Deterministic generation of multiqubit entangled states among distant parties using indefinite causal order
Phys. Rev. Applied 23, 054075 – Published 27 May, 2025
DOI: https://doi.org/10.1103/PhysRevApplied.23.054075
Abstract
Quantum entanglement plays an irreplaceable role in various remote quantum information-processing tasks. Here, we present protocols for generating deterministic and heralded -qubit entangled states across multiple network nodes. By utilizing a preshared maximally entangled state and single-qubit operations within an indefinite-causal-order framework, the multiqubit entangled state between distant parties can be generated deterministically. The complex entangled-state measurements and multiple preshared entangled states, are essential in conventional entanglement-swapping techniques but are not required in our approach. This greatly reduces the complexity of the quantum circuit and makes it more experimentally feasible. Furthermore, we develop optical architectures to implement these protocols by encoding qubits in polarization degrees of freedom. The results indicate that our protocols significantly improve the efficiency of long-distance entanglement generation and provide a practical framework for establishing large-scale quantum networks.
