Dynamical Resonances and Stepped Current in an Attractive Quantum Pump

TL;DR

This paper investigates the unique transport phenomena in an attractive quantum pump, revealing complex dynamical features like resonances and stepped currents through quantum, classical, and semiclassical analyses.

Contribution

It introduces the effects of an attractive potential well in a quantum pump, highlighting phenomena absent in barrier potentials, including fractal scattering and dynamical Fano resonances.

Findings

Sharp steps, spikes, and dips in quantum current as a function of incident energy

Fractal-like structure in classical scattering trajectories

Dynamical Fano resonance influences current depending on incident direction

Abstract

We report on the transport properties of a single mode quantum pump that operates by the simultaneous translation and oscillation of a potential well. We examine the dynamics comparatively using quantum, classical and semiclassical simulations. The use of an attractive or well potential is found to present several striking features absent if a barrier potential is used instead, as usually favored. The trapping of particles by the well for variable durations and subsequent release leads to a fractal-like structure in the distribution of the classical scattering trajectories. Interference among them leads to a rich dynamical structure in the quantum current, conspicuously missing in the classical current. Specifically, we observe sharp steps, spikes and dips in the current as a function of the incident energy of the carriers, and determine that a dynamical version of Fano resonance has a role that depends on the direction of incidence and on multiple scattering by the potential.