280 citations · 1.5k across the 41 of their papers we have counts for
41 papers
Emergent Closed Universes in Symmetric Orbifold CFTs
Akihiro Miyata, Keigo Horikoshi, Hiromasa Tajima +1
We identify closed universe sectors in large symmetric orbifold CFTs with holographic duals. Starting from tensor product states built out of a finite dimensional low energy su…
Physical Predictions in Closed Quantum Gravity
Yasunori Nomura, Tomonori Ugajin
Recent developments in gravitational path integrals indicate that the nonperturbative physical Hilbert space of a closed universe is one-dimensional within each superselection sect…
Black Hole Interior and Quantum Error Correction with Dynamical Gravity
Akihiro Miyata, Tomonori Ugajin
According to the island formula, information in the code subspace defined in the black hole interior is embedded in the Hawking radiation after the Page time. At first sight, this…
Nonperturbative Quantum Gravity in a Closed Lorentzian Universe
Yasunori Nomura, Tomonori Ugajin
We study how meaningful physical predictions can arise in nonperturbative quantum gravity in a closed Lorentzian universe. In such settings, recent developments suggest that the qu…
Double Holography of Entangled Universes
Robert C. Myers, Shan-Ming Ruan, Tomonori Ugajin
We employ double holography to examine a system of two entangled gravitating universes that live on two codimension-one branes in an asymptotically AdS spacetime with two disjo…
The Petz (lite) recovery map for scrambling channel
Yasuaki Nakayama, Akihiro Miyata, Tomonori Ugajin
We study properties of the Petz recovery map in chaotic systems, such as the Hayden-Preskill setup for evaporating black holes and the SYK model. Since these systems exhibit the ph…
de Sitter space is sometimes not empty
Vijay Balasubramanian, Yasunori Nomura, Tomonori Ugajin
Multiple lines of evidence suggest that the Hilbert space of an isolated de Sitter universe is one dimensional but can appear larger when probed by a gravitating observer. To test…
Holographic Local Operator Quenches in BCFTs
Taishi Kawamoto, Takato Mori, Yu-ki Suzuki +2
We present a gravity dual of local operator quench in a two-dimensional CFT with conformal boundaries. This is given by a massive excitation in a three-dimensional AdS space with t…
Factorizing Wormholes in a Partially Disorder-Averaged SYK Model
Kanato Goto, Kenta Suzuki, Tomonori Ugajin
In this paper, we introduce a "partially disorder-averaged" SYK model. This model has a real parameter that smoothly interpolates between the ordinary totally disorder-averaged SYK…
Entanglement between two evaporating black holes
Akihiro Miyata, Tomonori Ugajin
We study a thermo-field double type entangle state on two disjoint gravitating universes, say A and B, with an eternal black hole on each. As was shown previously, its entanglement…
A comment on a fine-grained description of evaporating black holes with baby universes
Norihiro Iizuka, Akihiro Miyata, Tomonori Ugajin
We study a partially fine-grained description of an evaporating black hole by introducing an open baby universe with a boundary. Since the Page's calculation of the entropy of Hawk…
Product of Random States and Spatial (Half-)Wormholes
Kanato Goto, Yuya Kusuki, Kotaro Tamaoka +1
We study how coarse-graining procedure of an underlying UV-complete quantum gravity gives rise to a connected geometry. It has been shown, quantum entanglement plays a key role in…
Entanglement between two gravitating universes
Vijay Balasubramanian, Arjun Kar, Tomonori Ugajin
We study two disjoint universes in an entangled pure state. When only one universe contains gravity, the path integral for the Rényi entropy includes a wormhole bet…
Evaporation of black holes in flat space entangled with an auxiliary universe
Akihiro Miyata, Tomonori Ugajin
We study a thermofield double type entangled state on two disjoint universes and , where one of the universes is asymptotically flat containing a black hole. As we increase…
Spectrum of End of the World Branes in Holographic BCFTs
Masamichi Miyaji, Tadashi Takayanagi, Tomonori Ugajin
We study overlaps between two regularized boundary states in conformal field theories. Regularized boundary states are dual to end of the world branes in an AdS black hole via the…
Wormholes and holographic decoherence
Takanori Anegawa, Norihiro Iizuka, Kotaro Tamaoka +1
We study a class of decoherence process which admits a 3 dimensional holographic bulk. Starting from a thermo-field double dual to a wormhole, we prepare another thermo-field doubl…
Holographic Rényi relative divergence in JT gravity
Tomonori Ugajin
We holographically compute the Rényi relative divergence between two density matrices prepared by path integrals with constant background f…
Islands in de Sitter space
Vijay Balasubramanian, Arjun Kar, Tomonori Ugajin
We consider black holes in 2d de Sitter JT gravity coupled to a CFT, and entangled with matter in a disjoint non-gravitating universe. Tracing out the entangling matter leaves the…
Entanglement between two disjoint universes
Vijay Balasubramanian, Arjun Kar, Tomonori Ugajin
We use the replica method to compute the entanglement entropy of a universe without gravity entangled in a thermofield-double-like state with a disjoint gravitating universe. Inclu…
Spin structures and baby universes
Vijay Balasubramanian, Arjun Kar, Simon F. Ross +1
We extend a 2d topological model of the gravitational path integral to include sums over spin structure, corresponding to Neveu-Schwarz (NS) or Ramond (R) boundary conditions for f…
Geometric secret sharing in a model of Hawking radiation
Vijay Balasubramanian, Arjun Kar, Onkar Parrikar +2
We consider a black hole in three dimensional AdS space entangled with an auxiliary radiation system. We model the microstates of the black hole in terms of a field theory living o…
Perturbative expansions of Rényi relative divergences and holography
Tomonori Ugajin
In this paper, we develop a novel way to perturbatively calculate Rényi relative divergences and related quantities without using replica trick a…
Towards an Entanglement Measure for Mixed States in CFTs Based on Relative Entropy
Tadashi Takayanagi, Tomonori Ugajin, Koji Umemoto
Relative entropy of entanglement (REE) is an entanglement measure of bipartite mixed states, defined by the minimum of the relative entropy between a given mix…
Chaos and relative entropy
Yuya O. Nakagawa, Gábor Sárosi, Tomonori Ugajin
One characterization of a chaotic system is the quick delocalization of quantum information (fast scrambling). One therefore expects that in such a system a state quickly becomes l…