The origins of noise in the Zeeman splitting of spin qubits in natural-silicon devices

Abstract

We measure and analyze noise-induced energy-fluctuations of spin qubits defined in quantum dots made of isotopically natural silicon. Combining Ramsey, time-correlation of single-shot measurements, and CPMG experiments, we cover the qubit noise power spectrum over a frequency range of nine orders of magnitude without any gaps. We find that the low-frequency noise spectrum is similar across three different devices suggesting that it is dominated by the hyperfine coupling to nuclei. The effects of charge noise are smaller, but not negligible, and are device dependent as confirmed from the noise cross-correlations. We also observe differences to spectra reported in GaAs {[Phys. Rev. Lett. 118, 177702 (2017), Phys. Rev. Lett. 101, 236803 (2008)]}, which we attribute to the presence of the valley degree of freedom in silicon. Finally, we observe $T_2^{\ast }$ to increase upon increasing the external magnetic field, which we speculate is due to the increasing field-gradient of the micromagnet suppressing nuclear spin diffusion.

12 pages, 10 figures

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Cited by in corpus (3)

• Interplay of Zeeman Splitting and Tunnel Coupling in Coherent Spin Qubit Shuttling
• Noise cross-correlations from single-shot measurements
• Comparison of spin-qubit architectures for quantum error-correcting codes