Cryogenic integrated spontaneous parametric down-conversion

Scalable quantum photonics relies on interfacing many optical components under mutually compatible operating conditions. To that end, we demonstrate that spontaneous parametric down-conversion (SPDC) in nonlinear waveguides, a standard technology for generating entangled photon pairs, squeezed states, and heralded single photons, is fully compatible with cryogenic operating conditions required for superconducting detectors. This is necessary for the proliferation of integrated quantum photonics in integration platforms exploiting quasiphase-matched second-order nonlinear interactions. We investigate how cryogenic operation at 4 K affects the SPDC process by comparing the heralding efficiency, second-order correlation function, and spectral properties with operation at room temperature. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

In this study, researchers demonstrate that spontaneous parametric down-conversion (SPDC) in nonlinear waveguides is fully compatible with the cryogenic operating conditions required for superconducting detectors. By comparing the performance indicators at low temperature and room temperature, they investigate the effect of low temperature on the SPDC process.