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Pekka Lahti [10]Pekka J. Lahti [7]
  1. Heisenberg's Uncertainty Principle.Paul Busch, Teiko Heinonen & Pekka Lahti - unknown
    Heisenberg's uncertainty principle is usually taken to express a limitation of operational possibilities imposed by quantum mechanics. Here we demonstrate that the full content of this principle also includes its positive role as a condition ensuring that mutually exclusive experimental options can be reconciled if an appropriate trade-off is accepted. The uncertainty principle is shown to appear in three manifestations, in the form of uncertainty relations: for the widths of the position and momentum distributions in any quantum state; for the (...)
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  2.  14
    The Determination of the Past and the Future of a Physical System in Quantum Mechanics.Paul Busch & Pekka J. Lahti - 1989 - Foundations of Physics 19 (6):633-678.
    The determination of the past and the future of a physical system are complementary aims of measurements. An optimal determination of the past of a system can be achieved by an informationally complete set of physical quantities. Such a set is always strongly noncommutative. An optimal determination of the future of a physical system can be obtained by a Boolean complete set of quantities. The two aims can be reconciled to a reasonable degree with using unsharp measurements.
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  3.  29
    The Standard Model of Quantum Measurement Theory: History and Applications. [REVIEW]Paul Busch & Pekka J. Lahti - 1996 - Foundations of Physics 26 (7):875-893.
    The standard model of the quantum theory of measurement is based on an interaction Hamiltonian in which the observable to be measured is multiplied by some observable of a probe system. This simple Ansatz has proved extremely fruitful in the development of the foundations of quantum mechanics. While the ensuing type of models has often been argued to be rather artificial, recent advances in quantum optics have demonstrated their principal and practical feasibility. A brief historical review of the standard model (...)
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  4.  51
    A Note on Quantum Theory, Complementarity, and Uncertainty.Paul Busch & Pekka J. Lahti - 1985 - Philosophy of Science 52 (1):64-77.
    Uncertainty relations and complementarity of canonically conjugate position and momentum observables in quantum theory are discussed with respect to some general coupling properties of a function and its Fourier transform. The question of joint localization of a particle on bounded position and momentum value sets and the relevance of this question to the interpretation of position-momentum uncertainty relations is surveyed. In particular, it is argued that the Heisenberg interpretation of the uncertainty relations can consistently be carried through in a natural (...)
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  5.  31
    On the Quantum Theory of Sequential Measurements.Paul Busch, Gianni Cassinelli & Pekka J. Lahti - 1990 - Foundations of Physics 20 (7):757-775.
    The quantum theory of sequential measurements is worked out and is employed to provide an operational analysis of basic measurement theoretical notions such as coexistence, correlations, repeatability, and ideality. The problem of the operational definition of continuous observables is briefly revisited, with a special emphasis on the localization observable. Finally, a brief overview is given of possible applications of the theory to various fields and problems in quantum physics.
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  6.  40
    Completely Positive Mappings in Quantum Dynamics and Measurement Theory.Paul Busch & Pekka J. Lahti - 1990 - Foundations of Physics 20 (12):1429-1439.
    The role of completely positive mappings in quantum dynamics and measurement theory is reanalyzed in light of the possibility of a generalized dynamics.
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  7.  22
    The Measurement Statistics Interpretation of Quantum Mechanics: Possible Values and Possible Measurement Results of Physical Quantities. [REVIEW]Gianni Cassinelli & Pekka J. Lahti - 1989 - Foundations of Physics 19 (7):873-890.
    Starting with the Born interpretation of quantum mechanics, we show that the quantum theory of measurement, supplemented by the strong law of large numbers, leads to a measurement statistics interpretation of quantum mechanics. A probabilistic characterization of the spectrum of a physical quantity is given, and an analysis of the notions of possible values and possible measurement results is carried out.
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  8.  61
    On the Complementarity of the Quadrature Observables.Pekka Lahti & Juha-Pekka Pellonpää - 2010 - Foundations of Physics 40 (9-10):1419-1428.
    In this paper we investigate the coupling properties of pairs of quadrature observables, showing that, apart from the Weyl relation, they share the same coupling properties as the position-momentum pair. In particular, they are complementary. We determine the marginal observables of a covariant phase space observable with respect to an arbitrary rotated reference frame, and observe that these marginal observables are unsharp quadrature observables. The related distributions constitute the Radon transform of a phase space distribution of the covariant phase space (...)
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  9.  24
    Repeatable Measurements in Quantum Theory: Their Role and Feasibility. [REVIEW]Paul Busch, Marian Grabowski & Pekka J. Lahti - 1995 - Foundations of Physics 25 (9):1239-1266.
    Recent advantages in experimental quantum physics call for a careful reconsideration of the measurement process in quantum mechanics. In this paper we describe the structure of the ideal measurements and their status among the repeatable measurements. Then we provide an exhaustive account of the interrelations between repeatability and the apparently weaker notions of value reproducible or first- kind measurements. We demonstrate the close link between repeatable measurements and discrete observables and show how the ensuing measurement limitations for continuous observables can (...)
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  10.  49
    Lueders Rule (Compendium Entry).Paul Busch & Pekka Lahti - unknown
    This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.
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  11.  45
    Measurement Theory (Compendium Entry).Paul Busch & Pekka Lahti - unknown
    This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberger, to be published by Springer-Verlag.
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  12.  64
    Observable (Compendium Entry).Paul Busch & Pekka Lahti - unknown
    This is an entry to the Compendium of Quantum Physics, edited by F Weinert, K Hentschel and D Greenberg, to be published by Springer-Verlag.
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  13.  24
    An Axiomatic Basis for Quantum Mechanics.Gianni Cassinelli & Pekka Lahti - 2016 - Foundations of Physics 46 (10):1341-1373.
    In this paper we use the framework of generalized probabilistic theories to present two sets of basic assumptions, called axioms, for which we show that they lead to the Hilbert space formulation of quantum mechanics. The key results in this derivation are the co-ordinatization of generalized geometries and a theorem of Solér which characterizes Hilbert spaces among the orthomodular spaces. A generalized Wigner theorem is applied to reduce some of the assumptions of Solér’s theorem to the theory of symmetry in (...)
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  14.  8
    Paul Busch 1955–2018.Stan Gudder, Pekka Lahti & Leon Loveridge - 2018 - Foundations of Physics 48 (9):1128-1130.
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  15.  8
    Paul Busch: At the Heart of Quantum Mechanics.Stan Gudder & Pekka Lahti - 2019 - Foundations of Physics 49 (6):457-459.
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  16.  6
    Complementary Observables in Quantum Mechanics.Jukka Kiukas, Pekka Lahti, Juha-Pekka Pellonpää & Kari Ylinen - 2019 - Foundations of Physics 49 (6):506-531.
    We review the notion of complementarity of observables in quantum mechanics, as formulated and studied by Paul Busch and his colleagues over the years. In addition, we provide further clarification on the operational meaning of the concept, and present several characterisations of complementarity—some of which new—in a unified manner, as a consequence of a basic factorisation lemma for quantum effects. We work out several applications, including the canonical cases of position–momentum, position–energy, number–phase, as well as periodic observables relevant to spatial (...)
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  17. Symposium on the Foundations of Modern Physics, 1990, Joensuu, Finland, 13-17 August 1990 Quantum Theory of Measurement and Related Philosophical Problems. [REVIEW]Peter Mittelstaedt & Pekka Lahti - 1991
     
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