Entanglement entropy of a Maxwell field on the sphere

Abstract We investigate perturbatively tractable deformations of topological defects in two-dimensional conformal field theories. We perturbatively compute the change in the g-factor, the reflectivity, and the entanglement entropy of the conformal defect at the end of these short RG flows. We also give instances of such flows in the diagonal Virasoro and Super-Virasoro Minimal Models.

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Entanglement entropy in low-energy field theories at a finite chemical potential

Physical Review Research ◽

10.1103/physrevresearch.2.033016 ◽

2020 ◽

Vol 2 (3) ◽

Author(s):

Ivan Morera ◽

Irénée Frérot ◽

Artur Polls ◽

Bruno Juliá-Díaz

Keyword(s):

Chemical Potential ◽

Entanglement Entropy ◽

Low Energy ◽

Field Theories ◽

Energy Field

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Quantum information probes of charge fractionalization in large-N gauge theories

Journal of High Energy Physics ◽

10.1007/jhep05(2021)149 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Brandon S. DiNunno ◽

Niko Jokela ◽

Juan F. Pedraza ◽

Arttu Pönni

Keyword(s):

Degrees Of Freedom ◽

Gauge Theories ◽

Entanglement Entropy ◽

Coarse Grained ◽

Strongly Coupled ◽

Information Theoretic ◽

Large N ◽

Wide Range ◽

Charge Fractionalization ◽

Electric Flux

Abstract We study in detail various information theoretic quantities with the intent of distinguishing between different charged sectors in fractionalized states of large-N gauge theories. For concreteness, we focus on a simple holographic (2 + 1)-dimensional strongly coupled electron fluid whose charged states organize themselves into fractionalized and coherent patterns at sufficiently low temperatures. However, we expect that our results are quite generic and applicable to a wide range of systems, including non-holographic. The probes we consider include the entanglement entropy, mutual information, entanglement of purification and the butterfly velocity. The latter turns out to be particularly useful, given the universal connection between momentum and charge diffusion in the vicinity of a black hole horizon. The RT surfaces used to compute the above quantities, though, are largely insensitive to the electric flux in the bulk. To address this deficiency, we propose a generalized entanglement functional that is motivated through the Iyer-Wald formalism, applied to a gravity theory coupled to a U(1) gauge field. We argue that this functional gives rise to a coarse grained measure of entanglement in the boundary theory which is obtained by tracing over (part) of the fractionalized and cohesive charge degrees of freedom. Based on the above, we construct a candidate for an entropic c-function that accounts for the existence of bulk charges. We explore some of its general properties and their significance, and discuss how it can be used to efficiently account for charged degrees of freedom across different energy scales.

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Islands and stretched horizon

Journal of High Energy Physics ◽

10.1007/jhep07(2021)051 ◽

2021 ◽

Vol 2021 (7) ◽

Author(s):

Yoshinori Matsuo

Keyword(s):

Black Holes ◽

Black Hole ◽

Hawking Radiation ◽

Entanglement Entropy ◽

Total System ◽

Island Rule ◽

Asymptotically Flat ◽

Flat Spacetime ◽

Ads Spacetime ◽

Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

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