3,656 research outputs found
Entanglement between an electron and a nuclear spin 1/2
We report on the preparation and detection of entangled states between an
electron spin 1/2 and a nuclear spin 1/2 in a molecular single crystal. These
were created by applying pulses at ESR (9.5 GHz) and NMR (28 MHz) frequencies.
Entanglement was detected by using a special entanglement detector sequence
based on a unitary back transformation including phase rotation.Comment: 4 pages, 3 figure
Factors influencing the development and carbohydrate metabolism of Echinococcus granulosus in dogs
Echinococcus granulosus adult worms, 35 days postinfection, were measured for dispersion in the intestines of 10 dogs, a range of morphological characters, and the excreted end products of carbohydrate catabolism following 4 hr incubation in vitro. Most worms were found in the proximal sections of the small intestine, but the pattern of dispersion differed between dogs. Worm development varied both between dogs and between different regions of the small intestine of individual dogs. Overall there was a high level of variability with no simple patterns. Worm metabolism was related to worm development and, also independently, to local population density within the intestine. Larger, more mature worms produced less lactate and, at higher densities. worms tended to produce more acetate and succinate (pathways with a higher energy yield than lactate) and less ethanol. Thus, both more developed worms and high population density are associated with a shift from cytosolic to mitochondrial metabolism. The variation between worm populations along the small intestine along with the observed variation between worm populations from sibling dogs infected with genetically identical parasites suggests that the local host environment has a significant effect on parasite development
Blow-up behaviour of a fractional Adams-Moser-Trudinger type inequality in odd dimension
Given a smoothly bounded domain with
odd, we study the blow-up of bounded sequences of solutions to the non-local equation
where , and denotes the Lions-Magenes spaces of functions which are supported in and with
. Extending previous works of
Druet, Robert-Struwe and the second author, we show that if the sequence
is not bounded in , a suitably rescaled subsequence
converges to the function
, which solves the prescribed
non-local -curvature equation recently studied by Da
Lio-Martinazzi-Rivi\`ere when , Jin-Maalaoui-Martinazzi-Xiong when ,
and Hyder when is odd. We infer that blow-up can occur only if
Dynamics of Global Entanglement under Decoherence
We investigate the dynamics of global entanglement, the Meyer-Wallach
measure, under decoherence, analytically. We study two important class of
multi-partite entangled states, the Greenberger-Horne-Zeilinger and the W
state. We obtain exact results for various models of system-environment
interactions (decoherence). Our results shows distinctly different scaling
behavior for these initially entangled states indicating a relative robustness
of the W state, consistent with previous studies.Comment: 5 pages and 5 figure
Passive decoy state quantum key distribution: Closing the gap to perfect sources
We propose a quantum key distribution scheme which closely matches the
performance of a perfect single photon source. It nearly attains the physical
upper bound in terms of key generation rate and maximally achievable distance.
Our scheme relies on a practical setup based on a parametric downconversion
source and present-day, non-ideal photon-number detection. Arbitrary
experimental imperfections which lead to bit errors are included. We select
decoy states by classical post-processing. This allows to improve the effective
signal statistics and achievable distance.Comment: 4 pages, 3 figures. State preparation correcte
Global vs local cosmic strings from pseudo-anomalous U(1)
We study the structure of cosmic strings produced at the breaking of an
anomalous U(1) gauge symmetry present in many superstring compactification
models. We show that their coupling with the axion necessary in order to cancel
the anomalies does not prevent them from being local, even though their energy
per unit length is found to diverge logarithmically. We discuss the formation
of such strings and the phenomenological constraints that apply to their
parameters.Comment: 6 pages, uses RevTeX, no figur
Entangled photons from a strongly coupled quantum dot-cavity system
A quantum dot strongly coupled to a photonic crystal has been recently
proposed as a source of entangled photon pairs [R. Johne et al., Phys. Rev.
Lett. 100, 240404 (2008)]. The biexction decay via intermediate polariton
states can be used to overcome the natural splitting between the exciton states
coupled to the horizontally and vertically polarized light modes, so that high
degrees of entanglement can be expected. We investigate theoretically the
features of realistic dot-cavity systems, including the effect of the different
oscillator strength of excitons resonances coupled to the different
polarizations of light. We show that in this case, an independent adjustment of
the cavity resonances is needed in order to keep a high entanglement degree. We
also consider the case when the biexciton-exciton transition is also strongly
coupled to a cavity mode. We show that a very fast emission rate can be
achieved allowing the repetition rates in the THz range. Such fast emission
should however be paid for by a very complex tuning of the many strongly
coupled resonances involved and by a loss of quantum efficiency. Altogether a
strongly coupled dot-cavity system seems to be very promising as a source of
entangled photon pairs.Comment: 7 pages, 5 figure
A deterministic cavity-QED source of polarization entangled photon pairs
We present two cavity quantum electrodynamics proposals that, sharing the
same basic elements, allow for the deterministic generation of entangled
photons pairs by means of a three-level atom successively coupled to two single
longitudinal mode high-Q optical resonators presenting polarization degeneracy.
In the faster proposal, the three-level atom yields a polarization entangled
photon pair via two truncated Rabi oscillations, whereas in the adiabatic
proposal a counterintuitive Stimulated Raman Adiabatic Passage process is
considered. Although slower than the former process, this second method is very
efficient and robust under fluctuations of the experimental parameters and,
particularly interesting, almost completely insensitive to atomic decay.Comment: 5 pages, 5 figure
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