共查询到20条相似文献,搜索用时 31 毫秒
1.
Based on the already-developed general theory (I.M. Sokolov, D.V. Kupriyanov, and M.D. Havey, JETP 112 (2), 246 (2011)), we have studied the spatial distribution of excited atoms and of the atomic polarization that a weak monochromatic
field creates in a dense ultracold atomic medium. We show that, in the case of a homogeneous random spatial distribution of
atoms, the amplitude of atomic polarization averaged over spatial configurations decreases outside boundary regions according
to an exponential law, while its phase linearly increases. Based on this, we have numerically determined the extinction coefficient
and the light wavelength in the medium, as well as its dielectric permittivity. The dispersion of the permittivity at different
concentrations has been studied. We show that, for dense clouds, the real part of the dielectric permittivity acquires negative
values in a certain frequency range. Based on the calculation of the spatial distribution of excited atoms, we have analyzed
the character of the transfer and trapping of quasi-resonant radiation in atomic clouds of differing density. 相似文献
2.
Results are presented on the search for anomalous transmission of ultracold neutrons (UCNs) through beryllium (thickness ∼0.14
mm), stainless steel (0.05 and 0.015 mm), and copper (0.01 and 0.018 mm) foils. This anomalous transmission is considered
to be a possible reason for the disappearance of UCNs from beryllium bottles, an effect which was discovered in experiments
at the St. Petersburg Nuclear Physics Institute and which was recently observed in the experiment of V. E. Varlamov et al., JETP Lett. 66, 336 (1997). No transmission was found in our measurements at the 10−7 level except in the case of copper foils, which we attribute to the presence in the UCN flux of an admixture of neutrons
with energies higher than the boundary energy for copper.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 440–444 (10 April 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
3.
S. A. Podoshvedov 《JETP Letters》2006,83(8):360-365
We generalize the scheme of conditional preparation of x(2) macroscopic entangled states [S.A. Podoshvedov, JETP 129 (2006)]. The studied system consists of a system of coupled down converters with type-I phase matching pumped simultaneously
by powerful optical fields in coherent states with one auxiliary photon in the superposition state of two input modes and
a projective measurement system. The projective measurement system involves two Hadamard gates introduced to generated output
modes followed by photodetectors. Identification of macroscopic entangled states is produced by registration of one photon.
No photon number resolving detection is required for the studied scheme.
The text was submitted by the author in English. 相似文献
4.
The purpose of this Letter is twofold. First, we generalize the correspondence between dynamical r-matrices and Poisson homogeneous spaces provided in Karolinsky, E. and Stolin, A [Lett. Math. Phys. 60 (2002), 257–274]. Secondly, we propose a quantization of this quasi-classical result. In particular, we explain the relationship between irreducible highest weight modules and equivariant quantization of coadjoint orbits.*Supported in part by the Royal Swedish Academy of Sciences**Supported in part by RFFI grant 02-01-00085a and CRDF grant RM1-2334-MO-02Mathematical Subject Classification (2000). 17B10, 17B20, 17B35, 17B62, 53C30. 相似文献
5.
Stimulated by the results of NMR experiments with superfluid 3He in “nematically ordered” aerogel [R. Sh. Askhadullin, V. V. Dmitriev, D. A. Krasnikhin, et al., JETP Lett. 95, 326 (2012)] we report on the results of phenomenological analysis of stability of different phases of superfluid 3He subjected to a strong homogeneous uniaxial anisotropy. On a basis of this analysis we suggest a form of the order parameter for the new ESP2 phase observed in the quoted experiments. In the weak coupling limit the suggested order parameter approaches that of the axi-planar phase. We discuss a possible experimental check of the proposed identification of the new phase. 相似文献
6.
Kh. G. Bogdanova V. A. Golenishchev-Kutuzov V. E. Leont’ev M. R. Nazipov M. M. Shakirzyanov M. I. Kurkin S. V. Petrov 《Journal of Experimental and Theoretical Physics》1999,88(5):947-953
An explanation is proposed for the gigantic magnetoacoustic effect that we observed in KMnF3 in previous work {Kh. G. Bogdanova, V. A. Golenishchev-Kutuzov, M. I. Kurkin et al., Zh. éksp. Teor. Fiz. 112, 1830 (1997) [JETP 85, 1001 (1997)]}. The effect entails a tenfold amplitude reduction of an acoustic pulse in a magnetic field that varies over
the range 0–8 kOe. It is shown that this effect is due to the interference of two nuclear magnetoelastic waves propagating
in the sample under magnetoacoustic resonance conditions, if this resonance occurs in the region of strong spatial dispersion
of nuclear spin waves. The effect is said to be gigantic because it exceeds in magnitude the magnetoacoustic effects observed
previously in magnetically ordered materials even though it is due to nuclear magnetism, which is 105 times weaker than electronic magnetism. We observe a concomitant anomalous dependence of the dispersion of the velocity of
sound on the external magnetic field.
Zh. éksp. Teor. Fiz. 115, 1727–1739 (May 1999) 相似文献
7.
《Journal of Nonlinear Mathematical Physics》2013,20(3):292-299
In this Letter a first-order Lagrangian for the Schrödinger–Newton equations is derived by modifying a second-order Lagrangian proposed by Christian [Exactly soluble sector of quantum gravity, Phys. Rev. D 56(8) (1997) 4844–4877]. Then Noether's theorem is applied to the Lie point symmetries determined by Robertshaw and Tod [Lie point symmetries and an approximate solution for the Schrödinger–Newton equations, Nonlinearity 19(7) (2006) 1507–1514] in order to find conservation laws of the Schrödinger–Newton equations. 相似文献
8.
The features of refraction (including the Goos-Hánchen effect) of a TM or TE bulk electromagnetic wave incident from outside
on the surface of a chiral magnetoelectric with the homogeneous antisymmetric magnetoelectric interaction has been analytically
studied on an example of the two-sublattice model of a multiferroic. In particular, it has been shown that the requirement
that the diagonal components of the permeability and permittivity tensors are simultaneously negative is not necessary for
the implementation of the properties of a left-handed medium. The results have been generalized to the case of an easy-axis
antiferromagnet with an antisymmetry center with the 4
z
±2
x
+
I
− structure in the static external magnetic field perpendicular to the easy axis of magnetization. Some results of this work
were preliminarily reported in D.V. Kulagin, G.G. Levchenko, A.S. Savchenko, A.S. Tarasenko, and S.V. Tarasenko, JETP Lett.
92, 511 (2010). 相似文献
9.
The transition between the texture of 3HeB confined by a set of parallel plates and the texture of bulk 3HeB influenced by a radio-frequency pulse is considered. The reverse relaxation process is studied experimentally. It turns out that the relaxation is not homogeneous. 相似文献
10.
The four-point correlation function has been studied in Liouville field theory. If one of the fields is degenerate, such a
function is described in terms of Coulomb integrals. Some nontrivial relations for these integrals have been found that can
be used to obtain new exact results in conformal field theory. In particular, a four-point correlation function has been calculated
in minimal quantum gravity. The result agrees with the results obtained recently by different methods [A. A. Belavin and A.
B. Zamolodchikov, JETP Lett. 82, 7 (2005); Theor. Math. Phys. 147, 729 (2006); A. B. Zamolodchikov, Theor. Math. Phys. 142, 183 (2005); I. K. Kostov and V. B. Petkova, Theor. Math. Phys. 146, 108 (2006)].
The text was submitted by the authors in English. 相似文献
11.
O.V. Oliinyk 《辐射效应与固体损伤》2013,168(5-6):519-541
ABSTRACTDissipative mechanism of formation of a modulated structure of vacancies in a body-centred cubic (b.c.c.) crystal is considered as its intrinsic property under an isothermal irradiation irrespectively of elastic-anisotropy factor sign. Conditions of self-organisation of a precursor of formation of a ‘superlattice’ of nanovoids, namely, the modulated structure in a spatial distribution of the diffusing vacancies generated by irradiation, because of the instability of their homogeneous distribution as a result of interaction between them in a b.c.c. host crystal under irradiation, are analysed. As shown for the first time, the ‘cohesive’ and ‘elastic’ couplings between interacting (and diffusing) vacancies have a crucial role in a pattern-selection process accordingly with different (positive or negative) elastic-anisotropy factors. 相似文献
12.
《Journal of Nonlinear Mathematical Physics》2013,20(1):96-105
Abstract The Einstein field equations for several cosmological models reduce to polynomial systems of ordinary differential equations. In this paper we shall concentrate our attention to the spatially homogeneous diagonal G 2 cosmologies. By using Darboux’s theory in order to study ordinary differential equations in the complex projective plane ??2 we solve the Bianchi V models totally. Moreover, we carry out a study of Bianchi VI models and first integrals are given in particular cases. 相似文献
13.
In this Letter we propose that for Lax integrable nonlinear partial differential equations the natural concept of weak solutions is implied by the compatibility condition for the respective distributional Lax pairs. We illustrate our proposal by comparing two concepts of weak solutions of the modified Camassa-Holm equation pointing out that in the peakon sector (a family of non-smooth solitons) only one of them, namely the one obtained from the distributional compatibility condition, supports the time invariance of the Sobolev H1 norm. 相似文献
14.
The study of double extensive air showers (EAS) with N e ≥ 5 · 106 particles separated in time by intervals of the order of 100 ns showed (JETP Lett. 85, 101 (2007)) that to explain the origin of “delayed” showers as a result of formation in the first interaction of heavy particles, the mass of such particles must reach 5 · 105 GeV. Such an explanation seems improbable. That is why it was assumed that advanced showers can be generated by tachyons. In this connection we decided to return to the analysis of our unpublished data on the anomalous events in X-ray films deep under the lead and soil. These events, we believe, can also be explained by the tachyon hypothesis. 相似文献
15.
Topological media are systems whose properties are protected by topology and thus are robust to deformations of the system.
In topological insulators and superconductors the bulk-surface and bulk-vortex correspondence gives rise to the gapless Weyl,
Dirac or Majorana fermions on the surface of the system and inside vortex cores. Here we show that in gapless topological
media, the bulk-surface and bulk-vortex correspondence is more effective: it produces topologically protected gapless fermions
without dispersion—the fiat band. Fermion zero modes forming the flat band are localized on the surface of topological media
with protected nodal lines [A. P. Schnyder and S. Ryu, Phys. Rev. B 84, 060504(R) (2011); T. T. Heikkil G. E. Volovik, JETP Lett. 93, 59 (2011)] and in the vortex core in systems with topologically protected Fermi points (Weyl points) [G. E. Volovik, JETP
Lett. 93, 66 (2011)]. Flat band has an extremely singular density of states, and we show that this property may give rise in particular
to surface superconductivity which could exist even at room temperature. 相似文献
16.
We investigate possible ordered phases in a magnetic field in quasi-one-dimensional conductors (Q1D). Long ago [I.E. Dzyaloshinskii, E.I. Kats, JETP 28 (1969) 178] we found that sufficiently strong external magnetic field leads to instability of the Fermi state with an arbitrarily weak repulsion between the particles. In the present communication we generalize this idea and provide more details to assign a physical meaning to such a state. We show that without umklapp processes the found instability corresponds to antiferromagnetic (spin density wave) order, whereas umklapp processes favor to Cooper pairing. 相似文献
17.
B. G. Zakharov 《JETP Letters》1996,64(11):781-787
A rigorous evaluation of the Landau-Pomeranchuk-Migdal effect for finite-size targets is performed within the path integral approach previously developed by the author [B. G. Zakharov, JETP Lett. 63, 952 (1996)]. The bremsstrahlung rate in QED is expressed through a solution of a two-dimensional Schrödinger equation with an imaginary potential. The boundary condition for this solution is formulated in terms of a product of the light-cone electron-photon wave function and the dipole cross section for scattering of an e + e ? pair off an atom. Numerical calculations are performed for homogeneous and structured targets. Our predictions for the homogeneous target agree well with the photon spectrum measured recently at SLAC with 25-GeV electrons. The spectra obtained for the structured, two-segment targets exhibit interference minima and maxima. 相似文献
18.
Self-consistent dynamics of an ensemble of screw dislocations during plastic deformation of crystals
A system of self-consistent field equations is formulated for an ensemble of continuously distributed screw dislocations.
Rapid relaxation of dislocation charges owing to the elastic interaction of the dislocations leads to a diffusive ensemble
dynamics. The conditions for development of an instability in the homogeneous state are determined. Self-organization of the
dislocations and their spatial ordering are described in the two-dimensional case.
Fiz. Tverd. Tela (St. Petersburg) 39, 1066–1071 (June 1997) 相似文献
19.
In recently reported experiments with uniaxially deformed germanium in a magnetic field [V. B. Timofeev and A. V. Chernenko,
JETP Lett. 61, 617 (1995)], it was found that applying a magnetic field of sufficiently high intensity results in the appearance of a new
line in the optical spectrum of the excitons. In the present paper a mechanism is proposed which can provide an explanation
for this experimentally observed spectral feature. The new spectral line may be attributed to the formation of strongly bound
biexcitonic molecules in the quantum state 3Πu.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 405–409 (25 March 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
20.
H. -W. Hammer 《The European Physical Journal A - Hadrons and Nuclei》2006,29(1):49-52
In the initial stage of the bottom-up picture of thermalization in heavy-ion collisions, the gluon distribution is highly
anisotropic which can give rise to plasma instability. This has not been taken into account in our original paper (Phys. Lett.
B 632, 257 (2006) hep-ph/0505164). It is shown that in the presence of instability there are scaling solutions, which depend on
one parameter, that match smoothly onto the late stage of bottom-up when thermalization takes place.-1 相似文献