共查询到20条相似文献,搜索用时 352 毫秒
1.
V. L. Gilyarov A. I. Slutsker V. P. Volodin A. I. Laius 《Physics of the Solid State》1998,40(8):1404-1406
The dependence of the temperature on the external adiabatic deformation is determined for a one-dimensional model of a solid
— chains of atoms with an anharmonic interaction. The resulting dependences of the average kinetic and potential components
of the internal energy on this deformation are compared with a model of adiabatic loading of a single oscillator.
Fiz. Tverd. Tela (St. Petersburg) 40, 1548–1551 (August 1998) 相似文献
2.
A. S. Moskvin I. B. Krynetskii R. Shimchak Yu. D. Panov S. V. Naumov A. A. Samokhvalov 《Physics of the Solid State》1997,39(3):412-418
It is shown that the formation of tunnel paramagnetic centers — triplet spin centers with a strongly different adiabatic potential
in different spin states — can form in copper oxides based on CuO clusters. The results of measurements of the magnetization
and magnetostriction of CuO single crystals are reported. They attest to the presence of nonequilibrium spin states and confirm
the results obtained in the model of tunnel paramagnetic centers.
Fiz. Tverd. Tela (St. Petersburg) 39, 474–482 (March 1997) 相似文献
3.
T. D. Varfolomeeva S. V. Popova A. G. Lyapin V. V. Brazhkin S. G. Lyapin Yu. P. Kudryavtsev S. E. Evsyukov 《JETP Letters》1997,66(4):255-260
Structural transformations of the cumulene form of amorphous carbyne which are induced by heating at high pressure (7.7 GPa)
are investigated. These can be described by the sequence amorphous phase — crystal — amorphous phase — disordered graphite.
Raman scattering shows that predominately the chain structure of carbyne remains at the first three stages. It was found that
the intermediate crystalline phase is an unknown modification of carbon whose structure is identified as cubic (a=3.145 Å). A mechanism of structural transformations in carbyne that involves the formation of new covalent bonds between
chains is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 237–242 (25 August 1997) 相似文献
4.
Molecular-dynamics was used to investigate the structural changes occurring in a three-dimensional solid when the solid is
transferred from an amorphous into a crystalline state. Crystal cells of a new type — pentadecahedrons with five square lateral
faces and ten regular triangular faces at the vertices of a cell — were found for the first time in a computer experiment.
It is shown that a bistructure consisting of crystal cells of different types, including cells with five-fold symmetry axes,
are stable in the solid.
Fiz. Tverd. Tela (St. Petersburg) 40, 1919–1924 (October 1998) 相似文献
5.
A new protocol is proposed for quantum cryptography. The protocol is based on the use of a set of measurements which make
it possible to reconstruct completely the density matrix — the information carrier — of a physical system. Such a protocol
can be implemented by means of homodyne detection (well known in quantum optics) of an electromagnetic field. An example is
given of a quantum cryptosystem in which the vacuum state of the photon field is used as one of two information states.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 1, 64–68 (10 July 1997) 相似文献
6.
Optical-resonance-Raman scattering by acoustic phonons is used to study the effect of an electric field on the state of excitons
in GaAs/AlAs superlattices. When the energy of the exciting photon coincides with the energy of an exciton bound to Wannier-Stark
states of a heavy hole and electron with Δn=0,±1, the acoustic Raman scattering is enhanced. Oscillations in the intensity of the Raman spectrum in the electric field
are explained by resonance delocalization of the exciton ground state as it interacts with Wannier-Stark states of neighboring
quantum wells or with Wannier-Stark states of a higher electron miniband.
Fiz. Tverd. Tela (St. Petersburg) 40, 827–829 (May 1998) 相似文献
7.
C.P. Sun D.L. Zhou S.X. Yu X.F. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):145-155
Based on the Born-Oppenhemer approximation, the concept of adiabatic quantum entanglement is introduced to account for quantum
decoherence of a quantum system due to its interaction with a large system of one or a few degrees of freedom. In the adiabatic
limit, it is shown that the wave function of the total system formed by the quantum system plus the large system can be factorized
as an entangled state with correlation between adiabatic quantum states and quasi-classical motion configurations of the large
system. In association with a novel viewpoint about quantum measurement, which has been directly verified by most recent experiments
[e.g., S. Durr et al., Nature 33, 359 (1998)], it is shown that the adiabatic entanglement is indeed responsible for the quantum decoherence and thus can
be regarded as a “clean” quantum measurement when the large system behaves as a classical object. By taking the large system
respectively to be a macroscopically distinguishable spatial variable, a high spin system and a harmonic oscillator with a
coherent initial state, three illustrations are presented with their explicit solutions in this paper.
Received 26 February 2000 and Received in final form 14 July 2000 相似文献
8.
V. A. Stephanovich 《JETP Letters》1997,65(5):446-451
A theory of self-localized states of free carriers near polarization fluctuations (fluctuons) in disordered ferroelectrics
is developed. Calculations are carried out for the model disordered ferroelectric K1− x
LixTaO3 (x≪0.05). The basic characteristics of the fluctuon — the energy and radius of the fluctuon state — are calculated as functions
of the impurity dipole concentration and temperature. The theory predicts the appearence of stable fluctuon states in both
the mixed ferroelectric-dipole-glass phase (a dipole glass is the electric analog of a spin glass) and the dipole-glass state
of disordered ferroelectrics. The possible role of fluctuons in kinetic phenomena such as conductivity in these substances
is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 5, 425–429 (10 March 1997)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
9.
A model of a closed system with self-organization is presented. This is a simplified model of a multijunction SQUID in an
ac magnetic field. In our closed system, a self-organized critical state is realized on account of the fact that current dumping,
which gives rise to self-organization in open systems, is replaced here by a fundamentally different mechanism — annihilation
of the currents.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 2, 119–125 (25 January 1999) 相似文献
10.
A. P. Zhernov 《Physics of the Solid State》1998,40(3):377-382
The electronic specific heat of metals with quantum defects in the superconducting state is examined. The role of the electron-polaron
effect, as well as that of the level population factor of two-level states, is analyzed in an adiabatic approach. The cases
of intermediate and strong coupling are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 413–418 (March 1998) 相似文献
11.
G.Q. Li P. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(1):79-84
We investigate the conversion of ultracold bosonic atoms to heteronuclear tetramer
A3B by an Efimov resonance-assisted stimulated Raman adiabatic passage
scheme. In view of recent experiments involving heteronuclear Efimov trimers KKRb and
KRbRb [Phys. Rev. Lett. 103, 043201 (2009)], the intermediate state populated
by heteronuclear trimer A2B in the conversion process is considered. The
atom-molecule dark state solution for a system with a population imbalance is derived
analytically, and the role played by the imbalance in the conversion is studied. In
addition, the effects of the external field parameters (including photoassociated pulse
intensity, width, magnetic coupling strength and its detuning) on the conversion are
discussed via the concept of adiabatic fidelity. 相似文献
12.
A model of a ferromagnet with nonuniform dissipation is introduced for the Landau-Lifshitz equations. It is shown that in
this model a ferromagnet can be regarded as an oscillating active medium where the formation of autowave structures — spin
autowaves, pacemakers, and spiral waves — is possible. Their wave characteristics, expressed in terms of the parameters of
the medium, are found for a special case.
Fiz. Tverd. Tela (St. Petersburg) 39, 513–515 (March 1997) 相似文献
13.
Two-dimensional and three-dimensional bipolarons of large radius, symmetrized with respect to the coordinate parts of the
two-center wave functions, are investigated in the adiabatic approximation with allowance for dynamic interelectronic correlations.
The adiabatic potential lines are plotted. It is shown that the quasimolecular configuration appearing in the Hartree-Fock
approximation is unstable in both the two-dimensional and the three-dimensional cases. The ground state is a one-center configuration.
Estimates are given for the binding energy and the heat of dissociation of a bipolaron.
Fiz. Tverd. Tela (St. Petersburg) 39, 441–443 (March 1997) 相似文献
14.
We have studied the dynamics of intramolecular vibrational redistribution (IVR) from the initially excited mode v1 ≈ 3330 cm−1 (acetylene-type H-C bond) in H-C≡C-CF3 molecules in the gaseous phase by means of anti-Stokes spontaneous Raman scattering. The time constant of this process is
estimated as 2.3 ns—this is the slowest IVR time reported so far for the room-temperature gases. It is suggested that so long
IVR time with respect to the other propyne derivatives can be explained by a larger defect, in this case, of the Fermi resonance
of v1 with v2 + 2v7—the most probable doorway state leading to IVR from v1 to the bath of all vibrational-rotational states with the close energies. In addition, it is shown that the observed dynamics
is in agreement with a theoretical model assuming strong vibrational-rotational mixing. 相似文献
15.
A thermodynamic invariant in the form of the ratio of a vibrational frequency in an anharmonic solid to the temperature in
adiabatic processes is derived. The adiabatic invariance established is used to derive in a simple manner an expression for
the temperature change due to elastic adiabatic loading of solids (Kelvin's equation).
Fiz. Tverd. Tela (St. Petersburg) 41, 134–136 (January 1999) 相似文献
16.
V. A. Burdov 《JETP Letters》1999,70(6):390-395
It is shown that when a strong ac electric field acts on an electron in a double quantum well, the dipole moment is an almost
periodic function of the dc voltage applied to the structure. An antipolarization effect — the structure is polarized in a
direction opposite to the external field — appears during one half of the period.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 6, 386–391 (25 September 1999) 相似文献
17.
18.
V. S. Vorob’ev 《Journal of Experimental and Theoretical Physics》1999,89(4):740-745
The free energy of a crystal containing a given void fraction is derived in terms of the truncated interparticle Lennard-Jones
potential. The free energy is minimized over the void fraction at constant pressure and temperature. It is shown that for
all pressures the optimal void fraction remains less than 1% as the temperature is raised. However, at some temperature it
grows suddenly and reaches values of the order of the percolation level for voids in a crystal, ∼0.125. At this point, the
crystal transitions to the liquid state takes place. The derived dependence of the transition temperature on the pressure—the
melting curve—is in good agreement with experimental data on the melting of solidified inert gases.
Zh. éksp. Teor. Fiz. 116, 1375–1385 (October 1999) 相似文献
19.
It is shown in numerical simulations with two-level atoms moving through a single-mode high-Q cavity that spontaneous emission of a new type — chaotic Rabi vacuum oscillations — arises in the strong atom-field coupling
regime.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 11, 801–806 (10 June 1997) 相似文献
20.
N. S. Ginzburg I. V. Zotova I. V. Konoplev A. S. Sergeev V. G. Shpak S. A. Shunailov M. R. Ul’maskulov M. I. Yalandin 《JETP Letters》1996,63(5):331-335
Intense (several hundreds of kilowatts) subnanosecond coherent microwave radiation — cyclotron superradiance of an electron
swarm moving in a uniform magnetic field — was recorded. The maximum power of the radiation was observed under group synchronization
conditions, when the translational velocity of the swarm is equal to the group velocity of the waves in the waveguide channel.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 5, 322–325 (10 March 1996) 相似文献