We have observed a strongly non-Gaussian distribution of Coulomb blockade conductance peak heights for tunneling through quantum dots. At zero magnetic field, a low-conductance spike dominates the distribution; the distribution at nonzero field is distinctly different and still non-Gaussian. The observed distributions are consistent with theoretical predictions based on single-level tunneling and the concept of “quantum chaos” in a closed system weakly coupled to leads.

• Received 26 July 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.1695