Current fluctuations of polymeric chains

TL;DR

This paper investigates electron transport and shot noise in polymeric chains within molecular devices, revealing how chain length and coupling strength influence noise characteristics and providing an algorithm to optimize current stability.

Contribution

It introduces a model combining Huckel and Newns-Anderson theories to analyze noise in polymeric molecular devices, highlighting the dependence on chain length and coupling, and offers a method to minimize current fluctuations.

Findings

Shot noise varies significantly with polymer length and coupling strength.

Transition from Poissonian to sub-Poissonian noise regimes is characterized.

An algorithm to calculate minimal current fluctuations is presented.

Abstract

Coherent electron transport is investigated in a molecular device made of polymeric chain sandwiched between two metallic electrodes. Molecular system is described by a simple Huckel model, while the coupling to the electrodes is treated through the use of Newns-Anderson chemisorption theory. Transport characteristics and noise power are calculated in two response regimes: linear and nonlinear, respectively. Here is shown a strong dependence of the shot noise on: (i) the length of the polymeric chain and (ii) the strength of the molecule-to-electrodes coupling. In particular, detailed discussion of Poissonian to sub-Poissonian crossover in the noise spectra is included. Presented algorithm allows to calculate the lowest possible level of current fluctuations (due to Pauli exclusion principle) in designing molecular devices.