共查询到20条相似文献,搜索用时 31 毫秒
1.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
2.
K.T. Stoychev M.T. Primatarowa K. Marinov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):301-304
Effects of the exciton and polariton dispersions and the nonlinear exciton and photon interactions on the properties of polariton
solitons in molecular crystals are investigated. Higher-order terms and phase-modulation (chirp) are taken into account. Bright-
and dark-soliton solutions of the resulting modified nonlinear Schr?dinger (NLS) equation are presented. Nonlinearity- and
dispersion-induced critical points on the polariton dispersion curve are obtained, separating regions with different solutions.
Received 2 October 2001 / Received in final form 23 May 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: Stoychev@issp.bas.bg 相似文献
3.
T. Kanna M. Lakshmanan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):249-254
Soliton interactions in systems modelled by coupled nonlinear Schr?dinger (CNLS) equations and encountered in phenomena such
as wave propagation in optical fibers and photorefractive media possess unusual features: shape changing intensity redistributions,
amplitude dependent phase shifts and relative separation distances. We demonstrate these properties in the case of integrable
2-CNLS equations. As a simple example, we consider the stationary two-soliton solution which is equivalent to the so-called
partially coherent soliton (PCS) solution discussed much in the recent literature.
Received 1st October 2001 / Received in final form 4 February 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: lakshman@bdu.ernet.in 相似文献
4.
E. Nissimov S. Pacheva 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):197-201
The recently proposed supersymmetric extensions of reduced Kadomtsev-Petviashvili (KP) integrable hierarchies in N = 1, 2 superspace are shown to contain in the purely bosonic limit new types of ordinary non-supersymmetric integrable systems.
The latter are coupled systems of several multi-component non-linear Schr?dinger-like hierarchies whose basic nonlinear evolution
equations contain additional quintic and higher-derivative nonlinear terms. Also, we obtain the N = 2 supersymmetric extension of Toda chain model as Darboux-B?cklund orbit of the simplest reduced N = 2 super-KP hierarchy and find its explicit solution.
Received 13 September 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: nissimov@inrne.bas.bg
RID="b"
ID="b"e-mail: svetlana@inrne.bas.bg 相似文献
5.
S. Murugesh Radha Balakrishnan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):193-196
We apply our recent formalism establishing new connections between the geometry of moving space curves and soliton equations,
to the nonlinear Schr?dinger equation (NLS). We show that any given solution of the NLS gets associated with three distinct
space curve evolutions. The tangent vector of the first of these curves, the binormal vector of the second and the normal
vector of the third, are shown to satisfy the integrable Landau-Lifshitz (LL) equation = ×, ( = 1). These connections enable us to find the three surfaces swept out by the moving curves associated with the NLS. As an
example, surfaces corresponding to a stationary envelope soliton solution of the NLS are obtained.
Received 5 December 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: radha@imsc.ernet.in 相似文献
6.
We present a quantum mechanical framework for defining the statistics of measurements of
, A(t) being a quantum mechanical variable. This is a generalization of the so-called full counting statistics proposed earlier for DC electric currents. We develop an influence functional formalism that allows us to study the quantum system along with the measuring device while fully accounting for the back action of the detector on the system to be measured. We define the full counting statistics of an arbitrary variable by means of an evolution operator that relates the initial and final density matrices of the measuring device. In this way we are able to resolve inconsistencies that occur in earlier definitions. We suggest two schemes to observe the so defined statistics experimentally.Received: 30 June 2003, Published online: 15 October 2003PACS:
73.50.Td Noise processes and phenomena - 73.23.-b Electronic transport in mesoscopic systems - 74.40.+k Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.) 相似文献
7.
P.K. Shukla R. Fedele M. Onorato N.L. Tsintsadze 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):613-618
The nonlinear coupling between light beams and non-resonant ion density perturbations in a plasma is considered, taking into
account the relativistic particle mass increase and the light beam ponderomotive force. A pair of equations comprising a nonlinear
Schr?dinger equation for light beams and a driven (by the light beam pressure) ion-acoustic wave response is derived. It is
shown that the stationary solutions of our nonlinear equations can be represented in the form of a bright and dark/gray soliton
for the one-dimensional problem. We also present numerical results which exhibit that our bright soliton solutions are stable
exclusively for the values of the parameters compatible with our theory.
Received 24 July 2002 Published online 31 October 2002
RID="a"
ID="a"Permanent address: Dipartimento di Scienze Fisiche, Universitá Federico II and INFN, Complesso Universitario di M.S. Angelo, Via Cintia, 80126
Napoli, Italy e-mail: renato.fedele@na.infn.it
RID="b"
ID="b"Permanent address: Dipartimento di Fisica Generale, Universitá di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
RID="c"
ID="c"Permanent address: Institute of Physics, Georgian Academy of Sciences, Tbilisi 380077, Georgia 相似文献
8.
Th. Desaive M. Hennenberg G. Lebon 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):641-647
In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below.
The effect of rotation is restricted to the Coriolis force, neglecting thus the centrifugal effects, the porous medium is
described by Brinkman's model. The linear eigenvalue problem is solved by means of a modified Galerkin method. The behavior
of the critical temperature gradient is discussed in terms of various parameters of the system for both stationary and overstable
convections. Finally a weakly nonlinear analysis is provided to derive amplitude equations and to study the onset of Küppers-Lortz
instability.
Received 24 June 2002 / Received in final form 11 September 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: tdesaive@ulg.ac.be 相似文献
9.
M.T. Primatarowa K.T. Stoychev R.S. Kamburova 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):291-294
We investigate the propagation and interaction of solitons associated with circularly polarized vibrations in gyrotropic media.
The chirality of the structure yields different dispersion laws and hence different phase and group velocities for the left-
and right-handed modes. The helical arrangement of the monomers is modelled through first- and third-neighbour interactions.
The dynamics of the excitations is governed by a system of coupled discrete nonlinear Schr?dinger equations which is studied
both analytically and numerically. Depending on the initial conditions and the interaction constants, different evolutionary
patterns are obtained corresponding to unbound or bound one- and two-soliton solutions. The results can be applied to the
process of energy transfer in helical polymers.
Received 1st October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: krad@issp.bas.bg 相似文献
10.
M. Georgiev M. Mladenova V. Krastev A. Andreev 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):273-277
Substitutional impurity ions in crystals are known to displace off-center and to perform hindered rotations around the ideal
lattice positions. The vibronic theory to describe both the off-center displacements and the hindered rotations by a single
angular equation incorporates terms up to 3rd order in the off-center displacement coordinates. When the rotation is confined
to a single plane, the corresponding vibronic equation is equivalent to Mathieu's equation. Extending our earlier work, we
derive here the dipole-dipole coupling to take into account cooperative phenomena. We also derive the optical absorption band
arising from dipolar transitions across “Mexican Hat” surfaces, and we show that hindered rotations gives rise to magnetic
moments quantized in rotational bands.
Received 18 October 2001 / Received in final form 5 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: allxrose@hotmail.com 相似文献
11.
M. Giroud K. Hasselbach H. Courtois D. Mailly B. Pannetier 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):103-109
We present electrical transport experiments performed on submicron hybrid devices made of a ferromagnetic conductor (Co) and
a superconducting (Al) electrode. The sample was patterned in order to separate the contributions of the Co conductor and
of the Co-Al interface. We observed a strong influence of the Al electrode superconductivity on the resistance of the Co conductor.
This effect is large only when the interface is highly transparent. We characterized the dependence of the observed resistance
decrease on temperature, bias current and magnetic field. As the differential resistance of the ferromagnet exhibits a non-trivial
asymmetry, we claim that the magnetic domain structure plays an important role in the electron transport properties of superconducting
/ ferromagnetic conductors.
Received 9 July 2002 / Received in final form 22 October 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: herve.courtois@grenoble.cnrs.fr
RID="b"
ID="b"associated to Université Joseph Fourier 相似文献
12.
A. Borah S. Ghosh S. Nandy 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):221-225
The novel inelastic collision properties of two-soliton interaction for an n-component coupled higher order nonlinear Schr?dinger equation are studied. Some interesting features of three soliton interactions,
related to the integrability of the n-component coupled higher order nonlinear Schr?dinger equation are also discussed.
Received 17 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: abhijit@iitg.ernet.in
RID="b"
ID="b"e-mail: sasanka@iitg.ernet.in
RID="c"
ID="c"e-mail: sudipta@iitg.ernet.in 相似文献
13.
M.B. Sheftel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):203-206
Using the heavenly equation as an example, we propose the method of group foliation as a tool for obtaining non-invariant
solutions of PDEs with infinite-dimensional symmetry groups. The method involves the study of compatibility of the given equations
with a differential constraint, which is automorphic under a specific symmetry subgroup and therefore selects exactly one
orbit of solutions. By studying the integrability conditions of this automorphic system, i.e. the resolving equations, one can provide an explicit foliation of the entire solution manifold into separate orbits. The
new important feature of the method is the extensive use of the operators of invariant differentiation for the derivation
of the resolving equations and for obtaining their particular solutions. Applying this method we obtain exact analytical solutions
of the heavenly equation, non-invariant under any subgroup of the symmetry group of the equation.
Received 13 September 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: sheftel@gursey.gov.tr 相似文献
14.
Zhi Ping Wang Xi Xia Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):265-271
Rayleigh-Schr?dinger perturbation theory and an improved Wigner-Brillouin perturbation theory has been used to study the cyclotron
resonance of the polarons in ternary mixed crystals in the zero-temperature limit. The interaction between an electron and
two branches of longitudinal optical phonon modes is taken into account in the framework of the random-element-isodisplacement
model. The numerical results for several ternary mixed crystals show that the polaronic cyclotron energy and mass split successively
twice related to the higher and lower branches of longitudinal optical phonon modes of ternary mixed crystals. A non-linear
dependence of the polaronic cyclotron energy and mass on the composition x is found.
Received 19 March 2002 / Received in final form 21 March 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: xxliang@imu.edu.cn 相似文献
15.
J.C. Cao X.L. Lei 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):553-559
We have extended the balance equations to account for conduction-valence interband impact ionization (II) process induced
by an intense terahertz (THz) electromagnetic irradiation in semiconductors, and applied them to study the II effect on electron
transport and electron-hole pair generation-recombination rate in THz-driven InAs/AlSb heterojunctions (HJ). As many as needed
multiphoton channels are self-consistently taken into account for yielding a given accuracy. The time evolution of transport
state including THz-radiation-induced II process are monitored in details by an extensive time-dependent analysis. Two different
physical stages, the quasi-steady state and the complete steady-state, are clearly identified from the present calculations.
Intersubband electron transfer rate and net electron-hole generation rate are derived as functions of the THz radiation strength
E
ac for various radiation frequencies from f
ac = 0.42 to 6 THz at lattice temperatures T = 6 K. It's indicated that the THz radiation with a larger E
ac or a lower f
ac, has a stronger effect on electron transport and II process. Qualitative agreement is obtained between the calculated electron-hole
generation rate and the available experimental data for InAs/AlSb HJ's at T = 6 K.
Received 24 May 2002 / Received in final form 26 August 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: jccao8@hotmail.com 相似文献
16.
G. Perna V. Capozzi M.C. Plantamura A. Minafra S. Orlando V. Marotta 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):541-545
ZnSe films were deposited by pulsed laser ablation on a crystalline GaAs substrate and on an amorphous quartz substrate. The
deposition process was performed with the same growth parameters. The films were investigated by means of X-ray diffraction,
reflectance and photoluminescence spectroscopy. The X-ray diffraction spectra have demonstrated that the films grow in a highly
oriented way but having different orientations, i.e. the films deposited on GaAs grow (100)-oriented and the films deposited on quartz grow (111)-oriented. Reflectance spectra
as a function of the temperature have been analysed by means of the classical oscillator model, in order to obtain the temperature
dependence of the band gap energy. This gives results comparable to those of ZnSe single crystals for ZnSe on GaAs, but it
is red-shifted for ZnSe on quartz, because of lattice and thermal strains. The photoluminescence measurements at T = 10 K confirm the better quality of ZnSe deposited on GaAs and show that pulsed laser ablation is a promising technique
to grow films having intrinsic luminescence even on an amorphous substrate.
Received 29 May 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: giuseppe.perna@ba.infn.it 相似文献
17.
R. Rajaraman 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):157-162
We present here an elementary pedagogical introduction to CPN solitons in quantum Hall systems. We begin with a brief introduction to both CPN models and to quantum Hall (QH) physics. We then focus on spin and layer-spin degrees of freedom in QH systems and point
out that these are in fact CPN fields for N
= 1 and N
= 3. Excitations in these degrees of freedom will be shown to be topologically non-trivial soliton solutions of the corresponding
CPN field equations. We conclude with a brief summary of our own recent work in this area, done with Sankalpa Ghosh.
Received 17 November 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: doug0700@mail.jnu.ac.in 相似文献
18.
A. Andreoni M. Bondani G.M. D'Ariano M.G.A. Paris 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):415-421
We propose a novel scheme for the joint generation of two squeezed beams at arbitrary frequencies ω
1 and ω
2. The scheme consists of two successive steps, both involving nonlinear interactions in χ(2) crystals. The dynamics of the setup is analyzed both quantum mechanically and classically within the parametric approximation.
An experimental implementation involving the fundamental and the harmonics of a Nd:YAG laser pulse, and β-BaB
2
O
4 nonlinear crystals is suggested.
Received 17 May 2000 and Received in final form 9 October 2000 相似文献
19.
Radulescu O. Janssen T. Etrillard J. 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):385-398
We compare within an unifying formalism the dynamical properties of modulated and composite aperiodic (incommensurate) crystals.
We discuss the concept of inner polarization and we define an inner polarization parameter β that distinguishes between different
acoustic modes of aperiodic crystals. Although this concept has its limitations, we show that it can be used to extract valuable
information from neutron coherent inelastic scattering experiments. Within certain conditions, the ratio between the dynamic
and the static structure factors at various Bragg peaks depends only on β. We show how the knowledge of β for modes of an
unknown structure can be used to decide whether the structure is composite or modulated. The same information can be used
to predict scattered intensity within unexplored regions of the reciprocal space, being thus a guide for experiments.
Received 9 June 2002 Published online 14 October 2002
RID="a"
ID="a"e-mail: Ovidiu.Radulescu@univ-rennes1.fr 相似文献
20.
Ch. Nacke H. Stolz G. Manzke K. Henneberger 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):303-312
The influence of thermalized non-coherent carriers on the dielectric function of GaAs/AlAs quantum wells is investigated by
reflection spectroscopy. Experiments are performed using the method of spectral interferometry, where both amplitude and phase
of reflected pulses can be determined. For low excitation density the complex coefficient of reflection can be described using
as dielectric function a broadened Elliot formula. With increasing carrier density pronounced nonlinearities appear in both
amplitude and phase due to many-body effects between excited carriers. The nonlinear behavior fits very well to the results
of a many-body theory based on the Semiconductor Bloch equations including memory effects in the scattering processes between
carriers and the polarization induced by the probe pulse.
Received 29 May 2002 / Received in final form 23 September 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: manzke@physik3.uni-rostock.de 相似文献