Simultaneous nonreciprocal and ultra-strong coupling in cavity magnonics

TL;DR

This paper demonstrates the simultaneous achievement of nonreciprocal coupling and ultra-strong coupling in cavity magnonics by using a yttrium iron garnet cylinder, enabling advanced nonreciprocal devices for quantum and microwave technologies.

Contribution

It introduces a novel experimental setup that combines nonreciprocal and ultra-strong coupling in cavity magnonics, advancing the development of hybrid quantum devices.

Findings

Achieved an ultra-strong coupling strength of 1.18 GHz.

Observed nonreciprocal microwave transmission within the photonic bandgap.

Demonstrated breaking of time-reversal symmetry via gyromagnetic and Faraday effects.

Abstract

We demonstrate the simultaneous realization of nonreciprocal coupling and ultra-strong coupling in cavity magnonics. By replacing a copper cylinder with a yttrium iron garnet cylinder within the photonic crystal, we achieve an ultra-strong coupling strength of 1.18 GHz and a coupling efficiency of 10.9%. Nonreciprocal microwave transmission emerges within the photonic bandgap, due to the breaking of time-reversal symmetry through the gyromagnetic and Faraday effects. This work establishes a foundation for advanced nonreciprocal devices in hybrid cavity magnonic systems, with promising applications in quantum information processing and microwave isolation.