6,049 research outputs found
Hadronic current correlation functions at finite temperature in the NJL model
Recently there have been suggestions that for a proper description of
hadronic matter and hadronic correlation functions within the NJL model at
finite density/temperature the parameters of the model should be taken
density/temperature dependent. Here we show that qualitatively similar results
can be obtained using a cutoff-independent regularization of the NJL model. In
this regularization scheme one can express the divergent parts at finite
density/temperature of the amplitudes in terms of their counterparts in vacuum.Comment: Presented at 9th Hadron Physics and 8th Relativistic Aspects of
Nuclear Physics (HADRON-RANP 2004): A Joint Meeting on QCD and QGP, Angra dos
Reis, Rio de Janeiro, Brazil, 28 Mar - 3 Apr 200
Continuous variable quantum teleportation with sculptured and noisy non-Gaussian resources
We investigate continuous variable (CV) quantum teleportation using relevant
classes of non-Gaussian states of the radiation field as entangled resources.
First, we introduce the class two-mode squeezed symmetric superposition of Fock
states, including finite truncations of twin-beam Gaussian states as special
realizations. These states depend on a set of free independent parameters that
can be adjusted for the optimization of teleportation protocols, with an
enhancement of the success probability of teleportation both for coherent and
Fock input states. We show that the optimization procedure reduces the
entangled resources to truncated twin beam states, which thus represents an
optimal class of non-Gaussian resources for quantum teleportation. We then
introduce a further class of two-mode non-Gaussian entangled resources, in the
form of squeezed cat-like states. We analyze the performance and the properties
of such states when optimized for (CV) teleportation, and compare them to the
optimized squeezed Bell-like states introduced in a previous work
\cite{CVTelepNoi}. We discuss how optimal resources for teleportation are
characterized by a suitable balance of entanglement content and squeezed vacuum
affinity. We finally investigate the effects of thermal noise on the efficiency
of quantum teleportation. To this aim, a convenient framework is to describe
noisy entangled resources as linear superpositions of non-Gaussian state and
thermal states. Although the presence of the thermal component strongly reduces
the teleportation fidelity, noisy non-Gaussian states remain preferred
resources when compared to noisy twin-beam Gaussian states.Comment: 11 pages, 8 figures. Largely revised and expanded version. New
material and sections added. To appear in EPJ-ST (Proceedings of the Central
European Workshop on Quantum Optics 2007. 14th Edition, 1-5 June 2007,
Palermo, Italy
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