Abstract
We demonstrate an all-fiber photon-pair source with the highest coincidence-to-accidental ratio (CAR) reported to date in the fiber-optic telecom C-band. We achieve this through careful optimization of pairproduction efficiency as well as careful characterization and minimization of all sources of background photons, including Raman generation in the nonlinear fiber, Raman generation in the single-mode fiber, and leakage of pump photons. We cool the nonlinear fiber to 4 K to eliminate most of the Raman scattering, and we reduce other noise photon counts through careful system design. This yields a CAR of 1300 at a pair generation rate of 2 kHz. This CAR is a factor of 12 higher than previously reported results in the C-band. Measured data agree well with theoretical predictions.
Highlights
Photon-pair sources have exciting applications as entangled photon-pair generators or as heralded sources of single photons in fields such as linear optical quantum computing, entanglement-based quantum key distribution, and metrology
Photon pairs were generated from spontaneous parametric down conversion (SPDC) in free-space nonlinear crystals and atoms [1], but more recently pair generation from four-wave mixing (FWM) in optical fiber has generated strong interest [2,3,4,5,6]
The efficiency of FWM in optical fiber is directly related to the dispersion of the fiber, with the highest efficiency occurring near the zero-dispersion wavelength (ZDW) of the fiber
Summary
Photon-pair sources have exciting applications as entangled photon-pair generators or as heralded sources of single photons in fields such as linear optical quantum computing, entanglement-based quantum key distribution, and metrology. Photon-pair generation in optical fiber has many advantages, including compatibility with existing fiber telecommunications networks and low-loss coupling to single-photon counting detectors. Another key advantage of our all-fiber photon pair source is its compact and portable design. An alternative for achieving high CAR with cryogenic cooling of the fiber is to use microstructure or photonic crystal fiber [8,9,10,11,12] These fibers have single-mode transmission over a broad wavelength range, and the Raman generation can be reduced through a wide detuning between the pump and the signal and idler wavelengths. We show agreement between measured data and the predictions based on [13]
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