Composite pulses for robust universal control of singlet-triplet qubits

Area of Science:

• Quantum Computing
• Quantum Information Science
• Semiconductor Physics

Background:

• Precise qubit manipulation is crucial for quantum computing but is hindered by environmental noise and stray couplings.
• Existing error correction methods are often unsuitable for specific qubit systems like the singlet-triplet spin qubit.

Purpose of the Study:

• To develop novel theoretical methods for correcting errors caused by magnetic field gradient fluctuations in singlet-triplet spin qubits.
• To address the limitations of experimental control over qubit manipulation in semiconductor quantum dots.

Main Methods:

• Theoretical modeling of error correction techniques for singlet-triplet spin qubits.
• Design of simple electrical pulse sequences tailored to the constraints of the experimental system.
• Analysis of error cancellation up to sixth order for small gradients and leading order for large gradients.

Main Results:

• Demonstrated the first theoretical progress in correcting magnetic field gradient errors for singlet-triplet spin qubits.
• Developed pulse sequences that perform z-axis rotations while mitigating errors under strong experimental constraints.
• Achieved arbitrary rotations with leading error cancellation for large gradients.

Conclusions:

• The proposed electrical pulse sequences offer a viable strategy for enhancing qubit control precision in semiconductor quantum dots.
• This work overcomes limitations in qubit manipulation control, paving the way for more robust quantum computations.
• The findings are significant for advancing the development of fault-tolerant quantum computers.