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Sample records for anderson localization excited

  1. Signatures of Anderson localization excited by an optical frequency comb

    KAUST Repository

    Gentilini, S.

    2010-01-25

    We investigate Anderson localization of light as occurring in ultrashort excitations. A theory based on time dependent coupled-mode equations predicts universal features in the spectrum of the transmitted pulse. In particular, the process of strong localization of light is shown to correspond to the formation of peaks in both the amplitude and in the group delay of the transmitted pulse. Parallel ab initio simulations made with finite-difference time-domain codes and molecular dynamics confirm theoretical predictions, while showing that there exists an optimal degree of disorder for the strong localization. © 2010 The American Physical Society.

  2. Anderson localization in metallic nanoparticle arrays

    CERN Document Server

    Mai, Zhijie; Pang, Wei; Xu, Haitao; Tan, Suiyan; Fu, Shenhe; Li, Yongyao

    2016-01-01

    Anderson localization has been observed in various types of waves, such as matter waves, optical waves and acoustic waves. Here we reveal that the effect of Anderson localization can be also induced in metallic nonlinear nanoparticle arrays excited by a random electrically driving field. We find that the dipole-induced nonlinearity results in ballistic expansion of dipole intensity during evolution; while the randomness of the external driving field can suppress such an expansion. Increasing the strength of randomness above the threshold value, a localized pattern of dipole intensity can be generated in the metallic nanoparticle arrays. By means of statistics, the mean intensity distribution of the dipoles reveals the formation of Anderson localization. We further show that the generated Anderson localization is highly confined, with its size down to the scale of incident wavelength. The reported results might facilitate the manipulations of electromagnetic fields in the scale of wavelength.

  3. Anderson localization in metallic nanoparticle arrays

    Science.gov (United States)

    Mai, Zhijie; Lin, Fang; Pang, Wei; Xu, Haitao; Tan, Suiyan; Fu, Shenhe; Li, Yongyao

    2016-06-01

    Anderson localization has been observed in various types of waves, such as matter waves, optical waves and acoustic waves. Here we reveal that the effect of Anderson localization can be also induced in metallic nonlinear nanoparticle arrays excited by a random electrically driving field. We find that the dipole-induced nonlinearity results in ballistic expansion of dipole intensity during evolution; while the randomness of the external driving field can suppress such an expansion. Increasing the strength of randomness above the threshold value, a localized pattern of dipole intensity can be generated in the metallic nanoparticle arrays. By means of statistics, the mean intensity distribution of the dipoles reveals the formation of Anderson localization. We further show that the generated Anderson localization is highly confined, with its size down to the scale of incident wavelength. The reported results might facilitate the manipulations of electromagnetic fields in the scale of wavelength.

  4. Hybrid Bloch-Anderson localization of light

    CERN Document Server

    Stutzer, Simon; Vysloukh, Victor A; Konotop, Vladimir V; Nolte, Stefan; Torner, Lluis; Szameit, Alexander

    2013-01-01

    We investigate the interplay of Bloch oscillations and Anderson localization in optics. Gradual washing out of Bloch oscillations and the formation of nearly stationary averaged intensity distributions, which are symmetric for narrow and strongly asymmetric for broad input excitations, are observed experimentally in laser-written waveguide arrays. At large disorder levels Bloch oscillations are completely destroyed and both narrow and wide excitations lead to symmetric stationary averaged intensity distributions with exponentially decaying tails.

  5. Hybrid Bloch-Anderson localization of light.

    Science.gov (United States)

    Stützer, Simon; Kartashov, Yaroslav V; Vysloukh, Victor A; Konotop, Vladimir V; Nolte, Stefan; Torner, Lluis; Szameit, Alexander

    2013-05-01

    We investigate the interplay of Bloch oscillations and Anderson localization in optics. Gradual washing out of Bloch oscillations and the formation of nearly stationary averaged intensity distributions, which are symmetric for narrow and strongly asymmetric for broad input excitations, are observed experimentally in laser-written waveguide arrays. At large disorder levels Bloch oscillations are completely destroyed and both narrow and wide excitations lead to symmetric stationary averaged intensity distributions with exponentially decaying tails.

  6. 50 Years of Anderson Localization

    CERN Document Server

    Abrahams, Elihu

    2010-01-01

    In his groundbreaking paper Absence of diffusion in certain random lattices (1958), Philip W. Anderson originated, described and developed the physical principles underlying the phenomenon of the localization of quantum objects due to disorder. Anderson's 1977 Nobel Prize citation featured that paper, which was fundamental for many subsequent developments in condensed matter theory and technical applications. After more than a half century, the subject continues to be of fundamental importance. In particular, in the last 25 years, the phenomenon of localization has proved to be crucial for the

  7. Anderson localization from classical trajectories

    OpenAIRE

    Brouwer, Piet W.; Altland, Alexander

    2008-01-01

    We show that Anderson localization in quasi-one dimensional conductors with ballistic electron dynamics, such as an array of ballistic chaotic cavities connected via ballistic contacts, can be understood in terms of classical electron trajectories only. At large length scales, an exponential proliferation of trajectories of nearly identical classical action generates an abundance of interference terms, which eventually leads to a suppression of transport coefficients. We quantitatively descri...

  8. Anderson Localization in Nonlocal Nonlinear Media

    CERN Document Server

    Folli, Viola; 10.1364/OL.37.000332

    2012-01-01

    The effect of focusing and defocusing nonlinearities on Anderson localization in highly nonlocal media is theoretically and numerically investigated. A perturbative approach is developed to solve the nonlocal nonlinear Schroedinger equation in the presence of a random potential, showing that nonlocality stabilizes Anderson states.

  9. Random nanolasing in the Anderson localized regime

    DEFF Research Database (Denmark)

    Liu, Jin; Garcia, P. D.; Ek, Sara;

    2014-01-01

    multiple scattering. The applicability of random lasers has been limited due to multidirectional emission, lack of tunability, and strong mode competition with chaotic fluctuations due to a weak mode confinement. The regime of Anderson localization of light has been proposed for obtaining stable multimode...... random lasing, and initial work concerned macroscopic one-dimensional layered media. Here, we demonstrate on-chip random nanolasers where the cavity feedback is provided by the intrinsic disorder. The strong confinement achieved by Anderson localization reduces the spatial overlap between lasing modes...

  10. An Anderson-localized random nanolaser

    CERN Document Server

    Liu, Jin; Ek, Sara; Gregersen, Niels; Suhr, Troels; Schubert, Martin; Mørk, Jesper; Stobbe, Søren; Lodahl, Peter

    2012-01-01

    Precision is a virtue throughout science in general and in optics in particular where carefully fabricated nanometer-scale devices hold great promise for both classical and quantum photonics [1-6]. In such nanostructures, unavoidable imperfections often impose severe performance limits but, in certain cases, disorder may enable new functionalities [7]. Here we demonstrate on-chip random nanolasers where the cavity feedback is provided by the intrinsic disorder in a semiconductor photonic-crystal waveguide, leading to Anderson localization of light [8]. This enables highly e?cient and broadband tunable lasers with very small mode volumes. We observe an intriguing interplay between gain, dispersion-controlled slow light, and disorder, which determines the cross-over from ballistic transport to Anderson localization. Such a behavior is a unique feature of non-conservative random media that enables the demonstration of all-optical control of random lasing. Our statistical analysis shows a way towards ultimate thr...

  11. Distribution of critical temperature at Anderson localization

    Science.gov (United States)

    Gammag, Rayda; Kim, Ki-Seok

    2016-05-01

    Based on a local mean-field theory approach at Anderson localization, we find a distribution function of critical temperature from that of disorder. An essential point of this local mean-field theory approach is that the information of the wave-function multifractality is introduced. The distribution function of the Kondo temperature (TK) shows a power-law tail in the limit of TK→0 regardless of the Kondo coupling constant. We also find that the distribution function of the ferromagnetic transition temperature (Tc) gives a power-law behavior in the limit of Tc→0 when an interaction parameter for ferromagnetic instability lies below a critical value. However, the Tc distribution function stops the power-law increasing behavior in the Tc→0 limit and vanishes beyond the critical interaction parameter inside the ferromagnetic phase. These results imply that the typical Kondo temperature given by a geometric average always vanishes due to finite density of the distribution function in the TK→0 limit while the typical ferromagnetic transition temperature shows a phase transition at the critical interaction parameter. We propose that the typical transition temperature serves a criterion for quantum Griffiths phenomena vs smeared transitions: Quantum Griffiths phenomena occur above the typical value of the critical temperature while smeared phase transitions result at low temperatures below the typical transition temperature. We speculate that the ferromagnetic transition at Anderson localization shows the evolution from quantum Griffiths phenomena to smeared transitions around the critical interaction parameter at low temperatures.

  12. Exciting Molecules Close to the Rotational Quantum Resonance: Anderson Wall and Rotational Bloch Oscillations.

    Science.gov (United States)

    Floß, Johannes; Averbukh, Ilya Sh

    2016-05-19

    We describe a universal behavior of linear molecules excited by a periodic train of short laser pulses under conditions close to the quantum resonance. The quantum resonance effect causes an unlimited ballistic growth of the angular momentum. We show that a disturbance of the quantum resonance, either by the centrifugal distortion of the rotating molecules or a controlled detuning of the pulse train period from the so-called rotational revival time, eventually halts the growth by causing Anderson localization beyond a critical value of the angular momentum, the Anderson wall. Below the wall, the rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. We suggest optical experiments capable of observing the rotational Anderson wall and Bloch oscillations at near-ambient conditions with the help of existing laser technology.

  13. Controlling Anderson localization in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren;

    2010-01-01

    In most experiments on Anderson localization so far, only completely random systems without any long-range correlation between the scattering sites have been used, meaning that the Anderson localized modes cannot be controlled. Strongly confined modes were recently observed in the slow-light regime...... of a disordered photonic crystal waveguide and attributed to Anderson localization. We have tested this hypothesis by measuring the light localization length, ξloc, in a disordered photonic crystal waveguide and checked explicitly the criterion of one dimensional Anderson localization that ξloc is...... shorter than the waveguide length LS. Our measurements demonstrate for the first time the close relation between light localization and density of states, which can be used ultimately for controlling Anderson localized modes....

  14. Probing the statistical properties of Anderson localization with quantum emitters

    DEFF Research Database (Denmark)

    Smolka, Stephan; Nielsen, Henri Thyrrestrup; Sapienza, Luca;

    2011-01-01

    Wave propagation in disordered media can be strongly modified by multiple scattering and wave interference. Ultimately, the so-called Anderson-localized regime is reached when the waves become strongly confined in space. So far, Anderson localization of light has been probed in transmission...

  15. Controlling Anderson localization in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Smolka, Stephan; Garcia, Pedro D.; Lodahl, Peter

    2010-01-01

    We prove Anderson localization in the slow-light regime of a photonic crystal waveguide by measuring the ensemble-averaged localization length which is controlled by the dispersion of the disordered photonic crystal waveguide.......We prove Anderson localization in the slow-light regime of a photonic crystal waveguide by measuring the ensemble-averaged localization length which is controlled by the dispersion of the disordered photonic crystal waveguide....

  16. Transverse Anderson localization of light: a tutorial review

    OpenAIRE

    Mafi, Arash

    2015-01-01

    This tutorial review gives an overview of the transverse Anderson localization of light in one and two transverse dimensions. A pedagogical approach is followed throughout the presentation, where many aspects of localization are illustrated by means of a few simple models. The tutorial starts with some basic aspects of random matrix theory, and light propagation through and reflection from a random stack of dielectric slabs. Transverse Anderson localization of light in one- and two-dimensiona...

  17. Cavity quantum electrodynamics in the Anderson-localized regime

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2010-01-01

    We experimentally measure, by means of time-resolved photoluminescence spectroscopy, a 15-fold enhancement of the spontaneous emission decay rate of single semiconductor quantum dots coupled to disorder-induced Anderson-localized modes with efficiencies reaching 94%....

  18. Anderson localization of spinons in a spin-1/2 antiferromagnetic Heisenberg chain

    OpenAIRE

    Pan, B. Y.; Zhou, S. Y.; Hong, X. C.; Qiu, X; Li, S. Y.

    2012-01-01

    Anderson localization is a general phenomenon of wave physics, which stems from the interference between multiple scattering paths1,2. It was originally proposed for electrons in a crystal, but later was also observed for light3-5, microwaves6, ultrasound7,8, and ultracold atoms9-12. Actually, in a crystal, besides electrons there may exist other quasiparticles such as magnons and spinons. However the search for Anderson localization of these magnetic excitations is rare so far. Here we repor...

  19. Absence of Anderson localization in certain random lattices

    OpenAIRE

    Choi, Wonjun; Yin, Cheng; Hooper, Ian R.; Bernes, William L.; Bertolotti, Jacopo

    2016-01-01

    We report on the transition between an Anderson localized regime and a conductive regime in a 1D scattering system with correlated disorder. We show experimentally that when long-range correlations, in the form of a power-law spectral density with power larger than 2, are introduced the localization length becomes much bigger than the sample size and the transmission peaks typical of an Anderson localized system merge into a pass band. As other forms of long-range correlations are known to ha...

  20. Multiple-beam Propagation in an Anderson Localized Optical Fiber

    CERN Document Server

    Karbasi, Salman; Mafi, Arash

    2012-01-01

    We investigate the simultaneous propagation of multiple beams in a disordered Anderson localized optical fiber. The profiles of each beam fall off exponentially, enabling multiple channels at high-density. We examine the influence of fiber bends on the movement of the beam positions, which we refer to as drift. We investigate the extent of the drift of localized beams induced by macro-bending and show that it is possible to design Anderson localized optical fibers which can be used for practical beam-multiplexing applications.

  1. Interplay of Anderson localization and strong interaction in disordered systems

    Energy Technology Data Exchange (ETDEWEB)

    Henseler, Peter

    2010-01-15

    We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length {xi}, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of {xi} for small and intermediate disorders and a strong reduction of {xi} due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of {xi} as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)

  2. Interplay of Anderson localization and strong interaction in disordered systems

    International Nuclear Information System (INIS)

    We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length ξ, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of ξ for small and intermediate disorders and a strong reduction of ξ due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of ξ as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)

  3. A modal perspective on the transverse Anderson localization of light in disordered optical lattices

    CERN Document Server

    Karbasi, Salman; Mafi, Arash

    2013-01-01

    We frame the transverse Anderson localization of light in a one-dimensional disordered optical lattice in the language of localized propagating eigenmodes. The modal analysis allows us to explore localization behavior of a disordered lattice independent of the properties of the external excitation. Various localization-related phenomena, such as the periodic revival of a propagating Anderson-localized beam are easily explained in modal language. We characterize the localization strength by the average width of the guided modes and carry out a detailed analysis of localization behavior as a function of the optical and geometrical parameters of the disordered lattice. We also show that in order to obtain a minimum average mode width, the average width of the individual random sites in the disordered lattice must be larger than the wavelength of the light by approximately a factor of two or more, and the optimum site width for the maximum localization depends on the design parameters of the disordered lattice.

  4. Cavity quantum electrodynamics with Anderson-localized modes

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2010-01-01

    by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices....

  5. Topological principles in the theory of Anderson localization

    NARCIS (Netherlands)

    A.M.M. Pruisken

    2009-01-01

    Scaling ideas in the theory of the quantum Hall effect are fundamentally based on topological principles in Anderson localization theory. These concepts have a very general significance and are not limited to replica field theory or disordered systems alone. We will discuss these ideas in several di

  6. Absence of Anderson localization in certain random lattices

    CERN Document Server

    Choi, Wonjun; Hooper, Ian R; Bernes, William L; Bertolotti, Jacopo

    2016-01-01

    We report on the transition between an Anderson localized regime and a conductive regime in a 1D scattering system with correlated disorder. We show experimentally that when long-range correlations, in the form of a power-law spectral density with power larger than 2, are introduced the localization length becomes much bigger than the sample size and the transmission peaks typical of an Anderson localized system merge into a pass band. As other forms of long-range correlations are known to have the opposite effect, i.e. to enhance localization, our results show that care is needed when discussing the effects of correlations, as different kinds of long-range correlations can give rise to very different behavior.

  7. Photon transport enhanced by transverse Anderson localization in disordered superlattices

    CERN Document Server

    Hsieh, Pin-Chun; McMillan, James; Tsai, Min-An; Lu, Ming; Panoiu, Nicolae; Wong, Chee Wei

    2014-01-01

    One of the daunting challenges in optical physics is to accurately control the flow of light at the subwavelength scale, by patterning the optical medium one can design anisotropic media. The light transport can also be significantly affected by Anderson localization, namely the wave localization in a disordered medium, a ubiquitous phenomenon in wave physics. Here we report the photon transport and collimation enhanced by transverse Anderson localization in chip-scale dispersion engineered anisotropic media. We demonstrate a new type of anisotropic photonic structure in which diffraction is nearly completely arrested by cascaded resonant tunneling through transverse guided resonances. By perturbing the shape of more than 4,000 scatterers in these superlattices we add structural disordered in a controlled manner and uncover the mechanism of disorder-induced transverse localization at the chip-scale. Arrested spatial divergence is captured in the power-law scaling, along with exponential asymmetric mode profil...

  8. Transverse Anderson localization of light: a tutorial review

    CERN Document Server

    Mafi, Arash

    2015-01-01

    This tutorial review gives an overview of the transverse Anderson localization of light in one and two transverse dimensions. A pedagogical approach is followed throughout the presentation, where many aspects of localization are illustrated by means of a few simple models. The tutorial starts with some basic aspects of random matrix theory, and light propagation through and reflection from a random stack of dielectric slabs. Transverse Anderson localization of light in one- and two-dimensional coupled waveguide arrays is subsequently established and discussed. Recent experimental observations of localization and image transport in disordered optical fibers are discussed. More advanced topics, such as hyper-transport in longitudinally varying disordered waveguides, the impact of nonlinearity, and propagation of partially coherent and quantum light, are also examined.

  9. Many-body Anderson localization in one-dimensional systems

    Science.gov (United States)

    Delande, Dominique; Sacha, Krzysztof; Płodzień, Marcin; Avazbaev, Sanat K.; Zakrzewski, Jakub

    2013-04-01

    We show, using quasi-exact numerical simulations, that Anderson localization in a disordered one-dimensional potential survives in the presence of attractive interaction between particles. The localization length of the particles' center of mass—computed analytically for weak disorder—is in good agreement with the quasi-exact numerical observations using the time evolving block decimation algorithm. Our approach allows for simulation of the entire experiment including the final measurement of all atom positions.

  10. Quantum-classical correspondence in multimensional nonlinear systems: Anderson localization and "superdiffusive" solitons

    KAUST Repository

    Brambila, Danilo

    2012-01-01

    We have theoretically studied Anderson localization in a 2D+1 nonlinear kicked rotor model. The system shows a very rich dynamical behavior, where the Anderson localization is suppressed and soliton wave-particles undergo a superdiffusive motion.

  11. Multi-Scale Jacobi Method for Anderson Localization

    Science.gov (United States)

    Imbrie, John Z.

    2015-11-01

    A new KAM-style proof of Anderson localization is obtained. A sequence of local rotations is defined, such that off-diagonal matrix elements of the Hamiltonian are driven rapidly to zero. This leads to the first proof via multi-scale analysis of exponential decay of the eigenfunction correlator (this implies strong dynamical localization). The method has been used in recent work on many-body localization (Imbrie in On many-body localization for quantum spin chains, arXiv:1403.7837 URL"/> , 2014).

  12. Experimental observation of Anderson localization in laser-kicked molecular rotors

    CERN Document Server

    Bitter, Martin

    2016-01-01

    We observe and study the phenomenon of Anderson localization in a system of true quantum kicked rotors. Nitrogen molecules in a supersonic molecular jet are cooled down to 27~K and are rotationally excited by a periodic train of 24~high-intensity femtosecond pulses. Exponential distribution of the molecular angular momentum - the most unambiguous signature of Anderson localization - is measured directly by means of coherent Raman scattering. We demonstrate the suppressed growth of the molecular rotational energy with the number of laser kicks and study the dependence of the localization length on the kick strength. Both timing and amplitude noise in the pulse train is shown to destroy the localization and revive the diffusive growth of angular momentum.

  13. Cavity quantum electrodynamics with Anderson-localized modes.

    Science.gov (United States)

    Sapienza, Luca; Thyrrestrup, Henri; Stobbe, Søren; Garcia, Pedro David; Smolka, Stephan; Lodahl, Peter

    2010-03-12

    A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.

  14. Quasiperiodic driving of Anderson localized waves in one dimension

    OpenAIRE

    Hatami, H.; Danieli, C.; Bodyfelt, J. D.; Flach, S

    2016-01-01

    We consider a quantum particle in a one-dimensional disordered lattice with Anderson localization, in the presence of multi-frequency perturbations of the onsite energies. Using the Floquet representation, we transform the eigenvalue problem into a Wannier-Stark basis. Each frequency component contributes either to a single channel or a multi-channel connectivity along the lattice, depending on the control parameters. The single channel regime is essentially equivalent to the undriven case. T...

  15. Quasiperiodic driving of Anderson localized waves in one dimension

    Science.gov (United States)

    Hatami, H.; Danieli, C.; Bodyfelt, J. D.; Flach, S.

    2016-06-01

    We consider a quantum particle in a one-dimensional disordered lattice with Anderson localization in the presence of multifrequency perturbations of the onsite energies. Using the Floquet representation, we transform the eigenvalue problem into a Wannier-Stark basis. Each frequency component contributes either to a single channel or a multichannel connectivity along the lattice, depending on the control parameters. The single-channel regime is essentially equivalent to the undriven case. The multichannel driving increases substantially the localization length for slow driving, showing two different scaling regimes of weak and strong driving, yet the localization length stays finite for a finite number of frequency components.

  16. Integrals of motion for one-dimensional Anderson localized systems

    Science.gov (United States)

    Modak, Ranjan; Mukerjee, Subroto; Yuzbashyan, Emil A.; Shastry, B. Sriram

    2016-03-01

    Anderson localization is known to be inevitable in one-dimension for generic disordered models. Since localization leads to Poissonian energy level statistics, we ask if localized systems possess ‘additional’ integrals of motion as well, so as to enhance the analogy with quantum integrable systems. We answer this in the affirmative in the present work. We construct a set of nontrivial integrals of motion for Anderson localized models, in terms of the original creation and annihilation operators. These are found as a power series in the hopping parameter. The recently found Type-1 Hamiltonians, which are known to be quantum integrable in a precise sense, motivate our construction. We note that these models can be viewed as disordered electron models with infinite-range hopping, where a similar series truncates at the linear order. We show that despite the infinite range hopping, all states but one are localized. We also study the conservation laws for the disorder free Aubry-Andre model, where the states are either localized or extended, depending on the strength of a coupling constant. We formulate a specific procedure for averaging over disorder, in order to examine the convergence of the power series. Using this procedure in the Aubry-Andre model, we show that integrals of motion given by our construction are well-defined in localized phase, but not so in the extended phase. Finally, we also obtain the integrals of motion for a model with interactions to lowest order in the interaction.

  17. Two-particle Anderson localization at low energies

    CERN Document Server

    Ekanga, Trésor

    2012-01-01

    We prove exponential spectral localization in a two-particle lattice Anderson model, with a short-range interaction and external random i.i.d. potential, at sufficiently low energies. The proof is based on the multi-particle multi-scale analysis developed earlier by Chulaevsky and Suhov (2009) in the case of high disorder. Our method applies to a larger class of random potentials than in Aizenman and Warzel (2009) where dynamical localization was proved with the help of the fractional moment method.

  18. Defect-controlled Anderson localization of light in photonic lattices

    International Nuclear Information System (INIS)

    The transverse localization of light in a disordered photonic lattice with a central defect is analyzed numerically. The effect of different input beam widths on various regimes of Anderson localization is investigated. The inclusion of a defect enhances the localization of both narrow and broad beams, as compared to the lattice with no defect. But, in the case of a broad beam a higher disorder level is needed to reach the same localization as for a narrow input beam. It is also investigated how the transverse localization of light in such geometries depends on both the strength of disorder and the strength of nonlinearity in the system. While in the linear regime the localization is most pronounced in the lattice with the defect, in the nonlinear regime this is not the case. (paper)

  19. Effect of coulomb interaction on Anderson localization; Effet de l'interaction coulombienne sur la localisation d'Anderson dans des systemes de basses dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Waintal, X

    1999-09-10

    We study the quantum mechanics of interacting particles in a disordered system, and in particular, what happens to Anderson localisation when interaction is taken into account. In the first part,one looks at the excited states of two particles in one dimension. For this model, it has been shown (Shepelyansky 1994) that a local repulsive interaction can partially destroy Anderson localisation. Here, we show that this model has similarities with the three-dimensional Anderson model at the metal-insulator transition. In particular, the maximum of rigidity obtained in the spectral statistics correspond to some intermediary statistics that cannot be described by random matrix theory neither by a Poisson statistics. The wave functions show a multifractal behaviour and the spreading of the center of mass of a wave packet is logarithmic in time. The second part deals with the ground state of a finite density of spinless fermions in two dimensions. After the scaling theory of localisation, it was commonly accepted that there was no metal in two dimensions. This idea has been challenged by the observation of a metal-insulator transition in low density electron gas (Kravchenko et al. 1994). We propose a scenario in which a metallic phase occurs between the Anderson insulator and the pinned Wigner crystal. This intermediate phase is characterized by an alignment of the local currents flowing in the system. (author)

  20. Transversal Anderson localization of sound in acoustic waveguide arrays

    International Nuclear Information System (INIS)

    We present designs of one-dimensional acoustic waveguide arrays and investigate wave propagation inside. Under the condition of single identical waveguide mode and weak coupling, the acoustic wave motion in waveguide arrays can be modeled with a discrete mode-coupling theory. The coupling constants can be retrieved from simulations or experiments as the function of neighboring waveguide separations. Sound injected into periodic arrays gives rise to the discrete diffraction, exhibiting ballistic or extended transport in transversal direction. But sound injected into randomized waveguide arrays readily leads to Anderson localization transversally. The experimental results show good agreement with simulations and theoretical predictions. (paper)

  1. Experimental Observation of Two-Dimensional Anderson Localization with the Atomic Kicked Rotor

    OpenAIRE

    Manai, Isam; Clément, Jean-François; Chicireanu, Radu; Hainaut, Clément; Garreau, Jean Claude; Szriftgiser, Pascal; Delande, Dominique

    2015-01-01

    Dimension 2 is expected to be the lower critical dimension for Anderson localization in a time-reversal-invariant disordered quantum system: the dynamics is generically localized in dimension lower than 2, while it presents a transition from a diffusive regime at weak disorder to a localized regime at strong disorder in dimension larger than 2. We use an atomic quasiperiodically kicked rotor – equivalent to a two-dimensional Anderson-like model – to experimentally study Anderson localization ...

  2. Quantum resonance, Anderson localisation and selective rotational excitation in periodically kicked molecules

    Directory of Open Access Journals (Sweden)

    Averbukh I. Sh.

    2013-03-01

    Full Text Available We show that molecules kicked periodically by laser pulses currently used in molecular alignment experiments allow to observe effects of the periodically kicked quantum rotor in a real rotational system. Among these effects are Anderson localisation in angular momentum and the scaling of the quantum resonance. Based on this, we propose a new scheme for selective molecular rotational excitation.

  3. Experimental Observation of Two-Dimensional Anderson Localization with the Atomic Kicked Rotor.

    Science.gov (United States)

    Manai, Isam; Clément, Jean-François; Chicireanu, Radu; Hainaut, Clément; Garreau, Jean Claude; Szriftgiser, Pascal; Delande, Dominique

    2015-12-11

    Dimension 2 is expected to be the lower critical dimension for Anderson localization in a time-reversal-invariant disordered quantum system. Using an atomic quasiperiodic kicked rotor-equivalent to a two-dimensional Anderson-like model-we experimentally study Anderson localization in dimension 2 and we observe localized wave function dynamics. We also show that the localization length depends exponentially on the disorder strength and anisotropy and is in quantitative agreement with the predictions of the self-consistent theory for the 2D Anderson localization. PMID:26705619

  4. Density of states controls Anderson localization in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren;

    2010-01-01

    We prove Anderson localization in a disordered photonic crystal waveguide by measuring the ensemble-averaged extinction mean-free path, ℓe, which is controlled by the dispersion in the photon density of states (DOS) of the photonic crystal waveguide. Except for the very low DOS case, where out...... demonstrates the close relation between Anderson localization and the DOS in disordered photonic crystals, which opens a promising route to controlling and exploiting Anderson-localized modes for efficient light confinement....

  5. Information Transmission and Anderson Localization in two-dimensional networks of firing-rate neurons

    Science.gov (United States)

    Natale, Joseph; Hentschel, George

    Firing-rate networks offer a coarse model of signal propagation in the brain. Here we analyze sparse, 2D planar firing-rate networks with no synapses beyond a certain cutoff distance. Additionally, we impose Dale's Principle to ensure that each neuron makes only or inhibitory outgoing connections. Using spectral methods, we find that the number of neurons participating in excitations of the network becomes insignificant whenever the connectivity cutoff is tuned to a value near or below the average interneuron separation. Further, neural activations exceeding a certain threshold stay confined to a small region of space. This behavior is an instance of Anderson localization, a disorder-induced phase transition by which an information channel is rendered unable to transmit signals. We discuss several potential implications of localization for both local and long-range computation in the brain. This work was supported in part by Grants JSMF/ 220020321 and NSF/IOS/1208126.

  6. All-solid-state cavity QED using Anderson-localized modes in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lodahl, Peter; Sapienza, Luca; Nielsen, Henri Thyrrestrup;

    2010-01-01

    We employ Anderson-localized modes in deliberately disordered photonic crystal waveguides to confine light and enhance the interaction with matter. A 15-fold enhancement of the decay rate of a single quantum dot is observed meaning that 94% of the emitted single photons are coupled to an Anderson...

  7. Two-photon Anderson localization in a disordered quadratic waveguide array

    International Nuclear Information System (INIS)

    We theoretically investigate two-photon Anderson localization in a χ (2) waveguide array with off-diagonal disorder. The nonlinear parametric down-conversion process would enhance both the single-photon and the two-photon Anderson localization. In the strong disorder regime, the two-photon position correlation exhibits a bunching distribution around the pumped waveguides, which is independent of pumping conditions and geometrical structures of waveguide arrays. Quadratic nonlinearity can be supplied as a new ingredient for Anderson localization. Also, our results pave the way for engineering quantum states through nonlinear quantum walks. (paper)

  8. Routes Towards Anderson-Like Localization of Bose-Einstein Condensates in Disordered Optical Lattices

    Science.gov (United States)

    Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J.; Sacha, K.; Zakrzewski, J.; Lewenstein, M.

    2005-10-01

    We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

  9. Routes Towards Anderson-Like Localization of Bose-Einstein Condensates in Disordered Optical Lattices

    International Nuclear Information System (INIS)

    We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters

  10. Localization of optical excitations on random surfaces: SNOM studies

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Localization of optical excitations on nanostructured metal surfaces and fractal colloid silver aggregates are studied by using a scanning near-field optical microscope (SNOM). The SNOM images obtained in both configurations exhibit spatially localized (within 150 to 250 nm) light intensity enhan...... enhancement by up to two orders of magnitude. The observed phenomena are related to strong (Anderson) localization of quasi-two-dimensional light waves....

  11. Anderson localization to enhance light-matter interaction (Conference Presentation)

    Science.gov (United States)

    Garcia, Pedro David

    2016-04-01

    Deliberately introducing disorder in low-dimensional nanostructures like photonic crystal waveguides (PCWs) [1] or photonic crystals (PCs) [2] leads to Anderson localization where light is efficiently trapped by random multiple scattering with the lattice imperfections. These disorder-induced optical modes hace been demonstrated to be very promising for cavity-quantum electrodynamics (QED) experiments where the radiative emission rate of single quantum emitters can be controlled when tuned through resonance with one of these random cavities. Our statistical analysis of the emission dynamics from single quantum dots embeded in disordered PCWs [3] provides detailed insigth about the statistical properties of QED in these complex nanostructures. In addition, using internal light sources reveals new physics in the form of nonuniversal intensity correlations between the different scattered paths within the structure which imprint the local QED properties deep inside the complex structure onto the far-field intensity pattern [2]. Finally, increasing the optical gain in PCWs allows on-chip random nanolasing where the cavity feedback is provided by the intrinsic disorder which enables highly efficient, stable, and broadband tunable lasers with very small mode volumes [4]. The figure of merit of these disorder-induced cavities is their localization length which determines to a large degree the coupling efficiency of a quantum emitter to a disorder-induced cavity as well as the efficiency of random lasing and reveals a strongly dispersive behavior and a non-trivial dependence on disorder in PCWs [5]. [1] L. Sapienza, H. Thyrrestrup, S. Stobbe, P.D. Garcia, S. Smolka, and P. Lodahl, Science 327, 1352 (2010). [2] P. D. García, S. Stobbe, I. Soellner and P. Lodahl, Physical Review Letters 109, 253902 (2012). [3] A. Javadi, S. Maibom, L. Sapienza, H. Thyrrestrup, P.D. Garcia, and P. Lodahl, Opt. Express 22, 30992 (2014). [4] J. Liu, P. D. Garcia, S. Ek, N. Gregersen, T. Suhr, M

  12. Quantum resonance, Anderson localization and selective manipulations in molecular mixtures by ultrashort laser pulses

    CERN Document Server

    Floß, Johannes

    2011-01-01

    We demonstrate that the current laser technology used for field-free molecular alignment via a cascade of Raman rotational transitions allows for observing long-discussed non-linear quantum phenomena in the dynamics of the periodically kicked rotor. This includes the scaling of the absorbed energy near the conditions of quantum resonance and Anderson-like localization in the angular momentum. Based on these findings, we suggest a novel approach to tunable selective rotational excitation and alignment in a molecular mixture, using trains of short laser pulses. We demonstrate the efficiency of this approach by applying it to a mixture of two nitrogen isotopologues (14N2 and 15N2), and show that strong selectivity is possible even at room temperature.

  13. Localized Excitations from Localized Unitary Operators

    CERN Document Server

    Sivaramakrishnan, Allic

    2016-01-01

    Localized unitary operators are basic probes of locality and causality in quantum systems: localized unitary operators create localized excitations in entangled states. Working with an explicit form, we explore the properties of these operators in quantum mechanics and quantum field theory. We show that, unlike unitary operators, local non-unitary operators generically create non-local excitations. We present a local picture for quantum systems in which localized experimentalists can only act through localized Hamiltonian deformations, and therefore localized unitary operators. We demonstrate that localized unitary operators model certain quantum quenches exactly. We show how the Reeh-Schlieder theorem follows intuitively from basic properties of entanglement, non-unitary operators, and the local picture. We show that a recent quasi-particle picture for excited-state entanglement entropy in conformal field theories is not universal for all local operators. We prove a causality relation for entanglement entrop...

  14. Image transport through a disordered optical fiber mediated by transverse Anderson localization

    CERN Document Server

    Karbasi, Salman; Koch, Karl W; Hawkins, Thomas; Ballato, John; Mafi, Arash

    2013-01-01

    Transverse Anderson localization of light allows localized optical-beam-transport through a transversely-disordered and longitudinally-invariant medium. Its successful implementation in disordered optical fibers recently resulted in the simultaneous propagation of multiple beams in a single strand of an optical fiber, suggesting potential applications for spatial beam multiplexing and image transport. We present what is, to the best of our knowledge, the first demonstration of optical image transport using transverse Anderson localization of light. The image transport quality obtained in the polymer disordered optical fiber is comparable with or better than some of the best commercially available multicore imaging fibers with less pixelation and higher contrast. A proof-of-concept glass version is also evaluated and further optimization is discussed. Our results open the way to device-level implementation of the transverse Anderson localization of light with potential applications in biological and medical im...

  15. Wigner-like crystallization of Anderson-localized electron systems with low electron densities

    CERN Document Server

    Slutskin, A A; Pepper, M

    2002-01-01

    We consider an electron system under conditions of strong Anderson localization, taking into account interelectron long-range Coulomb repulsion. We establish that at sufficiently low electron densities and sufficiently low temperatures the Coulomb electron interaction brings about ordering of the Anderson-localized electrons into a structure that is close to an ideal (Wigner) crystal lattice, provided the dimension of the system is > 1. This Anderson-Wigner glass (AWG) is a new macroscopic electron state that, on the one hand, is beyond the conventional Fermi glass concept, and on the other hand, qualitatively differs from the known 'plain' Wigner glass (inherent in self-localized electron systems) in that the random slight electron displacements from the ideal crystal sites essentially depend on the electron density. With increasing electron density the AWG is found to turn into the plain Wigner glass or Fermi glass, depending on the width of the random spread of the electron levels. It is shown that the res...

  16. Observation of migrating transverse Anderson localizations of light in nonlocal media

    CERN Document Server

    Leonetti, Marco; Mafi, Arash; Conti, Claudio

    2014-01-01

    We report the experimental observation of the interaction and attraction of many localized modes in a two dimensional (2D) system realized by a disordered optical fiber supporting transverse Anderson localization. We show that a nonlocal optically nonlinear response of thermal origin alters the localization length by an amount determined by the optical power and also induces an action at a distance between the localized modes and their spatial migration. Evidence of a collective and strongly interacting regime is given.

  17. Spectral statistics for the discrete Anderson model in the localized regime

    CERN Document Server

    Germinet, François

    2010-01-01

    We report on recent results on the spectral statistics of the discrete Anderson model in the localized phase. Our results show, in particular, that, for the discrete Anderson Hamiltonian with smoothly distributed random potential at sufficiently large coupling, the limit of the level spacing distribution is that of i.i.d. random variables distributed according to the density of states of the random Hamiltonian. This text is a contribution to the proceedings of the conference "Spectra of Random Operators and Related Topics" held at Kyoto University, 02-04/12/09 organized by N. Minami and N. Ueki.

  18. Scaling analysis of transverse Anderson localization in a disordered optical waveguide

    CERN Document Server

    Abaie, Behnam

    2016-01-01

    The intention of this manuscript is twofold. First, the mode-width probability density function (PDF) is introduced as a powerful statistical tool to study and compare the transverse Anderson localization properties of a disordered one dimensional optical waveguide. Second, by analyzing the scaling properties of the mode-width PDF with the transverse size of the waveguide, it is shown that the mode-width PDF gradually converges to a terminal configuration. Therefore, it may not be necessary to study a real-sized disordered structure in order to obtain its statistical localization properties and the same PDF can be obtained for a substantially smaller structure. This observation is important because it can reduce the often demanding computational effort that is required to study the statistical properties of Anderson localization in disordered waveguides. Using the mode-width PDF, substantial information about the impact of the waveguide parameters on its localization properties is extracted. This information ...

  19. Anderson Localization for a Multi-Particle Quantum Graph

    OpenAIRE

    Sabri, Mostafa

    2012-01-01

    We study a multi-particle quantum graph with random potential. Taking the approach of multiscale analysis we prove exponential and strong dynamical localization of any order in the Hilbert-Schmidt norm near the spectral edge. Apart from the results on multi-particle systems, we also prove Lifshitz-type asymptotics for single-particle systems. This shows in particular that localization for single-particle quantum graphs holds under a weaker assumption on the random potential than previously kn...

  20. Snapshots of Anderson localization beyond the ensemble average

    Science.gov (United States)

    El-Dardiry, Ramy G. S.; Faez, Sanli; Lagendijk, Ad

    2012-09-01

    We study (1+1)D transverse localization of electromagnetic radiation at microwave frequencies directly by two-dimensional spatial scans. Since the longitudinal direction can be mapped onto time, our experiments provide unique snapshots of the buildup of localized waves. The evolution of the wave functions is compared with semianalytical calculations. Studies beyond ensemble averages reveal counterintuitive surprises. Oscillations of the wave functions are observed in space and explained in terms of a beating between the eigenstates.

  1. Controlling Anderson localization in disordered heterostrctures with Lévy-type distribution

    International Nuclear Information System (INIS)

    In this paper, we propose a disordered heterostructure in which the distribution of the refractive index of one of its constituents follows a Lévy-type distribution characterized by the exponent α. For the normal and oblique incidences, the effect of α variation on the localization length is investigated in different frequency ranges. As a result, the controllability of Anderson localization can be achieved by changing the exponent α in the disordered structure having heavy tailed distribution. (paper)

  2. Light focusing in the Anderson Regime

    CERN Document Server

    Leonetti, Marco; Mafi, Arash; Conti, Claudio

    2014-01-01

    Anderson localization is a regime in which diffusion is inhibited and waves (also electromagnetic waves) get localized. Here we exploit adaptive optics to achieve focusing in disordered optical fibers in the Anderson regime. By wavefront shaping and optimization, we observe the generation of a propagation invariant beam, where light is trapped transversally by disorder, and show that Anderson localizations can be also excited by extended speckled beams. We demonstrate that disordered fibers allow a more efficient focusing action with respect to standard fibers in a way independent of their length, because of the propagation invariant features and cooperative action of transverse localizations.

  3. Transverse Anderson Localization in Disordered Glass Optical Fibers: A Review

    Directory of Open Access Journals (Sweden)

    Arash Mafi

    2014-07-01

    Full Text Available Disordered optical fibers show novel waveguiding properties that can be used for various device applications, such as beam-multiplexed optical communications and endoscopic image transport. The strong transverse scattering from the transversely disordered optical fibers results in transversely confined beams that can freely propagate in the longitudinal direction, similar to conventional optical fibers, with the advantage that any point in the cross section of the fiber can be used for beam transport. For beam multiplexing and imaging applications, it is highly desirable to make the localized beam radius as small as possible. This requires large refractive index differences between the materials that define the random features in the disordered fiber. Here, disordered glass-air fibers are briefly reviewed, where randomly placed airholes in a glass matrix provide the sufficiently large refractive index difference of 0.5 for strong random transverse scattering. The main future challenge for the fabrication of an optimally disordered glass-air fibers is to increase the fill-fraction of airholes to nearly 50% for maximum beam confinement.

  4. Anderson localization of electrons in single crystals: Li (x) Fe(7)Se(8).

    Science.gov (United States)

    Ying, Tianping; Gu, Yueqiang; Chen, Xiao; Wang, Xinbo; Jin, Shifeng; Zhao, Linlin; Zhang, Wei; Chen, Xiaolong

    2016-02-01

    Anderson (disorder-induced) localization, proposed more than half a century ago, has inspired numerous efforts to explore the absence of wave diffusions in disordered media. However, the proposed disorder-induced metal-insulator transition (MIT), associated with the nonpropagative electron waves, has hardly been observed in three-dimensional (3D) crystalline materials, let alone single crystals. We report the observation of an MIT in centimeter-size single crystals of Li x Fe7Se8 induced by lattice disorder. Both specific heat and infrared reflectance measurements reveal the presence of considerable electronic states in the vicinity of the Fermi level when the MIT occurs, suggesting that the transition is not due to Coulomb repulsion mechanism. The 3D variable range hopping regime evidenced by electrical transport measurements at low temperatures indicates the localized nature of the electronic states on the Fermi level. Quantitative analyses of carrier concentration, carrier mobility, and simulated density of states (DOS) fully support that Li x Fe7Se8 is an Anderson insulator. On the basis of these results, we provide a unified DOS picture to explain all the experimental results, and a schematic diagram for finding other potential Anderson insulators. This material will thus serve as a rich playground for both theoretical and experimental investigations on MITs and disorder-induced phenomena. PMID:26989781

  5. Eigenmodal analysis of Anderson localization: Applications to photonic lattices and Bose-Einstein condensates

    Science.gov (United States)

    Ying, Guanwen; Kouzaev, Guennadi

    2016-10-01

    We present the eigenmodal analysis techniques enhanced towards calculations of optical and non-interacting Bose-Einstein condensate (BEC) modes formed by random potentials and localized by Anderson effect. The results are compared with the published measurements and verified additionally by the convergence criterion. In 2-D BECs captured in circular areas, the randomness shows edge localization of the high-order Tamm-modes. To avoid strong diffusive effect, which is typical for BECs trapped by speckle potentials, a 3-D-lattice potential with increased step magnitudes is proposed, and the BECs in these lattices are simulated and plotted.

  6. Coalescence of Anderson-localized modes at an exceptional point in 2D random media

    CERN Document Server

    Bachelard, Nicolas; Arlandis, Julien; Touzani, Rachid; Sebbah, Patrick

    2014-01-01

    In non-hermitian systems, the particular position at which two eigenstates coalesce under a variation of a parameter in the complex plane is called an exceptional point. A non-perturbative theory is proposed which describes the evolution of modes in 2D open dielectric systems when permittivity distribution is modified. We successfully test this theory in a 2D disordered system to predict the position in the parameter space of the exceptional point between two Anderson-localized states. We observe that the accuracy of the prediction depends on the number of localized states accounted for. Such an exceptional point is experimentally accessible in practically relevant disordered photonic systems

  7. Anderson localization and saturable nonlinearity in one-dimensional disordered lattices

    CERN Document Server

    Nguyen, Ba Phi

    2016-01-01

    We investigate numerically the propagation and the Anderson localization of plane waves in a one-dimensional lattice chain, where disorder and saturable nonlinearity are simultaneously present. Using a calculation scheme for solving the stationary discrete nonlinear Schr\\"{o}dinger equation in the fixed input case, the disorder-averaged logarithmic transmittance and the localization length are calculated in a numerically precise manner. The localization length is found to be a nonmonotonic function of the incident wave intensity, acquiring a minimum value at a certain finite intensity, due to saturation effects. For low incident intensities where the saturation effect is ineffective, the enhancement of localization due to Kerr-type nonlinearity occurs in a way similar to the case without saturation. For sufficiently high incident intensities, we find that the localization length is an increasing function of the incident wave intensity, which implies that localization is suppressed for stronger input intensiti...

  8. Scaling analysis of transverse Anderson localization in a disordered optical waveguide

    Science.gov (United States)

    Abaie, Behnam; Mafi, Arash

    2016-08-01

    The intention of this paper is twofold. First, the mode-width probability density function (PDF) is introduced as a powerful statistical tool to study and compare the transverse Anderson localization properties of a disordered quasi-one-dimensional optical waveguide. Second, by analyzing the scaling properties of the mode-width PDF with the transverse size of the waveguide, it is shown that the mode-width PDF gradually converges to a terminal configuration. Therefore, it may not be necessary to study a real-sized disordered structure in order to obtain its statistical localization properties and the same PDF can be obtained for a substantially smaller structure. This observation is important because it can reduce the often demanding computational effort that is required to study the statistical properties of Anderson localization in disordered waveguides. Using the mode-width PDF, substantial information about the impact of the waveguide parameters on its localization properties is extracted. This information is generally obscured when disordered waveguides are analyzed using other techniques such as the beam propagation method. As an example of the utility of the mode-width PDF, it is shown that the cladding refractive index can be used to quench the number of extended modes, hence improving the contrast in image transport properties of disordered waveguides.

  9. Anderson localization in high temperature QCD: background configuration properties and Dirac eigenmodes

    Science.gov (United States)

    Cossu, Guido; Hashimoto, Shoji

    2016-06-01

    We investigate the properties of the background gauge field configurations that act as disorder for the Anderson localization mechanism in the Dirac spectrum of QCD at high temperatures. We compute the eigenmodes of the Möbius domain-wall fermion operator on configurations generated for the SU(3) gauge theory with two flavors of fermions, in the temperature range [0.9, 1.9]T c . We identify the source of localization of the eigenmodes with gauge configurations that are self-dual and support negative fluctuations of the Polyakov loop P L , in the high temperature sea of P L ˜ 1. The dependence of these observations on the boundary conditions of the valence operator is studied. We also investigate the spatial overlap of the left-handed and right-handed projected eigenmodes in correlation with the localization and the corresponding eigenvalue. We discuss an interpretation of the results in terms of monopole-instanton structures.

  10. Probing Anderson localization of light by weak non-linear effects

    International Nuclear Information System (INIS)

    Breakdown of wave transport due to strong disorder is a universal phenomenon known as Anderson localization (AL). It occurs because of the macroscopic population of reciprocal multiple scattering paths, which in three dimensional systems happens at a critical scattering strength. Intensities on these random loops should thus be highly increased relative to those of a diffusive sample. In order to highlight localized modes of light, we exploit the optical nonlinearities of TiO2. Power dependent and spectrally resolved time of flight distribution measurements in transmission through slabs of TiO2 powders at various turbidities reveal that mostly long loops are affected by nonlinearities and that the deviations from diffusive transport observed at long times are due to these localized modes. Our data are a first step in the experimental investigation of the interplay between nonlinear effects and AL in 3D. (fast track communication)

  11. Anderson Localization in high temperature QCD: background configuration properties and Dirac eigenmodes

    CERN Document Server

    Cossu, Guido

    2016-01-01

    We investigate the properties of the background gauge field configurations that act as disorder for the Anderson localization mechanism in the Dirac spectrum of QCD at high temperatures. We compute the eigenmodes of the M\\"obius domain-wall fermion operator on configurations generated for the $SU(3)$ gauge theory with two flavors of fermions, in the temperature range $[0.9,1.9]T_c$. We identify the source of localization of the eigenmodes with gauge configurations that are self-dual and support negative fluctuations of the Polyakov loop $P_L$, in the high temperature sea of $P_L\\sim 1$. The dependence of these observations on the boundary conditions of the valence operator is studied. We also investigate the spatial overlap of the left-handed and right-handed projected eigenmodes in correlation with the localization and the corresponding eigenvalue. We discuss an interpretation of the results in terms of monopole-instanton structures.

  12. Metallic Transport and Anderson Localization on In Atomic Layers on Silicon

    Science.gov (United States)

    Yamazaki, Shiro; Hosomura, Yoshikazu; Matsuda, Iwao; Hobara, Rei; Hasegawa, Shuji

    2008-03-01

    Metallic temperature dependence of electrical resistance have not been observed except extremely limited number of examples[1] below 100K in atomic-scale low-dimensional metal systems due to Anderson localization. Si(111)-√7 x√3 -In surface reconstruction consist of 1.2 ML In atoms. According to ARPES study, the surface is 2D metal with the large Fermi wave number (kF=14nm-1) and the large electron density (4.6x10^14eV-1cm-2), leading to a low resistance [2]. By using variable-temperature micro-four-point probe method [3], low resistance and metallic transport was found down to 10 K. It is quantitatively explained by the ARPES result by using Boltzmann equation R2D=4π^2λm^*e^2kF^2 kBT. By introducing defect, it shows semiconducting temperature dependence of variable range hopping due to Anderson localization. [1]K. Lee, et al. , Nature 441, 65 (2006). [2]E. Rotenberg, et al. , Phys. Rev. Lett. 91, 246404 (2003). [3]T. Tanikawa, et al. , e-J. Surf. Sci. Nanotech. 1, 50 (2003)

  13. Statistical measurements of quantum emitters coupled to Anderson-localized modes in disordered photonic-crystal waveguides

    CERN Document Server

    Javadi, Alisa; Sapienza, Luca; Thyrrestrup, Henri; Lodahl, Peter

    2013-01-01

    Optical nanostructures have proven to be meritorious for tailoring the emission properties of quantum emitters. However, unavoidable fabrication imperfections may represent a nuisance. Quite remarkably, disorder offers new opportunities since light can be efficiently confined by random multiple scattering leading to Anderson localization. Here we investigate the effect of such disorder-induced cavities on the emission dynamics of single quantum dots embedded in disordered photonic-crystal waveguides. We present time-resolved measurements of both the total emission from Anderson-localized cavities and from single emitters that are coupled to the cavities. We observe both strongly inhibited and enhanced decay rates relative to the rate of spontaneous emission in a homogeneous medium. From a statistical analysis, we report an average Purcell factor of 2 in without any control on the quantum dot - cavity detuning. By spectrally tuning individual quantum dots into resonance with Anderson-localized modes, a maximum...

  14. Anderson localization in the multi-particle tight-binding model at low energies or with weak interaction

    CERN Document Server

    Ekanga, Trésor

    2012-01-01

    We consider the multi-particle lattice Anderson model with an i.i.d. random external potential and a short-range interaction. Using the multi-particle multiscale analysis (MPMSA) developed by Chulaevsky and Suhov (2009), we prove spectral localization for such Hamiltonians at low energies under the assumption of log-H\\"{o}lder continuity of the marginal probability distribution of the random potential. Under a stronger assumption of H\\"older continuity, Anderson localization for such systems at low energies was established earlier by Aizenman and Warzel (2009) with the help of the multi-particle Fractional-Moment Method.

  15. Nonreciprocal Anderson localization in one-dimensional ternary disordered media containing magnetized plasma layers

    International Nuclear Information System (INIS)

    This paper proposes a one-dimensional random structure composed of three types of alternating layers of dielectric and magnetized plasma materials. By employing the transfer matrix method, the localization lengths of the waves propagating in opposite directions are calculated. The numerical results demonstrate that nonreciprocal features appear in the averaged localization length and individual transmission resonances. However, in the short wavelength regime, the nonreciprocal behavior of the averaged localization length disappears, and the maximum of differential transmission decreases. The author investigates the effects of the external magnetic field, incident angle, collision frequency, and plasma density of the plasma layer on the reciprocal properties. The frequencies at which nonreciprocity occurs depend on the external magnetic field. Thus, it is possible to realize a photonic diode that is tunable with the external magnetic field. Also found is that for small angles of incidence no significant difference exists between the localization lengths of the forward and backward waves. There is a lower limit for the plasma density of the magnetized plasma layers to obtain nonreciprocal Anderson localization. As the collision frequency increases, the nonreciprocal features of the proposed random system survive. (papers)

  16. Dual nature of localization in guiding systems with randomly corrugated boundaries: Anderson-type versus entropic

    International Nuclear Information System (INIS)

    coexist in waveguide-like systems with randomly corrugated boundaries, specifically, the entropic localization and the one-dimensional Anderson (disorder-driven) localization. If the particular mode propagates across the rough segment ballistically, the Fabry–Pérot-type oscillations should be observed in the conductance, which are suppressed for the mode transferred in the Anderson-localized regime

  17. Numerical Renormalization Group Study of Probability Distributions for Local Fluctuations in the Anderson-Holstein and Holstein-Hubbard Models

    OpenAIRE

    Hewson, Alex C.; Bauer, Johannes

    2010-01-01

    We show that information on the probability density of local fluctuations can be obtained from a numerical renormalisation group calculation of a reduced density matrix. We apply this approach to the Anderson-Holstein impurity model to calculate the ground state probability density $\\rho(x)$ for the displacement $x$ of the local oscillator. From this density we can deduce an effective local potential for the oscillator and compare its form with that obtained from a semiclassical approximation...

  18. Itinerant-Localized Transitions in Magnetic Phases of the Periodic Anderson Model

    Science.gov (United States)

    Kubo, Katsunori

    To clarify the characteristics of Fermi-surface reconstruction, called Lifshitz transitions, in magnetic phases of f-electron materials, we investigate magnetically ordered states of the periodic Anderson model by applying the variational Monte Carlo method. As variational wavefunctions, we use the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, and ferromagnetic states. Around half-filling, we find an antiferromagnetic phase, and far away from half-filling, we find a ferromagnetic phase as the ground state. Inside both magnetic phases, Lifshitz transitions take place. At the Lifshitz transitions, the sizes of the ordered moments change. In order to understand the Lifshitz transitions further, we also analyze the f -electron contribution to the Fermi surface by evaluating the jump in the momentum distribution function at the Fermi momentum. Then, we find that, in the large ordered-moment states, the f -electron contribution to the Fermi surface becomes small. This observation clearly shows that these Lifshitz transitions are itinerant-localized transitions of the f electrons.

  19. Anderson localization on the Cayley tree: multifractal statistics of the transmission at criticality and off criticality

    Energy Technology Data Exchange (ETDEWEB)

    Monthus, Cecile; Garel, Thomas, E-mail: cecile.monthus@cea.fr [Institut de Physique Theorique, CNRS and CEA Saclay 91191 Gif-sur-Yvette Cedex (France)

    2011-04-08

    In contrast to finite dimensions where disordered systems display multifractal statistics only at criticality, the tree geometry induces multifractal statistics for disordered systems also off criticality. For the Anderson tight-binding localization model defined on a tree of branching ratio K = 2 with N generations, we consider the Miller-Derrida scattering geometry (1994 J. Stat. Phys. 75 357), where an incoming wire is attached to the root of the tree, and where K{sup N} outcoming wires are attached to the leaves of the tree. In terms of the K{sup N} transmission amplitudes t{sub j}, the total Landauer transmission is T {identical_to} {Sigma}{sub j}|t{sub j}|{sup 2}, so that each channel j is characterized by the weight w{sub j} = |t{sub j}|{sup 2}/T. We numerically measure the typical multifractal singularity spectrum f({alpha}) of these weights as a function of the disorder strength W and we obtain the following conclusions for its left termination point {alpha}{sub +}(W). In the delocalized phase W < W{sub c}, {alpha}{sub +}(W) is strictly positive {alpha}{sub +}(W) > 0 and is associated with a moment index q{sub +}(W) > 1. At criticality, it vanishes {alpha}{sub +}(W{sub c}) = 0 and is associated with the moment index q{sub +}(W{sub c}) = 1. In the localized phase W > W{sub c}, {alpha}{sub +}(W) = 0 is associated with some moment index q{sub +}(W) < 1. We discuss the similarities with the exact results concerning the multifractal properties of the directed polymer on the Cayley tree.

  20. Energy level statistics at the metal-insulator transition in the Anderson model of localization with anisotropic hopping

    OpenAIRE

    Milde, Frank; R{ö}mer, Rudolf A.

    1998-01-01

    Recently, a metal-insulator transition (MIT) was found in the anisotropic Anderson model of localization by transfer-matrix methods (TMM). This MIT has been also investigated by multifractal analysis (MFA) and the same critical disorders $W_c$ have been obtained within the accuracy of the data. We now employ energy level statistics (ELS) to further characterize the MIT. We find a crossover of the nearest-neighbor level spacing distribution $P(s)$ from GOE statistics at small disorder indicati...

  1. Forward approximation as a mean-field approximation for the Anderson and many-body localization transitions

    Science.gov (United States)

    Pietracaprina, Francesca; Ros, Valentina; Scardicchio, Antonello

    2016-02-01

    In this paper we analyze the predictions of the forward approximation in some models which exhibit an Anderson (single-body) or many-body localized phase. This approximation, which consists of summing over the amplitudes of only the shortest paths in the locator expansion, is known to overestimate the critical value of the disorder which determines the onset of the localized phase. Nevertheless, the results provided by the approximation become more and more accurate as the local coordination (dimensionality) of the graph, defined by the hopping matrix, is made larger. In this sense, the forward approximation can be regarded as a mean-field theory for the Anderson transition in infinite dimensions. The sum can be efficiently computed using transfer matrix techniques, and the results are compared with the most precise exact diagonalization results available. For the Anderson problem, we find a critical value of the disorder which is 0.9 % off the most precise available numerical value already in 5 spatial dimensions, while for the many-body localized phase of the Heisenberg model with random fields the critical disorder hc=4.0 ±0.3 is strikingly close to the most recent results obtained by exact diagonalization. In both cases we obtain a critical exponent ν =1 . In the Anderson case, the latter does not show dependence on the dimensionality, as it is common within mean-field approximations. We discuss the relevance of the correlations between the shortest paths for both the single- and many-body problems, and comment on the connections of our results with the problem of directed polymers in random medium.

  2. EFFECTS OF CONSTANT EXCITATION ON LOCAL BIFURCATION

    Institute of Scientific and Technical Information of China (English)

    WU Zhi-qiang; CHEN Yu-shu

    2006-01-01

    The effects of the constant excitation on the local bifurcation of the periodic solutions in the 1:2 internal resonant systems were analyzed based on the singularity theory. It is shown that the constant excitation make influence only when there exist some nonlinear terms, in the oscillator with lower frequency. Besides acting as main bifurcation parameter, the constant excitation, together with coefficients of some nonlinear terms,may change the values of unfolding parameters and the type of the bifurcation. Under the non-degenerate cases, the effect of the third order terms can be neglected.

  3. Numerical renormalization group study of probability distributions for local fluctuations in the Anderson-Holstein and Holstein-Hubbard models.

    Science.gov (United States)

    Hewson, Alex C; Bauer, Johannes

    2010-03-24

    We show that information on the probability density of local fluctuations can be obtained from a numerical renormalization group calculation of a reduced density matrix. We apply this approach to the Anderson-Holstein impurity model to calculate the ground state probability density ρ(x) for the displacement x of the local oscillator. From this density we can deduce an effective local potential for the oscillator and compare its form with that obtained from a semiclassical approximation as a function of the coupling strength. The method is extended to the infinite dimensional Holstein-Hubbard model using dynamical mean field theory. We use this approach to compare the probability densities for the displacement of the local oscillator in the normal, antiferromagnetic and charge ordered phases.

  4. Giant fluctuations of local magnetoresistance of organic spin valves and the non-Hermitian 1D Anderson model.

    Science.gov (United States)

    Roundy, R C; Nemirovsky, D; Kagalovsky, V; Raikh, M E

    2014-06-01

    Motivated by recent experiments, where the tunnel magnetoresitance (TMR) of a spin valve was measured locally, we theoretically study the distribution of TMR along the surface of magnetized electrodes. We show that, even in the absence of interfacial effects (like hybridization due to donor and acceptor molecules), this distribution is very broad, and the portion of area with negative TMR is appreciable even if on average the TMR is positive. The origin of the local sign reversal is quantum interference of subsequent spin-rotation amplitudes in the course of incoherent transport of carriers between the source and the drain. We find the distribution of local TMR exactly by drawing upon formal similarity between evolution of spinors in time and of the reflection coefficient along a 1D chain in the Anderson model. The results obtained are confirmed by the numerical simulations. PMID:24949781

  5. Breakdown of Anderson localization in the transport of Bose-Einstein condensates through one-dimensional disordered potentials

    Science.gov (United States)

    Dujardin, Julien; Engl, Thomas; Schlagheck, Peter

    2016-01-01

    We study the transport of an interacting Bose-Einstein condensate through a 1D correlated disorder potential. We use for this purpose the truncated Wigner method, which is, as we show, corresponding to the diagonal approximation of a semiclassical van Vleck-Gutzwiller representation of this many-body transport process. We also argue that semiclassical corrections beyond this diagonal approximation are vanishing under disorder average, thus confirming the validity of the truncated Wigner method in this context. Numerical calculations show that, while for weak atom-atom interaction strengths Anderson localization is preserved with a slight modification of the localization length, for larger interaction strengths a crossover to a delocalized regime exists due to inelastic scattering. In this case, the transport is fully incoherent.

  6. Observation of Replica Symmetry Breaking in the 1D Anderson Localization Regime in an Erbium-Doped Random Fiber Laser

    CERN Document Server

    Gomes, Anderson S L; Pincheira, Pablo I R; Moura, André L; Gagné, Mathieu; Kashyap, Raman; Raposo, Ernesto P; de Araújo, Cid B

    2016-01-01

    The analogue of the paramagnetic to spin-glass phase transition in disordered magnetic systems, leading to the phenomenon of replica symmetry breaking, has been recently demonstrated in a two-dimensional random laser consisting of an organic-based amorphous solid-state thin film. We report here the first demonstration of replica symmetry breaking in a one-dimensional photonic system consisting of an erbium-doped random fiber laser operating in the continuous-wave regime based on a unique random fiber grating system, which plays the role of the random scatterers and operates in the Anderson localization regime. The clear transition from a photonic paramagnetic to a photonic spin glass phase, characterized by the probability distribution function of the Parisi overlap, was verified and characterized. In this unique system, the radiation field interacts only with the gain medium, and the fiber grating, which provides the disordered feedback mechanism, does not interfere with the pump.

  7. Anderson wall and Bloch oscillations in molecular rotation

    CERN Document Server

    Floß, Johannes

    2014-01-01

    We describe a universal behavior of linear molecules excited by a periodic train of short laser pulses under quantum resonance conditions. In a rigid rotor the resonance causes an unlimited ballistic growth of the angular momentum. We show that the centrifugal distortion of rotating molecules eventually halts the growth, by causing Anderson localization beyond a critical value of the angular momentum -- the Anderson wall. Its position solely depends on the molecular rotational constants and lies in the range of a few tens of hbar. Below the wall, rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. We suggest optical experiments capable of observing the rotational Anderson wall and Bloch oscillations at ambient conditions with the help of existing laser technology.

  8. Anderson wall and BLOCH oscillations in molecular rotation.

    Science.gov (United States)

    Floß, Johannes; Averbukh, Ilya Sh

    2014-07-25

    We describe a universal behavior of linear molecules excited by a periodic train of short laser pulses under quantum resonance conditions. In a rigid rotor, the resonance causes an unlimited ballistic growth of the angular momentum. We show that the centrifugal distortion of rotating molecules eventually halts the growth, by causing Anderson localization beyond a critical value of the angular momentum--the Anderson wall. Its position solely depends on the molecular rotational constants and lies in the range of a few tens of ℏ. Below the wall, rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. We suggest optical experiments capable of observing the rotational Anderson wall and Bloch oscillations at near-ambient conditions with the help of existing laser technology.

  9. Anderson localization of light in a colloidal suspension (TiO2@silica).

    Science.gov (United States)

    Jimenez-Villar, Ernesto; da Silva, Iran F; Mestre, Valdeci; de Oliveira, Paulo C; Faustino, Wagner M; de Sá, Gilberto F

    2016-06-01

    In recent years, there has been dramatic progress in the photonics field in disordered media, ranging from applications in solar collectors, photocatalyzers, random lasing, and other novel photonic functions, to investigations into fundamental topics, such as light confinement and other phenomena involving photon interactions. This paper reports several pieces of experimental evidence of localization transition in a strongly disordered scattering medium composed of a colloidal suspension of core-shell nanoparticles (TiO2@silica) in ethanol solution. We demonstrate the crossover from a diffusive transport to a localization transition regime as the nanoparticle concentration is increased, and that an enhanced absorption effect arises at localization transition.

  10. Anderson localization and its ramifications disorder, phase coherence and electron correlations

    CERN Document Server

    Kettemann, S

    2003-01-01

    The phenomenon of localization of the electronic wave function in a random medium can be regarded as the key manifestation of quantum coherence in a condensed matter system. As one of the most remarkable phenomena in condensed matter physics discovered in the 20th century, the localization problem is an indispensable part of the theory of the quantum Hall effects and rivals superconductivity in its significance as a manifestation of quantum coherence at a macroscopic scale. The present volume, written by some of the leading experts in the field, is intended to highlight some of the recent progress in the field of localization, with particular emphasis on the effect of interactions on quantum coherence. The chapters are written in textbook style and should serve as a reliable and thorough introduction for advanced students or researchers already working in the field of mesoscopic physics.

  11. Quantum entanglement of localized excited states at finite temperature

    OpenAIRE

    Caputa, Pawel; Simón, Joan; Štikonas, Andrius(School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, King’s Buildings, Edinburgh, EH9 3FD, U.K.); Takayanagi, Tadashi

    2015-01-01

    In this work we study the time evolutions of (Renyi) entanglement entropy of locally excited states in two dimensional conformal field theories (CFTs) at finite temperature.We consider excited states created by acting with local operators on thermal states and give both field theoretic and holographic calculations. In free field CFTs, we find that the growth of Renyi entanglement entropy at finite temperature is reduced compared to the zero temperature result by a small quantity proportional ...

  12. Quantum dimensions from local operator excitations in the Ising model

    CERN Document Server

    Caputa, Pawel

    2016-01-01

    We compare the time evolution of entanglement measures after local operator excitation in the critical Ising model with predictions from conformal field theory. For the spin operator and its descendants we find that Renyi entropies of a block of spins increase by a constant that matches the logarithm of the quantum dimension of the conformal family. However, for the energy operator we find a small constant contribution that differs from the conformal field theory answer equal to zero. We argue that the mismatch is caused by the subtleties in the identification between the local operators in conformal field theory and their lattice counterpart. Our results indicate that evolution of entanglement measures in locally excited states not only constraints this identification, but also can be used to extract non-trivial data about the conformal field theory that governs the critical point. We generalize our analysis to the Ising model away from the critical point, states with multiple local excitations, as well as t...

  13. Localized helium excitations in 4He_N-benzene clusters

    CERN Document Server

    Huang, P; Huang, Patrick

    2003-01-01

    We compute ground and excited state properties of small helium clusters 4He_N containing a single benzene impurity molecule. Ground-state structures and energies are obtained for N=1,2,3,14 from importance-sampled, rigid-body diffusion Monte Carlo (DMC). Excited state energies due to helium vibrational motion near the molecule surface are evaluated using the projection operator, imaginary time spectral evolution (POITSE) method. We find excitation energies of up to ~23 K above the ground state. These states all possess vibrational character of helium atoms in a highly anisotropic potential due to the aromatic molecule, and can be categorized in terms of localized and collective vibrational modes. These results appear to provide precursors for a transition from localized to collective helium excitations at molecular nanosubstrates of increasing size. We discuss the implications of these results for analysis of anomalous spectral features in recent spectroscopic studies of large aromatic molecules in helium clu...

  14. Linear and Non-linear Rabi Oscillations of a Two-Level System Resonantly Coupled to an Anderson-Localized Mode

    CERN Document Server

    Bachelard, Nicolas; Sebbah, Patrick; Vanneste, Christian

    2014-01-01

    We use time-domain numerical simulations of a two-dimensional (2D) scattering system to study the interaction of a collection of emitters resonantly coupled to an Anderson-localized mode. For a small electric field intensity, we observe the strong coupling between the emitters and the mode, which is characterized by linear Rabi oscillations. Remarkably, a larger intensity induces non-linear interaction between the emitters and the mode, referred to as the dynamical Stark effect, resulting in non-linear Rabi oscillations. The transition between both regimes is observed and an analytical model is proposed which accurately describes our numerical observations.

  15. Quantum Entanglement of Localized Excited States at Finite Temperature

    CERN Document Server

    Caputa, Pawel; Stikonas, Andrius; Takayanagi, Tadashi

    2014-01-01

    In this work we study the time evolutions of (Renyi) entanglement entropy of locally excited states in two dimensional conformal field theories (CFTs) at finite temperature. We consider excited states created by acting with local operators on thermal states and give both field theoretic and holographic calculations. In free field CFTs, we find that the growth of Renyi entanglement entropy at finite temperature is reduced compared to the zero temperature result by a small quantity proportional to the width of the localized excitations. On the other hand, in finite temperature CFTs with classical gravity duals, we find that the entanglement entropy approaches a characteristic value at late time. This behaviour does not occur at zero temperature. We also study the mutual information between the two CFTs in the thermofield double (TFD) formulation and give physical interpretations of our results.

  16. Quantum entanglement of localized excited states at finite temperature

    Science.gov (United States)

    Caputa, Pawel; Simón, Joan; Štikonas, Andrius; Takayanagi, Tadashi

    2015-01-01

    In this work we study the time evolutions of (Renyi) entanglement entropy of locally excited states in two dimensional conformal field theories (CFTs) at finite temperature. We consider excited states created by acting with local operators on thermal states and give both field theoretic and holographic calculations. In free field CFTs, we find that the growth of Renyi entanglement entropy at finite temperature is reduced compared to the zero temperature result by a small quantity proportional to the width of the localized excitations. On the other hand, in finite temperature CFTs with classical gravity duals, we find that the entanglement entropy approaches a characteristic value at late time. This behaviour does not occur at zero temperature. We also study the mutual information between the two CFTs in the thermofield double (TFD) formulation and give physical interpretations of our results.

  17. Transverse Chiral Optical Forces by Locally Excited Surface Plasmon Polaritons

    CERN Document Server

    Alizadeh, M H

    2015-01-01

    Recently the new concepts of transverse spin angular momentum and Belinfante spin momentum of evanescent waves have drawn considerable attention. Here, we investigate these novel physical properties of electromagnetic fields in the context of locally excited surface plasmon polaritons. We demonstrate, both analytically and numerically, that locally excited surface plasmon polaritons possess transverse spin angular momentum and Belinfante momentum with rich and non-trivial characteristics. We also show that the transverse spin angular momentum of locally excited surface plasmon polaritons leads to the emergence of transverse chiral forces in opposite directions for chiral objects of different handedness. The magnitude of such a transverse force is comparable to the optical gradient force and scattering forces. This finding may pave the way for realization of optical separation of chiral biomolecules.

  18. Efficiency of local surface plasmon polariton excitation on ridges

    DEFF Research Database (Denmark)

    Radko, I.P.; Bozhevolnyi, S.I.; Brucoli, G.;

    2008-01-01

    The issue of efficient local coupling of light into surface plasmon polariton (SPP) modes is an important concern in miniaturization of plasmonic components. Here we present experimental and numerical investigations of efficiency of local SPP excitation on gold ridges of rectangular profile...... positioned on a gold film. The excitation is accomplished by illuminating the metal surface normally with a focused laser beam. Wavelength dependence and dependence of the efficiency on geometrical parameters of ridges are examined. Using leakage radiation microscopy, the efficiency of ˜20% is demonstrated...

  19. Entanglement in Anderson Nanoclusters

    CERN Document Server

    Samuelsson, Peter

    2007-01-01

    We investigate the two-particle spin entanglement in magnetic nanoclusters described by the periodic Anderson model. An entanglement phase diagram is obtained, providing a novel perspective on a central property of magnetic nanoclusters, namely the temperature dependent competition between local Kondo screening and nonlocal Ruderman-Kittel-Kasuya-Yoshida spin ordering. We find that multiparticle entangled states are present for finite magnetic field as well as in the mixed valence regime and away from half filling. Our results emphasize the role of charge fluctuations.

  20. Novel Localized Excitations of Nonlinear Coupled Scalar Fields

    Institute of Scientific and Technical Information of China (English)

    ZHU Ren-Gui; LI Jin-Hua; WANG An-Min; WU Huang-Jiao

    2008-01-01

    Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ4 model are presented. Simultaneously, inspired by the new solutions of the famous φ4 model recently proposed by Jia, Huang and Lou, five kinds of new localized excitations of the nonlinear coupled scalar field (NCSF) system are obtained.

  1. Local excitation of surface plasmon polaritons in random surface nanostructures

    DEFF Research Database (Denmark)

    Bozhevolnyi, S.I.; Volkov, V.S.; Boltasseva, Alexandra;

    2003-01-01

    We investigate local excitation of surface plasmon polaritons (SPPs) at a 55-nm-thick gold layer covered with randomly located scatterers (density similar to75 mum(-2)) by using an uncoated fiber tip of a near-field optical microscope as a radiation source and detecting the radiation scattered...

  2. Causal Evolutions of Bulk Local Excitations from CFT

    CERN Document Server

    Goto, Kanato; Takayanagi, Tadashi

    2016-01-01

    Bulk localized excited states in an AdS spacetime can be constructed from Ishibashi states with respect to the global conformal symmetry in the dual CFT. We study boundary two point functions of primary operators in the presence of bulk localized excitations in two dimensional CFTs. From two point functions in holographic CFTs, we observe causal propagations of radiations when the mass of dual bulk scalar field is close to the BF bound. This behavior for holographic CFTs is consistent with the locality and causality in classical gravity duals. We also show that this cannot be seen in free fermion CFTs. Moreover, we find that the short distance behavior of two point functions is universal and obeys the relation which generalizes the first law of entanglement entropy.

  3. Localized excitations in superconducting point contacts: probing the Andreev doublet

    International Nuclear Information System (INIS)

    The Josephson effect describes the coherent coupling between superconductors and the resulting supercurrent. Microscopically, it arises from the existence of discrete quasiparticle states, localized at the weak link, the Andreev bound states. They come in doublets in each conduction channel of the weak link, with energies symmetric about the Fermi energy and opposite supercurrents. Each Andreev doublet gives rise to four states: the ground state |-> and the excited state |+>, with even parity, and the excited odd states |↑> and |↓>. Is it possible to address and control Andreev doublets? This thesis describes two sets of experiments designed to answer this question using the most basic Josephson element, a one-atom contact between two superconducting electrodes. In a first experiment, we have observed and characterized the excited odd states |↑> and |↓>. As expected for a spin-degenerate system, they do not carry supercurrent. In this experiment the excitation was uncontrolled and resulted from trapping of spurious quasiparticles. We have measured the lifetime of the odd states: under some condition, it is found to exceed 100 μs. The second experiment is a photon-absorption spectroscopy of the Andreev doublet. It was performed by using a Josephson junction as an integrated on-chip microwave emitter and detector. The observed Andreev transitions correspond to excitation from the ground state |->to the excited even state |+>, and are well accounted for by our quantum model. This result opens the way to coherent manipulation of this two level system. The direct observation of the excited Andreev state, either by quasiparticle-injection or photon-absorption, strongly supports the mesoscopic theory of the Josephson effect. It shows that in addition to the phase difference, each channel of a Josephson weak link possesses an internal fermionic degree of freedom. It could be used to code information in a novel type of superconducting qubit. (author)

  4. Enhanced Electromagnetic Chirality by Locally Excited Surface Plasmon Polaritons

    CERN Document Server

    Alizadeh, M H

    2015-01-01

    The possibility to enhance chiral light-matter interactions through plasmonic nanostructures provides entirely new opportunities for greatly improving the detection limits of chiroptical spectroscopies down to the single molecule level. The most pronounced of these chiral interactions occur in the ultraviolet (UV) range of the electromagnetic spectrum, which is difficult to access with conventional localized plasmon resonance based sensors. Although Surface Plasmon Polaritons (SPPs) on noble metal films can sustain resonances in the desired spectral range, their transverse magnetic nature has been an obstacle for enhancing chiroptical effects. Here we demonstrate, both analytically and numerically, that SPPs excited by near-field sources can exhibit rich and non-trivial chiral characteristics. In particular, we show that the excitation of SPPs by a chiral source not only results in a locally enhanced optical chirality but also achieves manifold enhancement of net optical chirality. Our finding that SPPs facil...

  5. Discrete Anderson Speckle

    CERN Document Server

    Kondakci, H Esat; Saleh, Bahaa E A

    2016-01-01

    When a disordered array of coupled waveguides is illuminated with an extended coherent optical field, discrete speckle develops: partially coherent light with a granular intensity distribution on the lattice sites. The same paradigm applies to a variety of other settings in photonics, such as imperfectly coupled resonators or fibers with randomly coupled cores. Through numerical simulations and analytical modeling, we uncover a set of surprising features that characterize discrete speckle in one- and two-dimensional lattices known to exhibit transverse Anderson localization. Firstly, the fingerprint of localization is embedded in the fluctuations of the discrete speckle and is revealed in the narrowing of the spatial coherence function. Secondly, the transverse coherence length (or speckle grain size) is frozen during propagation. Thirdly, the axial coherence depth is independent of the axial position, thereby resulting in a coherence voxel of fixed volume independently of position. We take these unique featu...

  6. Anderson Anderson,美国

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Design Concept: "Wuhan Blue Prototype" A highlight of the concept is its integration with the local neighbourhood.The building and site planning will be coordinated with the existing planned facilities with a great lawn leading up from the community entrance toward a community gym and shopping centre. The Blue Sky Prototype itself is planned as an open-air network of pedestrian streets and public gardens at ground level winding up to vertical floor plates. The front doors of each unit will open to wide open-air streets and the sky.

  7. Relativistic Coulomb excitation within Time Dependent Superfluid Local Density Approximation

    CERN Document Server

    Stetcu, I; Bulgac, A; Magierski, P; Roche, K J

    2014-01-01

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus $^{238}$U. The approach is based on Superfluid Local Density Approximation (SLDA) formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We have computed the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance and giant quadrupole modes were excited during the process. The one body dissipation of collective dipole modes is shown to lead a damping width $\\Gamma_\\downarrow \\approx 0.4$ MeV and the number of pre-equilibrium neutrons emitted has been quantified.

  8. Excitations and management of the nonlinear localized gap modes

    Indian Academy of Sciences (India)

    Bishwajyoti Dey

    2015-11-01

    We discuss about the theory of nonlinear localized excitations, such as soliton and compactons in the gap of the linear spectrum of the nonlinear systems. We show how the gap originates in the linear spectrum using examples of a few systems, such as nonlinear lattices, Bose–Einstein condensates in optical lattice and systems represented by coupled nonlinear evolution equations. We then analytically show the excitation of solitons and compacton-like solutions in the gap of the linear spectrum of a system of coupled Korteweg–de Vries (KdV) equations with linear and nonlinear dispersions. Finally, we discuss about the theory of Feshbach resonance management and dispersion management of the soliton solutions.

  9. Damage Localization of Offshore Platforms Under Ambient Excitation

    Institute of Scientific and Technical Information of China (English)

    杨和振; 李华军; 王树青

    2003-01-01

    In this paper Nondestructive Damage Detection (NDD) for offshore platforms is investigated under operational conditions. As is known, there is no easy way to measure ambient excitation, so damage detection methods based on ambient excitation have become very vital for the Structural Health Monitoring (SHM) of offshore platforms. The modal parameters (natural frequencies, damping ratios and mode shapes) are identified from structural response data with the Natural Excitation Technique (NExT) in conjunction with the Eigensystem Realization Algorithm (ERA). A new method of damage detection is presented, which utilizes the invariance property of element modal strain energy. This method is to assign element modal strain energy to two parts, and defines two damage detection indicators. One is compression modal strain energy change ratio (CMSECR); the other is flexural modal strain energy change ratio (FMSECR). The present modal strain energy is obtained by incomplete modal shape and structural stiffness matrix. Structural health monitoring is thus accomplished via monitoring the elemental CMSECR and FMSECR. Several damage cases are simulated by an offshore platform numerical model, and presented to illustrate the utility of the proposed method. According to the damage localization results, the proposed method is shown to be effective and precise for complex structural damage detection.

  10. Local excitation and collection in polymeric fluorescent microstructures

    Science.gov (United States)

    Henrique, Franciele Renata; Mendonca, Cleber Renato

    2016-04-01

    Integrated photonics has gained attention in recent years due to its wide range of applications which span from biology to optical communications. The use of polymer-based platforms for photonic devices is of great interest because organic compounds can be easily incorporated to polymers, enabling modifications to the system physical properties. The two-photon polymerization technique has emerged as an interesting tool for the production of three-dimensional polymeric microstructures. However, for their further incorporation in photonic devices it is necessary to develop methods to perform optical excitation and signal collection on such microstructures. With such purpose, we demonstrate approaches to perform local excitation and collection in polymeric microstructures doped with fluorescent dyes, employing tapered fibers. The obtained results indicate that fiber tapers are suitable to couple light in and out of fluorescent polymeric microstructures, paving the way for their incorporation in photonic devices. We also show that microstructures doped with more than one dye can be used as built-in broadband light sources to photonic circuits and their emission spectrum can be tuned by the right choice of the excitation position.

  11. The London-Anderson-Englert-Brout-Higgs-Guralnik-Hagen-Kibble-Weinberg mechanism and Higgs boson reveal the unity and future excitement of physics

    CERN Document Server

    Allen, Roland E

    2013-01-01

    The particle recently discovered by the CMS and ATLAS collaborations at CERN is almost certainly a Higgs boson, fulfilling a quest that can be traced back to three seminal high energy papers of 1964, but which is intimately connected to ideas in other areas of physics that go back much further. One might oversimplify the history of the features which (i) give mass to the W and Z particles that mediate the weak nuclear interaction, (ii) effectively break gauge invariance, (iii) eliminate physically unacceptable Nambu-Goldstone bosons, and (iv) give mass to fermions (like the electron) by collectively calling them the London-Anderson-Englert-Brout-Higgs-Guralnik-Hagen-Kibble-Weinberg mechanism. More important are the implications for the future: a Higgs boson appears to point toward supersymmetry, since new physics is required to protect its mass from enormous quantum corrections, while the discovery of neutrino masses seems to point toward grand unification of the nongravitational forces.

  12. Parametric excitation of multiple resonant radiations from localized wavepackets

    CERN Document Server

    Conforti, Matteo; Mussot, Arnaud; Kudlinski, Alexandre

    2015-01-01

    Fundamental physical phenomena such as laser-induced ionization, driven quantum tunneling, Faraday waves, Bogoliubov quasiparticle excitations, and the control of new states of matter rely on time-periodic driving of the system. A remarkable property of such driving is that it can induce the localized (bound) states to resonantly couple to the continuum. Therefore experiments that allow for enlightening and controlling the mechanisms underlying such coupling are of paramount importance. We implement such an experiment in a special fiber optics system characterized by a dispersion oscillating along the propagation coordinate, which mimics "time". The quasi-momentum associated with such periodic perturbation is responsible for the efficient coupling of energy from the localized wave-packets sustained by the fiber nonlinearity into free-running linear dispersive waves (continuum), at multiple resonant frequencies. Remarkably, the observed resonances can be explained by means of a unified approach, regardless of ...

  13. Probing the Locality of Excited States with Linear Algebra.

    Science.gov (United States)

    Etienne, Thibaud

    2015-04-14

    This article reports a novel theoretical approach related to the analysis of molecular excited states. The strategy introduced here involves gathering two pieces of physical information, coming from Hilbert and direct space operations, into a general, unique quantum mechanical descriptor of electronic transitions' locality. Moreover, the projection of Hilbert and direct space-derived indices in an Argand plane delivers a straightforward way to visually probe the ability of a dye to undergo a long- or short-range charge-transfer. This information can be applied, for instance, to the analysis of the electronic response of families of dyes to light absorption by unveiling the trend of a given push-pull chromophore to increase the electronic cloud polarization magnitude of its main transition with respect to the size extension of its conjugated spacer. We finally demonstrate that all the quantities reported in this article can be reliably approximated by a linear algebraic derivation, based on the contraction of detachment/attachment density matrices from canonical to atomic space. This alternative derivation has the remarkable advantage of a very low computational cost with respect to the previously used numerical integrations, making fast and accurate characterization of large molecular systems' excited states easily affordable.

  14. Probing the Locality of Excited States with Linear Algebra.

    Science.gov (United States)

    Etienne, Thibaud

    2015-04-14

    This article reports a novel theoretical approach related to the analysis of molecular excited states. The strategy introduced here involves gathering two pieces of physical information, coming from Hilbert and direct space operations, into a general, unique quantum mechanical descriptor of electronic transitions' locality. Moreover, the projection of Hilbert and direct space-derived indices in an Argand plane delivers a straightforward way to visually probe the ability of a dye to undergo a long- or short-range charge-transfer. This information can be applied, for instance, to the analysis of the electronic response of families of dyes to light absorption by unveiling the trend of a given push-pull chromophore to increase the electronic cloud polarization magnitude of its main transition with respect to the size extension of its conjugated spacer. We finally demonstrate that all the quantities reported in this article can be reliably approximated by a linear algebraic derivation, based on the contraction of detachment/attachment density matrices from canonical to atomic space. This alternative derivation has the remarkable advantage of a very low computational cost with respect to the previously used numerical integrations, making fast and accurate characterization of large molecular systems' excited states easily affordable. PMID:26574379

  15. Optical Excitation of Carbon Nanotubes Drives Localized Diazonium Reactions.

    Science.gov (United States)

    Powell, Lyndsey R; Piao, Yanmei; Wang, YuHuang

    2016-09-15

    Covalent chemistries have been widely used to modify carbon nanomaterials; however, they typically lack the precision and efficiency required to directly engineer their optical and electronic properties. Here, we show, for the first time, that visible light which is tuned into resonance with carbon nanotubes can be used to drive their functionalization by aryldiazonium salts. The optical excitation accelerates the reaction rate 154-fold (±13) and makes it possible to significantly improve the efficiency of covalent bonding to the sp(2) carbon lattice. Control experiments suggest that the reaction is dominated by a localized photothermal effect. This light-driven reaction paves the way for precise nanochemistry that can directly tailor carbon nanomaterials at the optical and electronic levels.

  16. Development of a radio frequency excited local impedance probe

    International Nuclear Information System (INIS)

    Local void fraction measurements were made with a Karlsruhe type impedance probe. The probe was operated at radiofrequency to minimize sensitivity to liquid phase resistivity. Two types of signal thresholding were used: level and derivative. A dual beam X-ray system was used as a calibration standard for the radio frequency excited impedance probe. Calibration was performed in vertical air/water flows. Derivative thresholding was found to be preferable to level thresholding, however, in both schemes hydrodynamic and surface tension effects were observed below a liquid superficial velocity of 0.5 m/s. Table salt (NaCl) was added to the water to verify the probe's response to changing water resistivity. Derivative thresholding appeared to work quite well but level thresholding was found to be inadequate due to the change in capacitance. (orig.)

  17. Controlling the localization and migration of optical excitation

    Science.gov (United States)

    Andrews, David L.; Bradshaw, David S.

    2012-09-01

    possibilities for technical application is emerging. For example, applications can be envisaged for new forms of all-optical switching and transistor action. There is also interest in engaging with the interplay of optical excitation and local nanoscale force, exploiting local responses to changes in dispersion forces, accompanying molecular energy transfer.

  18. Anderson localisation in laser kicked molecules

    CERN Document Server

    Floß, Johannes; Averbukh, Ilya Sh

    2013-01-01

    The paper explores the prospects of observing the phenomenon of dynamical Anderson localisation via non-resonant Raman-type rotational excitation of molecules by periodic trains of short laser pulses. We define conditions for such an experiment, and show that current femtosecond technology used for non-adiabatic laser alignment of linear molecules is sufficient for this task. Several observables which can serve as indicator for Anderson localisation are suggested for measurement, and the influence of experimental limitations imposed by laser intensity noise, finite pulse duration, limited number of pulses in a train, and thermal effects is analysed.

  19. New localized excitations in a (2+1)-dimensional Broer-Kaup system

    Institute of Scientific and Technical Information of China (English)

    Bai Cheng-Lin; Liu Xi-Qiang; Zhao Hong

    2005-01-01

    Starting with the extended homogeneous balance method and a variable separation approach, a general variable separation solution of the Broer-Kaup system is derived. In addition to the usual localized coherent soliton excitations like dromions, lumps, rings, breathers, instantons, oscillating soliton excitations, peakon and fractal localized solutions,some new types of localized excitations, such as compacton and folded excitations, are obtained by introducing appropriate lower-dimensional piecewise smooth functions and multiple-valued functions, and some interesting novel features of these structures are revealed.

  20. Efficiency of local surface plasmon polariton excitation on ridges

    DEFF Research Database (Denmark)

    Radko, Ilya; Bozhevolnyi, Sergey I.; Boltasseva, Alexandra;

    2008-01-01

    We investigate experimentally and numerically the efficiency of surface plasmon polariton excitation by a focused laser beam using gold ridges. The dependence of the efficiency on geometrical parameters of ridges and wavelength dependence are examined. The experimental measurements accomplished...

  1. The Anderson Quin Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.H.; Bilbow, W.M.

    1993-03-18

    The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since this grant was limited to 2150 man hours, we could not expect to achieve all the objectives within the allotted period of work. However, the most relevant program objectives have been completed as reported here. The analysis generally confirms the results originally estimated in my paper on the subject. (Ref. 2) Further optimizations should show even higher efficiencies. The Anderson Quin Cycle (US Patent applied for) basically consists of 5 elements in the power cycle: A refrigeration system to cool and clean the inlet air before it enters the compressor that supplies air for the gas turbine; a gas turbine consisting of a compressor, combustor, and turbine; a steam boiler and steam turbine system using the heat from the exhaust gas out of the gas turbine; a vapor turbine cycle, which utilizes the condensed heat from the exhaust of the steam turbine and the exhaust gas heat leaving the steam boiler to operate a vapor turbine cycle which utilizes another fluid than water, in this case isobutane; and the fifth element consists of a gas cooler and heat pump system, which removes the heat from the exhaust gas to lower its temperature essentially to atmospheric temperature, and at the same time permits treatment of the exhaust gas to remove acid components such as sulfur dioxide and nitrogen oxides. Current industry accepted component characteristics were incorporated in the performance analysis of the overall cycle, ensuring accurate and meaningful operating predictions. The characteristics and performance of each of the elements are described. The thermal efficiency of the optimized calculated Anderson Quin Cycle is 62 percent.

  2. Local excitation of surface plasmon polaritons by second-harmonic generation in crystalline organic nanofibers

    DEFF Research Database (Denmark)

    Skovsen, Esben; Søndergaard, Thomas; Fiutowski, Jacek;

    2012-01-01

    Coherent local excitation of surface plasmon polaritons (SPPs) by second-harmonic generation (SHG) in aligned crystalline organic functionalized para-phenylene nanofibers deposited on a thin silver film is demonstrated. The excited SPPs are characterized using angle-resolved leakage radiation...

  3. Localization of atomic excitation beyond the diffraction limit using electromagnetically induced transparency

    Science.gov (United States)

    Miles, J. A.; Das, Diptaranjan; Simmons, Z. J.; Yavuz, D. D.

    2015-09-01

    We experimentally demonstrate the localization of excitation between hyperfine ground states of 87Rb atoms to as small as λ /13 -wide spatial regions. We use ultracold atoms trapped in a dipole trap and utilize electromagnetically induced transparency (EIT) for the atomic excitation. The localization is achieved by combining a spatially varying coupling laser (standing wave) with the intensity dependence of EIT. The excitation is fast (150 ns laser pulses) and the dark-state fidelity can be made higher than 94% throughout the standing wave. Because the width of the localized regions is much smaller than the wavelength of the driving light, traditional optical imaging techniques cannot resolve the localized features. Therefore, to measure the excitation profile, we use an autocorrelation-like method where we perform two EIT sequences separated by a time delay, during which we move the standing wave.

  4. Damage Localization and Quantification of Earthquake Excited RC-Frames

    DEFF Research Database (Denmark)

    Skjærbæk, P.S.; Nielsen, Søren R.K.; Kirkegaard, Poul Henning;

    In the paper a recently proposed method for damage localization and quantification of RC-structures from response measurements is tested on experimental data. The method investigated requires at least one response measurement along the structure and the ground surface acceleration. Further, the t...

  5. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation.

    Science.gov (United States)

    Bayati, Mehdi; Valizadeh, Alireza; Abbassian, Abdolhossein; Cheng, Sen

    2015-01-01

    Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfire chains has been studied extensively in feed-forward networks of spiking neurons. However, it remains unclear how such neural activity could emerge in recurrent neuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higher frequency than the other, spontaneously active neurons in the network, can shape a network to allow for synchronous activity propagation. We use two-dimensional, locally connected and heterogeneous neuronal networks with spike-timing dependent plasticity (STDP). We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. This activity originates from the site of the local excitation and propagates through the network. The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even in the presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relatively simple way in realistic neural networks by locally exciting the desired origin of the neuronal sequence.

  6. Non-local effects of edge excitations in the quantum Hall regime

    OpenAIRE

    Deviatov, E. V.; Lorke, A.; Biasiol, G.; Sorba, L.

    2010-01-01

    We use a novel sample geometry to study non-local effects of edge excitations in the integer quantum Hall effect regime. We find that the condition of local equilibrium at the quantum Hall edge is affected by the diffusion of dynamically polarized nuclei. Our analysis indicates, that the nuclear diffusion is effectively one-dimensional in the present experiment.

  7. Nuclear charge-exchange excitations in localized covariant density functional theory

    CERN Document Server

    Liang, H Z; Nakatsukasa, T; Niu, Z M; Ring, P; Roca-Maza, X; Van Giai, N; Zhao, P W

    2014-01-01

    The recent progress in the studies of nuclear charge-exchange excitations with localized covariant density functional theory is briefly presented, by taking the fine structure of spin-dipole excitations in 16O as an example. It is shown that the constraints introduced by the Fock terms of the relativistic Hartree-Fock scheme into the particle-hole residual interactions are straightforward and robust.

  8. Nuclear charge-exchange excitations in localized covariant density functional theory

    International Nuclear Information System (INIS)

    The recent progress in the studies of nuclear charge-exchange excitations with localized covariant density functional theory is briefly presented, by taking the fine structure of spin-dipole excitations in 16O as an example. It is shown that the constraints introduced by the Fock terms of the relativistic Hartree-Fock scheme into the particle-hole residual interactions are straightforward and robust. (authors)

  9. Surface Plasmon Excitation and Localization by Metal-Coated Axicon Prism

    Directory of Open Access Journals (Sweden)

    Atsushi Ono

    2012-02-01

    Full Text Available Collimated Gaussian beams are efficiently localized at the apex of a metal-coated axicon prism by surface plasmon excitations. We observed the light scattered at the apex and the light reflected by the prism. Intense scattered light was observed with the radial polarization incidence. Further, each incidence of the radial, azimuthal, and linear polarizations provided field distributions of bright and dark intensities in the reflected images according to the surface plasmon excitation. We have demonstrated that surface plasmon waves are excited at the sides of the prism in the Kretschmann configuration and that they converge to its apex.

  10. Excitation Localization/Delocalization Isomerism in a Strongly Coupled Covalent Dimer of 1,3-Diphenylisobenzofuran

    Energy Technology Data Exchange (ETDEWEB)

    Schrauben, Joel N.; Akdag, Akin; Wen, Jin; Havlas, Zdenek; Ryerson, Joseph L.; Smith, Millie B.; Michl, Josef; Johnson, Justin C.

    2016-05-26

    Two isomers of both the lowest excited singlet (S1) and triplet (T1) states of the directly para, para'-connected covalent dimer of the singlet-fission chromophore 1,3-diphenylisobenzofuran have been observed. In one isomer, excitation is delocalized over both halves of the dimer, and in the other, it is localized on one or the other half. For a covalent dimer in solution, such 'excitation isomerism' is extremely rare. The vibrationally relaxed isomers do not interconvert, and their photophysical properties, including singlet fission, differ significantly.

  11. Plasmonic localized heating beyond the diffraction limit via magnetic polariton excitation

    Science.gov (United States)

    Alshehri, Hassan; Ying, Xiaoyan; Wang, Hao; Wang, Liping

    2016-09-01

    Optical localized heating in the nanoscale has recently attracted great attention due to its unique small hot spot size with high energy. However, the hot spot size is conventionally constrained by the diffraction limit. Plasmonic localized heating can provide solutions to this limitation in nanoscale patterning, cancer treatment, and data storage. Plasmonic approaches to overcome the diffraction limit in hot spot size have mainly utilized the excitation of surface plasmon or localized surface plasmon resonance. However, achieving plasmonic localized heating by the excitation of magnetic polariton has not been researched extensively yet. In this work, we numerically investigated the optical response of a nanoscale metamaterial composed of a gold nanowire array and a gold film separated by an ultrathin polymer spacer using ANSYS High Frequency Structural Simulator. A strong absorption peak at the wavelength of 760 nm was exhibited, and the underlying physical mechanism for the strong absorption was verified via the local electromagnetic field distribution to be magnetic resonance excitation. An inductor-capacitor circuit model was used to predict the magnetic resonance wavelength and compare with the numerical results for varied geometrical parameters. Volume loss density due to the strong local optical energy confinement was transferred as heat generation to an ANSYS thermal solver to obtain the local temperature profile. The steady state temperature profile shows an average temperature of 145 °C confined in a local area as small as 33 nm within the spacer, with a full-width at half-maximum of 50 nm along the x-direction. Moreover, the temperature rise from ambient drops to half its maximum value at a distance of 5 nm from the top of the spacer along the z-direction. This clearly demonstrates plasmonic localized heating beyond the diffraction limit via magnetic polariton excitation. Furthermore, the transient temperature profile shows that the system reached

  12. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism

    CERN Document Server

    Nagesh, Jayashree; Brumer, Paul; Izmaylov, Artur F

    2016-01-01

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A.F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory (TD-DFT) framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Stratman-Scuseria-Frisch atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1-naphthyl)-methyl)-anthracene and 4-((2-naphthyl)-methyl)-benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that are not accessible using simple density difference analysis.

  13. Localized Beampipe Heating due to $e^-$ Capture and Nuclear Excitation in Heavy Ion Colliders

    OpenAIRE

    Klein, Spencer R.

    2000-01-01

    At heavy ion colliders, two major sources of beam loss are expected to be $e^+e^-$ production, where the $e^-$ is bound to one of the nuclei, and photonuclear excitation and decay via neutron emission. Both processes alter the ions charged to mass ratio by well defined amounts, creating beams of particles with altered magnetic rigidity. These beams will deposit their energy in a localized region of the accelerator, causing localized heating, The size of the target region depends on the collid...

  14. Localized Excitations in a Sixth-Order (1+1)-Dimensional Nonlinear Evolution Equation

    Institute of Scientific and Technical Information of China (English)

    SHEN Shou-Feng

    2005-01-01

    In this letter, by means of the Lax pair, Darboux transformation, and variable separation approach, a new exact solution of a sixth-order (1+ 1)-dimensional nonlinear evolution equation, which includes some arbitrary functions,is obtained. Abundant new localized excitations can be found by selecting appropriate functions and they are illustrated both analytically and graphically.

  15. Lithuania 1940 / Herbert Foster Anderson

    Index Scriptorium Estoniae

    Foster Anderson, Herbert

    2004-01-01

    Stseenid Leedu ennesõjaaegsest pealinnast Kaunasest briti ärimehe H. Foster Andersoni silme läbi 1940. aastal. Lühikokkuvõte raamatust: Foster Anderson, Herbert. Borderline Russia. London : Cresset press, 1942

  16. The Price-Anderson Act

    International Nuclear Information System (INIS)

    The Price-Anderson Act establishes nuclear liability law in the United States. First passed in 1957, it has influenced other nuclear liability legislation around the world. The insurer response the nuclear accident at Three Mile Island in 1979 demonstrates the application of the Act in a real life situation. The Price-Anderson Act is scheduled to be renewed in 2002, and the future use of commercial nuclear power in tge United States will be influenced by this renewal. (author)

  17. Excitation of unsteady Görtler vortices by localized surface nonuniformities

    Science.gov (United States)

    Boiko, A. V.; Ivanov, A. V.; Kachanov, Yu. S.; Mischenko, D. A.; Nechepurenko, Yu. M.

    2016-08-01

    A combined theoretical and numerical analysis of an experiment devoted to the excitation of Görtler vortices by localized stationary or vibrating surface nonuniformities in a boundary layer over a concave surface is performed. A numerical model of generation of small-amplitude disturbances and their downstream propagation based on parabolic equations is developed. In the framework of this model, the optimal and the modal parts of excited disturbance are defined as solutions of initial-value problems with initial values being, respectively, the optimal disturbance and the leading local mode at the location of the source. It is shown that a representation of excited disturbance as a sum of the optimal part and a remainder makes it possible to describe its generation and downstream propagation, as well as to predict satisfactorily the corresponding receptivity coefficient. In contrast, the representation based on the modal part provides only coarse information about excitation and propagation of disturbance in the range of parameters under investigation. However, it is found that the receptivity coefficients estimated using the modal parts can be reinterpreted to preserve their practical significance. A corresponding procedure was developed. The theoretical and experimental receptivity coefficients are estimated and compared. It is found that the receptivity magnitudes grow significantly with the disturbance frequency. Variation of the span-wise scale of the nonuniformities affects weakly the receptivity characteristics at zero frequency. However, at high frequencies, the efficiency of excitation of Görtler vortices depends substantially on the span-wise scale.

  18. Potential-energy surfaces of local excited states from subsystem- and selective Kohn–Sham-TDDFT

    International Nuclear Information System (INIS)

    Research highlights: ► Application of selective TDDFT for potential-energy surfaces. ► Improved eigenvector guesses for convergence speed-up. ► Intuitive single-orbital transition picture breaks down in adsorbate–surface model. ► Comparison of frozen-density embedding with classical point-charge models. ► Frozen-density embedding yields smooth potential-energy surfaces for adsorbate states. - Abstract: Calculating excited-state potential-energy surfaces for systems with a large number of close-lying excited states requires the identification of the relevant electronic transitions for several geometric structures. Time-dependent density functional theory (TDDFT) is very efficient in such calculations, but the assignment of local excited states of the active molecule can be difficult. We compare the results of the frozen-density embedding (FDE) method with those of standard Kohn–Sham density-functional theory (KS-DFT) and simpler QM/MM-type methods. The FDE results are found to be more accurate for the geometry dependence of excitation energies than classical models. We also discuss how selective iterative diagonalization schemes can be exploited to directly target specific excitations for different structures. Problems due to strongly interacting orbital transitions and possible solutions are discussed. Finally, we apply FDE and the selective KS-TDDFT to investigate the potential energy surface of a high-lying π → π∗ excitation in a pyridine molecule approaching a silver cluster.

  19. Importance of local exact exchange potential in hybrid functionals for accurate excited states

    CERN Document Server

    Kim, Jaewook; Hwang, Sang-Yeon; Ryu, Seongok; Choi, Sunghwan; Kim, Woo Youn

    2016-01-01

    Density functional theory has been an essential analysis tool for both theoretical and experimental chemists since accurate hybrid functionals were developed. Here we propose a local hybrid method derived from the optimized effective potential (OEP) method and compare its distinct features with conventional nonlocal ones from the Hartree-Fock (HF) exchange operator. Both are formally exact for ground states and thus show similar accuracy for atomization energies and reaction barrier heights. For excited states, the local version yields virtual orbitals with N-electron character, while those of the nonlocal version have mixed characters between N- and (N+1)-electron orbitals. As a result, the orbital energy gaps from the former well approximate excitation energies with a small mean absolute error (MAE = 0.40 eV) for the Caricato benchmark set. The correction from time-dependent density functional theory with a simple local density approximation kernel further improves its accuracy by incorporating multi-config...

  20. High-Dimensional Nonlinear Envelope Equations and Nonlinear Localized Excitations in Photonic Crystals

    Institute of Scientific and Technical Information of China (English)

    HANG Chao; HUANG Guo-Xiang

    2006-01-01

    We investigate the nonlinear localized structures of optical pulses propagating in a one-dimensional photonic crystal with a quadratic nonlinearity. Using a method of multiple scales we show that the nonlinear evolution of a wave packet, formed by the superposition of short-wavelength excitations, and long-wavelength mean fields, generated by the self-interaction of the wave packet, are governed by a set of coupled high-dimensional nonlinear envelope equations, which can be reduced to Davey-Stewartson equations and thus support dromionlike high-dimensional nonlinear excitations in the system.

  1. Local excitation of surface plasmon polaritons using nitrogen-vacancy centers

    CERN Document Server

    Garcia-Ortiz, Cesar E; Bozhevolnyi, Sergey I

    2016-01-01

    Surface plasmon polaritons (SPPs) are locally excited at silver surfaces using (~100) nm-sized nanodiamonds (NDs) with multiple nitrogen-vacancy (NV) centers (~400). The fluorescence from an externally illuminated (at 532 nm) ND and from nearby NDs, which are not illuminated but produce out-of-plane scattering of SPPs excited by the illuminated ND, exhibit distinctly different wavelength spectra, showing short-wavelength filtering due to the SPP propagation loss. The results indicate that NDs with multiple NV centers can be used as efficient sub-wavelength SPP sources in planar integrated plasmonics for various applications.

  2. Local probing of magnetic films by optical excitation of magnetostatic waves

    Science.gov (United States)

    Chernov, A. I.; Kozhaev, M. A.; Vetoshko, P. M.; Dodonov, D. V.; Prokopov, A. R.; Shumilov, A. G.; Shaposhnikov, A. N.; Berzhanskii, V. N.; Zvezdin, A. K.; Belotelov, V. I.

    2016-06-01

    Excitation of volume and surface magnetostatic spin waves in ferrite garnet films by circularly polarized laser pulses utilizing to the inverse magnetooptical Faraday effect has been studied experimentally. The region of excitation of the magnetostatic spin waves is determined by the diameter of the laser beam (˜10 μm). At the same time, the characteristic propagation length of the modes is 30 μm. A method of finding the local characteristics of a magnetic film, in particular, the cubic and uniaxial anisotropy constants, based on the analysis of the azimuthal-angle dependence of the spectrum of the magnetostatic spin waves has been proposed.

  3. Polarons in π-Conjugated Polymers: Anderson or Landau?

    Science.gov (United States)

    Barford, William; Marcus, Max; Tozer, Oliver Robert

    2016-02-01

    Using both analytical expressions and the density matrix renormalization group method, we study the fully quantized disordered Holstein model to investigate the localization of charges and excitons by vibrational or torsional modes-i.e., the formation of polarons-in conformationally disordered π-conjugated polymers. We identify two distinct mechanisms for polaron formation, namely Anderson localization via disorder (causing the formation of Anderson polarons) and self-localization by self-trapping via normal modes (causing the formation of Landau polarons). We identify the regimes where either description is more valid. The key distinction between Anderson and Landau polarons is that for the latter the particle wave function is a strong function of the normal coordinates, and hence the "vertical" and "relaxed" wave functions are different. This has theoretical and experimental consequences for Landau polarons. Theoretically, it means that the Condon approximation is not valid, and so care needs to be taken when evaluating transition rates. Experimentally, it means that the self-localization of the particle as a consequence of its coupling to the normal coordinates may lead to experimental observables, e.g., ultrafast fluorescence depolarization. We apply these ideas to poly(p-phenylenevinylene). We show that the high frequency C-C bond oscillation only causes Landau polarons for a very narrow parameter regime; generally we expect disorder to dominate and Anderson polarons to be a more applicable description. Similarly, for the low frequency torsional fluctuations we show that Anderson polarons are expected for realistic parameters.

  4. Fluorescence and phosphorescence from individual C$_{60}$ molecules excited by local electron tunneling

    OpenAIRE

    Ćavar, Elizabeta; Blüm, Marie-Christine; Pivetta, Marina; Patthey, François; Chergui, Majed; Schneider, Wolf-Dieter

    2005-01-01

    Using the highly localized current of electrons tunneling through a double barrier Scanning Tunneling Microscope (STM) junction, we excite luminescence from a selected C$_{60}$ molecule in the surface layer of fullerene nanocrystals grown on an ultrathin NaCl film on Au(111). In the observed luminescence fluorescence and phosphorescence spectra, pure electronic as well as vibronically induced transitions of an individual C$_{60}$ molecule are identified, leading to unambiguous chemical recogn...

  5. Phil Anderson's Magnetic Ideas in Science

    CERN Document Server

    Coleman, Piers

    2016-01-01

    In Philip W. Anderson's research, magnetism has always played a special role, providing a prism through which other more complex forms of collective behavior and broken symmetry could be examined. I discuss his work on magnetism from the 1950s, where his early work on antiferromagnetism led to the pseudospin treatment of superconductivity - to the 70s and 80s, highlighting his contribution to the physics of local magnetic moments. Phil's interest in the mechanism of moment formation, and screening evolved into the modern theory of the Kondo effect and heavy fermions.

  6. Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation

    International Nuclear Information System (INIS)

    The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT

  7. Spatial organization of vegetation arising from non-local excitation with local inhibition in tropical rainforests

    Science.gov (United States)

    Thompson, Sally; Katul, Gabriel; Terborgh, John; Alvarez-Loayza, Patricia

    2009-06-01

    The Janzen-Connell (JC) effect, which hypothesizes that recruitment and growth of seedlings is positively correlated to the distance from the parent tree, is shown to generate highly organized vegetation biomass spatial patterns when coupled to a revised Fisher-Kolmogorov (FK) equation. Spatial organization arises through a novel mechanism of non-local activation and local inhibition. Over a single generation, the revised FK model calculations predict a “hen and chicks” dynamic pattern with mature trees surrounded by new seedlings growing at characteristic spatial distances in agreement with field data. Over longer timescales, the importance of stochastic dynamics, such as those associated with randomly occurring light gaps, increase thereby causing a substantial deviation between predictions from the deterministic FK model and its stochastic counterpart derived to account for such random disturbances. At still longer timescales, however, statistical measures of the spatial organization, specifically the spatial density of mature trees and their minimum spacing, converge between these two model representations.

  8. Folded Localized Excitations in a Generalized (2 + 1)-Dimensional Perturbed Nonlinear Schroedinger System

    Institute of Scientific and Technical Information of China (English)

    ZHENGChun-Long; ZHANGJie-Fang; CHENLi-Qun

    2003-01-01

    Starting from a special Baecklund transform and a variable separation approach, a quite general variable separation solution of the generalized ( 2 + 1 )-dimensional perturbed nonlinear Schroedinger system is obtained. In addition to the single-valued localized coherent soliron excitations like dromions, breathers, instantons, peakons, and previously revealed chaotic localized solution, a new type of multi-valued (folded) localized excitation is derived by introducing some appropriate lower-dimensional multiple valued functions.

  9. Stark effect of interfering electronic states: Localization of the nπ* excitations in toluquinone

    Science.gov (United States)

    Galaup, J. P.; Trommsdorff, H. P.

    1984-04-01

    High-precision Stark measurements on oriented single crystals of toluquinone at low temperatures have been performed and lead to an assessment of the electronic parenthood of the levels giving rise to the complex spectral region of interference between the two nearby nπ* excited states. The origin bands of the lowest excited singlet and triplet states are characterized by a measure of their factor-group splittings and an evaluation of the change in dipole moment and in polarizability upon excitation. The value of the change in dipole moment is shown to vary strongly between different vibrational levels of the lower state and an evaluation of the degree of localization of the electronic excitation on one CO group is made. The previous assignment of the second nπ* state is confirmed by the sign of the corresponding Stark shift. From measurements on crystals having been oriented in an electric field the absolute orientation of the polar crystal as well as the sign of the pyroelectric coefficient are proposed.

  10. Dimensional Dependence of Critical Exponent of the Anderson Transition in the Orthogonal Universality Class

    OpenAIRE

    Ueoka, Yoshiki; Slevin, Keith

    2014-01-01

    We report improved numerical estimates of the critical exponent of the Anderson transition in Anderson's model of localization in $d=4$ and $d=5$ dimensions. We also report a new Borel-Pad\\'e analysis of existing $\\epsilon$ expansion results that incorporates the asymptotic behaviour for $d\\to \\infty$ and gives better agreement with available numerical results.

  11. Spatial organization of vegetation arising from non-local excitation with local inhibition in forests

    Science.gov (United States)

    Thompson, S. E.; Katul, G. G.; Terborgh, J.; Alvarez-Loayza, P.

    2009-12-01

    Pattern formation in the biogeosciences is not limited to consideration of granular and fluid phenomena, but also occurs due to interactions within ecological systems. Here we present a novel mechanism of non-local activation and local inhibition that arises in the dynamics of competition and predation associated with parent trees and their seedlings. These dynamics, known as the Janzen-Connell (JC) effect, arise when recruitment and growth of seedlings is positively correlated to the distance from the parent tree. Such effects generate highly organized vegetation biomass spatial patterns when coupled to a revised Fisher-Kolmogorov (FK) equation. Over a single generation, the revised FK model calculations predict a "hen and chicks" dynamic pattern with mature trees surrounded by new seedlings growing at characteristic spatial distances in agreement with field data. Over longer timescales, the importance of stochastic dynamics, such as those associated with randomly occurring light gaps, increase thereby causing a substantial deviation between predictions from the deterministic FK model and its stochastic counterpart derived to account for such random disturbances. At still longer timescales, however, statistical measures of the spatial organization, specifically the spatial density of mature trees and their minimum spacing, converge between the two model representations.

  12. Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wolfrum, Matthias; Omel' chenko, Oleh E. [Weierstrass Institute, Mohrenstrasse 39, Berlin 10117 (Germany); Sieber, Jan [College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF (United Kingdom)

    2015-05-15

    We study a system of phase oscillators with nonlocal coupling in a ring that supports self-organized patterns of coherence and incoherence, called chimera states. Introducing a global feedback loop, connecting the phase lag to the order parameter, we can observe chimera states also for systems with a small number of oscillators. Numerical simulations show a huge variety of regular and irregular patterns composed of localized phase slipping events of single oscillators. Using methods of classical finite dimensional chaos and bifurcation theory, we can identify the emergence of chaotic chimera states as a result of transitions to chaos via period doubling cascades, torus breakup, and intermittency. We can explain the observed phenomena by a mechanism of self-modulated excitability in a discrete excitable medium.

  13. Conductance fluctuations in a macroscopic 3-dimensional Anderson insulator

    International Nuclear Information System (INIS)

    We report magnetoconductance experiment on a amorphous Yx-Si1-x alloy (∼0.3). which is an Anderson insulator where spin-orbit scattering is strong. Two principal and new features emerge from the data: the first one is an halving of the localization length by the application of a magnetic field of about 2.5 Teslas. This effect is predicted by a new approach of transport in Anderson insulators where basic symetry considerations are the most important ingredient. The second one is the observation of reproducible conductance fluctuations at very low temperature in this macroscopic 3 D amorphous material

  14. Local excitation of strongly coupled exciton-surface plasmons polaritons by a single nanoantenna

    Energy Technology Data Exchange (ETDEWEB)

    Eizner, E., E-mail: eladeiz@post.tau.ac.il; Ellenbogen, T. [Department of Physical Electronics, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

    2014-06-02

    We demonstrate experimentally local coupling of light from free space to exciton-surface plasmon polaritons (X-SPPs). This is achieved by using a single, sub-wavelength gold nanowire on top of a thin silver film which is covered with a 30 nm thick layer of J-aggregating dyes in polyvinyl alcohol. We show that the nanowire acts as an antenna that resonantly scatters light to X-SPPs states with a Rabi splitting of 0.1 eV. The locally excited X-SPPs properties are studied by angle resolved spectroscopy of the far-field leaky photons and are compared to the large-scale response through Kretschmann reflection measurements and to theoretical calculations. The nanowire scattering properties are studied by dark-field scattering measurements and finite-difference time-domain simulations. This method to locally excite X-SPPs can potentially be useful for future applications of hybrid light matter states.

  15. An Anderson-like model of the QCD chiral transition

    CERN Document Server

    Giordano, Matteo; Pittler, Ferenc

    2016-01-01

    We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the...

  16. Localized magnetic excitations for a line of magnetic impurities in a transverse Ising thin film ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Leite, R.V., E-mail: valmir.leite@uvanet.b [Universidade Estadual Vale do Acarau, Centro de Ciencias Exatas e Tecnologia, Av. Dr. Guarany, 317, Campus do Cidao, 62040-730 Sobral, Ceara (Brazil); Oliveira Filho, L.O. de [Universidade Estadual Vale do Acarau, Centro de Ciencias Exatas e Tecnologia, Av. Dr. Guarany, 317, Campus do Cidao, 62040-730 Sobral, Ceara (Brazil); Milton Pereira, J. [Instituto de Fisica, Universidade Federal de Alagoas, 57072-970 Maceio, Alagoas (Brazil)] [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceara (Brazil); Cottam, M.G. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7 (Canada); Costa Filho, R.N. [Department of Physics and Astronomy, University of Western Ontario, London, Ontario, N6A 3K7 (Canada)] [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceara (Brazil)

    2009-09-28

    A Green's function method is used to obtain the spectrum of spin excitations associated with a linear array of magnetic impurities implanted in a ferromagnetic thin film. The equations of motion for the Green's functions of the anisotropic film are written in the framework of the Ising model in a transverse field. The frequencies of localized modes are calculated as a function of the interaction parameters for the exchange coupling between impurity-spin pairs, host-spin pairs, and impurity-host neighbors, as well as the effective field parameter at the impurity sites.

  17. Femtosecond excitations in metallic nanostructures. From ultrafast light confinement to a local electron source

    Energy Technology Data Exchange (ETDEWEB)

    Ropers, C.

    2007-07-11

    This thesis contributes to the understanding of optical excitations in metallic nanostructures. In experiments on selected model structures, the dynamics of these excitations and their electromagnetic spatial modes are investigated with femtosecond temporal and nanometer spatial resolution, respectively. Angle- and time-resolved transmission experiments on metallic thin film gratings demonstrate the dominant role resonant surface plasmon polaritons (SPPs) play in the optical properties of such structures. The lifetimes of these excitations are determined, and it is shown that coherent couplings among SPP-resonances result in drastic lifetime modifications. Near the visible part of the spectrum, subradiant SPP lifetimes of up to 200 femtoseconds are observed, which is considerably longer than previously expected for these structures. The spatial SPP mode profiles are imaged using a custom-built near-field optical microscope. The experiments reveal a direct correlation between the spatial mode structure and the dynamics of different SPP resonances. Coupling-induced SPP band gaps are identified as splittings into symmetric and antisymmetric surface modes. These findings allow for an interpretation of the near-field optical image contrast in terms of the contributions of different vectorial components of the electromagnetic near-field. A selective imaging of different electric and magnetic field components is demonstrated for various types of near-field probes. Furthermore, the excitation of SPPs in periodic structures is employed in a novel type of near-field tip. The resonant excitation of SPPs in a nanofabricated grating on the shaft of a sharp metallic tip results in their concentration at the tip apex. The final part of the thesis highlights the importance of optical field enhancements for the local generation of nonlinear optical signals at the apex of sharp metallic tips. Specifically, the observation of intense multiphoton electron emission after femtosecond

  18. Localization of bleomycin in a single living cell using three-photon excitation microscopy

    Science.gov (United States)

    Abraham, Anil T.; Brautigan, David L.; Hecht, Sidney M.; Periasamy, Ammasi

    2001-04-01

    Bleomycin has been used in the clinic as a chemotherapeutic agent for the treatment of several neoplasms, including non-Hodgkins lymphomas, squamous cell carcinomas, and testicular tumors. The effectiveness of bleomycin is believed to be derived from its ability to bind and oxidatively cleave DNA in the presence of a iron cofactor in vivo. A substantial amount of data on BLM has been collected, there is little information concerning the effects of bleomycin in living cells. In order to obtain data pertinent to the effects of BLM in intact cells, we have exploited the intrinsic fluorescence property of bleomycin to monitor the uptake of the drug in mammalian cells. We employed two light microscopy techniques, a wide-field and three-photon excitation (760 nm) fluorescence microscopy. Treatment of HeLa cells with bleomycin resulted in rapid to localization within the cells. In addition data collected from the wide field experiments, three-photon excitation of BLM which considerably reduced the phototoxic effect compared with UV light excitation in the wide-field microscopy indicated co-localization of the drug to regions of the cytoplasm occupied by the endoplasmic reticulum probe, DiOC5. The data clearly indicates that the cellular uptake of bleomycin after one minute includes the nucleus as well as in cytoplasm. Contrary to previous studies, which indicate chromosomal DNA as the target of bleomycin, the current findings suggest that the drug is distributed to many areas within the cell, including the endoplasmic reticulum, an organelle that is known to contain ribonucleic acids.

  19. LoFEx — A local framework for calculating excitation energies: Illustrations using RI-CC2 linear response theory

    Science.gov (United States)

    Baudin, Pablo; Kristensen, Kasper

    2016-06-01

    We present a local framework for the calculation of coupled cluster excitation energies of large molecules (LoFEx). The method utilizes time-dependent Hartree-Fock information about the transitions of interest through the concept of natural transition orbitals (NTOs). The NTOs are used in combination with localized occupied and virtual Hartree-Fock orbitals to generate a reduced excitation orbital space (XOS) specific to each transition where a standard coupled cluster calculation is carried out. Each XOS is optimized to ensure that the excitation energies are determined to a predefined precision. We apply LoFEx in combination with the RI-CC2 model to calculate the lowest excitation energies of a set of medium-sized organic molecules. The results demonstrate the black-box nature of the LoFEx approach and show that significant computational savings can be gained without affecting the accuracy of CC2 excitation energies.

  20. Anderson Localization in the Induced Disorder System

    Science.gov (United States)

    Fei-Fei, Lu; Chun-Fang, Wang

    2016-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11104185, 11174084 and 10934011, and the National Basic Research Program of China under Grant No 2012CB921904.

  1. Evidence for Cation-Controlled Excited-State Localization in a Ruthenium Polypyridyl Compound.

    Science.gov (United States)

    Beauvilliers, Evan E; Meyer, Gerald J

    2016-08-01

    The visible absorption and photoluminescence (PL) properties of the four neutral ruthenium diimine compounds [Ru(bpy)2(dcb)] (B2B), [Ru(dtb)2(dcb)] (D2B), [Ru(bpy)2(dcbq)] (B2Q), and [Ru(dtb)2(dcbq)] (D2Q), where bpy is 2,2'-bipyridine, dcb is 4,4'-(CO2(-))2-bpy, dtb is 4,4'-(tert-butyl)2-bpy, and dcbq is 4,4'-(CO2(-))2-2,2'-biquinoline, are reported in the presence of Lewis acidic cations present in fluid solutions at room temperature. In methanol solutions, the measured spectra were insensitive to the presence of these cations, while in acetonitrile a significant red shift in the PL spectra (≤1400 cm(-1)) was observed consistent with stabilization of the metal-to-ligand charge transfer (MLCT) excited state through Lewis acid-base adduct formation. No significant spectral changes were observed in control experiments with the tetrabutylammonium cation. Titration data with Li(+), Na(+), Mg(2+), Ca(2+), Zn(2+), Al(3+), Y(3+), and La(3+) showed that the extent of stabilization saturated at high cation concentration with magnitudes that scaled roughly with the cation charge-to-size ratio. The visible absorption spectra of D2Q was particularly informative due to the presence of two well-resolved MLCT absorption bands: (1) Ru → bpy, λmax ≈ 450 nm; and (2) Ru → dcbq, λmax ≈ 540 nm. The higher-energy band blue-shifted and the lower-energy band red-shifted upon cation addition. The PL intensity and lifetime of the excited state of B2B first increased with cation addition without significant shifts in the measured spectra, behavior attributed to a cation-induced change in the localization of the emissive excited state from bpy to dcb. The importance of excited-state localization and stabilization for solar energy conversion is discussed. PMID:27391279

  2. Quantum Localization in Laser-Driven Molecular Rotation

    Science.gov (United States)

    Averbukh, Ilya

    2016-05-01

    Recently we predicted that several celebrated solid state quantum localization phenomena - Anderson localization, Bloch oscillations, and Tamm-Shockley surface states - may manifest themselves in the rotational dynamics of laser-kicked molecules. In this talk, I will present these new rotational effects in a gas of linear molecules subject to a moderately long periodic train of femtosecond laser pulses. A small detuning of the train period from the rotational revival time causes Anderson localization in the angular momentum space above some critical value of J - the Anderson wall. This wall marks an impenetrable border stopping any further rotational excitation. Below the Anderson wall, the rotational excitation oscillates with the number of pulses due to a mechanism similar to Bloch oscillations in crystalline solids. I will present the results of the first experimental observation of the laser-induced rotational Bloch oscillations in molecular nitrogen at ambient conditions (Stanford & Weizmann, 2015). We will also discuss the prospects of observing the rotational analogues of the Tamm surface states in a similar experimental setup. Our results offer laser-driven molecular rotation as a new platform for studies on the localization phenomena in quantum transport. These effects are important for many processes involving highly excited rotational states, including coherent optical manipulations in molecular mixtures, and propagation of powerful laser pulses in atmosphere.

  3. The Anderson transition due to random spin-orbit coupling in two-dimension

    OpenAIRE

    Asada, Yoichi; Slevin, Keith; Ohtsuki, Tomi

    2003-01-01

    We report an analysis of the Anderson transition in an SU(2) model with chiral symmetry. Clear single parameter scaling behaviour is observed. We estimate the critical exponent for the divergence of the localization length to be $\

  4. Localization of scalar massless excitations in self-gravitating $SO(10)$ kinks

    CERN Document Server

    Chavez, Rafael; Rodriguez, R Omar

    2016-01-01

    Three self-gravitating $SO(10)$ kinks inducing asymptotically the breaking pattern $SO(10)\\rightarrow SU(5)$ are determined which can be distinguished by the unbroken group on each of them: $SO(10)$ for the first kink and $SO(6)\\times SU(2)\\times U(1)$ and $SU(4)\\times SO(2)\\times U(1)$ for the second and third kink respectively. The scenarios are perturbed by considering small excitations on the fields; in particular, the metric fluctuations are parameterized in terms of tensor, vector and scalar modes. All these modes as well as the perturbations of the scalar field are rewritten as gauge-invariant variables. With regarding the tensor and vector fluctuations, for a four dimensional observer, the standard results are obtained: while the massless graviton is localized on the wall the graviphotons propagate freely in the bulk. On the other hand, for the scalar excitations in correspondence with the symmetry on the kink, both along the broken generators and along the some unbroken generators, normalizable zero ...

  5. Self-Localized Quasi-Particle Excitation in Quantum Electrodynamics and Its Physical Interpretation

    Directory of Open Access Journals (Sweden)

    Ilya D. Feranchuk

    2007-12-01

    Full Text Available The self-localized quasi-particle excitation of the electron-positron field (EPF is found for the first time in the framework of a standard form of the quantum electrodynamics. This state is interpreted as the ''physical'' electron (positron and it allows one to solve the following problems: i to express the ''primary'' charge $e_0$ and the mass $m_0$ of the ''bare'' electron in terms of the observed values of $e$ and $m$ of the ''physical'' electron without any infinite parameters and by essentially nonperturbative way; ii to consider $mu$-meson as another self-localized EPF state and to estimate the ratio $m_mu/m$; iii to prove that the self-localized state is Lorentz-invariant and its energy spectrum corresponds to the relativistic free particle with the observed mass $m$; iv to show that the expansion in a power of the observed charge $e ll 1$ corresponds to the strong coupling expansion in a power of the ''primary'' charge $e^{-1}_0 sim e$ when the interaction between the ''physical'' electron and the transverse electromagnetic field is considered by means of the perturbation theory and all terms of this series are free from the ultraviolet divergence.

  6. Excitation of XPS spectra from nanoscaled particles by local generation of x-rays

    International Nuclear Information System (INIS)

    In preliminary work, the authors have shown that use of an aluminum substrate to support a distribution of copper particles enables their characteristic photoelectrons to be observed within the Auger electron spectrum generated by an incident electron beam. This observation raises the possibility of the use of chemical shifts and the corresponding Auger parameter to identify the chemical states present on the surface of individual submicrometer particles within a mixture. In this context, the technique has an advantage in that, unlike conventional Auger electron spectroscopy, the electron beam does not dwell on the particle but on the substrate adjacent to it. Given the importance, for both medical and toxicological reasons, of the surface composition of such particles, the authors have continued to explore the potential of this development. In this contribution, the authors show that proximal excitation of x-rays is equally successful with magnesium substrates. In some regions of the x-ray photoelectron spectrum, the much larger Auger peaks generated by the electron beam can cause inconvenient clustering of Auger and photoelectron peaks. As in conventional x-ray photoelectron spectroscopy, the ability to switch between Al and Mg sources is useful in such situations. In this context, the authors have extended the studies to iron particles where the authors show that use of Al or Mg substrates, as necessary, can make a contribution to clear identification of individual components in the Fe 2p peaks. For this development in electron spectroscopy to achieve its full potential, it is necessary to optimize the beam conditions used to generate the local x-ray to give good selectivity of a given particle. Measurements made in support of this will be given. Of greater concern is a possible problem of local heating associated with x-ray generation. The authors continue to explore this problem and report some progress in minimizing heating of the particle while maintaining

  7. Excitation of XPS spectra from nanoscaled particles by local generation of x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Mallinson, Christopher F.; Castle, James E., E-mail: J.castle@surrey.ac.uk [The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2015-09-15

    In preliminary work, the authors have shown that use of an aluminum substrate to support a distribution of copper particles enables their characteristic photoelectrons to be observed within the Auger electron spectrum generated by an incident electron beam. This observation raises the possibility of the use of chemical shifts and the corresponding Auger parameter to identify the chemical states present on the surface of individual submicrometer particles within a mixture. In this context, the technique has an advantage in that, unlike conventional Auger electron spectroscopy, the electron beam does not dwell on the particle but on the substrate adjacent to it. Given the importance, for both medical and toxicological reasons, of the surface composition of such particles, the authors have continued to explore the potential of this development. In this contribution, the authors show that proximal excitation of x-rays is equally successful with magnesium substrates. In some regions of the x-ray photoelectron spectrum, the much larger Auger peaks generated by the electron beam can cause inconvenient clustering of Auger and photoelectron peaks. As in conventional x-ray photoelectron spectroscopy, the ability to switch between Al and Mg sources is useful in such situations. In this context, the authors have extended the studies to iron particles where the authors show that use of Al or Mg substrates, as necessary, can make a contribution to clear identification of individual components in the Fe 2p peaks. For this development in electron spectroscopy to achieve its full potential, it is necessary to optimize the beam conditions used to generate the local x-ray to give good selectivity of a given particle. Measurements made in support of this will be given. Of greater concern is a possible problem of local heating associated with x-ray generation. The authors continue to explore this problem and report some progress in minimizing heating of the particle while maintaining

  8. Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

    Science.gov (United States)

    Kamimura, H. A. S.; Wang, S.; Wu, S.-Y.; Karakatsani, M. E.; Acosta, C.; Carneiro, A. A. O.; Konofagou, E. E.

    2015-10-01

    Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n  =  15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52 MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52 MPa, burst duration: 20 ms, duration: 5 min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38+/- 5.71 mm3, 8.91+/- 3.91 mm3and 35.47+/- 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40+/- 28.43 V.s, 63.87+/- 29.97 V.s and 356.52+/- 257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue.

  9. Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

    Science.gov (United States)

    Kamimura, HAS; Wang, S; Wu, S-Y; Karakatsani, ME; Acosta, C; Carneiro, AAO; Konofagou, EE

    2015-01-01

    Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n=15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52 MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52 MPa, burst duration: 20 ms, duration: 5 min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38±5.71 mm3, 8.91±3.91 mm3 and 35.47 ± 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40±28.43 V.s, 63.87±29.97 V.s and 356.52±257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue. PMID:26394091

  10. Tracking local spin-dynamics via high-energy quasi-molecular excitations in a spin-orbit Mott insulator

    OpenAIRE

    Nembrini, Nicola; Peli, Simone; Banfi, Francesco; Ferrini, Gabriele; Singh, Yogesh; Gegenwart, Philipp; Comin, Riccardo; Foyevtsova, Kateryna; Damascelli, Andrea; Avella, Adolfo; Giannetti, Claudio

    2016-01-01

    We use time- and energy-resolved optical spectroscopy to investigate the coupling of electron-hole excitations to the local magnetic environment in the relativistic Mott insulator Na$_2$IrO$_3$. We show that, on the picosecond timescale, the photoinjected electron-hole pairs delocalize on the hexagons of the Ir lattice forming quasi-molecular orbital (QMO) excitations and exchanging energy with the short-range ordered magnetic background. Our results provide a unifying picture of the physics ...

  11. An Anderson-like model of the QCD chiral transition

    Science.gov (United States)

    Giordano, Matteo; Kovács, Tamás G.; Pittler, Ferenc

    2016-06-01

    We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the QCD spectrum and of the Dirac eigenmodes concerning chiral symmetry breaking and localisation, both in the ordered (deconfined) and disordered (confined) phases. Moreover, it allows us to study separately the roles played in the two phenomena by the diagonal and the off-diagonal terms of the Dirac-Anderson Hamiltonian. Our results support our expectation that chiral symmetry restoration and localisation of the low modes are closely related, and that both are triggered by the deconfinement transition.

  12. Benedict Andersons forestillede fællesskaber

    DEFF Research Database (Denmark)

    Ivarsson, Søren

    2007-01-01

    Artiklen diskuterer Benedict Andersons analyse af nationalismens opståen i en kolonial kontekst og den kritik som Partha Chatterjee har rejst mod denne. Udgivelsesdato: Januar 2008......Artiklen diskuterer Benedict Andersons analyse af nationalismens opståen i en kolonial kontekst og den kritik som Partha Chatterjee har rejst mod denne. Udgivelsesdato: Januar 2008...

  13. Fermi-liquid theory for the single-impurity Anderson model

    Science.gov (United States)

    Mora, Christophe; Moca, Cǎtǎlin Paşcu; von Delft, Jan; Zaránd, Gergely

    2015-08-01

    We generalize Nozières' Fermi-liquid theory for the low-energy behavior of the Kondo model to that of the single-impurity Anderson model. In addition to the electrons' phase shift at the Fermi energy, the low-energy Fermi-liquid theory is characterized by four Fermi-liquid parameters: the two given by Nozières that enter to first order in the excitation energy, and two additional ones that enter to second order and are needed away from particle-hole symmetry. We express all four parameters in terms of zero-temperature physical observables, namely the local charge and spin susceptibilities and their derivatives with respect to the local level position. We determine these in terms of the bare parameters of the Anderson model using Bethe ansatz and numerical renormalization group (NRG) calculations. Our low-energy Fermi-liquid theory applies throughout the crossover from the strong-coupling Kondo regime via the mixed-valence regime to the empty-orbital regime. From the Fermi-liquid theory, we determine the conductance through a quantum dot symmetrically coupled to two leads in the regime of small magnetic field, low temperature, and small bias voltage, and compute the coefficients of the ˜B2 , ˜T2 , and ˜V2 terms exactly in terms of the Fermi-liquid parameters. The coefficients of T2, V2, and B2 are found to change sign during the Kondo to empty-orbital crossover. The crossover becomes universal in the limit that the local interaction is much larger than the level width. For completeness, we also compute the shot noise and discuss the resulting Fano factor.

  14. Critical parameters from generalised multifractal analysis at the Anderson transition

    OpenAIRE

    Rodriguez, Alberto; Vasquez, Louella J.; Slevin, Keith; Römer, Rudolf A.

    2010-01-01

    We propose a generalization of multifractal analysis that is applicable to the critical regime of the Anderson localization-delocalization transition. The approach reveals that the behavior of the probability distribution of wavefunction amplitudes is sufficient to characterize the transition. In combination with finite-size scaling, this formalism permits the critical parameters to be estimated without the need for conductance or other transport measurements. Applying this method to high-pre...

  15. Tunable local excitation of surface plasmon polaritons by sum-frequency generation in ZnO nanowires

    Science.gov (United States)

    Brincker, Mads; Pedersen, Kjeld; Skovsen, Esben

    2015-12-01

    Tunable local excitation of surface plasmon polaritons (SPP) by sum-frequency generation (SFG) in Zinc Oxide (ZnO) nanowires on a smooth and thin silver film has been studied by applying angle resolved leakage radiation spectroscopy. SFG between an infrared (IR) source, with a variable wavelength in the telecom range between 1350 nm and 1550 nm, and a near-infrared (NIR) source with a fixed wavelength of 790 nm resulted in the excitation of SPP's at wavelengths between 498 nm and 523 nm. The SFG to SPP coupling efficiency was studied as a function of the excitation angle and the wavelength of the IR source. It was shown that the SPP coupling was most efficient at oblique excitation angles, and that SFG in ZnO nanowires allows for the coherent conversion of optical signals at telecom frequencies to SPP's with frequencies within the visible range.

  16. Mott transitions in the periodic Anderson model

    Science.gov (United States)

    Logan, David E.; Galpin, Martin R.; Mannouch, Jonathan

    2016-11-01

    The periodic Anderson model (PAM) is studied within the framework of dynamical mean-field theory, with particular emphasis on the interaction-driven Mott transition it contains, and on resultant Mott insulators of both Mott-Hubbard and charge-transfer type. The form of the PAM phase diagram is first deduced on general grounds using two exact results, over the full range of model parameters and including metallic, Mott, Kondo and band insulator phases. The effective low-energy model which describes the PAM in the vicinity of a Mott transition is then shown to be a one-band Hubbard model, with effective hoppings that are not in general solely nearest neighbour, but decay exponentially with distance. This mapping is shown to have a range of implications for the physics of the problem, from phase boundaries to single-particle dynamics; all of which are confirmed and supplemented by NRG calculations. Finally we consider the locally degenerate, non-Fermi liquid Mott insulator, to describe which requires a two-self-energy description. This is shown to yield a number of exact results for the associated local moment, charge, and interaction-renormalised levels, together with a generalisation of Luttinger’s theorem to the Mott insulator.

  17. Price-Anderson Law - reports on Price-Anderson issues

    International Nuclear Information System (INIS)

    Five of the six papers in this study are by experts outside the nuclear industry, and deal with fear, risk, and risk management as they apply to the review of the Price-Anderson Act. The purpose of the Act is to encourage private enterprise to develop a reliable source of electric power and to protect the public from the financial consequences of injury or damage that may occur during the process. The titles of the five papers are: (1) the effects of ionizing radiation on human health, (2) proof of causation through expert opinion evidence in low-level radiation cases, (3) a critical review of the probability of causation method, (4) the nuclear liability claims experience of the nuclear insurance pools, (5) review of nuclear liability compensation systems applicable to reactors outside the United States, and (6) the economic foundations of limited liability for nuclear reactor accidents. A separate abstract was prepared for each of the papers for EDB, EPA, and INS

  18. Topological approximation of the nonlinear Anderson model

    Science.gov (United States)

    Milovanov, Alexander V.; Iomin, Alexander

    2014-06-01

    We study the phenomena of Anderson localization in the presence of nonlinear interaction on a lattice. A class of nonlinear Schrödinger models with arbitrary power nonlinearity is analyzed. We conceive the various regimes of behavior, depending on the topology of resonance overlap in phase space, ranging from a fully developed chaos involving Lévy flights to pseudochaotic dynamics at the onset of delocalization. It is demonstrated that the quadratic nonlinearity plays a dynamically very distinguished role in that it is the only type of power nonlinearity permitting an abrupt localization-delocalization transition with unlimited spreading already at the delocalization border. We describe this localization-delocalization transition as a percolation transition on the infinite Cayley tree (Bethe lattice). It is found in the vicinity of the criticality that the spreading of the wave field is subdiffusive in the limit t →+∞. The second moment of the associated probability distribution grows with time as a power law ∝ tα, with the exponent α =1/3 exactly. Also we find for superquadratic nonlinearity that the analog pseudochaotic regime at the edge of chaos is self-controlling in that it has feedback on the topology of the structure on which the transport processes concentrate. Then the system automatically (without tuning of parameters) develops its percolation point. We classify this type of behavior in terms of self-organized criticality dynamics in Hilbert space. For subquadratic nonlinearities, the behavior is shown to be sensitive to the details of definition of the nonlinear term. A transport model is proposed based on modified nonlinearity, using the idea of "stripes" propagating the wave process to large distances. Theoretical investigations, presented here, are the basis for consistency analysis of the different localization-delocalization patterns in systems with many coupled degrees of freedom in association with the asymptotic properties of the

  19. Student trainee report of Walter L. Anderson

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The following report is intended to summarize the activities of Walter L. Anderson, Student Trainee (Wildlife Biology) at Malheur National Wildlife Refuge during...

  20. Enhanced Wegner and Minami estimates and eigenvalue statistics of random Anderson models at spectral edges

    CERN Document Server

    Germinet, François

    2011-01-01

    We consider the discrete Anderson model and prove enhanced Wegner and Minami estimates where the interval length is replaced by the IDS computed on the interval. We use these estimates to improve on the description of finite volume eigenvalues and eigenfunctions obtained in a previous paper. As a consequence of the improved description of eigenvalues and eigenfunctions, we revisit a number of results on the spectral statistics in the localized regime and extend their domain of validity, namely : - the local spectral statistics for the unfolded eigenvalues; - the local asymptotic ergodicity of the unfolded eigenvalues; In dimension 1, for the standard Anderson model, the improvement enables us to obtain the local spectral statistics at band edge, that is in the Lifshitz tail regime. In higher dimensions, this works for modified Anderson models.

  1. Localized Excitations of (2+1)-Dimensional Korteweg-de Vries System Derived from a Periodic Wave Solution

    Institute of Scientific and Technical Information of China (English)

    QIANG Ji-Ye; FEI Jin-Xi; CAI Gui-Ping; ZHENG Chun-Long

    2007-01-01

    With the aid of an improved projective approach and a linear variable separation method,new types of variable separation solutions (including solitary wave solutions,periodic wave solutions,and rational function solutions)with arbitrary functions for (2+1)-dimensional Korteweg-de Vries system are derived.Usually,in terms of solitary wave solutions and rational function solutions,one can find some important localized excitations.However,based on the derived periodic wave solution in this paper,we find that some novel and significant localized coherent excitations such as dromions,peakons,stochastic fractal patterns,regular fractal patterns,chaotic line soliton patterns as well as chaotic patterns exist in the KdV system as considering appropriate boundary conditions and/or initial qualifications.

  2. New localized excitations and cross-like fractal structures to the (2+1)-dimensional Broer–Kaup system

    Indian Academy of Sciences (India)

    Zitian Li

    2014-09-01

    A broad general variable separation solution with two arbitrary lower-dimensional functions of the (2+1)-dimensional Broer–Kaup (BK) equations was derived by means of a projective equation method and a variable separation hypothesis. Based on the derived variable separation excitation, some new special types of localized solutions such as oscillating solitons, instantonlike and cross-like fractal structures are revealed by selecting appropriate functions of the general variable separation solution.

  3. Nonlinear Response of Localized Excitons: Effects of the Excitation-Induced Dephasing

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang Werner; Birkedal, Dan;

    1997-01-01

    . In particular, we show experimentally that the excitation-induced dephasing gives rise to a photon echo in inhomogeneous systems. We develop a simple analytical model for the delay dependence of the signal, which enables us to deduce the dephasing time from the four-wave mixing decay....

  4. Excitation of localized modes and mechanism of random lasing forming in random media

    Institute of Scientific and Technical Information of China (English)

    WANG Hong; LIU Jinsong; WANG Kejia; HAN Yanling

    2006-01-01

    Laser phenomena in random media have been studied based on the localized theory for lightwave in random media. The relationship between random lasing modes and localized modes has been investigated by directly solving Maxwell equations numerically via the finite difference time domain method. The spatial distribution and the spectra of localized modes are obtained for both passive and active random media. The results show that random lasing modes directly originate from the localized modes inside the random medium. In the presence of gain, any one of the localized modes can be amplified and can serve as random lasing mode.

  5. Local excitation and interference of surface phonon polaritons studied by near-field infrared microscopy.

    Science.gov (United States)

    Huber, A J; Ocelic, N; Hillenbrand, R

    2008-03-01

    We demonstrate that mid-infrared surface phonon polariton excitation, propagation and interference can be studied by scattering-type near-field optical microscopy (s-SNOM). In our experiments we image surface phonon polaritons (SPPs) propagating on flat SiC crystals. They are excited by weakly focused illumination of single or closely spaced metal disks we fabricated on the SiC surface by conventional photolithography. SPP imaging is performed by pseudo-heterodyne interferometric detection of infrared light scattered by the metal tip of our s-SNOM. The pseudo-heterodyne technique simultaneously yields optical amplitude and phase images which allows us to measure the SPP wave vector--including its sign--and the propagation length and further to study SPP interference. High resolution imaging of SPPs could be applied to investigate for example SPP focusing or heat transfer by SPPs in low dimensional nanostructures. PMID:18331484

  6. Localization phenomena in interacting Rydberg lattice gases with position disorder

    CERN Document Server

    Marcuzzi, Matteo; Barredo, Daniel; de Léséleuc, Sylvain; Labuhn, Henning; Lahaye, Thierry; Browaeys, Antoine; Levi, Emanuele; Lesanovsky, Igor

    2016-01-01

    Disordered systems provide paradigmatic instances of ergodicity breaking and localization phenomena. Here we explore the dynamics of excitations in a system of Rydberg atoms held in optical tweezers. The finite temperature produces an intrinsic uncertainty in the atomic positions, which translates into quenched correlated disorder in the interatomic interaction strengths. In a simple approach, the dynamics in the many-body Hilbert space can be understood in terms of a one-dimensional Anderson-like model with disorder on every other site, featuring both localized and delocalized states. We conduct an experiment on an eight-atom chain and observe a clear suppression of excitation transfer. Our experiment accesses a regime which is described by a two-dimensional Anderson model on a "trimmed" square lattice. Our results thus provide a concrete example in which the absence of excitation propagation in a many-body system is directly related to Anderson-like localization in the Hilbert space, which is believed to be...

  7. Spin excitations in systems with hopping electron transport and strong position disorder in a large magnetic field

    Science.gov (United States)

    Shumilin, A. V.

    2016-10-01

    We discuss the spin excitations in systems with hopping electron conduction and strong position disorder. We focus on the problem in a strong magnetic field when the spin Hamiltonian can be reduced to the effective single-particle Hamiltonian and treated with conventional numerical technics. It is shown that in a 3D system with Heisenberg exchange interaction the spin excitations have a delocalized part of the spectrum even in the limit of strong disorder, thus leading to the possibility of the coherent spin transport. The spin transport provided by the delocalized excitations can be described by a diffusion coefficient. Non-homogenous magnetic fields lead to the Anderson localization of spin excitations while anisotropy of the exchange interaction results in the Lifshitz localization of excitations. We discuss the possible effect of the additional exchange-driven spin diffusion on the organic spin-valve devices.

  8. Spatial dispersion effects upon local excitation of extrinsic plasmons in a graphene micro-disk

    Science.gov (United States)

    Mencarelli, D.; Bellucci, S.; Sindona, A.; Pierantoni, L.

    2015-11-01

    Excitation of surface plasmon waves in extrinsic graphene is studied using a full-wave electromagnetic field solver as analysis engine. Particular emphasis is placed on the role played by spatial dispersion due to the finite size of the two-dimensional material at the micro-scale. A simple instructive set up is considered where the near field of a wire antenna is held at sub-micrometric distance from a disk-shaped graphene patch. The key-input of the simulation is the graphene conductivity tensor at terahertz frequencies, being modeled by the Boltzmann transport equation for the valence and conduction electrons at the Dirac points (where a linear wave-vector dependence of the band energies is assumed). The conductivity equation is worked out in different levels of approximations, based on the relaxation time ansatz with an additional constraint for particle number conservation. Both drift and diffusion currents are shown to significantly contribute to the spatially dispersive anisotropic features of micro-scale graphene. More generally, spatial dispersion effects are predicted to influence not only plasmon propagation free of external sources, but also typical scanning probe microscopy configurations. The paper sets the focus on plasmon excitation phenomena induced by near field probes, being a central issue for the design of optical devices and photonic circuits.

  9. Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy

    Science.gov (United States)

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2014-02-01

    Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging because of the small signal and large achiral background. Here we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light-harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic states following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability because of the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments.

  10. The Interplay between Localized and Propagating Plasmonic Excitations Tracked in Space and Time

    DEFF Research Database (Denmark)

    Lemke, Christoph; Leißner, Till; Evlyukhin, Andrey;

    2014-01-01

    In this work, the mutual coupling and coherent interaction of propagating and localized surface plasmons within a model-type plasmonic assembly is experimentally demonstrated, imaged, and analyzed. Using interferometric time-resolved photoemission electron microscopy the interplay between ultrash...

  11. Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

    Institute of Scientific and Technical Information of China (English)

    LI Bing-Wei; SUN Li-Li; CHEN Bin; YING He-Ping

    2007-01-01

    @@ Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies:for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.

  12. Topology dependent quantities at the Anderson transition

    OpenAIRE

    Slevin, Keith; Ohtsuki, Tomi; Kawarabayashi, Tohru

    2000-01-01

    The boundary condition dependence of the critical behavior for the three dimensional Anderson transition is investigated. A strong dependence of the scaling function and the critical conductance distribution on the boundary conditions is found, while the critical disorder and critical exponent are found to be independent of the boundary conditions.

  13. Corrections to scaling at the Anderson transition

    OpenAIRE

    Slevin, Keith; Ohtsuki, Tomi

    1998-01-01

    We report a numerical analysis of corrections to finite size scaling at the Anderson transition due to irrelevant scaling variables and non-linearities of the scaling variables. By taking proper account of these corrections, the universality of the critical exponent for the orthogonal universality class for three different distributions of the random potential is convincingly demonstrated.

  14. Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation.

    Science.gov (United States)

    Fountaine, Katherine T; Kendall, Christian G; Atwater, Harry A

    2014-05-01

    We report design methods for achieving near-unity broadband light absorption in sparse nanowire arrays, illustrated by results for visible absorption in GaAs nanowires on Si substrates. Sparse (unity absorption at wire resonant wavelengths due to coupling into 'leaky' radial waveguide modes of individual wires and wire-wire scattering processes. From a detailed conceptual development of radial mode resonant absorption, we demonstrate two specific geometric design approaches to achieve near unity broadband light absorption in sparse nanowire arrays: (i) introducing multiple wire radii within a small unit cell array to increase the number of resonant wavelengths, yielding a 15% absorption enhancement relative to a uniform nanowire array and (ii) tapering of nanowires to introduce a continuum of diameters and thus resonant wavelengths excited within a single wire, yielding an 18% absorption enhancement over a uniform nanowire array.

  15. Proteomic profiling of neuromas reveals alterations in protein composition and local protein synthesis in hyper-excitable nerves

    Directory of Open Access Journals (Sweden)

    Timms John F

    2008-08-01

    Full Text Available Abstract Neuropathic pain may arise following peripheral nerve injury though the molecular mechanisms associated with this are unclear. We used proteomic profiling to examine changes in protein expression associated with the formation of hyper-excitable neuromas derived from rodent saphenous nerves. A two-dimensional difference gel electrophoresis (2D-DIGE profiling strategy was employed to examine protein expression changes between developing neuromas and normal nerves in whole tissue lysates. We found around 200 proteins which displayed a >1.75-fold change in expression between neuroma and normal nerve and identified 55 of these proteins using mass spectrometry. We also used immunoblotting to examine the expression of low-abundance ion channels Nav1.3, Nav1.8 and calcium channel α2δ-1 subunit in this model, since they have previously been implicated in neuronal hyperexcitability associated with neuropathic pain. Finally, S35methionine in vitro labelling of neuroma and control samples was used to demonstrate local protein synthesis of neuron-specific genes. A number of cytoskeletal proteins, enzymes and proteins associated with oxidative stress were up-regulated in neuromas, whilst overall levels of voltage-gated ion channel proteins were unaffected. We conclude that altered mRNA levels reported in the somata of damaged DRG neurons do not necessarily reflect levels of altered proteins in hyper-excitable damaged nerve endings. An altered repertoire of protein expression, local protein synthesis and topological re-arrangements of ion channels may all play important roles in neuroma hyper-excitability.

  16. The Anderson Quin Cycle. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.H.; Bilbow, W.M.

    1993-03-18

    The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since this grant was limited to 2150 man hours, we could not expect to achieve all the objectives within the allotted period of work. However, the most relevant program objectives have been completed as reported here. The analysis generally confirms the results originally estimated in my paper on the subject. (Ref. 2) Further optimizations should show even higher efficiencies. The Anderson Quin Cycle (US Patent applied for) basically consists of 5 elements in the power cycle: A refrigeration system to cool and clean the inlet air before it enters the compressor that supplies air for the gas turbine; a gas turbine consisting of a compressor, combustor, and turbine; a steam boiler and steam turbine system using the heat from the exhaust gas out of the gas turbine; a vapor turbine cycle, which utilizes the condensed heat from the exhaust of the steam turbine and the exhaust gas heat leaving the steam boiler to operate a vapor turbine cycle which utilizes another fluid than water, in this case isobutane; and the fifth element consists of a gas cooler and heat pump system, which removes the heat from the exhaust gas to lower its temperature essentially to atmospheric temperature, and at the same time permits treatment of the exhaust gas to remove acid components such as sulfur dioxide and nitrogen oxides. Current industry accepted component characteristics were incorporated in the performance analysis of the overall cycle, ensuring accurate and meaningful operating predictions. The characteristics and performance of each of the elements are described. The thermal efficiency of the optimized calculated Anderson Quin Cycle is 62 percent.

  17. Transport of localized and extended excitations in chains embedded with randomly distributed linear and nonlinear n -mers

    Science.gov (United States)

    López-González, Dany; Molina, Mario I.

    2016-03-01

    We examine the transport of extended and localized excitations in one-dimensional linear chains populated by linear and nonlinear symmetric identical n -mers (with n =3 , 4, 5, and 6), randomly distributed. First, we examine the transmission of plane waves across a single linear n -mer, paying attention to its resonances, and looking for parameters that allow resonances to merge. Within this parameter regime we examine the transmission of plane waves through a disordered and nonlinear segment composed by n -mers randomly placed inside a linear chain. It is observed that nonlinearity tends to inhibit the transmission, which decays as a power law at long segment lengths. This behavior still holds when the n -mer parameters do not obey the resonance condition. On the other hand, the mean square displacement exponent of an initially localized excitation does not depend on nonlinearity at long propagation distances z , and shows a superdiffusive behavior ˜z1.8 for all n -mers, when parameters obey the resonance merging condition; otherwise the exponent reverts back to the random dimer model value ˜z1.5 .

  18. Collective excitations of dipolar gases based on local tunneling in ultracold superlattices

    CERN Document Server

    Cao, L; Deng, X; Schmelcher, P

    2016-01-01

    The collective dynamics of a dipolar fermionic quantum gas confined in a one-dimensional double-well superlattice is explored. The fermionic gas resides in a paramagnetic-like ground state in the weak interaction regime, upon which a new type of collective dynamics is found when applying a local perturbation. This dynamics is composed of the local tunneling of fermions in separate supercells, and is a pure quantum effect, with no classical counterpart. Due to the presence of the dipolar interactions the local tunneling transports through the entire superlattice, giving rise to a collective dynamics. A well-defined momentum-energy dispersion relation is identified in the ab-initio simulations demonstrating the phonon-like behavior. The phonon-like characteristic is also confirmed by an analytical description of the dynamics within a semiclassical picture.

  19. Mott-Hubbard and Anderson transitions in dynamical mean-field theory

    Energy Technology Data Exchange (ETDEWEB)

    Byczuk, Krzysztof [Institute of Theoretical Physics, Warsaw University, ul. Hoza 69, PL-00-681 Warsaw (Poland)]. E-mail: byczuk@fuw.edu.pl; Hofstetter, Walter [Condensed Matter Theory Group, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Vollhardt, Dieter [Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, D-86135 Augsburg (Germany)

    2005-04-30

    The Anderson-Hubbard Hamiltonian at half-filling is investigated within dynamical mean-field theory at zero temperature. The local density of states is calculated by taking the geometric and arithmetic mean, respectively. The non-magnetic ground state phase diagrams obtained within the different averaging schemes are compared.

  20. Local-field corrections to the decay rate of excited molecules in absorbing cavities the Onsager model

    CERN Document Server

    Tomas, M S

    2000-01-01

    The decay rate and the classical radiation power of an excited molecule (atom) located in the center of a dispersive and absorbing dielectric sphere taken as a simple model of a cavity are calculated adopting the Onsager model for the local field. The local-field correction factor to the external (radiation and absorption) power loss of the molecule is found to be $|3\\epsilon(\\omega)/[3\\epsilon(\\omega)+1]|^2$, with $\\epsilon(\\omega)$ being the dielectric function of the sphere. However, local-field corrections to the total decay rate (power loss) of the molecule are found to be much more complex, including those to the decay rate in the infinite cavity medium, as derived very recently by Scheel et al. [Rev. A 60, 4094 (1999)], and similiar corrections to the cavity-induced decay rate. The results obtained can be cast into model-independent forms. This suggests the general results for the local-field corrections to the decay rate and to the external power loss of a molecule in an absorbing cavity valid for mol...

  1. Absorption and Emission in quantum dots: Fermi surface effects of Anderson excitons

    OpenAIRE

    Helmes, R. W.; Sindel, M.; Borda, L.; von Delft, J.

    2005-01-01

    Recent experiments measuring the emission of exciton recombination in a self-organized single quantum dot (QD) have revealed that novel effects occur when the wetting layer surrounding the QD becomes filled with electrons, because the resulting Fermi sea can hybridize with the local electron levels on the dot. Motivated by these experiments, we study an extended Anderson model, which describes a local conduction band level coupled to a Fermi sea, but also includes a local valence band level. ...

  2. Localized excitations in discrete nonlinear Schrodinger systems: Effects of nonlocal dispersive interactions and noise

    DEFF Research Database (Denmark)

    Rasmussen, Kim; Christiansen, Peter Leth; Johansson, Magnus;

    1998-01-01

    , s(cr), there is an interval of bistability where two stable stationary states exist at each excitation number. The bistability of on-site solitons may occur for dipole-dipole dispersive interaction (s = 3), while s(cr) for inter-sire solitons is close to 2.1. In the framework of the DNLS equation......A one-dimensional discrete nonlinear Schrodinger (DNLS) model with the power dependence, r(-s) on the distance r, of dispersive interactions is proposed. The stationary states of the system are studied both analytically and numerically. Two kinds of trial functions, exp-like and sech......-like are exploited and the results of both approaches are compared. Both on-site and inter-site stationary states sue investigated. It is shown that for s sufficiently large air features of the model me qualitatively the same as in the DNLS model with nearest-neighbor interaction. For s less than some critical value...

  3. Analysis of localized diabatic states beyond the condon approximation for excitation energy transfer processes.

    Science.gov (United States)

    Alguire, Ethan C; Fatehi, Shervin; Shao, Yihan; Subotnik, Joseph E

    2014-12-26

    In a previous paper [ Fatehi , S. ; et al. J. Chem. Phys. 2013 , 139 , 124112 ], we demonstrated a practical method by which analytic derivative couplings of Boys-localized CIS states can be obtained. In this paper, we now apply that same method to the analysis of triplet-triplet energy transfer systems studied by Closs and collaborators [ Closs , G. L. ; et al. J. Am. Chem. Soc. 1988 , 110 , 2652 ]. For the systems examined, we are able to conclude that (i) the derivative coupling in the BoysOV basis is negligible, and (ii) the diabatic coupling will likely change little over the configuration space explored at room temperature. Furthermore, we propose and evaluate an approximation that allows for the inexpensive calculation of accurate diabatic energy gradients, called the "strictly diabatic" approximation. This work highlights the effectiveness of diabatic state analytic gradient theory in realistic systems and demonstrates that localized diabatic states can serve as an acceptable approximation to strictly diabatic states. PMID:24447246

  4. Impurity-induced antiferromagnetic domains in the periodic Anderson model

    Science.gov (United States)

    Benali, A.; Bai, Z. J.; Curro, N. J.; Scalettar, R. T.

    2016-08-01

    A central feature of the periodic Anderson model is the competition between antiferromagnetism, mediated by the Ruderman-Kittel-Kasuya-Yosida interaction at small conduction electron-local electron hybridization V , and singlet formation at large V . At zero temperature, and in dimension d >1 , these two phases are separated by a quantum critical point Vc. We use quantum Monte Carlo (QMC) simulations to explore the effect of impurities which have a local hybridization V*Vc . We measure the suppression of singlet correlations and the antiferromagnetic correlations which form around the impurity, as well as the size of the resulting domain. Exact diagonalization calculations for linear chains allow us to verify that the qualitative features obtained at intermediate coupling and finite T persist to strong coupling and T =0 , regimes which are difficult to access with QMC. Our calculations agree qualitatively with NMR measurements in CeCoIn5 -xCdx .

  5. A rational reduction of CI expansions: combining localized molecular orbitals and selected charge excitations.

    Science.gov (United States)

    Krah, Tim; Ben Amor, Nadia; Maynau, Daniel; Berger, J A; Robert, Vincent

    2014-07-01

    Based on localized molecular orbitals, the proposed method reduces large configuration interaction (CI) spaces while maintaining agreement with reference values. Our strategy concentrates the numerical effort on physically pertinent CI-contributions and is to be considered as a tool to tackle large systems including numerous open-shells. To show the efficiency of our method we consider two 4-electron parent systems. First, we illustrate our approach by describing the van der Waals interactions in the (H2)2 system. By systematically including local correlation, dispersion and charge transfer mechanisms, we show that 90% of the reference full CI dissociation energy of the H2 dimer is reproduced using only 3% of the full CI space. Second, the conformational cis/trans rotation barrier of the butadiene molecule is remarkably reproduced (97% of the reference value) with less than 1% of the reference space. This work paves the way to numerical strategies which afford the electronic structure determination of large open-shell systems avoiding the exponential limitation. At the same time, a physical analysis of the contents of the wave function is offered. PMID:24935105

  6. Chiral Condensate and Mott-Anderson Freeze-Out

    International Nuclear Information System (INIS)

    We present the idea of a Mott-Anderson freeze-out that suggests a key role of the localization of the hadron wave functions when traversing the hadronization transition. The extension of hadron wave functions in dense matter is governed by the behavior of the chiral quark condensate such that its melting at finite temperatures and chemical potentials entails an increase of the size of hadrons and thus their geometrical strong interaction cross sections. It is demonstrated within a schematic resonance gas model, that a kinetic freeze-out condition reveals a correlation with the reduction of the chiral condensate in the phase diagram up to 50% of its vacuum value. Generalizing the description of the chiral condensate by taking into account a full hadron resonance gas such correlation gets distorted. We discuss, that this may be due to our approximations in calculating the chiral condensate which disregard both, in-medium effects on hadron masses and hadron-hadron interactions. The latter, in particular due to quark exchange reactions, could lead to a delocalization of the hadron wave functions in accordance with the picture of a Mott-Anderson transition. (author)

  7. Some Ergodic Theorems for a Parabolic Anderson Model

    Institute of Scientific and Technical Information of China (English)

    Yong LIU; Feng Xia YANG

    2012-01-01

    In this paper,we study some ergodic theorems of a class of linear systems of interacting diffusions,which is a parabolic Anderson model.First,under the assumption that the transition kernel a =(a(i,j))i,j∈s is doubly stochastic,we obtain the long-time convergence to an invariant probability measure Vh starting from a bounded a-harmonic function h based on self-duality property,and then we show the convergence to the invariant probability measure vh holds for a broad class of initial distributions.Second,if (a(i,j))i,j∈s is transient and symmetric,and the diffusion parameter c remains below a threshold,we are able to determine the set of extremal invariant probability measures with finite second moment.Finally,in the case that the transition kernel (a(i,j))i,j∈s is doubly stochastic and satisfies Case Ⅰ (see Case Ⅰ in [Shiga,T.:An interacting system in population genetics.J.Math.Kyoto Univ.,20,213-242 (1980)]),we show that this parabolic Anderson model locally dies out independent of the diffusion parameter c.

  8. Anderson introduces a new biomass baler

    Energy Technology Data Exchange (ETDEWEB)

    D' amour, L.; Lavoie, F. [Anderson Group Co., Chesterville, PQ (Canada)

    2010-07-01

    Canadian-based Anderson Group Company has developed an innovative round baler for harvesting a large variety of woody biomass. The baler was initially developed in 2005 in collaboration with the University Laval and Agriculture and Agri-Food Canada. The third generation BIOBALER{sup TM} is currently built, engineered and commercialized by Anderson. It can produce up to 40 bales/hr in short rotations woody crops such as willow and hybrid poplar. The unit can harvest brushes up to 125 mm in diameter. A standard tractor can pull the BIOBALER in fallow or abandoned land, under power transmission lines, and between planted trees. The patented BIOBALER includes a mulcher head attachment, a choice of long or short swivel tongue, a fixed chamber and an undercarriage frame.

  9. Influence of an amorphous wall on the distribution of localized excitations in a colloidal glass-forming liquid

    Science.gov (United States)

    Gokhale, Shreyas; Hima Nagamanasa, K.; Sood, A. K.; Ganapathy, Rajesh

    2016-07-01

    Elucidating the nature of the glass transition has been the holy grail of condensed matter physics and statistical mechanics for several decades. A phenomenological aspect that makes glass formation a conceptually formidable problem is that structural and dynamic correlations in glass-forming liquids are too subtle to be captured at the level of conventional two-point functions. As a consequence, a host of theoretical techniques, such as quenched amorphous configurations of particles, have been devised and employed in simulations and colloid experiments to gain insights into the mechanisms responsible for these elusive correlations. Very often, though, the analysis of spatio-temporal correlations is performed in the context of a single theoretical framework, and critical comparisons of microscopic predictions of competing theories are thereby lacking. Here, we address this issue by analysing the distribution of localized excitations, which are building blocks of relaxation as per the dynamical facilitation (DF) theory, in the presence of an amorphous wall, a construct motivated by the random first-order transition theory (RFOT). We observe that spatial profiles of the concentration of excitations exhibit complex features such as non-monotonicity and oscillations. Moreover, the smoothly varying part of the concentration profile yields a length scale {ξc} , which we compare with a previously computed length scale {ξ\\text{dyn}} . Our results suggest a method to assess the role of dynamical facilitation in governing structural relaxation in glass-forming liquids.

  10. Stability and local bifurcation of parameter-excited vibration of pipes conveying pulsating fluid under thermal loading

    Institute of Scientific and Technical Information of China (English)

    Demin ZHAO; Jianlin LIU; C Q WU

    2015-01-01

    The parametric excited vibration of a pipe under thermal loading may occur because the fluid is often transported heatedly. The effects of thermal loading on the pipe stability and local bifurcations have rarely been studied. The stability and the local bifurcations of the lateral parametric resonance of the pipe induced by the pulsating fluid velocity and the thermal loading are studied. A mathematical model for a simply supported pipe is developed according to the Hamilton principle. Two partial differential equations describing the lateral and longitudinal vibration are obtained. The singularity theory is utilized to analyze the stability and the bifurcation of the system solutions. The transition sets and the bifurcation diagrams are obtained both in the unfolding parameter space and the physical parameter space, which can reveal the relationship between the thermal field parameter and the dynamic behaviors of the pipe. The frequency response and the relationship between the critical thermal rate and the pulsating fluid velocity are obtained. The numerical results demonstrate the accuracy of the single-mode expansion of the solution and the stability and local bifurcation analyses. It also confirms the existence of the chaos. The presented work can provide valuable information for the design of the pipeline and the controllers to prevent the structural instability.

  11. Integrative Medicine Program- MD Anderson Cancer Center

    OpenAIRE

    Lee, Richard T.

    2012-01-01

    The Integrative Medicine Program at MD Anderson Cancer Center was first established in 1998.  Our mission is to empower patients with cancer and their families to become active partners in their own physical, psycho-spiritual, and social health through personalized education and evidenced-based clinical care to optimize health, quality of life, and clinical outcomes across the cancer continuum.  The program consists of three main components: clinical care, research, and education.  The Integr...

  12. Near-field optical microscopy of localized excitations on rough surfaces: influence of a probe

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    calculate the self consistent field intensity at the site of a probe dipole scanning over resonantly interacting object dipoles and show that the intensity distribution deviates from that existing in the absence of a probe. I demonstrate that this difference increases with an increase in the polarizability...... of the probe dipole, resulting eventually in a completely different intensity distribution, The calculations also show that the perturbation of the intensity distribution due to the presence of a probe decreases with an increase in the probe-sample distance. In order to evaluate the degree of...... perturbation, I suggest comparing the images obtained at different probe-sample distances, Finally I formulate a simple rule of thumb that allows one to roughly estimate the probe-sample coupling when imaging localized elicitations....

  13. Does the regulation of local excitation-inhibition balance aid in recovery of functional connectivity? A computational account.

    Science.gov (United States)

    Vattikonda, Anirudh; Surampudi, Bapi Raju; Banerjee, Arpan; Deco, Gustavo; Roy, Dipanjan

    2016-08-01

    Computational modeling of the spontaneous dynamics over the whole brain provides critical insight into the spatiotemporal organization of brain dynamics at multiple resolutions and their alteration to changes in brain structure (e.g. in diseased states, aging, across individuals). Recent experimental evidence further suggests that the adverse effect of lesions is visible on spontaneous dynamics characterized by changes in resting state functional connectivity and its graph theoretical properties (e.g. modularity). These changes originate from altered neural dynamics in individual brain areas that are otherwise poised towards a homeostatic equilibrium to maintain a stable excitatory and inhibitory activity. In this work, we employ a homeostatic inhibitory mechanism, balancing excitation and inhibition in the local brain areas of the entire cortex under neurological impairments like lesions to understand global functional recovery (across brain networks and individuals). Previous computational and empirical studies have demonstrated that the resting state functional connectivity varies primarily due to the location and specific topological characteristics of the lesion. We show that local homeostatic balance provides a functional recovery by re-establishing excitation-inhibition balance in all areas that are affected by lesion. We systematically compare the extent of recovery in the primary hub areas (e.g. default mode network (DMN), medial temporal lobe, medial prefrontal cortex) as well as other sensory areas like primary motor area, supplementary motor area, fronto-parietal and temporo-parietal networks. Our findings suggest that stability and richness similar to the normal brain dynamics at rest are achievable by re-establishment of balance. PMID:27177761

  14. Topological Anderson insulators in systems without time-reversal symmetry

    Science.gov (United States)

    Su, Ying; Avishai, Y.; Wang, X. R.

    2016-06-01

    Occurrence of the topological Anderson insulator (TAI) in a HgTe quantum well suggests that when time-reversal symmetry (TRS) is maintained, the pertinent topological phase transition, marked by re-entrant 2 e2/h quantized conductance contributed by helical edge states, is driven by disorder. Here we show that when TRS is broken, the physics of the TAI becomes even richer. The pattern of longitudinal conductance and nonequilibrium local current distribution displays novel TAI phases characterized by nonzero Chern numbers, indicating the occurrence of multiple chiral edge modes. Tuning either disorder or Fermi energy (in both topologically trivial and nontrivial phases), drives transitions between these distinct TAI phases, characterized by jumps of the quantized conductance from 0 to e2/h and from e2/h to 2 e2/h . An effective medium theory based on the Born approximation yields an accurate description of different TAI phases in parameter space.

  15. Lifshitz transitions in magnetic phases of the periodic Anderson model

    International Nuclear Information System (INIS)

    We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons. (author)

  16. Lifshitz Transitions in Magnetic Phases of the Periodic Anderson Model

    Science.gov (United States)

    Kubo, Katsunori

    2015-09-01

    We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons.

  17. High pressure luminescence studies of localized excitations in ZnS doped with Pb2+ and Mn2+

    International Nuclear Information System (INIS)

    High pressure luminescence measurements have been made on ZnS doped with Pb+2 and Mn+2. The data include changes in peak energy and shape, integrated intensities, and lifetimes. These localized emissions are treated in terms of a single configuration coordinate model. For Pb+2 the emission peak shifted to lower energy by a moderate amount and narrowed. For excitation in the Pb+2 absorption the intensity was independent of pressure, which is consistent with the fact that the energy barrier for radiationless return to the ground state was high at all pressures. For excitation in the ZnS absorption edge the intensity decreased significantly with pressure above about 80 kbar. Data on shifts of the conduction band with pressure would indicate that one is approaching a transition from a direct to indirect transition at high pressure so that decrease in emission intensity may be associated with decreased absorption efficiency. The Mn+2 emission peak shifted strongly to lower energy with increasing pressure. The direction and magnitude of the shift were consistent with the predictions of ligand field theory. The intensity doubled in 100 kbar, while the lifetime decreased by roughly a factor of 2. These results could be described in terms of a model for a phonon assisted transition. In addition, peak location, intensity, and lifetime measurements were made on ZnS:Pb:Mn. There is clear evidence of energy transfer by exchange, but in addition there is a nonradiative process in the doubly doped crystal which affects both intensities and lifetimes

  18. Integrative Medicine Program- MD Anderson Cancer Center

    Directory of Open Access Journals (Sweden)

    Richard T Lee

    2012-06-01

    Full Text Available The Integrative Medicine Program at MD Anderson Cancer Center was first established in 1998.  Our mission is to empower patients with cancer and their families to become active partners in their own physical, psycho-spiritual, and social health through personalized education and evidenced-based clinical care to optimize health, quality of life, and clinical outcomes across the cancer continuum.  The program consists of three main components: clinical care, research, and education.  The Integrative Medicine Center provides clinical services to patients through individual and group programs.  The clinical philosophy of the center is to work collaboratively with the oncology teams to build comprehensive and integrative care plans that are personalized, evidence-based, and safe with the goal of improving clinical outcomes.  The individual services comprise of integrative oncology consultation, acupuncture, meditation, music therapy, nutrition, and oncology massage.  The center also provides a variety of group programs including meditation, yoga, tai chi, cooking classes and others.  Over the past 13 years, over 70,000 patients and families have participated in services and programs offered by the center.  The research portfolio focuses on three main areas: mind-body interventions, acupuncture, and meditation.  This lecture will focus on providing an overview of the Integrative Medicine Program at MD Anderson with a focus on the clinical services provided.  Participants will learn about the integrative clinical model and how this is applied to the care of cancer patients at MD Anderson Cancer Center.  Current and future research topics will be discussed as well as patient cases.

  19. Resonant excitation of Mn local vibrational modes in the higher order Raman spectra of nanocrystalline Ga{sub 1-x}Mn{sub x}N films

    Energy Technology Data Exchange (ETDEWEB)

    Dias da Silva, J H; Leite, D M G [Department of Physics, Advanced Materials Group, UNESP-Sao Paulo State University, Bauru SP, 17033-360 (Brazil); Zanatta, A R [Instituto de Fisica de Sao Carlos, USP, Sao Carlos 13560-250 (Brazil)], E-mail: jhdsilva@fc.unesp.br, E-mail: dmgleite@fc.unesp.br, E-mail: zanatta@ifsc.usp.br

    2008-06-25

    The effect of manganese on the vibrational properties of Ga{sub 1-x}Mn{sub x}N (0{<=}x{<=}0.18) films has been investigated by Raman scattering using 488.0 and 632.8 nm photon excitations. The first-order transverse and longitudinal optical GaN vibrational bands were observed in the whole composition range using both excitations, while the corresponding overtones, as well as a prominent peak located in 1238 cm{sup -1} (153.5 meV) were only observed in the Mn-containing films under 488.0 nm excitation. We propose that the peak observed at 1238 cm{sup -1} is due to resonant Mn local vibrational modes, the excitation process being related to electronic transitions involving the Mn acceptor band. (fast track communication)

  20. Localized Spatial Soliton Excitations Equation with Variable Nonlinearity in (2 +1)-Dimensional Nonlinear SchrSdinger and an External Potential

    Institute of Scientific and Technical Information of China (English)

    钟卫平; Milivoj R. Belic; HUANG Ting-Wen

    2012-01-01

    We report on the localized spatial soliton excitations in the multidimensional nonlinear Schrodinger equation with radially variable nonlinearity coefficient and an external potential. By using Hirota's binary differential operators, we determine a variety of external potentials and nonlinearity coefficients that can support nonlinear localized solutions of different but desired forms. For some specific external potentials and nonlinearity coefficients, we discuss features of the corresponding (2+1)-dimensional multisolitonic solutions, including ring solitons, lump solitons, and soliton clusters.

  1. Anderson transition in the three dimensional symplectic universality class

    OpenAIRE

    Asada, Yoichi; Slevin, Keith; Ohtsuki, Tomi

    2004-01-01

    We study the Anderson transition in the SU(2) model and the Ando model. We report a new precise estimate of the critical exponent for the symplectic universality class of the Anderson transition. We also report numerical estimation of the $\\beta$ function.

  2. Theory of Anderson pseudospin resonance with Higgs mode in superconductors

    Science.gov (United States)

    Tsuji, Naoto; Aoki, Hideo

    2015-08-01

    A superconductor illuminated by an ac electric field with frequency Ω is theoretically found to generate a collective precession of Anderson's pseudospins, and hence a coherent amplitude oscillation of the order parameter, with a doubled frequency 2 Ω through a nonlinear light-matter coupling. We provide a fundamental theory, based on the mean-field formalism, to show that the induced pseudospin precession resonates with the Higgs amplitude mode of the superconductor at 2 Ω =2 Δ with 2 Δ being the superconducting gap. The resonant precession is accompanied by a divergent enhancement of the third-harmonic generation (THG). By decomposing the THG susceptibility into the bare one and vertex correction, we find that the enhancement of the THG cannot be explained by individual quasiparticle excitations (pair breaking), so that the THG serves as a smoking gun for an identification of the collective Higgs mode. We further explore the effect of electron-electron scattering on the pseudospin resonance by applying the nonequilibrium dynamical mean-field theory to the attractive Hubbard model driven by ac electric fields. The result indicates that the pseudospin resonance is robust against electron correlations, although the resonance width is broadened due to electron scattering, which determines the lifetime of the Higgs mode.

  3. Localized excitations with and without propagating properties in (2+1)-dimensions obtained by a mapping approach

    Institute of Scientific and Technical Information of China (English)

    Zheng Chun-Long; Fang Jian-Ping; Chen Li-Qun

    2005-01-01

    By means of an extended mapping approach, a new type of variable-separation excitation is derived with two arbitrary functions in a (2+1)-dimensional modified dispersive water-wave system. Based on the derived variable-separation excitation, abundant nonpropagating and propagating solitons such as dromions, rings, peakons and compactons are revealed by selecting appropriate functions in this paper.

  4. Perturbation theory for Lyapunov exponents of an Anderson model on a strip

    CERN Document Server

    Schulz-Baldes, H

    2003-01-01

    It is proven that the localization length of an Anderson model on a strip of width $L$ is bounded above by $L/\\lambda^2$ for small values of the coupling constant $\\lambda$ of the disordered potential. For this purpose, a new formalism is developed in order to calculate the bottom Lyapunov exponent associated with random products of large symplectic matrices perturbatively in the coupling constant of the randomness.

  5. Slow Relaxation in Anderson Critical Systems

    Science.gov (United States)

    Choi, Soonwon; Yao, Norman; Choi, Joonhee; Kucsko, Georg; Lukin, Mikhail

    2016-05-01

    We study the single particle dynamics in disordered systems with long range hopping, focusing on the critical cases, i.e., the hopping amplitude decays as 1 /rd in d-dimension. We show that with strong on-site potential disorder, the return probability of the particle decays as power-law in time. As on-site potential disorder decreases, the temporal profile smoothly changes from a simple power-law to the sum of multiple power-laws with exponents ranged from 0 to νmax. We analytically compute the decay exponents using a simple resonance counting argument, which quantitatively agrees with exact numerical results. Our result implies that the dynamics in Anderson Critical systems are dominated by resonances. Harvard-MIT CUA, Kwanjeong Educational Fellowship, AFOSR MURI, Samsung Scholarship.

  6. Anderson Exploration Ltd. 1998 annual report

    International Nuclear Information System (INIS)

    In 1998, Anderson Exploration's undeveloped land inventory in the western provinces decreased 7% to 3,183,000 net acres largely due to lease expiries and drilling activity. The undeveloped land base is located 63% in Alberta, 19% in British Columbia, 17% in Saskatchewan, and 1% in Manitoba. During 1998, Anderson Exploration participated in drilling 446 wells for oil and gas vs. 669 for 1997. The average working interest in the wells was 63% vs. 64% in 1997. In 1998, the company spent $109 million on the construction of field gathering systems and production facilities vs. $123 million in 1997. In 1998, the company's gas sales increased to 555 million cubic feet per day from 549 million cubic feet per day in 1997. Crude oil sales averaged 29,808 barrels per day in 1998, an increase of 9% over the 1997 production. In 1998, the company replaced 148% of production with proven reserve additions, net of revisions, by spending 163% of cash flow from operations on capital spending. After a volatile year in 1 997, natural gas prices stabilized somewhat in 1998. A modest price increase was experienced in 1997. The company's average plant gate natural gas price increased modestly in 1998 to $1.94 per thousand cubic feet, marking the 3rd consecutive price increase. The company owns an average interest of 10.4% in two straddle plants at Empress, Alberta. The company operates and is a 50% owner of Federated Pipe Lines Ltd. The company is committed to protecting the health and safety of all employees and the public, as well as preserving the quality of the environment

  7. Magnetic field induced quantum phase transitions in the two-impurity Anderson model

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Lujun [Los Alamos National Laboratory; Zhu, Jian - Xin [Los Alamos National Laboratory

    2010-11-17

    In the two-impurity Anderson model, the inter-impurity spin exchange interaction favors a spin singlet state between two impurities leading to the localization of quasiparticles. We show that a local uniform magnetic field can delocalize the quasiparticies to restore the Kondo resonance. This transition is found to be continuous, accompanied by not only the divergence of the staggered (anti ferromagnetic) susceptibility, but also the divergence of the uniform spin susceptibility. This implies that the magnetic field induced quantum phase transitions in Kondo systems are in favor of the local critical type.

  8. Critical exponent for the Anderson transition in the three-dimensional orthogonal universality class

    International Nuclear Information System (INIS)

    We report a careful finite size scaling study of the metal–insulator transition in Anderson's model of localization. We focus on the estimation of the critical exponent ν that describes the divergence of the localization length. We verify the universality of this critical exponent for three different distributions of the random potential: box, normal and Cauchy. Our results for the critical exponent are consistent with the measured values obtained in experiments on the dynamical localization transition in the quantum kicked rotor realized in a cold atomic gas. (paper)

  9. Transverse Anderson Localization in Disordered Glass Optical Fibers: A Review

    OpenAIRE

    Arash Mafi; Salman Karbasi; Koch, Karl W.; Thomas Hawkins; John Ballato

    2014-01-01

    Disordered optical fibers show novel waveguiding properties that can be used for various device applications, such as beam-multiplexed optical communications and endoscopic image transport. The strong transverse scattering from the transversely disordered optical fibers results in transversely confined beams that can freely propagate in the longitudinal direction, similar to conventional optical fibers, with the advantage that any point in the cross section of the fiber can be used for beam t...

  10. Controlling Anderson localization in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren;

    Quantum optics and quantum information technologies require enhancement of light-matter interaction by, for example, confining light in a small volume. A very recently demonstrated route towards light confinement makes use of multiple scattering of light and wave interference in disordered photonic...

  11. Localized excitation of magnetostatic surface spin waves in yttrium iron garnet by shorted coaxial probe detected via spin pumping and rectification effect

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Wee Tee, E-mail: a0046479@u.nus.edu; Ong, C. K. [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Peng, Bin [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-04-21

    We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films.

  12. Many-body localization: Entanglement and efficient numerical simulations

    Science.gov (United States)

    Pollmann, Frank

    Many-body localization (MBL) occurs in isolated quantum systems when Anderson localization persists in the presence of finite interactions. To understand this phenomenon, the development of new efficient numerical methods to find highly excited many-body eigenstates is essential. In this talk, we will discuss two complimentary approaches to simulate MBL systems: First, we introduce a variant of the density-matrix renormalization group (DMRG) method that obtains individual highly excited eigenstates of MBL systems to machine precision accuracy at moderate to large disorder. This method explicitly takes advantage of the local spatial structure and the low entanglement which is characteristic for MBL eigenstates. Second, we propose an approach to directly find an approximate compact representation of the diagonalizing unitary by using a variational unitary matrix-product operator.

  13. Geology of the Anderson Mesa quadrangle, Colorado

    Science.gov (United States)

    Cater, Fred W.; Withington, C.F.

    1953-01-01

    The Anderson Mesa quadrangle is one of the eighteen 7 1/2-minute quadrangles covering the principal carnotite-producing area of the southwestern Colorado. The geology of these quadrangles was mapped by the U.S. Geological Survey for the Atomic Energy Commission as part of a comprehensive study of carnotite deposits. The rocks exposed in the eighteenth quadrangles consist of crystalline rocks of pre-Cambrian age and sedimentary rocks that range in age from late Paleozoic to Quarternary. Over much of the area the sedimentary rocks are flat lying, but in places the rocks are disrupted by high-angle faults, and northwest-tending folds. Conspicuous among the folds are large anticlines having cores of intrusive slat and gypsum. Most of the carnotite deposits are confined to the Salt Wash sandstone member of the Jurassic Morrison formation. Within this sandstone, most of the deposits are spottily distributed through an arcuate zone known as the "Uravan Mineral Belt". Individual deposits range in size from irregular masses containing many thousands of tons. The ore consists of largely of sandstone selectively impregnated and in part replaced by uranium and vanadium minerals. Most of the deposits appear to be related to certain sedimentary structures in sandstones of favorable composition.

  14. Numerical verification of universality for the Anderson transition

    OpenAIRE

    Slevin, Keith; Ohtsuki, Tomi

    2001-01-01

    We analyze the scaling behavior of the higher Lyapunov exponents at the Anderson transition. We estimate the critical exponent and verify its universality and that of the critical conductance distribution for box, Gaussian and Lorentzian distributions of the random potential.

  15. Martin Anderson valis "Joonase lähetamise" / Priit Kuusk

    Index Scriptorium Estoniae

    Kuusk, Priit, 1938-

    2000-01-01

    M. Anderson kommenteeris ameerika muusikaajakirjas "Fanfare" viit talle kõige enam mõju avaldanud heliplaati, sh. R. Tobiase oratooriumi "Joonase lähetamine" CD-plaati (BIS). M. Andersoni huvist eesti muusika vastu

  16. 2011 South Carolina DNR Lidar: Tricounty (Anderson, Oconee, Pickens)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Towill Inc. collected LiDAR for over 3,500 square miles in York, Pickens, Anderson, and Oconee Counties in South Carolina. The nominal pulse spacing for this...

  17. Scaling of the conductance distribution near the Anderson transition

    OpenAIRE

    Slevin, Keith; Markoš, Peter; Ohtsuki, Tomi

    2002-01-01

    The single parameter scaling hypothesis is the foundation of our understanding of the Anderson transition. However, the conductance of a disordered system is a fluctuating quantity which does not obey a one parameter scaling law. It is essential to investigate the scaling of the full conductance distribution to establish the scaling hypothesis. We present a clear cut numerical demonstration that the conductance distribution indeed obeys one parameter scaling near the Anderson transition.

  18. Finite Size Scaling Analysis of the Anderson Transition

    OpenAIRE

    Kramer, Bernhard; MacKinnon, Angus; Ohtsuki, Tomi; Slevin, Keith

    2010-01-01

    This chapter describes the progress made during the past three decades in the finite size scaling analysis of the critical phenomena of the Anderson transition. The scaling theory of localisation and the Anderson model of localisation are briefly sketched. The finite size scaling method is described. Recent results for the critical exponents of the different symmetry classes are summarised. The importance of corrections to scaling are emphasised. A comparison with experiment is made, and a di...

  19. The Anderson transition: time reversal symmetry and universality

    OpenAIRE

    Slevin, Keith; Ohtsuki, Tomi

    1997-01-01

    We report a finite size scaling study of the Anderson transition. Different scaling functions and different values for the critical exponent have been found, consistent with the existence of the orthogonal and unitary universality classes which occur in the field theory description of the transition. The critical conductance distribution at the Anderson transition has also been investigated and different distributions for the orthogonal and unitary classes obtained.

  20. Ferromagnetic order in the one-dimensional Anderson lattice

    International Nuclear Information System (INIS)

    Using bosonization an effective Hamiltonian is derived for the one-dimensional Anderson lattice model in the Toulouse limit. The effective Hamiltonian exhibits ferromagnetic ground state in the intermediate coupling regime. - Highlights: • 1D Anderson lattice is bosonized in the Toulouse limit. • The obtained effective Hamiltonian exhibits ferromagnetic order. • Ferromagnetism is due to a double-exchange mechanism. • The ferromagnetic transition has been identified to be an order–disorder transition

  1. Evidence of excited state localization and static disorder in LH2 investigated by 2D-polarization single-molecule imaging at room temperature.

    Science.gov (United States)

    Tubasum, Sumera; Camacho, Rafael; Meyer, Matthias; Yadav, Dheerendra; Cogdell, Richard J; Pullerits, Tõnu; Scheblykin, Ivan G

    2013-12-01

    Two-dimensional polarization fluorescence imaging of single light harvesting complexes 2 (LH2) of Rps. acidophila was carried out to investigate the polarization properties of excitation and fluorescence emission simultaneously, at room temperature. In two separate experiments we excited LH2 with a spectrally narrow laser line matched to the absorption bands of the two chromophore rings, B800 and B850, thereby indirectly and directly triggering fluorescence of the B850 exciton state. A correlation analysis of the polarization modulation depths in excitation and emission for a large number of single complexes was performed. Our results show, in comparison to B800, that the B850 ring is a more isotropic absorber due to the excitonic nature of its excited states. At the same time, we observed a strong tendency for LH2 to emit with dipolar character, from which preferential localization of the emissive exciton, stable for minutes, is inferred. We argue that the observed effects can consistently be explained by static energetic disorder and/or deformation of the complex, with possible involvement of exciton self-trapping.

  2. Investigation of Anderson lattice behavior in Yb1-xLuxAl3

    International Nuclear Information System (INIS)

    Measurements of magnetic susceptibility χ(T), specific heat C(T), Hall coefficient RH(T), and Yb valence ν = 2 + nf [f-occupation number nf (T) determined from Yb L3 x-ray absorption measurements] were carried out on single crystals of Yb1-xLuxAl3. The low temperature anomalies observed in χ(T) and C(T) corresponding to an energy scale Tcoh ∼ 40 K in the intermediate valence, Kondo lattice compound YbAl3 are suppressed by Lu concentrations as small as 5% suggesting these low-T anomalies are extremely sensitive to disorder and, therefore, are a true coherence effect. By comparing the temperature dependence of various physical quantities to the predictions of the Anderson Impurity Model, the slow crossover behavior observed in YbAl3, in which the data evolve from a low-temperature coherent, Fermi-liquid regime to a high temperature local moment regime more gradually than predicted by the Anderson Impurity Model, appears to evolve to fast crossover behavior at x ∼ 0.7 where the evolution is more rapid than predicted. These two phenomena found in Yb1-xLuxAl3, i.e., the low-T anomalies and the slow/fast crossover behavior are discussed in relation to recent theories of the Anderson lattice

  3. Quantum resonances in selective rotational excitation of molecules with a sequence of ultrashort laser pulses

    CERN Document Server

    Zhdanovich, S; Floß, J; Averbukh, I Sh; Hepburn, J W; Milner, V

    2012-01-01

    The periodically kicked rotor is a paradigm system for studying classical and quantum chaos. In the quantum regime, the dynamics of the kicked rotor exhibit such fundamental phenomena as suppression of classical chaos, Anderson localization in angular momentum and quantum resonances in the accumulation of rotational energy. Even though these effects have been thoroughly studied with ultracold atoms in optical fields and Rydberg atoms in microwave fields, they have never been observed experimentally in a real rotational system. In this work we demonstrate and study the effect of quantum resonance in the rotational excitation of the simplest quantum rotor - a diatomic molecule. By using the techniques of high-resolution femtosecond pulse shaping and rotational state-resolved detection, we measure directly the rotational distribution of molecules interacting with a periodic sequence of ultrashort laser pulses. We show significant enhancement of population transfer from the ground to the excited rotational states...

  4. Superdiffusive transport and energy localization in disordered granular crystals

    Science.gov (United States)

    Martínez, Alejandro J.; Kevrekidis, P. G.; Porter, Mason A.

    2016-02-01

    We study the spreading of initially localized excitations in one-dimensional disordered granular crystals. We thereby investigate localization phenomena in strongly nonlinear systems, which we demonstrate to differ fundamentally from localization in linear and weakly nonlinear systems. We conduct a thorough comparison of wave dynamics in chains with three different types of disorder—an uncorrelated (Anderson-like) disorder and two types of correlated disorders (which are produced by random dimer arrangements)—and for two types of initial conditions (displacement excitations and velocity excitations). We find for strongly precompressed (i.e., weakly nonlinear) chains that the dynamics depend strongly on the type of initial condition. In particular, for displacement excitations, the long-time asymptotic behavior of the second moment m˜2 of the energy has oscillations that depend on the type of disorder, with a complex trend that differs markedly from a power law and which is particularly evident for an Anderson-like disorder. By contrast, for velocity excitations, we find that a standard scaling m˜2˜tγ (for some constant γ ) applies for all three types of disorder. For weakly precompressed (i.e., strongly nonlinear) chains, m˜2 and the inverse participation ratio P-1 satisfy scaling relations m˜2˜tγ and P-1˜t-η , and the dynamics is superdiffusive for all of the cases that we consider. Additionally, when precompression is strong, the inverse participation ratio decreases slowly (with η disorder, and the dynamics leads to a partial localization around the core and the leading edge of a propagating wave packet. For an Anderson-like disorder, displacement perturbations lead to localization of energy primarily in the core, and velocity perturbations cause the energy to be divided between the core and the leading edge. This localization phenomenon does not occur in the sonic-vacuum regime, which yields the surprising result that the energy is no longer

  5. Local SAR, global SAR, transmitter power and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design

    OpenAIRE

    Guérin, Bastien; Gebhardt, Matthias; Cauley, Steven; Adalsteinsson, Elfar; Wald, Lawrence L.

    2013-01-01

    Purpose We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global specific absorption rate (SAR), and maximum and average power for small flip-angle pTx (eight channels) spokes pulses in the torso at 3 T and in the head at 7 T. Methods We compare the trade-offs between the above-mentioned quantities using the L-curve method. We use a p...

  6. Superdiffusive transport and energy localization in disordered granular crystals.

    Science.gov (United States)

    Martínez, Alejandro J; Kevrekidis, P G; Porter, Mason A

    2016-02-01

    We study the spreading of initially localized excitations in one-dimensional disordered granular crystals. We thereby investigate localization phenomena in strongly nonlinear systems, which we demonstrate to differ fundamentally from localization in linear and weakly nonlinear systems. We conduct a thorough comparison of wave dynamics in chains with three different types of disorder-an uncorrelated (Anderson-like) disorder and two types of correlated disorders (which are produced by random dimer arrangements)-and for two types of initial conditions (displacement excitations and velocity excitations). We find for strongly precompressed (i.e., weakly nonlinear) chains that the dynamics depend strongly on the type of initial condition. In particular, for displacement excitations, the long-time asymptotic behavior of the second moment m̃(2) of the energy has oscillations that depend on the type of disorder, with a complex trend that differs markedly from a power law and which is particularly evident for an Anderson-like disorder. By contrast, for velocity excitations, we find that a standard scaling m̃(2)∼t(γ) (for some constant γ) applies for all three types of disorder. For weakly precompressed (i.e., strongly nonlinear) chains, m̃(2) and the inverse participation ratio P(-1) satisfy scaling relations m̃(2)∼t(γ) and P(-1)∼t(-η), and the dynamics is superdiffusive for all of the cases that we consider. Additionally, when precompression is strong, the inverse participation ratio decreases slowly (with ηwave packet. For an Anderson-like disorder, displacement perturbations lead to localization of energy primarily in the core, and velocity perturbations cause the energy to be divided between the core and the leading edge. This localization phenomenon does not occur in the sonic-vacuum regime, which yields the surprising result that the energy is no longer contained in strongly nonlinear waves but instead is spread across many sites. In this regime, the

  7. Efficient evaluation of dielectric response functions and calculations of ground and excited state properties beyond local Density Functional approaches

    Science.gov (United States)

    Lu, Deyu; Li, Yan; Rocca, Dario; Viet Nguyen, H.; Gygi, Francois; Galli, Giulia

    2010-03-01

    A recently developed technique to diagonalize iteratively dielectric matrices [1], is used to carry out efficient, ab-initio calculations of dispersion interactions, and excited state properties of nanostructures. In particular, we present results for the binding energies of weakly bonded molecular crystals [2], obtained at the EXX/RPA level of theory, and for absorption spectra of semiconducting clusters, obtained by an iterative solution of the Bethe-Salpeter equations [3]. We show that the ability to obtain the eigenmodes of dielectric matrices from Density Functional perturbation theory, without computing single particle excited states, greatly improves the efficiency of both EXX/RPA and many body perturbation theory [3,4] calculations and opens the way to large scale computations. [1] H. Wilson, F. Gygi and G. Galli, Phys. Rev. B , 78, 113303, 2008; and H. Wilson, D. Lu, F. Gygi and G. Galli, Phys. Rev. B, 79, 245106, 2009. [2] D. Lu, Y. Li, D. Rocca and G. Galli, Phys. Rev. Lett, 102, 206411, 2009; and Y. Li, D. Lu, V. Nguyen and G. Galli, J. Phys. Chem. C (submitted) [3] D. Rocca, D. Lu and G. Galli, submitted. [4] D. Lu, F. Gygi and G. Galli, Phys. Rev. Lett. 100, 147601, 2008. Work was funded by DOE/Scidac DE-FC02-06ER25794 and DOE/BES DE-FG02-06ER46262.

  8. A scaling limit theorem for the parabolic Anderson model with exponential potential

    CERN Document Server

    Lacoin, Hubert

    2010-01-01

    The parabolic Anderson problem is the Cauchy problem for the heat equation with random potential and localized initial condition. In this paper we consider potentials which are constant in time and independent exponentially distributed in space. We study the growth rate of the total mass of the solution in terms of weak and almost sure limit theorems, and the spatial spread of the mass in terms of a scaling limit theorem. The latter result shows that in this case, just like in the case of heavy tailed potentials, the mass gets trapped in a single relevant island with high probability.

  9. The band-centre anomaly in the 1D Anderson model with correlated disorder

    International Nuclear Information System (INIS)

    We study the band-centre anomaly in the one-dimensional Anderson model with weak correlated disorder. Our analysis is based on the Hamiltonian map approach; the correspondence between the discrete model and its continuous counterpart is discussed in detail. We obtain analytical expressions of the localization length and of the invariant measure of the phase variable, valid for energies in a neighbourhood of the band centre. By applying these general results to specific forms of correlated disorder, we show how correlations can enhance or suppress the anomaly at the band centre. (paper)

  10. Interpretation of high-dimensional numerical results for the Anderson transition

    International Nuclear Information System (INIS)

    The existence of the upper critical dimension dc2 = 4 for the Anderson transition is a rigorous consequence of the Bogoliubov theorem on renormalizability of φ4 theory. For d ≥ 4 dimensions, one-parameter scaling does not hold and all existent numerical data should be reinterpreted. These data are exhausted by the results for d = 4, 5 from scaling in quasi-one-dimensional systems and the results for d = 4, 5, 6 from level statistics. All these data are compatible with the theoretical scaling dependences obtained from Vollhardt and Wolfle’s self-consistent theory of localization. The widespread viewpoint that dc2 = ∞ is critically discussed

  11. Localization of Spinons in Random Majumdar-Ghosh Chains

    Science.gov (United States)

    Roux, Guillaume; Lavarelo, Arthur

    2014-03-01

    We study the effect of disorder on frustrated dimerized spin-1/2 chains at the Majumdar-Ghosh point. Using variational methods and density-matrix renormalization group approaches, we identify two localization mechanisms for spinons which are the deconfined fractional elementary excitations of these chains. The first one belongs to the Anderson localization class and dominates at the random Majumdar-Ghosh point. There, spinons remain gapped and localize in Lifshitz states whose localization length is analytically obtained. The other mechanism is a random confinement mechanism which induces an effective interaction between spinons and brings the initially gapped antiferromagnetic chain into a gapless and partially polarized phase for arbitrarily small disorder. This Imry-Ma mechanism induces domains which statistics is analyzed. Last, the connection to the real-space renormalization group method suited for the strong disorder limit is discussed.

  12. Magnetic Moments of Chromium-Doped Gold Clusters: The Anderson Impurity Model in Finite Systems

    CERN Document Server

    Hirsch, K; Langenberg, A; Niemeyer, M; Langbehn, B; Möller, T; Terasaki, A; Issendorff, B v; Lau, J T

    2013-01-01

    The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy and density functional theory study of size-selected free chromium-doped gold clusters. The observed size-dependence of the local magnetic moment can essentially be understood in terms of the Anderson impurity model. Electronic shell closure in the host metal minimizes the interaction of localized impurity states with the confined free electron gas and preserves the full magnetic moment of $\\unit[5]{\\mu_B}$ in $\\mathrm{CrAu}_{2}^{+}$ and $\\mathrm{CrAu}_{6}^{+}$ clusters. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas generally stabilizes the local magnetic moment of the impurity.

  13. Conservation laws, radiative decay rates, and excited state localization in organometallic complexes with strong spin-orbit coupling

    CERN Document Server

    Powell, B J

    2015-01-01

    There is longstanding fundamental interest in 6-fold coordinated $d^6$ ($t_{2g}^6$) transition metal complexes such as [Ru(bpy)$_3$]$^{2+}$ and Ir(ppy)$_3$, particularly their phosphorescence. This interest has increased with the growing realisation that many of these complexes have potential uses in applications including photovoltaics, imaging, sensing, and light-emitting diodes. In order to design new complexes with properties tailored for specific applications a detailed understanding of the low-energy excited states, particularly the lowest energy triplet state, $T_1$, is required. Here we describe a model of pseudo-octahedral complexes based on a pseudo-angular momentum representation and show that the predictions of this model are in excellent agreement with experiment - even when the deviations from octahedral symmetry are large. This model gives a natural explanation of zero-field splitting of $T_1$ and of the relative radiative rates of the three sublevels in terms of the conservation of time-revers...

  14. Unified parameter for localization in isotope-selective rotational excitation of diatomic molecules using a train of optical pulses

    OpenAIRE

    Matsuoka, Leo

    2015-01-01

    We obtained a simple theoretical unified parameter for the characterization of rotational population propagation of diatomic molecules in a periodic train of resonant optical pulses. The parameter comprises the peak intensity and interval between the pulses, and the level energies of the initial and final rotational states of the molecule. Using the unified parameter, we can predict the upper and lower boundaries of probability localization on the rotational level network, including the effec...

  15. An Anderson Impurity Model for Efficient Sampling of Adiabatic Potential Energy Surfaces of Transition Metal Complexes

    CERN Document Server

    La Bute-Montiago X; Cox, D L

    2004-01-01

    We present a model intended for rapid sampling of ground and excited state potential energy surfaces for first-row transition metal active sites. The method is computationally inexpensive and is suited for dynamics simulations where (1) adiabatic states are required "on-the-fly" and (2) the primary source of the electronic coupling between the diabatic states is the perturbative spin-orbit interaction among the 3d electrons. The model Hamiltonian we develop is a variant of the Anderson impurity model and achieves efficiency through a physically motivated basis set reduction based on the large value of the d-d Coulomb interaction U_{d} and a Lanczos matrix diagonalization routine to solve for eigenvalues. The model parameters are constrained by fits to the partial density of states (PDOS) obtained from ab initio density functional theory calculations. For a particular application of our model we focus on electron-transfer occuring between cobalt ions solvated by ammonium, incorporating configuration interactio...

  16. Analytic Flow Equations for the Fermi Liquid Parameters of the Anderson Impurity Model.

    Science.gov (United States)

    Pandis, Vassilis; Hewson, Alex C

    2015-08-14

    The low temperature behavior of a Fermi liquid can be described in terms of quasiparticle excitations that are in 1-1 correspondence with those of the noninteracting system. Because of adiabatic continuity, the Landau parameters, which describe the interactions between the quasiparticles, must evolve continuously as the interactions are turned on and be described by a set of flow equations. For strongly correlated electron systems it is not possible to follow this flow in perturbation theory when the interactions become strong. We explore the idea here of overcoming this problem by renormalizing the quasiparticles in this flow using a renormalized perturbation theory. This approach is tested in the case of a single impurity Anderson model. Analytic flow equations are derived which give excellent results for the Landau parameters in the strong correlation regime.

  17. Anderson-Witting transport coefficients for flows in general relativity

    CERN Document Server

    Ambrus, Victor E

    2016-01-01

    The transport coefficients induced by the Anderson-Witting approximation of the collision term in the relativistic Boltzmann equation are derived for close to equilibrium flows in general relativity. Using the tetrad formalism, it is shown that the expression for these coefficients is the same as that obtained on flat space-time, in agreement with the generalized equivalence principle.

  18. Spectral density method to Anderson-Holstein model

    International Nuclear Information System (INIS)

    Two-parameter spectral density function of a magnetic impurity electron in a non-magnetic metal is calculated within the framework of the Anderson-Holstein model using the spectral density approximation method. The effect of electron-phonon interaction on the spectral function is investigated

  19. Louisa Garrett Anderson (1873-1943), surgeon and suffragette.

    Science.gov (United States)

    Geddes, Jennian F

    2008-11-01

    Louisa Garrett Anderson, daughter of Britain's first woman doctor, has been largely forgotten today despite the fact that her contribution to the women's movement was as great as that of her mother. Recognized by her contemporaries as an important figure in the suffrage campaign, Anderson chose to lend her support through high-profile action, being one of the few women doctors in her generation who risked their professional as well as their personal reputation in the fight for women's rights by becoming a suffragette - in her case, even going so far as to spend a month in prison for breaking a window on a demonstration. On the outbreak of war, with only the clinical experience she had gained as outpatient surgeon in a women's hospital, Anderson established a series of women-run military hospitals where she was a Chief Surgeon. The most successful was the Endell Street Military Hospital in London, funded by the Royal Army Medical Corps and the only army hospital ever to be run and staffed entirely by women. Believing that a doctor had an obligation to take a lead in public affairs, Anderson continued campaigning for women's issues in the unlikely setting of Endell Street, ensuring that their activities remained in the public eye through constant press coverage. Anderson's achievement was that her work played no small part in expunging the stigma of the militant years in the eyes of the public and - more importantly - was largely instrumental in putting women doctors on equal terms with their male colleagues. PMID:18952990

  20. Anderson transition on the Cayley tree as a traveling wave critical point for various probability distributions

    International Nuclear Information System (INIS)

    For Anderson localization on the Cayley tree, we study the statistics of various observables as a function of the disorder strength W and the number N of generations. We first consider the Landauer transmission TN. In the localized phase, its logarithm follows the traveling wave form TN≅(ln TN)-bar + ln t* where (i) the disorder-averaged value moves linearly (ln(TN))-bar≅-N/ξloc and the localization length diverges as ξloc∼(W-Wc)-νloc with νloc = 1 and (ii) the variable t* is a fixed random variable with a power-law tail P*(t*) ∼ 1/(t*)1+β(W) for large t* with 0 N are governed by rare events. In the delocalized phase, the transmission TN remains a finite random variable as N → ∞, and we measure near criticality the essential singularity (ln(T∞))-bar∼-|Wc-W|-κT with κT ∼ 0.25. We then consider the statistical properties of normalized eigenstates Σx|ψ(x)|2 = 1, in particular the entropy S = -Σx|ψ(x)|2ln |ψ(x)|2 and the inverse participation ratios (IPR) Iq = Σx|ψ(x)|2q. In the localized phase, the typical entropy diverges as Styp∼( W-Wc)-νS with νS 1.5, whereas it grows linearly as Styp(N) ∼ N in the delocalized phase. Finally for the IPR, we explain how closely related variables propagate as traveling waves in the delocalized phase. In conclusion, both the localized phase and the delocalized phase are characterized by the traveling wave propagation of some probability distributions, and the Anderson localization/delocalization transition then corresponds to a traveling/non-traveling critical point. Moreover, our results point toward the existence of several length scales that diverge with different exponents ν at criticality

  1. Detection of Influenza Virus with Specific Subtype by Using Localized Surface Plasmons Excited on a Flat Metal Surface

    Science.gov (United States)

    Ning, Jun; Nagata, Kotaro; Ainai, Akira; Hasegawa, Hideki; Kano, Hiroshi

    2013-08-01

    We report on a method to determine subtype of influenza viruses by using surface plasmons localized in microscopic region on a flat metal surface. In this method, refractive index variation arisen from interactions between viruses and their monoclonal antibodies is measured. The developed sensor shows stability of refractive index in the order of 10-4 against sample exchange. In our experiment, A/H1N1 viruses are distinguished from A/H3N2 viruses by using monoclonal antibodies immobilized on the metal surface. Since the measurement probe has the volume of ˜6 al, the method has potential to handle multiple subtypes in the measurement of a sample with ultra small volume.

  2. Modified Bose-Einstein and Fermi-Dirac statistics if excitations are localized on an intermediate length scale: Applications to non-Debye specific heat

    Science.gov (United States)

    Chamberlin, Ralph V.; Davis, Bryce F.

    2013-10-01

    Disordered systems show deviations from the standard Debye theory of specific heat at low temperatures. These deviations are often attributed to two-level systems of uncertain origin. We find that a source of excess specific heat comes from correlations between quanta of energy if excitations are localized on an intermediate length scale. We use simulations of a simplified Creutz model for a system of Ising-like spins coupled to a thermal bath of Einstein-like oscillators. One feature of this model is that energy is quantized in both the system and its bath, ensuring conservation of energy at every step. Another feature is that the exact entropies of both the system and its bath are known at every step, so that their temperatures can be determined independently. We find that there is a mismatch in canonical temperature between the system and its bath. In addition to the usual finite-size effects in the Bose-Einstein and Fermi-Dirac distributions, if excitations in the heat bath are localized on an intermediate length scale, this mismatch is independent of system size up to at least 106 particles. We use a model for correlations between quanta of energy to adjust the statistical distributions and yield a thermodynamically consistent temperature. The model includes a chemical potential for units of energy, as is often used for other types of particles that are quantized and conserved. Experimental evidence for this model comes from its ability to characterize the excess specific heat of imperfect crystals at low temperatures.

  3. Comparative study of many-body perturbation theory and time-dependent density functional theory in the out-of-equilibrium Anderson model

    OpenAIRE

    Uimonen, A. -M.; Khosravi, E.; Stan, A.; Stefanucci, Gianluca; Kurth, S.; Van Leeuwen, R; Gross, E. K. U.

    2011-01-01

    We study time-dependent electron transport through an Anderson model. The electronic interactions on the impurity site are included via the self-energy approximations at Hartree-Fock (HF), second Born (2B), GW, and T-matrix levels as well as within a time-dependent density functional (TDDFT) scheme based on the adiabatic Bethe-ansatz local density approximation (ABALDA) for the exchange-correlation potential. The Anderson model is driven out of equilibrium by applying a bias to the leads, and...

  4. Delocalization and Sensitivity of Quantum Wavepacket in Coherently Perturbed Kicked Anderson Model

    Directory of Open Access Journals (Sweden)

    Hiroaki Yamada

    2004-03-01

    Full Text Available Abstract: We consider quantum diffusion of the initially localized wavepacket in one-dimensional kicked disordered system with classical coherent perturbation. The wavepacket localizes in the unperturbed kicked Anderson model. However, the wavepacket get delocalized even by coupling with monochromatic perturbation. We call the state "dynamically delocalized state". It is numerically shown that the delocalized wavepacket spread obeying diffusion law, and the perturbation strength dependence of the diffusion rate is given. The sensitivity of the delocalized state is also shown by the time-reversal experiment after random change in phase of the wavepacket. Moreover, it is found that the diffusion strongly depend on the initial phase of the perturbation. We discuss a relation between the "classicalization" of the quantum wave packet and the time-dependence of the initial phase dependence. The complex structure of the initial phase dependence is related to the entropy production in the quantum system.

  5. Time-dependent Mott transition in the periodic Anderson model with nonlocal hybridization

    Science.gov (United States)

    Hofmann, Felix; Potthoff, Michael

    2016-08-01

    The time-dependent Mott transition in a periodic Anderson model with off-site, nearest-neighbor hybridization is studied within the framework of nonequilibrium self-energy functional theory. Using the two-site dynamical-impurity approximation, we compute the real-time dynamics of the optimal variational parameter and of different observables initiated by sudden quenches of the Hubbard-U and identify the critical interaction. The time-dependent transition is orbital selective, i.e., in the final state, reached in the long-time limit after the quench to the critical interaction, the Mott gap opens in the spectral function of the localized orbitals only. We discuss the dependence of the critical interaction and of the final-state effective temperature on the hybridization strength and point out the various similarities between the nonequilibrium and the equilibrium Mott transition. It is shown that these can also be smoothly connected to each other by increasing the duration of a U-ramp from a sudden quench to a quasi-static process. The physics found for the model with off-site hybridization is compared with the dynamical Mott transition in the single-orbital Hubbard model and with the dynamical crossover found for the real-time dynamics of the conventional Anderson lattice with on-site hybridization.

  6. Experimental determination of critical exponents in Anderson localisation of light

    OpenAIRE

    Aegerter, Christof M.; Störzer, Martin; Maret, Georg

    2006-01-01

    Anderson localisation predicts a phase transition in transport, where the diffuse spread of particles comes to a halt with the introduction of a critical amount of disorder. This is due to constructive interference on closed multiple scattering loops which leads to a renormalisation of the diffusion coefficient. This can be described by a slowing-down of diffusion, where the diffusion coefficient decreases with time according to a power law with an exponent a. In the case of strong localisati...

  7. Non-random perturbations of the Anderson Hamiltonian

    CERN Document Server

    Molchanov, S

    2010-01-01

    The Anderson Hamiltonian $H_0=-\\Delta+V(x,\\omega)$ is considered, where $V$ is a random potential of Bernoulli type. The operator $H_0$ is perturbed by a non-random, continuous potential $-w(x) \\leq 0$, decaying at infinity. It will be shown that the borderline between finitely, and infinitely many negative eigenvalues of the perturbed operator, is achieved with a decay of $O(\\ln^{-2/d} |x|)$.

  8. Perturbative Interpretation of Adaptive Thouless-Anderson-Palmer Free Energy

    Science.gov (United States)

    Yasuda, Muneki; Takahashi, Chako; Tanaka, Kazuyuki

    2016-07-01

    In conventional well-known derivation methods for the adaptive Thouless-Anderson-Palmer (TAP) free energy, special assumptions that are difficult to mathematically justify except in some mean-field models, must be made. Here, we present a new adaptive TAP free energy derivation method. Using this derivation technique, without any special assumptions, the adaptive TAP free energy can be simply obtained as a high-temperature expansion of the Gibbs free energy.

  9. Perturbative Interpretation of Adaptive Thouless-Anderson-Palmer Free Energy

    OpenAIRE

    Yasuda, Muneki; Takahashi, Chako; Tanaka, Kazuyuki

    2016-01-01

    In conventional well-known derivation methods for the adaptive Thouless-Anderson-Palmer (TAP) free energy, special assumptions that are difficult to mathematically justify except in some mean-field models, must be made. Here, we present a new adaptive TAP free energy derivation method. Using this derivation technique, without any special assumptions, the adaptive TAP free energy can be simply obtained as a high-temperature expansion of the Gibbs free energy.

  10. Smoothed universal correlations in the two-dimensional Anderson model

    OpenAIRE

    Uski, V.; Mehlig, B.; R.A. Romer; Schreiber, M.

    1998-01-01

    We report on calculations of smoothed spectral correlations in the two-dimensional Anderson model for weak disorder. As pointed out in (M. Wilkinson, J. Phys. A: Math. Gen. 21, 1173 (1988)), an analysis of the smoothing dependence of the correlation functions provides a sensitive means of establishing consistency with random matrix theory. We use a semiclassical approach to describe these fluctuations and offer a detailed comparison between numerical and analytical calculations for an exhaust...

  11. Spectra of Anderson Type Models with Decaying Randomness

    Indian Academy of Sciences (India)

    M Krishna; K B Sinha

    2001-05-01

    In this paper we consider some Anderson type models, with free parts having long range tails with the random perturbations decaying at different rates in different directions and prove that there is a.c. spectrum in the model which is pure. In addition, we show that there is pure point spectrum outside some interval. Our models include potentials decaying in all directions in which case absence of singular continuous spectrum is also shown.

  12. Changes of the local magnetic properties of the optically excited Nd3+ ions and their manifestation in the near IR spectra of the Nd0.5Gd0.5Fe3(BO3)4 crystal

    Science.gov (United States)

    Malakhovskii, A. V.; Gnatchenko, S. L.; Kachur, I. S.; Piryatinskaya, V. G.; Temerov, V. L.

    2016-02-01

    Polarized absorption spectra of f-f transitions 4I9/2 → 4F3/2 and (2H9/2 + 4F5/2) in the Nd3+ ion in the Nd0.5Gd0.5Fe3(BO3)4 single crystal were studied as a function of temperature in the range of 2-40 K and as a function of magnetic field in the range of 0-65 kOe at 2 K. It was found out that the selection rules for f-f electron transitions substantially changed in the magnetically ordered state of the crystal, and they strongly depended on the orientation of the Fe and Nd ions magnetic moments relative to the light polarization. The splitting of the ground and excited states of the Nd3+ ion in the exchange field of the Fe sublattice were determined. It was revealed that the value of the exchange splitting (the exchange interaction) in the excited states did not correlate with the theoretical Landé factors. The Landé factors of the excited states were experimentally found. In general, the local magnetic properties in the vicinity of the excited ion depend substantially on its electron state. In particular: (1) in one of the excited states a weak ferromagnetic moment appears, (2) the changes of type of the local magnetic anisotropy take place in some excited states, and (3) in some excited states the energetically favorable orientation of the Nd3+ ion magnetic moment is opposite to that in the ground state. In some excited states the nonequivalent Nd3+ centers were found out.

  13. Localized Etching of a Polyimide Film by an Atmospheric-Pressure Radio Frequency Microplasma Excited by a 100-µm-φ Metal Pipe Electrode

    Science.gov (United States)

    Yoshiki, Hiroyuki

    2010-08-01

    Atmospheric-pressure He and Ar microplasmas (µ-plasmas) have been generated by a 14 MHz radio-frequency (RF) discharge using a metal narrow pipe electrode with an outer diameter of 100 µm. The metal pipe acts as both a powered electrode and a gas nozzle. The discharge mode changed from a corona discharge to a glow discharge and finally to a thermal spot arc discharge with decreasing discharge gap between the pipe electrode and the grounded plate as well as with increasing RF power. The Ar glow µ-plasma was applied to the localized etching of a polyimide film with a thickness of 0.025 mm in air ambient. The etched spot showed an isotropic profile having a gradual slope with a full width at half maximum of approximately 170 µm. The etching rate was approximately 3 µm/s at an RF power of 1.5 W. The optical emission spectrum exhibited second-positive N2 molecular bands and atomic oxygen lines (777 and 845 nm) as well as many Ar atomic lines. It appears that the energetic N2 molecules and UV photons radiated from the excitation states of N2 broke C-C and C-H bonds and then O radicals reacted with the hydrocarbon fragments to produce CO2 and H2O. Consequently, isotropic chemical etching was achieved.

  14. 五强溪电厂机组进口励磁系统的国产化改造分析%Localization of Imported Unit Excitation System of Wu Qiang Xi Power Plant

    Institute of Scientific and Technical Information of China (English)

    易赤宇

    2014-01-01

    本文主要介绍五强溪电厂机组进口励磁系统国产化改造的成功应用,以及改造情况、实施效果的对比分析。%This paper nainly introduces the successful localization of the imported unit excitation system of Wu Qiang Xi Power Plant,and presents a comparative analysis of the localization condition and application effect.

  15. Conductance distribution at criticality: one-dimensional Anderson model with random long-range hopping

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, A. [Instituto de Fisica, Universidad Autonoma de Puebla, Apartado Postal J-48, Puebla 72570 (Mexico); Gopar, V. [Departamento de Fisica Teorica and Instituto de Biocomputacion y Fisica de Sistemas Complejos (BIFI), Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Varga, I. [Elmeleti Fizika Tanszek, Fizikai Intezet, Budapesti Mueszaki es Gazdasagtudomanyi Egyetem, 1521 Budapest (Hungary); Fachbereich Physik und Wissenschaftliches Zentrum fuer Materialwissenschaften, Philipps Universitaet Marburg, 35032 Marburg (Germany)

    2009-12-15

    We study numerically the conductance distribution function w(T) for the one-dimensional Anderson model with random long-range hopping described by the Power-law Banded Random Matrix model at criticality. We concentrate on the case of two single-channel leads attached to the system. We observe a smooth transition from localized to delocalized behavior in the conductance distribution by increasing b, the effective bandwidth of the model. Also, for b < 1 we show that w(ln T/T{sub typ}) is scale invariant, where T{sub typ} = exp left angle ln T right angle is the typical value of T. Moreover, we find that for T < T{sub typ}, w(ln T/T{sub typ}) shows a universal behavior proportional to (T/T{sub typ}){sup -1/2}. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  16. The parabolic Anderson model and long-range percolation

    OpenAIRE

    Erhard, Dirk

    2014-01-01

    This thesis has two parts. The first part deals with the parabolic Anderson model, which is a stochastic differential equation. It models the evolution of a field of particles performing independent simple random walks with binary branching. The focus of this work is on the exponential growth rate of the solution, where several basic properties are derived. The second part deals with two long-range percolation models. The occupied set of the first model is obtained by taking the union of a co...

  17. Note: Work function change measurement via improved Anderson method

    International Nuclear Information System (INIS)

    We propose the modification to the Anderson method of work function change (Δϕ) measurements. In this technique, the kinetic energy of the probing electrons is already low enough for non-destructive investigation of delicate molecular systems. However, in our implementation, all electrodes including filament of the electron gun are polarized positively. As a consequence, electron bombardment of any elements of experimental system is eliminated. Our modification improves cleanliness of the ultra-high vacuum system. As an illustration of the solution capabilities, we present Δϕ of the Ag(100) surface induced by cobalt phthalocyanine layers

  18. Nuclear excitation in plasma

    International Nuclear Information System (INIS)

    4 main electromagnetic excitation processes of atomic nuclei in hot dense plasma are reviewed: the black body photon absorption, the electron inelastic scattering, the nuclear excitation by electron capture (NEEC effect) and the nuclear excitation by electron transition (NEET effect). Experimental results on Ta181m are commented and an experiment showing the NEEC effect on Fe57 is described. A model including all the phenomena of excitation and de-excitation of a nuclear state in plasma, has been developed. Predictions about the evolution of the life-time of a nuclear excited state as a function of the temperature and density are made. A complete calculation of the NEET effect of the first excited state of U235 in a local thermodynamic equilibrium plasma is presented. Some experimental works on the excitation of U235m in a laser-produced plasma are discussed. The NEET effect on Hg201 in a laser-produced plasma is also considered in both theoretical and experimental aspects

  19. Paleontological analysis of a lacustrine carbonaceous uranium deposit at the Anderson mine, Date Creek basin, west-central Arizona (U.S.A.)

    Science.gov (United States)

    Otton, J.K.; Bradbury, J.P.; Forester, R.M.; Hanley, J.H.

    1990-01-01

    The Tertiary sedimentary sequence of the Date Creek basin area of Arizona is composed principally of intertonguing alluvial-fan and lacustrine deposits. The lacustrine rocks contain large intermediate- to, locally, high-grade uranium deposits that form one of the largest uranium resources in the United States (an estimated 670,000 tons of U3O8 at an average grade of 0.023% is indicated by drilling to date). At the Anderson mine, about 50,000 tons of U3O8 occurs in lacustrine carbonaceous siltstones and mudstones (using a cutoff grade of 0.01%). The Anderson mine constitutes a new class of ore deposit, a lacustrine carbonaceous uranium deposit. Floral and faunal remains at the Anderson mine played a critical role in creating and documenting conditions necessary for uranium mineralization. Organic-rich, uraniferous rocks at the Anderson mine contain plant remains and ostracodes having remarkably detailed preservation of internal features because of infilling by opaline silica. This preservation suggests that the alkaline lake waters in the mine area contained high concentrations of dissolved silica and that silicification occurred rapidly, before compaction or cementation of the enclosing sediment. Uranium coprecipitated with the silica. Thinly laminated, dark-colored, siliceous beds contain centric diatoms preserved with carbonaceous material suggesting that lake waters at the mine were locally deep and anoxic. These alkaline, silica-charged waters and a stagnant, anoxic environment in parts of the lake were necessary conditions for the precipitation of large amounts of uranium in the lake-bottom sediments. Sediments at the Anderson mine contain plant remains and pollen that were derived from diverse vegetative zones suggesting about 1500 m of relief in the area at the time of deposition. The pollen suggests that the valley floor was semiarid and subtropical, whereas nearby mountains supported temperate deciduous forests. ?? 1990.

  20. Anderson transition of Bogoliubov quasiparticles in the quasiperiodic kicked rotor

    OpenAIRE

    Vermersch, Benoit; Delande, Dominique; Garreau, Jean Claude

    2014-01-01

    We study the dynamics of Bogoliubov excitations of a Bose-Einstein condensate in the quasiperiodic kicked rotor. In the weakly interacting regime, the condensate is stable and both the condensate and the excitations undergo a phase transition from a quasilocalized to a diffusive regime. The corresponding critical exponents are identical for the condensate and the excitations, and compare very well with the value $\

  1. Price-Anderson Act - the third decade. Report to Congress

    International Nuclear Information System (INIS)

    Subsection 170p. of the Atomic Energy Act of 1954, as amended, requires that the Commission submit to the Congress by August 1, 1983, a detailed report on the need for continuation or modification of Section 170 of the Act, the Price-Anderson provisions. The report is divided into four sections with detailed subject reports appended to the main report. Sections I through III include an examination of issues that the Commission was required by statute to study (i.e., condition of the nuclear industry, state of knowledge of nuclear safety, and availability of private insurance), and discussion of other issues of interest and importance to the Congress and to the public. The subjects covered are as follows: (1) overview of the Price-Anderson system; (2) the state of knowledge of nuclear safety; (3) availability of private insurance; (4) conditions of the nuclear industry; (5) causality and proof of damages; (6) limitation of liability and subsidy; and (7) a proposal that would provide for removal of the limitation of liability but with limited annual liability payments. Section IV of the report contains conclusions and recommendations. Section V contains a bibliography

  2. Excitation-dependent variation in local symmetry in Ba2Mg(BO3)2 evidenced by Eu3+ luminescent structural probe

    Science.gov (United States)

    Jayakiruba, S.; Kumar, Gautam; Lakshminarasimhan, N.

    2016-05-01

    Eu3+ luminescence was studied in Ba2Mg(BO3)2 by selectively substituting at Mg site. The parent host Ba2Mg(BO3)2 and Ba2Mg0.9Eu0.05Li0.05(BO3)2 were synthesized by conventional solid state reaction method. Their isostructural nature was confirmed using powder X-ray diffraction technique. The photoluminescence excitation spectrum of Eu3+ exhibited a broad Eu3+sbnd O2- charge transfer band with a maximum at 253 nm along with other excitation transitions. The emission characteristics of Eu3+ were found to be excitation wavelength-dependent. The equally intense magnetic and electric dipole transitions for excitation under longer wavelengths showed the presence of Eu3+ at a site with non-inversion symmetry. Excitation using 253 nm resulted in the predominant magnetic dipole transition revealing Eu3+ at a site with inversion symmetry. The difference in the relative intensities of magnetic and electric dipole transitions originates from the change in symmetry around Eu3+ in Ba2Mg(BO3)2 under different excitations.

  3. Possible Anderson transition below two dimensions in disordered systems of noninteracting electrons

    OpenAIRE

    Asada, Yoichi; Slevin, Keith; Ohtsuki, Tomi

    2005-01-01

    We investigate the possibility of an Anderson transition below two dimensions in disordered systems of non-interacting electrons with symplectic symmetry. Numerical analysis of energy level statistics and conductance statistics on Sierpinski carpets with spin-orbit coupling indicates the occurrence of an Anderson transition below two dimensions.

  4. 75 FR 34170 - Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC...

    Science.gov (United States)

    2010-06-16

    ... Assistance on March 18, 2010, applicable to workers of Plastic Omnium Automotive Exteriors, LLC, Anderson, South Carolina. The notice was published in the Federal Register April 23, 2010 (75 FR 21356). The... Employment and Training Administration Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic...

  5. Award for Distinguished Scientific Early Career Contributions to Psychology: Adam K. Anderson

    Science.gov (United States)

    American Psychologist, 2009

    2009-01-01

    Adam K. Anderson, recipient of the Award for Distinguished Scientific Early Career Contributions to Psychology, is cited for his outstanding contribution to understanding the representation of emotion and its influence on cognition. By combining psychological and neuroscience techniques with rigorous and creative experimental designs, Anderson has…

  6. Absorption and emission in quantum dots: Fermi surface effects of Anderson excitons

    Science.gov (United States)

    Helmes, R. W.; Sindel, M.; Borda, L.; von Delft, J.

    2005-09-01

    Recent experiments measuring the emission of exciton recombination in a self-organized single quantum dot (QD) have revealed that different effects occur when the wetting layer surrounding the QD becomes filled with electrons because the resulting Fermi sea can hybridize with the local electron levels on the dot. Motivated by these experiments, we study an extended Anderson model, which describes a local conduction band level coupled to a Fermi sea, but also includes a local valence band level. We are interested, in particular, in how many-body correlations resulting from the presence of the Fermi sea affect the absorption and emission spectra. Using Wilson’s numerical renormalization group method, we calculate the zero-temperature absorption (emission) spectrum of a QD, which starts from (ends up in) a strongly correlated Kondo ground state. We predict two features: First, we find that the spectrum shows a power-law divergence close to the threshold, with an exponent that can be understood by analogy to the well-known x-ray edge absorption problem. Second, the threshold energy ω0 —below which no photon is absorbed (above which no photon is emitted)—shows a marked, monotonic shift as a function of the exciton binding energy Uexc .

  7. PWA90 Workshop : Marking the Scientific Accomplishments of Philip W. Anderson

    CERN Document Server

    Coleman, PIers; Kotliar, Gabi; Ong, Phuan; Stein, Daniel L; Yu, Clare; PWA90 : a lifetime of emergence

    2016-01-01

    In a remarkable career spanning more than six decades, Philip W Anderson has made many fundamental contributions to physics. As codified in his oft-quoted phrase "More is Different", Anderson has been the most forceful and persuasive proponent of the radical, but now ubiquitous, viewpoint of emergent phenomena: truly fundamental concepts that can and do emerge from studies of Nature at each layer of complexity or energy scale. Anderson's ideas have also extended deeply into other areas of physics, including the Anderson–Higgs mechanism and the dynamics of pulsars. PWA90: A Lifetime of Emergence is a volume of original scientific essays and personal reminiscences of Philip W Anderson by experts in the field, that were presented as part of "PWA90: Emergent Frontiers of Condensed Matter" meeting held at Princeton in December 2013 to highlight Anderson's contributions to physics.

  8. Excited states

    CERN Document Server

    Lim, Edward C

    1974-01-01

    Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

  9. Nuclear structure studies using the high resolution spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility. Progress report

    International Nuclear Information System (INIS)

    The research is concerned with obtaining detailed microscopic nuclear structure information (both ground state and excited state) through analyses of experimental data which have been, and which will be, obtained using the High Resolution Spectrometer (HRS) at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). Five types of experimental/theoretical studies constitute the present research program: (1) those providing nucleon-nucleon (N-N) data which describe the free N-N interaction at small momentum transfer (the starting point for analyses based on the impulse approximation), (2) those providing data which determine how the nuclear medium modifies the free amplitudes (leading to effective amplitudes for analyses based on the impulse approximation), (3) those which provide data that validate fundamental ideas implicit in the formulation of the microscopic theories, (4) those which provide data to be analyzed to provide detailed nuclear structure information, and (5) those which provide critical evaluations of the formulations of the microscopic theories themselves

  10. Nuclear structure studies using the High Resolution Spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility. Progress report

    International Nuclear Information System (INIS)

    The research described in this document is concerned with obtaining detailed microscopic nuclear structure information (both ground state and excited state) through analysis of experimental data which have been, and which will be, obtained using the High Resolution Spectrometer (HRS) at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). Three types of experiments and related theoretical work constitute the research programs: (1) those which provide nucleon-nucleon data to determine the key amplitudes required for microscopic analysis of intermediate energy p-nucleus elastic and inelastic scattering data, (2) those which provide data that validate fundamental ideas implicit in the formulation of the microscopic theories, and (3) those which provide data to be analyzed to provide detailed nuclear structure information

  11. The parabolic Anderson model random walk in random potential

    CERN Document Server

    König, Wolfgang

    2016-01-01

    This is a comprehensive survey on the research on the parabolic Anderson model – the heat equation with random potential or the random walk in random potential – of the years 1990 – 2015. The investigation of this model requires a combination of tools from probability (large deviations, extreme-value theory, e.g.) and analysis (spectral theory for the Laplace operator with potential, variational analysis, e.g.). We explain the background, the applications, the questions and the connections with other models and formulate the most relevant results on the long-time behavior of the solution, like quenched and annealed asymptotics for the total mass, intermittency, confinement and concentration properties and mass flow. Furthermore, we explain the most successful proof methods and give a list of open research problems. Proofs are not detailed, but concisely outlined and commented; the formulations of some theorems are slightly simplified for better comprehension.

  12. Price-Anderson Nuclear Safety Enforcement Program. 1997 annual report

    International Nuclear Information System (INIS)

    This report summarizes activities in the Department of Energy's Price-Anderson Amendments Act (PAAA) Enforcement Program in calendar year 1997 and highlights improvements planned for 1998. The DOE Enforcement Program involves the Office of Enforcement and Investigation in the DOE Headquarters Office of Environment, Safety and Health, as well as numerous PAAA Coordinators and technical advisors in DOE Field and Program Offices. The DOE Enforcement Program issued 13 Notices of Violation (NOV's) in 1997 for cases involving significant or potentially significant nuclear safety violations. Six of these included civil penalties totaling $440,000. Highlights of these actions include: (1) Brookhaven National Laboratory Radiological Control Violations / Associated Universities, Inc.; (2) Bioassay Program Violations at Mound / EG ampersand G, Inc.; (3) Savannah River Crane Operator Uptake / Westinghouse Savannah River Company; (4) Waste Calciner Worker Uptake / Lockheed-Martin Idaho Technologies Company; and (5) Reactor Scram and Records Destruction at Sandia / Sandia Corporation (Lockheed-Martin). Sandia / Sandia Corporation (Lockheed-Martin)

  13. Anderson localisation of visible light on a nanophotonic chip

    CERN Document Server

    Crane, Tom; Sapienza, Luca

    2016-01-01

    Controlling the propagation of visible light on a chip is of tremendous interest in research areas such as energy harvesting, imaging, sensing and biology. Technological advances allow us to control light at the nanoscale and to strongly enhance the light-matter interaction in highly engineered devices. However, compared to state-of-the-art two-dimensional optical cavities operating at longer wavelengths, the quality factor of on-chip visible light confinement is several orders of magnitude lower. Our approach makes use of fabrication imperfections to trap light: we demonstrate, for the first time, Anderson localisation of visible light on a chip. Remarkably, compared to quality factors of engineered cavities, disorder-induced localisation proves to be more efficient in trapping light than highly engineered devices, thus reversing the trend observed so far. We measure light-confinement quality factors as high as 7600 and, by implementing a sensitive imaging technique, we directly visualise the localised modes...

  14. Chiral transition, eigenmode localisation and Anderson-like models

    CERN Document Server

    Giordano, Matteo; Pittler, Ferenc

    2016-01-01

    We discuss chiral symmetry restoration and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We argue that the features of QCD relevant to both phenomena are the presence of order in the Polyakov line configuration, and the correlations that this induces between spatial links across time slices. This ties the fate of chiral symmetry and of localisation of the lowest Dirac eigenmodes to the confining properties of the theory. We then show numerical results obtained in a QCD-inspired Anderson-like toy model, derived by radically simplifying the QCD dynamics while keeping the important features mentioned above. The toy model reproduces all the important qualitative aspects of chiral symmetry breaking and localisation in QCD, thus supporting the central role played by the confinement/deconfinement transition in triggering both phenomena.

  15. Atomic Bose and Anderson Glasses in Optical Lattices

    Science.gov (United States)

    Damski, B.; Zakrzewski, J.; Santos, L.; Zoller, P.; Lewenstein, M.

    2003-08-01

    An ultracold atomic Bose gas in an optical lattice is shown to provide an ideal system for the controlled analysis of disordered Bose lattice gases. This goal may be easily achieved under the current experimental conditions by introducing a pseudorandom potential created by a second additional lattice or, alternatively, by placing a speckle pattern on the main lattice. We show that, for a noncommensurable filling factor, in the strong-interaction limit, a controlled growing of the disorder drives a dynamical transition from superfluid to Bose-glass phase. Similarly, in the weak interaction limit, a dynamical transition from superfluid to Anderson-glass phase may be observed. In both regimes, we show that even very low-intensity disorder-inducing lasers cause large modifications of the superfluid fraction of the system.

  16. Nuclear-structure studies using the high-resolution spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility. Progress report

    International Nuclear Information System (INIS)

    This document contains a description of the ongoing medium-energy nuclear-physics research program supported by the US Department of Energy with The University of Texas at Austin. A major part of the work is associated with research done using the High Resolution Spectrometer (HRS) at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF); this research focuses on: (1) providing data which test microscopic models of the medium - energy proton + nucleus interaction; (2) providing data which are to be analyzed to provide new nuclear-structure information (both ground state and excited state); and (3) developing and improving the models themselves. Publications are listed

  17. Localization of light in a disordered medium

    Science.gov (United States)

    Wiersma, Diederik S.; Bartolini, Paolo; Lagendijk, Ad; Righini, Roberto

    1997-12-01

    Among the unusual transport properties predicted for disordered materials is the Anderson localization phenomenon. This is a disorder-induced phase transition in the electron-transport behaviour from the classical diffusion regime, in which the well-known Ohm's law holds, to a localized state in which the material behaves as an insulator. The effect finds its origin in the interference of electrons that have undergone multiple scattering by defects in the solid. A similar phenomenon is anticipated for multiple scattering of electromagnetic waves, but with one important simplification: unlike electrons, photons do not interact with one another. This makes transport of photons in disordered materials an ideal model system in which to study Anderson localization. Here we report direct experimental evidence for Anderson localization of light in optical experiments performed on very strongly scattering semiconductor powders.

  18. Study of Localization for the Forced Vibration of Mistuned Bladed Disks Based on Engine Orders of Excitation%基于激励阶次的失谐叶盘振动响应局部化研究

    Institute of Scientific and Technical Information of China (English)

    张宏远; 袁惠群; 寇海江

    2016-01-01

    为了评估不同激励阶次和不同失谐标准差对叶盘系统结构振动的局部化影响,针对航空发动机压气机叶盘系统有限元模型,考虑榫槽和榫头的非线性接触,采用子结构模态综合法,通过引入相对振动局部化因子,研究了在不同激励阶次下的谐调和失谐两种情况下叶盘系统振动响应,分析不同失谐标准差下失谐叶盘系统的振动响应局部化特性,讨论了激励阶次对失谐叶盘系统位移和应变能的影响规律。结果表明,激励阶次对失谐叶盘系统频率、位移和应变能分布影响显著,随着激励阶次的增加,相对局部化因子呈现先增大再减小的趋势。%In order to evaluate the effect of localization for various engine orders of excitation and levels of mistuning on mistuned bladed disks,the finite element model of aero-engine compressor’ s bladed disks was established.Considering the non-linear contact problem of tenon and mortise, the localization of various engine orders of excitation of mistuned bladed disks was studied by adopting the component mode synthesis method and introducing the relative localization factors. The effect of displacement and strain energy for various engine orders of excitation of mistuned bladed disks was discussed,whose results indicated that the engine orders of excitation have significant effect on frequency,displacement and strain energy.With the increase of engine orders of excitation,the relative localization factors tend to first increase and then drop.

  19. Anderson localisation and optical-event horizons in rogue-soliton generation

    CERN Document Server

    Saleh, Mohammed F; Biancalana, Fabio

    2016-01-01

    We show that the true origin of rogue solitons in optical fibres is due to the combined action of linear Anderson localisation and the formation of optical-event horizons. Anderson localised modes are formed in certain temporal locations due to the random background noise. Such localised modes seed the formation of solitary waves at those preferred locations, while the strongest Anderson mode generates the rogue soliton. The event horizon effect between dispersive waves and solitons produces an artificial collective acceleration that favours the collision of solitons during the rogue wave formation.

  20. Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis and ab initio Theory.

    Science.gov (United States)

    Frandsen, Benjamin A; Brunelli, Michela; Page, Katharine; Uemura, Yasutomo J; Staunton, Julie B; Billinge, Simon J L

    2016-05-13

    We present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ∼1  nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. The Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory. PMID:27232042

  1. The completeness problem in the impurity Anderson model

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, T. [Instituto de Fisica da, Universidade Federal Fluminense, Av. Litoranea s/n, 24210-346 Niteroi, Rio de Janeiro, Brasil (Brazil); Figueira, M.S. [Instituto de Fisica da, Universidade Federal Fluminense, Av. Litoranea s/n, 24210-346 Niteroi, Rio de Janeiro, Brasil (Brazil)]. E-mail: figueira@if.uff.br; Franco, R. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia); Silva-Valencia, J. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia); Foglio, M.E. [Instituto de Fisica Gleb Wataghin - Universidade Estadual de Campinas, Barao Geraldo 13083-970 Campinas-SP, Brasil (Brazil)

    2007-09-01

    With the recent development of the nanoscopic technology, the impurity Anderson model (AIM) was experimentally realized in quantum dot devices, and there is renewed interest in the study of the Kondo physics of the AIM. Several Green's functions approximations by the equation of motion method (EOM), that incorporates the Kondo effect through a digamma function, have been presented in the literature as an adequate tool to describe, at least qualitatively, the Kondo effect. However, these approximations present several drawbacks: they are no longer valid as the temperature decreases below the Kondo temperature, because the logarithmic divergence of the digamma function makes the spectral density at the chemical potential to vanish, and the Friedel sum rule and the completeness in the occupation numbers are not fulfilled. In this work we present a critical discussion comparing the results of digamma approximations GF with the atomic approach, recently developed by some of us, that satisfy the completeness and the Friedel sum rule. We present results for the density of states, the Friedel sum rule and the completeness.

  2. What should the Price--Anderson Act accomplish

    International Nuclear Information System (INIS)

    A historical review of the Price-Anderson Act's goals is followed by recommendations for amendments to improve guarantees of public safety. Failures of the original Act are identified as its failure to cover some accident situations appropriately and to provide incentives for promoting public safety. Legislation should correct these problems and be extended to all energy areas. Legislation based on worst-case situations is not found to be meaningful in terms of increasing safety or estimating comprehensive compensation because it relies on invalidated assumptions, which are still useful in safety awareness. Legislation could take the direction of putting 1.5 percent of the reactor cost into a fund, with the vendor and licensee contributing equal parts. When an incident occurs at any reactor, another one percent is put in by every reactor plus a $1 million penalty proportioned among those responsible. The Federal government would cover amounts above the fund, which would have no limit. Compensation to public funds by the industry would be a social decision based on the social and economic impact

  3. Price--Anderson Act: the insurance industry's view

    International Nuclear Information System (INIS)

    The insurance industry feels the expense of providing insurance coverage under the Price-Anderson Act is justified because it encouraged development of nuclear power and assured protection for the public in the event of an accident. Insurance pools have been instituted in about 20 countries in order to distribute the risk on a worldwide basis. Changes in the original Act allow an off-site claimant to get compensation with defense waived and provide for the transition of financial responsibility from the public to the private sector. To date the pools have refunded $9.7 of $12.7 million (73 percent) of the premiums to the insured and the remainder has grown into a $45 million fund, which reflects the success of the nuclear industry and the regulatory agencies in establishing a safe record. This record covers 60 power reactors, 50 research and development reactors, waste disposal sites, and about 50 nuclear facilities. With the exception of reactor operators and fuel reprocessors, the insurance is voluntary at premiums ranging from $1000 to $260,000. A total of $600,000 has been paid in claims

  4. Magnetic flux creep in HTSC and Anderson-Kim theory

    International Nuclear Information System (INIS)

    The theoretical and experimental data on flux creep in high-temperature superconductors (HTSC) were analyzed in the review paper. On the one hand, the main attention is paid to the most striking experimental results which have had a significant influence on the investigations of flux creep in HTSC. On the other hand, the analysis of theoretical studies is concentrated on the works, which explain the features of flux creep on the basis of the Anderson-Kim (AK) theory modifications, and received previously unsufficient attention. However, it turned out that the modified AK theory could explain a lot of features of flux creep in HTSC: the scaling behaviour of current-voltage curves of HTSC, the finite rate of flux creep at ultra low temperatures, the logarithmic dependence of effective pinning potential as a function of transport current and its decrease with temperature. The harmonic potential field which is used in this approach makes it possible to solve accurately the both problems: viscous vortex motion and flux creep in this field. Moreover the distribution of pinning potential and the interaction of vortices with each other are taken into account in the approach. Thus, the modification of the AK theory consists, essentially, in its detailed elaboration and approaching to real situations in superconductors

  5. Wyodak-Anderson net coal thickness in the Gillette coalfield, Wyoming (gilcatg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains a polygon representation of the Wyodak-Anderson net coal thickness in the Gillette coalfield study area. This theme was created specifically...

  6. Wyodak-Anderson clinker in the Powder River Basin, Wyoming and Montana (prbclkg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This ArcView shapefile contains a polygon representation of the Wyodak-Anderson clinker in the Powder River Basin, Wyoming and Montana. This theme was created...

  7. Modified Anderson orthogonality catastrophe power law in the presence of shell structure

    Science.gov (United States)

    Bandopadhyay, Swarnali; Hentschel, Martina

    2011-01-01

    We study Anderson orthogonality catastrophe (AOC) for parabolic quantum dots and focus on the effects of degeneracies, realized through the inherent shell structure of their energy levels that can be lifted through an external magnetic field, on the Anderson overlap. We find rich and interesting behaviors as a function of the strength and position of the perturbation, the system size, and the applied magnetic field. In particular, even for weak perturbations, we observe a pronounced AOC that is related to the degeneracy of energy levels. Most importantly, the power-law decay of the Anderson overlap as a function of the number of particles is modified in comparison to the metallic case due to the rearrangement of the energy-level shell structure. We support our analytical results by numerical calculations and also study the distribution of Anderson overlaps.

  8. Excited Delirium

    Directory of Open Access Journals (Sweden)

    Takeuchi, Asia

    2011-02-01

    Full Text Available Excited (or agitated delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. [West J Emerg Med. 2011;12(1:77-83.

  9. Excited baryons

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  10. Thomas Anderson Goudge and the introduction of symbolic logic at the University of Toronto

    OpenAIRE

    Anellis, Irving H.

    1997-01-01

    Thomas Anderson Goudge was the first member of the philosophy department faculty to teach a course in modern mathematical logic at the University of Toronto. We provide here a brief discussion of the origin of Goudge's interest in logic and of how he came to introduce symbolic logic courses into the philosophy department curriculum at the University of Toronto. Much of the information presented here is based upon John G. Slater's three-page essay "Thomas Anderson Goudge" pre...

  11. Grotesque's Loneliness and George's Growth In "Winesburg, Ohio" by Sherwood Anderson

    Institute of Scientific and Technical Information of China (English)

    许丽丽

    2007-01-01

    Sherwood Anderson is called the first of American psychological writers. "Winesburg, Ohio" is the first work of fiction to expose the frustration, and inhibition behind the typical small town. Every grotesque in Winesburg had such a kind of tragic experience. Winesburg is the epitome of all mid-western small towns. Anderson explores the damages by industrialization to the middle westerners. George with all grotesques' hopes and wishes to leave Winesburg, just like a moment of illustration in the darkness.

  12. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  13. Slow dynamics in a two-dimensional Anderson-Hubbard model

    Science.gov (United States)

    Bar Lev, Yevgeny; Reichman, David R.

    2016-02-01

    We study the real-time dynamics of a two-dimensional Anderson-Hubbard model using nonequilibrium self-consistent perturbation theory within the second-Born approximation. When compared with exact diagonalization performed on small clusters, we demonstrate that for strong disorder this technique approaches the exact result on all available timescales, while for intermediate disorder, in the vicinity of the many-body localization transition, it produces quantitatively accurate results up to nontrivial times. Our method allows for the treatment of system sizes inaccessible by any numerically exact method and for the complete elimination of finite-size effects for the times considered. We show that for a sufficiently strong disorder the system becomes nonergodic, while for intermediate disorder strengths and for all accessible timescales transport in the system is strictly subdiffusive. We argue that these results are incompatible with a simple percolation picture, but are consistent with the heuristic random resistor network model where subdiffusion may be observed for long times until a crossover to diffusion occurs. The prediction of slow finite-time dynamics in a two-dimensional interacting and disordered system can be directly verified in future cold-atoms experiments.

  14. On the number of ground states of the Edwards-Anderson spin glass model

    CERN Document Server

    Arguin, Louis-Pierre

    2011-01-01

    Ground states of the Edwards-Anderson (EA) spin glass model are studied on infinite graphs with finite degree. Ground states are spin configurations that locally minimize the EA Hamiltonian on each finite set of vertices. A problem with far-reaching consequences in mathematics and physics is to determine the number of ground states for the model on Z^d for any d. This problem can be seen as the spin glass version of determining the number of infinite geodesics in first-passage percolation or the number of ground states in the disordered ferromagnet. It was recently shown by Newman, Stein and the two authors that, on the half-plane Z \\times N, there is a unique ground state (up to global flip) arising from the weak limit of finite-volume ground states for a particular choice of boundary conditions. In this paper, we study the entire set of ground states on the infinite graph, proving that the number of ground states on the half-plane must be two (related by a global flip) or infinity. This is the first result ...

  15. Parabolic Anderson Model in a Dynamic Random Environment: Random Conductances

    Science.gov (United States)

    Erhard, D.; den Hollander, F.; Maillard, G.

    2016-06-01

    The parabolic Anderson model is defined as the partial differential equation ∂ u( x, t)/ ∂ t = κ Δ u( x, t) + ξ( x, t) u( x, t), x ∈ ℤ d , t ≥ 0, where κ ∈ [0, ∞) is the diffusion constant, Δ is the discrete Laplacian, and ξ is a dynamic random environment that drives the equation. The initial condition u( x, 0) = u 0( x), x ∈ ℤ d , is typically taken to be non-negative and bounded. The solution of the parabolic Anderson equation describes the evolution of a field of particles performing independent simple random walks with binary branching: particles jump at rate 2 d κ, split into two at rate ξ ∨ 0, and die at rate (- ξ) ∨ 0. In earlier work we looked at the Lyapunov exponents λ p(κ ) = limlimits _{tto ∞} 1/t log {E} ([u(0,t)]p)^{1/p}, quad p in {N} , qquad λ 0(κ ) = limlimits _{tto ∞} 1/2 log u(0,t). For the former we derived quantitative results on the κ-dependence for four choices of ξ : space-time white noise, independent simple random walks, the exclusion process and the voter model. For the latter we obtained qualitative results under certain space-time mixing conditions on ξ. In the present paper we investigate what happens when κΔ is replaced by Δ𝓚, where 𝓚 = {𝓚( x, y) : x, y ∈ ℤ d , x ˜ y} is a collection of random conductances between neighbouring sites replacing the constant conductances κ in the homogeneous model. We show that the associated annealed Lyapunov exponents λ p (𝓚), p ∈ ℕ, are given by the formula λ p({K} ) = {sup} {λ p(κ ) : κ in {Supp} ({K} )}, where, for a fixed realisation of 𝓚, Supp(𝓚) is the set of values taken by the 𝓚-field. We also show that for the associated quenched Lyapunov exponent λ 0(𝓚) this formula only provides a lower bound, and we conjecture that an upper bound holds when Supp(𝓚) is replaced by its convex hull. Our proof is valid for three classes of reversible ξ, and for all 𝓚

  16. Attractive Hubbard model with disorder and the generalized Anderson theorem

    International Nuclear Information System (INIS)

    Using the generalized DMFT+Σ approach, we study the influence of disorder on single-particle properties of the normal phase and the superconducting transition temperature in the attractive Hubbard model. A wide range of attractive potentials U is studied, from the weak coupling region, where both the instability of the normal phase and superconductivity are well described by the BCS model, to the strong-coupling region, where the superconducting transition is due to Bose-Einstein condensation (BEC) of compact Cooper pairs, formed at temperatures much higher than the superconducting transition temperature. We study two typical models of the conduction band with semi-elliptic and flat densities of states, respectively appropriate for three-dimensional and two-dimensional systems. For the semi-elliptic density of states, the disorder influence on all single-particle properties (e.g., density of states) is universal for an arbitrary strength of electronic correlations and disorder and is due to only the general disorder widening of the conduction band. In the case of a flat density of states, universality is absent in the general case, but still the disorder influence is mainly due to band widening, and the universal behavior is restored for large enough disorder. Using the combination of DMFT+Σ and Nozieres-Schmitt-Rink approximations, we study the disorder influence on the superconducting transition temperature Tc for a range of characteristic values of U and disorder, including the BCS-BEC crossover region and the limit of strong-coupling. Disorder can either suppress Tc (in the weak-coupling region) or significantly increase Tc (in the strong-coupling region). However, in all cases, the generalized Anderson theorem is valid and all changes of the superconducting critical temperature are essentially due to only the general disorder widening of the conduction band

  17. The Writing Features of "The Egg" by Sherwood Anderson%The Writing Features of "The Egg" by Sherwood Anderson

    Institute of Scientific and Technical Information of China (English)

    张丽

    2012-01-01

    Sherwood Anderson is an important writer in American literary history, whose short story The Egg is well known for its distinctive style and elusive form. This paper is an attempt to explore the narrative art, symbols and deep implications in The Egg form perspectives of narrative point of view,narrative language.

  18. On the local relaxation of solid neon upon Rydberg excitation of a NO impurity: the role of the NO(A)-Ne interaction potential and zero-point quantum delocalization.

    Science.gov (United States)

    Pajón-Suárez, Pedro; Rojas-Lorenzo, Germán A; Rubayo-Soneira, Jesús; Hernández-Lamoneda, Ramón; Larrégaray, Pascal

    2009-12-31

    The local relaxation of solid neon subsequent to the impulsive excitation of the NO chromophore to its A(3s sigma) Ryberg state is investigated using molecular dynamics simulations. This study makes use of empirical NO(X,A)-Ne isotropic pair potentials as well as a recently developed ab initio triatomic potential energy surface for the excited state. The role of these interaction potentials is analyzed, including many-body effects. In particular, empirical potentials, designed to reproduce correctly both the NO X-A steady-state absorption and emission bands, are shown to lead to a good description of the subpicosecond relaxation dynamics. The 600 fs expansion of the electronic bubble fairly agrees with experimental data. This relatively long time scale with respect to solid Argon, which was previously attributed to the range of the NO(A)-Ne interaction, is presumably related to the quantum nature of the medium. The time-resolved local relaxation of the Ne solid is understandably intermediate between that of classical solids (e.g., Ar) and that of quantum solids (e.g., H(2)).

  19. Spatial and temporal localization of light in two dimensions

    CERN Document Server

    Máximo, Carlos E; Courteille, Philippe W; Kaiser, Robin; Bachelard, Romain

    2015-01-01

    Quasi-resonant scattering of light in two dimensions can be described either as a scalar or as a vectorial electromagnetic wave. Performing a scaling analysis we observe in both cases long lived modes, yet only the scalar case exhibits Anderson localized modes together with extremely long mode lifetimes. We show that the localization length of these modes is influenced only by their position, and not their lifetime. Investigating the reasons for the absence of localization, it appears that both the coupling of several polarizations and the presence of near-field terms are able to prevent long lifetimes and Anderson localization.

  20. Random Walks in Anderson's Garden: A Journey from Cuprates to Cooper Pair Insulators and Beyond

    CERN Document Server

    Baskaran, G

    2016-01-01

    Anderson's Garden is a drawing presented to Philip W. Anderson on the eve of his 60th birthday celebration, in 1983. This cartoon (Fig. 1), whose author is unknown, succinctly depicts some of Anderson's pre-1983 works, as a blooming garden. As an avid reader of Anderson's papers, random walk in Anderson's garden had become a part of my routine since graduate school days. This was of immense help and prepared me for a wonderful collaboration with the gardener himself, on the resonating valence bond (RVB) theory of High Tc cuprates and quantum spin liquids, at Princeton. The result was bountiful - the first (RVB mean field) theory for i) quantum spin liquids, ii) emergent fermi surfaces in Mott insulators and iii) superconductivity in doped Mott insulators. Beyond mean field theory - i) emergent gauge fields, ii) Ginzbuerg Landau theory with RVB gauge fields, iii) prediction of superconducting dome, iv) an early identification and study of a non-fermi liquid normal state of cuprates and so on. Here I narrate th...

  1. Local magnetic properties of multiferroic Nd{sub 0.5}Gd{sub 0.5}Fe{sub 3}(BO{sub 3}){sub 4} in the excited states of Nd{sup 3+} ion

    Energy Technology Data Exchange (ETDEWEB)

    Malakhovskii, A.V., E-mail: malakha@iph.krasn.ru [L. V. Kirensky Institute of Physics, Siberian Branch of Russian Academy of Sciences, 660036 Krasnoyarsk (Russian Federation); Gnatchenko, S.L.; Kachur, I.S.; Piryatinskaya, V.G. [B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 61103 Kharkov (Ukraine); Sukhachev, A.L.; Temerov, V.L. [L. V. Kirensky Institute of Physics, Siberian Branch of Russian Academy of Sciences, 660036 Krasnoyarsk (Russian Federation)

    2015-02-01

    Polarized absorption spectra of single-crystal Nd{sub 0.5}Gd{sub 0.5}Fe{sub 3}(BO{sub 3}){sub 4} were studied in the region of the transition {sup 4}I{sub 9/2}→({sup 4}G{sub 5/2}+{sup 2}G{sub 7/2}) in Nd{sup 3+} ion as a function of temperature (2–34 K) and magnetic field (0–65 kOe). The spectra of natural circular dichroism were measured in the range of 5–40 K. It was found out that the local magnetic properties in the vicinity of the excited ion substantially depended on its state. In particular, a weak ferromagnetic moment appears in some excited states. It was found out that the selection rules for electron transitions in the magnetically ordered state substantially deviated from those in the paramagnetic state of the crystal. They are different for different transitions and they are very sensitive to the orientation of the sublattice magnetic moment relative to the light polarization. In the spectrum of the natural circular dichroism, the transition is revealed which is not observed in the absorption spectrum. - Highlights: • Temperature and field dependences of f-f transitions in Nd{sub 0.5}Gd{sub 0.5}Fe{sub 3}(BO{sub 3}){sub 4}. • Natural circular dichroism in Nd{sub 0.5}Gd{sub 0.5}Fe{sub 3}(BO{sub 3}){sub 4} below T{sub N}. • Weak ferromagnetic moment was identified in some excited 4f states. • Selection rules for f-f transitions substantially change below T{sub N}. • Intensities of f-f transitions strongly depend on magnetic moment orientation.

  2. John Anderson's development of (situational) realism and its bearing on psychology today.

    Science.gov (United States)

    Hibberd, Fiona J

    2009-10-01

    In 1927, the Scottish philosopher John Anderson arrived in Australia to take up the chair of Philosophy at the University of Sydney. By the late 1930s, the "macrostructure" of his realist system was in place. It includes a theory of process and a substantial metaphysics, one that opposes positivism, linguistic philosophy and all forms of idealism. However, beyond Australia it remains largely unknown, despite its bearing on a number of current issues in psychology and the social sciences generally. This article outlines Anderson's transition from Hegelian idealism to realism, describes aspects of his ontology and epistemology, compares some of Anderson's ideas with Dewey's pragmatism and explains their relevance to present-day psychology. PMID:20027696

  3. beta-Function of Anderson localization transition in three dimensions at unitary symmetry

    Science.gov (United States)

    Neogi, Sanghamitra

    In recent years, with the advances in experimental techniques, the characteristic length scales of the materials synthesized, are becoming increasingly small. Many of these microscopic structures found their places in important commercial applications. However, the thermal loads imposed on these devices and structures create a major obstacle toward their applicability. This challenge is driving a renewed interest among researchers from various disciplines, toward the topic of thermal management. The interest in the topic of thermal transport in small scale structures, served as the motivation for the work performed in this dissertation. More specifically, the following topics were investigated: • Transport in One-Dimensional Nonlinear Systems: Thermal transport in materials can be explained in terms of the diffusive motion of the heat carriers at the microscopic level. An important and surprising situation emerges in some low dimensional model systems; the thermal conductivity diverges with system size. It was shown (Toda, 1979) that nonlinearity has an important effect on the heat transport in low dimensional systems. We investigate the transport of energy in a nonlinear one-dimensional chain. We show that solitons are spontaneous generated when we apply forcing functions at the end of the chain. We investigate the different characteristics of these solitons generated in the chain. • Transport in Fluids --- Study of Pair Distribution Function: Thermal transport in fluids depends on the distribution of particles in the fluid. It is well known that the two-particle distribution function can describe most of the thermodynamic properties for classical fluids in thermal equilibrium. We review the approximate integral equation theories (Percus-Yevick, Hypernetted chain approximation) to obtain the pair distribution functions of classical fluids. We find that these methods are highly dependent on the choice of the thermodynamic parameters of the fluid. We solve several Lennard-Jones fluid systems with different density and temperature values and prepare a density-temperature compressibility diagram. This diagram shows the region of applicability of these theories and helps us obtain the pair distribution function for a Lennard-Jones fluid with known thermodynamic parameters. We also suggest a modification of the integral-equation theories to obtain the pair distribution functions of quantum fluids. • Thermal Transport Across Interfaces: When thermal energy is transported from one material to another, there is a discontinuity in temperature at the interface between them. This thermal boundary resistance is known as Kapitza resistance. The scattering of phonons at interfaces is one of the main reasons behind the presence of thermal boundary resistance. We explore the scattering of acoustic waves at several solid-solid interfaces using lattice dynamical methods. We derive matrix equations to obtain the reflection and transmission coefficients for an acoustic wave incident on the interface. These coefficients can reproduce the familiar expressions in the continuum limit and are consistent with the conservation relations. We discuss a method to obtain the thermal boundary resistance for neutral solid-fluid interfaces. The acoustic mismatch theory works poorly for solid-fluid interfaces. One reason is that this theory only includes the long wavelength acoustic phonons. Our theory includes all the phonon modes in the solid and all the sound modes in the fluid, in the calculation of the thermal boundary resistance. We provide an application of this method to obtain the thermal boundary resistance at the interface between solid Argon and liquid Neon. Our method yields the value for Kapitza conductance for solid Argon-fluid Neon interface as 0.0374GW/Km2.

  4. Anderson localization in a partially random Bragg grating and a conserved area theorem

    CERN Document Server

    Mafi, Arash

    2015-01-01

    We investigate the gradual emergence of the disorder-related phenomena in intermediate regimes between a deterministic periodic Bragg grating and a fully random grating and highlight two critical properties of partially disordered Bragg gratings. First, the integral of the logarithm of the transmittance over the reciprocal wavevector space is a conserved quantity. Therefore, adding disorder merely redistributes the transmittance over the reciprocal space. Second, for any amount of disorder, the average transmittance decays exponentially with the number of grating layers in the simple form of $\\exp(-\\eta N)$ for sufficiently large $N$, where $\\eta$ is a constant and $N$ is the number of layers. Conversely, the simple exponential decay form does not hold for small $N$ except for a highly disordered system. Implications of these findings are demonstrated.

  5. Multifractality to Photonic Crystal & Self-Organization to Metamaterials through Anderson Localizations & Group/Gauge Theory

    Science.gov (United States)

    Hidajatullah-Maksoed, Widastra

    2015-04-01

    Arthur Cayley at least investigate by creating the theory of permutation group[F:∖∖Group_theory.htm] where in cell elements addressing of the lattice Qmf used a Cayley tree, the self-afine object Qmf is described by the combination of the finite groups of rotation & inversion and the infinite groups of translation & dilation[G Corso & LS Lacena: ``Multifractal lattice and group theory'', Physica A: Statistical Mechanics &Its Applications, 2005, v 357, issue I, h 64-70; http://www.sciencedirect.com/science/articel/pii/S0378437105005005 ] hence multifractal can be related to group theory. Many grateful Thanks to HE. Mr. Drs. P. SWANTORO & HE. Mr. Ir. SARWONO KUSUMAATMADJA.

  6. Adaptive and self-averaging Thouless-Anderson-Palmer mean-field theory for probabilistic modeling

    DEFF Research Database (Denmark)

    Opper, Manfred; Winther, Ole

    2001-01-01

    We develop a generalization of the Thouless-Anderson-Palmer (TAP) mean-field approach of disorder physics. which makes the method applicable to the computation of approximate averages in probabilistic models for real data. In contrast to the conventional TAP approach, where the knowledge of the d......We develop a generalization of the Thouless-Anderson-Palmer (TAP) mean-field approach of disorder physics. which makes the method applicable to the computation of approximate averages in probabilistic models for real data. In contrast to the conventional TAP approach, where the knowledge...

  7. Anomalous electrical resistivity and Hall constant of Anderson lattice with finite f-band width

    CERN Document Server

    Panwar, S S

    2002-01-01

    We study here an extension of the periodic Anderson model by considering finite f-band width. A variational method is used to study the temperature dependence of electronic transport properties of Anderson lattice for different values of the f-band width. The electrical resistivity rho(T) and Hall constant R sub H (T) calculated show qualitatively the features experimentally observed in heavy fermion materials. We find that as f-band width increases, the low temperature peak in rho(T) disappears, while the low-temperature peak in R sub H (T) becomes sharper. (author)

  8. Dynamical Localization in Kicked Quantum Rotors

    CERN Document Server

    Kamalov, Andrei; Bucksbaum, Philip H

    2015-01-01

    The periodically $\\delta$-kicked quantum linear rotor is known to experience non-classical bounded energy growth due to quantum dynamical localization in angular momentum space. We study the effect of random deviations of the kick period in simulations and experiments. This breaks the energy and angular momentum localization and increases the rotational alignment, which is the analog of the onset of Anderson localization in 1-D chains.

  9. Non-Fermi liquid and Fermi liquid in two-channel anderson lattice model. Theory for PrA2Al20 (A = V, Ti) and PrIr2Zn20

    International Nuclear Information System (INIS)

    We theoretically investigate electronic states and physical properties in a two-channel Anderson lattice model to understand the non-Fermi liquid behaviors observed in PrV2Al20 and PrIr2Zn20, whose ground state of the crystalline electric field for a local f-electron is the Γ3 non-Kramers doublet of f2-configuration and whose excited state is the Γ7 Kramers doublet of f1-configuration. We use the expansion from the limit of the large degeneracy N of the ground state (1/N-expansion), with N being the spin–orbital degeneracy. The inclusion of the self-energy of conduction electrons up to the order of O(1/N) leads to heavy electrons with channel and spin–orbit degeneracies. We find that the electrical resistivity is proportional to the temperature T in the limit T → 0 and follows the √T-law in a wide temperature region, i.e., Tx < T < T0, where the typical values of Tx and T0 are Tx ∼ 10-3TK and T0 ∼ 10-2TK, respectively, TK being the Kondo temperature of the model. We also find non-Fermi liquid behaviors at T ≪ TK in a series of physical quantities; chemical potential, specific heat, and magnetic susceptibility, which explain the non-Fermi liquid behaviors observed in PrV2Al20 and PrIr2Zn20. At the same time, we find that the Fermi liquid behavior becomes prominent for the system with a small hybridization between f- and conduction electrons, explaining the Fermi liquid behaviors observed in PrTi2Al20. (author)

  10. Multifractality and quantum-to-classical crossover in the Coulomb anomaly at the Mott–Anderson metal–insulator transition

    International Nuclear Information System (INIS)

    We study the interaction-driven localization transition, which a recent experiment (Richardella et al 2010 Science 327 665) in Ga1−xMnxAs has shown to come along with the multifractal behavior of the local density of states (LDoS) and the intriguing persistence of critical correlations close to the Fermi level. We show that the bulk of these phenomena can be understood within a Hartree–Fock (HF) treatment of disordered, Coulomb-interacting spinless fermions. A scaling analysis of the LDoS correlation demonstrates multifractality with the correlation dimension d2 ≈ 1.57, which is significantly larger than at a non-interacting Anderson transition and is compatible with the experimental value dexp2 = 1.8 ± 0.3. At the interaction-driven transition, the states at the Fermi level become critical, while the bulk of the spectrum remains delocalized up to substantially stronger interactions. The mobility edge stays close to the Fermi energy in a wide range of disorder strength, as the interaction strength is further increased. The localization transition is concomitant with the quantum-to-classical crossover in the shape of the pseudo-gap in the tunneling density of states, and with the proliferation of metastable HF solutions that suggest the onset of a glassy regime with poor screening properties. (paper)

  11. Nuclear structure studies using the high resolution spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility: Progress report, [1986-1987

    International Nuclear Information System (INIS)

    A major part of the work done this past year was associated with research conducted at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF) using the High Resolution Spectrometer (HRS) and the External Proton Beam (EPB). The research focussed on (1) providing p + nucleus data which test nonrelativistic and relativistic models of the medium energy proton + nucleus interaction, (2) providing (p,p) and (p,n) data which are to be analyzed to provide new nuclear structure information (both ground state and excited state), (3) providing nucleon + nucleon data to aid in the systematic study of the fundamental nucleon-nucleon interaction, (4) developing and improving the pA models themselves, and (5) initiating new experimental programs whose goals are to search for new phenomena in nuclear physics

  12. The Egg as a Symbol——Analysis of Sherwood Anderson's The Egg

    Institute of Scientific and Technical Information of China (English)

    孙慧春; 李伟

    2009-01-01

    @@ A naive narrator in Sherwood Anderson's The Egg leads the reader to witness the various experiences of his family related with eggs.The egg is a dominant theme in their living and an inseparable part of their family.The egg means something that he could only feel directly as a na(i)ve boy.

  13. Melissa L. Anderson: APA/APAGS Award for Distinguished Graduate Student in Professional Psychology

    Science.gov (United States)

    American Psychologist, 2012

    2012-01-01

    Presents a short biography of the winner of the American Psychological Association/American Psychological Association of Graduate Students Award for Distinguished Graduate Student in Professional Psychology. The 2012 winner is Melissa L. Anderson for her ongoing commitment to understanding, treating, and preventing domestic violence in Deaf women…

  14. Tractable approximations for probabilistic models: The adaptive Thouless-Anderson-Palmer mean field approach

    DEFF Research Database (Denmark)

    Opper, Manfred; Winther, Ole

    2001-01-01

    We develop an advanced mean held method for approximating averages in probabilistic data models that is based on the Thouless-Anderson-Palmer (TAP) approach of disorder physics. In contrast to conventional TAP. where the knowledge of the distribution of couplings between the random variables...

  15. Ilu võitlus koleduse välja vastu / Rebekka Lotman ; kommenteerinud Mart Anderson

    Index Scriptorium Estoniae

    Lotman, Rebekka, 1978-

    2009-01-01

    Konkursside "25 kauneimat Eesti raamatut" ja "Viis kauneimat Eesti lasteraamatut" võidutööde näitus Eesti Rahvusraamatukogus. Võidutööde valikut kommenteerib žürii esimees Mart Anderson. Loetletud 2008. aasta 25 kaunimat raamatut. Nimekiri: 2008. aasta 25 kauneimat raamatut

  16. Ago Anderson pälvis Helmi Tohvelmani preemia / Karin Klaus

    Index Scriptorium Estoniae

    Klaus, Karin

    2009-01-01

    13. oktoobril anti Endla teatri näitlejale Ago Andersonile üle Helmi Tohvelmani auhind. Pidulik sündmus toimus Väätsa põhikoolis, Tohvelmani kodukohas. Anderson pälvis tunnustuse kui kerge kehakeelega näitleja

  17. 78 FR 41835 - Inflation Adjustments to the Price-Anderson Act Financial Protection Regulations

    Science.gov (United States)

    2013-07-12

    ... made the initial changes to the Price-Anderson Act amounts on October 27, 2005 (70 FR 61885), and the first periodic inflation adjustments on September 29, 2008 (73 FR 56451). This final rule makes the... Writing,'' published June 10, 1998 (63 FR 31883). X. Backfit Analysis and Issue Finality The NRC...

  18. Financial analysis of potential retrospective premium assessments under the Price-Anderson system

    International Nuclear Information System (INIS)

    Ten representative nuclear utilities have been analyzed over the period 1981 to 1983 to evaluate the effects of three levels of retrospective premiums on various financial indicators. This analysis continues and expands on earlier analyses prepared as background for deliberations by the US Congress for possible extension or modification of the Price-Anderson Act

  19. Adolescent Identities and Sexual Behavior: An Examination of Anderson's Player Hypothesis

    Science.gov (United States)

    Giordano, Peggy C.; Longmore, Monica A.; Manning, Wendy D.; Northcutt, Miriam J.

    2009-01-01

    We investigate the social and behavioral characteristics of male adolescents who self-identify as players, focusing particularly on Anderson's claim that this social role is inextricably linked with poverty and minority status. Results indicate that black respondents, those affiliated with liberal peers and young men who initially report a…

  20. An asymptotically normal G-estimate for the Anderson-Fisher discriminant function

    Energy Technology Data Exchange (ETDEWEB)

    Girko, V.L.; Pavlenko, T.V. [Kiev State Univ. (Ukraine)

    1994-06-05

    Conditions under which a G-estimate of the Anderson-Fisher discriminant function is asymptotically normal are investigated. This estimate decreases by an order of magnitude the quantity of observations needed for a given level of accuracy on the part of an estimate and is thus of significant interest for practical applications. 3 refs.

  1. Effect of wave localization on plasma instabilities. Ph.D. Thesis

    Science.gov (United States)

    Levedahl, William Kirk

    1987-01-01

    The Anderson model of wave localization in random media is involved to study the effect of solar wind density turbulence on plasma processes associated with the solar type III radio burst. ISEE-3 satellite data indicate that a possible model for the type III process is the parametric decay of Langmuir waves excited by solar flare electron streams into daughter electromagnetic and ion acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Reigel criteria for wave localization in the solar wind with observed density fluctuations -1 percent. Numerical simulations of wave propagation in random media confirm the localization length predictions of Escande and Souillard for stationary density fluctations. For mobile density fluctuations localized wave packets spread at the propagation velocity of the density fluctuations rather than the group velocity of the waves. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action principle approach is used to develop a theory of non-linear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability. It is argued that localization of electromagnetic waves will allow the instability threshold to be exceeded for the parametric decay discussed above.

  2. Wildlife Protection, Mitigation, and Enhancement Plans, Anderson Ranch and Black Canyon Facilities: Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Meuleman, G. Allyn

    1987-06-01

    Under direction of the Pacific Northwest Electric Power Planning and Conservation Act of 1980, and the subsequent Northwest Power Planning Council's Columbia River Basin Fish and Wildlife Program, projects have been developed in Idaho to mitigate the impacts to wildlife habitat and production due to the development and operation of the Anderson Ranch and Black Canyon Facilities (i.e., dam, power plant, and reservoir areas). The Anderson Ranch Facility covered about 4812 acres of wildlife habitat while the Black Canyon Facility covered about 1115 acres. These acreages include dam and power plant staging areas. A separate mitigation plan has been developed for each facility. A modified Habitat Evaluation Procedure (HEP) was used to assess the benefits of the mitigation plans to wildlife. The interagency work group used the target species Habitat Units (HU's) lost at each facility as a guideline during the mitigation planning process, while considering the needs of wildlife in the areas. Totals of 9619 and 2238 target species HU's were estimated to be lost in the Anderson Ranch and Black Canyon Facility areas, respectively. Through a series of projects, the mitigation plans will provide benefits of 9620 target species HU's to replace Anderson Ranch wildlife impacts and benefits of 2195 target species HU's to replace Black Canyon wildlife impacts. Target species to be benefited by the Anderson Ranch and/or Black Canyon mitigation plans include the mallard, Canada goose, mink, yellow warbler, black-capped chickadee, ruffed grouse, mule deer, blue grouse, sharp-tailed grouse, ring-necked pheasant, and peregrine falcon.

  3. Localization in lattice gauge theory and a new multigrid method

    International Nuclear Information System (INIS)

    We show numerically that the lowest eigenmodes of the 2-dimensional Laplace-operator with SU(2) gauge couplings are strongly localized. A connection is drawn to the Anderson-Localization problem. A new Multigrid algorithm, capable to deal with these modes, shows no critical slowing down for this problem. (orig.)

  4. Strategies in Localization Proofs for One-Dimensional Random Schrödinger Operators

    Indian Academy of Sciences (India)

    Günter Stolz

    2002-02-01

    Recent results on localization, both exponential and dynamical, for various models of one-dimensional, continuum, random Schrödinger operators are reviewed. This includes Anderson models with indefinite single site potentials, the Bernoulli–Anderson model, the Poisson model, and the random displacement model. Among the tools which are used to analyse these models are generalized spectral averaging techniques and results from inverse spectral and scattering theory. A discussion of open problems is included.

  5. Localization of nonlinear excitations in curved waveguides

    DEFF Research Database (Denmark)

    Gaididei, Yu. B.; Christiansen, Peter Leth; Kevrekidis, P. G.;

    2005-01-01

    Motivated by the examples of a curved waveguide embedded in a photonic crystal and cold atoms moving in a waveguide created by a spatially inhomogeneous electromagnetic field, we examine the effects of geometry in a 'quantum channel' of parabolic form. Starting with the linear case we derive exact...... as well as approximate expressions for the eigenvalues and eigenfunctions of the linear problem. We then proceed to the nonlinear setting and its stationary states in a number of limiting cases that allow for analytical treatment. The results of our analysis are used as initial conditions in direct...

  6. Emergent Weyl excitations in systems of polar particles

    Science.gov (United States)

    Syzranov, Sergey; Wall, Michael; Zhu, Bihui; Gurarie, Victor; Rey, Ana Maria

    2016-05-01

    Systems with Weyl quasiparticle dispersion have been predicted to display a plethora of novel fascinating phenomena: chiral anomaly, topologically protected Fermi arcs on the surfaces, non-Anderson disorder-driven transitions, etc. Over the last several years enormous research efforts have been directed at finding new Weyl semimetals in solid-state systems and ways to realise them in ultracold atomic gases. We demonstrate that excitations with Weyl dispersion generically exist in three-dimensional systems of polar particles in the presence of magnetic field. They emerge due to the dipolar-interaction-induced transitions between the J = 0 and J = 1 angular-momentum states of the particles. Also, we calculate the quasiparticle spectra microscopically for systems of alkaline-earth atoms that can be realised experimentally and suggest a Ramsey-spectroscopy protocol for observing Weyl excitations in them.

  7. Liability coverage under the Price-Anderson Act for high level waste shipments and disposal

    International Nuclear Information System (INIS)

    The Price-Anderson Act provides the basis for a national system of liability protection for accidents arising out of nuclear activities. Private nuclear liability insurance and/or government indemnity is provided to certain Nuclear Regulatory Commission (NRC) licensees (principally operators of nuclear reactors) and certain Department of Energy (DOE) contractors (those whose activities DOE considers involve a risk of public liability for a substantial nuclear incident). As presently envisioned, both the coverage extended by the NRC to its licensees shipping spent fuel from reactors and the indemnity coverage extended by the DOE to its contractors operating a DOE repository under the Nuclear Waste Policy Act will be utilized to provide public liability protection for spent fuel shipments and disposal. Increased attention is being given to assuring a seamless web of protection provided under the Price-Anderson Act to Federal licensees and contractors

  8. Wildlife Impact Assessment: Anderson Ranch, Black Canyon, and Boise Diversion Projects, Idaho. Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Meuleman, G. Allyn

    1986-05-01

    This report presents an analysis of impacts on wildlife and their habitats as a result of construction and operation of the US Bureau of Reclamation's Anderson Ranch, Black Canyon, and Boise Diversion Projects in Idaho. The objectives were to: (1) determine the probable impacts of development and operation of the Anderson Ranch, Black Canyon, and Boise Diversion Projects to wildlife and their habitats; (2) determine the wildlife and habitat impacts directly attributable to hydroelectric development and operation; (3) briefly identify the current major concerns for wildlife in the vicinities of the hydroelectric projects; and (4) provide for consultation and coordination with interested agencies, tribes, and other entities expressing interest in the project.

  9. Scaling law and critical exponent for {alpha}{sub 0} at the 3D Anderson transition

    Energy Technology Data Exchange (ETDEWEB)

    Slevin, K. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Rodriguez, A.; Roemer, R.A. [Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL (United Kingdom); Vasquez, L.J.

    2009-12-15

    We use high-precision, large system-size wave function data to analyse the scaling properties of the multifractal spectra around the disorder-induced three-dimensional Anderson transition in order to extract the critical exponents of the transition. Using a previously suggested scaling law, we find that the critical exponent {nu} is significantly larger than suggested by previous results. We speculate that this discrepancy is due to the use of an oversimplified scaling relation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  10. Entanglement in One-Dimensional Anderson Model with Long-Range Correlated Disorder

    Institute of Scientific and Technical Information of China (English)

    GUO Zi-Zheng

    2008-01-01

    @@ By using the measure of concurrence,the entanglement of the ground state in the one-dimensional Anderson model is studied with consideration of the long-range correlations. Three kinds of correlations are discussed.We compare the effects of the long-rang Gaussian and power-law correlations between the site energies on the concurrence,and demonstrate the existence of the band structure of the concurrence in the power-law case.

  11. Imagined and imaginary whales: Benedict Anderson, Salman Rushdie and George Orwell

    OpenAIRE

    Hubble, N

    2002-01-01

    George Orwell, anticipating many of the arguments made by Benedict Anderson in the “Patriotism and Racism” chapter of Imagined Communities, illuminated patriotism and nationalism as shifting aspects of a wider dialectical interplay between an identification with imagined communities and a loyalty to humanity. Orwell's essay “Inside the Whale” can be seen, contrary to Salman Rushdie's criticism that it advocates quietism, as an essay about imaginary homelands. In this reading the whale is a me...

  12. Economic Impact of the 32nd Annual Peter Anderson Arts and Crafts Festival, Ocean Springs, Mississippi

    OpenAIRE

    Myles, Albert E.; Carter, Rachael

    2011-01-01

    Evaluating the Economic Impact of Festivals and Special Events: Lessons From the 32st Annual Peter Anderson Arts and Crafts Festival in Ocean Springs, Mississippi Background: Festivals are an integral part of the economies of most communities in Mississippi. The economic benefits of festivals can be assigned a dollar value, but no amount of money will accurately reflect the personal and social benefits of these events. Festivals can increase tourism in the area. These events not only bring ou...

  13. Wyodak-Anderson coal zone study limit in the Powder River Basin, Wyoming and Montana (wabndg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This ArcView shapefile contains a polygon representing the study area for the Wyodak-Anderson coal zone in the Powder River Basin, Wyoming and Montana. This theme...

  14. Overburden above the Wyodak-Anderson coal zone in the Powder River Basin, Wyoming and Montana, 1999 (waovbg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains a representation of the overburden above the Wyodak-Anderson coal zone. This theme was created specifically for the National Coal Resource...

  15. Unioned layer for the Wyodak-Anderson coal zone in the Powder River Basin, Montana and Wyoming (wafing.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This ArcView shapefile contains a polygon representation of numerous themes associated with the Wyodak-Anderson coal zone. The purpose for this theme is to allow...

  16. Analysis of the characteristics of patients with open tibial fractures of Gustilo and Anderson type III

    Directory of Open Access Journals (Sweden)

    Frederico Carlos Jaña Neto

    2016-04-01

    Full Text Available OBJECTIVE: To analyze the characteristics of patients with Gustilo-Anderson Type III open tibial fractures treated at a tertiary care hospital in São Paulo between January 2013 and August 2014. METHODS: This was a cross-sectional retrospective study. The following data were gathered from the electronic medical records: age; gender; diagnosis; trauma mechanism; comorbidities; associated fractures; Gustilo and Anderson, Tscherne and AO classifications; treatment (initial and definitive; presence of compartment syndrome; primary and secondary amputations; MESS (Mangled Extremity Severity Score index; mortality rate; and infection rate. RESULTS: 116 patients were included: 81% with fracture type IIIA, 12% IIIB and 7% IIIC; 85% males; mean age 32.3 years; and 57% victims of motorcycle accidents. Tibial shaft fractures were significantly more prevalent (67%. Eight patients were subjected to amputation: one primary case and seven secondary cases. Types IIIC (75% and IIIB (25% predominated among the patients subjected to secondary amputation. The MESS index was greater than 7 in 88% of the amputees and in 5% of the limb salvage group. CONCLUSION: The profile of patients with open tibial fracture of Gustilo and Anderson Type III mainly involved young male individuals who were victims of motorcycle accidents. The tibial shaft was the segment most affected. Only 7% of the patients underwent amputation. Given the current controversy in the literature about amputation or salvage of severely injured lower limbs, it becomes necessary to carry out prospective studies to support clinical decisions.

  17. Electronic structure of vitamin B12 within the framework of the Haldane-Anderson impurity model

    Science.gov (United States)

    Kandemir, Zafer; Mayda, Selma; Bulut, Nejat

    2015-03-01

    We study the electronic structure of vitamin B12 (cyanocobalamine C63H88CoN14O14P) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition-metal impurity in a semiconductor host. Here, our purpose is to understand the many-body effects originating from the transition-metal impurity. In this approach, the cobalt 3 d orbitals are treated as the impurity states placed in a semiconductor host which consists of the rest of the molecule. The parameters of the resulting effective Haldane-Anderson model are obtained within the Hartree-Fock approximation for the electronic structure of the molecule. The quantum Monte Carlo technique is then used to calculate the one-electron and magnetic correlation functions of this effective Haldane-Anderson model for vitamin B12. We find that new states form inside the semiconductor gap due to the on-site Coulomb interaction at the impurity 3 d orbitals and that these states become the highest occupied molecular orbitals. In addition, we present results on the charge distribution and spin correlations around the Co atom. We compare the results of this approach with those obtained by the density-functional theory calculations.

  18. Analysis of the characteristics of patients with open tibial fractures of Gustilo and Anderson type III☆

    Science.gov (United States)

    Jaña Neto, Frederico Carlos; de Paula Canal, Marina; Alves, Bernardo Aurélio Fonseca; Ferreira, Pablício Martins; Ayres, Jefferson Castro; Alves, Robson

    2016-01-01

    Objective To analyze the characteristics of patients with Gustilo–Anderson Type III open tibial fractures treated at a tertiary care hospital in São Paulo between January 2013 and August 2014. Methods This was a cross-sectional retrospective study. The following data were gathered from the electronic medical records: age; gender; diagnosis; trauma mechanism; comorbidities; associated fractures; Gustilo and Anderson, Tscherne and AO classifications; treatment (initial and definitive); presence of compartment syndrome; primary and secondary amputations; MESS (Mangled Extremity Severity Score) index; mortality rate; and infection rate. Results 116 patients were included: 81% with fracture type IIIA, 12% IIIB and 7% IIIC; 85% males; mean age 32.3 years; and 57% victims of motorcycle accidents. Tibial shaft fractures were significantly more prevalent (67%). Eight patients were subjected to amputation: one primary case and seven secondary cases. Types IIIC (75%) and IIIB (25%) predominated among the patients subjected to secondary amputation. The MESS index was greater than 7 in 88% of the amputees and in 5% of the limb salvage group. Conclusion The profile of patients with open tibial fracture of Gustilo and Anderson Type III mainly involved young male individuals who were victims of motorcycle accidents. The tibial shaft was the segment most affected. Only 7% of the patients underwent amputation. Given the current controversy in the literature about amputation or salvage of severely injured lower limbs, it becomes necessary to carry out prospective studies to support clinical decisions. PMID:27069881

  19. Abrupt physical and chemical changes during 1992-1999, Anderson Springs, SE Geyser Geothermal Field, California

    Science.gov (United States)

    Janik, Cathy J.; Goff, Fraser; Walter, Stephen R.; Sorey, Michael L.; Counce, Dale; Colvard, Elizabeth M.

    2000-01-01

    The Anderson Springs area is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. Patrons drank a variety of cool to hot mineral waters from improved springs, swam in various baths and pools, and hiked in the rugged hills flanking Anderson Creek and its tributaries. In the bluffs to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. By the early 1970s, the higher ridges south and west of Anderson Springs became part of the southeast sector of the greater Geysers geothermal field. Today, several electric power plants are built on these ridges, producing energy from a vapor-dominated 240 °C reservoir. Only the main hot spring at Anderson Springs has maintained a recognizable identity since the 1930s. The hot spring is actually a cluster of seeps and springs that issue from a small fault in a ravine southwest of Anderson Creek. Published and unpublished records show that the maximum temperature (Tm) of this cluster fell gradually from 63°C in 1889 to 48°C in 1992. However, Tm of the cluster climbed to 77°C in 1995 and neared boiling (98°C) in 1998. A new cluster of boiling vents and small fumaroles (Tm = 99.3°C) formed in 1998 about 30 m north of the old spring cluster. Several evergreen trees on steep slopes immediately above these vents apparently were killed by the new activity. Thermal waters at Anderson Hot Springs are mostly composed of near-surface ground waters with some added gases and condensed steam from The Geysers geothermal system. Compared to gas samples from Southeast Geysers wells, the hot spring gases are higher in CO2 and lower in H2S and NH3. As the springs increased in temperature, however, the gas composition became more like the mean composition

  20. On the possibility of many-body localization in a doped Mott insulator

    Science.gov (United States)

    He, Rong-Qiang; Weng, Zheng-Yu

    2016-01-01

    Many-body localization (MBL) is currently a hot issue of interacting systems, in which quantum mechanics overcomes thermalization of statistical mechanics. Like Anderson localization of non-interacting electrons, disorders are usually crucial in engineering the quantum interference in MBL. For translation invariant systems, however, the breakdown of eigenstate thermalization hypothesis due to a pure many-body quantum effect is still unclear. Here we demonstrate a possible MBL phenomenon without disorder, which emerges in a lightly doped Hubbard model with very strong interaction. By means of density matrix renormalization group numerical calculation on a two-leg ladder, we show that whereas a single hole can induce a very heavy Nagaoka polaron, two or more holes will form bound pair/droplets which are all localized excitations with flat bands at low energy densities. Consequently, MBL eigenstates of finite energy density can be constructed as composed of these localized droplets spatially separated. We further identify the underlying mechanism for this MBL as due to a novel ‘Berry phase’ of the doped Mott insulator, and show that by turning off this Berry phase either by increasing the anisotropy of the model or by hand, an eigenstate transition from the MBL to a conventional quasiparticle phase can be realized. PMID:27752064

  1. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    Energy Technology Data Exchange (ETDEWEB)

    Filatov, Michael, E-mail: mike.filatov@gmail.com [Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314 (United States); Huix-Rotllant, Miquel; Burghardt, Irene [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main (Germany)

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor–acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene–perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  2. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  3. Resources available for nuclear power plant emergencies under the Price-Anderson Act and the Robert T. Stafford Disaster Relief and Emergency Assistance Act

    International Nuclear Information System (INIS)

    Through a series of TABLETOP exercises and other events that involved participation by State and Federal organizations, the need was identified for further explanation of financial and other related resources available to individuals and State and local governments in a major emergency at a nuclear power plant. A group with representatives from the Nuclear Regulatory commission, the Federal Emergency Management Agency, and the American Nuclear Insurers/Mutual Atomic Energy Liability Underwriters was established to work toward this end. This report is the result of that effort. This document is not meant to modify, undermine, or replace any other planning document (e.g., the Federal Radiological Emergency Response Plan or the Federal Response Plan). Its purpose is to clarify issues that have surfaced regarding resources available under the Price-Anderson and Stafford Acts

  4. Anomalous drift of spiral waves in heterogeneous excitable media

    CERN Document Server

    Sridhar, S; Panfilov, Alexander V

    2009-01-01

    We study the drift of spiral waves in a simple model of heterogeneous excitable medium, having gradients in local excitability or cellular coupling. For the first time, we report the anomalous drift of spiral waves towards regions having higher excitability, in contrast to all earlier observations in reaction-diffusion models of excitable media. Such anomalous drift can promote the onset of complex spatio-temporal patterns, e.g., those responsible for life-threatening arrhythmias in the heart.

  5. Weak disorder expansion of the invariant measure for the one-dimensional Anderson model

    Energy Technology Data Exchange (ETDEWEB)

    Bovier, A.; Klein, A.

    1988-05-01

    We show that the formal perturbation expansion of the invariant measure for the Anderson model in one dimension has singularities at all energies E/sub 0/ = 2 cos ..pi..(p/q); we derive a modified expansion near these energies that we show to have finite coefficients to all orders. Moreover, we show that the first q - 3 of them coincide with those of the naive expansion, while there is an anomaly in the (q - 2)th term. This also gives a weak disorder expansion for the Liapunov exponent and for the density of states. This generalizes previous results of Kappus and Wegner and of Derrida and Gardner.

  6. An alternative functional renormalization group approach to the single impurity Anderson model

    OpenAIRE

    Kinza, Michael; Ortloff, Jutta; Bauer, Johannes; Honerkamp, Carsten

    2012-01-01

    We present an alternative functional renormalization group (fRG) approach to the single-impurity Anderson model at finite temperatures. Starting with the exact self-energy and interaction vertex of a small system ('core') containing a correlated site, we switch on the hybridization with a non-interacting bath in the fRG-flow and calculate spectra of the correlated site. Different truncations of the RG-flow-equations and choices of the core are compared and discussed. Furthermore we calculate ...

  7. Data Center Energy Efficiency and Renewable Energy Site Assessment: Anderson Readiness Center; Salem, Oregon

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, I.; Van Geet, O.

    2014-06-01

    This report summarizes the results from the data center energy efficiency and renewable energy site assessment conducted for the Oregon Army National Guard in Salem, Oregon. A team led by NREL conducted the assessment of the Anderson Readiness Center data centers March 18-20, 2014 as part of ongoing efforts to reduce energy use and incorporate renewable energy technologies where feasible. Although the data centers in this facility account for less than 5% of the total square footage, they are estimated to be responsible for 70% of the annual electricity consumption.

  8. Weak Anderson localisation in reverberation rooms and its effect on the uncertainty of sound power measurements

    DEFF Research Database (Denmark)

    Jacobsen, Finn

    2011-01-01

    The effect known as ‘weak Anderson localisation’, ‘coherent backscattering’ or ‘enhanced backscattering’ is a physical phenomenon that occurs in random systems, e.g., disordered media and linear wave systems, including reverberation rooms: the mean square response is increased at the drive point....... In a reverberation room this means that one can expect an increase of the reverberant sound field at the position of the source that generates the sound field. This affects the sound power output of the source and is therefore of practical concern. However, because of the stronger direct sound field...... implications for the uncertainty of sound power measurements....

  9. The Anderson-Darling test of fit for the power law distribution from left censored samples

    CERN Document Server

    Coronel-Brizio, H F

    2010-01-01

    Maximum likelihood estimation and a test of fit based on the Anderson-Darling statistic is presented for the case of the power law distribution when the parameters are estimated from a left-censored sample. Expressions for the maximum likelihood estimators and tables of asymptotic percentage points for the A^2 statistic are given. The technique is illustrated for data from the Dow Jones Industrial Average index, an example of high theoretical and practical importance in Econophysics, Finance, Physics, Biology and, in general, in other related Sciences such as Complexity Sciences.

  10. The exhaustion problem in the periodic Anderson model: An X-boson approach

    Energy Technology Data Exchange (ETDEWEB)

    Franco, R. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia)]. E-mail: rfrancop@unal.edu.co; Silva-Valencia, J. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia); Figueira, M.S. [Instituto de Fisica da Universidade Federal Fluminense, Av. Litoranea s/n, 24210-340 Niteroi, Rio de Janeiro C.P.100.093 (Brazil)

    2006-10-01

    We study the thermodynamical properties of the periodic Anderson model (PAM), within the X-boson approach. The exhaustion problem is studied and we calculate the entropy and the specific heat for the heavy fermion Kondo regime (HF-K) of the PAM. We compute numerically the evolution of the Kondo lattice T{sub KL} and the Fermi liquid T{sup *} temperatures as function of the conduction electron occupation number n{sub c}. The results obtained are consistent with others reported in the literature for the Kondo lattice.

  11. Variational Monte Carlo study of magnetic states in the periodic Anderson model

    Science.gov (United States)

    Kubo, Katsunori

    2015-03-01

    We study the magnetic states of the periodic Anderson model with a finite Coulomb interaction between f electrons on a square lattice by applying variational Monte Carlo method. We consider Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge density wave states. We find an antiferromagnetic phase around half-filling. There is a phase transition accompanying change in the Fermi-surface topology in this antiferromagnetic phase. We also study a case away from half-filling, and find a ferromagnetic state as the ground state there.

  12. Correlation-driven d -wave superconductivity in Anderson lattice model: Two gaps

    Science.gov (United States)

    Wysokiński, Marcin M.; Kaczmarczyk, Jan; Spałek, Józef

    2016-07-01

    Superconductivity in heavy-fermion systems has an unconventional nature and is considered to originate from the universal features of the electronic structure. Here, the Anderson lattice model is studied by means of the full variational Gutzwiller wave function incorporating nonlocal effects of the on-site interaction. We show that the d -wave superconducting ground state can be driven solely by interelectronic correlations. The proposed microscopic mechanism leads to a multigap superconductivity with the dominant contribution due to f electrons and in the dx2-y2-wave channel. Our results rationalize several important observations for CeCoIn5.

  13. The ground state of the Edwards-Anderson spin-glass model in the thermodynamic limit

    CERN Document Server

    Wreszinski, Walter F

    2011-01-01

    We derive rigorous lower bounds for the average ground-state energy per site of the Edwards-Anderson spin-glass model in dimensions two to three in the thermodynamic limit. They imply that the misfit parameter -a convenient measure of frustration- has a lower bound in the thermodynamic limit $\\mu_{0}$ with $\\mu_{0} \\ge 0.125$ in two dimensions and $\\mu_{0} \\ge 0.133$ in three dimensions, which compare well with the lower bounds obtained by Derrida for the random energy model.

  14. Physical, chemical, and isotopic data for samples from the Anderson Springs area, Lake County, California, 1998-1999

    Science.gov (United States)

    Janik, C.J.; Goff, F.; Sorey, M.L.; Rytuba, J.J.; Counce, D.; Colvard, E.M.; Huebner, M.; White, L.D.; Foster, A.

    1999-01-01

    Anderson Springs is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. In the rugged hills to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. In the 1970s, the high-elevation areas surrounding Anderson Springs became part of The Geysers geothermal field. Today, several electric powerplants are located on the ridges above Anderson Springs, utilizing steam produced from a 240°C vapor-dominated reservoir. The primary purpose of this report is to provide physical, chemical, and isotopic data on samples collected in the Anderson Springs area during 1998 and 1999, in response to a Freedom of Information Act request. In July 1998, drainage from the Schwartz adit of the abandoned Anderson mercury mine increased substantially over a 2-day period, transporting a slurry of water and precipitates down a tributary and into Anderson Creek. In August 1998, J.J. Rytuba and coworkers sampled the Schwartz adit drainage and water from the Anderson Springs Hot Spring for base metal and methylmercury analysis. They measured a maximum temperature (Tm) of 85°C in the Hot Spring. Published records show that the temperature of the Anderson Springs Hot Spring (main spring) was 63°C in 1889, 42–52°C from 1974 through 1991, and 77°C in March 1995. To investigate possible changes in thermal spring activity and to collect additional samples for geochemical analysis, C.J. Janik and coworkers returned to the area in September and December 1998. They determined that a cluster of springs adjacent to the main spring had Tm=98°C, and they observed that a new area of boiling vents and small fumaroles (Tm=99.3°C) had formed in an adjacent gully about 20 meters to the north of the main spring

  15. Plasmoelectronics: coupling plasmonic excitation with electron flow.

    Science.gov (United States)

    Warren, Scott C; Walker, David A; Grzybowski, Bartosz A

    2012-06-19

    Explorations of the coupling of light and charge via localized surface plasmons have led to the discovery that plasmonic excitation can influence macroscopic flows of charge and, conversely, that charging events can change the plasmonic excitation. We discuss recent theory and experiments in the emerging field of plasmoelectronics, with particular emphasis on the application of these materials to challenges in nanotechnology, energy use, and sensing. PMID:22385329

  16. Excited states v.6

    CERN Document Server

    Lim, Edward C

    1982-01-01

    Excited States, Volume 6 is a collection of papers that discusses the excited states of molecules. The first paper discusses the linear polyene electronic structure and potential surfaces, considering both the theoretical and experimental approaches in such electronic states. This paper also reviews the theory of electronic structure and cites some experimental techniques on polyene excitations, polyene spectroscopic phenomenology, and those involving higher states of polyenes and their triplet states. Examples of these experimental studies of excited states involve the high-resolution one-pho

  17. Excited states 2

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 2 is a collection of papers that deals with molecules in the excited states. The book describes the geometries of molecules in the excited electronic states. One paper describes the geometries of a diatomic molecule and of polyatomic molecules; it also discusses the determination of the many excited state geometries of molecules with two, three, or four atoms by techniques similar to diatomic spectroscopy. Another paper introduces an ordered theory related to excitons in pure and mixed molecular crystals. This paper also presents some experimental data such as those invo

  18. Electronic structure and correlations of vitamin B12 studied within the Haldane-Anderson impurity model

    Science.gov (United States)

    Kandemir, Zafer; Mayda, Selma; Bulut, Nejat

    2016-04-01

    We study the electronic structure and correlations of vitamin B12 (cyanocobalamine) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition-metal impurity in a semiconductor host. The parameters of the effective Haldane-Anderson model are obtained within the Hartree-Fock (HF) approximation. The quantum Monte Carlo (QMC) technique is then used to calculate the one-electron and magnetic correlation functions of this effective model. We observe that new states form inside the semiconductor gap found by HF due to the intra-orbital Coulomb interaction at the impurity 3d orbitals. In particular, the lowest unoccupied states correspond to an impurity bound state, which consists of states from mainly the CN axial ligand and the corrin ring as well as the Co eg-like orbitals. We also observe that the Co (3d) orbitals can develop antiferromagnetic correlations with the surrounding atoms depending on the filling of the impurity bound states. In addition, we make comparisons of the HF+QMC data with the density functional theory calculations. We also discuss the photoabsorption spectrum of cyanocobalamine.

  19. Dr Walter Henry Anderson (1870-1937) and the mission hospital at Safed, Palestine.

    Science.gov (United States)

    Stokes, Gordon S

    2013-02-01

    Walter Henry Anderson, a brewer's clerk in Burton-upon-Trent, became a missionary doctor, supported by a society promoting welfare and evangelism in Jewish communities abroad. His family background was rich in pastoral ministry at home and adventure abroad. Arguably, this background played a part in his decision to serve the Jews of Safed. His life in Palestine entailed much enterprise and hardship as he raised a family, fought disease and set up a mission hospital serving not only the Jewish community but persons of all faiths. His years in Palestine, from 1894 to 1915, were times of peace in the Middle East before the turmoil unleashed by the Great War. Jews from the Diaspora were gaining an increasing foothold in Palestine, their 'Promised Land'. Themes of that era - the rise of Zionism, confrontation between Judaism and evangelical Christianity, conflict between immigrant Jew and Palestinian Arab and the remarkable travels of Lawrence of Arabia were interwoven with the lives of Dr Anderson and his family. PMID:23610230

  20. Portuguese validation of the Symptom Inventory of the M.D. Anderson Cancer Center

    Directory of Open Access Journals (Sweden)

    Adriane Cristina Bernat Kolankiewicz

    2014-12-01

    Full Text Available Objective To analyze the reliability and validity of the psychometric properties of the Brazilian version of the instrument for symptom assessment, titled MD Anderson Symptom Inventory - core. Method A cross-sectional study with 268 cancer patients in outpatient treatment, in the municipality of Ijuí, state of Rio Grande do Sul, Brazil. Results The Cronbach’s alpha for the MDASI general, symptoms and interferences was respectively (0.857, (0.784 and (0.794. The factor analysis showed adequacy of the data (0.792. In total, were identified four factors of the principal components related to the symptoms. Factor I: sleep problems, distress (upset, difficulties in remembering things and sadness. Factor II: dizziness, nausea, lack of appetite and vomiting. Factor III: drowsiness, dry mouth, numbness and tingling. Factor IV: pain, fatigue and shortness of breath. A single factor was revealed in the component of interferences with life (0.780, with prevalence of activity in general (59.7%, work (54.9% and walking (49.3%. Conclusion The Brazilian version of the MD Anderson Symptom Inventory - core showed adequate psychometric properties in the studied population.

  1. Multi-Particle Anderson Localisation: Induction on the Number of Particles

    CERN Document Server

    Chulaevsky, Victor

    2008-01-01

    This paper is a follow-up of our recent papers \\cite{CS08} and \\cite{CS09} covering the two-particle Anderson model. Here we establish the phenomenon of Anderson localisation for a quantum $N$-particle system on a lattice $\\Z^d$ with short-range interaction and in presence of an IID external potential with sufficiently regular marginal cumulative distribution function (CDF). Our main method is an adaptation of the multi-scale analysis (MSA; cf. \\cite{FS}, \\cite{FMSS}, \\cite{DK}) to multi-particle systems, in combination with an induction on the number of particles, as was proposed in our earlier manuscript \\cite{CS07}. Similar results have been recently obtained in an independent work by Aizenman and Warzel \\cite{AW08}: they proposed an extension of the Fractional-Moment Method (FMM) developed earlier for single-particle models in \\cite{AM93} and \\cite{ASFH01} (see also references therein) which is also combined with an induction on the number of particles. An important role in our proof is played by a varian...

  2. Analysis of Anderson Acceleration on a Simplified Neutronics/Thermal Hydraulics System

    Energy Technology Data Exchange (ETDEWEB)

    Toth, Alex [North Carolina State University (NCSU), Raleigh; Kelley, C. T. [North Carolina State University (NCSU), Raleigh; Slattery, Stuart R [ORNL; Hamilton, Steven P [ORNL; Clarno, Kevin T [ORNL; Pawlowski, R. P. P. [Sandia National Laboratories (SNL)

    2015-01-01

    ABSTRACT A standard method for solving coupled multiphysics problems in light water reactors is Picard iteration, which sequentially alternates between solving single physics applications. This solution approach is appealing due to simplicity of implementation and the ability to leverage existing software packages to accurately solve single physics applications. However, there are several drawbacks in the convergence behavior of this method; namely slow convergence and the necessity of heuristically chosen damping factors to achieve convergence in many cases. Anderson acceleration is a method that has been seen to be more robust and fast converging than Picard iteration for many problems, without significantly higher cost per iteration or complexity of implementation, though its effectiveness in the context of multiphysics coupling is not well explored. In this work, we develop a one-dimensional model simulating the coupling between the neutron distribution and fuel and coolant properties in a single fuel pin. We show that this model generally captures the convergence issues noted in Picard iterations which couple high-fidelity physics codes. We then use this model to gauge potential improvements with regard to rate of convergence and robustness from utilizing Anderson acceleration as an alternative to Picard iteration.

  3. Alternating Anderson-Richardson method: An efficient alternative to preconditioned Krylov methods for large, sparse linear systems

    CERN Document Server

    Suryanarayana, Phanish; Pask, John E

    2016-01-01

    We generalize the recently proposed Alternating Anderson-Jacobi (AAJ) method (Pratapa et al., J. Comput. Phys. (2016), 306, 43--54) to include preconditioning, and demonstrate its efficiency and scaling in the solution of large, sparse linear systems on parallel computers. The resulting preconditioned Alternating Anderson-Richardson (AAR) method reduces to the AAJ method for a particular choice of preconditioner. The AAR method employs Anderson extrapolation at periodic intervals within a preconditioned Richardson iteration to accelerate convergence. In this work, we develop a version of the method that is particularly well suited for scalable high-performance computing. In applications to Helmholtz and Poisson equations, we show that the strong and weak parallel scaling of AAR is superior to both Generalized Minimal Residual (GMRES) and Conjugate Gradient (CG) methods, using the same preconditioning, in large-scale parallel calculations employing up to 110,592 computational cores. Moreover, we find that the ...

  4. Molecular analysis and intestinal expression of SAR1 genes and proteins in Anderson's disease (Chylomicron retention disease

    Directory of Open Access Journals (Sweden)

    Boileau Catherine

    2011-01-01

    Full Text Available Abstract Background Anderson's disease (AD or chylomicron retention disease (CMRD is a very rare hereditary lipid malabsorption syndrome. In order to discover novel mutations in the SAR1B gene and to evaluate the expression, as compared to healthy subjects, of the Sar1 gene and protein paralogues in the intestine, we investigated three previously undescribed individuals with the disease. Methods The SAR1B, SAR1A and PCSK9 genes were sequenced. The expression of the SAR1B and SAR1A genes in intestinal biopsies of both normal individuals and patients was measured by RTqPCR. Immunohistochemistry using antibodies to recombinant Sar1 protein was used to evaluate the expression and localization of the Sar1 paralogues in the duodenal biopsies. Results Two patients had a novel SAR1B mutation (p.Asp48ThrfsX17. The third patient, who had a previously described SAR1B mutation (p.Leu28ArgfsX7, also had a p.Leu21dup variant of the PCSK9 gene. The expression of the SAR1B gene in duodenal biopsies from an AD/CMRD patient was significantly decreased whereas the expression of the SAR1A gene was significantly increased, as compared to healthy individuals. The Sar1 proteins were present in decreased amounts in enterocytes in duodenal biopsies from the patients as compared to those from healthy subjects. Conclusions Although the proteins encoded by the SAR1A and SAR1B genes are 90% identical, the increased expression of the SAR1A gene in AD/CMRD does not appear to compensate for the lack of the SAR1B protein. The PCSK9 variant, although reported to be associated with low levels of cholesterol, does not appear to exert any additional effect in this patient. The results provide further insight into the tissue-specific nature of AD/CMRD.

  5. The Discovery of Anti-Matter The Autobiography of Carl David Anderson, the Youngest Man to Win the Nobel Prize

    CERN Document Server

    1999-01-01

    In 1936, at age 31, Carl David Anderson became the second youngest Nobel laureate for his discovery of antimatter when he observed positrons in a cloud chamber.He is responsible for developing rocket power weapons that were used in World War II.He was born in New York City in 1905 and was educated in Los Angeles. He served for many years as a physics professor at California Institute of Technology. Prior to Oppenheimer, Anderson was offered the job of heading the Los Alamos atomic bomb program but could not assume the role because of family obligations.He was a pioneer in studying cosmic rays

  6. IEEE Milestone at CERN - W Cleon Anderson (right), president of the Institute of Electrical and Electronics Engineers, unveils the Milestone plaque at CERN, together with Georges Charpak

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    At a ceremony on 26 September at CERN, W Cleon Anderson, president of the Institute of Electrical and Electronics Engineers (IEEE), formally dedicated a "Milestone" plaque in recognition of the invention of electronic particle detectors at CERN. The plaque was unveiled by Anderson and Georges Charpak, the Nobel-prize winning inventor of wire-chamber technology at CERN.

  7. Nuclear structure studies using the high resolution spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility: Annual progress report, [1987-1988

    International Nuclear Information System (INIS)

    This document constitutes the (1987 to 1988) progress report for the ongoing medium energy nuclear physics research program supported by the US Department of Energy with the University of Texas at Austin. A major part of the work has been and will continue to be associated with research done at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF) using the High Resolution Spectrometer (HRS), the External Proton Beam (EPB), and the new Neutron Time of Flight Facility (NTOF). Other research is done at the Fermi National Accelerator Laboratory (FNAL). The research focuses on (1) providing proton + nucleus data which test nonrelativistic and relativistic models of the medium energy proton + nucleus interaction, (2) providing (p,p) and (p,n) data which are to be analyzed to provide new nuclear structure information (both ground state and excited state), (3) providing nucleon + nucleon data to aid in the systematic study of the fundamental nucleon-nucleon interaction, (4) developing and improving the proton + nucleus theoretical models themselves, and (5) initiating new experimental programs whose goals are to search for new phenomena in nuclear physics. 182 refs., 71 figs., 5 tabs

  8. Surface plasmon interference excited by tightly focused laser beams.

    Energy Technology Data Exchange (ETDEWEB)

    Bouhelier, A.; Ignatovich, F.; Bruyant, A.; Huang, C.; Colas des Francs, G.; Weeber, J.-C.; Dereux, A.; Wiederrecht, G. P.; Novotny, L.; Center for Nanoscale Materials; Univ de Bourgogne; Univ. of Rochester; Univ Technologique de Troyes

    2007-09-01

    We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.

  9. Percolation of optical excitation mediated by near-field interactions

    CERN Document Server

    Naruse, Makoto; Takahashi, Taiki; Aono, Masashi; Akahane, Kouichi; D'Acunto, Mario; Hori, Hirokazu; Thylen, Lars; Katori, Makoto; Ohtsu, Motoichi

    2016-01-01

    Optical excitation transfer in nanostructured matter has been intensively studied in various material systems for versatile applications. Herein, we discuss the percolation of optical excitations in randomly organized nanostructures caused by optical near-field interactions governed by Yukawa potential in a two-dimensional stochastic model. The model results demonstrate the appearance of two phases of percolation of optical excitation as a function of the localization degree of near-field interaction. Moreover, it indicates sublinear scaling with percolation distance when the light localization is strong. The results provide fundamental insights into optical excitation transfer and will facilitate the design and analysis of nanoscale signal-transfer characteristics.

  10. Low-lying excitations in a strongly interacting Fermi gas

    Science.gov (United States)

    Vale, Christopher; Hoinka, Sascha; Dyke, Paul; Lingham, Marcus

    2016-05-01

    We present measurements of the low-lying excitation spectrum of a strongly interacting Fermi gas across the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover using Bragg spectroscopy. By focussing the Bragg lasers onto the central volume of the cloud we can probe atoms at near-uniform density allowing measurement of the homogeneous density-density response function. The Bragg wavevector is set to be approximately half of the Fermi wavevector to probe the collective response. Below the superfluid transition temperature the Bragg spectra dominated by the Bogoliubov-Anderson phonon mode. Single particle excitations become visible at energies greater than twice the pairing gap. As interactions are tuned from the BCS to BEC regime the phonon and single particle modes separate apart and both the pairing gap and speed of sound can be directly read off in certain regions of the crossover. Single particle pair-breaking excitations become heavily suppressed as interactions are tuned from the BCS to BEC regimes.

  11. Excited states 4

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 4 is a collection of papers that deals with the excited states of molecular activity. One paper investigates the resonance Raman spectroscopy as the key to vibrational-electronic coupling. This paper reviews the basic theory of Raman scattering; it also explains the derivation of the Raman spectra, excitation profiles, and depolarization ratios for simple resonance systems. Another paper reviews the magnetic properties of triplet states, including the zero-field resonance techniques, the high-field experiments, and the spin Hamiltonian. This paper focuses on the magnetic

  12. Localization of phonon-polaritons in disordered polar media

    OpenAIRE

    Satanin, Arkadii; Joe, Yong; Kim, Chang Sub; Vasilevskiy, Mikhail

    2005-01-01

    The localization of the hybrid modes of phonons and photons in polar matter is investigated in the presence of random scatterers theoretically. We employ the self-consistent generalized Born-Huang approach to derive effective equations describing the phonon-polariton fields. Based on these equations, the density of states and various localization properties are exploited in two-dimensional systems both analytically and numerically within the framework of the Anderson model with a non-Hermi...

  13. Classical mapping for Hubbard operators: application to the double-Anderson model.

    Science.gov (United States)

    Li, Bin; Miller, William H; Levy, Tal J; Rabani, Eran

    2014-05-28

    A classical Cartesian mapping for Hubbard operators is developed to describe the nonequilibrium transport of an open quantum system with many electrons. The mapping of the Hubbard operators representing the many-body Hamiltonian is derived by using analogies from classical mappings of boson creation and annihilation operators vis-à-vis a coherent state representation. The approach provides qualitative results for a double quantum dot array (double Anderson impurity model) coupled to fermionic leads for a range of bias voltages, Coulomb couplings, and hopping terms. While the width and height of the conduction peaks show deviations from the master equation approach considered to be accurate in the limit of weak system-leads couplings and high temperatures, the Hubbard mapping captures all transport channels involving transition between many electron states, some of which are not captured by approximate nonequilibrium Green function closures.

  14. Multichannel Numerical Renormalization Group study of the Anderson Hamiltonian with multiple impurities

    Science.gov (United States)

    Stokes, James; Konik, Robert

    2014-03-01

    Using the Numerical Renormalization Group (NRG), the low energy sector of the Anderson Hamiltonian with two impurities in parallel has been previously argued to be consistent with an underscreened spin-1 Kondo effect (R. Zitko and J. Bonca, Phys. Rev. B 76, 241305 (2007); Logan et al., Phys. Rev. B 80, 125117 (2009)). Bethe Ansatz and slave boson calculations have given the ground state as a singlet (M. Kulkarni and R. M. Konik, Phys. Rev. B 83, 245121 (2011)). As an attempt to understand these differences, we have developed a modified NRG routine that takes into account the multiple channels arising from the logarithmic discretization of the Fermi sea. This could conceivably allow for more complicated screening processes suggested by the Bethe ansatz computations. Results of studies using this code for various numbers of impurities and channels will be presented and discussed in relationship to these conflicting views.

  15. Leveraging Anderson Acceleration for improved convergence of iterative solutions to transport systems

    Energy Technology Data Exchange (ETDEWEB)

    Willert, Jeffrey; Taitano, William T.; Knoll, Dana

    2014-09-15

    In this note we demonstrate that using Anderson Acceleration (AA) in place of a standard Picard iteration can not only increase the convergence rate but also make the iteration more robust for two transport applications. We also compare the convergence acceleration provided by AA to that provided by moment-based acceleration methods. Additionally, we demonstrate that those two acceleration methods can be used together in a nested fashion. We begin by describing the AA algorithm. At this point, we will describe two application problems, one from neutronics and one from plasma physics, on which we will apply AA. We provide computational results which highlight the benefits of using AA, namely that we can compute solutions using fewer function evaluations, larger time-steps, and achieve a more robust iteration.

  16. Multifractality at non-Anderson disorder-driven transitions in Weyl semimetals and other systems

    Science.gov (United States)

    Syzranov, S. V.; Gurarie, V.; Radzihovsky, L.

    2016-10-01

    Systems with the power-law quasiparticle dispersion ɛk ∝kα exhibit non-Anderson disorder-driven transitions in dimensions d > 2 α, as exemplified by Weyl semimetals, 1D and 2D arrays of ultracold ions with long-range interactions, quantum kicked rotors, and semiconductor models in high dimensions. We study the wavefunction structure in such systems and demonstrate that at these transitions they exhibit fractal behaviour with an infinite set of multifractal exponents. The multifractality persists even when the wavefunction localisation is forbidden by symmetry or topology and occurs as a result of elastic scattering between all momentum states in the band on length scales shorter than the mean free path. We calculate explicitly the multifractal spectra in semiconductors and Weyl semimetals using one-loop and two-loop renormalisation-group approaches slightly above the marginal dimension d = 2 α.

  17. Anderson-Holstein model in two flavors of the noncrossing approximation

    Science.gov (United States)

    Chen, Hsing-Ta; Cohen, Guy; Millis, Andrew J.; Reichman, David R.

    2016-05-01

    The dynamical interplay between electron-electron interactions and electron-phonon coupling is investigated within the Anderson-Holstein model, a minimal model for open quantum systems that embody these effects. The influence of phonons on spectral and transport properties is explored in equilibrium, for nonequilibrium steady state and for transient dynamics after a quench. Both the particle-hole symmetric and the more generic particle-hole asymmetric cases are studied. The treatment is based on two complementary noncrossing approximations, the first of which is constructed around the weak-coupling limit and the second around the polaron limit. In general, the two methods disagree in nontrivial ways, indicating that more reliable approaches to the problem are needed. The frameworks used here can form the starting point for numerically exact methods based on bold-line continuous-time quantum Monte Carlo algorithms capable of treating open systems simultaneously coupled to multiple fermionic and bosonic baths.

  18. Leveraging Anderson Acceleration for improved convergence of iterative solutions to transport systems

    International Nuclear Information System (INIS)

    In this note we demonstrate that using Anderson Acceleration (AA) in place of a standard Picard iteration can not only increase the convergence rate but also make the iteration more robust for two transport applications. We also compare the convergence acceleration provided by AA to that provided by moment-based acceleration methods. Additionally, we demonstrate that those two acceleration methods can be used together in a nested fashion. We begin by describing the AA algorithm. At this point, we will describe two application problems, one from neutronics and one from plasma physics, on which we will apply AA. We provide computational results which highlight the benefits of using AA, namely that we can compute solutions using fewer function evaluations, larger time-steps, and achieve a more robust iteration

  19. VizieR Online Data Catalog: Radio observations of Galactic WISE HII regions (Anderson+, 2015)

    Science.gov (United States)

    Anderson, L. D.; Armentrout, W. P.; Johnstone, B. M.; Bania, T. M.; Balser, D. S.; Wenger, T. V.; Cunningham, V.

    2016-01-01

    We draw our targets from the MIR objects in the WISE catalog of Anderson+, 2014, J/ApJS/212/1. We also include in our sample Sharpless H II regions (Sharpless 1959, VII/20). See section 2 for further details. Our observations were made with the GBT 100m telescope from 2012 July through 2014 August. There are seven radio recombination lines (RRLs) that can be cleanly observed simultaneously with the GBT in the X-band: H87α to H93α. We average these seven RRLs (each at two orthogonal polarizations) to create a single average RRL spectrum. We followed the same GBT observational procedure as in the original HRDS (Green Bank Telescope H II Region Discovery Survey (GBT HRDS; Bania et al. 2010ApJ...718L.106B). (3 data files).

  20. Buildup of the Kondo effect from real-time effective action for the Anderson impurity model

    Science.gov (United States)

    Bock, Sebastian; Liluashvili, Alexander; Gasenzer, Thomas

    2016-07-01

    The nonequilibrium time evolution of a quantum dot is studied by means of dynamic equations for time-dependent Green's functions derived from a two-particle-irreducible (2PI) effective action for the Anderson impurity model. Coupling the dot between two leads at different voltages, the dynamics of the current through the dot is investigated. We show that the 2PI approach is capable of describing the dynamical buildup of the Kondo effect, which shows up as a sharp resonance in the spectral function, with a width exponentially suppressed in the electron self-coupling on the dot. An external voltage applied to the dot is found to deteriorate the Kondo effect at the hybridization scale. The dynamic equations are evaluated within different nonperturbative resummation schemes, within the direct, particle-particle, and particle-hole channels, as well as their combination, and the results compared with those from other methods.

  1. Superposition of Fragment Excitations for Excited States of Large Clusters with Application to Helium Clusters.

    Science.gov (United States)

    Closser, Kristina D; Ge, Qinghui; Mao, Yuezhi; Shao, Yihan; Head-Gordon, Martin

    2015-12-01

    We develop a local excited-state method, based on the configuration interaction singles (CIS) wave function, for large atomic and molecular clusters. This method exploits the properties of absolutely localized molecular orbitals (ALMOs), which strictly limits the total number of excitations, and results in formal scaling with the third power of the system size for computing the full spectrum of ALMO-CIS excited states. The derivation of the equations and design of the algorithm are discussed in detail, with particular emphasis on the computational scaling. Clusters containing ∼500 atoms were used in evaluating the scaling, which agrees with the theoretical predictions, and the accuracy of the method is evaluated with respect to standard CIS. A pioneering application to the size dependence of the helium cluster spectrum is also presented for clusters of 25-231 atoms, the largest of which results in the computation of 2310 excited states per sampled cluster geometry. PMID:26609558

  2. Oblique Axis Body Fracture: An Unstable Subtype of Anderson Type III Odontoid Fractures—Apropos of Two Cases

    Directory of Open Access Journals (Sweden)

    Hirokazu Takai

    2016-01-01

    Full Text Available Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced Anderson type III fractures with a characteristic fracture pattern that we refer to as “oblique type axis body fracture.” Results. The female patients aged 90 and 72 years, respectively, were both diagnosed with minimally displaced Anderson type III fractures. Both fractures had a characteristic “oblique type” fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1–C3/4 posterior fusion and the course was uneventful. Conclusions. Oblique type axis body fractures resemble a highly unstable subtype of Anderson type III fractures with the potential of severe secondary deformity following conservative treatment, irrespective of initial grade of displacement. The authors therefore warrant a high index of suspicion for this injury and suggest early operative stabilization.

  3. 77 FR 72906 - Chessie Logistics Co., LLC-Acquisition and Operation Exemption-J. Emil Anderson & Son, Inc.

    Science.gov (United States)

    2012-12-06

    ... Surface Transportation Board Chessie Logistics Co., LLC--Acquisition and Operation Exemption-- J. Emil Anderson & Son, Inc. Chessie Logistics Co., LLC (Chessie), a noncarrier, has filed a verified notice of... copy of each pleading must be served on Ariel A. Erbacher, Legal Counsel, Chessie Logistics Co.,...

  4. Scully : võin ka lolli mängida / Gillian Anderson ; tõlk. Triin Tael

    Index Scriptorium Estoniae

    Anderson, Gillian

    2008-01-01

    USA sarjale "The X-Files" põhinev teine järjefilm "Salatoimikud: Ma tahan uskuda" ("The X-Files: I Want to Believe") : režissöör Chris Carter : peaosades David Duchovny, Gillian Anderson : Ameerika Ühendriigid - Kanada 2008. Intervjuu ilmus juulis portaalis USA Weekend

  5. Qualitative breakdown of the noncrossing approximation for the symmetric one-channel Anderson impurity model at all temperatures

    Science.gov (United States)

    Sposetti, C. N.; Manuel, L. O.; Roura-Bas, P.

    2016-08-01

    The Anderson impurity model is studied by means of the self-consistent hybridization expansions in its noncrossing (NCA) and one-crossing (OCA) approximations. We have found that for the one-channel spin-1 /2 particle-hole symmetric Anderson model, the NCA results are qualitatively wrong for any temperature, even when the approximation gives the exact threshold exponents of the ionic states. Actually, the NCA solution describes an overscreened Kondo effect, because it is the same as for the two-channel infinite-U single-level Anderson model. We explicitly show that the NCA is unable to distinguish between these two very different physical systems, independently of temperature. Using the impurity entropy as an example, we show that the low-temperature values of the NCA entropy for the symmetric case yield the limit Simp(T =0 ) →ln√{2 }, which corresponds to the zero temperature entropy of the overscreened Kondo model. Similar pathologies are predicted for any other thermodynamic property. On the other hand, we have found that the OCA approach lifts the artificial mapping between the models and restores correct properties of the ground state, for instance, a vanishing entropy at low enough temperatures Simp(T =0 ) →0 . Our results indicate that the very well known NCA should be used with caution close to the symmetric point of the Anderson model.

  6. The role of Rh on a substituted Al Anderson heteropolymolybdate: Thermal and hydrotreating catalytic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cabello, Carmen I. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge J. Ronco, CINDECA - CONICET-Universidad Nacional de La Plata, Calle 47 No 257 (1900) La Plata, Buenos Aires (Argentina)]. E-mail: ccabello@quimica.unlp.edu.ar; Munoz, Mercedes [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge J. Ronco, CINDECA - CONICET-Universidad Nacional de La Plata, Calle 47 No 257 (1900) La Plata, Buenos Aires (Argentina); Botto, Irma L. [Centro de Quimica Inorganica CEQUINOR - CONICET-Universidad Nacional de La Plata (1900) La Plata, Buenos Aires (Argentina); Payen, Edmond [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Universite des Sciences et Technologies de Lille, Bat. C3, 59655 Villeneuve d' Ascq Cedex (France)

    2006-08-01

    The influence of Rh heteroatom on the molybdenum reducibility in the Anderson-type heteropolyoxomolybdate structure of formula (NH{sub 4}){sub 3}[RhMo{sub 6}O{sub 24}H{sub 6}].7H{sub 2}O was investigated by means of TPR technique. With comparative purposes, the thermal behavior in non-reducing conditions was also carried out by means of TGA-DTA studies. The study was performed by XRD, SEM, EDAX and FTIR-Raman techniques. Results were related to those preliminary measurements over other XMo{sub 6} Anderson phases. Likewise, Rh(III)-Al(III) formal replacement in the RhMo{sub 6} structural arrangement was proved. The formation of a solid solution in a limited range of composition (up to 0.25 Rh) was established in order to explore the catalytic performance of {gamma}-Al{sub 2}O{sub 3} supported planar heteropolyoxomolybdate, aiming at optimizing the noble metal content in the catalytic system. Preliminary measurements of RhMo{sub 6}/{gamma}-Al{sub 2}O{sub 3} and (Rh, Al)Mo{sub 6}/{gamma}-Al{sub 2}O{sub 3} activity for HDS and HYD processes were also performed. These results were compared to those obtained for CoMo{sub 6}/{gamma}-Al{sub 2}O{sub 3} system in similar operating conditions and other conventional catalytic systems. The potentiality and scope of RhMo{sub 6} catalytic system for the HDS and HYD processes were analyzed.

  7. Phase diagram and reentrance for the 3D Edwards–Anderson model using information theory

    Energy Technology Data Exchange (ETDEWEB)

    Cortez, V. [Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Avenida Diagonal las Torres 2640, Peñalolén, Santiago (Chile); Saravia, G.; Vogel, E.E. [Departamento de Ciencias Físicas, Universidad de La Frontera, Casilla 54-D, Temuco (Chile)

    2014-12-15

    Data compressor techniques are used to study the phase diagram of the generalized Edwards–Anderson model in three dimensions covering the full range of mixture between ferromagnetic (concentration 1−x) and antiferromagnetic interactions (concentration x). The recently proposed data compressor wlzip is used to recognize criticality by the maximum information content in the files storing the simulation processes. The method allows not only the characterization of the ferromagnetic to paramagnetic (FP) transition (x<0.22, or x>0.78) but also it equally well yields the spin-glass to paramagnetic (SP) transition (0.22Anderson model. • Ferromagnetic to paramagnetic and spin-glass to paramagnetic transitions are found. • A reentrant behavior is reported near the triple point. • Data compressor wlzip can operate for the full range of the phase diagram. • Results are robust with respect to equilibration and lattices size effects are small.

  8. Phase diagram and reentrance for the 3D Edwards–Anderson model using information theory

    International Nuclear Information System (INIS)

    Data compressor techniques are used to study the phase diagram of the generalized Edwards–Anderson model in three dimensions covering the full range of mixture between ferromagnetic (concentration 1−x) and antiferromagnetic interactions (concentration x). The recently proposed data compressor wlzip is used to recognize criticality by the maximum information content in the files storing the simulation processes. The method allows not only the characterization of the ferromagnetic to paramagnetic (FP) transition (x<0.22, or x>0.78) but also it equally well yields the spin-glass to paramagnetic (SP) transition (0.22Anderson model. • Ferromagnetic to paramagnetic and spin-glass to paramagnetic transitions are found. • A reentrant behavior is reported near the triple point. • Data compressor wlzip can operate for the full range of the phase diagram. • Results are robust with respect to equilibration and lattices size effects are small

  9. Excitable Scale Free Networks

    CERN Document Server

    Copelli, Mauro

    2007-01-01

    When a simple excitable system is continuously stimulated by a Poissonian external source, the response function (mean activity versus stimulus rate) generally shows a linear saturating shape. This is experimentally verified in some classes of sensory neurons, which accordingly present a small dynamic range (defined as the interval of stimulus intensity which can be appropriately coded by the mean activity of the excitable element), usually about one or two decades only. The brain, on the other hand, can handle a significantly broader range of stimulus intensity, and a collective phenomenon involving the interaction among excitable neurons has been suggested to account for the enhancement of the dynamic range. Since the role of the pattern of such interactions is still unclear, here we investigate the performance of a scale-free (SF) network topology in this dynamic range problem. Specifically, we study the transfer function of disordered SF networks of excitable Greenberg-Hastings cellular automata. We obser...

  10. Laser pulses for coherent xuv Raman excitation

    CERN Document Server

    Greenman, Loren; Whaley, K Birgitta

    2014-01-01

    We combine multi-channel electronic structure theory with quantum optimal control to derive Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and phase control facilitated by the pump pulse carrier envelope phase. Our results open a route to creating core-hole excitations in molecules and aggregates that locally address specific atoms and represent the first step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

  11. Optical Excitation and Probing of Bottle Microresonators

    Science.gov (United States)

    Murugan, G. Senthil; Wilkinson, J. S.; Zervas, M. N.

    2010-11-01

    Fiber bottle microresonators supporting helical whispering gallery modes and exhibiting field maxima symmetrically located on either side of the neck of the bottle have been demonstrated. Channel dropping characteristics have been studied experimentally for the first time in this type of microresonator, using tapered excitation and probe fibers symmetrically placed on both sides of the bottle microresonator. Selective excitation on one side of the bottle microresonator leads to symmetrically located turning points and power localization on both sides of the bottle, leading to the potential to construct add-drop filters.

  12. Hardness and excitation energy

    Indian Academy of Sciences (India)

    Á Nagy

    2005-09-01

    The concept of the ensemble Kohn-Sham hardness is introduced. It is shown that the first excitation energy can be given by the Kohn-Sham hardness (i.e. the energy difference of the ground-state lowest unoccupied and highest occupied levels) plus an extra term coming from the partial derivative of the ensemble exchange-correlation energy with respect to the weighting factor in the limit → 0. It is proposed that the first excitation energy can be used as a reactivity index instead of the hardness.

  13. The Anderson nomograms for permanent interstitial prostate implants: a briefing for practitioners

    International Nuclear Information System (INIS)

    Purpose: The objective of this report is to re-evaluate the role of the Anderson nomograms in treatment planning for permanent prostate implants. The incentive for revisiting this topic concerns three issues: (1) Although nomograms continue to be used in many centers for ordering seeds, few centers use them during treatment planning; (2) Whereas nomograms were designed to deliver a minimum peripheral dose for a uniform distribution of seeds in the gland, many practitioners use peripheral seed loading patterns to reduce urethral toxicity; and (3) As preoperative and intraoperative treatment planning is becoming standard, the apparent role of nomograms is diminished. The nomogram method is reviewed in terms of: (1) total activity predicted, (2) target coverage (as planned in the operating room and as calculated from postimplant computed tomography studies), and (3) reproducibility (i.e., patient-to-patient and planner-to-planner variability). In each case, the computer-optimization system for intraoperative planning currently in use at our institution was taken as the 'gold standard'. Methods and Materials: We compared for the same patient the results of nomogram planning to those yielded by genetic algorithm (GA) optimization in terms of total activity predicted (n=20 cases) and percent target coverage (n=5 cases). Furthermore, we examined retrospectively the dosimetry of 61 prostate implants planned with the GA (n=27) and the current implementation of Anderson nomograms (n=34). Results: Nomogram predictions of the total activity required are in good agreement (within 10%) with the GA-planned activity. However, computer-optimized plans consistently yield superior plans, as reflected in both pre- and postimplant analyses. We find also that user (specifically, treatment planner) implementation of the nomograms may be a major source of variability in nomogram planning - a difficulty to which robust computer optimization is less prone. Conclusions: Nomograms continue to

  14. Excitation Methods for Bridge Structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  15. Vacuum excitation by sudden (dis-)appearance of a Dirichlet wall in a cavity

    CERN Document Server

    Harada, Tomohiro; Miyamoto, Umpei

    2016-01-01

    Vacuum excitation by time-varying boundary conditions is not only of fundamental importance but also has recently been confirmed in a laboratory experiment. In this paper, we study the vacuum excitation of a scalar field by the instantaneous appearance and disappearance of a both-sided Dirichlet wall in the middle of a 1D cavity, as toy models of bifurcating and merging spacetimes, respectively. It is shown that the energy flux emitted positively diverges on the null lines emanating from the (dis-)appearance event, which is analogous to the result of Anderson and DeWitt. This result suggests that the semiclassical effect prevents the spacetime both from bifurcating and merging. In addition, we argue that the diverging flux in the disappearance case plays an interesting role to compensate for the lowness of ambient energy density after the disappearance, which is lower than the zero-point level.

  16. Vacuum excitation by sudden appearance and disappearance of a Dirichlet wall in a cavity

    Science.gov (United States)

    Harada, Tomohiro; Kinoshita, Shunichiro; Miyamoto, Umpei

    2016-07-01

    Vacuum excitation by time-varying boundary conditions is not only of fundamental importance but also has recently been confirmed in a laboratory experiment. In this paper, we study the vacuum excitation of a scalar field by the instantaneous appearance and disappearance of a two-sided Dirichlet wall in the middle of a one-dimensional cavity, as toy models of bifurcating and merging spacetimes, respectively. It is shown that the energy flux emitted positively diverges on the null lines emanating from the appearance and disappearance events, which is analogous to the result of Anderson and DeWitt. This result suggests that the semiclassical effect prevents the spacetime both from bifurcating and merging. In addition, we argue that the diverging flux in the disappearance case plays an interesting role to compensate for the low ambient energy density after the disappearance, which is lower than the zero-point level.

  17. Positron excitation of neon

    Science.gov (United States)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  18. Decoherence at constant excitation

    Science.gov (United States)

    Torres, J. M.; Sadurní, E.; Seligman, T. H.

    2012-02-01

    We present a simple exactly solvable extension of the Jaynes-Cummings model by adding dissipation. This is done such that the total number of excitations is conserved. The Liouville operator in the resulting master equation can be reduced to blocks of 4×4 matrices.

  19. Decoherence at constant excitation

    CERN Document Server

    Torres, Juan Mauricio; Seligman, Thomas H

    2011-01-01

    We present a simple exactly solvable extension of of the Jaynes-Cummings model by adding dissipation. This is done such that the total number of excitations is conserved. The Liouville operator in the resulting master equation can be reduced to blocks of $4\\times 4$ matrices.

  20. Excited lepton search

    International Nuclear Information System (INIS)

    Using the CELLO detector at PETRA we have searched for excited leptons by studying e+e- interactions which yield rho+rho-γγ, rho+rho-γ and γγ final states, where l=e, μ or tau. We observe good agreement with QED and set new limits on e*, μ* and tau* production

  1. Local measurement for structural health monitoring

    Institute of Scientific and Technical Information of China (English)

    G.Z.Qi; Guo Xun; Qi Xiaozhai; W. Dong; P.Chang

    2005-01-01

    Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fundamental issues about the local measurement for structural health monitoring including (1) the necessity of making local measurement, (2) the difficulty of making local measurement and (3) how to make local measurement are addressed in this paper. The results from both the analysis and the tests show that the local measurement can successfully monitor the structural health status as long as the local modes are excited. Unfortunately, the results also illustrate that it is difficult to excite local modes in a structure.Therefore, in order to carry structural health monitoring into effect, we must (1) ensure that the local modes are excited, and (2) deploy enough sensors in a structure so that the local modes can be monitored.

  2. Quantum Electrodynamics with Semiconductor Quantum Dots Coupled to Anderson‐localized Random Cavities

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;

    2011-01-01

    of the spontaneous emission decay rate by up to a factor 15 and an efficiency of channeling single photons into Anderson-localized modes reaching values as high as 94%. These results prove that disordered photonic media provide an efficient platform for quantum electrodynamics, offering a novel route to quantum...

  3. Influence of local spin polarization to the Kondo effect

    Institute of Scientific and Technical Information of China (English)

    LI Huan; GUO Wei

    2007-01-01

    We use the spin non-degenerate single impurity Anderson model to investigate the influence of the local spin polarization to the Kondo effect. By using the Schrieffer-Wolff transformation, we obtain a generalized s-d exchange Hamiltonian, which describes the interaction between a polarized local spin and conduction electrons. In this case, the singlet is no longer an eigenstate as shown by variational calculations where the splitting of the local energy △= εd↑ - εd↓ can be arbitrarily small. The local spin polarization generates the instability of the singlet ground state of the S = 1/2 s-d exchange model.

  4. Route to strong localization of light: The role of disorder

    KAUST Repository

    Molinari, Diego P.

    2012-01-01

    By employing Random Matrix Theory (RMT) and firstprinciple calculations, we investigated the behavior of Anderson localization in 1D, 2D and 3D systems characterized by a varying disorder. In particular, we considered random binary layer sequences in 1D and structurally disordered photonic crystals in two and three dimensions. We demonstrated the existence of a unique optimal degree of disorder that yields the strongest localization possible. In this regime, localized modes are constituted by defect states, which can show subwavelength confinement properties. These results suggest that disorder offers a new avenue for subwavelength light localization in purely dielectric media. © 2012 Optical Society of America.

  5. Nonequilibrium transport in the Anderson-Holstein model with interfacial screening

    Science.gov (United States)

    Perfetto, Enrico; Stefanucci, Gianluca

    Image charge effects in nanoscale junctions with strong electron-phonon coupling open the way to unexplored physical scenarios. Here we present a comprehensive study of the transport properties of the Anderson-Holstein model in the presence of dot-lead repulsion. We propose an accurate many-body approach to deal with the simultaneous occurrence of the Franck-Condon blockade and the screening-induced enhancement of the polaron mobility. Remarkably, we find that a novel mechanism of negative differential conductance origins from the competition between the charge blocking due to the electron-phonon interaction and the charge deblocking due to the image charges. An experimental setup to observe this phenomenon is discussed. References [1]E. Perfetto, G. Stefanucci and M. Cini, Phys. Rev. B 85, 165437 (2012). [2] E. Perfetto and G. Stefanucci, Phys. Rev. B 88, 245437 (2013). [3] E. Perfetto and G. Stefanucci, Journal of Computational Electronics 14, 352 (2015). E.P. and G.S. acknowledge funding by MIUR FIRB Grant No. RBFR12SW0J.

  6. An inventory of wetlands in the East Fork Poplar Creek floodplain, Anderson and Roane Counties, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-12-01

    An inventory of wetlands within the floodplain of East Fork Poplar Creek (EFPC) in Anderson and Roane Counties, Tennessee was conducted during October, 1991 through May, 1992 for the US Department of Energy (DOE) by the US Army Corps of Engineers, Nashville District. About 15 miles of EFPC channel and 500 acres of its floodplain are contaminated with mercury and other contaminants released from the Y-12 Plant on the DOE Oak Ridge Reservation. The wetland inventory will serve as baseline information for DOE`s remedial action planning and National Environmental Policy Act compliance efforts related to the contamination. In order to provide broad wetland determinations beyond which future wetland definitions are unlikely to expand, the 1989 Federal Manual for Identifying And Delineating Jurisdictional Wetlands was utilized. Using the manual`s methodology in a contaminated system under the approved health and safety plan presented some unique problems, resulting in intrusive sampling for field indicators of hydric soils being accomplished separately from observation of other criteria. Beginning with wetland areas identified on National Wetland Inventory Maps, the entire floodplain was examined for presence of wetland criteria, and 17 wetlands were identified ranging from 0.01 to 2.81 acres in size. The majority of wetlands identified were sized under 1 acre. Some of the wetlands identified were not delineated on the National Wetland Inventory Maps, and much of the wetland area delineated on the maps did not meet the criteria under the 1989 manual.

  7. Quantum-Mechanical Variant of the Thouless-Anderson-Palmer Equation for Error-Correcting Codes

    Science.gov (United States)

    Inoue, J.; Saika, Y.; Okada, M.

    Statistical mechanics of information has been applied to problems in various research topics of information science and technology [1],[2]. Among those research topics, error-correcting code is one of the most developed subjects. In the research field of error-correcting codes, Nicolas Sourlas showed that the so-called convolutional codes can be constructed by spin glass with infinite range p-body interactions and the decoded message should be corresponded to the ground state of the Hamiltonian [3]. Ruján pointed out that the bit error can be suppressed if one uses finite temperature equilibrium states as the decoding result, instead of the ground state [4], and the so-called Bayes-optimal decoding at some specific condition was proved by Nishimori [5] and Nishimori and Wong [6]. Kabashima and Saad succeeded in constructing more practical codes, namely low-density parity check (LDPC) codes by using the infinite range spin glass model with finite connectivities [7]. They used the so-called TAP (Thouless-Anderson-Palmer) equations to decode the original message for a given parity check.

  8. Asymptotic Behavior of Excitable Cellular Automata

    CERN Document Server

    Durrett, R; Durrett, Richard; Griffeath, David

    1993-01-01

    Abstract: We study two families of excitable cellular automata known as the Greenberg-Hastings Model (GHM) and the Cyclic Cellular Automaton (CCA). Each family consists of local deterministic oscillating lattice dynamics, with parallel discrete-time updating, parametrized by the range of interaction, the "shape" of its neighbor set, threshold value for contact updating, and number of possible states per site. GHM and CCA are mathematically tractable prototypes for the spatially distributed periodic wave activity of so-called excitable media observed in diverse disciplines of experimental science. Earlier work by Fisch, Gravner, and Griffeath studied the ergodic behavior of these excitable cellular automata on Z^2, and identified two distinct (but closely-related) elaborate phase portraits as the parameters vary. In particular, they noted the emergence of asymptotic phase diagrams (and Euclidean dynamics) in a well-defined threshold-range scaling limit. In this study we present several rigorous results and som...

  9. Two independent pivotal statistics that test location and misspecification and add-up to the Anderson-Rubin statistic

    OpenAIRE

    Kleibergen, F.R.

    2002-01-01

    We extend the novel pivotal statistics for testing the parameters in the instrumental variables regression model. We show that these statistics result from a decomposition of the Anderson-Rubin statistic into two independent pivotal statistics. The first statistic is a score statistic that tests location and the second statistic tests misspecification. We obtain the conditional distribution of the likelihood ratio statistic that tests location in case of multiple parameters of interest. This ...

  10. The Paean of Old People’s Love--The Appreciation and Analysis of Burns’John Anderson, My Jo

    Institute of Scientific and Technical Information of China (English)

    李圣轩

    2013-01-01

    Robert Burns is a great Romanticism poet in Scotland; his poem absorbs the essence of Scotland ballad, and has the national feature. The poem John Anderson, My Jo, Burns chooses the subject matter from the old people’s love and praises their love as if praises the beautiful setting sun. This paper aims to appreciate this poem from the perspective of rhythm, content and form.

  11. : Community of Inquiry en E-learning : à propos du modèle de Garrison et d'Anderson

    OpenAIRE

    Jézégou, Annie

    2010-01-01

    This article is based on a constructively critical analysis of the model of community of inquiry developed by Garrison and Anderson (2003) as part of a research conducted in the area of e-learning. The authors claim that certain collaborative interactions create "distant presence" fostering the emergence of a community of inquiry which has a positive influence on individual and collective learning. More specifically, the article points out that until now, the model's theoretical foundations h...

  12. Community of Inquiry en E-learning : à propos du modèle de Garrison et d'Anderson

    OpenAIRE

    Jézégou, Annie

    2010-01-01

    This article is based on a constructively critical analysis of the model of Community of Inquiry developed by Garrison and Anderson (2003) as part of research conducted in the area of e-learning. The authors claim that certain collaborative interactions create “distant presence” fostering the emergence of a community of inquiry which has a positive influence on individual and collective learning. More specifically, the article points out that until now the model's theoretical foundations had ...

  13. Book review: Windows of opportunity: how women seize peace negotiations for political change by Miriam J. Anderson

    OpenAIRE

    Thomson, Jennifer

    2016-01-01

    Why, even when women have not been intimately involved in conflicts, do peace agreements so frequently contain reference to their rights? In Windows of Opportunity: How Women Seize Peace Negotiations for Political Change, Miriam J. Anderson examines how provisions relating to gender and women’s rights have been part of peace negotiations through three case studies of conflict resolution in Burundi, Macedonia and Northern Ireland as well as discussion of 195 peace agreements signed between 197...

  14. Nailing the Coffin Shut on Doubts that Violent Video Games Stimulate Aggression ∼Comment on Anderson et al. (2010).

    OpenAIRE

    Huesmann, L. Rowell

    2010-01-01

    Over the past half-century the mass media, including video games, have become important socializers of children. Observational learning theory has evolved into social-cognitive information processing models that explain that what a child observes in any venue has both short-term and long-term influences on the child's behaviors and cognitions. Anderson's (2010) extensive meta-analysis of the effects of violent video games confirms what these theories predict and what prior research about othe...

  15. Clinical use of the combined Sclarovsky Birnbaum Severity and Anderson Wilkins Acuteness scores from the pre-hospital ECG in ST-segment elevation myocardial infarction

    DEFF Research Database (Denmark)

    Fakhri, Yama; Schoos, Mikkel M; Clemmensen, Peter;

    2014-01-01

    This review summarizes the electrocardiographic changes during an evolving ST segment elevation myocardial infarction and discusses associated electrocardiographic scores and the potential use of these indices in clinical practice, in particular the ECG scores developed by Anderson and Wilkins...

  16. Net coal thickness in the Wyodak-Anderson coal zone in the Powder River Basin, Wyoming and Montana (wacatg.shp)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This shapefile contains a representation of the total net coal thickness in the Wyodak-Anderson coal zone. This theme was created specifically for the National Coal...

  17. Nuclear structure studies using the high resolution spectrometer at The Los Alamos Clinton P. Anderson Meson Physics Facility. Technical progress report

    International Nuclear Information System (INIS)

    A major part of the work is associated with research done using the High Resolution Spectrometer (HRS) at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF); this research focuses on (1) providing data which test nonrelativistic and relativistic microscopic models of the medium energy proton + nucleus interaction, (2) providing data which are to be analyzed to provide new nuclear structure information (both ground state and excited state), and (3) developing and improving the models themselves. Progress is detailed on the following studies: (A) the relativistic impulse approximation; (B) Exp 425/433/479: p + nucleus elastic and inelastic scattering at 500 MeV; (C) Exp 654: measurement of spin-rotation parameter Q for 800 MeV p + nucleus elastic scattering; (D) Exp 470: reactive content of the optical potential at 800 MeV; (E) Exp 642: 800 MeV (vector p,p') inclusive cross sections and analyzing powers; (F) Exp 392: a measurement of the Wolfenstein amplitudes for p - p and p - n scattering at 800 MeV; (G) Exp 626: measurement of triple scattering parameters for 800 MeV inclusive (vector p,p') on 1H, 2H, and 12C; (H) Exp 686U: P + 208Pb elastic and inelastic scattering at 318 MeV; (I) Exp 736: P + 40,48Ca, 54Fe elastic scattering at 318 MeV; (J) Exp 563: P + P elastic scattering at 500 and 800 MeV; (K) Exp 760: P + 1H, 40Ca, and 208Pb elastic and inelastic scattering at 650 MeV; (L) BNL Exp 758: observation of hypernuclei in the 12C(π+,K+)/sub lambda/12C reaction; (M) theoretical study of kaon + nucleus elastic and inelastic scattering; and (N) theoretical determination of effective interactions. Publications are listed

  18. 1/(n-1) expansion for an Anderson impurity with N-fold degeneracy: a new large-N scheme based on a perturbation theory in U

    International Nuclear Information System (INIS)

    Full text: We describe a new large-N approach, which is referred to as 1/(N-1) expansion, to an N-fold degenerate Anderson impurity model with a finite Coulomb interaction U [1,2]. This approach is different from the usual 1/N expansion [3], non-crossing approximation [4], and recent developments [5,6] along the conventional large-N theory which is based on a perturbation expansion with respect to the tunneling matrix element v, between the impurity and conduction electrons, and on a scaling that takes Nv2 as a constant independent of N. In contrast, our formulation starts with the perturbation theory in U, for which a standard Feynman-diagrammatic analysis is applicable. Then, the perturbation series in U is reorganized as an expansion in powers of 1/(N-1), using the scaling that takes u=(N-1)U as an independent variable. The factor N-1 represents the number of interacting orbitals, excluding the one prohibited by the Pauli principle. This approach can be regarded as a fermionic analogue of an expansion scheme that was constructed for the bosonic N-component φ4 model for critical phenomena [7], and can be used to explore low-energy properties of quantum impurities and also lattice-fermion systems such as the Hubbard and periodic Anderson models. Our expansion scheme provides the Hartree-Fock (HF) approximation at zero order, where the limit N → ∞ is taken keeping u finite. Then, to leading order in 1/(N-1) it describes the Hartree-Fock random phase approximation (HF-RPA). The higher-order corrections, starting from order 1/(N-1)2 terms, describe systematically the fluctuations beyond the HF-RPA. We have calculated the renormalized parameters for the local-Fermi-liquid ground state up to terms of order 1/(N-1)2, and found that the results agree very closely with the exact numerical-renormalization-group results already at N=4, where the degeneracy is still not large. This ensures the reliability of our approach for N≥4. Note that the case for N=2 corresponds

  19. Many-body-localization transition: strong multifractality spectrum for matrix elements of local operators

    Science.gov (United States)

    Monthus, Cécile

    2016-07-01

    For short-ranged disordered quantum models in one dimension, the many-body-localization is analyzed via the adaptation to the many-body context (Serbyn et al 2015 Phys. Rev. X 5 041047) of the Thouless point of view on the Anderson transition: the question is whether a local interaction between two long chains is able to reshuffle completely the eigenstates (delocalized phase with a volume-law entanglement) or whether the hybridization between tensor states remains limited (many-body-localized phase with an area-law entanglement). The central object is thus the level of hybridization induced by the matrix elements of local operators, as compared with the difference of diagonal energies. The multifractal analysis of these matrix elements of local operators is used to analyze the corresponding statistics of resonances. Our main conclusion is that the critical point is characterized by the strong-multifractality spectrum f(0≤slant α ≤slant 2)=\\fracα{2} , well known in the context of Anderson localization in spaces of effective infinite dimensionality, where the size of the Hilbert space grows exponentially with the volume. Finally, the possibility of a delocalized non-ergodic phase near criticality is discussed.

  20. Excited nuclei fragmentation

    International Nuclear Information System (INIS)

    Experimental indications leading to the thought of a very excited nucleus fragmentation are resumed. Theoretical approaches are briefly described; they are used to explain the phenomenon in showing off they are based on a minimum information principle. This model is based on time dependent Thomas-Fermi calculation which allows the mean field effect description, and with a site-bound percolation model which allows the fluctuation description

  1. Cytokines and brain excitability

    OpenAIRE

    Galic, Michael A.; Riazi, Kiarash; Pittman, Quentin J.

    2011-01-01

    Cytokines are molecules secreted by peripheral immune cells, microglia, astrocytes and neurons in the central nervous system. Peripheral or central inflammation is characterized by an upregulation of cytokines and their receptors in the brain. Emerging evidence indicates that pro-inflammatory cytokines modulate brain excitability. Findings from both the clinical literature and from in vivo and in vitro laboratory studies suggest that cytokines can increase seizure susceptibility and may be in...

  2. Harmonically excited orbital variations

    International Nuclear Information System (INIS)

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

  3. Anderson-Fabry, the histrionic disease: from genetics to clinical management

    Directory of Open Access Journals (Sweden)

    Franco Cecchi

    2013-02-01

    Full Text Available Anderson-Fabry disease (AFD is an Xlinked lysosomal storage disorder of glycosphingolipid catabolism, due to deficiency or absence of a galactosidase A (α-gal A enzyme. The disease may affect males and females, the latter with an average 10 years delay. Metabolites storage (mostly Gb3 and lyso-Gb3 leads to progressive cellular and multiorgan dysfunction, with either early and late onset variable clinical manifestations that usually reduce quality of life and life expectancy. Heart and kidney failure, stroke and sudden death are the most devastating complications. AFD is always been considered a very rare disease, although new epidemiologic data, based on newborn screening, showed that AFD prevalence is probably underestimated and much higher than previously reported, especially for late-onset atypical phenotypes. Currently, the diagnosis may be easier and simpler by evaluating α-gal A enzyme activity and genetic analysis for GLA gene mutations on dried blood spot. While a marked α-gal A deficiency leads to diagnosis of AFD in hemizygous males, the molecular analysis is mandatory in heterozygous females. However, referral to a center with an expert multidisciplinary team is highly advisable, in order to ensure careful management and treatment of patients, based also on accurate molecular and biochemical data interpretation. While long-term efficacy of enzyme replacement therapy (ERT in advanced stage is still debated, increasing evidence shows greater efficacy of early treatment initiation. Concomitant, organ-specific therapy is also needed. New treatment approaches, such as chemical chaperone therapy, alone or in combination with ERT, are currently under investigation. The present review illustrates the major features of the disease, focusing also on biochemical and genetic aspects.

  4. Gutzwiller wave-function solution for Anderson lattice model: Emerging universal regimes of heavy quasiparticle states

    Science.gov (United States)

    Wysokiński, Marcin M.; Kaczmarczyk, Jan; Spałek, Jozef

    2015-09-01

    The recently proposed diagrammatic expansion (DE) technique for the full Gutzwiller wave function (GWF) is applied to the Anderson lattice model. This approach allows for a systematic evaluation of the expectation values with full Gutzwiller wave function in finite-dimensional systems. It introduces results extending in an essential manner those obtained by means of the standard Gutzwiller approximation (GA), which is variationally exact only in infinite dimensions. Within the DE-GWF approach we discuss the principal paramagnetic properties and their relevance to heavy-fermion systems. We demonstrate the formation of an effective, narrow f band originating from atomic f -electron states and subsequently interpret this behavior as a direct itineracy of f electrons; it represents a combined effect of both the hybridization and the correlations induced by the Coulomb repulsive interaction. Such a feature is absent on the level of GA, which is equivalent to the zeroth order of our expansion. Formation of the hybridization- and electron-concentration-dependent narrow f band rationalizes the common assumption of such dispersion of f levels in the phenomenological modeling of the band structure of CeCoIn5. Moreover, it is shown that the emerging f -electron direct itineracy leads in a natural manner to three physically distinct regimes within a single model that are frequently discussed for 4 f - or 5 f -electron compounds as separate model situations. We identify these regimes as (i) the mixed-valence regime, (ii) Kondo/almost-Kondo insulating regime, and (iii) the Kondo-lattice limit when the f -electron occupancy is very close to the f -state half filling, →1 . The nonstandard features of the emerging correlated quantum liquid state are stressed.

  5. The University of Texas M.D. Anderson Cancer Center Proton Therapy Facility

    Science.gov (United States)

    Smith, Alfred; Newhauser, Wayne; Latinkic, Mitchell; Hay, Amy; McMaken, Bruce; Styles, John; Cox, James

    2003-08-01

    The University of Texas M.D. Anderson Cancer Center (MDACC), in partnership with Sanders Morris Harris Inc., a Texas-based investment banking firm, and The Styles Company, a developer and manager of hospitals and healthcare facilities, is building a proton therapy facility near the MDACC main complex at the Texas Medical Center in Houston, Texas USA. The MDACC Proton Therapy Center will be a freestanding, investor-owned radiation oncology center offering state-of-the-art proton beam therapy. The facility will have four treatment rooms: three rooms will have rotating, isocentric gantries and the fourth treatment room will have capabilities for both large and small field (e.g. ocular melanoma) treatments using horizontal beam lines. There will be an additional horizontal beam room dedicated to physics research and development, radiation biology research, and outside users who wish to conduct experiments using proton beams. The first two gantries will each be initially equipped with a passive scattering nozzle while the third gantry will have a magnetically swept pencil beam scanning nozzle. The latter will include enhancements to the treatment control system that will allow for the delivery of proton intensity modulation treatments. The proton accelerator will be a 250 MeV zero-gradient synchrotron with a slow extraction system. The facility is expected to open for patient treatments in the autumn of 2005. It is anticipated that 675 patients will be treated during the first full year of operation, while full capacity, reached in the fifth year of operation, will be approximately 3,400 patients per year. Treatments will be given up to 2-shifts per day and 6 days per week.

  6. Effect of electron-electron interaction near the metal-insulator transition in doped semiconductors studied within the local density approximation

    OpenAIRE

    Harashima, Yosuke; Slevin, Keith

    2012-01-01

    We report a numerical analysis of Anderson localization in a model of a doped semiconductor. The model incorporates the disorder arising from the random spatial distribution of the donor impurities and takes account of the electron-electron interactions between the carriers using density functional theory in the local density approximation. Preliminary results suggest that the model exhibits a metal-insulator transition.

  7. Localization on the landscape and eternal inflation

    International Nuclear Information System (INIS)

    We investigate the validity of the assertion that eternal inflation populates the landscape of string theory. We verify that bubble solutions do not satisfy the Klein–Gordon equation for the landscape potential. Solutions to the landscape potential within the formalism of quantum cosmology are Anderson localized wavefunctions. These are inconsistent with inflating bubble solutions. The physical reasons behind the failure of a relation between eternal inflation and the landscape are rooted in quantum phenomena such as interference between wavefunction concentrated around the various vacua in the landscape. (paper)

  8. Localization on the landscape and eternal inflation

    Science.gov (United States)

    Mersini-Houghton, Laura; Perry, Malcolm J.

    2014-11-01

    We investigate the validity of the assertion that eternal inflation populates the landscape of string theory. We verify that bubble solutions do not satisfy the Klein-Gordon equation for the landscape potential. Solutions to the landscape potential within the formalism of quantum cosmology are Anderson localized wavefunctions. These are inconsistent with inflating bubble solutions. The physical reasons behind the failure of a relation between eternal inflation and the landscape are rooted in quantum phenomena such as interference between wavefunction concentrated around the various vacua in the landscape.

  9. Localization on the Landscape and Eternal Inflation

    CERN Document Server

    Mersini-Houghton, Laura

    2014-01-01

    We investigate the validity of the assertion that eternal inflation populates the landscape of string theory. We verify that bubble solutions do not satisfy the Klein Gordon equation for the landscape potential. Solutions to the landscape potential within the formalism of quantum cosmology are Anderson localized wavefunctions. Those are inconsistent with inflating bubble solutions. The physical reasons behind the failure of a relation between eternal inflation and the landscape are rooted in quantum phenomena such as interference between wavefunction concentrated around the various vacua in the landscape.

  10. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme

    Energy Technology Data Exchange (ETDEWEB)

    Theophilou, Iris, E-mail: i.theophilou@fz-juelich.de [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany); Tassi, M.; Thanos, S. [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)

    2014-04-28

    Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

  11. Broadband near-field enhancement in the macro-periodic and micro-random structure with a hybridized excitation of propagating Bloch-plasmonic and localized surface-plasmonic modes.

    Science.gov (United States)

    Lu, Haifei; Ren, Xingang; Sha, Wei E I; Ho, Ho-Pui; Choy, Wallace C H

    2015-10-28

    We demonstrate that the silver nanoplate-based macroscopically periodic (macro-periodic) and microscopically random (micro-random) structure has a broadband near-field enhancement as compared to conventional silver gratings. The specific field enhancement in a wide spectral range (from UV to near-infrared) originates from the abundance of localized surface-plasmonic (LSP) modes in the microscopically random distributed silver nanoplates and propagating Bloch-plasmonic (PBP) modes from the macroscopically periodic pattern. The characterization of polarization dependent spectral absorption, surface-enhanced Raman spectroscopy (SERS), as well as theoretical simulation was conducted to comprehensively understand the features of the broadband spectrum and highly concentrated near-field. The reported macro-periodic and micro-random structure may offer a new route for the design of plasmonic systems for photonic and optoelectronic applications.

  12. Non-equilibrium STLS approach to transport properties of single impurity Anderson model

    International Nuclear Information System (INIS)

    In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U2 IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: •We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. •We determine the transport properties of SIAM using the non-equilibrium STLS method. •We compare our results with order-U2 IPT and NRG. •We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. •We show that the method keeps the universal scaling behavior and correct

  13. Non-equilibrium STLS approach to transport properties of single impurity Anderson model

    Energy Technology Data Exchange (ETDEWEB)

    Rezai, Raheleh, E-mail: R_Rezai@sbu.ac.ir; Ebrahimi, Farshad, E-mail: Ebrahimi@sbu.ac.ir

    2014-04-15

    In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U{sup 2} IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: •We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. •We determine the transport properties of SIAM using the non-equilibrium STLS method. •We compare our results with order-U2 IPT and NRG. •We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. •We show that the method keeps the universal scaling behavior and correct

  14. Estimate of the Critical Exponent of the Anderson Transition in the Three and Four-Dimensional Unitary Universality Classes

    Science.gov (United States)

    Slevin, Keith; Ohtsuki, Tomi

    2016-10-01

    Disordered non-interacting systems are classified into ten symmetry classes, with the unitary class being the most fundamental. The three and four-dimensional unitary universality classes are attracting renewed interest because of their relation to three-dimensional Weyl semi-metals and four-dimensional topological insulators. Determining the critical exponent of the correlation/localisation length for the Anderson transition in these classes is important both theoretically and experimentally. Using the transfer matrix technique, we report numerical estimations of the critical exponent in a U(1) model in three and four dimensions.

  15. Bi-stability in single impurity Anderson model with strong electron-phonon interaction(polaron regime)

    Science.gov (United States)

    Eskandari-asl, Amir

    2016-09-01

    We consider a single impurity Anderson model (SIAM) in which the quantum dot(QD) is strongly coupled to a phonon bath in polaron regime. This coupling results in an effective e-e attraction. By computing the self energies using a current conserving approximation which is up to second order in this effective attraction, we show that if the interaction is strong enough, in non particle-hole (PH) symmetric case, the system would be bi-stable and we have hysteresis loop in the I-V characteristic. Moreover, the system shows negative differential conductance in some bias voltage intervals.

  16. Electromagnetic toroidal excitations in matter and free space.

    Science.gov (United States)

    Papasimakis, N; Fedotov, V A; Savinov, V; Raybould, T A; Zheludev, N I

    2016-03-01

    The toroidal dipole is a localized electromagnetic excitation, distinct from the magnetic and electric dipoles. While the electric dipole can be understood as a pair of opposite charges and the magnetic dipole as a current loop, the toroidal dipole corresponds to currents flowing on the surface of a torus. Toroidal dipoles provide physically significant contributions to the basic characteristics of matter including absorption, dispersion and optical activity. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses propagating at the speed of light and interacting with matter. We review recent experimental observations of resonant toroidal dipole excitations in metamaterials and the discovery of anapoles, non-radiating charge-current configurations involving toroidal dipoles. While certain fundamental and practical aspects of toroidal electrodynamics remain open for the moment, we envision that exploitation of toroidal excitations can have important implications for the fields of photonics, sensing, energy and information. PMID:26906961

  17. Excitation-energy sorting in superfluid fission dynamics

    Directory of Open Access Journals (Sweden)

    Schmidt K.-H.

    2010-10-01

    Full Text Available It is now well established that at moderate excitation energies the nucleus temperature does not vary with increasing excitation energy. We show that, as a consequence, two nuclei with different temperatures brought into contact show a rather surprising energy-sorting mechanism where the hotter nucleus transfers all its excitation energy to the colder one. The scission configuration of the fission process offers a unique possibility to observe this phenomenon. The energy-sorting mechanism is clearly reflected by the mean number of prompt neutrons as a function of the fragment mass and by the dependence of the local even-odd effect with mass asymmetry.

  18. Neural Excitability and Singular Bifurcations.

    Science.gov (United States)

    De Maesschalck, Peter; Wechselberger, Martin

    2015-12-01

    We discuss the notion of excitability in 2D slow/fast neural models from a geometric singular perturbation theory point of view. We focus on the inherent singular nature of slow/fast neural models and define excitability via singular bifurcations. In particular, we show that type I excitability is associated with a novel singular Bogdanov-Takens/SNIC bifurcation while type II excitability is associated with a singular Andronov-Hopf bifurcation. In both cases, canards play an important role in the understanding of the unfolding of these singular bifurcation structures. We also explain the transition between the two excitability types and highlight all bifurcations involved, thus providing a complete analysis of excitability based on geometric singular perturbation theory.

  19. Excited States in Solution through Polarizable Embedding

    DEFF Research Database (Denmark)

    Olsen, Jógvan Magnus; Aidas, Kestutis; Kongsted, Jacob

    2010-01-01

    mechanical calculation. The polarizable embedding potential is described by an atomistic representation including terms up to localized octupoles and anisotropic polarizabilities. It is generally applicable to any quantum chemical description but is here implemented for the case of Kohn−Sham density......We present theory and implementation of an advanced quantum mechanics/molecular mechanics (QM/MM) approach using a fully self-consistent polarizable embedding (PE) scheme. It is a polarizable layered model designed for effective yet accurate inclusion of an anisotropic medium in a quantum...... functional theory which we denote the PE-DFT method. It has been implemented in combination with time-dependent quantum mechanical linear and nonlinear response techniques, thus allowing for assessment of electronic excitation processes and dynamic ground- and excited-state molecular properties using...

  20. Nailing the coffin shut on doubts that violent video games stimulate aggression: comment on Anderson et al. (2010).

    Science.gov (United States)

    Huesmann, L Rowell

    2010-03-01

    Over the past half century the mass media, including video games, have become important socializers of children. Observational learning theory has evolved into social-cognitive information processing models that explain that what a child observes in any venue has both short-term and long-term influences on the child's behaviors and cognitions. C. A. Anderson et al.'s (2010) extensive meta-analysis of the effects of violent video games confirms what these theories predict and what prior research about other violent mass media has found: that violent video games stimulate aggression in the players in the short run and increase the risk for aggressive behaviors by the players later in life. The effects occur for males and females and for children growing up in Eastern or Western cultures. The effects are strongest for the best studies. Contrary to some critics' assertions, the meta-analysis of C. A. Anderson et al. is methodologically sound and comprehensive. Yet the results of meta-analyses are unlikely to change the critics' views or the public's perception that the issue is undecided because some studies have yielded null effects, because many people are concerned that the implications of the research threaten freedom of expression, and because many people have their identities or self-interests closely tied to violent video games.

  1. Development of the M. D. Anderson Cancer Center Gynecologic Applicators for the Treatment of Cervical Cancer: Historical Analysis

    International Nuclear Information System (INIS)

    Purpose: To provide historical background on the development and initial studies of the gynecological (gyn) applicators developed by Dr. Gilbert H. Fletcher, a radiation oncologist and chairperson from 1948 to 1981 of the department at the M.D. Anderson Hospital (MDAH) for Cancer Research in Houston, TX, and to acknowledge the previously unrecognized contribution that Dr. Leonard G. Grimmett, a radiation physicist and chairperson from 1949 to 1951 of the physics department at MDAH, made to the development of the gynecological applicators. Methods and Materials: We reviewed archival materials from the Historical Resource Center and from the Department of Radiation Physics at University of Texas M. D. Anderson Cancer Center, as well as contemporary published papers, to trace the history of the applicators. Conclusions: Dr. Fletcher’s work was influenced by the work on gynecologic applicators in the 1940s in Europe, especially work done at the Royal Cancer Hospital in London. Those efforts influenced not only Dr. Fletcher’s approach to the design of the applicators but also the methods used to perform in vivo measurements and determine the dose distribution. Much of the initial development of the dosimetry techniques and measurements at MDAH were carried out by Dr. Grimmett.

  2. Ferromagnetism and metal-half-metal-insulator transitions in a frustrated periodic Anderson-like organic polymer

    International Nuclear Information System (INIS)

    The ferromagnetism and quantum phase transitions of a periodic Anderson-like organic polymer, in which the next-nearest-neighboring hopping results in frustration, are investigated by means of many-body Green's function theory. It is found that the ground state lies in half-metallic and paramagnetic metallic states for weak and relatively strong frustrations, respectively. At finite temperatures, a ferrimagnetic order and two different ferromagnetic phases are unveiled. In a magnetic field, in addition to 1/3 magnetization plateau, it presents three cusps and three critical fields indicating metal-half-metal and half-metal-insulator transitions, respectively, which are closely related to the energy bands controlled by the field. - Highlights: • The ferromagnetism and quantum phase transitions of a frustrated periodic Anderson-like organic polymer are investigated by Green's function theory. • At finite temperatures, a ferrimagnetic order and two different ferromagnetic phases are unveiled. • In a magnetic field, we reveal the metal-half-metal and half-metal-insulator transitions

  3. 腹腔镜下 Cohen 及改良 Glenn-Anderson 输尿管膀胱再植术的疗效比较%A Comparison Between Laparoscopic Modified Glenn-Anderson and Cohen Ureteric Reimplantation

    Institute of Scientific and Technical Information of China (English)

    习林云; 何大维; 刘星; 华燚; 刘俊宏; 刘丰; 林涛; 魏光辉

    2015-01-01

    目的:探讨腹腔镜Cohen及改良Glenn-Anderson输尿管膀胱再植术治疗儿童输尿管膀胱连接部畸形的临床效果。方法回顾性分析我院2005年12月~2012年2月输尿管膀胱连接处疾病96例资料。前30例行Cohen术,后66例行改良Glenn-Anderson术。术后随访1年,比较2组手术时间、出血量、术后住院时间、并发症及术后输尿管积水恢复情况。结果2组各有1例中转开放手术,其余腹腔镜完成手术者2组手术时间[(129±30)min vs.(139±42)min,t=-1.177,P=0.242],术中出血量[(17.9±10.4)ml vs.(18.6±10.5)ml,t=-0.266,P=0.791],术后住院时间[(9.5±1.4)d vs.(9.2±1.4)d,t=0.941,P=0.349]差异均无显著性。 Cohen组1例术中皮下气肿,1例术后反复尿路感染,改良Glenn-Anderson组1例膀胱穿刺孔出血,2组并发症发生率差异无显著性(χ2=0.533,P=0.465)。术后1年Cohen组随访30例33根输尿管,改良Glenn-Anderson组随访53例57根输尿管,均无积水加重病例,改良Glenn-Anderson组输尿管恢复较Cohen组更好(恢复正常、缩小、无缓解分别为54、3、0侧和21、9、3侧,Z=-3.842,P=0.000),肾积水恢复情况2组差异无显著性(Z=-0.121,P=0.904)。结论腹腔镜下Cohen及改良Glenn-Anderson术式都具有安全有效、容易学习、具有微创优势的特点,后者输尿管直径缩小更明显。%Objective To describe the clinical efficacy of laparoscopic modified Glenn-Anderson and Cohen ureteric reimplantation for congenital malformation of vesicoureteral junction in children. Methods A retrospective review of 96 patients who underwent ureteric reimplantation from December 2005 to February 2012 was conducted.The first 30 cases were given Cohen procedure, while the remaining 66 cases underwent modified Glenn-Anderson procedure. The follow-up period was 1

  4. High energy magnetic excitations

    International Nuclear Information System (INIS)

    The report emphasizes that the current development in condensed matter physics opens a research field fit to inelastic neutron scattering experiments in the eV range which is easilly accessed by spallation neutron sources. Several important subjects adopted at thermal reactors are shown. It is desired to extend the implementation of the spectroscopic experiments for investigation of higher energy magnetic excitations. For La2CuO4, which is the mother crystal of the first high Tc materials found by Bednortz and Muller, it seems to be believed that the magnetism is well characterized by the two-dimensional Heisenberg antiferromagnetic Hamiltonian, and it is widely accepted that the magnetism is a most probable progenitor of high Tc superconductors. The unusual properties of spin correlations in this crystal have been studied extensively by standard neutron scattering techniques with steady neutrons at BNL. FeSi is not ordered magnetically but shows a very unique feature of temperature induced magnetism, which also has been studied extensively by using the thermal neutron scattering technique at BNL. In these experiments, polarized neutrons are indispensable to extract the clean magnetic components out of other components of non-magnetic scattering. (N.K.)

  5. Subsurface excitations in a metal

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Sosolik, C. E.;

    2009-01-01

    by the free-electron model of a metal still excite hot carriers. Excellent agreement between these results and a nonadiabatic model that accounts for the time-varying ion-surface interaction indicates that the measured excitations are due to semilocalized electrons near the metal surface....

  6. Multiple phonon excitation in nuclei

    International Nuclear Information System (INIS)

    The studies of multiphonon excitations in nuclei are reviewed both from the theoretical and experimental points of view. The presence of giant resonances in nuclei is described in the framework of macroscopic and microscopic models and the relative merits of different probes to excite such states are illustrated. The existence of giant resonances built on excited states is stressed. An exhaustive description of the theoretical estimates of the properties of the multiphonon states is presented. The theory predicts that such multiple collective excitations should closely follow a harmonic pattern. Recent experimental results on the double giant dipole resonance using the (π+π-) double charge exchange reaction are shown. The status of the search for isoscalar multiphonon excitations by means of the strong nuclear potential produced by heavy ions is presented. Conclusions are drawn and new prospects are discussed. (authors) 293 refs., 67 figs., 8 tabs

  7. [Biophysics of nerve excitation].

    Science.gov (United States)

    Kol'e, O R; Maksimov, G V

    2010-01-01

    The studies testifying to the presence of the interrelation between the physiological functions of the organism and physical and chemical processes in nerves are discussed. Changes in some physical and chemical parameters observed both upon elicited rhythmic exaltation of nerves and during the spontaneous rhythmic activity of neurons are analyzed. Upon rhythmic exaltation, a complex of physical and chemical processes is triggered, and reversible structural and metabolic rearrangements at the subcellular and molecular levels occur that do not take place during the generation of a single action potential. Thus, only in conditions of rhythmic exaltation of a nerve, it is possible to reveal those processes that provide exaltation of nerves in the organism. The future possibilities of the investigations combining the biophysical and physiological approaches are substantiated. Characteristic changes in physicochemical parameters are observed in nerves during the generation of a series of action potentials of different frequency and duration ("frequency dependence") under normal physiological conditions, as well as in extreme situations and in nerve pathology. The structural and metabolic rearrangements are directly related to the mode of rhythmic exaltation and proceed both in the course of rhythmic exaltation and after its termination. Participation and the basic components of the nervous fulcrum (an axon, Shwan cell, myelin, subcellular organelles) in the realization of rhythmic exaltation is shown. In the coordination of all processes involved in rhythmic exaltation, the main role is played by the systems of redistribution and transport of intercellular and endocellular calcium. The idea is put forward that myelin of nerve fibers is not only an isolator, but also an "intercellular depot" of calcium and participates in the redistribution of different ions. Thus, the rhythmic excitation is of great importance in the realization of some physiological functions, the

  8. Direct observation of localized dipolar excitations on rough nanostructured surfaces

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Markel, V.A.; Coello, V.;

    1998-01-01

    Using a photon scanning tunneling microscope (operating alternatively at the wavelengths of 594 and 633 nm) with shear-force feedback we image the topography of silver colloid fractals simultaneously with a near-field intensity distribution. We observe that near-field optical images exhibit spati...

  9. Damage Localization and Quantification of Earthquake Excited RC-Frames

    DEFF Research Database (Denmark)

    Skjærbæk, P. S.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning;

    1998-01-01

    of the ground motion events the storey accelerations were measured by accelerometers. After application of the last earthquake sequence to the structure the frames were cut into pieces and each of the beams and columns was statically tested and damage assessment was performed using the obtained stiffnesses...

  10. Spin-polarized spin excitation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J, E-mail: lothseb@us.ibm.com, E-mail: heinrich@almaden.ibm.com [IBM Research Division, Almaden Research Center, San Jose, CA 95120 (United States)

    2010-12-15

    We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu{sub 2}N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

  11. Universal role of quantum uncertainty in Anderson metal-insulator transition

    Science.gov (United States)

    Cheng, W. W.; Zhang, Z. J.; Gong, L. Y.; Zhao, S. M.

    2016-07-01

    We explore quantum uncertainty, based on Wigner-Yanase skew information, in various one-dimensional single-electron wave functions. For the power-law function and eigenfunctions in the Aubry-André model, the electronic localization properties are well-defined. For them, we find that quantum uncertainty is relatively small and large for delocalized and localized states, respectively. And around the transition points, the first-order derivative of the quantum uncertainty exhibits singular behavior. All these characters can be used as signatures of the transition from a delocalized phase to a localized one. With this criterion, we also study the quantum uncertainty in one-dimensional disorder system with long-range correlated potential. The results show that the first-order derivative of spectrum-averaged quantum uncertainty is minimal at a certain correlation exponent αm for a finite system, and has perfect finite-size scaling behaviors around αm. By extrapolating αm, the threshold value αc ≃ 1.56 ± 0.02 is obtained for the infinite system. Thus we give another perspective and propose a consistent interpretation for the discrepancies about localization property in the long-range correlated potential model. These results suggest that the quantum uncertainty can provide us with a new physical intuition to the localization transition in these models.

  12. Adiabatic quenches and characterization of amplitude excitations in a continuous quantum phase transition.

    Science.gov (United States)

    Hoang, Thai M; Bharath, Hebbe M; Boguslawski, Matthew J; Anquez, Martin; Robbins, Bryce A; Chapman, Michael S

    2016-08-23

    Spontaneous symmetry breaking occurs in a physical system whenever the ground state does not share the symmetry of the underlying theory, e.g., the Hamiltonian. This mechanism gives rise to massless Nambu-Goldstone modes and massive Anderson-Higgs modes. These modes provide a fundamental understanding of matter in the Universe and appear as collective phase or amplitude excitations of an order parameter in a many-body system. The amplitude excitation plays a crucial role in determining the critical exponents governing universal nonequilibrium dynamics in the Kibble-Zurek mechanism (KZM). Here, we characterize the amplitude excitations in a spin-1 condensate and measure the energy gap for different phases of the quantum phase transition. At the quantum critical point of the transition, finite-size effects lead to a nonzero gap. Our measurements are consistent with this prediction, and furthermore, we demonstrate an adiabatic quench through the phase transition, which is forbidden at the mean field level. This work paves the way toward generating entanglement through an adiabatic phase transition. PMID:27503886

  13. Adiabatic quenches and characterization of amplitude excitations in a continuous quantum phase transition

    Science.gov (United States)

    Hoang, Thai M.; Bharath, Hebbe M.; Boguslawski, Matthew J.; Anquez, Martin; Robbins, Bryce A.; Chapman, Michael S.

    2016-08-01

    Spontaneous symmetry breaking occurs in a physical system whenever the ground state does not share the symmetry of the underlying theory, e.g., the Hamiltonian. This mechanism gives rise to massless Nambu-Goldstone modes and massive Anderson-Higgs modes. These modes provide a fundamental understanding of matter in the Universe and appear as collective phase or amplitude excitations of an order parameter in a many-body system. The amplitude excitation plays a crucial role in determining the critical exponents governing universal nonequilibrium dynamics in the Kibble-Zurek mechanism (KZM). Here, we characterize the amplitude excitations in a spin-1 condensate and measure the energy gap for different phases of the quantum phase transition. At the quantum critical point of the transition, finite-size effects lead to a nonzero gap. Our measurements are consistent with this prediction, and furthermore, we demonstrate an adiabatic quench through the phase transition, which is forbidden at the mean field level. This work paves the way toward generating entanglement through an adiabatic phase transition.

  14. Architectural/historical assessment of the Oak Ridge National Laboratory, Oak Ridge Reservation, Anderson and Roane Counties, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    Carver, M.; Slater, M.

    The Department of Energy (DOE) is required by the National Historic Preservation Act (NHPA) of 1966, as amended, to identify any properties under its jurisdiction that are included in or eligible for inclusion in the National Register of Historic Places (National Register). In March 1993 Duvall & Associates, Inc., was engaged to survey the Oak Ridge National Laboratory (ORNL), a DOE facility located on the Oak Ridge Reservation (ORR) in Anderson and Roane Counties, Tennessee, and to prepare a determination of National Register eligibility for all ORNL properties. The purpose of this report is to summarize the results of research into the historical context of ORNL and at to identify historic properties at ORNL that are included in present or eligible for inclusion in the National Register. The identification of archaeological properties at ORNL that are included and eligible for inclusion in the National Register Clinton is addressed in a separate report.

  15. Crystal structure of an organic-inorganic hybrid compound based on morpholinium cations and a β-type Anderson polyanion.

    Science.gov (United States)

    Lukianova, Tamara J; Kinzhybalo, Vasyl; Pietraszko, Adam

    2015-11-01

    A new organic-inorganic hybrid compound, penta-morpholinium hexa-hydrogen hexa-molybdoferrate(III) sulfate 3.5-hydrate, (C4H10NO)5[Fe(III)(OH)6Mo6O18](SO4)·3.5H2O, was obtained from an aqueous solution. The polyoxidomolybdate (POM) anion is of the Anderson β-type with a central Fe(III) ion. Three of five crystallographically independent morpholinium cations are disordered over two sets of sites. An intricate network of inter-molecular N-H⋯O and O-H⋯O inter-actions between cations, POMs, sulfate anions and non-coordinating water mol-ecules creates a three-dimensional network structure.

  16. Dynamics of Barrier Crossings for the Generalized Anderson-Holstein Model: Beyond Electronic Friction and Conventional Surface Hopping.

    Science.gov (United States)

    Ouyang, Wenjun; Dou, Wenjie; Jain, Amber; Subotnik, Joseph E

    2016-09-13

    We investigate barrier crossings within the context of the Anderson-Holstein model, as relevant to coupled nuclear-electronic dynamics near a metal surface. Beyond standard electronic friction or conventional surface-hopping dynamics, we show that a broadened classical master equation can recover both the correct nonadiabatic and the correct adiabatic dynamics for a general escape problem (even with possibly multiple escape channels). In the case of a large barrier with only a single escape channel, we also find a surprising conclusion: electronic friction can recover Marcus's nonadiabatic theory of electron transfer in the limit of small molecule-metal couplings. The latter conclusion establishes a hidden connection between Marcus's nonadiabatic theory and Kramer's adiabatic theory of rate constants. PMID:27564005

  17. Nuclear structure studies using the high resolution spectrometer at the Los Alamos Clinton P. Anderson Meson Physics Facility. Progress report

    International Nuclear Information System (INIS)

    This document constitutes a progress report (1984 to 1985) and renewal proposal for the ongoing medium energy nuclear physics research program. The research efforts were carried out with the High Resolution Spectrometer (HRS) at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF) and at Brookhaven National Laboratory. The LAMPF research includes (1) p+ nucleus scattering data for a test of nonrelativistic and relativistic models of medium energy interaction; (2) data for nuclear structure information; (3) proton + nucleon data for the study of the fundamental nucleon-nucleon interaction; and (4) development of the above models. The Brookhaven work is a study of the formation and use of hypernuclei as a tool for nuclear studies. Individual reports are indexed separately

  18. Perry Anderson, Spectrum. From Right to Left in the World of Ideas, Londres-New York, Verso, 2005.

    Directory of Open Access Journals (Sweden)

    Gabriele Pedullà

    2010-09-01

    Full Text Available Perry Anderson se charge d’expliciter lui-même le sens de son dernier recueil d’essais, Spectrum : « On peut le considérer comme une sorte de travelling qui, se déplaçant de droite à gauche, éclaircit un paysage intellectuel particulier. […] Voilà le spectre auquel fait allusion le titre. » Il y a toutefois de bonnes raisons de proposer une autre lecture. Étant donné que le grand thème unificateur de ces essais, parus à l’origine entre 1992 et 2005 en différents lieux, est le monde des idées ...

  19. Anderson AFB, Agana, Guam. revised uniform summary of surface weather observations (RUSSWO). parts a-f. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-31

    This report is a six-part statistical summary of surface weather observations for Anderson AFB, Agana, Guam. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (C) Surface winds; (D) Ceiling Versus Visibility; Sky Cover; (E) Psychrometric Summaries (daily maximum and minimum temperatures, extreme maximum and minimum temperatures, psychrometric summary of wet-bulb temperature depression versus dry-bulb temperature, means and standard deviations of dry-bulb, wet-bulb and dew-point temperatures and relative humidity); and (F) Pressure Summary (means, standard, deviations, and observation counts of station pressure and sea-level pressure). Data in this report are presented in tabular form, in most cases in percentage frequency of occurrence or cumulative percentage frequency of occurrence tables.

  20. Uniform excitations in magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Steen Mørup

    2010-11-01

    Full Text Available We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering.

  1. Uniform excitations in magnetic nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

    2010-01-01

    We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization...... and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering....

  2. Clinical use of the combined Sclarovsky Birnbaum Severity and Anderson Wilkins Acuteness scores from the pre-hospital ECG in ST-segment elevation myocardial infarction.

    Science.gov (United States)

    Fakhri, Yama; Schoos, Mikkel M; Clemmensen, Peter; Sejersten, Maria

    2014-01-01

    This review summarizes the electrocardiographic changes during an evolving ST segment elevation myocardial infarction and discusses associated electrocardiographic scores and the potential use of these indices in clinical practice, in particular the ECG scores developed by Anderson and Wilkins estimating the acuteness of myocardial ischemia and Sclarovsky-Birnbaum's grades of ischemia evaluating the severity of ongoing ischemia. PMID:24792905

  3. The attorney/client privilege: a fond memory of things past an analysis of the privilege following United States v. Anderson.

    Science.gov (United States)

    Mustokoff, M M; Swichar, J L; Herzfeld, C R

    2000-01-01

    Mr. Mustokoff, Mr. Swichar, and Ms. Herzfeld address the rudiments of the attorney/client privilege, its crime-fraud exception, corporate compliance programs, the United States government's quest for voluntary disclosure, and how those principles have been affected by United States v. Anderson.

  4. Anderson Metal-Insulator Transitions With Classical Magnetic Impurities: Supplemental material

    OpenAIRE

    Jung, Daniel; Slevin, Keith; Kettemann, Stefan

    2015-01-01

    In the supplemental materials we justify our choice of the number of Chebychev moments used within the kernel polynomial method, show some preliminary results for the large coupling behavior, discuss possible correlation effects in the local density of states, estimate the spin relaxation length and introduce the goodness of fit probability that is used to assess the quality of the fits.

  5. Eigenfunction statistics for Anderson model with Hölder continuous single site potential

    Indian Academy of Sciences (India)

    DHRITI RANJAN DOLAI; ANISH MALLICK

    2016-10-01

    We consider random Schrödinger operators on ${\\mathcal l}^{2} ({\\mathbb Z}^d)$ with $\\alpha$-Hölder continuous $(0 \\lt \\alpha \\leq 1)$ single site distribution. In localized regime, we study the distribution of eigenfunctions in space and energy simultaneously. In a certain scaling limit, we prove limit points are Poisson.

  6. Imaging Cracks by Laser Excited Thermography

    Science.gov (United States)

    Schlichting, J.; Kervalishvili, G. N.; Maierhofer, Ch.; Kreutzbruck, M.

    2010-02-01

    During the last years active thermography is increasingly used in a number of NDT problems in production and maintenance. In this work we focus on the detection of vertical cracks starting at the surface, which is an important indication of structural failure. By using local thermal excitation it is possible to image anisotropies in the lateral diffusivity by recording the temporal temperature data with an infrared camera. The regional transient behaviour of temperature distribution then can provide quantitative information of the crack parameter. In doing so, we present an advanced technique for the determination of the crack depth. The experimental set-up is based on an Nd:YAG laser. The beam is focused on the test sample by using an optical scanner to create the required lateral heat flow. The time resolved temperature distribution is recorded with an infrared camera (InSb FPA, 3 to 5 μm) providing a frame rate of up to 500 Hz. In addition we report on numerical simulation to investigate the concept of local heat excitation for a quantitative estimation of crack parameters. The modeling also includes the influence of surface to surface radiation inside the crack. We obtained a good consistency between experimental and theoretical data.

  7. Resonance Radiation and Excited Atoms

    Science.gov (United States)

    Mitchell, Allan C. G.; Zemansky, Mark W.

    2009-06-01

    1. Introduction; 2. Physical and chemical effects connected with resonance radiation; 3. Absorption lines and measurements of the lifetime of the resonance state; 4. Collision processes involving excited atoms; 5. The polarization of resonance radiation; Appendix; Index.

  8. Coulomb excitations of monolayer germanene

    CERN Document Server

    Shih, Po-Hsin; Wu, Jhao-Ying; Shyu, Feng-Lin; Lin, Ming-Fa

    2016-01-01

    The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbital coupling and the buckled structure. The collective and single- particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e-h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e-h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.

  9. Autowaves in moving excitable media

    Directory of Open Access Journals (Sweden)

    V.A.Davydov

    2004-01-01

    Full Text Available Within the framework of kinematic theory of autowaves we suggest a method for analytic description of stationary autowave structures appearing at the boundary between the moving and fixed excitable media. The front breakdown phenomenon is predicted for such structures. Autowave refraction and, particulary, one-side "total reflection" at the boundary is considered. The obtained analytical results are confirmed by computer simulations. Prospects of the proposed method for further studies of autowave dynamics in the moving excitable media are discussed.

  10. Synaptic control of motoneuronal excitability

    DEFF Research Database (Denmark)

    Rekling, J C; Funk, G D; Bayliss, D A;

    2000-01-01

    important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization......, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions...

  11. Exciting Polaritons with Quantum Light

    Science.gov (United States)

    López Carreño, J. C.; Sánchez Muñoz, C.; Sanvitto, D.; del Valle, E.; Laussy, F. P.

    2015-11-01

    We discuss the excitation of polaritons—strongly coupled states of light and matter—by quantum light, instead of the usual laser or thermal excitation. As one illustration of the new horizons thus opened, we introduce "Mollow spectroscopy"—a theoretical concept for a spectroscopic technique that consists of scanning the output of resonance fluorescence onto an optical target—from which weak nonlinearities can be read with high precision even in strongly dissipative environments.

  12. Laser-induced nuclear excitation

    International Nuclear Information System (INIS)

    An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 103 Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

  13. Radial excitations of superconducting strings and their observational consequences

    CERN Document Server

    Hartmann, Betti; Peter, Patrick

    2016-01-01

    We report on the existence of a new type of cosmic string solutions in the Witten model with $U(1)_{\\rm global} \\times \\ U(1)_{\\rm local}$ symmetry. These solutions are superconducting with radially excited condensates. We show that some of these new solutions satisfy Carter's classical stability criterion and discuss some of their possible consequences.

  14. Plasmon-polaritons on a surface with fluctuating impedance: Scattering, localization, stability

    Science.gov (United States)

    Tarasov, Yu. V.; Usatenko, O. V.; Iakushev, D. A.

    2016-08-01

    Scattering of TM-polarized surface plasmon-polariton waves (PPW) by a finite segment of the metal-vacuum interface with randomly fluctuating surface impedance is examined. Solution of the integral equation relating the scattered field with the field of the incident PPW, valid for arbitrary scattering intensity and arbitrary dissipative characteristics of the conductive medium, is analyzed. As a measure of the PPW scattering, the Hilbert norm of the integral scattering operator is used. The strength of the scattering is shown to be determined not only by the parameters of the fluctuating impedance (dispersion, correlation radius and the length of the inhomogeneity region) but also by the conductivity of the metal. If the scattering operator norm is small, the PPW is mainly scattered into the vacuum, thus losing its energy through the excitation of quasi-isotropic bulk Norton waves above the conducting surface. The scattered field intensity is expressed in terms of the random impedance pair-correlation function. Its dependence on the incident and scattered wavenumbers shows that in the case of random-impedance-induced scattering of PPW it is possible to observe the effect analogous to Wood's anomalies on gratings. Under strong scattering, when the norm of the scattering operator becomes large compared to unity, the radiation into free space is strongly suppressed, and, in the limit, the incoming PPW is almost perfectly back-reflected from the inhomogeneous part of the interface. Therefore, within the model of a dissipation-free conducting medium, the surface polariton is unstable against arbitrary small fluctuations of the medium polarizability. Transition from scattering to back-reflection under strong fluctuations of the impedance is interpreted in terms of the Anderson localization.

  15. Diseño Mc. Lean‐Anderson aplicado para obtener recubrimientos de electrodos aleados con carbono, cromo y titanio//Mc. Lean‐Anderson design applied for recovered electrodes obtaining with carbon, chrome and titanium alloys

    Directory of Open Access Journals (Sweden)

    Carlos René Gómez-Pérez

    2013-05-01

    Full Text Available En el trabajo se estudia el comportamiento de electrodos recubiertos destinados al relleno superficial con el proceso de soldadura manual (SMAW, Shielded Metal Arc Welding. Para el diseño experimental se aplican un procedimiento de cálculo para el revestimiento y un plan de mezclas del tipo Mc. Lean-Anderson. En el diseño se conjuga una matriz compuesta por Calcita (26,73 %, Ferrosilicio (19,02 %,Ferromanganeso (16,58 %, Rutilo (26,69 %, Silicato de Potasio (11,70 % y diferentes cargas de aleación conformadas por Grafito (2 ≤ X1 ≤ 10 %, Ferro Cromo (5 ≤ X2 ≤ 35 %, ferrotungsteno (5 ≤ X3 ≤ 10 % y matriz (60 ≤ X4 ≤ 80 %. En el trabajo se ofrecen criterios sobre la selección de los niveles límites a explorar durante el plan experimental, a partir de consideraciones sobre los materiales empleados, sus rangos y el procedimiento de fabricación de los electrodos.Palabras claves: electrodos recubiertos, recubrimientos de electrodos, smaw, diseño de experimentos, relleno superficial._______________________________________________________________________________AbstractIn the present work the behavior of recovered electrodes for superficial filler with Shielded Metal Arc Welding (SMAW process is study. For the experimental design a coating calculation procedure and a Mc. Lean- Anderson type experimental plan are used. On the experimental design a matrix, composed by Calcite (26,73 %, Ferrosilicio (19,02%, Ferromanganese (16,58%, Rutile (26,69%, Potassium Silicate (11,70 %, and a alloy, conformed by Graphite (2 ≤ X1 ≤ 10, Ferro Chromium (5 ≤ X2 ≤ 35 %, ferrotungsteno (5 ≤ X3 ≤ 10 % and matrix (60 ≤ X4 ≤ 80 % is conjugated. In the work some criteria on the selection of the levels limits to explore during the experimental plan are offer, starting from considerations on the materials employees, their ranges and the procedure of production of the electrodes.Key words: recovered electrodes, electrodes coating, smaw

  16. Excited states rotational effects on the behavior of excited molecules

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 7 is a collection of papers that discusses the excited states of molecules. The first paper reviews the rotational involvement in intra-molecular in vibrational redistribution. This paper analyzes the vibrational Hamiltonian as to its efficacy in detecting the manifestations of intra-molecular state-mixing in time-resolved and time-averaged spectroscopic measurements. The next paper examines the temporal behavior of intra-molecular vibration-rotation energy transfer (IVRET) and the effects of IVRET on collision, reaction, and the decomposition processes. This paper also

  17. Variable Separation Approach to Solve (2 + 1)-Dimensional Generalized Burgers System:Solitary Wave and Jacobi Periodic Wave Excitations

    Institute of Scientific and Technical Information of China (English)

    ZHENG Chun-Long

    2004-01-01

    By means of the standard truncated Painleve expansion and a variable separation approach, a general variable separation solution of the generalized Burgers system is derived. In addition to the usual localized coherent soliton excitations like dromions, lumps, rings, breathers, instantons, oscillating soliton excitations, peakons, foldons,and previously revealed chaotic and fractal localized solutions, some new types of excitations - compacton and Jacobi periodic wave solutions are obtained by introducing appropriate lower dimensional piecewise smooth functions and Jacobi elliptic functions.

  18. Electron Energy Loss and One- and Two-Photon Excited SERS Probing of “Hot” Plasmonic Silver Nanoaggregates

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Wagner, Jakob Birkedal; Joseph, Virginia;

    2013-01-01

    between two- and one-photon excited SERS measured at different excitation wavelengths provides information about local fields in the hottest spots and their dependence on the photon energy. Our data verify experimentally the predicted increase of local optical fields in the hot spots with increasing wave...

  19. Energy spectrum for a strongly correlated network and local magnetism

    Institute of Scientific and Technical Information of China (English)

    Li-li LIU; Qiao BI

    2009-01-01

    In this work, we consider a quantum strongly correlated network described by an Anderson s-d mixing model. By introducing the Green function on the projected formalism of the Schrieffer and Wolf transformation, the energy spectrum of the system can be obtained. Using this result we calculate the survivability distribution of the network and discuss the local magnetism in the network, which shows that the survivability is an important statistical characteristic quantity not just to reflect the network topological property but also dynamics.

  20. Effet de l'interaction coulombienne sur la localisation d'Anderson dans le gaz bidimensionnel d'électrons

    Science.gov (United States)

    Fleury, G.

    2010-09-01

    Nous étudions l’effet des interactions coulombiennes sur la localisation d’Anderson dans le gaz bidimensionnel d’électrons désordonné. L’objectif est de statuer sur la question de l’existence de métaux à deux dimensions. En l’absence d’interaction, la théorie d’échelle de la localisation prédit qu’un désordre infinitésimal suffit à localiser la fonction d’onde électronique et donc à rendre le système isolant à température nulle (Abrahams et al., 1979). Dans certaines limites extrêmes, les interactions peuvent être prises en compte et l’on aboutit également à un état isolant. Cependant, aucune théorie analytique ne permet de traiter le régime quantique non-perturbatif où désordre et interaction sont intermédiaires. Expérimentalement, il est possible de l’explorer dans des échantillons de haute mobilité et basse densité. Depuis 1994, des comportements métalliques inexpliqués y ont été observés (Kravchenko et al., 1994). Nous avons mis au point une méthode numérique permettant d’étudier le problème couplé de la localisation d’Anderson en présence d’interaction. Cette méthode mêle Monte Carlo quantique à température nulle et théorie d’échelle pour la conductance de Thouless. Nous trouvons que la théorie d’échelle de la localisation est préservée en présence d’interaction et donc que le gaz bidimensionnel, même corrélé, est isolant à température nulle. Nos résultats montrent de plus que les interactions délocalisent le gaz bidimensionnel et que cet effet de délocalisation est accru en présence de dégénérescence de vallées. Ils nous permettent de proposer un mécanisme simple rendant compte des principales caractéristiques des comportements métalliques observés expérimentalement.