Phase property of the transmission through a quantum dot

We present a theoretical study of the phase property of the transmission coefficient of a quantum dot. We model the quantum dot by a cross-bar structure and take account of electron-electron interactions in the dot in a self-consistent mean-field approximation. We find that the phase acquired by electrons traversing the dot increases smoothly by π along a resonance peak and drops abruptly by π in the tail of the resonant peak, where the probability of the transmission vanishes. We also show that this sharp phase change cannot be seen in a model that assumes a single-particle, double-barrier structure only for the quantum dot.