The dynamic capture of electrons in a semiconductor quantum dot (QD) by raising a potential barrier is a crucial stage in metrological quantized charge pumping. In this work, we use a quantum point contact (QPC) charge sensor to study errors in the electron capture process of a QD formed in a GaAs heterostructure. Using a two-step measurement protocol to compensate for 1/f noise in the QPC current, and repeating the protocol more than 106 times, we are able to resolve errors with probabilities of order 10−6. For the studied sample, one-electron capture is affected by errors in ∼30 out of every million cycles, while two-electron capture was performed more than 106 times with only one error. For errors in one-electron capture, we detect both failure to capture an electron, and capture of two electrons. Electron counting measurements are a valuable tool for investigating non-equilibrium charge capture dynamics, and necessary for validating the metrological accuracy of semiconductor electron pumps.
@article{arxiv.1809.10081,
title = {High-resolution error detection in the capture process of a single-electron pump},
author = {S. P. Giblin and P. See and A. Petrie and T. J. B. M. Janssen and I. Farrer and J. P. Griffiths and G. A. C. Jones and D. A. Ritchie and M. Kataoka},
journal= {arXiv preprint arXiv:1809.10081},
year = {2018}
}