Charge and heat transport of soft nanosystems in the presence of time-dependent perturbations

TL;DR

This paper reviews how time-dependent perturbations influence charge and heat transport in soft nanosystems like molecular junctions, highlighting the interplay between electronic and vibrational modes under external driving.

Contribution

It generalizes the adiabatic approach to include external time-dependent perturbations and applies it to systems with electron-vibration coupling, providing insights into nonlinear regimes.

Findings

External forcing near vibrational resonance enhances electronic response.

Time-dependent perturbations induce nonlinear effects in charge and heat transport.

The generalized adiabatic approach agrees well with exact quantum calculations at low vibrational occupation.

Abstract

Soft nanosystems are electronic nanodevices, such as suspended carbon nanotubes or molecular junctions, whose transport properties are modulated by soft internal degrees of freedom, for example slow vibrational modes. In this review, effects of the electron-vibration coupling on the charge and heat transport of soft nanoscopic systems are theoretically investigated in the presence of time-dependent perturbations, such as a forcing antenna or pumping terms between the leads and the nanosystem. A well established approach valid for non-equilibrium adiabatic regimes is generalized to the case where external time-dependent perturbations are present. Then, a number of relevant applications of the method are reviewed for systems composed by a quantum dot (or molecule) described by a single electronic level coupled to a vibrational mode. Before introducing time-dependent perturbations, the range of validity of the adiabatic approach is discussed showing that a very good agreement with the results of an exact quantum calculation is obtained in the limit of low level occupation. Aim of this review has been to discuss common features of different soft nanosystems under external drive. The most interesting effects induced by time-dependent perturbations are obtained when the external forcing is nearly resonant with the slow vibrational modes. Indeed, not only the external forcing can enhance the electronic response, but it also induces nonlinear regimes where the interplay between electronic and vibrational degrees of freedom plays a major role.