We present a general formalism with the aim of describing the situation of an entity, how it is, how it reacts to experiments, how we can make statistics with it, and how it ‘changes ’ under the influence of the rest of the universe. Therefore we base our formalism on the following basic notions: (1) the states of the entity; they describe the modes of being of the entity, (2) the experiments that can be performed on the entity; they describe how we act upon and collect knowledge about the entity, (3) the probabilities; they describe our repeated experiments and the statistics of these repeated experiments, (4) the symmetries; they describe the interactions of the entity with the external world without being experimented upon. Starting from these basic notions we formulate the necessary derived notions: mixed states, mixed experiments and events, an eigen closure structure describing the properties of the entity, an ortho closure structure introducing an orthocomplementation, outcome determination, experiment determination, state determination and atomicity giving rise to some of the topological separation axioms for the closures. We define the notion of sub entity in a general way and identify the morphisms of our structure. We study specific examples in detail in the light of this formalism: a classical deterministic entity and a quantum entity described by the standard quantum mechanical formalism. We present a possible solution to the problem of the description of sub entities within the standard quantum mechanical procedure using the tensor product of the Hilbert spaces, by introducing a new completed quantum mechanics in Hilbert space, were new ‘pure ’ states are introduced, not represented by rays of the Hilbert space.

The aim of this article is to represent the general description of an entity by means of its states, contexts and properties. The entity that we want to describe does not necessarily have to be a physical entity, but can also be an entity of a more abstract nature, for example a concept, or a cultural artifact, or the mind of a person, etc..., which means that we aim at very general description. The effect that a context has on the state of the entity plays a fundamental role, which means that our approach is intrinsically contextual. The approach is inspired by the mathematical formalisms that have been developed in axiomatic quantum mechanics, where a specific type of quantum contextuality is modelled. However, because in general states also influence context – which is not the case in quantum mechanics – we need a more general setting than the one used there. Our focus on context as a fundamental concept makes it possible to unify ‘dynamical change ’ and ‘change under influence of measurement’, which makes our approach also more general and more powerful than the traditional quantum axiomatic approaches. For this reason an experiment (or measurement) is introduced as a specific kind of context. Mathematically we introduce a state context property system as the structure to describe an entity by means of its states, contexts and properties. We also strive from the start to a categorical setting and derive the morphisms between

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Consider two spatially separated agents, Alice and Bob, each of whom is able to make local quantum measurements, and who can communicate with each other over a purely classical channel. As has been pointed out by a number of authors, the set of mathematically consistent joint probability assignments (“states”) for such a system is properly larger than the set of quantum-mechanical mixed states for the joint Alice-Bob system. Indeed, it is canonically isomorphic to the set of positive (but not necessarily completely positive) linear maps L(HA) → L(HB) from the bounded linear operators on Alice’s Hilbert space to those on Bob’s, satisfying Tr (φ(1)) = 1. The present paper explores the properties of these states. We review what is known, including the fact that allowing classical communication between parties is equivalent to enforcing “noinstantaneous-signalling” (“no–influence”) in the direction opposite the communication. We establish that in the subclass of “decomposable”

Abstract. A ‘state property system ’ is the mathematical structure which models an arbitrary physical system by means of its set of states, its set of properties, and a relation of ‘actuality of a certain property for a certain state’. We work out a new axiomatization for standard quantum mechanics, starting with the basic notion of state property system, and making use of a generalization of the standard quantum mechanical notion of ‘superposition ’ for state property systems. 1.

Entanglement plays a pervasive role nowadays throughout quantum information science, and at the same time provides a bridging notion between quantum information science and fields as diverse as condensed-matter theory, quantum gravity, and quantum foundations. In recent years, a notion of Generalized Entanglement (GE) has emerged [H. Barnum et al, Phys. Rev. A 68, 032308 (2003); L. Viola et al, Contemp. Math. 381, 117 (2005)], based on the idea that entanglement may be directly defined through expectation values of preferred observables – without reference to a preferred subsystem decomposition. Preferred observables capture the physically relevant point of view, as defined by dynamical, operational, or fundamental constraints. While reducing to the standard entanglement notion when preferred observables are restricted to arbitrary local observables acting on individual subsystems, GE substantially expands subsystem-based entanglement theories, in terms of both conceptual foundations and range of applicability. Remarkably, the GE framework allows for non-trivial entanglement to exist within a single, indecomposable quantum system, demands in general a distinction between quantum separability and absence of entanglement, and naturally extends to situations where existing approaches may not be directly useful – such as entanglement in arbitrary convex-cones settings and entanglement for indistinguishable quantum particles. In this paper, we revisit the main motivations leading to GE, and summarize the accomplishments and prospects of the GE program to date, with an eye toward conceptual developments and implications. In particular,

urt, World Scientific, Singapora (2002). advances, that will demand a more straightforward connection between the theory and the type of manipulations and control to be executed in the laboratory. Although operational quantum mechanics is in full development, we must admit that the time has not yet come for it to function as a `better to apply and more easy to use' theory for experimentation. The reason is that the operational quantum structures that have been elaborated, while carefully but boldly aiming at physical clearness and transparency, stumble upon a lot of problems of purely technical mathematical nature. Quantum mechanics is not only conceptually a very di#cult theory, it entails also a very sophisticated mathematical apparatus. It becomes even more and more clear that both dimensions of di#culty, the conceptual one and the mathematical structural one, are linked in a profound way. It has been shown that some of the deep conceptual problems of quantum mechanics -- the so

The term quantum logic has different connotations for different people, having been considered as everything from a metaphysical attack on classical reasoning to an exercise in abstract algebra. Our aim here is to give a uniform presentation of what we call operational quantum logic, highlighting both its concrete physical origins and its purely mathematical structure. To orient readers new to this subject, we shall recount some of the historical development of quantum logic, attempting to show how the physical and mathematical sides of the subject have influenced and enriched one another. 1 This paper is a slightly modified version of the introductory chapter to the volume B. Coecke,

The term quantum logic has different connotations for different people, having been considered as everything from a metaphysical attack on classical reasoning to an exercise in abstract algebra. Our aim here is to give a uniform presentation of what we call operational quantum logic, highlighting both its concrete physical origins and its purely mathematical structure. To orient readers new to this subject, we shall recount some of the historical development of quantum logic, attempting to show how the physical and mathematical sides of the subject have influenced and enriched one another. 1 This paper is a slightly modified version of the introductory chapter to the volume B. Coecke,