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 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 φ 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.

Floquet scattering theory for current and heat noise in large amplitude adiabatic pumps

“…For the mesoscopic (phase coherent) samples with energy independent scattering matrix the Wiedemann-Franz law (with the same ratio) can be formulated in terms of electrical G and thermal K conductances which characterize the entire sample. 96,97,98 As a result we arrive at equation (30).…”

“…It should be noted that the equation (30) holds for the thermal noise modified by the pump. Therefore we can suggest that the instantaneous currents dIα/dE Eq.…”

Quantum pump driven fermionic Mach-Zehnder interferometer

“…Theoretically, a large number of investigations of various aspects of quantum pumping have been carried out, a representative collection can be found in Refs. [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32]. However, only a few experiments aimed at investigating quantum pumping of electrical currents have been performed.…”