Kicked Top
The kicked top is a paradigm of quantum chaos. A quantum spin-J evolves under a free precession plus periodic delta-function kicks:
H = p·J_y + κ/(2J)·J_z²·δ_T(t).
The Husimi Q-function projects the quantum state onto coherent states on the sphere, revealing the semiclassical structure. As kicking strength κ increases, regular tori dissolve into chaotic seas — quantum scars mark unstable classical orbits.
quantum chaos
Husimi Q-function
coherent states
semiclassical