Experimental realization of light with time separated correlations by rephasing amplified spontaneous emission

TL;DR

This paper demonstrates that amplified spontaneous emission in a solid-state system can be rephased to produce a coherent echo, revealing potential quantum correlations such as entanglement.

Contribution

It introduces a method to generate and rephase amplified spontaneous emission in a solid, showing evidence of entanglement at small optical thicknesses.

Findings

Rephasing of amplified spontaneous emission produces a coherent echo.

Evidence of entanglement between emission and echo at low optical thickness.

Demonstrates a new way to control noise in optical systems.

Abstract

Amplified spontaneous emission is a common noise source in active optical systems, it is generally seen as being an incoherent process. Here we excite an ensemble of rare earth ion dopants in a solid with a {\pi}-pulse, resulting in amplified spontaneous emission. The application of a second {\pi}-pulse leads to a coherent echo of the amplified spontaneous emission that is correlated in both amplitude and phase. For small optical thicknesses, we see evidence that the amplified spontaneous emission and its echo are entangled.