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31
A Covariant Holographic Entanglement Entropy Proposal
, 2008
"... With an aim towards understanding the timedependence of entanglement entropy in generic quantum field theories, we propose a covariant generalization of the holographic entanglement entropy proposal of hepth/0603001. Apart from providing several examples of possible covariant generalizations, we s ..."
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Cited by 140 (20 self)
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With an aim towards understanding the timedependence of entanglement entropy in generic quantum field theories, we propose a covariant generalization of the holographic entanglement entropy proposal of hepth/0603001. Apart from providing several examples of possible covariant generalizations, we study a particular construction based on lightsheets, motivated in similar spirit to the covariant entropy bound underlying the holographic principle. In particular, we argue that the entanglement entropy associated with a specified region on the boundary in the context of the AdS/CFT correspondence is given by the area of a codimension two bulk surface with vanishing expansions of null geodesics. We demonstrate our construction with several examples to illustrate its reduction to the holographic entanglement entropy proposal in static spacetimes. We further show how this proposal may be used to understand the time evolution of entanglement entropy in a time varying QFT state dual to a collapsing black hole background. Finally, we use our proposal to argue that the Euclidean wormhole geometries with multiple boundaries should be regarded as states in a noninteracting but entangled set of QFTs, one associated to each boundary.
Some uniqueness results for dynamical horizons
 Adv. Theor. Math. Phys
, 2005
"... We first show that the intrinsic, geometrical structure of a dynamical horizon is unique. A number of physically interesting constraints are then established on the location of trapped and marginally trapped surfaces in the vicinity of any dynamical horizon. These restrictions are used to prove seve ..."
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Cited by 37 (3 self)
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We first show that the intrinsic, geometrical structure of a dynamical horizon is unique. A number of physically interesting constraints are then established on the location of trapped and marginally trapped surfaces in the vicinity of any dynamical horizon. These restrictions are used to prove several uniqueness theorems for dynamical horizons. Ramifications of some of these results to numerical simulations of black hole spacetimes are discussed. Finally several expectations on the interplay between isometries and dynamical horizons are shown to be borne out. 1
Loop quantum gravity: An outside view
, 2005
"... We review aspects of loop quantum gravity in a pedagogical manner, with the aim of enabling a precise but critical assessment of its achievements so far. We emphasise that the offshell (‘strong’) closure of the constraint algebra is a crucial test of quantum spacetime covariance, and thereby of th ..."
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Cited by 24 (0 self)
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We review aspects of loop quantum gravity in a pedagogical manner, with the aim of enabling a precise but critical assessment of its achievements so far. We emphasise that the offshell (‘strong’) closure of the constraint algebra is a crucial test of quantum spacetime covariance, and thereby of the consistency, of the theory. Special attention is paid to the appearance of a large number of ambiguities, in particular in the formulation of the Hamiltonian constraint. Developing suitable approximation methods to establish a connection with classical gravity on the one hand, and with the physics of elementary particles on the other, remains a major challenge. Contents 1 Key questions 2
Spherically Symmetric Quantum Geometry: Hamiltonian Constraint
"... Variables adapted to the quantum dynamics of spherically symmetric models are introduced, which further simplify the spherically symmetric volume operator and allow an explicit computation of all matrix elements of the Euclidean and Lorentzian Hamiltonian constraints. The construction fits completel ..."
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Cited by 12 (5 self)
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Variables adapted to the quantum dynamics of spherically symmetric models are introduced, which further simplify the spherically symmetric volume operator and allow an explicit computation of all matrix elements of the Euclidean and Lorentzian Hamiltonian constraints. The construction fits completely into the general scheme available in loop quantum gravity for the quantization of the full theory as well as symmetric models. This then presents a further consistency check of the whole scheme in inhomogeneous situations, lending further credence to the physical results obtained so far mainly in homogeneous models. New applications in particular of the spherically symmetric model in the context of black hole physics are discussed. 1
The Fluid/Gravity Correspondence: a new perspective on the Membrane Paradigm
, 2011
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AdS/CFT Correspondence with Heat Conduction,” Phys
 Lett. B
, 2007
"... We study perturbations of the gravity dual to a perfect fluid model recently found by Janik and Perschanski [hepth/0512162]. We solve the Einstein equations in the bulk AdS space for a metric ansatz which includes offdiagonal terms. Through holographic renormalization, we show that these terms giv ..."
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Cited by 4 (0 self)
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We study perturbations of the gravity dual to a perfect fluid model recently found by Janik and Perschanski [hepth/0512162]. We solve the Einstein equations in the bulk AdS space for a metric ansatz which includes offdiagonal terms. Through holographic renormalization, we show that these terms give rise to heat conduction in the corresponding CFT on the boundary.