Elba Alonso-Monsalve (MIT) “Phase space of JT gravity with positive cosmological constant”
Abstract: We construct the classical phase space of Jackiw-Teitelboim (JT) gravity with positive cosmological constant on spatial slices with circle topology. We identify solutions not previously discussed in the literature, and find the phase space has many singular points and is not even Hausdorff. Nonetheless, it admits a group-theoretic description which is quite amenable to quantization. We comment on next … Read More
Martin Sasieta (UCB) “Baby Universes from Thermal Pure States in SYK”
Abstract: I will present a simple holographic model of closed universes originating from the black hole interior in JT gravity. The model relies on the insertion of a heavy operator to support the baby universe, together with a first-order phase transition between a black hole phase and an empty AdS phase. To this end, I will employ the Maldacena–Qi phase … Read More
Batoul Banihashemi (Stanford) “Reconstruction of de Sitter space beyond a single patch”
Abstract: I will describe implementing the TTbar-formalism to construct the entire de Sitter space bounded by two timelike boundaries. In previous works a finite Hamiltonian quantum mechanics system was developed for a bulk with a single timelike boundary. The holographic dual theory contains bands of energy levels that correspond to bounded patches of semiclassical gravity with positive cosmological constant and matter. … Read More
Bartek Czech (Institute for Advanced Study, Tsinghua University) ” A lesson from stabilizer states: Holography abhors syzygies
Abstract: Stabilizer states are a convenient and well-studied class of quantum states, with many applications including quantum error correction. One reason why they may NOT be good toy models of holographic systems is that they do not generally obey the constraints on entanglement entropies, which are implied by the Ryu-Takayanagi proposal. (Such constraints are collectively known as the holographic entropy … Read More
Wayne Weng (Stanford) “Replica manifolds, pole skipping, and the butterfly effect”
Abstract: Black holes are strongly chaotic quantum systems: small perturbations to its state grow exponentially in time. In holographic theories, this can be quantified by the butterfly velocity, defined using out-of-time-order correlators (OTOCs) or entanglement wedge reconstruction, which can in principle be different. There are many explicit calculations showing that the two velocities are in fact equal, including in theories with higher curvature corrections, … Read More
Beatrix Muhlmann (IAS) “dS^4 Metamorphosis”
Abstract: I will discuss the Euclidean path integral of minimal higher spin theory on the four-sphere and argue for a gluing formula in which the four-sphere is obtained by joining two hemispheres along an $S^3$ boundary. The resulting boundary theory is the $Sp(N)$-invariant sector of $N$ anticommuting, conformally coupled scalars, with conformal higher spin gauge fields mediating the gluing. This … Read More
Ronak Soni (Chennai Mathematical Institute) “Fixed-Area States, OPE Blocks and Hamiltonian Gauge Symmetry”
Abstract: In a particular code subspace for entangled states of many 2d holographic (B)CFTs, we propose a holographic bulk-boundary map. The proposal is stated in a fixed-area basis, and the essential idea is that each fixed area corresponds to a fixed primary. In particular, fixed-area states obtained from projections of path integral states are dual to smeared OPE blocks. We … Read More
Marija Tomasevic (CERN) “Dressing up naked singularities”
Abstract: Small naked singularities—those not shielded by a macroscopic event horizon—are ubiquitous in classical General Relativity. Their existence constitutes apparent violations of the weak cosmic censorship conjecture, which asserts that physically reasonable solutions should appear regular to asymptotic observers. In this talk, we will show how the inclusion of stringy and quantum effects resolves these pathologies by uplifting naked singularities into fully … Read More
Jacqueline Caminiti (Perimeter Institute) “From Inner Horizons to Quantum Information in the Bulk Point Limit”
Abstract: In 2017, a proposal was made for defining RT surfaces in asymptotically flat spacetimes, with the goal of computing the entanglement entropy in a putative dual theory. To avoid confusion with the usual RT prescription, the resulting surfaces are called swing surfaces. We take advantage of the flat limit of AdS/CFT to argue that swing surfaces do not compute … Read More
Masamichi Miyaji (Riken) “Perturbative Hilbert space of JT closed universe”
We consider gravitational path-integral of JT gravity of closed universe in AdS and dS spacetimes. In the absence of topology change, we calculate the amplitude and identify the perturbative Hilbert space. We find the Hilbert space is given by the co-invariant Hilbert space, an extended Hilbert space of boundary conditions divided by constraints, which is infinite dimensional. We also propose … Read More