Emission of photon echoes in a strongly scattering medium

TL;DR

This paper demonstrates photon echo emission in a scattering powder, showing coherent atomic excitation across grains, which could accelerate material development and advance studies of coherent propagation in scattering media.

Contribution

It presents the first observation of photon echoes in a scattering powder, revealing coherent collective emission across multiple grains, a novel approach in the field.

Findings

Photon echoes observed in a scattering powder.

Coherent atomic excitation across multiple grains.

Potential for faster material development and new insights into scattering media.

Abstract

We observe the two- and three-pulse photon echo emission from a scattering powder, obtained by grinding a Pr$^{3+}$:Y$_2$SiO$_5$ rare earth doped single crystal. We show that the collective emission is coherently constructed over several grains. A well defined atomic coherence can therefore be created between randomly placed particles. Observation of photon echo on powders as opposed to bulk materials opens the way to faster material development. More generally, time-domain resonant four-wave mixing offers an attractive approach to investigate coherent propagation in scattering media.