Heralded and robust W-state generation for distant superconducting qubits with practical microwave pulse scattering

Abstract

Nonlocal multipartite entanglement holds significant potential for both fundamental physics and practical applications. We present a robust protocol for generating remote entanglement, specifically W states, among multiple nonlocal superconducting qubits. Our protocol employs practical microwave pulse scattering through a microwave cavity, which is coupled to a far-detuned superconducting transmon qubit, facilitating a CNOT-like operation. Our approach can be implemented without the need for single microwave-photon sources and its completion is heralded by microwave photon measurements. Furthermore, our protocol can generate faithful nonlocal W states of distant superconducting qubits with practical detector units, each cascading two quantum non-demolition detectors, rather than ideal single-photon detectors. These distinct features make our protocol particularly useful for large quantum secure communication networks.