Intermediate quantum maps for quantum computation

We study quantum maps displaying spectral statistics intermediate between Poisson and Wigner-Dyson. It is shown that they can be simulated on a quantum computer with a small number of gates, and efficiently yield information about fidelity decay or spectral statistics. We study their matrix elements and entanglement production, and show that they converge with time to distributions which differ from random matrix predictions. A randomized version of these maps can be implemented even more economically, and yields pseudorandom operators with original properties, enabling for example to produce fractal random vectors. These algorithms are within reach of present-day quantum computers.Comment: 4 pages, 4 figures, research done at http://www.quantware.ups-tlse.fr

On the Impossibility to Extend Triples of Mutually Unbiased Product Bases in Dimension Six

An analytic proof is given which shows that it is impossible to extend any triple of mutually unbiased (MU) product bases in dimension six by a single MU vector. Furthermore, the 16 states obtained by removing two orthogonal states from any MU product triple cannot figure in a (hypothetical) complete set of seven MU bases. These results follow from exploiting the structure of MU product bases in a novel fashion, and they are among the strongest ones obtained for MU bases in dimension six without recourse to computer algebra.Comment: 12 pages, identical to published versio

Are the INTEGRAL Intermediate Polars Different?

One of the biggest surprises of the INTEGRAL mission was the detection of large numbers of magnetic cataclysmic variables – in particular the intermediate polar (IP) subclass. Not only have many previously known systems been detected, but many new ones have also been found and subsequently classified from optical follow-up observations, increasing the sample of IPs by ! 15%. We have recently been using a particle hydrodynamic code to investigate the accretion flows of IPs and determine the equilibrium spin-rates and accretion flow patterns across a wide range of orbital periods, mass ratios and magnetic field strengths. We use the results of these accretion flow simulations to examine whether the INTEGRAL IPs differ from the overall population and conclude that they do not. Most IPs are likely to be INTEGRAL sources, given sufficient exposure. Currently however, none of the 'EX Hya-like' IPs, with large spin-to-orbital period ratios and short orbital periods, are detected by INTEGRAL. If this continues to be the case once the whole sky has a comparable INTEGRAL exposure, it may indicate that the ring-like mode of accretion which we demonstrate occurs in these systems is responsible for their different appearance

Spectral fluctuations and 1/f noise in the order-chaos transition regime

Level fluctuations in quantum system have been used to characterize quantum chaos using random matrix models. Recently time series methods were used to relate level fluctuations to the classical dynamics in the regular and chaotic limit. In this we show that the spectrum of the system undergoing order to chaos transition displays a characteristic $f^{-\gamma}$ noise and $\gamma$ is correlated with the classical chaos in the system. We demonstrate this using a smooth potential and a time-dependent system modeled by Gaussian and circular ensembles respectively of random matrix theory. We show the effect of short periodic orbits on these fluctuation measures.Comment: 4 pages, 5 figures. Modified version. To appear in Phys. Rev. Let

Modified Chaplygin Traversable Wormholes

The modified Chaplygin gas (MCG) is a strong candidate for the unified model of dark matter and dark energy. The equation of state of this modified model is valid from the radiation era to the $\Lambda$CDM model. In early epoch (when $\rho$ was large), dark matter had the dominant role while at later stages (when $\rho$ is small), the MCG model behaves as dark energy. In this work, we have found exact solution of static spherically symmetric Einstein equations describing a wormhole for an inhomogeneous distribution of modified Chaplygin gas. For existence of wormhole solution, there are some restrictions relating the parameters in the equation of state for MCG and the throat radius of the wormhole. Physical properties and characteristics of these modified Chaplygin wormholes are analyzed in details.Comment: 9 pages, 1 figur

Random matrix analysis of complex networks

We study complex networks under random matrix theory (RMT) framework. Using nearest-neighbor and next-nearest-neighbor spacing distributions we analyze the eigenvalues of adjacency matrix of various model networks, namely, random, scale-free and small-world networks. These distributions follow Gaussian orthogonal ensemble statistic of RMT. To probe long-range correlations in the eigenvalues we study spectral rigidity via $\Delta_3$ statistic of RMT as well. It follows RMT prediction of linear behavior in semi-logarithmic scale with slope being $\sim 1/\pi^2$. Random and scale-free networks follow RMT prediction for very large scale. Small-world network follows it for sufficiently large scale, but much less than the random and scale-free networks.Comment: accepted in Phys. Rev. E (replaced with the final version

Improvement in Grinding and Classification Circuit by the use of Hydrocone at Rakha Concentrator

With increase in demand of metals, depleting ore reserves, falling ore grades and manyfold increase in operational cost, many of the mineral industries are now facing the prospect of closing their operations. However, efforts are being made at every place to reduce the cost of production through innovations and improvement tech-nology

Gravitational Constant and Torsion

Riemann-Cartan space time $U_{4}$ is considered here. It has been shown that when we link topological Nieh-Yan density with the gravitational constant then we get Einstein-Hilbert Lagrangian as a consequence.Comment: 8 page