  We present a direct mapping between the quantum optomechanical problem of the
atoms harmonically trapped in the vicinity of a chiral waveguide and a
generalized quantum Rabi model and discuss the analogy between the
self-organization of atomic chains in photonic structures and Dicke-like
quantum phase transitions in the ultrastrong coupling regime. We extend the
class of the superradiant phase transitions for the systems possessing
$\mathbb{Z}_3$ rather than parity $\mathbb{Z}_2$ symmetry and demonstrate the
emergence of the multicomponent Schrodinger cat ground states in these systems.
