Characterization of individual charge fluctuators in Si/SiGe quantum dots

Abstract

Electron spins in silicon quantum dots are excellent qubits due to their long coherence times, scalability, and compatibility with advanced semiconductor technology. Although high gate fidelities can be achieved with spin qubits, charge noise in the semiconductor environment still hinders further improvements. Despite the importance of charge noise, key questions about the specific nature of the fluctuators that cause charge noise remain unanswered. Here, we probe individual two-level fluctuators (TLFs) in Si/SiGe quantum dots through simple quantum-dot transport measurements and analyses based on the Allan variance and factorial hidden Markov modeling. We find that the TLF switching times depend sensitively on gate voltages, decrease with temperature, and depend on the current through a nearby quantum dot. A model for the data of the primary TLF we study indicates that it may be a bistable charge dipole near the plunger gate electrode, heated by current through the sensor dot, and experiencing state transitions driven not by direct electron-phonon coupling but through some other mechanism such as coupling to electrons passing through the sensor dot.

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Cited by in corpus (8)

• Automation of Quantum Dot Measurement Analysis via Explainable Machine Learning
• Real-time adaptive tracking of fluctuating relaxation rates in superconducting qubits
• Stabilizing an individual charge fluctuator in a Si/SiGe quantum dot
• Suppressing Si Valley Excitation and Valley-Induced Spin Dephasing for Long-Distance Shuttling
• Decoherence and fidelity enhancement during shuttling of entangled spin qubits
• Measuring pulse heating in Si quantum dots with individual two-level fluctuators
• Measuring and correcting nanosecond pulse distortions in quantum-dot spin qubits
• Subtleties in the pseudomodes formalism