Von Neumann entropy and localization-delocalization transition of electron states in quantum small-world networks

The von Neumann entropy for an electron in periodic, disorder and quasiperiodic quantum small-world networks(QSWNs) are studied numerically. For the disorder QSWNs, the derivative of the spectrum averaged von Neumann entropy is maximal at a certain density of shortcut links p*, which can be as a signature of the localization delocalization transition of electron states. The transition point p* is agreement with that obtained by the level statistics method. For the quasiperiodic QSWNs, it is found that there are two regions of the potential parameter. The behaviors of electron states in different regions are similar to that of periodic and disorder QSWNs, respectively.Comment: 6 pages, 13figure

Instanton Effects in Three-Dimensional Supersymmetric Gauge Theories with Matter

Using standard field theory techniques we compute perturbative and instanton contributions to the Coulomb branch of three-dimensional supersymmetric QCD with N=2 and N=4 supersymmetry and gauge group SU(2). For the N=4 theory with one massless flavor, we confirm the proposal of Seiberg and Witten that the Coulomb branch is the double-cover of the centered moduli space of two BPS monopoles constructed by Atiyah and Hitchin. Introducing a hypermultiplet mass term, we show that the asymptotic metric on the Coulomb branch coincides with the metric on Dancer's deformation of the monopole moduli space. For the N=2 theory with $N_f$ flavors, we compute the one-loop corrections to the metric and complex structure on the Coulomb branch. We then determine the superpotential including one-loop effects around the instanton background. These calculations provide an explicit check of several results previously obtained by symmetry and holomorphy arguments.Comment: 24 pages, Late

von Neumann entropy and localization properties of two interacting particles in one-dimensional nonuniform systems

With the help of von Neumann entropy, we study numerically the localization properties of two interacting particles (TIP) with on-site interactions in one-dimensional disordered, quasiperiodic, and slowly varying potential systems, respectively. We find that for TIP in disordered and slowly varying potential systems, the spectrum-averaged von Neumann entropy first increases with interaction U until its peak, then decreases as U gets larger. For TIP in the Harper model[S. N. Evangelou and D. E. Katsanos, Phys. Rev. B 56, 12797(1997)], the functions of versus U are different for particles in extended and localized regimes. Our numerical results indicate that for these two-particle systems, the von Neumann entropy is a suitable quantity to characterize the localization properties of particle states. Moreover, our studies propose a consistent interpretation of the discrepancies between previous numerical results.Comment: 7 pages,13 figure

Lunar landing module reflectivity model

Lunar landing module reflectivity model based on Surveyor and Orbiter photographs of lunar craters, hills, and boulder

Probable deviations in altitude reading given by the LM altimeter for the most rough surface along a certain given trajectory

Random noise calculations in altitude reading of lunar module altimeter for rough surfaces targe

Strongly modulated transmissions in gapped armchair graphene nanoribbons with sidearm or on-site gate voltage

We propose two schemes of field-effect transistor based on gapped armchair graphene nanoribbons connected to metal leads, by introducing sidearms or on-site gate voltages. We make use of the band gap to reach excellent switch-off character. By introducing one sidearm or on-site gate to the graphene nanoribbon, conduction peaks appear inside the gap regime. By further applying two sidearms or on-site gates, these peaks are broadened to conduction plateaus with a wide energy window, thanks to the resonance from the dual structure. The position of the conduction windows inside the gap can be fully controlled by the length of the sidearms or the on-site gate voltages, which allows "on" and "off" operations for a specific energy window inside the gap regime. The high robustness of both the switch-off character and the conduction windows is demonstrated and shows the feasibility of the proposed dual structures for real applications.Comment: 6 pages, 6 figure

Professionalising policing: seeking viable and sustainable approaches to police education and learning

This paper will explore the ‘police professionalization agenda’ and provide a brief outline of the ‘Police Qualification Education Framework’ (PEQF) administered by the College of Policing (CoP) in the United Kingdom, discuss the art, craft and science as a platform for evolving professionalization in policing and finally consider the future of policing with advances in technology. I will argue that the police service not only needs to consider how technology will affect the roles and activities of the police but also the impact on the communities that the police serve

The Quantum Dynamics of Heterotic Vortex Strings

We study the quantum dynamics of vortex strings in N=1 SQCD with U(N_c) gauge group and N_f=N_c quarks. The classical worldsheet of the string has N=(0,2) supersymmetry, but this is broken by quantum effects. We show how the pattern of supersymmetry breaking and restoration on the worldsheet captures the quantum dynamics of the underlying 4d theory. We also find qualitative matching of the meson spectrum in 4d and the spectrum on the worldsheet.Comment: 13 page

Gravitational Lensing by Dark Matter Halos with Non-universal Density Profiles

The statistics of gravitational lensing can provide us with a very powerful probe of the mass distribution of matter in the universe. By comparing predicted strong lensing probabilities with observations, we can test the mass distribution of dark matter halos, in particular, the inner density slope. In this letter, unlike previous work that directly models the density profiles of dark matter halos semi-analytically, we generalize the density profiles of dark matter halos from high-resolution N-body simulations by means of generalized Navarro-Frenk-White (GNFW) models of three populations with slopes, $\alpha$, of about -1.5, -1.3 and -1.1 for galaxies, groups and clusters, respectively. This approach is an alternative and independent way to examine the slopes of mass density profiles of halos. We present calculations of lensing probabilities using these GNFW profiles for three populations in various spatially flat cosmological models with a cosmological constant $\Lambda$. It is shown that the compound model of density profiles does not match well with the observed lensing probabilities derived from the Jodrell-Bank VLA Astrometric Survey data in combination with the Cosmic Lens All-Sky Survey data. Together with the previous work on lensing probability, our results suggest that a singular isothermal sphere mass model of less than about 10^{13}h^{-1}M_{\sun} can predict strong lensing probabilities that are consistent with observations of small splitting angles.Comment: 11 pages, 2 figures, Accepted by ApJL for publication (February 10 issue 2004

Fidelity, fidelity susceptibility and von Neumann entropy to characterize the phase diagram of an extended Harper model

For an extended Harper model, the fidelity for two lowest band edge states corresponding to different model parameters, the fidelity susceptibility and the von Neumann entropy of the lowest band edge states, and the spectrum-averaged von Neumann entropy are studied numerically, respectively. The fidelity is near one when parameters are in the same phase or same phase boundary; otherwise it is close to zero. There are drastic changes in fidelity when one parameter is at phase boundaries. For fidelity susceptibility the finite scaling analysis performed, the critical exponents $\alpha$, $\beta$, and $\nu$ depend on system sizes for the metal-metal phase transition, while not for the metal-insulator phase transition. For both phase transitions $\nu/\alpha\approx2$. The von Neumann entropy is near one for the metallic phase, while small for the insulating phase. There are sharp changes in von Neumann entropy at phase boundaries. According to the variation of the fidelity, fidelity susceptibility, and von Neumann entropy with model parameters, the phase diagram, which including two metallic phases and one insulating phase separated by three critical lines with one bicritical point, can be completely characterized, respectively. These numerical results indicate that the three quantities are suited for revealing all the critical phenomena in the model.Comment: 9 pages, 12 figure