Effects Of Electron-phonon Interaction Under External Field On Quantum Transport Through A Single-molecular Quantum Dots

It has been shown that Electron-phonon interaction (EPI) is strong in the systems of quantum dots(QDs) at low temperature. Important effects of the electron-phonon interaction on the properties of quantum transport and many-body have been studied. In this thesis, with special concerns focused on the effects on the EPI by field in the non-equilibrium transport through a single-molecular quantum dot, non-equilibrium Green function technique and canonical transformation method under the adiabatic approximation for the local electron-phonon system have been applied. Whereby the EPI can be treated nonperturbatively and nonequilibrium electron transport caused by the finite bias voltage across the system is treated conveniently. It is found that in the presence of the electron-phonon interaction and time-dependent fields, the variation of the time-depended current become periodicity with two times than frequency of time-dependent electric fields. The variation of the spectral function with time and energy is also studied.