S. Debievre et J. Renaud, OFF-DIAGONAL MATRIX-ELEMENTS IN THE SEMICLASSICAL LIMIT, Journal of physics. A, mathematical and general, 29(23), 1996, pp. 585-588
We give a very simple proof of the convergence of the non-diagonal Wig
ner functions of the harmonic oscillator eigenstates W-n,W-n+k(A,phi)
to delta(A-A(0))e(ik phi) in the semiclassical limit n-->infinity, HBA
R-->0 and nHBAR=A.