Fano Resonance in the Nonadiabatically Pumped Shot Noise of a Time-Dependent Quantum Well in 2DEG and Graphene

TL;DR

This paper investigates Fano resonance in nonadiabatic quantum wells within 2DEG and graphene, revealing wavevector matching as the key condition for resonance and analyzing its effects on shot noise.

Contribution

It demonstrates the occurrence of Fano resonance at wavevector matching in systems with transverse motion using Floquet theory, extending understanding beyond energy matching in 1D systems.

Findings

Fano resonance occurs at wavevector matching in 2D systems with transverse motion.

Resonance follows the dispersion of the quasibound state.

Prominent Fano resonance observed in pumped shot noise spectra.

Abstract

Interference between different quantum paths can generate Fano resonance. One of the examples is transport through a quasibound state driven by time-dependent scattering potential. Previously it is found that Fano resonance occurs as a result of energy matching in one-dimensional systems. In this work, we demonstrate that when transverse motion is present, Fano resonance occurs precisely at the wavevector matching situation. Using the Floquet scattering theory, we considered the transport properties of a nonadiabatic time-dependent well both in the 2DEG and monolayer graphene structure. Dispersion of the quasibound state of a static quantum well is obtained with transverse motion present. We found that Fano resonance occurs when the wavevector in the transport direction of one of the Floquet sidebands is exactly identical to that of the quasibound state in the well at equilibrium and follows the dispersion pattern of the latter. To observe the Fano resonance phenomenon in the transmission spectrum, we also considered the pumped shot noise properties when time and spatial symmetry secures vanishing current in the considered configuration. Prominent Fano resonance is found in the differential pumped shot noise to the reservoir Fermi energy.