11 May 2007 Femtosecond laser-pumped source of entangled photons for quantum cryptography applications
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We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion, based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulsewidth, mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an equal pump power. The output infrared pump photons (λ = 810 nm) are first up-converted to blue light (λ = 405 nm) and, subsequently, down-converted in a 1.5-mm-thick, type-II BBO crystal via spontaneous down-conversion. The resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes. The total down-conversion efficiency of our system, corresponding criterion of the pump power for real entangled coincident events, has been calculated to be 0.86 × 10-9. Our apparatus is intended as an efficient source/receiver system for the quantum communications and quantum cryptography applications.
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Dong Pan, Dong Pan, William Donaldson, William Donaldson, Roman Sobolewski, Roman Sobolewski, } "Femtosecond laser-pumped source of entangled photons for quantum cryptography applications", Proc. SPIE 6583, Photon Counting Applications, Quantum Optics, and Quantum Cryptography, 65830K (11 May 2007); doi: 10.1117/12.723698; https://doi.org/10.1117/12.723698

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