Microwave-to-optics conversion using a mechanical oscillator in its quantum groundstate

Understand

Conversion between signals in the microwave and optical domains is of great interest both for classical telecommunication, as well as for connecting future superconducting quantum computers into a global quantum network.

• For quantum applications, the conversion has to be both efficient, as well as operate in a regime of minimal added classical noise.
• While efficient conversion has been demonstrated using mechanical transducers, they have so far all operated with a substantial thermal noise background.
• Here, we overcome this limitation and demonstrate coherent conversion between GHz microwave signals and the optical telecom band with a thermal background of less than one phonon.