Precision measurement of a potential-profile tunable single-electron pump

Abstract

We performed a precision measurement of the current from a single-parameter electron pump, where the potential-profile for a quantum dot was manipulated by multiple top-metal gates. In an optimally tuned condition, driven with a sinusoidal-waveform microwave at f = 0.95 GHz, B = 11 T, and T = 0.3 K, the relative deviation of the pump current from ef, δI p /ef ≡ (I p − ef)/ef was measured to be (−0.92 ± 1.37) ppm. Our experiment reproduces the current quantisation accuracy of a previous measurement of a single-parameter pump, but in a device fabricated using very different geometry, thereby indicating that accurate single-parameter pumping is insensitive to device details.

High-resolution error detection in the capture process of a single-electron pump

“…2(b) and 2(e) we show P N ðV G2L Þ for 0 N 3, obtained from sets of 500 cycles for each V G2L using the slow and fast loading waveforms, respectively. As expected from DC measurements with the pump in a magnetic field, 5,7,8,20 there are a series of wide plateaus where one value of N dominates the loading statistics. This is highlighted by color-coding data points black when all the cycles yielded the same value of N. Comparable data have been presented previously, 9 but at zero magnetic field where the regime of very accurate loading could not be accessed.…”

“…In one example, a dynamically gated QD can pump electrons from a source to a drain electrode, [1][2][3][4] generating an accurate quantized current with metrological application as a new realisation of the ampere. [5][6][7][8] In this application, the accuracy of electron trapping and ejection in the non-adiabatic regime is of key importance. We wish to transfer n electrons in response to a single gate voltage cycle, with an error rate less than 10 À7 .…”

“…The error counting measurements on GaAs pumps 9,10 were performed in zero magnetic field using superconducting single electron transistor (SET) charge detectors, and were therefore not able to access the regime of high accuracy pumping attained in fields >10 T. 5,7,8 Precise single-electron counting tests of semiconductor QD pumps in the high-field, high-accuracy pumping regime are clearly desirable to validate the DC pumping measurements, and also to approach the benchmark error probability of $10 À8 demonstrated for a slow adiabatic metallic pump. 13 In this work, we focus on measuring P N , the probability of loading the QD with N electrons (distinguished from P n , the probability of pumping n electrons).…”

“…A magnetic field was applied perpendicular to the plane of the 2-DEG to enhance the current quantization. 5,7,8,20 Our measurement protocol is illustrated by schematic potential diagrams in Fig. 1(c).…”

Numerical simulation of quantized current generated by a quantum dot pump

“…[8][9][10][11][12] Also, spin pumping in graphene devices [13][14][15][16][17][18] and adiabatic pumping [19][20][21] were studied recently. It has been reported that the quantized current pumping can be achieved by applying periodic voltage modulation on a quantum dot gate.…”