Advances toward high-accuracy gigahertz operation of tunable-barrier single-hole pumps in silicon

TL;DR

This paper demonstrates gigahertz operation of silicon single-hole pumps with error rates around 0.01 ppm, showing their potential for high-precision quantum current standards and advanced quantum devices.

Contribution

It presents detailed investigation and optimization of silicon single-hole pumps, achieving high-frequency operation with ultra-low error rates, surpassing previous single-electron pump performance.

Findings

High energy selectivity of tunnel barrier confirmed

Dynamic gate compensation improves performance

Gigahertz operation with 0.01 ppm error rate achieved

Abstract

Precise and reproducible current generation is key to realize quantum current standards in metrology. A promising candidate is a tunable-barrier single-charge pump, which can accurately transfer single charges one by one with an error rate of less than ppm level. Although several high-accuracy measurements have revealed such a high performance of the pumps, it is necessary to further pursue the possibility of high-precision operation toward reproducible generation of the pumping current in many devices. Here, we investigate in detail a silicon single-hole pumps, which are potentially expected to have a superior performance to single-electron pumps because of a heavy effective mass of holes. Temperature dependence measurements of current generated by the single-hole pump revealed a high energy selectivity of the tunnel barrier, which is a critical parameter to achieve high-accuracy operation. In addition, we applied the dynamic gate compensation technique to the single-hole pump and confirm the further performance improvement. Furthermore, we demonstrate gigahertz operation of a single-hole pump with an estimated lower bound of an error rate of around 0.01 ppm. These results imply a superior capability of single-hole pumps in silicon toward high-accuracy, high-speed, and stable single-charge pumping appropriate for not only metrological applications but also quantum device applications.