Optimising the Efficiency of a Quantum Memory based on Rephased Amplified Spontaneous Emission

Abstract

We studied the recall efficiency as a function of optical depth of rephased amplified spontaneous emission (RASE), a protocol for generating entangled light. The experiments were performed on the ${}^3{H}_4$ $\to$ ${}^1{D}_2$ transition in the rare-earth doped crystal Pr${}^{3+}$:Y${}_2$SiO${}_5$, using a four-level echo sequence between four hyperfine levels to rephase the emission. Rephased emission was observed for optical depths in the range of $\alpha L$ = 0.8 to 2.0 with a maximum rephasing efficiency of 14 % observed while incorporating spin storage. This efficiency is a significant improvement over the previously reported non-classical result but is well short of the predicted efficiency. We discuss the possible mechanisms limiting the protocol's performance, and suggest ways to overcome these limits.

5 pages, 5 figures

References in corpus (3)

• The Quantum Internet
• Cavity-enhanced storage in an optical spin-wave memory
• Multi-mode and long-lived quantum correlations between photons and spins in a crystal

Cited by in corpus (3)

• Quantum networks using rare-earth ions
• Nonclassical photon-pair source based on noiseless photon echo
• Electromagnetically-induced transparency assists the Raman gradient echo memory at moderate detuning, dependent on gradient order