2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16948We present an {\it exact} quantum theory for the bound states in the vicinity of an edge or a line of impurities in a $d_{x^2-y^2}$ superconductor. For a (110)-surface we show that a finite dispersion of the one dimensional band of bound states leads to a two peak structure in the density of states (DOS). We study the effect of an applied magnetic field and a subdominant $id_{xy}$ order parameter on the DOS and discuss the implications of our results for tunneling experiments.4 pages, figures 2 and 3 are in colorSuperconductivityStrongly Correlated Electronstext