Physical Review Letters
Microwave Studies of Billiard Green Functions and Propagators
J. Stein, H.-J. Stöckmann, Ulrich Stoffregen
Abstract
In a microwave transmission measurement the Green function $G({r,r}^{\ensuremath{'}},k)$ of a stadium billiard was determined as a function of ${r}^{\ensuremath{'}}$ and $k$ for fixed $r$. From this billiard wave functions were obtained including the sign, which was not available earlier. The propagator $K({r,r}^{\ensuremath{'}},t)$ was obtained by Fourier transform of $G({r,r}^{\ensuremath{'}},k)$. It is shown that $K({r,r}^{\ensuremath{'}},t)$ supplies a very suggestive picture of pulse propagation including pulse reconstruction by focusing effects. This can be considered as an experimental verification of a work of Tomsovic and Heller, who found that semiclassical dynamics can account for the quantum mechanical behavior of billiards over surprisingly long times.