Reducing noise in single-photon-level frequency conversion

TLDR

The study demonstrates low‑noise, efficient frequency conversion via sum‑frequency mixing in a periodically poled LiNbO₃ waveguide and discusses its implications for single‑photon upconversion detection and quantum information. The conversion is achieved by sum‑frequency mixing in a PPLN waveguide with careful spectral filtering to suppress noise. Using a 1556 nm pump, 1302 nm photons are converted to 709 nm with 70 % internal and over 50 % external efficiency, achieving 600 noise counts per second at peak conversion under continuous‑wave pumping.

Abstract

We demonstrate low-noise and efficient frequency conversion by sum-frequency mixing in a periodically poled LiNbO(3) (PPLN) waveguide. Using a 1556 nm pump, 1302 nm photons are efficiently converted to 709 nm photons. We obtain 70% conversion efficiency in the PPLN waveguide and >50% external conversion efficiency with 600 noise counts per second at peak conversion with continuous-wave pumping. We simultaneously achieve low noise and high conversion efficiency by careful spectral filtering. We discuss the impact of low-noise frequency translation on single-photon upconversion detection and quantum information applications.