Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions

We consider a system of nonlinear spinor and a Bianchi type I gravitational fields in presence of viscous fluid. The nonlinear term in the spinor field Lagrangian is chosen to be $\lambda F$, with $\lambda$ being a self-coupling constant and $F$ being a function of the invariants $I$ an $J$ constructed from bilinear spinor forms $S$ and $P$. Self-consistent solutions to the spinor and BI gravitational field equations are obtained in terms of $\tau$, where $\tau$ is the volume scale of BI universe. System of equations for $\tau$ and \ve, where \ve is the energy of the viscous fluid, is deduced. This system is solved numerically for some special cases.Comment: 15 pages, 4 figure

Nonlinear σ\sigma model for disordered superconductors

We suggest a novel nonlinear $\sigma$-model for the description of disordered superconductors. The main distinction from existing models lies in the fact that the saddle point equation is solved non-perturbatively in the superconducting pairing field. It allows one to use the model both in the vicinity of the metal-superconductor transition and well below its critical temperature with full account for the self-consistency conditions. We show that the model reproduces a set of known results in different limiting cases, and apply it for a self-consistent description of the proximity effect at the superconductor-metal interface.Comment: Revised version, 8 pages, 1 fig., revtex; final version, as published, contains a few corrections in the summar

Thermostatistics of deformed bosons and fermions

Based on the q-deformed oscillator algebra, we study the behavior of the mean occupation number and its analogies with intermediate statistics and we obtain an expression in terms of an infinite continued fraction, thus clarifying successive approximations. In this framework, we study the thermostatistics of q-deformed bosons and fermions and show that thermodynamics can be built on the formalism of q-calculus. The entire structure of thermodynamics is preserved if ordinary derivatives are replaced by the use of an appropriate Jackson derivative and q-integral. Moreover, we derive the most important thermodynamic functions and we study the q-boson and q-fermion ideal gas in the thermodynamic limit.Comment: 14 pages, 2 figure

Quantum computing implementations with neutral particles

We review quantum information processing with cold neutral particles, that is, atoms or polar molecules. First, we analyze the best suited degrees of freedom of these particles for storing quantum information, and then we discuss both single- and two-qubit gate implementations. We focus our discussion mainly on collisional quantum gates, which are best suited for atom-chip-like devices, as well as on gate proposals conceived for optical lattices. Additionally, we analyze schemes both for cold atoms confined in optical cavities and hybrid approaches to entanglement generation, and we show how optimal control theory might be a powerful tool to enhance the speed up of the gate operations as well as to achieve high fidelities required for fault tolerant quantum computation.Comment: 19 pages, 12 figures; From the issue entitled "Special Issue on Neutral Particles

Coherent X-ray imaging and microscopy opportunities with a diffraction-limited Energy Recovery Linac (ERL) synchrotron source

A proposed Energy Recovery Linac (ERL) x-ray source at Cornell would be a 5-7 GeV synchrotron facility based on the energy-recovery principle with a superconducting linac. Because of its ultra-small round electron source and ultra-short but flexible bunch structure, the ERL has the potential to produce subpicosecond ultra-bright diffraction-limited hard x-ray beams that are superior to those from existing storage rings, and would enable new scientific experiments that are difficult or impossible to perform today. In this paper, we discuss the transverse coherence properties of the ERL source and show how these properties could benefit various x-ray microscopy applications that require a highly coherent and intense x-ray beam. These applications include full coherent illumination of wide-aperture zone-plate optics for scanning x-ray microscopy, diffraction-limited coherent phase-contrast microscopy and tomography, fully coherent hard x-ray diffraction microscopy, and large-coherence-area x-ray holography techniques

An Approach to Semantic Information Retrieval based on Natural Language Query Understanding

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Imaging field-dependent structure in charge-density waves by X-ray diffraction topography

We have imaged field-dependent CDW structure in NbSe3 single crystals by X-ray diffraction topography. Just above ET, the CDW shears along longitudinal steps in crystal thickness associated with small-angle grain boundaries, and at high fields transverse correlations recover. These results demonstrate X-ray topography as an effective probe of CDW structure, and together with earlier transport measurements establish that extrinsic sources dominate the most obvious manifestations of plasticity in this CDW conductor