INTERPOLATING ENSEMBLES OF RANDOM UNITARY MATRICES

We investigate transitions between ensembles of unitary random matrice s modeling changes of statistical properties of quantum chaotic system s which are periodically time dependent. The transitions simulating ch ange of integrability are modeled with the help of numerically generat ed one-parameter families of ensembles interpolating between an ensemb le of diagonal unitary matrices and a circular unitary or circular ort hogonal ensemble. In an analogous manner we describe transitions betwe en circular orthogonal and unitary ensembles corresponding to the time -reversal symmetry-breaking perturbation of a chaotic system. In all c ases we present results concerning statistics of the quasienergy level s and eigenvectors.