Realizing all-to-all couplings among detachable quantum modules using a microwave quantum state router

Abstract One of the primary challenges in realizing large-scale quantum processors is realization qubit couplings that balance interaction strength, connectivity, and mode confinement. Moreover, it very desirable for device elements to be detachable, allowing components built, tested, replaced independently. In this work, we present a microwave state router, centered on parametrically driven, Josephson-junction based three-wave mixing, realizes all-to-all among four detachable modules. We demonstrate coherent exchange all communication modes, with an average full- i SWAP time 764 ns inferred inter-module fidelity 0.969, limited by coherence. also photon transfer pairwise entanglement between module qubits, parallel operation simultaneous across router. Our router-module architecture serves as prototype modular computer has great potential enabling flexible, demountable, networks superconducting qubits cavities.