KRISS and NPL have demonstrated robust operation of a gallium arsenide tunable-barrier single-electron pump operating with 1 part-per-million accuracy at a temperature of 1.3 K and a pumping frequency of 500 MHz.

NPL and KRISS scientists showed that the current from a gallium arsenide electron pump was still accurately quantised at the level of 1 part per million even when the pump was ‘detuned’ from its optimal operating point. This means that the different voltage signals required to control the pump do not need to be precisely specified, a requirement for any primary standard based on a physical effect.

The measurements were performed at a temperature of ~1.3 kelvin. While cold by everyday standards, this temperature is larger than all previous precision measurements of gallium-arsenide pumps. Accurate and robust operation of the electron pump at this temperature is a promising step towards adoption of electron pumps as practical current standards.

This work was published open-access in Metrologia, a journal of the Institute of Physics:
S. P. Giblin, M. H. Bae, N. Kim, Y. H. Ahn and M. Kataoka,
“Robust operation of a GaAs tunable barrier electron pump”. Metrologia 54, 299 (2017).