A Geometric Picture of the Wave Function: Fermi's Trick
  We show that there is a one-to-one correspondence between wave functions and surfaces in the position-momentum phase plane bounded by a closed curve satisfying an exact quantum condition refining the usual EBK condition. This is achieved using an old forgotten idea of Enrico Fermi. 
Maurice A. de Gosson
quant-ph math-ph math.MP physics.pop-ph