  Spectral statistics of quantum oval billiard whose classical dynamical system
shows bifurcations is numerically investigated in terms of the two-point
correlation function (TPCF) which is defined as the probability density of
finding two levels at a specific energy interval. The eigenenergy levels at
bifurcation point is found to show anomalous accumulation which is observed as
a periodic spike oscillation of the TPCF. We analyzed the eigenfunctions
localizing onto the various classical trajectories in the phase space and found
that the oscillation is supplied from a limited region in the phase space,
which contains the bifurcating orbit. We also show that the period of the
oscillation is in good agreement with the period of a contribution from the
bifurcating orbit to the semiclassical TPCF obtained by Gutzwiller trace
formula.
