Classical fluctuations and semiclassical matrix elements
  We discuss the fluctuation properties of diagonal matrix elements in the semiclassical limit in chaotic systems. For extended observables, covering a phase space area of many times Planck's constant, both classical and quantal distributions are Gaussian. If the observable is a projection onto a single state or an incoherent projection onto several states classical and quantal distribution differ, but the mean and the variance are still obtainable from classical considerations. 
Bruno Eckhardt (1), Imre Varga (1,2) and Peter Pollner (1,3) ((1)   Philipps Universitaet Marburg, (2) Budapest University o...