31 research outputs found
A theory of reparameterizations for AdS gravity
We rewrite the Chern-Simons description of pure gravity on global AdS and
on Euclidean BTZ black holes as a quantum field theory on the AdS boundary. The
resulting theory is (two copies of) the path integral quantization of a certain
coadjoint orbit of the Virasoro group, and it should be regarded as the quantum
field theory of the boundary gravitons. This theory respects all of the
conformal field theory axioms except one: it is not modular invariant. The
coupling constant is with the central charge, and perturbation theory
in encodes loop contributions in the gravity dual. The QFT is a theory of
reparametrizations analogous to the Schwarzian description of nearly AdS
gravity, and has several features including: (i) it is ultraviolet-complete;
(ii) the torus partition function is the vacuum Virasoro character, which is
one-loop exact by a localization argument; (iii) it reduces to the Schwarzian
theory upon compactification; (iv) it provides a powerful new tool for
computing Virasoro blocks at large via a diagrammatic expansion. We use the
theory to compute several observables to one-loop order in the bulk, including
the "heavy-light" limit of the identity block. We also work out some
generalizations of this theory, including the boundary theory which describes
fluctuations around two-sided eternal black holes.Comment: 74 pages, 4 figures; v2: minor fixes; v3: various improvements and
typos fixed; added new material on PSL(2,R) currents, Euclidean black holes,
and a derivation of the boundary measure from the bul
Comments on the Necessity and Implications of State-Dependence in the Black Hole Interior
We revisit the "state-dependence" of the map that we proposed recently
between bulk operators in the interior of a large AdS black hole and operators
in the boundary CFT. By refining recent versions of the information paradox, we
show that this feature is necessary for the CFT to successfully describe local
physics behind the horizon --- not only for single-sided black holes but even
in the eternal black hole. We show that state-dependence is invisible to an
infalling observer who cannot differentiate these operators from those of
ordinary quantum effective field theory. Therefore the infalling observer does
not observe any violations of quantum mechanics. We successfully resolve a
large class of potential ambiguities in our construction. We analyze states
where the CFT is entangled with another system and show that the ER=EPR
conjecture emerges from our construction in a natural and precise form. We
comment on the possible semi-classical origins of state-dependence.Comment: 136 pages, 16 figure
Holographic Entanglement Entropy
We review the developments in the past decade on holographic entanglement
entropy, a subject that has garnered much attention owing to its potential to
teach us about the emergence of spacetime in holography. We provide an
introduction to the concept of entanglement entropy in quantum field theories,
review the holographic proposals for computing the same, providing some
justification for where these proposals arise from in the first two parts. The
final part addresses recent developments linking entanglement and geometry. We
provide an overview of the various arguments and technical developments that
teach us how to use field theory entanglement to detect geometry. Our
discussion is by design eclectic; we have chosen to focus on developments that
appear to us most promising for further insights into the holographic map.
This is a draft of a few chapters of a book which will appear sometime in the
near future, to be published by Springer. The book in addition contains a
discussion of application of holographic ideas to computation of entanglement
entropy in strongly coupled field theories, and discussion of tensor networks
and holography, which we have chosen to exclude from the current manuscript.Comment: 154 pages. many figures. preliminary version of book chapters.
comments welcome. v2: typos fixed and references adde
Computer Science for Continuous Data:Survey, Vision, Theory, and Practice of a Computer Analysis System
Building on George Boole's work, Logic provides a rigorous foundation for the powerful tools in Computer Science that underlie nowadays ubiquitous processing of discrete data, such as strings or graphs. Concerning continuous data, already Alan Turing had applied "his" machines to formalize and study the processing of real numbers: an aspect of his oeuvre that we transform from theory to practice.The present essay surveys the state of the art and envisions the future of Computer Science for continuous data: natively, beyond brute-force discretization, based on and guided by and extending classical discrete Computer Science, as bridge between Pure and Applied Mathematics
Supergravity Solitons, their Superpartners and Fluid/Gravity Correspondence
The first part of this thesis aims to explore the effects caused by the presence of Grassmann numbers in the fluid/gravity correspondence. We extend the fluid/gravity correspondence by considering supergravity theories in the bulk and by computing the black hole superpartner. The resulting metric is a supergravity black hole solution with its associated charges and entropy dependent upon Grassmann numbers. Moreover by fluid/gravity techniques we find that also the fluid dynamics parameters, such as the temperature and the velocity, are in general affected by Grassmann numbers. In the second part of the work we analyze matter coupled supergravities in 4 and 5 dimensions. In particular we focus on the modification of the attractor mechanism due to the backreaction of the supersymmetry multiplet to the presence of fermionic zero modes
Entanglement dynamics and chaos in long-range quantum systems
Over the past twenty years, experimental and technological progresses have motivated a renewed attention to the study of non-equilibrium isolated many-body systems, leading to a relatively well-established paradigm in the case of local Hamiltonians.
In the present thesis, I have used quantum information theoretical tools to study out-of-equilibrium dynamics, with particular attention on long-range interacting many-body systems. I have explored the dynamics of bipartite and multipartite entanglement in connection to chaos and scrambling in various long-range (clean and disordered) models. The results contained in this thesis contribute to establishing semi-classical tools as powerful techniques for the description of the quantum information spreading in long-range systems.
I have further considered a different, yet connected question, concerning the multipartite entanglement structure of chaotic eigenstates and its generic evolution