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

  1. 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.

  2. 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.

  3. 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.

  4. Low Temperature Analysis of Correlation Functions of the Blume-Emery-Griffiths Model at the Antiquadrupolar-Disordered Interface

    NASA Astrophysics Data System (ADS)

    Lima, Paulo C.

    2016-11-01

    We show that at low temperatures the d dimensional Blume-Emery-Griffiths model in the antiquadrupolar-disordered interface has all its infinite volume correlation functions < prod _{iin A}σ _i^{n_i}rangle _{τ }, where Asubset Z^d is finite and sum _{iin A}n_i is odd, equal zero, regardless of the boundary condition τ . In particular, the magnetization < σ _irangle _{τ } is zero, for all τ . We also show that the infinite volume mean magnetization lim _{Λ → ∞}Big < 1/|Λ |sum _{iin Λ }σ _iBig rangle _{Λ ,τ } is zero, for all τ.

  5. 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.

  6. Tri-critical behavior of the Blume-Emery-Griffiths model on a Kagomé lattice: Effective-field theory and Rigorous bounds

    NASA Astrophysics Data System (ADS)

    Santos, Jander P.; Sá Barreto, F. C.

    2016-01-01

    Spin correlation identities for the Blume-Emery-Griffiths model on Kagomé lattice are derived and combined with rigorous correlation inequalities lead to upper bounds on the critical temperature. From the spin correlation identities the mean field approximation and the effective field approximation results for the magnetization, the critical frontiers and the tricritical points are obtained. The rigorous upper bounds on the critical temperature improve over those effective-field type theories results.

  7. Static quadrupolar susceptibility for a Blume-Emery-Griffiths model based on the mean-field approximation

    NASA Astrophysics Data System (ADS)

    Pawlak, A.; Gülpınar, G.; Erdem, R.; Ağartıoğlu, M.

    2015-12-01

    The expressions for the dipolar and quadrupolar susceptibilities are obtained within the mean-field approximation in the Blume-Emery-Griffiths model. Temperature as well as crystal field dependences of the susceptibilities are investigated for two different phase diagram topologies which take place for K/J=3 and K/J=5.0.Their behavior near the second and first order transition points as well as multi-critical points such as tricritical, triple and critical endpoint is presented. It is found that in addition to the jumps connected with the phase transitions there are broad peaks in the quadrupolar susceptibility. It is indicated that these broad peaks lie on a prolongation of the first-order line from a triple point to a critical point ending the line of first-order transitions between two distinct paramagnetic phases. It is argued that the broad peaks are a reminiscence of very strong quadrupolar fluctuations at the critical point. The results reveal the fact that near ferromagnetic-paramagnetic phase transitions the quadrupolar susceptibility generally shows a jump whereas near the phase transition between two distinct paramagnetic phases it is an edge-like.

  8. Comparison of the exact thermodynamics of the AF Blume-Emery-Grifiths and of the spin-1 ferromagnetic Ising models

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We study in detail the thermodynamics of the anti-ferromagnetic Blume-Emery-Griffiths (AF BEG) model in the presence of a longitudinal magnetic field. Its thermodynamics is derived from the exact Helmholtz free energy (HFE) of the model, valid for T > 0. Numerical simulations of this model on a periodic space chain with 10 sites (N=10) yield the energy spectra of the model at K/J = 2 for D/J = 1 and D/J = 2, thus helping us compare, for a broad range of temperature, how some (per site) thermodynamic functions with the same value of K/J but distinct values of D/J behave, namely: the z-component of the magnetization, the specific heat and the entropy. These thermodynamic functions of the AF BEG model at K/|J| = 2 are compared to those of the spin-1 ferromagnetic Ising model with D/|J| > 1.5, for which the T=0 phase diagrams of both models are identical. This comparison is done in a large interval of temperature.

  9. 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.

  10. Inequivalence of Ensembles in a System with Long-Range Interactions

    SciTech Connect

    Barre, Julien; Mukamel, David; Ruffo, Stefano

    2001-07-16

    We study the global phase diagram of the infinite-range Blume-Emery-Griffiths model both in the canonical and in the microcanonical ensembles. The canonical phase diagram shows first-order and continuous transition lines separated by a tricritical point. We find that below the tricritical point, when the canonical transition is first order, the phase diagrams of the two ensembles disagree. In this region the microcanonical ensemble exhibits energy ranges with negative specific heat and temperature jumps at transition energies. These results can be extended to weakly decaying nonintegrable interactions.

  11. Violation of local realism by a system with N spin-(1/2) particles

    SciTech Connect

    Wu, Xiao-Hua; Zong, Hong-Shi

    2003-09-01

    Recently, it was found that Mermin's inequalities may not always be optimal for the refutation of a local realistic description [Phys. Rev. Lett. 88, 210402 (2002)]. To complete this work, we derive an inequality for the Greenberger-Horne-Zeilinger-type pure state for a system with N spin-(1/2) particles and the violation of the inequality can be shown for all the non product pure states. Mermin's inequality for a system of N spin-(1/2) particles and Gisin's theorem for a system of two spin-(1/2) particles are both included in our inequality.

  12. 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.

  13. 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.

  14. Green's function study of a mixed spin-1 and spin-3/2 Heisenberg ferrimagnetic system

    NASA Astrophysics Data System (ADS)

    Mert, Gülistan

    2012-09-01

    The magnetic properties of a mixed spin-1 and spin-3/2 Heisenberg ferrimagnetic system on a square lattice are investigated by using the double-time temperature-dependent Green's function technique. In order to decouple the higher order Green's functions, Anderson and Callen's decoupling and random phase approximations have been used. The nearest- and next-nearest-neighbor interactions and the single-ion anisotropies are considered and their effects on compensation and critical temperature are studied.

  15. Quantum simulation of Abelian Wu–Yang monopoles in spin-1/2 systems

    NASA Astrophysics Data System (ADS)

    Zhang, Ze-Lin; Chen, Ming-Feng; Wu, Huai-Zhi; Yang, Zhen-Biao

    2017-04-01

    With the help of the Berry curvature and the first Chern number (C 1), we both analytically and numerically investigate and thus simulate artificial magnetic monopoles formed in parameter space of the Hamiltonian of a driven superconducting qubit. The topological structure of a spin-1/2 system (qubit) can be captured by the distribution of Berry curvature, which describes the geometry of eigenstates of the Hamiltonian. Degenerate points in parameter space act as sources (C 1  =  1, represented by quantum ground state manifold) or sinks (C 1  =  ‑1, represented by quantum excited state manifold) of the magnetic field. We note that the strength of the magnetic field (described by Berry curvature) has an apparent impact on the quantum states during the process of topological transition. It exhibits an unusual property that the transition of the quantum states is asymmetric when the degenerate point passes from outside to inside and again outside the manifold spanned by system parameters. Our results also pave the way to explore intriguing properties of Abelian Wu–Yang monopoles in other spin-1/2 systems.

  16. 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.

  17. Ecological optimization of an irreversible quantum Carnot heat engine with spin-1/2 systems

    NASA Astrophysics Data System (ADS)

    Liu, Xiaowei; Chen, Lingen; Wu, Feng; Sun, Fengrui

    2010-02-01

    A model of a quantum heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting spin-1/2 systems is established in this paper. The quantum heat engine cycle is composed of two isothermal processes and two irreversible adiabatic processes and is referred to as a spin quantum Carnot heat engine. Based on the quantum master equation and the semi-group approach, equations of some important performance parameters, such as power output, efficiency, entropy generation rate and ecological function (a criterion representing the optimal compromise between exergy output rate and exergy loss rate), for the irreversible spin quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. The effects of internal irreversibility and heat leakage on ecological performance are discussed in detail.

  18. Multifrequency resonances in multiple-pulse NMR on a spin-1/2 system

    SciTech Connect

    Furman, G.B.; Goren, S.D.; Meerovich, V.M.; Sokolovsky, V.L.; Kibrik, G.E.; Polyakov, A.Yu.

    2003-12-01

    We have observed multifrequency resonances in a system with a spin 1/2 located in dc magnetic field and irradiated simultaneously by a multiple-pulse radio frequency sequence and a low-frequency field swept in the range 0-80 kHz. The used excitation scheme allowed us to measure the effective field of the radio frequency sequence. A peculiarity of this scheme is that the intensity of the resonance lines decreases slowly with the mode number. The theoretical description of the effect is presented using both the rotating frame approximation and the Floquet theory. Both approaches give identical results at the calculation of the resonance frequencies, transition probabilities, and shifts of resonance frequency. The calculated magnetization vs the frequency of the low-frequency field agrees well with the obtained experimental data. The multifrequency spectra give a way for studying slow atomic motion in solids.

  19. Screened spin-1 and -1/2 Kondo effect in a triangular quantum dot system with interdot Coulomb repulsion

    NASA Astrophysics Data System (ADS)

    Xiong, Yong-Chen; Wang, Wei-Zhong; Luo, Shi-Jun; Yang, Jun-Tao; Huang, Hai-Ming

    2017-03-01

    By means of the numerical renormalization group (NRG) technique, we study the low temperature transport property and the phase transition for a triangular triple quantum dot system, including two centered dots (dot 1 and 2) and one side dot (dot 3). We focus on the effect of interdot repulsion V between two centered dots in a wide range of the interdot hopping tij (i,j = 1,2,3). When the hoppings between the centered dot and the side dot are symmetric, i.e., t13 = t23, and that between two centered dots t12 is small, two centered dots form a spin triplet when V is absent, and a totally screened spin-1 Kondo effect is observed. In this case, one has a spin 1 that is partially screened by the leads as in the usual spin-1 Kondo model, and the remaining spin 1/2 degree of freedom forms a singlet with the side dot. As V is large enough, one of the centered dots is singly occupied, while the other one is empty. The spin-1/2 Kondo effect is found when t13 is small. For large t12, two centered dots form a spin singlet when V = 0, leading to zero conductance. As V is large enough, the spin-1/2 Kondo effect is recovered in the case of small t13. For asymmetric t13≠t23 and small t12, a crossover is found as V increases in comparison with a first order quantum phase transition for the symmetric case. In the regime of large V, the spin-1/2 Kondo effect could also be found when both t13 and t23 are small. We demonstrate the present model is similar to the side-coupled double dot system in some appropriate regimes, and it appears as a possible realization of side-controllable molecular electronics and spintronics devices.

  20. Chaotic behavior of a spin-glass model on a Cayley tree

    NASA Astrophysics Data System (ADS)

    da Costa, F. A.; de Araújo, J. M.; Salinas, S. R.

    2015-06-01

    We investigate the phase diagram of a spin-1 Ising spin-glass model on a Cayley tree. According to early work of Thompson and collaborators, this problem can be formulated in terms of a set of nonlinear discrete recursion relations along the branches of the tree. Physically relevant solutions correspond to the attractors of these mapping equations. In the limit of infinite coordination of the tree, and for some choices of the model parameters, we make contact with findings for the phase diagram of more recently investigated versions of the Blume-Emery-Griffiths spin-glass model. In addition to the anticipated phases, we numerically characterize the existence of modulated and chaotic structures.

  1. Spin-1 quantum walks

    NASA Astrophysics Data System (ADS)

    Morita, Daichi; Kubo, Toshihiro; Tokura, Yasuhiro; Yamashita, Makoto

    2016-06-01

    We study the quantum walks of two interacting spin-1 bosons. We derive an exact solution for the time-dependent wave function, which describes the two-particle dynamics governed by the one-dimensional spin-1 Bose-Hubbard model. We show that propagation dynamics in real space and mixing dynamics in spin space are correlated via the spin-dependent interaction in this system. The spin-mixing dynamics has two characteristic frequencies in the limit of large spin-dependent interactions. One of the characteristic frequencies is determined by the energy difference between two bound states, and the other frequency relates to the cotunneling process of a pair of spin-1 bosons. Furthermore, we numerically analyze the growth of the spin correlations in quantum walks. We find that long-range spin correlations emerge showing a clear dependence on the sign of the spin-dependent interaction and the initial state.

  2. 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.

  3. Transverse magnetization transfer under planar mixing conditions in spin systems consisting of three coupled spins 1/2.

    PubMed

    Luy, Burkhard; Glaser, Steffen J

    2003-10-01

    Polarization transfer under planar mixing conditions is a widely used tool in modern NMR-experiments. In the case of two coupled spins 1/2 or a chain of three or more spins 1/2 with only nearest neighbor couplings, it is only possible to transfer a single magnetization component (longitudinal magnetization in the principle axis system of the planar coupling tensors). However, if all couplings in a three-spin system are non-zero, it turns out that all magnetization components can be efficiently transferred even under strictly planar mixing conditions. In this article a detailed theoretical analysis is presented based on analytical transverse coherence transfer functions and on the underlying commutator algebra. In addition, transverse magnetization transfer is demonstrated experimentally. The results show that in highly coupled spin systems, as for example in the case of partially aligned samples with many residual dipolar couplings, special care has to be taken to avoid phase distortions if planar mixing steps are used.

  4. Low-temperature ordered phases of the spin-1/2 XXZ chain system Cs2CoCl4

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    In this study the magnetic order of the spin-1/2 XXZ chain system Cs2CoCl4 in a temperature range from 50 mK to 0.5 K and in applied magnetic fields up to 3.5 T is investigated by high-resolution measurements of the thermal expansion and the specific heat. Applying magnetic fields along a or c suppresses TN completely at about 2.1 T. In addition, we find an adjacent intermediate phase before the magnetization saturates close to 2.5 T. For magnetic fields applied along b , a surprisingly rich phase diagram arises. Two additional transitions are observed at critical fields μ0HS F 1≃0.25 T and μ0HS F 2≃0.7 T , which we propose to arise from a two-stage spin-flop transition.

  5. Magnetic properties of a mixed spin-1 and spin-2 Heisenberg ferrimagnetic system: Green’s function study

    NASA Astrophysics Data System (ADS)

    Mert, G.; Mert, H. Ş.

    2012-12-01

    The magnetic behaviors of a mixed spin-1 and spin-2 Heisenberg ferrimagnetic system on a square lattice are studied by using the double-time temperature-dependent Green’s function technique. In order to decouple the higher order Green’s functions, Anderson and Callen’s decoupling and random phase approximations have been used. The system is described in the presence of an external magnetic field. We illustrate the influences of the nearest- and next-nearest-neighbor interactions and the single-ion anisotropies with an external magnetic field on compensation and critical temperatures. We found that the system that includes only the nearest-neighbor interaction and the single-ion anisotropies does not have a compensation temperature. When the next-nearest-neighbor interactions exceed a certain minimum value, a compensation temperature begins to appear. For some negative values of single-ion anisotropies, there exist first-order phase transitions. The system has first-order phase transition properties when it is under the influence of an external magnetic field.

  6. Spin-(1)/(2) XXZ Chain System Cs2CoCl4 in a Transverse Magnetic Field

    NASA Astrophysics Data System (ADS)

    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 Cs2CoCl4 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 Jz/J⊥≈0.12, substantially smaller than previously believed. A spin-flop Ising quantum phase transition occurs at a critical field of μ0Hbcr≈2T before around 3.5 T the description in terms of an effective spin-(1)/(2) chain becomes inapplicable.

  7. 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.

  8. Magnetic properties of the mixed spin-1 and spin-3/2 Ising system on a bilayer square lattice: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    The magnetic behavior of the mixed spin-1 and spin-3/2 Ising system on a bilayer square lattice is studied using the Monte Carlo simulations for both ferromagnetic/ferromagnetic and antiferromagnetic/ferromagnetic interactions in the presence and absence of external magnetic, crystal field and for different values of exchange interactions. The thermal variations of the magnetizations are given. The magnetic hysteresis cycles are established. The magnetic coercive field and the remanent magnetization are deduced. The coercive magnetic field, remanent magnetization and the transition temperature were not affect by the size effect.

  9. 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′.

  10. Critical behavior of AC antiferromagnetic and ferromagnetic susceptibilities of a spin-1/2 > metamagnetic Ising system

    NASA Astrophysics Data System (ADS)

    Gulpinar, Gul; Vatansever, Erol

    2012-03-01

    In this study, the temperature variations of the equilibrium and the non-equilibrium antiferromagnetic and ferromagnetic susceptibilities of a metamagnetic system are examined near the critical point. The kinetic equations describing the time dependencies of the total and staggered magnetizations are derived by utilizing linear response theory. In order to obtain dynamic magnetic relaxation behavior of the system, the stationary solutions of the kinetic equations in existence of sinusoidal staggered and physical external magnetic fields are performed. In addition, the static and dynamical mean field critical exponents are calculated in order to formulate the critical behavior of antiferromagnetic and ferromagnetic magnetic response of a metamagnetic system. Finally, a comparison of the findings of this study with previous theoretical and experimental studies is represented and it is shown that a good agreement is found with our results.

  11. Relaxation Effects in a System of a Spin-1solar2 Nucleus Coupled to a Quadrupolar Spin Subjected to RF Irradiation: Evaluation of Broadband Decoupling Schemes

    NASA Astrophysics Data System (ADS)

    Smith, Scott A.; Murali, Nagarajan

    1999-01-01

    We have investigated the suitability and performance of various decoupling methods on systems in which an observed spin-1/2 nucleusI(13C or15N) is scalar-coupled to a quadrupolar spinS(2H). Simulations and experiments have been conducted by varying the strength of the irradiating radiofrequency (RF) field, RF offset, relaxation times, and decoupling schemes applied in the vicinity of theS-spin resonance. TheT1relaxation of the quadrupolar spin has previously been shown to influence the efficiency of continuous wave (CW) decoupling applied on resonance in such spin systems. Similarly, the performance of broadband decoupling sequences should also be affected by relaxation. However, virtually all of the more commonly used broadband decoupling schemes have been developed without consideration of relaxation effects. As a consequence, it is not obvious how one selects a suitable sequence for decoupling quadrupolar nuclei with exotic relaxation behavior. Herein we demonstrate that, despite its simplicity, WALTZ-16 decoupling is relatively robust under a wide range of conditions. In these systems it performs as well as the more recently developed decoupling schemes for wide bandwidth applications such as GARP-1 and CHIRP-95. It is suggested that in macromolecular motional regimes, broadband deuterium decoupling can be achieved with relatively low RF amplitudes (500-700 Hz) using WALTZ-16 multiple pulse decoupling.

  12. Disorder solutions of lattice spin models

    NASA Astrophysics Data System (ADS)

    Batchelor, M. T.; van Leeuwen, J. M. J.

    1989-01-01

    It is shown that disorder solutions, which have been obtained by different methods, follow from a simple decimation method. The method is put in general form and new disorder solutions are constructed for the Blume-Emery-Griffiths model on a triangular lattice and for Potts and Ising models on square and fcc lattices.

  13. Exact Product Operator Evolution of Weakly Coupled Spin- {1}/{2} I mS n Systems during Arbitrary RF Irradiation of the I Spins

    NASA Astrophysics Data System (ADS)

    Skinner, Thomas E.; Bendall, M. Robin

    1999-12-01

    In this article, we consider the evolution of weakly coupled ImSn systems of spin-{1}/{2} nuclei during arbitrary RF irradiation of the I spins. Exact solutions are presented for the time dependence of the density operator in terms of its constituent product operator components for a complete set of initial states derived from polarization of either the I or the S spin. The solutions extend the range of applications that are accessible to the product operator formalism and its associated vector picture of nuclear spin evolution. This marriage of quantum mechanics and a literal vector description of spin dynamics during RF irradiation supports physical intuition and has led to simple pulses for selective coherence transfer, among other new applications. The evolution of initial states that are free of transverse S-spin components can be described by classical precession of the I-spin components about effective fields defined by the interaction between the coupling and RF fields. Although there is no analogue involving classical rotations for the evolution of initial states composed of Sx or Sy, a vector description is still possible, and the solutions completely characterize the nature of J-coupling modulation during RF pulses. We emphasize the Cartesian product operator basis in the present treatment, but the solutions are readily obtained in any other basis that might prove suitable in analyzing an experiment. For a system of N coupled spins, standard exact methods involving diagonalization and multiplication of the 2N × 2N matrices that represent the system require on the order of (2N)3 operations to calculate the system response to a general RF waveform at each point in the time domain. By contrast, the efficiency of the present method scales linearly with the number of spins. Since the formalism presented also accommodates the absence of either RF irradiation or the coupling, the solutions provide an efficient means of general pulse sequence simulation

  14. 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.

  15. Tricritical behaviour in diluted mixed spin-1 and spin- {1}/{2} on square lattice

    NASA Astrophysics Data System (ADS)

    Benyoussef, A.; El Kenz, A.; Kaneyoshi, T.

    1994-03-01

    An effective-field theory with correlations is developed for a diluted mixed sping- {1}/{2} and spin-1 Ising ferromagnetic system with a crystal-field interaction D in a square lattice ( Z = 4). The phase diagrams in temperature-concentration of magnetic atoms ( p) and in temperature-crystal field interaction planes exhibit a variety of interesting phenomena such as second order phase transitions, tricritical points and first order phase transitions. The reentrant phenomena are also observed.

  16. Generic fixed point model for pseudo-spin-1/2 quantum dots in nonequilibrium: Spin-valve systems with compensating spin polarizations

    NASA Astrophysics Data System (ADS)

    Göttel, Stefan; Reininghaus, Frank; Schoeller, Herbert

    2015-07-01

    We study a pseudo-spin-1/2 quantum dot in the cotunneling regime close to the particle-hole symmetric point. For a generic tunneling matrix we find a fixed point with interesting nonequilibrium properties, characterized by effective reservoirs with compensating spin orientation vectors weighted by the polarizations and the tunneling rates. At large bias voltage we study the magnetic field dependence of the dot magnetization and the current. The fixed point can be clearly identified by analyzing the magnetization of the dot. We characterize the universal properties for the case of two reservoirs and discuss deviations from the fixed point model in experimentally realistic situations.

  17. Emergent incommensurate correlations in frustrated ferromagnetic spin-1 chains

    NASA Astrophysics Data System (ADS)

    Lee, Hyeong Jun; Choi, MooYoung; Jeon, Gun Sang

    2017-01-01

    We study frustrated ferromagnetic spin-1 chains, where the ferromagnetic nearest-neighbor coupling competes with the antiferromagnetic next-nearest-neighbor coupling. We use the density-matrix renormalization group to obtain the ground states. Through the analysis of spin-spin correlations we identify the double Haldane phase as well as the ferromagnetic phase. It is shown that the ferromagnetic coupling leads to incommensurate correlations in the double Haldane phase. Such short-range correlations transform continuously into the ferromagnetic instability at the transition to the ferromagnetic phase. We also compare the results with the spin-1/2 and classical spin systems and discuss the string orders in the system.

  18. 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

    2008-09-05

    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.

  19. Cloaking spin-(1/2) matter waves

    SciTech Connect

    Lin, De-Hone

    2010-06-15

    A physical construct for the cloaking of relativistic spin-(1/2) matter waves is proposed. It is shown that when the effective energy and mass of relativistic spin-(1/2) particles moving in an effective vector field in a spherical shell are controlled, their matter waves can be perfectly guided through the shell without any distortion or loss; that is, the construct provides a three-dimensional cloaking shell for relativistic spin-(1/2) matter waves. The proposal serves as the basis for some interesting applications such as providing a method to guide the matter waves of spin particles and an ideal setup to exhibit spin-spin interactions as well as perfect quantum interferences of some global effects in spin-(1/2) matter waves.

  20. 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.

  1. 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.

  2. Coulomb interaction on spin-1 particles

    NASA Astrophysics Data System (ADS)

    Owen, D. A.; Barrett, R. C.

    2003-11-01

    Using the electro-weak theory, we find the lowest order perturbative correction to a spin-1 particle in an external Coulomb field. We show this leads to a correction of order (Zα)4 and is independent of the mass of the external field. Previous work with Duffin-Kemmer-Petiau (see Nedjadi and Barrett [J. Math. Phys. 35 (1994) 4517]) and the Proca equation has failed to produce this correction.

  3. Substitution effects on the temperature versus magnetic field phase diagrams of the quasi-one-dimensional effective Ising spin-1/2 chain system BaCo2V2O8

    NASA Astrophysics Data System (ADS)

    Niesen, S. K.; Breunig, O.; Salm, S.; Seher, M.; Valldor, M.; Warzanowski, P.; Lorenz, T.

    2014-09-01

    BaCo2V2O8 is a quasi-one-dimensional antiferromagnetic spin-1/2 chain system with pronounced Ising anisotropy of the magnetic exchange. Due to finite interchain interactions, long-range antiferromagnetic order develops below TN≃5.5K, which is accompanied by a structural distortion in order to lift magnetic frustration effects. The corresponding temperature versus magnetic-field phase diagram is highly anisotropic with respect to the magnetic-field direction and various details are still under vivid discussion. Here, we report the influence of several substitutions on the magnetic properties and the phase diagrams of BaCo2V2O8. We investigate the substitution series Ba1-xSrxCo2V2O8 over the full range 0≤x≤1 as well as the influence of a partial substitution of the magnetic Co2+ by small amounts of other magnetic transition metals or by nonmagnetic magnesium. In all cases, the phase diagrams were obtained on single crystals from magnetization data and/or high-resolution studies of the thermal expansion and magnetostriction.

  4. Kibble-Zurek Mechanism in a Spin-1 Ferromagnetic BEC

    NASA Astrophysics Data System (ADS)

    Anquez, Martin; Robbins, Bryce; Bharath, H. M.; Boguslawski, Matthew; Hoang, Thai; Chapman, Michael

    2015-05-01

    A ferromagnetic spin-1 87Rb BEC exhibits a second-order gapless quantum phase transition due to the competition between magnetic and collisional spin interaction energies. In such a system, we expect to observe universal Kibble-Zurek power-law scaling of the excitations for slow quenches through the critical point. In spatially extended systems, the Kibble-Zurek mechanism is manifest in topological defects. In our small spin condensates, the excitations appear in the temporal evolution of the spin populations. In this poster, we present our experimental investigation of the spin excitations as a function of the quench speed when the system is driven from the polar to ferromagnetic phase. Our results are quantitatively compared with quantum simulations.

  5. 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.

  6. Dynamic properties of spin-1/2 XY chains (in English)

    NASA Astrophysics Data System (ADS)

    Derzhko, O.; Krokhmalskii, T.

    We have considered a numerical scheme for the calculation of the equilibrium properties of spin-{1/2} XY chains. Within its frames it is necessary to solve in the last resort only the 2N× 2N eigenvalue and eigenvector problem but not the 2^N× 2^N one as for an arbitrary system consisting of N spins {1/2}. To illustrate the approach we have presented some new results. Namely, the xx dynamic structure factor for the Ising model in transverse field, the density of states for the isotropic chain with random intersite couplings and transverse fields that linearly depend on the surrounding couplings, and the zz dynamic structure factor for the Ising model in the random transverse field. The results obtained are hoped to be useful for an interpretation of observable data for one-dimensional spin-{1/2} XY substances.

  7. Analytical solutions for the spin-1 Bose-Einstein condensate in a harmonic trap

    NASA Astrophysics Data System (ADS)

    Shi, Yu-Ren; Wang, Xue-Ling; Wang, Guang-Hui; Liu, Cong-Bo; Zhou, Zhi-Gang; Yang, Hong-Juan

    2013-06-01

    The homotopy analysis method and Galerkin spectral method are applied to find the analytical solutions for the Gross-Pitaevskii equations, a set of nonlinear Schrödinger equation used in simulation of spin-1 Bose-Einstein condensates trapped in a harmonic potential. We investigate the one-dimensional case and get the approximate analytical solutions successfully. Comparisons between the analytical solutions and the numerical solutions have been made. The results indicate that they are in agreement well with each other when the atomic interaction is weakly. We also find a class of exact solutions for the stationary states of the spin-1 system with harmonic potential for a special case.

  8. Comment on ``Electronic structure of spin- (1)/(2) Heisenberg antiferromagnetic systems: Ba2Cu(PO4)2 and Sr2Cu(PO4)2 ''

    NASA Astrophysics Data System (ADS)

    Rosner, H.; Schmitt, M.; Kasinathan, D.; Ormeci, A.; Richter, J.; Drechsler, S.-L.; Johannes, M. D.

    2009-03-01

    Recently S. S. Salunke [Phys. Rev. B 76, 085104 (2007)] reinvestigated the electronic and magnetic properties of the low-dimensional spin-1/2 materials Sr2Cu(PO4)2 and Ba2Cu(PO4)2 . Based on a NMTO downfolding methodology their main result is a considerably reduced transfer term along the magnetic chains compared to an earlier study [M. D. Johannes , Phys. Rev. B 74, 174435 (2006)]. The discrepancy is assigned to the N th-order muffin-tin orbital mapping procedure that is suggested to be more accurate than the tight-binding approach taken by Johannes Here, we demonstrate that in contrast to the suggestion of Salunke , the discrepancy arises solely from the employment of the atomic-sphere approximation in the underlying band-structure calculation rather than from the mapping scheme used. By comparison of the bandwidths of Salunke to those obtained using three different full-potential methods we find that the full-potential methods are all in nearly exact agreement with one another and yield an about 30% larger bandwidth compared to the results in Salunke . In general, our results emphasize the need for a full-potential description especially for strongly anisotropic structures as a precondition for a subsequent accurate modeling. Furthermore, we comment on the exact diagonalization results given by Salunke .

  9. 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.

  10. On properties of low-lying spin-1 hadron resonances

    NASA Astrophysics Data System (ADS)

    Chizhov, M. V.

    2017-03-01

    Properties of low-lying spin-1 hadron resonances are described in the review. It is shown how the Nambu-Jona-Lasinio model can be extended in the chiral invariant way by new tensor interactions. New mass formulas are obtained, which are not based on unitary symmetry groups but involve particles from different multiplets even with opposite parity. They all are in good agreement with experimental data. Dynamic properties of spin-1 mesons confirmed by the calculations performed using the QCD sum rule technique and the lattice calculations are understood and explained.

  11. Random crystal field effect on the magnetic and hysteresis behaviors of a spin-1 cylindrical nanowire

    NASA Astrophysics Data System (ADS)

    Zaim, N.; Zaim, A.; Kerouad, M.

    2017-02-01

    In this work, the magnetic behavior of the cylindrical nanowire, consisting of a ferromagnetic core of spin-1 atoms surrounded by a ferromagnetic shell of spin-1 atoms is studied in the presence of a random crystal field interaction. Based on Metropolis algorithm, the Monte Carlo simulation has been used to investigate the effects of the concentration of the random crystal field p, the crystal field D and the shell exchange interaction Js on the phase diagrams and the hysteresis behavior of the system. Some characteristic behaviors have been found, such as the first and second-order phase transitions joined by tricritical point for appropriate values of the system parameters, triple and isolated critical points can be also found. Depending on the Hamiltonian parameters, single, double and para hysteresis regions are explicitly determined.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    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.

  13. Metastability in the Spin-1 Blume–Emery–Griffiths Model within Constant Coupling Approximation

    NASA Astrophysics Data System (ADS)

    Ekiz, C.

    2017-02-01

    In this paper, the equilibrium properties of spin-1 Blume–Emery–Griffiths model are studied by using constant-coupling approximation. The dipolar and quadrupolar order parameters, the stable, metastable and unstable states and free energy of the model are investigated. The states are defined in terms of local minima of the free energy of system. The numerical calculations are presented for several values of exchange interactions on the simple cubic lattice with q = 6.

  14. Thermodynamic quantities and phase diagrams of spin-1 Blume-Capel bilayer Ising model

    NASA Astrophysics Data System (ADS)

    Kantar, Ersin; Ertaş, Mehmet

    2015-06-01

    An effective field theory with correlations has been used to study the critical behavior of the spin-1 Blume-Capel bilayer Ising model on a square lattice. The effects of the Hamiltonian parameters on thermodynamic quantities and phase diagrams are investigated in detail. We found that the system exhibits the first and the second order transitions as well as tricritical point. Furthermore, we have observed that the change of tricritical point values depends on interaction parameters.

  15. The paramagnetic properties of one-dimensional spin-1 single-ion anisotropic ferromagnet

    NASA Astrophysics Data System (ADS)

    Wang, Hai-Jun; Chen, Yuan; Fu, Liang-Jie; Lin, Rui-Na; Song, Chuang-Chuang

    2009-06-01

    One-dimensional single-ion anisotropic ferromagnet with spin-1 is investigated by means of Green's function treatment in this paper. The model Hamiltonian includes a Heisenberg ferromagnetic term, an external magnetic field, and a second-order single-ion anisotropy. The magnetic properties of the system are treated by the random phase approximation for the exchange interaction term and the Anderson-Callen approximation for the anisotropy term. Our paramagnetic results are in agreement with the other theoretical results.

  16. Emerging bosons with three-body interactions from spin-1 atoms in optical lattices

    SciTech Connect

    Mazza, L.; Rizzi, M.; Cirac, J. I.; Lewenstein, M.

    2010-10-15

    We study two many-body systems of bosons interacting via an infinite three-body contact repulsion in a lattice: a pairs quasicondensate induced by correlated hopping and the discrete version of the Pfaffian wave function. We propose to experimentally realize systems characterized by such interaction by means of a proper spin-1 lattice Hamiltonian: spin degrees of freedom are locally mapped into occupation numbers of emerging bosons, in a fashion similar to spin-1/2 and hardcore bosons. Such a system can be realized with ultracold spin-1 atoms in a Mott insulator with a filling factor of 1. The high versatility of these setups allows us to engineer spin-hopping operators breaking the SU(2) symmetry, as needed to approximate interesting bosonic Hamiltonians with three-body hardcore constraint. For this purpose we combine bichromatic spin-independent superlattices and Raman transitions to induce a different hopping rate for each spin orientation. Finally, we illustrate how our setup could be used to experimentally realize the first setup, that is, the transition to a pairs quasicondensed phase of the emerging bosons. We also report on a route toward the realization of a discrete bosonic Pfaffian wave function and list some open problems for reaching this goal.

  17. Finite Temperature Properties of Mixed Diamond Chain with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    We formulate statistical mechanics for a mixed diamond chain with spins 1 and 1/2. Owing to a series of conservation laws, any eigenstate of this system is decomposed into eigenstates of finite odd-length spin-1 chains. The ground state undergoes five quantum phase transitions with varying λ, a parameter that controls frustration. We evaluated the residual entropy and Curie constant which characterize each phase and phase boundary at low temperatures. We further find various characteristic finite-temperature properties such as the nonmonotonic temperature dependence of magnetic susceptibility, the multipeak structure in the λ-dependence of entropy, the plateau-like temperature dependence of entropy and the multipeak structure of specific heat.

  18. Spin-incoherent one-dimensional spin-1 Bose Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Jen, H. H.; Yip, S.-K.

    2016-09-01

    We investigate spin-incoherent Luttinger liquid of a one-dimensional spin-1 Bose gas in a harmonic trap. In this regime highly degenerate spin configurations emerge since the energy splitting between different spin states is much less than the thermal energy of the system, while the temperature is low enough that the lowest energetic orbitals are occupied. As an example we numerically study the momentum distribution of a one-dimensional spin-1 Bose gas in Tonks-Girardeau gas limit and in the sector of zero magnetization. We find that the momentum distributions broaden as the number of atoms increase due to the averaging of spin function overlaps. Large momentum (p ) asymptotic is analytically derived, showing the universal 1 /p4 dependence. We demonstrate that the spin-incoherent Luttinger liquid has a momentum distribution also distinct from spinless bosons at finite temperature.

  19. 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.

  20. 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).

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Pixley, Jedediah; Natu, Stefan; Cole, William; Rizzi, Matteo; Spielman, Ian

    2016-05-01

    We study the interplay of spin orbit coupling and strong correlations present for ultra cold spin-1 bosons on a square optical lattice. In addition to the conventional spinful Mott and superfluid phases contained in the spin-1 Bose-Hubbard model, we find new lattice symmetry breaking phases. For weak interactions, the interplay between the lattice momentum and the spin-orbit wave-vector induces a phase transition from a uniform superfluid to a phase where bosons simultaneously condense at the center and edge of the Brillouin zone. This state is characterized by spin density wave order, which arises from the spin-1 nature of the system. Interactions suppress this spin density wave order, and for sufficiently strong interactions the system becomes a Mott insulator. Inside the Mott lobes with an odd-integer filling we derive the effective low energy magnetic Hamiltonian. Focusing on the quasi-one-dimensional limit we solve the strongly coupled magnetic model in three ways: in its classical limit, with a spin-wave analysis, and using the density matrix renormalization group.

  3. Wheeler-Feynman dynamics of spin-1/2 particles

    NASA Astrophysics Data System (ADS)

    van Alstine, Peter; Crater, Horace W.

    1986-02-01

    By combining a supersymmetric description of a spinning particle in an external field with an appropriate modification of the ``adjunct field'' of Wheeler and Feynman, we construct a many-time relativistic dynamics for arbitrary numbers of spin-(1/2) and spinless particles in mutual scalar or vector interaction. Quantization of the slow-motion approximation to the dynamics of two spinning particles reproduces the corresponding field-theoretic (Bethe-Salpeter) dynamics through order α4.

  4. 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.

  5. Impact of mass generation for spin-1 mediator simplified models

    NASA Astrophysics Data System (ADS)

    Bell, Nicole F.; Cai, Yi; Leane, Rebecca K.

    2017-01-01

    In the simplified dark matter models commonly studied, the mass generation mechanism for the dark fields is not typically specified. We demonstrate that the dark matter interaction types, and hence the annihilation processes relevant for relic density and indirect detection, are strongly dictated by the mass generation mechanism chosen for the dark sector particles, and the requirement of gauge invariance. We focus on the class of models in which fermionic dark matter couples to a spin-1 vector or axial-vector mediator. However, in order to generate dark sector mass terms, it is necessary in most cases to introduce a dark Higgs field and thus a spin-0 scalar mediator will also be present. In the case that all the dark sector fields gain masses via coupling to a single dark sector Higgs field, it is mandatory that the axial-vector coupling of the spin-1 mediator to the dark matter is non-zero; the vector coupling may also be present depending on the charge assignments. For all other mass generation options, only pure vector couplings between the spin-1 mediator and the dark matter are allowed. If these coupling restrictions are not obeyed, unphysical results may be obtained such as a violation of unitarity at high energies. These two-mediator scenarios lead to important phenomenology that does not arise in single mediator models. We survey two-mediator dark matter models which contain both vector and scalar mediators, and explore their relic density and indirect detection phenomenology.

  6. Classification of trivial spin-1 tensor network states on a square lattice

    NASA Astrophysics Data System (ADS)

    Lee, Hyunyong; Han, Jung Hoon

    2016-09-01

    Classification of possible quantum spin liquid (QSL) states of interacting spin-1/2's in two dimensions has been a fascinating topic of condensed matter for decades, resulting in enormous progress in our understanding of low-dimensional quantum matter. By contrast, relatively little work exists on the identification, let alone classification, of QSL phases for spin-1 systems in dimensions higher than one. Employing the powerful ideas of tensor network theory and its classification, we develop general methods for writing QSL wave functions of spin-1 respecting all the lattice symmetries, spin rotation, and time reversal with trivial gauge structure on the square lattice. We find 25 distinct classes characterized by five binary quantum numbers. Several explicit constructions of such wave functions are given for bond dimensions D ranging from two to four, along with thorough numerical analyses to identify their physical characters. Both gapless and gapped states are found. The topological entanglement entropy of the gapped states is close to zero, indicative of topologically trivial states. In D =4 , several different tensors can be linearly combined to produce a family of states within the same symmetry class. A rich "phase diagram" can be worked out among the phases of these tensors, as well as the phase transitions among them. Among the states we identified in this putative phase diagram is the plaquette-ordered phase, gapped resonating valence bond phase, and a critical phase. A continuous transition separates the plaquette-ordered phase from the resonating valence bond phase.

  7. Interacting spin-orbit-coupled spin-1 Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    The recent experimental realization of spin-orbit (SO) coupling for spin-1 ultracold atoms opens an interesting avenue for exploring SO-coupling-related physics in large-spin systems, which is generally unattainable in electronic materials. In this paper, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 Bose-Einstein condensates (BECs) in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting in-phase or out-of-phase modulating patterns between spin-tensor and zero-spin-component density waves. 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 double maxon-roton structure in the Bogoliubov-excitation spectrum, attributed to the three band minima of the SO-coupled spin-1 BEC.

  8. 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

    2016-06-08

    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.

  9. Effects of Single-site Anisotropy on Mixed Diamond Chains with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'ichi

    2011-10-01

    Effects of single-site anisotropy on mixed diamond chains with spins 1 and 1/2 are investigated in the ground states and at finite temperatures. There are phases where the ground state is a spin cluster solid, i.e., an array of uncorrelated spin-1 clusters separated by singlet dimers. The ground state is nonmagnetic for the easy-plane anisotropy, while it is paramagnetic for the easy-axis anisotropy. Also, there are the Néel, Haldane, and large-D phases, where the ground state is a single spin cluster of infinite size and the system is equivalent to the spin-1 Heisenberg chain with alternating anisotropy. The longitudinal and transverse susceptibilities and entropy are calculated at finite temperatures in the spin-cluster-solid phases. Their low-temperature behaviors are sensitive to anisotropy.

  10. 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.

  11. 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.

  12. Production of spin-1/2 particles in inhomogeneous cosmologies

    NASA Astrophysics Data System (ADS)

    Campos, A.; Verdaguer, E.

    1992-06-01

    The production of spin-1/2 particles by small gravitational inhomogeneities is discussed by using a perturbative approach based on the evaluation of the scattering matrix. We compute the production of massive and massless particles by linear gravitational inhomogeneities in flat spacetime and the production of massless particles in an expanding universe described by the spatially flat Friedmann-Robertson-Walker models with small inhomogeneities. As in the case of scalar particles the total pair-creation probability is given in terms of geometric invariants of the spacetime.

  13. Weak value distributions for spin 1/2

    NASA Astrophysics Data System (ADS)

    Berry, M. V.; Dennis, M. R.; McRoberts, B.; Shukla, P.

    2011-05-01

    The simplest weak measurement is of a component of spin 1/2. For this observable, the probability distributions of the real and imaginary parts of the weak value, and their joint probability distribution, are calculated exactly for pre- and postselected states uniformly distributed over the surface of the Poincaré-Bloch sphere. The superweak probability, that the real part of the weak value lies outside the spectral range, is 1/3. This case, with just two eigenvalues, complements our previous calculation (Berry and Shukla 2010 J. Phys. A: Math. Theor. 43 354024) of the universal form of the weak value probability distribution for an operator with many eigenvalues.

  14. Criticality without frustration for quantum spin-1 chains.

    PubMed

    Bravyi, Sergey; Caha, Libor; Movassagh, Ramis; Nagaj, Daniel; Shor, Peter W

    2012-11-16

    Frustration-free (FF) spin chains have a property that their ground state minimizes all individual terms in the chain Hamiltonian. We ask how entangled the ground state of a FF quantum spin-s chain with nearest-neighbor interactions can be for small values of s. While FF spin-1/2 chains are known to have unentangled ground states, the case s=1 remains less explored. We propose the first example of a FF translation-invariant spin-1 chain that has a unique highly entangled ground state and exhibits some signatures of a critical behavior. The ground state can be viewed as the uniform superposition of balanced strings of left and right brackets separated by empty spaces. Entanglement entropy of one half of the chain scales as 1/2 log n+O(1), where n is the number of spins. We prove that the energy gap above the ground state is polynomial in 1/n. The proof relies on a new result concerning statistics of Dyck paths which might be of independent interest.

  15. Spinon excitations in the spin-1 XXZ chain and hidden supersymmetry

    NASA Astrophysics Data System (ADS)

    Matsui, Chihiro

    2016-12-01

    We study spinon excitations of the integrable spin-1 (Fateev-Zamolodchikov; FZ) chain and their relation to the hidden supersymmetry. Using the notion of the supercharges earlier introduced to the spin chains, which change the system length by one, we found that they nontrivially act on one of two kinds of the degrees of freedom for the FZ chain. Their actions were obtained to be the same as those of the supercharges defined on the supersymmetric sine-Gordon model, the low-energy effective field theory of the FZ chain. Moreover, we construct the eigenstates which are invariant under the supersymmetric Hamiltonian given as the anti-commutator of the supercharges.

  16. Exact and numerical results for a dimerized coupled spin- 1/2 chain

    PubMed

    Martins; Nienhuis

    2000-12-04

    We establish exact results for coupled spin-1/2 chains for special values of the four-spin interaction V and dimerization parameter delta. The first exact result is at delta = 1/2 and V = -2. Because we find a very small but finite gap in this dimerized chain, this can serve as a very strong test case for numerical and approximate analytical techniques. The second result is for the homogeneous chain with V = -4 and gives evidence that the system has a spontaneously dimerized ground state. Numerical diagonalization and bosonization techniques indicate that the interplay between dimerization and interaction could result in gapless phases in the regime 0

  17. Quantum Correlations of Two SPIN-1 Particles in the Optical Lattice

    NASA Astrophysics Data System (ADS)

    Shi, Jia-Dong; Wu, Tao; Song, Xue-Ke; Ye, Liu

    2014-01-01

    In this paper, we investigate the dynamical behaviors of quantum correlations witnessed by geometric discord and negativity when two three-level spin-1 atoms exist in the optical lattice. The results show that the GD can detect the critical point K = J at finite temperature associated with the quantum phase transition which separates the superfluid phase from the Mott insulator phase, while the negativity cannot. In addition, the system undergoes an entanglement sudden death (ESD), but the GD always exists, meanwhile, the GD is more robust than negativity against temperature T.

  18. 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.

  19. Non-Markovian dynamics in the extended cluster spin-1/2 XX chain

    NASA Astrophysics Data System (ADS)

    Mahmoudi, M.; Mahdavifar, S.; Zadeh, T. Mohammad Ali; Soltani, M. R.

    2017-01-01

    We study the dynamics of entanglement, mutual information, and quantum discord in the extended cluster spin-1/2 XX chain, equivalent to a one-dimensional spin-1/2 XX model with three-spin interaction (TSI). Selecting the nearest neighbor pair spins as an open quantum system, the rest of the chain plays the role of the environment. The two-point Heisenberg and the TSI are responsible for coupling between the system and the environment. Although the revival phenomenon of quantum correlations as an indication of non-Markovian dynamics is observed for TSI stronger than the Heisenberg interaction, the study of the trace distance has proven that the dynamical phase transition from the Markovian to the non-Markovian regime happens at a critical value where the TSI is equal to half of the Heisenberg interaction. By focusing on the nearest neighbor pair spins of the environment, we have also shown that the dynamics of quantum correlation in the environment is sensitive to Markovian and non-Markovian regions.

  20. 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.

  1. Effects of nongauge potentials on the spin-1/2 Aharonov-Bohm problem

    SciTech Connect

    Hagen, C.R. )

    1993-12-15

    Some recent work has attempted to show that the singular solutions which are known to occur in the Dirac description of spin-1/2 Aharonov-Bohm scattering can be eliminated by the inclusion of strongly repulsive potentials inside the flux tube. It is shown here that these calculations are generally unreliable since they necessarily require potentials which lead to the occurrence of Klein's paradox. To avoid that difficulty the problem is solved within the framework of the Galilean spin-1/2 wave equation which is free of that particular complication. It is then found that the singular solutions can be eliminated provided that the nongauge potential is made energy dependent. The effect of the inclusion of a Coulomb potential is also considered with the result being that the range of flux parameter for which singular solutions are allowed is only one-half as great as in the pure Aharonov-Bohm limit. Expressions are also obtained for the binding energies which can occur in the combined Aharonov-Bohm-Coulomb system.

  2. 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.

  3. 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.

  4. Zero-Temperature Study of a Tetrameric Spin-1/2 Chain in a Transverse Magnetic Field

    NASA Astrophysics Data System (ADS)

    Vahedi, J.; Arbousara, M. Shabani; Mahdavifar, S.

    2017-02-01

    We consider an alternating Heisenberg spin-1/2 antiferromagnetic-ferromagnetic chain with the space-modulated dominant antiferromagnetic exchange and anisotropic ferromagnetic coupling (tetrameric spin-1/2 chain). The zero-temperature effect of a symmetry breaking transverse magnetic field on the model is studied numerically. It is found that the anisotropy effect on the ferromagnetic coupling induces two new gapped phases. We identified their orderings as a kind of the stripe antiferromagnetic phase. As a result, the magnetic phase diagram of the tetrameric chain shows five gapped quantum phases, and the system is characterized by four critical fields which mark quantum phase transitions in the ground state of the system with the changing transverse magnetic field. We have also exploited the well-known bipartite entanglement (name as concurrence) and global entanglement tools to verify the occurrence of quantum phase transitions and the corresponding critical points.

  5. One-dimensional spin-1 ferromagnetic Heisenberg model with exchange anisotropy and single-ion anisotropy under external magnetic field

    NASA Astrophysics Data System (ADS)

    Song, Chuang-Chuang; Chen, Yuan; Liu, Ming-Wei

    2010-01-01

    The magnetic properties of the one-dimensional spin-1 ferromagnetic Heisenberg model are investigated by Green's function method. The magnetic properties of the system are treated by the random phase approximation for the exchange interaction term, and the Anderson-Callen approximation for the single-ion anisotropy term. The critical temperature, magnetization, and susceptibility are found to be dependent of the anisotropies. Our results are in agreement with the other theoretical results.

  6. Adiabatic and Non-adiabatic quenches in a Spin-1 Bose Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Boguslawski, Matthew; Hebbe Madhusudhana, Bharath; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael

    2016-05-01

    A quantum phase transition (QPT) is observed in a wide range of phenomena. We have studied the dynamics of a spin-1 ferromagnetic Bose-Einstein condensate for both adiabatic and non-adiabatic quenches through a QPT. At the quantum critical point (QCP), finite size effects lead to a non-zero gap, which makes an adiabatic quench possible through the QPT. We experimentally demonstrate such a quench, which is forbidden at the mean field level. For faster quenches through the QCP, the vanishing energy gap causes the reaction timescale of the system to diverge, preventing the system from adiabatically following the ground state. We measure the temporal evolution of the spin populations for different quench speeds and determine the exponents characterizing the scaling of the onset of excitations, which are in good agreement with the predictions of Kibble-Zurek mechanism.

  7. 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.

  8. 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

  9. 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.

  10. Symmetry restoring and ancilla-driven entanglement for ultra-cold spin-1 atoms in a three-site ring

    NASA Astrophysics Data System (ADS)

    Barasiński, Artur; Leoński, Wiesław

    2017-01-01

    The spin-change dynamics of a model with ultra-cold hyperfine-spin-1 atoms confined in an optical superlattice is discussed. First, the disturbance of the two-site dynamics by coupling the dimer to a spin-1 ancilla is analyzed. When the dimer is coupled to the ancilla, even by a weak coupling, the significant changes in the system's time-evolution processes are observed. Next, we show that for the two-particle case the total hyperfine-spin-singlet state is generated by exploiting a quadratic Zeeman shift with realistic values of the strength of external magnetic field and evolution period of time. Moreover, even in a weak coupling regime, the proper choice of the additional ancilla-dimer interaction results in generating the wave function which is characteristic of the homogeneous three-site ring. In consequence, such wave function exhibits translational invariance symmetry despite the strong asymmetry of the lattice. Furthermore, we present our proposal for extracting various kinds of maximally entangled states (MES) for three-site spin-1 systems, starting from initial product states. In particular, we show that the type of generated MES can be unambiguously recognized by the measurement performed on the ancilla.

  11. Renormalized entanglement in Heisenberg-Ising spin-1/2 chain with Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Khan, Salman; Khan, Kalimullah

    2016-06-01

    The influence of the Dzyaloshinsky-Moriya (DM) interaction on entanglement in the one-dimensional spin-1/2 Heisenberg-Ising model is investigated via concurrence. The existence of two states, different in quantum properties and linked through a critical point by quantum phase transition, in the thermodynamic limit, are identified. The strong DM interaction delays quantum phase transition and hence shifts the boundary between the two phases to the region of the strong coupling constant. The increasing strength of the DM interaction strongly restores entanglement against its degradation arising from the increasing size of the system. The first derivative of the entanglement quantifier diverges to the critical point and is related directly to the divergence of the correlation length. The scaling behavior in the vicinity of the quantum critical point is also discussed.

  12. Evolution of an isolated monopole in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Tiurev, Konstantin; Kuopanportti, Pekko; Gunyhó, András Márton; Ueda, Masahito; Möttönen, Mikko

    2016-11-01

    We simulate the decay dynamics of an isolated monopole defect in the nematic vector of a spin-1 Bose-Einstein condensate during the polar-to-ferromagnetic phase transition of the system. Importantly, the decay of the monopole occurs in the absence of external magnetic fields and is driven principally by the dynamical instability due to the ferromagnetic spin-exchange interactions. An initial isolated monopole is observed to relax into a polar-core spin vortex, thus demonstrating the spontaneous transformation of a point defect of the polar order parameter manifold to a line defect of the ferromagnetic manifold. We also investigate the dynamics of an isolated monopole pierced by a quantum vortex line with winding number κ . It is shown to decay into a coreless Anderson-Toulouse vortex if κ =1 and into a singular vortex with an empty core if κ =2 . In both cases, the resulting vortex is also encircled by a polar-core vortex ring.

  13. Quantum control of spin-nematic squeezing in a dipolar spin-1 condensate.

    PubMed

    Huang, Yixiao; Xiong, Heng-Na; Yang, Yang; Hu, Zheng-Da; Xi, Zhengjun

    2017-02-24

    Versatile controllability of interactions and magnetic field in ultracold atomic gases ha now reached an era where spin mixing dynamics and spin-nematic squeezing can be studied. Recent experiments have realized spin-nematic squeezed vacuum and dynamic stabilization following a quench through a quantum phase transition. Here we propose a scheme for storage of maximal spin-nematic squeezing, with its squeezing angle maintained in a fixed direction, in a dipolar spin-1 condensate by applying a microwave pulse at a time that maximal squeezing occurs. The dynamic stabilization of the system is achieved by manipulating the external periodic microwave pulses. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is numerical simulated and agrees with a stability analysis. Moreover, the stability range coincides well with the spin-nematic vacuum squeezed region which indicates that the spin-nematic squeezed vacuum will never disappear as long as the spin dynamics are stabilized.

  14. 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

  15. 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.

  16. Structure functions in the polarized Drell-Yan processes with spin-1/2 and spin-1 hadrons. I. General formalism

    NASA Astrophysics Data System (ADS)

    Hino, S.; Kumano, S.

    1999-05-01

    We discuss a general formalism for the structure functions which can be investigated in the polarized Drell-Yan processes with spin-1/2 and spin-1 hadrons. To be specific, the formalism can be applied to the proton-deuteron Drell-Yan processes. Because of the spin-1 nature, there are new structure functions which cannot be studied in the proton-proton reactions. Imposing Hermiticity, parity conservation, and time-reversal invariance, we find that 108 structure functions exist in the Drell-Yan processes. However, the number reduces to 22 after integrating the cross section over the virtual-photon transverse momentum Q-->T or after taking the limit QT-->0. There are 11 new structure functions in addition to the 11 in the Drell-Yan processes of spin-1/2 hadrons. The additional structure functions are associated with the tensor structure of the spin-1 hadron, and they could be measured by quadrupole spin asymmetries. For example, the structure functions exist for ``intermediate'' polarization although their contributions vanish in the longitudinal and transverse polarization reactions. We show a number of spin asymmetries for extracting the polarized structure functions. The proton-deuteron reaction may be realized in the RHIC-SPIN project and other future ones, and it could be a new direction of next generation high-energy spin physics.

  17. Quantum critical behavior of low-dimensional spin 1/2 Heisenberg antiferromagnets

    NASA Astrophysics Data System (ADS)

    Stone, Matthew Brandon

    In this dissertation, experiments on four different insulating antiferromagnetic spin 1/2 Heisenberg systems are presented and described. Copper pyrazine dinitrate is a linear chain spin 1/2 (S = 1/2) Heisenberg antiferromagnet. In an applied magnetic field, the continuum splits into multiple continua including incommensurate gapless excitations. The inelastic neutron scattering measurements presented represent the first complete experimental study of the S = 1/2 linear chain excitation spectrum in an applied magnetic field. Copper nitrate is a S = 1/2 alternating chain Heisenberg antiferromagnet. This system is near the isolated dimer limit, such that perturbation theory based on weakly coupled spin pairs accurately describes the excitation spectrum. Inelastic neutron scattering measurements were performed as a function of applied magnetic field. The data presented here represent the first such measure in all portions of the magnetic phase diagram of a gapped quantum magnet. Piperazinium hexachlorodicuprate is a two-dimensional S = 1/2 Heisenberg antiferromagnet. It is shown in this work that the structure consists of a collection of coupled spins in the crystalline ac plane. Multiple spin-spin interactions are important in this material. This has consequences for the nature of the dominant interactions and causes there to be significant spin frustration in this system. The spectrum consists of coherent dispersive singlet-triplet excitations describable in terms of multiple significant exchange interactions with geometrical frustration. Thermodynamic and inelastic neutron scattering measurements are presented which characterize the magnetic excitations as a function of temperature and applied magnetic field. In addition, the full magnetic phase diagram including a gapless disordered phase and a reentrant phase transition is presented. Cu2(1,4-diazacycloheptane)2Cl4 was widely believed to be a S = 1/2 Heisenberg spin-ladder material. Neutron scattering measurements

  18. 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.

  19. Characterizing the ``Higgs'' amplitude mode in a Spin-1 Bose Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Hebbe Madhusudhana, Bharath; Boguslawski, Matthew; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael

    2016-05-01

    Spontaneous symmetry breaking in a physical system is often characterized by massless Nambu-Goldstone modes and massive Anderson-Higgs modes. It occurs when a system crosses a quantum critical point (QCP) reaching a state does not share the symmetry of the underlying Hamiltonian. In a spin-1 Bose Einstein condensate, the transverse spin component can be considered as an order parameter. A quantum phase transition (QPT) of this system results in breaking of the symmetry group U(1) × SO(2) shared by the Hamiltonian. As a result, two massless coupled phonon-magnon modes are produced along with a single massive mode or a Higgs-like mode, in the form of amplitude excitations of the order parameter. Here we characterize the amplitude excitations experimentally by inducing coherent oscillation in the spin population. We further use the amplitude oscillations to measure the energy gap for different phases of the QPT. At the QCP, finite size effects lead to a non-zero gap, and our measurements are consistent with this prediction.

  20. 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

  1. 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.

  2. Topological Basis Method for Four-Qubit Spin-1/2 XXZ Heisenberg Chain with Dzyaloshinskii-Moriya Interaction

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Xue, Kang; Wang, Gangcheng

    2017-03-01

    In this paper, we investigate the four-qubit spin-1/2 XXZ Heisenberg chain with Dzyaloshinskii-Moriya interaction by topological basis method, and research the relationship between the topological basis states and the ground states. In order to study the Hamiltonian system beyond XXZ model, we introduce two Temperley-Lieb algebra generators and two other generalized generators. Then we investigate the relationship between topological basis and Heisenberg XXZ model with Dzyaloshinskii-Moriya interaction. The results show that the ground state of this model falls on the topological basis state for anti-ferromagnetic case and gapless phase case.

  3. Explicit solution of the Lindblad equation for nearly isotropic boundary driven XY spin 1/2 chain

    NASA Astrophysics Data System (ADS)

    Žunkovič, Bojan; Prosen, Tomaž

    2010-08-01

    Explicit solution for the two-point correlation function in a non-equilibrium steady state of a nearly isotropic boundary driven open XY spin 1/2 chain in the Lindblad formulation is provided. A non-equilibrium quantum phase transition from exponentially decaying correlations to long range order is discussed analytically. In the regime of long range order a new phenomenon of correlation resonances is reported, where the correlation response of the system is unusually high for certain discrete values of the external bulk parameter, e.g. the magnetic field.

  4. Supersymmetries of the spin-1/2 particle in the field of magnetic vortex, and anyons

    SciTech Connect

    Correa, Francisco; Falomir, Horacio; Plyushchay, Mikhail S.

    2010-12-15

    The quantum non-relativistic spin-1/2 planar systems in the presence of a perpendicular magnetic field are known to possess the N = 2 supersymmetry. We consider such a system in the field of a magnetic vortex, and find that there are just two self-adjoint extensions of the Hamiltonian that are compatible with the standard N = 2 supersymmetry. We show that only in these two cases one of the subsystems coincides with the original spinless Aharonov-Bohm model and comes accompanied by the super-partner Hamiltonian which allows a singular behavior of the wave functions. We find a family of additional, nonlocal integrals of motion and treat them together with local supercharges in the unifying framework of the tri-supersymmetry. The inclusion of the dynamical conformal symmetries leads to an infinitely generated superalgebra, that contains several representations of the superconformal osp(2 vertical bar 2) symmetry. We present the application of the results in the framework of the two-body model of identical anyons. The nontrivial contact interaction and the emerging N = 2 linear and nonlinear supersymmetries of the anyons are discussed.

  5. Real-space mean-field theory of a spin-1 Bose gas in synthetic dimensions

    NASA Astrophysics Data System (ADS)

    Hurst, Hilary M.; Wilson, Justin H.; Pixley, J. H.; Spielman, I. B.; Natu, Stefan S.

    2016-12-01

    The internal degrees of freedom provided by ultracold atoms provide a route for realizing higher dimensional physics in systems with limited spatial dimensions. Nonspatial degrees of freedom in these systems are dubbed "synthetic dimensions." This connection is useful from an experimental standpoint but complicated by the fact that interactions alter the condensate ground state. Here we use the Gross-Pitaevskii equation to study the ground-state properties of a spin-1 Bose gas under the combined influence of an optical lattice, spatially varying spin-orbit coupling, and interactions at the mean-field level. The associated phases depend on the sign of the spin-dependent interaction parameter and the strength of the spin-orbit field. We find "charge"- and spin-density-wave phases which are directly related to helical spin order in real space and affect the behavior of edge currents in the synthetic dimension. We determine the resulting phase diagram as a function of the spin-orbit coupling and spin-dependent interaction strength, considering both attractive (ferromagnetic) and repulsive (polar) spin-dependent interactions, and we provide a direct comparison of our results with the noninteracting case. Our findings are applicable to current and future experiments, specifically with 87Rb, 7Li, 41K, and 23Na.

  6. Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Zheng, Xu-Guang; Meng, Dong-Dong; Xu, Xing-Liang; Guo, Qi-Xin

    2013-06-01

    Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at Tc1 = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm-1, we observed probable signatures of successive magnetic transitions near Tc1 = 18 K and Tc2 = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at Tc1 = 18 K although a long-range order is formed.

  7. Temperature dependence of the NMR spin-lattice relaxation rate for spin-1/2 chains

    NASA Astrophysics Data System (ADS)

    Coira, E.; Barmettler, P.; Giamarchi, T.; Kollath, C.

    2016-10-01

    We use recent developments in the framework of a time-dependent matrix product state method to compute the nuclear magnetic resonance relaxation rate 1 /T1 for spin-1/2 chains under magnetic field and for different Hamiltonians (XXX, XXZ, isotropically dimerized). We compute numerically the temperature dependence of the 1 /T1 . We consider both gapped and gapless phases, and also the proximity of quantum critical points. At temperatures much lower than the typical exchange energy scale, our results are in excellent agreement with analytical results, such as the ones derived from the Tomonaga-Luttinger liquid (TLL) theory and bosonization, which are valid in this regime. We also cover the regime for which the temperature T is comparable to the exchange coupling. In this case analytical theories are not appropriate, but this regime is relevant for various new compounds with exchange couplings in the range of tens of Kelvin. For the gapped phases, either the fully polarized phase for spin chains or the low-magnetic-field phase for the dimerized systems, we find an exponential decrease in Δ /(kBT ) of the relaxation time and can compute the gap Δ . Close to the quantum critical point our results are in good agreement with the scaling behavior based on the existence of free excitations.

  8. 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.

  9. Quantum control of spin-nematic squeezing in a dipolar spin-1 condensate

    PubMed Central

    Huang, Yixiao; Xiong, Heng-Na; Yang, Yang; Hu, Zheng-Da; Xi, Zhengjun

    2017-01-01

    Versatile controllability of interactions and magnetic field in ultracold atomic gases ha now reached an era where spin mixing dynamics and spin-nematic squeezing can be studied. Recent experiments have realized spin-nematic squeezed vacuum and dynamic stabilization following a quench through a quantum phase transition. Here we propose a scheme for storage of maximal spin-nematic squeezing, with its squeezing angle maintained in a fixed direction, in a dipolar spin-1 condensate by applying a microwave pulse at a time that maximal squeezing occurs. The dynamic stabilization of the system is achieved by manipulating the external periodic microwave pulses. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is numerical simulated and agrees with a stability analysis. Moreover, the stability range coincides well with the spin-nematic vacuum squeezed region which indicates that the spin-nematic squeezed vacuum will never disappear as long as the spin dynamics are stabilized. PMID:28233786

  10. Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei

    NASA Astrophysics Data System (ADS)

    Prescott, D. W.; Malone, M. W.; Douglass, S. P.; Sauer, K. L.

    2012-12-01

    We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance.

  11. Structure functions in the polarized Drell-Yan processes with spin-1/2 and spin-1 hadrons. II. Parton model

    NASA Astrophysics Data System (ADS)

    Hino, S.; Kumano, S.

    1999-09-01

    We analyze the polarized Drell-Yan processes with spin-1/2 and spin-1 hadrons in a parton model. Quark and antiquark correlation functions are expressed in terms of possible combinations of Lorentz vectors and pseudovectors with the constrains of Hermiticity, parity conservation, and time-reversal invariance. Then, we find tensor-polarized distributions for a spin-1 hadron. The naive parton model predicts that there exist 19 structure functions. However, there are only four or five nonvanishing structure functions, depending on whether the cross section is integrated over the virtual-photon transverse momentum Q-->T or the limit QT-->0 is taken. One of the finite structure functions is related to the tensor-polarized distribution b1, and it does not exist in the proton-proton reactions. The vanishing structure functions should be associated with higher-twist physics. The tensor distributions can be measured by the quadrupole polarization measurements. The Drell-Yan process has an advantage over the lepton reaction in the sense that the antiquark tensor polarization could be extracted rather easily.

  12. Effects of Quantum Spin-1 /2 Impurities on the Magnetic Properties of Zigzag Spin Chains

    NASA Astrophysics Data System (ADS)

    Karmakar, Koushik; Skoulatos, Markos; Prando, Giacomo; Roessli, Bertran; Stuhr, Uwe; Hammerath, Franziska; Rüegg, Christian; Singh, Surjeet

    2017-03-01

    We investigate the effect of Co2 + (spin-1 /2 ) impurities on the magnetic ground state and low-lying spin excitations of the quasione-dimensional spin-1 /2 antiferromagnet SrCuO2 by means of neutron scattering, muon spin spectroscopy, and bulk (ac and dc) magnetic susceptibilities. We found that dilute Co doping induces an Ising-like anisotropy and enhances the magnetic ordering temperature rather significantly, but preserves the gapless nature of the spin excitations. These results are in apparent contradiction with the recent studies of Ni (spin-1) doped SrCuO2 . Low-temperature magnetic behavior of the Co-doped zigzag chains in SrCuO2 reveals the presence of a weak geometrical spin frustration.

  13. Effects of Quantum Spin-1/2 Impurities on the Magnetic Properties of Zigzag Spin Chains.

    PubMed

    Karmakar, Koushik; Skoulatos, Markos; Prando, Giacomo; Roessli, Bertran; Stuhr, Uwe; Hammerath, Franziska; Rüegg, Christian; Singh, Surjeet

    2017-03-10

    We investigate the effect of Co^{2+} (spin-1/2) impurities on the magnetic ground state and low-lying spin excitations of the quasione-dimensional spin-1/2 antiferromagnet SrCuO_{2} by means of neutron scattering, muon spin spectroscopy, and bulk (ac and dc) magnetic susceptibilities. We found that dilute Co doping induces an Ising-like anisotropy and enhances the magnetic ordering temperature rather significantly, but preserves the gapless nature of the spin excitations. These results are in apparent contradiction with the recent studies of Ni (spin-1) doped SrCuO_{2}. Low-temperature magnetic behavior of the Co-doped zigzag chains in SrCuO_{2} reveals the presence of a weak geometrical spin frustration.

  14. Subspace controllability of spin-1/2 chains with symmetries

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoting; Burgarth, Daniel; Schirmer, S.

    2016-11-01

    We develop a technique to prove simultaneous subspace controllability on multiple invariant subspaces, which specifically enables us study the controllability properties of spin systems that are not amenable to standard controllability arguments based on energy level connectivity graphs or simple induction arguments on the length of the chain. The technique is applied to establish simultaneous subspace controllability for Heisenberg spin chains subject to limited local controls. This model is theoretically important and the controllability result shows that a single control can be sufficient for complete controllability of an exponentially large subspace and universal quantum computation in the exponentially large subspace. The controllability results are extended to prove subspace controllability in the presence of control field leakage and discuss minimal control resources required to achieve controllability over the entire spin chain space.

  15. 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.

  16. Magnetic properties, Lyapunov exponent and superstability of the spin-{1}/{2} Ising-Heisenberg model on a diamond chain

    NASA Astrophysics Data System (ADS)

    Ananikian, N.; Hovhannisyan, V.

    2013-05-01

    The exactly solvable spin-{1}/{2} Ising-Heisenberg model on a diamond chain has been considered. We have found the exact results for the magnetization using the recursion relation method. The existence of the magnetization plateau has been observed at one third of the saturation magnetization in the antiferromagnetic case. Some ground-state properties of the model are examined. At low temperatures, the system has two ferrimagnetic (FRI1 and FRI2) phases and one paramagnetic (PRM) phase. Lyapunov exponents for the various values of the exchange parameters and temperatures have been analyzed. It has also been shown that the maximal Lyapunov exponent exhibits plateau. Lyapunov exponents exhibit different behavior for two ferrimagnetic phases. We have found the existence of the supercritical point for the multi-dimensional rational mapping of the spin-{1}/{2} Ising-Heisenberg model on a diamond chain for the first time in the absence of the external magnetic field and T→0 in the antiferromagnetic case.

  17. On the uniqueness of paths for spin-0 and spin-1 quantum mechanics

    NASA Astrophysics Data System (ADS)

    Struyve, W.; De Baere, W.; De Neve, J.; De Weirdt, S.

    2004-02-01

    The uniqueness of the Bohmian particle interpretation of the Kemmer equation, which describes massive spin-0 and spin-1 particles, is discussed. Recently the same problem for spin-(1/2) was dealt with by Holland. It appears that the uniqueness of boson paths can be enforced under well determined conditions. This in turn fixes the nonrelativistic particle equations of the nonrelativistic Schrödinger equation, which appear to correspond with the original definitions given by de Broglie and Bohm only in the spin-0 case. Similar to the spin-(1/2) case, there appears an additional spin-dependent term in the guidance equation in the spin-1 case. We also discuss the ambiguity associated with the introduction of an electromagnetic coupling in the Kemmer theory. We argue that when the minimal coupling is correctly introduced, then the current constructed from the energy-momentum tensor is no longer conserved. Hence this current cannot serve as a particle probability four-vector.

  18. Ground-State Phases of Anisotropic Mixed Diamond Chains with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2014-11-01

    The ground-state phases of anisotropic mixed diamond chains with spins 1 and 1/2 are investigated. Both single-site and exchange anisotropies are considered. We find the phases consisting of an array of uncorrelated spin-1 clusters separated by singlet dimers. Except in the simplest case where the cluster consists of a single S = 1 spin, this type of ground state breaks the translational symmetry spontaneously. Although the mechanism leading to this type of ground state is the same as that in the isotropic case, it is nonmagnetic or paramagnetic depending on the competition between two types of anisotropy. We also find the Néel, period-doubled Néel, Haldane, and large-D phases, where the ground state is a single spin cluster of infinite size equivalent to the spin-1 Heisenberg chain with alternating anisotropies. The ground-state phase diagrams are determined for typical sets of parameters by numerical analysis. In various limiting cases, the ground-state phase diagrams are determined analytically. The low-temperature behaviors of magnetic susceptibility and entropy are investigated to distinguish each phase by observable quantities. The relationship of the present model with the anisotropic rung-alternating ladder with spin-1/2 is also discussed.

  19. Analytical and numerical studies of disordered spin-1 Heisenberg chains with aperiodic couplings

    NASA Astrophysics Data System (ADS)

    Casa Grande, H. L.; Laflorencie, N.; Alet, F.; Vieira, A. P.

    2014-04-01

    We investigate the low-temperature properties of the one-dimensional spin-1 Heisenberg model with geometric fluctuations induced by aperiodic but deterministic coupling distributions, involving two parameters. We focus on two aperiodic sequences, the Fibonacci sequence and the 6-3 sequence. Our goal is to understand how these geometric fluctuations modify the physics of the (gapped) Haldane phase, which corresponds to the ground state of the uniform spin-1 chain. We make use of different adaptations of the strong-disorder renormalization-group (SDRG) scheme of Ma, Dasgupta, and Hu, widely employed in the study of random spin chains, supplemented by quantum Monte Carlo and density-matrix renormalization-group numerical calculations, to study the nature of the ground state as the coupling modulation is increased. We find no phase transition for the Fibonacci chain, while we show that the 6-3 chain exhibits a phase transition to a gapless, aperiodicity-dominated phase similar to the one found for the aperiodic spin-1/2 XXZ chain. Contrary to what is verified for random spin-1 chains, we show that different adaptations of the SDRG scheme may lead to different qualitative conclusions about the nature of the ground state in the presence of aperiodic coupling modulations.

  20. Three-component Gross-Pitaevskii equations in the spin-1 Bose-Einstein condensate: Spin-rotation symmetry, matter-wave solutions, and dynamics.

    PubMed

    Wen, Zichao; Yan, Zhenya

    2017-03-01

    We report new matter-wave solutions of the one-dimensional spin-1 Bose-Einstein condensate system by combining global spin-rotation states and similarity transformation. Dynamical behaviors of non-stationary global spin-rotation states derived from the SU(2) spin-rotation symmetry are discussed, which exhibit temporal periodicity. We derive generalized bright-dark mixed solitons and new rogue wave solutions and reveal the relations between Euler angles in spin-rotation symmetry and parameters in ferromagnetic and polar solitons. In the modulated spin-1 Bose-Einstein condensate system, new solutions are derived and graphically illustrated for different types of modulations. Moreover, numerical simulations are performed to investigate the stability of some obtained solutions for chosen parameters.

  1. Spin-1 diquark contributing to the formation of tetraquarks in light mesons

    NASA Astrophysics Data System (ADS)

    Kim, Hungchong; Cheoun, Myung-Ki; Kim, K. S.

    2017-03-01

    We apply a mixing framework to the light-meson systems and examine tetraquark possibility in the scalar channel. In the diquark-antidiquark model, a scalar diquark is a compact object when its color and flavor structures are in (\\bar{3}_c, \\bar{3}_f). Assuming that all the quarks are in an S-wave, the spin-0 tetraquark formed out of this scalar diquark has only one spin configuration, |J,J_{12},J_{34}\\rangle =|000\\rangle , where J is the spin of the tetraquark, J_{12} the diquark spin, J_{34} the antidiquark spin. In this construction of the scalar tetraquark, we notice that another compact diquark with spin-1 in (6_c, \\bar{3}_f) can be used although it is less compact than the scalar diquark. The spin-0 tetraquark constructed from this vector diquark leads to the spin configuration |J,J_{12},J_{34}\\rangle =|011\\rangle . The two configurations, |000\\rangle and |011\\rangle , are found to mix strongly through the color-spin interaction. The physical states can be identified with certain mixtures of the two configurations which diagonalize the hyperfine masses of the color-spin interaction. Matching these states to two scalar resonances a_0(980), a_0(1450) or to K^*_0(800), K^*_0(1430) depending on the isospin channel, we find that their mass splittings are qualitatively consistent with the hyperfine mass splittings, which can support their tetraquark structure. To test our mixing scheme further, we also construct the tetraquarks for J=1,J=2 with the spin configurations |111\\rangle and |211\\rangle , and we discuss possible candidates in the physical spectrum.

  2. Phase diagrams and magnetic properties of ferrimagnetic mixed spin-1/2 and spin-3/2 Ising nanowire

    NASA Astrophysics Data System (ADS)

    Boughazi, B.; Boughrara, M.; Kerouad, M.

    2017-01-01

    A hexagonal nanowire consisting of a ferromagnetic spin-1/2 core and spin-3/2 outer shell coupled with ferrimagnetic interlayer coupling has been studied by the use of the Monte Carlo simulation based on the heat bath algorithm. Particular emphasis is given to the effects of the size, the crystal field, the shell and the interface coupling constants on the critical and the compensation phenomenon. Some interesting behaviors have been observed which include the first and second order phase transitions. The isolated critical points are also observed. We have also found that the system exhibits the compensation phenomenon for appropriate values of the system parameters. The critical exponent has also been calculated.

  3. Dynamics of polar-core spin vortices in a ferromagnetic spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    A ferromagnetic spin-1 condensate supports polar-core spin vortices (PCVs) in the easy plane phase. We derive a model for the dynamics of these PCVs using a variational Lagrangian approach. The PCVs behave as massive charged particles interacting under the two-dimensional Coulomb interaction, with the mass arising from interaction effects within the vortex core. We compare this model to numerical simulations of the spin-1 Gross-Pitaevskii equations and find semiquantitative agreement. In addition, the numerical results suggest that the PCV core couples to spin waves, and this affects the PCV dynamics even far from the core. We identify areas of further research that could extend the model of PCV dynamics presented here.

  4. 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.

  5. Power conversion efficiency enhancement in OPV devices using spin 1/2 molecular additives

    NASA Astrophysics Data System (ADS)

    Basel, Tek; Vardeny, Valy; Yu, Luping

    2014-03-01

    We investigated the power conversion efficiency of bulk heterojunction OPV cells based on the low bandgap polymer PTB7, blend with C61-PCBM. We also employed the technique of photo-induced absorption, PA; electrical and magneto-PA (MPA) techniques to understand the details of the photocurrent generation process in this blend. We found that spin 1/2 molecular additives, such as Galvinoxyl (Gxl) radicals dramatically enhance the cell efficiency; we obtained 20% increase in photocurrent upon Gxl doping with 2% weight. We explain our finding by the ability of the spin 1/2 radicals to interfere with the known major loss mechanism in the cell due to recombination of charge transfer exciton at the D-A interface via triplet excitons in the polymer donors. Supported by National Science Foundation-Material Science & Engineering Center (NSF-MRSEC), University of Utah.

  6. Topological basis associated with B-M-W algebra: Two-spin-1/2 realization

    NASA Astrophysics Data System (ADS)

    Wang, Gangcheng; Sun, Chunfang; Liu, Bo; Liu, Ying; Zhang, Yan; Xue, Kang

    2015-01-01

    In this letter, we study the two-spin-1/2 realization for the Birman-Murakami-Wenzl (B-M-W) algebra and the corresponding Yang-Baxter R ˘ (θ , ϕ) matrix. Based on the two-spin-1/2 realization for the B-M-W algebra, the three-dimensional topological space, which is spanned by topological basis, is investigated. By means of such topological basis realization, the four-dimensional Yang-Baxter R ˘ (θ , ϕ) can be reduced to Wigner DJ function with J = 1. The entanglement and Berry phase in the spectral parameter space are also explored. The results show that one can obtain a set of entangled basis via Yang-Baxter R ˘ (θ , ϕ) matrix acting on the standard basis, and the entanglement degree is maximum when the R˘i (θ , ϕ) turns to the braiding operator.

  7. Next-to-leading order gravitational spin1-spin2 coupling with Kaluza-Klein reduction

    SciTech Connect

    Levi, Michele

    2010-09-15

    We use the recently proposed Kaluza-Klein (KK) reduction over the time dimension, within an effective field theory (EFT) approach, to calculate the next-to-leading order gravitational spin1-spin2 interaction between two spinning compact objects. It is shown here that to next-to-leading order in the spin1-spin2 interaction, the reduced KK action within the stationary approximation is sufficient to describe the gravitational interaction, and that it simplifies calculation substantially. We also find here that the gravitomagnetic vector field defined within the KK decomposition of the metric mostly dominates the mediation of the interaction. Our results coincide with those calculated in the Arnowitt-Deser-Misner Hamiltonian formalism, and we provide another explanation for the discrepancy with the result previously derived within the EFT approach, thus demonstrating clearly the equivalence of the Arnowitt-Deser-Misner Hamiltonian formalism and the EFT action approach.

  8. Spin-superflow turbulence in spin-1 ferromagnetic spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Fujimoto, Kazuya; Tsubota, Makoto

    2014-07-01

    Spin-superflow turbulence (SST) in spin-1 ferromagnetic spinor Bose-Einstein condensates is theoretically and numerically studied by using the spin-1 spinor Gross-Pitaevskii (GP) equations. SST is turbulence in which the disturbed spin and superfluid velocity fields are coupled. Applying the Kolmogorov-type dimensional scaling analysis to the hydrodynamic equations of spin and velocity fields, we theoretically find that the -5/3 and -7/3 power laws can appear in spectra of the superflow kinetic and the spin-dependent interaction energies, respectively. Our numerical calculation of the GP equations with a phenomenological small-scale energy dissipation confirms SST with the coexistence of disturbed spin and superfluid velocity field with two power laws.

  9. Distinct spin liquids and their transitions in spin-1/2 XXZ kagome antiferromagnets.

    PubMed

    He, Yin-Chen; Chen, Yan

    2015-01-23

    By using the density matrix renormalization group approach, we study spin-liquid phases of spin-1/2 XXZ kagome antiferromagnets. We find that the emergence of the spin-liquid phase is independent of the anisotropy of the XXZ interaction. In particular, the two extreme limits-the Ising (a strong S^{z} interaction) and the XY (zero S^{z} interaction)-host the same spin-liquid phases as the isotropic Heisenberg model. Both a time-reversal-invariant spin liquid and a chiral spin liquid with spontaneous time-reversal symmetry breaking are obtained. We show that they evolve continuously into each other by tuning the second- and the third-neighbor interactions. And last, we discuss possible implications of our results for the nature of spin liquid in nearest-neighbor XXZ kagome antiferromagnets, including the nearest-neighbor spin-1/2 kagome antiferromagnetic Heisenberg model.

  10. 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.

  11. What did we learn from the Aharonov-Bohm effect? Is spin 1/2 different?

    SciTech Connect

    Peshkin, M.

    1994-06-01

    I review what has been learned about fundamental issues in quantum mechanics from the Aharonov-Bohm effect. Following that, I consider the Aharonov-Casher effect and the Scalar Aharonov-Bohm effect, in both of which a spin-1/2 particle interacts with a local electromagnetic field through its magnetic moment, and conclude that those effects can be described as observable effects of local torques.

  12. Performance of an irreversible quantum Carnot engine with spin 1/2

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Chen, Lingen; Wu, Shuang; Sun, Fengrui; Wu, Chih

    2006-06-01

    The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible Carnot cycle with spin 1/2. The optimal relationship between the dimensionless power output P* versus the efficiency η for the irreversible quantum Carnot engine with heat leakage and other irreversible losses is derived. Especially, the performances of the engine at low temperature limit and at high temperature limit are discussed.

  13. Magnetism-driven ferroelectricity in spin-1/2 X Y chains

    NASA Astrophysics Data System (ADS)

    Menchyshyn, Oleg; Ohanyan, Vadim; Verkholyak, Taras; Krokhmalskii, Taras; Derzhko, Oleg

    2015-11-01

    We illustrate the magnetoelectric effect conditioned by the Katsura-Nagaosa-Balatsky (KNB) mechanism within the frames of exactly solvable spin-1 /2 X Y chains. Due to three-spin interactions which are present in our consideration, the magnetization (polarization) is influenced by the electric (magnetic) field even in the absence of the magnetic (electric) field. We also discuss a magnetoelectrocaloric effect examining the entropy changes under the isothermal varying of the magnetic and/or electric field.

  14. Order-disorder transition in a two-dimensional boron-carbon-nitride alloy

    NASA Astrophysics Data System (ADS)

    Lu, Jiong; Zhang, Kai; Feng Liu, Xin; Zhang, Han; Chien Sum, Tze; Castro Neto, Antonio H.; Loh, Kian Ping

    2013-10-01

    Two-dimensional boron-carbon-nitride materials exhibit a spectrum of electronic properties ranging from insulating to semimetallic, depending on their composition and geometry. Detailed experimental insights into the phase separation and ordering in such alloy are currently lacking. Here we report the mixing and demixing of boron-nitrogen and carbon phases on ruthenium (0001) and found that energetics for such processes are modified by the metal substrate. The brick-and-mortar patchwork observed of stoichiometrically percolated hexagonal boron-carbon-nitride domains surrounded by a network of segregated graphene nanoribbons can be described within the Blume-Emery-Griffiths model applied to a honeycomb lattice. The isostructural boron nitride and graphene assumes remarkable fluidity and can be exchanged entirely into one another by a catalytically assistant substitution. Visualizing the dynamics of phase separation at the atomic level provides the premise for enabling structural control in a two-dimensional network for broad nanotechnology applications.

  15. Order-disorder transition in a two-dimensional boron-carbon-nitride alloy.

    PubMed

    Lu, Jiong; Zhang, Kai; Liu, Xin Feng; Zhang, Han; Sum, Tze Chien; Castro Neto, Antonio H; Loh, Kian Ping

    2013-01-01

    Two-dimensional boron-carbon-nitride materials exhibit a spectrum of electronic properties ranging from insulating to semimetallic, depending on their composition and geometry. Detailed experimental insights into the phase separation and ordering in such alloy are currently lacking. Here we report the mixing and demixing of boron-nitrogen and carbon phases on ruthenium (0001) and found that energetics for such processes are modified by the metal substrate. The brick-and-mortar patchwork observed of stoichiometrically percolated hexagonal boron-carbon-nitride domains surrounded by a network of segregated graphene nanoribbons can be described within the Blume-Emery-Griffiths model applied to a honeycomb lattice. The isostructural boron nitride and graphene assumes remarkable fluidity and can be exchanged entirely into one another by a catalytically assistant substitution. Visualizing the dynamics of phase separation at the atomic level provides the premise for enabling structural control in a two-dimensional network for broad nanotechnology applications.

  16. Spin-1 Ising model: exact damage-spreading relations and numerical simulations.

    PubMed

    Anjos, A S; Mariz, A M; Nobre, F D; Araujo, I G

    2008-09-01

    The nearest-neighbor-interaction spin-1 Ising model is investigated within the damage-spreading approach. Exact relations involving quantities computable through damage-spreading simulations and thermodynamic properties are derived for such a model, defined in terms of a very general Hamiltonian that covers several spin-1 models of interest in the literature. Such relations presuppose translational invariance and hold for any ergodic dynamical procedure, leading to an efficient tool for obtaining thermodynamic properties. The implementation of the method is illustrated through damage-spreading simulations for the ferromagnetic spin-1 Ising model on a square lattice. The two-spin correlation function and the magnetization are obtained, with precise estimates of their associated critical exponents and of the critical temperature of the model, in spite of the small lattice sizes considered. These results are in good agreement with the universality hypothesis, with critical exponents in the same universality class of the spin- 12 Ising model. The advantage of the present method is shown through a significant reduction of finite-size effects by comparing its results with those obtained from standard Monte Carlo simulations.

  17. 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.

  18. Spontaneous dimerization, critical lines, and short-range correlations in a frustrated spin-1 chain

    NASA Astrophysics Data System (ADS)

    Chepiga, Natalia; Affleck, Ian; Mila, Frédéric

    2016-11-01

    We report on a detailed investigation of the spin-1 J1-J2-J3 Heisenberg model, a frustrated model with nearest-neighbor coupling J1, next-nearest neighbor coupling J2, and a three-site interaction J3[(Si -1.Si) (Si.Si +1) +H .c . ] previously studied in [Phys. Rev. B 93, 241108(R) (2016), 10.1103/PhysRevB.93.241108]. Using density matrix renormalization group (DMRG) and exact diagonalizations, we show that the phase boundaries between the Haldane phase, the next-nearest neighbor Haldane phase, and the dimerized phase can be very accurately determined by combining the information deduced from the dimerization, the ground-state energy, the entanglement spectrum and the Berry phase. By a careful investigation of the finite-size spectrum, we also show that the transition between the next-nearest neighbor Haldane phase and the dimerized phase is in the Ising universality class all along the critical line. Furthermore, we justify the conformal embedding of the SU (2) 2 Wess-Zumino-Witten conformal field theory in terms of a boson and an Ising field, and we explicitly derive a number of consequences of this embedding for the spectrum along the SU (2) 2 transition line between the Haldane phase and the dimerized phase. We also show that the solitons along the first-order transition line between the Haldane phase and the dimerized phase carry a spin-1/2, while the domain walls between different dimerization domains inside the dimerized phase carry a spin 1. Finally, we show that short-range correlations change character in the Haldane and dimerized phases through disorder and Lifshitz lines, as well as through the development of short-range dimer correlations in the Haldane phase, leading to a remarkably rich phase diagram.

  19. High-temperature series expansion for spin-1/2 Heisenberg models

    NASA Astrophysics Data System (ADS)

    Hehn, Andreas; van Well, Natalija; Troyer, Matthias

    2017-03-01

    We present a high-temperature series expansion code for spin-1/2 Heisenberg models on arbitrary lattices. As an example we demonstrate how to use the application for an anisotropic triangular lattice with two independent couplings J1 and J2 and calculate the high-temperature series of the magnetic susceptibility and the static structure factor up to 12th and 10th order, respectively. We show how to extract effective coupling constants for the triangular Heisenberg model from experimental data on Cs2CuBr4.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  1. Critical behavior of the spin-1 Blume-Capel model on two-dimensional Voronoi-Delaunay random lattices.

    PubMed

    Fernandes, F P; de Albuquerque, Douglas F; Lima, F W S; Plascak, J A

    2015-08-01

    The critical properties of the spin-1 Blume-Capel model in two dimensions is studied on Voronoi-Delaunay random lattices with quenched connectivity disorder. The system is treated by applying Monte Carlo simulations using the heat-bath update algorithm together with single histograms re-weighting techniques. We calculate the critical temperature as well as the critical exponents as a function of the crystal field Δ. It is found that this disordered system exhibits phase transitions of first- and second-order types that depend on the value of the crystal field. For values of Δ≤3, where the nearest-neighbor exchange interaction J has been set to unity, the disordered system presents a second-order phase transition. The results suggest that the corresponding exponent ratio belongs to the same universality class as the regular two-dimensional ferromagnetic model. There exists a tricritical point close to Δt=3.05(4) with different critical exponents. For Δt≤Δ<3.4 this model undergoes a first-order phase transition. Finally, for Δ≥3.4 the system is always in the paramagnetic phase.

  2. 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.

  3. Quantum spin-1 anisotropic ferromagnetic Heisenberg model in a crystal field: a variational approach.

    PubMed

    Carvalho, D C; Plascak, J A; Castro, L M

    2013-09-01

    A variational approach based on Bogoliubov inequality for the free energy is employed in order to treat the quantum spin-1 anisotropic ferromagnetic Heisenberg model in the presence of a crystal field. Within the Bogoliubov scheme an improved pair approximation has been used. The temperature-dependent thermodynamic functions have been obtained and provide much better results than the previous simple mean-field scheme. In one dimension, which is still nonintegrable for quantum spin-1, we get the exact results in the classical limit, or near-exact results in the quantum case, for the free energy, magnetization, and quadrupole moment, as well for the transition temperature. In two and three dimensions the corresponding global phase diagrams have been obtained as a function of the parameters of the Hamiltonian. First-order transition lines, second-order transition lines, tricritical and tetracritical points, and critical endpoints have been located through the analysis of the minimum of the Helmholtz free energy and a Landau-like expansion in the approximated free energy. Only first-order quantum transitions have been found at zero temperature. Limiting cases, such as isotropic Heisenberg, Blume-Capel, and Ising models, have been analyzed and compared to previous results obtained from other analytical approaches as well as from Monte Carlo simulations.

  4. Exploring ground states and excited states of spin-1 Bose-Einstein condensates by continuation methods

    SciTech Connect

    Chen, Jen-Hao; Chern, I-Liang; Wang Weichung

    2011-03-20

    A pseudo-arclength continuation method (PACM) is employed to compute the ground state and excited state solutions of spin-1 Bose-Einstein condensates (BEC). The BEC is governed by the time-independent coupled Gross-Pitaevskii equations (GPE) under the conservations of the mass and magnetization. The coupling constants that characterize the spin-independent and spin-exchange interactions are chosen as the continuation parameters. The continuation curve starts from a ground state or an excited state with very small coupling parameters. The proposed numerical schemes allow us to investigate the effect of the coupling constants and study the bifurcation diagrams of the time-independent coupled GPE. Numerical results on the wave functions and their corresponding energies of spin-1 BEC with repulsive/attractive and ferromagnetic/antiferromagnetic interactions are presented. Furthermore, we reveal that the component separation and population transfer between the different hyperfine states can only occur in excited states due to the spin-exchange interactions.

  5. 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.

  6. Symmetry and Bulk-Edge Correspondence in the Dimerized Spin-1/2 Heisenberg Ladder with External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kariyado, Toshikaze; Hatsugai, Yasuhiro

    2015-03-01

    The dimerized spin-1/2 Heisenberg ladder is topologically characterized from the viewpoints of symmetry protection and bulk-edge correspondence. Our focus is on the plateau phase at the half of the saturation induced by dimerization and magnetic field. The Berry phase associated with the twisted boundary condition is employed as a topological order parameter. The magnetic field reduces the symmetry of the system, but there is a topological phase protected by a spatial inversion symmetry that is characterized by a Berry phase quantized to 0/ π. For a Berry phase quantization, usage of a symmetry-preserving boundary, which leaves at least one inversion center after the system is cut at the boundary, is essential. As a comparison, a symmetry-breaking boundary is also analyzed. Naively, such a boundary is inadequate to make the Berry phase quantized and topological. However, for a specific type of boundary, we found a unique quantization of the Berry phase into +/- π / 2 , instead of 0/ π [1]. Further, for the case of +/- π / 2 -quantization, there appears an edge state distinct from the one for the 0/ π-quantization, which reveals new aspects of the bulk-edge correspondence for symmetry-breaking boundary.

  7. Decorated Shastry-Sutherland lattice in the spin-(1)/(2) magnet CdCu2(BO3)2

    NASA Astrophysics Data System (ADS)

    Janson, O.; Rousochatzakis, I.; Tsirlin, A. A.; Richter, J.; Skourski, Yu.; Rosner, H.

    2012-02-01

    We report the microscopic magnetic model for the spin-1/2 Heisenberg system CdCu2(BO3)2, one of the few quantum magnets showing the 1/2-magnetization plateau. Recent neutron diffraction experiments on this compound [M. Hase , Phys. Rev. BPLRBAQ0556-280510.1103/PhysRevB.80.104405 80, 104405 (2009)] evidenced long-range magnetic order, inconsistent with the previously suggested phenomenological magnetic model of isolated dimers and spin chains. Based on extensive density functional theory band structure calculations, exact diagonalizations, quantum Monte Carlo simulations, third-order perturbation theory as well as high-field magnetization measurements, we find that the magnetic properties of CdCu2(BO3)2 are accounted for by a frustrated quasi-2D magnetic model featuring four inequivalent exchange couplings: the leading antiferromagnetic coupling Jd within the structural Cu2O6 dimers, two interdimer couplings Jt1 and Jt2, forming magnetic tetramers, and a ferromagnetic coupling Jit between the tetramers. Based on comparison to the experimental data, we evaluate the ratios of the leading couplings Jd : Jt1 : Jt2 : Jit = 1 : 0.20 : 0.45 : -0.30, with Jd of about 178 K. The inequivalence of Jt1 and Jt2 largely lifts the frustration and triggers long-range antiferromagnetic ordering. The proposed model accounts correctly for the different magnetic moments localized on structurally inequivalent Cu atoms in the ground-state magnetic configuration. We extensively analyze the magnetic properties of this model, including a detailed description of the magnetically ordered ground state and its evolution in magnetic field with particular emphasis on the 1/2-magnetization plateau. Our results establish remarkable analogies to the Shastry-Sutherland model of SrCu2(BO3)2, and characterize the closely related CdCu2(BO3)2 as a material realization for the spin-1/2 decorated anisotropic Shastry-Sutherland lattice.

  8. Thermal entanglement of a spin-1/2 Ising-Heisenberg model on a symmetrical diamond chain.

    PubMed

    Ananikian, N S; Ananikyan, L N; Chakhmakhchyan, L A; Rojas, Onofre

    2012-06-27

    The entanglement quantum properties of a spin-1/2 Ising-Heisenberg model on a symmetrical diamond chain were analyzed. Due to the separable nature of the Ising-type exchange interactions between neighboring Heisenberg dimers, calculation of the entanglement can be performed exactly for each individual dimer. Pairwise thermal entanglement was studied in terms of the isotropic Ising-Heisenberg model and analytical expressions for the concurrence (as a measure of bipartite entanglement) were obtained. The effects of external magnetic field H and next-nearest neighbor interaction J(m) between nodal Ising sites were considered. The ground state structure and entanglement properties of the system were studied in a wide range of coupling constant values. Various regimes with different values of ground state entanglement were revealed, depending on the relation between competing interaction strengths. Finally, some novel effects, such as the two-peak behavior of concurrence versus temperature and coexistence of phases with different values of magnetic entanglement, were observed.

  9. 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.

  10. Magnetization Process and Magnetocaloric Effect of the Spin-1/2 XXZ Heisenberg Cuboctahedron

    NASA Astrophysics Data System (ADS)

    Karľová, Katarína; Strečka, Jozef

    2016-10-01

    Magnetic properties of the spin-1/2 XXZ Heisenberg cuboctahedron are examined using exact numerical diagonalization depending on a relative strength of the exchange anisotropy. While the Ising cuboctahedron exhibits in a low-temperature magnetization curve only one-third magnetization plateau, the XXZ Heisenberg cuboctahedron displays another four intermediate plateaux at zero, one-sixth, one-half and two-thirds of the saturation magnetization. The novel magnetization plateaux generally extend over a wider range of magnetic fields with increasing of a quantum (xy) part of the XXZ exchange interaction. It is shown that the XXZ Heisenberg cuboctahedron exhibits in the vicinity of all magnetization jumps anomalous thermodynamic behavior accompanied by an enhanced magnetocaloric effect.

  11. Interspecies singlet pairing in a mixture of two spin-1 Bose condensates

    SciTech Connect

    Zhang Jie; Li Tiantian; Zhang Yunbo

    2011-02-15

    We study the ground-state properties of a mixture formed by two spin-1 condensates in the absence of an external magnetic field. As the collisional symmetry between interspecies bosonic atoms is broken, the interspecies coupling interaction ({beta}) and interspecies singlet-pairing interaction ({gamma}) arise. The ground state can be calculated using the angular momentum theory analytically for {gamma}=0. The full quantum approach of exact diagonalization is adopted numerically to consider the more general case as {gamma}{ne}0. We illustrate the competition between the two interspecies interactions and find that as singlet-pairing interaction dominates (or the total spin vanishes), there are still different types of singlet formations which are well determined by {beta}.

  12. Thermodynamics of a spin-1/2 XYZ Heisenberg chain with a Dzyaloshinskii-Moriya interaction

    NASA Astrophysics Data System (ADS)

    Xi, Bin; Hu, Shijie; Luo, Qiang; Zhao, Jize; Wang, Xiaoqun

    2017-01-01

    We study the thermodynamics of a spin-1/2 XYZ Heisenberg chain with a Dzyaloshinskii-Moriya interaction. This model describes the low-energy behaviors of a one-dimensional two-component bosonic model with a synthetic spin-orbit coupling in the deep insulating region. In the limit U'/U →∞ , where U is the strength of the onsite intracomponent repulsion and U' is the intercomponent one, we solve our model exactly by Jordan-Wigner transformation, and thus provide a benchmark for our following numerical approach. In other cases, we calculate the entropy and the specific heat numerically by the transfer-matrix renormalization-group method. Their low-temperature behaviors depend crucially on the properties of the zero-temperature phases. A refined ground-state phase diagram is then deduced from their low-temperature behaviors. Our findings offer an alternative way to detect those distinguishable phases experimentally.

  13. 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.

  14. Magnetic and Superfluid Transitions in the One-Dimensional Spin-1 Boson Hubbard Model

    SciTech Connect

    Batrouni, G. G.; Rousseau, V. G.; Scalettar, R. T.

    2009-04-10

    Recent progress in experiments on trapped ultracold atoms has made it possible to study the interplay between magnetism and superfluid-insulator transitions in the boson Hubbard model. We report on quantum Monte Carlo simulations of the spin-1 boson Hubbard model in the ground state. For antiferromagnetic interactions favoring singlets, we present exact numerical evidence that the superfluid-insulator transition is first (second) order for even (odd) Mott lobes. Inside even lobes, we search for nematic-to-singlet first order transitions. In the ferromagnetic case where transitions are all continuous, we map the phase diagram and show the superfluid to be ferromagnetic. We compare the quantum Monte Carlo phase diagram with a third order perturbation calculation.

  15. Exact steady state manifold of a boundary driven spin-1 Lai-Sutherland chain

    NASA Astrophysics Data System (ADS)

    Ilievski, Enej; Prosen, Tomaž

    2014-05-01

    We present an explicit construction of a family of steady state density matrices for an open integrable spin-1 chain with bilinear and biquadratic interactions, also known as the Lai-Sutherland model, driven far from equilibrium by means of two oppositely polarizing Markovian dissipation channels localized at the boundary. The steady state solution exhibits n+1 fold degeneracy, for a chain of length n, due to existence of (strong) Liouvillian U(1) symmetry. The latter can be exploited to introduce a chemical potential and define a grand canonical nonequilibrium steady state ensemble. The matrix product form of the solution entails an infinitely-dimensional representation of a non-trivial Lie algebra (semidirect product of sl2 and a non-nilpotent radical) and hints to a novel Yang-Baxter integrability structure.

  16. Compression of Hamiltonian matrix: Application to spin-1/2 Heisenberg square lattice

    NASA Astrophysics Data System (ADS)

    Choi, Seongsoo; Kim, Woohyun; Kim, Jongho

    2016-09-01

    We introduce a simple algorithm providing a compressed representation (∈ℝNorbits×Norbits×ℕNorbits ) of an irreducible Hamiltonian matrix (number of magnons M constrained, dimension: N/spins!M ! (N spins-M ) ! >Norbits ) of the spin-1/2 Heisenberg antiferromagnet on the L ×L non-periodic lattice, not looking for a good basis. As L increases, the ratio of the matrix dimension to Norbits converges to 8 (order of the symmetry group of square) for the exact ground state computation. The sparsity of the Hamiltonian is retained in the compressed representation. Thus, the computational time and memory consumptions are reduced in proportion to the ratio.

  17. 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.

  18. 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.

  19. Gaussian phase transition and critical exponents in spin-1 bond-alternative Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Su, Yao Heng; Chen, Ai Min; Xiang, Chunhuan; Wang, Honglei; Xia, Cai-Juan; Wang, Jun

    2016-12-01

    The quantum Gaussian phase transition is investigated for the infinite spin-1 bond-alternative Heisenberg model in one spatial dimension. By using a tensor network representation with an infinite matrix product state approach, the ground state energy, bipartite entanglement entropy, non-local string order, and fidelity per lattice site are calculated to characterize the phase transition. At the quantum phase transition point, the scaling behavior of various physical observables with respect to the finite truncation dimension are discussed for the ground state wavefunctions. In addition, the central charge is extracted from the finite entanglement entropies and the finite correlation lengths. Furthermore, the various critical exponents of the string order are calculated. The characteristic critical exponents and the central charge determine the universality class of the phase transition.

  20. 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).

  1. First-order transition and tricritical behavior of the transverse crystal field spin-1 Ising model

    NASA Astrophysics Data System (ADS)

    Costabile, Emanuel; Viana, J. Roberto; de Sousa, J. Ricardo; de Arruda, Alberto S.

    2015-06-01

    The phase diagram of the spin-1 Ising model in the presence of a transverse crystal-field anisotropy (Dx) is studied within the framework of an effective-field theory with correlation. The effect of the coordination number (z) on the phase diagram in the T -Dx plane is investigated. We observe only second-order transitions for coordination number z < 7, while that for z ≥ 7 we have first- and second-order transitions, with the presence of two tricritical points. The lower tricritical temperature (Tt) decreases monotonically with the increasing value of z, and in the limit of z → ∞ we found Tt = 0, corresponding to the mean-field solution [Ricardo de Sousa and Branco, Phys. Rev. E 77 (2008) 012104] with a single tricritical point in the phase diagram.

  2. Face-to-face interaction of multisolitons in spin-1/2 quantum plasma

    NASA Astrophysics Data System (ADS)

    Roy, Kaushik; Choudhury, Sourav; Chatterjee, Prasanta; Wong, C. S.

    2017-01-01

    We investigate the face-to-face collision between multisolitons in spin-1/2 quantum plasma. It is studied in the framework of the model proposed by Marklund et al in Phys. Rev. E 76, 067401 (2007). This study is done with the help of the extended Poincare-Lighthill-Kno (PLK) method. The extended PLK method is also used to obtain two Korteweg-de Vries (KdV) equations and the phase shifts and trajectories during the head-on collision of multisolitons. The collision-induced phase shifts (trajectory changes) are also obtained. The effects of the Zeeman energy, total mass density of the charged plasma particles, speed of the wave and the ratio of the sound speed to Alfvén speed on the phase shifts are studied. It is observed that the phase shifts are significantly affected by all these parameters.

  3. 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

  4. Enhanced magnetocaloric effect in the proximity of magnetization steps and jumps of spin-1/2 XXZ Heisenberg regular polyhedra

    NASA Astrophysics Data System (ADS)

    KarǏová, Katarína; Strečka, Jozef; Richter, Johannes

    2017-03-01

    The magnetization process and adiabatic demagnetization of antiferromagnetic spin-1/2 XXZ Heisenberg clusters in the shape of regular polyhedra (tetrahedron, octahedron, cube, icosahedron and dodecahedron) are examined using the exact diagonalization method. It is demonstrated that a quantum (xy) part of the XXZ exchange interaction is a primary cause for the presence of additional intermediate magnetization plateaux and steps, which are totally absent in the limiting Ising case. The only exception to this rule is the spin-1/2 XXZ Heisenberg tetrahedron, which shows just a quantitative shift of the level-crossing fields related to two magnetization steps. It is shown that spin-1/2 XXZ Heisenberg regular polyhedra exhibit an enhanced magnetocaloric effect in the proximity of magnetization steps and jumps, which are accompanied with a rapid drop (rise) of temperature just above (below) the level-crossing field when the magnetic field is removed adiabatically.

  5. Enhanced magnetocaloric effect in the proximity of magnetization steps and jumps of spin-1/2 XXZ Heisenberg regular polyhedra.

    PubMed

    KarǏová, Katarína; Strečka, Jozef; Richter, Johannes

    2017-03-29

    The magnetization process and adiabatic demagnetization of antiferromagnetic spin-1/2 XXZ Heisenberg clusters in the shape of regular polyhedra (tetrahedron, octahedron, cube, icosahedron and dodecahedron) are examined using the exact diagonalization method. It is demonstrated that a quantum (xy) part of the XXZ exchange interaction is a primary cause for the presence of additional intermediate magnetization plateaux and steps, which are totally absent in the limiting Ising case. The only exception to this rule is the spin-1/2 XXZ Heisenberg tetrahedron, which shows just a quantitative shift of the level-crossing fields related to two magnetization steps. It is shown that spin-1/2 XXZ Heisenberg regular polyhedra exhibit an enhanced magnetocaloric effect in the proximity of magnetization steps and jumps, which are accompanied with a rapid drop (rise) of temperature just above (below) the level-crossing field when the magnetic field is removed adiabatically.

  6. Critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field.

    PubMed

    Dias, D A; Xavier, J C; Plascak, J A

    2017-01-01

    The phase diagram and the critical behavior of the spin-1 and the spin-3/2 two-dimensional Baxter-Wu model in a crystal field are studied by conventional finite-size scaling and conformal invariance theory. The phase diagram of this model, for the spin-1 case, is qualitatively the same as those of the diluted 4-states Potts model and the spin-1 Blume-Capel model. However, for the present case, instead of a tricritical point one has a pentacritical point for a finite value of the crystal field, in disagreement with previous work based on finite-size calculations. On the other hand, for the spin-3/2 case, the phase diagram is much richer and can present, besides a pentacritical point, an additional multicritical end point. Our results also support that the universality class of the critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field is the same as the pure Baxter-Wu model, even at the multicritical points.

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

    NASA Astrophysics Data System (ADS)

    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 Na23 and Rb87 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.

  8. Critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field

    NASA Astrophysics Data System (ADS)

    Dias, D. A.; Xavier, J. C.; Plascak, J. A.

    2017-01-01

    The phase diagram and the critical behavior of the spin-1 and the spin-3/2 two-dimensional Baxter-Wu model in a crystal field are studied by conventional finite-size scaling and conformal invariance theory. The phase diagram of this model, for the spin-1 case, is qualitatively the same as those of the diluted 4-states Potts model and the spin-1 Blume-Capel model. However, for the present case, instead of a tricritical point one has a pentacritical point for a finite value of the crystal field, in disagreement with previous work based on finite-size calculations. On the other hand, for the spin-3/2 case, the phase diagram is much richer and can present, besides a pentacritical point, an additional multicritical end point. Our results also support that the universality class of the critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field is the same as the pure Baxter-Wu model, even at the multicritical points.

  9. Development of a polarized 31Mg+ beam as a spin-1/2 probe for BNMR

    NASA Astrophysics Data System (ADS)

    Levy, C. D. P.; Pearson, M. R.; Dehn, M. H.; Karner, V. L.; Kiefl, R. F.; Lassen, J.; Li, R.; MacFarlane, W. A.; McFadden, R. M. L.; Morris, G. D.; Stachura, M.; Teigelhöfer, A.; Voss, A.

    2016-12-01

    A 28 keV beam of 31Mg+ ions was extracted from a uranium carbide, proton-beam-irradiated target coupled to a laser ion source. The ion beam was nuclear-spin polarized by collinear optical pumping on the 2it {S}_{1/2}-2it {P}_{1/2} transition at 280 nm. The polarization was preserved by an extended 1 mT guide field as the beam was transported via electrostatic bends into a 2.5 T longitudinal magnetic field. There the beam was implanted into a single crystal MgO target and the beta decay asymmetry was measured. Both hyperfine ground states were optically pumped with a single frequency light source, using segmentation of the beam energy, which boosted the polarization by approximately 50 % compared to pumping a single ground state. The total decay asymmetry of 0.06 and beam intensity were sufficient to provide a useful spin-1/2 beam for future BNMR experiments. A variant of the method was used previously to optically pump the full Doppler-broadened absorption profile of a beam of 11Be+ with a single-frequency light source.

  10. 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).

  11. 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.

  12. Keldysh effective action theory for universal physics in spin-(1)/(2) Kondo dots

    NASA Astrophysics Data System (ADS)

    Smirnov, Sergey; Grifoni, Milena

    2013-03-01

    We present a theory for the Kondo spin-(1)/(2) effect in strongly correlated quantum dots. The theory is applicable at any temperature and voltage. It is based on a quadratic Keldysh effective action parametrized by a universal function. We provide a general analytical form for the tunneling density of states through this universal function for which we propose a simple microscopic model. We apply our theory to the highly asymmetric Anderson model with U=∞ and describe its strong-coupling limit, weak-coupling limit, and crossover region within a single analytical expression. We compare our results with a numerical renormalization group in equilibrium and with a real-time renormalization group out of equilibrium and show that the universal shapes of the linear and differential conductance obtained in our theory and in these theories are very close to each other in a wide range of temperatures and voltages. In particular, as in the real-time renormalization group, we predict that at the Kondo voltage the differential conductance is equal to 2/3 of its maximum.

  13. 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.

  14. 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.

  15. Nonautonomous matter waves in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Shen, Yu-Jia; Gao, Yi-Tian; Zuo, Da-Wei; Sun, Yu-Hao; Feng, Yu-Jie; Xue, Long

    2014-06-01

    To investigate nonautonomous matter waves with time-dependent modulation in a one-dimensional trapped spin-1 Bose-Einstein condensate, we hereby work on the generalized three-coupled Gross-Pitaevskii equations by means of the Hirota bilinear method. By modulating the external trap potential, atom gain or loss, and coupling coefficients, we can obtain several nonautonomous matter-wave solitons and rogue waves including "bright" and "dark" shapes and arrive at the following conclusions: (i) the external trap potential and atom gain or loss can influence the propagation of matter-wave solitons and the duration and frequency of bound solitonic interaction, but they have little effect on the head-on solitonic interaction; (ii) through numerical simulation, stable evolution of the matter-wave solitons is realized with a perturbation of 5% initial random noise, and the spin-exchange interaction of atoms can be affected by the time-dependent modulation; (iii) under the influence of a periodically modulated trap potential and periodic atom gain or loss, rogue waves can emerge in the superposition of localized character and periodic oscillating properties.

  16. Nonautonomous matter waves in a spin-1 Bose-Einstein condensate.

    PubMed

    Shen, Yu-Jia; Gao, Yi-Tian; Zuo, Da-Wei; Sun, Yu-Hao; Feng, Yu-Jie; Xue, Long

    2014-06-01

    To investigate nonautonomous matter waves with time-dependent modulation in a one-dimensional trapped spin-1 Bose-Einstein condensate, we hereby work on the generalized three-coupled Gross-Pitaevskii equations by means of the Hirota bilinear method. By modulating the external trap potential, atom gain or loss, and coupling coefficients, we can obtain several nonautonomous matter-wave solitons and rogue waves including "bright" and "dark" shapes and arrive at the following conclusions: (i) the external trap potential and atom gain or loss can influence the propagation of matter-wave solitons and the duration and frequency of bound solitonic interaction, but they have little effect on the head-on solitonic interaction; (ii) through numerical simulation, stable evolution of the matter-wave solitons is realized with a perturbation of 5% initial random noise, and the spin-exchange interaction of atoms can be affected by the time-dependent modulation; (iii) under the influence of a periodically modulated trap potential and periodic atom gain or loss, rogue waves can emerge in the superposition of localized character and periodic oscillating properties.

  17. 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).

  18. Vortex-bright solitons in a spin-orbit-coupled spin-1 condensate

    NASA Astrophysics Data System (ADS)

    Gautam, Sandeep; Adhikari, S. K.

    2017-01-01

    We study the vortex-bright solitons in a quasi-two-dimensional spin-orbit-coupled (SO-coupled) hyperfine spin-1 three-component Bose-Einstein condensate using variational method and numerical solution of a mean-field model. The ground state of these vortex-bright solitons is radially symmetric for weak ferromagnetic and polar interactions. For a sufficiently strong ferromagnetic interaction, we observe the emergence of an asymmetric vortex-bright soliton as the ground state. We also numerically investigate stable moving solitons and binary collision between them. The present mean-field model is not Galilean invariant, and we use a Galilean-transformed model for generating the moving solitons. At low velocities, the head-on collision between two in-phase solitons results either in collapse or fusion of the soliton pair. On the other hand, in head-on collision, the two out-of-phase solitons strongly repel each other and trace back their trajectories before the actual collision. At low velocities, in a collision with an impact parameter, the out-of-phase solitons get deflected from their original trajectory like two rigid classical disks. These out-of-phase solitons behave like classical disks, and their collision dynamics is governed by classical laws of motion. However, at large velocities two SO-coupled spinor solitons, irrespective of phase difference, can pass through each other in a head-on collision like two quantum solitons.

  19. Barlowite: A Spin-1/2 Antiferromagnet with a Geometrically Perfect Kagome Motif.

    PubMed

    Han, Tian-Heng; Singleton, John; Schlueter, John A

    2014-11-28

    We present thermodynamic studies of a new spin-1/2 antiferromagnet containing undistorted kagome lattices-barlowite Cu_{4}(OH)_{6}FBr. Magnetic susceptibility gives θ_{CW}=-136  K, while long-range order does not happen until T_{N}=15  K with a weak ferromagnetic moment μ<0.1μ_{B}/Cu. A 60 T magnetic field induces a moment less than 0.5μ_{B}/Cu at T=0.6  K. Specific-heat measurements have observed multiple phase transitions at T≪∣θ_{CW}∣. The magnetic entropy of these transitions is merely 18% of k_{B}ln2 per Cu spin. These observations suggest that nontrivial spin textures are realized in barlowite with magnetic frustration. Comparing with the leading spin-liquid candidate herbertsmithite, the superior interkagome environment of barlowite sheds light on new spin-liquid compounds with minimum disorder. The robust perfect geometry of the kagome lattice makes charge doping promising.

  20. Lepton electric and magnetic dipole moments via lepton flavor-violating spin-1 unparticle interactions

    SciTech Connect

    Moyotl, A.; Rosado, A.; Tavares-Velasco, G.

    2011-10-01

    The magnetic dipole moment and the electric dipole moment of leptons are calculated under the assumption of lepton flavor violation (LFV) induced by spin-1 unparticles with both vector and axial-vector couplings to leptons, including a CP-violating phase. The experimental limits on the muon magnetic dipole moment and LFV process, such as the decay l{sub i}{sup -}{yields}l{sub j}{sup -}l{sub k}{sup -}l{sub k}{sup +}, are then used to constrain the LFV couplings for particular values of the unparticle operator dimension d{sub U} and the unparticle scale {Lambda}{sub U}, assuming that LFV transitions between the tau and muon leptons are dominant. It is found that the current experimental constraints favor a scenario with dominance of the vector couplings over the axial-vector couplings. We also obtain estimates for the electric dipole moments of the electron and the muon, which are well below the experimental values.

  1. Dynamical properties of the one-dimensional spin-1/2 Bose-Hubbard model near a Mott-insulator to ferromagnetic-liquid transition.

    PubMed

    Zvonarev, M B; Cheianov, V V; Giamarchi, T

    2009-09-11

    We investigate the dynamics of the one-dimensional strongly repulsive spin-1/2 Bose-Hubbard model for filling nu system is a Hubbard-Mott insulator exhibiting dynamical properties of the Heisenberg ferromagnet, at nu<1 it is a ferromagnetic liquid with complex spin dynamics. We find that close to the insulator-liquid transition the system admits for a complete separation of spin and density degrees of freedom valid at all energy and momentum scales within the t-J approximation. This allows us to derive the propagator of transverse spin waves and the shape of the magnon peak in the dynamic spin structure factor.

  2. 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.

    PubMed

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

  3. 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.

  4. Determining the exchange parameters of spin-1 metal-organic molecular magnets in pulsed magnetic fields

    SciTech Connect

    Mcdonald, Ross D; Singleton, John; Lancaster, Tom; Goddard, Paul; Manson, Jamie

    2011-01-14

    We nave measured the high-field magnetization of a number of Ni-based metal-organic molecular magnets. These materials are self-assembly coordination polymers formed from transition metal ions and organic ligands. The chemistry of the compounds is versatile allowing many structures with different magnetic properties to be formed. These studies follow on from previous measurements of the Cu-based analogues in which we showed it was possible to extract the exchange parameters of low-dimensional magnets using pulsed magnetic fields. In our recent experiments we have investigated the compound (Ni(HF{sub 2})(pyz){sub 2})PF{sub 6}, where pyz = pyrazine, and the Ni-ions are linked in a quasi-two-dimensional (Q2D) square lattice via the pyrazine molecules, with the layers held together by HF{sub 2} ligands. We also investigated Ni(NCS){sub 2}(pyzdo){sub 2}, where pyzdo = pyrazine dioxide. The samples are grown at Eastern Washington University using techniques described elsewhere. Measurements are performed at the pulsed magnetic field laboratory in Los Alamos. The magnetization of powdered samples is determined using a compensated coil magnetometer in a 65 T short pulse magnet. Temperatures as low as 500 mK are achievable using a {sup 3}He cryostat. The main figure shows the magnetization of the spin-1 [Ni(HF{sub 2})(pyz){sub 2}]PF{sub 6} compound at 1.43 K. The magnetization rises slowly at first, achieving a rounded saturation whose midpoint is around 19 T. A small anomaly is also seen in the susceptibility at low fields ({approx}3 T), which might be attributed to a spin-flop transition. In contrast, the spin-1/2 [Cu(HF{sub 2})(pyz){sub 2}]PF{sub 6} measured previously has a saturation magnetization of 35.5 T and a strongly concave form of M(B) below this field. This latter compound was shown to be a good example of a Q2D Heisenberg antiferromagnet with the strong exchange coupling (J{sub 2D} = 12.4 K, J{sub {perpendicular}}/J{sub 2D} {approx} 10{sup -2}) directed along

  5. Time minimal trajectories for a spin 1/2 particle in a magnetic field

    NASA Astrophysics Data System (ADS)

    Boscain, Ugo; Mason, Paolo

    2006-06-01

    In this paper we consider the minimum time population transfer problem for the z component of the spin of a (spin 1/2) particle, driven by a magnetic field, that is constant along the z axis and controlled along the x axis, with bounded amplitude. On the Bloch sphere (i.e., after a suitable Hopf projection), this problem can be attacked with techniques of optimal syntheses on two-dimensional (2-D) manifolds. Let (-E,E) be the two energy levels, and ∣Ω(t)∣≤M the bound on the field amplitude. For each couple of values E and M, we determine the time optimal synthesis starting from the level -E, and we provide the explicit expression of the time optimal trajectories, steering the state one to the state two, in terms of a parameter that can be computed solving numerically a suitable equation. For M /E≪1, every time optimal trajectory is bang-bang and, in particular, the corresponding control is periodic with frequency of the order of the resonance frequency ωR=2E. On the other side, for M /E>1, the time optimal trajectory steering the state one to the state two is bang-bang with exactly one switching. For fixed E, we also prove that for M →∞ the time needed to reach the state two tends to zero. In the case M /E>1 there are time optimal trajectories containing a singular arc. Finally, we compare these results with some known results of Khaneja, Brockett, and Glaser and with those obtained by controlling the magnetic field both on the x and y directions (or with one external field, but in the rotating wave approximation). As a byproduct we prove that the qualitative shape of the time optimal synthesis presents different patterns that cyclically alternate as M /E→0, giving a partial proof of a conjecture formulated in a previous paper.

  6. Vector-spin-chirality order in a dimerized frustrated spin-1/2 chain

    NASA Astrophysics Data System (ADS)

    Ueda, Hiroshi; Onoda, Shigeki

    2014-01-01

    A frustrated spin-1/2 XXZ chain model comprising a ferromagnetic nearest-neighbor coupling with the bond alternation, J1(1±δ)<0, and an antiferromagnetic second-neighbor exchange coupling J2>0 is studied at zero and weak magnetic fields by means of density-matrix renormalization-group calculations of order parameters, correlation functions, and the entanglement entropy, as well as an Abelian bosonization analysis. At zero magnetic field, the bond alternation δ >0 suppresses the gapless phase characterized by a vector-chiral (VC) long-range order (LRO) and a quasi-LRO of an incommensurate spin spiral, whereas this phase occupies a large region in the space of J1/J2 and the easy-plane exchange anisotropy for δ =0 [S. Furukawa et al., Phys. Rev. Lett. 105, 257205 (2010), 10.1103/PhysRevLett.105.257205]. Then, four gapped phases are found to appear as the exchange anisotropy varies from the SU(2)-symmetric case to the U(1)-symmetric case: the Haldane dimer (D+) phase with the same sign of the x ,y- and z-component dimer order parameters, two VC dimer (VCD+/VCD-) phases with the sign of the z-component dimer order parameter being unaltered/reversed, and the even-parity dimer (D-) phase. At small magnetic fields, a field-induced ring-exchange interaction, which is proportional to a staggered scalar chirality and a magnetic flux penetrating the associated triangle, drives a transition from the D- phase into a VC-Neel-dimer (VCND) phase, but not from the D+ phase. This VCND phase is stable up to the large magnetic field at which the Zeeman term closes the spin gap. A possible relevance to Rb2Cu2Mo3O12 is discussed.

  7. 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.

  8. Preserving coherent spin and squeezed spin states of a spin-1 Bose-Einstein condensate with rotary echoes

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Han, Yingying; Xu, Peng; Zhang, Wenxian

    2016-11-01

    A challenge in precision measurement with squeezed spin state arises from the spin dephasing due to stray magnetic fields. To suppress such environmental noises, we employ a continuous driving protocol, rotary echo, to enhance the spin coherence of a spin-1 Bose-Einstein condensate in stray magnetic fields. Our analytical and numerical results show that the coherent and the squeezed spin states are preserved for a significantly long time, compared to the free induction decay time, if the condition h τ =m π is met with h the pulse amplitude and τ pulse width. In particular, both the spin average and the spin squeezing, including the direction and the amplitude, are simultaneously fixed for a squeezed spin state. Our results point out a practical way to implement quantum measurements based on a spin-1 condensate beyond the standard quantum limit.

  9. Origin of the positive spin-1/2 photoluminescence-detected magnetic resonance in π-conjugated materials and devices

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Cai, Min; Hellerich, Emily; Shinar, Ruth; Shinar, Joseph

    2015-09-01

    The spin-1 /2 single-modulation (SM) and double-modulation (DM) photoluminescence (PL) detected magnetic resonance (PLDMR) in poly(2-methoxy-5-(2'-ethyl)-hexoxy-1,4- phenylene vinylene) (MEH-PPV) films and poly(3-hexylthiophene) (P3HT) films is described, analyzed, and discussed. In particular, the models based on spin-dependent recombination of charge pairs (SDR) and triplet-polaron quenching (TPQ) are evaluated. By analyzing the dependence of the resonance amplitude on the microwave chopping (modulation) frequency using rate equations, it is demonstrated that the TPQ model can well explain the observed resonance behavior, while SDR model cannot reproduce the results of the observed DM-PLDMR. Thus the observed spin-1 /2 PLDMR is assigned to TPQ rather than SDR, even though the latter may also be present.

  10. Scattering of spin 1/2 particles by the 2+1 dimensional noncommutative Aharonov-Bohm potential

    SciTech Connect

    Ferrari, A. F.; Gomes, M.; Stechhahn, C. A.

    2007-10-15

    In this work we study modifications in the Aharonov-Bohm effect for relativistic spin 1/2 particles due to the noncommutativity of spacetime in 2+1 dimensions. The noncommutativity gives rise to a correction to the Aharonov-Bohm potential which is highly singular at the origin, producing divergences in a perturbative expansion around the usual solution of the free Dirac equation. This problem is surmounted by using a perturbative expansion around the exact solution of the commutative Aharonov-Bohm problem. We calculate, in this setting, the scattering amplitude and the corrections to the differential and total cross sections for a spin 1/2 particle, in the small-flux limit.

  11. Characterization of Topological Phases of Spin-1/2 Frustrated Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chains by Entanglement Spectrum

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2016-02-01

    The topological classification of a series of frustration-induced spin-gap phases in the spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain with next-nearest-neighbour interaction reported in J. Phys. Soc. Jpn. 82, 064703 (2013) is confirmed using two kinds of entanglement spectra defined by different divisions of the whole chain. For the numerical calculation, the iDMRG method is used. The results are consistent with the valence bond solid picture proposed in the previous paper.

  12. The effective action of a spin 1/2 field in the background of a nontopological soliton

    NASA Astrophysics Data System (ADS)

    Baacke, J.

    1990-12-01

    We generalize a new method of calculating the effective action for fields in a spherically symmetric background to the case of a spin 1/2 field whose mass is a function of r=| x|, as it is the case in the nontopological soliton model of Friedberg and Lee. The quantum corrections to the soliton energy are sizeable, of the same order as the bound state energies that stabilize the soliton.

  13. Quantum amplitudes in black-hole evaporation: Spins 1 and 2

    NASA Astrophysics Data System (ADS)

    Farley, A. N. St. J.; D'Eath, P. D.

    2006-06-01

    Quantum amplitudes for s = 1 Maxwell fields and for s = 2 linearised gravitational-wave perturbations of a spherically symmetric Einstein/massless scalar background, describing gravitational collapse to a black hole, are treated by analogy with the previous treatment of s = 0 scalar-field perturbations of gravitational collapse at late times. Both the spin-1 and the spin-2 perturbations split into parts with odd and even parity. Their detailed angular behaviour is analysed, as well as their behaviour under infinitesimal coordinate transformations and their linearised field equations. In general, we work in the Regge-Wheeler gauge, except that, at a certain point, it becomes necessary to make a gauge transformation to an asymptotically flat gauge, such that the metric perturbations have the expected fall-off behaviour at large radii. In both the s = 1 and s = 2 cases, we isolate suitable 'coordinate' variables which can be taken as boundary data on a final space-like hypersurface ΣF. (For simplicity of exposition, we take the data on the initial surface ΣI to be exactly spherically symmetric.) The (large) Lorentzian proper-time interval between ΣI and ΣF, measured at spatial infinity, is denoted by T. We then consider the classical boundary-value problem and calculate the second-variation classical Lorentzian action Sclass(2), on the assumption that the time interval T has been rotated into the complex: T → | T| exp (-i θ), for 0 < θ ⩽ π/2. This complexified classical boundary-value problem is expected to be well-posed, in contrast to the boundary-value problem in the Lorentzian-signature case ( θ = 0), which is badly posed, since it refers to hyperbolic or wave-like field equations. Following Feynman, we recover the Lorentzian quantum amplitude by taking the limit as θ → 0 + of the semi-classical amplitude exp(iSclass(2)). The boundary data for s = 1 involve the (Maxwell) magnetic field, while the data for s = 2 involve the magnetic part of the Weyl

  14. Numerical study of magnetization plateaus in the spin-1/2 Heisenberg antiferromagnet on the checkerboard lattice

    NASA Astrophysics Data System (ADS)

    Capponi, Sylvain

    2017-01-01

    We present numerical evidence that the spin-1/2 Heisenberg model on the two-dimensional checkerboard lattice exhibits several magnetization plateaus for m =0 , 1 /4 , 1 /2 , and 3 /4 , where m is the magnetization normalized by its saturation value. These incompressible states correspond to somewhat similar valence-bond crystal phases that break lattice symmetries, though they are different from the already established plaquette phase for m =0 . Our results are based on exact diagonalization as well as density-matrix renormalization-group large-scale simulations and interpreted in terms of simple parameter-free trial wave functions.

  15. The effective action of a spin 1/2 field in the background of a chiral soliton

    NASA Astrophysics Data System (ADS)

    Baacke, J.

    1992-09-01

    We use a recently developed numerical technique in order to evaluate the renormalized effective action of a spin 1/2 field with a chiral mass term, the chiral angle being given by a static hedgehog configuration. The method is based on the use of Euclidean Green's functions. The divergent parts are regularized and renormalized analytically. For the sum over all convergent contributions we obtain an exact expression that can be evaluated numerically. A precarious numerical subtraction of the divergent parts is avoided by making use of integral equations for the partial waves.

  16. Modified Spin Wave Analysis of Low Temperature Properties of the Spin-1/2 Frustrated Ferromagnetic Ladder

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Iino, Takashi

    2012-03-01

    Low temperature properties of the spin-1/2 frustrated ladder with ferromagnetic rungs and legs, and two different antiferromagnetic next nearest neighbor interactions are investigated using the modified spin wave approximation in the region with ferromagnetic ground states. The temperature dependence of the magnetic susceptibility and magnetic structure factors is calculated. The results are consistent with the numerical exact diagonalization results in the intermediate temperature range. Below this temperature range, the finite size effect is significant in the numerical diagonalization results, while the modified spin wave approximation gives more reliable results. The low temperature properties near the limit of the stability of the ferromagnetic ground state are also discussed.

  17. Studies of heteronuclear dipolar interactions between spin-1/2 and quadrupolar nuclei by using REDOR during multiple quantum evolution

    NASA Astrophysics Data System (ADS)

    Pruski, M.; Bailly, A.; Lang, D. P.; Amoureux, J.-P.; Fernandez, C.

    1999-06-01

    A new technique for measurements of dipolar interactions in rotating solids is presented that combines the capabilities of multiple quantum magic angle spinning (MQMAS) with the rotational echo double resonance (REDOR). It employs the dipolar recoupling between spin-1/2 ( I) and quadrupolar ( S) nuclei by applying a series of π pulses to the I spins. In contrast to the previously reported MQ-REDOR method, the recoupling sequence is applied during the triple quantum, rather than single quantum evolution. As the dipolar effect is enhanced by the MQ coherence order, this new technique exhibits improved sensitivity toward weak dipolar interactions.

  18. Time-optimal control of spin 1/2 particles in the presence of radiation damping and relaxation.

    PubMed

    Zhang, Y; Lapert, M; Sugny, D; Braun, M; Glaser, S J

    2011-02-07

    We consider the time-optimal control of an ensemble of uncoupled spin 1/2 particles in the presence of relaxation and radiation damping effects, whose dynamics is governed by nonlinear equations generalizing the standard linear Bloch equations. For a single spin, the optimal control strategy can be fully characterized analytically. However, in order to take into account the inhomogeneity of the static magnetic field, an ensemble of isochromats at different frequencies must be considered. For this case, numerically optimized pulse sequences are computed and the dynamics under the corresponding optimal field is experimentally demonstrated using nuclear magnetic resonance techniques.

  19. Metastable spin textures and Nambu-Goldstone modes of a ferromagnetic spin-1 Bose-Einstein condensate confined in a ring trap

    NASA Astrophysics Data System (ADS)

    Kunimi, Masaya

    2014-12-01

    We investigate the metastability of a ferromagnetic spin-1 Bose-Einstein condensate confined in a quasi-one-dimensional rotating ring trap by solving the spin-1 Gross-Pitaevskii equation. We find analytical solutions that exhibit spin textures. By performing linear stability analysis, it is shown that the solutions can become metastable states. We also find that the number of Nambu-Goldstone modes changes at a certain rotation velocity without changing the continuous symmetry of the order parameter.

  20. Effects of the single-ion anisotropy on magnetic and thermodynamic properties of a ferrimagnetic mixed-spin (1, 3/2) cylindrical Ising nanowire

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bi, Jiang-lin; Liu, Rui-jia; Chen, Xu; Liu, Jin-ping

    2016-10-01

    Monte Carlo simulation has been performed in detail to study magnetic and thermodynamic properties of a ferrimagnetic mixed-spin (1, 3/2) cylindrical Ising nanowire with core-shell structure. The ground phase diagrams are obtained for different single-ion anisotropies. The system can display rich phase transitions such as the second- and first-order phase transitions, the tricritical points and the compensation points. Especially, emphasis has been given to the effects of the single-ion anisotropy and the temperate on the magnetization, the internal energy, the specific heat, the compensation points and hysteresis loops of the system as well as two sublattices. A number of characteristic phenomena such as such as various types of magnetization curves and triple, duadruple as well as quintuple hysteresis loops behaviors have been observed for certain physical parameters, originating from the competitions among the anisotropies, temperature and the longitudinal magnetic field. It is found that the single-ion anisotropy and the temperature strongly affect the coercivity and the remanence of the system. A satisfactory agreement can be achieved from comparisons between our results and previous theoretical and experimental works.

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

    DOE PAGES

    Zvyagin, S. A.; Ozerov, M.; Kamenskyi, D.; ...

    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

  2. The route to magnetic order in the spin-1/2 kagome Heisenberg antiferromagnet: The role of interlayer coupling

    NASA Astrophysics Data System (ADS)

    Götze, Oliver; Richter, Johannes

    2016-06-01

    While the existence of a spin-liquid ground state of the spin-1/2 kagome Heisenberg antiferromagnet (KHAF) is well established, the discussion of the effect of an interlayer coupling (ILC) by controlled theoretical approaches is still lacking. Here we study this problem by using the coupled-cluster method to high orders of approximation. We consider a stacked KHAF with a perpendicular ILC J_\\perp , where we study ferro- as well as antiferromagnetic J_\\perp . We find that the spin-liquid ground state (GS) persists until relatively large strengths of the ILC. Only if the strength of the ILC exceeds about 15% of the intralayer coupling the spin-liquid phase gives way for q = 0 magnetic long-range order, where the transition between both phases is continuous and the critical strength of the ILC, |J^c_\\perp| , is almost independent of the sign of J_\\perp . Thus, by contrast to the quantum GS selection of the strictly two-dimensional KHAF at large spin s, the ILC leads first to a selection of the q = 0 GS. Only at larger |J_\\perp| the ILC drives a first-order transition to the \\sqrt{3}×\\sqrt{3} long-range ordered GS. As a result, the stacked spin-1/2 KHAF exhibits a rich GS phase diagram with two continuous and two discontinuous transitions driven by the ILC.

  3. Field-induced quantum criticality and universal temperature dependence of the magnetization of a spin-1/2 heisenberg chain.

    PubMed

    Kono, Y; Sakakibara, T; Aoyama, C P; Hotta, C; Turnbull, M M; Landee, C P; Takano, Y

    2015-01-23

    High-precision dc magnetization measurements have been made on Cu(C4H4N2) (NO3)2 in magnetic fields up to 14.7 T, slightly above the saturation field Hs=13.97  T, in the temperature range from 0.08 to 15 K. The magnetization curve and differential susceptibility at the lowest temperature show excellent agreement with exact theoretical results for the spin-1/2 Heisenberg antiferromagnet in one dimension. A broad peak is observed in magnetization measured as a function of temperature, signaling a crossover to a low-temperature Tomonaga-Luttinger-liquid regime. With an increasing field, the peak moves gradually to lower temperatures, compressing the regime, and, at Hs, the magnetization exhibits a strong upturn. This quantum critical behavior of the magnetization and that of the specific heat withstand quantitative tests against theory, demonstrating that the material is a practically perfect one-dimensional spin-1/2 Heisenberg antiferromagnet.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Up-up-down-down magnetic chain structure of the spin-1/2 tetragonally distorted spinel GeC u2O4

    NASA Astrophysics Data System (ADS)

    Zou, T.; Cai, Y.-Q.; dela Cruz, C. R.; Garlea, V. O.; Mahanti, S. D.; Cheng, J.-G.; Ke, X.

    2016-12-01

    GeC u2O4 spinel exhibits a tetragonal structure due to the strong Jahn-Teller distortion associated with C u2 + ions. We show that its magnetic structure can be described as slabs composed of a pair of layers with orthogonally oriented spin-1/2 Cu chains in the basal a b plane. The spins between the two layers within a slab are collinearly aligned while the spin directions of neighboring slabs are perpendicular to each other. Interestingly, we find that spins along each chain form an unusual up-up-down-down (UUDD) pattern, suggesting a non-negligible nearest-neighbor biquadratic exchange interaction in the effective classical spin Hamiltonian. We hypothesize that spin-orbit coupling and orbital mixing of C u2 + ions in this system are non-negligible, which calls for future calculations using perturbation theory with extended Hilbert (spin and orbital) space and calculations based on density functional theory including spin-orbit coupling and looking at the global stability of the UUDD state.

  10. 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

  11. 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.

  12. Highly Efficient Polarization of Spin-1/2 Insensitive NMR Nuclei by Adiabatic Passage through Level Anticrossings.

    PubMed

    Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Lukzen, Nikita N; Ivanov, Konstantin L; Vieth, Hans-Martin

    2014-10-02

    A method is proposed to transfer spin order from para-hydrogen, that is, the H2 molecule in its singlet state, to spin-1/2 heteronuclei of a substrate molecule. The method is based on adiabatic passage through nuclear spin level anticrossings (LACs) in the doubly rotating frame of reference; the LAC conditions are fulfilled by applying resonant RF excitation at the NMR frequencies of protons and the heteronuclei. Efficient conversion of the para-hydrogen-induced polarization into net polarization of the heteronuclei is demonstrated; the achieved signal enhancements are about 6400 for (13)C nuclei at natural abundance. The theory behind the technique is described; advantages of the method are discussed in detail.

  13. The magnetic properties of three-dimensional spin-1 easy-axis single-ion anisotropic antiferromagnets

    NASA Astrophysics Data System (ADS)

    Hu, Ai-Yuan; Wang, Qin

    2010-05-01

    The ordered and disordered phases of spin-1 Heisenberg and Ising antiferromagnets with easy-axis single-ion anisotropy on a three-dimensional lattice are studied. By using of the double-time Green's function method within the Tyablikov decoupling for the exchange anisotropy and Callen's approximation for the single-ion anisotropy, the Néel temperature, magnetization and susceptibility are investigated. Their relations with the temperature and anisotropic parameter are analyzed over the entire range of temperature. It is found that our results agree well with spin wave theory results at low temperature, agree with the high temperature series results at high temperature, and compare reasonably well with the linked-cluster series approach and ratio method results at intermediate temperature.

  14. The magnetic properties of one-dimensional spin-1 ferromagnetic Heisenberg model in a magnetic field within Callen approximation

    NASA Astrophysics Data System (ADS)

    Liu, Ming-Wei; Chen, Yuan; Song, Chuang-Chuang; Wu, You; Ding, Hai-Ling

    2011-03-01

    The effect of magnetic field h on the magnetic properties of the one-dimensional spin-1 ferromagnetic Heisenberg model is studied by the double-time Green's function method. The magnetization and susceptibility are obtained within the Callen approximation. The zero-field susceptibility is as a decreasing function of the temperature T. The magnetization m increases in the whole field region, but the susceptibility maximum χ(Tm) decreases. The position Tm of the susceptibility maximum is both solved analytically and fits well to be a power law Tm∼hγ at low fields and to be linear increasing at high fields. The height χ(Tm) decreases as a power law χ(Tm)∼h with h increasing. The exponents (γ,β) obtained in our results agree with the other theoretical results. Our results are roughly in agreement with the results obtained in the experiment of Ni(OH)(NO3)H2O.

  15. Magnetic Signatures of Quantum Critical Points of the Ferrimagnetic Mixed Spin-(1/2, S) Heisenberg Chains at Finite Temperatures

    NASA Astrophysics Data System (ADS)

    Strečka, Jozef; Verkholyak, Taras

    2016-10-01

    Magnetic properties of the ferrimagnetic mixed spin-(1/2,S) Heisenberg chains are examined using quantum Monte Carlo simulations for two different quantum spin numbers S=1 and 3/2. The calculated magnetization curves at finite temperatures are confronted with zero-temperature magnetization data obtained within the density matrix renormalization group method, which imply an existence of two quantum critical points determining a breakdown of the gapped Lieb-Mattis ferrimagnetic phase and Tomonaga-Luttinger spin-liquid phase, respectively. While a square root behavior of the magnetization accompanying each quantum critical point is gradually smoothed upon rising temperature, the susceptibility and isothermal entropy change data at low temperatures provide a stronger evidence of the zero-temperature quantum critical points through marked local maxima and minima, respectively.

  16. Magnetic Raman Scattering in Two-Dimensional Spin-1/2 Heisenberg Antiferromagnets: Explanation of the Spectral Shape Anomaly

    NASA Astrophysics Data System (ADS)

    Nori, F.; Merlin, R.; Haas, S.; Sandvick, A.; Dagotto, E.

    1996-03-01

    We calculate(F. Nori, R.Merlin, S. Haas, A.W. Sandvik, and E. Dagotto, Physical Review Letters) 75, 553 (1995). the Raman spectrum of the two-dimensional (2D) spin-1/2 Heisenberg antiferromagnet by exact diagonalization and quantum Monte Carlo techniques on clusters of up to 144 sites. On a 16-site cluster, we consider the phonon-magnon interaction which leads to random fluctuations of the exchange integral. Results are in good agreement with experiments on various high-Tc precursors, such as La_2CuO4 and YBa_2Cu_3O_6.2. In particular, our calculations reproduce the broad lineshape of the two-magnon peak, the asymmetry about its maximum, the existence of spectral weight at high energies, and the observation of nominally forbidden A_1g scattering.

  17. Geometric frustration effects in the spin-1 antiferromagnetic Ising model on the kagome-like recursive lattice: exact results

    NASA Astrophysics Data System (ADS)

    Jurčišinová, E.; Jurčišin, M.

    2016-09-01

    The antiferromagnetic spin-1 Ising model is studied on the Husimi lattice constructed from elementary triangles with coordination number z  =  4. It is found that the model has a unique solution for arbitrary values of the magnetic field as well as for all temperatures. A detailed analysis of the magnetization is performed and it is shown that in addition to the standard plateau-like ground states, the model also contains well-defined single-point ground states related to definite values of the magnetic field. Exact values of the residual entropies for all ground states are found. The properties of the susceptibility and the specific heat of the model are also discussed. The existence of the Schottky-type behavior of the specific heat and the strong magnetocaloric effect for low enough temperatures and for the external magnetic field close to the values at which the single-point ground states exist are identified.

  18. Numerical methods for computing the ground state of spin-1 Bose-Einstein condensates in a uniform magnetic field.

    PubMed

    Lim, Fong Yin; Bao, Weizhu

    2008-12-01

    We propose efficient and accurate numerical methods for computing the ground-state solution of spin-1 Bose-Einstein condensates subjected to a uniform magnetic field. The key idea in designing the numerical method is based on the normalized gradient flow with the introduction of a third normalization condition, together with two physical constraints on the conservation of total mass and conservation of total magnetization. Different treatments of the Zeeman energy terms are found to yield different numerical accuracies and stabilities. Numerical comparison between different numerical schemes is made, and the best scheme is identified. The numerical scheme is then applied to compute the condensate ground state in a harmonic plus optical lattice potential, and the effect of the periodic potential, in particular to the relative population of each hyperfine component, is investigated through comparison to the condensate ground state in a pure harmonic trap.

  19. 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.

  20. Emergent infinite-randomness fixed points from the extensive random bipartitions of the spin-1 Affleck-Kennedy-Lieb-Tasaki topological state

    NASA Astrophysics Data System (ADS)

    Lu, Min; Rao, Wen-Jia; Narayanan, Rajesh; Wan, Xin; Zhang, Guang-Ming

    2016-12-01

    Quantum entanglement under an extensive bipartition can reveal the critical boundary theory of a topological phase in a parameter space. In this study we demonstrate that the infinite-randomness fixed point for spin-1/2 degrees of freedom can emerge from an extensive random bipartition of the spin-1 Affleck-Kennedy-Lieb-Tasaki chain. The nested entanglement entropy of the ground state of the reduced density matrix exhibits a logarithmic scaling with an effective central charge c ˜=0.72 ±0.02 ≈ln2 . We further discuss, in the language of bulk quantum entanglement, how to understand all phase boundaries and the surrounding Griffiths phases for the antiferromagnetic Heisenberg spin-1 chain with quenched disorder and dimerization.

  1. Generalizing spin and pseudospin symmetries for relativistic spin 1/2 fermions

    NASA Astrophysics Data System (ADS)

    Alberto, P.; Malheiro, M.; Frederico, T.; de Castro, A.

    2016-08-01

    We propose a generalization of pseudospin and spin symmetries, the SU(2) symmetries of Dirac equation with scalar and vector mean-field potentials originally found independently in the 70’s by Smith and Tassie, and Bell and Ruegg. As relativistic symmetries, they have been extensively researched and applied to several physical systems for the last 18 years. The main feature of these symmetries is the suppression of the spin-orbit coupling either in the upper or lower components of the Dirac spinor, thereby turning the respective second-order equations into Schrödinger-like equations, i.e, without a matrix structure. In this paper we use the original formalism of Bell and Ruegg to derive general requirements for the Lorentz structures of potentials in order to have these SU(2) symmetries in the Dirac equation, again allowing for the suppression of the matrix structure of the second-order equation of either the upper or lower components of the Dirac spinor. Furthermore, we derive equivalent conditions for spin and pseudospin symmetries with 2- and 1-dimensional potentials and list some possible candidates for 3, 2, and 1 dimensions. We suggest applications for physical systems in three and two dimensions, namely electrons in graphene.

  2. Absence of high-temperature ballistic transport in the spin-1/2 XXX chain within the grand-canonical ensemble

    NASA Astrophysics Data System (ADS)

    Carmelo, J. M. P.; Prosen, T.

    2017-01-01

    Whether in the thermodynamic limit, vanishing magnetic field h → 0, and nonzero temperature the spin stiffness of the spin-1/2 XXX Heisenberg chain is finite or vanishes within the grand-canonical ensemble remains an unsolved and controversial issue, as different approaches yield contradictory results. Here we provide an upper bound on the stiffness and show that within that ensemble it vanishes for h → 0 in the thermodynamic limit of chain length L → ∞, at high temperatures T → ∞. Our approach uses a representation in terms of the L physical spins 1/2. For all configurations that generate the exact spin-S energy and momentum eigenstates such a configuration involves a number 2S of unpaired spins 1/2 in multiplet configurations and L - 2 S spins 1/2 that are paired within Msp = L / 2 - S spin-singlet pairs. The Bethe-ansatz strings of length n = 1 and n > 1 describe a single unbound spin-singlet pair and a configuration within which n pairs are bound, respectively. In the case of n > 1 pairs this holds both for ideal and deformed strings associated with n complex rapidities with the same real part. The use of such a spin 1/2 representation provides useful physical information on the problem under investigation in contrast to often less controllable numerical studies. Our results provide strong evidence for the absence of ballistic transport in the spin-1/2 XXX Heisenberg chain in the thermodynamic limit, for high temperatures T → ∞, vanishing magnetic field h → 0 and within the grand-canonical ensemble.

  3. Evidence of Dirac Monopoles in a Spin-1 Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Ray, Michael; Ruokokoski, Emmi; Kandel, Saugat; Möttönen, Mikko; Hall, David

    2014-03-01

    Isolated magnetic poles (monopoles) have not yet been observed, although there are good theoretical reasons for thinking that they may exist -- and profound implications if they do. The first successful theoretical description of a magnetic monopole consistent with quantum mechanics was formulated by Dirac, but may be applied more generally to quantum-mechanical systems in the presence of gauge potentials. We describe the successful experimental creation of Dirac monopoles in a synthetic magnetic field in the context of a dilute-gas Bose-Einstein condensate. The existence of a monopole is inferred from direct observations of a vortex line that terminates inside the condensate, which evidence is supported by excellent agreement between experiment and numerical simulations.

  4. 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

  5. Fractional magnetization plateaus of the spin-1/2 Heisenberg orthogonal-dimer chain: Strong-coupling approach developed from the exactly solved Ising-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Verkholyak, Taras; Strečka, Jozef

    2016-10-01

    The spin-1/2 Heisenberg orthogonal-dimer chain is considered within the perturbative strong-coupling approach, which is developed from the exactly solved spin-1/2 Ising-Heisenberg orthogonal-dimer chain with the Heisenberg intradimer and the Ising interdimer couplings. Although the spin-1/2 Ising-Heisenberg orthogonal-dimer chain exhibits just intermediate plateaus at zero, one-quarter, and one-half of the saturation magnetization, the perturbative treatment up to second order stemming from this exactly solvable model additionally corroborates the fractional one-third plateau as well as the gapless Luttinger spin-liquid phase. It is evidenced that the approximate results obtained from the strong-coupling approach are in an excellent agreement with the state-of-the-art numerical data obtained for the spin-1/2 Heisenberg orthogonal-dimer chain within the exact diagonalization and density-matrix renormalization group method. The nature of individual quantum ground states is comprehensively studied within the developed perturbation theory.

  6. Measurement of <σ z> ≈ 100 for a spin- {1}/{2} particle or “polarization amplification” of <σ> ≈ 1?

    NASA Astrophysics Data System (ADS)

    Golub, R.; Gähler, R.

    1989-04-01

    We present a description of the Aharonov-Albert-Vaidman (AAV) anomaly, wherein spin- {1}/{2} particle can have apparent values of < σz> ≫ 1, in terms of a normal behaviour with < σz> = 1 followed by an amplification of the resulting precessio n angles by a “polarization amplifier” as proposed by Mezei.

  7. 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.

  8. 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.

  9. Magnetic behaviors of a transverse spin-1/2 Ising cubic nanowire with core/shell structure

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    The surface shell exchange coupling effect on the magnetic properties (surface shell, core, total longitudinal and total transverse magnetizations, susceptibility, phase diagram and hysteresis loops) of a transverse spin-1/2 Ising cubic nanowire is investigated, in the present work, by employing the effective-field theory based on the probability distribution technique with correlations, for both ferro- and antiferromagnetic cases. We have found that this parameter has a strong effect on the magnetic properties in both cases. In the ferromagnetic case, the total longitudinal magnetization curves display Q- and S-type behaviors and the hysteresis loop has just one loop, whereas in the antiferromagnetic case, the N-type behavior, in which one compensation temperature appears below the critical temperature, exists in the total longitudinal magnetization curve versus reduced temperature, and triple hysteresis loops are found. The effect of applied field is also investigated on the total longitudinal magnetization for the both cases, and we have found that a large applied field value can overcome the antiferromagnetic coupling leading to a ferromagnetic-like behavior.

  10. Magnetic-field-induced quantum criticality in a spin-1 planar ferromagnet with single-ion anisotropy

    NASA Astrophysics Data System (ADS)

    Mercaldo, Maria Teresa; Rabuffo, Ileana; Decesare, Luigi; Caramicod'Auria, Alvaro

    2014-03-01

    The effects of single-ion anisotropy on field-induced quantum criticality in spin-1 planar ferromagnet is explored by means of the two-time Green's function method. We work at the Tyablikov decoupling level for exchange interactions and the Anderson-Callen decoupling level for single-ion anisotropy. In our analysis a longitudinal external magnetic field is used as the non-thermal control parameter and the phase diagram and the quantum critical properties are established for suitable values of the single-ion anisotropy parameter. We find that the single-ion anisotropy has sensible effects on the structure of the phase diagram close to the quantum critical point. Indeed, for values of the uniaxial crystal-field parameter above a positive threshold a re-entrant behavior appears for the critical line, while above this value the conventional magnetic-field-induced quantum critical scenario remains unchanged. M. T. Mercaldo, I. Rabuffo, L. De Cesare, A. Caramico D'Auria, Eur. Phys. J. B 86, 340 (2013)

  11. Topological Phases of Spin-1/2 Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chains with Alternating Next-Nearest-Neighbour Interaction

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2016-12-01

    A series of symmetry-protected topological (SPT) and trivial spin-gap phases in the spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain with alternating next-nearest-neighbour interaction are investigated using two kinds of entanglement spectra defined by different divisions of the whole chain. In case one of the next-nearest-neighbor interactions vanishes, the model reduces to the Δ-chain in which a series of spin-gap phases are found, as shown in J. Phys. Soc. Jpn. 77, 044707 (2008). From the degeneracy of the entanglement spectra, these phases are identified as the SPT and trivial phases. It is found that the ground-state phase boundaries are insensitive to the strength of the alternation in the next-nearest-neighbor interaction. These results are consistent with the analysis based on the nonlinear σ model and exact solution on the ferromagnetic-nonmagnetic phase boundary.

  12. Magnetism and thermodynamics of the anisotropic frustrated spin-1 Heisenberg antiferromagnet on a body-centered cubic lattice

    NASA Astrophysics Data System (ADS)

    Mi, Bin-Zhou

    2017-02-01

    The magnetic and thermodynamic properties of anisotropic frustrated spin-1 Heisenberg antiferromagnet on a body-centered cubic lattice for Néel phase (the region of weak frustration) are systematically investigated by use of the double-time Green's function method within the random phase approximation and the Anderson and Callen's decoupling. The zero-temperature sublattice magnetization and Néel temperature increase with spin anisotropy strength and single-ion anisotropy strength, and decrease with frustration strength. This indicates that quantum fluctuation is suppressed by spin anisotropy and single-ion anisotropy, by contrast, is strengthened by frustration. It is possible to tune the quantum fluctuations by the competition of anisotropy strength and frustration strength to change the ground state properties of magnetic materials. Although we find that both the spin anisotropy and the single-ion anisotropy suppress the quantum fluctuations, but their respective effects on the thermodynamic quantities, especially the internal energy and free energy, are different at zero temperature and finite temperature. Furthermore, when these two kinds of anisotropic coexist, the effect of the spin anisotropy on the sublattice magnetization and internal energy is larger than that of the single-ion anisotropy.

  13. Asymptotic correlation functions and FFLO signature for the one-dimensional attractive spin-1/2 Fermi gas

    PubMed Central

    Lee, J.Y.; Guan, X.W.

    2011-01-01

    We investigate the long distance asymptotics of various correlation functions for the one-dimensional spin-1/2 Fermi gas with attractive interactions using the dressed charge formalism. In the spin polarized phase, these correlation functions exhibit spatial oscillations with a power-law decay whereby their critical exponents are found through conformal field theory. We show that spatial oscillations of the leading terms in the pair correlation function and the spin correlation function solely depend on ΔkF and 2ΔkF, respectively. Here ΔkF=π(n↑−n↓) denotes the mismatch between the Fermi surfaces of spin-up and spin-down fermions. Such spatial modulations are characteristics of a Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state. Our key observation is that backscattering among the Fermi points of bound pairs and unpaired fermions results in a one-dimensional analog of the FFLO state and displays a microscopic origin of the FFLO nature. Furthermore, we show that the pair correlation function in momentum space has a peak at the point of mismatch between both Fermi surfaces k=ΔkF, which has recently been observed in numerous numerical studies. PMID:26594088

  14. Stability analysis for bad cavity lasers using inhomogeneously broadened spin-1/2 atoms as a gain medium

    NASA Astrophysics Data System (ADS)

    Kazakov, G. A.; Schumm, T.

    2017-02-01

    Bad cavity lasers are experiencing renewed interest in the context of active optical frequency standards, due to their enhanced robustness against fluctuations of the laser cavity. The gain medium would consist of narrow-linewidth atoms, either trapped inside the cavity or intersecting the cavity mode dynamically. A series of effects like the atoms finite velocity distribution, atomic interactions, or interactions of realistic multilevel atoms with auxiliary or stray fields can lead to an inhomogeneous broadening of the atomic gain profile. This causes the emergence of unstable regimes of laser operation, characterized by complex temporal patterns of the field amplitude. We study the steady-state solutions and their stability for the metrology-relevant case of a bad cavity laser with spin-1/2 atoms, such as 171Yb, interacting with an external magnetic field. For the stability analysis, we present an efficient method, which can be applied to a broad class of single-mode bad cavity lasers with inhomogeneously broadened multilevel atoms acting as a gain medium.

  15. Phase shifts of magneto-acoustic solitons in spin-1/2 fermionic quantum plasma during head-on collision

    NASA Astrophysics Data System (ADS)

    Chatterjee, Prasanta; Roychoudhury, Rajkumar; Ghorui, Malay Kumar; Ghorui

    2013-06-01

    The head-on collision between two magneto-acoustic solitons in spin-1/2 fermionic quantum plasma is studied in the framework of the model proposed by Marklund et al. (Marklund, M., Eliasson, B. and Shukla, P. K. 2007 Phys. Rev. E. 76, 067401). The extended Poincare-Lighthill-Kuo method is used to obtain the phase shifts and the trajectories during the head-on collision of two solitons. The effect of the Zeeman energy for different speeds of the waves, the effect of the total mass density of the charged plasma particles for different strengths of magnetic field, the effect of the speed of the wave for different values of the Zeeman energy, and that of the ratio of the sound speed to Alfven speed for different values of Zeeman energ on the phase shift are studied. It is observed that the phase shifts are significantly affected in all the cases. The most interesting observation of this paper is that the phase shifts increase as well as decrease, and also they may be positive as well as negative depending upon the domain of the chosen parameters.

  16. Dynamics of a Single Spin-1/2 Coupled to x- and y-Spin Baths: Algorithm and Results

    NASA Astrophysics Data System (ADS)

    Novotny, M. A.; Guerra, Marta L.; De Raedt, Hans; Michielsen, Kristel; Jin, Fengping

    The real-time dynamics of a single spin-1/2 particle, called the central spin, coupled to the x(y)-components of the spins of one or more baths is simulated. The bath Hamiltonians contain interactions of x(y)-components of the bath spins only but are general otherwise. An efficient algorithm is described which allows solving the time-dependent Schr'odinger equation for the central spin, even if the x(y) baths contain hundreds of spins. The algorithm requires storage for 2 × 2 matrices only, no matter how many spins are in the baths. We calculate the expectation value of the central spin, as well as its von Neumann entropy S(t), the quantum purity P(t), and the off-diagonal elements of the quantum density matrix. In the case of coupling the central spin to both x- and y- baths the relaxation of S(t) and P(t) with time is a power law, compared to an exponential if the central spin is only coupled to an x-bath. The effect of different initial states for the central spin and bath is studied. Comparison with more general spin baths is also presented.

  17. Numerical study of incommensurate and decoupled phases of spin-1/2 chains with isotropic exchange J1, J2 between first and second neighbors.

    PubMed

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

    2016-05-05

    The spin-1/2 chain with isotropic exchange J1, J2 > 0 between first and second neighbors is frustrated for either sign of J1 and has a singlet ground state (GS) for J1/J2 ⩾ -4. Its rich quantum phase diagram supports gapless, gapped, commensurate (C), incommensurate (IC) and other phases. Critical points J1/J2 are evaluated using exact diagonalization and density matrix renormalization group calculations. The wave vector qG of spin correlations is related to GS degeneracy and obtained as the peak of the spin structure factor S(q). Variable qG indicates IC phases in two J1/J2 intervals, [-4, - 1.24] and [0.44, 2], and a C-IC point at J1/J2 = 2. The decoupled C phase in [-1.24, 0.44] has constant qG = 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 Eσ, are degenerate in finite systems at specific frustration J1/J2. Level crossing extrapolates in the thermodynamic limit to the same critical points as qG. The S(q) peak diverges at qG = π in the gapless phase with J1/J2 > 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 J2/J1 but disagree for the decoupled phase with weak exchange J1 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.

  18. 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.

  19. Kinetic analysis of spin current contribution to spectrum of electromagnetic waves in spin-1/2 plasma. II. Dispersion dependencies

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel A.

    2017-02-01

    The dielectric permeability tensor for spin polarized plasmas derived in terms of the spin-1/2 quantum kinetic model in six-dimensional phase space obtained in Part I of this work is applied for the study of spectra of high-frequency transverse and transverse-longitudinal waves propagating perpendicular to the external magnetic field. Cyclotron waves are studied in consideration of waves with the electric field directed parallel to the external magnetic field. It is found that the separate spin evolution modifies the spectrum of cyclotron waves. These modifications increase with the increase in spin polarization and the number of the cyclotron resonance. Spin dynamics gives a considerable modification of spectra even if the anomalous part of electron magnetic moment is not included in the model. The account of anomalous magnetic moment leads to a fine structure of each cyclotron resonance. So, each cyclotron resonance splits into three waves. Details of this spectrum and its changes with the change of spin polarization are studied for the first and second cyclotron waves. A cyclotron resonance existing at ω≈0.001 | Ωe| due to the anomalous magnetic moment is also described, where | Ωe| is the cyclotron frequency. The ordinary waves do not have any considerable modification. The electrostatic and electromagnetic Berstein modes are studied during the analysis of waves propagating perpendicular to the external magnetic field with the electric field perturbation directed perpendicular to the external field. A modification of the oscillatory structure caused by the equilibrium spin polarization is found in both regimes. Similar modification is found for the extraordinary wave spectrum.

  20. Transfer-matrix study of a hard-square lattice gas with two kinds of particles and density anomaly

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago J.; Stilck, Jürgen F.

    2015-09-01

    Using transfer matrix and finite-size scaling methods, we study the thermodynamic behavior of a lattice gas with two kinds of particles on the square lattice. Only excluded volume interactions are considered, so that the model is athermal. Large particles exclude the site they occupy and its four first neighbors, while small particles exclude only their site. Two thermodynamic phases are found: a disordered phase where large particles occupy both sublattices with the same probability and an ordered phase where one of the two sublattices is preferentially occupied by them. The transition between these phases is continuous at small concentrations of the small particles and discontinuous at larger concentrations, both transitions are separated by a tricritical point. Estimates of the central charge suggest that the critical line is in the Ising universality class, while the tricritical point has tricritical Ising (Blume-Emery-Griffiths) exponents. The isobaric curves of the total density as functions of the fugacity of small or large particles display a minimum in the disordered phase.

  1. Haldane Phases and Ferrimagnetic Phases with Spontaneous Translational Symmetry Breakdown in Distorted Mixed Diamond Chains with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    The ground states of two types of distorted mixed diamond chains with spins 1 and 1/2 are investigated using exact diagonalization, DMRG, and mapping onto low-energy effective models. In the undistorted case, the ground state consists of an array of independent spin-1 clusters separated by singlet dimers. The lattice distortion induces an effective interaction between cluster spins. When this effective interaction is antiferromagnetic, several Haldane phases appear with or without spontaneous translational symmetry breakdown (STSB). The transition between the Haldane phase without STSB and that with (n+1)-fold STSB (n=1, 2, and 3) belongs to the same universality class as the (n+1)-clock model. In contrast, when the effective interaction is ferromagnetic, the quantized and partial ferrimagnetic phases appear with or without STSB. An effective low-energy theory for the partial ferrimagnetic phase is presented.

  2. Ba8CoNb6O24 : A spin-1/2 triangular-lattice Heisenberg antiferromagnet in the two-dimensional limit

    NASA Astrophysics Data System (ADS)

    Rawl, R.; Ge, L.; Agrawal, H.; Kamiya, Y.; Dela Cruz, C. R.; Butch, N. P.; Sun, X. F.; Lee, M.; Choi, E. S.; Oitmaa, J.; Batista, C. D.; Mourigal, M.; Zhou, H. D.; Ma, J.

    2017-02-01

    The perovskite Ba8CoNb6O24 comprises equilateral effective spin-1/2 Co2 + triangular layers separated by six nonmagnetic layers. Susceptibility, specific heat, and neutron scattering measurements combined with high-temperature series expansions and spin-wave calculations confirm that Ba8CoNb6O24 is basically a two-dimensional magnet with no detectable spin anisotropy and no long-range magnetic ordering down to 0.06 K. In other words, Ba8CoNb6O24 is very close to be a realization of the paradigmatic spin-1/2 triangular Heisenberg model, which is not expected to exhibit symmetry breaking at finite temperatures according to the Mermin and Wagner theorem.

  3. 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.

  4. 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

  5. Restrictions on the parameters of the spin-1 antigraviton and the dilaton resulting from the Casimir effect and from the Eoetvoes and Cavendish experiments

    SciTech Connect

    Mostepanenko, V.M.; Sokolov, I.Y. )

    1989-06-01

    On the basis of an analysis of experimental data, restrictions are obtained on the parameters of hypothetical long-range Yukawa-type interactions which arise from the exchange of vector and pseudo-Goldstone particles. The masses of the spin-1 antigraviton and the dilaton are estimated to be greater than 6{times}10{sup {minus}5} and 4{times}10{sup {minus}5} eV, respectively.

  6. Spin-1/2 kagome XXZ model in a field: Competition between lattice nematic and solid orders

    NASA Astrophysics Data System (ADS)

    Kshetrimayum, Augustine; Picot, Thibaut; Orús, Román; Poilblanc, Didier

    2016-12-01

    We study numerically the spin-1/2 XXZ model in a field on an infinite kagome lattice. We use different algorithms based on infinite projected entangled pair states (iPEPSs) for this, namely, (i) an approach with simplex tensors and a 9-site unit cell, and (ii) an approach based on coarse-graining three spins in the kagome lattice and mapping it to a square-lattice model with local and nearest-neighbor interactions, with the usual PEPS tensors, 6- and 12-site unit cells. Similarly to our previous calculation at the SU(2)-symmetric point (Heisenberg Hamiltonian), for any anisotropy from the Ising limit to the XY limit, we also observe the emergence of magnetization plateaus as a function of the magnetic field, at mz=1/3 using 6-, 9-, and 12-site PEPS unit cells, and at mz=1/9 ,5/9 , and 7/9 using a 9-site PEPS unit cell, the latter setup being able to accommodate √{3 }×√{3 } solid order. We also find that, at mz=1/3 , (lattice) nematic and √{3 }×√{3 } VBC-order states are degenerate within the accuracy of the nine-site simplex method, for all anisotropy. The 6- and 12-site coarse-grained PEPS methods produce almost-degenerate nematic and 1 ×2 VBC-solid orders. We also find that, within our accuracy, the six-site coarse-grained PEPS method gives slightly lower energies, which can be explained by the larger amount of entanglement this approach can handle, even in cases where the PEPS unit cell is not commensurate with the expected ground-state unit cell. Furthermore, we do not observe chiral spin liquid behaviors at and close to the XY point, as has been recently proposed. Our results are the first tensor network investigations of the XXZ model in a field and reveal the subtle competition between nearby magnetic orders in numerical simulations of frustrated quantum antiferromagnets, as well as the delicate interplay between energy optimization and symmetry in tensor network numerical simulations.

  7. Effects of interference in the dynamics of a spin- 1/2 transverse XY chain driven periodically through quantum critical points

    NASA Astrophysics Data System (ADS)

    Mukherjee, Victor; Dutta, Amit

    2009-05-01

    We study the effects of interference on the quenching dynamics of a one-dimensional spin 1/2 XY model in the presence of a transverse field (h(t)) which varies sinusoidally with time as h = h0cosωt, with |t|<=tf = π/ω. We have explicitly shown that the finite values of tf make the dynamics inherently dependent on the phases of probability amplitudes, which had been hitherto unseen in all cases of linear quenching with large initial and final times. In contrast, we also consider the situation where the magnetic field consists of an oscillatory as well as a linearly varying component, i.e., h(t) = h0cosωt+t/τ, where the interference effects lose importance in the limit of large τ. Our purpose is to estimate the defect density and the local entropy density in the final state if the system is initially prepared in its ground state. For a single crossing through the quantum critical point with h = h0cosωt, the density of defects in the final state is calculated by mapping the dynamics to an equivalent Landau-Zener problem by linearizing near the crossing point, and is found to vary as \\sqrt {\\omega } in the limit of small ω. On the other hand, the local entropy density is found to attain a maximum as a function of ω near a characteristic scale ω0. Extending to the situation of multiple crossings, we show that the role of finite initial and final times of quenching are manifested non-trivially in the interference effects of certain resonance modes which solely contribute to the production of defects. Kink density as well as the diagonal entropy density show oscillatory dependence on the number of full cycles of oscillation. Finally, the inclusion of a linear term in the transverse field on top of the oscillatory component results in a kink density which decreases continuously with τ while it increases monotonically with ω. The entropy density also shows monotonic change with the parameters, increasing with τ and decreasing with ω, in sharp contrast to the

  8. 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.

  9. Crystallized half-skyrmions and inverted half-skyrmions in the condensation of spin-1 Bose gases with spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Su, S.-W.; Liu, I.-K.; Tsai, Y.-C.; Liu, W. M.; Gou, S.-C.

    2012-08-01

    The nonequilibrium dynamics of a rapidly quenched spin-1 Bose gas with spin-orbit coupling is studied. By solving the stochastic projected Gross-Pitaevskii equation, we show that crystallization of half-skyrmions (merons), can occur in a spinor condensate of 87Rb. The stability of such a crystal structure is analyzed. Likewise, inverted half-skyrmions can be created in a spin-polarized spinor condensate of 23Na. Our studies provide a chance to explore the fundamental properties of skyrmionlike matter.

  10. Kinetic analysis of spin current contribution to spectrum of electromagnetic waves in spin-1/2 plasma. I. Dielectric permeability tensor for magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel A.

    2017-02-01

    The dielectric permeability tensor for spin polarized plasmas is derived in terms of the spin-1/2 quantum kinetic model in six-dimensional phase space. Expressions for the distribution function and spin distribution function are derived in linear approximations on the path of dielectric permeability tensor derivation. The dielectric permeability tensor is derived for the spin-polarized degenerate electron gas. It is also discussed at the finite temperature regime, where the equilibrium distribution function is presented by the spin-polarized Fermi-Dirac distribution. Consideration of the spin-polarized equilibrium states opens possibilities for the kinetic modeling of the thermal spin current contribution in the plasma dynamics.

  11. 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.

  12. 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.

  13. Efficient polarization transfer between spin-1/2 and ¹⁴N nuclei in solid-state MAS NMR spectroscopy.

    PubMed

    Basse, Kristoffer; Jain, Sheetal Kumar; Bakharev, Oleg; Nielsen, Niels Chr

    2014-07-01

    Polarization transfer between spin-1/2 nuclei and quadrupolar spin-1 nuclei such as (14)N in solid-state NMR is severely challenged by the typical presence of large quadrupole coupling interactions. This has effectively prevented the use of the abundant (14)N spin as a probe to structural information and its use as an element in multi-dimensional solid-state NMR correlation experiments for assignment and structural characterization. In turn, this has been a contributing factor to the extensive use of isotope labeling in biological solid-state NMR, where (14)N is replaced with (15)N. The alternative strategy of using the abundant (14)N spins calls for methods enabling efficient polarization transfer between (14)N and its binding partners. This work demonstrates that the recently introduced (RESPIRATION)CP transfer method can be optimized to achieve efficient (1)H ↔(14)N polarization transfer under magic angle spinning conditions. The method is demonstrated numerically and experimentally on powder samples of NH4NO3 and L-alanine.

  14. Unconventional quantum ordered and disordered states in the highly frustrated spin-(1)/(2) Ising-Heisenberg model on triangles-in-triangles lattices

    NASA Astrophysics Data System (ADS)

    Čisárová, Jana; Strečka, Jozef

    2013-01-01

    The spin-(1)/(2) Ising-Heisenberg model on two geometrically related triangles-in-triangles lattices is exactly solved through the generalized star-triangle transformation, which establishes a rigorous mapping correspondence with the effective spin-(1)/(2) Ising model on a triangular lattice. Basic thermodynamic quantities were exactly calculated within this rigorous mapping method along with the ground-state and finite-temperature phase diagrams. Apart from the classical ferromagnetic phase, both investigated models exhibit several unconventional quantum ordered and disordered ground states. A mutual competition between two ferromagnetic interactions of basically different character generically leads to the emergence of a quantum ferromagnetic phase, in which a symmetric quantum superposition of three up-up-down states of the Heisenberg trimers accompanies a perfect alignment of all Ising spins. In the highly frustrated regime, we have either found the disordered quantum paramagnetic phase with a substantial residual entropy or a similar but spontaneously ordered phase with a nontrivial criticality at finite temperatures. The latter quantum ground state exhibits a striking coexistence of imperfect spontaneous order with partial disorder, which is evidenced by a quantum reduction of the spontaneous magnetization of Heisenberg spins that indirectly causes a small reduction of the spontaneous magnetization of otherwise classical Ising spins.

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

    DOE PAGES

    Ma, Jie; Kamiya, Yoshitomo; Hong, Tao; ...

    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

  17. Ground-state fidelity of the spin-1 Heisenberg chain with single ion anisotropy: quantum renormalization group and exact diagonalization approaches.

    PubMed

    Langari, A; Pollmann, F; Siahatgar, M

    2013-10-09

    We study the phase diagram of the anisotropic spin-1 Heisenberg chain with single ion anisotropy (D) using a ground-state fidelity approach. The ground-state fidelity and its corresponding susceptibility are calculated within the quantum renormalization group scheme where we obtained the renormalization of fidelity preventing calculation of the ground state. Using this approach, the phase boundaries between the antiferromagnetic Néel, Haldane and large-D phases are obtained for the whole phase diagram, which justifies the application of quantum renormalization group to trace the symmetry-protected topological phases. In addition, we present numerical exact diagonalization (Lanczos) results in which we employ a recently introduced non-local order parameter to locate the transition from Haldane to large-D phase accurately.

  18. Topological Phases of the Spin-1/2 Ferromagnetic--Antiferromagnetic Alternating Heisenberg Chain with Frustrated Next-Nearest-Neighbour Interaction

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    The spin-1/2 ferromagnetic--antiferromagnetic alternating Heisenberg chain with ferromagnetic next-nearest-neighbour (NNN) interaction is investigated. The ground state is the Haldane phase for weak NNN interaction, and is the ferromagnetic phase for weak antiferromagnetic interaction. We find a series of topologically distinct spin-gap phases with various magnitudes of edge spins for strong NNN interaction. The phase boundaries between these phases are determined on the basis of the DMRG calculation with additional spins that compensate the edge spins. It is found that each of the exact solutions with short-range antiferromagnetic correlation on the ferromagnetic--nonmagnetic phase boundary is representative of each spin gap phase.

  19. Bimodal random crystal field distribution effects on the ferrimagnetic mixed spin-1/2 > and spin-3/2 Blume-Capel model

    NASA Astrophysics Data System (ADS)

    Yigit, Ali; Albayrak, Erhan

    2013-03-01

    The effects of bimodal random crystal field on the phase diagrams and magnetization curves of ferrimagnetic mixed spin-1/2 and spin-3/2 Blume-Capel model are examined by using the effective field theory with correlations for honeycomb lattice. The phase diagrams are obtained on the (Δ,kT/|J|), (Δ,Tcomp) and (p,kT/|J|) planes for given values of p and Δ, respectively. The model exhibits only the second-order phase transitions as in the Blume-Capel model with constant crystal fields. In addition, it was found that the model presents one or two compensation temperatures for appropriate values of random crystal field for given probability in contrast to constant crystal field case. Therefore, it is shown that the random crystal field considerably affects the thermal variations of net and sublattice magnetizations.

  20. 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.

  1. Quantum tunneling of spin-1 particles from a 5D Einstein-Yang-Mills-Gauss-Bonnet black hole beyond semiclassical approximation

    NASA Astrophysics Data System (ADS)

    Jusufi, K.

    2016-12-01

    In the present paper we study the Hawking radiation as a quantum tunneling effect of spin-1 particles from a five-dimensional, spherically symmetric, Einstein-Yang-Mills-Gauss-Bonnet (5D EYMGB) black hole. We solve the Proca equation (PE) by applying the WKB approximation and separation of variables via Hamilton-Jacobi (HJ) equation which results in a set of five differential equations, and reproduces, in this way, the Hawking temperature. In the second part of this paper, we extend our results beyond the semiclassical approximation. In particular, we derive the logarithmic correction to the entropy of the EYMGB black hole and show that the quantum corrected specific heat indicates the possible existence of a remnant.

  2. Variational Monte Carlo study of a gapless spin liquid in the spin-1/2 XXZ antiferromagnetic model on the kagome lattice

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Jun; Gong, Shou-Shu; Becca, Federico; Sheng, D. N.

    2015-11-01

    By using the variational Monte Carlo technique, we study the spin-1/2 XXZ antiferromagnetic model (with easy-plane anisotropy) on the kagome lattice. A class of Gutzwiller projected fermionic states with a spin Jastrow factor is considered to describe either spin liquids [with U (1 ) or Z2 symmetry] or magnetically ordered phases [with q =(0 ,0 ) or q =(4 π /3 ,0 ) ]. We find that the magnetic states are not stable in the thermodynamic limit. Moreover, there is no energy gain to break the gauge symmetry from U (1 ) to Z2 within the spin-liquid states, as previously found in the Heisenberg model. The best variational wave function is therefore the U (1 ) Dirac state, supplemented by the spin Jastrow factor. Furthermore, a vanishing S =2 spin gap is obtained at the variational level, in the whole regime from the X Y to the Heisenberg model.

  3. 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.

  4. 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.

  5. Direct observation of impurity-induced magnetism in a spin-(1/2) antiferromagnetic Heisenberg two-leg spin ladder.

    PubMed

    Casola, F; Shiroka, T; Wang, S; Conder, K; Pomjakushina, E; Mesot, J; Ott, H-R

    2010-08-06

    Nuclear magnetic resonance and magnetization measurements were used to probe the magnetic features of single-crystalline Bi(Cu(1-x)Zn(x))(2)PO(6) with 00 and we present clear evidence for a temperature-dependent variation of the local magnetization close to the Zn sites. The generic nature of this observation is indicated by results of model calculations on appropriate spin systems of limited size employing quantum Monte Carlo methods.

  6. 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.

  7. Taurine detected using high-resolution magic angle spinning 1H nuclear magnetic resonance: A potential indicator of early myocardial infarction

    PubMed Central

    YANG, YUNLONG; YANG, LIN; ZHANG, YUE; GU, XINGHUA; XU, DANLING; FANG, FANG; SUN, AIJUN; WANG, KEQIANG; YU, YIHUA; ZUO, JI; GE, JUNBO

    2013-01-01

    Magnetic resonance spectroscopy (MRS) is a unique non-invasive method for detecting cardiac metabolic changes. However, MRS in cardiac diagnosis is limited due to insensitivity and low efficiency. Taurine (Tau) is the most abundant free amino acid in the myocardium. We hypothesized that Tau levels may indicate myocardial ischemia and early infarction. Sprague-Dawley rats were divided into seven groups according to different time points during the course of myocardial ischemia, which was induced by left anterior descending coronary artery ligation. Infarcted myocardial tissue was obtained for high-resolution magic angle spinning 1H nuclear magnetic resonance (NMR) analysis. Results were validated via high-performance liquid chromatography. The Tau levels in the ischemic myocardial tissue were reduced significantly within 5 min compared with those in the control group (relative ratio from 20.27±6.48 to 8.81±0.04, P<0.05) and were maintained for 6 h post-ischemia. Tau levels declined more markedly (56.5%) than creatine levels (48.5%) at 5 min after ligation. This suggests that Tau may have potential as an indicator in the early detection of myocardial ischemia by 1H MRS. PMID:23408155

  8. Effects of frustration and cyclic exchange on the spin-1/2 Heisenberg antiferromagnet within the self-consistent spin-wave theory

    NASA Astrophysics Data System (ADS)

    Rutonjski, Milica S.; Pavkov-Hrvojević, Milica V.; Berović, Maja B.

    2016-12-01

    The relevance of the quasi-two-dimensional spin-1/2 frustrated quantum antiferromagnet (AFM) due to its possibility of modeling the high-temperature superconducting parent compounds has resulted in numerous theoretical and experimental studies. This paper presents a detailed research of the influence of the varying exchange interactions on the model magnetic properties within the framework of self-consistent spin-wave theory based on Dyson-Maleev (DM) representation. Beside the nearest neighbor (NN) interaction within the plane, the planar frustration up to the third NNs, cyclic interaction and the interlayer coupling are taken into account. The detailed description of the elementary spin excitations, staggered magnetization, spin-wave velocity renormalization factor and ground state energy is given. The results are compared to the predictions of the linear spin-wave theory and when possible also to the second-order perturbative spin-wave expansion results. Finally, having at our disposal improved experimental results for the in-plane spin-wave dispersion in high-Tc copper oxide La2CuO4, the self-consistent spin-wave theory (SCSWT) is applied to that compound in order to correct earlier obtained set of exchange parameters and high-temperature spin-wave dispersion.

  9. SPAM-MQ-HETCOR: an improved method for heteronuclear correlation spectroscopy between quadrupolar and spin-1/2 nuclei in solid-state NMR.

    PubMed

    Wiench, Jerzy W; Tricot, Gregory; Delevoye, Laurent; Trebosc, Julien; Frye, James; Montagne, Lionel; Amoureux, Jean-Paul; Pruski, Marek

    2006-01-07

    The recently introduced concept of soft pulse added mixing (SPAM) is used in two-dimensional heteronuclear correlation (HETCOR) NMR experiments between half-integer quadrupolar and spin-1/2 nuclei. The experiments employ multiple quantum magic angle spinning (MQMAS) to remove the second order quadrupolar broadening and cross polarization (CP) or refocused INEPT for magnetization transfer. By using previously unexploited coherence pathways, the efficiency of SPAM-MQ-HETCOR NMR is increased by a factor of almost two without additional optimization. The sensitivity gain is demonstrated on a test sample, AlPO(4)-14, using CP and INEPT to correlate (27)Al and (31)P nuclei. SPAM-3Q-HETCOR is then applied to generate (27)Al-(31)P spectra of the devitrified 41Na(2)O-20.5Al(2)O(3)-38.5P(2)O(5) glass and the silicoaluminophosphate ECR-40. Finally, the method allowed the acquisition of the first high resolution solid-state correlation spectra between (27)Al and (29)Si.

  10. Magnetization process, bipartite entanglement, and enhanced magnetocaloric effect of the exactly solved spin-1/2 Ising-Heisenberg tetrahedral chain.

    PubMed

    Strečka, Jozef; Rojas, Onofre; Verkholyak, Taras; Lyra, Marcelo L

    2014-02-01

    The frustrated spin-1/2 Ising-Heisenberg ladder with Heisenberg intra-rung and Ising inter-rung interactions is exactly solved in a longitudinal magnetic field by taking advantage of the local conservation of the total spin on each rung and the transfer-matrix method. We have rigorously calculated the ground-state phase diagram, magnetization process, magnetocaloric effect, and basic thermodynamic quantities for the model, which can be alternatively viewed as an Ising-Heisenberg tetrahedral chain. It is demonstrated that a stepwise magnetization curve with an intermediate plateau at half of the saturation magnetization is also reflected in respective stepwise changes of the concurrence serving as a measure of bipartite entanglement. The ground-state phase diagram and zero-temperature magnetization curves of the Ising-Heisenberg tetrahedral chain are contrasted with the analogous results of the purely quantum Heisenberg tetrahedral chain, which have been obtained through density-matrix renormalization group (DMRG) calculations. While both ground-state phase diagrams fully coincide in the regime of weak inter-rung interaction, the purely quantum Heisenberg tetrahedral chain develops Luttinger spin-liquid and Haldane phases for strongly coupled rungs, which are absent in the Ising-Heisenberg counterpart model.

  11. 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.

  12. Level crossing, spin structure factor and quantum phases of the frustrated spin-1/2 chain with first and second neighbor exchange.

    PubMed

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

    2015-08-12

    The spin-1/2 chain with isotropic Heisenberg exchange J1, J2  >  0 between first and second neighbors is frustrated for either sign of J1. Its quantum phase diagram has critical points at fixed J1/J2 between gapless phases with nondegenerate ground state (GS) and quasi-long-range order (QLRO) and gapped phases with doubly degenerate GS and spin correlation functions of finite range. In finite chains, exact diagonalization (ED) estimates critical points as level crossing of excited states. GS spin correlations enter in the spin structure factor S(q) that diverges at wave vector qm in QLRO(q(m)) phases with periodicity 2π/q(m) but remains finite in gapped phases. S(q(m)) is evaluated using ED and density matrix renormalization group (DMRG) calculations. Level crossing and the magnitude of S(q(m)) are independent and complementary probes of quantum phases, based respectively on excited and ground states. Both indicate a gapless QLRO(π/2) phase between  -1.2  <  J1/|J2|  <  0.45. Numerical results and field theory agree well for quantum critical points at small frustration J2 but disagree in the sector of weak exchange J1 between Heisenberg antiferromagnetic chains on sublattices of odd and even-numbered sites.

  13. The field-induced laws of thermodynamic properties in the two-dimensional spin-1 ferromagnetic Heisenberg model with the exchange and single-ion anisotropies

    NASA Astrophysics Data System (ADS)

    Pu, Qiurong; Chen, Yuan

    2013-02-01

    Green's function method is applied to investigate the two-dimensional spin-1 ferromagnetic Heisenberg model with the exchange and single-ion anisotropies. In the presence of the magnetic field, the effects of the anisotropies and field on the thermodynamic properties are obtained within the random phase approximation combining with Anderson-Callen approximation. The field-induced laws are found for the thermodynamic properties. Field dependences of heights of the susceptibility maximum and specific heat maximum fit well to power laws. The linear increase at high fields is shown for positions of the susceptibility maximum and specific heat maximum. A power law at low fields occurs for the position of the susceptibility maximum. At the positions of the maxima, the magnetization and internal energy display the power-law increase and linear decrease with the field, respectively. The exponents of the power laws are dependent of the anisotropies, as well as the slopes of the linear laws. Our results do not support the 2/3 power law which was obtained by the Landau theory.

  14. Three-dimensional quantum phase diagram of the exact ground states of a mixture of two species of spin-1 Bose gases with interspecies spin exchange

    SciTech Connect

    Shi Yu; Ge Li

    2011-01-15

    We find nearly all the exact ground states of a mixture of two species of spin-1 atoms with both interspecies and intraspecies spin exchanges in the absence of a magnetic field. The quantum phase diagram in the three-dimensional parameter space and its two-dimensional cross sections are described. The boundaries where the ground states are either continuous or discontinuous are determined, with the latter identified as where quantum phase transitions take place. The two species are always disentangled if the interspecies spin coupling is ferromagnetic or zero. Quantum phase transitions occur when the interspecies spin coupling varies between antiferromagnetic and zero or ferromagnetic while the two intraspecies spin couplings both remain ferromagnetic. On the other hand, by tuning the interspecies spin coupling from zero to antiferromagnetic and then back to zero, one can circumvent the quantum phase transition due to sign change of the intraspecies spin coupling of a single species, which is spin decoupled with the other species with ferromagnetic intraspecies spin coupling. Generally speaking, interplay among interspecies and two intraspecies spin exchanges significantly enriches quantum phases of spinor atomic gases.

  15. 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.

  16. 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

  17. High-Resolution Magic-Angle Spinning-(1)H NMR Spectroscopy-Based Metabolic Profiling of Hippocampal Tissue in Rats with Depression-Like Symptoms.

    PubMed

    Akimoto, Hayato; Oshima, Shinji; Ohara, Kousuke; Negishi, Akio; Hiroyama, Hanako; Nemoto, Tadashi; Kobayashi, Daisuke

    2017-03-04

    Depressive disorders cause large socioeconomic effects influencing not only the patients themselves but also their family and broader community as well. To better understand the physiologic factors underlying depression, in this study, we performed metabolomics analysis, an omics technique that comprehensively analyzes small molecule metabolites in biological samples. Specifically, we utilized high-resolution magic-angle spinning-(1)H NMR (HRMAS-(1)H NMR) spectroscopy to comprehensively analyze the changes in metabolites in the hippocampal tissue of rats exposed to chronic stress (CS) via multi-step principal component analysis (multi-step PCA). The rats subjected to CS exhibited obvious depression-like behaviors. High correlations were observed between the first principal component (PC1) score in the score plot obtained using multi-step PCA and measurements from depression-like behavioral testing (body weight, sucrose preference test, and open field test). Alanine, glutamate, glutamine, and aspartate levels in the hippocampal tissue were significantly lower, whereas N-acetylaspartate, myo-inositol, and creatine were significantly higher in the CS group compared to the control (non-CS) group. As alanine, glutamate, and glutamine are known to be involved in energy metabolism, especially in the TCA cycle, chronic exogenous stress may have induced abnormalities in energy metabolism in the brains of the rats. The results suggest that N-acetylaspartate and creatine levels may have increased in order to complement the loss of energy-producing activity resulting from the development of the depression-like disorder. Multi-step PCA therefore allowed an exploration of the degree of depression-like symptoms as represented by changes in intrinsic metabolites.

  18. 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.

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

    PubMed

    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 Q_{2} 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 α_{c}=-0.93. Through the finite-size scaling analysis on Q_{2}, ρ_{x}, and ρ_{y}, 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 ^{3}He under different pressures and several magnetic compounds under various magnetic fields. The scaling behaviors of Q_{2}, ρ, and C(T) are carefully analyzed. The susceptibility is compared with the experimental data to give the magnetic parameters of both compounds.

  20. The quantum spin-1/2 J1-J2 antiferromagnet on a stacked square lattice: a study of effective-field theory in a finite cluster.

    PubMed

    Nunes, Wagner A; de Sousa, J Ricardo; Viana, J Roberto; Richter, J

    2010-04-14

    The ground state phase diagram of the quantum spin-1/2 Heisenberg antiferromagnet in the presence of nearest-neighbor (J(1)) and next-nearest-neighbor (J(2)) interactions (J(1)-J(2) model) on a stacked square lattice, where we introduce an interlayer coupling through nearest-neighbor bonds of strength J(), is studied within the framework of the differential operator technique. The Hamiltonian is solved by effective-field theory in a cluster with N=4 spins (EFT-4). We obtain the sublattice magnetization m(A) for the ordered phases: antiferromagnetic (AF) and collinear (CAF-collinear antiferromagnetic). We propose a functional for the free energy Ψ(μ)(m(μ)) (μ=A, B) to obtain the phase diagram in the λ-α plane, where λ=J()/J(1) and α=J(2)/J(1). Depending on the values of λ and α, we found different ordered states (AF and CAF) and a disordered state (quantum paramagnetic (QP)). For an intermediate region α(1c)(λ) < α < α(2c)(λ) we observe a QP phase that disappears for λ below some critical value λ(1)≈0.67. For α < α(1c)(λ) and α > α(2c)(λ), and below λ(1), we have the AF and CAF semi-classically ordered states, respectively. At α=α(1c)(λ) a second-order transition between the AF and QP states occurs and at α=α(2c)(λ) a first-order transition between the AF and CAF phases takes place. The boundaries between these ordered phases merge at the critical end point CEP≡(λ(1), α(c)), where α(c)≈0.56. Above this CEP there is again a direct first-order transition between the AF and CAF phases, with a behavior described by the point α(c) independent of λ ≥ λ(1).

  1. Thermal entanglement and sharp specific-heat peak in an exactly solved spin-1/2 Ising-Heisenberg ladder with alternating Ising and Heisenberg inter-leg couplings

    NASA Astrophysics Data System (ADS)

    Rojas, Onofre; Strečka, J.; de Souza, S. M.

    2016-11-01

    The spin-1/2 Ising-Heisenberg two-leg ladder accounting for alternating Ising and Heisenberg inter-leg couplings in addition to the Ising intra-leg coupling is rigorously mapped onto to a mixed spin-(3/2,1/2) Ising-Heisenberg diamond chain with the nodal Ising spins S = 3 / 2 and the interstitial spin-1/2 Heisenberg dimers. The latter effective model with higher-order interactions between the nodal and interstitial spins is subsequently exactly solved within the transfer-matrix method. The model under investigation exhibits five different ground states: ferromagnetic, antiferromagnetic, superantiferromagnetic and two types of frustrated ground states with a non-zero residual entropy. A detailed study of thermodynamic properties reveals an anomalous specific-heat peak at low enough temperatures, which is strongly reminiscent because of its extraordinary height and sharpness to an anomaly accompanying a phase transition. It is convincingly evidenced, however, that the anomalous peak in the specific heat is finite and it comes from vigorous thermal excitations from a two-fold degenerate ground state towards a macroscopically degenerate excited state. Thermal entanglement between the nearest-neighbor Heisenberg spins is also comprehensively explored by taking advantage of the concurrence. The threshold temperature delimiting a boundary between the entangled and disentangled parameter space may show presence of a peculiar temperature reentrance.

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

    SciTech Connect

    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 theoretical framework for describing excitation spectra in low-dimensional frustrated magnets under strong quantum effects.

  3. Spin-1/2 Ising-Heisenberg model with the pair XYZ Heisenberg interaction and quartic Ising interactions as the exactly soluble zero-field eight-vertex model.

    PubMed

    Strecka, Jozef; Canová, Lucia; Minami, Kazuhiko

    2009-05-01

    The spin-1/2 Ising-Heisenberg model with the pair XYZ Heisenberg interaction and quartic Ising interactions is exactly solved by establishing a precise mapping relationship with the corresponding zero-field (symmetric) eight-vertex model. It is shown that the Ising-Heisenberg model with the ferromagnetic Heisenberg interaction exhibits a striking critical behavior, which manifests itself through re-entrant phase transitions as well as continuously varying critical exponents. The changes in critical exponents are in accordance with the weak universality hypothesis in spite of a peculiar singular behavior that emerges at a quantum critical point of the infinite order, which occurs at the isotropic limit of the Heisenberg interaction. On the other hand, the Ising-Heisenberg model with the antiferromagnetic Heisenberg interaction surprisingly exhibits less significant changes in both critical temperatures and critical exponents upon varying the strength of the exchange anisotropy in the Heisenberg interaction.

  4. Phase transitions in a three-dimensional kinetic spin-1/2 Ising model with random field: effective-field-theory study.

    PubMed

    Costabile, Emanuel; de Sousa, J Ricardo

    2012-01-01

    The dynamical phase transitions of the kinetic Ising model in the presence of a random magnetic field with a bimodal probability distribution is studied by using effective-field theory (EFT) with correlations. We have used a Glauber-type stochastic dynamic to describe the time evolution of the system, where the system strongly depends on the H≡√(c) root mean square deviation of the magnetic field. The EFT dynamic equation is given for the simple cubic lattice (z=6), and the dynamic order parameter is calculated. The system presents ferromagnetic and paramagnetic states for low and high temperatures, respectively. Our results predict first-order transitions at low temperatures and large disorder strengths, which corresponds to the existence of a nonequilibrium tricritical point (TCP) in a phase diagram in the T-H plane. We compare the results with the equilibrium phase diagram, where only the first-order line is different. Our qualitative results are compatible with recent Monte Carlo simulations.

  5. Refining the spin Hamiltonian in the spin-1/2 kagome lattice antiferromagnet ZnCu3(OH)6Cl2 using single crystals.

    PubMed

    Han, Tianheng; Chu, Shaoyan; Lee, Young S

    2012-04-13

    We report thermodynamic measurements of the S=1/2 kagome lattice antiferromagnet ZnCu3(OH)6Cl2, a promising candidate system with a spin-liquid ground state. Using single crystal samples, the magnetic susceptibility both perpendicular and parallel to the kagome plane has been measured. A small, temperature-dependent anisotropy has been observed, where χ(z)/χ(p)>1 at high temperatures and χ(z)/χ(p)<1 at low temperatures. Fits of the high-temperature data to a Curie-Weiss model also reveal an anisotropy. By comparing with theoretical calculations, the presence of a small easy-axis exchange anisotropy can be deduced as the primary perturbation to the dominant Heisenberg nearest neighbor interaction. These results have great bearing on the interpretation of theoretical calculations based on the kagome Heisenberg antiferromagnet model to the experiments on ZnCu3(OH)6Cl2.

  6. Epitope diversity of N-glycans from bovine peripheral myelin glycoprotein P0 revealed by mass spectrometry and nano probe magic angle spinning 1H NMR spectroscopy.

    PubMed

    Gallego, R G; Blanco, J L; Thijssen-van Zuylen, C W; Gotfredsen, C H; Voshol, H; Duus, J Ø; Schachner, M; Vliegenthart, J F

    2001-08-17

    The carbohydrate structures present on the glycoproteins in the central and peripheral nerve systems are essential in many cell adhesion processes. The P0 glycoprotein, expressed by myelinating Schwann cells, plays an important role during the formation and maintenance of myelin, and it is the most abundant constituent of myelin. Using monoclonal antibodies, the homophilic binding of the P0 glycoprotein was shown to be mediated via the human natural keller cell (HNK)-1 epitope (3-O-SO(3)H-GlcUA(beta1-3)Gal(beta1-4)GlcNAc) present on the N-glycans. We recently described the structure of the N-glycan carrying the HNK-1 epitope, present on bovine peripheral myelin P0 (Voshol, H., van Zuylen, C. W. E. M., Orberger, G., Vliegenthart, J. F. G., and Schachner, M. (1996) J. Biol. Chem. 271, 22957-22960). In this study, we report on the structural characterization of the detectable glycoforms, present on the single N-glycosylation site, using state-of-the-art NMR and mass spectrometry techniques. Even though all structures belong to the hybrid- or biantennary complex-type structures, the variety of epitopes is remarkable. In addition to the 3-O-sulfate present on the HNK-1-carrying structures, most of the glycans contain a 6-O-sulfated N-acetylglucosamine residue. This indicates the activity of a 6-O-sulfo-GlcNAc-transferase, which has not been described before in peripheral nervous tissue. The presence of the disialo-, galactosyl-, and 6-O-sulfosialyl-Lewis X epitopes provides evidence for glycosyltransferase activities not detected until now. The finding of such an epitope diversity triggers questions related to their function and whether events, previously attributed merely to the HNK-1 epitope, could be mediated by the structures described here.

  7. Spin-1/2 Optical Lattice Clock

    NASA Astrophysics Data System (ADS)

    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.

    2009-08-01

    We experimentally investigate an optical clock based on Yb171 (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 3.4×10-16, 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.

  8. 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.

  9. 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.

  10. Spin-frustration in a new spin-1/2 oxyfluoride system (Cu13(VO4)4(OH)10F4) constructed by alternatively distorted kagome-like and triangular lattices.

    PubMed

    Yang, Ming; Zhang, Su-Yun; Guo, Wen-Bin; Tang, Ying-Ying; He, Zhang-Zhen

    2015-09-21

    A novel copper compound, Cu13(VO4)4(OH)10F4, featuring two types of two-dimensional extended kagome-like and triangular lattices, exhibits long-range antiferromagnetic ordering at ∼3 K, a strong spin-frustration effect with f = 21 and a spin-flop transition at 5 T.

  11. Exact linearization of the radiation-damped spin system

    PubMed

    Rourke; Augustine

    2000-02-21

    Nonlinear evolution of the Landau-Lifshitz type can be exactly linearized. Special cases include the radiation-damped spin system and the superradiant system in the semiclassical regime, in the presence of time-varying driving fields. For these, the resultant linear system is simply that of a spin 1 / 2 particle, with the radiation damping rate, or superradiant characteristic time, manifested as an imaginary addition to the spin's resonance frequency. Consequently, methods from inverse scattering theory can be used to design driving fields. The behavior of these systems under stochastic excitation can be determined exactly.

  12. Experimental Rectification of Entropy Production by Maxwell's Demon in a Quantum System

    NASA Astrophysics Data System (ADS)

    Camati, Patrice A.; Peterson, John P. S.; Batalhão, Tiago B.; Micadei, Kaonan; Souza, Alexandre M.; Sarthour, Roberto S.; Oliveira, Ivan S.; Serra, Roberto M.

    2016-12-01

    Maxwell's demon explores the role of information in physical processes. Employing information about microscopic degrees of freedom, this "intelligent observer" is capable of compensating entropy production (or extracting work), apparently challenging the second law of thermodynamics. In a modern standpoint, it is regarded as a feedback control mechanism and the limits of thermodynamics are recast incorporating information-to-energy conversion. We derive a trade-off relation between information-theoretic quantities empowering the design of an efficient Maxwell's demon in a quantum system. The demon is experimentally implemented as a spin-1 /2 quantum memory that acquires information, and employs it to control the dynamics of another spin-1 /2 system, through a natural interaction. Noise and imperfections in this protocol are investigated by the assessment of its effectiveness. This realization provides experimental evidence that the irreversibility in a nonequilibrium dynamics can be mitigated by assessing microscopic information and applying a feed-forward strategy at the quantum scale.

  13. 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.

  14. An Optical Lattice Clock with Spin 1/2 Atoms

    DTIC Science & Technology

    2012-01-01

    89 4.4 Vector Stark shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90...ytterbium atoms The first proposal for an optical lattice clock called for spectroscopy of a narrow optical tran- sition in ultracold strontium atoms [40...Since then, experimental groups have begun researching not only strontium (Sr) [70, 71, 72, 73, 74], but also ytterbium (Yb) [75, 76, 77, 78, 79] and

  15. Ground states of the spin-1 Bose-Hubbard model.

    PubMed

    Katsura, Hosho; Tasaki, Hal

    2013-03-29

    We prove basic theorems about the ground states of the S=1 Bose-Hubbard model. The results are quite universal and depend only on the coefficient U2 of the spin-dependent interaction. We show that the ground state exhibits saturated ferromagnetism if U2<0, is spin-singlet if U2>0, and exhibits "SU(3)-ferromagnetism" if U2=0, and completely determine the degeneracy in each region.

  16. 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

  17. 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.

  18. Broadband geodesic pulses for three spin systems: time-optimal realization of effective trilinear coupling terms and indirect SWAP gates.

    PubMed

    Reiss, Timo O; Khaneja, Navin; Glaser, Steffen J

    2003-11-01

    Broadband implementations of time-optimal geodesic pulse elements are introduced for the efficient creation of effective trilinear coupling terms for spin systems consisting of three weakly coupled spins 1/2. Based on these pulse elements, the time-optimal implementation of indirect SWAP operations is demonstrated experimentally. The duration of indirect SWAP gates based on broadband geodesic sequence is reduced by 42.3% compared to conventional approaches.

  19. Experimental simulation of quantum tunneling in small systems.

    PubMed

    Feng, Guan-Ru; Lu, Yao; Hao, Liang; Zhang, Fei-Hao; Long, Gui-Lu

    2013-01-01

    It is well known that quantum computers are superior to classical computers in efficiently simulating quantum systems. Here we report the first experimental simulation of quantum tunneling through potential barriers, a widespread phenomenon of a unique quantum nature, via NMR techniques. Our experiment is based on a digital particle simulation algorithm and requires very few spin-1/2 nuclei without the need of ancillary qubits. The occurrence of quantum tunneling through a barrier, together with the oscillation of the state in potential wells, are clearly observed through the experimental results. This experiment has clearly demonstrated the possibility to observe and study profound physical phenomena within even the reach of small quantum computers.

  20. Transition to Complicated Behavior in Infinite Dimensional Dynamical Systems

    DTIC Science & Technology

    1990-03-01

    2] is related to the Haldane’s conjecture that there is a gap in the spectrum of the spin-1 Heisenberg chain. This numerical study was the first to...1/2 Heisenberg chains,3 submitted to Physical Review B. 4. T. Kennedy, Ornstein-Zernike decay in a quantum spin system, in preparation.I U * 49 * G...Journal of Differential Equations, 81, 2 (1988). I I I ACMS Publication 88-2 72 Werner Ballmann and Maceij P. Wojtkowski An Estimate for the Measure

  1. Isolated many-body quantum systems far from equilibrium: Relaxation process and thermalization

    SciTech Connect

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

    2014-10-15

    We present an overview of our recent numerical and analytical results on the dynamics of isolated interacting quantum systems that are taken far from equilibrium by an abrupt perturbation. The studies are carried out on one-dimensional systems of spins-1/2, which are paradigmatic models of many-body quantum systems. Our results show the role of the interplay between the initial state and the post-perturbation Hamiltonian in the relaxation process, the size of the fluctuations after equilibration, and the viability of thermalization.

  2. Effects of interactions on periodically driven dynamically localized systems

    NASA Astrophysics Data System (ADS)

    Agarwala, Adhip; Sen, Diptiman

    2017-01-01

    It is known that there are lattice models in which noninteracting particles get dynamically localized when periodic δ -function kicks are applied with a particular strength. We use both numerical and analytical methods to study the effects of interactions in three different models in one dimension. The systems we have considered include spinless fermions with interactions between nearest-neighbor sites, the Hubbard model of spin-1/2 fermions, and the Bose-Hubbard model with on-site interactions. We derive effective Floquet Hamiltonians up to second order in the time period of kicking. Using these we show that interactions can give rise to a variety of interesting results such as two-body bound states in all three models and dispersionless few-particle bound states with more than two particles for spinless fermions and bosons. We substantiate these results by exact diagonalization and stroboscopic time evolution of systems with a few particles. We derive a pseudo-spin-1/2 limit of the Bose-Hubbard system in the thermodynamic limit and show that a special case of this has an exponentially large number of degenerate eigenstates of the effective Hamiltonian. Finally, we study the effect of changing the strength of the δ -function kicks slightly away from perfect dynamical localization; we find that a single particle remains dynamically localized for a long time after which it moves ballistically.

  3. 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.

  4. Real-time simulation of nonequilibrium transport of magnetization in large open quantum spin systems driven by dissipation

    NASA Astrophysics Data System (ADS)

    Banerjee, D.; Hebenstreit, F.; Jiang, F.-J.; Wiese, U.-J.

    2015-09-01

    Using quantum Monte Carlo, we study the nonequilibrium transport of magnetization in large open strongly correlated quantum spin-1/2 systems driven by purely dissipative processes that conserve the uniform or staggered magnetization, disregarding unitary Hamiltonian dynamics. We prepare both a low-temperature Heisenberg ferromagnet and an antiferromagnet in two parts of the system that are initially isolated from each other. We then bring the two subsystems in contact and study their real-time dissipative dynamics for different geometries. The flow of the uniform or staggered magnetization from one part of the system to the other is described by a diffusion equation that can be derived analytically.

  5. Spin segregation via dynamically induced long-range interactions in a system of ultracold fermions

    SciTech Connect

    Ebling, Ulrich; Eckardt, Andre; Lewenstein, Maciej

    2011-12-15

    We investigate theoretically the time evolution of a one-dimensional system of spin-1/2 fermions in a harmonic trap after, initially, a spiral spin configuration far from equilibrium is created. We predict a spin segregation building up in time already for weak interaction under realistic experimental conditions. The effect relies on the interplay between exchange interaction and the harmonic trap, and it is found for a wide range of parameters. It can be understood as a consequence of an effective, dynamically induced long-range interaction that is derived by integrating out the rapid oscillatory dynamics in the trap.

  6. Quantitative analysis of Earth's field NMR spectra of strongly-coupled heteronuclear systems.

    PubMed

    Halse, Meghan E; Callaghan, Paul T; Feland, Brett C; Wasylishen, Roderick E

    2009-09-01

    In the Earth's magnetic field, it is possible to observe spin systems consisting of unlike spins that exhibit strongly coupled second-order NMR spectra. Such spectra result when the J-coupling between two unlike spins is of the same order of magnitude as the difference in their Larmor precession frequencies. Although the analysis of second-order spectra involving only spin-(1/2) nuclei has been discussed since the early days of NMR spectroscopy, NMR spectra involving spin-(1/2) nuclei and quadrupolar (I>(1/2)) nuclei have rarely been treated. Two examples are presented here, the tetrahydroborate anion, BH4-, and the ammonium cation, NH4+. For the tetrahydroborate anion, (1)J((11)B,(1)H)=80.9Hz, and in an Earth's field of 53.3microT, nu((1)H)=2269Hz and nu((11)B)=728Hz. The (1)H NMR spectra exhibit features that both first- and second-order perturbation theory are unable to reproduce. On the other hand, second-order perturbation theory adequately describes (1)H NMR spectra of the ammonium anion, (14)NH4+, where (1)J((14)N,(1)H)=52.75Hz when nu((1)H)=2269Hz and nu((14)N)=164Hz. Contrary to an early report, we find that the (1)H NMR spectra are independent of the sign of (1)J((14)N,(1)H). Exact analysis of two-spin systems consisting of quadrupolar nuclei and spin-(1/2) nuclei are also discussed.

  7. Generation of squeezing in a driven many-body system

    NASA Astrophysics Data System (ADS)

    Hebbe Madhusudhana, Bharath; Boguslawski, Matthew; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael

    2016-05-01

    In a spin-1 Bose-Einstein condensate, the non-linear spin-dependent collisional interactions can create entanglement and squeezing. Typically, the condensate is initialized at an unstable fixed point of the phase space, and subsequent free evolution under a time-independent Hamiltonian creates the squeezed state. Alternatively, it is possible to generate squeezing by driving the system localized at a stable fixed point. Here, we demonstrate that periodic modulation of the Hamiltonian can generate highly squeezed states. Our measurements show -5 dB of squeezing, limited by the detection, but calculations indicate that a theoretical potential of -20 dB of squeezing. We discuss the advantages of this method compared with the typical techniques.

  8. 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.

  9. Exploring the limits of polarization transfer efficiency in homonuclear three spin systems.

    PubMed

    Neves, Jorge L; Heitmann, Björn; Reiss, Timo O; Schor, Heloiza H R; Khaneja, Navin; Glaser, Steffen J

    2006-07-01

    The limits of polarization transfer efficiency are explored for systems consisting of three isotropically coupled spins 1/2 in the absence of relaxation. An idealized free evolution and control Hamiltonian is studied, which provides an upper limit of transfer efficiency (in terms of transfer amplitude and transfer time) for realistic homonuclear spin systems with arbitrary Heisenberg-type coupling constants J12, J13, and J23. It is shown that optimal control based pulse sequences have significantly improved transfer efficiencies compared to conventional transfer schemes. An experimental demonstration of optimal polarization transfer is given for the case of the carbon spin system of fully 13C labelled alanine at 62.5 MHz Larmor frequency.

  10. Structure and magnetic properties of the spin-1/2-based honeycomb NaNi2BiO(6-δ) and its hydrate NaNi2BiO(6-δ)·1.7H2O.

    PubMed

    Seibel, Elizabeth M; Roudebush, John H; Ali, Mazhar N; Ross, K A; Cava, R J

    2014-10-20

    We present the structure and magnetic properties of the honeycomb anhydrate NaNi2BiO6-δ and its monolayer hydrate NaNi2BiO6-δ·1.7H2O, synthesized by deintercalation of the layered α-NaFeO2-type honeycomb compound Na3Ni2BiO6. The anhydrate adopts ABAB-type oxygen packing and a one-layer hexagonal unit cell, whereas the hydrate adopts an oxygen packing sequence based on a three-layer rhombohedral subcell. The metal-oxide layer separations are 5.7 Å in the anhydrate and 7.1 Å in the hydrate, making the hydrate a quasi 2-D honeycomb system. The compounds were characterized through single crystal diffraction, powder X-ray diffraction, thermogravimetric analysis, and elemental analysis. Temperature-dependent magnetic susceptibility measurements show both to have negative Weiss temperatures (-18.5 and -14.6 K, respectively) and similar magnetic moments (2.21 and 2.26 μB/Ni, respectively), though the field-dependent magnetization and heat capacity data suggest subtle differences in their magnetic behavior. The magnetic moments per Ni are relatively high, which we suggest is due to the presence of a mixture of Ni(2+) and Ni(3+) caused by oxygen vacancies.

  11. Nonequilibrium dynamics of a system with two kinds of fermions after a pulse

    NASA Astrophysics Data System (ADS)

    Zvyagin, A. A.

    2017-02-01

    The nonequilibrium evolution of the system of two kinds of fermions under the action of a pulse of the external field has been studied. The number of fermions of each kind oscillates (with beats and decaying) as a function of the duration of the pulse about the value determined by the magnitude of the pulse, and as a function of the magnitude of the pulse. For low-dimensional systems those oscillations can serve as a non-zero-temperature manifestation of dynamical quantum phase transitions. The response of a Fermi gas or liquid in a tilted magnetic field, an edge state of a topological insulator, a quantum wire with spin-orbit coupling, and a dimerized spin-1/2 chain to the pulse can manifest such dynamical oscillations, which can be observed in experiments.

  12. 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.

  13. 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.

  14. 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.

  15. Universal relations for the two-dimensional spin-1/2 Fermi gas with contact interactions

    SciTech Connect

    Valiente, Manuel; Zinner, Nikolaj T.; Moelmer, Klaus

    2011-12-15

    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.

  16. Surface waves on the spin-1/2 quantum magnetoplasma half-space

    NASA Astrophysics Data System (ADS)

    Zhu, Jun

    2015-01-01

    We present a theoretical investigation on the propagation of surface waves on the magnetized degenerate electron plasma half-space with spin effects. Using magnetohydrodynamic model with quantum effects due to the Bohm potential, Fermi degenerate pressure and electron spin, the dispersion relations of surface plasmon polaritons (SPPs) are derived. The dispersion relation of electrostatic surface waves is also obtained by taking electrostatic limit.

  17. Orbitally Degenerate Spin-1 Model for Insulating V{sub 2}O{sub 3}

    SciTech Connect

    Mila, F.; Shiina, R.; Zhang, F.-C.; Joshi, A.; Ma, M.; Anisimov, V.; Rice, T. M.

    2000-08-21

    Motivated by recent neutron, x-ray absorption, and resonant scattering experiments, we revisit the electronic structure of V{sub 2}O {sub 3} . We propose a model in which S=1 V{sup 3+} ions are coupled in the vertical V-V pairs forming twofold orbitally degenerate configurations with S=2 . Ferro-orbital ordering of the V-V pairs gives a description which is consistent with all experiments in the antiferromagnetic insulating phase. (c) 2000 The American Physical Society.

  18. Magnetic structure of the spin-1/2 layer compound NaNiO2

    NASA Astrophysics Data System (ADS)

    Darie, C.; Bordet, P.; de Brion, S.; Holzapfel, M.; Isnard, O.; Lecchi, A.; Lorenzo, J. E.; Suard, E.

    2005-01-01

    We have carried out high resolution neutron powder diffraction experiments aiming at a determination of the magnetic structure of the S=1/2 layer compound NaNiO2. The magnetic moments are ferromagnetically aligned in the NiO2 layers and antiparallel between layers. The direction of the magnetic moment has a small component along the a-direction.

  19. Anomalous curie response of impurities in quantum-critical spin-1/2 Heisenberg antiferromagnets.

    PubMed

    Höglund, Kaj H; Sandvik, Anders W

    2007-07-13

    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)10.1126/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*.

  20. Susceptibility of the 2D spin-1 / 2 Heisenberg antiferromagnet with an impurity.

    PubMed

    Höglund, Kaj H; Sandvik, Anders W

    2003-08-15

    We use a quantum Monte Carlo method (stochastic series expansion) to study the effects of a magnetic or nonmagnetic impurity on the magnetic susceptibility of the two-dimensional Heisenberg antiferromagnet. At low temperatures, we find a log-divergent contribution to the transverse susceptibility. We also introduce an effective few-spin model that can quantitatively capture the differences between magnetic and nonmagnetic impurities at high and intermediate temperatures.

  1. Geometric versus numerical optimal control of a dissipative spin-(1)/(2) particle

    NASA Astrophysics Data System (ADS)

    Lapert, M.; Zhang, Y.; Braun, M.; Glaser, S. J.; Sugny, D.

    2010-12-01

    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.

  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. Electromagnetic modes and gravitational instability of spin-1/2 magneto degenerate plasma

    NASA Astrophysics Data System (ADS)

    Sharma, Prerana; Rimza, Tripti

    2017-03-01

    We have studied self-gravitational instability using the two fluid model in which the important role of spin effect (due to spin quantum force and spin magnetization current) is established in highly magnetized and degenerate astrophysical environment of pulsar magnetosphere. Along with this; low frequency, high frequency modes of magnetosonic and magnetohydrodynamic waves were carried out discovering its utility in highly magnetized and degenerate astrophysical environments. The plasma is considered to be composed of degenerate electrons and non-degenerate ions and the quantum effects are incorporated via spin and diffraction effects along with the thermal effect of ions. The spin and quantum dominance are discussed analytically and numerically using the dispersion relation in parallel, perpendicular and oblique mode of propagation. The present study can be implemented on highly magnetized white dwarfs, neutron stars and pulsar magnetosphere (with strong magnetic field B0 ≤ 10^{10} T) and to degenerate laboratory environments.

  4. Relaxation of antiferromagnetic order in spin-1/2 chains following a quantum quench.

    PubMed

    Barmettler, Peter; Punk, Matthias; Gritsev, Vladimir; Demler, Eugene; Altman, Ehud

    2009-04-03

    We study the unitary time evolution of antiferromagnetic order in anisotropic Heisenberg chains that are initially prepared in a pure quantum state far from equilibrium. Our analysis indicates that the antiferromagnetic order imprinted in the initial state vanishes exponentially. Depending on the anisotropy parameter, oscillatory or nonoscillatory relaxation dynamics is observed. Furthermore, the corresponding relaxation time exhibits a minimum at the critical point, in contrast to the usual notion of critical slowing down, from which a maximum is expected.

  5. Quantum Phase Transitions in Conventional Matrix Product Systems

    NASA Astrophysics Data System (ADS)

    Zhu, Jing-Min; Huang, Fei; Chang, Yan

    2017-02-01

    For matrix product states(MPSs) of one-dimensional spin-1/2 chains, we investigate a new kind of conventional quantum phase transition(QPT). We find that the system has two different ferromagnetic phases; on the line of the two ferromagnetic phases coexisting equally, the system in the thermodynamic limit is in an isolated mediate-coupling state described by a paramagnetic state and is in the same state as the renormalization group fixed point state, the expectation values of the physical quantities are discontinuous, and any two spin blocks of the system have the same geometry quantum discord(GQD) within the range of open interval (0,0.25) and the same classical correlation(CC) within the range of open interval (0,0.75) compared to any phase having no any kind of correlation. We not only realize the control of QPTs but also realize the control of quantum correlation of quantum many-body systems on the critical line by adjusting the environment parameters, which may have potential application in quantum information fields and is helpful to comprehensively and deeply understand the quantum correlation, and the organization and structure of quantum correlation especially for long-range quantum correlation of quantum many-body systems.

  6. Proposal for measuring the finite-temperature Drude weight of integrable systems

    NASA Astrophysics Data System (ADS)

    Karrasch, C.; Prosen, T.; Heidrich-Meisner, F.

    2017-02-01

    Integrable models such as the spin-1/2 Heisenberg chain, the Lieb-Liniger, or the one-dimensional Hubbard model are known to avoid thermalization, which was also demonstrated in several quantum-quench experiments. Another dramatic consequence of integrability is the zero-frequency anomaly in transport coefficients, which results in ballistic finite-temperature transport, despite the presence of strong interactions. While this aspect of nonergodic dynamics has been known for a long time, there has so far not been any unambiguous experimental realization thereof. We make a concrete proposal for the observation of ballistic transport via local quantum-quench experiments in fermionic quantum-gas microscopes. Such an experiment would also unveil the coexistence of ballistic and diffusive transport channels in one and the same system and provide a means of measuring finite-temperature Drude weights. The connection between local quenches and linear-response functions is established via time-dependent Einstein relations.

  7. Simulating the exchange of Majorana zero modes with a photonic system

    NASA Astrophysics Data System (ADS)

    Xu, Jin-Shi; Sun, Kai; Han, Yong-Jian; Li, Chuan-Feng; Pachos, Jiannis K.; Guo, Guang-Can

    2016-10-01

    The realization of Majorana zero modes is in the centre of intense theoretical and experimental investigations. Unfortunately, their exchange that can reveal their exotic statistics needs manipulations that are still beyond our experimental capabilities. Here we take an alternative approach. Through the Jordan-Wigner transformation, the Kitaev's chain supporting two Majorana zero modes is mapped to the spin-1/2 chain. We experimentally simulated the spin system and its evolution with a photonic quantum simulator. This allows us to probe the geometric phase, which corresponds to the exchange of two Majorana zero modes positioned at the ends of a three-site chain. Finally, we demonstrate the immunity of quantum information encoded in the Majorana zero modes against local errors through the simulator. Our photonic simulator opens the way for the efficient realization and manipulation of Majorana zero modes in complex architectures.

  8. Compensation behavior of a ferrimagnetic nanoparticle system with binary alloy shell

    NASA Astrophysics Data System (ADS)

    Zaim, N.; Zaim, A.; Kerouad, M.

    2016-11-01

    The phase diagrams and the magnetic properties of a spherical ferrimagnetic nanoparticle, consisting of a ferromagnetic core of atoms A with spin-1/2 (SA = 1 / 2) surrounded by a disordered ferrimagnetic binary alloy shell of two kinds of atoms (A and B) with different spins (SA = 1 / 2 and SB = 3 / 2) are studied by using Monte Carlo simulation based on the Metropolis algorithm. Depending on the values of the Hamiltonian parameters, the system presents a number of outstanding phenomena, such as the possibility of one, two or even three compensation point(s). The existence of a compensation temperature is an interesting phenomenon with important technological applications in the field of thermomagnetic recording.

  9. Simulating the exchange of Majorana zero modes with a photonic system

    PubMed Central

    Xu, Jin-Shi; Sun, Kai; Han, Yong-Jian; Li, Chuan-Feng; Pachos, Jiannis K.; Guo, Guang-Can

    2016-01-01

    The realization of Majorana zero modes is in the centre of intense theoretical and experimental investigations. Unfortunately, their exchange that can reveal their exotic statistics needs manipulations that are still beyond our experimental capabilities. Here we take an alternative approach. Through the Jordan–Wigner transformation, the Kitaev's chain supporting two Majorana zero modes is mapped to the spin-1/2 chain. We experimentally simulated the spin system and its evolution with a photonic quantum simulator. This allows us to probe the geometric phase, which corresponds to the exchange of two Majorana zero modes positioned at the ends of a three-site chain. Finally, we demonstrate the immunity of quantum information encoded in the Majorana zero modes against local errors through the simulator. Our photonic simulator opens the way for the efficient realization and manipulation of Majorana zero modes in complex architectures. PMID:27779181

  10. 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.

  11. The thermodynamic cost of driving quantum systems by their boundaries.

    PubMed

    Barra, Felipe

    2015-10-08

    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.

  12. 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

  13. Model of resistances in systems of Tomonaga-Luttinger liquid wires

    NASA Astrophysics Data System (ADS)

    Soori, Abhiram; Sen, Diptiman

    2011-07-01

    In a recent paper, we combined the technique of bosonization with the concept of a Rayleigh dissipation function to develop a model for resistances in one-dimensional systems of interacting spinless electrons [Europhys. Lett.EULEEJ0295-507510.1209/0295-5075/93/57007 93, 57007 (2011)]. We also studied the conductance of a system of three wires by using a current splitting matrix M at the junction. In this paper, we extend our earlier work in several ways. The power dissipated in a three-wire system is calculated as a function of M and the voltages applied in the leads. By combining two junctions of three wires, we examine a system consisting of two parallel resistances. We study the conductance of this system as a function of the M matrices and the two resistances; we find that the total resistance is generally quite different from what one expects for a classical system of parallel resistances. We do a sum over paths to compute the conductance of this system when one of the two resistances is taken to be infinitely large. We study the conductance of a three-wire system of interacting spin-1/2 electrons, and show that the charge and spin conductances can generally be different from each other. Finally, we consider a system of two wires that are coupled by a dissipation function, and we show that this leads to a current in one wire when a voltage bias is applied across the other wire.

  14. 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.

  15. 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.

  16. 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.

  17. Simulation of spin dynamics: a tool in MRI system development

    NASA Astrophysics Data System (ADS)

    Stöcker, Tony; Vahedipour, Kaveh; Shah, N. Jon

    2011-05-01

    Magnetic Resonance Imaging (MRI) is a routine diagnostic tool in the clinics and the method of choice in soft-tissue contrast medical imaging. It is an important tool in neuroscience to investigate structure and function of the living brain on a systemic level. The latter is one of the driving forces to further develop MRI technology, as neuroscience especially demands higher spatiotemporal resolution which is to be achieved through increasing the static main magnetic field, B0. Although standard MRI is a mature technology, ultra high field (UHF) systems, at B0 >= 7 T, offer space for new technical inventions as the physical conditions dramatically change. This work shows that the development strongly benefits from computer simulations of the measurement process on the basis of a semi-classical, nuclear spin-1/2 treatment given by the Bloch equations. Possible applications of such simulations are outlined, suggesting new solutions to the UHF-specific inhomogeneity problems of the static main field as well as the high-frequency transmit field.

  18. Localized and propagating excitations in gapped phases of spin systems with bond disorder

    NASA Astrophysics Data System (ADS)

    Utesov, O. I.; Sizanov, A. V.; Syromyatnikov, A. V.

    2014-10-01

    Using the conventional T-matrix approach, we discuss gapped phases in one-, two-, and three-dimensional (3D) spin systems (both with and without a long-range magnetic order) with bond disorder and with weakly interacting bosonic elementary excitations. This work is motivated by recent experimental and theoretical activity in spin-liquid-like systems with disorder and in the disordered interacting boson problem. In particular, we apply our theory to both paramagnetic low-field and fully polarized high-field phases in dimerized spin-1/2 systems and in integer-spin magnets with large single-ion easy-plane anisotropy D with disorder in exchange coupling constants (and/or D). The elementary excitation spectrum and the density of states are calculated in the first order in defects concentration c ≪1. In 2D and 3D systems, the scattering on defects leads to a finite damping of all propagating excitations in the band except for states lying near its edges. We demonstrate that the analytical approach is inapplicable for states near the band edges and our numerical calculations reveal their localized nature. We find that the damping of propagating excitations can be much more pronounced in considered systems than in magnetically ordered gapless magnets with impurities. In 1D systems, the disorder leads to localization of all states in the band, while those lying far from the band edges (short-wavelength excitations) can look like conventional wave packets.

  19. 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.

  20. Classification of "multipole" superconductivity in multiorbital systems and its implications

    NASA Astrophysics Data System (ADS)

    Nomoto, T.; Hattori, K.; Ikeda, H.

    2016-11-01

    Motivated by a growing interest in multiorbital superconductors with spin-orbit interactions, we perform the group-theoretical classification of various unconventional superconductivity emerging in symmorphic O , D4, and D6 space groups. The generalized Cooper pairs, which we here call "multipole" superconductivity, possess spin-orbital coupled (multipole) degrees of freedom, instead of the conventional spin singlet/triplet in single-orbital systems. From the classification, we obtain the following key consequences, which have never been focused in the long history of research in this field: (1) A superconducting gap function with Γ9⊗Γ9 in D6 possesses nontrivial momentum dependence different from the usual spin-1/2 classification. (2) Unconventional gap structure can be realized in the BCS approximation of purely local (onsite) interactions irrespective of attraction/repulsion. It implies the emergence of an electron-phonon (e-ph) driven unconventional superconductivity. (3) Reflecting symmetry of orbital basis functions there appear not symmetry protected but inevitable line nodes/gap minima, and thus, anisotropic s -wave superconductivity can be naturally explained even in the absence of competing fluctuations.

  1. Manipulating and probing the polarisation of a methyl tunnelling system by field-cycling NMR

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Abu-Khumra, Sabah M. M.; Aibout, Abdellah; Horsewill, Anthony J.

    2017-02-01

    In NMR the polarisation of the Zeeman system may be routinely probed and manipulated by applying resonant rf pulses. As with spin-1/2 nuclei, at low temperature the quantum tunnelling states of a methyl rotor are characterised by two energy levels and it is interesting to consider how these tunnelling states might be probed and manipulated in an analogous way to nuclear spins in NMR. In this paper experimental procedures based on magnetic field-cycling NMR are described where, by irradiating methyl tunnelling sidebands, the polarisations of the methyl tunnelling systems are measured and manipulated in a prescribed fashion. At the heart of the technique is a phenomenon that is closely analogous to dynamic nuclear polarisation and the solid effect where forbidden transitions mediate polarisation transfer between 1H Zeeman and methyl tunnelling systems. Depending on the irradiated sideband, both positive and negative polarisations of the tunnelling system are achieved, the latter corresponding to population inversion and negative tunnelling temperatures. The transition mechanics are investigated through a series of experiments and a theoretical model is presented that provides good quantitative agreement.

  2. 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.

  3. Dipolar Coupling Information in Multispin Systems: Application of a Compensated REDOR NMR Approach to Inorganic Phosphates

    NASA Astrophysics Data System (ADS)

    Chan, Jerry C. C.; Eckert, Hellmut

    2000-12-01

    Anexperimental strategy has been developed for measuring multiple dipole-dipole interactions in inorganic compounds using the technique of rotational echo double resonance (REDOR) NMR. Geometry-independent information about the dipole couplings between the observe nuclear species S (arbitrary quantum number) and the heteronuclear species I (spin-{1}/{2}) can be conveniently obtained from the experimental curve of ΔS/S0 versus dipolar evolution time by limiting the analysis to the initial data range 0 < ΔS/S0 < 0.30. Numerical simulations have been carried out on a three-spin system of type SI2 in order to assess the effect of the I-I homonuclear dipole-dipole coupling and the influence of experimental imperfections such as finite pulse length and misadjustments of the 180° pulses applied to the I-spin species. The simulations show further that within the initial data range the effects of such misadjustments can be internally compensated by a modified sequence having an additional 180° pulse on the I channel in the middle of the dipolar evolution periods. Experimental 27Al{31P} REDOR results on the multispin systems Al(PO3)3, AlPO4, [AlPO4]12(C3H7)4NF, and Na3PO4 confirm the general utility of this approach. Thus, for applications to unknown systems the compensation strategy obviates calibration procedures with model compounds.

  4. Zero level of a purely magnetic two-dimensional nonrelativistic Pauli operator for SPIN-1/2 particles

    NASA Astrophysics Data System (ADS)

    Grinevich, P. G.; Mironov, A. E.; Novikov, S. P.

    2010-09-01

    We study the manifold of complex Bloch-Floquet eigenfunctions for the zero level of a two-dimensional nonrelativistic Pauli operator describing the propagation of a charged particle in a periodic magnetic field with zero flux through the elementary cell and a zero electric field. We study this manifold in full detail for a wide class of algebraic-geometric operators. In the nonzero flux case, the Pauli operator ground state was found by Aharonov and Casher for fields rapidly decreasing at infinity and by Dubrovin and Novikov for periodic fields. Algebraic-geometric operators were not previously known for fields with nonzero flux because the complex continuation of "magnetic" Bloch-Floquet eigenfunctions behaves wildly at infinity. We construct several nonsingular algebraic-geometric periodic fields (with zero flux through the elementary cell) corresponding to complex Riemann surfaces of genus zero. For higher genera, we construct periodic operators with interesting magnetic fields and with the Aharonov-Bohm phenomenon. Algebraic-geometric solutions of genus zero also generate soliton-like nonsingular magnetic fields whose flux through a disc of radius R is proportional to R (and diverges slowly as R → ∞). In this case, we find the most interesting ground states in the Hilbert space L 2 (ℝ 2 ).

  5. Gelified Biofluids for High-Resolution Magic Angle Spinning (1)H NMR Analysis: The Case of Urine.

    PubMed

    Takis, Panteleimon G; Tenori, Leonardo; Ravera, Enrico; Luchinat, Claudio

    2017-01-17

    In this letter, we propose an alternative, effective protocol for metabolomic characterization of biofluids based on their gelification and subsequent application of high-resolution magic angle spinning (HRMAS) (1)H nuclear magnetic resonance (NMR). The sample handling is very rapid and reproducible, and much less than 40 μL of neat urine are needed to obtain a sample. Our results indicate that the HRMAS spectra of gelified urine encompass all metabolites in the NMR fingerprint, as observed by solution NMR. The proposed approach can be efficiently integrated into the NMR based metabolomics analyses routines: multivariate statistical analysis of both solution and HRMAS data produced very similar statistical models, with high classification accuracy. One of the key advantages offered by the gelification approach is the improved short-term (up to 24 h) preservation of nonfrozen HRMAS NMR gel urine samples compared to the solution samples, which could lead to an alternative way for transportation or domestic collection of biofluids, without the need of cold-storage and reducing the risks of leakage.

  6. On polarization parameters of spin-1 particles and anomalous couplings in e^+e^-→ ZZ/Zγ

    NASA Astrophysics Data System (ADS)

    Rahaman, Rafiqul; Singh, Ritesh K.

    2016-10-01

    We study the anomalous trilinear gauge couplings of Z and γ using a complete set of polarization asymmetries for the Z boson in e^+e^-→ ZZ/Zγ processes with unpolarized initial beams. We use these polarization asymmetries, along with the cross section, to obtain a simultaneous limit on all the anomalous couplings using the Markov Chain Monte Carlo (MCMC) method. For an e^+e^- collider running at 500 GeV center-of-mass energy and 100 fb^{-1} of integrated luminosity the simultaneous limits on the anomalous couplings are 1-3× 10^{-3}.

  7. Ground States of Spin-1/2 Heisenberg Antiferromagnets with Frustration on a Diamond-Like-Decorated Square Lattice

    NASA Astrophysics Data System (ADS)

    Hirose, Yuhei; Oguchi, Akihide; Fukumoto, Yoshiyuki

    2017-01-01

    We study the ground-state phase diagram of a Heisenberg model with spin S = 1/2 on a diamond-like-decorated square lattice. A diamond unit has two types of antiferromagnetic exchange interactions, and the ratio λ of the length of the diagonal bond to that of the other four edges determines the strength of frustration. It has been pointed out [J. Phys. Soc. Jpn 85, 033705 (2016)] that the so-called tetramer-dimer states, which are expected to be stabilized in an intermediate region of λc < λ < 2, are identical to the square-lattice dimer-covering states, which ignited renewed interest in high-dimensional diamond-like-decorated lattices. In order to determine the phase boundary λc, we employ the modified spin wave method to estimate the energy of the ferrimagnetic state and obtain λc = 0.974. Furthermore, our numerical diagonalization study suggests that other cluster states do not appear in the ground-state phase diagram.

  8. Robust conversion of singlet spin order in coupled spin-1/2 pairs by adiabatically ramped RF-fields.

    PubMed

    Pravdivtsev, Andrey N; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L

    2016-12-01

    We propose a robust and highly efficient NMR technique to create singlet spin order from longitudinal spin magnetization in coupled spin-½ pairs and to perform backward conversion (singlet order)→magnetization. In this method we exploit adiabatic ramping of an RF-field in order to drive transitions between the singlet state and the T± triplet states of a spin pair under study. We demonstrate that the method works perfectly for both strongly and weakly coupled spin pairs, providing a conversion efficiency between the singlet spin order and magnetization, which is equal to the theoretical maximum. We anticipate that the proposed technique is useful for generating long-lived singlet order, for preserving spin hyperpolarization and for analyzing singlet spin order in nearly equivalent spin pairs in specially designed molecules and in low-field NMR studies.

  9. 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.

  10. Reentrant phenomena in a three-dimensional spin-1 planar ferromagnet with easy-axis single-ion anisotropy

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The two-time Green function method is employed to explore the phase diagram and the magnetic-field-induced quantum criticality of a three-dimensional spin-one planar ferromagnet with easy-axis single-ion anisotropy. We adopt the Tyablikov and Anderson-Callen decouplings for higher order exchange and single-ion anisotropy Green functions, respectively. The central finding is that, within a characteristic range of the anisotropy parameter values, reentrant phenomena occur in the phase diagram close to the quantum critical point producing a sensible change of the conventional quantum critical scenario.

  11. Magnetic Field versus Temperature Phase Diagram of the Spin-1/2 Alternating-Bond Chain Compound F5PNN

    NASA Astrophysics Data System (ADS)

    Yoshida, Yasuo; Kawae, Tatsuya; Hosokoshi, Yuko; Inoue, Katsuya; Maeshima, Nobuya; Okunishi, Kouichi; Okamoto, Kiyomi; Sakai, Toru

    2009-07-01

    We have measured the specific heat of the S = 1/2 alternating-bond Heisenberg antiferromagnetic chain compound pentafluorophenyl nitronyl nitroxide in magnetic fields using a single crystal and powder. A sharp peak due to field-induced magnetic ordering (FIMO) is observed in both samples. The H-T phase boundary of the FIMO of the single crystal is symmetric with respect to the central field of the gapless field region HC1≤ H≤ HC2, whereas it is distorted for the powder whose ordering temperatures are lower. We discuss possibility that an effective pressure caused by mixing the powder with grease, which is reported for various organic compounds, plays an important role for the distorted phase boundary. An analysis employing calculations based on the finite temperature density matrix renormalization group suggests that the pressure-induced frustration enhances incommensurate spin correlation leading to the distorted phase boundary for the powder.

  12. Superposition of scalar and residual dipolar couplings: analytical transfer functions for three spins 1/2 under cylindrical mixing conditions.

    PubMed

    Luy, B; Glaser, S J

    2001-01-01

    The superposition of scalar and residual dipolar couplings gives rise to so-called cylindrical mixing Hamiltonians in dipolar coupling spectroscopy. General analytical polarization and coherence transfer functions are presented for three cylindrically coupled spins 12 under energy-matched conditions. In addition, the transfer efficiency is analyzed as a function of the relative coupling constants for characteristic special cases.

  13. Monte Carlo study of magnetic properties for the mixed spin-3/2 and spin-1 ferrimagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, Liqin; Zhang, Jianmin; Chen, Zhigao; Feng, Qian; Huang, Zhigao

    2010-01-01

    Based on Monte Carlo simulation, the magnetic properties of the ferrimagnetic nanoparticles on a body-centered-cubic lattice are investigated. The particle is described by a mixed-spin Heisenberg model in which S=3/2 and σ=1 are distributed in the two interpenetrating square sublattices. It is found that no compensation point occurs at finite temperature when only the nearest-neighbor interaction between S- σ spins is included. But, when the next-nearest-neighbor interaction between σ- σ spins is taken into account and exceeds a threshold value that depends on the other parameters such as the next-nearest-neighbor interaction between S- S spins and single-ion anisotropies in the Hamiltonian, a compensation point can appear. With the appropriate order parameter which is constructed to characterize the compensation behavior clearly, a variety of phase diagrams including the finite-size effect are derived and discussed.

  14. Stripe order on the spin-1 stacked honeycomb lattice in Ba2Ni (PO4)2

    NASA Astrophysics Data System (ADS)

    Yogi, Arvind; Bera, A. K.; Maurya, Arvind; Kulkarni, Ruta; Yusuf, S. M.; Hoser, A.; Tsirlin, A. A.; Thamizhavel, A.

    2017-01-01

    We report a comprehensive investigation of the crystal structure and magnetic behavior of the S =1 compound Ba2Ni (PO4)2 with a honeycomblike topology of the spin lattice. Magnetic susceptibility and specific-heat data reveal two successive transitions at TN 1=5 K and TN 2=4.6 K . Additionally, these data demonstrate a broad peak at Tmax˜8 K , indicative of the short-range magnetic order above TN 1, whereas below TN 1 field-induced transitions around 4 and 10 T are identified from the magnetization measurements. Neutron diffraction in zero field establishes stripe antiferromagnetic order below TN 2 with the ordered moment of 1.75 (8 ) μB/Ni2 + at 1.5 K. Density-functional band-structure calculations reveal the leading interaction J3=3.5 K running perpendicular to the honeycomb planes, and weaker interactions J1=0.5 K and J4=1.8 K within the honeycomb planes, whereas the stripe order is stabilized by the diagonal interlayer interaction J2=1.3 K that frustrates J1. This is in contrast to the usually expected scenario where the competing second- and third-neighbor interactions on the honeycomb lattice stabilize the stripe order. The Ni2 + ions feature a sizable easy-plane anisotropy A ≃10.5 K , but the position of the easy plane changes from one atom to another, thus amplifying magnetic frustration.

  15. Modified Jeans instability of magnetized viscous spin 1/2 quantum plasma with resistive effects and Hall current

    NASA Astrophysics Data System (ADS)

    Sharma, Prerana; Chhajlani, R. K.

    2014-07-01

    The effect of Hall current on Jeans self-gravitational instability is examined for finitely conducting dense quantum viscous plasma in the presence of spin generated magnetization. The basic equations of the problem are constructed using quantum magneto hydrodynamic (QMHD) model. The Hall and resistivity terms are incorporated in the idealized Ohm's law and spin induced magnetization and viscosity terms are incorporated to the momentum equations. The general dispersion relation is found to be modified due to the presence of Hall current, electrical resistivity and viscosity parameter along with the spin induced magnetization. The dispersion relation is further reduced for both transverse and longitudinal mode of propagations. In the transverse mode of propagation the Jeans condition of instability is modified due to Alfven velocity, magnetization parameter and quantum corrections, and the growth rate of instability is found to be modified due to the electrical resistivity, viscosity, magnetization parameter and quantum corrections but remains unaffected by the presence of Hall current. In longitudinal direction of propagation the gravitational mode is affected due to the viscosity and quantum parameter while the Jeans condition of instability depends only upon the quantum correction. The Alfven mode in longitudinal direction gets modified due to the electrical resistivity, Hall current, viscosity and magnetization parameter however, it is found to be independent of quantum corrections. The numerical observations are also presented to show the effect of electrical resistivity, magnetization and quantum corrections on the growth rate of instability.

  16. 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.

  17. 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.

  18. 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.

  19. Effects of the interplay between initial state and Hamiltonian on the thermalization of isolated quantum many-body systems.

    PubMed

    Torres-Herrera, E J; Santos, Lea F

    2013-10-01

    We explore the role of the initial state on the onset of thermalization in isolated quantum many-body systems after a quench. The initial state is an eigenstate of an initial Hamiltonian H(I) and it evolves according to a different final Hamiltonian H(F). If the initial state has a chaotic structure with respect to H(F), i.e., if it fills the energy shell ergodically, thermalization is certain to occur. This happens when H(I) is a full random matrix, because its states projected onto H(F), are fully delocalized. The results for the observables then agree with those obtained with thermal states at infinite temperature. However, finite real systems with few-body interactions, as the ones considered here, are deprived of fully extended eigenstates, even when described by a nonintegrable Hamiltonian. We examine how the initial state delocalizes as it gets closer to the middle of the spectrum of H(F), causing the observables to approach thermal averages, be the models integrable or chaotic. Our numerical studies are based on initial states with energies that cover the entire lower half of the spectrum of one-dimensional Heisenberg spin-1/2 systems.

  20. Immune System

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Immune System KidsHealth > For Teens > Immune System A A A ... could put us out of commission. What the Immune System Does The immune (pronounced: ih-MYOON) system, which ...

  1. Universal Fermi liquid crossover and quantum criticality in a mesoscopic system.

    PubMed

    Keller, A J; Peeters, L; Moca, C P; Weymann, I; Mahalu, D; Umansky, V; Zaránd, G; Goldhaber-Gordon, D

    2015-10-08

    Quantum critical systems derive their finite-temperature properties from the influence of a zero-temperature quantum phase transition. The paradigm is essential for understanding unconventional high-Tc superconductors and the non-Fermi liquid properties of heavy fermion compounds. However, the microscopic origins of quantum phase transitions in complex materials are often debated. Here we demonstrate experimentally, with support from numerical renormalization group calculations, a universal crossover from quantum critical non-Fermi liquid behaviour to distinct Fermi liquid ground states in a highly controllable quantum dot device. Our device realizes the non-Fermi liquid two-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally to two independent electronic reservoirs. On detuning the exchange couplings we observe the Fermi liquid scale T*, at energies below which the spin is screened conventionally by the more strongly coupled channel. We extract a quadratic dependence of T* on gate voltage close to criticality, and validate an asymptotically exact description of the universal crossover between strongly correlated non-Fermi liquid and Fermi liquid states.

  2. 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.

  3. 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.

  4. The Thermodynamic Properties of Some Integrable Systems.

    NASA Astrophysics Data System (ADS)

    Lee, Kong-Ju-Bock

    I discuss the thermodynamic properties of integrable quantum systems, in particular, generalizations of the Heisenberg chain and the one-dimensional Hubbard model, by making use of the Bethe-Ansatz technique. For the Heisenberg chain the following properties are obtained: (1) The critical behavior of the SU(2) invariant ferromagnet with spin S is studied, yielding critical exponents alpha = -1/2, nu = 1, and gamma = 2 for the specific heat, the correlation length, and the susceptibility, respectively. (2) An integrable SU(2) invariant model of the spin 1 Heisenberg chain interacting with an impurity of spin S is constructed. At low temperature for ferromagnetic coupling the impurity follows the critical behavior of the chain, i.e., alpha = -1/2 and gamma = 2. For antiferromagnetic coupling the impurity susceptibility for S = 1/2 diverges logarithmically as H to 0, while for S > 1 the impurity spin is partially compensated by the spins of the chain. (3) The linear coefficient gamma of the low temperature specific heat for the S = 1/2 Heisenberg antiferromagnetic chain is anomalous as H to 0, i.e.,limlimits _{Tto 0} limlimits _{Hto 0} gamma = 2/3 ne limlimits_{Hto 0 } limlimits_{Tto 0} gamma = [ 1+(e/pi) ^{1/2}]/3.. I obtained the following results for the one-dimensional Hubbard model: (1) The thermodynamic Bethe-Ansatz equations for the Hubbard chain with an attractive on-site interaction U are derived. The results are discussed in special limits, e.g., U to infty, U to 0, T to infty, and T to 0. (2) The thermodynamic integral equations for the attractive Hubbard chain are solved numerically at low temperature. At low T the dominant states consist of Cooper pairs and their excitations. A critical field is obtained at T = 0, which disappears for T ne 0. the dependence of the low temperature specific heat coefficient gamma on band filling and magnetic field is obtained. The excitation spectrum is discussed in the context of superconductivity and resonant valence

  5. Data Systems vs. Information Systems

    PubMed Central

    Amatayakul, Margret K.

    1982-01-01

    This paper examines the current status of “hospital information systems” with respect to the distinction between data systems and information systems. It is proposed that the systems currently existing are incomplete data dystems resulting in ineffective information systems.

  6. Operating Systems.

    ERIC Educational Resources Information Center

    Denning, Peter J.; Brown, Robert L.

    1984-01-01

    A computer operating system spans multiple layers of complexity, from commands entered at a keyboard to the details of electronic switching. In addition, the system is organized as a hierarchy of abstractions. Various parts of such a system and system dynamics (using the Unix operating system as an example) are described. (JN)

  7. Respiratory System

    MedlinePlus

    ... this page from the NHLBI on Twitter. The Respiratory System The respiratory system is made up of organs ... vessels, and the muscles that enable breathing. The Respiratory System Figure A shows the location of the respiratory ...

  8. Lymph system

    MedlinePlus

    Lymphatic system ... Dains JE, Flynn JA, Solomon BS, Stewart RW. Lymphatic system. In: Ball JW, Dains JE, Flynn JA, Solomon ... 2015:chap 9. Hall JE. The microcirculation and lymphatic system: capillary fluid exchange, interstitial fluid, and lymph flow. ...

  9. Digestive System

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Digestive System KidsHealth > For Parents > Digestive System A A A ... the body can absorb and use. About the Digestive System Almost all animals have a tube-type digestive ...

  10. Mechanical Systems

    NASA Technical Reports Server (NTRS)

    Davis, Robert E.

    2002-01-01

    The presentation provides an overview of requirement and interpretation letters, mechanical systems safety interpretation letter, design and verification provisions, and mechanical systems verification plan.

  11. 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…

  12. Synthesis, structure and magnetic properties of low dimensional spin systems in the 3d transition metal oxides and superconductivity in magnesium borate

    NASA Astrophysics Data System (ADS)

    Rogado, Nyrissa S.

    The major part of this thesis deals with the synthesis and magnetic characterization of low dimensional spin systems in the 3d transition metal oxides. Such systems are of interest due to the simplicity of their structures, allowing theoretical modeling of their electronic and magnetic behavior. Exotic properties are also often encountered. Studies involving layered magnetic materials based on triangle lattices, in particular, have resulted in many observations of unusual low temperature spin dynamics, and have presented new challenges for the theoretical understanding of magnetic systems. The magnetic properties of some compounds exhibiting these triangle-based lattices are described here in detail. BaNi2V2O8 is a spin-1 antiferromagnet on a honeycomb net. Susceptibility chi(T), specific heat C(T), and neutron diffraction measurements on this compound reveal the onset of antiferromagnetic (AFM) long-range ordering (LRO) close to 50 K. Diffuse diffraction peaks that are characteristic of two-dimensional (2D) short-range order are also observed up to 100 K. chi(T) of Ba(Ni1-xMgx)2V 2O8 shows the gradual disappearance of LRO with doping. Ni3V2O8, Co3V2O 8, and beta-Cu3V2O8 have spin-1, spin-3/2, and spin-1/2 magnetic lattices that are a new anisotropic variant of the Kagome net, wherein edge-sharing MO6 octahedra form the rises and rungs of a "Kagome staircase". The anisotropy largely relieves the geometric frustration, but results in rich magnetic behavior. Characterization of the magnetization of polycrystalline samples of Ni 3V2O8 and Co3V2O8 reveals that the compounds are ferrimagnetic in character. C(T) show four distinct magnetic phase transitions below 9 K for Ni3V2O 8 and two below 11 K for Co3V2O8. In the case of beta-Cu3V2O8, chi(T) and C(T) show the onset of short-range ordering at approximately 75 K, and a magnetic phase transition with the characteristics of antiferromagnetism at around 29 K. The second part of this thesis describes the bulk synthesis of

  13. 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.

  14. Supersymmetry of the planar Dirac-Deser-Jackiw-Templeton system and of its nonrelativistic limit

    SciTech Connect

    Horvathy, Peter A.; Valenzuela, Mauricio; Plyushchay, Mikhail S.

    2010-09-15

    The planar Dirac and the topologically massive vector gauge fields are unified into a supermultiplet involving no auxiliary fields. The super-Poincare symmetry emerges from the osp(1|2) supersymmetry realized in terms of the deformed Heisenberg algebra underlying the construction. The nonrelativistic limit yields spin 1/2 as well as new, spin 1 ''Levy-Leblond-type'' equations which, together, carry an N=2 super-Schroedinger symmetry. Part of the latter has its origin in the universal enveloping algebra of the super-Poincare algebra.

  15. Explicit contextualized hidden-variable model replicating an indivisible quantum system

    NASA Astrophysics Data System (ADS)

    Plick, William N.; Lapkiewicz, Radek

    2014-02-01

    Recent experiments and theory have further illuminated the concept of "quantum contextuality." In this paper we take an inequality—the pentagram (or KCBS) inequality, which is violated by an unentangled spin-1 system—and given a relaxed assumption of noncontextuality show that a hidden-variable model may be constructed that replicates exactly the quantum bound. This is in contrast to the case of an entangled pair of spin-1/2 particles where a similar relaxation of the assumption of locality does not lead to a replication of the quantum bound. Some reasons are proposed for why this may be the case.

  16. 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.

  17. Systems thinking.

    PubMed

    Cabrera, Derek; Colosi, Laura; Lobdell, Claire

    2008-08-01

    Evaluation is one of many fields where "systems thinking" is popular and is said to hold great promise. However, there is disagreement about what constitutes systems thinking. Its meaning is ambiguous, and systems scholars have made diverse and divergent attempts to describe it. Alternative origins include: von Bertalanffy, Aristotle, Lao Tsu or multiple aperiodic "waves." Some scholars describe it as synonymous with systems sciences (i.e., nonlinear dynamics, complexity, chaos). Others view it as taxonomy-a laundry list of systems approaches. Within so much noise, it is often difficult for evaluators to find the systems thinking signal. Recent work in systems thinking describes it as an emergent property of four simple conceptual patterns (rules). For an evaluator to become a "systems thinker", he or she need not spend years learning many methods or nonlinear sciences. Instead, with some practice, one can learn to apply these four simple rules to existing evaluation knowledge with transformative results.

  18. Telemetry Systems

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Goddard Space Flight Center developed satellite telemetry processing technology to meet NASA's sophisticated processing requirements. The Microelectronic Systems Branch, a 'company' within Goddard, provided NASA with the telemetry data systems from 1985 to 1994. TSI/Telsys, Inc. was then founded to commercialize the systems and began operations on October 1, 1995. The system aids the remote sensing industry by providing affordable and quick access to data collected from space.

  19. 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.

  20. 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

  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. 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.

  3. CALUTRON SYSTEM

    DOEpatents

    Lawrence, E.O.

    1958-08-12

    A calutron system capable of functioning with only a portion of the separation tanks in the system operating is described. The invention is a calutron system comprssing a closed series of alternated tanks and electromagnets having a mid-yoke connecting intermediate positions of the series. dividing the series into twv-o portions, and thereby providing a closed magnetic path through either of the portions.

  4. Systemic Darwinism

    PubMed Central

    Winther, Rasmus Grønfeldt

    2008-01-01

    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

  5. 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.

  6. 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

  7. Nonperturbative linked-cluster expansions in long-range ordered quantum systems

    NASA Astrophysics Data System (ADS)

    Ixert, Dominik; Schmidt, Kai Phillip

    2016-11-01

    We introduce a generic scheme to perform nonperturbative linked cluster expansions in long-range ordered quantum phases. Clusters are considered to be surrounded by an ordered reference state leading to effective edge fields in the exact diagonalization on clusters, which break the associated symmetry of the ordered phase. Two approaches, based either on a self-consistent solution of the order parameter or on minimal sensitivity with respect to the ground-state energy per site, are formulated to find the optimal edge field in each NLCE order. Furthermore, we investigate the scaling behavior of the NLCE data sequences towards the infinite-order limit. We apply our scheme to gapped and gapless ordered phases of XXZ Heisenberg models on various lattices and for spins 1/2 and 1 using several types of cluster expansions ranging from a full-graph decomposition, rectangular clusters, up to more symmetric square clusters. It is found that the inclusion of edge fields allows to regularize nonperturbative linked-cluster expansions in ordered phases yielding convergent data sequences. This includes the long-range spin-ordered ground state of the spin-1/2 and spin-1 Heisenberg model on the square and triangular lattice as well as the trimerized valence bond crystal of the spin-1 Heisenberg model on the kagome lattice.

  8. Ultracold Mixtures of Rubidium and Ytterbium for Open Quantum System Engineering

    DTIC Science & Technology

    2014-06-01

    ric to the t ube with aluminum spacers at either end. The Zeeman slower provides a significant increase in the Rb beam phase space 42 250x103 - 0...Ludlow, Z. Barber, T. Fortier, S. Diddams, Y. Jiang, S. Jefferts, T. Heavner, T. Parker , and C. Oates, “Spin-1/2 optical lattice clock,” Physical

  9. 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.

  10. 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

  11. Phacoemulsification systems.

    PubMed

    1989-11-01

    Our objectives in conducting this evaluation were to present an overview of a basic phacoemulsification system and its components, to describe the phacoemulsification procedure within the context of the operating principles of the system's components, and to compare two manufacturers' products. Specifications for additional phacoemulsification systems are available in the November 1989 edition of ECRI's Hospital Product Comparison System. Both of the evaluated systems enable a surgeon to perform a complete cataract extraction procedure by phacoemulsification. We rated both units Acceptable. In selecting a unit, users should consider performance, safety, human factors design, and manufacturer training and support. Although list prices vary widely among available systems, cost factors should not override clinical performance and safety requirements. While we measured certain engineering parameters, such as stroke length and ultrasound (US) output forces exerted on a medium, we stress that the results of these tests do not provide enough information to predict clinical performance. Clinical performance of phacoemulsification systems can be determined only by the experience of the clinicians who use them. Clinicians should review our evaluation thoroughly before making a purchasing decision. The information we present is useful for purchasing the evaluated or other available models because our criteria will guide users in assessing all components, and our findings and discussion on some aspects are common to many available systems (e.g., type of pump, irrigation and aspiration [I/A] characteristics). The in-depth clinical and technical information will help users to better understand principles, thereby helping them to better define their needs. Although we discovered a number of problems with the evaluated models, users should not assume that similar or other problems do not exist with systems that we did not evaluate. The willingness of manufacturers to cooperate in

  12. 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.)

  13. 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

  14. Systems Vaccinology

    PubMed Central

    Pulendran, Bali; Li, Shuzhao; Nakaya, Helder I

    2010-01-01

    Vaccination is one of the greatest triumphs of modern medicine, yet we remain largely ignorant of the mechanisms by which successful vaccines stimulate protective immunity. Two recent advances are beginning to illuminate such mechanisms: realization of the pivotal role of the innate immune system in sensing microbes and stimulating adaptive immunity, and advances in systems biology. Recent studies have used systems biology approaches to obtain a global picture of the immune responses to vaccination in humans. This has enabled the identification of early innate signatures that predict the immunogenicity of vaccines, and identification of potentially novel mechanisms of immune regulation. Here we review these advances, and critically examine the potential opportunities and challenges posed by systems biology in vaccine development. PMID:21029962

  15. 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.

  16. Bioculture System

    NASA Technical Reports Server (NTRS)

    Figliozzi, Gianine; Sato, Kevin Y.; Sun. Sidney

    2013-01-01

    The document is a 2 page fact sheet that describes the Bioculture system, how it may be used by researchers for life science research, how and when it will be installed and validated aboard the international space station.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Robotic System

    NASA Technical Reports Server (NTRS)

    1984-01-01

    A complicated design project, successfully carried out by New York manufacturing consultant with help from NERAC, Inc., resulted in new type robotic system being marketed for industrial use. Consultant Robert Price, operating at E.S.I, Inc. in Albany, NY, sought help from NERAC to develop an automated tool for deburring the inside of 8 inch breech ring assemblies for howitzers produced by Watervliet Arsenal. NERAC conducted a search of the NASA data base and six others. From information supplied, Price designed a system consisting of a standard industrial robot arm, with a specially engineered six-axis deburring tool fitted to it. A microcomputer and computer program direct the tool on its path through the breech ring. E.S.I. markets the system to aerospace and metal cutting industries for deburring, drilling, routing and refining machined parts.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. International Systems.

    ERIC Educational Resources Information Center

    Saba, Farhad, Ed.

    1999-01-01

    Completes a discussion of a systems model of distance education (in articles since May 1999) focusing on the most complex level, international. Discussion includes transfer of technology from United States universities to developing nations, the free market, and the age of the global economy. Presents a list of "early indicators" of changes in…

  9. 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.

  10. Instructional Systems.

    ERIC Educational Resources Information Center

    Banathy, Bela H.

    The underlying assumption of this book is that the systems approach has a dual role in education. "As applied 'in' education, it offers a powerful methodology for decisionmaking and design development. As applied 'to' education, it may bring about a clear understanding of what education is truly about." The essential purpose of the book is to…

  11. 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...

  12. 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…

  13. Exploring Enterprise, System of Systems, and System and Software Architectures

    DTIC Science & Technology

    2016-06-13

    2009 Carnegie Mellon University Exploring Enterprise, System of Systems, and System and Software Architectures Software Engineering Institute...TITLE AND SUBTITLE Exploring Enterprise, System of Systems, and System and Software Architectures 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...Carnegie Mellon University, Software Engineering Institute,Pittsburgh,PA,15213 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY

  14. 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.

  15. Solar Systems

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The solar collectors shown are elements of domestic solar hot water systems produced by Solar One Ltd., Virginia Beach, Virginia. Design of these systems benefited from technical expertise provided Solar One by NASA's Langley Research Center. The company obtained a NASA technical support package describing the d e sign and operation of solar heating equipment in NASA's Tech House, a demonstration project in which aerospace and commercial building technology are combined in an energy- efficient home. Solar One received further assistance through personal contact with Langley solar experts. The company reports that the technical information provided by NASA influenced Solar One's panel design, its selection of a long-life panel coating which increases solar collection efficiency, and the method adopted for protecting solar collectors from freezing conditions.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. Systemic Assurance

    DTIC Science & Technology

    2015-07-31

    to, warranty of fitness for purpose or merchantability, exclusivity, or results obtained from use of the material. Stevens Institute of Technology...customer organizations judge them fit for use in the mission environment. These assurance judgments must be based on evidence that a system manifests...which it is achieved. Assurance is a human judgment of fitness for use. This judgment is thus contextualized by the mission definition, the features

  2. 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...

  3. CONTROL SYSTEM

    DOEpatents

    Shannon, R.H.; Williamson, H.E.

    1962-10-30

    A boiling water type nuclear reactor power system having improved means of control is described. These means include provisions for either heating the coolant-moderator prior to entry into the reactor or shunting the coolantmoderator around the heating means in response to the demand from the heat engine. These provisions are in addition to means for withdrawing the control rods from the reactor. (AEC)

  4. Bioregenerative system

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The design course is an eight semester credit multi-disciplinary engineering design course taught primarily to Engineering Science, Aerospace, Electrical and Mechanical Engineering seniors. This year the course project involved the design of the three interrelated loops: atmospheric, liquid nutrient and solid waste management, associated with growing higher plants to support man during long-term space missions. The project is complementary to the NASA Kennedy Space Center Controlled Environmental Life Support System (CELSS) project. The first semester the class worked on a preliminary design for a complete system. This effort included means for monitoring and control of composition, temperature, flow rate, etc., for the atmosphere and liquid nutrient solution; disease and contaminant monitoring and control; plant mechanical support, propagation and harvesting; solid and liquid waste recycling; and system maintenance and refurbishing. The project has significant biological, mechanical, electrical and Al/Robotics aspects. The second semester a small number of subsystems or components, identified as important and interesting during the first semester, were selected for detail design, fabrication, and testing. The class was supported by close cooperation with The Kennedy Space Center and by two teaching assistants. The availability of a dedicated, well equipped project room greatly enhanced the communication and team spirit of the class.

  5. 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.

  6. 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

  7. Spin Gap in the Zigzag Spin-1/2 Chain Cuprate Sr0.9Ca0.1CuO2

    NASA Astrophysics Data System (ADS)

    Hammerath, F.; Nishimoto, S.; Grafe, H.-J.; Wolter, A. U. B.; Kataev, V.; Ribeiro, P.; Hess, C.; Drechsler, S.-L.; Büchner, B.

    2011-07-01

    We report a comparative study of Cu63 nuclear magnetic resonance spin lattice relaxation rates T1-1 on undoped SrCuO2 and Ca-doped Sr0.9Ca0.1CuO2 spin chain compounds. A temperature independent T1-1 is observed for SrCuO2 as expected for an S=1/2 Heisenberg chain. Surprisingly, we observe an exponential decrease of T1-1 for T<90K in the Ca-doped sample evidencing the opening of a spin gap. The data analysis within the J1-J2 Heisenberg model employing density-matrix renormalization group calculations suggests an impurity driven small alternation of the J2-exchange coupling as a possible cause of the spin gap.

  8. 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.

  9. Muon-spin relaxation measurements on the dimerized spin- 1/2 chains NaTiSi2O6 and TiOCl

    NASA Astrophysics Data System (ADS)

    Baker, P. J.; Blundell, S. J.; Pratt, F. L.; Lancaster, T.; Brooks, M. L.; Hayes, W.; Isobe, M.; Ueda, Y.; Hoinkis, M.; Sing, M.; Klemm, M.; Horn, S.; Claessen, R.

    2007-03-01

    We report muon spin relaxation (μSR) and magnetic susceptibility investigations of two Ti3+(S=1/2) chain compounds, NaTiSi2O6 and TiOCl, each of which exhibits a spin gap at low temperature. From these we conclude that the spin gap in NaTiSi2O6 , which arises from orbital ordering at TOO=210K , is temperature independent below TOO , with a value of 2Δ=700(100)K . In TiOCl, we find thermally activated spin fluctuations corresponding to a spin gap 2Δ=440(60)K below Tc1=67K . We can describe both the μSR and susceptibility data in terms of a model based on the dimerization of the Ti3+ chains. We also compare the methods used to extract the spin gap and the concentration of free spins within the samples from μSR and magnetic susceptibility data.

  10. 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.

  11. Magnetic Excitations and Electronic Interactions in Sr2 CuTeO6 : A Spin-1 /2 Square Lattice Heisenberg Antiferromagnet

    NASA Astrophysics Data System (ADS)

    Babkevich, P.; Katukuri, Vamshi M.; Fâk, B.; Rols, S.; Fennell, T.; Pajić, D.; Tanaka, H.; Pardini, T.; Singh, R. R. P.; Mitrushchenkov, A.; Yazyev, O. V.; Rønnow, H. M.

    2016-12-01

    Sr2 CuTeO6 presents an opportunity for exploring low-dimensional magnetism on a square lattice of S =1 /2 Cu2 + ions. We employ ab initio multireference configuration interaction calculations to unravel the Cu2 + electronic structure and to evaluate exchange interactions in Sr2 CuTeO6 . The latter results are validated by inelastic neutron scattering using linear spin-wave theory and series-expansion corrections for quantum effects to extract true coupling parameters. Using this methodology, which is quite general, we demonstrate that Sr2 CuTeO6 is an almost ideal realization of a nearest-neighbor Heisenberg antiferromagnet but with relatively weak coupling of 7.18(5) meV.

  12. Solid-state NMR adiabatic TOBSY sequences provide enhanced sensitivity for multidimensional high-resolution magic-angle-spinning 1H MR spectroscopy

    NASA Astrophysics Data System (ADS)

    Andronesi, Ovidiu C.; Mintzopoulos, Dionyssios; Struppe, Jochem; Black, Peter M.; Tzika, A. Aria

    2008-08-01

    We propose a solid-state NMR method that maximizes the advantages of high-resolution magic-angle-spinning (HRMAS) applied to intact biopsies when compared to more conventional liquid-state NMR approaches. Theoretical treatment, numerical simulations and experimental results on intact human brain biopsies are presented. Experimentally, it is proven that an optimized adiabatic TOBSY (TOtal through Bond correlation SpectroscopY) solid-state NMR pulse sequence for two-dimensional 1H- 1H homonuclear scalar-coupling longitudinal isotropic mixing provides a 20%-50% improvement in signal-to-noise ratio relative to its liquid-state analogue TOCSY (TOtal Correlation SpectroscopY). For this purpose we have refined the C9151 symmetry-based 13C TOBSY pulse sequence for 1H MRS use and compared it to MLEV-16 TOCSY sequence. Both sequences were rotor-synchronized and implemented using WURST-8 adiabatic inversion pulses. As discussed theoretically and shown in simulations, the improved magnetization-transfer comes from actively removing residual dipolar couplings from the average Hamiltonian. Importantly, the solid-state NMR techniques are tailored to perform measurements at low temperatures where sample degradation is reduced. This is the first demonstration of such a concept for HRMAS metabolic profiling of disease processes, including cancer, from biopsies requiring reduced sample degradation for further genomic analysis.

  13. First-principles determination of Heisenberg Hamiltonian parameters for the spin-(1)/(2) kagome antiferromagnet ZnCu3(OH)6Cl2

    NASA Astrophysics Data System (ADS)

    Jeschke, Harald O.; Salvat-Pujol, Francesc; Valentí, Roser

    2013-08-01

    Herbertsmithite [ZnCu3(OH)6Cl2] is often discussed as the best realization of the highly frustrated antiferromagnetic kagome lattice known so far. We employ density functional theory (DFT) calculations to determine eight exchange coupling constants of the underlying Heisenberg Hamiltonian. We find the nearest-neighbor coupling J1 to exceed all other couplings by far. However, next-nearest-neighbor kagome layer couplings of 0.019J1 and interlayer couplings of up to -0.035J1 slightly modify the perfect antiferromagnetic kagome Hamiltonian. Interestingly, the largest interlayer coupling is ferromagnetic, even without Cu impurities in the Zn layer. In addition, we validate our DFT approach by applying it to kapellasite, a polymorph of herbertsmithite, which is known experimentally to exhibit competing exchange interactions.

  14. High-resolution magic angle spinning (1)H magnetic resonance spectroscopy detects choline as a biomarker in a swine obstructive chronic pancreatitis model at an early stage.

    PubMed

    Sun, Gaofeng; Wang, Jianhua; Zhang, Jian; Ma, Chao; Shao, Chengwei; Hao, Jun; Zheng, Jianming; Feng, Xiaoyuan; Zuo, Changjing

    2014-03-04

    Chronic pancreatitis (CP) is a progressive inflammatory and fibrotic disease of the pancreas which encompasses a variety of clinical syndromes ranging from mild to life-threatening complications. Metabolomics has increasingly been applied to identify biomarkers for disease diagnosis with particular interest in diseases at an early stage. In this study, we tested a swine obstructive CP model by subtotal ligation of the main pancreatic duct, and the metabolic profiles of the Bama miniature swine pancreas were investigated using high-resolution magic angle spinning proton magnetic resonance spectroscopy (HR MAS (1)H MRS) combined with principal components analysis (PCA). Increases in lactate and choline for mild CP and decreases in glycerophosphocholine, phosphocholine, betaine and glycine were observed from normal pancreas to mild, moderate and severe CP. PCA results showed visual separations among the groups. The increase of choline at an early stage of CP and the decrease of glycerophosphocholine, phosphocholine, betaine and glycine reveal the pathogenesis of CP at a molecular level. The MRS results presented here demonstrate the potential of metabolic profiles in discriminating a normal pancreas from different stages of CP, which may be used to achieve CP early diagnosis and timely intervention to prevent irreversible destruction of the pancreas.

  15. High-resolution mono- and multidimensional magic angle spinning 1H nuclear magnetic resonance of membrane peptides in nondeuterated lipid membranes and H2O.

    PubMed Central

    Le Guernevé, C; Seigneuret, M

    1996-01-01

    High-speed (14 kHz) solid-state magic angle spinning (MAS) 1H NMR has been applied to several membrane peptides incorporated into nondeuterated dilauroyl or dimyristoylphosphatidylcholine membranes suspended in H2O. It is shown that solvent suppression methods derived from solution NMR, such as presaturation or jump-return, can be used to reduce water resonance, even at relatively high water content. In addition, regioselective excitation of 1H peptide resonances promotes an efficient suppression of lipid resonances, even in cases where these are initially two orders of magnitude more intense. As a consequence, 1H MAS spectra of the peptide low-field region are obtained without interference from water and lipid signals. These display resonances from amide and other exchangeable 1H as well as from aromatic nonexchangeable 1H. The spectral resolution depends on the specific types of resonance and membrane peptide. For small amphiphilic or hydrophobic oligopeptides, resolution of most individual amide resonance is achieved, whereas for the transmembrane peptide gramicidin A, an unresolved amide spectrum is obtained. Partial resolution of aromatic 1H occurs in all cases. Multidimensional 1H-MAS spectra of membrane peptides can also be obtained by using water suppression and regioselective excitation. For gramicidin A, F2-regioselective 2D nuclear Overhauser effect spectroscopy (NOESY) spectra are dominated by intermolecular through-space connectivities between peptide aromatic or formyl 1H and lipid 1H. These appear to be compatible with the known structure and topography of the gramicidin pore. On the other hand, for the amphiphilic peptide leucine-enkephalin, F2-regioselective NOESY spectra mostly display cross-peaks originating from though-space proximities of amide or aromatic 1H with themselves and with aliphatic 1H. F3-regioselective 3D NOESY-NOESY spectra can be used to obtain through-space correlations within aliphatic 1H. Such intrapeptide proximities should allow determination of the conformation of the peptide in membranes. It is suggested that high-speed MAS multidimensional 1H NMR of peptides in nondeuterated membranes and in H2O can be used for studies of both peptide structure and lipid-peptide interactions. Images FIGURE 8 PMID:8913601

  16. 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.

  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. 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.

  19. 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.

  20. Systems Pharmacology

    PubMed Central

    Boran, Aislyn D. W.; Iyengar, Ravi

    2011-01-01

    We examine how physiology and pathophysiology are studied from a systems perspective, using high-throughput experiments and computational analysis of regulatory networks. We describe the integration of these analyses with pharmacology, which leads to new understanding of drug action and enables drug discovery for complex diseases. Network studies of drug-target relationships can serve as an indication on the general trends in the approved drugs and the drug-discovery progress. There is a growing number of targeted therapies approved and in the pipeline, which meets a new set of problems with efficacy and adverse effects. The pitfalls of these mechanistically based drugs are described, along with how a systems view of drug action is increasingly important to uncover intricate signaling mechanisms that play an important part in drug action, resistance mechanisms, and off-target effects. Computational methodologies enable the classification of drugs according to their structures and to which proteins they bind. Recent studies have combined the structural analyses with analysis of regulatory networks to make predictions about the therapeutic effects of drugs for complex diseases and possible off-target effects. PMID:20687178

  1. 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}.

  2. 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.

  3. Power systems

    NASA Astrophysics Data System (ADS)

    Kaplan, G.

    1982-01-01

    Significant events in current, prototype, and experimental utility power generating systems in 1981 are reviewed. The acceleration of licensing and the renewal of plans for reprocessing of fuel for nuclear power plants are discussed, including the rise of French reactor-produced electricity to over 40% of the country's electrical output. A 4.5 MW fuel cell neared completion in New York City, while three 2.5 MW NASA-designed windpowered generators began producing power in the state of Washington. Static bar compensators, nonflammable-liquid cooled power transformers, and ZnO surge arrestors were used by utilities for the first time, and the integration of a coal gasifier-combined cycle power plant approached the planning phase. An MHD generator was run for 1000 hours and produced 50-60 kWe, while a 20 MVA superconducting generator was readied for testing.

  4. Pumping system

    SciTech Connect

    Kime, J.A.

    1987-05-19

    This patent describes a gas-oil production system for pumping formation fluid in a well through a tubing string within which a down hole pump connects to a hydraulic stroking device through a rod string providing the pump including a plunger reciprocally driven by the hydraulic stroking device toward an upper terminal position during a plunger upstroke. The rod string normally supports the weight of a column of fluid and toward a lower terminal position at the end of a plunger downstroke during which the weight of the column fluid is normally transferred to the tubing string through fluid within the pump. The method for detecting when the well is pumped off comprises: supplying working fluid to the hydraulic stroking device to raise the hydraulic stroking device and thereby move the plunger from the lower terminal position to the upper terminal position; and removing the working fluid at a controlled rate from the hydraulic stroking device.

  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.

  6. 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.

  7. 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.

  8. Systemic vasculitis.

    PubMed

    Sharma, Poonam; Sharma, Sanjeev; Baltaro, Richard; Hurley, John

    2011-03-01

    The systemic vasculitides are characterized by inflammation of blood vessel walls. Vessels of any type, in any organ can be affected, resulting in a broad spectrum of signs and symptoms. The heterogenous nature of vasculitides presents a diagnostic challenge. The American College of Rheumatology classification criteria and the Chapel Hill Consensus Conference nomenclature are the most widely used to distinguish different forms of vasculitis. The Chapel Hill Consensus Conference nomenclature defines 10 primary vasculitides based on vessel size (large, medium, and small). The diagnosis relies on the recognition of a compatible clinical presentation supported by specific laboratory or imaging tests and confirmatory histology. Antineutrophilic cytoplasmic antibody testing has been of particular benefit in defining a subgroup of small vessel vasculitides. Treatment is based on clinical presentation and the pattern of organ involvement. Glucocorticoids are the primary treatment for many forms of vasculitis. Additional immunosuppressive agents, including methotrexate and cyclophosphamide, are sometimes required. Newer approaches, such as the use of anti-tumor necrosis factor or B cell therapies, are being tried in resistant cases. Patients can experience considerable treatment-related toxicity, especially infection from immunosuppressive therapy and adverse effects from steroids (e.g., osteoporosis, diabetes mellitus, cataract). Vitamin D and calcium prophylaxis are recommended in patients on long-term steroid therapy.

  9. Endocrine System (For Teens)

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Endocrine System KidsHealth > For Teens > Endocrine System A A A ... is called the endocrine system . What Is the Endocrine System? Although we rarely think about the endocrine system, ...

  10. 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…

  11. Airborne Global Positioning System Antenna System

    DTIC Science & Technology

    2004-10-14

    GLOBAL POSITIONING SYSTEM ANTENNA SYSTEM DISTRIBUTION: SMC/ GP (3 cys); AFFSA...standard that airborne Global Positioning System ( GPS ) antenna system must meet to be identified with the applicable MSO marking. The similarity of...UNCLASSIFIED DOCUMENT NO. DATE NO. MSO-C144 14 Oct 04 Initial Release REV: REV: SHEET 1 OF 16 TITLE: AIRBORNE GLOBAL POSITIONING SYSTEM

  12. RADAR WARNING SYSTEM,

    DTIC Science & Technology

    RADAR TRACKING, *AIRCRAFT DEFENSE SYSTEMS, RADAR EQUIPMENT, AIR TO AIR, SEARCH RADAR, GUIDED MISSILES, HIGH SPEED BOMBING, EARLY WARNING SYSTEMS, FIRE CONTROL SYSTEM COMPONENTS, AIRCRAFT, TIME, CHINA.

  13. 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.

  14. 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.

  15. From systems biology to systems biomedicine.

    PubMed

    Antony, Paul M A; Balling, Rudi; Vlassis, Nikos

    2012-08-01

    Systems Biology is about combining theory, technology, and targeted experiments in a way that drives not only data accumulation but knowledge as well. The challenge in Systems Biomedicine is to furthermore translate mechanistic insights in biological systems to clinical application, with the central aim of improving patients' quality of life. The challenge is to find theoretically well-chosen models for the contextually correct and intelligible representation of multi-scale biological systems. In this review, we discuss the current state of Systems Biology, highlight the emergence of Systems Biomedicine, and highlight some of the topics and views that we think are important for the efficient application of Systems Theory in Biomedicine.

  16. Global Positioning System Shipborne Reference System

    DTIC Science & Technology

    1997-09-30

    Office of Naval Research Space and Remote Sensing 1997 Annual Report 1 GLOBAL POSITIONING SYSTEM SHIPBORNE REFERENCE SYSTEM James R. Clynch...N00014-97-WR30044 LONG-TERM GOAL The long term goal is to improve the navigation capability of naval vessels using the Global Positioning System ...COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Global Positioning System Shipborne Reference System 5a. CONTRACT NUMBER 5b. GRANT

  17. Mechanical systems: A compilation

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A compilation of several mechanized systems is presented. The articles are contained in three sections: robotics, industrial mechanical systems, including several on linear and rotary systems and lastly mechanical control systems, such as brakes and clutches.

  18. Endocrine System (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Endocrine System KidsHealth > For Parents > Endocrine System A A A ... to help the body function properly. About the Endocrine System The foundations of the endocrine system are the ...

  19. Immune System (For Parents)

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Immune System KidsHealth > For Parents > Immune System A A A ... can lead to illness and infection. About the Immune System The immune system is the body's defense against ...

  20. Quantify information system benefits

    SciTech Connect

    Koppel, L.B.

    1995-06-01

    What are information systems and how do they relate to control systems? How do information systems produce benefits in hydrocarbon processing? What are some examples of benefit-generating information system applications? Information System Benefits (ISBEN) is a structured methodology for estimating information system benefits in hydrocarbon processing. The paper discusses information and control systems, information system benefits and applications, objectives, strategies and measures of ISBEN, ISBEN business drivers, ISBEN database, ISBEN methodology, and implementation.

  1. Data Systems Task Analysis.

    DTIC Science & Technology

    1979-08-01

    A08873 MARINE CORPS WASHINGTON DC F/B 5/9 DATA SYSTEMS TASK ANALYSIS. (U) "CLASSIFIEO. -%mm . LEVELIs DATA SYSTEMS O0 TASK ANALYSIS DCI) OO JF AUG 28...TECI-NICIAN jl. CCMPUTER SYSTEMS EVALLATOR ,13. LCMPUTER SYSTEMS MANAGER 314. LCMPUTER SYSTEMS MCNITOR A5o LCMPUTER TERMINAL OPERATOR j16. LCNFIGURATION...OPERATOR )27. DATA PROCESSING NCO )28. DATA PROCESSINIG TECHNICIAN 329e DATA SYSTEMS LIBRARIAN )35* DATA SYSTEMS OPERATICNS Cl-IEF 331. DATA SYSTEMS

  2. Practical systems thinking

    NASA Astrophysics Data System (ADS)

    Konkarikoski, K.; Ritala, R.; Ihalainen, H.

    2010-07-01

    System is a dynamic and complex whole, interacting as a structured functional unit. Systems thinking provides tools for understanding a such system structure and its dynamic behavior. Practical systems thinking course teaches first year bachelor students basics about systems and how open problem can be formulated to system task.

  3. 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.

  4. 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.

  5. 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.

  6. [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).

  7. 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.

  8. 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)

  9. 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.

  10. LCLS XTOD Attenuator System System Concept Report

    SciTech Connect

    Kishiyama, K; Roeben, M; Trent, J; Ryutov, D; Shen, S

    2006-04-12

    The attenuator system for the Linac Coherent Light Source (LCLS) X-ray Transport, Optics and Diagnostics (XTOD) system has been configured and analyzed by the Lawrence Livermore National Laboratory's New Technologies Engineering Division (NTED) as requested by the SLAC/LCLS program. The system layout, performance analyses and selection of the vacuum components are presented in this System Conceptual Review (SCR) report. Also included are the plans for prototype, procurement, mechanical integration, and the cost estimates.

  11. Systems Theory, Systems Technology, and Curriculum Design.

    ERIC Educational Resources Information Center

    Pratt, David

    1978-01-01

    John Goodlad (1958) stated that "Nowhere in education is there greater need for a conceptual system to guide decision-making than the field of curriculum." This research attempts to explore ways in which systems thinking can provide a conceptual system, to illuminate the study of curriculum and guide the design of curricula. (Author/RK)

  12. 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.

  13. Novel effects of spin-orbit interaction in interacting electronic systems

    NASA Astrophysics Data System (ADS)

    Sun, Jianmin

    Over the last several years there has been a remarkable growth in research activity in the physical properties of mesoscopic systems. Significant results, which were obtained by both theoretical and experimental studies, together with the enormous promise of nano-technology applications, contribute to this interest. In mesoscopic systems, there are 1023 or so electrons with strong Coulomb interaction. The length scale governing the electrons motion is small enough to cause quantization of the energy levels. In this work we study such quantum systems: quantum wires, quantum dots. During the last decade several experimental techniques have been developed for manufacturing both kinds of devices, which are currently an important tool for understanding low dimensions physics. The finite spin-orbit coupling is very natural, and, strictly speaking, unavoidable, in semiconducting quantum wires due to pronounced structural asymmetry inherent in the fabrication process. Thus the interplay between Coulomb interaction and spin-orbit coupling is important to investigate. The magnetic field also plays an important role which breaks the time-reversal symmetry of the Hamiltonian and splits the band of free electrons into two, corresponding to up-spin and down-spin electrons, reducing spin-rotational symmetry of the system from SU(2) to U(1). The dissertation takes account of the effect of the spin-orbit coupling interactions in the properties of mesoscopic systems. The manuscript is divided in four Chapters. In Chapter 1, the field theory in mesoscopic system is introduced. I present the relations between bosonic and fermionic operators in one dimension. These relations are used to bosonize spin 1/2 interaction fermion system. I show how to derive the RG equations around a fixed-point from the Operator Product Expansion (OPE). In Chapter 2, I present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbital interaction. I show that an

  14. 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…

  15. 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…

  16. Systems Engineering Measurement Primer

    DTIC Science & Technology

    1998-03-01

    Systems Engineering Measurement Primer A Basic Introduction to Systems Engineering Measurement Concepts and Use Version 1.0 March 1998 This document...Federal Systems Garry Roedler Lockheed Martin Management & Data Systems Cathy Tilton The National Registry, Inc. E. Richard Widmann Raytheon Systems...IV 1. INTRODUCTION

  17. 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.

  18. Systems Measures of Water Distribution System Resilience

    SciTech Connect

    Klise, Katherine A.; Murray, Regan; Walker, La Tonya Nicole

    2015-01-01

    Resilience is a concept that is being used increasingly to refer to the capacity of infrastructure systems to be prepared for and able to respond effectively and rapidly to hazardous events. In Section 2 of this report, drinking water hazards, resilience literature, and available resilience tools are presented. Broader definitions, attributes and methods for measuring resilience are presented in Section 3. In Section 4, quantitative systems performance measures for water distribution systems are presented. Finally, in Section 5, the performance measures and their relevance to measuring the resilience of water systems to hazards is discussed along with needed improvements to water distribution system modeling tools.

  19. 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.

  20. 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.

  1. 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

    2015-08-25

    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.

  2. 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.

  3. 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

    2016-10-11

    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.

  4. 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.

  5. 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.

  6. Systems Architecture for a Nationwide Healthcare System.

    PubMed

    Abin, Jorge; Nemeth, Horacio; Friedmann, Ignacio

    2015-01-01

    From a national level to give Internet technology support, the Nationwide Integrated Healthcare System in Uruguay requires a model of Information Systems Architecture. This system has multiple healthcare providers (public and private), and a strong component of supplementary services. Thus, the data processing system should have an architecture that considers this fact, while integrating the central services provided by the Ministry of Public Health. The national electronic health record, as well as other related data processing systems, should be based on this architecture. The architecture model described here conceptualizes a federated framework of electronic health record systems, according to the IHE affinity model, HL7 standards, local standards on interoperability and security, as well as technical advice provided by AGESIC. It is the outcome of the research done by AGESIC and Systems Integration Laboratory (LINS) on the development and use of the e-Government Platform since 2008, as well as the research done by the team Salud.uy since 2013.

  7. DQ-DRENAR: A new NMR technique to measure site-resolved magnetic dipole-dipole interactions in multispin-1/2 systems: Theory and validation on crystalline phosphates

    NASA Astrophysics Data System (ADS)

    Ren, Jinjun; Eckert, Hellmut

    2013-04-01

    A new solid state NMR technique is described for measuring homonuclear dipole-dipole interactions in multi-spin-1/2 systems under magic-angle spinning conditions. Re-coupling is accomplished in the form of an effective double quantum (DQ) Hamiltonian created by a symmetry-based POST-C7 sequence consisting of two excitation blocks, attenuating the signal (intensity S'). For comparison, a reference signal S0 with the dipolar re-coupling absent is generated by shifting the phase of the second block by 90° relative to the first block. As in rotational echo double resonance, the homonuclear dipole-dipole coupling constant can then be extracted from a plot of the normalized difference signal (S0 - S')/S0 versus dipolar mixing time. The method is given the acronym DQ-DRENAR ("Double-Quantum-based Dipolar Re-coupling effects Nuclear Alignment Reduction"). The method is analyzed mathematically, and on the basis of detailed simulations, with respect to the order and the geometry of the spin system, the dipolar truncation phenomenon, and the influence of the chemical shift anisotropy on experimental curves. Within the range of (S0 - S')/S0 ≤0.3-0.5 such DRENAR curves can be approximated by simple parabolae, yielding effective squared dipole-dipole coupling constants summed over all the pairwise interactions present. The method has been successfully validated for 31P-31P distance determinations of numerous crystalline model compounds representing a wide range of dipolar coupling strengths.

  8. TWRSview system requirements specification

    SciTech Connect

    Caldwell, J.A.; Lee, A.K.

    1995-12-01

    This document provides the system requirements specification for the TWRSview software system. The TWRSview software system is being developed to integrate electronic data supporting the development of the TWRS technical baseline

  9. Multivariable Control Systems

    DTIC Science & Technology

    1968-01-01

    one). Examples abound of systems with numerous controlled variables, and the modern tendency is toward ever greater utilization of systems and plants of this kind. We call them multivariable control systems (MCS).

  10. 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 ...

  11. 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.

  12. Air cushion landing system

    NASA Technical Reports Server (NTRS)

    Boghami, K. M.; Captain, K. M.; Fish, R. B.

    1978-01-01

    Static and dynamic performance of air cushion landing system is simulated in computer program that treats four primary ACLS subsystems: fan, feeding system, trunk, and cushion. Configuration of systems is sufficiently general to represent variety of practical designs.

  13. 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.

  14. Lungs and Respiratory System

    MedlinePlus

    ... Your 1- to 2-Year-Old Lungs and Respiratory System KidsHealth > For Parents > Lungs and Respiratory System Print ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't happen ...

  15. The Trinity System

    SciTech Connect

    Archer, Billy Joe; Vigil, Benny Manuel

    2015-01-13

    This paper describes the Trinity system, the first ASC Advanced Technology System (ATS-1). We describe the Trinity procurement timeline, the ASC computing strategy, the Trinity specific mission needs, and the Trinity system specifications.

  16. Lungs and Respiratory System

    MedlinePlus

    ... Your 1- to 2-Year-Old Lungs and Respiratory System KidsHealth > For Parents > Lungs and Respiratory System A ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't happen ...

  17. Evaluating a Portfolio System.

    ERIC Educational Resources Information Center

    Smit, David W.

    1990-01-01

    Contributes to the knowledge of portfolio systems for writing evaluation by sharing evaluative procedures and their results. Reports on the results of a survey of students evaluated using a portfolio system. Finds that students preferred the portfolio system. (RS)

  18. Antiskid braking system

    NASA Technical Reports Server (NTRS)

    Pazdera, J. S.

    1974-01-01

    Published report describes analytical development and simulation of braking system. System prevents wheels from skidding when brakes are applied, significantly reducing stopping distance. Report also presents computer simulation study on system as applied to aircraft.

  19. Digestive System (For Teens)

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Digestive System KidsHealth > For Teens > Digestive System A A A ... out of the body as feces. About the Digestive System Every morsel of food we eat has to ...

  20. Immune System Quiz

    MedlinePlus

    ... Room? What Happens in the Operating Room? Quiz: Immune System KidsHealth > For Kids > Quiz: Immune System A A A How much do you know about your immune system? Find out by taking this quiz! About KidsHealth ...