Theory of the vortex matter transformations in high Tc superconductor YBCO

Flux line lattice in type II superconductors undergoes a transition into a "disordered" phase like vortex liquid or vortex glass, due to thermal fluctuations and random quenched disorder. We quantitatively describe the competition between the thermal fluctuations and the disorder using the Ginzburg -- Landau approach. The following T-H phase diagram of YBCO emerges. There are just two distinct thermodynamical phases, the homogeneous and the crystalline one, separated by a single first order transitions line. The line however makes a wiggle near the experimentally claimed critical point at 12T. The "critical point" is reinterpreted as a (noncritical) Kauzmann point in which the latent heat vanishes and the line is parallel to the T axis. The magnetization, the entropy and the specific heat discontinuities at melting compare well with experiments.Comment: 4 pages 3 figure

The IT performance evaluation in the construction industry

To date there has been limited published work in the construction management and engineering literature that has provided empirical evidence to demonstrate that IT can improve organizational performance. Without an explicit understanding about how IT can be effectively used to improve organizational performance, its justification will remain to be weak for managers. To ensure the continuous increase in IT based applications in the construction industry, sufficient evidence has to be provided for management in various professions of the construction industry to evaluate, allocate and utilize appropriate IT systems. In an attempt to explore the relationship between IT and productivity, an empirical investigation of 60 Professional Consulting Firms (PCF) from the Hong Kong construction industry was undertaken. A model for determining the organizational productivity of IT is proposed, and the methodology used to test the model is described. The findings are analyzed and a cross-profession comparison of the results indicated the differences in the use of IT. The research findings are discussed with similarities being drawn. The limitations of the research are then presented and discussed. The implications of the findings and conclusions then fully presented

Taming computational complexity: efficient and parallel SimRank optimizations on undirected graphs

SimRank has been considered as one of the promising link-based ranking algorithms to evaluate similarities of web documents in many modern search engines. In this paper, we investigate the optimization problem of SimRank similarity computation on undirected web graphs. We first present a novel algorithm to estimate the SimRank between vertices in O(n3+ Kn2) time, where n is the number of vertices, and K is the number of iterations. In comparison, the most efficient implementation of SimRank algorithm in [1] takes O(K n3 ) time in the worst case. To efficiently handle large-scale computations, we also propose a parallel implementation of the SimRank algorithm on multiple processors. The experimental evaluations on both synthetic and real-life data sets demonstrate the better computational time and parallel efficiency of our proposed techniques

The Precise Formula in a Sine Function Form of the norm of the Amplitude and the Necessary and Sufficient Phase Condition for Any Quantum Algorithm with Arbitrary Phase Rotations

In this paper we derived the precise formula in a sine function form of the norm of the amplitude in the desired state, and by means of he precise formula we presented the necessary and sufficient phase condition for any quantum algorithm with arbitrary phase rotations. We also showed that the phase condition: identical rotation angles, is a sufficient but not a necessary phase condition.Comment: 16 pages. Modified some English sentences and some proofs. Removed a table. Corrected the formula for kol on page 10. No figure

First-order coherence versus entanglement in a nano-mechanical cavity

The coherence and correlation properties of effective bosonic modes of a nano-mechanical cavity composed of an oscillating mirror and containing an optical lattice of regularly trapped atoms are studied. The system is modeled as a three-mode system, two orthogonal polariton modes representing the coupled optical lattice and the cavity mode, and one mechanical mode representing the oscillating mirror. We examine separately the cases of two-mode and three-mode interactions which are distinguished by a suitable tuning of the mechanical mode to the polariton mode frequencies. In the two-mode case, we find that the occurrence of entanglement between one of the polariton modes and the mechanical mode is highly sensitive to the presence of the first-order coherence between the modes. In particular, the creation of the first-order coherence among the modes is achieved at the expense of entanglement between the modes. In the three-mode case, we show that no entanglement is created between the independent polariton modes if both modes are coupled to the mechanical mode by the parametric interaction. There is no entanglement between the polaritons even if the oscillating mirror is damped by a squeezed vacuum field. The interaction creates the first-order coherence between the polaritons and the degree of coherence can, in principle, be as large as unity. This demonstrates that the oscillating mirror can establish the first-order coherence between two independent thermal modes. A further analysis shows that two independent thermal modes can be made entangled in the system only when one of the modes is coupled to the intermediate mode by a parametric interaction and the other is coupled by a linear-mixing interaction.Comment: Published versio

Nuclear quantum shape-phase transitions in odd-mass systems

Microscopic signatures of nuclear ground-state shape phase transitions in odd-mass Eu isotopes are explored starting from excitation spectra and collective wave functions obtained by diagonalization of a core-quasiparticle coupling Hamiltonian based on energy density functionals. As functions of the physical control parameter -- the number of nucleons -- theoretical low-energy spectra, two-neutron separation energies, charge isotope shifts, spectroscopic quadrupole moments, and $E2$ reduced transition matrix elements accurately reproduce available data, and exhibit more pronounced discontinuities at neutron number $N=90$, compared to the adjacent even-even Sm and Gd isotopes. The enhancement of the first-order quantum phase transition in odd-mass systems can be attributed to a shape polarization effect of the unpaired proton which, at the critical neutron number, starts predominantly coupling to Gd core nuclei that are characterized by larger quadrupole deformation and weaker proton pairing correlations compared to the corresponding Sm isotopes.Comment: 6 pages, 4 figure

Could 2S 0114+650 be a magnetar?

We investigate the spin evolution of the binary X-ray pulsar 2S 0114+650, which possesses the slowest known spin period of $\sim 2.7$ hours. We argue that, to interpret such long spin period, the magnetic field strength of this pulsar must be initially \gsim 10^{14} G, that is, it was born as a magnetar. Since the pulsar currently has a normal magnetic field $\sim 10^{12}$ G, our results present support for magnetic field decay predicted by the magnetar model.Comment: 7 pages, 1 figure, accepted for publication in ApJ

Microscopic Analysis of Order Parameters in Nuclear Quantum Phase Transitions

Microscopic signatures of nuclear ground-state shape phase transitions in Nd isotopes are studied using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. As a function of the physical control parameter -- the number of nucleons, energy gaps between the ground state and the excited vibrational states with zero angular momentum, isomer shifts, and monopole transition strengths, exhibit sharp discontinuities at neutron number N=90, characteristic of a first-order quantum phase transition.Comment: 5 pages, 4 figures, accepted for publication as a Rapid Communication in Physical Review