  Interference of quasi bound states is studied in a ballistic electron ripple
waveguide with two ripple cavities whose distance apart can be varied. This
system is the waveguide analog of Dicke's model for two interacting atoms in a
radiation field. Dicke's model has resonances whose widths change in an
oscillatory manner as the distance between the atoms is varied. Resonances that
form in a bi-ripple waveguide behave in a manner that has some similarity to
Dicke's system, but also important differences. We numerically investigate the
behavior of resonance widths in the waveguide as the distance between the two
ripple cavities changes and we find that the resonance widths oscillate with
variation of distance, but the coupling does not decrease as it does in Dicke's
system. We discuss differences between our waveguide system and other systems
showing the analogous of Dicke effect. We also study S-matrix pole trajectories
and find that they rotate in counterclockwise direction on a circle in the
complex energy plane.
