Highly efficient frequency conversion with bandwidth compression of quantum light

TLDR

Hybrid quantum networks require efficient interfacing of disparate quantum nodes, yet no existing interface simultaneously achieves efficient bandwidth compression and substantial frequency translation. The study demonstrates an engineered sum‑frequency‑conversion process in lithium niobate that simultaneously achieves efficient bandwidth compression and substantial frequency translation. The authors implement a sum‑frequency‑conversion process in lithium niobate to compress bandwidth and translate frequency. The device converts telecom‑wavelength photons to the visible range, compressing bandwidth by 7.47× while preserving non‑classical statistics, achieves 61.5 % internal efficiency, and enables connections between previously incompatible quantum systems.

Abstract

Abstract Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.