Telecom networking with a diamond quantum memory

TL;DR

This paper demonstrates a low-noise, bidirectional quantum frequency conversion system that enables a diamond-based quantum memory to interface directly with telecom-band systems, facilitating scalable quantum networks.

Contribution

It introduces a novel quantum frequency conversion technique that maintains low noise and high indistinguishability, enabling direct integration of solid-state quantum memories with telecom channels.

Findings

Successful conversion of single photons from visible to telecom band with low noise

High indistinguishability of converted photons ($V=89 ext{ extpm}8 ext{ extperthousand}$)

Quantum state transfer over 50 km fiber with 87 ext{ extpm}2.5 ext{ extperthousand} fidelity

Abstract

Practical quantum networks require interfacing quantum memories with existing channels and systems that operate in the telecom band. Here we demonstrate low-noise, bidirectional quantum frequency conversion that enables a solid-state quantum memory to directly interface with telecom-band systems. In particular, we demonstrate conversion of visible-band single photons emitted from a silicon-vacancy (SiV) center in diamond to the telecom O-band, maintaining low noise ($g^2(0)<0.1$) and high indistinguishability ($V=89\pm8\%$). We further demonstrate the utility of this system for quantum networking by converting telecom-band time-bin pulses, sent across a lossy and noisy 50 km deployed fiber link, to the visible band and mapping their quantum states onto a diamond quantum memory with fidelity $\mathcal{F}=87\pm 2.5 \% $. These results demonstrate the viability of SiV quantum memories integrated with telecom-band systems for scalable quantum networking applications.