Power spectrum analysis of experimental Sinai quantum billiards

We perform a power spectrum analysis of energy level fluctuations in experimental quantum Sinai billiards. In spite of experimental limitations we find the 1/f1/f behavior expected for quantum chaotic systems. Moreover, the deviations observed at low frequencies are easily explained within the semiclassical periodic orbit theory. In conclusion, it is shown that the power spectrum analysis of energy level fluctuations is a robust signature of quantum chaos.