Ultrafast switchable spin-orbit coupling for silicon spin qubits via spin valves

Synthetic spin-orbit coupling (SOC) has achieved significant advancements in silicon-based electron spin qubits, positioning it as a promising platform for quantum computation. However, SOC also introduces challenges in coherence and quantum information exchange. To address these challenges and achieve practical scalability, on-demand switchable SOC is crucial. Yet, it remains underexplored due to the nonvolatility of micromagnets. Spin valves, which are known for their ultrafast magnetization switching and have been primarily used in magnetic storage, offer a potential solution. In this paper, we propose an alternative approach by utilizing the stray field of spin valves to enable switchable SOC in silicon. This switchable architecture provides a larger coherent region for spin arrays. It also makes long-sought coherent information exchange via swap operations and resonant quantum state transfer (QST) easily surpasses the fault-tolerance threshold when considering realistic experimental parameters. By leveraging these advantages, we have developed a modular quantum chip that successfully integrates the operation, coherence, and scalability of spin qubits. Combined with recent experimental advancements in spin qubits and spin valves, our proposal demonstrates high feasibility for large-scale silicon quantum computation.