75 research outputs found

### Relative entropy in higher spin holography

We examine relative entropy in the context of the higher-spin/CFT duality. We
consider 3$d$ bulk configurations in higher spin gravity which are dual to the
vacuum and a high temperature state of a CFT with $\mathcal{W}$-algebra
symmetries in presence of a chemical potential for a higher spin current. The
relative entropy between these states is then evaluated using the Wilson line
functional for holographic entanglement entropy. In the limit of small
entangling intervals, the relative entropy should vanish for a generic quantum
system. We confirm this behaviour by showing that the difference in the
expectation values of the modular Hamiltonian between the states matches with
the difference in the entanglement entropy in the short-distance regime.
Additionally, we compute the relative entropy of states corresponding to smooth
solutions in the $SL(2,\mathbb{Z})$ family with respect to the vacuum.Comment: 29 pages. Published version. All relative entropies are calculated
with respect to the vacuu

### Temperature dependent reversal of voltage modulated light emission and negative capacitance in AlGaInP based multi quantum well light emitting devices

We report a reversal in negative capacitance and voltage modulated light
emission from AlGaInP based multi-quantum well electroluminescent diodes under
temperature variation. Unlike monotonically increasing CW light emission with
decreasing temperature, modulated electroluminescence and negative capacitance
first increase to a maximum and then decrease while cooling down from room
temperature. Interdependence of such electronic and optical properties is
understood as a competition between defect participation in radiative
recombination and field assisted carrier escape from the quantum well region
during temperature variation. The temperature of maximum light emission must
coincide with the operating temperature of a device for better efficiency.Comment: 13 pages, 3 set of figure

### $T\bar{T}$ deformed partition functions

We demonstrate the presence of modular properties in partition functions of
$T\bar{T}$ deformed conformal field theories. These properties are verified
explicitly for the deformed free boson. The modular features facilitate a
derivation of the asymptotic density of states in these theories, which turns
out to interpolate between Cardy and Hagedorn behaviours. We also point out a
sub-sector of the spectrum that remains undeformed under the $T\bar{T}$ flow.
Finally, we comment on the deformation of the CFT vacuum character and its
implications for the holographic dual.Comment: Published versio

### Renyi entropies of free bosons on the torus and holography

We analytically evaluate the Renyi entropies for the two dimensional free
boson CFT. The CFT is considered to be compactified on a circle and at finite
temperature. The Renyi entropies S_n are evaluated for a single interval using
the two point function of bosonic twist fields on a torus. For the case of the
compact boson, the sum over the classical saddle points results in the
Riemann-Siegel theta function associated with the A_{n-1} lattice. We then
study the Renyi entropies in the decompactification regime. We show that in the
limit when the size of the interval becomes the size of the spatial circle, the
entanglement entropy reduces to the thermal entropy of free bosons on a circle.
We then set up a systematic high temperature expansion of the Renyi entropies
and evaluate the finite size corrections for free bosons. Finally we compare
these finite size corrections both for the free boson CFT and the free fermion
CFT with the one-loop corrections obtained from bulk three dimensional
handlebody spacetimes which have higher genus Riemann surfaces as its boundary.
One-loop corrections in these geometries are entirely determined by quantum
numbers of the excitations present in the bulk. This implies that the leading
finite size corrections contributions from one-loop determinants of the
Chern-Simons gauge field and the Dirac field in the dual geometry should
reproduce that of the free boson and the free fermion CFT respectively. By
evaluating these corrections both in the bulk and in the CFT explicitly we show
that this expectation is indeed true.Comment: Published version. 56 pages. 6 figures. Argument for the agreement of
the leading finite size corrections evaluated from CFT and gravity has been
adde

### Black holes in higher spin supergravity

We study black hole solutions in Chern-Simons higher spin supergravity based
on the superalgebra sl(3|2). These black hole solutions have a U(1) gauge field
and a spin 2 hair in addition to the spin 3 hair. These additional fields
correspond to the R-symmetry charges of the supergroup sl(3|2). Using the
relation between the bulk field equations and the Ward identities of a CFT with
N=2 super-W_3 symmetry, we identify the bulk charges and chemical potentials
with those of the boundary CFT. From these identifications we see that a
suitable set of variables to study this black hole is in terms of the charges
present in three decoupled bosonic sub-algebras of the N=2 super-W_3 algebra.
The entropy and the partition function of these R-charged black holes are then
evaluated in terms of the charges of the bulk theory as well as in terms of its
chemical potentials. We then compute the partition function in the dual CFT and
find exact agreement with the bulk partition function.Comment: 27 pages. Published versio

### ABS System of RAVO Street Sweeper for New Hydraulic Driveline Concepts

ABS System of RAVO Street Sweeper for New Hydraulic Driveline ConceptsABS System of RAVO Street Sweeper for New Hydraulic Driveline Concept

### Supersymmetry of classical solutions in Chern-Simons higher spin supergravity

We construct and study classical solutions in Chern-Simons supergravity based
on the superalgebra sl(N|N-1). The algebra for the N=3 case is written down
explicitly using the fact that it arises as the global part of the super
conformal W_3 superalgebra. For this case we construct new classical solutions
and study their supersymmetry. Using the algebra we write down the Killing
spinor equations and explicitly construct the Killing spinor for conical
defects and black holes in this theory. We show that for the general sl(N|N-1)
theory the condition for the periodicity of the Killing spinor can be written
in terms of the products of the odd roots of the super algebra and the
eigenvalues of the holonomy matrix of the background. Thus the supersymmetry of
a given background can be stated in terms of gauge invariant and well defined
physical observables of the Chern-Simons theory. We then show that for N\geq 4,
the sl(N|N-1) theory admits smooth supersymmetric conical defects.Comment: 40 pages, includes discussion of conical defects for N\geq 4, typos
corrected and presentation improve

### A two-component Bose Einstein condensate can 'bypass' the no-cloning theorem

No cloning theorem in quantum cryptography prevents an eavesdropper from
perfectly duplicating any arbitrary quantum state. Here we argue that an
experimental scheme for producing a two component quantum superposition of Bose
Einstein condensates can, in principle, generate N bosonic clones of a single
quantum state at large N thermodynamic limit and thus operationally bypass the
restrictions imposed by the above mentioned theorem. It is possible because the
quantum statistical nature of this cloning operation does not require the
unitary evolution of standard quantum mechanics. On the other hand, generation
of a two component Bose-Einstein condensate helps in generating the bosonic
clones with high fidelity. Such operationally executable perfect quantum
cloning machine will significantly impact existing understanding of quantum
cryptography and also that of relativity, in general, by allowing superluminal
signaling.Comment: 12 pages, 1 figur

### Higher-point conformal blocks and entanglement entropy in heavy states

We consider conformal blocks of two heavy operators and an arbitrary number
of light operators in a (1+1)-d CFT with large central charge. Using the
monodromy method, these higher-point conformal blocks are shown to factorize
into products of 4-point conformal blocks in the heavy-light limit for a class
of OPE channels. This result is reproduced by considering suitable worldline
configurations in the bulk conical defect geometry. We apply the CFT results to
calculate the entanglement entropy of an arbitrary number of disjoint intervals
for heavy states. The corresponding holographic entanglement entropy calculated
via the minimal area prescription precisely matches these results from CFT.
Along the way, we briefly illustrate the relation of these conformal blocks to
Riemann surfaces and their associated moduli space.Comment: 41 pages, 10 figures. (Published version; typos corrected and
references added.

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