28 research outputs found
Entanglement Entropy of Disjoint Regions in Excited States : An Operator Method
We develop the computational method of entanglement entropy based on the idea
that is written as the expectation value of the local
operator, where is a density matrix of the subsystem .
We apply it to consider the mutual Renyi information
of disjoint compact
spatial regions and in the locally excited states defined by acting the
local operators at and on the vacuum of a -dimensional field
theory, in the limit when the separation between and is much
greater than their sizes . For the general QFT which has a mass gap,
we compute explicitly and find that this result is interpreted
in terms of an entangled state in quantum mechanics. For a free massless scalar
field, we show that for some classes of excited states,
where or 2 which is determined by the property of the local
operators under the transformation and for
the vacuum state. We give a method to compute systematically.Comment: 22 pages; v3, typos corrected, published versio
Volume Law for the Entanglement Entropy in Non-local QFTs
In this paper, we present a simple class of non-local field theories whose
ground state entanglement entropy follows a volume law as long as the size of
subsystem is smaller than a certain scale. We will confirm this volume law both
from numerical calculations and from analytical estimation. This behavior fits
nicely with holographic results for spacetimes whose curvatures are much
smaller than AdS spaces such as those in the flat spacetime.Comment: 18 pages, 3 figures; v2, added reference
Entanglement between Two Interacting CFTs and Generalized Holographic Entanglement Entropy
In this paper we discuss behaviors of entanglement entropy between two
interacting CFTs and its holographic interpretation using the AdS/CFT
correspondence. We explicitly perform analytical calculations of entanglement
entropy between two free scalar field theories which are interacting with each
other in both static and time-dependent ways. We also conjecture a holographic
calculation of entanglement entropy between two interacting
super Yang-Mills theories by introducing a minimal surface in the S
direction, instead of the AdS direction. This offers a possible
generalization of holographic entanglement entropy.Comment: 37 pages, 7 figures, v2: typos corrected, references added, v3: a
ref. + a clarification note about minimal surfaces adde
EPR Pairs, Local Projections and Quantum Teleportation in Holography
In this paper we analyze three quantum operations in two dimensional
conformal field theories (CFTs): local projection measurements, creations of
partial entanglement between two CFTs, and swapping of subsystems between two
CFTs. We also give their holographic duals and study time evolutions of
entanglement entropy. By combining these operations, we present an analogue of
quantum teleportation between two CFTs and give its holographic realization. We
introduce a new quantity to probe tripartite entanglement by using local
projection measurement.Comment: 61 pages, 24 figures. v2: comments and refs added. v3: minor
correction
Gravity Dual of Quantum Information Metric
We study a quantum information metric (or fidelity susceptibility) in
conformal field theories with respect to a small perturbation by a primary
operator. We argue that its gravity dual is approximately given by a volume of
maximal time slice in an AdS spacetime when the perturbation is exactly
marginal. We confirm our claim in several examples.Comment: 5 pages plus appendices, Revtex, 2 figure
cMERA as Surface/State Correspondence in AdS/CFT
We present how the surface/state correspondence, conjectured in
arXiv:1503.03542, works in the setup of AdS3/CFT2 by generalizing the
formulation of cMERA. The boundary states in conformal field theories play a
crucial role in our formulation and the bulk diffeomorphism is naturally taken
into account. We give an identification of bulk local operators which
reproduces correct scalar field solutions on AdS3 and bulk scalar propagators.
We also calculate the information metric for a locally excited state and show
that it is given by that of 2d hyperbolic manifold, which is argued to describe
the time slice of AdS3.Comment: 8 pages, Revtex, 3 figures; comments added, a derivation of bulk
propagators is adde