Crystal and cavity combine into wavelength converter

Uniting microwave quantum technology, which operates at microwave wavelengths, and optical quantum technology, which operates at telecom wavelengths, would benefit both subfields. Linking the two through a microwave-to-telecom wavelength transducer takes a step toward hybrid quantum technologies and can help create quantum communication channels required for a quantum internet.

While microwave-to-telecom transduction has been explored via a myriad of methods, Ramp et al. are the first to demonstrate transduction using an optomechanical crystal in a 3D microwave cavity. The piezoelectric properties of the optomechanical crystal convert photons from the microwave cavity’s electrical field into high frequency mechanical motion, which can then be read out using the telecom mode of the optomechanical crystal.

Typically, capacitors, instead of a 3D microwave cavity, are used to directly drive optomechanical crystals.

“Microwave-to-telecom transduction is a critical part of the quantum toolbox,” said author Hugh Ramp. “The unique use of a 3D microwave cavity and a high frequency mechanical mode distinguishes our experiment as being uniquely suited for the creation of hybrid technology.”

The authors suggest that using a 3D microwave cavity could protect the transducer from outside noise as well as jumpstart the development of hybrid quantum systems, many of which already use 3D microwave cavities as a coupling mechanism.

Combining microwave cavities and optomechanical crystals offer a new way to explore hybrid quantum systems. For future work, the authors suggest replicating their experiment at cryogenic temperatures with a tunable superconducting microwave cavity, which could increase the transduction efficiency and frequency range. The authors plan to use the 3D microwave cavities to build a platform for superconducting qubit and magnon experiments.

Source: “Wavelength transduction from a 3D microwave cavity to telecom using piezoelectric optomechanical crystals,” by H. Ramp, T. J. Clark, B. D. Hauer, C. Doolin, K. C. Balram, K. Srinivasan, and J. P. Davis, Applied Physics Letters (2020). The article can be accessed at https://doi.org/10.1063/5.0002160 .