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Sample records for blume-emery-griffiths spin-1 system

  1. Schelling segregation in an open city: A kinetically constrained Blume-Emery-Griffiths spin-1 system

    NASA Astrophysics Data System (ADS)

    Gauvin, Laetitia; Nadal, Jean-Pierre; Vannimenus, Jean

    2010-06-01

    In the 70s Schelling introduced a multiagent model to describe the segregation dynamics that may occur with individuals having only weak preferences for “similar” neighbors. Recently variants of this model have been discussed, in particular, with emphasis on the links with statistical physics models. Whereas these models consider a fixed number of agents moving on a lattice, here, we present a version allowing for exchanges with an external reservoir of agents. The density of agents is controlled by a parameter which can be viewed as measuring the attractiveness of the city lattice. This model is directly related to the zero-temperature dynamics of the Blume-Emery-Griffiths spin-1 model, with kinetic constraints. With a varying vacancy density, the dynamics with agents making deterministic decisions leads to a variety of “phases” whose main features are the characteristics of the interfaces between clusters of agents of different types. The domains of existence of each type of interface are obtained analytically as well as numerically. These interfaces may completely isolate the agents leading to another type of segregation as compared to what is observed in the original Schelling model, and we discuss its possible socioeconomic correlates.

  2. Comparison of the ferromagnetic Blume-Emery-Griffiths model and the AF spin-1 longitudinal Ising model at low temperature

    NASA Astrophysics Data System (ADS)

    Thomaz, M. T.; Corrêa Silva, E. V.

    2016-03-01

    We derive the exact Helmholtz free energy (HFE) of the standard and staggered one-dimensional Blume-Emery-Griffiths (BEG) model in the presence of an external longitudinal magnetic field. We discuss in detail the thermodynamic behavior of the ferromagnetic version of the model, which exhibits magnetic field-dependent plateaux in the z-component of its magnetization at low temperatures. We also study the behavior of its specific heat and entropy, both per site, at finite temperature. The degeneracy of the ground state, at T=0, along the lines that separate distinct phases in the phase diagram of the ferromagnetic BEG model is calculated, extending the study of the phase diagram of the spin-1 antiferromagnetic (AF) Ising model in S.M. de Souza and M.T. Thomaz, J. Magn. and Magn. Mater. 354 (2014) 205 [5]. We explore the implications of the equality of phase diagrams, at T=0, of the ferromagnetic BEG model with K/|J| = - 2 and of the spin-1 AF Ising model for D/|J| > 1/2.

  3. Random-anisotropy Blume-Emery-Griffiths model

    NASA Technical Reports Server (NTRS)

    Maritan, Amos; Cieplak, Marek; Swift, Michael R.; Toigo, Flavio; Banavar, Jayanth R.

    1992-01-01

    The results are described of studies of a random-anisotropy Blume-Emery-Griffiths spin-1 Ising model using mean-field theory, transfer-matrix calculations, and position-space renormalization-group calculations. The interplay between the quenched randomness of the anisotropy and the annealed disorder introduced by the spin-1 model leads to a rich phase diagram with a variety of phase transitions and reentrant behavior. The results may be relevant to the study of the phase separation of He-3 - He-4 mixtures in porous media in the vicinity of the superfluid transition.

  4. Blume-Emery-Griffiths dynamics in social networks

    NASA Astrophysics Data System (ADS)

    Yang, Yao-Hui

    2010-08-01

    We introduce the Blume-Emery-Griffiths (BEG) model in a social networks to describe the three-state dynamics of opinion formation. It shows that the probability distribution function of the time series of opinion is a Gaussian-like distribution. We also study the response of BEG model to the external periodic perturbation. One can observe that both the interior thermo-noise and the external field result in phase transition, which is a split phenomena of the opinion distributions. It is opposite between the effect acted on the opinion systems of the amplitude of the external field and of the thermo-noise.

  5. Dynamical arrest with zero complexity: The unusual behavior of the spherical Blume-Emery-Griffiths disordered model

    NASA Astrophysics Data System (ADS)

    Rainone, Corrado; Ferrari, Ulisse; Paoluzzi, Matteo; Leuzzi, Luca

    2015-12-01

    The short- and long-time dynamics of model systems undergoing a glass transition with apparent inversion of Kauzmann and dynamical arrest glass transition lines is investigated. These models belong to the class of the spherical mean-field approximation of a spin-1 model with p -body quenched disordered interaction, with p >2 , termed spherical Blume-Emery-Griffiths models. Depending on temperature and chemical potential the system is found in a paramagnetic or in a glassy phase and the transition between these phases can be of a different nature. In specific regions of the phase diagram coexistence of low-density and high-density paramagnets can occur, as well as the coexistence of spin-glass and paramagnetic phases. The exact static solution for the glassy phase is known to be obtained by the one-step replica symmetry breaking ansatz. Different scenarios arise for both the dynamic and the thermodynamic transitions. These include: (i) the usual random first-order transition (Kauzmann-like) for mean-field glasses preceded by a dynamic transition, (ii) a thermodynamic first-order transition with phase coexistence and latent heat, and (iii) a regime of apparent inversion of static transition line and dynamic transition lines, the latter defined as a nonzero complexity line. The latter inversion, though, turns out to be preceded by a dynamical arrest line at higher temperature. Crossover between different regimes is analyzed by solving mode-coupling-theory equations near the boundaries of paramagnetic solutions and the relationship with the underlying statics is discussed.

  6. Dynamic phase transitions of the Blume-Emery-Griffiths model under an oscillating external magnetic field by the path probability method

    NASA Astrophysics Data System (ADS)

    Ertaş, Mehmet; Keskin, Mustafa

    2015-03-01

    By using the path probability method (PPM) with point distribution, we study the dynamic phase transitions (DPTs) in the Blume-Emery-Griffiths (BEG) model under an oscillating external magnetic field. The phases in the model are obtained by solving the dynamic equations for the average order parameters and a disordered phase, ordered phase and four mixed phases are found. We also investigate the thermal behavior of the dynamic order parameters to analyze the nature dynamic transitions as well as to obtain the DPT temperatures. The dynamic phase diagrams are presented in three different planes in which exhibit the dynamic tricritical point, double critical end point, critical end point, quadrupole point, triple point as well as the reentrant behavior, strongly depending on the values of the system parameters. We compare and discuss the dynamic phase diagrams with dynamic phase diagrams that were obtained within the Glauber-type stochastic dynamics based on the mean-field theory.

  7. Tricriticality of the Blume-Emery-Griffiths model in thin films of stacked triangular lattices

    NASA Astrophysics Data System (ADS)

    El Hog, Sahbi; Diep, H. T.

    2016-03-01

    We study in this paper the Blume-Emery-Griffiths model in a thin film of stacked triangular lattices. The model is described by three parameters: bilinear exchange interaction between spins J, quadratic exchange interaction K and single-ion anisotropy D. The spin Si at the lattice site i takes three values (-1, 0, +1). This model can describe the mixing phase of He-4 (Si = +1,-1) and He-3 (Si = 0) at low temperatures. Using Monte Carlo simulations, we show that there exists a critical value of D below (above) which the transition is of second-(first-)order. In general, the temperature dependence of the concentrations of He-3 is different from layer by layer. At a finite temperature in the superfluid phase, the film surface shows a deficit of He-4 with respect to interior layers. However, effects of surface interaction parameters can reverse this situation. Effects of the film thickness on physical properties will be also shown as functions of temperature.

  8. Phase transition in the spin- 3 / 2 Blume-Emery-Griffiths model with antiferromagnetic second neighbor interactions

    NASA Astrophysics Data System (ADS)

    Yezli, M.; Bekhechi, S.; Hontinfinde, F.; EZ-Zahraouy, H.

    2016-04-01

    Two nonperturbative methods such as Monte-Carlo simulation (MC) and Transfer-Matrix Finite-Size-Scaling calculations (TMFSS) have been used to study the phase transition of the spin- 3 / 2 ​Blume-Emery-Griffiths model (BEG) with quadrupolar and antiferromagnetic next-nearest-neighbor exchange interactions. Ground state and finite temperature phase diagrams are obtained by means of these two methods. New degenerate phases are found and only second order phase transitions occur for all values of the parameter interactions. No sign of the intermediate phase is found from both methods. Critical exponents are also obtained from TMFSS calculations. Ising criticality and nonuniversal behaviors are observed depending on the strength of the second neighbor interaction.

  9. The Blume Emery Griffiths model at an infinitely many ground states interface and exponential decay of correlations at all non-zero temperatures

    NASA Astrophysics Data System (ADS)

    Braga, Gastão A.; Lima, Paulo C.

    2003-09-01

    In this paper we study the spin-spin correlation function decay properties of the Blume-Emery-Griffiths (BEG) model with Hamiltonian located on the interface between the disordered and the anti-quadrupolar phases. On this interface, the BEG model has infinitely many ground state configurations. We show that, for any dimension d, there exists a parameter value, yd, below which the spin-spin correlation function with zero boundary condition decays exponentially fast at all non-zero temperatures. This result suggests that reentrant behaviour predicted by mean-field and numerical calculations may be absent for those values of parameters.

  10. Ground-state phase diagram and magnetization process of the exactly solved mixed spin-(1,1/2) Ising diamond chain

    NASA Astrophysics Data System (ADS)

    Lisnyi, Bohdan; Strečka, Jozef

    2013-11-01

    The ground state and magnetization process of the mixed spin-(1,1/2) Ising diamond chain are exactly solved by employing the generalized decoration-iteration mapping transformation and the transfer-matrix method. The decoration-iteration transformation is first used in order to establish a rigorous mapping equivalence with the corresponding spin-1 Blume-Emery-Griffiths chain in a non-zero magnetic field, which is subsequently exactly treated within the framework of the transfer-matrix technique. It is shown that the ground-state phase diagram includes just four different ground states and the low-temperature magnetization curve may exhibit an intermediate plateau precisely at one half of the saturation magnetization. Our rigorous results disprove recent Monte Carlo simulations of Xin et al. [Z. Xin, S. Chen, C. Zhang, J. Magn. Magn. Mater. 324 (2012) 3704], which imply an existence of the other magnetization plateaus at 0.283 and 0.426 of the saturation magnetization.

  11. Visualization of an entangled channel spin-1 system

    SciTech Connect

    Sirsi, Swarnamala; Adiga, Veena

    2010-08-15

    Covariance matrix formalism gives powerful entanglement criteria for continuous as well as finite dimensional systems. We use this formalism to study a mixed channel spin-1 system which is well known in nuclear reactions. A spin-j state can be visualized as being made up of 2j spinors which are represented by a constellation of 2j points on a Bloch sphere using Majorana construction. We extend this formalism to visualize an entangled mixed spin-1 system.

  12. Pair approximation method for spin-1 Heisenberg system

    NASA Astrophysics Data System (ADS)

    Mert, Murat; Kılıç, Ahmet; Mert, Gülistan

    2016-03-01

    Spin-1 Heisenberg system on simple cubic lattice is considered in the pair approximation method assuming that the second-nearest-neighbor exchange interaction parameter has a negative value. The system is described in presence of an external magnetic field. The effects of the negative single-ion anisotropy and the negative second-nearest-neighbor exchange interaction on magnetization, internal energy, heat capacity, entropy and free energy are investigated. There are diverse anomalies at low temperature. In the magnetization and other thermodynamic quantities, the first-order phase transitions from ferromagnetic state to antiferromagnetic state and from ferromagnetic state to paramagnetic state have been observed.

  13. Classical models of the spin 1/2 system

    NASA Astrophysics Data System (ADS)

    Salazar-Lazaro, Carlos H.

    We proposed a Quaternionic mechanical system motivated by the Foucault pendulum as a classical model for the dynamics of the spin ½ system. We showed that this mechanical system contains the dynamics of the spin state of the electron under a uniform magnetic field as it is given by the Schrodinger-Pauli-Equation (SPE). We closed with a characterization of the dynamics of this generalized classical system by showing that it is equivalent with the dynamics of the Schrodinger Pauli Equation as long as the solutions to the generalized classical system are roots of the Lagrangian, that is the condition L = 0 holds.

  14. Student understanding of the time dependence of spin-1/2 systems

    NASA Astrophysics Data System (ADS)

    Passante, Gina

    2016-03-01

    Time dependence is one of the most difficult concepts in quantum mechanics and one that is relevant throughout instruction. In this talk I will explore student responses to written questions regarding the time dependence for spin-1/2 systems after lecture instruction and again after a tutorial on the topic. These questions were asked in a junior-level quantum mechanics course that is taught using a spins-first curriculum.

  15. Phase-space spinor amplitudes for spin-1/2 systems

    NASA Astrophysics Data System (ADS)

    Watson, P.; Bracken, A. J.

    2011-04-01

    The concept of phase-space amplitudes for systems with continuous degrees of freedom is generalized to finite-dimensional spin systems. Complex amplitudes are obtained on both a sphere and a finite lattice, in each case enabling a more fundamental description of pure spin states than that previously given by Wigner functions. In each case the Wigner function can be expressed as the star product of the amplitude and its conjugate, so providing a generalized Born interpretation of amplitudes that emphasizes their more fundamental status. The ordinary product of the amplitude and its conjugate produces a (generalized) spin Husimi function. The case of spin-(1)/(2) is treated in detail, and it is shown that phase-space amplitudes on the sphere transform correctly as spinors under rotations, despite their expression in terms of spherical harmonics. Spin amplitudes on a lattice are also found to transform as spinors. Applications are given to the phase space description of state superposition, and to the evolution in phase space of the state of a spin-(1)/(2) magnetic dipole in a time-dependent magnetic field.

  16. Bethe lattice approach and relaxation dynamics study of spin-crossover materials

    NASA Astrophysics Data System (ADS)

    Oke, Toussaint Djidjoho; Hontinfinde, Félix; Boukheddaden, Kamel

    2015-07-01

    Dynamical properties of Prussian blue analogs and spin-crossover materials are investigated in the framework of a Blume-Emery-Griffiths (BEG) spin-1 model, where states ±1 and 0 represent the high-spin (HS) state and the low-spin state, respectively. The quadrupolar interaction depends on the temperature in the form . Magnetic interactions are controlled by a factor such that for (), magnetic ordering is not expected. The model is exactly solved using the Bethe lattice approach for the equilibrium properties. The results are closer to those calculated by numerical simulations with suitable Arrhenius-type transition rates. The study of relaxation processes of non-equilibrium HS states revealed one-step nonlinear sigmoidal relaxation curves of the HS fraction at low temperatures. We found that increasing the magnetic interactions leads to the appearance of a plateau in the thermal hysteresis as well as in the relaxation curves of the HS fraction at low temperature.

  17. Quantum refrigeration cycles using spin-1/2 systems as the working substance.

    PubMed

    He, Jizhou; Chen, Jincan; Hua, Ben

    2002-03-01

    The cycle model of a quantum refrigerator composed of two isothermal and two isomagnetic field processes is established. The working substance in the cycle consists of many noninteracting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semigroup approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate, and power input, are given. Especially, the case at high temperatures is analyzed in detail. The results obtained are further generalized and discussed, so that they may be directly used to describe the performance of the quantum refrigerator using spin-J systems as the working substance. Finally, the optimum characteristics of the quantum Carnot refrigerator are derived simply. PMID:11909203

  18. Triple quantum filtered spectroscopy of homonuclear three spin-1/2 systems employing isotropic mixing

    NASA Astrophysics Data System (ADS)

    Kirwai, Amey; Chandrakumar, N.

    2016-08-01

    We report the design and performance evaluation of novel pulse sequences for triple quantum filtered spectroscopy in homonuclear three spin-1/2 systems, employing isotropic mixing (IM) to excite triple quantum coherence (TQC). Our approach involves the generation of combination single quantum coherences (cSQC) from antisymmetric longitudinal or transverse magnetization components employing isotropic mixing (IM). cSQC's are then converted to TQC by a selective 180° pulse on one of the spins. As IM ideally causes magnetization to evolve under the influence of the spin coupling Hamiltonian alone, TQC is generated at a faster rate compared to sequences involving free precession. This is expected to be significant when the spins have large relaxation rates. Our approach is demonstrated experimentally by TQC filtered 1D spectroscopy on a 1H AX2 system (propargyl bromide in the presence of a paramagnetic additive), as well as a 31P linear AMX system (ATP in agar gel). The performance of the IM-based sequences for TQC excitation are compared against the standard three pulse sequence (Ernst et al., 1987) and an AX2 spin pattern recognition sequence (Levitt and Ernst, 1983). The latter reaches the unitary bound on TQC preparation efficiency starting from thermal equilibrium in AX2 systems, not considering relaxation. It is shown that in systems where spins relax rapidly, the new IM-based sequences indeed perform significantly better than the above two known TQC excitation sequences, the sensitivity enhancement being especially pronounced in the case of the proton system investigated. An overview of the differences in relaxation behavior is presented for the different approaches. Applications are envisaged to Overhauser DNP experiments and to in vivo NMR.

  19. Triple quantum filtered spectroscopy of homonuclear three spin-1/2 systems employing isotropic mixing.

    PubMed

    Kirwai, Amey; Chandrakumar, N

    2016-08-01

    We report the design and performance evaluation of novel pulse sequences for triple quantum filtered spectroscopy in homonuclear three spin-1/2 systems, employing isotropic mixing (IM) to excite triple quantum coherence (TQC). Our approach involves the generation of combination single quantum coherences (cSQC) from antisymmetric longitudinal or transverse magnetization components employing isotropic mixing (IM). cSQC's are then converted to TQC by a selective 180° pulse on one of the spins. As IM ideally causes magnetization to evolve under the influence of the spin coupling Hamiltonian alone, TQC is generated at a faster rate compared to sequences involving free precession. This is expected to be significant when the spins have large relaxation rates. Our approach is demonstrated experimentally by TQC filtered 1D spectroscopy on a (1)H AX2 system (propargyl bromide in the presence of a paramagnetic additive), as well as a (31)P linear AMX system (ATP in agar gel). The performance of the IM-based sequences for TQC excitation are compared against the standard three pulse sequence (Ernst et al., 1987) and an AX2 spin pattern recognition sequence (Levitt and Ernst, 1983). The latter reaches the unitary bound on TQC preparation efficiency starting from thermal equilibrium in AX2 systems, not considering relaxation. It is shown that in systems where spins relax rapidly, the new IM-based sequences indeed perform significantly better than the above two known TQC excitation sequences, the sensitivity enhancement being especially pronounced in the case of the proton system investigated. An overview of the differences in relaxation behavior is presented for the different approaches. Applications are envisaged to Overhauser DNP experiments and to in vivo NMR. PMID:27253727

  20. A simple protocol for the probability weights of the simulated tempering algorithm: Applications to first-order phase transitions

    NASA Astrophysics Data System (ADS)

    Fiore, Carlos E.; da Luz, M. G. E.

    2010-12-01

    The simulated tempering (ST) is an important method to deal with systems whose phase spaces are hard to sample ergodically. However, it uses accepting probabilities weights, which often demand involving and time consuming calculations. Here it is shown that such weights are quite accurately obtained from the largest eigenvalue of the transfer matrix—a quantity straightforward to compute from direct Monte Carlo simulations—thus simplifying the algorithm implementation. As tests, different systems are considered, namely, Ising, Blume-Capel, Blume-Emery-Griffiths, and Bell-Lavis liquid water models. In particular, we address first-order phase transition at low temperatures, a regime notoriously difficulty to simulate because the large free-energy barriers. The good results found (when compared with other well established approaches) suggest that the ST can be a valuable tool to address strong first-order phase transitions, a possibility still not well explored in the literature.

  1. Quantum phase diagrams and time-of-flight pictures of spin-1 Bose systems in honeycomb optical lattices

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Jiang, Ying

    2016-09-01

    By treating the hopping parameter as a perturbation, with the help of cumulant expansion and the re-summing technique, the one-particle Green’s function of a spin-1 Bose system in a honeycomb optical lattice is calculated analytically. By the use of the re-summed Green’s function, the quantum phase diagrams of the system in ferromagnetic cases as well as in antiferromagnetic cases are determined. It is found that in antiferromagnetic cases the Mott insulating states with even filling factor are more robust against the hopping parameter than that with odd filling factor, in agreement with results via other different approaches. Moreover, in order to illustrate the effectiveness of the re-summed Green’s function method in calculating time-of-flight pictures, the momentum distribution function of a honeycomb lattice spin-1 Bose system in the antiferromagnetic case is also calculated analytically and the corresponding time-of-flight absorption pictures are plotted.

  2. Collective uncertainty in partially polarized and partially decohered spin-(1/2) systems

    SciTech Connect

    Baragiola, Ben Q.; Chase, Bradley A.; Geremia, JM

    2010-03-15

    It has become common practice to model large spin ensembles as an effective pseudospin with total angular momentum J=Nj, where j is the spin per particle. Such approaches (at least implicitly) restrict the quantum state of the ensemble to the so-called symmetric Hilbert space. Here, we argue that symmetric states are not generally well preserved under the type of decoherence typical of experiments involving large clouds of atoms or ions. In particular, symmetric states are rapidly degraded under models of decoherence that act identically but locally on the different members of the ensemble. Using an approach [Phys. Rev. A 78, 052101 (2008)] that is not limited to the symmetric Hilbert space, we explore potential pitfalls in the design and interpretation of experiments on spin-squeezing and collective atomic phenomena when the properties of the symmetric states are extended to systems where they do not apply.

  3. SUSY partners for spin-1/2 systems in nonrelativistic limits

    NASA Astrophysics Data System (ADS)

    Takou, Daniel Sabi; Avossevou, Gabriel Y. H.; Kounouhewa, Basile B.

    2015-02-01

    In this paper, we use some well-known techniques of Supersymmetric QuantumMechanics (SUSYQM) namely the factorization method and shape invariance, to generate new analytically solvable potentials from some interacting fermionic models in nonrelativistic limits. These systems are described by the ordinary and the harmonically trapped Schrödinger-Pauli particle models and the Dirac-Coulomb Hamiltonian, this latter being set in its nonrelativistic limits. The spectrum for each of these models is obtained in a simple and transparent way. We then generate new solvable potentials that describe interactions between electromagnetic field and matter, paying due attention to the subtleties inherent in the application of SUSY to higher dimensional problems. SUSY breaking problems related to the partner singularities are dicussed along with the paper.

  4. Spin-1/2 XXZ chain system Cs2CoCl4 in a transverse magnetic field.

    PubMed

    Breunig, O; Garst, M; Sela, E; Buldmann, B; Becker, P; Bohatý, L; Müller, R; Lorenz, T

    2013-11-01

    Comparing high-resolution specific heat and thermal expansion measurements to exact finite-size diagonalization, we demonstrate that Cs(2)CoCl(4) for a magnetic field along the crystallographic b axis realizes the spin-1/2 XXZ chain in a transverse field. Exploiting both thermal as well as virtual excitations of higher crystal-field states, we find that the spin chain is in the XY limit with an anisotropy J(z)/J[perpindicular] ≈ 0.12, substantially smaller than previously believed. A spin-flop Ising quantum phase transition occurs at a critical field of μ(0)H(b)(cr) ≈ 2 T before around 3.5 T the description in terms of an effective spin-1/2 chain becomes inapplicable. PMID:24237555

  5. Spin-1 Dirac-Weyl fermions protected by bipartite symmetry

    NASA Astrophysics Data System (ADS)

    Lin, Zeren; Liu, Zhirong

    2015-12-01

    We propose that bipartite symmetry allows spin-1 Dirac-Weyl points, a generalization of the spin-1/2 Dirac points in graphene, to appear as topologically protected at the Fermi level. In this spirit, we provide methodology to construct spin-1 Dirac-Weyl points of this kind in a given 2D space group and get the classification of the known spin-1 systems in the literature. We also apply the workflow to predict two new systems, P3m1-9 and P31m-15, to possess spin-1 at K/K' in the Brillouin zone of hexagonal lattice. Their stability under various strains is investigated and compared with that of T3, an extensively studied model of ultracold atoms trapped in optical lattice with spin-1 also at K/K'.

  6. Spin-1 Dirac-Weyl fermions protected by bipartite symmetry

    SciTech Connect

    Lin, Zeren; Liu, Zhirong

    2015-12-07

    We propose that bipartite symmetry allows spin-1 Dirac-Weyl points, a generalization of the spin-1/2 Dirac points in graphene, to appear as topologically protected at the Fermi level. In this spirit, we provide methodology to construct spin-1 Dirac-Weyl points of this kind in a given 2D space group and get the classification of the known spin-1 systems in the literature. We also apply the workflow to predict two new systems, P3m1-9 and P31m-15, to possess spin-1 at K/K′ in the Brillouin zone of hexagonal lattice. Their stability under various strains is investigated and compared with that of T{sub 3}, an extensively studied model of ultracold atoms trapped in optical lattice with spin-1 also at K/K′.

  7. Spin compensation temperature in the Monte Carlo study of a mixed spin-1 and spin-3/2 Ising ferrimagnetic system on the decorated triangular lattice

    NASA Astrophysics Data System (ADS)

    Masrour, R.; Jabar, A.

    2016-07-01

    Mixed-spin-1 and spin-3/2 Ising model on the decorated triangular lattice is studied by the use of Monte Carlo simulation. Within this approach, the results for the ground-state of the antiferromagnetic and ferromagnetic of decorated triangular lattice are obtained. The reduced transition temperature of each sublattice are obtained. The reduced temperature of compensation is also obtained. The thermal total ratio of magnetic susceptibilities of sublattices is given. The effect of crystal field and exchange interactions on the magnetization of the system are detailed. The magnetic hysteresis cycles are found for different values of exchanges interactions between the same lattice and the two sublattices different, for different crystal filed and temperatures. In addition, very weak exchange interactions and for a higher temperatures and a higher crystal filed values the decorated triangular lattice has been exhibited the superparamagnetic behavior.

  8. Physics of Inference

    NASA Astrophysics Data System (ADS)

    Toroczkai, Zoltan

    Jaynes's maximum entropy method provides a family of principled models that allow the prediction of a system's properties as constrained by empirical data (observables). However, their use is often hindered by the degeneracy problem characterized by spontaneous symmetry breaking, where predictions fail. Here we show that degeneracy appears when the corresponding density of states function is not log-concave, which is typically the consequence of nonlinear relationships between the constraining observables. We illustrate this phenomenon on several examples, including from complex networks, combinatorics and classical spin systems (e.g., Blume-Emery-Griffiths lattice-spin models). Exploiting these nonlinear relationships we then propose a solution to the degeneracy problem for a large class of systems via transformations that render the density of states function log-concave. The effectiveness of the method is demonstrated on real-world network data. Finally, we discuss the implications of these findings on the relationship between the geometrical properties of the density of states function and phase transitions in spin systems. Supported in part by Grant No. FA9550-12-1-0405 from AFOSR/DARPA and by Grant No. HDTRA 1-09-1-0039 from DTRA.

  9. Neutron scattering study of a quasi-2D spin-1/2 dimer system Piperazinium Hexachlorodicuprate under hydrostatic pressure

    SciTech Connect

    Hong, Tao; Stock, C.; Cabrera, I.; Broholm, C.; Qiu, Y.; Leao, J. B.; Poulton, S. J.; Copley, J.R.D.

    2010-01-01

    We report inelastic neutron scattering study of a quasi-two-dimensional S=1/2 dimer system piperazinium hexachlorodicuprate under hydrostatic pressure. The spin gap {Delta} becomes softened with the increase of the hydrostatic pressure up to P = 9.0 kbar. The observed threefold degenerate triplet excitation at P = 6.0 kbar is consistent with the theoretical prediction and the bandwidth of the dispersion relation is unaffected within the experimental uncertainty. At P = 9.0 kbar the spin gap is reduced to {Delta} = 0.55 meV from {Delta} = 1.0 meV at ambient pressure.

  10. Influence of the nonmagnetic impurities on the spin-1 Heisenberg chain SrNi2V2O8 system

    NASA Astrophysics Data System (ADS)

    Giapintzakis, J.; Androulakis, J.; Syskakis, E.; Papageorgiou, Th. P.; Apostolopoulos, G.; Thanos, S.; Papastaikoudis, C.

    Dc-magnetization and heat capacity measurements on polycrystalline samples of SrNi2-x Mgx V2O8 (x = 0 and 0.05) are reported. The magnetization data suggest that both compounds are S = 1 quasi one-dimensional Heisenberg antiferromagnets. The substitution of non-magnetic impurity Mg2+ ions for Ni2+ induces a magnetic phase transition at ?3.7 K. A simple Hamiltonian model is proposed for these systems giving good quantitative agreement with the experimental magnetization data. The intrachain magnetic exchange constant (J 1/k B) and the Haldane gap (? ) for both compounds are estimated to be ?105 K and ?58.3 K (5.02 meV), respectively.

  11. Magnetic specific heat studies of two Ising spin 1/2 chain systems M(N3)2(bpy)

    NASA Astrophysics Data System (ADS)

    Hamida, Youcef; Danilovic, Dusan; Yuen, Tan; Li, Kunhao; Li, Jing

    2012-04-01

    M(N3)2(bpy) [where M = Cu(II), Co(II), N3 = azide, and bpy = 4,4'-bipyridine] are two newly synthesized metal-organic framework (MOF) systems, in which the divalent M ions are connected though the azide ligands forming almost ideal magnetic 1 D chains. Specific heat measurements were performed on these compounds and the magnetic specific heats were deduced using appropriate methods for estimating the lattice specific heat. The magnetic specific heat data were analyzed and fit to the Ising model. The exchange interaction J/kB values of 13.1 K for Cu(N3)2(bpy) and 8.2 K for Co(N3)2(bpy) were obtained and compared to the J values from fitting the measured magnetic susceptibility data.

  12. Quantumness of spin-1 states

    NASA Astrophysics Data System (ADS)

    Bohnet-Waldraff, Fabian; Braun, D.; Giraud, O.

    2016-01-01

    We investigate quantumness of spin-1 states, defined as the Hilbert-Schmidt distance to the convex hull of spin coherent states. We derive its analytic expression in the case of pure states as a function of the smallest eigenvalue of the Bloch matrix and give explicitly the closest classical state for an arbitrary pure state. Numerical evidence is given that the exact formula for pure states provides an upper bound on the quantumness of mixed states. Due to the connection between quantumness and entanglement we obtain new insights into the geometry of symmetric entangled states.

  13. Interplay between spin-crossover and magnetic interactions in a BEG model

    NASA Astrophysics Data System (ADS)

    Oke, T. D.; Hontinfinde, F.; Boukheddaden, K.

    2013-06-01

    A two-dimensional Blume-Emery-Griffiths spin-1 model with spin-phonon interaction is introduced to investigate the thermodynamic properties of Prussian Blue Analogs and Spin-crossover materials. The quadrupolar interaction parameter is assumed to depend on the temperature in the form K = α k B T while the crystal-field depends both on the ligand-field strength and the degeneracy ratio between high spin (HS) and low spin (LS) states as in some previous works. The model is solved by means of two statistical-mechanical methods: kinetic Monte Carlo simulations and corrective effective field theory calculations. Our calculations indicate that by tuning α, the spin-crossover transition changes to a sharp first order transition where the HS fraction, n HS changes discontinuously. Second order transitions are observed in the presence of magnetic ordering when the nearest-neighbor coupling constant J exceeds some critical value J c which depends on α and other model parameters. Below J c , simple spin-transition occurs at an equilibrium temperature T eq that is very sensitive to the values of the degenaracy ratio and the ligand-field. Competition between model parameters lead to interesting phase diagrams. Some of them are displayed for varying values of the coupling J and also in the specific case where J and K are of the same order of magnitude. Thermal hysteresis loops have been calculated by Monte Carlo simulations and also by using the self-consistent equations in the case of long-lived metastable states showing strong dependence on model parameters.

  14. Modified kagome physics in the natural spin-1/2 kagome lattice systems: kapellasite Cu3Zn(OH)6Cl2 and haydeeite Cu3Mg(OH)6Cl2.

    PubMed

    Janson, O; Richter, J; Rosner, H

    2008-09-01

    The recently discovered natural minerals Cu3Zn(OH)6Cl2 and Cu3Mg(OH)6Cl2 are spin 1/2 systems with an ideal kagome geometry. Based on electronic structure calculations, we develop a realistic model which includes couplings across the kagome hexagons beyond the original kagome model that are intrinsic in real kagome materials. Exact diagonalization studies for the derived model reveal a strong impact of these couplings on the magnetic ground state. Our predictions could be compared to and supplied with neutron scattering, thermodynamic data, and NMR data. PMID:18851233

  15. Frustrated mixed spin-1/2 and spin-1 Ising ferrimagnets on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Žukovič, M.; Bobák, A.

    2015-05-01

    Mixed spin-1/2 and spin-1 Ising ferrimagnets on a triangular lattice with sublattices A, B, and C are studied for two spin-value distributions (SA,SB,SC) =(1 /2 ,1 /2 ,1 ) and (1 /2 ,1 ,1 ) by Monte Carlo simulations. The nonbipartite character of the lattice induces geometrical frustration in both systems, which leads to the critical behavior rather different from their ferromagnetic counterparts. We confirm second-order phase transitions belonging to the standard Ising universality class occurring at higher temperatures, however, in both models these change at tricritical points (TCP) to first-order transitions at lower temperatures. In the model (1 /2 ,1 /2 ,1 ) , TCP occurs on the boundary between paramagnetic and ferrimagnetic (±1 /2 ,±1 /2 ,∓1 ) phases. The boundary between two ferrimagnetic phases (±1 /2 ,±1 /2 ,∓1 ) and (±1 /2 ,∓1 /2 ,0 ) at lower temperatures is always first order and it is joined by a line of second-order phase transitions between the paramagnetic and the ferrimagnetic (±1 /2 ,∓1 /2 ,0 ) phases at a critical endpoint. The tricritical behavior is also confirmed in the model (1 /2 ,1 ,1 ) on the boundary between the paramagnetic and ferrimagnetic (0 ,±1 ,∓1 ) phases.

  16. Dynamics of Spin-(1)/(2) Quantum Plasmas

    NASA Astrophysics Data System (ADS)

    Marklund, Mattias; Brodin, Gert

    2007-01-01

    The fully nonlinear governing equations for spin-(1)/(2) quantum plasmas are presented. Starting from the Pauli equation, the relevant plasma equations are derived, and it is shown that nontrivial quantum spin couplings arise, enabling studies of the combined collective and spin dynamics. The linear response of the quantum plasma in an electron-ion system is obtained and analyzed. Applications of the theory to solid state and astrophysical systems as well as dusty plasmas are pointed out.

  17. Dynamics of spin-1/2 quantum plasmas.

    PubMed

    Marklund, Mattias; Brodin, Gert

    2007-01-12

    The fully nonlinear governing equations for spin-1/2 quantum plasmas are presented. Starting from the Pauli equation, the relevant plasma equations are derived, and it is shown that nontrivial quantum spin couplings arise, enabling studies of the combined collective and spin dynamics. The linear response of the quantum plasma in an electron-ion system is obtained and analyzed. Applications of the theory to solid state and astrophysical systems as well as dusty plasmas are pointed out. PMID:17358613

  18. Neutron scattering study in the spin-1/2 ladder system: Sr{sub 14}Cu{sub 24}O{sub 41}

    SciTech Connect

    Matsuda, M.; Katsumata, K.; Shapiro, S.M.; Shirane, G.

    1996-10-01

    Inelastic neutron scattering measurements were performed on the S=1/2 quasi-one-dimensional system Sr{sub 14}Cu{sub 24}O{sub 41}, which has both simple chains and two-leg ladders of copper ions. We have observed that both the chain and the ladder exhibit a spin gap, which originates from a dimerized state.

  19. Phase ordering dynamics in spin-1 ferromagnetic condensates

    NASA Astrophysics Data System (ADS)

    Williamson, Lewis; Blakie, Peter

    2016-05-01

    Spinor Bose-Einstein condensates present rich phase diagrams for exploring phase transitions between states with different symmetry properties. In this work we simulate the approach to equilibrium of a spin-1 condensate quenched from an unmagnetised phase to three different ferromagnetic phases. The three ferromagnetic phases have Z2, SO(2) and SO(3) symmetries respectively and possess different conservation laws. Following the quench, domains of magnetization form, with each domain making an independent choice of the symmetry breaking order parameter. These domains grow and compete for the global equilibrium state. We find that this growth follows universal scaling laws and identify the dynamic universality class for each of the three quenches. Polar-core spin-vortices play a crucial role in the phase ordering of the SO(2) system and we identify fractal structures in the domain patterns of the SO(2) and SO(3) systems. We acknowledge support from the Marsden Fund of New Zealand.

  20. Investigations of quantum pendulum dynamics in a spin-1 BEC

    NASA Astrophysics Data System (ADS)

    Hoang, Thai; Gerving, Corey; Land, Ben; Anquez, Martin; Hamley, Chris; Chapman, Michael

    2013-05-01

    We investigate the quantum spin dynamics of a spin-1 BEC initialized to an unstable critical point of the dynamical phase space. The subsequent evolution of the collective states of the system is analogous to an inverted simple pendulum in the quantum limit and yields non-classical states with quantum correlations. For short evolution times in the low depletion limit, we observe squeezed states and for longer times beyond the low depletion limit we observe highly non-Gaussian distributions. C.D. Hamley, C.S. Gerving, T.M. Hoang, E.M. Bookjans, and M.S. Chapman, ``Spin-Nematic Squeezed Vacuum in a Quantum Gas,'' Nature Physics 8, 305-308 (2012).

  1. Phases of a polar spin-1 Bose gas in a magnetic field

    NASA Astrophysics Data System (ADS)

    Kis-Szabó, Krisztián; Szépfalusy, Péter; Szirmai, Gergely

    2007-05-01

    The two Bose Einstein condensed phases of a polar spin-1 gas at nonzero magnetizations and temperatures are investigated. The Hugenholtz Pines theorem is generalized to this system. Crossover to a quantum phase transition is also studied. Results are discussed in a mean field approximation.

  2. Spin quantum Hall effects in featureless nonfractionalized spin-1 magnets

    NASA Astrophysics Data System (ADS)

    Lu, Yuan-Ming; Lee, Dung-Hai

    2014-05-01

    The Affleck-Kennedy-Lieb-Tasaki state (or Haldane phase) in a spin-1 chain represents a large class of gapped topological paramagnets that host symmetry-protected gapless excitations on the boundary. In this work, we show how to realize this type of featureless spin-1 state on a generic two-dimensional lattice. These states have a gapped spectrum in the bulk, but they support gapless edge states protected by spin rotational symmetry along a certain direction, and they exhibit the spin quantum Hall effect. Using a fermion representation of integer spins, we show a concrete example of such spin-1 topological paramagnets on a kagome lattice, and we suggest a microscopic spin-1 Hamiltonian that may realize it.

  3. Most spin-1/2 transition-metal ions do have single ion anisotropy

    SciTech Connect

    Liu, Jia; Whangbo, Myung-Hwan E-mail: mike-whangbo@ncsu.edu; Koo, Hyun-Joo; Xiang, Hongjun E-mail: mike-whangbo@ncsu.edu; Kremer, Reinhard K.

    2014-09-28

    The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu{sup 2+} ions in CuCl{sub 2}·2H{sub 2}O, LiCuVO{sub 4}, CuCl{sub 2}, and CuBr{sub 2} on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu{sup 2+} ions of Bi{sub 2}CuO{sub 4} and Li{sub 2}CuO{sub 2}. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.

  4. Pulsed Spin Locking in Spin-1 NQR: Broadening Mechanisms

    NASA Astrophysics Data System (ADS)

    Malone, Michael W.

    , and therefore might have a significant heteronuclear dipolar coupling component. To incorporate this, a second model is developed composed of two different nuclear species, one spin 1 the other spin 1/2, although the work can be extended to additional spin species. This model reveals that heteronuclear dipolar coupling for this system behaves just like EFG broadening under spin locking, and that the strong homonuclear response is still observable. The experimental results closely match theoretical predictions, and the conclusions greatly expand the number of target substances that are suitable for this measurement technique of homonuclear dipolar coupling. The combined results explain why certain pulse sequences perform better than others for substance detection: it is because of the relative strengths of the line broadening mechanisms. Therefore the ability to measure homonuclear dipolar coupling's contribution to the linewidth is useful not only for material characterization, but also for substance detection. By explaining the conditions that reveal homonuclear coupling, we make it possible to measure the relative broadening strengths, increasing the efficiency of NQR in these roles.

  5. Magnetic entanglement in spin-1/2 XY chains

    NASA Astrophysics Data System (ADS)

    Fumani, Fatemeh Khastehdel; Nemati, Somayyeh; Mahdavifar, Saeed; Darooneh, Amir Hosein

    2016-03-01

    In the study of entanglement in a spin chain, people often consider the nearest-neighbor spins. The motivation is the prevailing role of the short range interactions in creating quantum correlation between the 1st neighbor (1N) spins. Here, we address the same question between farther neighbor spins. We consider the one-dimensional (1D) spin-1/2 XY model in a magnetic field. Using the fermionization approach, we diagonalize the Hamiltonian of the system. Then, we provide the analytical results for entanglement between the 2nd, 3rd and 4th neighbor (denoted as 2N, 3N, and 4N respectively) spins. We find a magnetic entanglement that starts from a critical entangled-field (hcE) at zero temperature. The critical entangled-field depends on the distance between the spins. In addition to the analytical results, the mentioned phenomenon is confirmed by the numerical Lanczos calculations. By adding the temperature to the model, the magnetic entanglement remains stable up to a critical temperature, Tc. Our results show that entanglement spreads step by step to farther neighbors in the spin chain by reducing temperature. At first, the 1N spins are entangled and then further neighbors will be entangled respectively. Tc depends on the value of the magnetic field and will be maximized at the quantum critical field.

  6. Heisenberg antiferromagnetic chain with multiple spin 1/2 particles of different flavors per site

    NASA Astrophysics Data System (ADS)

    Duki, Solomon F.; Yu, Yi-Kuo

    Motivated by the discoveries of quasi-1D magnetic systems, we studied a quantum mechanical spin lattice system consisting of a one-dimensional antiferromagnetic Heisenberg chain. In this system we considered M spin 1/2 particles of different flavors per site, and the low-lying states, ground state included, of the Hamiltonian was solved numerically using the exact diagonalization method for finite cluster sizes. We have also obtained the corresponding solutions for systems of the same chain length but with one spin M/2 particle per site. The low energy spectra of both systems are then compared. For M = 2 and M =3, our result shows that the two spin chain systems (one spin M/2 per site vs. M spin 1/2 of different flavors per site) have the same excitation spectra at low energy and the number of overlapped states increases as the size of the cluster increases. The observed overlap also indicates that low energy excitations of the M flavored spin 1/2 chain system selects the high spin states, effectively satisfying the Hund's Rule even though the system does not possess the orbital angular momentum. This work was supported by the Intramural Research Program of the National Library of Medicine at the National Institutes of Health.

  7. Spin-1 Heisenberg ferromagnet using pair approximation method

    NASA Astrophysics Data System (ADS)

    Mert, Murat; Kılıç, Ahmet; Mert, Gülistan

    2016-06-01

    Thermodynamic properties for Heisenberg ferromagnet with spin-1 on the simple cubic lattice have been calculated using pair approximation method. We introduce the single-ion anisotropy and the next-nearest-neighbor exchange interaction. We found that for negative single-ion anisotropy parameter, the internal energy is positive and heat capacity has two peaks.

  8. Magnetic properties of two-dimensional charged spin-1 Bose gases

    NASA Astrophysics Data System (ADS)

    Chen, Yingxue; Qin, Jihong; Gu, Qiang

    2014-01-01

    Within the mean-field theory, we investigate the magnetic properties of a charged spin-1 Bose gas in two dimensions. In this system the diamagnetism competes with paramagnetism, where the Landé factor g is introduced to describe the strength of the paramagnetic effect. The system presents a crossover from diamagnetism to paramagnetism with the increasing of the Landé factor. gc denotes the critical value of the Landé factor. We get the same value of gc both in the low temperature and strong magnetic field limit. Our results also show that in very weak magnetic field no condensation happens in the two-dimensional charged spin-1 Bose gas.

  9. Evolution Equation for a Joint Tomographic Probability Distribution of Spin-1 Particles

    NASA Astrophysics Data System (ADS)

    Korennoy, Ya. A.; Man'ko, V. I.

    2016-07-01

    The nine-component positive vector optical tomographic probability portrait of quantum state of spin-1 particles containing full spatial and spin information about the state without redundancy is constructed. Also the suggested approach is expanded to symplectic tomography representation and to representations with quasidistributions like Wigner function, Husimi Q-function, and Glauber-Sudarshan P-function. The evolution equations for constructed vector optical and symplectic tomograms and vector quasidistributions for arbitrary Hamiltonian are found. The evolution equations are also obtained in special case of the quantum system of charged spin-1 particle in arbitrary electro-magnetic field, which are analogs of non-relativistic Proca equation in appropriate representations. The generalization of proposed approach to the cases of arbitrary spin is discussed. The possibility of formulation of quantum mechanics of the systems with spins in terms of joint probability distributions without the use of wave functions or density matrices is explicitly demonstrated.

  10. Spin-Thermodynamics of Ultra-Cold Spin-1 Atoms

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Yao, D. X.; Bao, C. G.

    2015-08-01

    The spin-thermodynamics of a -body spin-1 condensate containing only the spin-degrees of freedom is studied via a theory in which , the total spin and its Z-component are exactly conserved. The magnetic field is considered as zero at first. Then the effect of a residual is evaluated. A temperature is defined as below that all the spatial degrees of freedom can be considered as being frozen and, accordingly, a pure spin-system will emerge. Effort is made to evaluate . When goes up from zero, the internal energy and the entropy experience sharp changes in two narrow domains of surrounding two turning temperatures and , the latter is higher. When or , and remain unchanged. Whereas when , and . It was found that and originate from the gap (the energy difference between the ground state (g.s.) and the first excited state) and the width (the energy difference between the g.s. and the highest state without spatial excitation) of the spectra, respectively. Thus their appearance is a common feature in spin-thermodynamics. In fact, marks the lowest excitation of the spin-modes, while marks the maximization of the entropy in the spin-space. In particular, the T-dependent population density is defined so that the theory can be checked by experimental data. Two kinds of condensates are notable: (i) the strongly trapped systems with a very small , they can work as pure spin-systems at relatively higher temperature; (ii) the systems with a high magnetization (say, ), the dimensions of their spin-spaces are very low. Furthermore, a larger together with a large N (for Rb) or a large (for Na) will lead to a sufficiently large so that a real g.s. can be experimentally created at a higher temperature. The spin-thermodynamics would remain valid whenever the spatial modes decouple from the spin-modes. This can occur at a higher temperature as demonstrated in Pechkis et al. (Phys Rev Lett 111:025301, 2013).

  11. SU(3) quantum critical model emerging from a spin-1 topological phase

    NASA Astrophysics Data System (ADS)

    Rao, Wen-Jia; Zhu, Guo-Yi; Zhang, Guang-Ming

    2016-04-01

    Different from the spin-1 Haldane gapped phase, we propose an SO(3) spin-1 matrix product state (MPS), whose parent Hamiltonian includes three-site spin interactions. From the entanglement spectrum of a single block with l sites, an enlarged SU(3) symmetry is identified in the edge states, which are conjugate to each other for the l =even block but identical for the l =odd block. By blocking this state, the blocked MPS explicitly displays the SU(3) symmetry with two distinct structures. Under a symmetric bulk bipartition with a sufficient large block length l =even , the entanglement Hamiltonian (EH) of the reduced system characterizes a spontaneous dimerized phase with twofold degeneracy. However, for the block length l =odd , the corresponding EH represents an SU(3) quantum critical point with delocalized edge quasiparticles, and the critical field theory is described by the SU(3) level-1 Wess-Zumino-Witten conformal field theory.

  12. Efficiency of quantum energy teleportation within spin-1/2 particle pairs

    NASA Astrophysics Data System (ADS)

    Frey, Michael R.

    2016-03-01

    A protocol for quantum energy teleportation (QET) is known for a so-called minimal spin-1/2 particle pair model. We extend this protocol to explicitly admit quantum weak measurements at its first stage. The extended protocol is applied beyond the minimal model to spin-1/2 particle pairs whose Hamiltonians are of a general class characterized by orthogonal pairs of entangled eigenstates. The energy transfer efficiency of the extended QET protocol is derived for this setting, and we show that weaker measurement yields greater efficiency. In the minimal particle pair model, for example, the efficiency can be doubled by this means. We also show that the QET protocol's transfer efficiency never exceeds 100 %, supporting the understanding that quantum energy teleportation is, indeed, an energy transfer protocol, rather than a protocol for remotely catalyzing local extraction of system energy already present.

  13. Magnetic properties of a two-dimensional spin 1 easy axis Heisenberg antiferromagnet with competing interaction

    NASA Astrophysics Data System (ADS)

    Pires, Antonio; Sousa, Griffith

    2014-03-01

    The square lattice antiferromagnet with next and next nearest neighbor exchange interaction has been the subject of intense research in the last years. It can present the behavior of a frustrated system and can otherwise describe real materials. However, a large part of the work has been dedicated to spin 1/2 and done at zero temperature. A system with spin 1 is of interest because it can have a single ion anisotropy. To study these models simple approaches which yield an analytical description are very useful for practical purposes. Here we use a Modified Spin Wave theory, where corrections owing to spin wave interactions are taken into account self-consistently, to study the easy axis two dimensional spin 1 antiferromagnet with competing interaction and single ion anisotropy. We calculate the phase diagram at zero temperature, and several thermodynamic quantities such as the magnetization, the gap and the specific heat. Their relations with the temperature and anisotropy parameter are analyzed over the entire range of temperature. We have found a Neel and a collinear phase separated by a disordered phase. This disordered phase could be a candidate for a spin liquid. This work was partially supported by CNPQ, FAPEMIG and FAPEAM.

  14. Interaction-driven exotic quantum phases in spin-orbit-coupled spin-1 bosons

    NASA Astrophysics Data System (ADS)

    Pixley, J. H.; Natu, Stefan S.; Spielman, I. B.; Das Sarma, S.

    2016-02-01

    We study the interplay between large-spin, spin-orbit coupling, and superfluidity for bosons in a two-dimensional optical lattice, focusing on the spin-1 spin-orbit-coupled system recently realized at the Joint Quantum Institute [Campbell et al., arXiv:1501.05984]. We find a rich quantum phase diagram where, in addition to the conventional phases—superfluid and insulator—contained in the spin-1 Bose-Hubbard model, there are new lattice symmetry breaking phases. For weak interactions, the interplay between two length scales, the lattice momentum and the spin-orbit wave vector, induce a phase transition from a uniform superfluid to a phase where bosons simultaneously condense at the center and edge of the Brillouin zone at a nonzero spin-orbit strength. This state is characterized by spin-density-wave order, which arises from the spin-1 nature of the system. Interactions suppress spin-density-wave order, and favor a superfluid only at the Brillouin zone edge. This state has spatially oscillating mean-field order parameters, but a homogeneous density. We show that the spin-density-wave superfluid phase survives in a two-dimensional harmonic trap, and thus establish that our results are directly applicable to experiments on 87Rb,7Li, and 41K.

  15. Coherent spin mixing dynamics in a spin-1 atomic condensate

    SciTech Connect

    Zhang Wenxian; Chang, M.-S.; Chapman, M.S.; Zhou, D.L.; You, L.

    2005-07-15

    We study the coherent off-equilibrium spin mixing inside an atomic condensate. Using mean-field theory and adopting the single-spatial-mode approximation, the condensate spin dynamics is found to be well described by that of a nonrigid pendulum and displays a variety of periodic oscillations in an external magnetic field. Our results illuminate several recent experimental observations and provide critical insights into the observation of coherent interaction-driven oscillations in a spin-1 condensate.

  16. Topological paramagnetism in frustrated spin-1 Mott insulators

    NASA Astrophysics Data System (ADS)

    Wang, Chong; Nahum, Adam; Senthil, T.

    2015-05-01

    Time-reversal-protected three-dimensional (3D) topological paramagnets are magnetic analogs of the celebrated 3D topological insulators. Such paramagnets have a bulk gap and no exotic bulk excitations, but have non-trivial surface states protected by symmetry. We propose that frustrated spin-1 quantum magnets are a natural setting for realizing such states in three dimensions. We describe a physical picture of the ground-state wave function for such a spin-1 topological paramagnet in terms of loops of fluctuating Haldane chains with nontrivial linking phases. We illustrate some aspects of such loop gases with simple exactly solvable models. We also show how 3D topological paramagnets can be very naturally accessed within a slave particle description of a spin-1 magnet. Specifically, we construct slave-particle mean-field states which are naturally driven into the topological paramagnet upon including fluctuations. We propose bulk projected wave functions for the topological paramagnet based on this slave-particle description. An alternate slave-particle construction leads to a stable U (1 ) quantum spin liquid from which a topological paramagnet may be accessed by condensing the emergent magnetic monopole excitation of the spin liquid.

  17. Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3 Nanosheets.

    PubMed

    Weber, Daniel; Schoop, Leslie M; Duppel, Viola; Lippmann, Judith M; Nuss, Jürgen; Lotsch, Bettina V

    2016-06-01

    Spin 1/2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still in demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl3 into the first halide monolayers and the magnetic characterization of the spin 1/2 honeycomb arrangement of turbostratically stacked RuCl3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1/2 state by electron injection into the layers. The restacked, macroscopic pellets of RuCl3 layers lack symmetry along the stacking direction. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at TN = 7 K if the field is aligned parallel to the ab-plane, while the magnetic properties differ from bulk α-RuCl3 if the field is aligned perpendicular to the ab-plane. The deliberate introduction of turbostratic disorder to manipulate the magnetic properties of RuCl3 is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model. PMID:27176463

  18. Core-shell structured square mixed-spin 1 and 1/2 Ising nanowire on the Bethe lattice

    NASA Astrophysics Data System (ADS)

    Albayrak, Erhan

    2016-03-01

    The square Ising nanowire is constructed by adding square nanoparticles consisting of one spin-1 at the center and four spin-1/2 at the corners along a straight line in both directions. Therefore, this system may be taken to be equivalent to Bethe lattice of coordination number two and can be solved in terms of the exact recursion relations. This core-shell structured model is studied by using ferromagnetic exchange interactions between surface spins (Js), between core spins (Jc) and between surface and core spins (Jsc) and crystal field interaction (D) at the sites of spin-1. The phase diagrams of the model are obtained in terms of these parameters by varying the temperature on the possible planes. It is found that the model presents both second- and first-order phase transitions and tricritical points for the appropriate values of these parameters.

  19. Coordinate Bethe ansatz computation for low temperature behavior of a triangular lattice of a spin-1 Heisenberg antiferromagnet

    SciTech Connect

    Shuaibu, A.; Rahman, M. M.

    2014-03-05

    We study the low temperature behavior of a triangular lattice quantum spin-1 Heisenberg antiferromagnet with single-site anisotropy by using coordinate Bethe ansatz method. We compute the standard two-particle Hermitian Hamiltonian, and obtain the eigenfunctions and eigenvalue of the system. The obtained results show a number of advantages in comparison with many results.

  20. Heisenberg-scaled magnetometer with dipolar spin-1 condensates

    NASA Astrophysics Data System (ADS)

    Xing, Haijun; Wang, Anbang; Tan, Qing-Shou; Zhang, Wenxian; Yi, Su

    2016-04-01

    We propose a scheme to realize a Heisenberg-scaled magnetometer using dipolar spin-1 condensates. The input state of magnetometer is prepared by slowly sweeping a transverse magnetic field to zero, which yields a highly entangled spin state of N atoms. We show that this process is protected by a parity symmetry such that the state preparation time is within the reach of the current experiment. We also propose a parity measurement with a Stern-Gerlach apparatus which is shown to approach the optimal measurement in the large atom number limit. Finally, we show that the phase estimation sensitivity of the proposed scheme roughly follows the Heisenberg scaling.

  1. Emergent SU(3) Symmetry in Random Spin-1 Chains.

    PubMed

    Quito, V L; Hoyos, José A; Miranda, E

    2015-10-16

    We show that generic SU(2)-invariant random spin-1 chains have phases with an emergent SU(3) symmetry. We map out the full zero-temperature phase diagram and identify two different phases: (i) a conventional random-singlet phase (RSP) of strongly bound spin pairs [SU(3) "mesons"] and (ii) an unconventional RSP of bound SU(3) "baryons," which are formed, in the great majority, by spin trios located at random positions. The emergent SU(3) symmetry dictates that susceptibilities and correlation functions of both dipolar and quadrupolar spin operators have the same asymptotic behavior. PMID:26550897

  2. Universal Coarsening Dynamics of a Quenched Ferromagnetic Spin-1 Condensate

    NASA Astrophysics Data System (ADS)

    Williamson, Lewis A.; Blakie, P. B.

    2016-01-01

    We demonstrate that a quasi-two-dimensional spin-1 condensate quenched to a ferromagnetic phase undergoes universal coarsening in its late time dynamics. The quench can be implemented by a sudden change in the applied magnetic field and, depending on the final value, the ferromagnetic phase has easy-axis (Ising) or easy-plane (X Y ) symmetry, with different dynamical critical exponents. Our results for the easy-plane phase reveal a fractal domain structure and the crucial role of polar-core spin vortices in the coarsening dynamics.

  3. On mono-W signatures in spin-1 simplified models

    NASA Astrophysics Data System (ADS)

    Haisch, Ulrich; Kahlhoefer, Felix; Tait, Tim M. P.

    2016-09-01

    The potential sensitivity to isospin-breaking effects makes LHC searches for mono-W signatures promising probes of the coupling structure between the Standard Model and dark matter. It has been shown, however, that the strong sensitivity of the mono-W channel to the relative magnitude and sign of the up-type and down-type quark couplings to dark matter is an artifact of unitarity violation. We provide three different solutions to this mono-W problem in the context of spin-1 simplified models and briefly discuss the impact that our findings have on the prospects of mono-W searches at future LHC runs.

  4. Electric and magnetic polarizabilities of pointlike spin-1/2 particles

    NASA Astrophysics Data System (ADS)

    Silenko, A. J.

    2014-11-01

    The electric and magnetic polarizabilities of pointlike spin-1/2 particles with an anomalous magnetic moment (AMM) are calculated by the transformation of an initial Hamiltonian into the Foldy-Wouthuysen (FW) representation. Corresponding results for spin-1/2 and spin-1 particles are compared.

  5. Quantum correlations and coherence in spin-1 Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Malvezzi, A. L.; Karpat, G.; ćakmak, B.; Fanchini, F. F.; Debarba, T.; Vianna, R. O.

    2016-05-01

    We explore quantum and classical correlations along with coherence in the ground states of spin-1 Heisenberg chains, namely the one-dimensional XXZ model and the one-dimensional bilinear biquadratic model, with the techniques of density matrix renormalization group theory. Exploiting the tools of quantum information theory, that is, by studying quantum discord, quantum mutual information, and three recently introduced coherence measures in the reduced density matrix of two nearest neighbor spins in the bulk, we investigate the quantum phase transitions and special symmetry points in these models. We point out the relative strengths and weaknesses of correlation and coherence measures as figures of merit to witness the quantum phase transitions and symmetry points in the considered spin-1 Heisenberg chains. In particular, we demonstrate that, as none of the studied measures can detect the infinite-order Kosterlitz-Thouless transition in the XXZ model, they appear to be able to signal the existence of the same type of transition in the biliear biquadratic model. However, we argue that what is actually detected by the measures here is the SU(3) symmetry point of the model rather than the infinite-order quantum phase transition. Moreover, we show in the XXZ model that examining even single site coherence can be sufficient to spotlight the second-order phase transition and the SU(2) symmetry point.

  6. Magnetic-field-induced dynamical instabilities in an antiferromagnetic spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Pu, Zhengguo; Zhang, Jun; Yi, Su; Wang, Dajun; Zhang, Wenxian

    2016-05-01

    We theoretically investigate four types of dynamical instability, in particular the periodic and oscillatory type IO, in an antiferromagnetic spin-1 Bose-Einstein condensate in a nonzero magnetic field, by employing the coupled-mode theory and numerical method. This is in sharp contrast to the dynamical stability of the same system in zero field. Remarkably, a pattern transition from a periodic dynamical instability IO to a uniform one IIIO occurs at a critical magnetic field. All four types of dynamical instability and the pattern transition are ready to be detected in 23Na condensates within the availability of the current experimental techniques.

  7. LETTER TO THE EDITOR: Parity-broken ground state for the spin-1 pyrochlore antiferromagnet

    NASA Astrophysics Data System (ADS)

    Yamashita, Yasufumi; Ueda, Kazuo; Sigrist, Manfred

    2001-12-01

    The ground-state properties of the spin-1 pyrochlore antiferromagnet are studied by applying the VBS-like tetrahedron-unit decomposition to the original spin system. The symmetrization required on every vertex is taken into account by introducing a ferromagnetic coupling. The pairwise effective Hamiltonian between the adjacent tetrahedrons is obtained by considering the next nearest neighbour and the third neighbour exchange interactions. We find that the transverse component of the spin chirality exhibits a long-range order, breaking the parity symmetry of the tetrahedral group, while the chirality itself is not broken.

  8. Group velocity of extraordinary waves in superdense magnetized quantum plasma with spin-1/2 effects

    SciTech Connect

    Li Chunhua; Ren Haijun; Yang Weihong; Wu Zhengwei; Chu, Paul K.

    2012-12-15

    Based on the one component plasma model, a new dispersion relation and group velocity of elliptically polarized extraordinary electromagnetic waves in a superdense quantum magnetoplasma are derived. The group velocity of the extraordinary wave is modified due to the quantum forces and magnetization effects within a certain range of wave numbers. It means that the quantum spin-1/2 effects can reduce the transport of energy in such quantum plasma systems. Our work should be of relevance for the dense astrophysical environments and the condensed matter physics.

  9. Constant-coupling approximation study of spin-1 Blume-Capel model

    NASA Astrophysics Data System (ADS)

    Ekiz, Cesur

    2016-07-01

    In this paper, the equilibrium properties of spin-1 Blume-Capel model are studied by using constant-coupling approximation. The formulation is based on developed by Obokata and Oguchi method, where the dependence upon the thermodynamic variables is determined by a set of two-couple nonlinear algebraic equations. The temperature dependence of the order parameters is examined to characterize the nature (continuous or discontinuous) of the phase transitions and to obtain the metastable and unstable branches. For the system, the effect of the uniaxial anisotropy parameter to phase transitions and stable, metastable and unstable states is discussed on the simple cubic lattice with the coordination number z = 6.

  10. A theoretical study of the hysteresis behaviors of a transverse spin-1/2 Ising nanocube

    NASA Astrophysics Data System (ADS)

    El Hamri, M.; Bouhou, S.; Essaoudi, I.; Ainane, A.; Ahuja, R.

    2016-09-01

    The applied magnetic field dependencies of the surface shell, core and total magnetizations of a transverse spin-1/2 Ising nanocube are investigated within the effective-field theory with correlations, based on the probability distribution technique, for both ferro- and antiferromagnetic exchange interactions. We have found that interfacial coupling has a strong effect on the shape and the number of hysteresis loops and also on the coercive field and remanent magnetization behaviors. Furthermore, when the temperature exceeds a critical one, the coercivities of the core, the surface shell and the system become zero.

  11. Evidence for a spin-1 particle produced by two photons

    NASA Astrophysics Data System (ADS)

    Aihara, H.; Alston-Garnjost, M.; Avery, R. E.; Barbaro-Galtieri, A.; Barker, A. R.; Barnes, A. V.; Barnett, B. A.; Bauer, D. A.; Bengtsson, H.-U.; Bintinger, D. L.; Bobbink, G. J.; Bolognese, T. S.; Bross, A. D.; Buchanan, C. D.; Buijs, A.; Caldwell, D. O.; Clark, A. R.; Cowan, G. D.; Crane, D. A.; Dahl, O. I.; Derby, K. A.; Eastman, J. J.; Eberhard, P. H.; Edberg, T. K.; Eisner, A. M.; Enomoto, R.; Erné, F. C.; Fujii, T.; Gary, J. W.; Gorn, W.; Hauptman, J. M.; Hofmann, W.; Huth, J. E.; Hylen, J.; Kamae, T.; Kaye, H. S.; Kees, K. H.; Kenney, R. W.; Kerth, L. T.; Ko, Winston; Koda, R. I.; Kofler, R. R.; Kwong, K. K.; Lander, R. L.; Langeveld, W. G.; Layter, J. G.; Linde, F. L.; Lindsey, C. S.; Loken, S. C.; Lu, A.; Lu, X.-Q.; Lynch, G. R.; Madaras, R. J.; Maeshima, K.; Magnuson, B. D.; Marx, J. N.; Masek, G. E.; Mathis, L. G.; Matthews, J. A.; Maxfield, S. J.; Melnikoff, S. O.; Miller, E. S.; Moses, W.; McNeil, R. R.; Nemethy, P.; Nygren, D. R.; Oddone, P. J.; Paar, H. P.; Park, D. A.; Park, S. K.; Pellett, D. E.; Pripstein, M.; Ronan, M. T.; Ross, R. R.; Rouse, F. R.; Schwitkis, K. A.; Sens, J. C.; Shapiro, G.; Shapiro, M. D.; Shen, B. C.; Slater, W. E.; Smith, J. R.; Steinman, J. S.; Stevenson, M. L.; Stork, D. H.; Strauss, M. G.; Sullivan, M. K.; Takahashi, T.; Thompson, J. R.; Toge, N.; Toutounchi, S.; van Tyen, R.; van Uitert, B.; Vandalen, G. J.; van Daalen Wetters, R. F.; Vernon, W.; Wagner, W.; Wang, E. M.; Wang, Y. X.; Wayne, M. R.; Wenzel, W. A.; White, J. T.; Williams, M. C.; Wolf, Z. R.; Yamamoto, H.; Yellin, S. J.; Zeitlin, C.; Zhang, W.-M.

    1986-11-01

    Two-photon production of K08K+/-π-/+ states has been studied by the TPC/Two-Gamma experiment at the SLAC storage ring PEP. A resonance of mass 1.42 GeV was seen when one of the photons was quite virtual but not when both photons were nearly real. Production of a spin-1 meson, which cannot be made by two real photons, would fit these observations. The Q2 dependence of the data in the resonance region agrees with this spin assignment and is incompatible with a spin-0 hypothesis. The mass and width of the resonance are similar to those of the E meson, which has been assigned JP=0- and JP=1+ by different experiments.

  12. Quantum phase transitions in spin-1 compass chains

    NASA Astrophysics Data System (ADS)

    Liu, Guang-Hua; Kong, Long-Juan; You, Wen-Long

    2015-11-01

    The ground-state phase diagram and quantum phase transitions (QPTs) in a spin-1 compass chain are investigated by the infinite time-evolving block decimation (iTEBD) method. Various phases are discerned by energy densities, spin correlations and entanglement entropy. A generalized string correlator is found to be capable of describing the nonlocal string order in the disordered phase. Furthermore, in the noncritical disordered phase, the spin-spin correlations are found to decay exponentially. Except for a multicritical point ( J 1 = 0, J 2 = 0), the QPTs are determined to have second-order characters. In addition, the central charges on these critical phase boundaries are determined to be c = 1 / 2, therefore these QPTs belong to the Ising universality class.

  13. Spin waves in a spin-1 normal Bose gas

    SciTech Connect

    Natu, Stefan S.; Mueller, Erich J.

    2010-05-15

    We present a theory of spin waves in a noncondensed gas of spin-1 bosons and provide both analytic calculations of the linear theory and full numerical simulations of the nonlinear response. We highlight the role of spin-dependent contact interactions in the dynamics of a thermal gas. Although these interactions are small compared to the thermal energy, they set the scale for low-energy, long-wavelength spin waves. In particular, we find that the polar state of {sup 87}Rb is unstable to collisional mixing of magnetic sublevels even in the normal state. We augment our analytic calculations by providing full numerical simulations of a trapped gas, explicitly demonstrating this instability. Further, we show that for strong antiferromagnetic interactions, the polar gas is unstable. Finally, we explore coherent population dynamics in a collisionless transversely polarized gas.

  14. Emulating quantum state transfer through a spin-1 chain on a one-dimensional lattice of superconducting qutrits

    NASA Astrophysics Data System (ADS)

    Ghosh, Joydip

    2014-12-01

    Spin-1 systems, in comparison to spin-1/2 systems, offer a better security for encoding and transferring quantum information, primarily due to their larger Hilbert spaces. Superconducting artificial atoms possess multiple energy levels, thereby being capable of emulating higher-spin systems. Here I consider a one-dimensional lattice of nearest-neighbor-coupled superconducting transmon systems, and devise a scheme to transfer an arbitrary qutrit state (a state encoded in a three-level quantum system) across the chain. I assume adjustable couplings between adjacent transmons, derive an analytic constraint for the control pulse, and show how to satisfy the constraint to achieve a high-fidelity state transfer under current experimental conditions. My protocol thus enables enhanced quantum communication and information processing with promising superconducting qutrits.

  15. Spin-1 atoms in optical superlattices: Single-atom tunneling and entanglement

    SciTech Connect

    Wagner, Andreas; Bruder, Christoph; Demler, Eugene

    2011-12-15

    We examine spinor Bose-Einstein condensates in optical superlattices theoretically using a Bose-Hubbard Hamiltonian that takes spin effects into account. Assuming that a small number of spin-1 bosons is loaded in an optical potential, we study single-particle tunneling that occurs when one lattice site is ramped up relative to a neighboring site. Spin-dependent effects modify the tunneling events in a qualitative and quantitative way. Depending on the asymmetry of the double well, different types of magnetic order occur, making the system of spin-1 bosons in an optical superlattice a model for mesoscopic magnetism. We use a double-well potential as a unit cell for a one-dimensional superlattice. Homogeneous and inhomogeneous magnetic fields are applied, and the effects of the linear and the quadratic Zeeman shifts are examined. We also investigate the bipartite entanglement between the sites and construct states of maximal entanglement. The entanglement in our system is due to both orbital and spin degrees of freedom. We calculate the contribution of orbital and spin entanglements and show that the sum of these two terms gives a lower bound for the total entanglement.

  16. Energy as Entanglement Witness in Bilinear-Biquadratic Spin-1 Chain

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Wang, An-Min; Zhao, Ning-Bo; Su, Xiao-Qiang; Zhu, Ren-Gui

    2006-10-01

    Energy is introduced as an entanglement witness to describe the entanglement property of a quantum system. The thermal equilibrium system is guaranteed to be entangled when system is cooled down below the entanglement temperature TE. By virtue of this concept we exploit the minimum separable state energy and entanglement temperature TE of the bilinear-biquadratic antiferromagnetic spin-1 chain model. We numerically calculate TE for arbitrary values of the strength of biquadratic exchange interaction Q up to N = 7. We find TE decreases with Q for fixed N when Q is between -3 and 1/3 (J = 1). In this regime TE also decreases with N for fixed Q and varies slowly for large N. While the thermal system is always entangled when Q is smaller than -3.

  17. Raman-dressed spin-1 spin-orbit-coupled quantum gas

    NASA Astrophysics Data System (ADS)

    Lan, Zhihao; Öhberg, Patrik

    2014-02-01

    The recently realized spin-orbit-coupled quantum gases [Lin et al., Nature (London) 471, 83 (2011), 10.1038/nature09887; Wang et al., Phys. Rev. Lett. 109, 095301 (2012), 10.1103/PhysRevLett.109.095301; Cheuk et al., Phys. Rev. Lett. 109, 095302 (2012), 10.1103/PhysRevLett.109.095302] mark a breakthrough in the cold atom community. In these experiments, two hyperfine states are selected from a hyperfine manifold to mimic a pseudospin-1/2 spin-orbit-coupled system by the method of Raman dressing, which is applicable to both bosonic and fermionic gases. In this paper, we show that the method used in these experiments can be generalized to create any large pseudospin spin-orbit-coupled gas if more hyperfine states are coupled equally by the Raman lasers. As an example, we study, in detail, a quantum gas with three hyperfine states coupled by the Raman lasers and show, when the state-dependent energy shifts of the three states are comparable, triple-degenerate minima will appear at the bottom of the band dispersions, thus, realizing a spin-1 spin-orbit-coupled quantum gas. A novel feature of this three-minima regime is that there can be two different kinds of stripe phases with different wavelengths, which has an interesting connection to the ferromagnetic and polar phases of spin-1 spinor Bose-Einstein condensates without spin-orbit coupling.

  18. Relativistic solutions for the spin-1 particles in the two-dimensional Smorodinsky–Winternitz potential

    SciTech Connect

    Bahar, M.K.; Yasuk, F.

    2014-05-15

    In this study, we investigate relativistic spin-1 particles in the V(x,y)=(ω{sub 0}{sup 2}/2)(x{sup 2}+y{sup 2})+k{sub 1}/x{sup 2}+k{sub 2}/y{sup 2} type of Smorodinsky–Winternitz potentials. In the first case, since this Smorodinsky–Winternitz potential has two dimensions, the system was transformed into polar coordinates from Cartesian coordinates. By using Duffin–Kemmer–Petiau formalism with the non-central Smorodinsky–Winternitz potential in two dimensions, the exact bound state energy eigenvalues and corresponding eigenfunctions were determined within the framework of the asymptotic iteration method. Bound state eigenfunctions were obtained in terms of confluent hypergeometric functions. -- Highlights: •We introduce formalism of the DKP equation in two dimensions. •The DKP equation with S–W potential is considered for spin-1 particles. •In order to solve the DKP equation, we explain the asymptotic iteration method (AIM). •Bound state energy eigenvalues and eigenfunctions are obtained by using AIM.

  19. Explicit expressions of quantum mechanical rotation operators for spins 1 to 2

    NASA Astrophysics Data System (ADS)

    Kocakoç, Mehpeyker; Tapramaz, Recep

    2016-03-01

    Quantum mechanical rotation operators are the subject of quantum mechanics, mathematics and pulsed magnetic resonance spectroscopies, namely NMR, EPR and ENDOR. They are also necessary for spin based quantum information systems. The rotation operators of spin 1/2 are well known and can be found in related textbooks. But rotation operators of other spins greater than 1/2 can be found numerically by evaluating the series expansions of exponential operator obtained from Schrödinger equation, or by evaluating Wigner-d formula or by evaluating recently established expressions in polynomial forms discussed in the text. In this work, explicit symbolic expressions of x, y and z components of rotation operators for spins 1 to 2 are worked out by evaluating series expansion of exponential operator for each element of operators and utilizing linear curve fitting process. The procedures gave out exact expressions of each element of the rotation operators. The operators of spins greater than 2 are under study and will be published in a separate paper.

  20. Complete positivity of a spin-1/2 master equation with memory

    SciTech Connect

    Maniscalco, Sabrina

    2007-06-15

    We study a non-Markovian spin-1/2 master equation with exponential memory. We derive the conditions under which the dynamical map describing the reduced system dynamics is completely positive, i.e., the nonunitary evolution of the system is compatible with a description in terms of a closed total spin-reservoir system. Our results show that for a zero-T reservoir, the dynamical map of the model here considered is never completely positive. For moderate- and high-T reservoirs, on the contrary, positivity is a necessary and sufficient condition for complete positivity. We also consider the Shabani-Lidar master equation recently introduced [A. Shabani and D.A. Lidar, Phys. Rev. A 71, 020101(R) (2005)] and we demonstrate that such a master equation is always completely positive.

  1. Theory of the spin-1 bosonic liquid metal - Equilibrium properties of liquid metallic deuterium

    NASA Technical Reports Server (NTRS)

    Oliva, J.; Ashcroft, N. W.

    1984-01-01

    The theory of a two-component quantum fluid comprised of spin-1/2 fermions and nonzero spin bosons is examined. This system is of interest because it embodies a possible quantum liquid metallic phase of highly compressed deuterium. Bose condensation is assumed present and the two cases of nuclear-spin-polarized and -unpolarized systems are considered. A significant feature in the unpolarized case is the presence of a nonmagnetic mode with quadratic dispersion owing its existence to nonzero boson spin. The physical character of this mode is examined in detail within a Bogoliubov approach. The specific heat, bulk modulus, spin susceptibility, and thermal expansion are all determined. Striking contrasts in the specific heats and thermal-expansion coefficients of the liquid and corresponding normal solid metallic phase are predicted.

  2. The histone code reader SPIN1 controls RET signaling in liposarcoma

    PubMed Central

    Franz, Henriette; Greschik, Holger; Willmann, Dominica; Ozretić, Luka; Jilg, Cordula Annette; Wardelmann, Eva; Jung, Manfred; Buettner, Reinhard; Schüle, Roland

    2015-01-01

    The histone code reader Spindlin1 (SPIN1) has been implicated in tumorigenesis and tumor growth, but the underlying molecular mechanisms remain poorly understood. Here, we show that reducing SPIN1 levels strongly impairs proliferation and increases apoptosis of liposarcoma cells in vitro and in xenograft mouse models. Combining signaling pathway, genome-wide chromatin binding, and transcriptome analyses, we found that SPIN1 directly enhances expression of GDNF, an activator of the RET signaling pathway, in cooperation with the transcription factor MAZ. Accordingly, knockdown of SPIN1 or MAZ results in reduced levels of GDNF and activated RET explaining diminished liposarcoma cell proliferation and survival. In line with these observations, levels of SPIN1, GDNF, activated RET, and MAZ are increased in human liposarcoma compared to normal adipose tissue or lipoma. Importantly, a mutation of SPIN1 within the reader domain interfering with chromatin binding reduces liposarcoma cell proliferation and survival. Together, our data describe a molecular mechanism for SPIN1 function in liposarcoma and suggest that targeting SPIN1 chromatin association with small molecule inhibitors may represent a novel therapeutic strategy. PMID:25749382

  3. Stripe phase and double-roton excitations in interacting spin-orbit-coupled spin-1 Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Sun, Kuei; Qu, Chunlei; Xu, Yong; Zhang, Yongping; Zhang, Chuanwei

    Spin-orbit (SO) coupling plays a major role in many important phenomena in condensed matter physics. However, the SO coupling physics in high-spin systems, especially with superfluids, has not been well explored because of the spin half of electrons in solids. In this context, the recent experimental realization of spin-orbit coupling in spin-1 Bose-Einstein condensates (BECs) has opened a completely new avenue for exploring SO-coupled high-spin superfluids. Nevertheless, the experiment has only revealed the single-particle physics of the system. Here, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 BECs in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting two modulating patterns. We characterize the phase transitions between different phases using the spin-tensor density as well as the collective dipole motion of the BEC. We show that there exists a new type of double maxon-roton structure in the Bogoliubov-excitation spectrum, attributing to the three band minima of the SO-coupled spin-1 BEC. Our work could motivate further theoretical and experimental study along this direction.

  4. Fast and slow magnetosonic waves in two-dimensional spin-1/2 quantum plasma

    SciTech Connect

    Mushtaq, A.; Vladimirov, S. V.

    2010-10-15

    Using the spin-1/2 resistive quantum magnetohydrodynamics model, linear and nonlinear relations for slow and fast magnetosonic modes are derived. Spin effects are incorporated via spin force and macroscopic spin magnetization current. The plasma resistivity is shown to play a role of dissipation in the system. With the aid of tanh method the traveling wave solution of Kadomstev-Petviashvili-Burgers is obtained. The solution shows a general shock wave profile superposed by a perturbative solitary-wave contribution. The dynamics of fast and slow magnetosonic shock and soliton, respectively, in the presence and absence of dissipation is investigated with respect to electron spin magnetization, quantum diffraction, and plasma statistic. It is found that results obtained from the spin quantum plasmas differ significantly from the nonspin quantum plasmas. The relevance of the present work to dense astrophysical plasmas such as pulsar magnetosphere is pointed out.

  5. Stability of nonstationary states of spin-1 Bose-Einstein condensates

    SciTech Connect

    Maekelae, H.; Lundh, E.; Johansson, M.; Zelan, M.

    2011-10-15

    The stability of nonstationary states of homogeneous spin-1 Bose-Einstein condensates is studied by performing Bogoliubov analysis in a frame of reference where the state is stationary. In particular, the effect of an external magnetic field is examined. It is found that a nonzero magnetic field introduces instability in a {sup 23}Na condensate. The wavelengths of this instability can be controlled by tuning the strength of the magnetic field. In a {sup 87}Rb condensate this instability is present already at zero magnetic field. Furthermore, an analytical bound for the size of a stable condensate is found, and a condition for the validity of the single-mode approximation is presented. Realization of the system in a toroidal trap is discussed, and the full time development is simulated.

  6. Symmetry-protected topological phases and transition in a frustrated spin-1/2 XXZ chain

    NASA Astrophysics Data System (ADS)

    Ueda, Hiroshi; Onoda, Shigeki

    2014-12-01

    A frustrated spin-1/2 XXZ zigzag chain relevant to Rb2Cu2Mo3O12 is revisited in the light of symmetry-protected topological (SPT) phases. Using a density-matrix renormalization group method for infinite systems, we identify projective representations for four distinct time-reversal invariant SPT phases; two parity-symmetric dimer phases near the Heisenberg and XX limits and two parity-broken vector-chiral (VC) dimer phases in between. A small bond alternation in the nearest-neighbor ferromagnetic exchange coupling induces a direct SPT transition between the two distinct VC dimer phases. It is also found numerically that two Berezinskii-Kosterlitz-Thouless transitions, which occur from the gapless to the two distinct gapped VC phases in the case of δ =0 , meet each other in the case of δ >0 at a Gaussian criticality of the same Tomonaga-Luttinger parameter value as in the SU(2)-symmetric case.

  7. Dimerized phase and entanglement in the one-dimensional spin-1 bilinear biquadratic model

    NASA Astrophysics Data System (ADS)

    Chen, Ai Min; Su, Yao Heng; Wang, Honglei

    2015-10-01

    Dimerized phase and quantum entanglement are investigated in the one-dimensional spin-1 bilinear biquadratic model. Employing the infinite matrix product state representation, groundstate wavefunctions are numerically obtained by using the infinite time evolving block decimation method in the infinite lattice system. From a bipartite entanglement measure of the groundstates, i.e., von Neumann entropy, the phase transition points can be clearly extracted. Moreover, the even-bond and odd-bond von Neumann entropies show two different values in the spontaneous dimerized phase. It implies that the quantum entanglement can distinguish the two degenerate groundstates. Then, we define a dimer entropy in the spontaneous dimerized phase. Comparing to the dimer order parameter, the dimer entropy can play a role of a local order parameter to characterize the spontaneous dimerized phase.

  8. Critical Behavior of the Spin-1/2 Baxter-Wu Model: Entropic Sampling Simulations

    NASA Astrophysics Data System (ADS)

    Jorge, L. N.; Ferreira, L. S.; Leão, S. A.; Caparica, A. A.

    2016-08-01

    In this work, we use a refined entropic sampling technique based on the Wang-Landau method to study the spin- 1/2 Baxter-Wu model. We adopt the total magnetization as the order parameter and, as a result, do not divide the system into three sub-lattices. The static critical exponents were determined as α = 0.6697(54), β = 0.0813(67), γ = 1.1772(33), and ν = 0.6574(61). The estimate for the critical temperature was T c = 2.26924(2). We compare the present results with those obtained from other well-established approaches, and we find a very good closeness with the exact values, besides the high precision reached for the critical temperature.

  9. Magnetic phases of spin-1 spin–orbit-coupled Bose gases

    PubMed Central

    Campbell, D. L.; Price, R. M.; Putra, A.; Valdés-Curiel, A.; Trypogeorgos, D.; Spielman, I. B.

    2016-01-01

    Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin–orbit-coupled atomic Bose gas and the quantum phase transitions between these phases. We observe ferromagnetic and unpolarized phases, which are stabilized by spin–orbit coupling's explicit locking between spin and motion. These phases are separated by a critical curve containing both first- and second-order transitions joined at a tricritical point. The first-order transition, with observed width as small as h × 4 Hz, gives rise to long-lived metastable states. These measurements are all in agreement with theory. PMID:27025562

  10. Magnetic phases of spin-1 spin-orbit-coupled Bose gases.

    PubMed

    Campbell, D L; Price, R M; Putra, A; Valdés-Curiel, A; Trypogeorgos, D; Spielman, I B

    2016-01-01

    Phases of matter are characterized by order parameters describing the type and degree of order in a system. Here we experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin-orbit-coupled atomic Bose gas and the quantum phase transitions between these phases. We observe ferromagnetic and unpolarized phases, which are stabilized by spin-orbit coupling's explicit locking between spin and motion. These phases are separated by a critical curve containing both first- and second-order transitions joined at a tricritical point. The first-order transition, with observed width as small as h × 4 Hz, gives rise to long-lived metastable states. These measurements are all in agreement with theory. PMID:27025562

  11. Small and arbitrary shock structures in spin 1/2 magnetohydrodynamic quantum plasma

    SciTech Connect

    Sahu, Biswajit; Choudhury, Sourav; Sinha, Anjana

    2015-02-15

    The shock structures in spin-1/2 quantum plasma, in the presence of magnetic diffusivity, are studied in the framework of the quantum magnetohydrodynamic model. Linear dispersion relation for the system is carried out analytically, and the results are plotted numerically for several values of the plasma parameters. Numerical analysis for arbitrary amplitude waves is carried out, whereas for waves of small amplitude, the reductive perturbation technique is applied to obtain the Korteweg-de Vries-Burgers equation. Both the analyses are observed to give the same qualitative picture. Most importantly, the different plasma parameters are found to play significant roles in determining the nature of the shock waves. The parametric ranges for which monotonic shock and oscillatory shock solutions are observed, are found analytically.

  12. Frustration and multicriticality in the antiferromagnetic spin-1 chain

    NASA Astrophysics Data System (ADS)

    Pixley, J. H.; Shashi, Aditya; Nevidomskyy, Andriy H.

    2014-12-01

    The antiferromagnetic spin-1 chain has a venerable history and has been thought to be well understood. Here, we show that inclusion of both next-nearest-neighbor (α ) and biquadratic (β ) interactions results in a rich phase diagram with a multicritical point that has not been observed before. We study the problem using a combination of the density matrix renormalization group (DMRG), an analytic variational matrix product state wave function, and conformal field theory. For negative β <β* , we establish the existence of a spontaneously dimerized phase, separated from the Haldane phase by the critical line αc(β ) of second-order phase transitions. In the opposite regime, β >β* , the transition from the Haldane phase becomes first order into the next-nearest-neighbor (NNN) AKLT phase. Based on the field theoretical arguments and DMRG calculations, we find that these two regimes are separated by a multicritical point (β*,α*) of a different universality class, described by the level-4 SU(2) Wess-Zumino-Witten conformal theory. From the DMRG calculations, we estimate this multicritical point to lie in the range -0.2 <β*<-0.15 and 0.47 <α*<0.53 . We further find that the dimerized and NNN-AKLT phases are separated from each other by a line of first-order phase transitions that terminates at the multicritical point. We establish that transitions out of the Haldane phase into the dimer or NNN-AKLT phases are topological in nature and occur either with or without closing of the bulk gap, respectively. We also study short-range incommensurate-to-commensurate transitions in the resulting phase diagram. Inside the Haldane phase, we show the existence of two incommensurate crossovers: the Lifshitz transition and the disorder transition of the first kind, marking incommensurate correlations in momentum and real space, respectively. Notably, these crossover lines stretch across the entire (β ,α ) phase diagram, merging into a single incommensurate

  13. On the spin- 1/2 Aharonov–Bohm problem in conical space: Bound states, scattering and helicity nonconservation

    SciTech Connect

    Andrade, F.M.; Silva, E.O.; Pereira, M.

    2013-12-15

    In this work the bound state and scattering problems for a spin- 1/2 particle undergone to an Aharonov–Bohm potential in a conical space in the nonrelativistic limit are considered. The presence of a δ-function singularity, which comes from the Zeeman spin interaction with the magnetic flux tube, is addressed by the self-adjoint extension method. One of the advantages of the present approach is the determination of the self-adjoint extension parameter in terms of physics of the problem. Expressions for the energy bound states, phase-shift and S matrix are determined in terms of the self-adjoint extension parameter, which is explicitly determined in terms of the parameters of the problem. The relation between the bound state and zero modes and the failure of helicity conservation in the scattering problem and its relation with the gyromagnetic ratio g are discussed. Also, as an application, we consider the spin- 1/2 Aharonov–Bohm problem in conical space plus a two-dimensional isotropic harmonic oscillator. -- Highlights: •Planar dynamics of a spin- 1/2 neutral particle. •Bound state for Aharonov–Bohm systems. •Aharonov–Bohm scattering. •Helicity nonconservation. •Determination of the self-adjoint extension parameter.

  14. Exact many-body ground states of a spin-1 Bose gas in Tonks-Girardeau limit

    NASA Astrophysics Data System (ADS)

    Jen, Hsiang-Hua; Yip, Sungkit

    2016-05-01

    We investigate the many-body ground states of a one-dimensional spin-1 Bose gas in Tonks-Girardeau (TG) limit. It is known that in TG gas limit of scalar bosons, the system becomes fermionized that bosons do not penetrate each other, and their wavefunctions take the form of noninteracting fermions. For a spin-1 Bose gas with an infinite atom-atom interaction in a harmonic trap, we construct the many-body ground states from the ones of a noninteracting Fermi gas along with the spin degrees of freedom. With zero magnetic field in the sector of Sz = 0 and in the regime of spin-incoherent Luttinger liquid where we assume negligible | a2 -a0 | , the interaction energy becomes spin-independent, and the many-body wavefunctions of a spin-1 Bose gas is also SU(3) invariant. The many-body wavefunction can be derived by calculating the weightings of spin functions using the conjugacy class G of SN symmetric group for the number of atoms N. We then study the first-order correlation function of the density matrix, from which we extract its momentum distribution. Finite-temperature calculation of the wavefunction by including orbital excitations is also investigated to compare with the case of spinless bosons. Ministry of Science and Technology, Taiwan, under Grant Number MOST-101-2112-M-001-021-MY3.

  15. K e4 decay as a source of information about the σ-particle mass and about the nature of spin-1 mesons

    NASA Astrophysics Data System (ADS)

    Shabalin, E. P.

    2014-12-01

    Data on the form factors for K e4 decay make it possible to fix the value of a parameter that is not determined by the theory itself and which is contained in the Lagrangian for the system formed by 0+ and 0- mesons. This makes it possible to find the mass of the lightest σ meson: mσ = 663 MeV. As for the nature of spin-1 mesons, which also contribute to the form factors for K e4 decay, data on them give no way to interpret spin-1 mesons as gauge bosons of chiral theory

  16. Explicit demonstration of spinor character for a spin-1/2 nucleus via NMR interferometry

    NASA Technical Reports Server (NTRS)

    Stoll, M. E.; Vaughan, R. W.; Vega, A. J.

    1977-01-01

    The results of a nuclear-magnetic-resonance experiment are presented which directly demonstrate the spinor character of a spin-1/2 nucleus, C-13. The interferometric spectroscopic technique used and its potential applications are discussed.

  17. All exactly solvable U(1)-invariant quantum spin 1 chains from Hecke algebra

    SciTech Connect

    Alcarez, F.C. ); Koberle, R. ); Lima-Santos, A. )

    1992-12-10

    In this paper, the authors obtain all exactly integrable spin 1 quantum chains, which are U(1) invariant and satisfy the Hecke algebra. The authors present various generalizations for arbitrary spin S and discuss their solution via Bethe ansatz methods.

  18. Quasi-local conserved charges and spin transport in spin-1 integrable chains

    NASA Astrophysics Data System (ADS)

    Piroli, Lorenzo; Vernier, Eric

    2016-05-01

    We consider the integrable one-dimensional spin-1 chain defined by the Zamolodchikov–Fateev (ZF) Hamiltonian. The latter is parametrized, analogously to the XXZ spin-1/2 model, by a continuous anisotropy parameter and at the isotropic point coincides with the well-known spin-1 Babujian–Takhtajan Hamiltonian. Following a procedure recently developed for the XXZ model, we explicitly construct a continuous family of quasi-local conserved operators for the periodic spin-1 ZF chain. Our construction is valid for a dense set of commensurate values of the anisotropy parameter in the gapless regime where the isotropic point is excluded. Using the Mazur inequality, we show that, as for the XXZ model, these quasi-local charges are enough to prove that the high-temperature spin Drude weight is non-vanishing in the thermodynamic limit, thus establishing ballistic spin transport at high temperature.

  19. Adiabatic demagnetization of spin-1/2 antiferromagnetic J1-J2 Heisenberg hexagon

    NASA Astrophysics Data System (ADS)

    Deb, Moumita; Ghosh, Asim Kumar

    2016-05-01

    Analytic expressions of exact eigenvalues of the antiferromagnetic spin-1/2 J1-J2 Heisenberg hexagon in the presence of magnetic field have been obtained. Studies on the magnetization process, nature of isentrops and properties of magnetocaloric effect in terms of adiabatic demagnetization have been carried out. Magnetocaloric effect of the spin-1/2 Heisenberg hexagonal compound Cu3WO6 has been investigated with the help of these theoretical findings.

  20. Adiabatic demagnetization of the antiferromagnetic spin-1/2 Heisenberg hexagonal cluster

    NASA Astrophysics Data System (ADS)

    Deb, Moumita; Ghosh, Asim Kumar

    2016-05-01

    Exact analytic expressions of eigenvalues of the antiferromagnetic spin-1/2 Heisenberg hexagon in the presence of uniform magnetic field have been obtained. Magnetization process, nature of isentrops and properties of magneto caloric effect in terms of adiabatic demagnetization have been investigated. Theoretical results have been used to study the magneto caloric effect of the spin-1/2 Heisenberg hexagonal compound Cu3WO6.

  1. Spin-stripe phase in a frustrated zigzag spin-1/2 chain

    PubMed Central

    Pregelj, M.; Zorko, A.; Zaharko, O.; Nojiri, H.; Berger, H.; Chapon, L. C.; Arčon, D.

    2015-01-01

    Motifs of periodic modulations are encountered in a variety of natural systems, where at least two rival states are present. In strongly correlated electron systems, such behaviour has typically been associated with competition between short- and long-range interactions, for example, between exchange and dipole–dipole interactions in the case of ferromagnetic thin films. Here we show that spin-stripe textures may develop also in antiferromagnets, where long-range dipole–dipole magnetic interactions are absent. A comprehensive analysis of magnetic susceptibility, high-field magnetization, specific heat and neutron diffraction measurements unveils β-TeVO4 as a nearly perfect realization of a frustrated (zigzag) ferromagnetic spin-1/2 chain. Notably, a narrow spin-stripe phase develops at elevated magnetic fields due to weak frustrated short-range interchain exchange interactions, possibly assisted by the symmetry-allowed electric polarization. This concept provides an alternative route for the stripe formation in strongly correlated electron systems and may help understanding of other widespread, yet still elusive, stripe-related phenomena. PMID:26068618

  2. Quantum Phase Transitions in Alternating-Bond Mixed Diamond Chains with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'ichi; Suzuki, Hidenori

    2010-04-01

    We investigate the mixed diamond chain composed of spins 1 and 1/2 when the exchange interaction is alternatingly distorted. Depending on the strengths of frustration and distortion, this system has various ground states. Each ground state consists of an array of spin clusters separated by singlet dimers by virtue of an infinite number of local conservation laws. We determine the ground-state phase diagram by numerically analyzing each spin cluster. In particular, for strong distortions, we find an infinite series of quantum phase transitions using the cluster expansion method and conformal field theory. This leads to an infinite series of steps in the behavior of Curie constant and residual entropy.

  3. Thermal conductivity of anisotropic and frustrated spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Heidrich-Meisner, F.; Honecker, A.; Cabra, D. C.; Brenig, W.

    2002-10-01

    We analyze the thermal conductivity of anisotropic and frustrated spin-1/2 chains using analytical and numerical techniques. This includes mean-field theory based on the Jordan-Wigner transformation, bosonization, and exact diagonalization of systems with N<=18 sites. We present results for the temperature dependence of the zero-frequency weight of the conductivity for several values of the anisotropy Δ. In the gapless regime, we show that the mean-field theory compares well to known results and that the low-temperature limit is correctly described by bosonization. In the antiferromagnetic and ferromagnetic gapped regime, we analyze the temperature dependence of the thermal conductivity numerically. The convergence of the finite-size data is remarkably good in the ferromagnetic case. Finally, we apply our numerical method and mean-field theory to the frustrated chain where we find a good agreement of these two approaches on finite systems. Our numerical data do not yield evidence for a diverging thermal conductivity in the thermodynamic limit in case of the antiferromagnetic gapped regime of the frustrated chain.

  4. Properties of Haldane Excitations and Multiparticle States in the Antiferromagnetic Spin-1 Chain Compound CsNiCl3

    SciTech Connect

    Kenzelmann, M.; Cowley, R. A.; Buyers, W. J. L.; Tun, Z.; Coldea, Radu; Enderle, M.

    2002-01-01

    We report inelastic time-of-flight and triple-axis neutron scattering measurements of the excitation spectrum of the coupled antiferromagnetic spin-1 Heisenberg chain system CsNiCl{sub 3}. Measurements over a wide range of wave-vector transfers along the chain confirm that above T{sub N} CsNiCl{sub 3} is in a quantum-disordered phase with an energy gap in the excitation spectrum. The spin correlations fall off exponentially with increasing distance with a correlation length {zeta} = 4.0(2) sites at T = 6.2K. This is shorter than the correlation length for an antiferromagnetic spin-1 Heisenberg chain at this temperature, suggesting that the correlations perpendicular to the chain direction and associated with the interchain coupling lower the single-chain correlation length. A multiparticle continuum is observed in the quantum-disordered phase in the region in reciprocal space where antiferromagnetic fluctuations are strongest, extending in energy up to twice the maximum of the dispersion of the well-defined triplet excitations. We show that the continuum satisfies the Hohenberg-Brinkman sum rule. The dependence of the multiparticle continuum on the chain wave vector resembles that of the two-spinon continuum in antiferromagnetic spin-1/2 Heisenberg chains. This suggests the presence of spin-1/2 degrees of freedom in CsNiCl{sub 3} for T {approx}< 12 K, possibly caused by multiply frustrated interchain interactions.

  5. Coarsening and thermalization properties of a quenched ferromagnetic spin-1 condensate

    NASA Astrophysics Data System (ADS)

    Williamson, Lewis A.; Blakie, P. B.

    2016-08-01

    We examine the dynamics of a quasi-two-dimensional spin-1 condensate in which the quadratic Zeeman energy q is suddenly quenched to a value where the system has a ferromagnetic ground state. There are two distinct types of ferromagnetic phases, i.e., a range of q values where the magnetization prefers to be in the direction of the external field (easy axis) and a range of q values where it prefers to be transverse to the field (easy plane). We study the quench dynamics for a variety of q values and show that there is a single dynamic critical exponent to characterize the scale-invariant domain growth for each ferromagnetic phase. For both quenches we give simple analytic models that capture the essential scale-invariant dynamics and correctly predict the exponents. Because the order parameter for each phase is different, the natures of the domains and the relevant topological defects in each type of coarsening are also different. To explore these differences we characterize the fractal dimension of the domain walls and the relationship of polar-core spin vortices to the domains in the easy-plane phase. Finally, we consider how the energy liberated from the quench thermalizes in the easy-axis quench. We show that local equilibrium is established in the spin waves on moderate time scales, but continues to evolve as the domains anneal.

  6. Geometric phase of a spin-1 2 particle coupled to a quantum vector operator

    NASA Astrophysics Data System (ADS)

    Aguilar, Pedro; Chryssomalakos, Chryssomalis; Guzmán, Edgar

    2016-05-01

    We calculate Berry’s phase when the driving field, to which a spin-1 2 is coupled adiabatically, rather than the familiar classical magnetic field, is a quantum vector operator, of noncommuting, in general, components, e.g. the angular momentum of another particle, or another spin. The geometric phase of the entire system, spin plus “quantum driving field”, is first computed, and is then subdivided into the two subsystems, using the Schmidt decomposition of the total wave function — the resulting expression shows a marked, purely quantum effect, involving the commutator of the field components. We also compute the corresponding mean “classical” phase, involving a precessing magnetic field in the presence of noise, up to terms quadratic in the noise amplitude — the results are shown to be in excellent agreement with numerical simulations in the literature. Subtleties in the relation between the quantum and classical case are pointed out, while three concrete examples illustrate the scope and internal consistency of our treatment.

  7. Antiferromagnetic Heisenberg spin-1 chain: Magnetic susceptibility of the Haldane chain described using scaling

    NASA Astrophysics Data System (ADS)

    Souletie, Jean; Drillon, Marc; Rabu, Pierre; Pati, Swapan K.

    2004-08-01

    The phenomenological expression χT/(Ng2μB2/k)=C1nexp(-W1n/T)+C2nexp(-W2n/T) describes very accurately the temperature dependence of the magnetic susceptibility computed for antiferromagnetic rings of Heisenberg spins S=1 , whose size n is even and ranges from 6 to 20. This expression has been obtained through a strategy justified by scaling considerations together with finite size numerical calculations. For n large, the coefficients of the expression converge towards C1=0.125 , W1=0.451J , C2=0.564 , W2=1.793J ( J is the exchange constant), which are appropriate for describing the susceptibility of the spin-1 Haldane chain. The Curie constant, the paramagnetic Curie-Weiss temperature, the correlation length at T=0 and the Haldane gap are found to be closely related to these coefficients. With this expression, a very good description of the magnetic behavior of Y2BaNiO5 and of Ni(C2H8N2)2NO2ClO4 (NENP), the archetype of the Haldane gap systems, is achieved over the whole temperature range.

  8. Chiral and critical spin liquids in a spin-1/2 kagome antiferromagnet

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gong, S. S.; Sheng, D. N.

    2015-07-01

    The kagome spin-1/2 systems have attracted intensive attention in recent years as the primary candidate for hosting different gapped spin liquids (SLs). To uncover the nature of the novel quantum phase transition between the SL states, we study a minimum X Y model with the nearest-neighbor (NN) (Jx y), the second-NN, and the third-NN couplings (J2 x y=J3 x y=Jxy ' ). We identify the time-reversal-symmetry-broken chiral SL (CSL) with the turn on of a small perturbation Jxy '˜0.06 Jx y , which is fully characterized by the fractionally quantized topological Chern number and the conformal edge spectrum as the ν =1 /2 fractional quantum Hall state. Interestingly, the NN X Y model (Jxy '=0 ) is shown to be a critical SL state adjacent to the CSL, characterized by the gapless spin singlet and spin triplet excitations. The quantum phase transition from the CSL to the gapless critical SL is driven by the collapsing of the neutral (spin singlet) excitation gap. The effect of the NN spin-z coupling Jz is also studied, which leads to a quantum phase diagram with an extended regime for the gapless SL.

  9. Ground-state phase structure of the spin-1/2 anisotropic planar pyrochlore.

    PubMed

    Li, P H Y; Bishop, R F

    2015-09-30

    We study the zero-temperature ground-state (GS) properties of the spin-1/2 anisotropic planar pyrochlore, using the coupled cluster method (CCM) implemented to high orders of approximation. The system comprises a J 1-J 2 model on the checkerboard lattice, with isotropic Heisenberg interactions of strength J 1 between all nearest-neighbour pairs of spins on the square lattice, and of strength J 2 between half of the next-nearest-neighbour pairs (in the checkerboard pattern). We calculate results for the GS energy and average local GS on-site magnetization, using various antiferromagnetic classical ground states as CCM model states. We also give results for the susceptibility of one of these states against the formation of crossed-dimer valence-bond crystalline (CDVBC) ordering. The complete GS phase diagram is presented for arbitrary values of the frustration parameter k≡J2/J1, and when each of the exchange couplings can take either sign. PMID:26348836

  10. Quantum phase transitions in composite matrix product states of one-dimensional spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Zhu, Jing-Min

    2015-02-01

    For matrix product states of one-dimensional spin-1/2 chains, we investigate the properties of quantum phase transition of the proposed composite system. We find that the system has three different ferromagnetic phases, one line of the two ferromagnetic phases coexisting equally describes the paramagnetic state, and the other two lines of two ferromagnetic phases coexisting equally describe the ferrimagnetic states, while the three phases coexisting equally point describes the ferromagnetic state. Whether on phase transition lines or at the phase transition point, the system is always in an isolated mediate-coupling state, the physical quantities are discontinuous and the system has long-range correlation and has long-range classical correlation and long-range quantum correlation. We believe that our work is helpful for comprehensively and profoundly understanding the quantum phase transitions, and of some certain guidance and enlightening on the classification and measure of quantum correlation of quantum many-body systems.

  11. Dimerized ground state in the one-dimensional spin-1 boson Hubbard model

    SciTech Connect

    Apaja, Vesa; Syljuaasen, Olav F.

    2006-09-15

    We have investigated the one-dimensional spin-1 boson Hubbard model with antiferromagnetic interactions using quantum Monte Carlo methods. We obtain the shapes of the two lowest Mott lobes and show that the ground state within the lowest Mott lobe is dimerized. The results presented here are relevant for optically trapped antiferromagnetic spin-1 bosons. An experimental signature of the dimerized ground state is modulated Bragg peaks in the noise distribution of the atomic cloud obtained after switching off the trap. These Bragg peaks are located at wave vectors corresponding to half-integer multiples of the reciprocal wave vector of the optical lattice.

  12. Quantum-mechanical description of spin-1 particles with electric dipole moments

    NASA Astrophysics Data System (ADS)

    Silenko, Alexander J.

    2013-04-01

    The Proca-Corben-Schwinger equations for a spin-1 particle with an anomalous magnetic moment are added by a term describing an electric dipole moment, then they are reduced to a Hamiltonian form, and finally they are brought to the Foldy-Wouthuysen representation. Relativistic equations of motion are derived. The needed agreement between quantum-mechanical and classical relativistic equations of motion is proved. The scalar and tensor electric and magnetic polarizabilities of pointlike spin-1 particles (W bosons) are calculated for the first time.

  13. Spin-1 and -2 bilayer Bethe lattice: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Masrour, R.; Jabar, A.; Benyoussef, A.; Hamedoun, M.

    2016-03-01

    The magnetic behaviors of bilayer with spin-1 and 2 Ising model on the Bethe lattice are investigated using the Monte Carlo simulations. The thermal magnetizations, the magnetic susceptibilities and the transition temperature of the bilayer spin-1 and 2 on the Bethe lattice are studied for different values of crystal field and intralayer coupling constants of the two layers and interlayer coupling constant between the layers. The thermal and magnetic hysteresis cycles are given for different values of the crystal field, for different temperatures and for different exchange interactions.

  14. Quantum Correlations of Two Relativistic Spin-{1}/{2} Particles Under Noisy Channels

    NASA Astrophysics Data System (ADS)

    Mahdian, M.; Mojaveri, B.; Dehghani, A.; Makaremi, T.

    2016-02-01

    We study the quantum correlation dynamics of bipartite spin-{1}/{2} density matrices for two particles under Wigner rotations induced by Lorentz transformations which is transmitted through noisy channels. We compare quantum entanglement, geometric discord(GD), and quantum discord (QD) for bipartite relativistic spin-{1}/{2} states under noisy channels. We find out QD and GD tend to death asymptotically but a sudden change in the decay rate of the entanglement occurs under noisy channels. Also, bipartite relativistic spin density matrices are considered as a quantum channel for teleportation one-qubit state under the influence of depolarizing noise and compare fidelity for various velocities of observers.

  15. Optimization of the magnetocaloric effect in Ni-Mn-In alloys: A theoretical study

    SciTech Connect

    Sokolovskiy, V. V.; Buchelnikov, V. D.; Entel, P.

    2012-10-15

    Based on ab initio and Monte Carlo simulations, we study the influence of the strength of the magnetic exchange parameters on the inverse and conventional magnetocaloric effect in the Ni{sub 50}Mn{sub 34}In{sub 16} Heusler alloy using the mixed Potts and Blume-Emery-Griffiths model Hamiltonian. Within the proposed model, the temperature dependences of the magnetization, tetragonal deformation, and adiabatic temperature changes for magnetic field variation are obtained. It is first shown that a decrease in the magnetic exchange interactions leads to increased values of the magnetocaloric effect. We suppose that a reduction of the exchange interactions in the Ni-Mn-In alloy can be realized by the doping with nonmagnetic atoms such as B, Si, Zn, Cu, etc.

  16. Effects of a space modulation on the behavior of a 1D alternating Heisenberg spin-1/2 model.

    PubMed

    Mahdavifar, Saeed; Abouie, Jahanfar

    2011-06-22

    The effects of a magnetic field (h) and a space modulation (δ) on the magnetic properties of a one-dimensional antiferromagnetic-ferromagnetic Heisenberg spin-1/2 model have been studied by means of numerical exact diagonalization of finite size systems, the nonlinear σ model, and a bosonization approach. The space modulation is considered on the antiferromagnetic couplings. At δ = 0, the model is mapped to a gapless Lüttinger liquid phase by increasing the magnetic field. However, the space modulation induces a new gap in the spectrum of the system and the system experiences different quantum phases which are separated by four critical fields. By opening the new gap, a magnetization plateau appears at ½M(sat). The effects of the space modulation are reflected in the emergence of a plateau in other physical functions such as the F-dimer and the bond-dimer order parameters, and the pair-wise entanglement. PMID:21613724

  17. Quantum tunneling of massive spin-1 particles from non-stationary metrics

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Övgün, A.

    2016-01-01

    We focus on the HR of massive vector (spin-1) particles tunneling from Schwarzschild BH expressed in the Kruskal-Szekeres and dynamic Lemaitre coordinates. Using the Proca equation together with the Hamilton-Jacobi and the WKB methods, we show that the tunneling rate, and its consequence Hawking temperature are well recovered by the quantum tunneling of the massive vector particles.

  18. Next-to-leading order gravitational spin(1)-spin(2) dynamics in Hamiltonian form

    SciTech Connect

    Steinhoff, Jan; Hergt, Steven; Schaefer, Gerhard

    2008-04-15

    Based on recent developments by the authors a next-to-leading order spin(1)-spin(2) Hamiltonian is derived for the first time. The result is obtained within the canonical formalism of Arnowitt, Deser, and Misner (ADM) utilizing their generalized isotropic coordinates. A comparison with other methods is given.

  19. The Hidden Symmetries of Spin-1 Ising Lattice Gas for Usual Quantum Hamiltonians

    NASA Astrophysics Data System (ADS)

    Payandeh, Farrin

    2016-02-01

    In this letter, the most common quantum Hamiltonian is exploited in order to compare the definite equivalences, corresponding to possible spin values in a lattice gas model, to those in a spin-1 Ising model. Our approach also requires interpolating both results in a p-state clock model, in order to find the hidden symmetries of both under consideration models.

  20. The spin- {1}/{2} transverse XX chain with regularly alternating bonds and fields

    NASA Astrophysics Data System (ADS)

    Derzhko, Oleg; Richter, Johannes; Zaburannyi, Oles'

    1999-11-01

    We use continued fractions for a study of the thermodynamic properties of the periodic nonuniform spin- {1}/{2} isotropic XY chain in a non-random/random (Lorentzian) transverse field. The obtained results permit to examine the influence of a magnetic field and randomness on the spin-Peierls dimerization.

  1. Non-equilibrium dynamics of an unstable quantum pendulum explored in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Gerving, C. S.; Hoang, T. M.; Land, B. J.; Anquez, M.; Hamley, C. D.; Chapman, M. S.

    2012-11-01

    A pendulum prepared perfectly inverted and motionless is a prototype of unstable equilibrium and corresponds to an unstable hyperbolic fixed point in the dynamical phase space. Here, we measure the non-equilibrium dynamics of a spin-1 Bose-Einstein condensate initialized as a minimum uncertainty spin-nematic state to a hyperbolic fixed point of the phase space. Quantum fluctuations lead to non-linear spin evolution along a separatrix and non-Gaussian probability distributions that are measured to be in good agreement with exact quantum calculations up to 0.25s. At longer times, atomic loss due to the finite lifetime of the condensate leads to larger spin oscillation amplitudes, as orbits depart from the separatrix. This demonstrates how decoherence of a many-body system can result in apparent coherent behaviour. This experiment provides new avenues for studying macroscopic spin systems in the quantum limit and for investigations of important topics in non-equilibrium quantum dynamics.

  2. Crystal Structure of the Spin 1/2 Honeycomb-Lattice Antiferromagnet Cu2(pymca)3(ClO4)

    NASA Astrophysics Data System (ADS)

    Honda, Zentaro; Kodama, Takafumi; Kikukawa, Reo; Hagiwara, Masayuki; Kida, Takanori; Sakai, Masamichi; Fukuda, Takeshi; Fujihara, Takashi; Kamata, Norihiko

    2015-03-01

    Using X-ray diffraction techniques, we have studied the crystal structure of a copper polynuclear coordination polymer Cu2(pymca)3(ClO4) (pymca = pyrimidine-2-carboxylate), which is found to crystallize as a trigonal crystal system, space group P31m, with the lattice constants a = 9.5904(18) Å and c = 5.9000(11) Å, at temperature T = 150 K. Each pymca ligand connects to two Cu2+ ions, forming a honeycomb network in the ab plane. The T dependence of the magnetic susceptibility of Cu2(pymca)3(ClO4) shows a broad maximum near T = 26 K, indicating low-dimensional antiferromagnetic interactions. From the crystal structure and magnetic properties, we conclude that Cu2(pymca)3(ClO4) is a good realization of a spin-1/2 honeycomb lattice antiferromagnet.

  3. Exact asymptotic correlation functions of bilinear spin operators of the Heisenberg antiferromagnetic spin-1/2 chain

    NASA Astrophysics Data System (ADS)

    Vekua, T.; Sun, G.

    2016-07-01

    Exact asymptotic expressions of the uniform parts of the two-point correlation functions of bilinear spin operators in the Heisenberg antiferromagnetic spin-1/2 chain are obtained. Apart from the algebraic decay, the logarithmic contribution is identified, and the numerical prefactor is determined. We also confirm numerically the multiplicative logarithmic correction of the staggered part of the bilinear spin operators < > =(-1) rd /(r ln3/2r ) +(3 δa ,b-1 ) ln2r /(12 π4r4) , and estimate the numerical prefactor as d ≃0.067 . The relevance of our results for ground-state fidelity susceptibility at the Berezinskii-Kosterlitz-Thouless quantum phase transition points in one-dimensional systems is discussed at the end of our work.

  4. On the Superradiance of Spin-1 Waves in an Equatorial Wedge around a Kerr Hole.

    PubMed

    Aguirre

    2000-01-20

    Recently Van Putten has suggested that superradiance of magnetosonic waves in a toroidal magnetosphere around a Kerr black hole may play a role in the central engine of gamma-ray bursts. In this context, he computed (in the WKB approximation) the superradiant amplification of scalar waves confined to a thin equatorial wedge around a Kerr hole and found that the superradiance is higher than for radiation incident over all angles. This Letter presents calculations of both spin-0 (scalar) superradiance (integrating the radial equation rather than using the WKB method) and spin-1 (electromagnetic/magnetosonic) superradiance in Van Putten's wedge geometry. In contrast to the scalar case, spin-1 superradiance decreases in the wedge geometry, decreasing the likelihood of its astrophysical importance. PMID:10615024

  5. Low-energy singlet excitations in spin-1/2 Heisenberg antiferromagnet on square lattice

    NASA Astrophysics Data System (ADS)

    Aktersky, A. Yu.; Syromyatnikov, A. V.

    2016-05-01

    We present an approach based on a dimer expansion which describes low-energy singlet excitations (singlons) in spin-1/2 Heisenberg antiferromagnet on simple square lattice. An operator ("effective Hamiltonian") is constructed whose eigenvalues give the singlon spectrum. The "effective Hamiltonian" looks like a Hamiltonian of a spin-1/2 magnet in strong external magnetic field and it has a gapped spectrum. It is found that singlet states lie above triplet ones (magnons) in the whole Brillouin zone except in the vicinity of the point (π , 0), where their energies are slightly smaller. Based on this finding, we suggest that a magnon decay is possible near (π , 0) into another magnon and a singlon which may contribute to the dip of the magnon spectrum near (π , 0) and reduce the magnon lifetime. It is pointed out that the singlon-magnon continuum may contribute to the continuum of excitations observed recently near (π , 0).

  6. Characterizing the Haldane phase in quasi-one-dimensional spin-1 Heisenberg antiferromagnets

    NASA Astrophysics Data System (ADS)

    Wierschem, Keola; Sengupta, Pinaki

    2014-12-01

    We review the basic properties of the Haldane phase in spin-1 Heisenberg antiferromagnetic chains, including its persistence in quasi-one-dimensional (Q1D) geometries. Using large-scale numerical simulations, we map out the phase diagram for a realistic model applicable to experimental Haldane compounds. We also investigate the effect of different chain coupling geometries and confirm a general mean-field universality of the critical coupling times the coordination number of the lattice. Inspired by recent developments in the characterization of symmetry protected topological (SPT) states, of which the Haldane phase of the spin-1 Heisenberg antiferromagnetic chain is a preeminent example, we provide direct evidence that the Q1D Haldane phase is indeed a nontrivial SPT state.

  7. Violation of Bell’s inequality in a spin 1/2 quantum magnet

    SciTech Connect

    Chakraborty, Tanmoy Singh, Harkirat Mitra, Chiranjib

    2014-04-24

    Violation of Bell’s inequality test has been established as an efficient tool to determine the presence of entanglement in quantum spin 1/2 magnets. Herein, macroscopic thermodynamic quantities, namely, magnetic susceptibility and specific heat have been employed to perform Bell’s inequality test for [NH{sub 4}CuPO{sub 4}, H{sub 2}O], a spin 1/2 antiferromagnet with nearest neighbor interactions. The mean value of the Bell operator is quantified and plotted as a function of temperature. The threshold temperature is determined above which the Bell’s inequality is not violated and a good consistency is found between the analyses done on magnetic and thermal data.

  8. Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole

    SciTech Connect

    Sakalli, I.; Ovgun, A.

    2015-09-15

    We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton–Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.

  9. Hawking radiation of spin-1 particles from a three-dimensional rotating hairy black hole

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Ovgun, A.

    2015-09-01

    We study the Hawking radiation of spin-1 particles (so-called vector particles) from a three-dimensional rotating black hole with scalar hair using a Hamilton-Jacobi ansatz. Using the Proca equation in the WKB approximation, we obtain the tunneling spectrum of vector particles. We recover the standard Hawking temperature corresponding to the emission of these particles from a rotating black hole with scalar hair.

  10. Renormalization and additional degrees of freedom within the chiral effective theory for spin-1 resonances

    SciTech Connect

    Kampf, Karol; Novotny, Jiri; Trnka, Jaroslav

    2010-06-01

    We study in detail various aspects of the renormalization of the spin-1 resonance propagator in the effective field theory framework. First, we briefly review the formalisms for the description of spin-1 resonances in the path integral formulation with the stress on the issue of propagating degrees of freedom. Then we calculate the one-loop 1{sup --} meson self-energy within the resonance chiral theory in the chiral limit using different methods for the description of spin-1 particles, namely, the Proca field, antisymmetric tensor field, and the first-order formalisms. We discuss in detail technical aspects of the renormalization procedure which are inherent to the power-counting nonrenormalizable theory and give a formal prescription for the organization of both the counterterms and one-particle irreducible graphs. We also construct the corresponding propagators and investigate their properties. We show that the additional poles corresponding to the additional one-particle states are generated by loop corrections, some of which are negative norm ghosts or tachyons. We count the number of such additional poles and briefly discuss their physical meaning.

  11. Effects of spacetime curvature on spin-1/2 particle zitterbewegung

    NASA Astrophysics Data System (ADS)

    Singh, Dinesh; Mobed, Nader

    2009-09-01

    This paper investigates the properties of spin-1/2 particle zitterbewegung in the presence of a general curved spacetime background described in terms of Fermi normal coordinates, where the spatial part is expressed using general curvilinear coordinates. Adopting the approach first introduced by Barut and Bracken for zitterbewegung in the local rest frame of the particle, it is shown that non-trivial gravitational contributions to the relative position and momentum operators appear due to the coupling of zitterbewegung frequency terms with the Ricci curvature tensor in the Fermi frame, indicating a formal violation of the weak equivalence principle. Explicit expressions for these contributions are shown for the case of quasi-circular orbital motion of a spin-1/2 particle in a Vaidya background. Formal expressions also appear for the time derivative of the Pauli-Lubanski vector due to spacetime curvature effects coupled to the zitterbewegung frequency. Also, the choice of curvilinear coordinates results in non-inertial contributions in the time evolution of the canonical momentum for the spin-1/2 particle, where zitterbewegung effects lead to stability considerations for its propagation, based on the Floquet theory of differential equations.

  12. SPIN-1/2 Particles in Weak Gravitational Fields:. Foldy-Wouthuysen and Cini-Touschek Approximations

    NASA Astrophysics Data System (ADS)

    Singh, Dinesh; Papini, Giorgio

    2002-12-01

    We introduce a Hamiltonian for spin-1/2 particles with weak inertial and gravitational field corrections. Low- and high-energy approximations then follow from the Foldy-Wouthuysen and Cini-Touschek transformations.

  13. Quantum Kibble-Zurek Mechanism in a Spin-1 Bose-Einstein Condensate.

    PubMed

    Anquez, M; Robbins, B A; Bharath, H M; Boguslawski, M; Hoang, T M; Chapman, M S

    2016-04-15

    The dynamics of a quantum phase transition are explored using slow quenches from the polar to the broken-axisymmetry phases in a small spin-1 ferromagnetic Bose-Einstein condensate. Measurements of the evolution of the spin populations reveal a power-law scaling of the temporal onset of excitations versus quench speed as predicted from quantum extensions of the Kibble-Zurek mechanism. The satisfactory agreement of the measured scaling exponent with the analytical theory and numerical simulations provides experimental confirmation of the quantum Kibble-Zurek model. PMID:27127974

  14. High precision description and new properties of a spin-1 particle in a magnetic field

    NASA Astrophysics Data System (ADS)

    Silenko, Alexander J.

    2014-06-01

    The exact Foldy-Wouthuysen Hamiltonian is derived for a pointlike spin-1 particle with a normal magnetic moment in a nonuniform magnetic field. For a uniform magnetic field, it is exactly separated into terms linear and quadratic in spin. New unexpected properties of a particle with an anomalous magnetic moment are found. Spin projections of a particle moving in a uniform magnetic field are not integer, and the tensor polarization is asymmetric in the plane orthogonal to the field. Previously described spin-tensor effects caused by the tensor magnetic polarizability exist not only for nuclei but also for pointlike particles.

  15. Plane waves in de Sitter space: Spin-1/2 field

    NASA Astrophysics Data System (ADS)

    Reza Tanhayi, M.; Mohsenzadeh, M.; Yusofi, E.

    2016-06-01

    We employ the coordinate-independent plane wave solution in de Sitter space to study the spin-1/2 particle production. The so-called plane waves in the zero-curvature limit reduce to the usual plane waves in flat space. Previously in (Int. J. Mod. Phys. D 24, 1550052 (2015)) we used such modes to study the instability of the de Sitter space, here, by explicit calculation, we study the sipn-1/2 particle creation in de Sitter space caused by mixing modes.

  16. Long-range order for the spin-1 Heisenberg model with a small antiferromagnetic interaction

    SciTech Connect

    Lees, Benjamin

    2014-09-15

    We look at the general SU(2) invariant spin-1 Heisenberg model. This family includes the well-known Heisenberg ferromagnet and antiferromagnet as well as the interesting nematic (biquadratic) and the largely mysterious staggered-nematic interaction. Long range order is proved using the method of reflection positivity and infrared bounds on a purely nematic interaction. This is achieved through the use of a type of matrix representation of the interaction making clear several identities that would not otherwise be noticed. Using the reflection positivity of the antiferromagnetic interaction one can then show that the result is maintained if we also include an antiferromagnetic interaction that is sufficiently small.

  17. Dynamic Structure Factors of the Spin-1/2 XX Chain with Dzyaloshinskii-Moriya Interaction

    NASA Astrophysics Data System (ADS)

    Derzhko, Oleg; Verkholyak, Taras

    2006-10-01

    We consider the spin-1/2 isotropic XY chain in a (z) transverse magnetic field with the Dzyaloshinskii-Moriya interaction directed along the z-axis in spin space and examine the effects of the latter interaction on the zz, xx (yy) and xy (yx) dynamic structure factors. The Dzyaloshinskii-Moriya interaction does not manifest itself in the zz dynamic quantities. In contrast, the xx (yy) and xy (yx) dynamic structure factors show dramatical changes owing to the Dzyaloshinskii-Moriya interaction. Implications of our results for electron spin resonance experiments are briefly discussed.

  18. Exact solution of the spin-1/2 Ising model on the Shastry Sutherland (orthogonal-dimer) lattice

    NASA Astrophysics Data System (ADS)

    Strečka, Jozef

    2006-01-01

    A star-triangle mapping transformation is used to establish an exact correspondence between the spin-1/2 Ising model on the Shastry Sutherland (orthogonal-dimer) lattice and respectively, the spin-1/2 Ising model on a bathroom tile (4 8) lattice. Exact results for the critical temperature and spontaneous magnetization are obtained and compared with corresponding results on the regular Ising lattices.

  19. Magnetoelectric effects in the spin 1/2 XX chain with three spin interactions and Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Durganandini, P.

    We consider the spin 1/2 XX chain with three spin interactions of the XZX+YXY and XZY-YZX types in an external magnetic field and with Dzyaloshinskii-Moriya (D-M) interaction. Interpreting the D-M interaction as a local electric polarization, we study the magnetoelectric effects in the system by using the exact solution of the problem. We obtain the ground state phase diagram by calculating the electric polarization, magnetization and isentropes. There are various regimes of magnetic and electric polarization depending on the relative strengths of the three spin interaction as well as that of the external fields. For a certain range of three spin interaction strengths, the system shows the existence of finite magnetization and electric polarization even in the absence of any external fields. The external electric and magnetic fields modify the ground state phases and can be used to tune the various regimes. We also calculate the entropy and analyze the electrocaloric and magnetocaloric effects. We show that the electrocaloric and magnetocaloric effects can be used to obtain information about the magnetoelectric effects in the system. I thank DST, India for financial support through research grant.

  20. Contribution of the spin-1 diquark to the nucleon's g1 structure function

    NASA Astrophysics Data System (ADS)

    Zamani, F.

    2010-07-01

    This is the final installment of a series of work that we have done in the context of the meson cloud model that investigates F2 and g1 structure functions. In our previous work on g1 structure function, we showed that having a spin-0 quark-diquark for the nucleon core along with both pseudoscalar and vector meson clouds was not sufficient to reproduce experimental observation(s) consistently. For the F2 structure function, we found that both superposition of a spin-0 diquark and a spin-1 diquark in the nucleon core along with pseudoscalar and vector meson clouds are needed to reproduce the observed F2(x) and the Gottfried sum rule (GSR) violation. Therefore, in the present work, we consider the contribution of a spin-1 diquark in the nucleon core to the g1 structure function. The calculation is performed in the light-cone frame. The dressed nucleon is assumed to be a superposition of the bare nucleon plus virtual light-cone Fock states of baryon-meson pairs. For the bare nucleon, we consider different quark-diquark configurations along with the possibility that there is no diquark inside the nucleon. The initial distributions are evolved. The final results are compared with experimental results and other theoretical predictions.

  1. Second order formalism for spin (1/2) fermions and Compton scattering

    SciTech Connect

    Delgado-Acosta, E. G.; Napsuciale, Mauro; Rodriguez, Simon

    2011-04-01

    We develop a second order formalism for massive spin 1/2 fermions based on the projection over Poincare invariant subspaces in the ((1/2),0)+(0,(1/2)) representation of the homogeneous Lorentz group. Using the U(1){sub em} gauge principle we obtain a second order description for the electromagnetic interactions of a spin 1/2 fermion with two free parameters, the gyromagnetic factor g and a parameter {xi} related to odd-parity Lorentz structures. We calculate Compton scattering in this formalism. In the particular case g=2, {xi}=0, and for states with well-defined parity, we recover Dirac results. In general, we find the correct classical limit and a finite value r{sub c}{sup 2} for the forward differential cross section, independent of the photon energy and of the value of the parameters g and {xi}. The differential cross section vanishes at high energies for all g, {xi} except in the forward direction. The total cross section at high energies vanishes only for g=2, {xi}=0. We argue that this formalism is more convenient than Dirac theory in the description of low energy electromagnetic properties of baryons and illustrate the point with the proton case.

  2. Magnetic and nematic phases in a Weyl type spin–orbit-coupled spin-1 Bose gas

    NASA Astrophysics Data System (ADS)

    Chen, Guanjun; Chen, Li; Zhang, Yunbo

    2016-06-01

    We present a variational study of the spin-1 Bose gases in a harmonic trap with three-dimensional spin–orbit (SO) coupling of Weyl type. For weak SO coupling, we treat the single-particle ground states as the form of perturbational harmonic oscillator states in the lowest total angular momentum manifold with j = 1, m j = 1, 0, ‑1. When the two-body interaction is considered, we set the trail order parameter as the superposition of three degenerate single-particle ground-states and the weight coefficients are determined by minimizing the energy functional. Two ground state phases, namely the magnetic and the nematic phases, are identified depending on the spin-independent and the spin-dependent interactions. Unlike the non-SO-coupled spin-1 Bose–Einstein condensate for which the phase boundary between the magnetic and the nematic phase lies exactly at zero spin-dependent interaction, the boundary is modified by the SO-coupling. We find the magnetic phase is featured with phase-separated density distributions, 3D skyrmion-like spin textures and competing magnetic and biaxial nematic orders, while the nematic phase is featured with miscible density distributions, zero magnetization and spatially modulated uniaxial nematic order. The emergence of higher spin order creates new opportunities for exploring spin-tensor-related physics in SO coupled superfluid.

  3. Regularly alternating spin- 1 /2 anisotropic XY chains: The ground-state and thermodynamic properties

    NASA Astrophysics Data System (ADS)

    Derzhko, Oleg; Richter, Johannes; Krokhmalskii, Taras; Zaburannyi, Oles'

    2004-06-01

    Using the Jordan-Wigner transformation and continued fractions we calculate rigorously the thermodynamic quantities for the spin- 1 /2 transverse Ising chain with periodically varying intersite interactions and/or on-site fields. We consider in detail the properties of the chains having a period of the transverse field modulation equal to 3. The regularly alternating transverse Ising chain exhibits several quantum phase transition points, where the number of transition points for a given period of alternation strongly depends on the specific set of the Hamiltonian parameters. The critical behavior in most cases is the same as for the uniform chain. However, for certain sets of the Hamiltonian parameters the critical behavior may be changed and weak singularities in the ground-state quantities appear. Due to the regular alternation of the Hamiltonian parameters the transverse Ising chain may exhibit plateaulike steps in the zero-temperature dependence of the transverse magnetization vs transverse field and many-peak temperature profiles of the specific heat. We compare the ground-state properties of regularly alternating transverse Ising and transverse XX chains and of regularly alternating quantum and classical chains. Making use of the corresponding unitary transformations we extend the elaborated approach to the study of thermodynamics of regularly alternating spin- 1 /2 anisotropic XY chains without field. We use the exact expression for the ground-state energy of such a chain of period 2 to discuss how the exchange interaction anisotropy destroys the spin-Peierls dimerized phase.

  4. Thermodynamics of spin- 1/2 antiferromagnet-antiferromagnet-ferromagnet and ferromagnet-ferromagnet-antiferromagnet trimerized quantum Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Gu, Bo; Su, Gang; Gao, Song

    2006-04-01

    The magnetization process, the susceptibility, and the specific heat of the spin- 1/2 antiferromagnet (AF)-AF-ferromagnet (F) and F-F-AF trimerized quantum Heisenberg chains have been investigated by means of the transfer matrix renormalization group (TMRG) technique as well as the modified spin-wave (MSW) theory. A magnetization plateau at m=1/6 for both trimerized chains is observed at low temperature. The susceptibility and the specific heat show various behaviors for different ferromagnetic and antiferromagnetic interactions and in different magnetic fields. The TMRG results of susceptibility and the specific heat can be nicely fitted by a linear superposition of double two-level systems, where two fitting equations are proposed. Three branch excitations, one gapless excitation and two gapful excitations, for both systems are found within the MSW theory. It is observed that the MSW theory captures the main characteristics of the thermodynamic behaviors at low temperatures. The TMRG results are also compared with the possible experimental data.

  5. Deformable spin- (1)/(2) XX chain with three-site interactions at zero and finite temperatures

    NASA Astrophysics Data System (ADS)

    Derzhko, Oleg; Krokhmalskii, Taras; Stolze, Joachim; Verkholyak, Taras

    2009-03-01

    We study spin-Peierls structural lattice instabilities for a spin-1/2 isotropic XY chain with three-site interactions of (XZX+YZY) type. Within the adopted adiabatic treatment we have to examine the ground-state energy or the Helmholtz free energy of the spin chain with exchange couplings varying coherently with a possible static lattice distortion pattern. Since the considered spin model can be converted into a system of noninteracting spinless fermions the required ground-state energy or the Helmholtz free energy can be calculated accurately without making any approximations. We examine rigorously several lattice distortion patterns focusing on dimerized and trimerized ones, which owe their presence to the spin-Peierls mechanism. We present phase diagrams illustrating the effect of the three-site interaction on the spin-Peierls lattice distortions. Finally we discuss some properties of the deformable spin chain in the ground state and at finite temperatures. In particular, we examine the transverse magnetization, the static transverse susceptibility and the specific heat illustrating the changes in these quantities due to lattice instabilities.

  6. Hamiltonian and action principle formalisms for spin-1/2 magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Lingam, M.

    2015-02-01

    A Hamiltonian and Action Principle formulation of spin-1/2 magnetohydrodynamics is presented via a first-principles derivation of the underlying Lagrangian, and the associated Hamiltonian. The derivation invokes the notion of "frozen-in" constraints, symmetry breaking, and similarities with Ginzburg-Landau theory to arrive at the relevant terms in the Hamiltonian. The model thus obtained includes the effects of spin and other quantum corrections and is shown to be in full agreement with existent models in the literature. It is also indicated how two-fluid effects, gyroviscosity, and anisotropic pressure can be included in the model, in addition to incorporating higher-order (nonlinear) quantum spin corrections. An interesting analogy with the theory of liquid crystals is also highlighted.

  7. Spin-1/2 Heisenberg Antiferromagnet on the Spatially Anisotropic Kagome Lattice

    NASA Astrophysics Data System (ADS)

    Schnyder, Andreas; Starykh, Oleg; Balents, Leon

    2008-03-01

    We study the quasi-one-dimensional limit of the Spin-1/2 quantum antiferromagnet on the Kagome lattice, a model Hamiltonian that might be of relevance for the mineral volborthite [1,2]. The lattice is divided into antiferromagnetic spin-chains (exchange J) that are weakly coupled via intermediate ``dangling'' spins (exchange J'). Using bosonization, renormalization group methods, and current algebra techniques we determine the ground state as a function of J'/J. The case of a strictly one-dimensional Kagome strip is also discussed. [1] Z. Hiroi, M. Hanawa, N. Kobayashi, M. Nohara, Hidenori Takagi, Y. Kato, and M. Takigawa, J. Phys. Soc. Japan 70, 3377 (2001). [2] F. Bert, D. Bono, P. Mendels, F. Ladieu, F. Duc, J.-C. Trumbe, and P. Millet, Phys. Rev. Lett. 95, 087203 (2005).

  8. Partition function zeros and magnetization plateaus of the spin-1 Ising-Heisenberg diamond chain

    NASA Astrophysics Data System (ADS)

    Hovhannisyan, V. V.; Ananikian, N. S.; Kenna, R.

    2016-07-01

    We study the properties of the generalized spin-1 Ising-Heisenberg model on a diamond chain, which can be considered as a theoretical model for the homometallic magnetic complex [Ni3(C4H2O4)2 -(μ3 - OH) 2(H2O)4 ] n ṡ(2H2 O) n. The model possesses a large variety of ground-state phases due to the presence of biquadratic and single-ion anisotropy parameters. Magnetization and quadrupole moment plateaus are observed at one- and two-thirds of the saturation value. The distributions of Yang-Lee and Fisher zeros are studied numerically for a variety of values of the model parameters. The usual value σ = -1/2 alongside an unusual value σ = -2/3 ​is determined for the Yang-Lee edge singularity exponents.

  9. Hamiltonian and action principle formalisms for spin-1/2 magnetohydrodynamics

    SciTech Connect

    Lingam, M.

    2015-02-15

    A Hamiltonian and Action Principle formulation of spin-1/2 magnetohydrodynamics is presented via a first-principles derivation of the underlying Lagrangian, and the associated Hamiltonian. The derivation invokes the notion of “frozen-in” constraints, symmetry breaking, and similarities with Ginzburg-Landau theory to arrive at the relevant terms in the Hamiltonian. The model thus obtained includes the effects of spin and other quantum corrections and is shown to be in full agreement with existent models in the literature. It is also indicated how two-fluid effects, gyroviscosity, and anisotropic pressure can be included in the model, in addition to incorporating higher-order (nonlinear) quantum spin corrections. An interesting analogy with the theory of liquid crystals is also highlighted.

  10. Quantum and classical thermal correlations in the XY spin-(1/2) chain

    SciTech Connect

    Maziero, J.; Guzman, H. C.; Celeri, L. C.; Serra, R. M.; Sarandy, M. S.

    2010-07-15

    We investigate pairwise quantum correlation as measured by the quantum discord as well as its classical counterpart in the thermodynamic limit of anisotropic XY spin-1/2 chains in a transverse magnetic field for both zero and finite temperatures. Analytical expressions for both classical and quantum correlations are obtained for spin pairs at any distance. In the case of zero temperature, it is shown that the quantum discord for spin pairs farther than second neighbors is able to characterize a quantum phase transition, even though pairwise entanglement is absent for such distances. For finite temperatures, we show that quantum correlations can be increased with temperature in the presence of a magnetic field. Moreover, in the XX limit, thermal quantum discord is found to be dominant over classical correlation while the opposite scenario takes place for the transverse field Ising model limit.

  11. Scaling behavior of spin gap of the bond alternating anisotropic spin-1/2 Heisenberg chain

    NASA Astrophysics Data System (ADS)

    Paul, Susobhan; Ghosh, Asim Kumar

    2016-05-01

    Scaling behavior of spin gap of a bond alternating spin-1/2 anisotropic Heisenberg chain has been studied both in ferromagnetic (FM) and antiferromagnetic (AFM) cases. Spin gap has been estimated by using exact diagonalization technique. All those quantities have been obtained for a region of anisotropic parameter Δ defined by 0≤Δ≤1. Spin gap is found to develop as soon as the non-uniformity in the alternating bond strength is introduced in the AFM regime which furthermore sustains in the FM regime as well. Scaling behavior of the spin gap has been studied by introducing scaling exponent. The variation of scaling exponents with Δ is fitted with a regular function.

  12. Quantum discord in spin-1/2 Heisenberg chains with Dzyaloshinkii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Ma, Xiao San; Wang, An Min

    2015-12-01

    We have investigated the quantum discord (QD) of the thermal density matrix of spin-1/2 Heisenberg chains with Dzyaloshinskii-Moriya (DM) interaction. With fermionization technique, we study the mutual effect of DM interaction and the external magnetic field on the QD and the entanglement. Our analysis implies that the DM interaction can enhance the QD while the external magnetic field will shrink the QD. By a comparison between the entanglement and the QD, we find that the QD is more robust to the temperature and to the external magnetic field than the entanglement of formation (EoF) in the sense that the EoF takes a zero value while the QD does not for high temperature and strong external magnetic field. This point confirms the conclusion that there exist some separable states containing non-zero QD.

  13. Magnetic phases of spin-1 spin-orbit coupled Bose gases

    NASA Astrophysics Data System (ADS)

    Campbell, Daniel; Price, Ryan; Putra, Andika; Valdés-Curiel, Ana; Trypogeorgos, Dimitrios; Spielman, Ian; Spielman Team

    We experimentally explore the magnetic phases present in a near-zero temperature spin-1 spin-orbit coupled atomic Bose gas. We observe ferromagnetic and unpolarized phases which are stabilized by the spin-orbit coupling's explicit locking between spin and motion. In the limit of weak spin-orbit coupling, these phases are separated by a critical curve of 1st order quantum phase transitions, with an observed width as small as h × 4Hz . These phase transitions give rise to long-lived metastable states. This work was partially supported by the ARO's atomtronics MURI, by the AFOSR's Quantum Matter MURI, NIST, and the NSF through the PFC at the JQI.

  14. Quantum dimer model for the spin-1/2 kagome Z2 spin liquid

    NASA Astrophysics Data System (ADS)

    Rousochatzakis, Ioannis; Wan, Yuan; Tchernyshyov, Oleg; Mila, Frederic

    2015-03-01

    We revisit the description of the low-energy singlet sector of the spin-1/2 Heisenberg antiferromagnet on kagome in terms of an effective quantum dimer model. With the help of exact diagonalizations of appropriate finite-size clusters, we show that the embedding of a given process in its kagome environment leads to dramatic modifications of the amplitudes of the elementary loop processes, an effect not accessible to the standard approach based on the truncation of the Hamiltonian to the nearest-neighbour valence-bond basis. The resulting parameters are consistent with a Z2 spin liquid rather than with a valence-bond crystal, in agreement with the last density matrix renormalization group results. Currently at: School of Physics and Astronomy, University of Minnesota.

  15. Mott lobes evolution of the spin-1 Bose-Hubbard model

    NASA Astrophysics Data System (ADS)

    Hincapie-F, A. F.; Franco, R.; Silva-Valencia, J.

    2016-02-01

    We study spin-1 bosons confined in a one-dimensional optical lattice, taking into consideration both ferromagnetic and antiferromagnetic interaction. Using the density matrix renormalization group, we determine the phase diagram for the two firsts lobes and report the evolution of the first and second Mott lobes with respect to the spin-exchange interaction parameter (U 2). We determine that for the antiferromagnetic case, the first lobe is suppressed while the second grows as |U 2| increases. For the ferromagnetic case, the first and second Mott lobes are suppressed by the spin-exchange interaction parameter. We propose an expresion to describe the evolution of the critical point with the increase in |U 2| for both cases.

  16. Modulated phases and chaotic behavior in a spin-1 Ising model with competing interactions

    NASA Astrophysics Data System (ADS)

    Tomé, Tânia; Salinas, S. R.

    1989-02-01

    We formulate the Blume-Capel spin-1 Ising model, with competing first- and second-neighbor interactions along the branches of a Cayley tree, in the infinite-coordination limit, as a discrete two-dimensional nonlinear mapping problem. The phase diagram displays multicritical points and many modulated phases. Mean-field calculations for the analogous model on a cubic lattice give the same qualitative results. We take advantage of the simplicity of the mapping to show the existence of complete devil's staircases, at low temperatures T, with increasing values of the Hausdorff dimensionality DF with T. We show that there are regions of the phase diagram associated with positive values of the Lyapunov exponents of the mapping, and we give strong numerical evidence to support the existence of a strange attractor with a Lyapunov dimension Dλ>1. We also find a route to chaos, according to the scenario of Feigenbaum, with a reasonable estimate of the exponent δ.

  17. Dirac dynamics on stochastic phase spaces for spin 1/2 particles

    NASA Astrophysics Data System (ADS)

    Prugovečki, Eduard

    1980-06-01

    The Foldy-Wouthuysen representation of the dynamics of a free spin {1}/{2} particle is formulated in a Hilbert space H(Γ) of spinor-valued functions over Γ-space. H(Γ) carries a reducible Wigner-type representation of the Poincaré group. The transition to the Dirac representation in a new bispinor Hilbert space K(Γ) is effected by means of a generalized inverse Foldy-Wouthuysen transformation. Explicit expressions are derived for the resolution generators η of invariant subspaces K±(Γ η) carrying irreducible representations of the resulting representations of the Poincaré group. The formalism is recast in a manifestly covariant form and the Dirac equation on H(Γ s) with minimal coupling to a four-potential is examined. It is shown that the resulting external field theory is gauge-invariant and relativistically covariant.

  18. CP-Violation from Spin-1 Resonances in a Left-Right Dynamical Higgs Context

    NASA Astrophysics Data System (ADS)

    Ruan, Kun-Ming; Shu, Jing; Yepes, Juan

    2016-07-01

    New physics field content in the nature, more specifically, from spin-1 resonances sourced by the extension of the SM local gauge symmetry to the larger local group SU(2)L ⊗ SU(2)R ⊗ U(1)B-L, may induce CP-violation signalling NP effects from higher energy regimes. In this work we completely list and study all the CP-violating operators up to the p4-order in the Lagrangian expansion, for a non-linear left-right electroweak chiral context and coupled to a light dynamical Higgs. Heavy right handed fields can be integrated out from the physical spectrum, inducing thus a physical impact in the effective gauge couplings, fermionic electric dipole moment, and CP-violation in the decay h → ZZ* → 4l that are briefly analysed. The final relevant set of effective operators have also been identified at low energies. Supported by KITPC financial during the completion of this work

  19. Generalized parton correlation functions for a spin-1/2 hadron

    SciTech Connect

    Stephan Meissner, Andreas Metz, Marc Schlegel

    2009-08-01

    The fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects, in particular, can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. We find that none of these relations can be promoted to a model-independent status. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist. The present paper is a natural extension of our previous corresponding analysis for spin-0 hadrons.

  20. Spin 1 /2 field and regularization in a de Sitter and radiation dominated universe

    NASA Astrophysics Data System (ADS)

    Ghosh, Suman

    2016-02-01

    We construct a simple algorithm to derive number density of spin 1 /2 particles created in spatially flat Friedmann-Lemaitre-Robertson-Walker spacetimes and resulting renormalized energy-momentum tensor within the framework of adiabatic regularization. Physical quantities thus found are in agreement with the known results. This formalism can be considered as an appropriate extension of the techniques originally introduced for scalar fields, applicable to fermions in curved space. We apply this formalism to compute the particle number density and the renormalized energy density and pressure analytically (wherever possible) and numerically, in two interesting cosmological scenarios: a de Sitter spacetime and a radiation dominated universe. Results prove the efficiency of the methodology presented here.

  1. Spin-0 and spin-1/2 particles in a constant scalar-curvature background

    NASA Astrophysics Data System (ADS)

    Alimohammadi, M.; Vakili, B.

    2004-03-01

    We study the Klein-Gordon and Dirac equations in the presence of a background metric d s2=-d t2+d x2+e -2 gx(d y2+d z2) in a semi-infinite lab ( x>0). This metric has a constant scalar-curvature R=6 g2 and is produced by a perfect fluid with equation of state p=- ρ/3. The eigenfunctions of spin-0 and spin-1/2 particles are obtained exactly, and the quantized energy eigenvalues are compared. It is shown that both of these particles must have nonzero transverse momentum in this background. We show that there is a minimum energy E2min= m2c4+ g2c2ℏ 2 for bosons ( EKG> Emin), while the fermions have no specific ground state ( EDirac> mc2).

  2. Spin-orbit angular momentum coupling in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Chen, Li; Pu, Han; Zhang, Yunbo

    2016-01-01

    We propose a simple model with spin and orbit angular momentum coupling in a spin-1 Bose-Einstein condensate, where three internal atomic states are Raman coupled by a pair of copropagating Laguerre-Gaussian beams. The resulting Raman transition imposes a transfer of orbital angular momentum between photons and the condensate in a spin-dependent way. Focusing on a regime where the single-particle ground state is nearly threefold degenerate, we show that the weak interatomic interaction in the condensate produces a rich phase diagram, and that a many-body Rabi oscillation between two quantum phases can be induced by a sudden quench of the quadratic Zeeman shift. We carried out our calculations using both a variational method and a full numerical method, and found excellent agreement.

  3. Magnetic properties of spin-1/2 Fermi gases with ferromagnetic interaction

    NASA Astrophysics Data System (ADS)

    Wang, Baobao; Qin, Jihong; Guo, Huaiming

    2015-10-01

    We investigate the magnetic properties of spin-1/2 charged Fermi gases with ferromagnetic coupling via mean-field theory, and find the interplay among the paramagnetism, diamagnetism and ferromagnetism. Paramagnetism and diamagnetism compete with each other. When increasing the ferromagnetic coupling the spontaneous magnetization occurs in a weak magnetic field. The critical ferromagnetic coupling constant of the paramagnetic phase to ferromagnetic phase transition increases linearly with the temperature. Both the paramagnetism and diamagnetism increase when the magnetic field increases. It reveals the magnetization density bar M increases firstly as the temperature increases, and then reaches a maximum. Finally the magnetization density bar M decreases smoothly in the high temperature region. The domed shape of the magnetization density bar M variation is different from the behavior of Bose gas with ferromagnetic coupling. We also find the curve of susceptibility follows the Curie-Weiss law, and for a given temperature the susceptibility is directly proportional to the Landé factor.

  4. Mean field study of the topological Haldane-Hubbard model of spin-1/2 fermions

    NASA Astrophysics Data System (ADS)

    Arun, V. S.; Sohal, R.; Hickey, C.; Paramekanti, A.

    2016-03-01

    Motivated by exploring the effect of interactions on Chern insulators, and by recent experiments realizing topological bands for ultracold atoms in synthetic gauge fields, we study the honeycomb lattice Haldane-Hubbard model of spin-1/2 fermions. Using an unrestricted mean field approach, we map out the instability of the topological band insulator towards magnetically ordered insulators which emerge with increasing Hubbard repulsion. In addition to the topological Néel phase, we recover various chiral noncoplanar magnetic orders previously identified within a strong-coupling approach. We compute the band structure of these ordered phases, showing that the triple-Q tetrahedral phase harbors topological Chern bands with large Chern numbers.

  5. Magnetoelectric effects in the spin-1/2 XXZ model with Dzyaloshinskii-Moriya interaction

    SciTech Connect

    Thakur, Pradeep; Durganandini, P.

    2015-06-24

    We study the 1D spin-1/2 XXZ chain in the presence of the Dzyaloshinskii-Moriya (D-M) interaction and with longitudinal and transverse magnetic fields. We assume the spin-current mechanism of Katsura-Nagaosa-Balatsky at play and interpret the D-M interaction as a coupling between the local electric polarization and an external electric field. We study the interplay of electric and magnetic order in the ground state using the numerical density matrix renormalization group(DMRG) method. Specifically, we investigate the dependences of the magnetization and electric polarization on the external electric and magnetic fields. We find that for transverse magnetic fields, there are two different regimes of polarization while for longitudinal magnetic fields, there are three different regimes of polarization. The different regimes can be tuned by the external magnetic fields.

  6. Quantum and classical thermal correlations in the XY spin-(1)/(2) chain

    NASA Astrophysics Data System (ADS)

    Maziero, J.; Guzman, H. C.; Céleri, L. C.; Sarandy, M. S.; Serra, R. M.

    2010-07-01

    We investigate pairwise quantum correlation as measured by the quantum discord as well as its classical counterpart in the thermodynamic limit of anisotropic XY spin-1/2 chains in a transverse magnetic field for both zero and finite temperatures. Analytical expressions for both classical and quantum correlations are obtained for spin pairs at any distance. In the case of zero temperature, it is shown that the quantum discord for spin pairs farther than second neighbors is able to characterize a quantum phase transition, even though pairwise entanglement is absent for such distances. For finite temperatures, we show that quantum correlations can be increased with temperature in the presence of a magnetic field. Moreover, in the XX limit, thermal quantum discord is found to be dominant over classical correlation while the opposite scenario takes place for the transverse field Ising model limit.

  7. Fermi spin current contribution in spin wave spectrum of spin-1/2 fermions

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel; Kuzmenkov, Leonid

    2016-05-01

    General theory predicts the presence of the thermal part of the spin current in the spin evolution equation for bosons and fermions. For bosons in Bose-Einstein condensate state, it is equal to zero. However, for degenerate fermions it is non zero and it can give a considerable contribution since it describes the Pauli blocking. In this work, we consider spin-1/2 partially polarized fermions. We derive an equation of state for the thermal part of the spin current of degenerate fermions and call it Fermi spin current. We present the spin evolution equation with the Fermi spin current as a part of applied hydrodynamic model. We consider spectrum of collective excitation and describe contribution of the Fermi spin current in the spin wave spectrum. The work of P.A. was supported by the Russian Foundation for Basic Research (Grant No. 16-32-00886) and the Dynasty foundation.

  8. Relaxation after quantum quenches in the spin-1/2 Heisenberg XXZ chain

    NASA Astrophysics Data System (ADS)

    Fagotti, Maurizio; Collura, Mario; Essler, Fabian H. L.; Calabrese, Pasquale

    2014-03-01

    We consider the time evolution after quantum quenches in the spin-1/2 Heisenberg XXZ quantum spin chain with Ising-type anisotropy. The time evolution of short-distance spin-spin correlation functions is studied by numerical tensor network techniques for a variety of initial states, including Néel and Majumdar-Ghosh states and the ground state of the XXZ chain at large values of the anisotropy. The various correlators appear to approach stationary values, which are found to be in good agreement with the results of exact calculations of stationary expectation values in appropriate generalized Gibbs ensembles. In particular, our analysis shows how symmetries of the post-quench Hamiltonian that are broken by particular initial states are restored at late times.

  9. Signals for new spin-1 resonances in electroweak gauge boson pair production at the LHC

    SciTech Connect

    Alves, A.; Eboli, O. J. P.; Netto, D. Goncalves; Gonzalez-Garcia, M. C.; Mizukoshi, J. K.

    2009-10-01

    The mechanism of electroweak symmetry breaking (EWSB) will be directly scrutinized soon at the CERN Large Hadron Collider. We analyze the LHC potential to look for new vector bosons associated with the EWSB sector, presenting a possible model independent approach to search for these new spin-1 resonances. We show that the analyses of the processes pp{yields}l{sup +}l{sup '-}Ee{sub T}, l{sup {+-}}jjEe{sub T}, l{sup '{+-}}l{sup +}l{sup -}Ee{sub T}, l{sup {+-}}jjEe{sub T}, and l{sup +}l{sup -}jj (with l, l{sup '}=e or {mu} and j=jet) have a large reach at the LHC and can lead to the discovery or exclusion of many EWSB scenarios such as Higgsless models.

  10. Local Magnetization in the Impure Spin 1/2 Anisotropic Ising-Heisenberg Chains

    NASA Astrophysics Data System (ADS)

    Gildenblat, Gennady

    A theory of the Friedel-type oscillations of the local magnetization in the impure antiferromagnetic spin 1/2 chains is developed using the Green function equations of motion in the pseudo-fermion representation. For the isotropic XY (XX) chain, the problem is solved exactly, while the Ising-Heisenberg model is investigated numerically within a temperature-dependent Hartree-Fock approximation. It is shown that the Hartree-Fock self consistency equations for the uniformly magnetized XXZ chain can be recovered as a particular case of the formalism developed in the present work. Comparison with the earlier perturbation theory treatment in a free-fermion approximation reveals that the magnetic field dependence of the perturbation of the local magnetization is sensitive to the formation of the localized states and the exact form of the energy dispersion law of the quasi-particles. In particular it is shown that the perturbations of the local magnetization in the impure spin 1/2 chains disappear in the absence of the external magnetic field. Using the exact solution for the XY chain it is shown that unless the localized energy levels are formed outside the pseudo-fermion energy band the singularity of the local magnetization existing in the pure chain disappears at an arbitrary distance from the single impurity spin. For the ferromagnetic chain with the ferromagnetically coupled impurity the solution of the Hartree-Fock equations at low temperatures agrees reasonably with the results of the linear spin-wave theory. If the impurity is antiferromagnetically coupled, then, in contrast with the results of the spin -wave theory, the Hartree-Fock approximation agrees with the exact result for the zero-field ground state spin defect at the impurity site. Unlike the previous methods, the technique developed in this work permits investigation of the whole temperature range and predicts the correct Curie-Weiss behavior at sufficiently large temperatures.

  11. Chiral spin liquid emerging between competing magnetic order states in the spin-1/2 J1-J2-J3 kagome Heisenberg model

    NASA Astrophysics Data System (ADS)

    Gong, Shoushu; Zhu, Wei; Balents, Leon; Sheng, Dongning

    2015-03-01

    We studied the extended spin- 1 / 2 kagome model with the first neighbor (J1), the second (J2) and third neighbor (J3) couplings using density matrix renormalization group. We established a quantum phase diagram for 0 <= J 2 <= 0 . 25J1 and 0 <=J3 <=J1 , where we find a q = (0 , 0) Neel phase, a chiral spin liquid (CSL), a cuboc1 phase that breaks both time-reversal and spin rotational symmetries, and a valence-bond solid at the neighbor of the Heisenberg model, where a possible Z2 spin liquid has been previously identified. Interestingly, the classical cuboc1 phase could survive in the spin- 1 / 2 system with strong quantum fluctuations, and the CSL emerges between the q = (0 , 0) and the cuboc1 phases. We discover that the CSL has the short spin correlation pattern consistent with the cuboc1 phase, but the chiral order structure is totally different. The CSL might be understood as a result of the competitions between the q = (0 , 0) and the cuboc1 phases in the presence of strong quantum fluctuations. We further studied the quantum phase transitions from the CSL to the magnetically ordered phases, and to the possible Z2 spin liquid of the Heisenberg kagome model. Interestingly, the exotic continuous topological phase transition might be realized in the system.

  12. Direct and inverse cascades of spin-wave turbulence in spin-1 ferromagnetic spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Fujimoto, Kazuya; Tsubota, Makoto

    2016-03-01

    We theoretically and numerically study spin wave turbulence in spin-1 ferromagnetic spinor Bose-Einstein condensates, finding direct and inverse cascades with power-law behavior. To derive these power exponents analytically, the conventional weak wave turbulence theory is applied to the spin-1 spinor Gross-Pitaevskii equation. Thus we obtain the -7 /3 and -5 /3 power laws in the transverse spin correlation function for the direct and inverse cascades, respectively. To confirm these power laws, numerical calculations are performed that obtain results consistent with these power laws.

  13. A two-parameter continuation method for computing numerical solutions of spin-1 Bose–Einstein condensates

    SciTech Connect

    Wang, Y.-S.; Chien, C.-S.

    2014-01-01

    We describe a novel two-parameter continuation method combined with a spectral-collocation method (SCM) for computing the ground state and excited-state solutions of spin-1 Bose–Einstein condensates (BEC), where the second kind Chebyshev polynomials are used as the basis functions for the trial function space. To compute the ground state solution of spin-1 BEC, we implement the single parameter continuation algorithm with the chemical potential μ as the continuation parameter, and trace the first solution branch of the Gross–Pitaevskii equations (GPEs). When the curve-tracing is close enough to the target point, where the normalization condition of the wave function is going to be satisfied, we add the magnetic potential λ as the second continuation parameter with the magnetization M as the additional constraint condition. Then we implement the two-parameter continuation algorithm until the target point is reached, and the ground state solution of the GPEs is obtained. The excited state solutions of the GPEs can be treated in a similar way. Some numerical experiments on {sup 23}Na and {sup 87}Rb are reported. The numerical results on the spin-1 BEC are the same as those reported in [10]. Further numerical experiments on excited-state solutions of spin-1 BEC suffice to show the robustness and efficiency of the proposed two-parameter continuation algorithm.

  14. Heat Conductivity of the Heisenberg Spin-1 /2 Ladder: From Weak to Strong Breaking of Integrability

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Herbrych, Jacek; Zotos, Xenophon; Brenig, Wolfram

    2016-01-01

    We investigate the heat conductivity κ of the Heisenberg spin-1 /2 ladder at finite temperature covering the entire range of interchain coupling J⊥, by using several numerical methods and perturbation theory within the framework of linear response. We unveil that a perturbative prediction κ ∝J⊥-2 , based on simple golden-rule arguments and valid in the strict limit J⊥→0 , applies to a remarkably wide range of J⊥, qualitatively and quantitatively. In the large J⊥ limit, we show power-law scaling of opposite nature, namely, κ ∝J⊥2. Moreover, we demonstrate the weak and strong coupling regimes to be connected by a broad minimum, slightly below the isotropic point at J⊥=J∥. Reducing temperature T , starting from T =∞ , this minimum scales as κ ∝T-2 down to T on the order of the exchange coupling constant. These results provide for a comprehensive picture of κ (J⊥,T ) of spin ladders.

  15. Stability and internal structure of vortices in spin-1 Bose-Einstein condensates with conserved magnetization

    NASA Astrophysics Data System (ADS)

    Lovegrove, Justin; Borgh, Magnus O.; Ruostekoski, Janne

    2016-03-01

    We demonstrate how conservation of longitudinal magnetization can have pronounced effects on both stability and structure of vortices in the atomic spin-1 Bose-Einstein condensate by providing a systematic characterization of nonsingular and singular vortex states. Constructing spinor wave functions for vortex states that continuously connect ferromagnetic and polar phases, we systematically derive analytic models for nonrotating cores of different singular vortices and for composite defect states with distinct small- and large-distance topology. We explain how the conservation law provides a stabilizing mechanism when the coreless vortex imprinted on the condensate relaxes in the polar regime of interatomic interactions. The resulting structure forms a composite defect: The inner ferromagnetic coreless vortex deforms toward an outer singly quantized polar vortex. We also numerically show how other even more complex hierarchies of vortex-core topologies may be stabilized. Moreover, we analyze the structure of the coreless vortex also in a ferromagnetic condensate and show how reducing magnetization leads to a displacement of the vortex from the trap center and eventually to the deformation and splitting of its core where a singular vortex becomes a lower-energy state. For the case of singular vortices, we find that the stability and the core structure are notably less influenced by the conservation of magnetization.

  16. The ground state of a spin-1 anti-ferromagnetic atomic condensate for Heisenberg limited metrology

    NASA Astrophysics Data System (ADS)

    Wu, Ling-Na; You, Li

    2016-05-01

    The ground state of a spin-1 atomic condensate with anti-ferromagnetic interaction can be applied to quantum metrology approaching the Heisenberg limit. Unlike a ferromagnetic condensate state where individual atomic spins are aligned in the same direction, atoms in an anti-ferromagnetic ground state condensate exist as spin singlet pairs, whose inherent correlation promises metrological precisions beyond the standard quantum limit (SQL) for uncorrelated atoms. The degree of improvement over the SQL is measured by quantum Fisher information (QFI), whose dependence on the ratio of linear Zeeman shift p to spin-dependent atomic interaction c is studied. At a typical value of p = 0 . 4 c corresponding to a magnetic field of 28 . 6 μ G with c = h × 50 Hz (for 23 Na atom condensate in the F = 1 state at a typical density of ~1014cm-3), the scaled QFI can reach ~ 0 . 48 N , which is close to the limits of N for NooN state, or 0 . 5 N for twin-Fock state. We hope our work will stimulate experimental efforts towards reaching the anti-ferromagnetic condensate ground state at extremely low magnetic fields.

  17. Enhancement of spin coherence in a spin-1 Bose-Einstein condensate by dynamical decoupling approaches

    SciTech Connect

    Ning Boyuan; Zhuang Jun; Zhang Wenxian; You, J. Q.

    2011-07-15

    We study the enhancement of spin coherence with periodic, concatenated, or Uhrig dynamical decoupling N-pulse sequences in a spin-1 Bose-Einstein condensate, where the intrinsic dynamical instability in such a ferromagnetically interacting condensate causes spin decoherence and eventually leads to a multiple spatial-domain structure or a spin texture. Our results show that all three sequences successfully enhance the spin coherence by pushing the wave vector of the most unstable mode in the condensate to a larger value. Among the three sequences with the same number of pulses, the concatenated one shows the best performance in preserving the spin coherence. More interestingly, we find that all three sequences exactly follow the same enhancement law, k{sub -}T{sup 1/2}=c, with k{sub -} the wave vector of the most unstable mode, T the sequence period, and c a sequence-dependent constant. Such a law between k{sub -} and T is also derived analytically for an attractive scalar Bose-Einstein condensate subjected to a periodic dynamical decoupling sequence.

  18. Kaleidoscope of quantum phases in a long-range interacting spin-1 chain

    NASA Astrophysics Data System (ADS)

    Gong, Z.-X.; Maghrebi, M. Â. F.; Hu, A.; Foss-Feig, M.; Richerme, P.; Monroe, C.; Gorshkov, A. Â. V.

    2016-05-01

    Motivated directly by recent trapped-ion quantum simulation experiments, we carry out a comprehensive study of the phase diagram of a spin-1 chain with XXZ-type interactions that decay as 1 /rα , using a combination of finite and infinite-size DMRG calculations, spin-wave analysis, and field theory. In the absence of long-range interactions, varying the spin-coupling anisotropy leads to four distinct and well-studied phases: a ferromagnetic Ising phase, a disordered XY phase, a topological Haldane phase, and an antiferromagnetic Ising phase. If long-range interactions are antiferromagnetic and thus frustrated, we find primarily a quantitative change of the phase boundaries. On the other hand, ferromagnetic (nonfrustrated) long-range interactions qualitatively impact the entire phase diagram. Importantly, for α ≲3 , long-range interactions destroy the Haldane phase, break the conformal symmetry of the XY phase, give rise to a new phase that spontaneously breaks a U (1 ) continuous symmetry, and introduce a possibly exotic tricritical point with no direct parallel in short-range interacting spin chains. Importantly, we show that the main signatures of all five phases found could be observed experimentally in the near future.

  19. Proca stars: Gravitating Bose-Einstein condensates of massive spin 1 particles

    NASA Astrophysics Data System (ADS)

    Brito, Richard; Cardoso, Vitor; Herdeiro, Carlos A. R.; Radu, Eugen

    2016-01-01

    We establish that massive complex Abelian vector fields (mass μ) can form gravitating solitons, when minimally coupled to Einstein's gravity. Such Proca stars (PSs) have a stationary, everywhere regular and asymptotically flat geometry. The Proca field, however, possesses a harmonic time dependence (frequency w), realizing Wheeler's concept of geons for an Abelian spin 1 field. We obtain PSs with both a spherically symmetric (static) and an axially symmetric (stationary) line element. The latter form a countable number of families labelled by an integer m ∈Z+. PSs, like (scalar) boson stars, carry a conserved Noether charge, and are akin to the latter in many ways. In particular, both types of stars exist for a limited range of frequencies and there is a maximal ADM mass, Mmax, attained for an intermediate frequency. For spherically symmetric PSs (rotating PSs with m = 1 , 2 , 3), Mmax ≃ 1.058 MPl2 / μ (Mmax ≃ 1.568 , 2.337 , 3.247 MPl2 / μ), slightly larger values than those for (mini-)boson stars. We establish perturbative stability for a subset of solutions in the spherical case and anticipate a similar conclusion for fundamental modes in the rotating case. The discovery of PSs opens many avenues of research, reconsidering five decades of work on (scalar) boson stars, in particular as possible dark matter candidates.

  20. Quasilocal conservation laws in XXZ spin-1/2 chains: Open, periodic and twisted boundary conditions

    NASA Astrophysics Data System (ADS)

    Prosen, Tomaž

    2014-09-01

    A continuous family of quasilocal exact conservation laws is constructed in the anisotropic Heisenberg (XXZ) spin-1/2 chain for periodic (or twisted) boundary conditions and for a set of commensurate anisotropies densely covering the entire easy plane interaction regime. All local conserved operators follow from the standard (Hermitian) transfer operator in fundamental representation (with auxiliary spin s=1/2), and are all even with respect to a spin flip operation. However, the quasilocal family is generated by differentiation of a non-Hermitian highest weight transfer operator with respect to a complex auxiliary spin representation parameter s and includes also operators of odd parity. For a finite chain with open boundaries the time derivatives of quasilocal operators are not strictly vanishing but result in operators localized near the boundaries of the chain. We show that a simple modification of the non-Hermitian transfer operator results in exactly conserved, but still quasilocal operators for periodic or generally twisted boundary conditions. As an application, we demonstrate that implementing the new exactly conserved operator family for estimating the high-temperature spin Drude weight results, in the thermodynamic limit, in exactly the same lower bound as for almost conserved family and open boundaries. Under the assumption that the bound is saturating (suggested by agreement with previous thermodynamic Bethe ansatz calculations) we propose a simple explicit construction of infinite time averages of local operators such as the spin current.

  1. Using the ground state of an antiferromagnetic spin-1 atomic condensate for Heisenberg-limited metrology

    NASA Astrophysics Data System (ADS)

    Wu, Ling-Na; You, L.

    2016-03-01

    We show that the ground state of a spin-1 atomic condensate with antiferromagnetic interactions constitutes a useful resource for quantum metrology upon approaching the Heisenberg limit. Unlike a ferromagnetic condensate state where individual atomic spins are aligned in the same direction, the antiferromagnetic ground-state condensate is a condensate of spin-singlet atom pairs. The inherent correlation between paired atoms allows for parameter estimation at precisions beyond the standard quantum limit (SQL) for uncorrelated atoms. The degree of improvement over the SQL is measured by the scaled quantum Fisher information (QFI), whose dependence on the ratio of linear Zeeman shift p to spin-dependent atomic interaction c is studied. At a typical value of p =0.4 c , which corresponds to a magnetic field of 28.6 μ G for c =50 h Hz (for 23Na atom condensate in the F =1 state at a typical density of ˜1014cm-3 ), the scaled QFI can reach ˜0.48 N , which approaches the limit of 0.5 N for the twin-Fock state |N/2 > +|N/2 > - . Our work encourages experimental efforts to reach the ground state of an antiferromagnetic condensate at a extremely low magnetic field.

  2. Entanglement and quantum phase transitions in matrix-product spin-1 chains

    SciTech Connect

    Alipour, S.; Karimipour, V.; Memarzadeh, L.

    2007-05-15

    We consider a one-parameter family of matrix-product states of spin-1 particles on a periodic chain and study in detail the entanglement properties of such a state. In particular, we calculate exactly the entanglement of one site with the rest of the chain, and the entanglement of two distant sites with each other, and show that the derivative of both these properties diverge when the parameter g of the states passes through a critical point. Such a point can be called a point of quantum phase transition, since at this point the character of the matrix-product state, which is the ground state of a Hamiltonian, changes discontinuously. We also study the finite size effects and show how the entanglement depends on the size of the chain. This later part is relevant to the field of quantum computation where the problem of initial state preparation in finite arrays of qubits or qutrits is important. It is also shown that the entanglement of two sites have scaling behavior near the critical point.

  3. Low-lying {Lambda} baryons with spin 1/2 in two-flavor lattice QCD

    SciTech Connect

    Takahashi, Toru T.; Oka, Makoto

    2010-02-01

    Low-lying {Lambda} baryons with spin 1/2 are analyzed in full (unquenched) lattice QCD. We construct 2x2 cross correlators from flavor SU(3) octet and singlet baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor CP-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the O(a)-improved quark action. Three different {beta}'s, {beta}=1.80, 1.95, and 2.10, are employed, whose corresponding lattice spacings are a=0.2150, 0.1555, and 0.1076 fm. For each cutoff, we use four hopping parameters, ({kappa}{sub val},{kappa}{sub sea}), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity {Lambda} states nearly degenerate at around 1.6 GeV, while no state as low as {Lambda}(1405) is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multiquark pictures of {Lambda}(1405).

  4. Anomalous Curie response of an impurity in a quantum critical spin-1/2 Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Höglund, Kaj; Sandvik, Anders

    2007-03-01

    There is a disagreement concerning the low-temperature (T) magnetic susceptibility χ^zimp˜C/T of a spin-S impurity in a nearly quantum critical antiferromagnetic host. Field-theoretical work [1] predicted an anomalous Curie constant S^2/30 quantum Monte Carlo simulations in order to resolve the controversy. Our main result is for a vacancy in a quantum critical spin-1/2 Heisenberg antiferromagnet on a bilayer lattice. In our susceptibility data for the S=1/2 impurity we observe a Curie constant C=0.262(2). Although the value falls outside the predicted range, it should correspond to an anomalous impurity response, as proposed in Ref. [1]. [1] S. Sachdev, C. Buragohain, and M. Vojta, Science 286, 2479 (1999); M. Vojta, C. Buragohain, and S. Sachdev, Phys. Rev. B 61, 15152 (2000). [2] O. P. Sushkov, Phys. Rev. B 62, 12135 (2000). [3] M. Troyer, Prog. Theor. Phys. Supp. 145, 326 (2002).

  5. Optimal control of the signal-to-noise ratio per unit time of a spin 1/2 particle: The crusher gradient and the radiation damping cases

    SciTech Connect

    Lapert, M.; Glaser, S. J.; Assémat, E.; Sugny, D.

    2015-01-28

    We show to which extent the signal to noise ratio per unit time of a spin 1/2 particle can be maximized. We consider a cyclic repetition of experiments made of a measurement followed by a radio-frequency magnetic field excitation of the system, in the case of unbounded amplitude. In the periodic regime, the objective of the control problem is to design the initial state of the system and the pulse sequence which leads to the best signal to noise performance. We focus on two specific issues relevant in nuclear magnetic resonance, the crusher gradient and the radiation damping cases. Optimal control techniques are used to solve this non-standard control problem. We discuss the optimality of the Ernst angle solution, which is commonly applied in spectroscopic and medical imaging applications. In the radiation damping situation, we show that in some cases, the optimal solution differs from the Ernst one.

  6. Kondo conductance across the smallest spin 1/2 radical molecule

    PubMed Central

    Requist, Ryan; Modesti, Silvio; Baruselli, Pier Paolo; Smogunov, Alexander; Fabrizio, Michele; Tosatti, Erio

    2014-01-01

    Molecular contacts are generally poorly conducting because their energy levels tend to lie far from the Fermi energy of the metal contact, necessitating undesirably large gate and bias voltages in molecular electronics applications. Molecular radicals are an exception because their partly filled orbitals undergo Kondo screening, opening the way to electron passage even at zero bias. Whereas that phenomenon has been experimentally demonstrated for several complex organic radicals, quantitative theoretical predictions have not been attempted so far. It is therefore an open question whether and to what extent an ab initio-based theory is able to make accurate predictions for Kondo temperatures and conductance lineshapes. Choosing nitric oxide (NO) as a simple and exemplary spin 1/2 molecular radical, we present calculations based on a combination of density functional theory and numerical renormalization group (DFT+NRG), predicting a zero bias spectral anomaly with a Kondo temperature of 15 K for NO/Au(111). A scanning tunneling spectroscopy study is subsequently carried out to verify the prediction, and a striking zero bias Kondo anomaly is confirmed, still quite visible at liquid nitrogen temperatures. Comparison shows that the experimental Kondo temperature of about 43 K is larger than the theoretical one, whereas the inverted Fano lineshape implies a strong source of interference not included in the model. These discrepancies are not a surprise, providing in fact an instructive measure of the approximations used in the modeling, which supports and qualifies the viability of the density functional theory and numerical renormalization group approach to the prediction of conductance anomalies in larger molecular radicals. PMID:24367113

  7. Kondo conductance across the smallest spin 1/2 radical molecule.

    PubMed

    Requist, Ryan; Modesti, Silvio; Baruselli, Pier Paolo; Smogunov, Alexander; Fabrizio, Michele; Tosatti, Erio

    2014-01-01

    Molecular contacts are generally poorly conducting because their energy levels tend to lie far from the Fermi energy of the metal contact, necessitating undesirably large gate and bias voltages in molecular electronics applications. Molecular radicals are an exception because their partly filled orbitals undergo Kondo screening, opening the way to electron passage even at zero bias. Whereas that phenomenon has been experimentally demonstrated for several complex organic radicals, quantitative theoretical predictions have not been attempted so far. It is therefore an open question whether and to what extent an ab initio-based theory is able to make accurate predictions for Kondo temperatures and conductance lineshapes. Choosing nitric oxide (NO) as a simple and exemplary spin 1/2 molecular radical, we present calculations based on a combination of density functional theory and numerical renormalization group (DFT+NRG), predicting a zero bias spectral anomaly with a Kondo temperature of 15 K for NO/Au(111). A scanning tunneling spectroscopy study is subsequently carried out to verify the prediction, and a striking zero bias Kondo anomaly is confirmed, still quite visible at liquid nitrogen temperatures. Comparison shows that the experimental Kondo temperature of about 43 K is larger than the theoretical one, whereas the inverted Fano lineshape implies a strong source of interference not included in the model. These discrepancies are not a surprise, providing in fact an instructive measure of the approximations used in the modeling, which supports and qualifies the viability of the density functional theory and numerical renormalization group approach to the prediction of conductance anomalies in larger molecular radicals. PMID:24367113

  8. Collinear order in the frustrated three-dimensional spin-1/2 antiferromagnet Li2CuW2O8

    NASA Astrophysics Data System (ADS)

    Ranjith, K. M.; Nath, R.; Skoulatos, M.; Keller, L.; Kasinathan, D.; Skourski, Y.; Tsirlin, A. A.

    2015-09-01

    Magnetic frustration in three dimensions (3D) manifests itself in the spin-1/2 insulator Li2CuW2O8 . Density-functional band-structure calculations reveal a peculiar spin lattice built of triangular planes with frustrated interplane couplings. The saturation field of 29 T contrasts with the susceptibility maximum at 8.5 K and a relatively low Néel temperature TN≃3.9 K . Magnetic order below TN is collinear with the propagation vector (0 ,1/2 ,0 ) and an ordered moment of 0.65(4) μB according to neutron diffraction data. This reduced ordered moment together with the low maximum of the magnetic specific heat (Cmax/R ≃0.35 ) pinpoint strong magnetic frustration in 3D. Collinear magnetic order suggests that quantum fluctuations play a crucial role in this system, where a noncollinear spiral state would be stabilized classically.

  9. Local magnetic moments in a dinuclear Co{sup 2+} complex as seen by polarized neutron diffraction:Beyond the effective spin-(1/2) model

    SciTech Connect

    Borta, Ana; Luneau, Dominique; Jeanneau, Erwann; Gillon, Beatrice; Gukasov, Arsen; Cousson, Alain; Ciumacov, Iurii; Sakiyama, Hiroshi; Tone, Katsuya; Mikuriya, Masahiro

    2011-05-01

    Polarized neutron diffraction investigations of a paramagnetic molecular dinuclear Co{sup 2+} complex, using the local site susceptibility method, show that the Co{sup 2+} ions carry opposite magnetic moments of 3.1(1) and 3.2(1) {mu}{sub B}, making an angle of 37(1) deg. which is in agreement with the value (39 deg.) provided by the theoretical analysis of the magnetic susceptibility using the model of effective spin 1/2. Polarized neutron diffraction (PND) shows that this dinuclear Co{sup 2+} complex behaves more like a system of two antiferromagnetically coupled ions with spin 3/2, the directions of which are imposed by the distortion axis of the octahedra around each Co{sup 2+} ion due to ligand field. This first application of the local susceptibility tensor method to a molecular compound demonstrates the efficiency of the PND method as a tool for exploring magnetic anisotropy in molecular paramagnets.

  10. Efficient numerical methods for computing ground states of spin-1 Bose–Einstein condensates based on their characterizations

    SciTech Connect

    Bao, Weizhu; Chern, I-Liang; Zhang, Yanzhi

    2013-11-15

    In this paper, we propose efficient numerical methods for computing ground states of spin-1 Bose–Einstein condensates (BECs) with/without the Ioffe–Pritchard magnetic field B(x). When B(x)≠0, a numerical method is introduced to compute the ground states and it is also applied to study properties of ground states. Numerical results suggest that the densities of m{sub F}=±1 components in ground states are identical for any nonzero B(x). In particular, if B(x)≡B≠0 is a constant, the ground states satisfy the single-mode approximation. When B(x)≡0, efficient and simpler numerical methods are presented to solve the ground states of spin-1 BECs based on their ferromagnetic/antiferromagnetic characterizations. Numerical simulations show that our methods are more efficient than those in the literature. In addition, some conjectures are made from our numerical observations.

  11. On the non-relativistic limit of a spin- {1}/{2} particle in a classical gravitational field

    NASA Astrophysics Data System (ADS)

    Bäuerle, G. G. A.; Twelker, H. F.

    1985-04-01

    An external gravitational field modifies the description of a spin- {1}/{2} particle in various ways. For instance, the inner product of Dirac wave functions, and the equal-time anti-commutation relations and the canonical energy-momentum tensor of the quantized Dirac field are modified. This has the following consequences. The Dirac-Hamiltonian (2.29) of a spin- {1}/{2} particle in a time-dependent gravitational field is not Hermitian. Furthermore, the Euler-Lagrange equation and the Heisenberg equation for the quantized Dirac field are not consistent. We obviate these deficiencies by the introduction of the η-field as the fundamental variable instead of the Dirac field. At the same time, the non-relativistic limit is most conveniently discussed in the η-description. For this purpose, we introduce a modification of the Foldy-Wouthuysen transformation.

  12. Spin and quadrupolar orders in the spin-1 bilinear-biquadratic model for iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Luo, Cheng; Datta, Trinanjan; Yao, Dao-Xin

    2016-06-01

    Motivated by the recent experimental and theoretical progress of the magnetic properties in iron-based superconductors, we provide a comprehensive analysis of the extended spin-1 bilinear-biquadratic (BBQ) model on the square lattice. Using a variational approach at the mean-field level, we identify the existence of various magnetic phases, including conventional spin dipolar orders (ferro- and antiferromagnet), novel quadrupolar orders (spin nematic), and mixed dipolar-quadrupolar orders. In contrast to the regular Heisenberg model, the elementary excitations of the spin-1 BBQ model are described by the SU(3) flavor-wave theory. By fitting the experimental spin-wave dispersion, we determine the refined exchange couplings corresponding to the collinear antiferromagnetic iron pnictides. We also present the dynamic structure factors of both spin dipolar and quadrupolar components with connections to the future experiments.

  13. Spin and pseudospin symmetries and the equivalent spectra of relativistic spin-1/2 and spin-0 particles

    SciTech Connect

    Alberto, P.; Castro, A. S. de; Malheiro, M.

    2007-04-15

    We show that the conditions which originate the spin and pseudospin symmetries in the Dirac equation are the same that produce equivalent energy spectra of relativistic spin-1/2 and spin-0 particles in the presence of vector and scalar potentials. The conclusions do not depend on the particular shapes of the potentials and can be important in different fields of physics. When both scalar and vector potentials are spherical, these conditions for isospectrality imply that the spin-orbit and Darwin terms of either the upper component or the lower component of the Dirac spinor vanish, making it equivalent, as far as energy is concerned, to a spin-0 state. In this case, besides energy, a scalar particle will also have the same orbital angular momentum as the (conserved) orbital angular momentum of either the upper or lower component of the corresponding spin-1/2 particle. We point out a few possible applications of this result.

  14. Spin structure of spin-1/2 baryon and spinless meson production amplitudes in photonic and hadronic reactions

    SciTech Connect

    Nakayama, K.; Love, W.G.

    2005-09-01

    The most general spin structures of the spin-1/2 baryon and spinless meson production operator for both photon and nucleon induced reactions are derived from the partial-wave expansions of these reaction amplitudes. The present method provides the coefficients multiplying each spin operator in terms of the partial-wave matrix elements. The result should be useful in studies of these reactions based on partial-wave analyses, especially, when spin observables are considered.

  15. Cooling into the spin-nematic state for a spin-1 Bose gas in an optical lattice

    SciTech Connect

    Chung, M.-C.; Yip Sungkit

    2009-05-15

    The possibility of adiabatically cooling a spin-1 polar Bose gas to a spin-nematic phase is theoretically discussed. The relation between the order parameter of the final spin-nematic phase and the starting temperature of the spinor Bose gas is obtained both using the mean-field approach for high temperature and spin-wave approach for low temperature. We find that there exists a good possibility to reach the spin-nematic ordering starting with spinor antiferromagnetic Bose gases.

  16. Dirac operators on the fuzzy AdS2 with the spins 1/2 and 1

    NASA Astrophysics Data System (ADS)

    Fakhri, H.; Lotfizadeh, M.

    2011-10-01

    It is shown here how the pseudo chirality and Dirac operators with the spins 1/2 and 1 on the commutative and fuzzy AdS2 should be constructed. The finite-dimensional and nonunitary representations of SU(1, 1) carrying the spin degrees of freedom 1/2 and 1 are used for the Dirac fields on commutative and fuzzy AdS2. In the fuzzy case, an explicit description of pseudo generalization of the Ginsparg-Wilson algebra is used to construct projective modules. The projector couplings left angular momentum and spin on the fuzzy AdS2 are used to produce minimum total angular momenta. They are realized by the first two and three representations of the total angular momentum for the spins 1/2 and 1, respectively. The pseudo projectors, the pseudo chirality, and Dirac operators with the spins 1/2 and 1 on the fuzzy AdS2 tend to their corresponding operators in the commutative limit.

  17. Oxygen-17 and copper-63 NMR study of spindynamics in low- dimensional spin 1/2 antiferromagnets

    NASA Astrophysics Data System (ADS)

    Thurber, Kent Robert

    63Cu and 17O nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) experiments are reported on copper-oxide compounds related to high temperature superconductors that are nearly ideal realizations of spin 1/2 Heisenberg antiferromagnets with different geometries of the magnetic interactions: 1 dimensional spin chains, 2 dimensional planes, two coupled chains (two-leg ladder), and three coupled chains (three-leg ladder). Comparison of the spin-lattice relaxation rate, 1/T1, for 63Cu and 17O reveals the wave-vector, q, dependence of low-energy magnetic fluctuations, and 1/T2 G the Gaussian spin-spin relaxation rate provides information about the electron spin correlation length, ξ. In the 1d material, Sr 2CuO3, 171/T1(q = 0) ~ aT + bT2 over the whole temperature range 10 to 700 K. Frequency dependence measurements show that diffusive contributions dominate T1(q ~ 0) for the double chain 1d material, SrCuO2. For the undoped 2d copper oxide material, Sr2CuO2Cl2, we demonstrate that 17O 1/T1 measures the spin wave damping in the undoped antiferromagnet for short wavelengths. We find that the spin wave damping is small, clarifying one of the unique properties of these 2d copper-oxide antiferromagnetic materials: there is a wide temperature range where short range spin excitations exist with long lifetimes, without long range 3-dimensional order. The two-leg ladder materials, SrCu2O3 and A 14Cu24O41 (A = La,Sr,Ca), have a large energy gap for spin excitations. There is a crossover in magnetic fluctuations from temperatures below the spin gap to above the spin gap. For the doped two-leg ladders, the effective doping of the ladders changes with temperature, and this temperature is correlated to the magnetic spin gap energy. The three-leg ladder material, Sr2Cu3O5, demonstrates a crossover in the temperature dependence of the spin correlation length, ξ. At high temperatures, we find the ξ ~ 1/T behavior characteristic of a 1d structure (isolated three

  18. A Fortran 90 program to solve the Hartree-Fock equations for interacting spin- 1/2 > fermions confined in harmonic potentials

    NASA Astrophysics Data System (ADS)

    Pal, Hridis Kumar; Shukla, Alok

    2008-08-01

    A set of weakly interacting spin- 1/2 > Fermions, confined by a harmonic oscillator potential, and interacting with each other via a contact potential, is a model system which closely represents the physics of a dilute gas of two-component fermionic atoms confined in a magneto-optic trap. In the present work, our aim is to present a Fortran 90 computer program which, using a basis set expansion technique, solves the Hartree-Fock (HF) equations for spin- 1/2 > Fermions confined by a three-dimensional harmonic oscillator potential, and interacting with each other via pair-wise delta-function potentials. Additionally, the program can also account for those anharmonic potentials which can be expressed as a polynomial in the position operators x, y, and z. Both the restricted-HF (RHF), and the unrestricted-HF (UHF) equations can be solved for a given number of Fermions, with either repulsive or attractive interactions among them. The option of UHF solutions for such systems also allows us to study possible magnetic properties of the physics of two-component confined atomic Fermi gases, with imbalanced populations. Using our code we also demonstrate that such a system exhibits shell structure, and follows Hund's rule. Program summaryProgram title: trap.x Catalogue identifier: AEBB_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBB_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 17 750 No. of bytes in distributed program, including test data, etc.: 205 138 Distribution format: tar.gz Programming language: mostly Fortran 90 Computer: PCs—SUN, HP Alpha, IBM Operating system: Linux, Solaris, Tru64, AIX Classification: 7.7 Nature of problem: The simplest description of a spin 1/2 >; trapped system at the mean field level is given by the Hartree-Fock method. This

  19. Entanglement in Mixed-Spin (1/2, 3/2) Heisenberg XXZ Model with Dzyaloshinskii-Moriya Interaction

    NASA Astrophysics Data System (ADS)

    Zhou, Chao-Biao; Xiao, Shu-Yuan; Zhang, Shao-Wu; Ran, Yang-Qiang

    2016-02-01

    In this paper, the entanglement in a mixed-spin (1/2, 3/2) Heisenberg XXZ model with Dzyaloshinskii-Moriya (DM) interaction in an inhomogeneous external magnetic field is studied. We not only calculate the ground-state entanglement but also investigate the behaviors of quantum phase transition following the changes of DM interaction and nonuniform magnetic field. More importantly, we note that the DM interaction improves the critical magnetic field B c , the critical temperature T c and broadens the region of entanglement.

  20. Effective spin-1/2 scalar chiral order on kagome lattices in Nd3Sb3Mg2O14

    NASA Astrophysics Data System (ADS)

    Scheie, A.; Sanders, M.; Krizan, J.; Qiu, Y.; Cava, R. J.; Broholm, C.

    2016-05-01

    We introduce Nd3Sb3Mg2O14 with ideal kagome lattices of neodymium ions in ABC stacking. Thermodynamic measurements show a Curie-Weiss temperature of ΘCW=-0.12 K, a Nd3 + spin-1/2 Kramers doublet ground state, and a second-order phase transition at TN=0.56 (2 ) K. Neutron scattering reveals noncoplanar scalar chiral k =0 magnetic order with a correlation length exceeding 400 Å=55 a and an ordered moment of 1.79 (5 ) μB . This order includes a canted ferromagnetic component perpendicular to the kagome planes favored by Dzyaloshinskii-Moriya interactions.

  1. High Resolution Magic Angle Spinning 1H-NMR Metabolic Profiling of Nanoliter Biological Tissues at High Magnetic Field

    SciTech Connect

    Feng, Ju; Hu, Jian Z.; Burton, Sarah D.; Hoyt, David W.

    2013-03-05

    It is demonstrated that a high resolution magic angle spinning 1H-NMR spectrum of biological tissue samples with volumes as small as 150 nanoliters, or 0.15 mg in weight, can be acquired in a few minutes at 21.1 T magnetic field using a commercial 1.6 mm fast-MAS probe with minor modification of the MAS rotor. The strategies of sealing the samples inside the MAS rotor to avoid fluid leakage as well as the ways of optimizing the signal to noise are discussed.

  2. Quantum dynamics of atomic coherence in a spin-1 condensate: Mean-field versus many-body simulation

    NASA Astrophysics Data System (ADS)

    Plimak, L. I.; Weiß, C.; Walser, R.; Schleich, W. P.

    2006-08-01

    We analyse and numerically simulate the full many-body quantum dynamics of a spin-1 condensate in the single spatial mode approximation. Initially, the condensate is in a "ferromagnetic" state with all spins aligned along the y axis and the magnetic field pointing along the z axis. In the course of evolution the spinor condensate undergoes a characteristic change of symmetry, which in a real experiment could be a signature of spin-mixing many-body interactions. The results of our simulations are conveniently visualised within the picture of irreducible tensor operators.

  3. Probing the quantum ground state of a spin-1 Bose-Einstein condensate with cavity transmission spectra

    SciTech Connect

    Zhang, J. M.; Cui, S.; Jing, H.; Zhou, D. L.; Liu, W. M.

    2009-10-15

    We propose to probe the quantum ground state of a spin-1 Bose-Einstein condensate with the transmission spectra of an optical cavity. By choosing a circularly polarized cavity mode with an appropriate frequency, we can realize coupling between the cavity mode and the magnetization of the condensate. The cavity transmission spectra then contain information of the magnetization statistics of the condensate and thus can be used to distinguish the ferromagnetic and antiferromagnetic quantum ground states. This technique may also be useful for continuous observation of the spin dynamics of a spinor Bose-Einstein condensate.

  4. Quasilocal conservation laws from semicyclic irreducible representations of Uq (sl2) in XXZ spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Zadnik, Lenart; Medenjak, Marko; Prosen, Tomaž

    2016-01-01

    We construct quasilocal conserved charges in the gapless (| Δ | ≤ 1) regime of the Heisenberg XXZ spin-1/2 chain, using semicyclic irreducible representations of Uq (sl2). These representations are characterized by a periodic action of ladder operators, which act as generators of the aforementioned algebra. Unlike previously constructed conserved charges, the new ones do not preserve magnetization, i.e. they do not possess the U (1) symmetry of the Hamiltonian. The possibility of application in relaxation dynamics resulting from U (1)-breaking quantum quenches is discussed.

  5. Prospects for spin-1 resonance search at 13 TeV LHC and the ATLAS diboson excess

    NASA Astrophysics Data System (ADS)

    Abe, Tomohiro; Kitahara, Teppei; Nojiri, Mihoko M.

    2016-02-01

    Motivated by ATLAS diboson excess around 2 TeV, we investigate a phenomenology of spin-1 resonances in a model where electroweak sector in the SM is weakly coupled to strong dynamics. The spin-1 resonances, W' and Z', are introduced as effective degrees of freedom of the dynamical sector. We explore several theoretical constraints by investigating the scalar potential of the model as well as the current bounds from the LHC and precision measurements. It is found that the main decay modes are V' → VV and V' → Vh, and the V' width is narrow enough so that the ATLAS diboson excess can be explained. In order to investigate future prospects, we also perform collider simulations at √{s}=13 TeV LHC, and obtain a model independent expected exclusion limit for σ( pp → W' → WZ → JJ). We find a parameter space where the diboson excess can be∫ explained, and are within a reach of the LHC at int dt{L}=10{fb}^{-1}} and √{s}=13 TeV.

  6. Dynamics and stability of stationary states for the spin-1 Bose-Einstein condensates in a standing light wave

    NASA Astrophysics Data System (ADS)

    Wang, Deng-Shan; Han, Wei; Shi, Yuren; Li, Zaidong; Liu, Wu-Ming

    2016-07-01

    The spin-1 Bose-Einstein condensates trapped in a standing light wave can be described by three coupled Gross-Pitaevskii equations with a periodic potential. In this paper, nine families of stationary solutions without phase structures in the form of Jacobi elliptic functions are proposed, and their stabilities are analyzed by both linear stability analysis and dynamical evolutions. Taking the ferromagnetic 87Rb atoms and antiferromagnetic (polar) 23Na atoms as examples, we investigate the stability regions of the nine stationary solutions, which are given in term of elliptic modulus k. It is shown that for the same stationary solution the stability regions of condensates with antiferromagnetic (polar) spin-dependent interactions are larger than that of the condensates with ferromagnetic ones. The dn-dn-dn stationary solution is the most stable solution among the nine families of stationary solutions. Moreover, in the same standing light wave, the spin-1 Bose-Einstein condensates are more stable than the scalar Bose-Einstein condensate.

  7. Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4

    DOE PAGESBeta

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; Wosnitza, J.; Krzystek, J.; Yoshizawa, D.; Hagiwara, M.; Hu, Rongwei; Ryu, Hyejin; Petrovic, C.; et al

    2015-11-27

    We present on high- field electron spin resonance (ESR) studies of magnetic excitations in the spin- 1/2 triangular-lattice antiferromagnet Cs2CuBr4. Frequency- field diagrams of ESR excitations are measured for different orientations of magnetic fields up to 25 T. We show that the substantial zero- field energy gap, Δ ≈ 9.5 K, observed in the low-temperature excitation spectrum of Cs2CuBr4 [Zvyagin et al:, Phys. Rev. Lett. 112, 077206 (2014)], is present well above TN. Noticeably, the transition into the long-range magnetically ordered phase does not significantly affect the size of the gap, suggesting that even below TN the high-energy spin dynamicsmore » in Cs2CuBr4 is determined by short-range-order spin correlations. The experimental data are compared with results of model spin-wave-theory calculations for spin-1/2 triangle-lattice antiferromagnet.« less

  8. General formalism of local thermodynamics with an example: Quantum Otto engine with a spin-1 /2 coupled to an arbitrary spin

    NASA Astrophysics Data System (ADS)

    Altintas, Ferdi; Müstecaplıoǧlu, Ã.-zgür E.

    2015-08-01

    We investigate a quantum heat engine with a working substance of two particles, one with a spin-1 /2 and the other with an arbitrary spin (spin s ), coupled by Heisenberg exchange interaction, and subject to an external magnetic field. The engine operates in a quantum Otto cycle. Work harvested in the cycle and its efficiency are calculated using quantum thermodynamical definitions. It is found that the engine has higher efficiencies at higher spins and can harvest work at higher exchange interaction strengths. The role of exchange coupling and spin s on the work output and the thermal efficiency is studied in detail. In addition, the engine operation is analyzed from the perspective of local work and efficiency. We develop a general formalism to explore local thermodynamics applicable to any coupled bipartite system. Our general framework allows for examination of local thermodynamics even when global parameters of the system are varied in thermodynamic cycles. The generalized definitions of local and cooperative work are introduced by using mean field Hamiltonians. The general conditions for which the global work is not equal to the sum of the local works are given in terms of the covariance of the subsystems. Our coupled spin quantum Otto engine is used as an example of the general formalism.

  9. General formalism of local thermodynamics with an example: Quantum Otto engine with a spin-1/2 coupled to an arbitrary spin.

    PubMed

    Altintas, Ferdi; Müstecaplıoğlu, Özgür E

    2015-08-01

    We investigate a quantum heat engine with a working substance of two particles, one with a spin-1/2 and the other with an arbitrary spin (spin s), coupled by Heisenberg exchange interaction, and subject to an external magnetic field. The engine operates in a quantum Otto cycle. Work harvested in the cycle and its efficiency are calculated using quantum thermodynamical definitions. It is found that the engine has higher efficiencies at higher spins and can harvest work at higher exchange interaction strengths. The role of exchange coupling and spin s on the work output and the thermal efficiency is studied in detail. In addition, the engine operation is analyzed from the perspective of local work and efficiency. We develop a general formalism to explore local thermodynamics applicable to any coupled bipartite system. Our general framework allows for examination of local thermodynamics even when global parameters of the system are varied in thermodynamic cycles. The generalized definitions of local and cooperative work are introduced by using mean field Hamiltonians. The general conditions for which the global work is not equal to the sum of the local works are given in terms of the covariance of the subsystems. Our coupled spin quantum Otto engine is used as an example of the general formalism. PMID:26382378

  10. Spin (1/2){sup +}, spin (3/2){sup +}, and transition magnetic moments of low lying and charmed baryons

    SciTech Connect

    Sharma, Neetika; Dahiya, Harleen; Chatley, P. K.; Gupta, Manmohan

    2010-04-01

    Magnetic moments of the low lying and charmed spin (1/2){sup +} and spin (3/2){sup +} baryons have been calculated in the SU(4) chiral constituent quark model ({chi}CQM) by including the contribution from cc fluctuations. Explicit calculations have been carried out for the contribution coming from the valence quarks, ''quark sea'' polarizations and their orbital angular momentum. The implications of such a model have also been studied for magnetic moments of the low lying spin (3/2){sup +{yields}}(1/2){sup +} and (1/2){sup +{yields}}(1/2){sup +} transitions as well as the transitions involving charmed baryons. The predictions of {chi}CQM not only give a satisfactory fit for the baryons where experimental data is available but also show improvement over the other models. In particular, for the case of {mu}(p), {mu}({Sigma}{sup +}), {mu}({Xi}{sup 0}), {mu}({Lambda}), Coleman-Glashow sum rule for the low lying spin (1/2){sup +} baryons and {mu}({Delta}{sup +}), {mu}({Omega}{sup -}) for the low lying spin (3/2){sup +} baryons, we are able to achieve an excellent agreement with data. For the spin (1/2){sup +} and spin (3/2){sup +} charmed baryon magnetic moments, our results are consistent with the predictions of the QCD sum rules, light cone sum rules and spectral sum rules. For the cases where light quarks dominate in the valence structure, the sea and orbital contributions are found to be fairly significant however, they cancel in the right direction to give the correct magnitude of the total magnetic moment. On the other hand, when there is an excess of heavy quarks, the contribution of the quark sea is almost negligible, for example, {mu}({Omega}{sub c}{sup 0}), {mu}({Lambda}{sub c}{sup +}), {mu}({Xi}{sub c}{sup +}), {mu}({Xi}{sub c}{sup 0}), {mu}({Omega}{sub cc}{sup +}), {mu}({Omega}{sup -}), {mu}({Omega}{sub c}*{sup 0}), {mu}({Omega}{sub cc}*{sup +}), and {mu}({Omega}{sub ccc}*{sup ++}). The effects of configuration mixing and quark masses have also been

  11. Gapless quantum spin liquid ground state in the two-dimensional spin-1/2 triangular antiferromagnet YbMgGaO4

    PubMed Central

    Li, Yuesheng; Liao, Haijun; Zhang, Zhen; Li, Shiyan; Jin, Feng; Ling, Langsheng; Zhang, Lei; Zou, Youming; Pi, Li; Yang, Zhaorong; Wang, Junfeng; Wu, Zhonghua; Zhang, Qingming

    2015-01-01

    Quantum spin liquid (QSL) is a novel state of matter which refuses the conventional spin freezing even at 0 K. Experimentally searching for the structurally perfect candidates is a big challenge in condensed matter physics. Here we report the successful synthesis of a new spin-1/2 triangular antiferromagnet YbMgGaO4 with symmetry. The compound with an ideal two-dimensional and spatial isotropic magnetic triangular-lattice has no site-mixing magnetic defects and no antisymmetric Dzyaloshinsky-Moriya (DM) interactions. No spin freezing down to 60 mK (despite θw ~ −4 K), the power-law temperature dependence of heat capacity and nonzero susceptibility at low temperatures suggest that YbMgGaO4 is a promising gapless (≤|θw|/100) QSL candidate. The residual spin entropy, which is accurately determined with a non-magnetic reference LuMgGaO4, approaches zero (<0.6%). This indicates that the possible QSL ground state (GS) of the frustrated spin system has been experimentally achieved at the lowest measurement temperatures. PMID:26552727

  12. Interplay of interchain interactions and exchange anisotropy: Stability and fragility of multipolar states in spin-1/2 quasi-one-dimensional frustrated helimagnets

    NASA Astrophysics Data System (ADS)

    Nishimoto, Satoshi; Drechsler, Stefan-Ludwig; Kuzian, Roman; Richter, Johannes; van den Brink, Jeroen

    2015-12-01

    We quantify the stability of the formation of multipolar states against always present interchain couplings in quasi-one-dimensional spin-1/2 chain systems with a frustrating in-chain J1-J2 exchange, including parameter regimes that are of direct relevance to many edge-shared cuprate spin-chain compounds. Three representative types of antiferromagnetic interchain coupling and the presence of uniaxial exchange anisotropy are considered. The magnetic phase diagrams are determined by density matrix renormalization group calculations and completed by very accurate analytic and numerical results for the nematic and the dipolar phases employing the hard-core-boson approach. We establish that a sizable interchain coupling has a strong influence on the possible instability of multipolar phases at high magnetic fields in the vicinity of the saturation fields in favor of the usual dipolar one-magnon phase. Moreover, skew interchain couplings strongly affect the pitch of spiral states. Our theoretical results bring to the fore candidate materials close to quantum nematic/triatic ordering.

  13. The ± J model for the mixed-spin 1/2 and 3/2 Blume-Capel model

    NASA Astrophysics Data System (ADS)

    Albayrak, Erhan

    2016-08-01

    The effects of the bimodal bilinear exchange interaction, ± J model, are investigated for the mixed-spin 1/2 and 3/2 Blume-Capel (BC) model on the Bethe lattice (BL). The bilinear exchange interaction is either turned on ferrimagnetically (J > 0) or turned off antiferrimagnetically (J < 0) with probabilities p and 1 - p for the nearest-neighbor sites on the BL. The phase diagrams of the model are obtained with the inclusion of the crystal field interactions on the sites of spin-3/2 for the coordination number, q=3,4 and 6, for given p values. It was found that the model gives either second- or first-order phase transition lines for each given value of p. The temperatures of these lines increase with the increasing values of q.

  14. Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy.

    PubMed

    Ren, Jie; Liu, Guang-Hua; You, Wen-Long

    2015-03-18

    We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain numerically. By using the density-matrix renormalization group method, the effects of the alternating single-site anisotropy D on fidelity susceptibility are investigated. Its relation with the quantum phase transition is analyzed. It is found that the quantum phase transition from the Haldane spin liquid to periodic Néel spin solid can be well characterized by the fidelity. Finite size scaling of fidelity susceptibility shows a power-law divergence at criticality, which indicates the quantum phase transition is of second order. The results are confirmed by the second derivative of the ground-state energy. We also study the relationship between the entanglement entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from these quantum information observables agree well with each other. PMID:25707024

  15. A relativistic one-particle Time of Arrival operator for a free spin- 1 / 2 particle in (1 + 1) dimensions

    NASA Astrophysics Data System (ADS)

    Bunao, Joseph; Galapon, Eric A.

    2015-05-01

    As a follow-up to a recent study in the spin-0 case (Bunao and Galapon, 2015), we construct a one-particle Time of Arrival (TOA) operator conjugate to a Hamiltonian describing a free relativistic spin- 1 / 2 particle in one spatial dimension. Upon transformation in a representation where the Hamiltonian is diagonal, it turns out that the constructed operator consists of an operator term T ˆ whose action is the same as in the spin-0 case, and another operator term Tˆ0 which commutes with the Hamiltonian but breaks invariance under parity inversion. If we must impose this symmetry on our TOA operator, then we can throw away Tˆ0 so that the TOA operator is just T ˆ .

  16. Compensation temperature of the two-dimension mixed spin-1 and spin-3/2 anisotropic Heisenberg ferrimagnet

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Hu, Ai-Yuan; Wang, Huai-Yu

    2016-08-01

    We study a two-dimensional Heisenberg ferrimagnet composed of spin-1 and spin-3/2 sublattices considering both exchange and single-ion anisotropies. The adjoint effects of the two anisotropies on the possible compensation point are investigated. It is concluded that a primary condition for the compensation point to appear is that the single-ion anisotropy of the smaller spins should be nonzero and be greater than a certain value which depends on other parameters. The exchange anisotropy can raise the compensation point slightly. The thermodynamic functions are evaluated. All the thermodynamic functions with various parameter values are smooth no matter whether there is a compensation point or not. Thus, from the thermodynamic functions, one is unable to judge if the compensation occurs.

  17. Quantum enhanced measurement of rotations with a spin-1 Bose-Einstein condensate in a ring trap

    NASA Astrophysics Data System (ADS)

    Nolan, Samuel P.; Sabbatini, Jacopo; Bromley, Michael W. J.; Davis, Matthew J.; Haine, Simon A.

    2016-02-01

    We present a model of a spin-squeezed rotation sensor utilizing the Sagnac effect in a spin-1 Bose-Einstein condensate in a ring trap. The two input states for the interferometer are seeded using Raman pulses with Laguerre-Gauss beams and are amplified by the bosonic enhancement of spin-exchange collisions, resulting in spin-squeezing and potential quantum enhancement of the interferometry. The ring geometry has an advantage over separated beam path atomic rotation sensors due to the uniform condensate density. We model the interferometer both analytically and numerically for realistic experimental parameters and find that significant quantum enhancement is possible, but this enhancement is partially degraded when working in a regime with strong atomic interactions.

  18. Exact results for the spin-1 Ising model on pure "square" Husimi lattices: Critical temperatures and spontaneous magnetization

    NASA Astrophysics Data System (ADS)

    Jurčišinová, E.; Jurčišin, M.

    2016-02-01

    We investigate the second order phase transitions of the ferromagnetic spin-1 Ising model on pure Husimi lattices built up from elementary squares with arbitrary values of the coordination number. It is shown that the critical temperatures of the second order phase transitions are driven by a single equation simultaneously on all such lattices. It is also shown that for arbitrary given value of the coordination number this equation is equivalent to the corresponding polynomial equation. The explicit form of these polynomial equations is present for the lattices with the coordination numbers z = 4 , 6, and 8. It is proven that, at least for the small values of the coordination number, the positions of the critical temperatures are uniquely determined. In addition, it is shown that the properties of all phases of the model are also driven by the corresponding single equations simultaneously on all pure Husimi lattices built up from elementary squares. The spontaneous magnetization of the model is investigated in detail.

  19. Enhancement of tunneling density of states at a Y junction of spin-1/2 Tomonaga-Luttinger liquid wires

    NASA Astrophysics Data System (ADS)

    Mardanya, Sougata; Agarwal, Amit

    2015-07-01

    We calculate the tunneling density of states (TDOS) in a dissipationless three-wire junction of interacting spin-1/2 electrons, and find an anomalous enhancement of the TDOS in the zero-bias limit, even for repulsive interactions for several bosonic fixed points. This enhancement is physically related to the reflection of holes from the junction for incident electrons, and it occurs only in the vicinity of the junction (x

  20. Composite nonlinear structure within the magnetosonic soliton interactions in a spin-1/2 degenerate quantum plasma

    SciTech Connect

    Han, Jiu-Ning Luo, Jun-Hua; Li, Jun-Xiu; Li, Sheng-Chang; Liu, Shi-Wei; Yang, Yang; Duan, Wen-Shan; Han, Juan-Fang

    2015-06-15

    We study the basic physical properties of composite nonlinear structure induced by the head-on collision of magnetosonic solitons. Solitary waves are assumed to propagate in a quantum electron-ion magnetoplasma with spin-1/2 degenerate electrons. The main interest of the present work is to investigate the time evolution of the merged composite structure during a specific time interval of the wave interaction process. We consider three cases of colliding-situation, namely, compressive-rarefactive solitons interaction, compressive-compressive solitons interaction, and rarefactive-rarefactive solitons interaction, respectively. Compared with the last two colliding cases, the changing process of the composite structure is more complex for the first situation. Moreover, it is found that they are obviously different for the last two colliding cases.

  1. Wigner-Yanase skew information and quantum phase transition in one-dimensional quantum spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Lei, Shuguo; Tong, Peiqing

    2016-04-01

    The quantum coherence based on Wigner-Yanase skew information and its relations with quantum phase transitions (QPTs) in one-dimensional quantum spin-1/2 chains are studied. Different from those at the critical point (CP) of the Ising transition in the transverse-field XY chain, the single-spin quantum coherence and the two-spin local σ ^z quantum coherence are extremal at the CP of the anisotropy transition, and the first-order derivatives of the two-spin local σ ^x and σ ^y quantum coherence have logarithmic divergence with the chain size. For the QPT between the gapped and gapless phases in the chain with three-spin interactions, however, no finite-size scaling behavior of the derivatives of quantum coherence is found.

  2. Exactly solvable spin-1 Ising-Heisenberg diamond chain with the second-neighbor interaction between nodal spins.

    PubMed

    Hovhannisyan, V V; Strečka, J; Ananikian, N S

    2016-03-01

    The spin-1 Ising-Heisenberg diamond chain with the second-neighbor interaction between nodal spins is rigorously solved using the transfer-matrix method. In particular, exact results for the ground state, magnetization process and specific heat are presented and discussed. It is shown that further-neighbor interaction between nodal spins gives rise to three novel ground states with a translationally broken symmetry, but at the same time, does not increases the total number of intermediate plateaus in a zero-temperature magnetization curve compared with the simplified model without this interaction term. The zero-field specific heat displays interesting thermal dependencies with a single- or double-peak structure. PMID:26836749

  3. Exactly solvable spin-1 Ising-Heisenberg diamond chain with the second-neighbor interaction between nodal spins

    NASA Astrophysics Data System (ADS)

    Hovhannisyan, V. V.; Strečka, J.; Ananikian, N. S.

    2016-03-01

    The spin-1 Ising-Heisenberg diamond chain with the second-neighbor interaction between nodal spins is rigorously solved using the transfer-matrix method. In particular, exact results for the ground state, magnetization process and specific heat are presented and discussed. It is shown that further-neighbor interaction between nodal spins gives rise to three novel ground states with a translationally broken symmetry, but at the same time, does not increases the total number of intermediate plateaus in a zero-temperature magnetization curve compared with the simplified model without this interaction term. The zero-field specific heat displays interesting thermal dependencies with a single- or double-peak structure.

  4. Degeneracies and exotic phases in an isotropic frustrated spin-1/2 chain

    NASA Astrophysics Data System (ADS)

    Parvej, Aslam; Kumar, Manoranjan

    2016-03-01

    In the presence of an axial magnetic field, a frustrated isotropic J1 - J2 model system shows many exotic phases, such as vector chiral and multipolar phases. In this paper, the phase boundaries of these exotic phases are calculated based on the order parameters, energy level crossings and magnetization jumps in the system. The order parameter of the vector chiral phase is calculated using the broken symmetry states at a finite magnetic field. The exact diagonalization and the density matrix renormalization group results are used to show that the vector chiral phase exists only in a narrow range of J2/J1 parameter space. In the quadrupolar phase, the magnetization jumps can be associated with the binding energy of two magnons localized at two different legs of the zigzag chain. The energy level crossings and degeneracies in the presence of the axial magnetic field are studied in detail using the exact diagonalization method.

  5. Finite temperature dynamics of spin-1/2 chains with symmetry breaking interactions

    NASA Astrophysics Data System (ADS)

    Manmana, Salvatore R.; Tiegel, Alexander C.; Pruschke, Thomas; Honecker, Andreas

    I will discuss recent developments for flexible matrix product state (MPS) approaches to calculate finite-temperature spectral functions of low-dimensional strongly correlated quantum systems. The main focus will be on a Liouvillian formulation. The resulting algorithm does not specifically depend on the MPS formulation, but is applicable for any wave function based approach which can provide a purification of the density matrix, opening the way for further developments of numerical methods. Based on MPS results for various spin chains, in particular systems with Dzyaloshinskii-Moriya interactions caused by spin-orbit coupling and dimerized chains, I will discuss how symmetry breaking interactions change the nature of the finite-temperature dynamic spin structure factor obtained in ESR and neutron scattering experiments. We acknowledge funding by the Helmholtz Virtual Institute ``New States of Matter and Their Excitations''.

  6. The Operator Product Expansion Beyond Leading Order for Spin-1/2 Fermions

    NASA Astrophysics Data System (ADS)

    Emmons, Samuel; Kang, Daekyoung; Platter, Lucas

    2016-05-01

    Strongly interacting systems of ultracold, two-component fermions have been studied using various techniques for many years. One technique that has been applied is a quantum field theoretical formulation of the zero-range model. In this framework, the Operator Product Expansion was used to derive universal relations for systems with a large scattering length. This corroborated and extended the work of Tan. We calculate finite range corrections to the momentum distribution using the OPE framework and demonstrate the utility of including the 1 /k6 tail from the OPE for the momentum distribution. Corrections to the universal relations for the system are calculated and expressed in terms of the S-wave effective range and an additional quantity D similar to Tan's contact which, in addition to the contact, relates various physical observables. We compare our results with quantum Monte Carlo calculations for the two-component Fermi gas with large scattering length. NSF Grant No. PHY-1516077; U.S. DOE Office of Science, Office of Nuclear Physics Contract Nos. DE-AC52-06NA25396, DE-AC05-00OR22725, an Early Career Research Award; LANL/LDRD Program.

  7. Resonances of Spin-1/2 Fermions in Eddington-Inspired Born-Infeld Gravity

    NASA Astrophysics Data System (ADS)

    Fu, Qi-Ming; Zhao, Li; Du, Yun-Zhi; Gu, Bao-Min

    2016-03-01

    We investigate the fermionic resonances for both chiralities in five-dimensional Eddington-inspired Born-Infeld (EiBI) theory. In order to localize fermion on the brane, it needs to be considered the Yukawa coupling between the fermion and the background scalar field. In our models, since the background scalar field has kink, double kink, or anti-kink solution, the system has rich resonant Kaluza–Klein (KK) modes structure. The massive KK fermionic modes feel a volcano potential, which result in a fermionic zero mode and a set of continuous massive KK modes. The inner structure of the branes and a free parameter in background scalar field influence the resonant behaviors of the massive KK fermions. Supported in part by the National Natural Science Foundation of China under Grant No. 11075065, the Huo Ying-Dong Education Foundation of Chinese Ministry of Education under Grant No. 121106 and the Fundamental Research Funds for the Central Universities under Grant No. lzujbky-2014-31

  8. Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3Nanosheets

    NASA Astrophysics Data System (ADS)

    Weber, Daniel; Schoop, Leslie M.; Duppel, Viola; Lippmann, Judith M.; Nuss, Jürgen; Lotsch, Bettina V.

    2016-06-01

    Spin $\\frac{1}{2}$ honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still of demand. Here, we report the exfoliation of the magnetic semiconductor $\\alpha$-RuCl$_3$ into the first halide monolayers and the magnetic characterization of the spin $\\frac{1}{2}$ honeycomb arrangement of turbostratically stacked RuCl$_3$ monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin $\\frac{1}{2}$ state by electron injection into the layers. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at T$_N$ = 7 K in the in-plane direction, while the magnetic properties in the out-of-plane direction vastly differ from bulk $\\alpha$-RuCl$_3$. The macroscopic pellets of RuCl$_3$ therefore behave like a stack of monolayers without any symmetry relation in the stacking direction. The deliberate introduction of turbostratic disorder to manipulate the spin structure of RuCl$_3$ is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model.

  9. Singularities of the dynamical structure factors of the spin-1/2 XXX chain at finite magnetic field

    NASA Astrophysics Data System (ADS)

    Carmelo, J. M. P.; Sacramento, P. D.; Machado, J. D. P.; Campbell, D. K.

    2015-10-01

    We study the longitudinal and transverse spin dynamical structure factors of the spin-1/2 XXX chain at finite magnetic field h, focusing in particular on the singularities at excitation energies in the vicinity of the lower thresholds. While the static properties of the model can be studied within a Fermi-liquid like description in terms of pseudoparticles, our derivation of the dynamical properties relies on the introduction of a form of the ‘pseudofermion dynamical theory’ (PDT) of the 1D Hubbard model suitably modified for the spin-only XXX chain and other models with two pseudoparticle Fermi points. Specifically, we derive the exact momentum and spin-density dependences of the exponents {{\\zeta}τ}(k) controlling the singularities for both the longitudinal ≤ft(τ =l\\right) and transverse ≤ft(τ =t\\right) dynamical structure factors for the whole momentum range k\\in ]0,π[ , in the thermodynamic limit. This requires the numerical solution of the integral equations that define the phase shifts in these exponents expressions. We discuss the relation to neutron scattering and suggest new experiments on spin-chain compounds using a carefully oriented crystal to test our predictions.

  10. Singularities of the dynamical structure factors of the spin-1/2 XXX chain at finite magnetic field.

    PubMed

    Carmelo, J M P; Sacramento, P D; Machado, J D P; Campbell, D K

    2015-10-14

    We study the longitudinal and transverse spin dynamical structure factors of the spin-1/2 XXX chain at finite magnetic field h, focusing in particular on the singularities at excitation energies in the vicinity of the lower thresholds. While the static properties of the model can be studied within a Fermi-liquid like description in terms of pseudoparticles, our derivation of the dynamical properties relies on the introduction of a form of the 'pseudofermion dynamical theory' (PDT) of the 1D Hubbard model suitably modified for the spin-only XXX chain and other models with two pseudoparticle Fermi points. Specifically, we derive the exact momentum and spin-density dependences of the exponents ζ(τ)(k) controlling the singularities for both the longitudinal (τ = l) and transverse (τ = t) dynamical structure factors for the whole momentum range k ∈ ]0,π[, in the thermodynamic limit. This requires the numerical solution of the integral equations that define the phase shifts in these exponents expressions. We discuss the relation to neutron scattering and suggest new experiments on spin-chain compounds using a carefully oriented crystal to test our predictions. PMID:26403307

  11. Heat Conductivity of the Heisenberg Spin-1/2 Ladder: From Weak to Strong Breaking of Integrability.

    PubMed

    Steinigeweg, Robin; Herbrych, Jacek; Zotos, Xenophon; Brenig, Wolfram

    2016-01-01

    We investigate the heat conductivity κ of the Heisenberg spin-1/2 ladder at finite temperature covering the entire range of interchain coupling J(⊥), by using several numerical methods and perturbation theory within the framework of linear response. We unveil that a perturbative prediction κ∝J(⊥)(-2), based on simple golden-rule arguments and valid in the strict limit J(⊥)→0, applies to a remarkably wide range of J(⊥), qualitatively and quantitatively. In the large J(⊥) limit, we show power-law scaling of opposite nature, namely, κ∝J(⊥)(2). Moreover, we demonstrate the weak and strong coupling regimes to be connected by a broad minimum, slightly below the isotropic point at J(⊥)=J(∥). Reducing temperature T, starting from T=∞, this minimum scales as κ∝T(-2) down to T on the order of the exchange coupling constant. These results provide for a comprehensive picture of κ(J(⊥),T) of spin ladders. PMID:26799041

  12. Effect of Dzyaloshinskii-Moriya interaction on phase diagrams of spin-1 Heisenberg-Ising alternating chains

    NASA Astrophysics Data System (ADS)

    Liu, Guang-Hua; Dou, Jun-Ya; Lu, Peng

    2016-03-01

    The effect of the Dzyaloshinskii-Moriya interaction (DMI) on ground-state phase diagrams of spin-1 Heisenberg-Ising alternating chains is investigated by the infinite time-evolving block decimation method. Three rich phase diagrams for three cases with different DMIs are obtained and discussed systematically. The DMI on even bonds plays a key role in the ground-state phase diagram, especially the appearance of the Haldane phase. However, the DMI on odd bonds seems to have very weak effect on the phase diagram. Both the odd- and even-string orders become nonzero in the Haldane phase, and have their maximum values at θ = π. For the odd-dimer phase, the even-string correlator vanishes absolutely despite varying θ, but a double-peak structure of the odd-string correlator is observed. Odd-string correlator becomes maximum at θ = π / 2 and 3 π / 2, but vanishes at θ = π. It indicates that the generalized string correlator can be used to distinguish the odd-dimer from the Haldane phase. Doubly degenerate entanglement spectrum is observed in the Haldane phase, which can be regarded as a clear signature of the existence of topological orders. Strong enough transverse nearest-neighbor correlations are found to be very important for the appearance of the Haldane and the odd-dimer phases.

  13. Coupled antiferromagnetic spin-1/2 chains in green dioptase Cu6[Si6O18] .6 H2O

    NASA Astrophysics Data System (ADS)

    Podlesnyak, A.; Anovitz, L. M.; Kolesnikov, A. I.; Matsuda, M.; Prisk, T. R.; Toth, S.; Ehlers, G.

    2016-02-01

    In this paper, we report inelastic neutron scattering measurements of the magnetic excitations of green dioptase Cu6[Si6O18] .6 H2O . The observed spectrum contains two magnetic modes and a prominent spin gap that is consistent with the ordered ground state of Cu moments coupled antiferromagnetically in spiral chains along the c axis and ferromagnetically in a b planes on the hexagonal cell. The data are in excellent agreement with a spin-1/2 Hamiltonian that includes antiferromagnetic nearest-neighbor intrachain coupling Jc=10.6 (1 ) meV, ferromagnetic interchain coupling Ja b=-1.2 (1 ) meV, and exchange anisotropy Δ Jc=0.14 (1 ) meV. We calculated the sublattice magnetization to be strongly reduced, ˜0.39 μB . This appears compatible with a reduced Néel temperature, TN=14.5 K≪Jc , and can be explained by a presence of quantum spin fluctuations.

  14. Bound states of two spin-(1/2) fermions in a synthetic non-Abelian gauge field

    SciTech Connect

    Vyasanakere, Jayantha P.; Shenoy, Vijay B.

    2011-03-01

    We study the bound states of two spin-(1/2) fermions interacting via a contact attraction (characterized by a scattering length) in the singlet channel in three-dimensional space in presence of a uniform non-Abelian gauge field. The configuration of the gauge field that generates a Rashba-type spin-orbit interaction is described by three coupling parameters ({lambda}{sub x},{lambda}{sub y},{lambda}{sub z}). For a generic gauge field configuration, the critical scattering length required for the formation of a bound state is negative, i.e., shifts to the ''BCS side'' of the resonance. Interestingly, we find that there are special high-symmetry configurations (e.g., {lambda}{sub x}={lambda}{sub y}={lambda}{sub z}) for which there is a two-body bound state for anyscattering length however small and negative. Remarkably, the bound-state wave functions obtained for such configurations have nematic spin structure similar to those found in liquid {sup 3}He. Our results show that the BCS-BEC (Bose-Einstein condensation) crossover is drastically affected by the presence of a non-Abelian gauge field. We discuss possible experimental signatures of our findings both at high and low temperatures.

  15. Localization and quasilocalization of a spin-1 /2 fermion field on a two-field thick braneworld

    NASA Astrophysics Data System (ADS)

    Guo, Heng; Xie, Qun-Ying; Fu, Chun-E.

    2015-11-01

    Localization of a spin-1 /2 fermion on the braneworld is an important and interesting problem. It is well known that a five-dimensional free massless fermion Ψ minimally coupled to gravity cannot be localized on the Randall-Sundrum braneworld. In order to trap such a fermion, the coupling between the fermion and bulk scalar fields should be introduced. In this paper, localization and quasilocalization of a bulk fermion on the thick braneworld generated by two scalar fields (a kink scalar ϕ and a dilaton scalar π ) are investigated. Two types of couplings between the fermion and two scalars are considered. One coupling is the usual Yukawa coupling -η Ψ ¯ϕ Ψ between the fermion and kink scalar, another one is λ Ψ ¯ΓM∂Mπ γ5Ψ between the fermion and dilaton scalar. The left-chiral fermion zero mode can be localized on the brane, and both the left- and right-chiral fermion massive Kaluza-Klein modes may be localized or quasilocalized. Hence the four-dimensional massless left-chiral fermion and massive Dirac fermions, whose lifetime is infinite or finite, can be obtained on the brane.

  16. Suppression of SPIN1-mediated PI3K-Akt pathway by miR-489 increases chemosensitivity in breast cancer.

    PubMed

    Chen, Xu; Wang, Ya-Wen; Xing, Ai-Yan; Xiang, Shuai; Shi, Duan-Bo; Liu, Lei; Li, Yan-Xiang; Gao, Peng

    2016-08-01

    Drug resistance is one of the major obstacles for improving the prognosis of breast cancer patients. Increasing evidence has linked the association of aberrantly expressed microRNAs (miRNAs) with tumour development and progression as well as chemoresistance. Despite recent advances, there is still little known about the potential role and mechanism of miRNAs in breast cancer chemoresistance. Here we describe that 16 miRNAs were found to be significantly down-regulated and 11 up-regulated in drug-resistant breast cancer tissues compared with drug-sensitive tissues, using a miRNA microarray. The results also showed miR-489 to be one of the most down-regulated miRNAs in drug-resistant tissues and cell lines, as confirmed by miRNA microarray screening and real-time quantitative PCR. A decrease in miR-489 expression was associated with chemoresistance as well as lymph node metastasis, increased tumour size, advanced pTNM stage and poor prognosis in breast cancer. Functional analysis revealed that miR-489 increased breast cancer chemosensitivity and inhibited cell proliferation, migration and invasion, both in vitro and in vivo. Furthermore, SPIN1, VAV3, BCL2 and AKT3 were found to be direct targets of miR-489. SPIN1 was significantly elevated in drug-resistant and metastatic breast cancer tissues and inversely correlated with miR-489 expression. High expression of SPIN1 was associated with higher histological grade, lymph node metastasis, advanced pTNM stage and positive progesterone receptor (PR) status. Increased SPIN1 expression enhanced cell migration and invasion, inhibited apoptosis and partially antagonized the effects of miR-489 in breast cancer. PIK3CA, AKT, CREB1 and BCL2 in the PI3K-Akt signalling pathway, demonstrated to be elevated in drug-resistant breast cancer tissues, were identified as downstream effectors of SPIN1. It was further found that either inhibition of SPIN1 or overexpression of miR-489 suppressed the PI3K-Akt signalling pathway. These data

  17. Comment on ``Sodium Pyroxene NaTiSi2O6: Possible Haldane Spin-1 Chain System''

    NASA Astrophysics Data System (ADS)

    Streltsov, S. V.; Popova, O. A.; Khomskii, D. I.

    2006-06-01

    A Comment on the Letter by Zoran S. Popović, Zeljko V. Šlijivančanin, and Filip R. Vukajlović, Phys. Rev. Lett. 93, 036401 (2004).PRLTAO0031-900710.1103/PhysRevLett.93.036401. The authors of the Letter offer a Reply.

  18. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel A.

    2015-06-01

    We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.

  19. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    SciTech Connect

    Andreev, Pavel A.

    2015-06-15

    We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.

  20. Ground-state phases of the spin-1 J1-J2 Heisenberg antiferromagnet on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Li, P. H. Y.; Bishop, R. F.

    2016-06-01

    We study the zero-temperature quantum phase diagram of a spin-1 Heisenberg antiferromagnet on the honeycomb lattice with both nearest-neighbor exchange coupling J1>0 and frustrating next-nearest-neighbor coupling J2≡κ J1>0 , using the coupled cluster method implemented to high orders of approximation, and based on model states with different forms of classical magnetic order. For each we calculate directly in the bulk thermodynamic limit both ground-state low-energy parameters (including the energy per spin, magnetic order parameter, spin stiffness coefficient, and zero-field uniform transverse magnetic susceptibility) and their generalized susceptibilities to various forms of valence-bond crystalline (VBC) order, as well as the energy gap to the lowest-lying spin-triplet excitation. In the range 0 <κ <1 we find evidence for four distinct phases. Two of these are quasiclassical phases with antiferromagnetic long-range order, one with two-sublattice Néel order for κ <κc1=0.250(5 ) , and another with four-sublattice Néel-II order for κ >κc 2=0.340 (5 ) . Two different paramagnetic phases are found to exist in the intermediate region. Over the range κc1<κ<κci=0.305 (5 ) we find a gapless phase with no discernible magnetic order, which is a strong candidate for being a quantum spin liquid, while over the range κci<κ <κc 2 we find a gapped phase, which is most likely a lattice nematic with staggered dimer VBC order that breaks the lattice rotational symmetry.

  1. Exploring the global entanglement and quantum phase transition in the spin 1/2 XXZ model with Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Yang; Shi, Jia-Dong; Wang, Dong; Ye, Liu

    2016-01-01

    We study the global entanglement and quantum phase transition with the anisotropy parameter and Dzyaloshinskii-Moriya (DM) interaction by methodology of quantum renormalization group within a spin 1/2 XXZ model. It has been shown that the global entanglement can develop two different fixed values, which can exhibit quantum phase transition at the critical point, and DM interaction not only can control the occurrence of the critical point, but also can recover the spoiled three-block entanglement. The behavior of the three-block global entanglement of this large 1D spin 1/2 XXZ model with DM interaction can be revealed in this paper. It turns out that the critical exponent had a relation with the correlation length in the neighborhood of the critical point. Furthermore, the scaling behavior and nonanalytic phenomenon in the spin chains are disclosed.

  2. Bogoliubov theory and Lee-Huang-Yang corrections in spin-1 and spin-2 Bose-Einstein condensates in the presence of the quadratic Zeeman effect

    SciTech Connect

    Uchino, Shun; Kobayashi, Michikazu; Ueda, Masahito

    2010-06-15

    We develop Bogoliubov theory of spin-1 and spin-2 Bose-Einstein condensates (BECs) in the presence of a quadratic Zeeman effect, and derive the Lee-Huang-Yang (LHY) corrections to the ground-state energy, pressure, sound velocity, and quantum depletion. We investigate all the phases of spin-1 and spin-2 BECs that can be realized experimentally. We also examine the stability of each phase against quantum fluctuations and the quadratic Zeeman effect. Furthermore, we discuss a relationship between the number of symmetry generators that are spontaneously broken and that of Nambu-Goldstone (NG) modes. It is found that in the spin-2 nematic phase there are special Bogoliubov modes that have gapless linear dispersion relations but do not belong to the NG modes.

  3. Geometric phases in electric dipole searches with trapped spin-1/2 particles in general fields and measurement cells of arbitrary shape with smooth or rough walls

    NASA Astrophysics Data System (ADS)

    Golub, R.; Kaufman, C.; Müller, G.; Steyerl, A.

    2015-12-01

    The important role of geometric phases in searches for a permanent electric dipole moment of the neutron, using Ramsey separated oscillatory field nuclear magnetic resonance, was first noted by Commins [Am. J. Phys. 59, 1077 (1991), 10.1119/1.16616] and investigated in detail by Pendlebury et al. [Phys. Rev. A 70, 032102 (2004), 10.1103/PhysRevA.70.032102]. Their analysis was based on the Bloch equations. In subsequent work using the spin-density matrix, Lamoreaux and Golub [Phys. Rev. A 71, 032104 (2005), 10.1103/PhysRevA.71.032104] showed the relation between the frequency shifts and the correlation functions of the fields seen by trapped particles in general fields (Redfield theory). More recently, we presented a solution of the Schrödinger equation for spin-1 /2 particles in circular cylindrical traps with smooth walls and exposed to arbitrary fields [A. Steyerl et al., Phys. Rev. A 89, 052129 (2014), 10.1103/PhysRevA.89.052129]. Here, we extend this work to show how the Redfield theory follows directly from the Schrödinger equation solution. This serves to highlight the conditions of validity of the Redfield theory, a subject of considerable discussion in the literature [e.g., M. P. Nicholas et al., Prog. Nucl. Magn. Reson. Spectrosc. 57, 111 (2010), 10.1016/j.pnmrs.2010.04.003]. Our results can be applied where the Redfield result no longer holds, such as observation times on the order of or shorter than the correlation time and nonstochastic systems, and thus we can illustrate the transient spin dynamics, i.e., the gradual development of the shift with increasing time subsequent to the start of the free precession. We consider systems with rough, diffuse reflecting walls, cylindrical trap geometry with arbitrary cross section, and field perturbations that do not, in the frame of the moving particles, average to zero in time. We show by direct, detailed, calculation the agreement of the results from the Schrödinger equation with the Redfield theory for the

  4. Plaquette-triplon analysis of magnetic disorder and order in a trimerized spin-1 kagome Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Ghosh, Pratyay; Verma, Akhilesh Kumar; Kumar, Brijesh

    2016-01-01

    A spin-1 Heisenberg model on trimerized kagome lattice is studied by doing a low-energy bosonic theory in terms of plaquette triplons defined on its triangular unit cells. The model considered has an intratriangle antiferromagnetic exchange interaction J (set to 1) and two intertriangle couplings J'>0 (nearest neighbor) and J″ (next nearest neighbor; of both signs). The triplon analysis performed on this model investigates the stability of the trimerized singlet ground state (which is exact in the absence of intertriangle couplings) in the J'-J″ plane. It gives a quantum phase diagram that has two gapless antiferromagnetically ordered phases separated by the spin-gapped trimerized singlet phase. The trimerized singlet ground state is found to be stable on J″=0 line (the nearest-neighbor case), and on both sides of it for J″≠0 , in an extended region bounded by the critical lines of transition to the gapless antiferromagnetic phases. The gapless phase in the negative J″ region has a coplanar 120∘ antiferromagnetic order with √{3 }×√{3 } structure. In this phase, all the magnetic moments are of equal length, and the angle between any two of them on a triangle is exactly 120∘. The magnetic lattice in this case has a unit cell consisting of three triangles. The other gapless phase, in the positive J″ region, is found to exhibit a different coplanar antiferromagnetic order with ordering wave vector q =(0 ,0 ) . Here, two magnetic moments in a triangle are of the same magnitude, but shorter than the third. While the angle between two short moments is 120∘-2 δ , it is 120∘+δ between a short and the long one. Only when J″=J' , their magnitudes become equal and the relative angles 120∘. The magnetic lattice in this q =(0 ,0 ) phase has the translational symmetry of the kagome lattice with triangular unit cells of reduced (isosceles) symmetry. This reduction in the point-group symmetry is found to show up as a difference in the intensities of

  5. Commensurate and incommensurate magnetic order in spin-1 chains stacked on the triangular lattice in Li2NiW2O8

    NASA Astrophysics Data System (ADS)

    Ranjith, K. M.; Nath, R.; Majumder, M.; Kasinathan, D.; Skoulatos, M.; Keller, L.; Skourski, Y.; Baenitz, M.; Tsirlin, A. A.

    2016-07-01

    We report the thermodynamic properties, magnetic ground state, and microscopic magnetic model of the spin-1 frustrated antiferromagnet Li2NiW2O8 , showing successive transitions at TN 1≃18 K and TN 2≃12.5 K in zero field. Nuclear magnetic resonance and neutron diffraction reveal collinear and commensurate magnetic order with the propagation vector k =(1/2 ,0 ,1/2 ) below TN 2. The ordered moment of 1.8 μB at 1.5 K is directed along [0.89 (9 ),-0.10 (5 ),-0.49 (6 )] and matches the magnetic easy axis of spin-1 Ni2 + ions, which is determined by the scissor-like distortion of the NiO6 octahedra. Incommensurate magnetic order, presumably of spin-density-wave type, is observed in the region between TN 2 and TN 1. Density-functional band-structure calculations put forward a three-dimensional spin lattice with spin-1 chains running along the [01 1 ¯] direction and stacked on a spatially anisotropic triangular lattice in the a b plane. We show that the collinear magnetic order in Li2NiW2O8 is incompatible with the triangular lattice geometry and thus driven by a pronounced easy-axis single-ion anisotropy of Ni2 +.

  6. Numerical study of incommensurate and decoupled phases of spin-1/2 chains with isotropic exchange J 1, J 2 between first and second neighbors.

    PubMed

    Soos, Zoltán G; Parvej, Aslam; Kumar, Manoranjan

    2016-05-01

    The spin-1/2 chain with isotropic exchange J 1, J 2  >  0 between first and second neighbors is frustrated for either sign of J 1 and has a singlet ground state (GS) for J 1/J 2  ⩾  -4. Its rich quantum phase diagram supports gapless, gapped, commensurate (C), incommensurate (IC) and other phases. Critical points J 1/J 2 are evaluated using exact diagonalization and density matrix renormalization group calculations. The wave vector q G of spin correlations is related to GS degeneracy and obtained as the peak of the spin structure factor S(q). Variable q G indicates IC phases in two J 1/J 2 intervals, [-4, -  1.24] and [0.44, 2], and a C-IC point at J 1/J 2  =  2. The decoupled C phase in [-1.24, 0.44] has constant q G  =  π/2, nondegenerate GS, and a lowest triplet state with broken spin density on sublattices of odd and even numbered sites. The lowest triplet and singlet excitations, E m and E σ , are degenerate in finite systems at specific frustration J 1/J 2. Level crossing extrapolates in the thermodynamic limit to the same critical points as q G. The S(q) peak diverges at q G  =  π in the gapless phase with J 1/J 2  >  4.148 and quasi-long-range order (QLRO(π)). S(q) diverges at  ±π/2 in the decoupled phase with QLRO(π/2), but is finite in gapped phases with finite-range correlations. Numerical results and field theory agree at small J 2/J 1 but disagree for the decoupled phase with weak exchange J 1 between sublattices. Two related models are summarized: one has an exact gapless decoupled phase with QLRO(π/2) and no IC phases; the other has a single IC phase without a decoupled phase in between. PMID:27028489

  7. Numerical study of incommensurate and decoupled phases of spin-1/2 chains with isotropic exchange J 1, J 2 between first and second neighbors

    NASA Astrophysics Data System (ADS)

    Soos, Zoltán G.; Parvej, Aslam; Kumar, Manoranjan

    2016-05-01

    The spin-1/2 chain with isotropic exchange J 1, J 2  >  0 between first and second neighbors is frustrated for either sign of J 1 and has a singlet ground state (GS) for J 1/J 2  ⩾  -4. Its rich quantum phase diagram supports gapless, gapped, commensurate (C), incommensurate (IC) and other phases. Critical points J 1/J 2 are evaluated using exact diagonalization and density matrix renormalization group calculations. The wave vector q G of spin correlations is related to GS degeneracy and obtained as the peak of the spin structure factor S(q). Variable q G indicates IC phases in two J 1/J 2 intervals, [-4, -  1.24] and [0.44, 2], and a C-IC point at J 1/J 2  =  2. The decoupled C phase in [-1.24, 0.44] has constant q G  =  π/2, nondegenerate GS, and a lowest triplet state with broken spin density on sublattices of odd and even numbered sites. The lowest triplet and singlet excitations, E m and E σ , are degenerate in finite systems at specific frustration J 1/J 2. Level crossing extrapolates in the thermodynamic limit to the same critical points as q G. The S(q) peak diverges at q G  =  π in the gapless phase with J 1/J 2  >  4.148 and quasi-long-range order (QLRO(π)). S(q) diverges at  ±π/2 in the decoupled phase with QLRO(π/2), but is finite in gapped phases with finite-range correlations. Numerical results and field theory agree at small J 2/J 1 but disagree for the decoupled phase with weak exchange J 1 between sublattices. Two related models are summarized: one has an exact gapless decoupled phase with QLRO(π/2) and no IC phases; the other has a single IC phase without a decoupled phase in between.

  8. Analysis of heavy spin-3/2 baryon-heavy spin-1/2 baryon-light vector meson vertices in QCD

    SciTech Connect

    Aliev, T. M.; Savci, M.; Azizi, K; Zamiralov, V. S.

    2011-05-01

    The heavy spin-3/2 baryon-heavy spin-1/2 baryon vertices with light vector mesons are studied within the light cone QCD sum rules method. These vertices are parametrized in terms of three coupling constants. These couplings are calculated for all possible transitions. It is shown that correlation functions for these transitions are described by only one invariant function for every Lorenz structure. The obtained relations between the correlation functions of the different transitions are structure independent while explicit expressions of invariant functions depend on the Lorenz structure.

  9. Lower bound for the variation of the hyperfine populations in the ground state of spin-1 condensates against a magnetic field

    NASA Astrophysics Data System (ADS)

    Xie, W. F.; He, Y. Z.; Bao, C. G.

    2015-10-01

    A simple and analytical expression for the variation of the lower bound and upper bound of the population density ρ0 of hyperfine component μ = 0 particles in the ground state of spin-1 condensates against a magnetic field B has been derived. The lower bound has a distinguished feature, namely, it will tend to the actual ρ0 when B tends to zero and infinite. This feature assures that, in the whole range of B, the lower bound can provide an effective constraint. Numerical examples are given to demonstrate the applicability of the bound.

  10. Dynamics of spin-1 bosons in an optical lattice: Spin mixing, quantum-phase-revival spectroscopy, and effective three-body interactions

    NASA Astrophysics Data System (ADS)

    Mahmud, K. W.; Tiesinga, E.

    2013-08-01

    We study the dynamics of spin-1 atoms in a periodic optical-lattice potential and an external magnetic field in a quantum quench scenario where we start from a superfluid ground state in a shallow lattice potential and suddenly raise the lattice depth. The time evolution of the nonequilibrium state shows collective collapse-and-revival oscillations of matter-wave coherence as well as oscillations in the spin populations. We show that the complex pattern of these two types of oscillations reveals details about the superfluid and magnetic properties of the initial many-body ground state. Furthermore, we show that the strengths of the spin-dependent and spin-independent atom-atom interactions can be deduced from the observations. The Hamiltonian that describes the physics of the final deep lattice not only contains two-body interactions but also effective multibody interactions, which arise due to virtual excitations to higher bands. We derive these effective spin-dependent three-body interaction parameters for spin-1 atoms and describe how spin mixing is affected. Spinor atoms are unique in the sense that multibody interactions are directly evident in the in situ number densities in addition to the momentum distributions. We treat both antiferromagnetic (e.g., 23Na) and ferromagnetic (e.g., 87Rb and 41K) condensates.

  11. Exact quantum numbers of collapsed and non-collapsed two-string solutions in the spin-1/2 Heisenberg spin chain

    NASA Astrophysics Data System (ADS)

    Deguchi, Tetsuo; Ranjan Giri, Pulak

    2016-04-01

    Every solution of the Bethe-ansatz equations (BAEs) is characterized by a set of quantum numbers, by which we can evaluate it numerically. However, no general rule is known how to give quantum numbers for the physical solutions of BAE. For the spin-1/2 XXX chain we rigorously derive all the quantum numbers for the complete set of the Bethe-ansatz eigenvectors in the two down-spin sector with any chain length N. Here we obtain them both for real and complex solutions. We also show that all the solutions associated with them are distinct. Consequently, we prove the completeness of the Bethe ansatz and give an exact expression for the number of real solutions which correspond to collapsed bound-state solutions (i.e., two-string solutions) in the sector: 2[(N-1)/2-(N/π ){{tan}}-1(\\sqrt{N-1})] in terms of Gauss’ symbol. Moreover, we prove in the sector the scheme conjectured by Takahashi for solving BAE systematically. We also suggest that by applying the present method we can derive the quantum numbers for the spin-1/2 XXZ chain.

  12. Spin-lattice relaxation of heavy spin-1/2 nuclei in diamagnetic solids: A Raman process mediated by spin-rotation interaction

    NASA Astrophysics Data System (ADS)

    Vega, Alexander J.; Beckmann, Peter A.; Bai, Shi; Dybowski, Cecil

    2006-12-01

    We present a theory for the nuclear spin-lattice relaxation of heavy spin-1/2 nuclei in solids, which explains within an order of magnitude the unexpectedly effective lead and thallium nuclear spin-lattice relaxation rates observed in the ionic solids lead molybdate, lead chloride, lead nitrate, thallium nitrate, thallium nitrite, and thallium perchlorate. The observed rates are proportional to the square of the temperature and are independent of magnetic field. This rules out all known mechanisms usually employed to model nuclear spin relaxation in lighter spin-1/2 nuclei. The relaxation is caused by a Raman process involving the interactions between nuclear spins and lattice vibrations via a fluctuating spin-rotation magnetic field. The model places an emphasis on the time dependence of the angular velocity of pairs of adjacent atoms rather than on their angular momentum. Thus the spin-rotation interaction is characterized not in the traditional manner by a spin-rotation constant but by a related physical parameter, the magnetorotation constant, which relates the local magnetic field generated by spin rotation to an angular velocity. Our semiclassical relaxation model involves a frequency-mode description of the spectral density that can directly be related to the mean-square amplitudes and mode densities of lattice vibrations in the Debye model.

  13. Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4

    SciTech Connect

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; Wosnitza, J.; Krzystek, J.; Yoshizawa, D.; Hagiwara, M.; Hu, Rongwei; Ryu, Hyejin; Petrovic, C.; Zhitomirsky, M. E.

    2015-11-27

    We present on high- field electron spin resonance (ESR) studies of magnetic excitations in the spin- 1/2 triangular-lattice antiferromagnet Cs2CuBr4. Frequency- field diagrams of ESR excitations are measured for different orientations of magnetic fields up to 25 T. We show that the substantial zero- field energy gap, Δ ≈ 9.5 K, observed in the low-temperature excitation spectrum of Cs2CuBr4 [Zvyagin et al:, Phys. Rev. Lett. 112, 077206 (2014)], is present well above TN. Noticeably, the transition into the long-range magnetically ordered phase does not significantly affect the size of the gap, suggesting that even below TN the high-energy spin dynamics in Cs2CuBr4 is determined by short-range-order spin correlations. The experimental data are compared with results of model spin-wave-theory calculations for spin-1/2 triangle-lattice antiferromagnet.

  14. Efficient rotational echo double resonance recoupling of a spin-1/2 and a quadrupolar spin at high spinning rates and weak irradiation fields

    NASA Astrophysics Data System (ADS)

    Nimerovsky, Evgeny; Goldbourt, Amir

    2010-09-01

    A modification of the rotational echo (adiabatic passage) double resonance experiments, which allows recoupling of the dipolar interaction between a spin-1/2 and a half integer quadrupolar spin is proposed. We demonstrate efficient and uniform recoupling at high spinning rates ( ν r), low radio-frequency (RF) irradiation fields ( ν1), and high values of the quadrupolar interaction ( ν q) that correspond to values of α=ν12/νqνr, the adiabaticity parameter, which are down to less than 10% of the traditional adiabaticity limit for a spin-5/2 (α = 0.55). The low-alpha rotational echo double resonance curve is obtained when the pulse on the quadrupolar nucleus is extended to full two rotor periods and beyond. For protons (spin-1/2) and aluminum (spin-5/2) species in the zeolite SAPO-42, a dephasing curve, which is significantly better than the regular REAPDOR experiment (pulse length of one-third of the rotor period) is obtained for a spinning rate of 13 kHz and RF fields down to 10 and even 6 kHz. Under these conditions, α is estimated to be approximately 0.05 based on an average quadrupolar coupling in zeolites. Extensive simulations support our observations suggesting the method to be robust under a large range of experimental values.

  15. Quasiclassical magnetic order and its loss in a spin-1/2 Heisenberg antiferromagnet on a triangular lattice with competing bonds

    NASA Astrophysics Data System (ADS)

    Li, P. H. Y.; Bishop, R. F.; Campbell, C. E.

    2015-01-01

    We use the coupled cluster method (CCM) to study the zero-temperature ground-state (GS) properties of a spin-1/2 J1-J2 Heisenberg antiferromagnet on a triangular lattice with competing nearest-neighbor and next-nearest-neighbor exchange couplings J1>0 and J2≡κ J1>0 , respectively, in the window 0 ≤κ <1 . The classical version of the model has a single GS phase transition at κcl=1/8 in this window from a phase with 3-sublattice antiferromagnetic (AFM) 120∘ Néel order for κ <κcl to an infinitely degenerate family of 4-sublattice AFM Néel phases for κ >κcl . This classical accidental degeneracy is lifted by quantum fluctuations, which favor a 2-sublattice AFM striped phase. For the quantum model we work directly in the thermodynamic limit of an infinite number of spins, with no consequent need for any finite-size scaling analysis of our results. We perform high-order CCM calculations within a well-controlled hierarchy of approximations, which we show how to extrapolate to the exact limit. In this way we find results for the case κ =0 of the spin-1/2 model for the GS energy per spin, E /N =-0.5521 (2 ) J1 , and the GS magnetic order parameter, M =0.198 (5 ) (in units where the classical value is Mcl=1/2), which are among the best available. For the spin-1/2 J1-J2 model we find that the classical transition at κ =κcl is split into two quantum phase transitions at κ1c=0.060 (10 ) and κ2c=0.165 (5 ) . The two quasiclassical AFM states (viz., the 120∘ Néel state and the striped state) are found to be the stable GS phases in the regime κ <κ1c and κ >κ2c , respectively, while in the intermediate regimes κ1c<κ <κ2c the stable GS phase has no evident long-range magnetic order.

  16. Effects of thermal and quantum fluctuations on the phase diagram of a spin-1 {sup 87}Rb Bose-Einstein condensate

    SciTech Connect

    Phuc, Nguyen Thanh; Kawaguchi, Yuki; Ueda, Masahito

    2011-10-15

    We investigate the effects of thermal and quantum fluctuations on the phase diagram of a spin-1 {sup 87}Rb Bose-Einstein condensate (BEC) under the quadratic Zeeman effect. Due to the large ratio of spin-independent to spin-dependent interactions of {sup 87}Rb atoms, the effect of noncondensed atoms on the condensate is much more significant than that in scalar BECs. We find that the condensate and spontaneous magnetization emerge at different temperatures when the ground state is in the broken-axisymmetry phase. In this phase, a magnetized condensate induces spin coherence of noncondensed atoms in different magnetic sublevels, resulting in temperature-dependent magnetization of the noncondensate. We also examine the effect of quantum fluctuations on the order parameter at absolute zero and find that the ground-state phase diagram is significantly altered by quantum depletion.

  17. Observation of Overlapping Spin-1 and Spin-3 D¯0K- Resonances at Mass 2.86 GeV /c2

    NASA Astrophysics Data System (ADS)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassen, R.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Aquines Gutierrez, O.; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bettler, M.-O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Bird, T.; Bizzeti, A.; Bjørnstad, P. M.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brambach, T.; van den Brand, J.; Bressieux, J.; Brett, D.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Brown, H.; Bursche, A.; Busetto, G.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Campora Perez, D.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cassina, L.; Castillo Garcia, L.; Cattaneo, M.; Cauet, Ch.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chefdeville, M.; Chen, S.; Cheung, S.-F.; Chiapolini, N.; Chrzaszcz, M.; Ciba, K.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Counts, I.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Dalseno, J.; David, P.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Silva, W.; De Simone, P.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Déléage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Di Canto, A.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suárez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H.-M.; Evans, T.; Falabella, A.; Färber, C.; Farinelli, C.; Farley, N.; Farry, S.; Fay, RF; Ferguson, D.; Fernandez Albor, V.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; García Pardiñas, J.; Garofoli, J.; Garra Tico, J.; Garrido, L.; Gaspar, C.; Gauld, R.; Gavardi, L.; Gavrilov, G.; Geraci, A.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianelle, A.; Gianı, S.; Gibson, V.; Giubega, L.; Gligorov, V. V.; Göbel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gotti, C.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Grünberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hampson, T.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Heß, M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Hunt, P.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jaton, P.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kaballo, M.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kelsey, M.; Kenyon, I. R.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Korolev, M.; Kozlinskiy, A.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kurek, K.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lambert, R. W.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Lefèvre, R.; Leflat, A.; Lefrançois, J.; Leo, S.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Liles, M.; Lindner, R.; Linn, C.; Lionetto, F.; Liu, B.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lopez-March, N.; Lowdon, P.; Lu, H.; Lucchesi, D.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Malinin, A.; Manca, G.; Mancinelli, G.; Mapelli, A.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Märki, R.; Marks, J.; Martellotti, G.; Martens, A.; Martín Sánchez, A.; Martinelli, M.; Martinez Santos, D.; Martinez Vidal, F.; Martins Tostes, D.; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Mazurov, A.; McCann, M.; McCarthy, J.; McNab, A.; McNulty, R.; McSkelly, B.; Meadows, B.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M.-N.; Moggi, N.; Molina Rodriguez, J.; Monteil, S.; Morandin, M.; Morawski, P.; Mordà, A.; Morello, M. J.; Moron, J.; Morris, A.-B.; Mountain, R.; Muheim, F.; Müller, K.; Mussini, M.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Nicol, M.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Oggero, S.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Onderwater, G.; Orlandea, M.; Otalora Goicochea, J. M.; Owen, P.; Oyanguren, A.; Pal, B. K.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L. L.; Parkes, C.; Parkinson, C. J.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrignani, C.; Pazos Alvarez, A.; Pearce, A.; Pellegrino, A.; Pepe Altarelli, M.; Perazzini, S.; Perez Trigo, E.; Perret, P.; Perrin-Terrin, M.; Pescatore, L.; Pesen, E.; Petridis, K.; Petrolini, A.; Picatoste Olloqui, E.; Pietrzyk, B.; Pilař, T.; Pinci, D.; Pistone, A.; Playfer, S.; Plo Casasus, M.; Polci, F.; Poluektov, A.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Price, E.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Punzi, G.; Qian, W.; Rachwal, B.; Rademacker, J. H.; Rakotomiaramanana, B.; Rama, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Reichert, S.; Reid, M. M.; dos Reis, A. C.; Ricciardi, S.; Richards, S.; Rihl, M.; Rinnert, K.; Rives Molina, V.; Roa Romero, D. A.; Robbe, P.; Rodrigues, A. B.; Rodrigues, E.; Rodriguez Perez, P.; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rotondo, M.; Rouvinet, J.; Ruf, T.; Ruffini, F.; Ruiz, H.; Ruiz Valls, P.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrie, M.; Savrina, D.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M.-H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Seco, M.; Semennikov, A.; Sepp, I.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Silva Coutinho, R.; Simi, G.; Sirendi, M.; Skidmore, N.; Skwarnicki, T.; Smith, N. A.; Smith, E.; Smith, E.; Smith, J.; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; Souza, D.; Souza De Paula, B.; Spaan, B.; Sparkes, A.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Steinkamp, O.; Stenyakin, O.; Stevenson, S.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Stroili, R.; Subbiah, V. K.; Sun, L.; Sutcliffe, W.; Swientek, K.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szilard, D.; Szumlak, T.; T'Jampens, S.; Teklishyn, M.; Tellarini, G.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Tran, M. T.; Tresch, M.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Ubeda Garcia, M.; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vagnoni, V.; Valenti, G.; Vallier, A.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vázquez Sierra, C.; Vecchi, S.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voß, C.; Voss, H.; de Vries, J. A.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, J.; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Websdale, D.; Whitehead, M.; Wicht, J.; Wiedner, D.; Wilkinson, G.; Williams, M. P.; Williams, M.; Wilson, F. F.; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.; Wu, S.; Wyllie, K.; Xie, Y.; Xing, Z.; Xu, Z.; Yang, Z.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, L.; Zhang, W. C.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.; Zvyagin, A.; LHCb Collaboration

    2014-10-01

    The resonant substructure of Bs0→D¯ 0K-π+ decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb-1 of p p collision data recorded by the LHCb detector. An excess at m (D¯ 0K-)≈2.86 GeV /c2 is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the DsJ *(2860 )- state previously observed in inclusive e+e-→D¯ 0K-X and p p →D¯ 0K-X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the Ds2 *(2573 )- meson are measured, giving the most precise determinations to date.

  18. Quantum fidelity, string order parameter, and topological quantum phase transition in a spin-1/2 dimerized and frustrated Heisenberg chain

    NASA Astrophysics Data System (ADS)

    Liu, Jin Hua; Wang, Hai Tao

    2015-10-01

    Topological quantum phase transitions are numerically investigated in a spin-1/2 dimerized and frustrated Heisenberg chain by using infinite matrix product state representation with the infinite time evolving block decimation method. Quantum fidelity approach is employed to detect the degenerate ground states and quantum phase transitions. By calculating the long-range string order parameters, we find two topological Haldane phases characterized by two long-range string orders. Also, continuous and discontinuous behaviors of von Neumann entropy show that phase transitions between two topological Haldane phases are topologically continuous and discontinuous quantum phase transitions. For the topologically continuous phase transition, the central charge at the critical point is obtained as c = 1, which means that the topologically continuous quantum phase transition belongs to the Gaussian universality class.

  19. Presence or absence of order by disorder in a highly frustrated region of the spin-1/2 Ising-Heisenberg model on triangulated Husimi lattices.

    PubMed

    Strečka, Jozef; Ekiz, Cesur

    2015-05-01

    The geometrically frustrated spin-1/2 Ising-Heisenberg model on triangulated Husimi lattices is exactly solved by combining the generalized star-triangle transformation with the method of exact recursion relations. The ground-state and finite-temperature phase diagrams are rigorously calculated along with both sublattice magnetizations of the Ising and Heisenberg spins. It is evidenced that the Ising-Heisenberg model on triangulated Husimi lattices with two or three interconnected triangles-in-triangles units displays in a highly frustrated region a quantum disorder irrespective of temperature, whereas the same model on triangulated Husimi lattices with a greater connectivity of triangles-in-triangles units exhibits at low enough temperatures an outstanding quantum order due to the order-by-disorder mechanism. The quantum reduction of both sublattice magnetizations in the peculiar quantum ordered state gradually diminishes upon increasing the coordination number of the underlying Husimi lattice. PMID:26066155

  20. Static and Dynamical Properties of the Spin-1/2 Equilateral Triangular-Lattice Antiferromagnet Ba_{3}CoSb_{2}O_{9}.

    PubMed

    Ma, J; Kamiya, Y; Hong, Tao; Cao, H B; Ehlers, G; Tian, W; Batista, C D; Dun, Z L; Zhou, H D; Matsuda, M

    2016-02-26

    We present single-crystal neutron scattering measurements of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba_{3}CoSb_{2}O_{9}. Besides confirming that the Co^{2+} magnetic moments lie in the ab plane for zero magnetic field and then determining all the exchange parameters of the minimal quasi-2D spin Hamiltonian, we provide conclusive experimental evidence of magnon decay through observation of intrinsic line broadening. Through detailed comparisons with the linear and nonlinear spin-wave theories, we also point out that the large-S approximation, which is conventionally employed to predict magnon decay in noncollinear magnets, is inadequate to explain our experimental observation. Thus, our results call for a new theoretical framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects. PMID:26967439

  1. Gapless quantum spin liquid ground state in the spin-1 antiferromagnet 6HB-Ba3NiSb2O9

    NASA Astrophysics Data System (ADS)

    Quilliam, J. A.; Bert, F.; Manseau, A.; Darie, C.; Guillot-Deudon, C.; Payen, C.; Baines, C.; Amato, A.; Mendels, P.

    2016-06-01

    We present an in-depth study of the magnetic properties of the spin-1 antiferromagnet 6HB-Ba3NiSb2O9 . μ SR measurements demonstrate that this material shows no static magnetism down to temperatures as low as 20 mK, making it a likely candidate for a quantum spin liquid state. 121Sb NMR shift measurements show that the local, intrinsic susceptibility levels off at temperatures below ˜60 K. The NMR spin-lattice relaxation rate 1 /T1 is essentially constant in temperature and the muon relaxation rate exhibits a low-temperature relaxation plateau, all indications of gapless spin excitations. Our local probe measurements are discussed in the context of several theories proposed for this material.

  2. Static and dynamical properties of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba3CoSb2O9

    DOE PAGESBeta

    Ma, Jie; Kamiya, Yoshitomo; Hong, Tao; Cao, H. B.; Ehlers, Georg; Tian, Wei; Batista, C. D.; Dun, Z. L.; Zhou, H. D.; Matsuda, Masaaki

    2016-02-24

    We present single-crystal neutron scattering measurements of the spin-1/2 equilateral triangular-lattice antiferromagnet Ba3CoSb2O9. Besides confirming that the Co2+ magnetic moments lie in the ab plane for zero magnetic field and then determining all the exchange parameters of the minimal quasi-2D spin Hamiltonian, we provide conclusive experimental evidence of magnon decay through observation of intrinsic line broadening. Through detailed comparisons with the linear and nonlinear spin-wave theories, we also point out that the large-S approximation, which is conventionally employed to predict magnon decay in noncollinear magnets, is inadequate to explain our experimental observation. Hence, our results call for a new theoreticalmore » framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects.« less

  3. Quantum Darwinism and non-Markovian dissipative dynamics from quantum phases of the spin-1/2 X X model

    NASA Astrophysics Data System (ADS)

    Giorgi, Gian Luca; Galve, Fernando; Zambrini, Roberta

    2015-08-01

    Quantum Darwinism explains the emergence of a classical description of objects in terms of the creation of many redundant registers in an environment containing their classical information. This amplification phenomenon, where only classical information reaches the macroscopic observer and through which different observers can agree on the objective existence of such object, has been revived lately for several types of situations, successfully explaining classicality. We explore quantum Darwinism in the setting of an environment made of two level systems which are initially prepared in the ground state of the XX model, which exhibits different phases; we find that the different phases have different abilities to redundantly acquire classical information about the system, the "ferromagnetic phase" being the only one able to complete quantum Darwinism. At the same time we relate this ability to how non-Markovian the system dynamics is, based on the interpretation that non-Markovian dynamics is associated with backflow of information from environment to system, thus spoiling the information transfer needed for Darwinism. Finally, we explore mixing of bath registers by allowing a small interaction among them, finding that this spoils the stored information as previously found in the literature.

  4. Two-photon exchange amplitude with π N intermediate states: Spin-1/2 and spin-3/2 channels

    NASA Astrophysics Data System (ADS)

    Borisyuk, Dmitry; Kobushkin, Alexander

    2015-09-01

    We calculate two-photon exchange amplitudes for the elastic electron-proton scattering, and take into account intermediate hadronic states containing a π N system with total angular momentum 1/2 or 3/2, which includes eight different channels. This is the improvement of our previous calculation, where only the π N states with quantum numbers of Δ resonance were included. The results show good consistency with recent experimental data. At high Q2, newly calculated contributions affect the correction to the measured proton form factor ratio μ GE/GM . The total correction becomes somewhat smaller compared to our previous work, but is still significant and grows approximately linearly with Q2. Comparing contributions of different channels, we found that larger contributions come from the channels with quantum numbers of lightest resonances.

  5. The Phases of an Interacting Spin-1/2 Fermi Gas as seen from a New Variational Ansatz

    NASA Astrophysics Data System (ADS)

    Chung, Sangwoo; Sun, Kuei; Bolech, Carlos

    2015-05-01

    Since its introduction, the continuous matrix product states (cMPS) have demonstrated success in predicting low energy properties of repulsive one-dimensional (1D) Bose gas systems. We have extended those efforts to nonrelativistic fermions and shown that the cMPS, moreover, is able to correctly describe the ground-state superfluid and magnetic properties of interacting Fermi gases in 1D. This includes the signatures of a partially polarized superfluid regime, in agreement with the large amount of theoretical and experimental work from recent years by the cold-atoms community. The new type of ansatz promises to be ideally posed to be able to describe atomic gases in optical lattices economically but without making a lattice-model (tight-binding) approximation. Funding for this work was provided by the University of Cincinnati and by the DARPA OLE program through ARO W911NF-07-1-0464; parallel computing resources were from the Ohio Supercomputer Center (OSC).

  6. Chemical and Magnetic Order in Vapor-Deposited Metal Films

    NASA Astrophysics Data System (ADS)

    Rooney, Peter Wiliam

    1995-01-01

    A stochastic Monte Carlo model of vapor deposition and growth of a crystalline, binary, A_3 B metallic alloy with a negative energy of mixing has been developed which incorporates deposition and surface diffusion in a physically correct manner and allows the simulation of deposition rates that are experimentally realizable. The effects of deposition rate and growth temperature on the development of short range order (SRO) in vapor-deposited films have been examined using this model. SRO in the simulated films increases with growth temperature up to the point at which the temperature corresponds to the energy of mixing, but we see no corresponding development of anisotropic SRO (preferential ordering of A-B pairs along the growth direction). Epitaxial (100) and (111) CoPt_3 films have been deposited over a range of growth temperatures from -50^circ C to 800^circC. Curie temperature (T_{rm c}) and saturation magnetization are dramatically enhanced in those films grown near 400^circ C over the values expected for the chemically homogeneous alloy. Magnetization data indicates that the high T _{rm c} films are inhomogeneous. These phenomena are interpreted as evidence of a previously unobserved magnetically driven miscibility gap in the Co-Pt phase diagram. Films grown near 400^circ C exhibit large uniaxial perpendicular magnetic anisotropy that cannot be accounted for by strain. The observed anisotropy coincides with the chemical phase separation and it seems likely that these two phenomena are related. Long range order (LRO) in the as-deposited films peaks at a growth temperature of 630^circC and then decreases with decreasing growth temperature. The decrease in LRO is either due to kinetic frustration or to competition from magnetically induced Co clustering. Theoretical phase diagrams based on the appropriate Blume-Emery-Griffiths Hamiltonian suggest the latter.

  7. Equivalence of ADM Hamiltonian and Effective Field Theory approaches at next-to-next-to-leading order spin1-spin2 coupling of binary inspirals

    SciTech Connect

    Levi, Michele; Steinhoff, Jan E-mail: jan.steinhoff@ist.utl.pt

    2014-12-01

    The next-to-next-to-leading order spin1-spin2 potential for an inspiralling binary, that is essential for accuracy to fourth post-Newtonian order, if both components in the binary are spinning rapidly, has been recently derived independently via the ADM Hamiltonian and the Effective Field Theory approaches, using different gauges and variables. Here we show the complete physical equivalence of the two results, thereby we first prove the equivalence of the ADM Hamiltonian and the Effective Field Theory approaches at next-to-next-to-leading order with the inclusion of spins. The main difficulty in the spinning sectors, which also prescribes the manner in which the comparison of the two results is tackled here, is the existence of redundant unphysical spin degrees of freedom, associated with the spin gauge choice of a point within the extended spinning object for its representative worldline. After gauge fixing and eliminating the unphysical degrees of freedom of the spin and its conjugate at the level of the action, we arrive at curved spacetime generalizations of the Newton-Wigner variables in closed form, which can also be used to obtain further Hamiltonians, based on an Effective Field Theory formulation and computation. Finally, we make use of our validated result to provide gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to fourth post-Newtonian order, including all known sectors up to date.

  8. Simulations of molecular dynamics in solid-state NMR spectra of spin-1 nuclei including effects of CSA- and EFG-terms up to second order.

    PubMed

    Larsen, Flemming H

    2007-04-01

    By numerical simulations MAS and QCPMG methods for acquiring spectra of spin-1 nuclei were compared in order to determine the most sensitive experiment for analysis of molecular dynamics. To comply with the large quadrupolar constants for 14N and the CSA reported for 6Li both of these interactions are included up to second order. For 2H and 6Li both QCPMG and single-pulse MAS experiments were suitable for dynamics studies whereas the single-pulse MAS experiment were the method of choice for investigation of 14N dynamics for C(Q)'s larger than 750kHz at 14.1T. This property prohibits excitation of the 14N lineshape using either single hard or softer composite rf-pulses. Focusing on 14N it was demonstrated that the centerband lineshape is sensitive toward both off-MAS and CSA effects. In addition, excitation by real-time pulses showed that proper lineshapes corresponding to a site with a C(Q) of 3MHz may be excited by a very short pulse. PMID:17418539

  9. Quantum phase transitions and string orders in the spin-1/2 Heisenberg-Ising alternating chain with Dzyaloshinskii-Moriya interaction.

    PubMed

    Liu, Guang-Hua; You, Wen-Long; Li, Wei; Su, Gang

    2015-04-29

    Quantum phase transitions (QPTs) and the ground-state phase diagram of the spin-1/2 Heisenberg-Ising alternating chain (HIAC) with uniform Dzyaloshinskii-Moriya (DM) interaction are investigated by a matrix-product-state (MPS) method. By calculating the odd- and even-string order parameters, we recognize two kinds of Haldane phases, i.e. the odd- and even-Haldane phases. Furthermore, doubly degenerate entanglement spectra on odd and even bonds are observed in odd- and even-Haldane phases, respectively. A rich phase diagram including four different phases, i.e. an antiferromagnetic (AF), AF stripe, odd- and even-Haldane phases, is obtained. These phases are found to be separated by continuous QPTs: the topological QPT between the odd- and even-Haldane phases is verified to be continuous and corresponds to conformal field theory with central charge c = 1; while the rest of the phase transitions in the phase diagram are found to be c = 1/2. We also revisit, with our MPS method, the exactly solvable case of HIAC model with DM interactions only on odd bonds and find that the even-Haldane phase disappears, but the other three phases, i.e. the AF, AF stripe and odd-Haldane phases, still remain in the phase diagram. We exhibit the evolution of the even-Haldane phase by tuning the DM interactions on the even bonds gradually. PMID:25817273

  10. Spin-1 J1 -J2 -J3 ferromagnetic Heisenberg model with an easy-plane crystal field on the cubic lattice: A bosonic approach

    NASA Astrophysics Data System (ADS)

    Carvalho, D. C.; Pires, A. S. T.; Mól, L. A. S.

    2016-06-01

    We examine the phase diagram of the spin-1 J1 -J2 -J3 ferromagnetic Heisenberg model with an easy-plane crystal field on the cubic lattice, in which J1 is the ferromagnetic exchange interaction between nearest neighbors, J2 is the antiferromagnetic exchange interaction between next-nearest neighbors and J3 is the antiferromagnetic exchange interaction between next-next-nearest neighbors. Using the bond-operator formalism, we investigate the phase transitions between the disordered paramagnetic phase and the ordered ones. We show that the nature of the quantum phase transitions changes as the frustration parameters (J2/J1, J3/J1) are varied. The zero-temperature phase diagram exhibits second- and first-order transitions, depending on the energy gap behavior. Remarkably, we find a disordered nonmagnetic phase, even in the absence of a crystal field, which is suggested to be a quantum spin liquid candidate. We also depict the phase diagram at finite temperature for some values of crystal field and frustration parameters.

  11. Quantum phase transitions and string orders in the spin-1/2 Heisenberg-Ising alternating chain with Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Liu, Guang-Hua; You, Wen-Long; Li, Wei; Su, Gang

    2015-04-01

    Quantum phase transitions (QPTs) and the ground-state phase diagram of the spin-1/2 Heisenberg-Ising alternating chain (HIAC) with uniform Dzyaloshinskii-Moriya (DM) interaction are investigated by a matrix-product-state (MPS) method. By calculating the odd- and even-string order parameters, we recognize two kinds of Haldane phases, i.e. the odd- and even-Haldane phases. Furthermore, doubly degenerate entanglement spectra on odd and even bonds are observed in odd- and even-Haldane phases, respectively. A rich phase diagram including four different phases, i.e. an antiferromagnetic (AF), AF stripe, odd- and even-Haldane phases, is obtained. These phases are found to be separated by continuous QPTs: the topological QPT between the odd- and even-Haldane phases is verified to be continuous and corresponds to conformal field theory with central charge c = 1 while the rest of the phase transitions in the phase diagram are found to be c = 1/2. We also revisit, with our MPS method, the exactly solvable case of HIAC model with DM interactions only on odd bonds and find that the even-Haldane phase disappears, but the other three phases, i.e. the AF, AF stripe and odd-Haldane phases, still remain in the phase diagram. We exhibit the evolution of the even-Haldane phase by tuning the DM interactions on the even bonds gradually.

  12. Spin frustration of a spin-1/2 Ising-Heisenberg three-leg tube as an indispensable ground for thermal entanglement

    NASA Astrophysics Data System (ADS)

    Strečka, Jozef; Alécio, Raphael Cavalcante; Lyra, Marcelo L.; Rojas, Onofre

    2016-07-01

    The spin-1/2 Ising-Heisenberg three-leg tube composed of the Heisenberg spin triangles mutually coupled through the Ising inter-triangle interaction is exactly solved in a zero magnetic field. By making use of the local conservation for the total spin on each Heisenberg spin triangle the model can be rigorously mapped onto a classical composite spin-chain model, which is subsequently exactly treated through the transfer-matrix method. The ground-state phase diagram, correlation functions, concurrence, Bell function, entropy and specific heat are examined in detail. It is shown that the spin frustration represents an indispensable ground for a thermal entanglement, which is quantified by the quantum concurrence. The specific heat displays diverse temperature dependences, which may include a sharp low-temperature peak mimicking a temperature-driven first-order phase transition. It is convincingly evidenced that this anomalous peak originates from massive thermal excitations from the doubly degenerate ground state towards an excited state with a high macroscopic degeneracy due to chiral degrees of freedom of the Heisenberg spin triangles.

  13. Observation of overlapping spin-1 and spin-3 D0K- resonances at mass 2.86 GeV/c2.

    PubMed

    Aaij, R; Adeva, B; Adinolfi, M; Affolder, A; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Anderson, J; Andreassen, R; Andreotti, M; Andrews, J E; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Bachmann, S; Back, J J; Badalov, A; Baesso, C; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Batozskaya, V; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Borsato, M; Bowcock, T J V; Bowen, E; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brodzicka, J; Brook, N H; Brown, H; Bursche, A; Busetto, G; Buytaert, J; Cadeddu, S; Calabrese, R; Calvi, M; Calvo Gomez, M; Campana, P; Campora Perez, D; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cassina, L; Castillo Garcia, L; Cattaneo, M; Cauet, Ch; Cenci, R; Charles, M; Charpentier, Ph; Chefdeville, M; Chen, S; Cheung, S-F; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Coquereau, S; Corti, G; Corvo, M; Counts, I; Couturier, B; Cowan, G A; Craik, D C; Cruz Torres, M; Cunliffe, S; Currie, R; D'Ambrosio, C; Dalseno, J; David, P; David, P N Y; Davis, A; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Silva, W; De Simone, P; Decamp, D; Deckenhoff, M; Del Buono, L; Déléage, N; Derkach, D; Deschamps, O; Dettori, F; Di Canto, A; Dijkstra, H; Donleavy, S; Dordei, F; Dorigo, M; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dreimanis, K; Dujany, G; Dupertuis, F; Durante, P; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Ely, S; Esen, S; Evans, H-M; Evans, T; Falabella, A; Färber, C; Farinelli, C; Farley, N; Farry, S; Fay, Rf; Ferguson, D; Fernandez Albor, V; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fiore, M; Fiorini, M; Firlej, M; Fitzpatrick, C; Fiutowski, T; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Fu, J; Furfaro, E; Gallas Torreira, A; Galli, D; Gallorini, S; Gambetta, S; Gandelman, M; Gandini, P; Gao, Y; García Pardiñas, J; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauld, R; Gavardi, L; Gavrilov, G; Geraci, A; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gianelle, A; Gianì, S; Gibson, V; Giubega, L; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gotti, C; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Griffith, P; Grillo, L; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hamilton, B; Hampson, T; Han, X; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; He, J; Head, T; Heijne, V; Hennessy, K; Henrard, P; Henry, L; Hernando Morata, J A; van Herwijnen, E; Heß, M; Hicheur, A; Hill, D; Hoballah, M; Hombach, C; Hulsbergen, W; Hunt, P; Hussain, N; Hutchcroft, D; Hynds, D; Idzik, M; Ilten, P; Jacobsson, R; Jaeger, A; Jalocha, J; Jans, E; Jaton, P; Jawahery, A; Jing, F; John, M; Johnson, D; Jones, C R; Joram, C; Jost, B; Jurik, N; Kaballo, M; Kandybei, S; Kanso, W; Karacson, M; Karbach, T M; Karodia, S; Kelsey, M; Kenyon, I R; Ketel, T; Khanji, B; Khurewathanakul, C; Klaver, S; Klimaszewski, K; Kochebina, O; Kolpin, M; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kucewicz, W; Kucharczyk, M; Kudryavtsev, V; Kurek, K; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanfranchi, G; Langenbruch, C; Langhans, B; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leo, S; Leroy, O; Lesiak, T; Leverington, B; Li, Y; Likhomanenko, T; Liles, M; Lindner, R; Linn, C; Lionetto, F; Liu, B; Lohn, S; Longstaff, I; Lopes, J H; Lopez-March, N; Lowdon, P; Lu, H; Lucchesi, D; Luo, H; Lupato, A; Luppi, E; Lupton, O; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Malde, S; Malinin, A; Manca, G; Mancinelli, G; Mapelli, A; Maratas, J; Marchand, J F; Marconi, U; Marin Benito, C; Marino, P; Märki, R; Marks, J; Martellotti, G; Martens, A; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Martinez Vidal, F; Martins Tostes, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Mazurov, A; McCann, M; McCarthy, J; McNab, A; McNulty, R; McSkelly, B; Meadows, B; Meier, F; Meissner, M; Merk, M; Milanes, D A; Minard, M-N; Moggi, N; Molina Rodriguez, J; Monteil, S; Morandin, M; Morawski, P; Mordà, A; Morello, M J; Moron, J; Morris, A-B; Mountain, R; Muheim, F; Müller, K; Mussini, M; Muster, B; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neri, N; Neubert, S; Neufeld, N; Neuner, M; Nguyen, A D; Nguyen, T D; Nguyen-Mau, C; Nicol, M; Niess, V; Niet, R; Nikitin, N; Nikodem, T; Novoselov, A; O'Hanlon, D P; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Onderwater, G; Orlandea, M; Otalora Goicochea, J M; Owen, P; Oyanguren, A; Pal, B K; Palano, A; Palombo, F; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Pappalardo, L L; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Patrignani, C; Pazos Alvarez, A; Pearce, A; Pellegrino, A; Pepe Altarelli, M; Perazzini, S; Perez Trigo, E; Perret, P; Perrin-Terrin, M; Pescatore, L; Pesen, E; Petridis, K; Petrolini, A; Picatoste Olloqui, E; Pietrzyk, B; Pilař, T; Pinci, D; Pistone, A; Playfer, S; Plo Casasus, M; Polci, F; Poluektov, A; Polycarpo, E; Popov, A; Popov, D; Popovici, B; Potterat, C; Price, E; Prisciandaro, J; Pritchard, A; Prouve, C; Pugatch, V; Puig Navarro, A; Punzi, G; Qian, W; Rachwal, B; Rademacker, J H; Rakotomiaramanana, B; Rama, M; Rangel, M S; Raniuk, I; Rauschmayr, N; Raven, G; Reichert, S; Reid, M M; Dos Reis, A C; Ricciardi, S; Richards, S; Rihl, M; Rinnert, K; Rives Molina, V; Roa Romero, D A; Robbe, P; Rodrigues, A B; Rodrigues, E; Rodriguez Perez, P; Roiser, S; Romanovsky, V; Romero Vidal, A; Rotondo, M; Rouvinet, J; Ruf, T; Ruffini, F; Ruiz, H; Ruiz Valls, P; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salustino Guimaraes, V; Sanchez Mayordomo, C; Sanmartin Sedes, B; Santacesaria, R; Santamarina Rios, C; Santovetti, E; Sarti, A; Satriano, C; Satta, A; Saunders, D M; Savrie, M; Savrina, D; Schiller, M; Schindler, H; Schlupp, M; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M-H; Schwemmer, R; Sciascia, B; Sciubba, A; Seco, M; Semennikov, A; Sepp, I; Serra, N; Serrano, J; Sestini, L; Seyfert, P; Shapkin, M; Shapoval, I; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, V; Shires, A; Silva Coutinho, R; Simi, G; Sirendi, M; Skidmore, N; Skwarnicki, T; Smith, N A; Smith, E; Smith, E; Smith, J; Smith, M; Snoek, H; Sokoloff, M D; Soler, F J P; Soomro, F; Souza, D; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Sridharan, S; Stagni, F; Stahl, M; Stahl, S; Steinkamp, O; Stenyakin, O; Stevenson, S; Stoica, S; Stone, S; Storaci, B; Stracka, S; Straticiuc, M; Straumann, U; Stroili, R; Subbiah, V K; Sun, L; Sutcliffe, W; Swientek, K; Swientek, S; Syropoulos, V; Szczekowski, M; Szczypka, P; Szilard, D; Szumlak, T; T'Jampens, S; Teklishyn, M; Tellarini, G; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Tolk, S; Tomassetti, L; Tonelli, D; Topp-Joergensen, S; Torr, N; Tournefier, E; Tourneur, S; Tran, M T; Tresch, M; Tsaregorodtsev, A; Tsopelas, P; Tuning, N; Ubeda Garcia, M; Ukleja, A; Ustyuzhanin, A; Uwer, U; Vagnoni, V; Valenti, G; Vallier, A; Vazquez Gomez, R; Vazquez Regueiro, P; Vázquez Sierra, C; Vecchi, S; Velthuis, J J; Veltri, M; Veneziano, G; Vesterinen, M; Viaud, B; Vieira, D; Vieites Diaz, M; Vilasis-Cardona, X; Vollhardt, A; Volyanskyy, D; Voong, D; Vorobyev, A; Vorobyev, V; Voß, C; Voss, H; de Vries, J A; Waldi, R; Wallace, C; Wallace, R; Walsh, J; Wandernoth, S; Wang, J; Ward, D R; Watson, N K; Websdale, D; Whitehead, M; Wicht, J; Wiedner, D; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wimberley, J; Wishahi, J; Wislicki, W; Witek, M; Wormser, G; Wotton, S A; Wright, S; Wu, S; Wyllie, K; Xie, Y; Xing, Z; Xu, Z; Yang, Z; Yuan, X; Yushchenko, O; Zangoli, M; Zavertyaev, M; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhokhov, A; Zhong, L; Zvyagin, A

    2014-10-17

    The resonant substructure of B(s)(0) → D(0)K(-)π(+) decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collision data recorded by the LHCb detector. An excess at m(D(0)K(-))≈ 2.86 GeV/c(2) is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the D(sJ)*(2860)(-) state previously observed in inclusive e(+)e(-) → D(0)K(-)X and pp → D(0)K(-)X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the D(s2)*(2573)(-) meson are measured, giving the most precise determinations to date. PMID:25361252

  14. Quantum phase transition, universality, and scaling behaviors in the spin-1/2 Heisenberg model with ferromagnetic and antiferromagnetic competing interactions on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Zhen; Xi, Bin; Chen, Xi; Li, Wei; Wang, Zheng-Chuan; Su, Gang

    2016-06-01

    The quantum phase transition, scaling behaviors, and thermodynamics in the spin-1/2 quantum Heisenberg model with antiferromagnetic coupling J >0 in the armchair direction and ferromagnetic interaction J'<0 in the zigzag direction on a honeycomb lattice are systematically studied using the continuous-time quantum Monte Carlo method. By calculating the Binder ratio Q2 and spin stiffness ρ in two directions for various coupling ratios α =J'/J under different lattice sizes, we found that a quantum phase transition from the dimerized phase to the stripe phase occurs at the quantum critical point αc=-0.93 . Through the finite-size scaling analysis on Q2, ρx, and ρy, we determined the critical exponent related to the correlation length ν to be 0.7212(8), implying that this transition falls into a classical Heisenberg O(3) universality. A zero magnetization plateau is observed in the dimerized phase, whose width decreases with increasing α . A phase diagram in the coupling ratio α -magnetic field h plane is obtained, where four phases, including dimerized, stripe, canted stripe, and polarized, are identified. It is also unveiled that the temperature dependence of the specific heat C (T ) for different α 's intersects precisely at one point, similar to that of liquid 3He under different pressures and several magnetic compounds under various magnetic fields. The scaling behaviors of Q2, ρ , and C (T ) are carefully analyzed. The susceptibility is compared with the experimental data to give the magnetic parameters of both compounds.

  15. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair

    NASA Astrophysics Data System (ADS)

    Chang, Zhiwei; Halle, Bertil

    2013-10-01

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

  16. Long-range and short-range magnetic correlations, and microscopic origin of net magnetization in the spin-1 trimer chain compound CaNi3P4O14

    NASA Astrophysics Data System (ADS)

    Bera, A. K.; Yusuf, S. M.; Kumar, Amit; Majumder, M.; Ghoshray, K.; Keller, L.

    2016-05-01

    Spin-spin correlations and microscopic origin of net magnetization in the spin-1 trimer chain compound CaNi3P4O14 have been investigated by powder neutron diffraction. The present study reveals a three-dimensional long-range magnetic ordering below 16 K where the magnetic structure consists of ferromagnetic trimers that are coupled ferromagnetically along the spin-chain direction (b axis). The moment components along the a and c axes arrange antiferromagnetically. Our study establishes that the uncompensated moment components along the b axis (mb) result in a net magnetization per unit cell. The magnetic structure, determined in the present study, is in agreement with the results of recent first-principles calculation; however, it is in contrast to a fascinating experimental prediction of ferrimagnetic ordering based on the periodicity of the exchange interactions in CaNi3P4O14 . Our study also confirms the presence of broad diffuse magnetic scattering, due to one-dimensional short-range spin-spin correlations, over a wide temperature range below ˜50 K down to a temperature well below the Tc. Total neutron scattering analysis by the reverse Monte Carlo (RMC) method reveals that the dominating spin-spin correlation above Tc is ferromagnetic and along the b axis. The nearest-neighbor spin-spin correlations along the a and c axes are found to be weakly antiferromagnetic. The nature of the trimer spin structure of the short-range ordered state (above Tc) is similar to that of the 3D long-range ordered state (below Tc). The present investigation of microscopic nature of the magnetic ground state also explains the condition required for the 1/3 magnetization plateau to be observed in the trimer spin chains. In spite of the S =1 trimer chain system, the present compound CaNi3P4O14 is found to be a good realization of a three-dimensional magnet below Tc=16 K with full ordered moment values of ˜2 μB/Ni2 + (1.98 and 1.96 μB/Ni2 + for two Ni sites, respectively) at 1.5 K.

  17. Gyromagnetic gs factors of the spin-1/2 particles in the (1/2+-1/2--3/2-) triad of the four-vector spinor, ψμ, irreducibility and linearity

    NASA Astrophysics Data System (ADS)

    Delgado Acosta, E. G.; Banda Guzmán, V. M.; Kirchbach, M.

    2015-07-01

    The gauged Klein-Gordon equation, extended by a gsσμνFμν/4 interaction, the contraction of the electromagnetic field strength tensor, Fμν, with the generators, σμν/2, of the Lorentz group in (1/2, 0) ⊕ (0, 1/2), and gs being the gyromagnetic factor, is examined with the aim to find out as to what extent it qualifies as a wave equation for general relativistic spin-1/2 particles transforming as (1/2, 0) ⊕ (0, 1/2) and possibly distinct from the Dirac fermions. This equation can be viewed as the generalization of the gs = 2 case, known under the name of the Feynman-Gell-Mann equation, the only one which allows for a bilinearization into the gauged Dirac equation and its conjugate. At the same time, it is well-known a fact that a gs = 2 value can also be obtained upon the bilinearization of the nonrelativistic Schrödinger into nonrelativistic Pauli equations. The inevitable conclusion is that it must not be necessarily relativity which fixes the gyromagnetic factor of the electron to g(1/2) = 2, but rather the specific form of the primordial quadratic wave equation obeyed by it, that is amenable to a linearization. The fact is that space-time symmetries alone define solely the kinematic properties of the particles and neither fix the values of their interacting constants, nor do they necessarily prescribe linear Lagrangians. Information on such properties has to be obtained from additional physical inputs involving the dynamics. We here provide an example in support of the latter statement. Our case is that the spin-1/2- fermion residing within the four-vector spinor triad, ψμ (1/2+-1/2--3/2-), whose sectors at the free particle level are interconnected by spin-up and spin-down ladder operators, does not allow for a description within a linear framework at the interacting level. Upon gauging, despite transforming according to the irreducible (1/2, 1) ⊕ (1, 1/2) building block of ψμ, and being described by 16-dimensional four-vector spinors, though

  18. Exact results of a mixed spin-1/2 and spin- S Ising model on a bathroom tile (4-8) lattice: Effect of uniaxial single-ion anisotropy

    NASA Astrophysics Data System (ADS)

    Strečka, Jozef

    2006-02-01

    Effect of uniaxial single-ion anisotropy upon magnetic properties of a mixed spin-1/2 and spin- S ( S⩾1) Ising model on a bathroom tile (4-8) lattice is examined within the framework of an exact star-triangle mapping transformation. Particular attention is focused on the phase diagrams established for several values of the quantum spin number S. It is shown that the mixed-spin bathroom tile lattice exhibits very similar phase boundaries as the mixed-spin honeycomb lattice whose critical points are merely slightly enhanced with respect to the former ones. The influence of uniaxial single-ion anisotropy upon the total magnetization vs. temperature dependence is particularly investigated as well.

  19. Structure and thermodynamic properties of (C5H12N)CuBr3: a new weakly coupled antiferromagnetic spin-1/2 chain complex lying in the 1D-3D dimensional cross-over regime.

    PubMed

    Pan, Bingying; Wang, Yang; Zhang, Lijuan; Li, Shiyan

    2014-04-01

    Single crystals of a metal organic complex (C5H12N)CuBr3 (C5H12N = piperidinium, pipH for short) have been synthesized, and the structure was determined by single-crystal X-ray diffraction. (pipH)CuBr3 crystallizes in the monoclinic group C2/c. Edging-sharing CuBr5 units link to form zigzag chains along the c axis, and the neighboring Cu(II) ions with spin-1/2 are bridged by bibromide ions. Magnetic susceptibility data down to 1.8 K can be well fitted by the Bonner-Fisher formula for the antiferromagnetic spin-1/2 chain, giving the intrachain magnetic coupling constant J ≈ -17 K. At zero field, (pipH)CuBr3 shows three-dimensional (3D) order below TN = 1.68 K. Calculated by the mean-field theory, the interchain coupling constant J' = -0.91 K is obtained and the ordered magnetic moment m0 is about 0.23 μB. This value of m0 makes (pipH)CuBr3 a rare compound suitable to study the 1D-3D dimensional cross-over problem in magnetism, since both 3D order and one-dimensional (1D) quantum fluctuations are prominent. In addition, specific heat measurements reveal two successive magnetic transitions with lowering temperature when external field μ0H ≥ 3 T is applied along the a' axis. The μ0H-T phase diagram of (pipH)CuBr3 is roughly constructed. PMID:24617285

  20. Algebraic treatments of the problems of the spin-1/2 particles in the one- and two-dimensional geometry: A systematic study

    SciTech Connect

    Koc, Ramazan . E-mail: koc@gantep.edu.tr; Tuetuencueler, Hayriye; Koca, Mehmet; Olgar, Eser

    2005-10-01

    We consider solutions of the 2 x 2 matrix Hamiltonians of the physical systems within the context of the su (2) and su (1, 1) Lie algebras. Our technique is relatively simple when compared with those of others and treats those Hamiltonians which can be treated in a unified framework of the Sp (4, R) algebra. The systematic study presented here reproduces a number of earlier results in a natural way as well as leads to a novel finding. Possible generalizations of the method are also suggested.

  1. A tensor product state approach to spin-1/2 square J1-J2 antiferromagnetic Heisenberg model: evidence for deconfined quantum criticality

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Gu, Zheng-Cheng; Verstraete, Frank; Wen, Xiang-Gang

    We study this model using the cluster update algorithm for tensor product states (TPSs). We find that the ground state energies at finite sizes and in the thermodynamic limit are in good agreement with the exact diagonalization study. At the largest bond dimension available D = 9 and through finite size scaling of the magnetization order near the transition point, we accurately determine the critical point J2c1 = 0 . 53 (1) J1 and the critical exponents β = 0 . 50 (4) . In the intermediate region we find a paramagnetic ground state without any static valence bond solid (VBS) order, supported by an exponentially decaying spin-spin correlation while a power law decaying dimer-dimer correlation. By fitting a universal scaling function for the spin-spin correlation we find the critical exponents ν = 0 . 68 (3) and ηs = 0 . 34 (6) , which is very close to the observed critical exponents for deconfined quantum critical point (DQCP) in other systems. Thus our numerical results strongly suggest a Landau forbidden phase transition from Neel order to VBS order at J2c1 = 0 . 53 (1) J1 . This project is supported by the EU Strep project QUEVADIS, the ERC Grant QUERG, and the FWF SFB Grants FoQuS and ViCoM; and the Institute for Quantum Information and Matter.

  2. Series of phase transitions and multiferroicity in the quasi-two-dimensional spin-1/2 triangular-lattice antiferromagnet Ba3CoNb2O9

    NASA Astrophysics Data System (ADS)

    Lee, M.; Hwang, J.; Choi, E. S.; Ma, J.; Dela Cruz, C. R.; Zhu, M.; Ke, X.; Dun, Z. L.; Zhou, H. D.

    2014-03-01

    We have investigated the magnetic and electric ground states of a quasi-two-dimensional triangular lattice antiferromagnet (TLAF), Ba3CoNb2O9, in which the effective spin of Co2+ is 1/2. At zero field, the system undergoes a two-step transition upon cooling at TN2=1.36 K and TN1=1.10 K and enters a 120∘ ordered state. By applying magnetic fields, a series of spin states with fractions of the saturation magnetization Ms are observed. They are spin states with 1/3, 1/2, 2/3 (or √3 /3) Ms. The ferroelectricity emerges in all spin states, either with collinear or noncollinear spin structure, which makes Ba3CoNb2O9 another unique TLAF exhibiting both a series of magnetic phase transitions and multiferroicity. We discuss the role of quantum fluctuations and magnetic anisotropy in contributing more complex phase diagram compared to its sister multiferroic TLAF compound Ba3NiNb2O9 [J. Hwang et al., Phys. Rev. Lett. 109, 257205 (2012), 10.1103/PhysRevLett.109.257205].

  3. Spin-1/2 Optical Lattice Clock

    SciTech Connect

    Lemke, N. D.; Ludlow, A. D.; Barber, Z. W.; Fortier, T. M.; Diddams, S. A.; Jiang, Y.; Jefferts, S. R.; Heavner, T. P.; Parker, T. E.; Oates, C. W.

    2009-08-07

    We experimentally investigate an optical clock based on {sup 171}Yb (I=1/2) atoms confined in an optical lattice. We have evaluated all known frequency shifts to the clock transition, including a density-dependent collision shift, with a fractional uncertainty of 3.4x10{sup -16}, limited principally by uncertainty in the blackbody radiation Stark shift. We measured the absolute clock transition frequency relative to the NIST-F1 Cs fountain clock and find the frequency to be 518 295 836 590 865.2(0.7) Hz.

  4. Separability of massive field equations for spin-0 and spin-1/2 charged particles in the general nonextremal rotating charged black hole spacetimes in minimal five-dimensional gauged supergravity

    NASA Astrophysics Data System (ADS)

    Wu, Shuang-Qing

    2009-10-01

    We continue to investigate the separability of massive field equations for spin-0 and spin-1/2 charged particles in the general, nonextremal, rotating, charged, Chong-Cvetič-Lü-Pope black holes with two independent angular momenta and a nonzero cosmological constant in minimal D=5 gauged supergravity theory. We show that the complex Klein-Gordon equation and the modified Dirac equation with the inclusion of an extra counterterm can be separated by variables into purely radial and purely angular parts in this general Einstein-Maxwell-Chern-Simons background spacetime. A second-order symmetry operator that commutes with the complex Laplacian operator is constructed from the separated solutions and expressed compactly in terms of a rank-2 Stäckel-Killing tensor which admits a simple diagonal form in the chosen pentad one-forms so that it can be understood as the square of a rank-3 totally antisymmetric tensor. A first-order symmetry operator that commutes with the modified Dirac operator is expressed in terms of a rank-3 generalized Killing-Yano tensor and its covariant derivative. The Hodge dual of this generalized Killing-Yano tensor is a generalized principal conformal Killing-Yano tensor of rank-2, which can generate a “tower” of generalized (conformal) Killing-Yano and Stäckel-Killing tensors that are responsible for the whole hidden symmetries of this general, rotating, charged, Kerr-anti-de Sitter black hole geometry. In addition, the first laws of black hole thermodynamics have been generalized to the case that the cosmological constant can be viewed as a thermodynamical variable.

  5. Separability of massive field equations for spin-0 and spin-1/2 charged particles in the general nonextremal rotating charged black hole spacetimes in minimal five-dimensional gauged supergravity

    SciTech Connect

    Wu Shuangqing

    2009-10-15

    We continue to investigate the separability of massive field equations for spin-0 and spin-1/2 charged particles in the general, nonextremal, rotating, charged, Chong-Cvetic-Lue-Pope black holes with two independent angular momenta and a nonzero cosmological constant in minimal D=5 gauged supergravity theory. We show that the complex Klein-Gordon equation and the modified Dirac equation with the inclusion of an extra counterterm can be separated by variables into purely radial and purely angular parts in this general Einstein-Maxwell-Chern-Simons background spacetime. A second-order symmetry operator that commutes with the complex Laplacian operator is constructed from the separated solutions and expressed compactly in terms of a rank-2 Staeckel-Killing tensor which admits a simple diagonal form in the chosen pentad one-forms so that it can be understood as the square of a rank-3 totally antisymmetric tensor. A first-order symmetry operator that commutes with the modified Dirac operator is expressed in terms of a rank-3 generalized Killing-Yano tensor and its covariant derivative. The Hodge dual of this generalized Killing-Yano tensor is a generalized principal conformal Killing-Yano tensor of rank-2, which can generate a 'tower' of generalized (conformal) Killing-Yano and Staeckel-Killing tensors that are responsible for the whole hidden symmetries of this general, rotating, charged, Kerr-anti-de Sitter black hole geometry. In addition, the first laws of black hole thermodynamics have been generalized to the case that the cosmological constant can be viewed as a thermodynamical variable.

  6. Quantum criticality of a spin-1 XY model with easy-plane single-ion anisotropy via a two-time Green function approach avoiding the Anderson-Callen decoupling

    NASA Astrophysics Data System (ADS)

    Mercaldo, M. T.; Rabuffo, I.; De Cesare, L.; Caramico D'Auria, A.

    2016-04-01

    In this work we study the quantum phase transition, the phase diagram and the quantum criticality induced by the easy-plane single-ion anisotropy in a d-dimensional quantum spin-1 XY model in absence of an external longitudinal magnetic field. We employ the two-time Green function method by avoiding the Anderson-Callen decoupling of spin operators at the same sites which is of doubtful accuracy. Following the original Devlin procedure we treat exactly the higher order single-site anisotropy Green functions and use Tyablikov-like decouplings for the exchange higher order ones. The related self-consistent equations appear suitable for an analysis of the thermodynamic properties at and around second order phase transition points. Remarkably, the equivalence between the microscopic spin model and the continuous O(2) -vector model with transverse-Ising model (TIM)-like dynamics, characterized by a dynamic critical exponent z=1, emerges at low temperatures close to the quantum critical point with the single-ion anisotropy parameter D as the non-thermal control parameter. The zero-temperature critic anisotropy parameter Dc is obtained for dimensionalities d > 1 as a function of the microscopic exchange coupling parameter and the related numerical data for different lattices are found to be in reasonable agreement with those obtained by means of alternative analytical and numerical methods. For d > 2, and in particular for d=3, we determine the finite-temperature critical line ending in the quantum critical point and the related TIM-like shift exponent, consistently with recent renormalization group predictions. The main crossover lines between different asymptotic regimes around the quantum critical point are also estimated providing a global phase diagram and a quantum criticality very similar to the conventional ones.

  7. Einstein-Podolsky-Rosen correlations in a hybrid system

    SciTech Connect

    Caban, Pawel; Rembielinski, Jakub; Witas, Piotr; Wlodarczyk, Marta

    2011-03-15

    We calculate the relativistic correlation function for a hybrid system of a photon and a Dirac particle. Such a system can be produced in decay of another spin-(1/2) fermion. We show that the relativistic correlation function, which depends on particle momenta, may have local extrema for fermion velocity of the order 0.5c. This influences the degree of violation of the Clauser-Horne-Shimony-Holt inequality.

  8. Quasiequilibria in open quantum systems

    SciTech Connect

    Walls, Jamie D.

    2010-03-15

    In this work, the steady-state or quasiequilibrium resulting from periodically modulating the Liouvillian of an open quantum system, L-circumflex-circumflex(t), is investigated. It is shown that differences between the quasiequilibrium and the instantaneous equilibrium occur due to nonadiabatic contributions from the gauge field connecting the instantaneous eigenstates of L-circumflex-circumflex(t) to a fixed basis. These nonadiabatic contributions are shown to result in an additional rotation and/or depolarization for a single spin-1/2 in a time-dependent magnetic field and to affect the thermal mixing of two coupled spins interacting with a time-dependent magnetic field.

  9. Quantum phase transition in dimerised spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Das, Aparajita; Bhadra, Sreeparna; Saha, Sonali

    2015-11-01

    Quantum phase transition in dimerised antiferromagnetic Heisenberg spin chain has been studied. A staircase structure in the variation of concurrence within strongly coupled pairs with that of external magnetic field has been observed indicating multiple critical (or critical like) points. Emergence of entanglement due to external magnetic field or magnetic entanglement is observed for weakly coupled spin pairs too in the same dimer chain. Though closed dimerised isotropic XXX Heisenberg chains with different dimer strengths were mainly explored, analogous studies on open chains as well as closed anisotropic (XX interaction) chains with tilted external magnetic field have also been studied.

  10. Collective spin 1 singlet phase in high-pressure oxygen

    PubMed Central

    Crespo, Yanier; Fabrizio, Michele; Scandolo, Sandro; Tosatti, Erio

    2014-01-01

    Oxygen, one of the most common and important elements in nature, has an exceedingly well-explored phase diagram under pressure, up to and beyond 100 GPa. At low temperatures, the low-pressure antiferromagnetic phases below 8 GPa where O2 molecules have spin S = 1 are followed by the broad apparently nonmagnetic ε phase from about 8 to 96 GPa. In this phase, which is our focus, molecules group structurally together to form quartets while switching, as believed by most, to spin S = 0. Here we present theoretical results strongly connecting with existing vibrational and optical evidence, showing that this is true only above 20 GPa, whereas the S = 1 molecular state survives up to about 20 GPa. The ε phase thus breaks up into two: a spinless ε0 (20−96 GPa), and another ε1 (8−20 GPa) where the molecules have S = 1 but possess only short-range antiferromagnetic correlations. A local spin liquid-like singlet ground state akin to some earlier proposals, and whose optical signature we identify in existing data, is proposed for this phase. Our proposed phase diagram thus has a first-order phase transition just above 20 GPa, extending at finite temperature and most likely terminating into a crossover with a critical point near 30 GPa and 200 K. PMID:25002513

  11. Collective spin 1 singlet phase in high-pressure oxygen.

    PubMed

    Crespo, Yanier; Fabrizio, Michele; Scandolo, Sandro; Tosatti, Erio

    2014-07-22

    Oxygen, one of the most common and important elements in nature, has an exceedingly well-explored phase diagram under pressure, up to and beyond 100 GPa. At low temperatures, the low-pressure antiferromagnetic phases below 8 GPa where O2 molecules have spin S = 1 are followed by the broad apparently nonmagnetic ε phase from about 8 to 96 GPa. In this phase, which is our focus, molecules group structurally together to form quartets while switching, as believed by most, to spin S = 0. Here we present theoretical results strongly connecting with existing vibrational and optical evidence, showing that this is true only above 20 GPa, whereas the S = 1 molecular state survives up to about 20 GPa. The ε phase thus breaks up into two: a spinless ε0 (20-96 GPa), and another ε1 (8-20 GPa) where the molecules have S = 1 but possess only short-range antiferromagnetic correlations. A local spin liquid-like singlet ground state akin to some earlier proposals, and whose optical signature we identify in existing data, is proposed for this phase. Our proposed phase diagram thus has a first-order phase transition just above 20 GPa, extending at finite temperature and most likely terminating into a crossover with a critical point near 30 GPa and 200 K. PMID:25002513

  12. Dynamics of open quantum spin systems: An assessment of the quantum master equation approach.

    PubMed

    Zhao, P; De Raedt, H; Miyashita, S; Jin, F; Michielsen, K

    2016-08-01

    Data of the numerical solution of the time-dependent Schrödinger equation of a system containing one spin-1/2 particle interacting with a bath of up to 32 spin-1/2 particles is used to construct a Markovian quantum master equation describing the dynamics of the system spin. The procedure of obtaining this quantum master equation, which takes the form of a Bloch equation with time-independent coefficients, accounts for all non-Markovian effects inasmuch the general structure of the quantum master equation allows. Our simulation results show that, with a few rather exotic exceptions, the Bloch-type equation with time-independent coefficients provides a simple and accurate description of the dynamics of a spin-1/2 particle in contact with a thermal bath. A calculation of the coefficients that appear in the Redfield master equation in the Markovian limit shows that this perturbatively derived equation quantitatively differs from the numerically estimated Markovian master equation, the results of which agree very well with the solution of the time-dependent Schrödinger equation. PMID:27627265

  13. Bold Diagrammatic Monte Carlo for Fermionic and Fermionized Systems

    NASA Astrophysics Data System (ADS)

    Svistunov, Boris

    2013-03-01

    In three different fermionic cases--repulsive Hubbard model, resonant fermions, and fermionized spins-1/2 (on triangular lattice)--we observe the phenomenon of sign blessing: Feynman diagrammatic series features finite convergence radius despite factorial growth of the number of diagrams with diagram order. Bold diagrammatic Monte Carlo technique allows us to sample millions of skeleton Feynman diagrams. With the universal fermionization trick we can fermionize essentially any (bosonic, spin, mixed, etc.) lattice system. The combination of fermionization and Bold diagrammatic Monte Carlo yields a universal first-principle approach to strongly correlated lattice systems, provided the sign blessing is a generic fermionic phenomenon. Supported by NSF and DARPA

  14. Dynamic Stabilization of a Quantum Many-Body Spin System

    NASA Astrophysics Data System (ADS)

    Hoang, T. M.; Gerving, C. S.; Land, B. J.; Anquez, M.; Hamley, C. D.; Chapman, M. S.

    2013-08-01

    We demonstrate dynamic stabilization of a strongly interacting quantum spin system realized in a spin-1 atomic Bose-Einstein condensate. The spinor Bose-Einstein condensate is initialized to an unstable fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that rotate the spin-nematic many-body fluctuations and limit their growth. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is measured and compares well with a stability analysis.

  15. Dynamic stabilization of a quantum many-body spin system.

    PubMed

    Hoang, T M; Gerving, C S; Land, B J; Anquez, M; Hamley, C D; Chapman, M S

    2013-08-30

    We demonstrate dynamic stabilization of a strongly interacting quantum spin system realized in a spin-1 atomic Bose-Einstein condensate. The spinor Bose-Einstein condensate is initialized to an unstable fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that rotate the spin-nematic many-body fluctuations and limit their growth. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is measured and compares well with a stability analysis. PMID:24033006

  16. Origin of Temperature Gradient in Nonequilibrium Steady States in Weakly Coupled Quantum Spin Systems

    NASA Astrophysics Data System (ADS)

    Ishida, Toyohiko; Sugita, Ayumu

    2016-07-01

    We study nonequilibrium steady states (NESSs) in quantum spin-1/2 chains in contact with two heat baths at different temperatures. We consider the weak-coupling limit both for spin-spin coupling in the system and for system-bath coupling. This setting allows us to treat NESSs with a nonzero temperature gradient analytically. We develop a perturbation theory for this weak-coupling situation and show a simple condition for the existence of nonzero temperature gradient. This condition is independent of the integrability of the system.

  17. Dynamical symmetries and crossovers in a three-spin system with collective dissipation

    NASA Astrophysics Data System (ADS)

    Pigeon, S.; Xuereb, A.; Lesanovsky, I.; Garrahan, J. P.; De Chiara, G.; Paternostro, M.

    2015-01-01

    We consider the non-equilibrium dynamics of a simple system consisting of interacting spin-1/2 particles subjected to a collective damping. The model is close to situations that can be engineered in hybrid electro/opto-mechanical settings. Making use of large-deviation theory, we find a Gallavotti-Cohen symmetry in the dynamics of the system as well as evidence for the coexistence of two dynamical phases with different activity levels. We show that additional damping processes smooth out this behavior. Our analytical results are backed up by Monte Carlo simulations that reveal the nature of the trajectories contributing to the different dynamical phases.

  18. Quasilocal charges in integrable lattice systems

    NASA Astrophysics Data System (ADS)

    Ilievski, Enej; Medenjak, Marko; Prosen, Tomaž; Zadnik, Lenart

    2016-06-01

    We review recent progress in understanding the notion of locality in integrable quantum lattice systems. The central concept concerns the so-called quasilocal conserved quantities, which go beyond the standard perception of locality. Two systematic procedures to rigorously construct families of quasilocal conserved operators based on quantum transfer matrices are outlined, specializing on anisotropic Heisenberg XXZ spin-1/2 chain. Quasilocal conserved operators stem from two distinct classes of representations of the auxiliary space algebra, comprised of unitary (compact) representations, which can be naturally linked to the fusion algebra and quasiparticle content of the model, and non-unitary (non-compact) representations giving rise to charges, manifestly orthogonal to the unitary ones. Various condensed matter applications in which quasilocal conservation laws play an essential role are presented, with special emphasis on their implications for anomalous transport properties (finite Drude weight) and relaxation to non-thermal steady states in the quantum quench scenario.

  19. Exact spin dynamics of inhomogeneous 1-d systems at high temperature

    NASA Astrophysics Data System (ADS)

    Danieli, E. P.; Pastawski, H. M.; Levstein, P. R.

    2002-07-01

    The evaluation of spin excitation dynamics in finite 1-d systems of spins {1}/{2} with XY exchange interaction J acquired new interest because NMR experiments at high temperature ( kBT≫ J) confirmed the predicted spin wave behavior of mesoscopic echoes. In this work, we use the Jordan-Wigner transformation to obtain the exact dynamics of inhomogeneous chains and rings where the evolution is reduced to one-body dynamics. For higher dimensions, the spin excitations manifest many-body effects that can be interpreted as a simple dynamics of non-interacting fermions plus a decoherent process.

  20. Irreversibility and the Arrow of Time in a Quenched Quantum System

    NASA Astrophysics Data System (ADS)

    Batalhão, T. B.; Souza, A. M.; Sarthour, R. S.; Oliveira, I. S.; Paternostro, M.; Lutz, E.; Serra, R. M.

    2015-11-01

    Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction of time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. Using a nuclear magnetic resonance setup, we measure the nonequilibrium entropy produced in an isolated spin-1 /2 system following fast quenches of an external magnetic field. We experimentally demonstrate that it is equal to the entropic distance, expressed by the Kullback-Leibler divergence, between a microscopic process and its time reversal. Our result addresses the concept of irreversibility from a microscopic quantum standpoint.

  1. Irreversibility and the Arrow of Time in a Quenched Quantum System.

    PubMed

    Batalhão, T B; Souza, A M; Sarthour, R S; Oliveira, I S; Paternostro, M; Lutz, E; Serra, R M

    2015-11-01

    Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction of time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. Using a nuclear magnetic resonance setup, we measure the nonequilibrium entropy produced in an isolated spin-1/2 system following fast quenches of an external magnetic field. We experimentally demonstrate that it is equal to the entropic distance, expressed by the Kullback-Leibler divergence, between a microscopic process and its time reversal. Our result addresses the concept of irreversibility from a microscopic quantum standpoint. PMID:26588367

  2. Entanglement properties of correlated random spin chains and similarities with conformally invariant systems

    NASA Astrophysics Data System (ADS)

    Getelina, João C.; Alcaraz, Francisco C.; Hoyos, José A.

    2016-01-01

    We study the Rényi entanglement entropy and the Shannon mutual information for a class of spin-1/2 quantum critical XXZ chains with random coupling constants which are partially correlated. In the XX case, distinctly from the usual uncorrelated random case where the system is governed by an infinite-disorder fixed point, the correlated-disorder chain is governed by finite-disorder fixed points. Surprisingly, we verify that, although the system is not conformally invariant, the leading behavior of the Rényi entanglement entropies are similar to those of the clean (no randomness) conformally invariant system. In addition, we compute the Shannon mutual information among subsystems of our correlated-disorder quantum chain and verify the same leading behavior as the n =2 Rényi entanglement entropy. This result extends a recent conjecture concerning the same universal behavior of these quantities for conformally invariant quantum chains. For the generic spin-1/2 quantum critical XXZ case, the true asymptotic regime is identical to that in the uncorrelated disorder case. However, these finite-disorder fixed points govern the low-energy physics up to a very long crossover length scale, and the same results as in the XX case apply. Our results are based on exact numerical calculations and on a numerical strong-disorder renormalization group.

  3. Ground State of the Parallel Double Quantum Dot System

    NASA Astrophysics Data System (ADS)

    Žitko, Rok; Mravlje, Jernej; Haule, Kristjan

    2012-02-01

    We resolve the controversy regarding the ground state of the parallel double quantum dot system near half filling. The numerical renormalization group predicts an underscreened Kondo state with residual spin-1/2 magnetic moment, ln⁡2 residual impurity entropy, and unitary conductance, while the Bethe ansatz solution predicts a fully screened impurity, regular Fermi-liquid ground state, and zero conductance. We calculate the impurity entropy of the system as a function of the temperature using the hybridization-expansion continuous-time quantum Monte Carlo technique, which is a numerically exact stochastic method, and find excellent agreement with the numerical renormalization group results. We show that the origin of the unconventional behavior in this model is the odd-symmetry “dark state” on the dots.

  4. A perturbative probabilistic approach to quantum many-body systems

    NASA Astrophysics Data System (ADS)

    Di Stefano, Andrea; Ostilli, Massimo; Presilla, Carlo

    2013-04-01

    In the probabilistic approach to quantum many-body systems, the ground-state energy is the solution of a nonlinear scalar equation written either as a cumulant expansion or as an expectation with respect to a probability distribution of the potential and hopping (amplitude and phase) values recorded during an infinitely lengthy evolution. We introduce a perturbative expansion of this probability distribution which conserves, at any order, a multinomial-like structure, typical of uncorrelated systems, but includes, order by order, the statistical correlations provided by the cumulant expansion. The proposed perturbative scheme is successfully tested in the case of pseudo-spin 1/2 hard-core boson Hubbard models also when affected by a phase problem due to an applied magnetic field.

  5. Quantum impurities develop fractional local moments in spin-orbit coupled systems

    NASA Astrophysics Data System (ADS)

    Agarwala, Adhip; Shenoy, Vijay B.

    2016-06-01

    Systems with spin-orbit coupling have the potential to realize exotic quantum states which are interesting both from fundamental and technological perspectives. We investigate the physics that arises when a correlated spin-1/2 quantum impurity hybridizes with a spin-orbit coupled Fermi system. The intriguing aspect uncovered is that, in contrast to unit local moments in conventional systems, the impurity here develops a fractional local moment of 2/3. The concomitant Kondo effect has a high Kondo temperature (TK). Our theory explains these features including the origins of the fractional local moment and provides a recipe to use spin-orbit coupling (λ ) to enhance the Kondo temperature (TK˜λ4 /3 ). Even as our finding of such rich phenomena in a simple looking many-body system is of interest in itself, we also point out opportunities for systems with tunable spin-orbit coupling (such as cold atoms) to explore this physics.

  6. Algebraic versus Exponential Decoherence in Dissipative Many-Particle Systems.

    PubMed

    Cai, Zi; Barthel, Thomas

    2013-10-11

    The interplay between dissipation and internal interactions in quantum many-body systems gives rise to a wealth of novel phenomena. Here we investigate spin-1/2 chains with uniform local couplings to a Markovian environment using the time-dependent density matrix renormalization group. For the open XXZ model, we discover that the decoherence time diverges in the thermodynamic limit. The coherence decay is then algebraic instead of exponential. This is due to a vanishing gap in the spectrum of the corresponding Liouville superoperator and can be explained on the basis of a perturbative treatment. In contrast, decoherence in the open transverse-field Ising model is found to be always exponential. In this case, the internal interactions can both facilitate and impede the environment-induced decoherence. PMID:24160582

  7. Quantum phase transitions in frustrated magnetic systems

    NASA Astrophysics Data System (ADS)

    Wölfle, P.; Schmitteckert, P.

    2015-07-01

    We review our recent work on quantum phase transitions in frustrated magnetic systems. In the first part a Pseudo Fermion Functional Renormalization Group (PFFRG) method is presented. By using an exact representation of spin 1/2 operators in terms of pseudofermions a quantum spin Hamiltonian may be mapped onto an interacting fermion system. For the latter an FRG treatment is employed. The results for the J1-J2 model and similar models of frustrated interaction show phase diagrams in agreement with those obtained by other methods, but give more detailed information on the nature of correlations, in particular in the non-magnetic phases. Applications of PFFRG to geometrically frustrated systems and to highly anisotropic Kitaev type models are also reported. In the second part the derivation of quantum spin models from the microscopic many-body Hamiltonian is discussed. The results for multiband systems with strong spin-orbit interaction encountered in the iridates class of compounds are shown to resolve some of the questions posed by experiment.

  8. Optimal dynamics for quantum-state and entanglement transfer through homogeneous quantum systems

    SciTech Connect

    Banchi, L.; Apollaro, T. J. G.; Cuccoli, A.; Vaia, R.; Verrucchi, P.

    2010-11-15

    The capability of faithfully transmit quantum states and entanglement through quantum channels is one of the key requirements for the development of quantum devices. Different solutions have been proposed to accomplish such a challenging task, which, however, require either an ad hoc engineering of the internal interactions of the physical system acting as the channel or specific initialization procedures. Here we show that optimal dynamics for efficient quantum-state and entanglement transfer can be attained in generic quantum systems with homogeneous interactions by tuning the coupling between the system and the two attached qubits. We devise a general procedure to determine the optimal coupling, and we explicitly implement it in the case of a channel consisting of a spin-(1/2)XY chain. The quality of quantum-state and entanglement transfer is found to be very good and, remarkably, almost independent of the channel length.

  9. Monte Carlo and Exact Diagonalization of Copper (II) Trimer Spin Frustrated Systems

    NASA Astrophysics Data System (ADS)

    Egido-Betancourt, Hailey X.; Ter Haar, Leonard W.; Varney, Christopher N.

    We discuss the use and importance of trimer-based systems because of the spin frustration that may arise within extended lattices comprised of trimers. The possible intra- and inter-trimer exchange pathways they posses due to interconnections are evaluated using density functional theory (DFT) to identify the optimal structures that may be used in designing extended lattices. As example, trinuclear Cu36+ cores with each pair of copper atoms bridged by carboxylate ligands have three-fold symmetry. As trimers these structures have the potential to be modeled as a frustrated quantum spin-1/2 system. To analyze the magnetic ground state and topological properties, we utilize exact diagonalization on small clusters and compare with Monte Carlo simulations for a range of system sizes. Research reported in this abstract was supported by UWF NIH MARC U-STAR 1T34GM110517-01.

  10. Exact calculation of entanglement in a 19-site two-dimensional spin system

    NASA Astrophysics Data System (ADS)

    Xu, Qing; Kais, Sabre; Naumov, Maxim; Sameh, Ahmed

    2010-02-01

    Using the trace minimization algorithm, we carried out an exact calculation of entanglement in a 19-site two-dimensional transverse Ising model. This model consists of a set of localized spin-(1)/(2) particles in a two-dimensional triangular lattice coupled through exchange interaction J and subject to an external magnetic field of strength h. We demonstrate, for such a class of two-dimensional magnetic systems, that entanglement can be controlled and tuned by varying the parameter λ=h/J in the Hamiltonian and by introducing impurities into the systems. Examining the derivative of the concurrence as a function of λ shows that the system exhibits a quantum phase transition at about λc=3.01, a transition induced by quantum fluctuations at the absolute zero of temperature.

  11. On the Orthocomplementation of State-Property-Systems of Contextual Systems

    NASA Astrophysics Data System (ADS)

    D'Hooghe, Bart

    2010-12-01

    We adopt an operational approach to quantum mechanics in which a physical system is defined by the mathematical structure of its set of states and properties. We present a model in which the maximal change of state of the system due to interaction with the measurement context is controlled by a parameter which corresponds with the number N of possible outcomes in an experiment. In the case N=2 the system reduces to a model for the spin measurements on a quantum spin-1/2 particle. In the limit N→∞ the system is classical, i.e. the experiments are deterministic and its set of properties is a Boolean lattice. For intermediate situations the change of state due to measurement is neither ‘maximal’ (i.e. quantum) nor ‘zero’ (i.e. classical). We show that two of the axioms used in Piron’s representation theorem for quantum mechanics are violated, namely the covering law and weak modularity. Next, we discuss a modified version of the model for which it is even impossible to define an orthocomplementation on the set of properties. Another interesting feature for the intermediate situations of this model is that the probability of a state transition in general not only depends on the two states involved, but also on the measurement context which induces the state transition.

  12. Construction and Implementation of NMR Quantum Logic Gates for Two Spin Systems

    NASA Astrophysics Data System (ADS)

    Price, M. D.; Somaroo, S. S.; Tseng, C. H.; Gore, J. C.; Fahmy, A. F.; Havel, T. F.; Cory, D. G.

    1999-10-01

    The implementation of small prototype quantum computers has been studied through ensemble quantum computing via NMR measurements. In such laboratory studies it is convenient to have access to a wide array of logic gates. Here a systematic approach to reduce the logic gate to an NMR pulse sequence is introduced. This approach views the truth table for a quantum logic operation as a permutation matrix that corresponds to a propagator for an NMR transition. This propagator is then used as the starting point for the derivation of a pulse sequence. Pulse sequences for all the permutations of a four level system are reported along with implementations of representative examples on a two spin-{1}/{2} system, 13C-labeled chloroform.

  13. Survival Probability of the Néel State in Clean and Disordered Systems: An Overview

    NASA Astrophysics Data System (ADS)

    Torres-Herrera, E. J.; Távora, Marco; Santos, Lea F.

    2016-06-01

    In this work we provide an overview of our recent results about the quench dynamics of one-dimensional many-body quantum systems described by spin-1/2 models. To illustrate those general results, here we employ a particular and experimentally accessible initial state, namely the Néel state. Both cases are considered: clean chains without any disorder and disordered systems with static random on-site magnetic fields. The quantity used for the analysis is the probability for finding the initial state later in time, the so-called survival probability. At short times, the survival probability may decay faster than exponentially, Gaussian behaviors and even the limit established by the energy-time uncertainty relation are displayed. The dynamics at long times slows down significantly and shows a powerlaw behavior. For both scenarios, we provide analytical expressions that agree very well with our numerical results.

  14. SKRYN: A fast semismooth-Krylov-Newton method for controlling Ising spin systems

    NASA Astrophysics Data System (ADS)

    Ciaramella, G.; Borzì, A.

    2015-05-01

    The modeling and control of Ising spin systems is of fundamental importance in NMR spectroscopy applications. In this paper, two computer packages, ReHaG and SKRYN, are presented. Their purpose is to set-up and solve quantum optimal control problems governed by the Liouville master equation modeling Ising spin-1/2 systems with pointwise control constraints. In particular, the MATLAB package ReHaG allows to compute a real matrix representation of the master equation. The MATLAB package SKRYN implements a new strategy resulting in a globalized semismooth matrix-free Krylov-Newton scheme. To discretize the real representation of the Liouville master equation, a norm-preserving modified Crank-Nicolson scheme is used. Results of numerical experiments demonstrate that the SKRYN code is able to provide fast and accurate solutions to the Ising spin quantum optimization problem.

  15. Slow dynamics in many-body quantum systems with long range interactions

    NASA Astrophysics Data System (ADS)

    Santos, Lea; Perez-Bernal, Francisco

    2016-05-01

    In recent experiments with ion traps the range of the interactions between spins-1/2 can be controlled. In the limit of infinite-range interaction the system may be described by the Lipkin model, which exhibits an excited state quantum phase transition (ESQPT). The latter corresponds to a singularity in the spectrum that occurs at the ground state and propagates to higher energies as the control parameter increases beyond the ground state critical point. We show that the evolution of an initial state with energy close to the ESQPT critical point may be extremely slow. This result is surprising, since the dynamics is usually expected to be very fast in systems with long-range interactions. This behavior is justified with the analysis of the structures of the eigenstates. This work was supported by the NSF Grant No. DMR-1147430.

  16. Systematic analytical and numerical studies of highly correlated electron systems

    NASA Astrophysics Data System (ADS)

    Tsai, Shan-Wen

    Strong electron correlations in condensed matter systems give rise to a wide range of striking physical properties, producing phenomena as varied as high temperature superconductivity, metal-insulator transitions and the integer and fractional quantum Hall effects. Quantum critical systems also exhibit strong correlations between a large number of degrees of freedom. In this thesis we study these complicated systems using a combination of analytical and numerical approaches. We perform systematic investigations, which adds to the robustness of our results. We develop a new method, based on the density-matrix renormalization-group (DMRG) algorithm combined with finite-size scaling analysis, to study critical behavior in quantum spin chains and extract critical exponents. Accurate results are obtained for spin-1/2 antiferromagnetic chains and the spin-1 chain at the critical point separating the Haldane and the dimerized phases. Disorder in a system can change its properties drastically. Plateau transitions in the integer quantum Hall effect provide the clearest example of quantum critical behavior in a disordered system. We provide analytical proof that the Chalker-Coddington model, which is used to describe the plateau transitions, is quantum critical. Starting from a field theory based on this model, equivalent to a non-Hermitian supersymmetric spin chain, we prove quantum criticality by a Lieb-Schultz-Mattis type theorem. This approach was motivated by numerical results obtained using the DMRG/finite-size scaling method. Our generalized LSM theorem also applies to the spin quantum Hall effect, which can appear in disordered d-wave superconductors with broken time-reversal symmetry. The last part of the thesis is a renormalization-group study of two dimensional interacting electron systems. We obtain results relevant to high-temperature superconductors and also to the family of kappa - (BEDT - TTF)2X organic superconductors. At half filling, the fully nested

  17. Ground Band and Excited Band of Spin-1 BEC in Cigar Shaped Laser Trap

    NASA Astrophysics Data System (ADS)

    Pang, Wei; Li, Zhi-Bing; Bao, Cheng-Guang

    2007-10-01

    The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the chemical potentials. These equations are solved numerically for 23Na and 87Rb condensates. The deformed trap shows significant effects on the spectrum. This implies that the spin effect of the spinor BEC are more easily detected in an optical trap of larger aspect ratio.

  18. Quantum Monte Carlo Simulations of Adulteration Effect on Bond Alternating Spin=1/2 Chain

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Xu, Zhaoxin; Ying, Heping; Dai, Jianhui; Crompton, Peter

    The S=1/2 Heisenberg chain with bond alternation and randomness of antiferromagnetic (AFM) and ferromagnetic (FM) interactions is investigated by quantum Monte Carlo simulations of loop/cluster algorithm. Our results have shown interesting finite temperature magnetic properties of this model. The relevance of our study to former investigation results is discussed.

  19. Ground state and zero temperature phase diagrams of the XXZ antiferromagnetic spin- {1}/{2} chain

    NASA Astrophysics Data System (ADS)

    Zhou, P.

    1990-05-01

    An expression of the XXZ model is given from which the Ising, isotropic XY and Heisenberg models may be more properly obtained by varying only one anisotropy parameter. The ground state and spin configuration of the antiferromagnetic quasi-classical s = {1}/{2}XXZ chain in a magnetic field of arbitrary direction are studied. The phase diagrams with a longitudinal ( h⊥ = 0) and a transverse field ( h‖ = 0) are presented. Because we take into account an effect of anisotropy in the Zeeman interaction, the phase diagrams are quite different from those given by Kurmann, et al. [Physica A 112 (1982) 235]. A ferromagnetic-antiferromagnetic first order phase transition is indicated for the Ising case with h⊥=0.

  20. High-resolution magic angle spinning 1H MRS in prostate cancer.

    PubMed

    Decelle, Emily A; Cheng, Leo L

    2014-01-01

    Prostate cancer (PCa) is the most frequently diagnosed malignancy in men worldwide, largely as a result of the increased use of the annual serum prostate-specific antigen (PSA) screening test for detection. PSA screening has saved lives, but it has also resulted in the overtreatment of many patients with PCa because of a limited ability to accurately localize and characterize PCa lesions through imaging. High-resolution magic angle spinning (HRMAS) (1)H MRS has proven to be a strong potential clinical tool for PCa diagnosis and prognosis. The HRMAS technique allows valuable metabolic information to be obtained from ex vivo intact tissue samples and also enables the performance of histopathology on the same tissue specimens. Studies have found that the quantification of individual metabolite levels and metabolite ratios, as well as metabolomic profiles, shows strong potential to improve accuracy in PCa detection, diagnosis and monitoring. Ex vivo HRMAS is also a valuable tool for the interpretation of in vivo results, including the localization of tumors, and thus has the potential to improve in vivo diagnostic tests used in the clinic. Here, we primarily review publications of HRMAS (1)H MRS and its use for the study of intact human prostate tissue. PMID:23529951

  1. Universal relations for the two-dimensional spin-1/2 Fermi gas with contact interactions

    NASA Astrophysics Data System (ADS)

    Valiente, Manuel; Zinner, Nikolaj T.; Mølmer, Klaus

    2011-12-01

    We present universal relations for a two-dimensional Fermi gas with pairwise contact interactions. The derivation of these relations is made possible by obtaining the explicit form of a generalized function—selector—in the momentum representation. The selector implements the short-distance boundary condition between two fermions in a straightforward manner and leads to simple derivations of the universal relations, in the spirit of Tan's original method for the three-dimensional gas.

  2. Geometric versus numerical optimal control of a dissipative spin-(1/2) particle

    SciTech Connect

    Lapert, M.; Sugny, D.; Zhang, Y.; Braun, M.; Glaser, S. J.

    2010-12-15

    We analyze the saturation of a nuclear magnetic resonance (NMR) signal using optimal magnetic fields. We consider both the problems of minimizing the duration of the control and its energy for a fixed duration. We solve the optimal control problems by using geometric methods and a purely numerical approach, the grape algorithm, the two methods being based on the application of the Pontryagin maximum principle. A very good agreement is obtained between the two results. The optimal solutions for the energy-minimization problem are finally implemented experimentally with available NMR techniques.

  3. Linearized kinetic theory of spin-1/2 particles in magnetized plasmas

    SciTech Connect

    Lundin, J.; Brodin, G.

    2010-11-15

    We have considered linear kinetic theory, including the electron-spin properties in a magnetized plasma. The starting point is a mean-field Vlasov-like equation, derived from a fully quantum-mechanical treatment, where effects from the electron-spin precession and the magnetic dipole force are taken into account. The general conductivity tensor is derived, including both the free current contribution and the magnetization current associated with the spin contribution. We conclude the paper with an extensive discussion of the quantum-mechanical boundary where we list parameter conditions that must be satisfied for various quantum effects to be influential.

  4. Magnetohydrodynamic waves with relativistic electrons and positrons in degenerate spin-1/2 astrophysical plasmas

    SciTech Connect

    Maroof, R.; Ali, S.; Mushtaq, A.; Qamar, A.

    2015-11-15

    Linear properties of high and low frequency waves are studied in an electron-positron-ion (e-p-i) dense plasma with spin and relativity effects. In a low frequency regime, the magnetohydrodynamic (MHD) waves, namely, the magnetoacoustic and Alfven waves are presented in a magnetized plasma, in which the inertial ions are taken as spinless and non-degenerate, whereas the electrons and positrons are treated quantum mechanically due to their smaller mass. Quantum corrections associated with the spin magnetization and density correlations for electrons and positrons are re-considered and a generalized dispersion relation for the low frequency MHD waves is derived to account for relativistic degeneracy effects. On the basis of angles of propagation, the dispersion relations of different modes are discussed analytically in a degenerate relativistic plasma. Numerical results reveal that electron and positron relativistic degeneracy effects significantly modify the dispersive properties of MHD waves. Our present analysis should be useful for understanding the collective interactions in dense astrophysical compact objects, like, the white dwarfs and in atmosphere of neutron stars.

  5. Long-lived states with well-defined spins in spin-1 /2 homogeneous Bose gases

    NASA Astrophysics Data System (ADS)

    Yurovsky, Vladimir A.

    2016-02-01

    Many-body eigenfunctions of the total spin operator can be constructed from the spin and spatial wave functions with nontrivial permutation symmetries. Spin-dependent interactions can lead to relaxation of the spin eigenstates to the thermal equilibrium. A mechanism that stabilizes the many-body entangled states is proposed here. Surprisingly, despite coupling with the chaotic motion of the spatial degrees of freedom, the spin relaxations can be suppressed by destructive quantum interference due to spherical vector and tensor terms of the spin-dependent interactions. Tuning the scattering lengths by the method of Feshbach resonances, readily available in cold atomic laboratories, can enhance the relaxation time scales by several orders of magnitude.

  6. Theory of microwave absorption by the spin-1/2 Heisenberg-Ising magnet.

    PubMed

    Brockmann, Michael; Göhmann, Frank; Karbach, Michael; Klümper, Andreas; Weisse, Alexander

    2011-07-01

    We analyze the problem of microwave absorption by the Heisenberg-Ising magnet in terms of shifted moments of the imaginary part of the dynamical susceptibility. When both the Zeeman field and the wave vector of the incident microwave are parallel to the anisotropy axis, the first four moments determine the shift of the resonance frequency and the linewidth in a situation where the frequency is varied for fixed Zeeman field. For the one-dimensional model we can calculate the moments exactly. This provides exact data for the resonance shift and the linewidth at arbitrary temperatures and magnetic fields. In current ESR experiments the Zeeman field is varied for fixed frequency. We show how in this situation the moments give perturbative results for the resonance shift and for the integrated intensity at small anisotropy as well as an explicit formula connecting the linewidth with the anisotropy parameter in the high-temperature limit. PMID:21797567

  7. Universal spin-1/2 fermion field localization on a 5D braneworld

    NASA Astrophysics Data System (ADS)

    Barbosa-Cendejas, Nandinii; Malagón-Morejón, Dagoberto; Mora-Luna, Refugio Rigel

    2015-07-01

    In this work we present a refined method for the localization of spin- fermions on the 5D braneworld paradigm. We begin by proposing a more natural ansatz for the Yukawa coupling in the 5D bulk fermionic action, that guarantees the localization of the ground states for the 4D fermions with right- or left-chirality. In earlier works the existing freedom on the form of the Yukawa coupling was used in a rather speculative way depending on the type of model, the ansatz proposed in this work is suitable for thin and thick braneworld models and can be applied to branes made of a scalar field or not and in this sense it is the more natural choice. Furthermore, we show that the fermion ground states localization allow us to show the absence of tachyonic modes in the left- and right-chiral Kaluza-Klein mass spectrum. More precisely, we show that localization of gravity in the 5D braneworld implies the localization of the spin- fermions.

  8. Chiral and Critical Spin Liquids in Spin-1/2 Kagome Antiferromagnet

    NASA Astrophysics Data System (ADS)

    Sheng, Dongning; Zhu, Wei; Gong, Shoushu; Group of D. N. Sheng Team, Prof.

    2015-03-01

    The spin liquids (SL) and their phase transitions have attracted much attentions. The extended kagome antiferromagnet emerges as the primary candidate for hosting both time reversal symmetry (TRS) preserving and TRS breaking SLs based on DMRG simulations. To uncover the nature of the novel transition between them, we study a minimum XY model with the nearest-neighbor (NN) (Jxy), the second and third neighbor couplings (J2 xy =J3 xy =Jxy'). We identify the chiral SL (CSL) with the turn on of a small perturbation Jxy' ~ 0 . 06Jxy , which is characterized by topological Chern number and conformal edge spectrum as the ν = 1 / 2 fractional quantum Hall state. On the other hand, the NN XY model (Jxy' = 0) is shown to be a critical SL, characterized by the gapless spin singlet and vanishing small spin triplet excitations. The phase transition from the CSL to the critical SL is driven by the collapsing of singlet gap. By following the evolution of entanglement spectrum, we find the transition takes place through the coupling of the edge states with opposite chiralities, which merge into the bulk and become gapless neutral excitations. The effect of the NN spin- z coupling is also studied, which leads to a phase diagram with an extended regime for the gapless SL. U.S. Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02-06ER46305 (W.Z., D.N.S.), the National Science Foundation through Grants DMR-1408560 (S.S.G).

  9. Supersolid phase induced by correlated hopping in spin-1/2 frustrated quantum magnets.

    PubMed

    Schmidt, K P; Dorier, J; Läuchli, A M; Mila, F

    2008-03-01

    We show that correlated hopping of triplets, which is often the dominant source of kinetic energy in dimer-based frustrated quantum magnets, produces a remarkably strong tendency to form supersolid phases in a magnetic field. These phases are characterized by simultaneous modulation and ordering of the longitudinal and transverse magnetization, respectively. Using quantum Monte Carlo and a semiclassical approach for an effective hard-core boson model with nearest-neighbor repulsion on a square lattice, we prove, in particular, that a supersolid phase can exist even if the repulsion is not strong enough to stabilize an insulating phase at half-filling. Experimental implications for frustrated quantum antiferromagnets in a magnetic field at zero and finite temperature are discussed. PMID:18352679

  10. Anomalous Curie Response of Impurities in Quantum-Critical Spin-1/2 Heisenberg Antiferromagnets

    NASA Astrophysics Data System (ADS)

    Höglund, Kaj H.; Sandvik, Anders W.

    2007-07-01

    We consider a magnetic impurity in two different S=1/2 Heisenberg bilayer antiferromagnets at their respective critical interlayer couplings separating Néel and disordered ground states. We calculate the impurity susceptibility using a quantum Monte Carlo method. With intralayer couplings in only one of the layers (Kondo lattice), we observe an anomalous Curie constant C*, as predicted on the basis of field-theoretical work [S. Sachdev , Science 286, 2479 (1999)SCIEAS0036-807510.1126/science.286.5449.2479]. The value C*=0.262±0.002 is larger than the normal Curie constant C=S(S+1)/3. Our low-temperature results for a symmetric bilayer are consistent with a universal C*.

  11. Phonon-to-spin mapping in a system of a trapped ion via optimal control

    NASA Astrophysics Data System (ADS)

    Müller, Matthias M.; Poschinger, Ulrich G.; Calarco, Tommaso; Montangero, Simone; Schmidt-Kaler, Ferdinand

    2015-11-01

    We propose a protocol for measurement of the phonon number distribution of a harmonic oscillator based on selective mapping to a discrete spin-1/2 degree of freedom. We consider a system of a harmonically trapped ion, where a transition between two long-lived states can be driven with resolved motional sidebands. The required unitary transforms are generated by amplitude-modulated polychromatic radiation fields, where the time-domain ramps are obtained from numerical optimization by application of the chopped random basis algorithm (CRAB). We provide a detailed analysis of the scaling behavior of the attainable fidelities and required times for the mapping transform with respect to the size of the Hilbert space. As one application we show how the mapping can be employed as a building block for experiments which require measurement of the work distribution of a quantum process.

  12. Dynamics of two-site Fermi-Hubbard and Bose-Hubbard systems

    SciTech Connect

    Ziegler, K.

    2010-03-15

    This paper analyzes dynamical properties of small Fermi-Hubbard and Bose-Hubbard systems, focusing on the structure of the underlying Hilbert space. We evaluate time-dependent quantities such as the return probability to the initial state and the spin imbalance of spin-1/2 fermions. For the symmetric two-site Fermi-Hubbard model we find that the spin imbalance and the return probability are controlled by two and three frequencies, respectively. The spin imbalance and the return probability are identical for the asymmetric Falicov-Kimball limit and controlled by only one frequency. In general, the transition probabilities between the initial state and the energy eigenstates depend strongly on the particle-particle interaction. This is discussed for 'self-trapping' of spinless bosons in a double-well potential. We observe that the available Hilbert space is reduced significantly by strong interaction.

  13. Excited-state quantum phase transitions in many-body systems with infinite-range interaction: Localization, dynamics, and bifurcation

    NASA Astrophysics Data System (ADS)

    Santos, Lea F.; Távora, Marco; Pérez-Bernal, Francisco

    2016-07-01

    Excited-state quantum phase transitions (ESQPTs) are generalizations of quantum phase transitions to excited levels. They are associated with local divergences in the density of states. Here, we investigate how the presence of an ESQPT can be detected from the analysis of the structure of the Hamiltonian matrix, the level of localization of the eigenstates, the onset of bifurcation, and the speed of the system evolution. Our findings are illustrated for a Hamiltonian with infinite-range Ising interaction in a transverse field. This is a version of the Lipkin-Meshkov-Glick (LMG) model and the limiting case of the one-dimensional spin-1/2 system with tunable interactions realized with ion traps. From our studies for the dynamics, we uncover similarities between the LMG and the noninteracting XX models.

  14. The thermodynamic cost of driving quantum systems by their boundaries.

    PubMed

    Barra, Felipe

    2015-01-01

    The laws of thermodynamics put limits to the efficiencies of thermal machines. Analogues of these laws are now established for quantum engines weakly and passively coupled to the environment providing a framework to find improvements to their performance. Systems whose interaction with the environment is actively controlled do not fall in that framework. Here we consider systems actively and locally coupled to the environment, evolving with a so-called boundary-driven Lindblad equation. Starting from a unitary description of the system plus the environment we simultaneously obtain the Lindblad equation and the appropriate expressions for heat, work and entropy-production of the system extending the framework for the analysis of new, and some already proposed, quantum heat engines. We illustrate our findings in spin 1/2 chains and explain why an XX chain coupled in this way to a single heat bath relaxes to thermodynamic-equilibrium while and XY chain does not. Additionally, we show that an XX chain coupled to a left and a right heat baths behaves as a quantum engine, a heater or refrigerator depending on the parameters, with efficiencies bounded by Carnot efficiencies. PMID:26445899

  15. The thermodynamic cost of driving quantum systems by their boundaries

    PubMed Central

    Barra, Felipe

    2015-01-01

    The laws of thermodynamics put limits to the efficiencies of thermal machines. Analogues of these laws are now established for quantum engines weakly and passively coupled to the environment providing a framework to find improvements to their performance. Systems whose interaction with the environment is actively controlled do not fall in that framework. Here we consider systems actively and locally coupled to the environment, evolving with a so-called boundary-driven Lindblad equation. Starting from a unitary description of the system plus the environment we simultaneously obtain the Lindblad equation and the appropriate expressions for heat, work and entropy-production of the system extending the framework for the analysis of new, and some already proposed, quantum heat engines. We illustrate our findings in spin 1/2 chains and explain why an XX chain coupled in this way to a single heat bath relaxes to thermodynamic-equilibrium while and XY chain does not. Additionally, we show that an XX chain coupled to a left and a right heat baths behaves as a quantum engine, a heater or refrigerator depending on the parameters, with efficiencies bounded by Carnot efficiencies. PMID:26445899

  16. The thermodynamic cost of driving quantum systems by their boundaries

    NASA Astrophysics Data System (ADS)

    Barra, Felipe

    2015-10-01

    The laws of thermodynamics put limits to the efficiencies of thermal machines. Analogues of these laws are now established for quantum engines weakly and passively coupled to the environment providing a framework to find improvements to their performance. Systems whose interaction with the environment is actively controlled do not fall in that framework. Here we consider systems actively and locally coupled to the environment, evolving with a so-called boundary-driven Lindblad equation. Starting from a unitary description of the system plus the environment we simultaneously obtain the Lindblad equation and the appropriate expressions for heat, work and entropy-production of the system extending the framework for the analysis of new, and some already proposed, quantum heat engines. We illustrate our findings in spin 1/2 chains and explain why an XX chain coupled in this way to a single heat bath relaxes to thermodynamic-equilibrium while and XY chain does not. Additionally, we show that an XX chain coupled to a left and a right heat baths behaves as a quantum engine, a heater or refrigerator depending on the parameters, with efficiencies bounded by Carnot efficiencies.

  17. Quantum systems with position-dependent mass and spin-orbit interaction via Rashba and Dresselhaus terms

    SciTech Connect

    Schmidt, Alexandre G. M. Portugal, L. Jesus, Anderson L. de

    2015-01-15

    We consider a particle with spin 1/2 with position-dependent mass moving in a plane. Considering separately Rashba and Dresselhaus spin-orbit interactions, we write down the Hamiltonian for this problem and solve it for Dirichlet boundary conditions. Our radial wavefunctions have two contributions: homogeneous ones which are written as Bessel functions of non-integer orders—that depend on angular momentum m—and particular solutions which are obtained after decoupling the non-homogeneous system. In this process, we find non-homogeneous Bessel equation, Laguerre, as well as biconfluent Heun equation. We also present the probability densities for m = 0, 1, 2 in an annular quantum well. Our results indicate that the background as well as the spin-orbit interaction naturally splits the spinor components.

  18. Steepest-entropy-ascent quantum thermodynamic modeling of decoherence in two different microscopic composite systems

    NASA Astrophysics Data System (ADS)

    Cano-Andrade, Sergio; Beretta, Gian Paolo; von Spakovsky, Michael R.

    2015-01-01

    The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is used to model the decoherence that occurs during the state evolution of two different microscopic composite systems. The test cases are a two-spin-1/2-particle composite system and a particle-photon field composite system like that experimentally studied in cavity quantum electrodynamics. The first system is used to study the characteristics of the nonlinear equation of motion of the SEAQT framework when modeling the state evolution of a microscopic composite system with particular interest in the phenomenon of decoherence. The second system is used to compare the numerical predictions of the SEAQT framework with experimental cavity quantum electrodynamic data available in the literature. For the two different numerical cases presented, the time evolution of the density operator of the composite system as well as that of the reduced operators belonging to the two constituents is traced from an initial nonequilibrium state of the composite along its relaxation towards stable equilibrium. Results show for both cases how the initial entanglement and coherence is dissipated during the state relaxation towards a state of stable equilibrium.

  19. Boundary driven open quantum many-body systems

    SciTech Connect

    Prosen, Tomaž

    2014-01-08

    In this lecture course I outline a simple paradigm of non-eqjuilibrium quantum statistical physics, namely we shall study quantum lattice systems with local, Hamiltonian (conservative) interactions which are coupled to the environment via incoherent processes only at the system's boundaries. This is arguably the simplest nontrivial context where one can study far from equilibrium steady states and their transport properties. We shall formulate the problem in terms of a many-body Markovian master equation (the so-called Lindblad equation, and some of its extensions, e.g. the Redfield eqaution). The lecture course consists of two main parts: Firstly, and most extensively we shall present canonical Liouville-space many-body formalism, the so-called 'third quantization' and show how it can be implemented to solve bi-linear open many-particle problems, the key peradigmatic examples being the XY spin 1/2 chains or quasi-free bosonic (or harmonic) chains. Secondly, we shall outline several recent approaches on how to approach exactly solvable open quantum interacting many-body problems, such as anisotropic Heisenberg ((XXZ) spin chain or fermionic Hubbard chain.

  20. Colossal magnetocaloric effect in magneto-auxetic systems

    NASA Astrophysics Data System (ADS)

    Dudek, M. R.; Wojciechowski, K. W.; Grima, J. N.; Caruana-Gauci, R.; Dudek, K. K.

    2015-08-01

    We show that a mechanically driven magnetocaloric effect (MCE) in magneto-auxetic systems (MASs) in the vicinity of room temperature is possible and the effect can be colossal. Even at zero external magnetic field, the magnetic entropy change in this reversible process can be a few times larger in magnitude than in the case of the giant MCE discovered by Pecharsky and Gschneidner in Gd5(Si2Ge2). MAS represent a novel class of metamaterials having magnetic insertions embedded within a non-magnetic matrix which exhibits a negative Poisson’s ratio. The auxetic behaviour of the non-magnetic matrix may either enhance the magnetic ordering process or it may result in a transition to the disordered phase. In the MAS under consideration, a spin 1/2 system is chosen for the magnetic component and the well-known Onsager solution for the two-dimensional square lattice Ising model at zero external magnetic field is used to show that the isothermal change in magnetic entropy accompanying the auxetic behaviour can take a large value at room temperature. The practical importance of our findings is that MCE materials used in present engineering applications may be further enhanced by changing their geometry such that they exhibit auxetic behaviour.

  1. System requirements. [Space systems

    SciTech Connect

    Austin, R.E.

    1982-06-01

    Requirements of future space systems, including large space systems, that operate beyond the space shuttle are discussed. Typical functions required of propulsion systems in this operational regime include payload placement, retrieval, observation, servicing, space debris control and support to large space systems. These functional requirements are discussed in conjunction with two classes of propulsion systems: (1) primary or orbit transfer vehicle (OTV) and (2) secondary or systems that generally operate within or relatively near an operational base orbit. Three propulsion system types are described in relation to these requirements: cryogenic OTV, teleoperator maneuvering system and a solar electric OTV.

  2. A fully controllable Kondo system: Coupling a flux qubit and an ultracold Fermi gas

    NASA Astrophysics Data System (ADS)

    Patton, Kelly

    We show that a composite spin-1/2 Kondo system can be formed by coupling a superconducting quantum interference device (SQUID) to the internal hyperfine states of a trapped ultracold atomic Fermi gas. Here, the SQUID, or flux qubit, acts as an effective magnetic impurity that induces spin-flip scattering near the Fermi energies of the trapped gas. Although the ultracold gas and SQUID are at vastly different temperatures, the formation of a strongly correlated Kondo state between the two systems is found when the gas is cooled below the Kondo temperature. We find that the Kondo temperature of this hybrid system is within current experimental limits. Furthermore, the momentum distribution of the trapped fermions is calculated. We find that it clearly contains an experimental signature of this correlated state and the associated Kondo screening length. In addition to probing Kondo physics, the con- trollability of this system can be used to systematically explore the relaxation and equilibration of a strongly correlated system that has been initially prepared in a selected nonequilibrium state.

  3. Generalized mean-field description of entanglement in dimerized spin systems

    NASA Astrophysics Data System (ADS)

    Boette, A.; Rossignoli, R.; Canosa, N.; Matera, J. M.

    2015-02-01

    We discuss a generalized self-consistent mean-field (MF) treatment, based on the selection of an arbitrary subset of operators for representing the system density matrix, and its application to the problem of entanglement evaluation in composite quantum systems. As a specific example, we examine in detail a pair MF approach to the ground state (GS) of dimerized spin-1 /2 systems with anisotropic ferromagnetic-type X Y and X Y Z couplings in a transverse field, including chains and arrays with first neighbor and also longer range couplings. The approach is fully analytic and able to capture the main features of the GS of these systems, in contrast with the conventional single-spin MF. Its phase diagram differs significantly from that of the latter, exhibiting (Sz) parity breaking just in a finite field window if the coupling between pairs is sufficiently weak, together with a fully dimerized phase below this window and a partially aligned phase above it. It is then shown that through symmetry restoration, the approach is able to correctly predict not only the concurrence of a pair, but also its entanglement with the rest of the chain, which shows a pronounced peak in the parity breaking window. Perturbative corrections allow to reproduce more subtle observables like the entanglement between weakly coupled spins and the low lying energy spectrum. All predictions are tested against exact results for finite systems.

  4. Quantum Impurities develop Fractional Local Moments in Spin-Orbit Coupled Systems

    NASA Astrophysics Data System (ADS)

    Agarwala, Adhip; Shenoy, Vijay B.

    Systems with spin-orbit coupling have the potential to realize exotic quantum states which are interesting both from fundamental and technological perspectives. We investigate the new physics that arises when a correlated spin-1/2 quantum impurity hybridizes with a spin-orbit coupled Fermi system. The intriguing aspect uncovered is that, in contrast to unit local moment in conventional systems, the impurity here develops a fractional local moment of 2/3. The concomitant Kondo effect has a high Kondo temperature (TK). Our theory explains these novel features including the origins of the fractional local moment and provides a recipe to use spin-orbit coupling(λ) to enhance Kondo temperature (TK ~λ 4 / 3). These results will be useful in shedding light on a range of experiments, including those of magnetic impurities at oxide interfaces. Our predictions can also be directly tested in cold-atom systems where the spin-orbit coupling can be engendered via a uniform synthetic non-Abelian gauge field. In addition, this work opens up new directions of research in spin-orbit coupled Kondo lattice systems. Reference: arXiv:1509.07328 Work supported by CSIR, DST and DAE.

  5. Bipartite entanglement and entropic boundary law in lattice spin systems

    SciTech Connect

    Hamma, Alioscia; Ionicioiu, Radu; Zanardi, Paolo

    2005-02-01

    We investigate bipartite entanglement in spin-1/2 systems on a generic lattice. For states that are an equal superposition of elements of a group G of spin flips acting on the fully polarized state |0>{sup xn}, we find that the von Neumann entropy depends only on the boundary between the two subsystems A and B. These states are stabilized by the group G. A physical realization of such states is given by the ground state manifold of the Kitaev's model on a Riemann surface of genus g. For a square lattice, we find that the entropy of entanglement is bounded from above and below by functions linear in the perimeter of the subsystem A and is equal to the perimeter (up to an additive constant) when A is convex. The entropy of entanglement is shown to be related to the topological order of this model. Finally, we find that some of the ground states are absolutely entangled, i.e., no partition has zero entanglement. We also provide several examples for the square lattice.

  6. Dynamics of isolated quantum systems: many-body localization and thermalization

    NASA Astrophysics Data System (ADS)

    Torres-Herrera, E. Jonathan; Tavora, Marco; Santos, Lea F.

    2016-05-01

    We show that the transition to a many-body localized phase and the onset of thermalization can be inferred from the analysis of the dynamics of isolated quantum systems taken out of equilibrium abruptly. The systems considered are described by one-dimensional spin-1/2 models with static random magnetic fields and by power-law band random matrices. We find that the short-time decay of the survival probability of the initial state is faster than exponential for sufficiently strong perturbations. This initial evolution does not depend on whether the system is integrable or chaotic, disordered or clean. At long-times, the dynamics necessarily slows down and shows a power-law behavior. The value of the power-law exponent indicates whether the system will reach thermal equilibrium or not. We present how the properties of the spectrum, structure of the initial state, and number of particles that interact simultaneously affect the value of the power-law exponent. We also compare the results for the survival probability with those for few-body observables. EJTH aknowledges financial support from PRODEP-SEP and VIEP-BUAP, Mexico.

  7. Nematic phase in two-dimensional frustrated systems with power-law decaying interactions

    NASA Astrophysics Data System (ADS)

    Barci, Daniel G.; Ribeiro, Leonardo; Stariolo, Daniel A.

    2013-06-01

    We address the problem of orientational order in frustrated interaction systems as a function of the relative range of the competing interactions. We study a spin model Hamiltonian with short-range ferromagnetic interaction competing with an antiferromagnetic component that decays as a power law of the distance between spins, 1/rα. These systems may develop a nematic phase between the isotropic disordered and stripe phases. We evaluate the nematic order parameter using a self-consistent mean-field calculation. Our main result indicates that the nematic phase exists, at mean-field level, provided 0<α<4. We analytically compute the nematic critical temperature and show that it increases with the range of the interaction, reaching its maximum near α˜0.5. We also compute a coarse-grained effective Hamiltonian for long wavelength fluctuations. For 0<α<4 the inverse susceptibility develops a set of continuous minima at wave vectors |k⃗|=k0(α) which dictate the long-distance physics of the system. For α→4, k0→0, making the competition between interactions ineffective for greater values of α.

  8. Spin correlations and impurities in one-dimensional gapped spin systems

    NASA Astrophysics Data System (ADS)

    Xu, Guangyong

    2000-05-01

    Magnetic excitations and impurity effects in the quasi- one-dimensional spin systems Y2BaNiO5 and Cu(NO3)2 . 2.5D2O have been studied by neutron scattering. Both materials exhibit an energy gap between their ground state and first excited state. Unlike most crystalline and weakly disordered three dimensional magnets, no long-ranged magnetic order exists in these 1-D antiferromagnetic systems and new magnetic phenomena occur. With Ni2+ ions carrying spins S = 1, and coupled antiferromagnetically along the chain, Y2BaNiO 5 is one of the best experimental realizations of a Haldane spin chain. Using neutron scattering, we studied in detail low energy excitations in pure Y2BaNiO5 over the temperature range 0 < T ~ Δ/kB. In addition, effects of doping by chemical substitution in this spin liquid were also examined. Our results from Mg doped Y2BaNiO5 confirmed the theoretical prediction of chain end spin-1/2 degrees of freedom in spin-1 AFM chains. Doping with Ca into Y2BaNiO5 leads to novel excited states that fill the Haldane gap. Our data provide evidence of antiferromagnetic spin-polarization clouds around impurity sites and suggest an alternative interpretation of similar data in over-doped 2-D superconducting cuprates. Cu(NO3)2 . 2.5D2), is a strongly dimerized alternating chain compound. We have performed the first detailed mapping of the full single-particle spectrum of the material for 0.06 < kBT/J1, < 1.5. At low T there is a coherent, dispersive mode which is well-described by the Single Mode Approximation with exchange constants J 1 = 0.442(2) meV and J2 = 0.106(2) meV for the strong and weak nearest-neighbor couplings along the chain. With increasing temperature, the overall spectral weight decreases in the same way as for an ensemble of independent spin pairs. The relaxation rate is thermally activated, and wave-vector dependent.

  9. Solar system positioning system

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I.; Chui, Talso

    2006-01-01

    Power-rich spacecraft envisioned in Prometheus initiative open up possibilities for long-range high-rate communication. A constellation of spacecraft on orbits several A.U. from the Sun, equipped with laser transponders and precise clocks can be configured to measure their mutual distances to within few cm. High on-board power can create substantial non-inertial contribution to the spacecraft trajectory. We propose to alleviate this contribution by employing secondary ranging to a passive daughter spacecraft. Such constellation can form the basis of it navigation system capable of providing position information anywhere in the soIar system with similar accuracy. Apart from obvious Solar System exploration implications, this system can provide robust reference for GPS and its successors.

  10. Cluster Mean-Field Approach to the Steady-State Phase Diagram of Dissipative Spin Systems

    NASA Astrophysics Data System (ADS)

    Jin, Jiasen; Biella, Alberto; Viyuela, Oscar; Mazza, Leonardo; Keeling, Jonathan; Fazio, Rosario; Rossini, Davide

    2016-07-01

    We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free) energy. To this end, by combining the cluster methods extensively used in equilibrium phase transitions to quantum trajectories and tensor-network techniques, we extend them to nonequilibrium phase transitions in dissipative many-body systems. We analyze in detail a model of spin-1 /2 on a lattice interacting through an X Y Z Hamiltonian, each of them coupled to an independent environment that induces incoherent spin flips. In the steady-state phase diagram derived from our cluster approach, the location of the phase boundaries and even its topology radically change, introducing reentrance of the paramagnetic phase as compared to the single-site mean field where correlations are neglected. Furthermore, a stability analysis of the cluster mean field indicates a susceptibility towards a possible incommensurate ordering, not present if short-range correlations are ignored.

  11. Optimal analysis of the performance of an irreversible quantum heat engine with spin systems

    NASA Astrophysics Data System (ADS)

    Lin, Bihong; Chen, Jincan

    2005-01-01

    It is considered that the cycle of a quantum heat engine using many non-interacting spin-1/2 systems as the working substance is composed of two adiabatic and two isomagnetic field processes and is referred to as a spin quantum Brayton engine cycle. Based on the quantum master equation and semi-group approach, expressions for the efficiency and power output of the cycle are derived. By using numerical solutions, the power output of the heat engine subject to finite cycle duration is optimized. The maximum power output and the corresponding parameters are calculated numerically. The optimal region of the efficiency and the optimal ranges of temperatures of the working substance and times spent on the two isomagnetic field processes are determined, so that the general optimum performance characteristics of the cycle are revealed. Moreover, the optimal performance of the cycle in the high-temperature limit is also analysed in detail. The results obtained here are further generalized, so that they may be directly used to describe the performance of a quantum Brayton heat engine using spin-J systems as the working substance.

  12. Systems autonomy

    NASA Technical Reports Server (NTRS)

    Lum, Henry, Jr.

    1988-01-01

    Information on systems autonomy is given in viewgraph form. Information is given on space systems integration, intelligent autonomous systems, automated systems for in-flight mission operations, the Systems Autonomy Demonstration Project on the Space Station Thermal Control System, the architecture of an autonomous intelligent system, artificial intelligence research issues, machine learning, and real-time image processing.

  13. Dynamics of entanglement in a two-dimensional spin system

    SciTech Connect

    Xu Qing; Sadiek, Gehad; Kais, Sabre

    2011-06-15

    We consider the time evolution of entanglement in a finite two-dimensional transverse Ising model. The model consists of a set of seven localized spin-(1/2) particles in a two-dimensional triangular lattice coupled through nearest-neighbor exchange interaction in the presence of an external time-dependent magnetic field. The magnetic field is applied in different function forms: step, exponential, hyperbolic, and periodic. We found that the time evolution of the entanglement shows an ergodic behavior under the effect of the time-dependent magnetic fields. Also, we found that while the step magnetic field causes great disturbance to the system, creating rapid oscillations, the system shows great controllability under the effects of the other magnetic fields where the entanglement profile follows closely the shape of the applied field even with the same frequency for periodic fields. This follow-up trend breaks down as the strength of the field, the transition constant for the exponential and hyperbolic forms, or the frequency for periodic field increase leading to rapid oscillations. We observed that the entanglement is very sensitive to the initial value of the applied periodic field: the smaller the initial value is, the less distorted the entanglement profile is. Furthermore, the effect of thermal fluctuations is very devastating to the entanglement, which decays very rapidly as the temperature increases. Interestingly, although a large value of the magnetic field strength may yield a small entanglement, the magnetic field strength was found to be more persistent against thermal fluctuations than the small field strengths.

  14. Discrimination of Basal Cell Carcinoma from Normal Skin Tissue Using High-Resolution Magic Angle Spinning 1H NMR Spectroscopy

    PubMed Central

    Mun, Je-Ho; Lee, Heonho; Yoon, Dahye; Kim, Byung-Soo; Kim, Moon-Bum; Kim, Shukmann

    2016-01-01

    High-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy is a useful tool for investigating the metabolism of various cancers. Basal cell carcinoma (BCC) is the most common skin cancer. However, to our knowledge, data on metabolic profiling of BCC have not been reported in the literature. The objective of the present study was to investigate the metabolic profiling of cutaneous BCC using HR-MAS 1H NMR spectroscopy. HR-MAS 1H NMR spectroscopy was used to analyze the metabolite profile and metabolite intensity of histopathologically confirmed BCC tissues and normal skin tissue (NST) samples. The metabolic intensity normalized to the total spectral intensities in BCC and NST was compared, and multivariate analysis was performed with orthogonal partial least-squares discriminant analysis (OPLS-DA). P values < 0.05 were considered statistically significant. Univariate analysis revealed 9 metabolites that showed statistically significant difference between BCC and NST. In multivariate analysis, the OPLS-DA models built with the HR-MAS NMR metabolic profiles revealed a clear separation of BCC from NST. The receiver operating characteristic curve generated from the results revealed an excellent discrimination of BCC from NST with an area under the curve (AUC) value of 0.961. The present study demonstrated that the metabolite profile and metabolite intensity differ between BCC and NST, and that HR-MAS 1H NMR spectroscopy can be a valuable tool in the diagnosis of BCC. PMID:26934749

  15. Measurement backaction on the quantum spin-mixing dynamics of a spin-1 Bose-Einstein condensate

    SciTech Connect

    Zhang Keye; Zhou Lu; Zhang Weiping; Ling, Hong Y.; Pu Han

    2011-06-15

    We consider a small F=1 spinor condensate inside an optical cavity driven by an optical probe field, and subject the output of the probe to a homodyne detection, with the goal of investigating the effect of measurement backaction on the spin dynamics of the condensate. Using the stochastic master equation approach, we show that the effect of backaction is sensitive to not only the measurement strength but also the quantum fluctuation of the spinor condensate. The same method is also used to estimate the atom numbers below which the effect of backaction becomes so prominent that extracting spin dynamics from this cavity-based detection scheme is no longer practical.

  16. Transition from hadronic to partonic interactions for a composite spin-1/2 model of a nucleon

    SciTech Connect

    Tjon, J. A.; Wallace, S. J.

    2000-12-01

    A simple model of a composite nucleon is developed in which a fermion and a boson, representing quark and diquark constituents of the nucleon, form a bound state owing to a contact interaction. Photon and pion couplings to the quark provide vertex functions for the photon and pion interactions with the composite nucleon. By a suitable choice of cutoff parameters of the model, realistic electromagnetic form factors are obtained for the proton. When a pseudoscalar pion-quark coupling is used, the pion-nucleon coupling is predominantly pseudovector. A virtual photopion amplitude is considered in which there are two types of contributions: hadronic contributions where the photon and pion interactions have an intervening propagator of the nucleon or its excited states, and contactlike contributions where the photon and pion interactions occur within a single vertex. At large Q, the contactlike contributions are dominant. The model nucleon exhibits scaling behavior in deep-inelastic scattering and the normalization of the parton distribution provides a rough normalization of the contactlike contributions. Calculations for the virtual photopion amplitude are performed using kinematics appropriate to its occurrence as a meson-exchange current in electron-deuteron scattering. The results suggest that the contactlike terms can dominate the meson-exchange current for Q>1GeV/c. There is a direct connection of the contactlike terms to the off-forward parton distributions of the model nucleon.

  17. Effects of the biaxial transverse crystal-field on the phase diagrams of a spin-1 nanowire

    NASA Astrophysics Data System (ADS)

    Magoussi, H.; Zaim, A.; Boughrara, M.; Kerouad, M.

    2016-09-01

    By using the effective field theory based on a probability distribution method, the phase diagrams and the magnetic properties of an Ising nanowire in the presence of the biaxial transverse crystal-field are investigated. The effects of the biaxial transverse crystal field, the interfacial coupling and the exchange interaction in the surface on the phase diagram, the magnetization and the internal energy are examined. Some characteristic phenomena are found such as the tricritical behavior, the critical end point and the re-entrant phenomenon.

  18. Structural and magnetic properties of quasi-1 and 2D pyrazine-containing spin-1/2 antiferromagnets.

    SciTech Connect

    Manson, J. L.; Connor, M. M.; Schlueter, J. A.; Hyzer, K. A.; Kykeem, A.; Materials Science Division; Eastern Washington Univ.

    2007-06-01

    Aqueous reaction of Cu(BF{sub 4}){sub 2}, NH{sub 4}HF{sub 2}, and pyrazine leads to formation of a novel 3D framework, [Cu(HF{sub 2})(pyz){sub 2}]BF{sub 4} (1), where 2D [Cu(pyz){sub 2}]{sup 2+} square layers are connected via HF{sub 2}{sup -}. A second compound, Cu(ReO{sub 4}){sub 2}(H{sub 2}O){sub 2}(pyz) (2), was the result of our attempt to create the perrhenate analog of 1; a linear chain compound consisting of CuO{sub 4}N{sub 2} octahedra linked through pyrazine ligands formed instead. Both compounds exhibit extensive hydrogen bonding interactions where bifluoride, F...H...F{sup -}, and O-H...O link layers and chains together in 1 and 2, respectively. Broad maxima indicative of short-range magnetic ordering (SRO) were observed in the magnetic susceptibility at 5.5 (1) and 7.7 K (2) while no evidence for the transition to long-range magnetic ordering (LRO) was detected above 2 K.

  19. Biochemical classification of kidney carcinoma biopsy samples using magic-angle-spinning 1H nuclear magnetic resonance spectroscopy.

    PubMed

    Moka, D; Vorreuther, R; Schicha, H; Spraul, M; Humpfer, E; Lipinski, M; Foxall, P J; Nicholson, J K; Lindon, J C

    1998-05-01

    High resolution 1H nuclear magnetic resonance (NMR) spectra using spinning at the magic angle (1H MAS NMR) have been obtained on intact normal and pathological kidney tissue samples from patients undergoing surgery for renal cell carcinoma (RCC). The spectra were measured on ca. 80 mg samples and provided high resolution 1H NMR spectra in which effects of dipolar couplings, chemical shift anisotropy and magnetic susceptibility differences are minimised thus yielding high spectral resolution. Conventional one-dimensional and spin-echo spectra and two-dimensional J-resolved, TOCSY and 1H-13C HMQC spectra were also measured on selected samples and these allowed the assignment of resonances of endogenous substances comprising both cytosolic and membrane components. The tumour tissues were characterised principally by an increased lipid content. These are the first reported results on human tumour tissues using this technique and the approach offers potential for the rapid classification of different types of tumour tissue. PMID:9608434

  20. Immune System

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Immune System KidsHealth > For Teens > Immune System Print A A ... could put us out of commission. What the Immune System Does The immune (pronounced: ih-MYOON) system, which ...

  1. Editorial: Focus on Dynamics and Thermalization in Isolated Quantum Many-Body Systems

    NASA Astrophysics Data System (ADS)

    Cazalilla, M. A.; Rigol, M.

    2010-05-01

    understand many-body quantum systems. This focus issue of New Journal Physics brings together both experimentalists and theoreticians working on these problems to provide a comprehensive picture of the state of the field. Focus on Dynamics and Thermalization in Isolated Quantum Many-Body Systems Contents Spin squeezing of high-spin, spatially extended quantum fields Jay D Sau, Sabrina R Leslie, Marvin L Cohen and Dan M Stamper-Kurn Thermodynamic entropy of a many-body energy eigenstate J M Deutsch Ground states and dynamics of population-imbalanced Fermi condensates in one dimension Masaki Tezuka and Masahito Ueda Relaxation dynamics in the gapped XXZ spin-1/2 chain Jorn Mossel and Jean-Sébastien Caux Canonical thermalization Peter Reimann Minimally entangled typical thermal state algorithms E M Stoudenmire and Steven R White Manipulation of the dynamics of many-body systems via quantum control methods Julie Dinerman and Lea F Santos Multimode analysis of non-classical correlations in double-well Bose-Einstein condensates Andrew J Ferris and Matthew J Davis Thermalization in a quasi-one-dimensional ultracold bosonic gas I E Mazets and J Schmiedmayer Two simple systems with cold atoms: quantum chaos tests and non-equilibrium dynamics Cavan Stone, Yassine Ait El Aoud, Vladimir A Yurovsky and Maxim Olshanii On the speed of fluctuations around thermodynamic equilibrium Noah Linden, Sandu Popescu, Anthony J Short and Andreas Winter A quantum central limit theorem for non-equilibrium systems: exact local relaxation of correlated states M Cramer and J Eisert Quantum quench dynamics of the sine-Gordon model in some solvable limits A Iucci and M A Cazalilla Nonequilibrium quantum dynamics of atomic dark solitons A D Martin and J Ruostekoski Quantum quenches in the anisotropic spin-1⁄2 Heisenberg chain: different approaches to many-body dynamics far from equilibrium Peter Barmettler, Matthias Punk, Vladimir Gritsev, Eugene Demler and Ehud Altman Crossover from adiabatic to sudden

  2. Equivalence between Redfield- and master-equation approaches for a time-dependent quantum system and coherence control

    SciTech Connect

    Soares-Pinto, D. O.; Moussa, M. H. Y.; Azevedo, E. R. de; Bonagamba, T. J.; Maziero, J.; Serra, R. M.; Celeri, L. C.

    2011-06-15

    We present a derivation of the Redfield formalism for treating the dissipative dynamics of a time-dependent quantum system coupled to a classical environment. We compare such a formalism with the master equation approach where the environments are treated quantum mechanically. Focusing on a time-dependent spin-1/2 system we demonstrate the equivalence between both approaches by showing that they lead to the same Bloch equations and, as a consequence, to the same characteristic times T{sub 1} and T{sub 2} (associated with the longitudinal and transverse relaxations, respectively). These characteristic times are shown to be related to the operator-sum representation and the equivalent phenomenological-operator approach. Finally, we present a protocol to circumvent the decoherence processes due to the loss of energy (and thus, associated with T{sub 1}). To this end, we simply associate the time dependence of the quantum system to an easily achieved modulated frequency. A possible implementation of the protocol is also proposed in the context of nuclear magnetic resonance.

  3. Adiabatic fast passage application in solid state NMR study of cross relaxation and molecular dynamics in heteronuclear systems.

    PubMed

    Baranowski, M; Woźniak-Braszak, A; Jurga, K

    2016-01-01

    The paper presents the benefits of using fast adiabatic passage for the study of molecular dynamics in the solid state heteronuclear systems in the laboratory frame. A homemade pulse spectrometer operating at the frequency of 30.2MHz and 28.411MHz for protons and fluorines, respectively, has been enhanced with microcontroller direct digital synthesizer DDS controller [1-4]. This work briefly describes how to construct a low-cost and easy-to-assemble adiabatic extension set for homemade and commercial spectrometers based on recently very popular Arduino shields. The described set was designed for fast adiabatic generation. Timing and synchronization problems are discussed. The cross-relaxation experiments with different initial states of the two spin systems have been performed. Contrary to our previous work [5] where the steady-state NOE experiments were conducted now proton spins (1)H are polarized in the magnetic field B0 while fluorine spins (19)F are perturbed by selective saturation for a short time and then the system is allowed to evolve for a period in the absence of a saturating field. The adiabatic passage application leads to a reversal of magnetization of fluorine spins and increases the amplitude of the signal. PMID:26705906

  4. Adiabatic fast passage application in solid state NMR study of cross relaxation and molecular dynamics in heteronuclear systems

    NASA Astrophysics Data System (ADS)

    Baranowski, M.; Woźniak-Braszak, A.; Jurga, K.

    2016-01-01

    The paper presents the benefits of using fast adiabatic passage for the study of molecular dynamics in the solid state heteronuclear systems in the laboratory frame. A homemade pulse spectrometer operating at the frequency of 30.2 MHz and 28.411 MHz for protons and fluorines, respectively, has been enhanced with microcontroller direct digital synthesizer DDS controller [1-4]. This work briefly describes how to construct a low-cost and easy-to-assemble adiabatic extension set for homemade and commercial spectrometers based on recently very popular Arduino shields. The described set was designed for fast adiabatic generation. Timing and synchronization problems are discussed. The cross-relaxation experiments with different initial states of the two spin systems have been performed. Contrary to our previous work [5] where the steady-state NOE experiments were conducted now proton spins 1H are polarized in the magnetic field B0 while fluorine spins 19F are perturbed by selective saturation for a short time and then the system is allowed to evolve for a period in the absence of a saturating field. The adiabatic passage application leads to a reversal of magnetization of fluorine spins and increases the amplitude of the signal.

  5. Domain-wall melting in ultracold-boson systems with hole and spin-flip defects

    NASA Astrophysics Data System (ADS)

    Halimeh, Jad C.; Wöllert, Anton; McCulloch, Ian; Schollwöck, Ulrich; Barthel, Thomas

    2014-06-01

    Quantum magnetism is a fundamental phenomenon of nature. As of late, it has garnered a lot of interest because experiments with ultracold atomic gases in optical lattices could be used as a simulator for phenomena of magnetic systems. A paradigmatic example is the time evolution of a domain-wall state of a spin-1/2 Heisenberg chain, the so-called domain-wall melting. The model can be implemented by having two species of bosonic atoms with unity filling and strong on-site repulsion U in an optical lattice. In this paper, we study the domain-wall melting in such a setup on the basis of the time-dependent density matrix renormalization group (tDMRG). We are particularly interested in the effects of defects that originate from an imperfect preparation of the initial state. Typical defects are holes (empty sites) and flipped spins. We show that the dominating effects of holes on observables like the spatially resolved magnetization can be taken account of by a linear combination of spatially shifted observables from the clean case. For sufficiently large U, further effects due to holes become negligible. In contrast, the effects of spin flips are more severe as their dynamics occur on the same time scale as that of the domain-wall melting itself. It is hence advisable to avoid preparation schemes that are based on spin flips.

  6. Giant magnetoresistance of edge current between fermion and spin topological systems

    NASA Astrophysics Data System (ADS)

    Slieptsov, Igor O.; Karnaukhov, Igor N.

    2015-07-01

    A spin-1/2 subsystem conjoined along a cut with a subsystem of spinless fermions in the state of topological insulator is studied on a honeycomb lattice. The model describes a junction between a 2D topological insulator and a 2D spin lattice with direction-dependent exchange interactions in topologically trivial and nontrivial phase states. The model Hamiltonian of the complex system is solved exactly by reduction to free Majorana fermions in a static ℤ2 gauge field. In contrast to junctions between topologically trivial phases, this junction is defined by chiral edge states and direct interaction between them for topologically nontrivial phases. As a result of the boundary interaction between chiral edge modes, the edge junction is defined by the Chern numbers of the subsystems: such gapless edge modes with the same (different) chirality switch on (off) an edge current between topological subsystems. The sign of the Chern number of spin subsystem is changed in an external magnetic field, thus the electric current strongly depends both on a direction and a value of an applied weak magnetic field. We provide a detailed analysis of the edge current and demonstrate how to switch on (off) the electric current in the magnetic field.

  7. Quantum sweeps, synchronization, and Kibble-Zurek physics in dissipative quantum spin systems

    NASA Astrophysics Data System (ADS)

    Henriet, Loïc; Le Hur, Karyn

    2016-02-01

    We address dissipation effects on the nonequilibrium quantum dynamics of an ensemble of spins-1/2 coupled via an Ising interaction. Dissipation is modeled by a (Ohmic) bath of harmonic oscillators at zero temperature and correspond either to the sound modes of a one-dimensional Bose-Einstein (quasi-)condensate or to the zero-point fluctuations of a long transmission line. We consider the dimer comprising two spins and the quantum Ising chain with long-range interactions and develop an (mathematically and numerically) exact stochastic approach to address nonequilibrium protocols in the presence of an environment. For the two-spin case, we first investigate the dissipative quantum phase transition induced by the environment through quantum quenches and study the effect of the environment on the synchronization properties. Then we address Landau-Zener-Stueckelberg-Majorana protocols for two spins and for the spin array. In this latter case, we adopt a stochastic mean-field point of view and present a Kibble-Zurek-type argument to account for interaction effects in the lattice. Such dissipative quantum spin arrays can be realized in ultracold atoms, trapped ions, and mesoscopic systems and are related to Kondo lattice models.

  8. Systems Thinking (and Systems Doing).

    ERIC Educational Resources Information Center

    Brethower, Dale M.; Dams, Peter-Cornelius

    1999-01-01

    Introduces human performance technology (HPT) by answering the following questions related to: what systems does; practical issues and questions to which systems thinking is relevant; research questions and answers with respect to systems thinking; how HPT practitioners can do systems thinking; systems thinking tools; what is and is not known…

  9. Exploring corner transfer matrices and corner tensors for the classical simulation of quantum lattice systems

    NASA Astrophysics Data System (ADS)

    Orús, Román

    2012-05-01

    In this paper we explore the practical use of the corner transfer matrix and its higher-dimensional generalization, the corner tensor, to develop tensor network algorithms for the classical simulation of quantum lattice systems of infinite size. This exploration is done mainly in one and two spatial dimensions (1D and 2D). We describe a number of numerical algorithms based on corner matrices and tensors to approximate different ground-state properties of these systems. The proposed methods also make use of matrix product operators and projected entangled pair operators and naturally preserve spatial symmetries of the system such as translation invariance. In order to assess the validity of our algorithms, we provide preliminary benchmarking calculations for the spin-1/2 quantum Ising model in a transverse field in both 1D and 2D. Our methods are a plausible alternative to other well-established tensor network approaches such as iDMRG and iTEBD in 1D, and iPEPS and TERG in 2D. The computational complexity of the proposed algorithms is also considered and, in 2D, important differences are found depending on the chosen simulation scheme. We also discuss further possibilities, such as 3D quantum lattice systems, periodic boundary conditions, and real-time evolution. This discussion leads us to reinterpret the standard iTEBD and iPEPS algorithms in terms of corner transfer matrices and corner tensors. Our paper also offers a perspective on many properties of the corner transfer matrix and its higher-dimensional generalizations in the light of novel tensor network methods.

  10. Far-from-Equilibrium Field Theory of Many-Body Quantum Spin Systems: Prethermalization and Relaxation of Spin Spiral States in Three Dimensions

    NASA Astrophysics Data System (ADS)

    Babadi, Mehrtash; Demler, Eugene; Knap, Michael

    2015-10-01

    We study theoretically the far-from-equilibrium relaxation dynamics of spin spiral states in the three-dimensional isotropic Heisenberg model. The investigated problem serves as an archetype for understanding quantum dynamics of isolated many-body systems in the vicinity of a spontaneously broken continuous symmetry. We present a field-theoretical formalism that systematically improves on the mean field for describing the real-time quantum dynamics of generic spin-1 /2 systems. This is achieved by mapping spins to Majorana fermions followed by a 1 /N expansion of the resulting two-particle-irreducible effective action. Our analysis reveals rich fluctuation-induced relaxation dynamics in the unitary evolution of spin spiral states. In particular, we find the sudden appearance of long-lived prethermalized plateaus with diverging lifetimes as the spiral winding is tuned toward the thermodynamically stable ferro- or antiferromagnetic phases. The emerging prethermalized states are characterized by different bosonic modes being thermally populated at different effective temperatures and by a hierarchical relaxation process reminiscent of glassy systems. Spin-spin correlators found by solving the nonequilibrium Bethe-Salpeter equation provide further insight into the dynamic formation of correlations, the fate of unstable collective modes, and the emergence of fluctuation-dissipation relations. Our predictions can be verified experimentally using recent realizations of spin spiral states with ultracold atoms in a quantum gas microscope [S. Hild et al., Phys. Rev. Lett. 113, 147205 (2014), 10.1103/PhysRevLett.113.147205].

  11. Measurement of homonuclear magnetic dipole-dipole interactions in multiple 1/2-spin systems using constant-time DQ-DRENAR NMR

    NASA Astrophysics Data System (ADS)

    Ren, Jinjun; Eckert, Hellmut

    2015-11-01

    A new pulse sequence entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. As described in the present manuscript, the efficiency and performance of this sequence can be significantly improved, if the measurement is done in the constant-time mode. We describe both the theoretical analysis of this method and its experimental validation of a number of crystalline model compounds, considering both symmetry-based and back-to-back (BABA) DQ-coherence excitation schemes. Based on the combination of theoretical analysis and experimental results we discuss the effect of experimental parameters such as the chemical shift anisotropy (CSA), the spinning rate, and the radio frequency field inhomogeneity upon its performance. Our results indicate that constant-time (CT-) DRENAR is a method of high efficiency and accuracy for compounds with multiple homonuclear spin systems with particular promise for the analysis of stronger-coupled and short T2 spin systems.

  12. Crystal Systems.

    ERIC Educational Resources Information Center

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  13. Concentrator Systems

    NASA Astrophysics Data System (ADS)

    Luque-Heredia, Ignacio; Luque, Antonio

    2015-10-01

    The following sections are included: * Introduction * The early development of CPV * Concentrator solar cells * Optics for photovoltaic concentrators * Photovoltaic concentration modules * Tracking systems for photovoltaic concentration * High-concentration systems * Rating and performance * Cost considerations * Conclusions * References

  14. Discovery Systems

    NASA Technical Reports Server (NTRS)

    Pell, Barney

    2003-01-01

    A viewgraph presentation on NASA's Discovery Systems Project is given. The topics of discussion include: 1) NASA's Computing Information and Communications Technology Program; 2) Discovery Systems Program; and 3) Ideas for Information Integration Using the Web.

  15. Fluid Management System (FMS) fluid systems overview

    NASA Technical Reports Server (NTRS)

    Baird, R. S.

    1990-01-01

    Viewgraphs on fluid management system (FMS) fluid systems overview are presented. Topics addressed include: fluid management system description including system requirements (integrated nitrogen system, integrated water system, and integrated waste gas system) and physical description; and fluid management system evolution.

  16. Linked Systems.

    ERIC Educational Resources Information Center

    Association of Research Libraries, Washington, DC.

    Three papers are compiled here for research library directors: (1) "Background: Open Systems Interconnection," in which David F. Bishop provides fundamental background information to explain the concept of the emerging technology of linked systems and open systems interconnection--i.e., an agreed upon standard set of conventions or rules that,…

  17. Systems Engineering

    NASA Technical Reports Server (NTRS)

    Pellerano, Fernando

    2015-01-01

    This short course provides information on what systems engineering is and how the systems engineer guides requirements, interfaces with the discipline leads, and resolves technical issues. There are many system-wide issues that either impact or are impacted by the thermal subsystem. This course will introduce these issues and illustrate them with real life examples.

  18. Expert systems and fuzzy systems

    SciTech Connect

    Negoita, C.

    1985-01-01

    This book examines the design of the expert computer system and how fuzzy systems can be used to deal with imprecise information. As the author explores the effects of semantic systems on decision support systems, he asserts that the utilization of fuzzy set theory can help an expert system draw from its knowledge base more efficiently and therefore make more accurate and reliable decisions. The book includes realistic status reports in approximate reasoning and knowledge representation that are supported by a ''theory of categories'' mathematical approach. The differences between symbolic and semantic manipulation are outline, and detailed information is given on the actual theory of knowledge-based systems.

  19. System Effectiveness

    SciTech Connect

    Powell, Danny H; Elwood Jr, Robert H

    2011-01-01

    An effective risk assessment system is needed to address the threat posed by an active or passive insider who, acting alone or in collusion, could attempt diversion or theft of nuclear material. It is critical that a nuclear facility conduct a thorough self-assessment of the material protection, control, and accountability (MPC&A) system to evaluate system effectiveness. Self-assessment involves vulnerability analysis and performance testing of the MPC&A system. The process should lead to confirmation that mitigating features of the system effectively minimize the threat, or it could lead to the conclusion that system improvements or upgrades are necessary to achieve acceptable protection against the threat. Analysis of the MPC&A system is necessary to understand the limits and vulnerabilities of the system to internal threats. Self-assessment helps the facility be prepared to respond to internal threats and reduce the risk of theft or diversion of nuclear material. MSET is a self-assessment or inspection tool utilizing probabilistic risk assessment (PRA) methodology to calculate the system effectiveness of a nuclear facility's MPC&A system. MSET analyzes the effectiveness of an MPC&A system based on defined performance metrics for MPC&A functions based on U.S. and international best practices and regulations. A facility's MC&A system can be evaluated at a point in time and reevaluated after upgrades are implemented or after other system changes occur. The total system or specific subareas within the system can be evaluated. Areas of potential performance improvement or system upgrade can be assessed to determine where the most beneficial and cost-effective improvements should be made. Analyses of risk importance factors show that sustainability is essential for optimal performance. The analyses reveal where performance degradation has the greatest detrimental impact on total system risk and where performance improvements have the greatest reduction in system risk

  20. Dynamics of observables and exactly solvable quantum problems: Using time-dependent density-functional theory to control quantum systems

    NASA Astrophysics Data System (ADS)

    Farzanehpour, M.; Tokatly, I. V.

    2016-05-01

    We use analytic (current) density-potential maps of time-dependent (current) density-functional theory [TD(C)DFT] to inverse engineer analytically solvable time-dependent quantum problems. In this approach the driving potential (the control signal) and the corresponding solution of the Schrödinger equation are parametrized analytically in terms of the basic TD(C)DFT observables. We describe the general reconstruction strategy and illustrate it with a number of explicit examples. First we consider the real space one-particle dynamics driven by a time-dependent electromagnetic field and recover, from the general TDDFT reconstruction formulas, the known exact solution for a driven oscillator with a time-dependent frequency. Then we use analytic maps of the lattice TD(C)DFT to control quantum dynamics in a discrete space. As a first example we construct a time-dependent potential which generates prescribed dynamics on a tight-binding chain. Then our method is applied to the dynamics of spin-1/2 driven by a time-dependent magnetic field. We design an analytic control pulse that transfers the system from the ground to excited state and vice versa. This pulse generates the spin flip thus operating as a quantum not gate.

  1. Cryogenic Systems

    NASA Astrophysics Data System (ADS)

    Hosoyama, Kenji

    2002-02-01

    In this lecture we discuss the principle of method of cooling to a very low temperature, i.e. cryogenic. The "gas molecular model" will be introduced to explain the mechanism cooling by the expansion engine and the Joule-Thomson expansion valve. These two expansion processes are normally used in helium refrigeration systems to cool the process gas to cryogenic temperature. The reverse Carnot cycle will be discussed in detail as an ideal refrigeration cycle. First the fundamental process of liquefaction and refrigeration cycles will be discussed, and then the practical helium refrigeration system. The process flow of the system and the key components; -compressor, expander, and heat exchanger- will be discussed. As an example of an actual refrigeration system, we will use the cryogenic system for the KEKB superconducting RF cavity. We will also discuss the liquid helium distribution system, which is very important, especially for the cryogenic systems used in accelerator applications. 1 Principles of Cooling and Fundamental Cooling Cycle 2 Expansion engine, Joule-Thomson expansion, kinetic molecular theory, and enthalpy 3 Liquefaction Systems 4 Refrigeration Systems 5 Practical helium liquefier/refrigeration system 6 Cryogenic System for TRISTAN Superconducting RF Cavity

  2. Unconventional phases in quantum spin and pseudospin systems in two dimensional and three dimensional lattices

    NASA Astrophysics Data System (ADS)

    Xu, Cenke

    Several examples of quantum spin systems and pseudo spin systems have been studied, and unconventional states of matters and phase transitions have been realized in all these systems under consideration. In the p +/- ip superconductor Josephson lattice and the p--band cold atomic system trapped in optical lattices, novel phases which behave similarly to 1+1 dimensional systems are realized, despite the fact that the real physical systems are in two or three dimensional spaces. For instance, by employing a spin-wave analysis together with a new duality transformation, we establish the existence and stability of a novel gapless "critical phase", which we refer to as a "bond algebraic liquid". This novel critical phase is analogous to the 1+1 dimensional algebraic boson liquid phase. The reason for the novel physics is that there is a quasilocal gauge symmetry in the effective low energy Hamiltonian. In a spin-1 system on the kagome lattice, and a hard-core boson system on the honeycomb lattice, the low energy physics is controlled by two components of compact U(1) gauge symmetries that emerge at low energy. Making use of the confinement nature of the 2+1 dimensional compact gauge theories and the powerful duality between gauge theories and height field theories, the crystalline phase diagrams are studied for both systems, and the transitions to other phases are also considered. These phase diagrams might be accessible in strongly correlated materials, or atomic systems in optical lattices. A novel quantum ground state of matter is realized in a bosonic model on three dimensional fcc lattice with emergent low energy excitations. The novel phase obtained is a stable gapless boson liquid phase, with algebraic boson density correlations. The stability of this phase is protected against the instanton effect and superfluidity by self-duality and large gauge symmetries on both sides of the duality. The gapless collective excitations of this phase closely resemble the

  3. Vector polarons in a degenerate electron system

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.; Foell, Charles A.

    2004-08-01

    We consider a one-dimensional model of an electron in a doubly (or nearly) degenerate band that interacts with elastic distortions. We show that the electron equations of motion reduce to a set of coupled nonlinear Schrödinger equations. For the case of interband electron-phonon coupling stemming from local Jahn-Teller interactions, multicomponent self-localized polaron solutions-vector polarons- are described and classified. The phase diagram for the different types of vector polarons in this model is presented. By interpreting the components of the orbital doublet as those of spin- (1)/(2) , our results can also be used to describe bound magnetic polarons.

  4. Geothermal systems

    NASA Technical Reports Server (NTRS)

    Mohl, C.

    1978-01-01

    Several tasks of JPL related to geothermal energy are discussed. The major task is the procurement and test and evaluation of a helical screw drive (wellhead unit). A general review of geothermal energy systems is given. The presentation focuses attention on geothermal reservoirs in California, with graphs and charts to support the discussion. Included are discussions on cost analysis, systems maintenance, and a comparison of geothermal and conventional heating and cooling systems.

  5. [Information systems].

    PubMed

    Rodríguez Maniega, José Antonio; Trío Maseda, Reyes

    2005-03-01

    The arrival of victims of the terrorist attacks of 11 March at the hospital put the efficiency of its information systems to the test. To be most efficient, these systems should be simple and directed, above all, to the follow-up of victims and to providing the necessary information to patients and families. A specific and easy to use system is advisable. PMID:15771852

  6. Direct observation of an out-of-plane spin polarization caused by an in-plane magnetic field in a GaAs 2D hole system

    NASA Astrophysics Data System (ADS)

    Yeoh, Lareine; Srinivasan, Ashwin; Klochan, Oleh; Micolich, Adam; Winkler, Roland; Simmons, Michelle; Ritchie, David; Pepper, Michael; Hamilton, Alexander

    2014-03-01

    Recent interest in spin-orbit coupling has led to studies of quantum confined, hole based semiconductor devices, which naturally possess strong spin-orbit interaction due to the intrinsic spin-3/2 nature of holes. In general both crystal anisotropies and quantum confinement will affect the spin properties of holes. In high symmetry crystals such anisotropies can be ignored, however in low symmetry crystals this complex interplay between the crystal and the confining potential gives rise to intriguing spin behavior, which has no counterpart in spin-1/2 electron-based systems. Here I will present the first direct observations of an unusual effect where a magnetic field applied in the plane of the 2D hole system generates a spin polarization perpendicular to the 2D plane. This out-of-plane spin polarisation is detected in transport measurements of a symmetrically doped, GaAs 2D hole quantum well in tilted magnetic fields. We are able to extract the sign of this off-diagonal component of the Landé g-factor and show that it is consistent with theory.

  7. Systemic darwinism.

    PubMed

    Winther, Rasmus Grønfeldt

    2008-08-19

    Darwin's 19th century evolutionary theory of descent with modification through natural selection opened up a multidimensional and integrative conceptual space for biology. We explore three dimensions of this space: explanatory pattern, levels of selection, and degree of difference among units of the same type. Each dimension is defined by a respective pair of poles: law and narrative explanation, organismic and hierarchical selection, and variational and essentialist thinking. As a consequence of conceptual debates in the 20th century biological sciences, the poles of each pair came to be seen as mutually exclusive opposites. A significant amount of 21st century research focuses on systems (e.g., genomic, cellular, organismic, and ecological/global). Systemic Darwinism is emerging in this context. It follows a "compositional paradigm" according to which complex systems and their hierarchical networks of parts are the focus of biological investigation. Through the investigation of systems, Systemic Darwinism promises to reintegrate each dimension of Darwin's original logical space. Moreover, this ideally and potentially unified theory of biological ontology coordinates and integrates a plurality of mathematical biological theories (e.g., self-organization/structure, cladistics/history, and evolutionary genetics/function). Integrative Systemic Darwinism requires communal articulation from a plurality of perspectives. Although it is more general than these, it draws on previous advances in Systems Theory, Systems Biology, and Hierarchy Theory. Systemic Darwinism would greatly further bioengineering research and would provide a significantly deeper and more critical understanding of biological reality. PMID:18697926

  8. Anticipatory systems as linguistic systems

    NASA Astrophysics Data System (ADS)

    Ekdahl, Bertil

    2000-05-01

    The idea of system is well established although not well defined. What makes up a system depends on the observer. Thinking in terms of systems is only a convenient way to conceptualize organizations, natural or artificial, that show coherent properties. Among all properties, which can be ascribed to systems, one property seems to be more outstanding than others, namely that of being anticipatory. In nature, anticipatory properties are found only in living organizations. In this way it can be said to separate non-living systems from living because there is no indication that any natural phenomenon occurring in systems where there is no indication of life is anticipatory. The characteristic of living systems is that they are exposed to the evolution contrary to causal systems that do not undergo changes due to the influence of the environment. Causal systems are related to the past in such a way that subsequent situations can be calculated from knowledge of past situations. In causal systems the past is the cause of the present and there is no reference to the future as a determining agent, contrary to anticipatory systems where expectations are the cause of the present action. Since anticipatory properties are characteristic of living systems, this property, as all other properties in living systems, is a result of the evolution and can be found in plants as well as in animals. Thus, it is not only tied to consciousness but is found at a more basic level, i.e., in the interplay between genotype and phenotype. Anticipation is part of the genetic language in such a way that appropriate actions, for events in the anticipatory systems environment, are inscribed in the genes. Anticipatory behavior, as a result of the interpretation of the genetic language, has been selected by the evolution. In this paper anticipatory systems are regarded as linguistic systems and I argue that as such anticipation cannot be fragmented but must be holistically studied. This has the

  9. Numerical Simulations of Quantum Many-body Systems

    SciTech Connect

    Scalapino, Douglas J. Sugar, Robert L.

    1998-04-20

    The goals of our DOE work were to develop numerical tools in order to (1) determine the actual phase of particular many-electron models and (2) to understand the underlying mechanisms responsible for the observed phases. Over the years, DOE funds provided support for a number of graduate students and postdoctoral fellows who have gone on to continue and extend this effort. Looking back, they were more successful in determining the types of correlations that developed in particular models and less successful in establishing the underlying mechanisms. For example, they found clear evidence for antiferromagnetism, d{sub x{sup 3}-y{sup 2}}-pairing correlations, and stripes in various t-t{prime}-J and Hubbard models. Here, the stripes consisted of 1/2-filled domain walls of holes separated by {pi}-phase shifted antiferromagnetic regions. They found that a next-near-neighbor hopping t{prime} with t{prime}/t > 0 suppressed the stripes and favored the d{sub x{sup 3}-y{sup 2}}-pairing correlations. They studied a model of a CuO, 2-leg ladder and found that d{sub x{sup 3}-y{sup 2}} correlations formed when the system was doped with either electrons or holes. Another example that they studied was a two-dimensional spin 1/2 easy plane model with a near-neighbor exchange J and a four-site ring exchange K. In this J-K model, as K/J is increased, one moves from XY order to stripe order and to Ising antiferromagnetic order. They are still exploring the unusual transition between the Xy and striped phase. The key feature that we found was that strongly-correlated, many-electron systems are 'delicately balanced' between different possible phases. They also believe that their work provides strong support in favor of Anderson's suggestion that the Hubbard model contains the basic physics of the cuprates. That is, it exhibits antiferromagnetism, d{sub x{sup 3}-y{sup 2}}-pairing correlations, and stripes as the half-filled model is doped with holes. They were not as successful in

  10. Educational Systems.

    ERIC Educational Resources Information Center

    Archer, Margaret

    1981-01-01

    Presents a general review of research on educational systems, with emphasis on variations in the definition of an educational system, neglected questions, areas of major concern, research needs, traditional and modern stands in the sociology of education, educational politics, and researcher bias. (DB)

  11. Systemic Change.

    ERIC Educational Resources Information Center

    Tosti, Donald T.

    2000-01-01

    Examines three factors contributing to organizational success: use of a systemic model to design and guide the change effort; analysis of interdependencies within the system and of the change potential; and use of communication methods to help ensure that the change will be supported. Presents characteristics of successful change efforts with…

  12. Power system

    DOEpatents

    Hickam, Christopher Dale

    2008-03-18

    A power system includes a prime mover, a transmission, and a fluid coupler having a selectively engageable lockup clutch. The fluid coupler may be drivingly connected between the prime mover and the transmission. Additionally, the power system may include a motor/generator drivingly connected to at least one of the prime mover and the transmission. The power-system may also include power-system controls configured to execute a control method. The control method may include selecting one of a plurality of modes of operation of the power system. Additionally, the control method may include controlling the operating state of the lockup clutch dependent upon the mode of operation selected. The control method may also include controlling the operating state of the motor/generator dependent upon the mode of operation selected.

  13. Electronic system

    DOEpatents

    Robison, G H; Dickson, J F

    1960-11-15

    An electronic system is designed for indicating the occurrence of a plurality of electrically detectable events within predetermined time intervals. The system comprises separate input means electrically associated with the events under observation an electronic channel associated with each input means, including control means and indicating means; timing means adapted to apply a signal from the input means after a predetermined time to the control means to deactivate each of the channels; and means for resetting the system to its initial condition after the observation of each group of events. (D.L.C.)

  14. System identification

    NASA Astrophysics Data System (ADS)

    Juang, Jer-Nan

    Major issues in system identification are summarized and recent advances are reviewed. Modal testing and system identification used in control theory are examined, and the mathematical relationships and conversions of the models appropriate to modal testing and those appropriate to modern control design methods are discussed. The importance of obtaining input and output matrices in modal testing is emphasized, and the changes that may be needed in modal testing procedures to meet the needs of the control system designer are addressed. Directions for future research are considered.

  15. Saturn Systems.

    PubMed

    U Rehman, Habib; McKee, Nida A; McKee, Michael L

    2016-01-15

    Several ring systems (Saturn systems) have been studied using DFT methods that include dispersion effects. Comparison with X-ray structures are made with three systems, and the agreement is quite good. Binding enthalpies and binding free energies in dichloromethane and toluene have been computed. The effect of an encapsulated lithium cation is accessed by comparing C60 @(C6 H4 )10 and [Li@C60 @(C6 H4 )10 ](+). The [Li@C60 ](+) cation is a much better acceptor than C60 which leads to greater donor-acceptor interactions and larger charge transfer from the ring to [Li@C60 ](+). PMID:26096724

  16. Processing system

    NASA Technical Reports Server (NTRS)

    Hilland, J. E.

    1983-01-01

    To implement the analysis techniques and to provide end-to-end processing, a system was designed with the following capabilities: receive and catalog data from many sources; organize the data on mass storage for rapid access; edit for reasonableness; create new data sets by sorting on parameter, averaging and merging; provide statistical analysis and display tools; and distribute data on demand. Consideration was given to developing a flexible system that could meet immediate workshop needs and respond to future requirements. System architecture and data set details implemented are discussed.

  17. Respiratory system

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G., Jr.

    1973-01-01

    The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

  18. Microelectromechanical Systems

    NASA Technical Reports Server (NTRS)

    Gabriel, Kaigham J.

    1995-01-01

    Micro-electromechanical systems (MEMS) is an enabling technology that merges computation and communication with sensing and actuation to change the way people and machines interact with the physical world. MEMS is a manufacturing technology that will impact widespread applications including: miniature inertial measurement measurement units for competent munitions and personal navigation; distributed unattended sensors; mass data storage devices; miniature analytical instruments; embedded pressure sensors; non-invasive biomedical sensors; fiber-optics components and networks; distributed aerodynamic control; and on-demand structural strength. The long term goal of ARPA's MEMS program is to merge information processing with sensing and actuation to realize new systems and strategies for both perceiving and controlling systems, processes, and the environment. The MEMS program has three major thrusts: advanced devices and processes, system design, and infrastructure.

  19. Lymph system

    MedlinePlus

    ... the lymph nodes make more infection-fighting white blood cells, which cause the nodes to swell. The swollen nodes are sometimes felt in the neck, under the arms, and groin. The lymph system includes the: Tonsils Adenoids Spleen Thymus

  20. [Systemic urticarias].

    PubMed

    Hachulla, E

    2003-05-01

    Systemic urticaria remains a challenge in terms of etiology, investigation and management. Most of cases are urticarial vasculitis consequence of inflammatory injury of capillaries and postcapillary venules in the skin. If hypocomplementemic urticarial vasculitis syndrome is a classical cause, the majority of patients have an underlying systemic disease like systemic lupus erythematosus, Sjögren's syndrome, mixed cryoglobulinemia, Still disease or cancer. Others systemic urticaria have been reported without clearly evidence of vasculitis like in primary or acquired angioedema, hereditary periodic fever syndromes and in some thyroiditis. Diagnosis needs a step to step procedure. Treatment depends the underlying disease. Some patients respond to nonsteroidal antiinflammatory drugs, some other need corticosteroids or immunosuppression. If urticarial vasculitis seems isolated in the absence of chronic obstructive pulmonary disease, antihistamines, nonsteroidal antiinflammatory drugs, colchicine, dapsone or hydroxychloroquine must be first used. PMID:12843810

  1. SAMPLING SYSTEM

    DOEpatents

    Hannaford, B.A.; Rosenberg, R.; Segaser, C.L.; Terry, C.L.

    1961-01-17

    An apparatus is given for the batch sampling of radioactive liquids such as slurries from a system by remote control, while providing shielding for protection of operating personnel from the harmful effects of radiation.

  2. Recommender systems

    NASA Astrophysics Data System (ADS)

    Lü, Linyuan; Medo, Matúš; Yeung, Chi Ho; Zhang, Yi-Cheng; Zhang, Zi-Ke; Zhou, Tao

    2012-10-01

    The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification and comparison of different approaches are lacking, which impedes further advances. In this article, we review recent developments in recommender systems and discuss the major challenges. We compare and evaluate available algorithms and examine their roles in the future developments. In addition to algorithms, physical aspects are described to illustrate macroscopic behavior of recommender systems. Potential impacts and future directions are discussed. We emphasize that recommendation has great scientific depth and combines diverse research fields which makes it interesting for physicists as well as interdisciplinary researchers.

  3. Systems and Components Fuel Delivery System, Water Delivery System, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Systems and Components - Fuel Delivery System, Water Delivery System, Derrick Crane System, and Crane System Details - Marshall Space Flight Center, F-1 Engine Static Test Stand, On Route 565 between Huntsville and Decatur, Huntsville, Madison County, AL

  4. Optically Detected Magnetic Resonance Studies on π-conjugated semiconductor systems

    SciTech Connect

    Chen, Ying

    2011-01-01

    Optically Detected Magnetic Resonance (ODMR) techniques were used to investigate the dynamics of excitons and charge carriers in π-conjugated organic semiconductors. Degradation behavior of the negative spin-1/2 electroluminescence-detected magnetic resonance (ELDMR) was observed in Alq3 devices. The increase in the resonance amplitude implies an increasing bipolaron formation during degradation, which might be the result of growth of charge traps in the device. The same behavior of the negative spin-1/2 ELDMR was observed in 2wt% Rubrene doped Tris(8-hydroxyquinolinato)aluminium (Alq3) devices. However, with increasing injection current, a positive spin-1/2 ELDMR, together with positive spin 1 triplet powder patterns at ΔmS=±1 and ΔmS=±2, emerges. Due to the similarities in the frequency dependences of single and double modulated ELDMR and the photoluminescence-detected magnetic resonance (PLDMR) results in poly[2-methoxy-5-(2 -ethyl-hexyloxy)-1,4-phenyl ene vinylene] (MEH-PPV) films, the mechanism for this positive spin-1/2 ELDMR was assigned to enhanced triplet-polaron quenching under resonance conditions. The ELDMR in rubrene doped Alq3 devices provides a path to investigate charge distribution in the device under operational conditions. Combining the results of several devices with different carrier blocking properties and the results from transient EL, it was concluded trions not only exist near buffer layer but also exist in the electron transport layer. This TPQ model can also be used to explain the positive spin-1/2 PLDMR in poly(3-hexylthiophene) (P3HT) films at low temperature and in MEH-PPV films at various temperatures up to room temperature. Through quantitative analysis, TE-polaron quenching (TPQ) model is shown having the ability to explain most behaviors of the positive spin-1/2 resonance. Photocurrent detected magnetic resonance (PCDMR) studies on MEH-PPV devices revealed a novel transient resonance signal. The signal

  5. Systems Studies

    SciTech Connect

    Graham, R.L.

    1998-03-17

    The Systems Studies Activity had two objectives: (1) to investigate nontechnical barriers to the deployment of biomass production and supply systems and (2) to enhance and extend existing systems models of bioenergy supply and use. For the first objective, the Activity focused on existing bioenergy markets. Four projects were undertaken: a comparative analysis of bioenergy in Sweden and Austria; a one-day workshop on nontechnical barriers jointly supported by the Production Systems Activity; the development and testing of a framework for analyzing barriers and drivers to bioenergy markets; and surveys of wood pellet users in Sweden, Austria and the US. For the second objective, two projects were undertaken. First, the Activity worked with the Integrated BioEnergy Systems (TBS) Activity of TEA Bioenergy Task XIII to enhance the BioEnergy Assessment Model (BEAM). This model is documented in the final report of the IBS Activity. The Systems Studies Activity contributed to enhancing the feedstock portion of the model by developing a coherent set of willow, poplar, and switchgrass production modules relevant to both the US and the UK. The Activity also developed a pretreatment module for switchgrass. Second, the Activity sponsored a three-day workshop on modeling bioenergy systems with the objectives of providing an overview of the types of models used to evaluate bioenergy and promoting communication among bioenergy modelers. There were nine guest speakers addressing different types of models used to evaluate different aspects of bioenergy, ranging from technoeconomic models based on the ASPEN software to linear programming models to develop feedstock supply curves for the US. The papers from this workshop have been submitted to Biomass and Bioenergy and are under editorial review.

  6. Systemic trauma.

    PubMed

    Goldsmith, Rachel E; Martin, Christina Gamache; Smith, Carly Parnitzke

    2014-01-01

    Substantial theoretical, empirical, and clinical work examines trauma as it relates to individual victims and perpetrators. As trauma professionals, it is necessary to acknowledge facets of institutions, cultures, and communities that contribute to trauma and subsequent outcomes. Systemic trauma-contextual features of environments and institutions that give rise to trauma, maintain it, and impact posttraumatic responses-provides a framework for considering the full range of traumatic phenomena. The current issue of the Journal of Trauma & Dissociation is composed of articles that incorporate systemic approaches to trauma. This perspective extends conceptualizations of trauma to consider the influence of environments such as schools and universities, churches and other religious institutions, the military, workplace settings, hospitals, jails, and prisons; agencies and systems such as police, foster care, immigration, federal assistance, disaster management, and the media; conflicts involving war, torture, terrorism, and refugees; dynamics of racism, sexism, discrimination, bullying, and homophobia; and issues pertaining to conceptualizations, measurement, methodology, teaching, and intervention. Although it may be challenging to expand psychological and psychiatric paradigms of trauma, a systemic trauma perspective is necessary on both scientific and ethical grounds. Furthermore, a systemic trauma perspective reflects current approaches in the fields of global health, nursing, social work, and human rights. Empirical investigations and intervention science informed by this paradigm have the potential to advance scientific inquiry, lower the incidence of a broader range of traumatic experiences, and help to alleviate personal and societal suffering. PMID:24617751

  7. Systemic fluoride.

    PubMed

    Sampaio, Fábio Correia; Levy, Steven Marc

    2011-01-01

    There is substantial evidence that fluoride, through different applications and formulas, works to control caries development. The first observations of fluoride's effects on dental caries were linked to fluoride naturally present in the drinking water, and then from controlled water fluoridation programs. Other systemic methods to deliver fluoride were later suggested, including dietary fluoride supplements such as salt and milk. These systemic methods are now being questioned due to the fact that many studies have indicated that fluoride's action relies mainly on its post-eruptive effect from topical contact with the tooth structure. It is known that even the methods of delivering fluoride known as 'systemic' act mainly through a topical effect when they are in contact with the teeth. The effectiveness of water fluoridation in many geographic areas is lower than in previous eras due to the widespread use of other fluoride modalities. Nevertheless, this evidence should not be interpreted as an indication that systemic methods are no longer relevant ways to deliver fluoride on an individual basis or for collective health programs. Caution must be taken to avoid excess ingestion of fluoride when prescribing dietary fluoride supplements for children in order to minimize the risk of dental fluorosis, particularly if there are other relevant sources of fluoride intake - such as drinking water, salt or milk and/or dentifrice. Safe and effective doses of fluoride can be achieved when combining topical and systemic methods. PMID:21701196

  8. Turbine system

    DOEpatents

    McMahan, Kevin Weston; Dillard, Daniel Jackson

    2016-05-03

    A turbine system is disclosed. The turbine system includes a transition duct having an inlet, an outlet, and a passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The turbine system further includes a turbine section connected to the transition duct. The turbine section includes a plurality of shroud blocks at least partially defining a hot gas path, a plurality of buckets at least partially disposed in the hot gas path, and a plurality of nozzles at least partially disposed in the hot gas path. At least one of a shroud block, a bucket, or a nozzle includes means for withstanding high temperatures.

  9. Memory systems.

    PubMed

    Wolk, David A; Budson, Andrew E

    2010-08-01

    Converging evidence from patient and neuroimaging studies suggests that memory is a collection of abilities that use different neuroanatomic systems. Neurologic injury may impair one or more of these memory systems. Episodic memory allows us to mentally travel back in time and relive an episode of our life. Episodic memory depends on the hippocampus, other medial temporal lobe structures, the limbic system, and the frontal lobes, as well as several other brain regions. Semantic memory provides our general knowledge about the world and is unconnected to any specific episode of our life. Although semantic memory likely involves much of the neocortex, the inferolateral temporal lobes (particularly the left) are most important. Procedural memory enables us to learn cognitive and behavioral skills and algorithms that operate at an automatic, unconscious level. Damage to the basal ganglia, cerebellum, and supplementary motor area often impair procedural memory. PMID:22810510

  10. Lindenmayer Systems

    NASA Astrophysics Data System (ADS)

    Honkala, Juha

    The theory of Lindenmayer systems studies free monoid morphisms, free monoid substitutions and their iterations. In this chapter, we discuss similar ideas in a more general framework. Instead of a free monoid, we consider the free semi-algebra S<Σ*> consisting of polynomials with non-commuting variables in Σ and coefficients in a semiring S and we study the iteration of endomorphisms of S<Σ*>. We allow various modes of iteration and we consider various classes of morphisms. Classical L systems are obtained as special cases by taking S to be the Boolean semiring. Our approach also generalizes the theory of algebraic series in noncommuting variables.

  11. ELECTRONIC SYSTEM

    DOEpatents

    Robison, G.H. et al.

    1960-11-15

    An electronic system is described for indicating the occurrence of a plurality of electrically detectable events within predetermined time intervals. It is comprised of separate input means electrically associated with the events under observation: an electronic channel associated with each input means including control means and indicating means; timing means associated with each of the input means and the control means and adapted to derive a signal from the input means and apply it after a predetermined time to the control means to effect deactivation of each of the channels; and means for resetting the system to its initial condition after observation of each group of events.

  12. Complex Systems

    PubMed Central

    Goldberger, Ary L.

    2006-01-01

    Physiologic systems in health and disease display an extraordinary range of temporal behaviors and structural patterns that defy understanding based on linear constructs, reductionist strategies, and classical homeostasis. Application of concepts and computational tools derived from the contemporary study of complex systems, including nonlinear dynamics, fractals and “chaos theory,” is having an increasing impact on biology and medicine. This presentation provides a brief overview of an emerging area of biomedical research, including recent applications to cardiopulmonary medicine and chronic obstructive lung disease. PMID:16921107

  13. Computer systems

    NASA Technical Reports Server (NTRS)

    Olsen, Lola

    1992-01-01

    In addition to the discussions, Ocean Climate Data Workshop hosts gave participants an opportunity to hear about, see, and test for themselves some of the latest computer tools now available for those studying climate change and the oceans. Six speakers described computer systems and their functions. The introductory talks were followed by demonstrations to small groups of participants and some opportunities for participants to get hands-on experience. After this familiarization period, attendees were invited to return during the course of the Workshop and have one-on-one discussions and further hands-on experience with these systems. Brief summaries or abstracts of introductory presentations are addressed.

  14. Microbiology System

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Technology originating in a NASA-sponsored study of the measurement of microbial growth in zero gravity led to the development of Biomerieux Vitek, Inc.'s VITEK system. VITEK provides a physician with accurate diagnostic information and identifies the most effective medication. Test cards are employed to identify organisms and determine susceptibility to antibiotics. A photo-optical scanner scans the card and monitors changes in the growth of cells contained within the card. There are two configurations - VITEK and VITEK JR as well as VIDAS, a companion system that detects bacteria, viruses, etc. from patient specimens. The company was originally created by McDonnell Douglas, the NASA contractor.

  15. Pauli spinors and Hestenes' geometric algebra

    NASA Astrophysics Data System (ADS)

    Hamilton, J. Dwayne

    1984-01-01

    Hestenes' geometric algebra and Pauli's two-component spinors are reviewed and are united into a simple mathematical system. The resulting formalism is used to develop a new method for spin 1/2 projection calculations and is also applied to a spin 1/2 electron magnetic resonance problem.

  16. Auditory system

    NASA Technical Reports Server (NTRS)

    Ades, H. W.

    1973-01-01

    The physical correlations of hearing, i.e. the acoustic stimuli, are reported. The auditory system, consisting of external ear, middle ear, inner ear, organ of Corti, basilar membrane, hair cells, inner hair cells, outer hair cells, innervation of hair cells, and transducer mechanisms, is discussed. Both conductive and sensorineural hearing losses are also examined.

  17. Immune System

    EPA Science Inventory

    A properly functioning immune system is essential to good health. It defends the body against infectious agents and in some cases tumor cells. Individuals with immune deficiencies resulting from genetic defects, diseases (e.g., AIDS, leukemia), or drug therapies are more suscepti...

  18. Metric System.

    ERIC Educational Resources Information Center

    Del Mod System, Dover, DE.

    This autoinstructional unit deals with the identification of units of measure in the metric system and the construction of relevant conversion tables. Students in middle school or in grade ten, taking a General Science course, can handle this learning activity. It is recommended that high, middle or low level achievers can use the program.…

  19. Irrigation System

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Under contract with Marshall Space Flight Center, Midwest Research Institute compiled a Lubrication Handbook intended as a reference source for designers and manufacturers of aerospace hardware and crews responsible for maintenance of such equipment. Engineers of Lindsay Manufacturing Company learned of this handbook through NASA Tech Briefs and used it for supplemental information in redesigning gear boxes for their center pivot agricultural irrigation system.

  20. Cardiovascular system

    MedlinePlus Videos and Cool Tools

    The cardiovascular system is composed of the heart and the network of arteries, veins, and capillaries that transport blood throughout the body. The ... which they are eliminated. Most of the blood is made up of a watery, protein-laden fluid ...

  1. Systems Science

    ERIC Educational Resources Information Center

    Christakis, Alexander; Hammond, Debora; Jackson, Michael; Laszlo, Alexander; Mitroff, Ian; Snowden, Dave; Troncale, Len; Carr-Chellman, Alison; Spector, J. Michael; Wilson, Brent

    2013-01-01

    Scholars representing the field of systems science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Alexander Christakis, Debora Hammond, Michael Jackson, Alexander Laszlo, Ian Mitroff, Dave…

  2. STAR System.

    ERIC Educational Resources Information Center

    Doverspike, James E.

    The STAR System is a developmental guidance approach to be used with elementary school children in the 5th or 6th grades. Two basic purposes underlie STAR: to increase learning potential and to enhance personal growth and development. STAR refers to 4 basic skills: sensory, thinking, adapting, and revising. Major components of the 4 skills are:…

  3. System Dynamics

    NASA Astrophysics Data System (ADS)

    Morecroft, John

    System dynamics is an approach for thinking about and simulating situations and organisations of all kinds and sizes by visualising how the elements fit together, interact and change over time. This chapter, written by John Morecroft, describes modern system dynamics which retains the fundamentals developed in the 1950s by Jay W. Forrester of the MIT Sloan School of Management. It looks at feedback loops and time delays that affect system behaviour in a non-linear way, and illustrates how dynamic behaviour depends upon feedback loop structures. It also recognises improvements as part of the ongoing process of managing a situation in order to achieve goals. Significantly it recognises the importance of context, and practitioner skills. Feedback systems thinking views problems and solutions as being intertwined. The main concepts and tools: feedback structure and behaviour, causal loop diagrams, dynamics, are practically illustrated in a wide variety of contexts from a hot water shower through to a symphony orchestra and the practical application of the approach is described through several real examples of its use for strategic planning and evaluation.

  4. Systems Biology

    SciTech Connect

    Wiley, H S.

    2006-06-01

    The biology revolution over the last 50 years has been driven by the ascendancy of molecular biology. This was enthusiastically embraced by most biologists because it took us into increasingly familiar territory. It took mysterious processes, such as the replication of genetic material and assigned them parts that could be readily understood by the human mind. When we think of ''molecular machines'' as being the underlying basis of life, we are using a paradigm derived from everyday experience. However, the price that we paid was a relentless drive towards reductionism and the attendant balkanization of biology. Now along comes ''systems biology'' that promises us a solution to the problem of ''knowing more and more about less and less''. Unlike molecular biology, systems biology appears to be taking us into unfamiliar intellectual territory, such as statistics, mathematics and computer modeling. Not surprisingly, systems biology has met with widespread skepticism and resistance. Why do we need systems biology anyway and how does this new area of research promise to change the face of biology in the next couple of decades?

  5. Surveying System

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Sunrise Geodetic Surveys are setting up their equipment for a town survey. Their equipment differs from conventional surveying systems that employ transit rod and chain to measure angles and distances. They are using ISTAC Inc.'s Model 2002 positioning system, which offers fast accurate surveying with exceptional signals from orbiting satellites. The special utility of the ISTAC Model 2002 is that it can provide positioning of the highest accuracy from Navstar PPS signals because it requires no knowledge of secret codes. It operates by comparing the frequency and time phase of a Navstar signal arriving at one ISTAC receiver with the reception of the same set of signals by another receiver. Data is computer processed and translated into three dimensional position data - latitude, longitude and elevation.

  6. Burner systems

    DOEpatents

    Doherty, Brian J.

    1984-07-10

    A burner system particularly useful for downhole deployment includes a tubular combustion chamber unit housed within a tubular coolant jacket assembly. The combustion chamber unit includes a monolithic tube of refractory material whose inner surface defines the combustion zone. A metal reinforcing sleeve surrounds and extends the length of the refractory tube. The inner surface of the coolant jacket assembly and outer surface of the combustion chamber unit are dimensioned so that those surfaces are close to one another in standby condition so that the combustion chamber unit has limited freedom to expand with that expansion being stabilized by the coolant jacket assembly so that compression forces in the refractory tube do not exceed about one-half the safe compressive stress of the material; and the materials of the combustion chamber unit are selected to establish thermal gradient parameters across the combustion chamber unit to maintain the refractory tube in compression during combustion system start up and cool down sequences.

  7. Copernican System

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The heliocentric (i.e. `Sun-centered') theory proposed by the Polish astronomer Nicolaus Copernicus (1473-1543), and published by him in 1543 in his book, De Revolutionibus Orbium Coelestium. In this system Copernicus placed the Sun at the center of the universe and regarded the Earth and the planets as moving around it in circular orbits. Because of his retention of the notion of circular motion...

  8. Gasification system

    DOEpatents

    Haldipur, Gaurang B.; Anderson, Richard G.; Cherish, Peter

    1985-01-01

    A method and system for injecting coal and process fluids into a fluidized bed gasification reactor. Three concentric tubes extend vertically upward into the fluidized bed. Coal particulates in a transport gas are injected through an inner tube, and an oxygen rich mixture of oxygen and steam are injected through an inner annulus about the inner tube. A gaseous medium relatively lean in oxygen content, such as steam, is injected through an annulus surrounding the inner annulus.

  9. Gasification system

    DOEpatents

    Haldipur, Gaurang B.; Anderson, Richard G.; Cherish, Peter

    1983-01-01

    A method and system for injecting coal and process fluids into a fluidized bed gasification reactor. Three concentric tubes extend vertically upward into the fluidized bed. Coal particulates in a transport gas are injected through an inner tube, and an oxygen rich mixture of oxygen and steam are injected through an inner annulus about the inner tube. A gaseous medium relatively lean in oxygen content, such as steam, is injected through an annulus surrounding the inner annulus.

  10. Tychonic System

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The world system proposed in 1583 by the Danish astronomer Tycho Brahe (1546-1601). Unable to accept the Copernican doctrine that the Earth moves around the Sun, he put forward the view, later disproved by Kepler (1571-1630), that the planets move around the Sun, but the Sun and Moon move around the Earth. The theory explained the observed variations of the phases of Venus, for which the Ptolemai...

  11. Imaging System

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The 1100C Virtual Window is based on technology developed under NASA Small Business Innovation (SBIR) contracts to Ames Research Center. For example, under one contract Dimension Technologies, Inc. developed a large autostereoscopic display for scientific visualization applications. The Virtual Window employs an innovative illumination system to deliver the depth and color of true 3D imaging. Its applications include surgery and Magnetic Resonance Imaging scans, viewing for teleoperated robots, training, and in aviation cockpit displays.

  12. Security system

    DOEpatents

    Baumann, Mark J.; Kuca, Michal; Aragon, Mona L.

    2016-02-02

    A security system includes a structure having a structural surface. The structure is sized to contain an asset therein and configured to provide a forceful breaching delay. The structure has an opening formed therein to permit predetermined access to the asset contained within the structure. The structure includes intrusion detection features within or associated with the structure that are activated in response to at least a partial breach of the structure.

  13. Mine system

    SciTech Connect

    Stoppani, B.R.

    1983-10-04

    A mine system comprises at least one mining machine adapted to haul itself, in a reciprocating manner, along a mineral face, and a control box housing means to control the various electrical elements of the machine(s), the box being located in a mine roadway at one end of the mineral face along which the machine(s) is reciprocating, and the box being electrically connected to a terminal box housed in a body of the machine(s).

  14. Systemic amyloidosis.

    PubMed

    Wechalekar, Ashutosh D; Gillmore, Julian D; Hawkins, Philip N

    2016-06-25

    Tissue deposition of protein fibrils causes a group of rare diseases called systemic amyloidoses. This Seminar focuses on changes in their epidemiology, the current approach to diagnosis, and advances in treatment. Systemic light chain (AL) amyloidosis is the most common of these conditions, but wild-type transthyretin cardiac amyloidosis (ATTRwt) is increasingly being diagnosed. Typing of amyloid fibrils, a critical determinant of therapy, has improved with the wide availability of laser capture and mass spectrometry from fixed histological tissue sections. Specific and accurate evaluation of cardiac amyloidosis is now possible using cardiac magnetic resonance imaging and cardiac repurposing of bone scintigraphy tracers. Survival in AL amyloidosis has improved markedly as novel chemotherapy agents have become available, but challenges remain in advanced disease. Early diagnosis, a key to better outcomes, still remains elusive. Broadening the amyloid-specific therapeutic landscape to include RNA inhibitors, fibril formation stabilisers and inhibitors, and immunotherapeutic targeting of amyloid deposits holds promise to transform outcomes in systemic amyloidoses. PMID:26719234

  15. Braking system

    DOEpatents

    Norgren, D.U.

    1982-09-23

    A balanced braking system comprising a plurality of braking assemblies located about a member to be braked. Each of the braking assemblies consists of a spring biased piston of a first material fitted into a body of a different material which has a greater contraction upon cooling than the piston material. The piston is provided with a recessed head portion over which is positioned a diaphragm and forming a space therebetween to which is connected a pressurized fluid supply. The diaphragm is controlled by the fluid in the space to contact or withdraw from the member to be braked. A cooling means causes the body within which the piston is fitted to contract more than the piston, producing a tight shrink fit therebetween. The braking system is particularly applicable for selectively braking an arbor of an electron microscope which immobilizes, for example, a vertically adjustable low temperature specimen holder during observation. The system provides balanced braking forces which can be easily removed and re-established with minimal disturbance to arbor location.

  16. Bearing system

    DOEpatents

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  17. Sterilization System

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Cox Sterile Products, Inc.'s Rapid Heat Transfer Sterilizer employs a heat exchange process that induces rapid air movement; the air becomes the heat transfer medium, maintaining a uniform temperature of 375 degrees Fahrenheit. It features pushbutton controls for three timing cycles for different instrument loads, a six-minute cycle for standard unpackaged instruments, eight minutes for certain specialized dental/medical instruments and 12 minutes for packaged instruments which can then be stored in a drawer in sterile condition. System will stay at 375 degrees all day. Continuous operation is not expensive because of the sterilizer's very low power requirements.

  18. Relaxation System

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Environ Corporation's relaxation system is built around a body lounge, a kind of super easy chair that incorporates sensory devices. Computer controlled enclosure provides filtered ionized air to create a feeling of invigoration, enhanced by mood changing aromas. Occupant is also surrounded by multidimensional audio and the lighting is programmed to change colors, patterns, and intensity periodically. These and other sensory stimulators are designed to provide an environment in which the learning process is stimulated, because research has proven that while an individual is in a deep state of relaxation, the mind is more receptive to new information.

  19. Purification system

    NASA Technical Reports Server (NTRS)

    Flanagan, David T. (Inventor); Gibbons, Randall E. (Inventor)

    1992-01-01

    A system for prolonging the life of a granulated activated charcoal (GAC) water treatment device is disclosed in which an ultraviolet light transparent material is used to constrain water to flow over carbon surfaces. It is configured to receive maximum flux from a UV radiation source for the purpose of preventing microbial proliferation on the carbon surfaces; oxidizing organic contaminants adsorbed from the water onto the carbon surfaces and from biodegradation of adsorbed microbial forms; disinfecting water; and oxidizing organic contaminants in the water.

  20. Videobasierte Systeme

    NASA Astrophysics Data System (ADS)

    Knoll, Peter

    Videosensoren spielen für Fahrerassistenz systeme eine zentrale Rolle, da sie die Interpretation visueller Informationen (Objektklassifikation) gezielt unterstützen. Im Heckbereich kann die Video sensorik in der einfachsten Variante die ultraschallbasierte Einparkhilfe bei Einpark- und Rangiervorgängen unterstützen. Beim Nachtsichtsystem NightVision wird das mit Infrarotlicht angestrahlte Umfeld vor dem Fahrzeug mit einer Frontkamera aufgenommen und im Fahrzeugcockpit auf einem Display dem Fahrer angezeigt (s. Nachtsichtsysteme). Andere Fahrerassistenzsysteme verarbeiten die Videosignale und generieren daraus gezielt Informationen, die für eigenständige Funktionen (z. B. Spurverlassenswarner) oder aber als Zusatzinformation für andere Funktionen ausgewertet werden (Sensordatenfusion).

  1. Balance System

    NASA Technical Reports Server (NTRS)

    1988-01-01

    TherEx Inc.'s AT-1 Computerized Ataxiameter precisely evaluates posture and balance disturbances that commonly accompany neurological and musculoskeletal disorders. Complete system includes two-strain gauged footplates, signal conditioning circuitry, a computer monitor, printer and a stand-alone tiltable balance platform. AT-1 serves as assessment tool, treatment monitor, and rehabilitation training device. It allows clinician to document quantitatively the outcome of treatment and analyze data over time to develop outcome standards for several classifications of patients. It can evaluate specifically the effects of surgery, drug treatment, physical therapy or prosthetic devices.

  2. Editorial: Focus on Dynamics and Thermalization in Isolated Quantum Many-Body Systems

    NASA Astrophysics Data System (ADS)

    Cazalilla, M. A.; Rigol, M.

    2010-05-01

    understand many-body quantum systems. This focus issue of New Journal Physics brings together both experimentalists and theoreticians working on these problems to provide a comprehensive picture of the state of the field. Focus on Dynamics and Thermalization in Isolated Quantum Many-Body Systems Contents Spin squeezing of high-spin, spatially extended quantum fields Jay D Sau, Sabrina R Leslie, Marvin L Cohen and Dan M Stamper-Kurn Thermodynamic entropy of a many-body energy eigenstate J M Deutsch Ground states and dynamics of population-imbalanced Fermi condensates in one dimension Masaki Tezuka and Masahito Ueda Relaxation dynamics in the gapped XXZ spin-1/2 chain Jorn Mossel and Jean-Sébastien Caux Canonical thermalization Peter Reimann Minimally entangled typical thermal state algorithms E M Stoudenmire and Steven R White Manipulation of the dynamics of many-body systems via quantum control methods Julie Dinerman and Lea F Santos Multimode analysis of non-classical correlations in double-well Bose-Einstein condensates Andrew J Ferris and Matthew J Davis Thermalization in a quasi-one-dimensional ultracold bosonic gas I E Mazets and J Schmiedmayer Two simple systems with cold atoms: quantum chaos tests and non-equilibrium dynamics Cavan Stone, Yassine Ait El Aoud, Vladimir A Yurovsky and Maxim Olshanii On the speed of fluctuations around thermodynamic equilibrium Noah Linden, Sandu Popescu, Anthony J Short and Andreas Winter A quantum central limit theorem for non-equilibrium systems: exact local relaxation of correlated states M Cramer and J Eisert Quantum quench dynamics of the sine-Gordon model in some solvable limits A Iucci and M A Cazalilla Nonequilibrium quantum dynamics of atomic dark solitons A D Martin and J Ruostekoski Quantum quenches in the anisotropic spin-1⁄2 Heisenberg chain: different approaches to many-body dynamics far from equilibrium Peter Barmettler, Matthias Punk, Vladimir Gritsev, Eugene Demler and Ehud Altman Crossover from adiabatic to sudden

  3. Transfer system

    DOEpatents

    Kurosawa, Kanji; Koga, Bunichiro; Ito, Hideki; Kiriyama, Shigeru; Higuchi, Shizuo

    2003-05-20

    A transport system includes a traveling rail (1) which constitutes a transport route and a transport body (3) which is capable of traveling on the traveling rail in the longitudinal direction of the traveling rail. Flexible drive tubes (5) are arranged on the traveling rail in the longitudinal direction of the traveling rail. The transport body includes a traveling wheel (4) which is capable of rolling on the traveling rail and drive wheels (2) which are capable of rolling on the drive tubes upon receiving the rotational drive power generated by pressure of a pressure medium supplied to the drive tubes while depressing the drive tubes. The traveling rail includes a plurality of transport sections and the transport body is capable of receiving a rotational drive force from the drive tubes at every transport sections. If necessary, a transport route changeover switch which changes over the transport route can be provided between the transport sections.

  4. Dataflow systems

    SciTech Connect

    Cohen, A.T.

    1982-01-01

    Dataflow languages are stream-oriented and functional, and assume a different operating environment. Programs in these languages are functions which define output as a function of input, with each program being a composition of subfunctions. There is no notion of a global store and, hence, there are no assignment statements. Control flow is determined by the availability of data (function arguments) and need not be explicitly specified by the programmer. The use and development of dataflow languages are motivated by three considerations. They represent parallelism naturally, particularly as it occurs in networks and distributed systems. They readily support very high level programming and their modularity and lack of side-effects makes their programs amenable to analysis. The paper briefly discusses their advantages in each of these three areas. 32 references.

  5. Systems toxicology.

    PubMed

    Hartung, Thomas; van Vliet, Erwin; Jaworska, Joanna; Bonilla, Leo; Skinner, Nigel; Thomas, Russell

    2012-01-01

    The need for a more mechanistic understanding of the ways in which chemicals modulate biological pathways is urgent if we are to identify and better assess safety issues relating to a wide range of substances developed by the pharmaceutical, chemical, agri-bio, and cosmetic industries. Omics technologies provide a valuable opportunity to refine existing methods and provide information for so-called integrated testing strategies via the creation of signatures of toxicity. By mapping these signatures to underlying pathways of toxicity, some of which have been identified by toxicologists over the last few decades, and bringing them together with pathway information determined from biochemistry and molecular biology, a "systems toxicology" approach will enable virtual experiments to be conducted that can improve the prediction of hazard and the assessment of compound toxicity. PMID:22562485

  6. Intelligent Engine Systems: Bearing System

    NASA Technical Reports Server (NTRS)

    Singh, Arnant P.

    2008-01-01

    The overall requirements necessary for sensing bearing distress and the related criteria to select a particular rotating sensor were established during the phase I. The current phase II efforts performed studies to evaluate the Robustness and Durability Enhancement of the rotating sensors, and to design, and develop the Built-in Telemetry System concepts for an aircraft engine differential sump. A generic test vehicle that can test the proposed bearing diagnostic system was designed, developed, and built. The Timken Company, who also assisted with testing the GE concept of using rotating sensors for the differential bearing diagnostics during previous phase, was selected as a subcontractor to assist General Electric (GE) for the design, and procurement of the test vehicle. A purchase order was prepared to define the different sub-tasks, and deliverables for this task. The University of Akron was selected to provide the necessary support for installing, and integrating the test vehicle with their newly designed test facility capable of simulating the operating environment for the planned testing. The planned testing with good and damaged bearings will be on hold pending further continuation of this effort during next phase.

  7. Quasi-exactly-solvable confining solutions for spin-1 and spin-0 bosons in (1+1)-dimensions with a scalar linear potential

    SciTech Connect

    Castro, Luis B.; Castro, Antonio S. de

    2014-12-15

    We point out a misleading treatment in the recent literature regarding confining solutions for a scalar potential in the context of the Duffin–Kemmer–Petiau theory. We further present the proper bound-state solutions in terms of the generalized Laguerre polynomials and show that the eigenvalues and eigenfunctions depend on the solutions of algebraic equations involving the potential parameter and the quantum number.

  8. Elementary Treatment of Some Difficulties in the Construction of Irreducible Representations of the Rotation Group in Terms of Products of the Spin-1/2 Representation.

    ERIC Educational Resources Information Center

    Daniels, J. M.

    1979-01-01

    Explains why failure to distinguish clearly between three concepts: a vector, its components, and its representatives, renders understanding of how the representations of the rotation group are constructed from products of the spin-half representation, difficult to comprehend. (Author/GA)

  9. Decoupled phase of frustrated spin-(1)/(2) antiferromagnetic chains with and without long-range order in the ground state

    NASA Astrophysics Data System (ADS)

    Kumar, Manoranjan; Soos, Z. G.

    2013-10-01

    The quantum phases of one-dimensional spin s=1/2 chains are discussed for models with two parameters, frustrating exchange g=J2>0 between second neighbors and normalized nonfrustrating power-law exchange with exponent α and distance dependence r-α. The ground state (GS) at g=0 has a long-range order (LRO) for α<2 and long-range spin fluctuations for α>2. The models conserve total spin S=SA+SB, have singlet GS for any g, α≥0 and decouple at 1/g=0 to linear Heisenberg antiferromagnets on sublattices A and B of odd- and even-numbered sites. Exact diagonalization of finite chains gives the sublattice spin , the magnetic gap Em to the lowest triplet state, and the excitation Eσ to the lowest singlet with opposite inversion symmetry to the GS. An analytical model that conserves sublattice spin has a first-order quantum transition at gc=1/4ln2 from a GS with perfect LRO to a decoupled phase with SA=SB=0 for g≥4/π2 and no correlation between spins in different sublattices. The model with α=1 has a first-order transition to a decoupled phase that closely resembles the analytical model. The bond order wave (BOW) phase and continuous quantum phase transitions of finite models with α≥2 are discussed in terms of GS degeneracy where Eσ(g)=0, excited state degeneracy where Eσ(g)=Em(g), and . The decoupled phase at large frustration has nondegenerate GS for any exponent α and excited states related to sublattice excitations.

  10. Sr2Cu(PO4)2 and Ba2Cu(PO4)2 as quasi-one-dimensional spin-1/2 Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Haque, Md. Mahfoozul; Ahsan, M. A. H.

    2016-03-01

    Using magnetic exchange couplings for antiferromagnets Sr2Cu(PO4)2 and Ba2Cu(PO4)2, estimated independently by Johannes (2006 [1]) and Salunke (2007 [2]), we present model calculations via exact diagonalization for several lattices of 24 and 16 spins by calculating experimentally accessible quantities like spin-spin correlation, the antiferromagnetic order-parameter, entropy-density, specific-heat and z-component of the magnetic susceptibility using up to 15 low-lying eigenstates. From our calculation, the ratio of critical entropy and mean-field critical entropy comes out to be ∼ 0.492(7). The slope of the specific heat curve at low temperatures is found to be 2 / 3. The peak value of z-component of the magnetic susceptibility versus temperature curve turns out to be 1/3 χ ∼ 0.05 . Our results favor the conclusion that these magnetic compounds are indeed quasi-one-dimensional antiferromagnets.

  11. Projected wave function study of Z2 spin liquids on the kagome lattice for the spin-1/2 quantum Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Becca, Federico; Iqbal, Yasir; Poilblanc, Didier

    2012-02-01

    Within the class of Gutzwiller projected fermionic wave functions, by using quantum variational Monte Carlo simulations, we investigated the energetics of all possible Z2 spin liquids that can potentially occur as ground states of the nearest-neighbor S=1/2 quantum Heisenberg model on the Kagome lattice [1]. We conclusively show that all gapped and gapless Z2 spin liquids are higher in energy compared to the U(1) gapless states in whose neighborhoods they lie. In particular, the most promising gapped Z2 spin liquid (the so-called Z2[0,π]β state), conjectured to describe the ground state [2], is always higher in energy compared to the U(1) Dirac spin liquid. We also extended the U(1) Dirac state and the uniform RVB spin liquid to include next-nearest-neighbor hopping terms, and studied its local and global stability towards various valence bond crystal patterns. We found that a non-trivial 36-site VBC is stabilized upon addition of a small ferromagnetic exchange coupling [3]. [4pt] [1] Y. Iqbal, F. Becca, and D. Poilblanc, Phys. Rev. B 84, 020407(R) (2011)[0pt] [2] Y.-M. Lu, Y. Ran, and P.A. Lee. Phys. Rev. B 83, 224413 (2011)[0pt] [3] Y. Iqbal, F. Becca, and D. Poilblanc, Phys. Rev. B 83, 100404(R) (2011)

  12. Effect of organochlorine pesticides exposure on the maize root metabolome assessed using high-resolution magic-angle spinning (1)H NMR spectroscopy.

    PubMed

    Blondel, Claire; Khelalfa, Farid; Reynaud, Stéphane; Fauvelle, Florence; Raveton, Muriel

    2016-07-01

    (1)H-HRMAS NMR-based metabolomics was used to better understand the toxic effects on maize root tips of organochlorine pesticides (OCPs), namely lindane (γHCH) and chlordecone (CLD). Maize seedlings were exposed to 2.5 μM γHCH (mimicking basic environmental contaminations) for 7 days and compared to 2.5 μM CLD and 25 μM γHCH for 7 days (mimicking hot spot contaminations). The (1)H-HRMAS NMR-based metabolomic profiles provided details of the changes in carbohydrates, amino acids, tricarboxylic acid (TCA) cycle intermediates and fatty acids with a significant separation between the control and OCP-exposed root tips. First of all, alterations in the balance between glycolysis/gluconeogenesis were observed with sucrose depletion and with dose-dependent fluctuations in glucose content. Secondly, observations indicated that OCPs might inactivate the TCA cycle, with sizeable succinate and fumarate depletion. Thirdly, disturbances in the amino acid composition (GABA, glutamine/glutamate, asparagine, isoleucine) reflected a new distribution of internal nitrogen compounds under OCP stress. Finally, OCP exposure caused an increase in fatty acid content, concomitant with a marked rise in oxidized fatty acids which could indicate failures in cell integrity and vitality. Moreover, the accumulation of asparagine and oxidized fatty acids with the induction of LOX3 transcription levels under OCP exposure highlighted an induction of protein and lipid catabolism. The overall data indicated that the effect of OCPs on primary metabolism could have broader physiological consequences on root development. Therefore, (1)H-HRMAS NMR metabolomics is a sensitive tool for understanding molecular disturbances under OCP exposure and can be used to perform a rapid assessment of phytotoxicity. PMID:27131813

  13. Spin gap in the single spin-1/2 chain cuprate Sr1.9Ca0.1CuO3

    NASA Astrophysics Data System (ADS)

    Hammerath, F.; Brüning, E. M.; Sanna, S.; Utz, Y.; Beesetty, N. S.; Saint-Martin, R.; Revcolevschi, A.; Hess, C.; Büchner, B.; Grafe, H.-J.

    2014-05-01

    We report Cu63 nuclear magnetic resonance and muon spin rotation measurements on the S =1/2 antiferromagnetic Heisenberg spin chain compound Sr1.9Ca0.1CuO3. An exponentially decreasing spin-lattice relaxation rate T1-1 indicates the opening of a spin gap. This behavior is very similar to what has been observed for the cognate zigzag spin chain compound Sr0.9Ca0.1CuO2, and it confirms that the occurrence of a spin gap upon Ca doping is independent of the interchain exchange coupling J'. Our results therefore suggest that the appearance of a spin gap in an antiferromagnetic Heisenberg spin chain is induced by a local bond disorder of the intrachain exchange coupling J. A low-temperature upturn of T1-1 evidences growing magnetic correlations. However, zero-field muon spin rotation measurements down to 1.5 K confirm the absence of magnetic order in this compound, which is most likely suppressed by the opening of the spin gap.

  14. Oblique propagation of longitudinal waves in magnetized spin-1/2 plasmas: Independent evolution of spin-up and spin-down electrons

    SciTech Connect

    Andreev, Pavel A. Kuz’menkov, L.S.

    2015-10-15

    We consider quantum plasmas of electrons and motionless ions. We describe separate evolution of spin-up and spin-down electrons. We present corresponding set of quantum hydrodynamic equations. We assume that plasmas are placed in an uniform external magnetic field. We account different occupation of spin-up and spin-down quantum states in equilibrium degenerate plasmas. This effect is included via equations of state for pressure of each species of electrons. We study oblique propagation of longitudinal waves. We show that instead of two well-known waves (the Langmuir wave and the Trivelpiece–Gould wave), plasmas reveal four wave solutions. New solutions exist due to both the separate consideration of spin-up and spin-down electrons and different occupation of spin-up and spin-down quantum states in equilibrium state of degenerate plasmas.

  15. Calculation of geometric phases in electric dipole searches with trapped spin-1/2 particles based on direct solution of the Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Steyerl, A.; Kaufman, C.; Müller, G.; Malik, S. S.; Desai, A. M.; Golub, R.

    2014-05-01

    Pendlebury etal . [Phys. Rev. A 70, 032102 (2004), 10.1103/PhysRevA.70.032102] were the first to investigate the role of geometric phases in searches for an electric dipole moment (EDM) of elementary particles based on Ramsey-separated oscillatory field magnetic resonance with trapped ultracold neutrons and comagnetometer atoms. Their work was based on the Bloch equation and later work using the density matrix corroborated the results and extended the scope to describe the dynamics of spins in general fields and in bounded geometries. We solve the Schrödinger equation directly for cylindrical trap geometry and obtain a full description of EDM-relevant spin behavior in general fields, including the short-time transients and vertical spin oscillation in the entire range of particle velocities. We apply this method to general macroscopic fields and to the field of a microscopic magnetic dipole.

  16. Phase diagram of the spin-1/2 triangular J1-J2 Heisenberg model on a three-leg cylinder

    NASA Astrophysics Data System (ADS)

    Saadatmand, S. N.; Powell, B. J.; McCulloch, I. P.

    2015-06-01

    We study the phase diagram of the frustrated Heisenberg model on the triangular lattice with nearest- and next-nearest-neighbor spin-exchange coupling, on three-leg ladders. Using the density-matrix renormalization-group method, we obtain the complete phase diagram of the model, which includes quasi-long-range 120∘ and columnar order, and a Majumdar-Ghosh phase with short-ranged correlations. All these phases are nonchiral and planar. We also identify the nature of phase transitions.

  17. Investigation of magnetic structure on (C5H12N)CuBr3 system on the basis of DFT study and orbital interaction

    NASA Astrophysics Data System (ADS)

    Lee, Changhoon; Hong, Jisook; Shim, Ji Hoon; Pohang Univ of Sci; Tech Team

    2015-03-01

    The (C5H12N)CuBr3 compound crystallizes in the monoclinic group C2/c. Magnetic susceptibility data down to 1.8 K can be well fitted for the antiferromagnetic spin-1/2 chain, giving the intrachain magnetic coupling constant Jintra ~ -17 K. At zero field, (pipH)CuBr3 shows 3D order below TN = 1.68 K. Calculated by the mean-field theory, the interchain coupling constant Jinter = - 0.91 K is obtained and the ordered magnetic moment is about 0.23 μB. However, the interchain interaction should be strong unlike experimental observation. From the analysis of local structure, the Jinter spin dimer show the possibility of good orbital overlap via Cu-O...O-Cu path in which angle for Cu-O...O-Cu is 161° indicating strong interchain interaction via Cu-O...O-Cu path. The magnetic structure of (C5H12N)CuBr3 system in terms of orbital interaction could anticipated by two-leg spin ladder which such spin ladders interact ferromagnetically to form ladder. In this study, we evaluated spin exchange interactions of (pipH)CuBr3 based on DFT calculations to find the magnetic structure of this system. As a consequence, the Jinter interaction is strong and the magnetic structure of this system, indeed, is described by two-leg spin ladder. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013R1A1A2060341)

  18. DEEP, LOW-MASS RATIO OVERCONTACT BINARY SYSTEMS. XII. CK BOOTIS WITH POSSIBLE CYCLIC MAGNETIC ACTIVITY AND ADDITIONAL COMPANION

    SciTech Connect

    Yang, Y.-G.; Qian, S.-B.; Soonthornthum, B. E-mail: qsb@ynao.ac.cn

    2012-05-15

    We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f = 71.7({+-} 4.4)%. From the O - C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67({+-} 0.20) yr may result from magnetic activity cycles, which are identified by the variability of Max. I - Max. II. Another sinusoidal variation (i.e., A = 0.0131 days({+-} 0.0009 days) and P{sub 3} = 24.16({+-} 0.64) yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt = +9.79 ({+-}0.80) Multiplication-Sign 10{sup -8} days yr{sup -1}, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J{sub spin} > (1/3)J{sub orb}.

  19. Separation system

    DOEpatents

    Rubin, Leslie S.

    1986-01-01

    A separation system for dewatering radioactive waste materials includes a disposal container, drive structure for receiving the container, and means for releasably attaching the container to the drive structure. Separation structure disposed in the container adjacent the inner surface of the side wall structure retains solids while allowing passage of liquids. Inlet port structure in the container top wall is normally closed by first valve structure that is centrifugally actuated to open the inlet port and discharge port structure at the container periphery receives liquid that passes through the separation structure and is normally closed by second valve structure that is centrifugally actuated to open the discharge ports. The container also includes coupling structure for releasable engagement with the centrifugal drive structure. Centrifugal force produced when the container is driven in rotation by the drive structure opens the valve structures, and radioactive waste material introduced into the container through the open inlet port is dewatered, and the waste is compacted. The ports are automatically closed by the valves when the container drum is not subjected to centrifugal force such that containment effectiveness is enhanced and exposure of personnel to radioactive materials is minimized.

  20. [Systemic sclerosis].

    PubMed

    Tamborrini, Giorgio; Distler, Meike; Distler, Oliver

    2008-05-01

    Systemic sclerosis (SSc) is a severe fibrotic multiorgan connective tissue disease. Vascular abnormalities such as fingertip ulcers and Raynaud's syndrome as well as involvement of organs including the lungs, heart, kidney and the gastrointestinal tract are prominent features of the disease. There are currently no disease modifying drugs available that can modify the course of the disease. In this review we will discuss medications that have been found to be effective in improving specific organ involvement due to SSc. For the treatment of gastroesophageal reflux disease (GERD), proton pump inhibitors are effective agents. In the setting of clinically significant gastrointestinal dysmotility, metoclopramide, erythromycin and octreotide may be beneficial. Small bowel bacterial overgrowth should be treated with oral antibiotics. Angiotensin converting enzyme inhibitors are the first-line agents for acute renal crisis. A variety of treatment options are available for Raynaud's phenomenon and include calcium channel blockers, iloprost (i. v.), losartan, fluoxetine and sildenafil. Fingertip ulcers can be prevented by using the endothelin receptor antagonist bosentan. The therapeutic options for treatment of pulmonary hypertension associated with SSc include bosentan, sildenafil and various prostacyclin analogs (eg, epoprostenol, treprostinil, iloprost). Sitaxentan, ambrisentan and new phosphodiesterase-5 inhibitors could be new options for therapy as well. Therapeutic options for interstitial lung fibrosis include cyclophosphamide, however, clinical effects are mild to moderate. Methotrexate has been used to treat skin fibrosis and can be beneficial when arthritis is present. PMID:18552072

  1. Incinerator system

    SciTech Connect

    Rathmell, R.K.

    1986-10-07

    An incineration system is described which consists of: combustion chamber structure having an inlet, an outlet, and burner structure in the combustion chamber, heat exchanger structure defining a chamber, divider structure between the heat exchanger chamber and the combustion chamber, an array of tubes extending through the heat exchanger chamber to the inlet of the combustion chamber at the divider structure. The heat exchanger chamber has an inlet coupled to the outlet of the combustion chamber for flow of the combustion products discharged from the combustion chamber through the heat exchanger chamber over the tubes in heat exchange relation, and an outlet for discharge of products from the heat exchanger chamber, aspirator sleeve structure secured to the divider structure between the heat exchanger chamber and the combustion chamber. Each aspirator sleeve receives the outlet end of a heat exchanger tube in slip fit relation so that the heat exchanger tubes are free to thermally expand longitudinally within the aspirator sleeves, and means for flowing vapor through the heat exchanger tubes into the combustion chamber at sufficiently high velocity to produce a reduced pressure effect in the aspirator sleeves in the heat exchanger chamber to draw a minor fraction of combustion products through the aspirator sleeves into the combustion chamber for reincineration.

  2. New Systems Produced by Systemic Change

    ERIC Educational Resources Information Center

    Battino, Wendy; Clem, Jo; Caine, Renate N.; Reigeluth, Charles M.; Chapman, Carrie; Flinders, David J.; Malopinsky, Larissa V.

    2006-01-01

    This article presents new systems produced by systemic change. First is Systemic Changes in the Chugach School District by Wendy Battino and Jo Clem. Second is Systemic Changes in Public Schools through Brain-Based Learning by Renate N. Caine. Third is A Vision of an Information-Age Educational System by Charles M. Reigeluth. Fourth is Systemic…

  3. System safety education focused on system management

    NASA Technical Reports Server (NTRS)

    Grose, V. L.

    1971-01-01

    System safety is defined and characteristics of the system are outlined. Some of the principle characteristics include role of humans in hazard analysis, clear language for input and output, system interdependence, self containment, and parallel analysis of elements.

  4. Distinguishing Systemic from Systematic.

    ERIC Educational Resources Information Center

    Carr, Alison A.

    1996-01-01

    Describes the difference between systemic and systematic as they relate to school reform and instructional design. Highlights include a history of systems theory; systems engineering; instructional systems design; systemic versus reductionist thinking; social systems; and systemic change in education, including power relationships. (LRW)

  5. Emergent low temperature phases in strongly correlated multi-orbital and cold atom systems

    NASA Astrophysics Data System (ADS)

    Puetter, Christoph Minol

    This thesis considers various strongly correlated quantum phases in solid state and cold atom spin systems. In the first part we focus on phases emerging in multi-orbital materials. We study even-parity spin-triplet superconductivity originating from Hund's coupling between t2g orbitals and investigate the effect of spin-orbit interaction on spin-triplet and spin-singlet pairing. Various aspects of the pairing state are discussed against the backdrop of the spin-triplet superconductor Sr2RuO 4. Motivated by the remarkable phenomena observed in the bilayer compound Sr3Ru2O7, which point to the formation of an electronic nematic phase in the presence of critical fluctuations, we investigate how such a broken symmetry state emerges from electronic interactions. Since the broken x-y symmetry is revealed experimentally by applying a small in-plane magnetic field component, we examine nematic phases in a bilayer system and the role of the in-plane magnetic field using a phenomenological approach. In addition, we propose a microscopic mechanism for nematic phase formation specific to Sr3Ru2O7. The model is based on a realistic multi-orbital band structure and local and nearest neighbour interactions. Considering all t2g-orbital derived bands on an equal footing, we find a nematic quantum critical point and a nearby meta-nematic transition in the phase diagram. This finding harbours important implications for the phenomena observed in Sr3Ru2O7. The second part is devoted to the study of the anisotropic bilinear biquadratic spin-1 Heisenberg model, where the existence of an unusual direct phase transition between a spin-nematic phase and a dimerized valence bond solid phase in the quasi-1D limit was conjectured based on Quantum Monte Carlo simulations. We establish the quasi-1D phase diagram using a large-N Schwinger boson approach and show that the phase transition is largely conventional except possibly at two particular points. We further discuss how to realize and to

  6. System design description cone penetrometer system

    SciTech Connect

    Seda, R.Y., Westinghouse Hanford

    1996-08-12

    The system design description documents in detail the design of the cone penetrometer system. The systems includes the cone penetrometer physical package, raman spectroscopy package and moisture sensor package. Information pertinent to the system design, development, fabrication and testing is provided.

  7. Systems view of power systems autonomy

    SciTech Connect

    Anderson, J.L.

    1984-08-01

    A space station will involve the formation and sustained operation of an assembly of humans and machines in space for a period of 10-20 years. Technology and mission studies of a permanently manned, evolutionary space station have identified the need for automated and eventually some degree of autonomous systems operation. A space station power system will have a high degree of interaction with other onboard systems which will act as power loads. By examining the evolution of an operational power system from a systems viewpoint through increasing degrees of automation the system and technology requirements are identified for an evolutionary system.

  8. Networked control of microgrid system of systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Magdi S.; Rahman, Mohamed Saif Ur; AL-Sunni, Fouad M.

    2016-08-01

    The microgrid has made its mark in distributed generation and has attracted widespread research. However, microgrid is a complex system which needs to be viewed from an intelligent system of systems perspective. In this paper, a network control system of systems is designed for the islanded microgrid system consisting of three distributed generation units as three subsystems supplying a load. The controller stabilises the microgrid system in the presence of communication infractions such as packet dropouts and delays. Simulation results are included to elucidate the effectiveness of the proposed control strategy.

  9. Systems design of long-life systems

    NASA Technical Reports Server (NTRS)

    Miles, R. F., Jr.

    1974-01-01

    A long-life system is defined as a system which cannot be life-tested in its operational environment. Another restriction is that preventive maintenance and repair shall be either impossible or economically disadvantageous. Examples of such systems include planetary spacecraft, communication satellites, undersea telephone cables, and nuclear power plants. The questions discussed are related to the implementation of system functions, approaches to determine the required level of system reliability, and aspects of tradeoffs between requirements and reliability.

  10. Female Reproductive System

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Female Reproductive System KidsHealth > For Teens > Female Reproductive System Print A ... and female reproductive systems. continue What Is the Female Reproductive System? Most species have two sexes: male and female. ...

  11. Multiple System Atrophy

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Multiple System Atrophy Information Page Condensed from Multiple System Atrophy ... Trials Organizations Publicaciones en Español What is Multiple System Atrophy? Multiple system atrophy (MSA) is a progressive ...

  12. System of systems modeling and analysis.

    SciTech Connect

    Campbell, James E.; Anderson, Dennis James; Longsine, Dennis E.; Shirah, Donald N.

    2005-01-01

    This report documents the results of an LDRD program entitled 'System of Systems Modeling and Analysis' that was conducted during FY 2003 and FY 2004. Systems that themselves consist of multiple systems (referred to here as System of Systems or SoS) introduce a level of complexity to systems performance analysis and optimization that is not readily addressable by existing capabilities. The objective of the 'System of Systems Modeling and Analysis' project was to develop an integrated modeling and simulation environment that addresses the complex SoS modeling and analysis needs. The approach to meeting this objective involved two key efforts. First, a static analysis approach, called state modeling, has been developed that is useful for analyzing the average performance of systems over defined use conditions. The state modeling capability supports analysis and optimization of multiple systems and multiple performance measures or measures of effectiveness. The second effort involves time simulation which represents every system in the simulation using an encapsulated state model (State Model Object or SMO). The time simulation can analyze any number of systems including cross-platform dependencies and a detailed treatment of the logistics required to support the systems in a defined mission.

  13. System Software Framework for System of Systems Avionics

    NASA Technical Reports Server (NTRS)

    Ferguson, Roscoe C.; Peterson, Benjamin L; Thompson, Hiram C.

    2005-01-01

    Project Constellation implements NASA's vision for space exploration to expand human presence in our solar system. The engineering focus of this project is developing a system of systems architecture. This architecture allows for the incremental development of the overall program. Systems can be built and connected in a "Lego style" manner to generate configurations supporting various mission objectives. The development of the avionics or control systems of such a massive project will result in concurrent engineering. Also, each system will have software and the need to communicate with other (possibly heterogeneous) systems. Fortunately, this design problem has already been solved during the creation and evolution of systems such as the Internet and the Department of Defense's successful effort to standardize distributed simulation (now IEEE 1516). The solution relies on the use of a standard layered software framework and a communication protocol. A standard framework and communication protocol is suggested for the development and maintenance of Project Constellation systems. The ARINC 653 standard is a great start for such a common software framework. This paper proposes a common system software framework that uses the Real Time Publish/Subscribe protocol for framework-to-framework communication to extend ARINC 653. It is highly recommended that such a framework be established before development. This is important for the success of concurrent engineering. The framework provides an infrastructure for general system services and is designed for flexibility to support a spiral development effort.

  14. Phonon assisted IR spectroscopy of quantum antiferromagnets

    SciTech Connect

    Lorenzana, J.; Eder, R.; Sawatzky, G.A.

    1996-12-31

    The authors review resent theoretical results for multimagnon-phonon assisted infrared absorption in antiferromagnetic Heisenberg systems. They show spin wave theory line shapes for 2D spin 1/2 systems (like the parent insulating high-Tc cuprates) 1D spin 1/2 systems and 2D spin 1 systems (like the nickelates) and exact diagonalization results in two-dimensional spin 1/2 systems. The theoretical line shapes are compared with experiments. In the case of the cuprates they explain mid-infrared peaks observed in the insulator. In the case of the nickelates a predicted line shape is also shown to agree with the experiments. They discuss the possibility to observe this excitations in other experiments.

  15. Intelligent systems technology infrastructure for integrated systems

    NASA Technical Reports Server (NTRS)

    Lum, Henry, Jr.

    1991-01-01

    Significant advances have occurred during the last decade in intelligent systems technologies (a.k.a. knowledge-based systems, KBS) including research, feasibility demonstrations, and technology implementations in operational environments. Evaluation and simulation data obtained to date in real-time operational environments suggest that cost-effective utilization of intelligent systems technologies can be realized for Automated Rendezvous and Capture applications. The successful implementation of these technologies involve a complex system infrastructure integrating the requirements of transportation, vehicle checkout and health management, and communication systems without compromise to systems reliability and performance. The resources that must be invoked to accomplish these tasks include remote ground operations and control, built-in system fault management and control, and intelligent robotics. To ensure long-term evolution and integration of new validated technologies over the lifetime of the vehicle, system interfaces must also be addressed and integrated into the overall system interface requirements. An approach for defining and evaluating the system infrastructures including the testbed currently being used to support the on-going evaluations for the evolutionary Space Station Freedom Data Management System is presented and discussed. Intelligent system technologies discussed include artificial intelligence (real-time replanning and scheduling), high performance computational elements (parallel processors, photonic processors, and neural networks), real-time fault management and control, and system software development tools for rapid prototyping capabilities.

  16. Systems engineering and analysis

    SciTech Connect

    Blanchard, B.S.; Fabrycky, W.J.

    1981-01-01

    An introduction to systems is provided and tools for systems analysis are considered, taking into account system definitions and concepts, approaches for bringing systems into being, models in systems analysis, economic analysis techniques, mathematical modeling and optimization, probability and statistics, queuing theory and analysis, and control concepts and techniques. The system design process is discussed along with the design for operational feasibility, systems engineering management, and system design case studies. Attention is given to conceptual design, preliminary system design, detail design and development, system test and evaluation, design for reliability, design for maintainability, design for supportability, design for economic feasibility, communication system design, finite population system design, energy storage system design, and procurement-inventory system design.

  17. [X-33 Systems

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Lockheed Martin Skunk Works has compiled an Annual Performance Report of the X-33/RLV Program. This report consists of individual reports from all industry team members, as well as NASA team centers. This portion of the report is comprised of a status report of Allied-Signal Aerospace's contribution to the program. The following is a summary of the work reviewed under their portion of the agreement: (1) Communication Systems; (2) Environmental Control Systems- Active Thermal Control System (ATCS), Purge and Vent System, Hydrogen Detection System (HDS), Avionics Bay Inerting System (ABIS), and Flush Air Data System (FADS); (2) Landing Systems; (3) Power Management and Generation Systems; (4) Flight Control Actuation System (FCAS)- Electric Power Control & Distribution System (EPCDS), and Battery Power System (BPS); and (5) Vehicle Management Systems (VMS)- VMS Hardware, VMS Software Development Activities, and System Integration Laboratory (SIL).

  18. Freedom System Text and Graphics System (TAGS)

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The Text and Graphics System (TAGS) is a high-resolution facsimile system that scans text or graphics material and converts the analog SCAN data into serial digital data. This video shows the TAGS in operation.

  19. Language as a System of Systems

    ERIC Educational Resources Information Center

    Mulder, J. W. F.; Hervey, S. G. J.

    1975-01-01

    Based on Mulder's previous classification of all semiotic systems designed to describe the system of discrete features in human languages, this article explores a further subclassification of the genus language into species. (CLK)

  20. Intelligent tutoring systems for systems engineering methodologies

    NASA Technical Reports Server (NTRS)

    Meyer, Richard J.; Toland, Joel; Decker, Louis

    1991-01-01

    The general goal is to provide the technology required to build systems that can provide intelligent tutoring in IDEF (Integrated Computer Aided Manufacturing Definition Method) modeling. The following subject areas are covered: intelligent tutoring systems for systems analysis methodologies; IDEF tutor architecture and components; developing cognitive skills for IDEF modeling; experimental software; and PC based prototype.

  1. System Design of the SWRL Financial System.

    ERIC Educational Resources Information Center

    Ikeda, Masumi

    To produce various management and accounting reports in order to maintain control of SWRL (Southwest Regional Laboratory) operational and financial activities, a computer-based SWRL financial system was developed. The system design is outlined, and various types of system inputs described. The kinds of management and accounting reports generated…

  2. Optical system defect propagation in ABCD systems.

    PubMed

    McKinley, W G; Yura, H T; Hanson, S G

    1988-05-01

    We describe how optical system defects (tilt/jitter, decenter, and despace) propagate through an arbitrary paraxial optical system that can be described by an ABCD ray transfer matrix. A pedagogical example is given that demonstrates the effect of alignment errors on a typical optical system. PMID:19745889

  3. General Systems Theory and Instructional Systems Design.

    ERIC Educational Resources Information Center

    Salisbury, David F.

    1990-01-01

    Describes basic concepts in the field of general systems theory (GST) and identifies commonalities that exist between GST and instructional systems design (ISD). Models and diagrams that depict system elements in ISD are presented, and two matrices that show how GST has been used in ISD literature are included. (11 references) (LRW)

  4. DDL system: Design systhesis of digital systems

    NASA Technical Reports Server (NTRS)

    Shiva, S. G.

    1983-01-01

    Digital Systems Design Language was integrated into the CADAT system environment of NASA-MSFC. The major technical aspects of this integration are summarized. Automatic hardware synthesis is now possible starting with a high level description of the system to be synthesized. The DDL system provides a high level design verification capability, thereby minimizing design changes in the later stages of the design cycle. An overview of the DDL system covering the translation, simulation and synthesis capabilities is provided. Two companion documents (the user's and programmer's manuals) are to be consulted for detailed discussions.

  5. Lighting system with thermal management system

    SciTech Connect

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Seeley, Charles Erklin; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Utturkar, Yogen Vishwas; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2015-08-25

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  6. Lighting system with thermal management system

    DOEpatents

    Arik, Mehmet; Weaver, Stanton; Stecher, Thomas; Seeley, Charles; Kuenzler, Glenn; Wolfe, Jr., Charles; Utturkar, Yogen; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2013-05-07

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  7. Lighting system with thermal management system

    DOEpatents

    Arik, Mehmet; Weaver, Stanton Earl; Stecher, Thomas Elliot; Seeley, Charles Erklin; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Utturkar, Yogen Vishwas; Sharma, Rajdeep; Prabhakaran, Satish; Icoz, Tunc

    2015-02-24

    Lighting systems having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system is configured to provide an air flow, such as a unidirectional air flow, through the housing structure in order to cool the light source. The driver electronics are configured to provide power to each of the light source and the thermal management system.

  8. Microwave landing system autoland system analysis

    NASA Technical Reports Server (NTRS)

    Feather, J. B.; Craven, B. K.

    1991-01-01

    The objective was to investigate the ability of present day aircraft equipped with automatic flight control systems to fly advanced Microwave Landing Systems (MLS) approaches. The tactical approach used to achieve this objective included reviewing the design and autoland operation of the MD-80 aircraft, simulating the MLS approaches using a batch computer program, and assessing the performance of the autoland system from computer generated data. The results showed changes were required to present Instrument Landing System (ILS) procedures to accommodate the new MLS curved paths. It was also shown that in some cases, changes to the digital flight guidance systems would be required so that an autoland could be performed.

  9. Intelligent test integration system

    NASA Technical Reports Server (NTRS)

    Sztipanovits, J.; Padalkar, S.; Rodriguez-Moscoso, J.; Kawamura, K.; Purves, B.; Williams, R.; Biglari, H.

    1988-01-01

    A new test technology is described which was developed for space system integration. The ultimate purpose of the system is to support the automatic generation of test systems in real time, distributed computing environments. The Intelligent Test Integration System (ITIS) is a knowledge based layer above the traditional test system components which can generate complex test configurations from the specification of test scenarios.

  10. Collaborative Systems Testing

    ERIC Educational Resources Information Center

    Pocatilu, Paul; Ciurea, Cristian

    2009-01-01

    Collaborative systems are widely used today in various activity fields. Their complexity is high and the development involves numerous resources and costs. Testing collaborative systems has a very important role for the systems' success. In this paper we present taxonomy of collaborative systems. The collaborative systems are classified in many…

  11. Energy Systems Design

    NASA Technical Reports Server (NTRS)

    1986-01-01

    PRESTO, a COSMIC program, handles energy system specifications and predicts design efficiency of cogeneration systems. These systems allow a company to use excess energy produced to generate electricity. PRESTO is utilized by the Energy Systems Division of Thermo Electron Corporation in the custom design of cogeneration systems.

  12. Systems Intelligence Inventory

    ERIC Educational Resources Information Center

    Törmänen, Juha; Hämäläinen, Raimo P.; Saarinen, Esa

    2016-01-01

    Purpose: Systems intelligence (SI) (Saarinen and Hämäläinen, 2004) is a construct defined as a person's ability to act intelligently within complex systems involving interaction and feedback. SI relates to our ability to act in systems and reason about systems to adaptively carry out productive actions within and with respect to systems such as…

  13. The LSST: A System of Systems

    NASA Astrophysics Data System (ADS)

    Claver, Chuck F.; Debois-Felsmann, G. P.; Delgado, F.; Hascall, P.; Marshall, S.; Nordby, M.; Schumacher, G.; Sebag, J.; LSST Collaboration

    2011-01-01

    The Large Synoptic Survey Telescope (LSST) is a complete observing system that acquires and archives images, processes and analyzes them, and publishes reduced images and catalogs of sources and objects. The LSST will operate over a ten year period producing a survey of 20,000 square degrees over the entire [Southern] sky in 6 filters (ugrizy) with each field having been visited several hundred times enabling a wide spectrum of science from fast transients to exploration of dark matter and dark energy. The LSST itself is a complex system of systems consisting of the 8.4m 3-mirror telescope, a 3.2 billion pixel camera, and a peta-scale data management system. The LSST project uses a Model Based Systems Engineering (MBSE) methodology to ensure an integrated approach to system design and rigorous definition of system interfaces and specifications. The MBSE methodology is applied through modeling of the LSST's systems with the System Modeling Language (SysML). The SysML modeling recursively establishes the threefold relationship between requirements, logical & physical functional decomposition and definition, and system and component behavior at successively deeper level of abstraction and detail. The LSST modeling includes the analysis and documenting the flow of command and control information and data between the suite of systems in the LSST observatory that are needed to carry out the activities of the survey. The MBSE approach is applied throughout all stages of the project from design, to validation and verification, though to commissioning.

  14. Levonorgestrel Intrauterine System

    MedlinePlus

    ... new system inserted at any time during your menstrual cycle. If you have chosen to use a different ... of your intrauterine system and you have regular menstrual cycles, you should have the system removed during the ...

  15. Manned systems technology discipline

    NASA Technical Reports Server (NTRS)

    Bretoi, Remus

    1990-01-01

    Viewgraphs on manned systems technology discipline for Space Station Freedom are presented. Topics covered include: crew-systems interfaces and interactions; crew training; on-board systems maintenance and support; habitability and environment; and computational human factors.

  16. Autonomic Nervous System Disorders

    MedlinePlus

    Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart ... breathing and swallowing Erectile dysfunction in men Autonomic nervous system disorders can occur alone or as the result ...

  17. Autonomic Nervous System Disorders

    MedlinePlus

    Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating ... with breathing and swallowing Erectile dysfunction in men Autonomic nervous system disorders can occur alone or as ...

  18. Immune System Involvement

    MedlinePlus

    ... Tips" to find out more! Email * Zipcode The Immune System and Psoriatic Disease What is an autoimmune disease? ... swollen and painful joints and tendons. Treating the immune system The immune system is not only the key ...

  19. Female Reproductive System

    MedlinePlus

    ... Story" 5 Things to Know About Zika & Pregnancy Female Reproductive System KidsHealth > For Parents > Female Reproductive System Print A ... the egg or sperm. continue Components of the Female Reproductive System Unlike the male, the human female has a ...

  20. Wind energy systems

    NASA Technical Reports Server (NTRS)

    Stewart, H. J.

    1978-01-01

    A discussion on wind energy systems involved with the DOE wind energy program is presented. Some of the problems associated with wind energy systems are discussed. The cost, efficiency, and structural design of wind energy systems are analyzed.