Electron counting in a silicon single-electron pump

TL;DR

This paper demonstrates precise electron counting in a silicon quantum dot pump, confirming its quantized current and improved robustness with electrostatic confinement, advancing silicon-based quantum metrology.

Contribution

It introduces a single-electron counting method in silicon quantum dots, validating quantized current and robustness improvements over previous techniques.

Findings

Probabilities match direct current measurements across various potentials.

Counting confirms quantized electron transfer up to 4 electrons per cycle.

Robustness of pumping improves with increased electrostatic confinement.

Abstract

We report electron counting experiments in a silicon metal-oxide-semiconductor quantum dot architecture which has been previously demonstrated to generate a quantized current in excess of 80 pA with uncertainty below 30 parts per million. Single-shot detection of electrons pumped into a reservoir dot is performed using a capacitively coupled single-electron transistor. We extract the full probability distribution of the transfer of n electrons per pumping cycle for n = 0, 1, 2, 3, and 4. We find that the probabilities extracted from the counting experiment are in agreement with direct current measurements in a broad range of dc electrochemical potentials of the pump. The electron counting technique is also used to confirm the improving robustness of the pumping mechanism with increasing electrostatic confinement of the quantum dot.