Spontaneous symmetry breaking and restricted superposition principle

Vladan Panković

A.S. Shumovskij, Vyacheslav I. Yukalov

Chuang Liu

This essay explores the nature of spontaneous symmetry breaking (SSB) in connection with a cluster of interrelated concepts such as Curie's symmetry principle, ergodicity, and chance and stability in classical systems. First, a clarification of the two existing senses of SSB is provided and an argument developed for a proposal for SSB, in which not only the possibilities but also the actual breakings are referred to. Second, a detailed analysis is given of classical SSB that answers the questions: (i) how we are justified in regarding it as a matter of chance, and (ii) why the breakings in it are equally probable. The answer provides some support to the applicability of ergodicity in special systems (such as ours).

K. Ziegler

Vladan Panković, Milan Predojević

In this work spontaneous (non-dynamical) breaking (effective hiding) of the unitary quantum mechanical dynamical symmetry (superposition) is considered. It represents an especial but very interesting case of the general formalism of the spontaneous symmetry breaking (effective hiding). Conceptual analogies with spontaneous breaking of the gauge symmetry in Weinberg-Sallam's electro-weak interaction are pointed out. Also, consequences of the spontaneous superposition breaking in the measurement process are discussed. Measurement can be considered as a typical Landau's continuous phase transition with spontaneous superposition breaking (effective hiding) effectively corresponding to collapse. Here critical values of the order parameters are determined by Heisenberg's uncertainty relations.

Yuanxin Li

In this paper, we propose a mechanism analogous to the spontaneous symmetry breaking to explain quantum measurement. It is actually a supplement to the decoherence theory. We introduce the effective potential between eigenstates and show that a wave function in a superposition of several eigenstates reduces to a single eigenstate due to the spontaneous-symmetry-breaking-like kinetic effect.