Abstract
Time-dependent electron transport processes are often driven by a periodic field and studied in the wide-band limit. In this thesis, we extend the generalized Floquet approach beyond wide-band limit for the nonperturbative treatment of electron transport driven by monochromatic or bichromatic fields. In order to deal with the case of bichromatically driven fields with incommensurate frequencies, we adopt the many-mode Floquet theory to reduce the non-periodically time-dependent Hamiltonian into an equivalent time-independent infinite-dimensional generalized Floquet matrix eigenvalue problem. The approach is used to perform a detailed analysis of the electron-transport dc current in the electrode-quantum dots-electrode system driven by external fields, including periodic and bichromatic fields. The coherent destruction of tunneling phenomenon is studied in the case of symmetric Λ-type triple quantum dots driven by a periodic field. Besides, we show that the dc current depends sensitively on the commensurability of the driving frequencies. These interesting physical phenomena may provide a convenient way to control the current by fabricating a quantum device.
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