A two-atom electron pump

Area of Science:

• Quantum electronics
• Nanofabrication
• Solid-state physics

Background:

• Single-atom transistors represent extreme miniaturization in nanofabrication.
• Coupling multiple dopants in nanoelectronic devices offers promising functionalities.
• Previous work enabled spectroscopy of donor states via d.c. electrical transport.

Purpose of the Study:

• To demonstrate single electron manipulation over two dopants in series.
• To investigate electron pumping in a silicon nanowire with two phosphorus donors.
• To explore the behavior of electron pumping in both adiabatic and non-adiabatic regimes.

Main Methods:

• Fabrication of a silicon nanowire with two serially implanted phosphorus donors.
• Electrical transport measurements to demonstrate electron pumping.
• Analysis of charge transfer dynamics, considering tunneling rates and Landau-Zener transitions.

Main Results:

• Successful demonstration of electron pumping through two serially coupled phosphorus donors.
• Observation of quantized pumping in the low-frequency adiabatic regime.
• Identification of non-adiabatic features at higher frequencies, limited by tunneling rates.
• Modeling of quantum state transitions using Landau-Zener theory to explain observed signatures.

Conclusions:

• Electron pumping over two donors in a silicon nanowire is achievable.
• The study reveals distinct behaviors in adiabatic and non-adiabatic pumping regimes.
• Landau-Zener transitions provide a framework for understanding non-adiabatic charge transfer dynamics in such systems.