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Title: Theory and experiment of entanglement in a quasi-phase-matched two-crystal source

Abstract

We report results regarding a source of polarization entangled photon pairs created by the process of spontaneous parametric downconversion in two orthogonally oriented, periodically poled, bulk KTiOPO{sub 4} crystals. The source emits light colinearly at the nondegenerate wavelengths of 810 and 1550 nm, and is optimized for a 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 KTiOPO{sub 4}, and zero for LiNbO{sub 3}. The best obtained raw visibility, when canceling decoherence with an extra piece of crystal, was 91{+-}0.2%, including background counts. We confirm by a violation of the CHSH-inequality (S=2.679{+-}0.004 at 55 s{sup -1/2} standard deviations) and by complete quantum state tomography that the fibers carry high-quality entangled pairs at a maximum rate of 55x10{sup 3} s{sup -1} THz{sup -1} mW{sup -1}.

Authors:
; ; ;  [1]
  1. Department of Microelectronics and Information Technology, Royal Institute of Technology, KTH, Electrum 229, SE-164 40 Kista (Sweden)
Publication Date:
OSTI Identifier:
20786875
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 73; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.73.032326; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CONVERSION; CRYSTALS; DATA TRANSMISSION; DISTANCE; LITHIUM COMPOUNDS; NIOBATES; OPTICAL FIBERS; OPTICAL MODES; OPTICS; PAIR PRODUCTION; PERIODICITY; PHOTONS; POLARIZATION; POTASSIUM COMPOUNDS; PROBABILITY; QUANTUM ENTANGLEMENT; QUANTUM MECHANICS; TITANIUM COMPOUNDS; TOMOGRAPHY

Citation Formats

Ljunggren, Daniel, Tengner, Maria, Marsden, Philip, and Pelton, Matthew. Theory and experiment of entanglement in a quasi-phase-matched two-crystal source. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.0.
Ljunggren, Daniel, Tengner, Maria, Marsden, Philip, & Pelton, Matthew. Theory and experiment of entanglement in a quasi-phase-matched two-crystal source. United States. https://doi.org/10.1103/PHYSREVA.73.0
Ljunggren, Daniel, Tengner, Maria, Marsden, Philip, and Pelton, Matthew. Wed . "Theory and experiment of entanglement in a quasi-phase-matched two-crystal source". United States. https://doi.org/10.1103/PHYSREVA.73.0.
@article{osti_20786875,
title = {Theory and experiment of entanglement in a quasi-phase-matched two-crystal source},
author = {Ljunggren, Daniel and Tengner, Maria and Marsden, Philip and Pelton, Matthew},
abstractNote = {We report results regarding a source of polarization entangled photon pairs created by the process of spontaneous parametric downconversion in two orthogonally oriented, periodically poled, bulk KTiOPO{sub 4} crystals. The source emits light colinearly at the nondegenerate wavelengths of 810 and 1550 nm, and is optimized for a 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 KTiOPO{sub 4}, and zero for LiNbO{sub 3}. The best obtained raw visibility, when canceling decoherence with an extra piece of crystal, was 91{+-}0.2%, including background counts. We confirm by a violation of the CHSH-inequality (S=2.679{+-}0.004 at 55 s{sup -1/2} standard deviations) and by complete quantum state tomography that the fibers carry high-quality entangled pairs at a maximum rate of 55x10{sup 3} s{sup -1} THz{sup -1} mW{sup -1}.},
doi = {10.1103/PHYSREVA.73.0},
url = {https://www.osti.gov/biblio/20786875}, journal = {Physical Review. A},
issn = {1050-2947},
number = 3,
volume = 73,
place = {United States},
year = {2006},
month = {3}
}