QUASI-PARTICLE LIFETIME IN A QUANTUM-DOT

The quasi-particle lifetime is calculated for electrons in a quantum d ot as a function of energy, disorder, and dot size. As a result of ele ctron-electron interaction, the spectrum is discrete only in close vic inity of the Fermi level. In the strongly diffusive case, levels farth er than the Thouless energy (inverse diffusion time across the dot) fr om the Fermi level are broadened by the interaction beyond the average level spacing and merge to form a continuous spectrum. The number of discrete levels is hence of the order of 5-20 in typical experiments t hough such dots may contain thousands of electrons. For less disordere d and ballistics dots, the number of discrete levels is of the order o f the square root of the number of electrons in the dot.