Interference Effect in Multi-level Transport through a Quantum Dot
H. Aikawa, K. Kobayashi, A. Sano, S. Katsumoto, and Y. Iye
We present experimental results and a model to solve the problem of "in-phase Coulomb peaks" ubiquitously observed in transport through a quantum dot. In a marginal region between Coulomb blockade and open-dot, we observed Fano-type interference through two energy levels inside the dot, which manifest itself as two widely different kinds of Coulomb-diamond-like structures in the excitation spectrum. One of the two levels is strongly coupled to the leads and the phase of traversing electrons is locked. We have detected the phase change at the vertices and the centers of the larger diamonds through the sign of the Fano”Ēs asymmetric parameters supporting the above deduction.