M. Farotti | Search arXiv

arXiv2026

A no-go theorem for irreversibility in arbitrary realizations of the collapse dynamics

We study finite dimensional quantum systems with arbitrary collapse events, establishing a structural no-go for operational irreversibility along arbitrary realizations of the collapse dynamics. More precisely, we prove that, for every choice of a physically admissible trajectory (i.e., collapse outcomes having nonzero Born weight) assigned to each state, there exists a nonempty topologically closed subset of the projective state space within which any two states can be connected with arbitrarily fine Fubini-Study precision and arbitrarily small integrated energetic cost. This shows that the preservation of information along observed realizations of outcomes guarantees islands of quasi-reversibility, while genuine irreversibility requires additional ingredients such as non-compactness or information erasure.

math-ph↗

arXiv2026

On linearly ordered sets of chain components

In a dynamical system $(X,f)$, with $X$ a compact metric space, the chain components, the fundamental building blocks in the Conley decomposition of dynamics, have a natural partial order induced by the chain relation between points. Although chain components are crucial for understanding the long-term behavior of topological systems, they have not been widely studied from the point of view of poset theory. In this work, we pursue this line of research, considering both the case in which $f$ is a continuous map and the general case in which no regularity assumption is made. Our main results are that, if $f$ is continuous: - the chain components poset cannot be linearly and densely ordered; - every countable well-order with a maximum is the order type of the chain components poset of an interval map. If no regularity assumption is made: - there is a dynamical system on the interval whose chain components poset is countable and densely ordered; - the chain components poset has at least one minimal element. These results, bridging dynamical systems and order theory, highlight both the structural constraints and the possibilities for the chain components posets.

math.DS↗