Analytic treatment of CRIB Quantum Memories for Light using Two-level Atoms

TL;DR

This paper analytically demonstrates that optical gradient echo quantum memories using two-level atoms can achieve 100% efficiency through controlled inhomogeneous broadening and multiple switching, even in optically thin regimes.

Contribution

It provides an analytical framework showing the potential for perfect efficiency in CRIB quantum memories with controlled broadening and multiple switching.

Findings

Multiple switching achieves 100% retrieval efficiency

Analytical calculation confirms noise-free, perfect efficiency

Efficiency depends on optical depth and control protocols

Abstract

It has recently been discovered that the optical analogue of a gradient echo in an optically thick material could form the basis of a optical memory that is both completely efficient and noise free. Here we present analytical calculation showing this is the case. There is close analogy between the operation of the memory and an optical system with two beam splitters. We can use this analogy to calculate efficiencies as a function of optical depth for a number of quantum memory schemes based on controlled inhomogeneous broadening. In particular we show that multiple switching leads to a net 100% retrieval efficiency for the optical gradient echo even in the optically thin case.