For the first time, a gravitational calculation was recently shown to yield the Page curve for the entropy of Hawking radiation, consistent with unitary evolution. However, the calculation takes as essential input Hawking’s result that the radiation entropy becomes large at late times. We call this apparent contradiction the state paradox. We exhibit its manifestations in standard and doubly-holographic settings, … Read More
The QES prescription is a rule for computing entanglement entropies in quantum gravity that has become one of the central tools in holography. In particular, it was crucial to recent progress on understanding the Page curve for evaporating black holes. However, as I will show, a naïve application of the QES prescription for arbitrary bulk states is paradoxical, even at … Read More
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 describe a bulk procedure that generates a sequence of coarse-grained holographic states by disentangling degrees of freedom at short distances. This is manifested as a flow in the bulk which approaches quantum extremal surfaces. This procedure generalizes an earlier classical construction by including bulk quantum corrections. ========= You will have to login into your Zoom account in … Read More
Abstract: I will describe work in progress with Ooguri on the singularities of the two point function at finite temperature in a conformal field theory in more than two dimensions. At weak coupling the only singularity is on the light cone, but in the large N, large lambda regime a new singularity emerges. This new singularity corresponds to a null … Read More
Abstract: “I will present a holographic framework for reconstructing the experience of bulk observers in AdS/CFT. In particular, I will show how to recover the proper time and energy distribution measured along bulk worldlines, directly in the CFT via a universal, background-independent prescription. For an observer falling into an eternal AdS black hole, the proposal resolves a conceptual puzzle raised … 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