Elimination of Noise in Optically Rephased Photon Echoes

TL;DR

This paper introduces a noiseless photon-echo protocol using a four-level atomic system, significantly improving quantum memory fidelity by eliminating spontaneous emission noise in photon echo processes.

Contribution

The work presents a novel noiseless photon-echo protocol implemented in a Eu3+:Y2SiO5 crystal, enabling high-fidelity quantum memory with spin-wave storage and easy operation.

Findings

Achieved a storage fidelity of 0.952 for time-bin qubits.

Demonstrated elimination of spontaneous emission noise in photon echoes.

Showed the protocol's applicability to other physical systems.

Abstract

Photon echo is a fundamental tool for the manipulation of electromagnetic fields. Unavoidable spontaneous emission noise is generated in this process due to the strong rephasing pulse, which limits the achievable signal-to-noise ratio and represents a fundamental obstacle towards their applications in the quantum regime. Here we propose a noiseless photon-echo protocol based on a four-level atomic system. We implement this protocol in a Eu3+:Y2SiO5bcrystal to serve as an optical quantum memory. A storage fidelity of 0.952 is obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity achievable using the classical measure-and-prepare strategy. In this work, the demonstrated noiseless photon-echo quantum memory features spin-wave storage, easy operation and high storage fidelity, which should be easily extended to other physical systems.