An 11-qubit atom processor in silicon.

Area of Science:

• Quantum Computing
• Atomic Physics
• Solid-State Systems

Background:

• Nuclear spins of phosphorus atoms in silicon offer long coherence times and high-fidelity control for quantum computing.
• Coupling multiple phosphorus atoms via hyperfine interaction enables multi-qubit control and small-scale quantum algorithms.
• Scaling quantum processors requires extending high-fidelity entanglement non-locally across multiple spin registers.

Purpose of the Study:

• To develop and demonstrate an 11-qubit atom processor capable of high-fidelity, non-local entanglement.
• To investigate the performance of interconnected nuclear spin registers for quantum information processing.
• To advance towards fault-tolerant quantum computation using atom processors.

Main Methods:

• Constructed an 11-qubit processor with two multi-nuclear spin registers linked by electron exchange interaction.
• Advanced calibration and control protocols to achieve high-fidelity single- and multi-qubit gates.
• Performed entanglement of local and non-local nuclear-spin pairs, including Greenberger-Horne-Zeilinger (GHZ) state generation.

Main Results:

• Achieved single- and multi-qubit gate fidelities ranging from 99.10% to 99.99%.
• Demonstrated state-of-the-art Bell-state fidelities up to 99.5% for various spin pair combinations.
• Generated GHZ states and showed entanglement of up to eight nuclear spins.

Conclusions:

• Established high-fidelity operation across interconnected nuclear spin registers.
• Realized a significant milestone towards scalable, fault-tolerant quantum computation with atom processors.
• The developed processor architecture and control methods are promising for future quantum technologies.