Experimental investigation of nodal domains in the chaotic microwave rough billiard.

We present the results of experimental study of nodal domains of wave functions (electric field distributions) lying in the regime of Shnirelman ergodicity in the chaotic half-circular microwave rough billiard. Nodal domains are regions where a wave function has a definite sign. The wave functions PsiN of the rough billiard were measured up to the level number N=435 . In this way the dependence of the number of nodal domains [symbol: see text]N on the level number N was found. We show that in the limit N-->infinity a least squares fit of the experimental data reveals the asymptotic number of nodal domains [symbol: see text]N/N approximately equal to 0.058+/-0.006 that is close to the theoretical prediction [symbol: see text]N/N approximately equal to 0.062 . We also found that the distributions of the areas s of nodal domains and their perimeters l have power behaviors ns is proportional to s(-tau) and nl is proportional to l(-tau'), where scaling exponents are equal to tau=1.99+/-0.14 and tau'=2.13+/-0.23 , respectively. These results are in a good agreement with the predictions of percolation theory. Finally, we demonstrate that for higher level numbers N approximately equal to 220-435 the signed area distribution oscillates around the theoretical limit SigmaA approximately 0.0386 N(-1) .