AI 中文总结
研究如何从经典声子模型出发，通过经典哈密顿形式主义恢复单无自旋粒子相对论量子力学特征，定义连续泊松括号，建立与量子力学形式的联系并恢复庞加莱群变换及代数。
AI 中文摘要
在本系列第一部分，已展示单粒子薛定谔方程及非相对论量子可观测量可从纯经典声子模型通过牛顿运动方程得到。本文聚焦于将经典哈密顿形式主义应用于同一声子系统以恢复单无自旋粒子相对论量子力学特征。利用声子模型的经典性质定义经典可观测量间的连续泊松括号，恢复可观测量动力学等，还建立了与量子形式的联系及恢复庞加莱群变换和代数。
英文摘要
In the first part of this series we have shown how the Schrodinger equation for a single particle and the corresponding non relativistic quantum observables can be obtained from a purely classical phonon model through the Newtonian equations of motion. In this work we focus instead on how the classical Hamiltonian formalism applied to the same phonon system allows to recover the feature of relativistic quantum mechanics for a single spinless particle. Using the classical nature of the phonon model, we naturally define continuous Poisson brackets between classical observables, which allows to recover the dynamics of such observables, i.e. the Ehrenfest relations associated to real-valued Klein-Gordon fields. The Poisson brackets also permits to obtain the generic form of constants of motions, thus generalizing the concept of inner products and momentum on Klein-Gordon fields. We then connect the formalism of real-valued classical functionals with that of hermitian operators and complex-valued wave functions. This is done through the introduction of a non-local complex-valued change of variables which allows to rewrite the real-valued Klein-Gordon equation in a form akin to the Schrodinger equation, and the classical observables as quantum expectation values. Then, we show how this change of variables allows to rewrite the classical Poisson brackets as commutators of hermitian operators. This points out the strict equivalence between the Heisenberg formalism and the formalism of classical Poisson bracket. Eventually, we illustrate how the Poisson brackets allows to recover the transformations of Poincare group in 1+1 dimension together with its algebra. The latter makes the link between the Lorentz invariant inner product of Mostafazadeh and the Casimir invariant associated to the mass of particle.
