Waveform sampling using an adiabatically driven electron ratchet in a two-dimensional electron system

TL;DR

This paper demonstrates a method to generate a net dc current in a 2D electron system using a phase-shifted, waveform-dependent adiabatic ratchet mechanism driven by interdigitated gates.

Contribution

It introduces a novel waveform-dependent electron ratchet in a 2D system, supported by a linear adiabatic pumping model that matches experimental results.

Findings

The dc pumping current depends on phase shift and waveform of gate voltages.

Different periodic signals produce phase dependence similar to their waveforms.

The linear model accurately reproduces experimental observations.

Abstract

We utilize a time-periodic ratchet-like potential modulation imposed onto a two-dimensional electron system inside a GaAs/Al$_x$Ga$_{1-x}$As heterostructure to evoke a net dc pumping current. The modulation is induced by two sets of interdigitated gates, interlacing off center, which can be independently addressed. When the transducers are driven by two identical but phase-shifted ac signals, a lateral dc pumping current $I(\phi)$ results, which strongly depends on both, the phase shift $\phi$ and the waveform $V(t)$ of the imposed gate voltages. We find that for different periodic signals, the phase dependence $I(\phi)$ closely resembles $V(t)$. A simple linear model of adiabatic pumping in two-dimensional electron systems is presented, which reproduces well our experimental findings.