Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE EUROCON - International Conference on Computer as a Tool (EUROCON)

Polarization-entangled photon pairs using spontaneous four-wave mixing in a fiber loop

A. J. Almeida, S. R. M. Carneiro, N. A. Silva, Nelson Jesus Muga, Armando N. Pinto

Published Apr 1, 2011• 5 citations
Publisher

Abstract

We generate polarization-entangled photon pairs in the 1550-nm wavelength telecom band, using spontaneous four-wave mixing in a highly nonlinear fiber loop. With accidental coincidences subtracted, we obtain coincidence fringes with visibilities greater than 86%, and thus observe a violation of Clauser, Horne, Shimony and Holt (CHSH) inequality by 2.7 standard deviations. The experimental setup is built using only fiber connections, which contribute to its long time stability.

DOI
10.1109/eurocon.2011.5929315

Related papers

Generation of polarization-entangled photon pairs and violation of Bell’s inequality using spontaneous four-wave mixing in a fiber loop

Hiroki Takesue, Kyo Inoue

We report the generation of polarization entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing in a dispersion-shifted fiber loop. The use of the fiber-loop configuration made it possible to generate polarization entangled states very stably. With accidental coincidences subtracted, we obtained coincidence fringes with $>90%$ visibilities, and observed a violation of Bell's inequality by seven standard deviations. We also confirmed the preservation of the quantum correlation between the photons even after they had been separated by 20 km of optical fiber.

arXiv:quant-ph/0408032•Physical Review A•Sep 30, 2004•223 citations

Violation of Bell's Inequality in 1550 nm Band without Subtraction of Accidental Coincidences

Akio Yoshizawa, Hidemi Tsuchida

A violation of Bell's inequalities using quantum entanglement indicates the nonlocality of two particles such as photons and electrons. We observe a violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, a particular Bell's inequality, in polarization-entangled photon pairs in the 1550 nm band. For photon pair generation based on spontaneous parametric down conversion, a fiber-optic two-photon interferometer with two periodically poled lithium niobate waveguides is adopted. The obtained S value of the CHSH inequality is 2.44 ±0.02 without subtraction of accidental coincidences, yielding a violation by ∼22 standard deviations in an hour. Two-photon interference with a visibility of 0.885 is also observed. If those coincidences are subtracted, the visibility becomes almost unity.

Japanese Journal of Applied Physics•Mar 1, 2005•7 citations

Generation of high-purity entangled photon pair in a short highly nonlinear fiber

Yong Meng Sua, John E. Malowicki, Masaaki Hirano +1 more

We generate photon pairs at telecom wavelength through a spontaneous four-wave mixing process in a short 10 m of highly nonlinear fiber. We use a counterpropagating scheme to generate a correlated and entangled photon pair. We observe coincidence to accidental-coincidence ratio of 29±3 at room temperature (300 K) and as high as 130±5 when the fiber is cooled to liquid-nitrogen temperature (77 K). Two-photon interference with visibility >98% (>92%) and the violation of Bell's inequality by >12 (≈5) standard deviation are observed at 77 K (300 K), respectively, without subtracting accidental-coincidence count. We obtain a photon-pair production rate about factor 3(2) higher than a 300 m dispersion-shifted fiber at 300 K (77 K).

Optics Letters•Dec 20, 2012•29 citations

Optical-Fiber Source of Polarization-Entangled Photons in the 1550 nm Telecom Band

Xiaoying Li, Paul L. Voss, Jay E. Sharping +1 more

We present a fiber-based source of polarization-entangled photons that is well suited for quantum communication applications in the 1550 nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal and idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal and idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either signal or idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of the Clauser-Horne-Shimony-Holt form of Bell's inequality by up to 10 standard deviations of measurement uncertainty.

arXiv:quant-ph/0402191•Physical Review Letters•Feb 9, 2005•454 citations

Generation of High Purity Photon-Pair in a Short Highly Non-Linear Fiber

Yong Meng Sua, John E. Malowicki, Masaaki Hirano +1 more

Abstract : We generate photon pairs at telecom wavelength through a spontaneous four-wave mixing process in a short 10 m of highly nonlinear fiber. We use a counter propagating scheme to generate a correlated and entangled photon pair. We observe coincidence to accidental-coincidence ratio of 29 + or - 3 at room temperature (300 K) and as high as 130 + or - 5 when the fiber is cooled to liquid-nitrogen temperature (77 K). Two-photon interference with visibility 98% (92%) and the violation of Bell's inequality by 12 (approx. equal 5) standard deviation are observed at 77 K (300 K), respectively, without subtracting accidental-coincidence count. We obtain a photon-pair production rate about factor 3(2) higher than a 300 m dispersion-shifted fiber at 300 K (77 K).

•Jan 1, 2013•1 citation

Direct Generation of Polarization-Entangled Photon Pairs in a Poled Fiber

Eric Y. Zhu, Zhiyuan Tang, Li Qian +7 more

We experimentally demonstrate the direct generation of polarization-entangled photon pairs in an optical fiber at room temperature by exploiting type-II phase-matched spontaneous parametric down-conversion. A second-order nonlinearity is artificially induced in the 17-cm-long weakly birefringent step-index fiber through the process of thermal poling, and quasi-phase-matching allows for the generation of entangled photons in the 1.5-micron telecom band when the fiber is pumped at 775 nm. A greater-than 80:1 coincidence-to-accidental ratio is achieved, limited mainly by multiphoton pair generation. Without the need to subtract accidentals or to compensate for walk-off, the raw two-photon interference visibility is found to be better than 95%, and violation of Bell's inequality is observed by more than 18 standard deviations. This makes for a truly alignment-free, plug-and-play source of polarization-entangled photon pairs.

Physical Review Letters•May 21, 2012•83 citations
We generate polarization-entangled photon pairs in the 1550-nm wavelength telecom band, using spontaneous four-wave mixing in a highly nonlinear fiber loop. With accidental coincidences subtracted, we obtain coincidence fringes with visibilities greater than 86%, and thus observe a violation of Clauser, Horne, Shimony and Holt (CHSH) inequality by 2.7 standard deviations. The experimental setup is built using only fiber connections, which contribute to its long time stability.
We report the generation of polarization entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing in a dispersion-shifted fiber loop. The use of the fiber-loop configuration made it possible to generate polarization entangled states very stably. With accidental coincidences subtracted, we obtained coincidence fringes with >90>90%>90 visibilities, and observed a violation of Bell's inequality by seven standard deviations. We also confirmed the preservation of the quantum correlation between the photons even after they had been separated by 20 km of optical fiber.
A violation of Bell's inequalities using quantum entanglement indicates the nonlocality of two particles such as photons and electrons. We observe a violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, a particular Bell's inequality, in polarization-entangled photon pairs in the 1550 nm band. For photon pair generation based on spontaneous parametric down conversion, a fiber-optic two-photon interferometer with two periodically poled lithium niobate waveguides is adopted. The obtained S value of the CHSH inequality is 2.44 ±0.02 without subtraction of accidental coincidences, yielding a violation by ∼22 standard deviations in an hour. Two-photon interference with a visibility of 0.885 is also observed. If those coincidences are subtracted, the visibility becomes almost unity.
We generate photon pairs at telecom wavelength through a spontaneous four-wave mixing process in a short 10 m of highly nonlinear fiber. We use a counterpropagating scheme to generate a correlated and entangled photon pair. We observe coincidence to accidental-coincidence ratio of 29±3 at room temperature (300 K) and as high as 130±5 when the fiber is cooled to liquid-nitrogen temperature (77 K). Two-photon interference with visibility >98% (>92%) and the violation of Bell's inequality by >12 (≈5) standard deviation are observed at 77 K (300 K), respectively, without subtracting accidental-coincidence count. We obtain a photon-pair production rate about factor 3(2) higher than a 300 m dispersion-shifted fiber at 300 K (77 K).
We present a fiber-based source of polarization-entangled photons that is well suited for quantum communication applications in the 1550 nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal and idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal and idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either signal or idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of the Clauser-Horne-Shimony-Holt form of Bell's inequality by up to 10 standard deviations of measurement uncertainty.
Abstract : We generate photon pairs at telecom wavelength through a spontaneous four-wave mixing process in a short 10 m of highly nonlinear fiber. We use a counter propagating scheme to generate a correlated and entangled photon pair. We observe coincidence to accidental-coincidence ratio of 29 + or - 3 at room temperature (300 K) and as high as 130 + or - 5 when the fiber is cooled to liquid-nitrogen temperature (77 K). Two-photon interference with visibility 98% (92%) and the violation of Bell's inequality by 12 (approx. equal 5) standard deviation are observed at 77 K (300 K), respectively, without subtracting accidental-coincidence count. We obtain a photon-pair production rate about factor 3(2) higher than a 300 m dispersion-shifted fiber at 300 K (77 K).
We experimentally demonstrate the direct generation of polarization-entangled photon pairs in an optical fiber at room temperature by exploiting type-II phase-matched spontaneous parametric down-conversion. A second-order nonlinearity is artificially induced in the 17-cm-long weakly birefringent step-index fiber through the process of thermal poling, and quasi-phase-matching allows for the generation of entangled photons in the 1.5-micron telecom band when the fiber is pumped at 775 nm. A greater-than 80:1 coincidence-to-accidental ratio is achieved, limited mainly by multiphoton pair generation. Without the need to subtract accidentals or to compensate for walk-off, the raw two-photon interference visibility is found to be better than 95%, and violation of Bell's inequality is observed by more than 18 standard deviations. This makes for a truly alignment-free, plug-and-play source of polarization-entangled photon pairs.