Global and Local Spin Squeezing in Coupled Quantum Kicked Tops Model

We investigate the global and the local spin squeezing in a weakly coupled quantum kicked tops system. Two different situations are considered: (i) N=1 and (ii) N=30 for each subsystem, corresponding to quantum and classical cases, respectively. In the first case, since the two subsystems have no spin squeezing, the global squeezing completely originates from quantum correlations. For the second one, the global spin squeezing is enhanced over the local one. Due to the chaotic nature of the system, the spin squeezing is sensitive to the initial state. In chaotic region, the squeezing vanished time is much shorter than that in the regular region.