4,212 research outputs found
Reduction criterion for separability
We introduce a separability criterion based on the positive map Γ:ρ→(Tr ρ)-ρ, where ρ is a trace-class Hermitian operator. Any separable state is mapped by the tensor product of Γ and the identity into a non-negative operator, which provides a simple necessary condition for separability. This condition is generally not sufficient because it is vulnerable to the dilution of entanglement. In the special case where one subsystem is a quantum bit, Γ reduces to time reversal, so that this separability condition is equivalent to partial transposition. It is therefore also sufficient for 2×2 and 2×3 systems. Finally, a simple connection between this map for two qubits and complex conjugation in the “magic” basis [Phys. Rev. Lett. 78, 5022 (1997)] is displayed
Effect of charged partons on black hole production at the Large Hadron Collider
The cross section for black hole production in hadron colliders is calculated
using a factorization hypothesis in which the parton-level process is
integrated over the parton density functions of the protons. The mass, spin,
charge, colour, and finite size of the partons are usually ignored. We examine
the effects of parton electric charge on black hole production using the
trapped-surface approach of general relativity. Accounting for electric charge
of the partons could reduce the black hole cross section by one to four orders
of magnitude at the Large Hadron Collider. The cross section results are
sensitive to the Standard Model brane thickness. Lower limits on the amount of
energy trapped behind the event horizon in the collision of charged particles
are also calculated.Comment: corrected typo in figure 1b; added some clarification in 3 places; 21
pages, 9 figures, JHEP3 forma
Teleportation with a uniformly accelerated partner
In this work, we give a description of the process of teleportation between
Alice in an inertial frame, and Rob who is in uniform acceleration with respect
to Alice. The fidelity of the teleportation is reduced due to Unruh radiation
in Rob's frame. In so far as teleportation is a measure of entanglement, our
results suggest that quantum entanglement is degraded in non inertial frames.Comment: 7 pages with 4 figures (in revtex4
Noncommutative geometry inspired black holes in higher dimensions at the LHC
When embedding models of noncommutative geometry inspired black holes into
the peridium of large extra dimensions, it is natural to relate the
noncommutativity scale to the higher-dimensional Planck scale. If the Planck
scale is of the order of a TeV, noncommutative geometry inspired black holes
could become accessible to experiments. In this paper, we present a detailed
phenomenological study of the production and decay of these black holes at the
Large Hadron Collider (LHC). Noncommutative inspired black holes are relatively
cold and can be well described by the microcanonical ensemble during their
entire decay. One of the main consequences of the model is the existence of a
black hole remnant. The mass of the black hole remnant increases with
decreasing mass scale associated with noncommutative and decreasing number of
dimensions. The experimental signatures could be quite different from previous
studies of black holes and remnants at the LHC since the mass of the remnant
could be well above the Planck scale. Although the black hole remnant can be
very heavy, and perhaps even charged, it could result in very little activity
in the central detectors of the LHC experiments, when compared to the usual
anticipated black hole signatures. If this type of noncommutative inspired
black hole can be produced and detected, it would result in an additional mass
threshold above the Planck scale at which new physics occurs.Comment: 21 pages, 7 figure
OSETI with STACEE: A Search for Nanosecond Optical Transients from Nearby Stars
We have used the STACEE high-energy gamma-ray detector to look for fast
blue-green laser pulses from the vicinity of 187 stars. The STACEE detector
offers unprecedented light-collecting capability for the detection of
nanosecond pulses from such lasers. We estimate STACEE's sensitivity to be
approximately 10 photons per square meter at a wavelength of 420 nm. The stars
have been chosen because their characteristics are such that they may harbor
habitable planets and they are relatively close to Earth. Each star was
observed for 10 minutes and we found no evidence for laser pulses in any of the
data sets.Comment: 38 pages, 12 figures. Accepted for publication in Astrobiolog
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