Title:Exact semiclassical dynamics of generic Lipkin-Meshkov-Glick model

Abstract:Lipkin-Meshkov-Glick model is paradigmatic to study quantum phase transition in equilibrium or non-equilibrium systems and entanglement dynamics for a variety of disciplines. In thermodynamics limit, quantum fluctuations are negligible, its semiclassical dynamics in presence of only one nonlinear couplings, as a good benchmark to study quantum fluctuation in finite-size system, can be well obtained in terms of Jacobi elliptic functions. In this work, we extend this semiclassical analysis into the regime where both nonlinear interactions are present, and successfully obtain its exact solutions of semiclassical equations by constructing an auxiliary function that is a linear combination of the $y$ and $z$ component of the classical spin in thermodynamic limit. Taking implementation of Lipkin-Meshkov-Glick model in a Bose-Einstein condensate setup as an example, we figure out all classical dynamical modes, specially find out mesoscopic self-trapping mode in population and phase-difference space even persists in presence of both nonlinear couplings. Our results would be useful to analyze dynamical phase transitions and entanglement dynamics of Lipkin-Meshkov-Glick model in presence of both nonlinear couplings.