Charge-noise spectroscopy of Si/SiGe quantum dots via dynamically-decoupled exchange oscillations

• Published in: Nature communications Vol. 13; no. 1; pp. 940 - 9
• Main Authors: Connors, Elliot J, Nelson, J, Edge, Lisa F, Nichol, John M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 17.02.2022; Nature Publishing Group UK; Nature Portfolio
• Subjects: Accuracy; Electron spin; Electrons; Fabrication; Frequency ranges; Noise; Noise control; Noise measurement; Oscillations; Quantum dots; Qubits (quantum computing); Silicon; Silicon germanides; Spectroscopy; Spectrum analysis
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-28519-x

Electron spins in silicon quantum dots are promising qubits due to their long coherence times, scalable fabrication, and potential for all-electrical control. However, charge noise in the host semiconductor presents a major obstacle to achieving high-fidelity single- and two-qubit gates in these devices. In this work, we measure the charge-noise spectrum of a Si/SiGe singlet-triplet qubit over nearly 12 decades in frequency using a combination of methods, including dynamically-decoupled exchange oscillations with up to 512 π pulses during the qubit evolution. The charge noise is colored across the entire frequency range of our measurements, although the spectral exponent changes with frequency. Moreover, the charge-noise spectrum inferred from conductance measurements of a proximal sensor quantum dot agrees with that inferred from coherent oscillations of the singlet-triplet qubit, suggesting that simple transport measurements can accurately characterize the charge noise over a wide frequency range in Si/SiGe quantum dots.