Abstract
This thesis is intended theoretically comparing the quantum properties through a single level to the transport through the two levels in the 1D nanotransport. We use the tight-binding model and linearize the wave function of two leads. Meanwhile, we ignore the interaction between electrons, so the we deal with the 1D Fermi liquid without Coulomb blockade effect. We calculate these transport properties with equation of motion method and path integral method. Therefore, we conclude that the spectral function of a single level the get broadening when the levels are coupling to the leads which we regard as reservoirs. Besides, the Meir and Wingreen's formula is applied in a channel which is a single level, so that the conductance is proportional to the spectral function. However, when we consider the channel which is the two levels, the relation between the conductance and the spectral function is not longer correct, that is because that there is quantum interference effects here.