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Updated: Jun 5, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Production of degenerate polarization entangled photon pairs in the telecom-band from a pump enhanced parametric
P J Thomas1, C J Chunnilall, D J M Stothard
1National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK. peterjaythomas@googlemail.com
Abstract:
The design and implementation of a novel source of degenerate polarization entangled photon pairs in the telecom band, based on a cavity enhanced parametric downconversion process, is presented. Two of the four maximally entangled Bell states are produced; the remaining two are obtainable by the addition of a half wave plate into the setup. The coincident photon detection rate in the A/D basis between two detectors at the output of the device revealed the production of highly entangled states, resulting in quantum interference visibilities of 0.971 ± 0.041 (ϕ = 0 state) and 0.932 ± 0.036 (ϕ = π state) respectively. The entangled states were found to break the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality by around 6 standard deviations. From the measured coincidence counting rates and the optical system losses, an entangled photon pair production rate of 8.9 × 10(4) s(-1) mW(-1) pump was estimated.
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