Quantum-Referenced Spontaneous Emission Tomography

TL;DR

This paper introduces quantum-referenced spontaneous emission tomography (Q-SpET), a novel method for characterizing the joint spectral phase of photon pairs emitted from uncharacterized sources using quantum interference.

Contribution

The paper presents a new quantum tomography technique that measures the joint spectral phase of photon pairs via quantum interference, applicable to integrated photonic sources.

Findings

Photon pairs from micro-ring resonators differ from stimulated emission.

Q-SpET accurately characterizes the joint spectral phase of photon pairs.

Classical stimulated emission tomography cannot fully characterize such sources.

Abstract

We present a method of tomography that measures the joint spectral phase (JSP) of spontaneously emitted photon pairs originating from a largely uncharacterized ``target" source. We use quantum interference between our target source and a reference source to extract the JSP with four spectrally resolved measurements, in a process that we call quantum-referenced spontaneous emission tomography (Q-SpET). We have demonstrated this method on a photonic integrated circuit for a target micro-ring resonator photon-pair source. Our results show that spontaneously emitted photon pairs from a micro-ring resonator are distinctively different from that of stimulated emission, and thus cannot in general be fully characterized using classical stimulated emission tomography without detailed knowledge of the source.