Chaotic behavior induced by point contacts in quantum dots

The conductance of quantum dots with ballistic point contacts supporting a single channel and placed at arbitrary sites on their perimeters has been numerically computed. The results indicate that whenever the contacts break the dot symmetry, the statistics of the conductance closely follow the circular orthogonal ensemble result, no matter whether the shape of the quantum dot is itself regular or not and independently of its size. On the other hand, the statistics of adjacent resonances (a property closely related to the level statistics of the isolated quantum dot) follows the Wigner-Dyson distribution only for small systems.