Knowledge and the measurement process

Diederik Aerts

We explain the quantum structure as due to the presence of two effects, (a) a real change of state of the entity under influence of the measurement and, (b) a lack of knowledge about a deeper deterministic reality of the measurement process. We present a quantum machine, where we can illustrate in a simple way how the quantum structure arises as a consequence of the two mentioned effects. We introduce a parameter epsilon that measures the size of the lack of knowledge on the measurement process, and by varying this parameter, we describe a continuous evolution from a quantum structure (maximal lack of knowledge) to a classical structure (zero lack of knowledge). We show that for intermediate values of epsilon we find a new type of structure, that is neither quantum nor classical. We apply the model that we have introduced to situations of lack of knowledge about the measurement process appearing in other regions of reality. More specifically we investigate the quantum-like structures that appear in the situation of psychological decision processes, where the subject is influenced during the testing, and forms some of his opinions during the testing process. Our conclusion is that in the light of this explanation, the quantum probabilities are epistemic and not ontological, which means that quantum mechanics is compatible with a determinism of the whole.

Roger Balian

F. F. Fanchini, Göktuğ Karpat, Barış Çakmak +6 more

The degree of non-Markovianity of quantum processes has been characterized in several different ways in the recent literature. However, the relationship between the non-Markovian behavior and the flow of information between the system and the environment through an entropic measure has not been yet established. We propose an entanglement-based measure of non-Markovianity by employing the concept of assisted knowledge, where the environment $\mathcal{E}$, acquires information about a system $\mathcal{S}$, by means of its measurement apparatus $\mathcal{A}$. The assisted knowledge, based on the accessible information in terms of von Neumann entropy, monotonically increases in time for all Markovian quantum processes. We demonstrate that the signatures of non-Markovianity can be captured by the nonmonotonic behavior of the assisted knowledge. We explore this scenario for a two-level system undergoing a relaxation process, through an experimental implementation using an optical approach that allows full access to the state of the environment.

Paul Busch, PEKKA J. LAHTI

Luigi M. Bianchi

Oleg Curbatov

The paper entitled “From the Quantum Act to a Convergent Pact for Quantum Technologies for the Future”* by Oleg Curbatov aims to draw attention to and open discussion on the introduction of new conceptual objects such as “quantum knowledge systems” and “quantum rationality agents,”which constitute original characteristics of the functioning of quantum devices. In the first part, these concepts have already been presented within the framework of various consultations relating to the development of future normative instruments, notably within the European Commission in the context of the future Quantum Act, as well as before several bodies of the United Nations system, including UNESCO, UNCTAD, and ECOSOC. Quantum physics has demonstrated that the act of measurement directly intervenes in the observed phenomenon. This property suggests that the acquisition of information forms an integral part of the physical process itself. From this perspective, the emergence of “quantum knowledge systems” modifies their properties at the very moment they are observed or appropriated by observers or their digital analogues (AI-Digital-Systems). This results in a process of knowledge transformation that may be described through three complementary levels: 1. The potential state of non-local knowledge, corresponding to a set of probabilistic possibilities and constituting the prerequisite for the emergence of non-local knowledge systems;2. The act of transformation, associated with observation, measurement, and information transfer during the interaction between the observer and the non-local knowledge system;3. Local knowledge, corresponding to the observed outcome, that is, knowledge that has become localized and actualized following the observation process.These “quantum knowledge systems” possess specific properties that may be associated with different forms of rationality (including quantum rationality) and with the behaviors that derive from them. They therefore invite a distinction between several regimes of legal responsibility and normative governance depending on the state of the knowledge system under consideration. Before the act of measurement, when knowledge remains in a potential, non-local, and probabilistic state, the issues primarily concern the conditions for protecting systems and governing the informational possibilities that may be generated. After the act of measurement, when knowledge becomes localized, observable, and appropriable by identified actors, legal responsibilities emerge that are more directly linked to the emergence, use, dissemination, ownership, traceability, and effects produced by these “knowledge systems.”In this respect, the act of measurement could be recognized as a legal act of responsibility in its own right with regard to the quantum knowledge conversion systems that it triggers, insofar as it simultaneously modifies the state of the knowledge system, the information accessible to actors, and the effects that may result from it.Such an approach would open the way to a new reflection on the liability regimes applicable to quantum technologies, not only according to their uses or outcomes, but also according to the transformations of 'quantum knowledge systems” produced during the act of measurement itself. From this perspective, the act of measurement appears as an act of knowledge governance. It constitutes the point of transition between different states of a knowledge system and could, as such, be recognized as a generating event of legal responsibility. Responsibility would therefore not relate solely to the effects produced by quantum technology, but also to the processes of conversion of quantum knowledge systems that it initiates, transforms, and renders legally accountable. This distinction leads to the consideration that each form of “quantum knowledge system” may fall under specific normative frameworks, both at the national and international levels, depending on its degree of design and protection, in accordance with the “Quantum-Safe-by-Design” principle, its implementation, its state of localization, and its appropriation by different actors. Would this idea of now considering the quantum domain in terms of states and knowledge systems change the framework for the development of normative instruments? Indeed, if quantum physics distinguishes different states before and after the act of measurement, it may be relevant to examine whether the knowledge systems associated with these states should likewise be subject to differentiated legal and normative regimes. Questions of responsibility, governance, protection, and use of knowledge could thus be assessed differently depending on whether one is situated before the act of measurement, in a potential state of knowledge, or after the act of measurement, in a state of non-localized or localized knowledge. The International Association of University Professors and Lecturers (IAUPL), an organization holding General Consultative Status with the United Nations ECOSOC, proposed during the joint meetings of the United Nations General Assembly and ECOSOC, 05/05/2026, the ECOSOC Science, Technology and Innovation Forums (2025, 2026), the 221st and 223rd sessions of UNESCO’s Executive Board, as well as at the 43rd UNESCO General Conference (2025), to initiate a reflection with Member States on the development of a “Convergent Pact for Quantum Technologies for the Future.”This proposal is based on the principles of convergence of knowledge, “ quantum knowledge systems,” and convergent technologies, as well as on the convergence of objectives pursued and effects produced by quantum technologies in the scientific, educational, economic, social, and institutional domains. The second part of this presentation will focus on the very nature of “convergence,” a notion raised during consultations relating to the future European Quantum Act, for which IAUPL submitted its consultative response in December 2025. It will examine how these principles of “Convergence” could be systematized within future normative instruments and how they could ultimately spread and generate impact at the international level within the framework of global governance of quantum technologies and the knowledge systems associated with them.