CHAOTIC BEHAVIOR INDUCED BY POINT CONTACTS IN QUANTUM DOTS

The conductance of quantum dots with ballistic point contacts supporti ng 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 clo sely follow the circular orthogonal ensemble result, no matter whether the shape of the quantum dot is itself regular or not and independent ly of its size. On the other hand, the statistics of adjacent resonanc es (a property closely related to the level statistics of the isolated quantum dot) follows the Wigner-Dyson distribution only for small sys tems. [S0163-1829(98)50540-1].