Simultaneously achieving fidelity, robustness, and scalability in multi-qubit gate implementations

Determine architectures and control strategies for multi-qubit quantum gate implementations that simultaneously achieve high fidelity, robustness, and scalability under realistic experimental constraints such as operational complexity and limited coherence times.

Background

The paper surveys progress on multi-qubit gates across superconducting circuits, trapped ions, photonics, quantum dots, and neutral atoms, noting substantial advances but emphasizing that no approach has yet simultaneously realized all three key attributes: high fidelity, robustness, and scalability.

This open problem motivates the authors’ hybrid molecule–Rydberg-atom scheme, which leverages long-lived molecular ground states and strong, tunable Rydberg interactions to seek improved performance and scalability for multipartite CNOT operations.

References

Despite these advances, achieving simultaneously high fidelity, robustness, and scalability remains an open problem.

— Multipartite controlled-NOT gates using molecules and Rydberg atoms  (2603.29349 - Bai et al., 31 Mar 2026) in Introduction

Despite these intrinsic advantages, scaling fluxonium-based processors beyond linear or minimal-connectivity configurations remains an open engineering problem, limited by the lack of a coupling scheme that simultaneously suppresses residual qubit-qubit interactions during idling and while executing single-qubit operations and supports high-fidelity two-qubit operations without spurious spectator errors.

— High-Fidelity Entangled States in a Connectivity-Four Fluxonium Quantum Processor  (2608.25503 - Schirk et al., 26 Aug 2026) in Section 1, Introduction