Jason Mickel, Josh Aller, Philip Battle, Alex Bierut, Catherine Lee, Tony Roberts
Abstract
High rate, high spectral purity entanglement sources are expected to be an important resource for scalable quantum networking. KTP waveguides offer unique dispersion properties which enable the production of high spectral purity SPDC photons in the telecom C-band. We present a high rate, high fidelity, high spectral purity near-degenerate polarization entangled photon source produced via a dual-element, single-pass fully fiber-coupled PPKTP waveguide. The source was first characterized for CW entanglement generation and achieved both HV (horizontal/vertical) and DA (diagonal/antidiagonal) polarization basis visibilities of >95% with a pair rate of >5 MHz/mW. Additionally, the joint spectral intensity of the generated SPDC photons was characterized with a variety of pulsed pump parameters to achieve a spectral purity of >90%. When pumped at the pulse duration, corresponding to max spectral purity, the entanglement fidelity (with respect to the target Bell state) measured >94%. High entanglement fidelity of the SPDC photons is achieved by phase and timing compensation of the generated SPDC photons at the output of the module by means of a Soleil-Babinet compensator and PM1550 fiber. This work aids in reducing the complexity, size, weight and optical power required for polarization entangled photon sources thus simplifying their deployment in fielded quantum network nodes.
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