We introduce the Quantum Harp (QH), a thought experiment designed to explore the con-ceptual limits of quantum entanglement, information transfer, and spacetime structure. Theexperiment postulates a mechanism enabling instantaneous state updates between arbitrarilydistant systems sharing a hypothetical, perfect entanglement resource (the "Harp"). We rigor-ously define the operational premise of the QH interaction function, H. Analyzing the QH withinthe frameworks of Special and General Relativity reveals apparent paradoxes related to simul-taneity and causality. We interpret them constructively as opportunities and as highlightingthe extreme physical conditions or fundamentally new physics (potentially related to wormholes, Closed Timelike Curves, or quantum gravity non-locality) required forsuch a mechanism to operate consistently. We explore the basic implications for informationencoding and decoding using single vs. multiple entangled "strings," and introduce multi-party(Alice, Bob, Charlie) scenarios revealing potential for instant broadcast and correlation controlunder the QH premise. The Quantum Harp experiment serves not as a proposal for a real de-vice, but as a sharply defined theoretical construct acting as a theoretical scenario to investigatethe interplay between quantum non-locality, relativistic causality, and the fundamental natureof information transfer in physics and potentially novel computational paradigms. The coreformalism defining the QH interaction (H) and the resulting system dynamics are presentedherein.
We introduce the Quantum Harp (QH), a thought experiment designed to explore the con-ceptual limits of quantum entanglement, information transfer, and spacetime structure. Theexperiment postulates a mechanism enabling instantaneous state updates between arbitrarilydistant systems sharing a hypothetical, perfect entanglement resource (the "Harp"). We rigor-ously define the operational premise of the QH interaction function, H. Analyzing the QH withinthe frameworks of Special and General Relativity reveals apparent paradoxes related to simul-taneity and causality. We interpret them constructively as opportunities and as highlightingthe extreme physical conditions or fundamentally new physics (potentially related to wormholes, Closed Timelike Curves, or quantum gravity non-locality) required forsuch a mechanism to operate consistently. We explore the basic implications for informationencoding and decoding using single vs. multiple entangled "strings," and introduce multi-party(Alice, Bob, Charlie) scenarios revealing potential for instant broadcast and correlation controlunder the QH premise. The Quantum Harp experiment serves not as a proposal for a real de-vice, but as a sharply defined theoretical construct acting as a theoretical scenario to investigatethe interplay between quantum non-locality, relativistic causality, and the fundamental natureof information transfer in physics and potentially novel computational paradigms. The coreformalism defining the QH interaction (H) and the resulting system dynamics are presentedherein.
This work presents a minimal reinterpretation of quantum entanglement based solely on the causal structure inherent in relativistic spacetime. No new physical entities, parameters, or modifications to existing theories are introduced.The discussion remains entirely within the established frameworks of general relativity and quantum mechanics, with particular emphasis on Lorentz invariance and relativistic causality. The central idea is that the causal structure of spacetime is unique and invariant, while spatial separation corresponds to different references (foliations) to this structure rather than its duplication.Within this viewpoint, quantum entanglement is understood as a local readout of correlations already encoded in a shared causal structure, without invoking nonlocal influences or superluminal information transfer. This document is intended as a conceptual clarification and archival record rather than a proposal of a new theory.It is provided to preserve a logically consistent interpretation that may be of interest for future foundational discussions.
Abstract Quantum mechanics and relativity are two of the most successful theoretical frameworks in modern physics, yet their conceptual foundations remain difficult to reconcile at the deepest level. Quantum theory describes physical systems through states, observables, probabilities, measurement contexts, superposition, entanglement, and nonclassical correlations. Relativity describes physical processes through space-time structure, causal order, invariant physical law, observer-dependent decomposition of time and space, and constraints on signal propagation. This article examines the conceptual relationship between quantum measurement, relativistic causality, and space-time description. The purpose is not to present a mathematical unification but to analyze how the two frameworks organize physical explanation differently and where their interpretive tensions arise. Special attention is given to the measurement problem, the status of quantum states, the role of observers and reference frames, the meaning of locality, the distinction between correlation and causal influence, and the challenge of describing quantum processes without privileging a single global time. The article argues that many apparent conflicts between quantum theory and relativity result from importing classical intuitions into domains where they no longer apply. Quantum entanglement does not permit controllable faster-than-light communication, yet it challenges classical separability. Relativity forbids superluminal signaling, yet it does not require that all physically meaningful correlations be reducible to local classical properties. Measurement introduces another difficulty because standard quantum theory often describes state update in a way that appears instantaneous, while relativistic space-time does not provide a universal present. The discussion develops a conceptual framework in which quantum measurement is treated as a physical interaction, relativistic causality as a constraint on operational influence, and space-time description as an organizing structure for events rather than a simple background stage. This analysis is relevant for quantum field theory, quantum information, relativistic quantum foundations, and future approaches to quantum gravity.
This paper investigates the theoretical feasibility of quantum information transmission leveraging artificially induced spacetime distortions. The core claim proposes that controlled spacetime curvature, mimicking the effects predicted by General Relativity, can facilitate quantum information transfer between entangled particles over distances exceeding the limitations imposed by the speed of light. The proposed mechanism utilizes a specifically designed apparatus capable of generating a localized, simulated spacetime distortion. This distortion, in turn, alters the effective distance between entangled particles, allowing for instantaneous information correlation despite the spatial separation. Mathematical modeling and key equations are presented to illustrate the theoretical framework, including the relationship between spacetime curvature, quantum entanglement, and information transfer rates. The potential implications of this approach for future quantum communication technologies are discussed, acknowledging the significant technological challenges involved in realizing such a system. The central focus remains on the theoretical exploration of this novel paradigm, providing a foundational understanding for potential future research.
Closed timelike curves (CTCs) challenge our conception of causality by allowing information to loop back into its own past. Any consistent description of such scenarios must avoid time-travel paradoxes while respecting the no-new-physics principle, which requires that the set of operations available within any local spacetime region remain unchanged, irrespective of whether CTCs exist elsewhere. Within an information-theoretic framework, this leads to process functions: deterministic classical communication structures that remain logically consistent under arbitrary local operations, yet can exhibit correlations incompatible with any definite causal order - a phenomenon known as non-causality. In this work, we establish a correspondence between process functions and unambiguous complete product bases, i.e. product bases in which every local state belongs to a unique local basis. This equivalence implies that non-causality of process functions is exactly mirrored by quantum nonlocality without entanglement (QNLWE) - the impossibility of perfectly distinguishing separable states using local operations and causal classical communication - for such bases. Our results generalize previous special cases to arbitrary local dimensions and any number of parties, enable systematic constructions of non-causal process functions and unambiguous QNLWE bases, and implies, inter alia, that bipartite unambiguous QNLWE bases do not exist. Finally, this work reveals an unexpected connection between causal and non-signaling inequalities: every process function both maximally violates an associated causal inequality and yields a corresponding Bell inequality that admits no violation.
Quantum mechanics has achieved unparalleled success as an operational theory, describing a wide range of experiments to remarkable accuracy. However, the physical foundations on which it rests remain as puzzling as they were a century ago, and a concise statement of the physical principles that underlie quantum mechanics is still outstanding. One promising approach holds that these principles should be formulated in terms of information, since many of the counter-intuitive effects in quantum theory concern questions such as what one can know about a quantum system and how the information encoded therein can be processed and distributed between parties. Another challenging feature of quantum theory is its incompatibility with the other cornerstone of modern physics, general relativity. In order to reconcile the two, one must identify and retain only the essential concepts and principles of each theory, and in the case of general relativity, causality has been identified as such a concept. This raises the question of how our classical understanding of causality must change when quantum theory is taken into account. In order to address these questions about information, knowledge and causality, I turn to the framework of causal models. In classical statistics, causal models explain the relations among a set of variables in terms of causal influences, which makes them a powerful tool for structuring our knowledge about complex systems and developing strategies for interacting with them. More importantly, the framework provides the conceptual underpinnings and mathematical methods for addressing questions about causation, information and knowledge in a rigorous manner. In this thesis, I develop a version of the classical causal models framework that is compatible with quantum theory and explore its physical implications. \n \n \nA first step is to define quantum versions of fundamental elements such as variables, conditionals and belief propagation rules. This allows one to consider the question of what one can come to know about a quantum variable from the point of view of causal modelling. The conditionals relating quantum variables are found to have a richer structure than their classical counterparts, which can be exploited for the task of discerning causal relations given limited data -- a central problem in classical causal modelling. The mathematical properties of quantum conditionals also establish a correspondence between various classes of two-party correlations, such as bound and distillable entanglement, and the types of causal structures that can give rise to them, which may become a useful tool for entanglement theory and quantum information processing. In the context of open quantum systems dynamics, quantum causal models provide a clear physical explanation of not completely positive maps and, more broadly, of non-Markovian quantum dynamics. Finally, I consider the possibility of non-classical effects in the way that different causal mechanisms are combined -- that is, non-classical causal structures. For the simple case of two causally ordered variables, I propose indicators that witness different classes of combinations of causal mechanisms, including a non-classical mixture, and describe an experiment realizing examples of the different classes. \n \n \nAs these results illustrate, the framework of quantum causal models provides both greater conceptual clarity and a comprehensive mathematical formalism for studying a diverse set of problems, ranging from foundational questions to applications in open systems dynamics and the exploration of non-classical causal structures, which are likely to feature in a future theory of quantum gravity. The material presented in this thesis is intended as a foundation and inspiration for further applications of quantum causal models.