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

Abstract

A silicon electron pump operating at the temperature of liquid helium has demonstrated repeatable operation with sub-ppm accuracy. The pump current, approximately 168 pA, is measured by three laboratories, and the measurements agree with the expected current ef within the uncertainties which range from 0.2 ppm to 1.3 ppm. All the measurements are carried out in zero applied magnetic field, and the pump drive signal is a sine wave. The combination of simple operating conditions with high accuracy demonstrates the possibility that an electron pump can operate as a current standard in a National Measurement Institute. We also discuss other practical aspects of using the electron pump as a current standard, such as testing its robustness to changes in the control parameters, and using a rapid tuning procedure to locate the optimal operation point.

Controlling the error mechanism in a tunable-barrier non-adiabatic charge pump by dynamic gate compensation

“…( 2) and (3). The same mechanism for the capture of the (unwanted) second electron predicts [34] a steep double-exponential V DC 2dependence of P 2 , however, at low enough P 2 other error mechanisms [21,30,36,43] take over, with rare thermal errors following the exponential ansatz (6).…”

“…Single-electron pumps based on tunable barrier quantum dots (QDs) [1,2] show much promise as quantum current standard [3][4][5][6] within the revised SI-system that came into effect on May 20th, 2019. Since then, the value of the elementary charge e in SI units is defined as 1.602176634 × 10 −19 As without uncertainty.…”

“…Non-adiabatic single gate modulation of QDs is a robust mode of operation and was investigated extensively [4,5,9,18,[27][28][29][30][31]. For GaAs-based single-electron pumps a magnetic field is applied to enhance the pumping accuracy [28,32,33] with demonstrated accuracies down to 0.16 ppm, limited by uncertainties in the measurement setup [4][5][6]31]. Generally, underlying error mechanisms are explained by backtunneling errors using the decay cascade model [34].…”

New single-electron pump regime with highly controllable plateaus

“…There are a few theoretical models that describe a possible mechanism for conventional quantised pumping 2,12,15 , with a good summary and the relative merits and limitations discussed by Giblin et al 16 . Flatness for metrology needs to be done empirically, as fits do not necessarily capture all the error mechanisms in the pumping process, and currently there is no theoretical framework that describes all the error mechanisms and provides a good fit to the data.…”

Simulations of hybrid charge-sensing single-electron-transistors and CMOS circuits

“…Currently, conventional Si transistors are much smaller than SETs. SETs have attracted attention as charge sensors [11][12][13] , which have been used for the readouts of silicon qubits [14][15][16] , or as current standards [17][18][19] .…”