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DYNAMICAL CHAOS IN SU(2) CIRCLE-TIMES-U (1) THEORY / G. . BERMAN [et al.] // Phys. Lett. A. - 1994. - Vol. 194, Is. 4. - P. 251-264, DOI 10.1016/0375-9601(94)91247-5. - Cited References: 26 . - ISSN 0375-9601

РУБ Physics, Multidisciplinary
Рубрики:
GAUGE-THEORY
SYSTEMS
FIELDS
Аннотация: We study the dynamics of the classical homogeneous SU(2) x U(1) gauge theory in the spontaneously broken phase. A transition from regular to chaotic dynamics is shown to occur for energy densities epsilon 0.3m(w)2/G(F) almost-equal-to 2 x 10(10) GeV/fm3. The regular regime is characterized by a sharp frequency spectrum for the Yang-Mills fields. The frequency spectrum in the chaotic regime is continuous and the sharp frequency lines of the regular regime are dispersed. In the early universe or at high energy densities in a Yang-Mills plasma this transition may have observable effects that can be studied by analyzing the frequency spectrum and the time correlation functions. In the chaotic regime these time correlation functions decay considerably faster than in the regular regime.

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Держатели документа:
KIRENSKY PHYS INST,KRASNOYARSK 660036,RUSSIA
LOS ALAMOS NATL LAB,DIV THEORET,LOS ALAMOS,NM 87545
ИФ СО РАН

Доп.точки доступа:
BERMAN, G.; Bulgakov, E. N.; Булгаков, Евгений Николаевич; HOLM, D.; KLUGER, Y.
}
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Bondarenko, I. N.
Magnetic transitions in layered triangular antiferromagnets / I. N. Bondarenko, R. S. Gekht, V. I. Ponomarev // Phys. Lett. A. - 1996. - Vol. 222, Is. 4. - P. 269-274, DOI 10.1016/0375-9601(96)00635-4. - Cited References: 22 . - ISSN 0375-9601

РУБ Physics, Multidisciplinary
Рубрики:
HEISENBERG-ANTIFERROMAGNET
   PHASE-TRANSITION
   VBR2
   SYSTEMS
   FIELD
   VCL2
Кл.слова (ненормированные):
triangular antiferromagnets -- quantum and thermal fluctuations -- successive phase transitions -- Quantum and thermal fluctuations -- Successive phase transitions -- Triangular antiferromagnets
Аннотация: Magnetic states and phase transitions of the layered triangular antiferromagnets in an applied field are studied. It is shown that in compounds like VBr2 and VCl2 quantum effects change the ground state structure and cause successive phase transitions as the magnetic field increases. Coplanar structures of different spin configuration are realized far from the saturation field and a noncoplanar structure of umbrella-type configuration is realized near this field. The ground-state phase diagram is constructed, and a finite region of fields where the collinear phase is also possible is indicated.

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Держатели документа:
Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036, Russian Federation

Доп.точки доступа:
Gekht, R. S.; Ponomarev, V. I.
}
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Aplesnin, S. S.
Dimerization of antiferromagnetic chain with 4-spin interaction / S. S. Aplesnin // Fiz. Tverd. Tela. - 1996. - Vol. 38, Is. 6. - P. 1868-1877. - Cited References: 30 . - ISSN 0367-3294

РУБ Physics, Condensed Matter
Рубрики:
SPIN-1/2 HEISENBERG-ANTIFERROMAGNET
   COMPETING INTERACTIONS
   MONTE-CARLO
   THERMODYNAMIC PROPERTIES
   SYSTEMS
   CUGEO3
   TEMPERATURE
   NEUTRON
   STATE
   MODEL

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Wigner function description of ac transport through a two-dimensional quantum point contact / I. E. Aronov [et al.] // J. Phys.: Condens. Matter. - 1997. - Vol. 9, Is. 24. - P. 5089-5103, DOI 10.1088/0953-8984/9/24/009. - Cited References: 45 . - ISSN 0953-8984

РУБ Physics, Condensed Matter
Рубрики:
QUANTIZED CONDUCTANCE
   BALLISTIC-RESISTANCE
   CONSTRICTION
   CAPACITANCE
   ADMITTANCE
   ELECTRONS
   SYSTEMS
   FIELD
   PUMP
Аннотация: We have calculated the admittance of a two-dimensional quantum point contact (QPC) using a novel variant of the Wigner distribution function (WDF) formalism. In the semiclassical approximation, a Boltzmann-like equation is derived for the partial WDF describing both propagating and non-propagating electron modes in an effective potential generated by the adiabatic QPC. We show that this quantum kinetic approach leads to the well known stepwise behaviour of the real part of the admittance (the conductance), and of the imaginary part of the admittance (the emittance), in agreement with the latest results derived by Christen and Buttiker, which is determined by the number of propagating electron modes. It is shown that the emittance is sensitive to the geometry of the QPC, and can be controlled by the gate voltage. We have established that the emittance has contributions corresponding to both quantum inductance and quantum capacitance. Stepwise oscillations in the quantum inductance are determined by the harmonic mean of the velocities for the propagating modes, whereas the quantum capacitance is a significant mesoscopic manifestation of the nonpropagating (reflecting) modes.

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Держатели документа:
LOS ALAMOS NATL LAB,CNLS,LOS ALAMOS,NM 87545
UKRAINIAN ACAD SCI,INST RADIOPHYS & ELECT,UA-310085 KHARKOV,UKRAINE
LV KIRENSKII INST PHYS,KRASNOYARSK 660036,RUSSIA
UNIV ILLINOIS,DEPT PHYS,URBANA,IL 61801
ИФ СО РАН
Theoretical Division, CNLS, Los Alamos National Laboratory, Los Alamos, NM 87545, United States
Inst. Radiophysics and Electronics, Natl. Academy of Sciences of Ukraine, 12 Acad Proskura Street, 310085, Kharkov, Ukraine
Kirensky Institute of Physics, 660036, Krasnoyarsk, Russian Federation
Department of Physics, Univ. Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801-3080, United States

Доп.точки доступа:
Aronov, I. E.; Berman, G. P.; Campbell, D. K.; Dudiy, S. V.
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Aplesnin, S. S.
Modeling a dimer state in CuGeO3 in the two-dimensional anisotropic Heisenberg model with alternated exchange interaction / S. S. Aplesnin // J. Exp. Theor. Phys. - 1997. - Vol. 85, Is. 6. - P. 1196-1203, DOI 10.1134/1.558393. - Cited References: 33 . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
SPIN-PEIERLS TRANSITION
   HIGH MAGNETIC-FIELDS
   COMPOUND CUGEO3
   GROUND-STATE
   SYSTEMS
   NEUTRON
Аннотация: The two-dimensional Heisenberg spin-1/2 model with alternated exchange interaction along the c axis and an anisotropic distribution of the exchange interaction in the lattice, J(b)/J(c)=0.1, is examined. A quantum Monte Carlo method is used to calculate the phase diagrams of the antiferromagnet, the dimer state in a plane, the value of the alternation delta of the exchange interaction, and the anisotropy Delta=1-J(xy)/J(z) of the exchange interaction, Delta similar to delta(0.58(6)). The following characteristics are calculated for Delta=0.25: the dependence of the temperature of the dimer-state-paramagnet transition on the alternation of the exchange interaction, T-c(delta)=0.55(4(delta-0.082(6))(0.50(3)), the singlet-triplet energy gap, and the dependence of the magnetization on the external field for some values of delta. The value of the exchange interaction, J(c)=127 K, the alternation of the exchange interaction, delta=0.11J(c), and the correlation radius along the c axis, xi(c) approximate to 28c, are determined. Finally, it is found that the temperature dependence of the susceptibility and the specific heat are in good agreement with the experimental data. (C) 1997 American Institute of Physics. [S1063-7761(97)01912-4].

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович
}
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Berman, G. P.
Error correction for a spin quantum computer / G. P. Berman, D. K. Campbell, V. I. Tsifrinovich // Phys. Rev. B. - 1997. - Vol. 55, Is. 9. - P. 5929-5936, DOI 10.1103/PhysRevB.55.5929. - Cited References: 26 . - ISSN 0163-1829

РУБ Physics, Condensed Matter
Рубрики:
SYSTEMS
   COMPUTATION
   UNIVERSAL
   DYNAMICS
   LOGIC
Аннотация: The problems of error correction in a spin quantum computer are discussed. For digital processing in the Ising and Heisenberg chains driven by a resonant electromagnetic field, the simple schemes are suggested which provide correction of errors caused by imperfect pi pulses, and prevent the most significant errors caused by the nonresonant action of rr pulses. The probability of error caused by the Heisenberg interaction during the action of rr pulses is estimated. For quantum computations in spin systems a principal opportunity to correct the phase errors, based on Steane's three quantum-bits scheme, is described.

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Держатели документа:
LOS ALAMOS NATL LAB,CTR NONLINEAR STUDIES,LOS ALAMOS,NM 87545
LV KIRENSKII INST PHYS,KRASNOYARSK 660036,RUSSIA
UNIV ILLINOIS,DEPT PHYS,URBANA,IL 61801
POLYTECH INST NEW YORK,DEPT APPL MATH & PHYS,BROOKLYN,NY 11201
ИФ СО РАН

Доп.точки доступа:
Campbell, D. K.; Tsifrinovich, V. I.
}
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Alekseev, K. N.
Light squeezing at the transition to quantum chaos / K. N. Alekseev, J. . Perina // Phys. Rev. E. - 1998. - Vol. 57, Is. 4. - P. 4023-4034, DOI 10.1103/PhysRevE.57.4023. - Cited References: 62 . - ISSN 1063-651X

РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
HIGHLY-EXCITED ATOMS
   ELECTROMAGNETIC-FIELD
   ANHARMONIC-OSCILLATOR
   MICROWAVE IONIZATION
   MONOCHROMATIC-FIELD
   CLASSICAL MECHANICS
   PERIODIC-ORBITS
   RYDBERG ATOMS
   HYDROGEN-ATOM
   SYSTEMS
Аннотация: We investigate theoretically the dynamics of squeezed state generation in nonlinear systems possessing a transition from regular to chaotic dynamics in the limit of a large number of photons. As an example, the model of a kicked Kerr oscillator is considered. We show that at the transition to quantum chaos the maximum possible degree of squeezing increases exponentially in time, in contrast to the regular dynamics, where the degree of squeezing increases only powerwise in time. We demonstrate the one-to-one correspondence of the degree of squeezing and the value of the local Lyapunov instability rate in the corresponding classical chaotic system.

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Держатели документа:
Abo Akad, Dept Phys, SF-20500 Turku, Finland
Russian Acad Sci, LV Kirensky Phys Inst, Theory Nonlinear Proc Lab, Krasnoyarsk 660036, Russia
Palacky Univ, Dept Opt, Olomouc 77207, Czech Republic
Palacky Univ, Joint Lab Opt, Olomouc 77207, Czech Republic
ИФ СО РАН

Доп.точки доступа:
Perina, J.
}
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Aplesnin, S. S.
Quantum spin liquid in the 2D anisotropic Heisenberg model with frustrated next nearest neighbor exchange / S. S. Aplesnin // Low Temp. Phys. - 1998. - Vol. 24, Is. 8. - P. 572-577 ; Физика низких температур, DOI 10.1063/1.593639. - Cited References: 25 . - ISSN 1063-777X

РУБ Physics, Applied
Рубрики:
SQUARE-LATTICE ANTIFERROMAGNETS
   VALENCE BOND STATES
   SYSTEMS
   SUPERCONDUCTIVITY
   SYMMETRY
Аннотация: The two-dimensional (2D) Heisenberg model with anisotropic exchange (Delta = 1 - J(x)/J(z)) and with negative next nearest neighbor exchange (J(2)) with S = 1/2 is investigated by using the quantum-mechanical Monte-Carlo method. The energy, magnetic moment at a site, heat capacity, and spin-spin correlation functions are calculated. The stability regions for Neel ordering of spins as well as the strip-phase and gapless quantum spin liquid are determined in the interval Delta/2 less than or equal to J(2)/ J(1)less than or equal to 1/(2 Delta). (C) 1998 American Institute of Physics. [S1063-777X(98)00808-1].

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Держатели документа:
Russian Acad Sci, LV Kirenskii Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович

}
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Aplesnin, S. S.
Quantum Monte Carlo analysis of the 2D Heisenberg antiferromagnet with S=1/2: the influence of exchange anisotropy / S. S. Aplesnin // J. Phys.: Condens. Matter. - 1998. - Vol. 10, Is. 44. - P. 10061-10065, DOI 10.1088/0953-8984/10/44/012. - Cited References: 21 . - ISSN 0953-8984

РУБ Physics, Condensed Matter
Рубрики:
SQUARE LATTICE
SYSTEMS
MODEL
Аннотация: The two-dimensional (2D) Heisenberg model with exchange anisotropy Delta = 1 - J(x)/J(z) (J 0) and S

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Держатели документа:
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
L V Kirensky Institute of Physics, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Аплеснин, Сергей Степанович
}
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10.

Spontaneous dc current generation in a resistively shunted semiconductor superlattice driven by a terahertz field / K. N. Alekseev [et al.] // Phys. Rev. Lett. - 1998. - Vol. 80, Is. 12. - P. 2669-2672, DOI 10.1103/PhysRevLett.80.2669. - Cited References: 21 . - ISSN 0031-9007

РУБ Physics, Multidisciplinary
Рубрики:
DYNAMIC LOCALIZATION
   BLOCH OSCILLATIONS
   ELECTRIC-FIELD
   THZ-FIELD
   PENDULUM
   CHAOS
   TIME
   SUPPRESSION
   SYSTEMS
Аннотация: We study a resistively shunted semiconductor superlattice subject to a high-frequency electric field. Using a balance equation approach that incorporates the influence of the electric circuit, we determine numerically a range of amplitude and frequency of the ac field for which a de bias and current are generated spontaneously and show that this region is likely accessible to current experiments. Our simulations reveal that the Bloch frequency corresponding to the spontaneous de bias is approximately an integer multiple of the ac field frequency.

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Держатели документа:
Univ Illinois, Dept Phys, Urbana, IL 61801 USA
NORDITA, DK-2100 Copenhagen O, Denmark
LV Kirensky Phys Inst, Theory Nonlinear Proc Lab, Krasnoyarsk 660036, Russia
Loughborough Univ Technol, Dept Phys, Loughborough LE11 3TU, Leics, England
ИФ СО РАН

Доп.точки доступа:
Alekseev, K. N.; Cannon, E. H.; McKinney, J. C.; Kusmartsev, F. V.; Campbell, D. K.
}
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11.

Alekseev, K. N.
Squeezed states and quantum chaos / K. N. Alekseev, D. S. Priimak // J. Exp. Theor. Phys. - 1998. - Vol. 86, Is. 1. - P. 61-70, DOI 10.1134/1.558469. - Cited References: 41 . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
PERIODICALLY KICKED PENDULUM
   CLASSICAL CORRESPONDENCE
   SYSTEMS
   LIGHT
   FLUCTUATIONS
   OSCILLATOR
   MECHANICS
   MASER
Аннотация: We examine the dynamics of a wave packet that initially corresponds to a coherent state in the model of a quantum rotator excited by a periodic sequence of kicks. This model is the main model of quantum chaos and allows for a transition from regular behavior to chaotic in the classical limit. By doing a numerical experiment we study the generation of squeezed states in quasiclassical conditions and in a time interval when quantum-classical correspondence is well-defined. We find that the degree of squeezing depends on the degree of local instability in the system and increases with the Chirikov classical stochasticity parameter. We also discuss the dependence of the degree of squeezing on the initial width of the packet, the problem of stability and observability of squeezed states in the transition to quantum chaos, and the dynamics of disintegration of wave packets in quantum chaos. (C) 1998 American Institute of Physics.

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Priimak, D. S.
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12.

Ignatchenko, V. A.
Spectrum of waves in randomly modulated multilayers / V. A. Ignatchenko, Y. I. Mankov, A. A. Maradudin // Phys. Rev. B. - 1999. - Vol. 59, Is. 1. - P. 42-45, DOI 10.1103/PhysRevB.59.42. - Cited References: 14 . - ISSN 0163-1829

РУБ Physics, Condensed Matter
Рубрики:
SEMICONDUCTOR SUPERLATTICES
LOCALIZATION
SYSTEMS
Аннотация: The spectrum and damping of waves in partially randomized multilayer structures are calculated. A method of calculation which was proposed and demonstrated earlier for the model of a superlattice with a harmonic dependence of its material parameters along its axis in the initial state, is extended here to the case of a multilayer structure (i.e., a superlattice with sharp interfaces). One- and three-dimensional inhomogeneities are considered, and the correlation function of the superlattice is derived. The spectrum and damping of waves in the superlattice described by this correlation function are found in the weak-coupling approximation in the vicinities of all the odd Brillouin zone boundaries. [S0163-1829(99)14501-6].

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Держатели документа:
LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA
ИФ СО РАН

Доп.точки доступа:
Mankov, Y. I.; Maradudin, A. A.; Игнатченко, Вальтер Алексеевич
}
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13.

Ignatchenko, V. A.
The spectrum and damping of waves in partially randomized multilayers / V. A. Ignatchenko, Y. I. Mankov, A. A. Maradudin // J. Phys.: Condens. Matter. - 1999. - Vol. 11, Is. 13. - P. 2773-2790, DOI 10.1088/0953-8984/11/13/013. - Cited References: 24 . - ISSN 0953-8984

РУБ Physics, Condensed Matter
Рубрики:
SPIN-WAVES
   SEMICONDUCTOR SUPERLATTICES
   LOCALIZATION
   SYSTEMS
Аннотация: The spectrum and damping of waves in partially randomized multilayer structures are calculated. A method of calculation that was proposed and demonstrated earlier, for the model of a superlattice with a harmonic dependence of its material parameters along its axis in the initial state, is extended to the case of a multilayer structure (i.e., a superlattice with sharp interfaces). One- and three-dimensional random modulations of the period are considered, and the correlation function of the superlattice is derived as a series in which each term is a product of a harmonic and a monotonically decaying function. The law of decay of the correlation function is Gaussian for smooth inhomogeneities, and has different forms for one- and three-dimensional short-wavelength inhomogeneities. The spectrum and damping of waves in the superlattice described by this correlation function are found in the weak-coupling approximation in the vicinities of all of the odd Brillouin zone boundaries. Analytical dependences of the main characteristics of the spectrum and damping on the zone number n are obtained. The conditions for the closing of the gaps at the Brillouin zone boundaries are derived, and depend on the dimensionality of the inhomogeneities and the degree of their smoothness.

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Держатели документа:
LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
Univ Calif Irvine, Irvine, CA 92697 USA
ИФ СО РАН
L V Kirensky Institute of Physics, 660036 Krasnoyarsk, Russian Federation
University of California, Irvine, CA 92697 4575, United States

Доп.точки доступа:
Mankov, Y. I.; Maradudin, A. A.; Игнатченко, Вальтер Алексеевич
}
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14.

Aplesnin, S. S.
Investigation of the magnetic properties of chains with alternating ferro- and antiferromagnetic exchange interactions in the Heisenberg model with spin S=1/2 / S. S. Aplesnin, G. A. Petrakovskii // Phys. Solid State. - 1999. - Vol. 41, Is. 9. - P. 1511-1512, DOI 10.1134/1.1131042. - Cited References: 11 . - ISSN 1063-7834

РУБ Physics, Condensed Matter
Рубрики:
HALDANE-GAP
SYSTEMS
Аннотация: The quantum Monte Carlo method is used to calculate the susceptibility and pairwise spin-spin correlation functions of chains with alternating ferro (K)- and antiferromagnetic (J)-exchange interactions within the Heisenberg model with spin S=1/2. From the susceptibility, the energy gap between the ground state and excited triplet states is determined for arbitrary ratios K/J. The value of the gap coincides with the Haldane gap for spin S=1 when K/J 1.25. (C) 1999 American Institute of Physics. [S1063-7834(99)02409-0].

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Публикация на русском языке Аплеснин, Сергей Степанович. Исследование магнитных свойств цепочки с чередующимися ферро- и антиферромагнитными обменными взаимодействиями в модели Гейзенберга со спином S=1/2 [Текст] / С. С. Аплеснин, Г. А. Петраковский // Физ. тверд. тела. - Санкт-Петербург, 1999. - Т. 41 Вып. 9. - С. 1650-1651

Держатели документа:
Russian Acad Sci, Siberian Branch, LV Kirenskii Inst Phys, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Petrakovskii, G. A.; Петраковский, Герман Антонович; Аплеснин, Сергей Степанович
}
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15.

Gluck, M.
Lifetime statistics for a Bloch particle in ac and dc fields / M. . Gluck, A. R. Kolovsky, H. J. Korsch // Phys. Rev. E. - 1999. - Vol. 60, Is. 1. - P. 247-258, DOI 10.1103/PhysRevE.60.247. - Cited References: 27 . - ISSN 1063-651X

РУБ Physics, Fluids & Plasmas + Physics, Mathematical
Рубрики:
DYNAMIC LOCALIZATION
   QUANTUM
   TRANSITION
   SCATTERING
   MATRICES
   SYSTEMS
   LADDER
   STATES
   ATOMS
   LIGHT
Аннотация: We study the statistics of the Wigner delay time and resonance width for a Bloch particle in ac and de fields in the regime of quantum chaos. It is shown that after appropriate rescaling the distributions of these quantities have a universal character predicted by the random matrix theory of chaotic scattering. [s1063-651X(99)09907-9].

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Держатели документа:
Univ Kaiserslautern, Fachbereich Phys, D-67653 Kaiserslautern, Germany
LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Kolovsky, A. R.; Коловский, Андрей Радиевич; Korsch, H. J.
}
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16.

Aplesnin, S. S.
Quantum Monte Carlo investigation of the magnetic properties of weakly interacting antiferromagnetic chains with an alternating exchange interaction with spin S=1/2 / S. S. Aplesnin // J. Exp. Theor. Phys. - 2000. - Vol. 90, Is. 1. - P. 194-201, DOI 10.1134/1.559075. - Cited References: 35 . - ISSN 1063-7761

РУБ Physics, Multidisciplinary
Рубрики:
PEIERLS COMPOUND CUGEO3
   MAGNON DISPERSION
   BI2CUO4
   EXCITATIONS
   RESONANCE
   SYSTEMS
   SCATTERING
   DYNAMICS
   NEUTRON
   PHASE
Аннотация: An approximation dependence of the spontaneous magnetic moment at a site, sigma/sigma(0) - 1 = 0.71(6)delta(2.5(2)), and the antiferromagnet-singlet state phase boundary, J(2)/J(1) = 0.52(3)delta, are determined by the quantum Monte Carlo method in the self-consistent sublattice molecular field approximation for weakly interacting (J(2)) antiferromagnetic chains with spin S = 1/2 and alternating exchange interaction (J(1) +/- delta). The Neel temperature and a number of critical temperatures which could be related with the filling energy of two singlets (Delta S-z = 0) and one triplet (Delta S-z= 1) spin bands, each of which is split by the sublattice field (h(x,y)not equal h(z)) into two subbands, are determined on the basis of the computed correlation radii of the two- and four-spin correlation function, the squared total spin (S-z)(2) with respect to the longitudinal components, the dimerization parameter, and the correlation functions between the nearest neighbors with respect to longitudinal and transverse spin components. On the basis of the Monte Carlo calculations, the critical temperatures and possible energy gaps at the band center are determined for the antiferromagnets CuWO4 and Bi2CuO4 and for the singlet compounds (VO)(2)P2O7 and CuGeO3 , agreeing satisfactorily with existing results, and new effects are also predicted. (C) 2000 MAIK "Nauka / Interperiodica".

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Держатели документа:
Russian Acad Sci, Siberian Div, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович
}
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17.

Aplesnin, S. S.
Static and dynamic magnetic properties of coupled spin-1/2 antiferromagnetic chains / S. S. Aplesnin // J. Phys.: Condens. Matter. - 2000. - Vol. 12, Is. 37. - P. 8191-8207, DOI 10.1088/0953-8984/12/37/316. - Cited References: 21 . - ISSN 0953-8984

РУБ Physics, Condensed Matter
Рубрики:
ONE-DIMENSIONAL ANTIFERROMAGNETS
   SYSTEMS
   SUSCEPTIBILITY
   EXCITATIONS
   SR2CUO3
   CA2CUO3
   KCUF3
Кл.слова (ненормированные):
Computational methods -- Copper compounds -- Correlation methods -- Functions -- Magnetic field effects -- Magnetic properties -- Magnetization -- Monte Carlo methods -- Quantum theory -- Specific heat -- Thermal effects -- Excitation spectroscopy -- Interchain coupling -- Intrachain couplings -- Mean-field approximation -- Spin-spin correlation function -- Spinons -- Antiferromagnetic materials
Аннотация: Calculations of the thermodynamic quantities, and the spectra of spinons, triplet excitations, and two-particle spin-singlet (Delta S-z = 0, +/- 1) excitations for a weakly coupled antiferromagnetic S = 1/2 spin chain are made using a mean-field approximation for the interchain couplings (J(2)) by the quantum Monte Carlo method. The mass gaps in these excitation spectra are estimated as functions of the interchain coupling. The critical held H-c, and the temperatures at which the spinon and singlet gaps close (T-1 and T-2, respectively) are obtained. Some peculiarities of the staggered magnetization, the specific heat, and the spin-spin correlation function are found at T-1 = 0.9J(2), T-2 = 1.5J(2), H-c = 3.8J(2), as determined by linear function fitting for J(2)/J(1) < 0.15 The intrachain and interchain couplings, and the staggered magnetization for KCuF3, Sr2CuO3, and Ca2CuO3 are estimated, and mass gaps are predicted to exist in the spectra of the spinons and the singlet two-particle excitations.

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Держатели документа:
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
L V Kirensky Institute of Physics, Siberian Br. Russ. Acad. of Sci., Krasnoyarsk, 660036, Russian Federation

Доп.точки доступа:
Аплеснин, Сергей Степанович
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18.

Gluck, M.
Fractal stabilization of Wannier-Stark resonances / M. . Gluck, A. R. Kolovsky, H. J. Korsch // Europhys. Lett. - 2000. - Vol. 51, Is. 3. - P. 255-260, DOI 10.1209/epl/i2000-00345-2. - Cited References: 17 . - ISSN 0295-5075

РУБ Physics, Multidisciplinary
Рубрики:
BLOCH PARTICLE
   FIELDS
   STATISTICS
   QUANTUM
   SYSTEMS
   AC
   DC
   ELECTRONS
Аннотация: The quasienergy spectrum of a Bloch electron affected by dc-ac fields is known to have a fractal structure as a function of the so-called electric matching ratio, which is the ratio of the ac field frequency and the Bloch frequency. This paper studies a manifestation of the fractal nature of the spectrum in the system "atom in a standing laser wave", which is a quantum-optical realization of a Bloch electron. It is shown that for an appropriate choice of the system parameters the atomic survival probability (a quantity measured in laboratory experiments) also develops a fractal structure as a function of the electric matching ratio. Numerical simulations under classically chaotic scattering conditions show good agreement with theoretical predictions based on random matrix theory.

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Держатели документа:
Univ Kaiserslautern, Fachbereich Phys, D-67653 Kaiserslautern, Germany
LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
ИФ СО РАН
Fachbereich Physik, Universitat Kaiserslautern, D-67653 Kaiserslautern, Germany
Kirensky Institute of Physics, 660036 Krasnoyarsk, Russian Federation

Доп.точки доступа:
Kolovsky, A. R.; Коловский, Андрей Радиевич; Korsch, H. J.
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19.

Aplesnin, S. S.
The study of magnetic properties of the quasi-one-dimensianal spin-1/2 antiferromagnet by Monte-Carlo method / S. S. Aplesnin // Phys. Low-Dimens. Struct. - 2000. - Vol. 07.08.2013. - P. 37-46. - Cited References: 15 . - ISSN 0204-3467

РУБ Physics, Applied + Physics, Condensed Matter
Рубрики:
ONE-DIMENSIONAL ANTIFERROMAGNETS
   SYSTEMS
   CHAINS
   CA2CUO3
Аннотация: The thermodynamic quantities, two- and four-spin correlation functions as well as the correlation radius for weakly coupled antiferromagnetic spin chains with S = 1/2 are calculated using the mean-field approximation for the interchain coupling (J(2)) for longitudinal and transverse spin components by quantum Monte Carlo method. Results for the staggered magnetization and Neel temperature are in agreement with general scaling arguments. The value of triplet DeltaS(z) =1 gp in the spectrum of excitations is estimated. The transverse staggered field was found to induce an additional maximum in the correlation radius of the four spin correlation function around T/J(1) approximate to [0.05 divided by 0.075), J(2)/J(1) 0.03.

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Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Branch, Krasnoyarsk 660036, Russia
ИФ СО РАН

Доп.точки доступа:
Аплеснин, Сергей Степанович
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20.

    Arkhipkin, V. G.
    Adiabatic propagation of short pulses under conditions of electromagnetically induced transparency / V. G. Arkhipkin, I. V. Timofeev // Quantum Electron. - 2000. - Vol. 30, Is. 2. - P. 180-184, DOI 10.1070/QE2000v030n02ABEH001683. - Cited References: 31 . - ISSN 1063-7818
   Перевод заглавия: Адиабатическое распространение коротких импульсов в условиях электромагнитно-индуцированной прозрачности

РУБ Engineering, Electrical & Electronic + Physics, Applied
Рубрики:
POPULATION TRANSFER
   LASER-PULSES
   INTERFERENCE
   ENHANCEMENT
   COHERENCE
   QUANTUM
   SYSTEMS
   INDEX
Аннотация: The spatial and temporal dynamics of two short pulses propagating in an optically dense medium of resonant three-level Lambda-atoms is investigated numerically and analytically. The maximum coherence for the Raman transition due to coherent population trapping. it is shown that, at the initial stage of propagation, the waveforms of such pulses only slightly change along the length of the medium, which may considerably exceed the length of linear absorption for a single weak pulse. As the length of the absorbing medium increases, the energy of the probe (first) pulse is completely transferred into the second (control) pulse.

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Публикация на русском языке Архипкин, Василий Григорьевич. Адиабатическое распространение коротких импульсов в условиях электромагнитно-индуцированной прозрачности [Текст] / В. Г. Архипкин, И. В. Тимофеев // Квант. электрон. - 2000. - Т. 30 № 2. - С. 180-184

Держатели документа:
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Div, Krasnoyarsk 660036, Russia
Krasnoyarsk State Univ, Krasnoyarsk 660041, Russia

Доп.точки доступа:
Timofeev, I. V.; Тимофеев, Иван Владимирович; Архипкин, Василий Григорьевич
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