14,962 research outputs found
Wigner representation for polarization-momentum hyperentanglement generated in parametric down conversion, and its application to complete Bell-state measurement
We apply the Wigner function formalism to the study of two-photon
polarization-momentum hyperentanglement generated in parametric down
conversion. It is shown that the consideration of a higher number of degrees of
freedom is directly related to the extraction of additional uncorrelated sets
of zeropoint modes at the source. We present a general expression for the
description of the quantum correlations corresponding to the sixteen Bell base
states, in terms of four beams whose amplitudes are correlated through the
stochastic properties of the zeropoint field. A detailed analysis of the two
experiments on complete Bell-state measurement included in [Walborn et al.,
Phys. Rev. A 68, 042313 (2003)] is made, emphasizing the role of the zeropoint
field. Finally, we investigate the relationship between the zeropoint inputs at
the source and the analysers, and the limits on optimal Bell-state measurement.Comment: 28 pages, 4 figure
Partial Bell-state analysis with parametric down conversion in the Wigner function formalism
We apply the Wigner function formalism to partial Bell-state analysis using
polarization entanglement produced in parametric down conversion. Two-photon
statistics at a beam-splitter are reproduced by a wavelike description with
zeropoint fluctuations of the electromagnetic field. In particular, the
fermionic behaviour of two photons in the singlet state is explained from the
invariance on the correlation properties of two light beams going through a
balanced beam-splitter. Moreover, we show that a Bell-state measurement
introduces some fundamental noise at the idle channels of the analyzers. As a
consequence, the consideration of more independent sets of vacuum modes
entering the crystal appears as a need for a complete Bell-state analysis
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Entanglement Swapping: Entangling Atoms That Never Interacted
In this paper we discuss four different proposals of entangling atomic states
of particles which have never interacted. The experimental realization proposed
makes use of the interaction of Rydberg atoms with a micromaser cavity prepared
in either a coherent state or in a superposition of the zero and one field Fock
states. We consider atoms in either a three-level cascade or lambda
configurationComment: 17 pages and 2 figure
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