Theory of Microwave-Optical Conversion Using Rare-Earth Ion Dopants

TL;DR

This paper presents a theoretical model for a microwave-to-optical photon converter using rare-earth ion dopants, predicting over 80% efficiency with current experimental setups, advancing quantum information technologies.

Contribution

The authors develop a comprehensive quantum model for a microwave-optical converter employing rare-earth ions, including numerical simulations and a simplified efficiency-predicting model.

Findings

Conversion efficiency above 80% is achievable with existing technology.

The model accounts for inhomogeneous broadening and cavity interactions.

Numerical simulations validate the theoretical predictions.

Abstract

We develop a theoretical description of a device for coherent conversion of microwave to optical photons. For the device, dopant ions in a crystal are used as three-level systems, and interact with the fields inside overlapping microwave and optical cavities. We develop a model for the cavity fields interacting with an ensemble of ions, and model the ions using an open quantum systems approach, while accounting for the effect of inhomogeneous broadening. Numerical methods are developed to allow us to accurately simulate the device. We also further develop a simplified model, applicable in the case of small cavity fields which is relevant to quantum information applications. This simplified model is used to predict the maximum conversion efficiency of the device. We investigate the effect of various parameters, and predict that conversion efficiency of above 80% should be possible with currently existing experimental setups inside a dilution refrigerator.