Realization of high-fidelity perfect entangler between remote superconducting quantum processors

TL;DR

This paper demonstrates high-fidelity entangling gates between remote superconducting qubits over 30 cm, using standing-wave modes in coaxial cables, advancing scalable distributed quantum computing.

Contribution

It presents the first realization of high-fidelity perfect entanglers between remote superconducting quantum processors over a significant distance.

Findings

Achieved CNOT fidelity of 99.15%

Achieved CZ fidelity of 98.04%

Demonstrated efficient remote entanglement over 30 cm

Abstract

Superconducting qubits, a promising candidate for universal quantum computing, currently face limitations in chip size due to reproducibility, wiring complexity, and packaging modes. Distributed quantum modules offer a viable strategy for constructing larger quantum information processing systems, though universal quantum gate operations between remote qubits have yet to be realized. Here, we demonstrate high-fidelity perfect entanglers between two remote superconducting quantum devices over 30 cm distance, leveraging the standing-wave modes in the coaxial cable connecting them. We achieve cross-entropy benchmarking (XEB) fidelities of $(99.15 \pm 0.02)\%$ and $(98.04 \pm 0.04)\%$ for CNOT and CZ gates, respectively, which are more efficient and universal than existing state transfer or feedback-based protocols. This advancement significantly enhances the feasibility of universal distributed quantum information processing, essential for the future development of large-scale quantum systems.