Measurement of long-range wavefunction correlations in an open microwave   billiard
  We investigate the statistical properties of wavefunctions in an open chaotic cavity. When the number of channels in the openings of the billiard is increased by varying the frequency, wavefunctions cross over from real to complex. The distribution of the phase rigidity, which characterizes the degree to which a wavefunction is complex, and long-range correlations of intensity and current density are studied as a function of the number of channels in the openings. All measured quantities are in perfect agreement with theoretical predictions. 
Y.-H. Kim, U. Kuhl, H.-J. St\"ockmann, P.W. Brouwer