1,755 research outputs found
Two Black Hole Holography, Lensing and Intensity
We numerically verify the analysis of the "expanding horizon" theory of
Susskind in relation to the 't Hooft holographic conjecture. By using a
numerical simulation to work out the image formed by two black holes upon a
screen very far away, it is seen that it is impossible for a horizon to hide
behind another. We also compute the intensity distribution of such an
arrangement.Comment: 10 page
Computing the spectrum of black hole radiation in the presence of high frequency dispersion: an analytical approach
We present a method for computing the spectrum of black hole radiation of a
scalar field satisfying a wave equation with high frequency dispersion. The
method involves a combination of Laplace transform and WKB techniques for
finding approximate solutions to ordinary differential equations. The modified
wave equation is obtained by adding a higher order derivative term suppressed
by powers of a fundamental momentum scale to the ordinary wave equation.
Depending on the sign of this new term, high frequency modes propagate either
superluminally or subluminally. We show that the resulting spectrum of created
particles is thermal at the Hawking temperature, and further that the out-state
is a thermal state at the Hawking temperature, to leading order in , for
either modification.Comment: 26 pages, plain latex, 6 figures included using psfi
Fermionic microstates within Painlev\'e-Gullstrand black hole
We consider the quantum vacuum of fermionic field in the presence of a
black-hole background as a possible candidate for the stabilized black hole.
The stable vacuum state (as well as thermal equilibrium states with arbitrary
temperature) can exist if we use the Painlev\'e-Gullstrand description of the
black hole, and the superluminal dispersion of the particle spectrum at high
energy, which is introduced in the free-falling frame. Such choice is inspired
by the analogy between the quantum vacuum and the ground state of quantum
liquid, in which the event horizon for the low-energy fermionic quasiparticles
also can arise. The quantum vacuum is characterized by the Fermi surface, which
appears behind the event horizon. We do not consider the back reaction, and
thus there is no guarantee that the stable black hole exists. But if it does
exist, the Fermi surface behind the horizon would be the necessary attribute of
its vacuum state. We also consider exact discrete spectrum of fermions inside
the horizon which allows us to discuss the problem of fermion zero modes.Comment: LaTeX, 20 pages, 2 figure
Diffusion constant of supercharge density in N=4 SYM at finite chemical potential
We compute holographically the diffusion constant of supercharges in N=4 SYM
at finite chemical potential for the R-charge, by solving the equations of
motion for the transverse mode of the gravitino in the STU black hole in 5
dimensions. We consider the case of one charge and three charges, and we
present analytical solutions for small values of the charges and numerical
solutions for arbitrary values. We compare our results with other known results
in 4 dimensions.Comment: 20 pages, 4 figures; v2: typos correcte
Fermion zero modes in Painlev\'e-Gullstrand black hole
Painleve-Gullstrand metric of the black hole allows to discuss the fermion
zero modes inside the hole. The statistical mechanics of the fermionic
microstates can be responsible for the black hole thermodynamics. Fermion zero
modes also lead to quantization of the horizon area.Comment: LaTeX, 13 pages, no figures, version submitted to JETP Leter
Large-scale non-locality in "doubly special relativity" with an energy-dependent speed of light
There are two major alternatives for violating the (usual) Lorentz invariance
at large (Planckian) energies or momenta - either not all inertial frames (in
the Planck regime) are equivalent (e.g., there is an effectively preferred
frame) or the transformations from one frame to another are (non-linearly)
deformed (``doubly special relativity''). We demonstrate that the natural (and
reasonable) assumption of an energy-dependent speed of light in the latter
method goes along with violations of locality/separability (and even
translational invariance) on macroscopic scales.
PACS: 03.30.+p, 11.30.Cp, 04.60.-m, 04.50.+h.Comment: 5 pages RevTeX, several modification
Holographic three-point functions of giant gravitons
Working within the AdS/CFT correspondence we calculate the three-point
function of two giant gravitons and one pointlike graviton using methods of
semiclassical string theory and considering both the case where the giant
gravitons wrap an S^3 in S^5 and the case where the giant gravitons wrap an S^3
in AdS_5. We likewise calculate the correlation function in N=4 SYM using two
Schur polynomials and a single trace chiral primary. We find that the gauge and
string theory results have structural similarities but do not match perfectly,
and interpret this in terms of the Schur polynomials' inability to interpolate
between dual giant and pointlike gravitons.Comment: 21 page
Quantum geometry and gravitational entropy
Most quantum states have wavefunctions that are widely spread over the
accessible Hilbert space and hence do not have a good description in terms of a
single classical geometry. In order to understand when geometric descriptions
are possible, we exploit the AdS/CFT correspondence in the half-BPS sector of
asymptotically AdS_5 x S^5 universes. In this sector we devise a
"coarse-grained metric operator" whose eigenstates are well described by a
single spacetime topology and geometry. We show that such half-BPS universes
have a non-vanishing entropy if and only if the metric is singular, and that
the entropy arises from coarse-graining the geometry. Finally, we use our
entropy formula to find the most entropic spacetimes with fixed asymptotic
moments beyond the global charges.Comment: 29 pages, 2 figures; references adde
Lattice deformation at the sub-micron scale: X-ray nanobeam measurements of elastic strain in electron shuttling devices
The lattice strain induced by metallic electrodes can impair the
functionality of advanced quantum devices operating with electron or hole
spins. Here we investigate the deformation induced by CMOS-manufactured
titanium nitride electrodes on the lattice of a buried, 10 nm-thick Si/SiGe
Quantum Well by means of nanobeam Scanning X-ray Diffraction Microscopy. We
were able to measure TiN electrode-induced local modulations of the strain
tensor components in the range of with ~60 nm lateral
resolution. We have evaluated that these strain fluctuations are reflected into
local modulations of the potential of the conduction band minimum larger than 2
meV, which is close to the orbital energy of an electrostatic quantum dot. We
observe that the sign of the strain modulations at a given depth of the quantum
well layer depends on the lateral dimensions of the electrodes. Since our work
explores the impact of device geometry on the strain-induced energy landscape,
it enables further optimization of the design of scaled CMOS-processed quantum
devices.Comment: 16 pages, 6 figure
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