Continuous and Time-Domain Coherent Signal Conversion between Optical and Microwave Frequencies

Converting seamlessly between optical and microwave frequencies would enable ultralow-loss long-distance communication of both classical and quantum signals, and could enable a quantum telecommunication repeater. High conversion rates with low loss are needed for any practical technology. The authors present a significant step toward both of those goals: an integrated electromechanical and optomechanical design that yields significantly lower loss with megahertz conversion rates, which is promising for future bidirectional quantum communication. Their design includes a number of innovations for generating and transmitting the rf acoustic signals that are key to device operation.