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Papers by Vladimir Hizhnyakov

Journal of Superconductivity, 1997

d-wave ands-wave-type solutions of the BCS gap equations are studied numerically with account of ... more d-wave ands-wave-type solutions of the BCS gap equations are studied numerically with account of long-range and short-range interaction with optical phonon and Coulomb repulsion. It is found that for realistic values of parameters the maximal value of the gap is determined mainly by unscreened long-range interactions of charge carriers with long-waveA lg , -andB lg -phonons. The type of the

$Research paper thumbnail of Quantum emission of a medium with a time-dependent refractive index$

Journal of Optics B-quantum and Semiclassical Optics - J OPT B-QUANTUM SEMICL OPT, 1992

Quantum emission of photons caused by sudden change of the refractive index of a medium is consid... more Quantum emission of photons caused by sudden change of the refractive index of a medium is considered. This emission appears due to time dependence of the zeroth quantum state of the field and is a non-stationary analogue of the Casimir effect. A model-exact solution of the problem is presented. If sudden changes of the refractive index are caused by excitation of a semiconductor near to a band-to-band transition by a synchroneously pumped subpicosecond dye laser the intensity of the quantum emission is approximately 10-9 W in the infrared. The analogy of the effect with and its difference from, the Hawking and the Unruh radiations are discussed.

Phys Status Solidi B Basic So, 1978

Physical Review B, 1997

ABSTRACT The two-phonon decay of self-localized soliton in a one-dimensional monatomic anharmonic... more ABSTRACT The two-phonon decay of self-localized soliton in a one-dimensional monatomic anharmonic lattice caused by cubic anharmonicity is considered. It is shown that the decay takes place with emission of phonon bursts. The average rate of emission of phonons is of the order of vibrational quantum per vibrational period. Characteristic time of the relaxation is determined by the quantum anharmonicity parameter; this time may vary from a few (quantum lattices, large anharmonicity) to thousands (ordinary lattices, small anharmonicity) of vibrational periods. Comment: 6 pages, 3 figures

Physical Review B, 1984

The emission tail arising from multiphonon resonance Raman scattering by F centers in alkali hali... more The emission tail arising from multiphonon resonance Raman scattering by F centers in alkali halide crystals exhibits remarkable polarization which weakly depends on the emitted-photon frequency. This means that depolarization processes accompanying vibrational relaxation in the excited electronic state take place only in the earliest stage of relaxation; later they are switched off. This depolarization switching-off effect may be understood

Laser Optics of Condensed Matter, 1988

Optics Communications, 1984

A two-level atom in the field of two quantized laser modes with equal frequencies is considered. ... more A two-level atom in the field of two quantized laser modes with equal frequencies is considered. It is shown that the ener gy spectrum of the system forms a ladder of pair bands analogous to those of onedimensional twoatom lattice. The band states correspond to quasi-particles describing the transfer of photons between the modes. The fluorescence and weak probe field as well as strong field absorption spectra are calculated.

Light Scattering in Solids, 1979

The Journal of Chemical Physics, Oct 31, 1999

The optical dephasing, caused by vibrational modulation of interactions of optical centers with d... more The optical dephasing, caused by vibrational modulation of interactions of optical centers with defects is studied. This mechanism is essential for crystals with a substantial amount of defects, being more efficient at low temperatures than the Raman mechanism, caused by scattering of acoustic phonons at optical centers. A theory is developed, which allows one to find averaged widths and shapes of spectral holes in these systems dependending on the temperature T and concentration c of defects. The shape of the hole is found to be close to a Lorentzian, and at intermediate temperatures its width is proportional to T3, and strongly depends on c (for charged point defects as c8/3).

$Research paper thumbnail of Strong two-photon emission by a medium with periodically time-dependent refractive index$

A two-photon emission of a medium with periodically time-dependent refractive index is considered... more A two-photon emission of a medium with periodically time-dependent refractive index is considered. The emission results from the zero-point fluctuations of the medium. Usually this emission is very weak. However, it can be strongly enhanced if the resonant condition omega_0\omega_0omega0 = 2.94 c/l0c/l_0c/l0 is fulfilled (here omega0\omega_0omega0 and l0l_0 l_0 are the frequency and the amplitude of the oscillations of the optical length of the medium, respectively). Besides, a medium with resonant oscillations of the optical length performs the phase conjugated reflection with high efficiency. A similar resonant enhancement of the two-quantum emission of other bosons is also predicted.

Journal of the Physical Society of Japan, Jan 15, 1988

A nonequilibrium statistical operator of a vibronic system in the representation of the configura... more A nonequilibrium statistical operator of a vibronic system in the representation of the configurational coordinate and the corresponding characteristic Wigner function are considered. In the formulas obtained, quadratic quantum fluctuations in the nonstationary state are expressed via integrals from the dynamical Green’s functions; the expressions at small and large times pass over into the Callen-Welton formula. The formalism proposed can be used to describe squeezed pulses.

Solid State Communications, 1982

Plasmonics: Metallic Nanostructures and Their Optical Properties X, 2012

ABSTRACT The mesoscopic effect of spectral modulation occurring due to the interference of two ph... more ABSTRACT The mesoscopic effect of spectral modulation occurring due to the interference of two photonic fiber modes filtered out by a metal-coated SNOM tip is used to observe the surface plasmon polariton (SPP) excitation in SNOM tips. In a spectrum of the broadband light transmitted by a SNOM tip a region of highly regular spectral modulation can be found, indicating the spectral interval in which only two photonic modes (apparently HE11 and TM01) are transmitted with significant and comparable amplitudes. The modulation period yields the value of optical path difference (OPD) for this pair of modes. Due to the multimode fiber's inherent modal dispersion, this OPD value depends linearly on the fiber tail length l. An additional contribution to OPD can be generated in a metal-coated SNOM tip due to a mode-dependent photon-plasmon coupling strength resulting in generation of SPPs with different propagation velocities. For an Al-coated 200 nm SNOM tip spectra of transmitted light have been registered for ten different l values. An extrapolation of the linear OPD (l) dependence to l=0 yields a significant residual OPD value, indicating according to our theoretical considerations a mode-selective SPP excitation in the metal-coated tip. The modal dispersion is shown to switch its sign in the SNOM tip. First results of analogous experiments with an Al-coated 150 nm SNOM tip confirm our conclusions.

Emission of photon pairs by metal-dielectric interface in case of a superluminally propagating la... more Emission of photon pairs by metal-dielectric interface in case of a superluminally propagating laser-induced nonlinear polarization is considered. Using oblique incidence of the laser wave it is possible to tune frequencies of generated photons due to the Doppler effect. For every frequency smaller than frequency of induced polarization there exist an excitation angle when singular enhancement of the emission takes place. Emitted photon pairs are in the polarization entangled state. The yield of emission is estimated.

Emission of pairs of photons in the interface metal-dielectric under the laser excitation arising... more Emission of pairs of photons in the interface metal-dielectric under the laser excitation arising due to the time-dependent perturbation of the zero-point fluctuations of the electromagnetic field by photons of the laser is considered. The enhancement of this emission by surface plasmons may be used for getting polarization-entangled photons. A possibility to compensate the energy of the zero-point fluctuations of bosons by other fluctuations with negative energy is discussed.

NATO Science for Peace and Security Series B: Physics and Biophysics, 2012

ABSTRACT The effect of a tapered Al-coated optical fiber terminated by a subwavelength aperture (... more ABSTRACT The effect of a tapered Al-coated optical fiber terminated by a subwavelength aperture (SWA) on the spectrum of the transmitted light is investigated experimentally. Under certain conditions a remarkable spectral modulation of the transmitted light can be observed [1]. This effect is of a mesoscopic origin, occurring only for a certain interval of SWA diameters. A noticeable modulation appears when the number of the transmitted fiber modes is small but exceeds unity, thus indicating the presence of a phase shift between different modes.

Advanced Photonics, 2014

ABSTRACT The emission of polarization entangled photons by a metal-dielectric interface in case o... more ABSTRACT The emission of polarization entangled photons by a metal-dielectric interface in case of superluminally propagating laser-induced nonlinear polarization is considered. The emission is strongly enhanced for definite intensity and excitation angle.

Chemical Physics, 2015

ABSTRACT Chemically bound structures of several benzene molecules are studied both analytically a... more ABSTRACT Chemically bound structures of several benzene molecules are studied both analytically and numerically. The bonds in these structures are established by replacing the intra π- bonds of C6 rings by the inter σ-bonds. The rearrangements of different π- bonds may take place differently which causes distortions of C6 rings. The reason of the distortions is the pseudo-Jahn-Teller effect (PJTE). In the case of two chemically bound benzene molecules in a hollow position (with direct on-top stacking), called as bi-benzene, three different distorted states in addition to the undistorted one are found to exist. PJTE leads also to a chemical bonding of three and more benzene molecules stacked directly on-top of each other. These bound structures do not exist for undistorted molecules. All bound states, although being metastable are separated from the unbound ones by energy barriers ≳ 2 eV.. It is found that the height of the barrier for symmetric bi-benzene is essentially affected by the Jahn-Teller effect.

The Journal of chemical physics, Jan 21, 2014

A theoretical study of time-dependent dynamical Jahn-Teller effect in an impurity center in a sol... more A theoretical study of time-dependent dynamical Jahn-Teller effect in an impurity center in a solid is presented. We are considering the relaxation of excited states in the E⊗e-problem through the conical intersection of the potential energy. A strict quantum-mechanical treatment of vibronic interactions with both the main Jahn-Teller active vibration and the nontotally symmetric phonons causing the energy loss is given. The applied method enables us to calculate the time-dependence of the distribution function of the basic configurational coordinate. We have performed a series of numerical calculations allowing us, among other relaxation features, to visualise the details of the relaxation through the conical intersection. In particular, we elucidate how the Slonczewski quantization of the states in the conical intersection affects the relaxation.

Physical review. B, Condensed matter, 1996