Lapse of transmission phase and electron molecules in quantum dots

The puzzling behavior of the transition phase through a quantum dot can be understood in a natural way via a formation of the electron molecule in the quantum dot. In this case the resonance tunneling takes place through the quasi-stationary (doorway) state, which emerges when the number of electrons occupying the dot reaches a certain ``critical'' value, $N_{cr}$. Our estimation of this quantity agrees with the experimental data. The dependence of $N_{cr}$ on the dot's size is predicted as well.