Charge-noise spectroscopy using exchange oscillations in Si/SiGe spin qubits

Electron spins in silicon quantum dots are a promising qubit platform due to their long coherence times, small footprint, and compatibility with industrial fabrication. Recent advances with isotopically purified silicon and heterostructure quality have enabled single-qubit and two-qubit fidelities beyond the threshold for fault-tolerant operation, limited by charge-noise in the host semiconductor. We measure the charge-noise spectrum in a Si/SiGe singlet-triplet qubit on Intel’s latest testchip [1], over nearly 11 decades of frequency using exchange oscillations biased in the detuning-sensitive regime. Dynamically decoupling low-frequency noise with up to 128 π-pulses [2] enables the design of filter functions to probe charge-noise at tens of MHz, revealing a 1/f spectrum over the entire frequency range of our measurements. The charge-noise spectrum provides key insights for evaluating heterostructure quality, fabrication process flows, and developing noise mitigation strategies, including dynamically corrected gates for suppressed noise sensitivity and higher single and two-qubit fidelities.

1. Neyens, S., Zietz, O., et al. arXiv:2307.04812

2. Connors, E.J., et al. Nat. Commun. 13, 940 (2022)