arXiv subjects

Kenya Tasuki

Publications and source records attributed to Kenya Tasuki.

6 recordsLinked to original sources

arXiv2026

Strong-to-Weak Spontaneous Symmetry Breaking from Wormholes in Holography

We study strong-to-weak spontaneous symmetry breaking (SWSSB) at finite temperature and its implications in holography. SWSSB is a novel critical phenomenon that arises only in mixed states. We demonstrate SWSSB with the BTZ black hole and show that, in the bulk, it is realized through wormhole geometries connecting the two copies in the thermofield-double construction. We point out that SWSSB can be recast as an emergence of global symmetries under ensemble averaging. We further examine the interplay between SWSSB and the swampland program, and propose a new swampland conjecture for quantum-gravity theories involving ensemble averages.

hep-th↗

arXiv2026

Saddle Incompatibility Generates Genuine Multientropy in Heavy Local Quenches

We study the time evolution of tripartite genuine multientropy in heavy local quenches via AdS${}_3$/CFT${}_2$. Its linear response around the vacuum cancels pointwise for arbitrary adjacent intervals. At finite backreaction, the vacuum-subtracted genuine multientropy arises only from an incompatibility gap between the triplet of windings selected by the trivalent geodesic network and the windings selected independently by the bipartite geodesics. The heavy-light vacuum-block calculation reproduces the same formula from the boundary perspective. The time dependence is kinematically fixed and is independent of the heavy operator dimension. These results show that the genuine multipartite entanglement is controlled by global saddle transition rather than by local energy response or quasiparticle propagation.

hep-th↗

arXiv2025

Multi-entropy and the Dihedral Measures at Quantum Critical Points

The multi-entropy and dihedral measures are a class of tractable measures for multi-partite entanglement, which are labeled by the Rényi index (or replica number) $n$ as in the Rényi entanglement entropy. The purpose of this article is to demonstrate that these quantities are new useful probes of quantum critical points by examining concrete examples. In particular, we compute the multi-entropy and dihedral measures in the $1+1$ dimensional massless free scalar field theory on a lattice and in the transverse-field Ising model. For $n=2$, we find that the numerical results in both lattice theories quantitatively agree with those from conformal field theoretic calculations. For $n=3$ and $n=4$, we provide new predictions of these measures for the massless scalar field theory.

hep-th↗

arXiv2024

The $g$-theorem from Strong Subadditivity

We show that strong subadditivity provides a simple derivation of the $g$-theorem for the boundary renormalization group flow in two-dimensional conformal field theories. We work out its holographic interpretation and also give a derivation of the $g$-theorem for the case of an interface in two-dimensional conformal field theories. We also geometrically confirm strong subadditivity for holographic duals of conformal field theories on manifolds with boundaries.

hep-th↗

arXiv2023

Entanglement Phase Transition in Holographic Pseudo Entropy

In this paper, we present holographic descriptions of entanglement phase transition using AdS/BCFT. First, we analytically calculate the holographic pseudo entropy in the AdS/BCFT model with a brane localized scalar field and show the entanglement phase transition behavior where the time evolution of entropy changes from the linear growth to the trivial one via a critical logarithmic evolution. In this model, the imaginary valued scalar field localized on the brane controls the phase transition, which is analogous to the amount of projections in the measurement induced phase transition. Next, we study the AdS/BCFT model with a brane localized gauge field, where the phase transition looks different in that there is no logarithmically evolving critical point. Finally, we discuss a bulk analog of the above model by considering a double Wick rotation of the Janus solution. We compute the holographic pseudo entropy in this model and show that the entropy grows logarithmically.

hep-th↗

arXiv2023

Pseudo entropy under joining local quenches

We compute the pseudo entropy in two-dimensional holographic and free Dirac fermion CFTs for excited states under joining local quenches. Our analysis reveals two of its characteristic properties that are missing in the conventional entanglement entropy. One is that, under time evolution, the pseudo entropy exhibits a dip behavior as the excitations propagate from the joined point to the boundaries of the subsystem. The other is that the excess of pseudo entropy over entanglement entropy can be positive in holographic CFTs, whereas it is always non-positive in free Dirac fermion CFTs. We argue that the entropy excess can serve as a measure of multi-partite entanglement. Its positivity implies that the vacuum state in holographic CFTs possesses multi-partite entanglement, in contrast to free Dirac fermion CFTs.

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