SPECTROSCOPY AND ENERGY-LEVEL STATISTICS IN A DISORDERED QUANTUM-DOT

The spectrum of heavily doped quantum dots is found to be discrete onl y in close vicinity to the Fermi energy. Levels further away are broad ened beyond the average level spacing and merge to form a quasi-contin uous spectrum. This breakdown of a single particle picture is consiste nt with electron-electron interaction in the dot. For the discrete par t of the spectrum, level statistics is studied as a function of magnet ic field and found to agree remarkably well with recent calculations.