On superposition and entropy in quantum dynamics

Antonio Zecca A

Md. Shaikhul Hadis Nazat

Abstract We introduce the Superpositional Asymmetry Principle (SAP), an effective theoretical framework linking symmetry-breaking dynamics, entropy production, and the suppression of quantum coherence in open quantum systems. Rather than modifying quantum mechanics or postulating a fundamental collapse mechanism, SAP treats classicalization as an emergent, coarse-grained phenomenon described entirely within standard open-system dynamics. By decomposing the system action into symmetry-preserving and symmetry-breaking contributions, we propose a phenomenological scaling law for decoherence rates governed by the ratio of asymmetric to symmetric action intensities and the local von Neumann entropy. The resulting dynamics are formulated within the Lindblad master-equation formalism. SAP unifies symmetry breaking, decoherence, and entropy into a single effective principle and yields experimentally testable predictions distinct from mass-based objective collapse models.

Göran Lindblad

Amit Anand, Anne-Catherine de la Hamette, Robert Mann +1 more

While the superposition of quantum evolutions is known to produce interference effects, the interference between evolutions with regular and chaotic classical limits remains largely unexplored. Here, we use a Mach-Zehnder interferometer to investigate the superposition of two quantum evolutions, implemented via post-selection, and to compare it with the corresponding classical mixture. The quantum kicked top provides a natural platform for this study, as its classical dynamics ranges from regular to mixed to fully chaotic depending on the Hamiltonian parameters. We show that when a regular evolution is superposed with a chaotic one, the resulting subsystem entropy can exceed that of the classical mixture, provided the contribution of the chaotic branch dominates in the superposed quantum evolution. We further demonstrate that entropy production in such superpositions is strongly influenced by the structure of the underlying classical phase space. We further show that increased entropy generation can occur for purely regular dynamics at small values of the chaos parameter, given an appropriate choice of post-selection. These results reveal a nontrivial interplay between classical chaos and quantum interference in superposed quantum dynamics

Igor Jex, Arkadiusz Orłowski

We report on the time evolution of the Wehrl entropy in a Kerr-like medium. We show that the Wehrl entropy gives a clear signature for the formation of finite superpositions of coherent states (cat-like states). In addition, the actual value of the Wehrl entropy at the time of a superposition formation gives the number of coherent components taking part in the superposition.