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  • 1995-1999  (8)
  • 1
    Electronic Resource
    Electronic Resource
    The structure of decoherence functionals for von Neumann quantum histories (1995)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 36 (1995), S. 5409-5413 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Gell-Mann and Hartle have proposed a significant generalization of quantum theory in which decoherence functionals perform a key role. Isham–Linden–Schreckenberg have given a penetrating analysis of decoherence functionals for L(H), where H is finite dimensional (dimension greater than 2). In this note their conjecture on the significance of boundedness is verified. In particular, it is shown that when d is a bounded decoherence functional associated with a von Neumann algebra A, then, provided A has no direct summand of type I2, d can be represented as the difference between semi-innerproducts on A. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531268
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Kalmbach outer measures and valuations (1995)
    Springer
    Archiv der Mathematik 64 (1995), S. 523-529 
    Details
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195134
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  • 3
    Electronic Resource
    Electronic Resource
    Homogeneous Decoherence Functionals¶in Standard and History Quantum Mechanics (1999)
    Springer
    Communications in mathematical physics 204 (1999), S. 249-267 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: General history quantum theories are quantum theories without a globally defined notion of time. Decoherence functionals represent the states in the history approach and are defined as certain bivariate complex-valued functionals on the space of all histories. However, in practical situations – for instance in the history formulation of standard quantum mechanics – there often is a global time direction and the homogeneous decoherence functionals are specified by their values on the subspace of homogeneous histories. In this work we study the analytic properties of (i) the standard decoherence functional in the history version of standard quantum mechanics and (ii) homogeneous decoherence functionals in general history theories. We restrict ourselves to the situation where the space of histories is given by the lattice of projections on some Hilbert space ℋ. Among other things we prove the non-existence of a finitely valued extension for the standard decoherence functional to the space of all histories, derive a representation for the standard decoherence functional as an unbounded quadratic form with a natural representation on a Hilbert space and prove the existence of an Isham–Linden–Schreckenberg (ILS) type representation for the standard decoherence functional.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002200050645
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  • 4
    Electronic Resource
    Electronic Resource
    The Multi-form Generalised Gleason Theorem (1998)
    Springer
    Communications in mathematical physics 198 (1998), S. 705-709 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: Arising from investigations of decoherence functionals in the “histories” approach to quantum mechanics, the following result is given by the methods of [14]. Let A 1 and A 2 be von Neumann algebras without Type I 2 direct summands and let P(E j ), (j=1,2) be their lattices of projections. Let m\colon; P(A 1)×(P(A 2)→ℂ be a bounded quantum bi-measure. Then there is a unique bounded bilinear functional M on A 1×A 2 which extends m. In this note we use a different approach to establish a generalisation of this result to k-fold, vector valued, quantum multi-measures. This tool is needed for further investigations of decoherence functionals in quantum theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002200050491
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  • 5
    Electronic Resource
    Electronic Resource
    Decoherence Functionals for von Neumann Quantum Histories: Boundedness and Countable Additivity (1998)
    Springer
    Communications in mathematical physics 191 (1998), S. 493-500 
    Details
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: Gell–Mann and Hartle have proposed a significant generalisation of quantum theory in which decoherence functionals perform a key role. Verifying a conjecture of Isham–Linden–Schreckenberg, the author analysed the structure of bounded, finitely additive, decoherence functionals for a general von Neumann algebra A (where A has no Type I2 direct summand). Isham et al. had already given a penetrating analysis for the situation where A is finite dimensional. The assumption of countable additivity for a decoherence functional may seem more plausible, physically, than that of boundedness. The results of this note are obtained much more generally but, when specialised to L(H), the algebra of all bounded linear operators on a separable Hilbert space H, give: Let d be a countably additive decoherence functional defined on all pairs of projections in L(H). If H is infinite dimensional then d must be bounded. By contrast, when H is finite dimensional, unbounded (countably additive) decoherence functionals always exist for L(A).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002200050275
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  • 6
    Electronic Resource
    Electronic Resource
    Detection of nitrogen dioxide by means of a gold film in a surface-plasmon resonance scheme (1997)
    Springer
    Technical physics letters 23 (1997), S. 920-922 
    Details
    ISSN: 1090-6533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is demonstrated that nitrogen dioxide can be detected by means of a gold film in a surface-plasmon resonance scheme. The sensor response is reversible at room temperature and permits detection of nitrogen dioxide down to concentrations of the order of 1 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1261933
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  • 7
    Electronic Resource
    Electronic Resource
    Erratum: Mayer Expansions and the Hamiltonian–Jacobi Equation. II. Fermions, Dimensional Reduction Formulas (1999)
    Springer
    Journal of statistical physics 97 (1999), S. 1027-1027 
    Details
    ISSN: 1572-9613
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The authors apologize to readers for an egregious error in the proof of Theorem 2.3: contrary to our claim, (2.12) does not follow from Proposition 2.2 and Theorem 2.3 is almost certainly false. We are indebted to Manfred Salmhofer and Christian Wieczerkowski for discovering the error. They are preparing a paper with a corrected theorem proven by different methods. The work in Section 3 is independent of Section 2 and Theorem 3.1 is unaffected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004666114935
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  • 8
    Electronic Resource
    Electronic Resource
    Sol-gel composites for optical sensing of solvents (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1127-1132 
    Details
    ISSN: 1573-4846
    Keywords: sensors ; cyclodextrin ; fluorescence ; solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Porous sol-gel glasses containing entrapped fluorescent-labelled β-cyclodextrin have been prepared from tetramethylorthosilicate (TMOS). Small non-polar solvent molecules such as cyclohexane and toluene displace the fluorescent label from the cyclodextrin cavity, and the resulting decrease in fluorescence intensity is proportional to the solvent vapour concentration in the range 40–100 ppm, and is reversible. Polar solvents such as acetone give no response. Strategies for optimisation of the system are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436995
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