Generation of light with multimode time-delayed entanglement using storage in a solid state spin-wave quantum memory

TL;DR

This paper demonstrates the generation and storage of entanglement in a solid state spin-wave quantum memory using rephased amplified spontaneous emission, showing multimode capabilities and potential for scalable quantum networks.

Contribution

It introduces a method to generate and store entanglement in a solid state quantum memory using RASE, with demonstrated multimode operation and preservation of entanglement for several microseconds.

Findings

Entanglement generated between ensemble and output light.

Stored entanglement preserved for up to 5 microseconds.

Achieved near-perfect distinguishability between temporal modes.

Abstract

Here we demonstrate generating and storing entanglement in a solid state spin-wave quantum memory with on-demand read out using the process of rephased amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE), resulting from an inverted ensemble of Pr$^{3+}$ ions doped into a Y$_2$SiO$_5$ crystal, generates entanglement between collective states of the praseodymium ensemble and the output light. The ensemble is then rephased using a four-level photon echo technique. Entanglement between the ASE and its echo is confirmed and the inseparability violation preserved when the RASE is stored as a spin-wave for up to 5 $\mu$s. RASE is shown to be temporally multimode with almost perfect distinguishability between two temporal modes demonstrated. These results pave the way for the use of multimode solid state quantum memories in scalable quantum networks.