IAS High Energy Theory Seminar

Entanglement Entropy in Flat Holography

Wei Song
Member, School of Natural Sciences, Institute for Advanced Study; Tsinghua University
May 15, 2020
The appearance of BMS symmetry as the asymptotic symmetry of Minkowski spacetime suggests a holographic relation between Einstein gravity and quantum field theory with BMS invariance, dubbed BMSFT. With a three dimensional bulk, the dual BMSFT is a non-Lorentz invariant, two dimensional field theory with infinite-dimensional symmetries. In this talk, I will argue that entanglement entropy in BMSFT can be described by a swing surface in the bulk.

A Quantum Circuit Interpretation of Evaporating Black Hole Geometry

Ying Zhao
Member, School of Natural Sciences, Institute for Advanced Study
May 1, 2020
Abstract: When Alice shares thermofield double with Bob, her time evolution can make the wormhole grow. We identify different kinds of operations Alice can do as being responsible for the growth of different parts of spacetime and see how it fits together with subregion duality. With this, we give a quantum circuit interpretation of evaporating black hole geometry. We make an analogy between the appearance of island for evaporating black hole and the transition from two-sided to one-sided black hole in the familiar example of perturbed thermofield double.

Twisted M-theory and Holography

Davide Gaiotto
Perimeter Institute
April 27, 2020
A few years ago, K.Costello proposed how to isolate a self-contained, protected subsector of the M2 brane AdS4/CFT3 correspondence and demonstrated the holographic duality explicitly for the OPE of the corresponding boundary local operators. The construction can be naturally extended to protected correlation functions, but several new challenges arise. I will discuss how to take the large N limit on the CFT3 side of the story.

A Tutorial on Entanglement Island Computations

Raghu Mahajan
Member, School of Natural Sciences, Institute for Advanced Study
April 17, 2020
In this talk we will present details of quantum extremal surface computations in a simple setup, demonstrating the role of entanglement islands in resolving entropy paradoxes in gravity. The setup involves eternal AdS2 black holes in thermal equilibrium with auxiliary bath systems. We will also describe the extension of this setup to higher dimensions using Randall-Sundrum branes.

A New Topological Symmetry of Asymptotically Flat Spacetimes

Uri Kol
New York University
April 13, 2020
Abstract: I will show that the isometry group of asymptotically flat spacetimes contains, in addition to the BMS group, a new dual supertranslation symmetry. The corresponding new conserved charges are akin to the large magnetic U(1) charges in QED. They factorize the Hilbert space of asymptotic states into distinct super-selection sectors and reveal a rich topological structure exhibited by the asymptotic metric.

Geometry and 5d N=1 QFTs

Lakshya Bhardwaj
Harvard University
March 30, 2020
I will explain that a geometric theory built upon the theory of complex surfaces can be used to understand wide variety of phenomena in five-dimensional supersymmetric theories, which includes the following: Classification of 5d superconformal field theories (SCFTs)
Enhanced flavor symmetries of 5d SCFTs
5d N=1 gauge theory descriptions of 5d and 6d SCFTs
Dualities between 5d N=1 gauge theories
T-dualities between 6d N=(1,0) little string theories

Solving Random Matrix Models with Positivity

Henry Lin
Princeton University
March 27, 2020
Abstract: A new approach to solving random matrix models directly in the large N limit is developed. First, a set of numerical values for some low-pt correlation functions is guessed. The large N loop equations are then used to generate values of higher-pt correlation functions based on this guess. Then one tests whether these higher-pt functions are consistent with positivity requirements, e.g., tr M^{2k} > 0. If not, the guessed values are systematically ruled out.

How to See Everything in the Entanglement Wedge

Adam Levine
Member, School of Natural Sciences, Institute for Advanced Study
March 20, 2020
Abstract: We will describe work in progress in which we argue that a generalization of the procedure developed by Gao-Jafferis-Wall can allow one to see the entirety of the entanglement wedge. Gao-Jafferis-Wall demonstrated that one can see excitations behind the horizon by deforming the boundary Hamiltonian using a non-local operator. We will argue in a simple class of examples that deforming the boundary Hamiltonian by a specific modular Hamiltonian can allow one to see (almost) everything in the entanglement wedge.

Covariant Phase Space with Boundaries

Daniel Harlow
Massachusetts Institute of Technology
March 16, 2020
The Hamiltonian formulation of mechanics has many advantages, but its standard presentation destroys manifest covariance. This can be avoided by using the "covariant phase formalism" of Iyer and Wald, but until recently this formalism has suffered from several ambiguities related to boundary terms and total derivatives. In this talk I will present a new version of the formalism which incorporates boundary effects from the beginning.