PPLN waveguide for quantum communication |
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Authors: | S Tanzilli W Tittel H De Riedmatten H Zbinden P Baldi M DeMicheli DB Ostrowsky N Gisin |
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Institution: | (1) Laboratoire de Physique de la Matière Condensée, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France, FR;(2) Group of Applied Physics, Université de Genève, 20 rue de l'école-de-Médecine, 1211 Geneva 4, Switzerland, CH |
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Abstract: | We report on energy-time and time-bin entangled photon-pair sources based on a periodically poled lithium niobate (PPLN) waveguide.
Degenerate twin photons at 1 314 nm wavelength are created by spontaneous parametric down-conversion and coupled into standard
telecom fibers. Our PPLN waveguide features a very high conversion efficiency of about 10-6, roughly 4 orders of magnitude more than that obtained employing bulk crystals #!Tanzilli01a!#]. Even if using low power
laser diodes, this engenders a significant probability for creating two pairs at a time - an important advantage for some
quantum communication protocols. We point out a simple means to characterize the pair creation probability in case of a pulsed
pump. To investigate the quality of the entangled states, we perform photon-pair interference experiments, leading to visibilities
of 97% for the case of energy-time entanglement and of 84% for the case of time-bin entanglement. Although the last figure
must still be improved, these tests demonstrate the high potential of PPLN waveguide based sources to become a key element
for future quantum communication schemes.
Received 13 July 2001 |
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Keywords: | PACS 42 65 Wi Nonlinear waveguides – 03 65 Ud Entanglement and quantum nonlocality (e g EPR paradox Bell's inequalities GHZ states etc ) – 03 67 Hk Quantum communication |
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