13,807 research outputs found

    Entanglement production in quantum decision making

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    The quantum decision theory introduced recently is formulated as a quantum theory of measurement. It describes prospect states represented by complex vectors of a Hilbert space over a prospect lattice. The prospect operators, acting in this space, form an involutive bijective algebra. A measure is defined for quantifying the entanglement produced by the action of prospect operators. This measure characterizes the level of complexity of prospects involved in decision making. An explicit expression is found for the maximal entanglement produced by the operators of multimode prospects.Comment: Latex file, 7 page

    Statistics of Oscillator Strengths in Chaotic Systems

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    The statistical description of oscillator strengths for systems like hydrogen in a magnetic field is developed by using the supermatrix nonlinear σ\sigma-model. The correlator of oscillator strengths is found to have a universal parametric and frequency dependence, and its analytical expression is given. This universal expression applies to quantum chaotic systems with the same generality as Wigner-Dyson statistics.Comment: 11 pages, REVTeX3+epsf, two EPS figures. Replaced by the published version. Minor changes

    Surface criticality in random field magnets

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    The boundary-induced scaling of three-dimensional random field Ising magnets is investigated close to the bulk critical point by exact combinatorial optimization methods. We measure several exponents describing surface criticality: β1\beta_1 for the surface layer magnetization and the surface excess exponents for the magnetization and the specific heat, βs\beta_s and αs\alpha_s. The latter ones are related to the bulk phase transition by the same scaling laws as in pure systems, but only with the same violation of hyperscaling exponent θ\theta as in the bulk. The boundary disorders faster than the bulk, and the experimental and theoretical implications are discussed.Comment: 6 pages, 9 figures, to appear in Phys. Rev.
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