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

Hohls, Frank; Kashcheyevs, Vyacheslavs; Stein, F.; Wenz, Tobias; Kaestner, B.; Schumacher, H. W.

doi:10.1103/physrevb.105.205425

Cited by 3 publications

(2 citation statements)

References 43 publications

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“…In the case of the LPR there appears to be no change in the accuracy in pumped current as the number of electrons pumped through the QD per cycle is increased. In the CPR the demonstration of high pumped accuracy of below 2 × 10 -7 at a current of around 100 pA has been demonstrated [30] in high fields with work by Hohls et al [31] uncertainties of the order 10 -6 were shown. These results however were achieved with only a single electron n = 1 pumped per cycle, with no work shown on the accuracy achieved for a higher number n > 1 of electrons per cycle.…”

Section: Pump Accuracymentioning

confidence: 91%

Multiple electron pumping

Blumenthal,

Mahony,

Ahmad

et al. 2023

EPJ Quantum Technol.

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The need to pump single electrons with a high degree of accuracy and fidelity has led to the development of a range of different pump and turnstile designs. Previous pumping mechanisms have all demonstrated that pumping more than one electron per cycle degrades the quantisation of the measured current. This unreliable delivery of multiple electrons per cycle has limited the use of on-demand single electron sources in electron quantum optic experiments. We present highly quantised current with multiple electrons pumped per cycle. We experimentally demonstrate that in our pumps an increase in electron throughput per cycle does not lead to an appreciable degradation in the accuracy of the produced current.Our pump is realised in an aluminium gallium arsenide two-dimensional electron gas, where electrons are pumped through a one-dimensional split-gate confinement potential under the influence of an applied source-drain voltage $V_{\text{SD}}$ V SD , and where the pump is driven by a trapezoidal arbitrary waveform. This combination of a split-gate potential, $V_{\text{SD}}$ V SD bias and trapezoidal wave form has led to the observation of robust quantised plateaus where not just a single electron, but a multiple integer number of electrons are pumped per cycle with a high degree of robustness and without the need of a magnetic field. For seven electrons per cycle, we report an increase of over two orders of magnitude in pumping accuracy from $2.72 \times 10^{-2}$ 2.72 × 10 − 2 in devices operating in the conventional pumping regime, to $1.64 \times 10^{-4}$ 1.64 × 10 − 4 in pumps operating in what we call the long plateau regime, a regime accessed under a change in a split-gate pumps applied $V_{\text{SD}}$ V SD voltage. This pump will find direct use in quantum transport measurements where the metrological accuracy of single electrons pumped per cycle is not required and the low throughput per cycle of electrons is limiting.

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Section: Pump Accuracymentioning

confidence: 91%

Multiple electron pumping

Blumenthal,

Mahony,

Ahmad

et al. 2023

EPJ Quantum Technol.

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“…In particular, we slow down the evolution of energy difference for the desired processes while accelerating that of the unwanted events, hence decreasing the likelihood of the latter. Recently, a similar approach has been employed to suppress back-tunneling events in semiconductor quantum dot single-electron pumps [35], but with no bias modulation. With this, we go beyond the device and setup optimization for error suppression, turning our attention instead to modifying the island chemical potential evolution beyond the simple gate waveform modification.…”

Section: Introductionmentioning

confidence: 99%

Suppression of Back-Tunneling Events in Hybrid Single-Electron Turnstiles by Source-Drain Bias Modulation

et al. 2023

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The accuracy of single-electron currents produced in hybrid turnstiles at high operation frequencies is, among other errors, limited by electrons tunneling in the wrong direction. Increasing the barrier transparency between the island and the leads, together with the source-drain bias, helps to suppress these events in a larger frequency range, although they lead to some additional errors. We experimentally demonstrate a driving scheme that suppresses tunneling in the wrong direction, thus extending the range of frequencies for generating accurate single-electron currents. The main feature of this approach is an additional ac signal applied to the bias with frequency twice that applied to the gate electrode. This allows additional modulation of the island chemical potential. By using this approach under certain parameters, we improve the single-electron current accuracy by one order of magnitude. Finally, we show through experimentally contrasted calculations that our method can improve accuracy even in devices for which the usual gate driving gives errors of the order of 10 −3 at high frequencies and can bring them under 5 × 10 −4 .

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

Yamahata,

Fujiwara

2024

Journal of Applied Physics

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Precise and reproducible current generation is the key to realizing 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 below the ppm level. Although several measurements have shown such levels of accuracy, it is necessary to further pursue the possibility of high-precision operation toward reproducible generation of the pumping current in many devices. Here, we investigated silicon single-hole pumps, which may have the potential to outperform single-electron pumps because of the heavy effective mass of holes. Measurements on the temperature dependence of the current generated by the single-hole pump revealed that the tunnel barrier had high energy selectivity, which is a critical parameter for high-accuracy operation. In addition, we applied the dynamic gate-compensation technique to the single-hole pump and confirmed that it yielded a further performance improvement. Finally, we demonstrated gigahertz operation of a single-hole pump in which the estimated lower bound of the pump error rate was around 0.01 ppm. These results imply that single-hole pumps in silicon are capable of high-accuracy, high-speed, and stable single-charge pumping in metrological and quantum-device applications.

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

Cited by 3 publications

References 43 publications

Multiple electron pumping

Multiple electron pumping

Suppression of Back-Tunneling Events in Hybrid Single-Electron Turnstiles by Source-Drain Bias Modulation

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

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