124 research outputs found
Entanglement of a Single Spin-1 Object: An Example of Ubiquitous Entanglement
Using a single spin-1 object as an example, we discuss a recent approach to
quantum entanglement. The key idea of the approach consists in presetting of
basic observables in the very definition of quantum system. Specification of
basic observables defines the dynamic symmetry of the system. Entangled states
of the system are then interpreted as states with maximal amount of uncertainty
of all basic observables. The approach gives purely physical picture of
entanglement. In particular, it separates principle physical properties of
entanglement from inessential. Within the model example under consideration, we
show relativity of entanglement with respect to dynamic symmetry and argue
existence of single-particle entanglement. A number of physical examples are
considered.Comment: 12 pages, 2 figure : title has been changed, paper is re-organized,
new section "Violation of Bell-type condition by single spin-1" is adde
Robust Entanglement in Atomic Systems via Lambda-Type Processes
It is shown that the system of two three-level atoms in
configuration in a cavity can evolve to a long-lived maximum entangled state if
the Stokes photons vanish from the cavity by means of either leakage or
damping. The difference in evolution picture corresponding to the general model
and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure
Single-particle entanglement
Using the approach to quantum entanglement based on the quantum fluctuations of observables, we show the existence of perfect entangled states of a single 'spin-1' particle. We give physical examples related to photons and condensed matter physics. © 2005 IOP Publishing Ltd
Faithful remote state preparation using finite classical bits and a non-maximally entangled state
We present many ensembles of states that can be remotely prepared by using
minimum classical bits from Alice to Bob and their previously shared entangled
state and prove that we have found all the ensembles in two-dimensional case.
Furthermore we show that any pure quantum state can be remotely and faithfully
prepared by using finite classical bits from Alice to Bob and their previously
shared nonmaximally entangled state though no faithful quantum teleportation
protocols can be achieved by using a nonmaximally entangled state.Comment: 6 page
Noninvasive rapid detection of metabolic adaptation in activated human T lymphocytes by hyperpolarized <sup>13</sup>C magnetic resonance.
The metabolic shift induced in human CD4 <sup>+</sup> T lymphocytes by stimulation is characterized by an upregulation of glycolysis, leading to an augmentation in lactate production. This adaptation has already been highlighted with various techniques and reported in several previous studies. We herein propose a method to rapidly and noninvasively detect the associated increase in flux from pyruvate to lactate catalyzed by lactate dehydrogenase using hyperpolarized <sup>13</sup> C magnetic resonance, a technique which can be used for in vivo imaging. It was shown that the conversion of hyperpolarized <sup>13</sup> C-pyruvate to <sup>13</sup> C-lactate during the one-minute measurement increased by a mean factor of 3.6 in T cells stimulated for 5 days as compared to resting T cells. This method can be extended to other metabolic substrates and is therefore a powerful tool to noninvasively analyze T cell metabolism, possibly in vivo
Persistent Perfect Entanglement in Atomic Systems
It is shown that the system of an even number of three-level atoms in the Λ configuration in a cavity can evolve into a persistent maximum entangled state. The time of formation of such an entangled state is estimated
Persistent entanglement in three-level atomic systems
We discuss the evolution towards persistent entangled state in an atom-photon system. A maximally entangled state can be stabilized at a local minimum of the system by draining some energy, thus obtaining a persistent entangled state. This scheme can be realized in three-level, A type atomic systems since the third level is a meta-stable state. In particular, we compare dynamical description based on the exact and effective models. Some experimental realizations are discussed
Angular momentum of photons emitted by atoms
It is shown that the spin and orbital angular momentum of electric dipole photons have the same operator structure and may differ from each other only in the spatial dependence in the very vicinity of the atom. It is shown that the photon twins created by a dipole forbidden transition can manifest the maximum entanglement with respect to the angular momentum. It is shown that the states of photons with a projection of angular momentum m = 0 are less stable than those with m = ±1
Lower limit on the neutralino mass in the general MSSM
We discuss constraints on SUSY models with non-unified gaugino masses and R_P
conservation. We derive a lower bound on the neutralino mass combining the
direct limits from LEP, the indirect limits from gmuon, bsgamma, Bsmumu and the
relic density constraint from WMAP. The lightest neutralino (mneutralino=6GeV)
is found in models with a light pseudoscalar with MA<200GeV and a large value
for . Models with heavy pseudoscalars lead to mneutralino>18(29)GeV
for . We show that even a very conservative bound from the
muon anomalous magnetic moment can increase the lower bound on the neutralino
mass in models with mu<0 and/or large values of . We then examine
the potential of the Tevatron and the direct detection experiments to probe the
SUSY models with the lightest neutralinos allowed in the context of light
pseudoscalars with high . We also examine the potential of an e+e-
collider of 500GeV to produce SUSY particles in all models with neutralinos
lighter than the W. In contrast to the mSUGRA models, observation of at least
one sparticle is not always guaranteed.Comment: 37 pages, LateX, 16 figures, paper with higher resolution figures
available at
http://wwwlapp.in2p3.fr/~boudjema/papers/bound-lsp/bound-lsp.htm
Methods and algorithms for unsupervised learning of morphology
This is an accepted manuscript of a chapter published by Springer in Computational Linguistics and Intelligent Text Processing. CICLing 2014. Lecture Notes in Computer Science, vol 8403 in 2014 available online: https://doi.org/10.1007/978-3-642-54906-9_15
The accepted version of the publication may differ from the final published version.This paper is a survey of methods and algorithms for unsupervised learning of morphology. We provide a description of the methods and algorithms used for morphological segmentation from a computational linguistics point of view. We survey morphological segmentation methods covering methods based on MDL (minimum description length), MLE (maximum likelihood estimation), MAP (maximum a posteriori), parametric and non-parametric Bayesian approaches. A review of the evaluation schemes for unsupervised morphological segmentation is also provided along with a summary of evaluation results on the Morpho Challenge evaluations.Published versio
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