  A change in boundary conditions (BC) from uniform Dirichlet to non-identical
BC on the edges of a triangular billiard often brings about a dramatic change
in quantum spectral fluctuations. We provide a theory for this based on
periodic orbits and show that non-identical BC on adjacent edges can lead to a
quantum splitting of periodic orbit families which results in a significant
change in the form factor. Thus, the classical spectrum alone cannot determine
quantum correlations.
