  Utilizing an adiabatic approximation method a bipartite qudit-oscillator
Hamiltonian is explicitly studied for low spin values in both strong and
ultrastrong coupling regimes. The quasiprobability densities on the hybrid
factorized phase space are introduced. Integrating over a sector of the
composite phase space, the quasiprobability distributions of the complementary
subsystem are recovered. In the strong coupling regime the qudit entropy
displays a pattern of quasiperiodic collapses and revivals, where the locally
minimum nonzero configurations appearing at rational fractions of the revival
time correspond to the spin kitten states. Starting with a bipartite
factorizable initial state the evolution to the nonclassical transitory spin
kitten states are displayed via the diagonal spin PQ-representation. The
formation of transient spin kitten states is further substantiated by
constructing the spin tomogram that employs the positive definite probability
distributions embodying the diagonal elements of the corresponding density
matrix in an arbitrarily rotated frame. As another manifestation of
nonclassicality the emergence of the spin squeezed states during the bipartite
evolution is observed. In the ultrastrong coupling domain a large number of
interaction dependent modes and their harmonics are generated. The consequent
randomization of the phases eliminates the quasiperiodicity of the system which
is now driven towards a stabilization of the entropy accompanied with
stochastic fluctuations around its stabilized value. Both in the strong and
ultrastrong coupling realms antibunching of the photoemission events are
realized particularly for the small spin values.
