dorsal/arxiv
View SchemaTheory and experiment of entanglement in a quasi-phase-matched two-crystal source
| Authors | Daniel Ljunggren, Maria Tengner, Philip Marsden, Matthew Pelton |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0510218 |
| URL | https://arxiv.org/abs/quant-ph/0510218 |
| DOI | 10.1103/PhysRevA.73.032326 |
Abstract
We report new results regarding a source of polarization entangled photon-pairs created by the process of spontaneous parametric downconversion in two orthogonally oriented, periodically poled, bulk KTiOPO4 crystals (PPKTP). The source emits light colinearly at the non-degenerate wavelengths of 810 nm and 1550 nm, and is optimized for single-mode optical fiber collection and long-distance quantum communication. The configuration favors long crystals, which promote a high photon-pair production rate at a narrow bandwidth, together with a high pair-probability in fibers. The quality of entanglement is limited by chromatic dispersion, which we analyze by determining the output state. We find that such a decoherence effect is strongly material dependent, providing for long crystals an upper bound on the visibility of the coincidence fringes of 41% for KTiOPO4, and zero for LiNbO3. The best obtained raw visibility, when canceling decoherence with an extra piece of crystal, was 91 \pm 0.2%, including background counts. We confirm by a violation of the CHSH-inequality (S = 2.679 \pm 0.004 at 55 s^{-1/2} standard deviations) and by complete quantum state tomography that the fibers carry high-quality entangled pairs at a maximum rate of 55 x 10^3 s^{-1}THz^{-1}mW^{-1}.
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"abstract": "We report new results regarding a source of polarization entangled\nphoton-pairs created by the process of spontaneous parametric downconversion in\ntwo orthogonally oriented, periodically poled, bulk KTiOPO4 crystals (PPKTP).\nThe source emits light colinearly at the non-degenerate wavelengths of 810 nm\nand 1550 nm, and is optimized for single-mode optical fiber collection and\nlong-distance quantum communication. The configuration favors long crystals,\nwhich promote a high photon-pair production rate at a narrow bandwidth,\ntogether with a high pair-probability in fibers. The quality of entanglement is\nlimited by chromatic dispersion, which we analyze by determining the output\nstate. We find that such a decoherence effect is strongly material dependent,\nproviding for long crystals an upper bound on the visibility of the coincidence\nfringes of 41% for KTiOPO4, and zero for LiNbO3. The best obtained raw\nvisibility, when canceling decoherence with an extra piece of crystal, was 91\n\\pm 0.2%, including background counts. We confirm by a violation of the\nCHSH-inequality (S = 2.679 \\pm 0.004 at 55 s^{-1/2} standard deviations) and by\ncomplete quantum state tomography that the fibers carry high-quality entangled\npairs at a maximum rate of 55 x 10^3 s^{-1}THz^{-1}mW^{-1}.",
"arxiv_id": "quant-ph/0510218",
"authors": [
"Daniel Ljunggren",
"Maria Tengner",
"Philip Marsden",
"Matthew Pelton"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.73.032326",
"title": "Theory and experiment of entanglement in a quasi-phase-matched two-crystal source",
"url": "https://arxiv.org/abs/quant-ph/0510218"
},
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