Nonreciprocal reconfigurable microwave optomechanical circuit

TLDR

Nonreciprocal microwave devices are essential for radar, radio communication, and superconducting quantum readout, yet conventional ferrite-based designs require bulky magnetic fields, prompting interest in magnetic‑field‑free on‑chip alternatives such as Josephson‑nonlinearity circuits. The authors aim to realize reconfigurable nonreciprocal transmission between two microwave modes using purely optomechanical interactions in a superconducting electromechanical circuit. Their scheme employs interference between two mechanical modes to couple the microwave cavities without a magnetic field, and they analyze the resulting isolation, transmission, and noise properties. The results show that this principle enables quantum‑limited circulators, directional amplifiers, and offers a foundation for realizing topological states of light and sound.

Abstract

Abstract Nonreciprocal microwave devices are ubiquitous in radar and radio communication and indispensable in the readout chains of superconducting quantum circuits. Since they commonly rely on ferrite materials requiring large magnetic fields that make them bulky and lossy, there has been significant interest in magnetic-field-free on-chip alternatives, such as those recently implemented using the Josephson nonlinearity. Here, we realize reconfigurable nonreciprocal transmission between two microwave modes using purely optomechanical interactions in a superconducting electromechanical circuit. The scheme relies on the interference in two mechanical modes that mediate coupling between the microwave cavities and requires no magnetic field. We analyse the isolation, transmission and the noise properties of this nonreciprocal circuit. Finally, we show how quantum-limited circulators can be realized with the same principle. All-optomechanically mediated nonreciprocity demonstrated here can also be extended to directional amplifiers, and it forms the basis towards realizing topological states of light and sound.