Robustness of single-electron pumps at sub-ppm level

Single-electron pumps (SEP's) based on tunable barrier quantum dots show the most promise as high-precision nanoampere quantum sources. They are treated as a good candidate in the context of a quantum representation of the SI base unit ampere. A key point for such a realization is the robustness of operation. Here we show the invariance of current at a sub-ppm level against variation of magnetic flux density, bias voltage on source and drain and the entrance gate voltage.