215 research outputs found
Generation of polarization entangled photon pairs by a single crystal interferometric source pumped by femtosecond laser pulses
Photon pairs, highly entangled in polarization have been generated under
femtosecond laser pulse excitation by a type I crystal source, operating in a
single arm interferometric scheme. The relevant effects of temporal walk-off
existing in these conditions between the ordinary and extraordinary photons
were experimentally investigated. By introducing a suitable temporal
compensation between the two orthogonal polarization components highly
entangled pulsed states were obtained
Experimental Bell inequality violation without the postselection loophole
We report on an experimental violation of the Bell-Clauser-Horne-Shimony-Holt
(Bell-CHSH) inequality using energy-time entangled photons. The experiment is
not free of the locality and detection loopholes, but is the first violation of
the Bell-CHSH inequality using energy-time entangled photons which is free of
the postselection loophole described by Aerts et al. [Phys. Rev. Lett. 83, 2872
(1999)].Comment: 4 pages, 3 figures, v2 minor correction
Quantum tomography of the GHZ state
We present a method of generation of the Greenberger-Horne-Zeilinger state
involving type II and type I parametric downconversion, and triggering
photodetectors. The state generated by the proposed experimental set-up can be
reconstructed through multi-mode quantum homodyne tomography. The feasibility
of the measurement is studied on the basis of Monte-Carlo simulations.Comment: Paper submitted to the proceedings of the III Adriatico Research
Conference on Quantum Interferometry, ICTP, March 1-5,1999. 5 pages, 3 eps
figure
Hyperentanglement of two photons in three degrees of freedom
A 6-qubit hyperentangled state has been realized by entangling two photons in
three degrees of freedom. These correspond to the polarization, the
longitudinal momentum and the indistinguishable emission produced by a
2-crystal system operating with Type I phase matching in the spontaneous
parametric down conversion regime. The state has been characterized by a
chained interferometric apparatus and its complete entangled nature has been
tested by a novel witness criterium specifically introduced for hyperentangled
states. The experiment represents the first realization of a genuine
hyperentangled state with the maximum entanglement between the two particles
allowed in the given Hilbert space.Comment: 4 pages, 2 figures, Revtex
Hyperentangled mixed phased Dicke states: optical design and detection
We present an experimental method to produce 4-qubit phased Dicke states,
based on a source of 2-photon hyperentangled states. By introducing quantum
noise in the multipartite system in a controlled way, we have tested the
robustness of these states. To this purpose the entanglement of the resulting
multipartite entangled mixed states has been verified by using a new kind of
structural witness.Comment: 6 pages, 3 figure, supplementary information include
Complete and Deterministic discrimination of polarization Bell state assisted by momentum entanglement
A complete and deterministic Bell state measurement was realized by a simple
linear optics experimental scheme which adopts 2-photon polarization-momentum
hyperentanglement. The scheme, which is based on the discrimination among the
single photon Bell states of the hyperentangled state, requires the adoption of
standard single photon detectors. The four polarization Bell states have been
measured with average fidelity by using the linear momentum
degree of freedom as the ancilla. The feasibility of the scheme has been
characterized as a function of the purity of momentum entanglement.Comment: 4 pages, v2, comments adde
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