Entanglement in string theory, and Generalized entropy for generalized subregions in quantum gravity


Friday, February 9, 2024
12:30 - 13:30


The first speaker will be Upamanyu who will tell us about

Title: Entanglement in string theory

Abstract: The finiteness of the entanglement entropy in string theory has crucial implications for the information paradox, quantum gravity, and holography. In my talk, I will describe the recent progress made on establishing this finiteness. I will describe the orbifold construction appropriate for analyzing entanglement in string theory, the tachyonic divergences that one encounters and how we get a finite and calculable answer for the entanglement entropy, including ten-dimensional string theory, compactification to lower dimensions and black holes in AdS spacetime. (Based on works in collaboration with Atish Dabholkar).

Then we will hear from Antony on

Title: Generalized entropy for generalized subregions in quantum gravity

Abstract: I will describe a construction of algebras of observables associated with local subregions in quantum gravity in the small G_N limit. This algebra consists of operators dressed to a semiclassical observer degree of freedom which serves as an anchor defining the subregion. I will argue that properly implementing the gravitational constraints on this algebra results in a type II von Neumann algebra, which possesses a well-defined notion of entropy. Up to a state-independent constant, this entropy agrees with the UV-finite generalized entropy of the subregion, consisting of a Bekenstein-Hawking area term and a bulk entropy term. This gives an algebraic interpretation of the generalized entropy, and provides a number of tools for investigating aspects of semiclassical gravitational entropy, including the generalized second law, the quantum focusing conjecture, and the quantum extremal surface prescription in holography.


String Theory group


UvA - Faculty of Science

Room number



Group Seminar


quantum matter, string theory


Upamanyu Moitra, Antony Speranza

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