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  • 1
    Electronic Resource
    Electronic Resource
    Statistical properties of resonance radiation selectively reflected from a cold semi-infinite medium (1999)
    Springer
    Journal of experimental and theoretical physics 89 (1999), S. 435-443 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The problem of the quantum-statistical properties of resonance radiation selectively reflected from unexcited media in the case where the photons are mutually correlated in the incident radiation flux is posed and solved. Allowance for mutual photon correlation precludes, in principle, solving the problem by perturbation methods. A quantum analog of the optical theorem of absorption, which causes an infinite subsequence of Feynman diagrams to vanish, is pointed out. The frequency-angle distribution of the photons in the reflected flux is predicted. The Fresnel formulas are reconstructed for the averaged reflection characteristics. The limits for their applicability in describing the reflection of mutually correlated photons are given. A suppression effect is predicted for the reflection of radiation from a laser source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.559001
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  • 2
    Electronic Resource
    Electronic Resource
    Selective reflection of resonance radiation from excited media (1998)
    Springer
    Journal of experimental and theoretical physics 86 (1998), S. 289-298 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract According to quantum electrodynamics, the cross section for resonant scattering of radiation on an aggregate of excited atoms can be written as a sum of positive definite terms. This type of structure is not consistent with the Fresnel formulas for the reflection coefficient of radiation from thermally excited media. The difference shows up on a macroscopic level and indicates that semiclassical radiation theory cannot be used. A study of the correlation between elastic scattering and stimulated emission processes clarifies the reason for the discrepancies. The resulting singularities require summing of Feynman diagrams which appear beginning in the sixth order of perturbation theory. A lower bound estimate for the reflection coefficient from a plane layer is given, including processes which violate the statistics of radiation. The contribution of stimulated emission processes caused by the initially scattered photon are examined specifically. An experiment is proposed which would settle the choice of theories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558455
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  • 3
    Electronic Resource
    Electronic Resource
    Photon cooperative effect in resonance spectroscopy (1998)
    Springer
    Journal of experimental and theoretical physics 87 (1998), S. 270-279 
    Details
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A systematic method is proposed for calculating the density matrix of subsystems interacting with their environment under conditions of thermodynamic equilibrium. The density matrix of photons resonantly interacting with a surrounding gas is calculated. It is shown that use of the Gibbs distribution allows one to completely eliminate inelastic processes from the calculations. A correct account of photon-photon correlators indicates the presence of new cooperative effects. A new branch of the polariton spectrum is predicted, which is due to the presence of excited atoms in the medium. With the help of the density matrix the mean filling numbers of the photon modes are calculated. In terms of wavelengths, we have obtained a generalization of the Planck formula which accounts for photon cooperative phenomena. The manifestation of these effects in kinetic processes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.558656
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  • 4
    Electronic Resource
    Electronic Resource
    Coherence relaxation during the diffusion of resonance radiation in media with a magnetic field (1975)
    Springer
    Russian physics journal 18 (1975), S. 1000-1004 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The kinetic Green's function method is used to obtain equations which describe the transport of resonance radiation in magnetic fields for arbitrary ratios between the natural widthγ, the Doppler width Δω D, and the Zeeman splitting of the excited atomic levels. It is shown that as ΔωD/γ→0 the equations become very much simpler and in particular cases admit an exact solution. In particular, the decay of coherence in an infinite homogeneous space is characterized by five relaxation times, which are defined by a system of algebraic equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00894538
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  • 5
    Electronic Resource
    Electronic Resource
    Spectral representations and the density matrix of subsystems (1978)
    Springer
    Russian physics journal 21 (1978), S. 616-620 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A regular method is indicated which makes it possible, under conditions of thermodynamic equilibrium, to find in a constructive manner the density matrix of a subsystem which, in general, is in strong interaction with its surroundings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00890977
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  • 6
    Electronic Resource
    Electronic Resource
    Phase relations in quantum optics and the bremsstrahlung structure (1978)
    Springer
    Russian physics journal 21 (1978), S. 707-712 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The distribution function of amplitude a and phase ϕ of an arbitrary quantum magnetic field is investigated on the basis of the combined use of two representations, related with a Fourier transform. The square of the wave function in one of these representations determines the distribution function α cos ϕ and in the other, α sin ϕ. As an application, the structure of the bremsstrahlung of a wave packet of electrons is considered. It is shown that the nature of the radiation density matrix depends significantly on the spatial nonuniformity of the electron packet in the region of the scattering centers. A comparison is carried out with the quasiclassical theory of radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00936675
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  • 7
    Electronic Resource
    Electronic Resource
    Forward transition radiation in a medium with excited atoms (1986)
    Springer
    Russian physics journal 29 (1986), S. 130-133 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract On the basis of the quantum theory of radiation, we study the characteristics of forward transition radiation not predicted by the semiclassical radiation theory (which uses a nonquantized electromagnetic field) and not described by the index of refraction of the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00896350
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  • 8
    Electronic Resource
    Electronic Resource
    Combinational absorption of the two-photon field in a dispersive medium by an impurity atom (1987)
    Springer
    Russian physics journal 30 (1987), S. 1041-1044 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A complete solution is given for the problem of impurity excitation by a two-photon field, as a result of which the remaining free quantum passes from one polariton branch of the spectrum to another without change in the wave vector. The decisive role of relaxation constants in the formation of the process is noted. The criteria of independent behavior of photons in this reaction are given. The given process belongs to the class of processes due to disrupted interference of the matrix elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00897918
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  • 9
    Electronic Resource
    Electronic Resource
    Point source of polarized resonance radiation in an unbounded medium (1974)
    Springer
    Russian physics journal 17 (1974), S. 478-482 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The diffusion of polarized resonance radiation is considered. An explicit expression is given for the Green's function of the corresponding equation for an unbounded uniform space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00891006
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  • 10
    Electronic Resource
    Electronic Resource
    Change in the electromagnetic field frequency because of stimulated radiation in a medium (1982)
    Springer
    Russian physics journal 25 (1982), S. 438-441 
    Details
    ISSN: 1573-9228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spectrum of a two-photon electromagnetic field in a transparent dispersing medium consists of three branches. Excitation of the secondary branches of the spectrum implies a change in the electromagnetic field frequency during passage through a medium of finite size if excited impurity atoms are present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00891768
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