The new paper outlines the concept and presents a prototype device, which uses an optomechanical crystal implemented in a piezoelectric material in a way that is compatible with superconducting qubits, quantum analogs of classical bits. Operating the device at the single phonon limit, the scientists were able generate coherent interactions between electrical signals, very high frequency mechanical vibrations, and optical signals.
Although the first prototype of the transducer has not been operated in the quantum realm, that is, in fact, the next step for the research effort. "In this paper, we're characterizing the system using classical electrical and optical signals and find that the essential parameters look very promising," says Bochmann. "In the next step, we would have to actually input quantum signals from the electrical side and then check whether the quantum properties are preserved in the light."
According to the authors, their prototype transducer is fully compatible with superconducting quantum circuits and is well suited for cryogenic operation. "The coupled dynamics of the system should be the same at low temperatures as in our room temperature measurements, albeit with a lower thermal background," said co-author Andrew Cleland, a professor of physics and associate director of the California Nanosystems Institute at UCSB. "Genuine quantum features and non-classical mechanical states will emerge when we couple a superconducting qubit to the transducer.
"We believe that combining optomechanics with superconducting quantum devices will enable a new generation of on-chip quantum devices with unique capabilities, as well as opening an exciting pathway for realizing entangled networks of electronic and photonic quantum systems," Cleland said.