Robust operation of a GaAs tunable barrier electron pump

Abstract

We demonstrate the 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. The accuracy of current quantisation is investigated as a function of multiple control parameters, and robust plateaus are seen as a function of three control gate voltages and RF drive power. The electron capture is found to be in the decay-cascade, rather than the thermally-broadened regime. The observation of robust plateaus at an elevated temperature which does not require expensive refrigeration is an important step towards validating tunable-barrier pumps as practical current standards.PACS numbers: 1234 1 arXiv:1810.00100v1 [cond-mat.mes-hall]

Realisation of a quantum current standard at liquid helium temperature with sub-ppm reproducibility

“…Exceptionally stable examples of this model of DVM have demonstrated stability of the calibration factor as good as a few parts in 10 8 per day 21 . However, our experience in this study, and with previous studies at NPL 6,8,15 is that the C could change by up to a few parts in 10 7 per day. Even with daily calibrations directly against a Josephson array, as in the MIKES measurements, the use of a rectangular distribution yielded a typical relative uncertainty due to drift of around 10 −7 .…”

“…The plateau tilt ∆I = I max −I min = (0.3±0.5) ppm. This numerical statement about the plateau flatness is essentially a 2-dimensional extension of earlier attempts to define the pump plateau as the range of data points in a onedimensional scan for which the uncertainty in the gra-dient of a linear fit is greater than the fitted gradient 15 . In this work, unlike in Ref.…”

“…The typical method for testing robustness, used in several studies thus far 6,7,15 , reviewed in Ref. 5 and also shown in Fig.…”

“…In this work, unlike in Ref. 15, we have randomised the order of the data points which means that drift in the calibration of the measuring instruments only increases the random scatter of the data points (and therefore the uncertainty in the fitted slope), but cannot be mistaken for a sloped plateau. We find that there is thus no tilt of the plateau within the measurement uncertainty.…”

Evidence for universality of tunable-barrier electron pumps

“…In section V, we describe how the devices are tuned to achieve the high-accuracy pumping regime, and in section VI, we discuss the techniques used to compare the pump current to known reference currents. Finally in section VII, we review the experimental evidence for robustness and agreement from the seven precision studies [16][17][18][19][20][21][22] under consideration.…”