A picture has emerged of an approximately, but not exactly, 1/ f-like charge-noise spectrum that may originate from surfaces or interfaces in Si/SiGe and other Si devices 5, 8, 9, 10, 11, 12, 13. As a result, charge noise in the semiconductor environment often limits the fidelity of these operations 2, 5. Most single- and two-qubit gates rely on manipulating electrons by precisely controlling their local electrostatic potentials, which typically result from voltages applied to gate electrodes, but are also affected by charge fluctuations in the environment.
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.ĭespite their long coherence times, which lead to high-fidelity single- 1, 2, 3 and two-qubit gates 4, 5, 6, 7, electron spins in Si/SiGe quantum dots suffer from charge noise. The charge noise is colored across the entire frequency range of our measurements, although the spectral exponent changes with frequency. 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. However, charge noise in the host semiconductor presents a major obstacle to achieving high-fidelity single- and two-qubit gates in these devices.
Electron spins in silicon quantum dots are promising qubits due to their long coherence times, scalable fabrication, and potential for all-electrical control.
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