Würzburg Seminar on Quantum Field Theory and Gravity

It is believed that entanglement plays a central role in the emergence of semiclassical geometry in holographic theories. However, the role of mixed-state or multipartite entanglement remains largely unexplored. In this talk, I will discuss a useful diagnostic of mixed-state entanglement known as the computable cross-norm or realignment (CCNR) in the context of holography. I will discuss the calculation of the CCNR in random tensor networks and holographic CFTs. For general semiclassical states, I will argue for a holographic dual which involves a backreacted entanglement wedge cross-section in a geometry sourced by Rényi-2 cosmic branes. Specializing to the case of two intervals in a hyperbolic random tensor network as well the vacuum state of a 2D holographic CFT, I will describe the occurrence of a connected-to-disconnected phase transition which is directly related to the Hawking-Page transition. Finally, I will discuss some potentially interesting open problems for holographic CCNR and related quantities.