Noise spectra and initial correlation effects of transient quantum transport in nanostructures

Abstract

Transport current and current-current correlations are major quantities for the study of quantum transport through nanostructures They characterize the transport properties and can be examined through experimental measurements In this thesis we investigate quantum transport current and current-current correlations in the transient regime In particular utilizing the quantum Langevin equation we obtain a general formalism for transient current-current correlations and transient noise spectra for noninteracting nanostructures The exact solution of transient current correlations in both the time and the frequency domains are explicitly carried out for a single-level quantum dot system We investigate transient current-current correlations with different bias voltages at different temperatures without taking the wideband limit Transient noise spectra over the whole frequency range are found Various time scales associated with the energy structures of nanostructures are extracted through the transient current-current correlations and transient noise spectra We also derived the exact master equation incorporating initial system-lead correlations through the quantum Langevin equation The transient electron transport current incorporating initial correlations is obtained by solving the master equation We show that the initial correlations can affect quantum transport not only in the transient regime but also in the steady-state limit when system-lead couplings are strong enough such that electron localized states occur in the device system which sufficiently manifests non-Markovian memory effects

Date of Award	2016 Jan 26
Original language	English
Supervisor	Wei-Min Zhang (Supervisor)