此論文以理論的角度研究奈米尺度下的傳輸現象。當傳輸的通道是以兩個能階表示時，傳輸過程中會發生量子干涉效應。

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.

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