A silicon single-electron pump with tunable electrostatic confinement

Nanoscale single-electron pumps could serve as the realization of a new quantum standard of electrical current. Here, a silicon quantum dot with tunable tunnel barriers is used as a source of quantized current. By controlling the electrostatic confinement of the dot via purposely engineered gate electrodes, we show that the stability of the pumping mechanisms can be dramatically enhanced. Our pump can produce a current in excess of 80 pA with experimentally determined relative uncertainty lower than 50 parts per million (ppm).