Finger-gate array quantum pumps:pumping characteristics and mechanisms

Abstract

We study the pumping effects, in both the adiabatic and nonadiabatic regimes, of a pair of \QTR{it}{finite} finger-gate array (FGA) on a narrow channel. Connection between the pumping characteristics and associated mechanisms is established. The pumping potential is generated by ac biasing the FGA pair. For a single pair (N=1) of finger gates (FG's), the pumping mechanism is due to the coherent inelastic scattering of the traversing electron to its subband threshold. For a pair of FGA with pair number $N>2$, the dominant pumping mechanism becomes that of the time-dependent Bragg reflection. The contribution of the time-dependent Bragg reflection to the pumping is enabled by breaking the symmetry in the electron transmission when the pumping potential is of a predominant propagating type. This propagating wave condition can be achieved both by an appropriate choice of the FGA pair configuration and by the monitoring of a phase difference $\varphi$ between the ac biases in the FGA pair. The robustness of such a pumping mechanism is demonstrated by considering a FGA pair with only pair number N=4.

7 pages, 6 figures

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• Nonadiabatic charge pumping by oscillating potentials in one dimension: results for infinite system and finite ring
• Nonadiabatic charge pumping in a one-dimensional system of noninteracting electrons by an oscillating potential
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• Transient magnetotransport through a quantum wire
• Time-dependent magnetotransport of a wave packet in a quantum wire with embedded quantum dots
• Numerical study of parametric pumping current in mesoscopic systems in the presence of magnetic field
• Coherent magnetotransport and time-dependent transport through split-gated quantum constrictions