We report on the realization of a single-electron source, where current is transported through a single-level quantum dot (Q), tunnel-coupled to two superconducting leads (S). When driven with an ac gate voltage, the experiment demonstrates electron turnstile operation. Compared to the more conventional superconductor - normal metal - superconductor turnstile, our SQS device presents a number of novel properties, including higher immunity to the unavoidable presence of non-equilibrium quasiparticles in superconducting leads. In addition, we demonstrate its ability to deliver electrons with a very narrow energy distribution.
@article{arxiv.1601.02469,
title = {Single Quantum Level Electron Turnstile},
author = {D. M. T. van Zanten and D. M. Basko and I. M. Khaymovich and J. P. Pekola and H. Courtois and C. B. Winkelmann},
journal= {arXiv preprint arXiv:1601.02469},
year = {2016}
}