The Power Flow Angle of Acoustic Waves in Thin Piezoelectric Plates

The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A0) and quasi-symmetric (S0) Lamb waves as well as quasi-shear-horizontal (SH0) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S0 and SH0 wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers

First results of systematic studies done with different types of Silicon Photomultipliers

The presented results are obtained during the first steps taken in order to develop a setup and measurement procedures which allow to compare properties of diverse kinds of silicon photomultipliers. The response to low-intensity light was studied for silicon photomultipliers produced by CPTA (Russia), Hamamatsu (Japan), ITC-irst (Italy) and SensL (Ireland).Comment: 3 pages, 3 figures, proceedings of the Internationa Linear Collider Workshop LCWS2007, Hamburg, German

Identification of the byproducts of the oxygen evolution reaction on rutile-type oxides under dynamic conditions

Peer reviewedPostprin

The characteristics of fundamental shear-horizontal acoustic waves in structure “nanocomposite polymeric film-vacuum gap-piezoelectric plate”

AbstractRecently it has been shown that SH0 wave in structure “piezoelectric plate-nanocomposite polymeric film with Fe nanoparticles” is characterized by the low TCD (∼15 ppm/C) and high value of K2 (∼32%). However in the case of the acoustical contact of polymeric material with the plate such structure possesses significant attenuation of the acoustic wave (∼1dB/λ). In order to avoid this effect it was suggested to use the structure containing the gap between the polymeric film and plate. As the result of theoretical analysis the dependencies of SH0 wave velocity versus relative thickness of vacuum gap were obtained. It has been found that there exist such values of gap and dielectric permittivity of the nanocomposite material when the value of TCD of SH0 wave significantly decreases. At that the attenuation connected with the dissipation factor is practically absent

Long-distance entanglement and quantum teleportation in XX spin chains

Isotropic XX models of one-dimensional spin-1/2 chains are investigated with the aim to elucidate the formal structure and the physical properties that allow these systems to act as channels for long-distance, high-fidelity quantum teleportation. We introduce two types of models: I) open, dimerized XX chains, and II) open XX chains with small end bonds. For both models we obtain the exact expressions for the end-to-end correlations and the scaling of the energy gap with the length of the chain. We determine the end-to-end concurrence and show that model I) supports true long-distance entanglement at zero temperature, while model II) supports {\it ``quasi long-distance''} entanglement that slowly falls off with the size of the chain. Due to the different scalings of the gaps, respectively exponential for model I) and algebraic in model II), we demonstrate that the latter allows for efficient qubit teleportation with high fidelity in sufficiently long chains even at moderately low temperatures.Comment: 9 pages, 6 figure

Multiple Quantum NMR Dynamics in Dipolar Ordered Spin Systems

We investigate analytically and numerically the Multiple Quantum (MQ) NMR dynamics in systems of nuclear spins 1/2 coupled by the dipole-dipole interactions in the case of the dipolar ordered initial state. We suggest two different methods of MQ NMR. One of them is based on the measurement of the dipolar temperature in the quasi-equilibrium state which establishes after the time of order T2 after the MQ NMR experiment. The other method uses an additional resonance 45^0 -pulse after the preparation period of the standard MQ NMR experiment in solids. Many-spin clusters and correlations are created faster in such experiments than in the usual MQ NMR experiments and can be used for the investigation of many-spin dynamics of nuclear spins in solids.Comment: 11 pages, 3 figures. accepted for publication in Physical Review

Magneto-optical Feshbach resonance: Controlling cold collision with quantum interference

We propose a method of controlling two-atom interaction using both magnetic and laser fields. We analyse the role of quantum interference between magnetic and optical Feshbach resonances in controlling cold collision. In particular, we demonstrate that this method allows us to suppress inelastic and enhance elastic scattering cross sections. Quantum interference is shown to modify significantly the threshold behaviour and resonant interaction of ultracold atoms. Furthermore, we show that it is possible to manipulate not only the spherically symmetric s-wave interaction but also the anisotropic higher partial-wave interactions which are particularly important for high temperature superfluid or superconducting phases of matter.Comment: 7 pages 3 figures, some minor errors are corrected, Accepted in J. Phys.

One-dimensional structures behind twisted and untwisted superYang-Mills theory

We give a one-dimensional interpretation of the four-dimensional twisted N=1 superYang-Mills theory on a Kaehler manifold by performing an appropriate dimensional reduction. We prove the existence of a 6-generator superalgebra, which does not possess any invariant Lagrangian but contains two different subalgebras that determine the twisted and untwisted formulations of the N=1 superYang-Mills theory.Comment: 12 pages. Final version to appear in Lett. Math. Phys. with improved notation and misprints correcte