Null wave front and Ryu–Takayanagi surface

Jun Tsujimura, Yasusada Nambu

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The Ryu–Takayanagi formula provides the entanglement entropy of quantum field theory as an area of the minimal surface (Ryu–Takayanagi surface) in a corresponding gravity theory. There are some attempts to understand the formula as a flow rather than as a surface. In this paper, we consider null rays emitted from the AdS boundary and construct a flow representing the causal holographic information. We present a sufficient and necessary condition that the causal information surface coincides with Ryu–Takayanagi surface. In particular, we show that, in spherical symmetric static spacetimes with a negative cosmological constant, wave fronts of null geodesics from a point on the AdS boundary become extremal surfaces and therefore they can be regarded as the Ryu–Takayanagi surfaces. In addition, from the viewpoint of flow, we propose a wave optical formula to calculate the causal holographic information.

Original languageEnglish
Article number1297
Pages (from-to)1-14
Number of pages14
Issue number11
Publication statusPublished - Nov 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


Dive into the research topics of 'Null wave front and Ryu–Takayanagi surface'. Together they form a unique fingerprint.

Cite this