Gigahertz Single-Electron Pumping Mediated by Parasitic States.

Area of Science:

• Quantum metrology and solid-state physics.
• Focus on semiconductor devices for fundamental electrical standards.

Background:

• Semiconductor single-electron pumps are crucial for the quantum standard of the ampere.
• Electrostatically defined quantum dots (QDs) offer fast, accurate charge transfer but degrade above 1 GHz.
• Hybrid pumps coupling QDs to trap states show potential for higher transfer rates.

Purpose of the Study:

• To operate and characterize a novel hybrid electron pump in silicon.
• To investigate current quantization robustness at gigahertz frequencies.
• To understand the role of parasitic states in electron transfer fidelity.

Main Methods:

• Fabrication of a hybrid electron pump in silicon by coupling a quantum dot (QD) to parasitic trap states.
• Operation of the hybrid pump at radio frequencies up to several gigahertz.
• Analysis of pumped current and charge transfer fidelity as a function of frequency and parasitic state loading sequence.

Main Results:

• Achieved robust current quantization in the silicon hybrid electron pump up to gigahertz frequencies.
• Demonstrated that electron capture fidelity is sensitive to the loading sequence of parasitic states.
• Observed distinct frequency-dependent features in the pumped current attributed to parasitic state dynamics.

Conclusions:

• Hybrid electron pumps utilizing parasitic states in silicon can maintain accurate current quantization at high frequencies.
• The control over parasitic state loading sequences is key to optimizing electron pump performance.
• This work advances the development of semiconductor-based electron pumps for future quantum electrical standards.