We investigate the local density of states (LDOS) for non-interacting
electrons in a hard wall ellipse in the presence of a single non-magnetic
scattering center. Using a T-matrix analysis we calculate the local Green's
function and observe a variety of quantum mirage effects for different impurity
positions. Locating the impurity near positions with LDOS maxima for the
impurity free corral can either lead to a reduction or an enhancement of the
LDOS at the mirror image point, i.e. a mirage or anti-mirage effect, or even
suppress LDOS maxima in the entire area of the corral.Comment: 6 pages, 7 figure