Fidelity benchmarks for two-qubit gates in silicon.

Area of Science:

• Quantum Information Science
• Solid-State Quantum Computing
• Quantum Error Correction

Background:

• Universal quantum computation necessitates scalable qubit platforms and high-fidelity gate operations for error correction.
• Superconducting qubits are the only solid-state qubits demonstrating two-qubit fidelities near the fault-tolerance threshold.
• Silicon quantum dot qubits offer scalability via standard lithography and achieve high single-qubit fidelities.

Purpose of the Study:

• To accurately assess the fidelities of two-qubit gates in silicon quantum dot qubits using Clifford-based randomized benchmarking.
• To demonstrate the potential of silicon-based qubits for scalable quantum computation.

Main Methods:

• Encoding qubits on electron spin states within gate-defined silicon quantum dots.
• Performing Bell state tomography to evaluate two-qubit gate fidelity.
• Utilizing two-qubit randomized benchmarking to measure average Clifford and controlled-rotation gate fidelities.

Main Results:

• Bell state tomography yielded fidelities between 80% and 89%.
• Average Clifford gate fidelity reached 94.7% via randomized benchmarking.
• Average controlled-rotation fidelity was measured at 98%.

Conclusions:

• The achieved fidelities are currently limited by gate operation times relative to qubit decoherence times.
• Future silicon qubit designs incorporating faster gate operations and advanced pulsing techniques are expected to significantly enhance fidelities.
• These advancements position silicon quantum dots as a promising platform for scalable, fault-tolerant quantum computation.