ELECTRON CONDUCTANCE AND LIFETIMES IN A BALLISTIC ELECTRON WAVE-GUIDE

Ballistic electron waveguides are open quantum systems that can be for med at very low temperatures at a GaAs/AlGaAs interface. Dissipation d ue to electron-phonon and electron-electron interactions in these syst ems is negligible. Although the electrons only interact with the walls of the waveguide, they can have a complicated spectrum including both positive energy bound states and quasibound states which appear as co mplex energy poles of the scattering S-matrix or energy Green's functi on. The quasibound states can give rise to zeros in the waveguide cond uctance as the energy of the electrons is varied. The width of the con duction zeros is determined by the lifetimes of the quasibound states. The ''complex energy spectrum'' associated with the quasibound states also governs the survival probability of electrons placed in the wave guide cavities.