Abstract
The silicon metal-oxide-semiconductor (MOS) material system is a technologically important implementation of spin-based quantum information processing. However, the MOS interface is imperfect leading to concerns about 1/f trap noise and variability in the electron g-factor due to spin–orbit (SO) effects. Here we advantageously use interface–SO coupling for a critical control axis in a double-quantum-dot singlet–triplet qubit. The magnetic field-orientation dependence of the g-factors is consistent with Rashba and Dresselhaus interface–SO contributions. The resulting all-electrical, two-axis control is also used to probe the MOS interface noise. The measured inhomogeneous dephasing time, T_{{mathrm{2m}}}^ star, of 1.6 μs is consistent with 99.95% 28Si enrichment. Furthermore, when tuned to be sensitive to exchange fluctuations, a quasi-static charge noise detuning variance of 2 μeV is observed, competitive with low-noise reports in other semiconductor qubits. This work, therefore, demonstrates that the MOS interface inherently provides properties for two-axis qubit control, while not increasing noise relative to other material choices.
Highlights
The silicon metal-oxide-semiconductor (MOS) material system is a technologically important implementation of spin-based quantum information processing
The qubit in this work is formed within a MOS double-quantum dot (DQD)
Two electrons are electrostatically confined within a double well potential, where the dominant interaction between the electrons can be electrically tuned between two regimes for two-axis control (Fig. 1c)
Summary
The silicon metal-oxide-semiconductor (MOS) material system is a technologically important implementation of spin-based quantum information processing. We advantageously use the inherent g-factor difference from the SO coupling at the Si/SiO2 interface to create a second axis of control for a double-quantum dot (DQD) singlet–triplet (ST) qubit. This first demonstration of an allelectrical, two-axis controlled qubit in MOS is used to study qubit noise and SO interaction at the dielectric interface. The magnitudes are comparable if not better than those reported for other semiconductor qubit materials like GaAs/AlGaAs and Si/SiGe. The second central result of this paper is that we demonstrate a SO ST qubit and use its coherent qubit rotations to characterize the SO interaction at the MOS interface over its full magnetic field angular dependence. This work, further advances our understanding of the silicon MOS interface as a potential state-of-the-art platform for quantum information technologies
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