Floquet-engineering magnonic NOON states with performance improved by soft quantum control

We present a high-performance scheme of soft quantum control to deterministically generate entangled NOON states between two magnon modes. A superconducting qubit is considered as a data bus coupled to two magnon modes and a circuit resonator that accounts for providing an N-photon Fock state. Assisted by the Floquet engineering, effective couplings among the photon mode in the resonator and two magnon modes are constructed and can induce a chiral Fock-state transfer from the photon mode to one magnon mode, for which the magnonic Fock-state receiver mode is dependent of the qubit state. Therefore, a superposed qubit state can exactly lead to a magnonic NOON state. Compared with the recent scheme of generating magnonic NOON states (Qi and Jing in Phys Rev A 107:013702, 2023) that uses constant effective couplings, the present scheme designs Gaussian-type soft control of effective couplings, which observably improves the fidelity and robustness of generating the magnonic NOON state.

Automated summary

We present a high-performance scheme of soft quantum control to deterministically generate entangled NOON states between two magnon modes. With the assistance of Floquet engineering, effective couplings among the photon mode and two magnon modes are constructed, and a superconducting qubit is used as a data bus to provide an N-photon Fock state.