A semiclassical nonequilibrium Green's Function approach to electron transport in systems exhibiting electron-phonon couplings

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Main Author: Ochoa, Maicol A.
Format: Preprint
Published: 2025
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author Ochoa, Maicol A.
author_facet Ochoa, Maicol A.
contents We formulate a semiclassical theory for electron transport in open quantum systems with electron-phonon interactions adequate for situations when the system's phonon dynamics is comparable with the electron transport timescale. Starting from the Keldysh non-equilibrium Green's function formalism we obtain equations of motion for the retarded and lesser electronic Green's functions including contributions due to the phonon dynamics up to second order in the electron-phonon coupling strength. The resulting equations assume that the system's phonon follow classical time-local dynamics with delta-correlated noise. We apply our method to the study of the charging/discharging of a periodically driven quantum dot, and a three-level model for a single-electron pump, analyzing the signatures in the transient current, electron population and process performance of the phonon dynamics. For these systems, we adopt the fluctuation-dissipation theorem and consider external harmonic driving of the phonon at frequencies comparable with the electron modulation, and different scenarios, varying electron-phonon coupling strength, coupling to the electron part of the system, and in phase and anti-phase driving. Our results illustrate that our method provides an efficient protocol to describe the effects of nuclear motion in ultrafast transient phenomena.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23620
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publishDate 2025
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spellingShingle A semiclassical nonequilibrium Green's Function approach to electron transport in systems exhibiting electron-phonon couplings
Ochoa, Maicol A.
Mesoscale and Nanoscale Physics
We formulate a semiclassical theory for electron transport in open quantum systems with electron-phonon interactions adequate for situations when the system's phonon dynamics is comparable with the electron transport timescale. Starting from the Keldysh non-equilibrium Green's function formalism we obtain equations of motion for the retarded and lesser electronic Green's functions including contributions due to the phonon dynamics up to second order in the electron-phonon coupling strength. The resulting equations assume that the system's phonon follow classical time-local dynamics with delta-correlated noise. We apply our method to the study of the charging/discharging of a periodically driven quantum dot, and a three-level model for a single-electron pump, analyzing the signatures in the transient current, electron population and process performance of the phonon dynamics. For these systems, we adopt the fluctuation-dissipation theorem and consider external harmonic driving of the phonon at frequencies comparable with the electron modulation, and different scenarios, varying electron-phonon coupling strength, coupling to the electron part of the system, and in phase and anti-phase driving. Our results illustrate that our method provides an efficient protocol to describe the effects of nuclear motion in ultrafast transient phenomena.
title A semiclassical nonequilibrium Green's Function approach to electron transport in systems exhibiting electron-phonon couplings
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2503.23620