Realization of High-Fidelity Perfect Entanglers between Remote Superconducting Quantum Processors

Superconducting qubit systems, one of the leading candidates for universal quantum computing, face scalability challenges such as frequency crowding, wiring complexity, and packaging problems. Distributed quantum computing offers a viable strategy for constructing larger quantum information processing systems. Yet, direct universal quantum gates between remote qubits-critical to distributed architectures-remain unrealized. Here, we demonstrate direct high-fidelity entangling gates between two remote superconducting quantum processors separated by a 30 cm distance, utilizing standing-wave modes in their connecting coaxial cable. We achieve cross-entropy benchmarking fidelities of (99.15±0.02)% and (98.03±0.04)% for the controlled-not and controlled-z gates, respectively, outperforming state transfer and feedback-based protocols in fidelity and efficiency. This advancement significantly enhances the prospect of universal distributed quantum information processing, which is the critical step toward future large-scale quantum systems.