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Phys. Rev. A 70, 031802(R) (2004) [4 pages]

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

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Hiroki Takesue* and Kyo Inoue
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0198, Japan

Received 25 March 2004; published 30 September 2004

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.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.70.031802
DOI:
10.1103/PhysRevA.70.031802
PACS:
42.50.Dv, 42.65.Lm, 03.67.Hk

*Electronic address: htakesue@will.brl.ntt.co.jp;