Single-Qubit Gates with Errors at the 10^{-7} Level

Area of Science:

• Quantum Computing
• Atomic Physics
• Quantum Information Science

Background:

• Trapped-ion qubits are promising platforms for quantum computation.
• Achieving high-fidelity single-qubit gates is crucial for scalable quantum computers.
• Minimizing errors from decoherence, leakage, and measurement is essential.

Purpose of the Study:

• To demonstrate single-qubit gates with sub-part-per-million error rates.
• To investigate the trade-off between gate speed and fidelity in a trapped-ion system.
• To identify and quantify dominant error sources in the qubit operations.

Main Methods:

• Utilized a ^{43}Ca^{+} hyperfine clock qubit in a surface-electrode trap.
• Employed chip-integrated microwave resonators for electronic qubit control.
• Explored gate times ranging from 4.4 to 35 microseconds.

Main Results:

• Achieved single-qubit gates with error rates below 1.5(4)×10^{-7} per Clifford gate.
• Suppressed calibration errors to below 10^{-8}.
• Identified qubit decoherence (T_{2}≈70s), leakage, and measurement as primary error sources.

Conclusions:

• Single-qubit gates with unprecedented fidelity have been realized in a trapped-ion system.
• The experimental setup operates at room temperature without magnetic shielding.
• Further improvements require addressing decoherence, leakage, and measurement errors for advanced quantum computing.