МОДЕЛИРОВАНИЕ ЭЛЕКТ РОННО-ОПТИЧЕСКИХ СИС ТЕМ С ОСЕВОЙ СИММЕТРИЕЙ П РИ ПОМОЩИ СЕТИ СОПРОТИВЛЕНИЙ

The paper explains the theory of modelling electrostatic fields by a resistance network. The conditions, which the resistance network must satisfy, are derived and the question of modelling electrodes of different shapes is solved. The finished network and the results obtained on it when modelling a jet for a linear h-f accelerator of electrons are described. Particular attention is paid to the influence of a space charge, the modelling of which is an advantage of this method.

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1- , 1964., , .

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More inequalities for critical exponents

A variety of rigorous inequalities for critical exponents is proved. Most notable is the low-temperature Josephson inequalitydv +2 2–. Others are 1 1 +v, 1 1 , 1,d 1 + 1/ (for d),dv, ₃ + (for d), ₄ , and _{2m 2m+2} (form 2). The hypotheses vary; all inequalities are true for the spin-1/2 Ising model with nearest-neighbor ferromagnetic pair interactions.NSF Predoctoral Fellow (1976–1979). Research supported in part by NSF Grant PHY 78-23952.     

Double quantum transitions in paramagnetic resonance

The theory of double quantum transitions of the M=±2 type, with regard to inhomogeneously broadened spin systems is studied in this paper with the approximation ²T₂T₃ 1. We suppose that the inhomogeneous broadening is formed by an inhomogeneous crystal field. The obtained results describe the magnitude of absorption as a function of the h.f. power and also describe the shape of the absorption curve. It is demonstrated that in inhomogeneously broadened spin systems the absorption curve of double quantum transitions has the form of the difference of two different Lorentz's curves and that at the saturation ( ²T₂T₁ 1) the absorption increases with the cube of the h.f. field intensity. The shape of the curves is expressed by means of phenomenological relaxation constants of the system.

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M=±2 ²T₂T₃ 1. , - . . , ( ²T₂T₁ 1) . .

     

Anti-photon

It should be apparent from the title of this article that the author does not like the use of the word photon, which dates from 1926. In his view, there is no such thing as a photon. Only a comedy of errors and historical accidents led to its popularity among physicists and optical scientists. I admit that the word is short and convenient. Its use is also habit forming. Similarly, one might find it convenient to speak of the aether or vacuum to stand for empty space, even if no such thing existed. There are very good substitute words for photon, (e.g., radiation or light), and for photonics (e.g., optics or quantum optics). Similar objections are possible to use of the word phonon, which dates from 1932. Objects like electrons, neutrinos of finite rest mass, or helium atoms can, under suitable conditions, be considered to be particles, since their theories then have viable non-relativistic and non-quantum limits. This paper outlines the main features of the quantum theory of radiation and indicates how they can be used to treat problems in quantum optics.It is a pleasure to join in the 60th birthday celebration of the Director, Herbert Walther, of the Max-Planck-Institute for Quantum Optics at Garching, and wish him much happiness and many more years of his very great scientific creativity.     

A generalized Kubo-Toyabe formula for muon spin relaxation in crystals with uniaxial symmetry

The Kubo-Toyabe semiclassical formula, describing the time development of the polarization of a particle in zero external field at a lattice site with cubic local environment, is generalized for uniaxial site symmetry. The relaxation function and, in particular, its first moments and long time asymptotics obtained in a closed form depend on the angle between polarization and the crystalc-axis and are shown to vary sensitively with the asymmetry of the field distribution at the particular muon site. Besides the exact uniaxial variant of the Kubo-Toyabe relaxation function, an approximate simple interpolation formula is also derived, which is correct for both short times and in its long time asymptotics. The two parameters (, ₁) in the uniaxial formulae can be determined by using the observed values of the second momentM ₂ for two different crystal orientations.     

ИЗЛУЧЕНИЕ ЭЛЕКТРИЧЕ СКОГО ДИПОЛЯ НАД ГРАН ИЦЕЙ ДВУХ СРЕД

, , . , - - . - . -, - , . , - ; , , .     

Quantum non-demolition measurements in optics: a review and some recent experimental results

We review the schemes which have been implemented, in order to achieve quantum non-demolition (QND) measurements in the optical domain. The simplest schemes can be obtained using the optical Kerr effect, which yields a crossed-phase modulation coupling between two light beams. Other schemes use either independently generated squeezed light, or coupled-mode parametric amplifiers. These various schemes can be characterized using three criteria, which describe, respectively, the quality of the quantum measurement, the non-destruction of the signal, and the conditional variance of the output signal beam, given the output meter beam (quantum-state preparation criterion). We show that quantitative limits can be defined with respect to these criteria, delimiting classical and quantum domains of operation. Then we present in more detail a new experimental implementation of QND measurements, using three-level atoms inside a doubly-resonant optical cavity.     

Новый метод измерени я магнитокалорическ ого эффекта у ферромагни тных полупроводнико в

, .     

КРУЧЕНИЕ ПРИЗМАТИЧЕ СКИХ СТЕРЖНЕЙ ШВЕЛЛЕ РНОГО ПОПЕРЕЧНОГО СЕЧЕНИЯ

- [3], [4], U(x, y) . - U(x, y) -, . B § 10 - . , - , - D, . - .     

Ar ion laser assisted chemical etching of via holes in tungsten sheets in air

Ar ion laser assisted chemical etching of 150 m thick annealed tungsten sheets in air is reported. The material removal mechanism involves local heating by the laser to temperatures in the range of 1000–1500 °C that causes rapid oxidation of the W to WO₃ which volatilizes readily. Holes with straight walls and slightly enlarged entrances near the surface were drilled with etch rates as high as 11.5 m/s at 13.8 W, and a minimum hole diameter of 21 m at 8.1 W. The diameters of the holes and the etch rates were measured and found to increase as a function of the laser power. It was found that by increasing the laser power above 11–12 W, no change was observed in the hole diameters which remained constant at about 31 m, whereas the etch rates continued to increase even faster than at low powers. Distinct adjacent holes of 25 m diameter could be drilled with their centers separated by as little as 60 m. This is therefore also the etching resolution in the present study.     

ДАЛЬНЕЙШИЕ ИССЛЕДОВ АНИЯ ФИЛЬТРА ДВОЙНОГ О ЛУЧЕПРЕЛОМЛЕНИЯ

, 4, (1954), 53. . .     

Study of the Anglular Structure of Emission from the Radio Galaxy 3C295 in the Decameter Wavelength Range

We present the results of observations of the angular structure of the radio source 3C295 at decameter waves using the URAN-1 and URAN-2 interferometers. It is shown that the radio image of 3C295 at these frequencies differs drastically from the structure of this object observed at higher frequencies. The simplest model of the structure of this radio galaxy, comprising one component with a Gaussian brightness distribution of angular size (7.4 ± 0.4)× (8.7± 0.4) at 25 MHz and (9.1± 0.5)× (10.6 ± 0.5) at 20 MHz, is determined. A decrease in the spectral density of the emission with decreasing frequency, observed below 50 MHz, is explained.     

Охлаждение накалива емой проволоки в подз вуковом потоке

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On the probability of double beta decay

Double beta decay is discussed in relation to parity non-conservation. Two possible ways of neutrino-less double beta decay (allowed and forbidden) are investigated and the half-life of decay is calculated. For allowed transitions we obtain for Ca⁴⁸ an estimatedT1/2=2×10¹⁹ years. The negative results of the experiments by Lukjanov et al., who give the valueT1/2=0.7×10¹⁹ years for the lower limit of the half-life of double beta decay of Ca⁴⁸, cannot therefore be regarded as a definitive solution of the question, whether the neutrino is a Dirac or Majorana particle. Further study of double beta decay, aimed at finding higher values of the lower limit of half-life, are of considerable importance for theory.

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- . - ( ) . ⁴⁸ T1/2210¹⁹ . - . [1] ( - ⁴⁸ T1/2 0,710¹⁹ ), , . - .

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In conclusion the author thanks Prof. I. S. apiro for suggesting this work and help in elaborating it.     

Amplitude and energy coefficients of reflected and refracted light

The tensor of reflected and refracted light was first introduced into the principal axes and then the latter were transformed into thep ands direction of the electric field strength. The amplitude coefficient of thep-components of refracted light has different forms depending on which complex unit vector is unit with respect to the square or the absolute value. The energy coefficient has the same value in both cases.

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, p s . p- , . .

     

Steady temperature in a composite rectangle

The present paper solves the steady temperature problem in a rectangle consisting of any number of homogeneous isotropic parts. As usual with such questions, the results are very complicated and cannot be found in the literature.

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, . , - .

     

ВЛИЯНИЕ ДАВЛЕНИЯ НА Ч УВСТВИТЕЛЬНОСТЬ ФОТОГРАФИЧЕСКОЙ ЭМУ ЛЬСИИ

- gr, -, . - , - . , , .     

The influence of elastic deformation on the magnetostriction constant of nickel and iron-nickel alloys

The dependence of the magnetostriction constant of different materials in the form of a wire on the elastic elongation was measured. With pure nickel the magnetostriction constant is independent of the elastic deformation. All three alloys of iron and nickel and the triple alloy Fe-Ni-Co exhibit a linear dependence on the deformation, which differs for different crystallographic texture. In two iron-nickel alloys the dependence of the magnetostriction constants of the single crystal on the elastic deformation was calculated from measurements on polycrystals having different crystallographic textures. In the triple alloy Fe-Ni -Co a considerable linear decrease in the volume magnetostriction with the elastic elongation was also found. The observed changes can be explained by assuming the influence of the lattice deformation on the spinorbital interaction in alloys.

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. . - Fe-Ni-Co , . - . , Fe-Ni-Co . - .

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A preliminary report on some of the results of this paper was given at the conference on magnetism in Kyoto (Japan) in September 1961.

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In conclusion the authors thank Z. Frait C. Sc. and S. Libovický for remarks, J. Míová for help in the measurements, members of the chemical department of our institute for annealing and analyzing the samples and members of the Metal Research Institute in Panenské Beany for their exceptional helpfulness in preparing the wires.     

Luminescence in the systems ZnS-CuAlS2 and ZnS-AgAlS2

ZnS-CuAlS₂ and ZnS-AgAlS₂ phosphors (denoted by CuAl and AgAl) have blue, green, and red emission bands. The excitation spectra of these bands have characteristic peaks. The effects of activator concentration on the parameters of the emission and excitation spectra are examined.     

New two-color dimer models with critical ground states

We define two new models on the square lattice in which each allowed configuration is a superposition of a covering by white dimers and one by black dimers. Each model maps to a solid-on-solid (SOS) model in which the height field is two dimensional. Measuring the stiffness of the SOS fluctuations in the rough phase provides critical exponents of the dimer models. Using this height representation, we have performed Monte Carlo simulations. They confirm that each dimer model has critical correlations and belongs to a new universality class. In the dimer-loop model (which maps to a loop model) one height component is smooth, but has unusual correlated fluctuations; the other height component is rough. In the noncrossing-dimer model the heights are rough, having two different elastic constants; an unusual form of its elastic theory implies anisotropic critical correlations.