Results for 'Quantum state of a composite system'

999 found
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  1.  28
    Description of Composite Quantum Systems by Means of Classical Random Fields.Andrei Khrennikov - 2010 - Foundations of Physics 40 (8):1051-1064.
    Recently a new attempt to go beyond QM was performed in the form of so-called prequantum classical statistical field theory (PCSFT). In this approach quantum systems are described by classical random fields, e.g., the electron field or the neutron field. Averages of quantum observables arise as approximations of averages of classical variables (functionals of “prequantum fields”) with respect to fluctuations of fields. For classical variables given by quadratic functionals of fields, quantum and prequantum averages simply coincide. In (...)
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  2.  46
    Quantum Incompressibility of a Falling Rydberg Atom, and a Gravitationally-Induced Charge Separation Effect in Superconducting Systems.R. Y. Chiao, S. J. Minter, K. Wegter-McNelly & L. A. Martinez - 2012 - Foundations of Physics 42 (1):173-191.
    Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous, and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like object, when both objects are dropped from the same height above the Earth’s surface. This indicates that, apart (...)
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  3. Discerning Fermions.Simon Saunders & F. A. Muller - 2008 - British Journal for the Philosophy of Science 59 (3):499 - 548.
    We demonstrate that the quantum-mechanical description of composite physical systems of an arbitrary number of similar fermions in all their admissible states, mixed or pure, for all finite-dimensional Hilbert spaces, is not in conflict with Leibniz's Principle of the Identity of Indiscernibles (PII). We discern the fermions by means of physically meaningful, permutation-invariant categorical relations, i.e. relations independent of the quantum-mechanical probabilities. If, indeed, probabilistic relations are permitted as well, we argue that similar bosons can also be (...)
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  4. Towards unified field theory: Quantitative differences and qualitative sameness.Mael A. Melvin - 1982 - Synthese 50 (3):359 - 397.
    A survey is given of the concepts of interaction (force) and matter, i.e., of process and substance. The development of these concepts, first in antiquity, then in early modern times, and finally in the contemporary system of quantum field theory is described. After a summary of the basic phenomenological attributes (coupling strengths, symmetry quantities, charges), the common ground of concepts of quantum field theory for both interactions and matter entities is discussed. Then attention is focused on the (...)
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  5. Quantum Mechanics of the Composite System and Its Subsystems.Shigeru Machida & Akio Motoyoshi - 1998 - Foundations of Physics 28 (1):45-57.
    We revisit the EPR problem and make clear what is a correct comprehension of its problem. When one applies the quantum mechanics correctly, it will be shown that there is no paradox. According to these lines of thought, a quantum teleportation scheme without resort to the von Neumann projection postulate is presented.
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  6.  15
    State of Charge Estimation of Composite Energy Storage Systems with Supercapacitors and Lithium Batteries.Kai Wang, Chunli Liu, Jianrui Sun, Kun Zhao, Licheng Wang, Jinyan Song, Chongxiong Duan & Liwei Li - 2021 - Complexity 2021:1-15.
    This paper studies the state of charge estimation of supercapacitors and lithium batteries in the hybrid energy storage system of electric vehicles. According to the energy storage principle of the electric vehicle composite energy storage system, the circuit models of supercapacitors and lithium batteries were established, respectively, and the model parameters were identified online using the recursive least square method and Kalman filtering algorithm. Then, the online estimation of SOC was completed based on the Kalman filtering (...)
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  7.  32
    Quantum States as Informational Bridges.Richard A. Healey - unknown
    A quantum state represents neither properties of a physical system nor anyone's knowledge of its properties. The important question is not what quantum states represent but how they are used as informational bridges. Knowing about some physical situations, an agent may assign a quantum state to form expectations about other possible physical situations. Quantum states are objective: only expectations based on correct state assignments are generally reliable. If a quantum state (...)
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  8.  88
    On quantum electrodynamics of two-particle bound states containing spinless particles.David A. Owen - 1994 - Foundations of Physics 24 (2):273-296.
    We develop here the general treatment arising from the Bethe-Salpeter equation for a two-particle bound system in which at least one of the particles is spinless. It is shown that a natural two-component formalism can be formulated for describing the propagators of scalar particles. This leads to a formulation of the Bethe-Salpeter equation in a form very reminiscent of the fermion-fermion case. It is also shown, that using this two-component formulation for spinless particles, the perturbation theory can be systematically (...)
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  9.  29
    Revisiting Consistency Conditions for Quantum States of Systems on Closed Timelike Curves: An Epistemic Perspective.Joel J. Wallman & Stephen D. Bartlett - 2012 - Foundations of Physics 42 (5):656-673.
    There has been considerable recent interest in the consequences of closed timelike curves (CTCs) for the dynamics of quantum mechanical systems. A vast majority of research into this area makes use of the dynamical equations developed by Deutsch, which were developed from a consistency condition that assumes that mixed quantum states uniquely describe the physical state of a system. We criticize this choice of consistency condition from an epistemic perspective, i.e., a perspective in which the (...) state represents a state of knowledge about a system. We demonstrate that directly applying Deutsch’s condition when mixed states are treated as representing an observer’s knowledge of a system can conceal time travel paradoxes from the observer, rather than resolving them. To shed further light on the appropriate dynamics for quantum systems traversing CTCs, we make use of a toy epistemic theory with a strictly classical ontology due to Spekkens and show that, in contrast to the results of Deutsch, many of the traditional paradoxical effects of time travel are present. (shrink)
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  10.  60
    Compact quantum systems and the Pauli data problem.A. J. Bracken & R. J. B. Fawcett - 1993 - Foundations of Physics 23 (2):277-289.
    Compact quantum systems have underlying compact kinematical Lie algebras, in contrast to familiar noncompact quantum systems built on the Weyl-Heisenberg algebra. Pauli asked in the latter case: to what extent does knowledge of the probability distributions in coordinate and momentum space determine the state vector? The analogous question for compact quantum systems is raised, and some preliminary results are obtained.
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  11. Can quantum probability provide a new direction for cognitive modeling?Emmanuel M. Pothos & Jerome R. Busemeyer - 2013 - Behavioral and Brain Sciences 36 (3):255-274.
    Classical (Bayesian) probability (CP) theory has led to an influential research tradition for modeling cognitive processes. Cognitive scientists have been trained to work with CP principles for so long that it is hard even to imagine alternative ways to formalize probabilities. However, in physics, quantum probability (QP) theory has been the dominant probabilistic approach for nearly 100 years. Could QP theory provide us with any advantages in cognitive modeling as well? Note first that both CP and QP theory share (...)
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  12.  20
    Schrödinger’s microbe: implications of coercing a living organism into a coherent quantum mechanical state.J. W. Bull & A. Gordon - 2015 - Biology and Philosophy 30 (6):845-856.
    Consideration of the experimental activities carried out in one discipline, through the lens of another, can lead to novel insights. Here, we comment from a biological perspective upon experiments in quantum mechanics proposed by physicists that are likely to feasible in the near future. In these experiments, an entire living organism would be knowingly placed into a coherent quantum state for the first time, i.e. would be coerced into demonstrating quantum phenomena. The implications of the proposed (...)
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  13. A Dynamic-Logical Perspective on Quantum Behavior.A. Baltag & S. Smets - 2008 - Studia Logica 89 (2):187-211.
    In this paper we show how recent concepts from Dynamic Logic, and in particular from Dynamic Epistemic logic, can be used to model and interpret quantum behavior. Our main thesis is that all the non-classical properties of quantum systems are explainable in terms of the non-classical flow of quantum information. We give a logical analysis of quantum measurements (formalized using modal operators) as triggers for quantum information flow, and we compare them with other logical operators (...)
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  14.  92
    Bound states and the Special Composition Question.McKenzie Kerry & F. A. Muller - 2017 - In Michela Massimi, Jan-Willem Romeijn & Gerhard Schurz (eds.), EPSA15 Selected Papers: The 5th conference of the European Philosophy of Science Association in Düsseldorf. Cham: Springer.
    The Special Composition Question asks under what conditions a plurality of objects form another, composite object. We propose a condition grounded in our scientific knowledge of physical reality, the essence of which is that objects form a composite object when and only when they are in a bound state – whence our Bound State Proposal. We provide a variety of reasons in favour of a mereological theory that accommodates our Proposal. We consider but reject another proposal, (...)
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  15.  27
    A Separable, Dynamically Local Ontological Model of Quantum Mechanics.Jacques Pienaar - 2016 - Foundations of Physics 46 (1):104-119.
    A model of reality is called separable if the state of a composite system is equal to the union of the states of its parts, located in different regions of space. Spekkens has argued that it is trivial to reproduce the predictions of quantum mechanics using a separable ontological model, provided one allows for arbitrary violations of ‘dynamical locality’. However, since dynamical locality is strictly weaker than local causality, this leaves open the question of whether an (...)
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  16.  61
    Geometro-differential conception of extended particles and their quantum theory in de Sitter space.A. Smida, M. Hachemane & M. Fellah - 1995 - Foundations of Physics 25 (12):1769-1795.
    A geometro-differential quantum theory of extended particles is presented. The geometrical selling is that of Hilbert fiber bundles whose base manifolds are pseudo-Riemannian space-times of points χ which are interpreted as partial aspects of physical reality (the extended particle). The fibers are carrier spaces of induced (internal configuration and momentum) representations of the structural group (the de Sitter group here). Sections of these bundles are seen as physical representations of the particle, and their values in the fibers are interpreted (...)
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  17. Entanglement and Quantum Superposition of a Macroscopic-Macroscopic system.Francesco De Martini - 2011 - Foundations of Physics 41 (3):363-370.
    Two quantum Macro-states and their Macroscopic Quantum Superpositions (MQS) localized in two far apart, space-like separated sites can be non-locally correlated by any entangled couple of single-particles having interacted in the past. This novel “Macro-Macro” paradigm is investigated on the basis of a recent study on an entangled Micro-Macro system involving N≈105 particles. Crucial experimental issues as the violation of Bell’s inequalities by the Macro-Macro system are considered.
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  18.  18
    Trajectories of two-particle states for the harmonic oscillator.A. Kyprianidis - 1988 - Foundations of Physics 18 (11):1077-1091.
    Using the example of a harmonic oscillator and nondispersive wave packets, we derive, in the frame of the causal interpretation, the equations of motion and particle trajectories in one- and two-particle systems. The role of the symmetry or antisymmetry of the wave function is analyzed as it manifests itself in the specific types of corelated trajectories. This simple example shows that the concepts of the quantum potential and the quantum forces prove to be essential for the specification of (...)
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  19.  7
    On the Reality of the Quantum State Once Again: A No-Go Theorem for ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-Ontic Models. [REVIEW]Christine A. Aidala, Andrea Oldofredi & Gabriele Carcassi - 2024 - Foundations of Physics 54 (1):1-15.
    In this paper we show that ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-ontic models, as defined by Harrigan and Spekkens (HS), cannot reproduce quantum theory. Instead of focusing on probability, we use information theoretic considerations to show that all pure states of ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\psi$$\end{document}-ontic models must be orthogonal to each other, in clear violation of quantum mechanics. Given that (i) Pusey, Barrett and Rudolph (PBR) previously showed that (...)
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  20.  11
    Propagation Properties of Bound Electromagnetic Field: Classical and Quantum Viewpoints.A. L. Kholmetskii, O. V. Missevitch, T. Yarman & R. Smirnov-Rueda - 2020 - Foundations of Physics 50 (11):1686-1722.
    The present work is motivated by recent experiments aimed to measure the propagation velocity of bound electromagnetic field that reveal no retardation in the absence of EM radiation. We show how these findings can be incorporated into the mathematical structure of special relativity theory that allows us to reconsider some selected problems of classical and quantum electrodynamics. In particular, we come to the conclusion that the total four-momentum for a classical system “particles plus fields” ought to be a (...)
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  21.  89
    Is “relative quantum phase” transitive?A. J. Leggett - 1995 - Foundations of Physics 25 (1):113-122.
    I discuss the question: Is it possible to prepare, by purely thermodynamic means, an ensemble described by a quantum state having a definite phase relation between two component states which have never been in direct contact? Resolution of this question requires us to take explicit account of the nature of the correlations between the system and its thermal environment.
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  22. Pauli's electron as a dynamic system.Y. A. Rylov - 1995 - Foundations of Physics 25 (7):1055-1086.
    A dynamic systemS P described by the Pauli equation for nonrelativistic electron is investigated merely as a distributed dynamic system. No quantum principles are used. This system is shown to be a statistical ensemble of nonrelativistic stochastic pointlike particles. The electron spin is shown to have a classical analog which is a collective (statistical) property of the ensemble (not a property of a single electron). The magnetic moment of the electron is a quantum property which has (...)
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  23.  28
    A first-order equation for spin in a manifestly relativistically covariant quantum theory.A. Arensburg & L. P. Horwitz - 1992 - Foundations of Physics 22 (8):1025-1039.
    Relativistic quantum mechanics has been formulated as a theory of the evolution ofevents in spacetime; the wave functions are square-integrable functions on the four-dimensional spacetime, parametrized by a universal invariant world time τ. The representation of states with spin is induced with a little group that is the subgroup of O(3, 1) leaving invariant a timelike vector nμ; a positive definite invariant scalar product, for which matrix elements of tensor operators are covariant, emerges from this construction. In a previous (...)
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  24.  2
    Quantum Prey–Predator Dynamics: A Gaussian Ensemble Analysis.A. E. Bernardini & O. Bertolami - 2023 - Foundations of Physics 53 (3):1-11.
    Quantum frameworks for modeling competitive ecological systems and self-organizing structures have been investigated under multiple perspectives yielded by quantum mechanics. These comprise the description of the phase-space prey–predator competition dynamics in the framework of the Weyl–Wigner quantum mechanics. In this case, from the classical dynamics described by the Lotka–Volterra (LV) Hamiltonian, quantum states convoluted by statistical gaussian ensembles can be analytically evaluated. Quantum modifications on the patterns of equilibrium and stability of the prey–predator dynamics can (...)
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  25.  28
    On Some Troubles with the Metaphysics of Fermionic Compositions.Tomasz Bigaj - 2016 - Foundations of Physics 46 (9):1168-1184.
    In this paper I discuss some metaphysical consequences of an unorthodox approach to the problem of the identity and individuality of “indistinguishable” quantum particles. This approach is based on the assumption that the only admissible way of individuating separate components of a given system is with the help of the permutation-invariant qualitative properties of the total system. Such a method of individuation, when applied to fermionic compositions occupying so-called GMW-nonentangled states, yields highly implausible consequences regarding the number (...)
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  26.  80
    A formal framework for the study of the notion of undefined particle number in quantum mechanics.Newton C. A. da Costa & Federico Holik - 2015 - Synthese 192 (2):505-523.
    It is usually stated that quantum mechanics presents problems with the identity of particles, the most radical position—supported by E. Schrödinger—asserting that elementary particles are not individuals. But the subject goes deeper, and it is even possible to obtain states with an undefined particle number. In this work we present a set theoretical framework for the description of undefined particle number states in quantum mechanics which provides a precise logical meaning for this notion. This construction goes in the (...)
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  27.  95
    On the Measurement Problem for a Two-level Quantum System.Alexey A. Kryukov - 2007 - Foundations of Physics 37 (1):3-39.
    A geometric approach to quantum mechanics with unitary evolution and non-unitary collapse processes is developed. In this approach the Schrödinger evolution of a quantum system is a geodesic motion on the space of states of the system furnished with an appropriate Riemannian metric. The measuring device is modeled by a perturbation of the metric. The process of measurement is identified with a geodesic motion of state of the system in the perturbed metric. Under the (...)
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  28.  37
    How Quantum Theory Helps Us Explain.Richard A. Healey - 2015 - British Journal for the Philosophy of Science 66 (1):1-43.
    I offer an account of how the quantum theory we have helps us explain the enormous variety of phenomena it is generally taken to explain. The account depends on what I have elsewhere called a pragmatist interpretation of the theory. This rejects views according to which a quantum state describes or represents a physical system, holding instead that it functions as a source of sound advice to physically situated agents like us on the content and appropriate (...)
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  29.  21
    A model of quantum measurement in Josephson junctions.Roger A. Hegstrom & Fernando Sols - 1995 - Foundations of Physics 25 (5):681-700.
    A model for the quantum measurement of the electronic current in a Josephson junction is presented and analyzed. The model is similar to a Stern-Gerlach apparatus, relying on the deflection of a spin-polarized particle beam by the magnetic field created by the Josephson current. The aim is (1) to explore, with the help of a simple model, some general ideas about the nature of the information which can be obtained by measurements upon a quantum system and (2) (...)
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  30.  56
    Quantum Mechanics as an Emergent Property of Ergodic Systems Embedded in the Zero-point Radiation Field.L. de la Peña, A. Valdés-Hernández & A. M. Cetto - 2009 - Foundations of Physics 39 (11):1240-1272.
    The present paper reveals (non-relativistic) quantum mechanics as an emergent property of otherwise classical ergodic systems embedded in a stochastic vacuum or zero-point radiation field (zpf). This result provides a theoretical basis for understanding recent numerical experiments in which a statistical analysis of an atomic electron interacting with the zpf furnishes the quantum distribution for the ground state of the H atom. The action of the zpf on matter is essential within the present approach, but it is (...)
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  31.  52
    Quantum Properties of a Single Beam Splitter.F. Laloë & W. J. Mullin - 2012 - Foundations of Physics 42 (1):53-67.
    When a single beam-splitter receives two beams of bosons described by Fock states (Bose-Einstein condensates at very low temperatures), interesting generalizations of the two-photon Hong-Ou-Mandel effect take place for larger number of particles. The distributions of particles at two detectors behind the beam splitter can be understood as resulting from the combination of two effects, the spontaneous phase appearing during quantum measurement, and the quantum angle. The latter introduces quantum “population oscillations”, which can be seen as a (...)
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  32.  6
    The Emerging Quantum: The Physics Behind Quantum Mechanics.Luis de la Peña - 2015 - Cham: Imprint: Springer. Edited by Ana María Cetto & Andrea Valdés Hernández.
    This monograph presents the latest findings from a long-term research project intended to identify the physics behind Quantum Mechanics. A fundamental theory for quantum mechanics is constructed from first physical principles, revealing quantization as an emergent phenomenon arising from a deeper stochastic process. As such, it offers the vibrant community working on the foundations of quantum mechanics an alternative contribution open to discussion. The book starts with a critical summary of the main conceptual problems that still beset (...)
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  33.  86
    Selection rules, causality, and unitarity in statistical and quantum physics.A. Kyrala - 1974 - Foundations of Physics 4 (1):31-51.
    The integrodifferential equations satisfied by the statistical frequency functions for physical systems undergoing stochastic transitions are derived by application of a causality principle and selection rules to the Markov chain equations. The result equations can be viewed as generalizations of the diffusion equation, but, unlike the latter, they have a direct bearing onactive transport problems in biophysics andcondensation aggregation problems of astrophysics and phase transition theory. Simple specific examples of the effects of severe selection rules, such as the relaxational Boltzmann (...)
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  34. A New Negentropic Subject: Reviewing Michel Serres' Biogea.A. Staley Groves - 2012 - Continent 2 (2):155-158.
    continent. 2.2 (2012): 155–158 Michel Serres. Biogea . Trans. Randolph Burks. Minneapolis: Univocal Publishing. 2012. 200 pp. | ISBN 9781937561086 | $22.95 Conveying to potential readers the significance of a book puts me at risk of glad handing. It’s not in my interest to laud the undeserving, especially on the pages of this journal. This is not a sales pitch, but rather an affirmation of a necessary work on very troubled terms: human, earth, nature, and the problematic world we made. (...)
     
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  35.  75
    Quantum states and potentialities of quantum systems.Shimon Malin - 1986 - Foundations of Physics 16 (12):1297-1305.
    In a previous article it was shown that in general quantum states represent perspectives on the potentialities of quantum systems, rather than the potentialities themselves. In the present paper the following questions are investigated in the context of this result: (1) How do quantum states which undergo collapse transform under pure translations? (2) Under what conditions do quantum states represent the potentialities themselves? Two alternatives are presented in response to the first question: (1) Quantum states (...)
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  36.  15
    Representation of Quantum States as Points in a Probability Simplex Associated to a SIC-POVM.José Ignacio Rosado - 2011 - Foundations of Physics 41 (7):1200-1213.
    The quantum state of a d-dimensional system can be represented by a probability distribution over the d 2 outcomes of a Symmetric Informationally Complete Positive Operator Valued Measure (SIC-POVM), and then this probability distribution can be represented by a vector of $\mathbb {R}^{d^{2}-1}$ in a (d 2−1)-dimensional simplex, we will call this set of vectors $\mathcal{Q}$ . Other way of represent a d-dimensional system is by the corresponding Bloch vector also in $\mathbb {R}^{d^{2}-1}$ , we will (...)
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  37. Probability Description and Entropy of Classical and Quantum Systems.Margarita A. Man’ko & Vladimir I. Man’ko - 2011 - Foundations of Physics 41 (3):330-344.
    Tomographic approach to describing both the states in classical statistical mechanics and the states in quantum mechanics using the fair probability distributions is reviewed. The entropy associated with the probability distribution (tomographic entropy) for classical and quantum systems is studied. The experimental possibility to check the inequalities like the position–momentum uncertainty relations and entropic uncertainty relations are considered.
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  38.  14
    Quantum Polar Duality and the Symplectic Camel: A New Geometric Approach to Quantization.Maurice A. De Gosson - 2021 - Foundations of Physics 51 (3):1-39.
    We define and study the notion of quantum polarity, which is a kind of geometric Fourier transform between sets of positions and sets of momenta. Extending previous work of ours, we show that the orthogonal projections of the covariance ellipsoid of a quantum state on the configuration and momentum spaces form what we call a dual quantum pair. We thereafter show that quantum polarity allows solving the Pauli reconstruction problem for Gaussian wavefunctions. The notion of (...)
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  39. Empirical State Determination of Entangled Two-Level Systems and Its Relation to Information Theory.Y. Ben-Aryeh, A. Mann & B. C. Sanders - 1999 - Foundations of Physics 29 (12):1963-1975.
    Theoretical methods for empirical state determination of entangled two-level systems are analyzed in relation to information theory. We show that hidden variable theories would lead to a Shannon index of correlation between the entangled subsystems which is larger than that predicted by quantum mechanics. Canonical representations which have maximal correlations are treated by the use of Schmidt and Hilbert-Schmidt decomposition of the entangled states, including especially the Bohm singlet state and the GHZ entangled states. We show that (...)
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  40.  63
    Spatial Degrees of Freedom in Everett Quantum Mechanics.Mark A. Rubin - 2006 - Foundations of Physics 36 (8):1115-1159.
    Stapp claims that, when spatial degrees of freedom are taken into account, Everett quantum mechanics is ambiguous due to a “core basis problem.” To examine an aspect of this claim I generalize the ideal measurement model to include translational degrees of freedom for both the measured system and the measuring apparatus. Analysis of this generalized model using the Everett interpretation in the Heisenberg picture shows that it makes unambiguous predictions for the possible results of measurements and their respective (...)
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  41.  26
    Timelines and Quantum Time Operators.Curt A. Moyer - 2015 - Foundations of Physics 45 (4):382-403.
    The failure of conventional quantum theory to recognize time as an observable and to admit time operators is addressed. Instead of focusing on the existence of a time operator for a given Hamiltonian, we emphasize the role of the Hamiltonian as the generator of translations in time to construct time states. Taken together, these states constitute what we call a timeline. Such timelines are adequate for the representation of any physical state, and appear to exist even for the (...)
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  42.  48
    On quantum logic.T. A. Brody - 1984 - Foundations of Physics 14 (5):409-430.
    The status and justification of quantum logic are reviewed. On the basis of several independent arguments it is concluded that it cannot be a logic in the philosophical sense of a general theory concerning the structure of valid inferences. Taken as a calculus for combining quantum mechanical propositions, it leaves a number of significant aspects of quantum physics unaccounted for. It is shown, moreover, that quantum logic, far from being more general than Boolean logic, forms a (...)
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  43. Computable functions, quantum measurements, and quantum dynamics.M. A. Nielsen - unknown
    Quantum mechanical measurements on a physical system are represented by observables - Hermitian operators on the state space of the observed system. It is an important question whether all observables may be realized, in principle, as measurements on a physical system. Dirac’s influential text ( [1], page 37) makes the following assertion on the question: The question now presents itself – Can every observable be measured? The answer theoretically is yes. In practice it may be (...)
     
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  44. Withering away, weakly.F. A. Muller - 2011 - Synthese 180 (2):223 - 233.
    One of the reasons provided for the shift away from an ontology for physical reality of material objects & properties towards one of physical structures & relations (Ontological Structural Realism: OntSR) is that the quantum-mechanical description of composite physical systems of similar elementary particles entails they are indiscernible. As material objects, they 'whither away', and when they wither away, structures emerge in their stead. We inquire into the question whether recent results establishing the weak discernibility of elementary particles (...)
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  45. Measurement and Quantum Dynamics in the Minimal Modal Interpretation of Quantum Theory.Jacob A. Barandes & David Kagan - 2020 - Foundations of Physics 50 (10):1189-1218.
    Any realist interpretation of quantum theory must grapple with the measurement problem and the status of state-vector collapse. In a no-collapse approach, measurement is typically modeled as a dynamical process involving decoherence. We describe how the minimal modal interpretation closes a gap in this dynamical description, leading to a complete and consistent resolution to the measurement problem and an effective form of state collapse. Our interpretation also provides insight into the indivisible nature of measurement—the fact that you (...)
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  46.  49
    Solutions of the Time-Dependent Schrödinger Equation for a Two-State System.J. F. Ralph, T. D. Clark, H. Prance, R. J. Prance, A. Widom & Y. N. Srivastava - 1998 - Foundations of Physics 28 (8):1271-1282.
    The statistical properties of a single quantum object and an ensemble of independent such objects are considered in detail for two-level systems. Computer simulations of dynamic zero-point quantum fluctuations for a single quantum object are reported and compared with analytic solutions for the ensemble case.
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    The Case Against Factorism: On the Labels of $$\otimes$$-Factor Hilbert-Spaces of Similar Particles in Quantum Mechanics.F. A. Muller & Gijs Leegwater - 2022 - Journal for General Philosophy of Science / Zeitschrift für Allgemeine Wissenschaftstheorie 53 (3):291-306.
    We discuss the case against Factorism, which is the standard assumption in quantum mechanics that the labels of the $$\otimes$$ ⊗ -factor Hilbert-spaces in direct-product Hilbert-spaces of composite physical systems of similar particles refer to particles, either directly or descriptively. We distinguish different versions of Factorism and argue for their truth or falsehood. In particular, by introducing the concepts of snapshot Hilbert-space and Schrödinger-movie, we demonstrate that there are Hilbert-spaces and $$\otimes$$ ⊗ -factorisations where the labels do refer, (...)
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  48. Quantum States of a Time-Asymmetric Universe: Wave Function, Density Matrix, and Empirical Equivalence.Eddy Keming Chen - 2019 - Dissertation, Rutgers University - New Brunswick
    What is the quantum state of the universe? Although there have been several interesting suggestions, the question remains open. In this paper, I consider a natural choice for the universal quantum state arising from the Past Hypothesis, a boundary condition that accounts for the time-asymmetry of the universe. The natural choice is given not by a wave function but by a density matrix. I begin by classifying quantum theories into two types: theories with a fundamental (...)
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    Quaternionic Quantum Dynamics on Complex Hilbert Spaces.Matthew A. Graydon - 2013 - Foundations of Physics 43 (5):656-664.
    We consider a quaternionic quantum formalism for the description of quantum states and quantum dynamics. We prove that generalized quantum measurements on physical systems in quaternionic quantum theory can be simulated by usual quantum measurements with positive operator valued measures on complex Hilbert spaces. Furthermore, we prove that quaternionic quantum channels can be simulated by completely positive trace preserving maps on complex matrices. These novel results map all quaternionic quantum processes to algorithms (...)
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    Quantum Brain States.Richard A. Mould - 2003 - Foundations of Physics 33 (4):591-612.
    If conscious observers are to be included in the quantum mechanical universe, we need to find the rules that engage observers with quantum mechanical systems. The author has proposed five rules that are discovered by insisting on empirical completeness; that is, by requiring the rules to draw empirical information from Schrödinger's solutions that is more complete than is currently possible with the (Born) probability interpretation. I discard Born's interpretation, introducing probability solely through probability “current.” These rules tell us (...)
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