Fortschritte der Physik

Cover image for Vol. 61 Issue 7‐8

July 2013

Volume 61, Issue 7-8

Pages 701–778

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Issue Information
    4. Contents
    5. Original Papers
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      Cover Picture: Fortschritte der Physik 7–8 / 2013

      Version of Record online: 1 JUL 2013 | DOI: 10.1002/prop.201390008

      Thumbnail image of graphical abstract

      The cover page shows snapshots of a decaying Schrödinger cat Wigner function. This is a quasi-probability distribution for the amplitude of a microwave field stored in an ultra-high quality superconducting cavity. A single circular Rydberg atom interacting with a coherent state produces a quantum superposition of two fields with different phases. The two positive peaks in the Wigner function (front) are centered on the classical amplitudes of these components. The interference pattern in-between indicates the quantum nature of the superposition. As time proceeds (from front to rear), the interference pattern vanishes, revealing the rapid decoherence of a mesoscopic quantum state superposition.

  2. Issue Information

    1. Top of page
    2. Cover Picture
    3. Issue Information
    4. Contents
    5. Original Papers
    1. You have free access to this content
  3. Contents

    1. Top of page
    2. Cover Picture
    3. Issue Information
    4. Contents
    5. Original Papers
    1. You have free access to this content
  4. Original Papers

    1. Top of page
    2. Cover Picture
    3. Issue Information
    4. Contents
    5. Original Papers
    1. Dispersion theory of nucleon Compton scattering and polarizabilities (pages 703–741)

      M. Schumacher and M.D. Scadron

      Version of Record online: 2 APR 2013 | DOI: 10.1002/prop.201300007

      A status report on the topic nucleon Compton scattering and polarizabilities is presented with emphasis on the scalar t-channel. Precise values for the polarizabilities are the result of a newly developed analysis which is the main topic of the present paper. The most important recent discovery is that the largest part of the electric polarizability and the total diamagnetic polarizability of the nucleon are properties of the σ meson as part of the constituent-quark structure, as expected from the mechanism of chiral symmetry breaking.

    2. Black hole's quantum N-portrait (pages 742–767)

      G. Dvali and C. Gomez

      Version of Record online: 8 APR 2013 | DOI: 10.1002/prop.201300001

      The occupation number N of gravitons in a gravitational field is established as a quantum measure of classicality. This allows viewing the classical background geometries as quantum Bose-condensates with large occupation numbers of soft gravitons. Among all possible sources of a given physical length, N is maximized by the black hole and coincides with its entropy. The emerging quantum mechanical picture of a black hole is surprisingly simple and fully parameterized by N. It provides a simple quantum description of the phenomena of Hawking radiation, Bekenstein entropy as well as of non-Wilsonian UV-self-completion of Einstein gravity.

    3. Black hole quantum mechanics in the presence of species (pages 768–778)

      G. Dvali, C. Gomez and D. Lüst

      Version of Record online: 23 APR 2013 | DOI: 10.1002/prop.201300002

      Within the framework as used in the preceeding paper the semi-classical black hole bound on the number of particle species Nspecies is revised. It is shown that unlike the bound on global charge, the bound on species survives in the quantum picture and gives rise to a new fundamental length-scale, beyond which the resolution of species identities is impossible. This finding nullifies the so-called species problem. This scale sets the size of the lightest quantum black hole in the theory, the Planckion.

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