13,668 research outputs found
Shear and Vorticity in a Combined Einstein-Cartan-Brans-Dicke Inflationary Lambda-Universe
A combined BCDE (Brans-Dicke and Einstein-Cartan) theory with lambda-term is
developed through Raychaudhuri's equation, for inflationary scenario. It
involves a variable cosmological constant, which decreases with time, jointly
with energy density, cosmic pressure, shear, vorticity, and Hubble's parameter,
while the scale factor, total spin and scalar field increase exponentially. The
post-inflationary fluid resembles a perfect one, though total spin grows, but
the angular speed does not (Berman, 2007d). Keywords: Cosmology; Einstein;
Brans-Dicke; Cosmological term; Shear; Spin; Vorticity; Inflation;
Einstein-Cartan; Torsion. PACS: 04.20.-q ; 98.80.-k ; 98.80.Bp ; 98.80.JkComment: 8 pages including front one. Published versio
Ground resonance analysis using a substructure modeling approach
A convenient and versatile procedure for modeling and analyzing ground resonance phenomena is described and illustrated. A computer program is used which dynamically couples differential equations with nonlinear and time dependent coefficients. Each set of differential equations may represent a component such as a rotor, fuselage, landing gear, or a failed damper. Arbitrary combinations of such components may be formulated into a model of a system. When the coupled equations are formed, a procedure is executed which uses a Floquet analysis to determine the stability of the system. Illustrations of the use of the procedures along with the numerical examples are presented
Radiative Tail in Decay and Some Comments on Universality
The result of lowest-order perturbation theory calculations of the photon and
positron spectra in radiative pion(e2) decay are generalized to all orders of
perturbation theory using the structure-function method. An additional source
of radiative corrections to the ratio of the positron and muon channels of pion
decay, due to emission of virtual and real photons and pairs, is considered. It
depends on details of the detection of the final particles and is large enough
to be taken into account in theoretical estimates with a level of accuracy of
0.1%.Comment: 5 pages, LaTeX, some misprints are corrected, submitted to Pisma Zh.
Eksp. Teor. Fi
Spectrum of light scattering from an extended atomic wave packet
The spectrum of the light scattered from an extended atomic wave packet is
calculated. For a wave packet consisting of two spatially separated peaks
moving on parallel trajectories, the spectrum contains Ramsey-like fringes that
are sensitive to the phase difference between the two components of the wave
packet. Using this technique, one can establish the mutual coherence of the two
components of the wave packet without recombining them.Comment: 4 page
Microscopic Theory of Spontaneous Decay in a Dielectric
The local field correction to the spontanous dacay rate of an impurity source
atom imbedded in a disordered dielectric is calculated to second order in the
dielectric density. The result is found to differ from predictions associated
with both "virtual" and "real" cavity models of this decay process. However, if
the contributions from two dielectric atoms at the same position are included,
the virtual cavity result is reproduced.Comment: 12 Page
Solid-State Quantum Computer Based on Scanning Tunneling Microscopy
We propose a solid-state nuclear spin quantum computer based on application
of scanning tunneling microscopy (STM) and well-developed silicon technology.
It requires the measurement of tunneling current modulation caused by the
Larmor precession of a single electron spin.
Our envisioned STM quantum computer would operate at the high magnetic field
(T) and at low temperature K.Comment: 3pages RevTex including 2 figure
Electrical 2-omega-cm 0.046-cm-thick silicon solar cells as a function of intensity and temperature
Electrical characteristics of Mariner '71 type silicon solar cells are presented in graphical and tabular format as a function of intensity and temperature
Simplifying and adapting antiretroviral treatment in resource-poor settings: a necessary step to scaling-up.
Dynamical Stability and Quantum Chaos of Ions in a Linear Trap
The realization of a paradigm chaotic system, namely the harmonically driven
oscillator, in the quantum domain using cold trapped ions driven by lasers is
theoretically investigated. The simplest characteristics of regular and chaotic
dynamics are calculated. The possibilities of experimental realization are
discussed.Comment: 24 pages, 17 figures, submitted to Phys. Rev
Simulations of Quantum Logic Operations in Quantum Computer with Large Number of Qubits
We report the first simulations of the dynamics of quantum logic operations
with a large number of qubits (up to 1000). A nuclear spin chain in which
selective excitations of spins is provided by the gradient of the external
magnetic field is considered. The spins interact with their nearest neighbors.
We simulate the quantum control-not (CN) gate implementation for remote qubits
which provides the long-distance entanglement. Our approach can be applied to
any implementation of quantum logic gates involving a large number of qubits.Comment: 13 pages, 15 figure
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