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 pi along a resonance peak and drops abruptly by pi 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.