11 research outputs found
Limitations to Realize Quantum Zeno Effect in Beam Splitter Array -- a Monte Carlo Wavefunction Analysis
Effects of non-ideal optical components in realizing quantum Zeno effect in
an all-optical setup are analyzed. Beam splitters are the important components
in this experimental configuration. Nonuniform transmission coefficient, photon
absorption and thermal noise are considered. Numerical simulation of the
experiment is performed using the Monte Carlo wavefunction method. It is argued
that there is an optimal number of beam splitters to be used for maximizing the
expected output in the experiment.Comment: To be published in the Journal of the Physical Society of Japa
Nonlinear Langevin dynamics via holography
In this work, we consider non-linear corrections to the Langevin effective
theory of a heavy quark moving through a strongly coupled CFT plasma. In
AdS/CFT, this system can be identified with that of a string stretched between
the boundary and the horizon of an asymptotically AdS black-brane solution. We
compute the Feynman-Vernon influence phase for the heavy quark by evaluating
the Nambu-Goto action on a doubled string configuration. This configuration is
the linearised solution of the string motion in the doubled black-brane
geometry which has been proposed as the holographic dual of a thermal
Schwinger-Keldysh contour of the CFT. Our expression for the influence phase
passes non-trivial consistency conditions arising from the underlying unitarity
and thermality of the bath. The local effective theory obeys the recently
proposed non-linear fluctuation dissipation theorem relating the
non-Gaussianity of thermal noise to the thermal jitter in the damping constant.
This furnishes a non-trivial check for the validity of these relations derived
in the weak coupling regime.Comment: 31 pages + appendices. Minor revision added on integrating out ghost
fields in the path integra
Effective field theory of stochastic diffusion from gravity
Planar black holes in AdS have long-lived quasinormal modes which capture the
physics of charge and momentum diffusion in the dual field theory. How should
we characterize the effective dynamics of a probe system coupled to the
conserved currents of the dual field theory? Specifically, how would such a
probe record the long-lived memory of the black hole and its Hawking
fluctuations? We address this question by exhibiting a universal gauge
invariant framework which captures the physics of stochastic diffusion in
holography: a designer scalar with a gravitational coupling governed by a
single parameter, the Markovianity index. We argue that the physics of gauge
and gravitational perturbations of a planar Schwarzschild-AdS black hole can be
efficiently captured by such designer scalars. We demonstrate that this
framework allows one to decouple, at the quadratic order, the long-lived
quasinormal and Hawking modes from the short-lived ones. It furthermore
provides a template for analyzing fluctuating open quantum field theories with
memory. In particular, we use this set-up to analyze the diffusive Hawking
photons and gravitons about a planar Schwarzschild-AdS black hole and derive
the quadratic effective action that governs fluctuating hydrodynamics of the
dual CFT. Along the way we also derive results relevant for probes of
hyperscaling violating backgrounds at finite temperature.Comment: 57 pages + appendices. v2: typos fixed. v3: minor changes, published
versio
Holography of information in massive gravity using Dirac brackets
Abstract The principle of holography of information states that in massless gravity, it is possible to extract bulk information using asymptotic boundary operators. In our work, we study this principle in a linearized setting about empty flat space and formulate it using Dirac brackets between boundary Hamiltonian and bulk operators. We then address whether the storage of bulk information in flat space linearized massive gravity resembles that of massless gravity. For linearized massless gravity, using Dirac brackets, we recover the necessary criteria for the holography of information. In contrast, we show that the Dirac bracket of the relevant boundary observable with bulk operators vanishes for massive gravity. We use this important distinction to outline the canonical Hilbert space. This leads to split states, and consequently, one cannot use asymptotic boundary observables to extract bulk information in massive gravity. We also argue the split property directly without an explicit reference to the Hilbert space. The result reflects that we can construct local bulk operators in massive gravity about the vacuum, which are obscured from boundary observables due to the lack of diffeomorphism invariance. Our analysis sheds some light on evaporating black holes in the context of the islands proposal
The timbre of Hawking gravitons: an effective description of energy transport from holography
Planar black holes in AdS, which are holographically dual to compressible
relativistic fluids, have a long-lived phonon mode that captures the physics of
attenuated sound propagation and transports energy in the plasma. We describe
the open effective field theory of this fluctuating phonon degree of freedom.
The dynamics of the phonon is encoded in a single scalar field whose
gravitational coupling has non-trivial spatial momentum dependence. This
description fits neatly into the paradigm of classifying gravitational modes by
their Markovianity index, depending on whether they are long-lived. The sound
scalar is a non-Markovian field with index (3-d) for a d-dimensional fluid. We
reproduce (and extend) the dispersion relation of the holographic sound mode to
quartic order in derivatives, constructing in the process the effective field
theory governing its attenuated dynamics and associated stochastic
fluctuations. We also remark on the presence of additional spatially
homogeneous zero modes in the gravitational problem, which remain disconnected
from the phonon Goldstone mode.Comment: 29 pages + appendices. v2: minor improvements and fixed typo