# Microwave-to-optical conversion via four-wave-mixing in a cold ytterbium ensemble

## TL;DR

This paper proposes a noise-free microwave-to-optical transducer using four-wave-mixing in cold ytterbium atoms, achieving about 50% efficiency and 100 kHz bandwidth, advancing quantum communication interfaces.

## Contribution

It introduces a novel scheme for microwave-to-optical conversion using Rydberg states in cold ytterbium, enabling high efficiency and noise suppression at the single-photon level.

## Key findings

- Predicted conversion efficiency of approximately 50%.
- Achieved bandwidth of around 100 kHz.
- Proposed continuous operation far detuned from intermediate states.

## Abstract

Interfacing superconducting qubits with optical photons requires noise-free microwave-to-optical transducers, a technology currently not realized at the single-photon level. We propose to use four-wave-mixing in an ensemble of cold ytterbium (Yb) atoms prepared in the metastable 'clock' state. The parametric process uses two high-lying Rydberg states for bidirectional conversion between a 10 GHz microwave photon and an optical photon in the telecommunication E-band. To avoid noise photons due to spontaneous emission, we consider continuous operation far detuned from the intermediate states. We use an input-output formalism to predict conversion efficiencies of $\approx50\%$ with bandwidths of $\approx100$ kHz.