Efficient single sideband microwave to optical conversion using an electro-optical whispering gallery mode resonator

TL;DR

This paper demonstrates a highly efficient single sideband microwave-to-optical conversion using a whispering gallery mode resonator, significantly advancing quantum communication technology by enabling coherent, low-loss signal conversion.

Contribution

It introduces a novel triply resonant whispering gallery mode resonator that achieves true single sideband conversion with three orders of magnitude improved efficiency over previous methods.

Findings

Achieved 0.1% photon number conversion efficiency at 10 GHz

Demonstrated conversion bandwidth larger than 1 MHz

Compatible with superconducting quantum circuits

Abstract

Linking classical microwave electrical circuits to the optical telecommunication band is at the core of modern communication. Future quantum information networks will require coherent microwave-to-optical conversion to link electronic quantum processors and memories via low-loss optical telecommunication networks. Efficient conversion can be achieved with electro-optical modulators operating at the single microwave photon level. In the standard electro-optic modulation scheme this is impossible because both, up- and downconverted, sidebands are necessarily present. Here we demonstrate true single sideband up- or downconversion in a triply resonant whispering gallery mode resonator by explicitly addressing modes with asymmetric free spectral range. Compared to previous experiments, we show a three orders of magnitude improvement of the electro-optical conversion efficiency reaching 0.1% photon number conversion for a 10GHz microwave tone at 0.42mW of optical pump power. The presented scheme is fully compatible with existing superconducting 3D circuit quantum electrodynamics technology and can be used for non-classical state conversion and communication. Our conversion bandwidth is larger than 1MHz and not fundamentally limited.