Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre

TL;DR

This paper demonstrates the first quantum memory for entangled telecom-wavelength photons in an erbium-doped optical fibre, advancing fibre-based quantum networks despite current efficiency and storage time limitations.

Contribution

It presents a novel fibre-based quantum memory for entangled photons at telecom wavelengths using erbium-doped fibre and photon-echo protocol, a first in the field.

Findings

Successful storage and recall of entangled photons at 1532 nm

First implementation of quantum memory in erbium-doped fibre at telecom wavelength

Potential for integration into quantum communication networks

Abstract

The realization of a future quantum Internet requires processing and storing quantum information at local nodes, and interconnecting distant nodes using free-space and fibre-optic links. Quantum memories for light are key elements of such quantum networks. However, to date, neither an atomic quantum memory for non-classical states of light operating at a wavelength compatible with standard telecom fibre infrastructure, nor a fibre-based implementation of a quantum memory has been reported. Here we demonstrate the storage and faithful recall of the state of a 1532 nm wavelength photon, entangled with a 795 nm photon, in an ensemble of cryogenically cooled erbium ions doped into a 20 meter-long silicate fibre using a photon-echo quantum memory protocol. Despite its currently limited efficiency and storage time, our broadband light-matter interface brings fibre-based quantum networks one step closer to reality. Furthermore, it facilitates novel tests of light-matter interaction and collective atomic effects in unconventional materials.