Figure 1

(a) Schematic energy level diagram for electrons on helium in a perpendicular magnetic field. For simplicity only the lowest bound state and the continuum states are shown for the $n=0$ and $n=1$ Landau levels. Also shown are the polarizations of microwave radiation needed to drive transitions from the $n=0$ bound state to the $n=0$ continuum and the $n=1$ bound state. (b) The Fano lineshape of Eq. (5) plotted for asymmetry parameter $q=0$ (dashed red curve), $q=1$ (dotted blue curve), and $q=2$ (solid green curve). The horizontal axis is scaled by the energy width of the line. (c) The phase shift for perturbed continuum states (solid red curve) calculated by numerical solution of the full Schrödinger equation shows the jump of $\pi$ relative to the unperturbed phase shift (dotted blue curve) as predicted by the approximate truncation to Fano's model. The energy is in natural units defined in the text.