Wave propagation and group velocity

Unified interpretation of superluminal behaviors in wave propagation

Diffraction effects in microwave propagation at the origin of superluminal behaviors

Bonds between atoms/molecules of condensed substances must be described within the framework of quantum electrodynamics (QED) as an exchange of virtual photons. Such representation is supported by the known conformity of latent heat with residual infrared (IR) rays and the possibility of latent heat removal by characteristic frequencies. These bonds are virtual if the duration of photons’ formation (their ‘dressing’) τ exceeds the duration of free path in substance l = 1/σ tot N, i.e. if τ > l/c. It is assumed that reversing this inequality corresponds to bond breakage and phase transitions. With low σ tot and τ frequencies, it leads to the universal radius of correlations, R c ∼ ω −ν, ν = 2/3, and allows refinement of the Ginzburg–Landau model of phase transitions by expansion of thermodynamic potentials over R c (instead of temperature distance), which results in the correct system of critical indices. Such a consideration offers an opportunity for the stimulation of definite phase transitions by resona...

Towards a microscopic theory of phase transitions: residual rays, correlation radii and critical indices

Reciprocal Schrodinger equation for scattering matrix $\partial S(\omega,\mathbf{r})/i\partial\omega= \hat{\tau}(\omega,\mathbf{r})S(\omega,\mathbf{r})$
 
determines temporal function, its real part presents the Wigner–Smith duration of delay and imaginary part describes the duration of resulted (dressed) state formation. “Deduction” of this equation is executed by the Legendre transformation of classical action function with subsequent transition to quantum description and, in the covariant form, by a temporal variant of the Bogoliubov variational method. Temporal functions are expressed via propagators of fields, they are formally equivalent to adding a photon line of zero energy-momentum to the Feynman graphs. As an apparent example they can be clearly interpreted in the oscillator model via polarization and conductivity of medium. It is shown that the adiabatic hypothesis in scattering theory represents an implicit account of temporal parameters. By these functions are described some renormalization procedures, their physical sense is refined, etc.

Reciprocal Schrödinger Equation: Durations of Delay and Formation of States in Scattering Processes

The observation of superluminal transmission of photons created discussions of their reality and significance. To analyze the possibility of such phenomena in general, the most general method is employed based on the covariant theory of dispersion relations. It is shown that superluminal phenomena can only be realized as tunneling of excitations within the near field zone. On this basis, the main experimental data can be described as sequential processes of single photon scattering. Their temporal distribution is estimated by taking into account the scattering time. Thus, the difference is explained between the advance of the superluminal part of the light pulse (i.e., the transition time of single photons) and the signal velocity of the macroscopic pulse of light.

“Superluminal” phenomena can be attributed to instantaneous transfer of excitations in the near field zone

Investigation of near field in QED requires the refuse from an averaging of the Lorentz condition that smooths out some field peculiarities. Instead of it the Schwinger decomposition of 4-potential with the Bogoliubov method of interaction switching in time and in space regions is considered. At such approach near field is describable by the part of covariant Green function of QED, the fast-damping Schwinger function is formed by longitudinal and scalar components of Aμ none restricted by light cone. This description reveals possibility of superluminal phenomena within the near field zone as a “nonlocality in the small”. Some specification of the Bogoliubov method allows, as examples, descriptions of near fields of point-like charge and at FTIR phenomena. Precisely such possibilities of nonlocal interactions are revealed in the common QED expressions for the Van-der-Waals and Casimir interactions and in the Forster law.

Near field in quantum electrodynamics: Green functions, Lorentz condition, “nonlocality in the small”, frustrated total reflection

Investigation of near field of QED requires the refuse from an averaging of the Lorentz condition that smooths out some field peculiarities. Instead of it Schwinger decomposition of the 4-potential with the Bogoliubov method of interaction switching in time and in space regions is considered. At such approach near field is describable by the part of covariant Green function of QED, the fast-damping Schwinger function formed by longitudinal and scalar components of Aμ none restricted by light cone. This description reveals possibility of superluminal phenomena within the near field zone as a "nonlocality in the small". Some specification of Bogoliubov method allows, as examples, descriptions of near fields of point-like charge and at FTIR phenomena. Precisely such possibilities of nonlocal interactions are revealed in the common QED expressions for the Van-der-Waals and Casimir interactions and in the F\"{o}rster law. 
Key words: Lorentz condition, near field, propagators, superluminal, FTIR. 
PACS: 03.30.+p, 12.20.-m, 13.40.-f, 68.37.Uv.

Near field in quantum electrodynamics: Green functions, Lorentz condition, "nonlocality in the small", frustrated total reflection

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“Superluminal” phenomena can be attributed to instantaneous transfer of excitations in the near field zone

Near field in quantum electrodynamics: Green functions, Lorentz condition, “nonlocality in the small”, frustrated total reflection

Near field in quantum electrodynamics: Green functions, Lorentz condition, "nonlocality in the small", frustrated total reflection