Single-Step High-Fidelity Three-Qubit Gates by Anisotropic Chiral Interactions

Direct multiqubit gates are becoming critical to facilitate quantum computations in near-term devices by reducing the gate counts and circuit depth. Here, we demonstrate that fast and high-fidelity three-qubit gates can be realized in a single step by leveraging small anisotropic and chiral three-qubit interactions. These ingredients naturally arise in state-of-the-art spin-based quantum hardware through a combination of spin-orbit interactions and orbital magnetic fields. These interactions resolve the key synchronization issues inherent in protocols relying solely on two-qubit couplings, which significantly limit gate fidelity. We confirm with numerical simulations that our single-step three-qubit gate can outperform existing protocols, potentially achieving infidelity <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo>≤</a:mo><a:mspace width="0.2em"/><a:msup><a:mn>10</a:mn><a:mrow><a:mo>−</a:mo><a:mn>4</a:mn></a:mrow></a:msup></a:math> in 80–100 ns under current experimental conditions. To further benchmark its performance, we also propose an alternative composite three-qubit gate sequence based on anisotropic two-qubit interactions with built-in echo sequence and show that the single-step protocol can outperform it, making it highly suitable for near-term quantum processors.