High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectors

TL;DR

This paper demonstrates a high-fidelity method for converting visible photons to telecommunication wavelengths using solid-state difference frequency generation, enabling faithful quantum information transfer with superconducting detectors.

Contribution

The authors experimentally achieve high-fidelity visible-to-telecommunication wavelength conversion using solid-state difference frequency generation and superconducting detectors, advancing quantum communication technologies.

Findings

Fidelity of 0.93 after wavelength conversion

Successful entanglement preservation between 780 nm and 1522 nm

Effective use of superconducting single-photon detectors

Abstract

We experimentally demonstrate a high-fidelity visible-to-telecommunication wavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 nm is converted to a 1522-nm photon, resulting in the entangled photon pair between 780 nm and 1522 nm. Using superconducting single-photon detectors with low dark count rates and small timing jitters, we selectively observed well-defined temporal modes containing the two photons. We achieved a fidelity of $0.93 \pm 0.04$ after the wavelength conversion, indicating that our solid-state-based scheme can be used for faithful frequency down-conversion of visible photons emitted from quantum memories composed of various media.