Continuous variable entanglement of phase locked light beams

We explore in detail the possibility of intracavity generation of continuous-variable (CV) entangled states of light beams under mode phase-locked conditions. We show that such quantum states can be generated in self-phase locked nondegenerate optical parametric oscillator (NOPO) based on a type-II phase-matched down-conversion combined with linear mixer of two orthogonally polarized modes of the subharmonics in a cavity. A quantum theory of this device, recently realized in the experiment, is developed for both sub-threshold and above-threshold operational regimes. We show that the system providing high level phase coherence between two generated modes, unlike to the ordinary NOPO, also exhibits different types of quantum correlations between photon numbers and phases of these modes. We quantify the CV entanglement as two-mode squeezing and show that the maximal degree of the integral two-mode squeezing(that is 50% relative to the level of vacuum fluctuations) is achieved at the pump field intensity close to the generation threshold of self-phase locked NOPO, provided that the constant of linear coupling between the two polarizations is much less than the mode detunings. The peculiarities of CV entanglement for the case of unitary, non-dissipative dynamics of the system under consideration is also cleared up

Giant dispersion of critical currents in superconductor with fractal clusters of a normal phase

The influence of fractal clusters of a normal phase on the dynamics of a magnetic flux trapped in a percolative superconductor is considered. The critical current distribution and the current-voltage characteristics of fractal superconducting structures in the resistive state are obtained for an arbitrary fractal dimension of the cluster boundaries. The range of fractal dimensions, where the dispersion of critical currents becomes infinite, is found. It is revealed that the fractality of clusters depresses of the electric field caused by the magnetic flux motion thus increasing the critical current value. It is expected that the maximum current-carrying capability of a superconductor can be achieved in the region of giant dispersion of critical currents.Comment: 7 pages with 3 figure

The effect of electronic entropy on temperature peculiarities of the frequency characteristics of two interacting anharmonic vibrational modes in β−\beta-Zr

A 2D temperature-dependent effective potential is calculated for the interacting longitudinal and transverse $L-$phonons of $\beta$ zirconium in the frozen-phonon model. The effective potentials obtained for different temperatures are used for the numerical solution of a set of stochastic differential equations with a thermostat of the white-noise type. Analysis of the spectral density of transverse vibrations allows one to determine the temperature at which $\beta$-Zr becomes unstable with respect to the longitudinal $L-$vibrations. The obtained temperature value practically coincides with the experimental temperature of the $\beta \to \alpha$ structural transition in zirconium. The role of electronic entropy in the $\beta-$Zr stability is discussed.Comment: 9 pages, 10 figures (submitted in Phys.Rev.

Conductivity and Atomic Structure of Isolated Multiwalled Carbon Nanotubes

We report associated high resolution transmission electron microscopy (HRTEM) and transport measurements on a series of isolated multiwalled carbon nanotubes. HRTEM observations, by revealing relevant structural features of the tubes, shed some light on the variety of observed transport behaviors, from semiconducting to quasi-metallic type. Non Ohmic behavior is observed for certain samples which exhibit "bamboo like" structural defects. The resistance of the most conducting sample, measured down to 20 mK, exhibits a pronounced maximum at 0.6 K and strong positive magnetoresistance.Comment: 4 pages, 4 eps figure

Limiting distributions of continuous-time random walks with superheavy-tailed waiting times

We study the long-time behavior of the scaled walker (particle) position associated with decoupled continuous-time random walk which is characterized by superheavy-tailed distribution of waiting times and asymmetric heavy-tailed distribution of jump lengths. Both the scaling function and the corresponding limiting probability density are determined for all admissible values of tail indexes describing the jump distribution. To analytically investigate the limiting density function, we derive a number of different representations of this function and, by this way, establish its main properties. We also develop an efficient numerical method for computing the limiting probability density and compare our analytical and numerical results.Comment: 35 pages, 4 figure

Adaptive observers for nonlinearly parameterized systems subjected to parametric constraints

We consider the problem of adaptive observer design in the settings when the system is allowed to be nonlinear in the parameters, and furthermore they are to satisfy additional feasibility constraints. A solution to the problem is proposed that is based on the idea of universal observers and non-uniform small-gain theorem. The procedure is illustrated with an example.Comment: 19th IFAC World Congress on Automatic Control, 10869-10874, South Africa, Cape Town, 24th-29th August, 201

Toward precision mass measurements of neutron-rich nuclei relevant to rr-process nucleosynthesis

The open question of where, when, and how the heavy elements beyond iron enrich our Universe has triggered a new era in nuclear physics studies.\ Of all the relevant nuclear physics inputs, the mass of very neutron-rich nuclides is a key quantity for revealing the origin of heavy elements beyond iron.\ Although the precise determination of this property is a great challenge, enormous progress has been made in recent decades, and it has contributed significantly to both nuclear structure and astrophysical nucleosynthesis studies.\ In this review, we first survey our present knowledge of the nuclear mass surface, emphasizing the importance of nuclear mass precision in $r$-process calculations.\ We then discuss recent progress in various methods of nuclear mass measurement with a few selected examples.\ For each method, we focus on recent breakthroughs and discuss possible ways of improving the weighing of $r$-process nuclides.Comment: 10 figures, review articles in Frontiers of Physic