Gigahertz quantized charge pumping

Blumenthal, M.; Kaestner, B.; Li, L.; Giblin, S. P.; Janssen, T.J.B.M.; Pepper, M.; Anderson, David V.; Jones, G. A. C.; Ritchie, D. A.

doi:10.1038/nphys582

Cited by 377 publications

(329 citation statements)

References 25 publications

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“…However, these multijunction devices are hard to control and relatively slow 15 . Thus, the quest for feasible implementation with a possibility of parallel architecture for higher yield have led to alternative solutions such as surface-acoustic-wave-driven one-dimensional channels 8 , superconducting devices 11,[16][17][18][19][20][21] and semiconducting quantum dots 22 . These do produce large currents in the nano-ampere range but their accuracy is still limited.…”

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confidence: 99%

Hybrid single-electron transistor as a source of quantized electric current

Pekola¹,

Vartiainen²,

et al. 2007

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The basis of synchronous manipulation of individual electrons in solid-state devices was laid by the rise of single electronics about two decades ago 1-3 . Ultrasmall structures in a low-temperature environment form an ideal domain for addressing electrons one by one. In the so-called metrological triangle, voltage from the Josephson effect and resistance from the quantum Hall effect would be tested against current via Ohm's law for a consistency check of the fundamental constants of nature,h and e (ref. 4). Several attempts to create a metrological current source that would comply with the demanding criteria of extreme accuracy, high yield and implementation with not too many control parameters have been reported [5][6][7][8][9][10][11] . Here, we propose and prove the unexpected concept of a hybrid normal-metalsuperconductor turnstile in the form of a one-island singleelectron transistor with one gate, which demonstrates robust current plateaux at multiple levels of e f at frequency f .Synchronized sources, where current I is related to frequency by I = N ef and N is the integer number of electrons injected in one period, are the prime candidates for the devices to define one ampere in quantum metrology. The accuracy of these devices is based on the discreteness of the electron charge and the high accuracy of frequency determined from atomic clocks. Modern methods are replacing classical definitions of electrical quantities; voltage can be derived on the basis of the a.c. Josephson effect of superconductivity 12 and resistance by the quantum Hall effect 13,14 , but one ampere still needs to be determined via the mutual force exerted by the leads carrying the current. Early proposals of current pumps for quantum metrology were based on arrays of mesoscopic metallic tunnel junctions 5,6 , in which small currents could eventually be pumped at very low error rates 7 . However, these multijunction devices are hard to control and relatively slow 15 . Thus, the quest for feasible implementation with a possibility of parallel architecture for higher yield have led to alternative solutions such as surface-acoustic-wave-driven one-dimensional channels 8 , superconducting devices 11,16-21 and semiconducting quantum dots 22 . These do produce large currents in the nano-ampere range but their accuracy is still limited.Surprisingly, a simple hybrid single-electron transistor, with a small normal-metal (N) island and superconducting (S) leads, has been overlooked in this context. As demonstrated here, an SNS transistor, or alternatively an NSN transistor, see Fig. 1, presents a robust turnstile for electrons showing current plateaux at multiples of ef . We emphasize here that a one-island turnstile does not work even in principle without the hybrid design. An important feature in the present system is that hybrid tunnel junctions suppress tunnelling in an energy range determined by the gap ∆ in the density of states of the superconductor, see Fig. 1d bottom inset; current through a junction vanishes as long as |V J | ∼ < ∆/e...

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Hybrid single-electron transistor as a source of quantized electric current

Pekola¹,

Vartiainen²,

et al. 2007

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“…This device ideally generates a quantized output current, I P = nef , where n is an integer and f is the frequency of an external periodic drive. Several enabling technologies have already been developed including metal/oxide tunnel barrier devices 6,7 , normal-metal/superconductor turnstiles 8,9 , graphene double quantum dots 10 , donor-based pumps [11][12][13] , silicon-based quantum dot pumps [14][15][16][17][18] and GaAs-based quantum dot pumps [19][20][21][22][23][24][25][26][27] . To date, the latter scheme provides the lowest uncertainty of 1.2 parts per million (ppm) yielding current in excess of 150 pA 27 .…”

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confidence: 99%

An Accurate Single-Electron Pump Based on a Highly Tunable Silicon Quantum Dot

et al. 2014

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Nanoscale single-electron pumps can be used to generate accurate currents, and can potentially serve to realize a new standard of electrical current based on elementary charge. Here, we use a silicon-based quantum dot with tunable tunnel barriers as an accurate source of quantized current. The charge transfer accuracy of our pump can be dramatically enhanced by controlling the electrostatic confinement of the dot using purposely engineered gate electrodes. Improvements in the operational robustness, as well as suppression of non-adiabatic transitions that reduce pumping accuracy, are achieved via small adjustments of the gate voltages. We can produce an output current in excess of 80 pA with experimentally determined relative uncertainty below 50 parts per million.As early as one and a half centuries ago, J. C. Maxwell envisaged the need for a system of standards based on phenomena at the atomic scale and directly related to invariant constants of nature. 1 However, Maxwell could not anticipate that, in order to harness the behaviour of the world at the nanometer scale, a completely new physical interpretation was needed, namely, quantum mechanics. At first, the laws of quantum mechanics seemed to reveal fundamental limits to the accuracy of physical measurements. Concepts like the Heisenberg uncertainty principle, which imposes intrinsic fluctuations on the values of non-commuting observables, and the wavefunction collapse, responsible for the randomization of a system configuration after performing a measurement, appeared to be at odds with the requirement of deterministic consistency that is paramount for metrological purposes. Nevertheless, quantum-based systems are today acknowledged as the most stable and reliable metrological tools, as they can be strongly intertwined with fundamental constants. Exquisitely quantum-mechanical phenomena such as the ac Josephson effect 2 and the quantum Hall effect 3 have paved the way towards new and more reliable reference standards for the units of voltage and resistance, respectively.Major efforts are currently ongoing to re-define the unit of electrical current, the ampere (A), in terms of the elementary charge, e, by means of quantum technologies 4,5 . A practical implementation of this standard may be the electron pump, a device in which a quantum phenomenon, namely tunnelling, and classical Coulomb repulsion, are combined to control the transfer of an integer number of elementary charges. This device ideally generates a quantized output current, I P = nef , where n is an integer and f is the frequency of an external periodic drive. Several enabling technologies have already been developed including metal/oxide tunnel barrier devices 6,7 , normal-metal/superconductor turnstiles 8,9 , graphene double quantum dots 10 , donor-based pumps 11-13 , silicon-based quantum dot pumps 14-18 and GaAs-based quantum dot pumps [19][20][21][22][23][24][25][26][27] . To date, the latter scheme provides the lowest uncertainty of 1.2 parts per million (ppm) yielding current in excess o...

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“…9, the amplitude and phase relation of the two high frequency signals applied to the two gates have to be carefully controlled. Kaestner et al have shown experimentally that it is sufficient to drive a single gate to achieve a quantized pumping current at very high frequency.…”

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confidence: 99%

“…Recently, Blumenthal et al have demonstrated a new promising way to deliver high currents. 9 Their device consists of a semiconductor quantum wire crossed by three metal gates. For pumping, two of these gates are driven by phase locked high frequency signals.…”

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confidence: 99%