Fiber-Optic Sources of Quantum Entanglement

TL;DR

This paper introduces a fiber-based source of polarization-entangled photon pairs at 1.5μm, suitable for quantum communication, demonstrating high-visibility biphoton interference using a nonlinear fiber Sagnac interferometer.

Contribution

The work presents a novel fiber-based entangled photon source operating at telecom wavelengths with demonstrated high-visibility interference.

Findings

Photon pairs exhibit >90% biphoton interference visibility.

Entanglement is generated using a fiber Sagnac interferometer with orthogonally polarized pulses.

Nonclassical properties confirmed with InGaAs/InP avalanche photodiodes.

Abstract

We present a fiber-based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1.5$\mu$m band of standard telecommunication fiber. Quantum-correlated signal and idler photon pairs are produced when a nonlinear-fiber Sagnac interferometer is pumped in the anomalous-dispersion region of the fiber. Recently, we have demonstrated nonclassical properties of such photon pairs by using Geiger-mode InGaAs/InP avalanche photodiodes. Polarization entanglement in the photon pairs can be created by pumping the Sagnac interferometer with two orthogonally polarized pulses. In this case the parametrically scattered signal-idler photons yield biphoton interference with $>$90% visibility in coincidence detection, while no interference is observed in direct detection of either the signal or the idler photons.