Resonances in a two-dimensional electron waveguide with a single delta-function scatterer

We study the conductance properties of a straight two-dimensional electron waveguide with an s-like scatterer modeled by a single delta-function poten tial with a finite number of modes. Even such a simple system exhibits inte resting resonance phenomena. These resonances are explained in terms of qua sibound states both by using a direct solution of the Schrodinger equation and by studying the Green's function of the system. Using the Green's funct ion we calculate the survival probability as well as the power absorption, and show the influence of the quasibound states on these two quantities.