3,518 research outputs found
Quantum computing based on space states without charge transfer
An implementation of a quantum computer based on space states in double
quantum dots is discussed. There is no charge transfer in qubits during
calculation, therefore, uncontrollable entan-glement between them due to
long-range Coulomb interaction is suppressed. Other plausible sources of
decoherence caused by interaction with phonons and gates could be substantially
suppressed in the structure too. We also demonstrate how all necessary quantum
logic operations, initialization, writing, and read-out could be carried out in
the computer.Comment: 7 pages, 4 figures, RevTeX forma
Infrared radiation of Venusian clouds
The thermal infrared emission of Venus measured by Venera-9 and Venera-10 is analyzed. The emission of the night side corresponds to a brightness temperature of 244 K. The brightest temperature of the day side is 233-234 K. The extent of the upper layer of clouds, in which the thermal emission is formed, is 4-6 km. The altitude of the emitting layer above the surface of the planet (64-67 km) is determined from the brightness temperature and the existing models of the atmosphere of Venus. In some cases, correlation is noted between the inhomogeneity and the details of the ultraviolet image. The day side temperatures strangely coincide with the freezing point of sulfuric acid at a concentration of 66-77%
Thin films flowing down inverted substrates: Three dimensional flow
We study contact line induced instabilities for a thin film of fluid under
destabilizing gravitational force in three dimensional setting. In the previous
work (Phys. Fluids, {\bf 22}, 052105 (2010)), we considered two dimensional
flow, finding formation of surface waves whose properties within the
implemented long wave model depend on a single parameter,
, where is the capillary number and is
the inclination angle. In the present work we consider fully 3D setting and
discuss the influence of the additional dimension on stability properties of
the flow. In particular, we concentrate on the coupling between the surface
instability and the transverse (fingering) instabilities of the film front. We
furthermore consider these instabilities in the setting where fluid viscosity
varies in the transverse direction. It is found that the flow pattern strongly
depends on the inclination angle and the viscosity gradient
Interaction of Radiation and a Relativistic Electron in Motion in a Constant Magnetic Field
The work examines the effect of multiple photon emission on the quantum
mechanical state of an electron emitting synchrotron radiation and on the
intensity of that radiation. Calculations are done with the variant of
perturbation theory based on the use of extended coherent states. A general
formula is derived for the number of emitted photons, which allows for taking
into account their mutual interaction. A model problem is used to demonstrate
the absence of the infrared catastrophe in the modified perturbation theory.
Finally, the electron density matrix is calculated, and the analysis of this
matrix makes it possible to conclude that the degree of the elecron's spatial
localization increases with the passage of time if the electron is being
accelerated.Comment: 29 pages, no figure
Electrical discharges in the atmosphere of Venus
Data received from Venera 11 and 12 experiments involving the electrical activity of the atmosphere of Venus show that the electrical discharges occur in the cloud layer. Their energy is roughly the same as in terrestrial lightning, but with a pulse repetition frequency of the discharges which is much greater
Cutting Edge Geometry Effect on Plastic Deformation of Titanium Alloy
The paper presents experimental studies of ОТ4 titanium alloy machining with cutting edges of various geometry parameters. Experiments were performed at a low speed by the scheme of free cutting. Intensity of plastic shear strain was set for defining of cutting edge geometry effect on machining. Images of chip formed are shown. Estimation of strain magnitude was accomplished with digital image correlation method. Effect of rake angle and cutting edge angle has been studied. Depth of deformed layer and the area of the plastic strain is determine. Results showed that increasing the angle of the cutting edge inclination results in a change the mechanism of chip formation
Nucleon-nucleon interaction in the -matrix inverse scattering approach and few-nucleon systems
The nucleon-nucleon interaction is constructed by means of the -matrix
version of inverse scattering theory. Ambiguities of the interaction are
eliminated by postulating tridiagonal and quasi-tridiagonal forms of the
potential matrix in the oscillator basis in uncoupled and coupled waves,
respectively. The obtained interaction is very accurate in reproducing the
scattering data and deuteron properties. The interaction is used in the no-core
shell model calculations of H and He nuclei. The resulting binding
energies of H and He are very close to experimental values.Comment: Text is revised, new figures and references adde
On the Weyl - Eddington - Einstein affine gravity in the context of modern cosmology
We propose new models of an `affine' theory of gravity in -dimensional
space-times with symmetric connections. They are based on ideas of Weyl,
Eddington and Einstein and, in particular, on Einstein's proposal to specify
the space - time geometry by use of the Hamilton principle. More specifically,
the connection coefficients are derived by varying a `geometric' Lagrangian
that is supposed to be an arbitrary function of the generalized (non-symmetric)
Ricci curvature tensor (and, possibly, of other fundamental tensors) expressed
in terms of the connection coefficients regarded as independent variables. In
addition to the standard Einstein gravity, such a theory predicts dark energy
(the cosmological constant, in the first approximation), a neutral massive (or,
tachyonic) vector field, and massive (or, tachyonic) scalar fields. These
fields couple only to gravity and may generate dark matter and/or inflation.
The masses (real or imaginary) have geometric origin and one cannot avoid their
appearance in any concrete model. Further details of the theory - such as the
nature of the vector and scalar fields that can describe massive particles,
tachyons, or even `phantoms' - depend on the concrete choice of the geometric
Lagrangian. In `natural' geometric theories, which are discussed here, dark
energy is also unavoidable. Main parameters - mass, cosmological constant,
possible dimensionless constants - cannot be predicted, but, in the framework
of modern `multiverse' ideology, this is rather a virtue than a drawback of the
theory. To better understand possible applications of the theory we discuss
some further extensions of the affine models and analyze in more detail
approximate (`physical') Lagrangians that can be applied to cosmology of the
early Universe.Comment: 15 pages; a few misprints corrected, one footnote removed and two
added, the formulae and results unchanged but the text somewhat edited, esp.
in Sections 4,5; the reference to the RFBR grant corrected
- …