We review recent precision measurements on semiconductor tunable-barrier electron pumps operating in a ratchet mode. Seven studies on five different designs of pumps have reported measurements of the pump current with relative total uncertainties around 10−6 or less. Combined with theoretical models of electron capture by the pumps, these experimental data exhibits encouraging evidence that the pumps operate according to a universal mechanism, independent of the details of device design. Evidence for robustness of the pump current against changes in the control parameters is at a more preliminary stage, but also encouraging, with two studies reporting robustness of the pump current against three or more parameters in the range of ∼5×10−7 to ∼2×10−6. This review highlights the need for an agreed protocol for tuning the electron pump for optimal operation, as well as more rigorous evaluations of the robustness in a wide range of pump designs.
@article{arxiv.1901.05218,
title = {Evidence for universality of tunable-barrier electron pumps},
author = {Stephen P. Giblin and Akira Fujiwara and Gento Yamahata and Myung-Ho Bae and Nam Kim and Alessandro Rossi and Mikko Möttönen and Masaya Kataoka},
journal= {arXiv preprint arXiv:1901.05218},
year = {2019}
}