Event Category: String Seminar

String Seminar:
Tuesdays at 3:40pm on campus

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Abstract: We discuss dilaton gravity with potentials that are deformed away from JT gravity. We discuss semi-classical solutions with these potentials and elucidate new complex saddles at fixed energy which contribute to the density of states. We also discuss how to reproduce the semi-classical limit of a formula for the density of states first derived by using the connection between … Read More

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Abstract: The idea that spacetime may be discrete in the UV, possibly at the Planck scale, has been fraught with issues due to generically strong effects of such discreteness on the flow of a quantum field theory down to the IR. Nevertheless, recent work on two dimensional models of holography seem to provide an example of the emergence of spacetime from … Read More

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Abstract: Geodesics play an important role in holographic quantities such as entropy and complexity. It is therefore of interest to understand to what extent these results can be generalized to De Sitter space. In this talk, I will derive a geodesic approximation to two-point correlation functions of heavy fields in De Sitter space. Intriguingly, this approximation involves a sum over … Read More

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Abstract: We describe the dynamical evaporation of a black hole as the classical evolution in time of a black hole in an Anti-de Sitter braneworld. A bulk black hole whose horizon intersects the brane yields the classical bulk dual of a black hole coupled to quantum conformal fields. The evaporation of this black hole happens when the bulk horizon slides off … Read More

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Abstract: Recently, Danielson, Satishchandran, and Wald proposed a novel mechanism for decoherence in spacetimes with Killing horizons. When Alice performs a Stern-Gerlach type experiment outside the horizon, there is a fundamental rate of decoherence due to the emission of soft gravitons/photons that radiate away information. In this talk, I will sharpen and generalize this mechanism by recasting the gedankenexperiment in … Read More

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Abs: Historically tensor networks have been helpful models of AdS/CFT, but there have always been some aspects that they fail to capture, particularly those involving the time direction. In this talk I will take the perspective that we can learn a lot from trying to incorporate these aspects into tensor networks, and I will explain some progress on resolving the … Read More

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Abstract: We analyze the algebra of boundary observables in canonically quantised JT gravity with or without matter. In the absence of matter, this algebra is commutative, generated by the ADM Hamiltonian. After coupling to a bulk quantum field theory, it becomes a highly noncommutative algebra of Type II∞ with a trivial center. As a result, density matrices and entropies on … Read More

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Abstract: We consider higher-spin gravity in (A)dS_4, defined as the holographic dual of a free O(N) or Sp(N) vector model. At the quartic level, this theory has been judged non-local at distances greater than the (A)dS radius, due to a mismatch of massless (twist=1) exchange-type terms in its boundary OPE behavior. We review the non-locality argument, and note that it relies … Read More