Chiral current in Floquet cavity magnonics

Floquet engineering can induce complex collective behavior and an interesting synthetic gauge field in quantum systems through temporal modulation of the system parameters by periodic drives. Using a Floquet drive on frequencies of the magnon modes, we realize a chiral state transfer in a cavity-magnonic system. The time-reversal symmetry is broken in such a promising platform for coherent information processing. In particular, the photon mode is adiabatically eliminated in the large-detuning regime and the magnon modes under conditional longitudinal drives can be indirectly coupled to each other with a phase-modulated interaction. The effective Hamiltonian is then used to generate chiral currents in a circular loop, whose dynamics is evaluated to measure the symmetry of the system Hamiltonian. Beyond the dynamics limited in the manifold with a fixed number of excitations, our protocol applies to continuous-variable systems with arbitrary states. Also, it is found to be robust against systematic errors in the photon-magnon coupling strength and Kerr nonlinearity.