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

TL;DR

This study comprehensively measures charge noise in Si/SiGe quantum dots across a vast frequency spectrum using advanced dynamical decoupling techniques, revealing its colored nature and consistency with conductance-based assessments, crucial for qubit fidelity.

Contribution

It provides the first extensive charge-noise spectrum of Si/SiGe quantum dots over 12 decades in frequency using dynamical decoupling and conductance measurements, demonstrating their agreement.

Findings

Charge noise is colored across all measured frequencies.

Spectral exponent varies with frequency.

Conductance measurements reliably characterize charge noise.

Abstract

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 {\pi} 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.