Improving qubit fidelity from > 99.99% to > 99.999% and evaluating background noise effects in Si/SiGe

Silicon quantum dots provide a promising platform for spin-based quantum computing with high-fidelity qubits. Achieving high-fidelity qubit operation is a crucial prerequisite for realizing fault-tolerant computation and helps reduce the qubit overhead required for logical operations.

Recently, we achieved fidelities exceeding 99.99% in isotopically purified 28Si/SiGe quantum dots by carefully calibrating gate pulse errors and optimizing the microwave burst time window to minimize crosstalk between qubits. We identified the remaining limiting factors as background charge noise and magnetic noise. In this talk, I will discuss possible approaches to further improve the fidelity beyond 99.999%.