#### Alladi Ramakrishnan Hall

#### Generalized spin kitten states in a strongly coupled spin-oscillator system

#### M. Balamurugan

##### Department of Theoretical Physics, Madras University

*Utilizing an adiabatic approximation method, a bipartite qudit-oscillator*

Hamiltonian is studied for low-spin values (s=1 and s=3/2) 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 its complementary subsystem are recovered. In

the strong coupling regime, the qudit entropy displays a pattern of quasiperiodic

collapses and revivals. Starting with a bipartite factorizable initial state, we observe

that almost pure spin kitten type states dynamically develop at near-null values of

entropy. The Hilbert-Schmidt distance measure of these states puts them metrically

far away from the initial state. Other localized spin states form at locally minimum

but significantly large values of entropy. The evolution to the nonclassical transitory

spin states is displayed via the diagonal spin P-representation. 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 that also undergoes stochastic

fluctuations around a suitably stabilized value. In both the strong and ultrastrong

coupling realms, antibunching of the photoemission events is realized particularly for

the small spin values.

Done