Abstract: I’ll discuss ways to quantify multipartite correlations, in quantum information and in holography. We’ll focus on optimized correlation measures: linear combinations of entropies minimized over all possible purifications of a state that also satisfy monotonicity conditions. These contain far more information about correlations than entanglement entropy alone. We give a procedure to derive such quantities, and construct a menagerie … Read More

Abstract: I will introduce a GNS construction as a formalism to study baby universes. This naturally shifts the primordial role to the algebra of observables rather than the Hilbert spaces. I will explicitly form baby universe operations and utilize them to build baby universe algebras. Using these ingredients, I will construct the baby universe Hilbert spaces. I will highlight that … Read More

Abstract:I will discuss how the central charges appearing in near-horizon symmetry algebras arise from an anomalous transformation of the null boundary term in the gravitational action.  This parallels the way in which the holographic Weyl anomaly appears in AdS/CFT, with the ambiguity in the normalization of the null generator being the analogue of the choice of Weyl frame.  As an … Read More

Abstract: I discuss string theory on AdS3xS3xT4 in the tensionless limit, with one unit of NS-NS flux. This theory is conjectured to be dual to the symmetric product orbifold CFT. I show how to compute the full string partition function on various locally AdS3 backgrounds, such as thermal AdS3, the BTZ black and conical defects, and find that it is independent of the … Read More

Abstract: We discover a wide range of new nonperturbative effects in quantum gravity, namely moduli spaces of constrained saddles (often called constrained instantons) of the Einstein-Hilbert action. We find these in all spacetime dimensions, for AdS and dS. Many can be written in closed form, and some are shown to be quadratically stable. In the Euclidean AdS setting, these constrained … Read More

Abstract: A large class of two-dimensional dilaton-gravity theories in asymptotically AdS2 spacetimes are holographically dual to a matrix integral, interpreted as an ensemble average over Hamiltonians. Viewing these theories as Jackiw-Teitelboim gravity with a gas of defects, I will show how to extend this duality to a broader class of dilaton potentials compared to previous work by including conical defects … Read More

Abstract: Standard lore holds that a consistent theory of quantum gravity cannot have exact global symmetries. In this talk, we will show how simple generalizations of this lore can be used to motivate a number of other well-supported “Swampland conjectures,” thereby highlighting the importance of global symmetries for understanding universal features of quantum gravity.

Abstract:We discuss the role of wormholes and eigenbranes in reconciling geometry with quantum mechanics, working within two dimensional dilaton gravity. First, we review how wormholes enable geometry to accurate capture averaged properties of late time correlators of chaotic quantum systems. Because these are averaged properties, naively, wormholes in gravitational theories suggest some ensemble interpretation of those gravitational theories, here embodied … Read More

Abstract:We show that the presence of replica wormholes in the Euclidean path integral of gravity leads to a non-perturbative violation of any global symmetry present in the low-energy description of quantum gravity. Explicitly, we compute the scattering probability between different charged states in several low-dimensional models of quantum gravity and find a non-vanishing answer. This suggests that the set of … Read More

Abstract: The talk will focus on the spectrum of near-extremal black holes in gravity and near-BPS black holes in supergravity. For concreteness, we will study cases in asymptotically four-dimensional flat space and three-dimensional Anti-de Sitter. This will be done by analyzing quantum effects near the horizon captured by an emergent Jackiw-Teitelboim mode at low temperatures. This will allow us to … Read More