Resource-efficient fault-tolerant one-way quantum repeater with code concatenation

One-way quantum repeaters that use quantum error-correcting codes can overcome loss and operational errors to enable fast, reliable qubit transmission. Minimizing resources such as qubits per node and operational complexity is critical for near-term implementation. This work proposes a resource-efficient, fault-tolerant one-way quantum repeater using code concatenation: a loss-tolerant photonic tree-cluster code as an inner code and a 5‑qubit code as an outer code to protect against Pauli errors. Using flag-based stabilizer measurements and interspersed repeater nodes specialized for either loss or operational errors, the architecture can bridge intercontinental distances up to 10,000 km with minimized resource overhead. The results show that tailored error-correcting codes can substantially reduce experimental requirements for long-distance quantum communication.