Parametric-curvature distribution in quantum kicked tops

We report a numerical study of the parametric sensitivity of quantum kicked tops in the classically chaotic regime where their quasienergy spectrum is irregular. We calculate the statistical distribution of the level curvatures defined as the second derivative of the eigenphases of the Floquet operator with respect to the parameter. We show that the curvature density for the orthogonal, unitary, and symplectic systems decreases, respectively, as ‖K${\mathrm{\Vert }}^{\mathrm{-}3}$, ‖K${\mathrm{\Vert }}^{\mathrm{-}4}$, and ‖K${\mathrm{\Vert }}^{\mathrm{-}6}$ for large curvatures ‖K‖, in agreement with theory.