Cavity-enhanced spectroscopy of a few-ion ensemble in Eu3+:Y2O3

TL;DR

This paper demonstrates cavity-enhanced spectroscopy of a few europium ions in a nanocrystal, showing increased fluorescence and potential for quantum communication applications.

Contribution

It introduces a method to couple single europium-doped nanocrystals to a fiber microcavity and performs cavity-enhanced spectroscopy under cryogenic conditions.

Findings

Observed strong correlation between emission lifetime and brightness.

Quantified scattering loss and deduced crystal size.

Detected fluorescence from few ions with Purcell enhancement.

Abstract

We report on the coupling of the emission from a single europium-doped nanocrystal to a fiber-based microcavity under cryogenic conditions. As a first step, we study the sample properties and observe a strong correlation between emission lifetime and brightness, as well as a lifetime reduction for nanocrystals embedded in a polymer film. This is explained by differences in the local density of states. We furthermore quantify the scattering loss of a nanocrystal inside the cavity and use this to deduce the crystal size. Finally, by resonantly coupling the cavity to a selected transition, we perform cavity-enhanced spectroscopy to measure the inhomogeneous linewidth, and detect the fluorescence from an ensemble of few ions in the regime of power broadening. We observe an increased fluorescence rate consistent with Purcell enhancement. The results represent an important step towards the efficient readout of single rare-earth ions with excellent optical and spin coherence properties, which is promising for applications in quantum communication and distributed quantum computation.