spacelike entanglement entropies. On the other hand, for field theories with gravitational duals, timelike entanglement can also be computed via the Ryu–Takayanagi (RT) formula. In certain setups, we can obtain the RT surfaces in the bulk analytically or numerically. These surfaces often extend behind the black hole horizon, thus providing new probes for the degrees of freedom inside the horizon. We further establish a relation between timelike and spacelike entanglement entropies, which, in the holographic context, can be interpreted as a classical correlation between degrees of freedom inside and outside the black hole horizon. This reflects the principle of black hole complementarity. Finally, I will comment on some open questions and possible directions toward resolving them.

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