WorldWideScience

Sample records for one-dimensional fermi gas

  1. Backward scattering in the one-dimensional Fermi gas

    International Nuclear Information System (INIS)

    Apostol, M.

    1980-05-01

    The Ward identity is derived for non-relativistic fermions with two-body spin-independent interaction. Using this identity for the one-dimensional Fermi gas with backward scattering the equations of the perturbation theory are solved for the effective interaction and the collective excitations of the particle density fluctuations are obtained. (author)

  2. Topological phase transition in the quench dynamics of a one-dimensional Fermi gas

    OpenAIRE

    Wang, Pei; Yi, Wei; Xianlong, Gao

    2014-01-01

    We study the quench dynamics of a one-dimensional ultracold Fermi gas in an optical lattice potential with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of t...

  3. Quantum criticality of one-dimensional multicomponent Fermi gas with strongly attractive interaction

    International Nuclear Information System (INIS)

    He, Peng; Jiang, Yuzhu; Guan, Xiwen; He, Jinyu

    2015-01-01

    Quantum criticality of strongly attractive Fermi gas with SU(3) symmetry in one dimension is studied via the thermodynamic Bethe ansatz (TBA) equations. The phase transitions driven by the chemical potential μ, effective magnetic field H 1 , H 2 (chemical potential biases) are analyzed at the quantum criticality. The phase diagram and critical fields are analytically determined by the TBA equations in the zero temperature limit. High accurate equations of state, scaling functions are also obtained analytically for the strong interacting gases. The dynamic exponent z=2 and correlation length exponent ν=1/2 read off the universal scaling form. It turns out that the quantum criticality of the three-component gases involves a sudden change of density of states of one cluster state, two or three cluster states. In general, this method can be adapted to deal with the quantum criticality of multicomponent Fermi gases with SU(N) symmetry. (paper)

  4. Topological phase transition in the quench dynamics of a one-dimensional Fermi gas with spin–orbit coupling

    International Nuclear Information System (INIS)

    Wang, Pei; Yi, Wei; Xianlong, Gao

    2015-01-01

    We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems. (paper)

  5. Topological phase transition in the quench dynamics of a one-dimensional Fermi gas with spin-orbit coupling

    Science.gov (United States)

    Wang, Pei; Yi, Wei; Xianlong, Gao

    2015-01-01

    We study the quench dynamics of a one-dimensional ultracold Fermi gas with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of the pairing gap at a critical quenched interaction strength. We further demonstrate the topological nature of this dynamical phase transition from edge-state analysis of the quenched states. Our findings provide interesting clues for the understanding of topological phase transitions in dynamical processes, and can be useful for the dynamical detection of Majorana edge states in corresponding systems.

  6. Interacting Fermi gases in disordered one-dimensional lattices

    International Nuclear Information System (INIS)

    Xianlong, Gao; Polini, M.; Tosi, M. P.; Tanatar, B.

    2006-01-01

    Interacting two-component Fermi gases loaded in a one-dimensional (1D) lattice and subject to harmonic trapping exhibit intriguing compound phases in which fluid regions coexist with local Mott-insulator and/or band-insulator regions. Motivated by experiments on cold atoms inside disordered optical lattices, we present a theoretical study of the effects of a random potential on these ground-state phases. Within a density-functional scheme we show that disorder has two main effects: (i) it destroys the local insulating regions if it is sufficiently strong compared with the on-site atom-atom repulsion, and (ii) it induces an anomaly in the compressibility at low density from quenching of percolation

  7. An interpolatory ansatz captures the physics of one-dimensional confined Fermi systems

    DEFF Research Database (Denmark)

    Andersen, Molte Emil Strange; Salami Dehkharghani, Amin; Volosniev, A. G.

    2016-01-01

    beyond the Bethe ansatz and bosonisation allow us to predict the behaviour of one-dimensional confined systems with strong short-range interactions, and new experiments with cold atomic Fermi gases have already confirmed these theories. Here we demonstrate that a simple linear combination of the strongly...

  8. Korteweg de Vries Description of One-Dimensional Superfluid Fermi Gases

    International Nuclear Information System (INIS)

    Xu Yan-Xia; Duan Wen-Shan

    2011-01-01

    We study one-dimensional matter-wave pulses in cigar-shaped superfluid Fermi gases, including the linear and nonlinear waves of the system. A Korteweg de Vries (KdV) solitary wave is obtained for the superfluid Fermi gases in the limited case of a BEC regime, a BCS regime and unitarity. The dependences of the propagation velocity, amplitude and the width of the solitary wave on the dimensionless interaction parameter y = 1/(k F a sc ) are given for the limited cases of BEC and unitarity. (physics of gases, plasmas, and electric discharges)

  9. Correlation Functions of the One-Dimensional Attractive Bose Gas

    International Nuclear Information System (INIS)

    Calabrese, Pasquale; Caux, Jean-Sebastien

    2007-01-01

    The zero-temperature correlation functions of the one-dimensional attractive Bose gas with a delta-function interaction are calculated analytically for any value of the interaction parameter and number of particles, directly from the integrability of the model. We point out a number of interesting features, including zero recoil energy for a large number of particles, analogous to the Moessbauer effect

  10. Anomalous heat conduction in a one-dimensional ideal gas.

    Science.gov (United States)

    Casati, Giulio; Prosen, Tomaz

    2003-01-01

    We provide firm convincing evidence that the energy transport in a one-dimensional gas of elastically colliding free particles of unequal masses is anomalous, i.e., the Fourier law does not hold. Our conclusions are confirmed by a theoretical and numerical analysis based on a Green-Kubo-type approach specialized to momentum-conserving lattices.

  11. Fermi surface of the one-dimensional Hubbard model. Finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Bourbonnais, C.; Nelisse, H.; Reid, A.; Tremblay, A.M.S. (Dept. de Physique and Centre de Recherche en Physique du Solide (C.R.P.S.), Univ. de Sherbrooke, Quebec (Canada))

    1989-12-01

    The results reported here, using a standard numerical algorithm and a simple low temperature extrapolation, appear consistent with numerical results of Sorella et al. for the one-dimensional Hubbard model in the half-filled and quarter-filled band cases. However, it is argued that the discontinuity at the Fermi level found in the quarter-filled case is likely to come from the zero-temperature finite-size dependence of the quasiparticle weight Z, which is also discussed here. (orig.).

  12. Fermi-edge singularity in one-dimensional electron systems with long-range Coulomb interactions

    International Nuclear Information System (INIS)

    Otani, H.; Ogawa, T.

    1996-01-01

    Effects of long-range Coulomb interactions on the Fermi-edge singularity in optical spectra are investigated theoretically for one-dimensional spin-1/2 fermion systems with the use of the Tomonaga-Luttinger bosonization technique. Low-energy excitation spectrum near the Fermi level shows that dispersion of the charge-density fluctuation remains gapless but is nonlinear when the electron-electron (e-e) Coulomb interaction is of the x -1 type (i.e., an infinite force range). Temporal behavior of the current-current correlation function is calculated analytically for arbitrary force ranges, λ e and λ h , of the e-e and the electron-hole (e-h) Coulomb interactions. (i) When both the e-e and the e-h interactions have large but finite force ranges (λ e h max[λ e ,λ h ]/v F . Corresponding optical spectrum near the Fermi edge (within an energy range of ℎv F /max[λ e ,λ h ]) exhibits the power-law divergence or the power-law convergence, which is an ordinary Fermi-edge singularity. (ii) When either the e-e or the e-h interaction is of the x -1 type (i.e., λ e →∞ and/or λ h →∞), an exponent of the correlation function is dependent on time to lead the faster decay than that of any power laws. Then the optical spectra show no power law dependence and always converge (become zero) at the Fermi edge, which is in striking contrast to the ordinary power-law singularity

  13. One-Dimensional Rydberg Gas in a Magnetoelectric Trap

    International Nuclear Information System (INIS)

    Mayle, Michael; Hezel, Bernd; Lesanovsky, Igor; Schmelcher, Peter

    2007-01-01

    We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the required linear density of Rydberg atoms

  14. One-dimensional gas of bosons with Feshbach-resonant interactions

    International Nuclear Information System (INIS)

    Gurarie, V.

    2006-01-01

    We present a study of a gas of bosons confined in one dimension with Feshbach-resonant interactions, at zero temperature. Unlike the gas of one-dimensional bosons with non resonant interactions, which is known to be equivalent to a system of interacting spinless fermions and can be described using the Luttinger liquid formalism, the resonant gas possesses additional features. Depending on its parameters, the gas can be in one of three possible regimes. In the simplest of those, it can still be described by the Luttinger liquid theory, but its Fermi momentum cannot be larger than a certain cutoff momentum dependent on the details of the interactions. In the other two regimes, it is equivalent to a Luttinger liquid at low density only. At higher densities its excitation spectrum develops a minimum, similar to the roton minimum in helium, at momenta where the excitations are in resonance with the Fermi sea. As the density of the gas is increased further, the minimum dips below the Fermi energy, thus making the ground state unstable. At this point the standard ground state gets replaced by a more complicated one, where not only the states with momentum below the Fermi points, but also the ones with momentum close to that minimum, get filled, and the excitation spectrum develops several branches. We are unable so far to study this regime in detail due to the lack of the appropriate formalism

  15. Three-Dimensional Non-Fermi-Liquid Behavior from One-Dimensional Quantum Critical Local Moments

    Science.gov (United States)

    Classen, Laura; Zaliznyak, Igor; Tsvelik, Alexei M.

    2018-04-01

    We study the temperature dependence of the electrical resistivity in a system composed of critical spin chains interacting with three-dimensional conduction electrons and driven to criticality via an external magnetic field. The relevant experimental system is Yb2 Pt2 Pb , a metal where itinerant electrons coexist with localized moments of Yb ions which can be described in terms of effective S =1 /2 spins with a dominantly one-dimensional exchange interaction. The spin subsystem becomes critical in a relatively weak magnetic field, where it behaves like a Luttinger liquid. We theoretically examine a Kondo lattice with different effective space dimensionalities of the two interacting subsystems. We characterize the corresponding non-Fermi liquid behavior due to the spin criticality by calculating the electronic relaxation rate and the dc resistivity and establish its quasilinear temperature dependence.

  16. Matter waves of Bose-Fermi mixtures in one-dimensional optical lattices

    International Nuclear Information System (INIS)

    Bludov, Yu. V.; Santhanam, J.; Kenkre, V. M.; Konotop, V. V.

    2006-01-01

    We describe solitary wave excitations in a Bose-Fermi mixture loaded in a one-dimensional and strongly elongated lattice. We focus on the mean-field theory under the condition that the fermion number significantly exceeds the boson number, and limit our consideration to lattice amplitudes corresponding to the order of a few recoil energies or less. In such a case, the fermionic atoms display 'metallic' behavior and are well-described by the effective mass approximation. After classifying the relevant cases, we concentrate on gap solitons and coupled gap solitons in the two limiting cases of large and small fermion density, respectively. In the former, the fermionic atoms are distributed almost homogeneously and thus can move freely along the lattice. In the latter, the fermionic density becomes negligible in the potential maxima, and this leads to negligible fermionic current in the linear regime

  17. Analytical and numerical studies of Bose-Fermi mixtures in a one-dimensional harmonic trap

    Science.gov (United States)

    Dehkharghani, A. S.; Bellotti, F. F.; Zinner, N. T.

    2017-07-01

    In this paper we study a mixed system of bosons and fermions with up to six particles in total. All particles are assumed to have the same mass. The two-body interactions are repulsive and are assumed to have equal strength in both the Bose-Bose and the Fermi-Boson channels. The particles are confined externally by a harmonic oscillator one-body potential. For the case of four particles, two identical fermions and two identical bosons, we focus on the strongly interacting regime and analyze the system using both an analytical approach and density matrix renormalization group calculations using a discrete version of the underlying continuum Hamiltonian. This provides us with insight into both the ground state and the manifold of excited states that are almost degenerate for large interaction strength. Our results show great variation in the density profiles for bosons and fermions in different states for strongly interacting mixtures. By moving to slightly larger systems, we find that the ground state of balanced mixtures of four to six particles tends to separate bosons and fermions for strong (repulsive) interactions. On the other hand, in imbalanced Bose-Fermi mixtures we find pronounced odd-even effects in systems of five particles. These few-body results suggest that question of phase separation in one-dimensional confined mixtures are very sensitive to system composition, both for the ground state and the excited states.

  18. Scattering resonances in a degenerate Fermi gas

    DEFF Research Database (Denmark)

    Challis, Katharine; Nygaard, Nicolai; Mølmer, Klaus

    2009-01-01

    We consider elastic single-particle scattering from a one-dimensional trapped two-component superfluid Fermi gas when the incoming projectile particle is identical to one of the confined species. Our theoretical treatment is based on the Hartree-Fock ground state of the trapped gas...

  19. Interaction quantum quenches in the one-dimensional Fermi-Hubbard model

    Science.gov (United States)

    Heidrich-Meisner, Fabian; Bauer, Andreas; Dorfner, Florian; Riegger, Luis; Orso, Giuliano

    2016-05-01

    We discuss the nonequilibrium dynamics in two interaction quantum quenches in the one-dimensional Fermi-Hubbard model. First, we study the decay of the Néel state as a function of interaction strength. We observe a fast charge dynamics over which double occupancies are built up, while the long-time decay of the staggered moment is controlled by spin excitations, corroborated by the analysis of the entanglement dynamics. Second, we investigate the formation of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) correlations in a spin-imbalanced system in quenches from the noninteracting case to attractive interactions. Even though the quench puts the system at a finite energy density, peaks at the characteristic FFLO quasimomenta are visible in the quasi-momentum distribution function, albeit with an exponential decay of s-wave pairing correlations. We also discuss the imprinting of FFLO correlations onto repulsively bound pairs and their rapid decay in ramps. Supported by the DFG (Deutsche Forschungsgemeinschaft) via FOR 1807.

  20. Higher first Chern numbers in one-dimensional Bose-Fermi mixtures

    Science.gov (United States)

    Knakkergaard Nielsen, Kristian; Wu, Zhigang; Bruun, G. M.

    2018-02-01

    We propose to use a one-dimensional system consisting of identical fermions in a periodically driven lattice immersed in a Bose gas, to realise topological superfluid phases with Chern numbers larger than 1. The bosons mediate an attractive induced interaction between the fermions, and we derive a simple formula to analyse the topological properties of the resulting pairing. When the coherence length of the bosons is large compared to the lattice spacing and there is a significant next-nearest neighbour hopping for the fermions, the system can realise a superfluid with Chern number ±2. We show that this phase is stable in a large region of the phase diagram as a function of the filling fraction of the fermions and the coherence length of the bosons. Cold atomic gases offer the possibility to realise the proposed system using well-known experimental techniques.

  1. Exact results on the one-dimensional Potts lattice gas

    International Nuclear Information System (INIS)

    Riera, R.; Chaves, C.M.G.F.

    1982-12-01

    An exact calculation of the Potts Lattice Gas in one dimension is presented. Close to T=O 0 K, the uniform susceptibility presents an essencial singularity, when the excharge parameter is positive, and a power law behaviour with critical exponent γ=1, when this parameter is negative. (Author) [pt

  2. Exact results on the one-dimensional Potts lattice gas

    International Nuclear Information System (INIS)

    Riera, R.; Chaves, C.M.G.F.

    1983-01-01

    An exact calculation of the Potts Lattice Gas in one dimension is presented. Close to T=O 0 K, the uniform susceptibility presents an essential singularity, when the exchange parameter is positive, and a power law behaviour with critical exponent γ=1, when this parameter is negative. (Author) [pt

  3. Boltzmann equations for a binary one-dimensional ideal gas.

    Science.gov (United States)

    Boozer, A D

    2011-09-01

    We consider a time-reversal invariant dynamical model of a binary ideal gas of N molecules in one spatial dimension. By making time-asymmetric assumptions about the behavior of the gas, we derive Boltzmann and anti-Boltzmann equations that describe the evolution of the single-molecule velocity distribution functions for an ensemble of such systems. We show that for a special class of initial states of the ensemble one can obtain an exact expression for the N-molecule velocity distribution function, and we use this expression to rigorously prove that the time-asymmetric assumptions needed to derive the Boltzmann and anti-Boltzmann equations hold in the limit of large N. Our results clarify some subtle issues regarding the origin of the time asymmetry of Boltzmann's H theorem.

  4. Faraday waves in quasi-one-dimensional superfluid Fermi-Bose mixtures

    DEFF Research Database (Denmark)

    Abdullaev, F. Kh.; Ögren, Magnus; Sørensen, Mads Peter

    2013-01-01

    The generation of Faraday waves in superfluid Fermi-Bose mixtures in elongated traps is investigated. The generation of waves is achieved by periodically changing a parameter of the system in time. Two types of modulations of parameters are considered: a variation of the fermion-boson scattering...... length and the boson-boson scattering length. We predict the properties of the generated Faraday patterns and study the parameter regions where they can be excited....

  5. Energy and contact of the one-dimensional Fermi polaron at zero and finite temperature.

    Science.gov (United States)

    Doggen, E V H; Kinnunen, J J

    2013-07-12

    We use the T-matrix approach for studying highly polarized homogeneous Fermi gases in one dimension with repulsive or attractive contact interactions. Using this approach, we compute ground state energies and values for the contact parameter that show excellent agreement with exact and other numerical methods at zero temperature, even in the strongly interacting regime. Furthermore, we derive an exact expression for the value of the contact parameter in one dimension at zero temperature. The model is then extended and used for studying the temperature dependence of ground state energies and the contact parameter.

  6. One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator.

    Science.gov (United States)

    Botari, Tiago; Leonel, Edson D

    2013-01-01

    A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization.

  7. A one-dimensional gravitationally interacting gas and the convex minorant of Brownian motion

    International Nuclear Information System (INIS)

    Suidan, T M

    2001-01-01

    The surprising connection between a one-dimensional gravitationally interacting gas of sticky particles and the convex minorant process generated by Brownian motion on [0,1] is studied. A study is made of the dynamics of this 1-D gas system by identifying three distinct clustering regimes and the time scales at which they occur. At the critical moment of time the mass distribution of the gas can be computed in terms of functionals of the convex minorant process

  8. One-dimensional magnetohydrodynamic calculations of a hydrogen-gas puff

    International Nuclear Information System (INIS)

    Maxon, S.; Nielsen, P.D.

    1981-01-01

    A one-dimensional Lagrangian calculation of the implosion of a hydrogen gas puff is presented. At maximum compression, 60% of the mass is located in a density spike .5 mm off the axis with a half width of 40 μm. The temperature on axis reaches 200 eV

  9. Theory of superfluidity and drag force in the one-dimensional Bose gas

    NARCIS (Netherlands)

    Cherny, A.Y.; Caux, J.-S.; Brand, J.

    2012-01-01

    The one-dimensional Bose gas is an unusual superfluid. In contrast to higher spatial dimensions, the existence of non-classical rotational inertia is not directly linked to the dissipationless motion of infinitesimal impurities. Recently, experimental tests with ultracold atoms have begun and

  10. Effects of interaction imbalance in a strongly repulsive one-dimensional Bose gas

    DEFF Research Database (Denmark)

    Barfknecht, Rafael Emilio; Zinner, Nikolaj Thomas; Foerster, Angela

    2018-01-01

    We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate...

  11. Quantum quenches to the attractive one-dimensional Bose gas: exact results

    Directory of Open Access Journals (Sweden)

    Lorenzo Piroli, Pasquale Calabrese, Fabian H. L. Essler

    2016-09-01

    Full Text Available We study quantum quenches to the one-dimensional Bose gas with attractive interactions in the case when the initial state is an ideal one-dimensional Bose condensate. We focus on properties of the stationary state reached at late times after the quench. This displays a finite density of multi-particle bound states, whose rapidity distribution is determined exactly by means of the quench action method. We discuss the relevance of the multi-particle bound states for the physical properties of the system, computing in particular the stationary value of the local pair correlation function $g_2$.

  12. Tonks-Girardeau and super-Tonks-Girardeau states of a trapped one-dimensional spinor Bose gas

    International Nuclear Information System (INIS)

    Girardeau, M. D.

    2011-01-01

    A harmonically trapped, ultracold, one-dimensional (1D) spin-1 Bose gas with strongly repulsive or attractive 1D even-wave interactions induced by a three-dimensional (3D) Feshbach resonance is studied. The exact ground state, a hybrid of Tonks-Girardeau (TG) and ideal Fermi gases, is constructed in the TG limit of infinite even-wave repulsion by a spinor Fermi-Bose mapping to a spinless ideal Fermi gas. It is then shown that in the limit of infinite even-wave attraction this same state remains an exact many-body eigenstate, now highly excited relative to the collapsed generalized McGuire-cluster ground state, showing that the hybrid TG state is completely stable against collapse to this cluster ground state under a sudden switch from infinite repulsion to infinite attraction. It is shown to be the TG limit of a hybrid super-Tonks-Girardeau (STG) state, which is metastable under a sudden switch from finite but very strong repulsion to finite but very strong attraction. It should be possible to create it experimentally by a sudden switch from strongly repulsive to strongly attractive interaction, as in the recent Innsbruck experiment on a spin-polarized bosonic STG gas. In the case of strong attraction, there should also exist another STG state of much lower energy, consisting of strongly bound dimers, a bosonic analog of a recently predicted STG state which is an ultracold gas of strongly bound bosonic dimers of fermionic atoms, but it is shown that this STG state cannot be created by such a switch from strong repulsion to strong attraction.

  13. Effects of Interaction Imbalance in a Strongly Repulsive One-Dimensional Bose Gas

    Science.gov (United States)

    Barfknecht, R. E.; Foerster, A.; Zinner, N. T.

    2018-05-01

    We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate the time evolution of the system and show that, for a certain ratio of interactions, the minority population travels through the system as an effective wave packet.

  14. Investigation of the diffusion of a massive particle in a one-dimensional ideal gas

    International Nuclear Information System (INIS)

    Khazin, M.L.

    1987-01-01

    Numerical methods have been used to investigate the dependence of the diffusion coefficient of a massive particle in a one-dimensional ideal gas on its mass. It is shown that the lower limit for the diffusion coefficient obtained by Sinai and Soloveichick and Szasz and Toth is a greatest lower bound. In addition, application of Pearson's x 2 test showed that the limit distribution of a massive particle is not Gaussian with a high significance level

  15. Quantum quench dynamics of the attractive one-dimensional Bose gas via the coordinate Bethe ansatz

    Directory of Open Access Journals (Sweden)

    Jan C. Zill, Tod M. Wright, Karen V. Kheruntsyan, Thomas Gasenzer, Matthew J. Davis

    2018-02-01

    Full Text Available We use the coordinate Bethe ansatz to study the Lieb-Liniger model of a one-dimensional gas of bosons on a finite-sized ring interacting via an attractive delta-function potential. We calculate zero-temperature correlation functions for seven particles in the vicinity of the crossover to a localized solitonic state and study the dynamics of a system of four particles quenched to attractive interactions from the ideal-gas ground state. We determine the time evolution of correlation functions, as well as their temporal averages, and discuss the role of bound states in shaping the postquench correlations and relaxation dynamics.

  16. Spin interaction with an ideal fermi gas

    International Nuclear Information System (INIS)

    Aizenstadt, V.V.; Malyshev, V.A.

    1987-01-01

    The authors consider the equilibrium dynamics of a system consisting of a spin interacting with an ideal Fermi gas on the lattice Z/sup v, v ≥ 3. They present two examples; when this system is unitarily equivalent to an ideal Fermi gas or to a spin in an ideal Fermi gas without interactions between them

  17. Synthesis and integration of one-dimensional nanostructures for chemical gas sensing applications

    Science.gov (United States)

    Parthangal, Prahalad Madhavan

    The need for improved measurement technology for the detection and monitoring of gases has increased tremendously for maintenance of domestic and industrial health and safety, environmental surveys, national security, food-processing, medical diagnostics and various other industrial applications. Among the several varieties of gas sensors available in the market, solid-state sensors are the most popular owing to their excellent sensitivity, ruggedness, versatility and low cost. Semiconducting metal oxides such as tin oxide (SnO2), zinc oxide (ZnO), and tungsten oxide (WO3) are routinely employed as active materials in these sensors. Since their performance is directly linked to the exposed surface area of the sensing material, one-dimensional nanostructures possessing very high surface to volume ratios are attractive candidates for designing the next generation of sensors. Such nano-sensors also enable miniaturization thereby reducing power consumption. The key to achieve success in one-dimensional nanotechnologies lies in assembly. While synthesis techniques and capabilities continue to expand rapidly, progress in controlled assembly has been sluggish due to numerous technical challenges. In this doctoral thesis work, synthesis and characterization of various one-dimensional nanostructures including nanotubes of SnO2, and nanowires of WO3 and ZnO, as well as their direct integration into miniature sensor platforms called microhotplates have been demonstrated. The key highlights of this research include devising elegant strategies for growing metal oxide nanotubes using carbon nanotubes as templates, substantially reducing process temperatures to enable growth of WO3 nanowires on microhotplates, and successfully fabricating a ZnO nanowire array based sensor using a hybrid nanowire-nanoparticle assembly approach. In every process, the gas-sensing properties of one-dimensional nanostructures were observed to be far superior in comparison with thin films of the same

  18. Decay of superfluid currents in the interacting one-dimensional Bose gas

    International Nuclear Information System (INIS)

    Cherny, Alexander Yu.; Caux, Jean-Sebastien; Brand, Joachim

    2009-01-01

    We examine the superfluid properties of a one-dimensional (1D) Bose gas in a ring trap based on the model of Lieb and Liniger. While the 1D Bose gas has nonclassical rotational inertia and exhibits quantization of velocities, the metastability of currents depends sensitively on the strength of interactions in the gas: the stronger the interactions, the faster the current decays. It is shown that the Landau critical velocity is zero in the thermodynamic limit due to the first supercurrent state, which has zero energy and finite probability of excitation. We calculate the energy dissipation rate of ring currents in the presence of weak defects, which should be observable on experimental time scales.

  19. Monopole excitations of a harmonically trapped one-dimensional Bose gas from the ideal gas to the Tonks-Girardeau regime.

    Science.gov (United States)

    Choi, S; Dunjko, V; Zhang, Z D; Olshanii, M

    2015-09-11

    Using a time-dependent modified nonlinear Schrödinger equation (MNLSE)-where the conventional chemical potential proportional to the density is replaced by the one inferred from Lieb-Liniger's exact solution-we study frequencies of the collective monopole excitations of a one-dimensional Bose gas. We find that our method accurately reproduces the results of a recent experimental study [E. Haller et al., Science 325, 1224 (2009)] in the full spectrum of interaction regimes from the ideal gas, through the mean-field regime, through the mean-field Thomas-Fermi regime, all the way to the Tonks-Giradeau gas. While the former two are accessible by the standard time-dependent NLSE and inaccessible by the time-dependent local density approximation, the situation reverses in the latter case. However, the MNLSE is shown to treat all these regimes within a single numerical method.

  20. Violation of self-similarity in the expansion of a one-dimensional Bose gas

    International Nuclear Information System (INIS)

    Pedri, P.; Santos, L.; Oehberg, P.; Stringari, S.

    2003-01-01

    The expansion of a one-dimensional Bose gas after releasing its initial harmonic confinement is investigated employing the Lieb-Liniger equation of state within the local-density approximation. We show that during the expansion the density profile of the gas does not follow a self-similar solution, as one would expect from a simple scaling ansatz. We carry out a variational calculation, which recovers the numerical results for the expansion, the equilibrium properties of the density profile, and the frequency of the lowest compressional mode. The variational approach allows for the analysis of the expansion in all interaction regimes between the mean-field and the Tonks-Girardeau limits, and in particular shows the range of parameters for which the expansion violates self-similarity

  1. Non-thermal fixed points and solitons in a one-dimensional Bose gas

    International Nuclear Information System (INIS)

    Schmidt, Maximilian; Erne, Sebastian; Nowak, Boris; Sexty, Dénes; Gasenzer, Thomas

    2012-01-01

    Single-particle momentum spectra for a dynamically evolving one-dimensional Bose gas are analysed in the semi-classical wave limit. Representing one of the simplest correlation functions, these provide information on a possible universal scaling behaviour. Motivated by the previously discovered connection between (quasi-) topological field configurations, strong wave turbulence and non-thermal fixed points of quantum field dynamics, soliton formation is studied with respect to the appearance of transient power-law spectra. A random-soliton model is developed for describing the spectra analytically, and the analogies and differences between the emerging power laws and those found in a field theory approach to strong wave turbulence are discussed. The results open a new perspective on solitary wave dynamics from the point of view of critical phenomena far from thermal equilibrium and the possibility of studying this dynamics by experiment without the need for detecting solitons in situ. (paper)

  2. Slow quench dynamics of a one-dimensional Bose gas confined to an optical lattice.

    Science.gov (United States)

    Bernier, Jean-Sébastien; Roux, Guillaume; Kollath, Corinna

    2011-05-20

    We analyze the effect of a linear time variation of the interaction strength on a trapped one-dimensional Bose gas confined to an optical lattice. The evolution of different observables such as the experimentally accessible on site particle distribution are studied as a function of the ramp time by using time-dependent numerical techniques. We find that the dynamics of a trapped system typically displays two regimes: For long ramp times, the dynamics is governed by density redistribution, while at short ramp times, local dynamics dominates as the evolution is identical to that of an homogeneous system. In the homogeneous limit, we also discuss the nontrivial scaling of the energy absorbed with the ramp time.

  3. Cluster properties of the one-dimensional lattice gas: the microscopic meaning of grand potential.

    Science.gov (United States)

    Fronczak, Agata

    2013-02-01

    Using a concrete example, we demonstrate how the combinatorial approach to a general system of particles, which was introduced in detail in an earlier paper [Fronczak, Phys. Rev. E 86, 041139 (2012)], works and where this approach provides a genuine extension of results obtained through more traditional methods of statistical mechanics. We study the cluster properties of a one-dimensional lattice gas with nearest-neighbor interactions. Three cases (the infinite temperature limit, the range of finite temperatures, and the zero temperature limit) are discussed separately, yielding interesting results and providing alternative proof of known results. In particular, the closed-form expression for the grand partition function in the zero temperature limit is obtained, which results in the nonanalytic behavior of the grand potential, in accordance with the Yang-Lee theory.

  4. Dynamics of attractively interacting Fermi atoms in one-dimensional optical lattices: Non-equilibrium simulations of fermion superfluidity

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, M., E-mail: okumura.masahiko@jaea.go.j [CCSE, Japan Atomic Energy Agency, 6-9-3 Higashi-Ueno, Taito-ku, Tokyo 110-0015 (Japan); CREST (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Onishi, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Yamada, S. [CCSE, Japan Atomic Energy Agency, 6-9-3 Higashi-Ueno, Taito-ku, Tokyo 110-0015 (Japan); CREST (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Machida, M. [CCSE, Japan Atomic Energy Agency, 6-9-3 Higashi-Ueno, Taito-ku, Tokyo 110-0015 (Japan); CREST (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan) and JST, TRIP, Sambancho Chiyoda-ku, Tokyo 102-0075 (Japan)

    2010-12-15

    We study center of mass (CoM) motions of attractively interacting fermionic atoms loaded on an one-dimensional optical lattice confined by a harmonic potential at zero temperature by using adaptive time-dependent density-matrix renormalization-group method. We find that the CoM motions in weak and strong attraction show underdamped and overdamped motions, respectively, which are consistent with the experimental results of the CoM motion in the three-dimensional optical lattice. In addition, we find spin-imbalance effects on the CoM motion, which slow the CoM motion down.

  5. Scaling symmetries, conservation laws and action principles in one-dimensional gas dynamics

    International Nuclear Information System (INIS)

    Webb, G M; Zank, G P

    2009-01-01

    Scaling symmetries of the planar, one-dimensional gas dynamic equations with adiabatic index γ are used to obtain Lagrangian and Eulerian conservation laws associated with the symmetries. The known Eulerian symmetry operators for the scaling symmetries are converted to the Lagrangian form, in which the Eulerian spatial position of the fluid element is given in terms of the Lagrangian fluid labels. Conditions for a linear combination of the three scaling symmetries to be a divergence or variational symmetry of the action are established. The corresponding Lagrangian and Eulerian form of the conservation laws are determined by application of Noether's theorem. A nonlocal conservation law associated with the scaling symmetries is obtained by applying a nonlocal symmetry operator to the scaling symmetry-conserved vector. An action principle incorporating known conservation laws using Lagrangian constraints is developed. Noether's theorem for the constrained action principle gives the same formulas for the conserved vector as the classical Noether theorem, except that the Lie symmetry vector field now includes the effects of nonlocal potentials. Noether's theorem for the constrained action principle is used to obtain nonlocal conservation laws. The scaling symmetry conservation laws only apply for special forms of the entropy of the gas.

  6. Universality and Quantum Criticality of the One-Dimensional Spinor Bose Gas

    Science.gov (United States)

    PâÅ£u, Ovidiu I.; Klümper, Andreas; Foerster, Angela

    2018-06-01

    We investigate the universal thermodynamics of the two-component one-dimensional Bose gas with contact interactions in the vicinity of the quantum critical point separating the vacuum and the ferromagnetic liquid regime. We find that the quantum critical region belongs to the universality class of the spin-degenerate impenetrable particle gas which, surprisingly, is very different from the single-component case and identify its boundaries with the peaks of the specific heat. In addition, we show that the compressibility Wilson ratio, which quantifies the relative strength of thermal and quantum fluctuations, serves as a good discriminator of the quantum regimes near the quantum critical point. Remarkably, in the Tonks-Girardeau regime, the universal contact develops a pronounced minimum, reflected in a counterintuitive narrowing of the momentum distribution as we increase the temperature. This momentum reconstruction, also present at low and intermediate momenta, signals the transition from the ferromagnetic to the spin-incoherent Luttinger liquid phase and can be detected in current experiments with ultracold atomic gases in optical lattices.

  7. Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

    Energy Technology Data Exchange (ETDEWEB)

    Roy S. Baty, F. Farassat, John A. Hargreaves

    2007-05-25

    Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.

  8. Remarks on the global existence in the dynamics of a viscous, heat-conducting, one-dimensional gas

    International Nuclear Information System (INIS)

    Song Jiang

    1994-01-01

    We consider initial boundary value problems for the equations of the motion of a viscous, heat-conducting, one-dimensional gas which is confined to a fixed tube with impermeable ends and whose viscosity varies with density, and prove the global existence of smooth (large) solutions. (author). 17 refs

  9. Quantitative study of quasi-one-dimensional Bose gas experiments via the stochastic Gross-Pitaevskii equation

    International Nuclear Information System (INIS)

    Cockburn, S. P.; Gallucci, D.; Proukakis, N. P.

    2011-01-01

    The stochastic Gross-Pitaevskii equation is shown to be an excellent model for quasi-one-dimensional Bose gas experiments, accurately reproducing the in situ density profiles recently obtained in the experiments of Trebbia et al.[Phys. Rev. Lett. 97, 250403 (2006)] and van Amerongen et al.[Phys. Rev. Lett. 100, 090402 (2008)] and the density fluctuation data reported by Armijo et al.[Phys. Rev. Lett. 105, 230402 (2010)]. To facilitate such agreement, we propose and implement a quasi-one-dimensional extension to the one-dimensional stochastic Gross-Pitaevskii equation for the low-energy, axial modes, while atoms in excited transverse modes are treated as independent ideal Bose gases.

  10. Effect on cavity optomechanics of the interaction between a cavity field and a one-dimensional interacting bosonic gas

    International Nuclear Information System (INIS)

    Sun Qing; Hu Xinghua; Liu, W. M.; Xie, X. C.; Ji Anchun

    2011-01-01

    We investigate optomechanical coupling between one-dimensional interacting bosons and the electromagnetic field in a high-finesse optical cavity. We show that by tuning interatomic interactions, one can realize effective optomechanics with mechanical resonators ranging from side-mode excitations of a Bose-Einstein condensate (BEC) to particle-hole excitations of a Tonks-Girardeau (TG) gas. We propose that this unique feature can be formulated to detect the BEC-TG gas crossover and measure the sine-Gordon transition continuously and nondestructively.

  11. Statistical mechanics of magnetized pair Fermi gas

    International Nuclear Information System (INIS)

    Daicic, J.; Frankel, N.E.; Kowalenko, V.

    1993-01-01

    Following previous work on the magnetized pair Bose gas this contribution presents the statistical mechanics of the charged relativistic Fermi gas with pair creation in d spatial dimensions. Initially, the gas in no external fields is studied. As a result, expansions for the various thermodynamic functions are obtained in both the μ/m→0 (neutrino) limit, and about the point μ/m =1, where μ is the chemical potential. The thermodynamics of a gas of quantum-number conserving massless fermions is also discussed. Then a complete study of the pair Fermi gas in a homogeneous magnetic field, is presented investigating the behavior of the magnetization over a wide range of field strengths. The inclusion of pairs leads to new results for the net magnetization due to the paramagnetic moment of the spins and the diamagnetic Landau orbits. 20 refs

  12. Long-distance behavior of temperature correlation functions in the one-dimensional Bose gas

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [UMR 5672 du CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

    2010-12-15

    We describe a Bethe ansatz based method to derive, starting from a multiple integral representation, the long-distance asymptotic behavior at finite temperature of the density-density correlation function in the interacting onedimensional Bose gas. We compute the correlation lengths in terms of solutions of non-linear integral equations of the thermodynamic Bethe ansatz type. Finally, we establish a connection between the results obtained in our approach with the correlation lengths stemming from the quantum transfer matrix method. (orig.)

  13. Thermodynamics of a one-dimensional ideal gas with fractional exclusion statistics

    International Nuclear Information System (INIS)

    Murthy, M.V.N.; Shankar, R.

    1994-01-01

    We show that the particles in the Calogero-Sutherland model obey fractional exclusion statistics as defined by Haldane. We construct anyon number densities and derive the energy distribution function. We show that the partition function factorizes in the form characteristic of an ideal gas. The virial expansion is exactly computable and interestingly it is only the second virial coefficient that encodes the statistics information

  14. Exact Local Correlations and Full Counting Statistics for Arbitrary States of the One-Dimensional Interacting Bose Gas

    Science.gov (United States)

    Bastianello, Alvise; Piroli, Lorenzo; Calabrese, Pasquale

    2018-05-01

    We derive exact analytic expressions for the n -body local correlations in the one-dimensional Bose gas with contact repulsive interactions (Lieb-Liniger model) in the thermodynamic limit. Our results are valid for arbitrary states of the model, including ground and thermal states, stationary states after a quantum quench, and nonequilibrium steady states arising in transport settings. Calculations for these states are explicitly presented and physical consequences are critically discussed. We also show that the n -body local correlations are directly related to the full counting statistics for the particle-number fluctuations in a short interval, for which we provide an explicit analytic result.

  15. Exact dynamics of a one dimensional Bose gas in a periodic time-dependent harmonic trap

    Science.gov (United States)

    Scopa, Stefano; Unterberger, Jéremie; Karevski, Dragi

    2018-05-01

    We study the unitary dynamics of a 1D gas of hard-core bosons trapped into a harmonic potential which varies periodically in time with frequency . Such periodic systems can be classified into orbits of different monodromies corresponding to two different physical situations, namely the case in which the bosonic cloud remains stable during the time-evolution and the case where it turns out to be unstable. In the present work we derive in the large particle number limit exact results for the stroboscopic evolution of the energy and particle densities in both physical situations.

  16. Effects of a delta-attractive impurity in the thermodynamics properties of an one-dimensional ideal Bose gas

    International Nuclear Information System (INIS)

    Ioriatti Junior, L.C.

    1976-01-01

    The thermodynamic behavior of the one-dimensional bose gas-attractive delta impurity system is studied. The system is shown to undergo the Bose-Einstein condensation and the cause of the phase transition is attributed to the bound state introduced by the impurity in the free particle energy spectrum. The condensed phase is composed by particles captured by the impurity, forming a drop of particles well localized in space. This gives to the Bose-Einstein condensation in this system the appearance of the ordinary vapor-liquid phase transition. The order of the phase transition is analized with the aid of the Clausius-Clayperon equation, leading to the conclusion that the transition is a first order one. This reinforces the interpretation of a vapor-liquid transition. The evaluation of the heat capacity at constant length shows the existence of a finite discontinuity at the transition temperature [pt

  17. Analogy between soap film and gas dynamics. II. Experiments on one-dimensional motion of shock waves in soap films

    Energy Technology Data Exchange (ETDEWEB)

    Wen, C.Y.; Chang-Jian, S.K.; Chuang, M.C. [Department of Mechanical Engineering, Da-Yeh University, Chang-Hwa (Taiwan)

    2003-02-01

    This paper presents an experimental investigation of one-dimensional moving shock waves in vertical soap films. The shock waves were generated by bursting the films with a perforating spark. Images of propagating shock waves and small disturbances were recorded using a fast line scan CCD camera. An aureole and a shock wave preceding the rim of the expanding hole were clearly observed. These images are similar to the x-t diagrams in gas dynamics and give the velocities of shock and sound waves. The moving shock waves cause jumps in thickness. The variations of the induced Mach number, M{sub 2} and the ratio of film thickness across the shock wave, {delta}{sub 2}/{delta}{sub 1}, are plotted versus the shock Mach number, M{sub s}. Both results suggest that soap films are analogous to compressible gases with a specific heat ratio of {gamma}{approx_equal}1.0. (orig.)

  18. Ground-state pressure of an ideal Fermi gas

    International Nuclear Information System (INIS)

    Delsante, A.E.; Frankel, N.E.

    1979-01-01

    A simple relationship between the pressure, internal energy and Fermi energy of an ideal ultra-degenerate Fermi gas is derived in two ways. The conditions for its validity and its use in simplifying calculations are discussed

  19. Massive Fermi gas in the expanding universe

    Energy Technology Data Exchange (ETDEWEB)

    Trautner, Andreas, E-mail: atrautner@uni-bonn.de [Bethe Center for Theoretical Physics and Physikalisches Institut der Universität Bonn, Nussallee 12, 53115 Bonn (Germany)

    2017-03-01

    The behavior of a decoupled ideal Fermi gas in a homogeneously expanding three-dimensional volume is investigated, starting from an equilibrium spectrum. In case the gas is massless and/or completely degenerate, the spectrum of the gas can be described by an effective temperature and/or an effective chemical potential, both of which scale down with the volume expansion. In contrast, the spectrum of a decoupled massive and non-degenerate gas can only be described by an effective temperature if there are strong enough self-interactions such as to maintain an equilibrium distribution. Assuming perpetual equilibration, we study a decoupled gas which is relativistic at decoupling and then is red-shifted until it becomes non-relativistic. We find expressions for the effective temperature and effective chemical potential which allow us to calculate the final spectrum for arbitrary initial conditions. This calculation is enabled by a new expansion of the Fermi-Dirac integral, which is for our purpose superior to the well-known Sommerfeld expansion. We also compute the behavior of the phase space density under expansion and compare it to the case of real temperature and real chemical potential. Using our results for the degenerate case, we also obtain the mean relic velocity of the recently proposed non-thermal cosmic neutrino background.

  20. Broad-Spectrum Liquid- and Gas-Phase Decontamination of Chemical Warfare Agents by One-Dimensional Heteropolyniobates.

    Science.gov (United States)

    Guo, Weiwei; Lv, Hongjin; Sullivan, Kevin P; Gordon, Wesley O; Balboa, Alex; Wagner, George W; Musaev, Djamaladdin G; Bacsa, John; Hill, Craig L

    2016-06-20

    A wide range of chemical warfare agents and their simulants are catalytically decontaminated by a new one-dimensional polymeric polyniobate (P-PONb), K12 [Ti2 O2 ][GeNb12 O40 ]⋅19 H2 O (KGeNb) under mild conditions and in the dark. Uniquely, KGeNb facilitates hydrolysis of nerve agents Sarin (GB) and Soman (GD) (and their less reactive simulants, dimethyl methylphosphonate (DMMP)) as well as mustard (HD) in both liquid and gas phases at ambient temperature and in the absence of neutralizing bases or illumination. Three lines of evidence establish that KGeNb removes DMMP, and thus likely GB/GD, by general base catalysis: a) the k(H2 O)/k(D2 O) solvent isotope effect is 1.4; b) the rate law (hydrolysis at the same pH depends on the amount of P-PONb present); and c) hydroxide is far less active against the above simulants at the same pH than the P-PONbs themselves, a critical control experiment. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Instabilities of a Fermi gas with nested Fermi surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schlottmann, Pedro [Department of Physics, Florida State University, Tallahassee, FL (United States)

    2018-01-15

    The nesting of the Fermi surfaces of an electron and a hole pocket separated by a vector Q commensurate with the lattice in conjunction with the interaction between the quasiparticles can give rise to a rich phase diagram. Of particular importance is itinerant antiferromagnetic order in the context of pnictides and heavy fermion compounds. By mismatching the nesting the order can gradually be suppressed and as the Neel temperature tends to zero a quantum critical point is obtained. A superconducting dome above the quantum critical point can be induced by the transfer of pairs of electrons between the pockets. The conditions under which such a dome arises are studied. In addition numerous other phases may arise, e.g. charge density waves, non-Fermi liquid behavior, non-s-wave superconductivity, Pomeranchuk instabilities of the Fermi surface, nematic order, and phases with persistent orbital currents. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Orientifolding of the ABJ Fermi gas

    International Nuclear Information System (INIS)

    Okuyama, Kazumi

    2016-01-01

    The grand partition functions of ABJ theory can be factorized into even and odd parts under the reflection of fermion coordinate in the Fermi gas approach. In some cases, the even/odd part of ABJ grand partition function is equal to that of N=5O(n)×USp(n"′) theory, hence it is natural to think of the even/odd projection of grand partition function as an orientifolding of ABJ Fermi gas system. By a systematic WKB analysis, we determine the coefficients in the perturbative part of grand potential of such orientifold ABJ theory. We also find the exact form of the first few “half-instanton” corrections coming from the twisted sector of the reflection of fermion coordinate. For the Chern-Simons level k=2,4,8 we find closed form expressions of the grand partition functions of orientifold ABJ theory, and for k=2,4 we prove the functional relations among the grand partition functions conjectured in http://arxiv.org/abs/1410.7658.

  3. Orientifolding of the ABJ Fermi gas

    Science.gov (United States)

    Okuyama, Kazumi

    2016-03-01

    The grand partition functions of ABJ theory can be factorized into even and odd parts under the reflection of fermion coordinate in the Fermi gas approach. In some cases, the even/odd part of ABJ grand partition function is equal to that of {N}=5O(n)× USp({n}^') theory, hence it is natural to think of the even/odd projection of grand partition function as an orientifolding of ABJ Fermi gas system. By a systematic WKB analysis, we determine the coefficients in the perturbative part of grand potential of such orientifold ABJ theory. We also find the exact form of the first few "half-instanton" corrections coming from the twisted sector of the reflection of fermion coordinate. For the Chern-Simons level k = 2 ,4 ,8 we find closed form expressions of the grand partition functions of orientifold ABJ theory, and for k = 2 , 4 we prove the functional relations among the grand partition functions conjectured in arXiv:1410.7658.

  4. Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

    DEFF Research Database (Denmark)

    Sarkar, I.; Laux, M.; Demokritova, J.

    2010-01-01

    We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth...... of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method....

  5. Electroweak interactions in a relativistic Fermi gas

    International Nuclear Information System (INIS)

    Vantournhout, K.; Jachowicz, N.; Ryckebusch, J.

    2006-01-01

    We present a relativistic model for computing the neutrino mean free path in neutron matter. In this model, neutron matter is described as a noninteracting Fermi gas in β equilibrium. We present results for the neutrino mean free path for temperatures of 0 to 50 MeV and a broad range of neutrino energies. We show that relativistic effects cause a considerable enhancement of neutrino-scattering cross sections in neutron matter. The influence of the Q 2 dependence in the electroweak form factors and the inclusion of a weak-magnetic term in the hadron current is discussed. The weak-magnetic term in the hadron current is at the origin of some selective spin dependence for the nucleons that are subject to neutrino interactions

  6. Joule-Thomson Coefficient for Strongly Interacting Unitary Fermi Gas

    International Nuclear Information System (INIS)

    Liao Kai; Chen Jisheng; Li Chao

    2010-01-01

    The Joule-Thomson effect reflects the interaction among constituent particles of macroscopic system. For classical ideal gas, the corresponding Joule-Thomson coefficient is vanishing while it is non-zero for ideal quantum gas due to the quantum degeneracy. In recent years, much attention is paid to the unitary Fermi gas with infinite two-body scattering length. According to universal analysis, the thermodynamical law of unitary Fermi gas is similar to that of non-interacting ideal gas, which can be explored by the virial theorem P = 2E/3V. Based on previous works, we further study the unitary Fermi gas properties. The effective chemical potential is introduced to characterize the nonlinear levels crossing effects in a strongly interacting medium. The changing behavior of the rescaled Joule-Thomson coefficient according to temperature manifests a quite different behavior from that for ideal Fermi gas. (general)

  7. OSCIL: one-dimensional spring-mass system simulator for seismic analysis of high temperature gas cooled reactor core

    International Nuclear Information System (INIS)

    Lasker, L.

    1976-01-01

    OSCIL is a program to predict the effects of seismic input on a HTGR core. The present model is a one-dimensional array of blocks with appropriate spring constants, inter-elemental and ground damping, and clearances. It can be used more generally for systems of moving masses separated by nonlinear springs and dampers

  8. OSCIL: one-dimensional spring-mass system simulator for seismic analysis of high temperature gas cooled reactor core

    Energy Technology Data Exchange (ETDEWEB)

    Lasker, L. (ed.)

    1976-01-01

    OSCIL is a program to predict the effects of seismic input on a HTGR core. The present model is a one-dimensional array of blocks with appropriate spring constants, inter-elemental and ground damping, and clearances. It can be used more generally for systems of moving masses separated by nonlinear springs and dampers.

  9. Coulomb sum rules in the relativistic Fermi gas model

    International Nuclear Information System (INIS)

    Do Dang, G.; L'Huillier, M.; Nguyen Giai, Van.

    1986-11-01

    Coulomb sum rules are studied in the framework of the Fermi gas model. A distinction is made between mathematical and observable sum rules. Differences between non-relativistic and relativistic Fermi gas predictions are stressed. A method to deduce a Coulomb response function from the longitudinal response is proposed and tested numerically. This method is applied to the 40 Ca data to obtain the experimental Coulomb sum rule as a function of momentum transfer

  10. A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, J.R.; Arnau, F.J.; Dolz, V.; Tiseira, A. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Cervello, C. [Conselleria de Cultura, Educacion y Deporte, Generalitat Valenciana (Spain)

    2008-12-15

    The paper presents a model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with zero- and one-dimensional gas dynamic codes. The model is based from its very conception on the measured characteristics of the turbine. Nevertheless, it is capable of extrapolating operating conditions that differ from those included in the turbine maps, since the engines usually work within these zones. The presented model has been implemented in a one-dimensional gas dynamic code and has been used to calculate unsteady operating conditions for several turbines. The results obtained have been compared with success against pressure-time histories measured upstream and downstream of the turbine during on-engine operation. (author)

  11. A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling

    International Nuclear Information System (INIS)

    Serrano, J.R.; Arnau, F.J.; Dolz, V.; Tiseira, A.; Cervello, C.

    2008-01-01

    The paper presents a model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with zero- and one-dimensional gas dynamic codes. The model is based from its very conception on the measured characteristics of the turbine. Nevertheless, it is capable of extrapolating operating conditions that differ from those included in the turbine maps, since the engines usually work within these zones. The presented model has been implemented in a one-dimensional gas dynamic code and has been used to calculate unsteady operating conditions for several turbines. The results obtained have been compared with success against pressure-time histories measured upstream and downstream of the turbine during on-engine operation

  12. Resonant tunneling and persistent current of a non-interacting and weakly interacting one-dimensional electron gas

    International Nuclear Information System (INIS)

    Krive, I.V.; Sandstroem, P.

    1997-01-01

    The persistent current for a one-dimensional ring with two tunneling barriers is considered in the limit of weakly interacting electrons. In addition to small off-resonance current, there are two kinds of resonant behaviour; (i) a current independent of the barrier transparency (true resonance) and (ii) a current analogous to the one for a ring with only single barrier (''semi''-resonance). For a given barrier transparency the realization of this or that type of resonant behaviour depends both on the geometrical factor (the ratio of interbarrier distance to a ring circumference) and on the strength of electron-electron interaction. It is shown that repulsive interaction favours the ''semi''-resonance behaviour. For a small barrier transparency the ''semi''-resonance peaks are easily washed out by temperature whereas the true resonance peaks survive. (author). 22 refs, 2 figs

  13. Terahertz gas sensing based on a simple one-dimensional photonic crystal cavity with high-quality factors

    DEFF Research Database (Denmark)

    Chen, T.; Han, Z. H.; Liu, J. J.

    2014-01-01

    We report in this paper terahertz gas sensing using a simple 1D photonic crystal cavity. The resonant frequencies of the cavity depend linearly on the refractive index of the ambient gas, which can then be measured by monitoring the resonance shift. Although quite easy to manufacture, this cavity...... exhibits high-quality factors, facilitating the realization of high sensitivity in the gas refractive index sensing. In our experiment, 6% of the change of hydrogen concentration in air, which corresponds to a refractive index change of 1.4 x 10(-5), can be steadily detected, and different gas samples can...

  14. Time-dependent solution for a one-dimensional piston problem in a non-ideal gas

    International Nuclear Information System (INIS)

    Purohit, S.C.

    1980-01-01

    In this article we study the effect of a non-ideal gas parameter on the piston (contact) surface when a strong shock moves into a non-uniform medium. The solution corresponding to the ideal gas can be obtained as a particular case of the analysis. (orig.)

  15. Hydrodynamics in a Degenerate, Strongly Attractive Fermi Gas

    Science.gov (United States)

    Thomas, John E.; Kinast, Joseph; Hemmer, Staci; Turlapov, Andrey; O'Hara, Ken; Gehm, Mike; Granade, Stephen

    2004-01-01

    In summary, we use all-optical methods with evaporative cooling near a Feshbach resonance to produce a strongly interacting degenerate Fermi gas. We observe hydrodynamic behavior in the expansion dynamics. At low temperatures, collisions may not explain the expansion dynamics. We observe hydrodynamics in the trapped gas. Our observations include collisionally-damped excitation spectra at high temperature which were not discussed above. In addition, we observe weakly damped breathing modes at low temperature. The observed temperature dependence of the damping time and hydrodynamic frequency are not consistent with collisional dynamics nor with collisionless mean field interactions. These observations constitute the first evidence for superfluid hydrodynamics in a Fermi gas.

  16. The analytical solution of the problem of a shock focusing in a gas for one-dimensional case

    Science.gov (United States)

    Shestakovskaya, E. S.; Magazov, F. G.

    2018-03-01

    The analytical solution of the problem of an imploding shock wave in the vessel with an impermeable wall is constructed for the cases of planar, cylindrical and spherical symmetry. The negative velocity is set at the vessel boundary. The velocity of cold ideal gas is zero. At the initial time the shock spreads from this point into the center of symmetry. The boundary moves under the particular law which conforms to the movement of the shock. In Euler variables it moves but in Lagrangian variables its trajectory is a vertical line. Equations that determine the structure of the gas flow between the shock front and the boundary as a function of time and the Lagrangian coordinate as well as the dependence of the entropy on the shock wave velocity are obtained. Self-similar coefficients and corresponding critical values of self-similar coordinates were found for a wide range of adiabatic index. The problem is solved for Lagrangian coordinates.

  17. Quantum hydrodynamics and nonlinear differential equations for degenerate Fermi gas

    International Nuclear Information System (INIS)

    Bettelheim, Eldad; Abanov, Alexander G; Wiegmann, Paul B

    2008-01-01

    We present new nonlinear differential equations for spacetime correlation functions of Fermi gas in one spatial dimension. The correlation functions we consider describe non-stationary processes out of equilibrium. The equations we obtain are integrable equations. They generalize known nonlinear differential equations for correlation functions at equilibrium [1-4] and provide vital tools for studying non-equilibrium dynamics of electronic systems. The method we developed is based only on Wick's theorem and the hydrodynamic description of the Fermi gas. Differential equations appear directly in bilinear form. (fast track communication)

  18. Itinerant Ferromagnetism in a Polarized Two-Component Fermi Gas

    DEFF Research Database (Denmark)

    Massignan, Pietro; Yu, Zhenhua; Bruun, Georg

    2013-01-01

    We analyze when a repulsively interacting two-component Fermi gas becomes thermodynamically unstable against phase separation. We focus on the strongly polarized limit, where the free energy of the homogeneous mixture can be calculated accurately in terms of well-defined quasiparticles, the repul......We analyze when a repulsively interacting two-component Fermi gas becomes thermodynamically unstable against phase separation. We focus on the strongly polarized limit, where the free energy of the homogeneous mixture can be calculated accurately in terms of well-defined quasiparticles...

  19. Problems on gravitational collapse of interstellar gas clouds. II. Caustic and critical times for a one-dimensional hydrodynamic model

    Energy Technology Data Exchange (ETDEWEB)

    Ferraioli, F; Virgopia, N [Rome Univ. (Italy). Ist. di Matematica; Ruggeri, T [Bologna Univ. (Italy)

    1978-07-01

    The gravitational collapse of a spherically symmetric interstellar gas cloud has been investigated following the non-linear discontinuity waves propagation theory. It has been pointed out that macroscopic phenomena, such as the process of fragmentation, can arise (shock wave formation) - even in the case of spherical symmetry - at times smaller than the free-fall time tsub(ff), provided the initial data of the Cauchy problem be discontinuous within a sphere of radius R(mean) < Rsub(cloud) (caustic cases). It has also been proved that strong discontinuities outside the mentioned sphere may generate critical times tsub(cr) < tsub(ff) (depending on the typical non-linear structure of the differential system). The cooling-heating function plays an important role in contrasting the formation of shock waves.

  20. Noninteracting Fermi gas in a square-well potential.

    Science.gov (United States)

    Nash, C. E.

    1971-01-01

    The problem of a noninteracting Fermi gas in a finite square-well potential is solved analytically in the limit that the well becomes infinitely wide. The errors of previous authors using this model as a first approximation to the problem of a simple metal with surfaces are pointed out.

  1. Resonance superfluidity in a quantum degenerate Fermi gas

    NARCIS (Netherlands)

    Kokkelmans, S.J.J.M.F.; Holland, M.; Walser, R.; Chiofalo, M.L.; Chu, S.; Vuletic, V.; Kerman, A.J.; Chin, C.

    2002-01-01

    We consider the superfluid phase transition that arises when a Feshbach resonance pairing occurs in a dilute Fermi gas. This is related to the phenomenon of superconductivity described by the seminal Bardeen-Cooper-Schrieffer (BCS) theory. In superconductivity, the phase transition is caused by a

  2. Chemical potential of one-dimensional simple harmonic oscillators

    International Nuclear Information System (INIS)

    Mungan, Carl E

    2009-01-01

    Expressions for the chemical potential of an Einstein solid, and of ideal Fermi and Bose gases in an external one-dimensional oscillatory trap, are calculated by two different methods and are all found to share the same functional form. These derivations are easier than traditional textbook calculations for an ideal gas in an infinite three-dimensional square well. Furthermore, the results indicate some important features of chemical potential that could promote student learning in an introductory course in statistical mechanics at the undergraduate level.

  3. The universal sound velocity formula for the strongly interacting unitary Fermi gas

    International Nuclear Information System (INIS)

    Liu Ke; Chen Ji-Sheng

    2011-01-01

    Due to the scale invariance, the thermodynamic laws of strongly interacting limit unitary Fermi gas can be similar to those of non-interacting ideal gas. For example, the virial theorem between pressure and energy density of the ideal gas P = 2E/3V is still satisfied by the unitary Fermi gas. This paper analyses the sound velocity of unitary Fermi gases with the quasi-linear approximation. For comparison, the sound velocities for the ideal Boltzmann, Bose and Fermi gas are also given. Quite interestingly, the sound velocity formula for the ideal non-interacting gas is found to be satisfied by the unitary Fermi gas in different temperature regions. (general)

  4. Basic physics of one-dimensional metals

    International Nuclear Information System (INIS)

    Emery, V.J.

    1976-01-01

    Largely nonmathematical qualitative lectures are given on the basic physics of nearly one-dimensional conductors. The main emphasis is placed on the properties of a purely one-dimensional electron gas. The effects of a real system having interchain coupling, impurities, a compressible lattice, lattice distortions and phonon anomalies are discussed

  5. Vortex formation in a rotating two-component Fermi gas

    Energy Technology Data Exchange (ETDEWEB)

    Warringa, Harmen J.; Sedrakian, Armen [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt am Main, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany)

    2011-08-15

    A two-component Fermi gas with attractive s-wave interactions forms a superfluid at low temperatures. When this gas is confined in a rotating trap, fermions can unpair at the edges of the gas and vortices can arise beyond certain critical rotation frequencies. We compute these critical rotation frequencies and construct the phase diagram in the plane of scattering length and rotation frequency for different total numbers of particles. We work at zero temperature and consider a cylindrically symmetric harmonic trapping potential. The calculations are performed in the Hartree-Fock-Bogoliubov approximation which implies that our results are quantitatively reliable for weak interactions.

  6. Instanton effects in ABJM theory from Fermi gas approach

    Energy Technology Data Exchange (ETDEWEB)

    Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Tokyo Institute of Technology (Japan). Dept. of Physics; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst.; Nagoya Univ. (Japan). Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

    2012-11-19

    We study the instanton effects of the ABJM partition function using the Fermi gas formalism. We compute the exact values of the partition function at the Chern-Simons levels k=1, 2, 3, 4, 6 up to N=44, 20, 18, 16, 14 respectively, and extract non-perturbative corrections from these exact results. Fitting the resulting non-perturbative corrections by their expected forms from the Fermi gas, we determine unknown parameters in them. After separating the oscillating behavior of the grand potential, which originates in the periodicity of the grand partition function, and the worldsheet instanton contribution, which is computed from the topological string theory, we succeed in proposing an analytical expression for the leading D2-instanton correction. Just as the perturbative result, the instanton corrections to the partition function are expressed in terms of the Airy function.

  7. Small metal particles and the ideal Fermi gas

    International Nuclear Information System (INIS)

    Barma, Mustanpir

    1991-01-01

    Kubo's theoretical model of a small metal particle consists of a number of noninteraction electrons (an ideal Fermi gas) confined to a finite volume. By 'small' it meant that the size of the particle is intermediate between that of a few atoms cluster and the bulk solid, the radius of the particle being 5 to 50 Angstroms. The model is discussed and size dependence of various energy scales is studied. For a fermi gas confined in a sphere or a cube, two size-dependent energy scales are important. The inner scale δ is the mean spacing between successive energy levels. It governs the very low temperature behaviour. The outer scale Δ is associated with the shell structure when δ ≤T<Δ, thermodynamic properties show an oscillatory fluctuations around a smooth background as the size or energy is varied. (M.G.B.) 23 refs

  8. Fermi

    Data.gov (United States)

    National Aeronautics and Space Administration — Fermi is a powerful space observatory that will open a wide window on the universe. Gamma rays are the highest-energy form of light, and the gamma-ray sky is...

  9. Degenerate Fermi gas in a combined harmonic-lattice potential

    International Nuclear Information System (INIS)

    Blakie, P. B.; Bezett, A.; Buonsante, P.

    2007-01-01

    In this paper we derive an analytic approximation to the density of states for atoms in a combined optical lattice and harmonic trap potential as used in current experiments with quantum degenerate gases. We compare this analytic density of states to numerical solutions and demonstrate its validity regime. Our work explicitly considers the role of higher bands and when they are important in quantitative analysis of this system. Applying our density of states to a degenerate Fermi gas, we consider how adiabatic loading from a harmonic trap into the combined harmonic-lattice potential affects the degeneracy temperature. Our results suggest that occupation of excited bands during loading should lead to more favorable conditions for realizing degenerate Fermi gases in optical lattices

  10. One-Dimensionality and Whiteness

    Science.gov (United States)

    Calderon, Dolores

    2006-01-01

    This article is a theoretical discussion that links Marcuse's concept of one-dimensional society and the Great Refusal with critical race theory in order to achieve a more robust interrogation of whiteness. The author argues that in the context of the United States, the one-dimensionality that Marcuse condemns in "One-Dimensional Man" is best…

  11. Peltier heat measurements at a junction between materials exhibiting Fermi gas and Fermi liquid behaviour

    International Nuclear Information System (INIS)

    Kuznetsov, V L; Kuznetsova, L A; Rowe, D M

    2003-01-01

    The feasibility of improving the conversion efficiency of a thermoelectric converter by employing interfaces between materials exhibiting Fermi gas (FG) and Fermi liquid (FL) behaviour has been studied. Thermocouples consisting of a semiconductor and a strongly correlated material have been fabricated and the Peltier heat measured over the temperature range 15 deg 330 K. A number of materials possessing different types of strong electron correlation have been synthesized including the heavy fermion compound YbAl 3 , manganite La 0.7 Ca 0.3 MnO 3 and high-T c superconductor YBa 2 Cu 3 O 7δ . n- and p-Bi 2 Te 3 -based solid solutions as well as n-Bi 0.85 Sb 0.15 solid solution have also been synthesized and used as materials exhibiting FG properties. Experimental measurements of the Peltier heat were compared to the results of calculations based on preliminary measured thermoelectric properties of materials and electrical contact resistance at the interfaces. The potential of employing FG/FL interfaces in thermoelectric energy conversion is discussed

  12. Attack-Induced Entanglement of Noninteracting Fermi Gas

    International Nuclear Information System (INIS)

    Ren Jie; Zhu Shiqun

    2008-01-01

    The bipartite entanglement in Fermi gas without interaction is investigated when there are three fermions in the system. The negativity and the von Neumann entropy are employed to measure the entanglement of the system. The position of the third fermion can affect the entanglement between the first and the second fermions. The entanglement can be enhanced or suppressed when the third fermion changes its position. When the two fermions are at the same position or when their distance is more than 2.0/k F , the third fermion cannot affect them

  13. Preparing a highly degenerate Fermi gas in an optical lattice

    International Nuclear Information System (INIS)

    Williams, J. R.; Huckans, J. H.; Stites, R. W.; Hazlett, E. L.; O'Hara, K. M.

    2010-01-01

    We propose a method to prepare fermionic atoms in a three-dimensional optical lattice at unprecedentedly low temperatures and uniform filling factors. The process involves adiabatic loading of degenerate atoms into multiple energy bands of an optical lattice followed by a filtering stage whereby atoms from all but the lowest band are removed. Of critical importance is the use of a nonharmonic trapping potential to provide external confinement for the atoms. For realistic experimental parameters, this procedure will produce a Fermi gas in a lattice with a reduced temperature T/T F ∼0.003 and an entropy per particle of s∼0.02 k B .

  14. Thermodynamics of an Attractive 2D Fermi Gas

    Science.gov (United States)

    Fenech, K.; Dyke, P.; Peppler, T.; Lingham, M. G.; Hoinka, S.; Hu, H.; Vale, C. J.

    2016-01-01

    Thermodynamic properties of matter are conveniently expressed as functional relations between variables known as equations of state. Here we experimentally determine the compressibility, density, and pressure equations of state for an attractive 2D Fermi gas in the normal phase as a function of temperature and interaction strength. In 2D, interacting gases exhibit qualitatively different features to those found in 3D. This is evident in the normalized density equation of state, which peaks at intermediate densities corresponding to the crossover from classical to quantum behavior.

  15. Quantitative analysis of fragrance in selectable one dimensional or two dimensional gas chromatography-mass spectrometry with simultaneous detection of multiple detectors in single injection.

    Science.gov (United States)

    Tan, Hui Peng; Wan, Tow Shi; Min, Christina Liew Shu; Osborne, Murray; Ng, Khim Hui

    2014-03-14

    A selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-mass spectrometry (GC-MS) system coupled with flame ionization detector (FID) and olfactory detection port (ODP) was employed in this study to analyze perfume oil and fragrance in shower gel. A split/splitless (SSL) injector and a programmable temperature vaporization (PTV) injector are connected via a 2-way splitter of capillary flow technology (CFT) in this selectable (1)D/(2)D GC-MS/FID/ODP system to facilitate liquid sample injections and thermal desorption (TD) for stir bar sorptive extraction (SBSE) technique, respectively. The dual-linked injectors set-up enable the use of two different injector ports (one at a time) in single sequence run without having to relocate the (1)D capillary column from one inlet to another. Target analytes were separated in (1)D GC-MS/FID/ODP and followed by further separation of co-elution mixture from (1)D in (2)D GC-MS/FID/ODP in single injection without any instrumental reconfiguration. A (1)D/(2)D quantitative analysis method was developed and validated for its repeatability - tR; calculated linear retention indices (LRI); response ratio in both MS and FID signal, limit of detection (LOD), limit of quantitation (LOQ), as well as linearity over a concentration range. The method was successfully applied in quantitative analysis of perfume solution at different concentration level (RSD≤0.01%, n=5) and shower gel spiked with perfume at different dosages (RSD≤0.04%, n=5) with good recovery (96-103% for SSL injection; 94-107% for stir bar sorptive extraction-thermal desorption (SBSE-TD). Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Hidden magnetism in periodically modulated one dimensional dipolar fermions

    Science.gov (United States)

    Fazzini, S.; Montorsi, A.; Roncaglia, M.; Barbiero, L.

    2017-12-01

    The experimental realization of time-dependent ultracold lattice systems has paved the way towards the implementation of new Hubbard-like Hamiltonians. We show that in a one-dimensional two-components lattice dipolar Fermi gas the competition between long range repulsion and correlated hopping induced by periodically modulated on-site interaction allows for the formation of hidden magnetic phases, with degenerate protected edge modes. The magnetism, characterized solely by string-like nonlocal order parameters, manifests in the charge and/or in the spin degrees of freedom. Such behavior is enlighten by employing Luttinger liquid theory and numerical methods. The range of parameters for which hidden magnetism is present can be reached by means of the currently available experimental setups and probes.

  17. Universal structure of a strongly interacting Fermi gas

    Energy Technology Data Exchange (ETDEWEB)

    Kuhnle, Eva; Dyke, Paul; Hoinka, Sascha; Mark, Michael; Hu Hui; Liu Xiaji; Drummond, Peter; Hannaford, Peter; Vale, Chris, E-mail: cvale@swin.edu.au [ARC Centre of Excellence for Quantum Atom Optics, Swinburne University of Technology, Hawthorn 3122 (Australia)

    2011-01-10

    This paper presents studies of the universal properties of strongly interacting Fermi gases using Bragg spectroscopy. We focus on pair-correlations, their relationship to the contact C introduced by Tan, and their dependence on both the momentum and temperature. We show that short-range pair correlations obey a universal law, first derived by Tan through measurements of the static structure factor, which displays a universal scaling with the ratio of the contact to the momentum C/q. Bragg spectroscopy of ultracold {sup 6}Li atoms is employed to measure the structure factor for a wide range of momenta and interaction strengths, providing broad confirmation of this universal law. We show that calibrating our Bragg spectra using the f-sum rule leads to a dramatic improvement in the accuracy of the structure factor measurement. We also measure the temperature dependence of the contact in a unitary gas and compare our results to calculations based on a virial expansion.

  18. Universal relations for spin-orbit-coupled Fermi gas near an s -wave resonance

    Science.gov (United States)

    Zhang, Pengfei; Sun, Ning

    2018-04-01

    Synthetic spin-orbit-coupled quantum gases have been widely studied both experimentally and theoretically in the past decade. As shown in previous studies, this modification of single-body dispersion will in general couple different partial waves of the two-body scattering and thus distort the wave function of few-body bound states which determines the short-distance behavior of many-body wave function. In this work, we focus on the two-component Fermi gas with one-dimensional or three-dimensional spin-orbit coupling (SOC) near an s -wave resonance. Using the method of effective field theory and the operator product expansion, we derive universal relations for both systems, including the adiabatic theorem, viral theorem, and pressure relation, and obtain the momentum distribution matrix 〈ψa†(q ) ψb(q ) 〉 at large q (a ,b are spin indices). The momentum distribution matrix shows both spin-dependent and spatial anisotropic features. And the large momentum tail is modified at the subleading order thanks to the SOC. We also discuss the experimental implication of these results depending on the realization of the SOC.

  19. Full evaporation dynamic headspace in combination with selectable one-dimensional/two-dimensional gas chromatography-mass spectrometry for the determination of suspected fragrance allergens in cosmetic products.

    Science.gov (United States)

    Devos, Christophe; Ochiai, Nobuo; Sasamoto, Kikuo; Sandra, Pat; David, Frank

    2012-09-14

    Suspected fragrance allergens were determined in cosmetic products using a combination of full evaporation-dynamic headspace (FEDHS) with selectable one-dimensional/two-dimensional GC-MS. The full evaporation dynamic headspace approach allows the non-discriminating extraction and injection of both apolar and polar fragrance compounds, without contamination of the analytical system by high molecular weight non-volatile matrix compounds. The method can be applied to all classes of cosmetic samples, including water containing matrices such as shower gels or body creams. In combination with selectable (1)D/(2)D GC-MS, consisting of a dedicated heart-cutting GC-MS configuration using capillary flow technology (CFT) and low thermal mass GC (LTM-GC), a highly flexible and easy-to-use analytical solution is offered. Depending on the complexity of the perfume fraction, analyses can be performed in one-dimensional GC-MS mode or in heart-cutting two-dimensional GC-MS mode, without the need of hardware reconfiguration. The two-dimensional mode with independent temperature control of the first and second dimension column is especially useful to confirm the presence of detected allergen compounds when mass spectral deconvolution is not possible. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Faraday instability and Faraday patterns in a superfluid Fermi gas

    International Nuclear Information System (INIS)

    Tang Rongan; Xue Jukui; Li Haocai

    2011-01-01

    With the consideration of the coupling between the transverse width and the longitudinal density, the parametric excitations related to Faraday waves in a cigar-shaped superfluid Fermi gas are studied. A Mathieu equation is obtained, and it is demonstrated firstly that the excited actual 3D Faraday pattern is the combination of the longitudinal Faraday density wave and the corresponding transverse width fluctuation in the longitudinal direction. The Faraday instability growth index and the kinematic equations of the Faraday density wave and the width fluctuation along the Bose-Einstein condensate (BEC)-Bardeen-Cooper-Schrieffer (BCS) crossover are also given for the first time. It is found that the 3D Faraday pattern presents quite different behaviours (such as the excitations and the motions) when the system crosses from the BEC side to the BCS side. The coupling not only plays an important role in the parametric excitation, but also determines the dominant wavelength of the spatial structure. Along the crossover, the coupling effects are more significant in the BCS side. The final numerical investigation verifies these results and gives a detailed study of the parametric excitations (i.e. Faraday instability) and the 3D pattern formation.

  1. Myth and One-Dimensionality

    Directory of Open Access Journals (Sweden)

    William Hansen

    2017-12-01

    Full Text Available A striking difference between the folk-narrative genres of legend and folktale is how the human characters respond to supernatural, otherworldly, or uncanny beings such as ghosts, gods, dwarves, giants, trolls, talking animals, witches, and fairies. In legend the human actors respond with fear and awe, whereas in folktale they treat such beings as if they were ordinary and unremarkable. Since folktale humans treat all characters as belonging to a single realm, folklorists have described the world of the folktale as one-dimensional, in contrast to the two-dimensionality of the legend. The present investigation examines dimensionality in the third major genre of folk narrative: myth. Using the Greek and Hebrew myths of primordial paradise as sample narratives, the present essay finds—surprisingly—that the humans in these stories respond to the otherworldly one-dimensionally, as folktale characters do, and suggests an explanation for their behavior that is peculiar to the world of myth.

  2. One dimensional reactor core model

    International Nuclear Information System (INIS)

    Kostadinov, V.; Stritar, A.; Radovo, M.; Mavko, B.

    1984-01-01

    The one dimensional model of neutron dynamic in reactor core was developed. The core was divided in several axial nodes. The one group neutron diffusion equation for each node is solved. Feedback affects of fuel and water temperatures is calculated. The influence of xenon, boron and control rods is included in cross section calculations for each node. The system of equations is solved implicitly. The model is used in basic principle Training Simulator of NPP Krsko. (author)

  3. Relativistic stability of interacting Fermi gas in a strong magnetic field

    International Nuclear Information System (INIS)

    Wang Lilin; Tian Jincheng; Men Fudian; Zhang Yipeng

    2013-01-01

    By means of the single particle energy spectrum of weak interaction between fermions and Poisson formula, the thermodynamic potential function of relativistic Fermi gas in a strong magnetic field is derived. Based on this, we obtained the criterion of stability for the system. The results show that the mechanics stability of a Fermi gas with weak interacting is influenced by the interacting. While the magnetic field is able to regulate the influence and the relativistic effect has almost no effect on it. (authors)

  4. Experimental investigation of the dynamics in a strongly interacting Fermi gas : collective modes and rotational properties

    International Nuclear Information System (INIS)

    Riedl, S.

    2009-01-01

    This thesis explores the dynamics in an ultracold strongly interacting Fermi gas. Therefore we perform measurements on collective excitation modes and rotational properties of the gas. The strongly interacting gas is realized using an optically trapped Fermi gas of 6 Li atoms, where the interactions can be tuned using a broad Feshbach resonance. Our measurements allow to test the equation of state of the gas, study the transition from hydrodynamic to collisionless behavior, reveal almost ideal hydrodynamic behavior in the nonsuperfluid phase, investigate the lifetime of angular momentum, and show superfluidity through the quenching of the moment of inertia. (author)

  5. Collective molecule formation in a degenerate Fermi gas via a Feshbach resonance

    International Nuclear Information System (INIS)

    Javanainen, Juha; Kostrun, Marijan; Zheng Yi; Carmichael, Andrew; Shrestha, Uttam; Meinel, Patrick J.; Mackie, Matt; Dannenberg, Olavi; Suominen, Kalle-Antti

    2004-01-01

    We model collisionless collective conversion of a degenerate Fermi gas of atoms into bosonic molecules via a Feshbach resonance, treating the bosonic molecules as a classical field and seeding the pairing amplitudes with random phases. A dynamical instability of the Fermi sea against association with molecules drives the conversion. The model qualitatively reproduces several experimental observations [Regal et al., Nature (London) 424, 47 (2003)]. We predict that the initial temperature of the Fermi gas sets the limit for the efficiency of atom-molecule conversion

  6. Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas

    International Nuclear Information System (INIS)

    Perali, A.; Palestini, F.; Pieri, P.; Strinati, G. C.; Stewart, J. T.; Gaebler, J. P.; Drake, T. E.; Jin, D. S.

    2011-01-01

    Wave-vector resolved radio frequency spectroscopy data for an ultracold trapped Fermi gas are reported for several couplings at T c , and extensively analyzed in terms of a pairing-fluctuation theory. We map the evolution of a strongly interacting Fermi gas from the pseudogap phase into a fully gapped molecular Bose gas as a function of the interaction strength, which is marked by a rapid disappearance of a remnant Fermi surface in the single-particle dispersion. We also show that our theory of a pseudogap phase is consistent with a recent experimental observation as well as with quantum Monte Carlo data of thermodynamic quantities of a unitary Fermi gas above T c .

  7. One dimensional model for polytypes

    International Nuclear Information System (INIS)

    Rosato, A.

    1979-01-01

    The general expression for the dispersion relation for a polyatomic one dimensional crystal obtained by the Laplace Transform Method is applied to materials with the fcc and hcp structures, both consisting of close-packed planes of atoms with the stacking sequence of plane ABC/ABC... and AB/AB... respectively. The expression is also applied to polytypes, that is materials caracterized by a stacking sequence with longer repeat unit. The effective mass is cast in a condensed form useful for further calculations. The results from this simple model are only qualitative. (Author) [pt

  8. Description of a heat transfer model suitable to calculate transient processes of turbocharged diesel engines with one-dimensional gas-dynamic codes

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, J.; Lujan, J.M.; Serrano, J.R.; Dolz, V. [CMT-Motores Termicos, Universidad Politecnica de Valencia, Valencia (Spain); Guilain, S. [Renault s.a.s., Lardy (France)

    2006-01-15

    This paper describes a heat transfer model to be implemented in a global engine 1-D gas-dynamic code to calculate reciprocating internal combustion engine performance in steady and transient operations. A trade off between simplicity and accuracy has been looked for, in order to fit with the stated objective. To validate the model, the temperature of the exhaust manifold wall in a high-speed direct injection (HSDI) turbocharged diesel engine has been measured during a full load transient. In addition, an indirect assessment of the exhaust gas temperature during this transient process has been carried out. The results show good agreement between the measured and modelled data with good accuracy to predict the engine performance. A dual-walled air gap exhaust manifold has been tested in order to quantify the potential of exhaust gas thermal energy saving on engine transient performance. The experimental results together with the heat transfer model have been used to analyse the influence of thermal energy saving on dynamic performance during the load transient of an HSDI turbocharged diesel engine. (author)

  9. Thermostatistic properties of a q-deformed ideal Fermi gas with a general energy spectrum

    International Nuclear Information System (INIS)

    Cai, Shukuan; Su, Guozhen; Chen, Jincan

    2007-01-01

    The thermostatistic problems of a q-deformed ideal Fermi gas in any dimensional space and with a general energy spectrum are studied, based on the q-deformed Fermi-Dirac distribution. The effects of the deformation parameter q on the properties of the system are revealed. It is shown that q-deformation results in some novel characteristics different from those of an ordinary system. Besides, it is found that the effects of the q-deformation on the properties of the Fermi systems are very different for different dimensional spaces and different energy spectrums

  10. Analysis of Polycyclic Aromatic Hydrocarbons in Ambient Aerosols by Using One-Dimensional and Comprehensive Two-Dimensional Gas Chromatography Combined with Mass Spectrometric Method: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Yun Gyong Ahn

    2018-01-01

    Full Text Available Advanced separation technology paired with mass spectrometry is an ideal method for the analysis of atmospheric samples having complex chemical compositions. Due to the huge variety of both natural and anthropogenic sources of organic compounds, simultaneous quantification and identification of organic compounds in aerosol samples represents a demanding analytical challenge. In this regard, comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS has become an effective analytical method. However, verification and validation approaches to quantify these analytes have not been critically evaluated. We compared the performance of gas chromatography with quadrupole mass spectrometry (GC-qMS and GC×GC-TOFMS for quantitative analysis of eighteen target polycyclic aromatic hydrocarbons (PAHs. The quantitative obtained results such as limits of detection (LODs, limits of quantification (LOQs, and recoveries of target PAHs were approximately equivalent based on both analytical methods. Furthermore, a larger number of analytes were consistently identified from the aerosol samples by GC×GC-TOFMS compared to GC-qMS. Our findings suggest that GC×GC-TOFMS would be widely applicable to the atmospheric and related sciences with simultaneous target and nontarget analysis in a single run.

  11. Relativistic density matrix in the diagonal momentum representation. Fermi-gas

    International Nuclear Information System (INIS)

    Makhlin, A.N.; Sinyukov, Yu.M.

    1984-01-01

    The relativistically invariant theory of ideal Fermi-gas is built in the framework of the quantum field theory. The average occupation numbers and correlation functions of statistical systems are found on the equal-time surfaces of arbitrary inertial frames. The effects of anisotropy in their behaviour are pointed out. The partition function method is developed to calculate the thermodynamic quantities of Fermi-gases moving as a whole

  12. Solvothermal synthesis and characterisation of new one-dimensional indium and gallium sulphides: [C1N4H26]0.5[InS2] and [C1N4H26]0.5[GaS2

    International Nuclear Information System (INIS)

    Vaqueiro, Paz

    2006-01-01

    Two new main group metal sulphides, [C 1 N 4 H 26 ] 0.5 [InS 2 ] (1) and [C 1 N 4 H 26 ] 0.5 [GaS 2 ] (2) have been prepared solvothermally in the presence of 1,4-bis(3-aminopropyl)piperazine and their crystal structures determined by single-crystal X-ray diffraction. Both compounds are isostructural and crystallise in the monoclinic space group P2 1 /n (Z=4), with a=6.5628(5), b=11.2008(9), c=12.6611(9) A and β=94.410(4) o (wR=0.035) for compound (1) and a=6.1094(5), b=11.2469(9), c=12.7064(10) A and β=94.313(4) o (wR=0.021) for compound (2). The structure of [C 1 N 4 H 26 ] 0.5 [MS 2 ] (M=In,Ga) consists of one-dimensional [MS 2 ] - chains which run parallel to the crystallographic a axis and are separated by diprotonated amine molecules. These materials represent the first example of solvothermally prepared one-dimensional gallium and indium sulphides. -- Graphical abstract: [C 1 N 4 H 26 ] 0.5 [InS 2 ] and [C 1 N 4 H 26 ] 0.5 [GaS 2 ], prepared under solvothermal conditions, consist of one-dimensional [MS 2 ] - chains separated by diprotonated 1,4-bis(3-aminopropyl)piperazine molecules

  13. Superfluid quenching of the moment of inertia in a strongly interacting Fermi gas

    Science.gov (United States)

    Riedl, S.; Sánchez Guajardo, E. R.; Kohstall, C.; Hecker Denschlag, J.; Grimm, R.

    2011-03-01

    We report on the observation of a quenched moment of inertia resulting from superfluidity in a strongly interacting Fermi gas. Our method is based on setting the hydrodynamic gas in slow rotation and determining its angular momentum by detecting the precession of a radial quadrupole excitation. The measurements distinguish between the superfluid and collisional origins of hydrodynamic behavior, and show the phase transition.

  14. Special treatment of the optical potential of a spherical attractive fermi gas as a Saxon-Woods potential

    International Nuclear Information System (INIS)

    Grado-Caffaro, M.A.; Grado-Caffaro, M.

    2015-01-01

    Within a special scheme providing significant new results, we show that the (attractive) optical potential due to a spherical (non-relativistic) dilute and degenerate Fermi-Dirac gas becomes a Saxon-Woods potential which, in turn, is approximated by a truncated Dirac delta function near the center of the above spherical gas. This approximation is suitable to investigate phenomena in which fermions are restricted to move in relatively small spatial domains. In relation to this, we determine the corresponding fermion stationary wavefunctions which are found to be proportional to the aforementioned delta function if twice the fermion rest-mass multiplied by the total electron energy is much larger than the square of the reduced Planck constant. If this relationship is not fulfilled, the above fermion system is found to be roughly equivalent to fermions in an infinite one-dimensional potential well. In addition, the force field derived from the optical potential in question is determined as well as the chemical potential of the gas. Finally, application of our formulation to study electron transport in nanostructures is outlined

  15. Mean free path of nucleons in a Fermi gas at finite temperature

    International Nuclear Information System (INIS)

    Collins, M.T.; Griffin, J.J.

    1980-01-01

    The mean free path of a nucleon in a nuclear Fermi gas at finite temperature is calculated by utilizing the free nucleon-nucleon cross section modified to suppress final states excluded by the Pauli principle. The results agree with an earlier zero-temperature calculation but yield substantially smaller values than a previous finite-temperature analysis. The Fermi gas mean free paths are some two to four times shorter than those implied by phenomenological imaginary optical potentials, suggesting that the present Fermi gas model fails to adequately describe the physical processes determining the mean free path. Even so, the present results, taken as lower bounds on te mean free path, require temperatures of some 4.5 MeV before the mean free path of bound nucleons becomes as short as the nuclear diameter. It follows that very high excitation energies are prerequisite to any short mean free path assumption in nuclear heavy-ion collisions. (orig.)

  16. Shear viscosity and spin-diffusion coefficient of a two-dimensional Fermi gas

    DEFF Research Database (Denmark)

    Bruun, Georg

    2012-01-01

    Using kinetic theory, we calculate the shear viscosity and the spin-diffusion coefficient as well as the associated relaxation times for a two-component Fermi gas in two dimensions, as a function of temperature, coupling strength, polarization, and mass ratio of the two components. It is demonstr......Using kinetic theory, we calculate the shear viscosity and the spin-diffusion coefficient as well as the associated relaxation times for a two-component Fermi gas in two dimensions, as a function of temperature, coupling strength, polarization, and mass ratio of the two components....... It is demonstrated that the minimum value of the viscosity decreases with the mass ratio, since Fermi blocking becomes less efficient. We furthermore analyze recent experimental results for the quadrupole mode of a two-dimensional gas in terms of viscous damping, obtaining a qualitative agreement using no fitting...

  17. The finite-temperature thermodynamics of a trapped unitary Fermi gas within fractional exclusion statistics

    International Nuclear Information System (INIS)

    Qin Fang; Chen Jisheng

    2010-01-01

    We utilize the fractional exclusion statistics of the Haldane and Wu hypothesis to study the thermodynamics of a unitary Fermi gas trapped in a harmonic oscillator potential at ultra-low finite temperature. The entropy per particle as a function of the energy per particle and energy per particle versus rescaled temperature are numerically compared with the experimental data. The study shows that, except the chemical potential behaviour, there exists a reasonable consistency between the experimental measurement and theoretical attempt for the entropy and energy per particle. In the fractional exclusion statistics formalism, the behaviour of the isochore heat capacity for a trapped unitary Fermi gas is also analysed.

  18. Analytical thermodynamics of a strongly attractive three-component Fermi gas in one dimension

    International Nuclear Information System (INIS)

    He Peng; Yin Xiangguo; Wang Yupeng; Guan Xiwen; Batchelor, Murray T.

    2010-01-01

    Ultracold three-component atomic Fermi gases in one dimension are expected to exhibit rich physics due to the presence of trions and different pairing states. Quantum phase transitions from the trion state into a paired phase and a normal Fermi liquid occur at zero temperature. We derive the analytical thermodynamics of strongly attractive three-component one-dimensional fermions with SU(3) symmetry via the thermodynamic Bethe ansatz method in unequal Zeeman splitting fields H 1 and H 2 . We find explicitly that for low temperature the system acts like either a two-component or a three-component Tomonaga-Luttinger liquid dependent on the system parameters. The phase diagrams for the chemical potential and specific heat are presented for illustrative values of the Zeeman splitting. We also demonstrate that crossover between different Tomonaga-Luttinger-liquid phases exhibit singular behavior in specific heat and entropy as the temperature tends to zero. Beyond Tomonaga-Luttinger-liquid physics, we obtain the equation of state which provides a precise description of universal thermodynamics and quantum criticality in three-component, strongly attractive Fermi gases.

  19. Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium

    DEFF Research Database (Denmark)

    Aikawa, K.; Frisch, A.; Mark, M.

    2014-01-01

    We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic $^{167}$Er fermions, spin-polarized in the lowest Zeeman sublevel. In this system, elastic...

  20. One-Dimensional Photonic Crystal Superprisms

    Science.gov (United States)

    Ting, David

    2005-01-01

    Theoretical calculations indicate that it should be possible for one-dimensional (1D) photonic crystals (see figure) to exhibit giant dispersions known as the superprism effect. Previously, three-dimensional (3D) photonic crystal superprisms have demonstrated strong wavelength dispersion - about 500 times that of conventional prisms and diffraction gratings. Unlike diffraction gratings, superprisms do not exhibit zero-order transmission or higher-order diffraction, thereby eliminating cross-talk problems. However, the fabrication of these 3D photonic crystals requires complex electron-beam substrate patterning and multilayer thin-film sputtering processes. The proposed 1D superprism is much simpler in structural complexity and, therefore, easier to design and fabricate. Like their 3D counterparts, the 1D superprisms can exhibit giant dispersions over small spectral bands that can be tailored by judicious structure design and tuned by varying incident beam direction. Potential applications include miniature gas-sensing devices.

  1. A two-dimensional Fermi gas in the BEC-BCS crossover

    Energy Technology Data Exchange (ETDEWEB)

    Ries, Martin Gerhard

    2016-01-21

    This thesis reports on the preparation of a 2D Fermi gas in the BEC-BCS crossover and the observation of the BKT transition into a quasi long-range ordered superfluid phase. The pair momentum distribution of the gas is probed by means of a matter-wave focusing technique which relies on time-of-flight evolution in a weak harmonic potential. This distribution holds the coherence properties of the gas. The quasi long-range ordered phase manifests itself as a sharp low-momentum peak. The temperature where it forms is identified as the transition temperature. By tuning the temperature and the interaction strength, the phase diagram of the 2D Fermi gas in the BEC-BCS crossover is mapped out. The phase coherence is investigated in a self-interference experiment. Furthermore, algebraic decay of correlations is observed in the trap average of the first order correlation function, which is obtained from the Fourier transform of the pair momentum distribution. This is in qualitative agreement with predictions of homogeneous theory for the superfluid phase in a 2D gas. The presented results provide a foundation for future experimental and theoretical studies of strongly correlated 2D Fermi gases. They might thus help to elucidate complex systems such as the electron gas in high-T{sub c} superconductors.

  2. Quasi-one-dimensional metals on semiconductor surfaces with defects

    International Nuclear Information System (INIS)

    Hasegawa, Shuji

    2010-01-01

    Several examples are known in which massive arrays of metal atomic chains are formed on semiconductor surfaces that show quasi-one-dimensional metallic electronic structures. In this review, Au chains on Si(557) and Si(553) surfaces, and In chains on Si(111) surfaces, are introduced and discussed with regard to the physical properties determined by experimental data from scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES) and electrical conductivity measurements. They show quasi-one-dimensional Fermi surfaces and parabolic band dispersion along the chains. All of them are known from STM and ARPES to exhibit metal-insulator transitions by cooling and charge-density-wave formation due to Peierls instability of the metallic chains. The electrical conductivity, however, reveals the metal-insulator transition only on the less-defective surfaces (Si(553)-Au and Si(111)-In), but not on a more-defective surface (Si(557)-Au). The latter shows an insulating character over the whole temperature range. Compared with the electronic structure (Fermi surfaces and band dispersions), the transport property is more sensitive to the defects. With an increase in defect density, the conductivity only along the metal atomic chains was significantly reduced, showing that atomic-scale point defects decisively interrupt the electrical transport along the atomic chains and hide the intrinsic property of transport in quasi-one-dimensional systems.

  3. Response Functions for the Two-Dimensional Ultracold Fermi Gas: Dynamical BCS Theory and Beyond

    Science.gov (United States)

    Vitali, Ettore; Shi, Hao; Qin, Mingpu; Zhang, Shiwei

    2017-12-01

    Response functions are central objects in physics. They provide crucial information about the behavior of physical systems, and they can be directly compared with scattering experiments involving particles such as neutrons or photons. Calculations of such functions starting from the many-body Hamiltonian of a physical system are challenging and extremely valuable. In this paper, we focus on the two-dimensional (2D) ultracold Fermi atomic gas which has been realized experimentally. We present an application of the dynamical BCS theory to obtain response functions for different regimes of interaction strengths in the 2D gas with zero-range attractive interaction. We also discuss auxiliary-field quantum Monte Carlo (AFQMC) methods for the calculation of imaginary time correlations in these dilute Fermi gas systems. Illustrative results are given and comparisons are made between AFQMC and dynamical BCS theory results to assess the accuracy of the latter.

  4. Zero sound in a two-dimensional dipolar Fermi gas

    NARCIS (Netherlands)

    Lu, Z.K.; Matveenko, S.I.; Shlyapnikov, G.V.

    2013-01-01

    We study zero sound in a weakly interacting two-dimensional (2D) gas of single-component fermionic dipoles (polar molecules or atoms with a large magnetic moment) tilted with respect to the plane of their translational motion. It is shown that the propagation of zero sound is provided by both

  5. Current correlation functions of ideal Fermi gas at finite temperature

    Indian Academy of Sciences (India)

    in the study of time dependent density functional theory [5] due to the work of Vignale and. Kohn [6,7]. They obtained ... part has relevance to the study of viscous effects [10] in the electron gas and to the dia- magnetic ... is found that the diamagnetic susceptibility, related to the transverse part, smoothly cross over from ...

  6. Thermal conductivity in one-dimensional nonlinear systems

    Science.gov (United States)

    Politi, Antonio; Giardinà, Cristian; Livi, Roberto; Vassalli, Massimo

    2000-03-01

    Thermal conducitivity of one-dimensional nonlinear systems typically diverges in the thermodynamic limit, whenever the momentum is conserved (i.e. in the absence of interactions with an external substrate). Evidence comes from detailed studies of Fermi-Pasta-Ulam and diatomic Toda chains. Here, we discuss the first example of a one-dimensional system obeying Fourier law : a chain of coupled rotators. Numerical estimates of the thermal conductivity obtained by simulating a chain in contact with two thermal baths at different temperatures are found to be consistent with those ones based on linear response theory. The dynamics of the Fourier modes provides direct evidence of energy diffusion. The finiteness of the conductivity is traced back to the occurrence of phase-jumps. Our conclusions are confirmed by the analysis of two variants of the rotator model.

  7. Isobaric expansion coefficient and isothermal compressibility for a finite-size ideal Fermi gas system

    International Nuclear Information System (INIS)

    Su, Guozhen; Chen, Liwei; Chen, Jincan

    2014-01-01

    Due to quantum size effects (QSEs), the isobaric thermal expansion coefficient and isothermal compressibility well defined for macroscopic systems are invalid for finite-size systems. The two parameters are redefined and calculated for a finite-size ideal Fermi gas confined in a rectangular container. It is found that the isobaric thermal expansion coefficient and isothermal compressibility are generally anisotropic, i.e., they are generally different in different directions. Moreover, it is found the thermal expansion coefficient may be negative in some directions under the condition that the pressures in all directions are kept constant. - Highlights: • Isobaric thermal expansion coefficient and isothermal compressibility are redefined. • The two parameters are calculated for a finite-size ideal Fermi gas. • The two parameters are generally anisotropic for a finite-size system. • Isobaric thermal expansion coefficient may be negative in some directions

  8. Fermi-Dirac gas of atoms in a box with low adiabatic invariant

    International Nuclear Information System (INIS)

    Vlad, V.I.; Inonescu-Pallas, N.

    2004-06-01

    Quantum degenerate Fermi-Dirac gas of atoms, confined in a cubic box, shows an energy spectrum, which is discrete and strongly dependent on the atomic mass number, A at , box geometry and temperature, for low product of A at and the adiabatic invariant, TV 1/3 , i.e. on γ = A at TV 1/3 . The present study compares the total number of particles and the total energy obtained by summing up the contributions of a finite number of states, defined by the values of γ, to the widespread approximations of the corresponding integrals. The sums show simple calculation algorithms and more precise results for a large interval of values of γ. A new accurate analytic formula for the chemical potential of the Fermi-Dirac quantum gas is also given. (author)

  9. Implementing the correlated fermi gas nuclear model for quasielastic neutrino-nucleus scattering

    Science.gov (United States)

    Tockstein, Jameson

    2017-09-01

    When studying neutrino oscillations an understanding of charged current quasielastic (CCQE) neutrino-nucleus scattering is imperative. This interaction depends on a nuclear model as well as knowledge of form factors. Neutrino experiments, such as MiniBooNE, often use the Relativistic Fermi Gas (RFG) nuclear model. Recently, the Correlated Fermi Gas (CFG) nuclear model was suggested in, based on inclusive and exclusive scattering experiments at JLab. We implement the CFG model for CCQE scattering. In particular, we provide analytic expressions for this implementation that can be used to analyze current and future neutrino CCQE data. This project was supported through the Wayne State University REU program under NSF Grant PHY-1460853 and by the DOE Grant DE-SC0007983.

  10. Anisotropic superfluidity in the two-species polar Fermi gas

    International Nuclear Information System (INIS)

    Liao Renyuan; Brand, Joachim

    2010-01-01

    We study the superfluid pairing in a two-species gas of heteronuclear fermionic molecules with equal density. The interplay of the isotropic s-wave interaction and anisotropic long-range dipolar interaction reveals rich physics. We find that the single-particle momentum distribution has a characteristic ellipsoidal shape that can be reasonably represented by a deformation parameter α defined similarly to the normal phase. Interesting momentum-dependent features of the order parameter are identified. We calculate the critical temperatures of both the singlet and triplet superfluids, suggesting a possible pairing symmetry transition by tuning the s-wave or dipolar interaction strength.

  11. Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance

    International Nuclear Information System (INIS)

    Conduit, G. J.; Simons, B. D.

    2009-01-01

    We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi gas with repulsive interactions and population imbalance. In a spatially uniform system, we show that at zero temperature the transition to the itinerant magnetic phase transforms from first to second order with increasing population imbalance. Drawing on these results, we elucidate the phases present in a trapped geometry, finding three characteristic types of behavior with changing population imbalance. Finally, we outline the potential experimental implications of the findings.

  12. Phase diagram of a polarized Fermi gas across a Feshbach resonance in a potential trap

    International Nuclear Information System (INIS)

    Yi, W.; Duan, L.-M.

    2006-01-01

    We map out the detailed phase diagram of a trapped ultracold Fermi gas with population imbalance across a wide Feshbach resonance. We show that under the local density approximation, the properties of the atoms in any (anisotropic) harmonic traps are universally characterized by three dimensionless parameters: the normalized temperature, the dimensionless interaction strength, and the population imbalance. We then discuss the possible quantum phases in the trap, and quantitatively characterize their phase boundaries in various typical parameter regions

  13. Spectral zeta function and non-perturbative effects in ABJM Fermi-gas

    International Nuclear Information System (INIS)

    Hatsuda, Yasuyuki

    2015-03-01

    The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of ''non-perturbative'' poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example associated with a spectral problem in topological string theory. A conjectured non-perturbative free energy on the resolved conifold is successfully reproduced in this framework.

  14. E Fermi

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. E Fermi. Articles written in Resonance – Journal of Science Education. Volume 19 Issue 1 January 2014 pp 82-96 Classics. Quantization of an Ideal Monoatomic Gas · E Fermi · More Details Fulltext PDF ...

  15. Approximate characteristics for one-dimensional two-phase flows

    International Nuclear Information System (INIS)

    Sarayloo, A.; Peddleson, J.

    1985-01-01

    An approximate method for determining the characteristics associated with one-dimensional particulate two-phase flow models is presented. The method is based on iteration and is valid for small particulate volume fractions. The method is applied to several special cases involving incompressible particles suspended in a gas. The influences of certain changes in the physical model are investigated

  16. One-Dimensional Czedli-Type Islands

    Science.gov (United States)

    Horvath, Eszter K.; Mader, Attila; Tepavcevic, Andreja

    2011-01-01

    The notion of an island has surfaced in recent algebra and coding theory research. Discrete versions provide interesting combinatorial problems. This paper presents the one-dimensional case with finitely many heights, a topic convenient for student research.

  17. Analytical solution of one dimensional temporally dependent ...

    African Journals Online (AJOL)

    user

    transfer of heat in fluids, flow through porous media, and the spread of ... In present paper, advection-dispersion equation is considered one dimensional longitudinal initially solute free semi- .... free. Thus initial and boundary conditions for eq.

  18. Factorizations of one-dimensional classical systems

    International Nuclear Information System (INIS)

    Kuru, Senguel; Negro, Javier

    2008-01-01

    A class of one-dimensional classical systems is characterized from an algebraic point of view. The Hamiltonians of these systems are factorized in terms of two functions that together with the Hamiltonian itself close a Poisson algebra. These two functions lead directly to two time-dependent integrals of motion from which the phase motions are derived algebraically. The systems so obtained constitute the classical analogues of the well known factorizable one-dimensional quantum mechanical systems

  19. One-dimensional photonic crystal design

    International Nuclear Information System (INIS)

    Mee, Cornelis van der; Contu, Pietro; Pintus, Paolo

    2010-01-01

    In this article we present a method to determine the band spectrum, band gaps, and discrete energy levels, of a one-dimensional photonic crystal with localized impurities. For one-dimensional crystals with piecewise constant refractive indices we develop an algorithm to recover the refractive index distribution from the period map. Finally, we derive the relationship between the period map and the scattering matrix containing the information on the localized modes.

  20. Polyacene and a new class of quasi-one-dimensional conductors

    International Nuclear Information System (INIS)

    Kivelson, S.; Chapman, O.L.

    1983-01-01

    Most one-dimensional conductors are quite similar since the Fermi surface is a point and the electron energy dispersion relation near the Fermi surface is linear. It is pointed out that in polyacene the Fermi surface lies at the edge of the Brillouin zone, but that an accidental degeneracy between the valence and conduction bands makes it metallic nonetheless. The dispersion relation is therefore quadratic, and the density of states diverges at the Fermi surface. Thus, polyacene [(C 4 H 2 )/sub n/] and its possible derivatives represent a conceptually new class of quasi-one-dimensional conductors. Moreover, we find that this class of materials has the possibility of possessing interesting condensed phases including high-temperature superconductivity and ferromagnetism

  1. Kohn's theorem in a superfluid Fermi gas with a Feshbach resonance

    International Nuclear Information System (INIS)

    Ohashi, Y.

    2004-01-01

    We investigate the dipole mode in a superfluid gas of Fermi atoms trapped in a harmonic potential. According to Kohn's theorem, the frequency of this collective mode is not affected by an interaction between the atoms and is always equal to the trap frequency. This remarkable property, however, does not necessarily hold in an approximate theory. We explicitly prove that the Hartree-Fock-Bogoliubov generalized random phase approximation (HFB-GRPA), including a coupling between fluctuations in the density and Cooper channels, is consistent with both Kohn's theorem as well as Goldstone's theorem. This proof can be immediately extended to the strong-coupling superfluid theory developed by Nozieres and Schmitt-Rink (NSR), where the effect of superfluid fluctuations is included within the Gaussian level. As a result, the NSR-GRPA formalism can be used to study collective modes in the BCS-BEC crossover region in a manner which is consistent with Kohn's theorem. We also include the effect of a Feshbach resonance and a condensate of the associated molecular bound states. A detailed discussion is given of the unusual nature of the Kohn mode eigenfunctions in a Fermi superfluid, in the presence and absence of a Feshbach resonance. When the molecular bosons feel a different trap frequency from the Fermi atoms, the dipole frequency is shown to depend on the strength of effective interaction associated with the Feshbach resonance

  2. Fermi-edge superfluorescence from a quantum-degenerate electron-hole gas

    Science.gov (United States)

    Kim, Ji-Hee; , G. Timothy Noe, II; McGill, Stephen A.; Wang, Yongrui; Wójcik, Aleksander K.; Belyanin, Alexey A.; Kono, Junichiro

    2013-11-01

    Nonequilibrium can be a source of order. This rather counterintuitive statement has been proven to be true through a variety of fluctuation-driven, self-organization behaviors exhibited by out-of-equilibrium, many-body systems in nature (physical, chemical, and biological), resulting in the spontaneous appearance of macroscopic coherence. Here, we report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence (SF), which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary SF, making electron-hole SF even more ``super'' than atomic SF.

  3. Observation of Dynamical Super-Efimovian Expansion in a Unitary Fermi Gas

    Science.gov (United States)

    Deng, Shujin; Diao, Pengpeng; Li, Fang; Yu, Qianli; Yu, Shi; Wu, Haibin

    2018-03-01

    We report an observation of a dynamical super Efimovian expansion in a strongly interacting Fermi gas by engineering time dependent external harmonic trap frequencies. When the trap frequency is tailored as [1 /4 t2+1 /t2λ log2(t /t*)]1/2, where t* and λ are two controllable parameters, and the change is faster than a critical value, the expansion of such a quantum gas shows novel dynamics that share the same characteristics as the super Efimov effect. A clear double-log periodicity with discrete geometric scaling emerges for the cloud size in the expansion. The universality of such scaling dynamics is verified both in the noninteracting and in the unitarity limit of Fermi gas. Moreover, the measured energy scaling reveals that the potential and internal energy also show double-log periodicity with a π /2 phase difference, but the total energy is monotonically decreased. Observing super Efimovian evolution represents a paradigm in probing universal properties and allows us in a new way to study many-body nonequilibrium dynamics with experiments.

  4. Conversion of a Degenerate Fermi Gas of 6Li Atoms to a Molecular BEC

    International Nuclear Information System (INIS)

    Strecker, K.E.; Partridge, G.B.; Kamar, R.I.; Jack, M.W.; Hulet, R.G.

    2005-01-01

    Atomic Feshbach resonances have recently been used to produce a strongly interacting Fermi gas, where the BCS/BEC crossover can be explored. We have used both narrow and broad Feshbach resonances to convert a quantum degenerate Fermi gas of 6Li atoms into an ultracold gas of Li2 molecules. For the narrow resonances, the molecules are formed by coherent adiabatic passage through the resonance. We find that 50% of the atoms are converted to molecules. Furthermore, the lifetime of these molecules was measured to be surprisingly long, 1 s. We will discuss these measurements in the context of the present theoretical understanding. Molecules can also be formed using static fields near the broad Feshbach resonance. The lifetime of these molecules is again long, and sufficient to enable their evaporation to a Bose-Einstein condensate. Phase contrast images of the molecular condensate are presented. The BCS/BEC crossover may be explored by starting with a pure molecular condensate on the low-field side of the Feshbach resonance, and adiabatically changing the field to any final value around resonance. We combine this ability with optical spectroscopy on a bound-bound molecular transition to probe the nature of the many-body wavefunction in the crossover regime

  5. Temperature and coupling dependence of the universal contact intensity for an ultracold Fermi gas

    International Nuclear Information System (INIS)

    Palestini, F.; Perali, A.; Pieri, P.; Strinati, G. C.

    2010-01-01

    Physical properties of an ultracold Fermi gas in the temperature-coupling phase diagram can be characterized by the contact intensity C, which enters the pair-correlation function at short distances and describes how the two-body problem merges into its surrounding. We show that the local order established by pairing fluctuations about the critical temperature T c of the superfluid transition considerably enhances the contact C in a temperature range where pseudogap phenomena are maximal. Our ab initio results for C in a trap compare well with recently available experimental data over a wide coupling range. An analysis is also provided for the effects of trap averaging on C.

  6. Generalized virial theorem and pressure relation for a strongly correlated Fermi gas

    International Nuclear Information System (INIS)

    Tan, Shina

    2008-01-01

    For a two-component Fermi gas in the unitarity limit (i.e., with infinite scattering length), there is a well-known virial theorem, first shown by J.E. Thomas et al. A few people rederived this result, and extended it to few-body systems, but their results are all restricted to the unitarity limit. Here I show that there is a generalized virial theorem for FINITE scattering lengths. I also generalize an exact result concerning the pressure to the case of imbalanced populations

  7. Universal Behavior of Pair Correlations in a Strongly Interacting Fermi Gas

    International Nuclear Information System (INIS)

    Kuhnle, E. D.; Hu, H.; Liu, X.-J.; Dyke, P.; Mark, M.; Drummond, P. D.; Hannaford, P.; Vale, C. J.

    2010-01-01

    We show that short-range pair correlations in a strongly interacting Fermi gas follow a simple universal law described by Tan's relations. This is achieved through measurements of the static structure factor which displays a universal scaling proportional to the ratio of Tan's contact to the momentum C/q. Bragg spectroscopy of ultracold 6 Li atoms from a periodic optical potential is used to measure the structure factor for a wide range of momenta and interaction strengths, providing broad confirmation of this universal law. We calibrate our Bragg spectra using the f-sum rule, which is found to improve the accuracy of the structure factor measurement.

  8. One-dimensional Gromov minimal filling problem

    International Nuclear Information System (INIS)

    Ivanov, Alexandr O; Tuzhilin, Alexey A

    2012-01-01

    The paper is devoted to a new branch in the theory of one-dimensional variational problems with branching extremals, the investigation of one-dimensional minimal fillings introduced by the authors. On the one hand, this problem is a one-dimensional version of a generalization of Gromov's minimal fillings problem to the case of stratified manifolds. On the other hand, this problem is interesting in itself and also can be considered as a generalization of another classical problem, the Steiner problem on the construction of a shortest network connecting a given set of terminals. Besides the statement of the problem, we discuss several properties of the minimal fillings and state several conjectures. Bibliography: 38 titles.

  9. Many-body pairing in a two-dimensional Fermi gas

    Energy Technology Data Exchange (ETDEWEB)

    Neidig, Mathias

    2017-05-24

    This thesis reports on experiments conducted in a single layer, quasi two-dimensional, two-component ultracold Fermi gas in the strongly interacting regime. Ultracold gases can be used to simulate key aspects of more complicated systems like for example cuprates which show high-T{sub c} superconductivity. The momentum distribution of a sample of bosonic dimers in a quasi-2D square lattice geometry was measured to obtain the coherence properties. For shallow lattices, sharp peaks in the momentum distribution, indicating coherence, were observed at zero momentum as well as at positive and negative lattice momenta along each axis. For deeper lattices, heating impeded the ability to prepare a Mott-insulator. A spatially resolved radio-frequency spectroscopy was employed for a quasi-2D Fermi gas in the normal phase throughout the BEC-BCS crossover. The interaction induced energy shifts were measured in the strongly interacting region where they can be on the order of the Fermi energy and thus the local resolution is crucial. Furthermore, the onset of pairing in the strongly interacting region was measured as a function of temperature and it was shown that the fraction of free atoms decreases faster than expected from thermal non-interacting theory. At last, the pairing gap was measured using an imbalanced sample. On the BEC side it was found to be in very good agreement with two-body physics as expected. In the strongly interacting regime, however, a deviation from two-body physics indicates that here many-body effects play a role and thus further studies are required.

  10. Sounds in one-dimensional superfluid helium

    International Nuclear Information System (INIS)

    Um, C.I.; Kahng, W.H.; Whang, E.H.; Hong, S.K.; Oh, H.G.; George, T.F.

    1989-01-01

    The temperature variations of first-, second-, and third-sound velocity and attenuation coefficients in one-dimensional superfluid helium are evaluated explicitly for very low temperatures and frequencies (ω/sub s/tau 2 , and the ratio of second sound to first sound becomes unity as the temperature decreases to absolute zero

  11. QUASI-ONE DIMENSIONAL CLASSICAL FLUIDS

    Directory of Open Access Journals (Sweden)

    J.K.Percus

    2003-01-01

    Full Text Available We study the equilibrium statistical mechanics of simple fluids in narrow pores. A systematic expansion is made about a one-dimensional limit of this system. It starts with a density functional, constructed from projected densities, which depends upon projected one and two-body potentials. The nature of higher order corrections is discussed.

  12. Highly conducting one-dimensional solids

    CERN Document Server

    Evrard, Roger; Doren, Victor

    1979-01-01

    Although the problem of a metal in one dimension has long been known to solid-state physicists, it was not until the synthesis of real one-dimensional or quasi-one-dimensional systems that this subject began to attract considerable attention. This has been due in part to the search for high­ temperature superconductivity and the possibility of reaching this goal with quasi-one-dimensional substances. A period of intense activity began in 1973 with the report of a measurement of an apparently divergent conduc­ tivity peak in TfF-TCNQ. Since then a great deal has been learned about quasi-one-dimensional conductors. The emphasis now has shifted from trying to find materials of very high conductivity to the many interesting problems of physics and chemistry involved. But many questions remain open and are still under active investigation. This book gives a review of the experimental as well as theoretical progress made in this field over the last years. All the chapters have been written by scientists who have ...

  13. Remarks for one-dimensional fractional equations

    Directory of Open Access Journals (Sweden)

    Massimiliano Ferrara

    2014-01-01

    Full Text Available In this paper we study a class of one-dimensional Dirichlet boundary value problems involving the Caputo fractional derivatives. The existence of infinitely many solutions for this equations is obtained by exploiting a recent abstract result. Concrete examples of applications are presented.

  14. Controlled size and one-dimensional growth

    Indian Academy of Sciences (India)

    875–881. c Indian Academy of Sciences. Synthesis of azamacrocycle stabilized palladium nanoparticles: Controlled size and one-dimensional growth. JEYARAMAN ATHILAKSHMI and DILLIP KUMAR CHAND. ∗. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India e-mail: dillip@iitm.ac.

  15. High-temperature behavior of a deformed Fermi gas obeying interpolating statistics.

    Science.gov (United States)

    Algin, Abdullah; Senay, Mustafa

    2012-04-01

    An outstanding idea originally introduced by Greenberg is to investigate whether there is equivalence between intermediate statistics, which may be different from anyonic statistics, and q-deformed particle algebra. Also, a model to be studied for addressing such an idea could possibly provide us some new consequences about the interactions of particles as well as their internal structures. Motivated mainly by this idea, in this work, we consider a q-deformed Fermi gas model whose statistical properties enable us to effectively study interpolating statistics. Starting with a generalized Fermi-Dirac distribution function, we derive several thermostatistical functions of a gas of these deformed fermions in the thermodynamical limit. We study the high-temperature behavior of the system by analyzing the effects of q deformation on the most important thermostatistical characteristics of the system such as the entropy, specific heat, and equation of state. It is shown that such a deformed fermion model in two and three spatial dimensions exhibits the interpolating statistics in a specific interval of the model deformation parameter 0 < q < 1. In particular, for two and three spatial dimensions, it is found from the behavior of the third virial coefficient of the model that the deformation parameter q interpolates completely between attractive and repulsive systems, including the free boson and fermion cases. From the results obtained in this work, we conclude that such a model could provide much physical insight into some interacting theories of fermions, and could be useful to further study the particle systems with intermediate statistics.

  16. Correlation functions of one-dimensional bosons at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

    2010-12-15

    We consider the low-temperature limit of the long-distance asymptotic behavior of the finite temperature density-density correlation function in the one-dimensional Bose gas derived recently in the algebraic Bethe Ansatz framework. Our results confirm the predictions based on the Luttinger liquid and conformal field theory approaches. We also demonstrate that the amplitudes arising in this asymptotic expansion at low-temperature coincide with the amplitudes associated with the so-called critical form factors. (orig.)

  17. A study of correlation functions for the delta-function fermi gas

    International Nuclear Information System (INIS)

    Berkovich, A.

    1987-01-01

    In this dissertation, the author considers the quantum nonlinear Schrodinger model, describing a non-relativistic, finite-density gas of one-dimensional fermions with repulsive delta-function interaction. The author employs the quantum inverse scattering method and temperature Green function technique to derive some new results for the two-point, equal-time correlation function. For the case of zero temperature, it is shown that the correlation function in the infinite coupling limit (c → ∞) can be expressed concisely in terms of the solution of the Painleve equation of the fifth kind. The author, then, extends this result and obtains an exact expression for the order (1/c) correction to the two-point function in terms of the Painleve transcendents. This work is essentially self-contained; both old and new results are presented and discussed at some length

  18. Realization of Configurable One-Dimensional Reflectarray

    Science.gov (United States)

    2017-08-31

    experiments show strong signatures of beam steering that are dependent upon graphene doping. This seed grant has allowed our team to establish the essential...based, one-dimensional reflectarrays. Several immediate improvements to the device design and process flow are essential to suppress specular...beam steering that are dependent upon graphene doping. This seed grant has allowed our team to establish the essential operating procedures (i.e

  19. Impurity coupled to an artificial magnetic field in a Fermi gas in a ring trap

    Science.gov (United States)

    Ünal, F. Nur; Hetényi, B.; Oktel, M. Ã.-.

    2015-05-01

    The dynamics of a single impurity interacting with a many-particle background is one of the central problems of condensed-matter physics. Recent progress in ultracold-atom experiments makes it possible to control this dynamics by coupling an artificial gauge field specifically to the impurity. In this paper, we consider a narrow toroidal trap in which a Fermi gas is interacting with a single atom. We show that an external magnetic field coupled to the impurity is a versatile tool to probe the impurity dynamics. Using a Bethe ansatz, we calculate the eigenstates and corresponding energies exactly as a function of the flux through the trap. Adiabatic change of flux connects the ground state to excited states due to flux quantization. For repulsive interactions, the impurity disturbs the Fermi sea by dragging the fermions whose momentum matches the flux. This drag transfers momentum from the impurity to the background and increases the effective mass. The effective mass saturates to the total mass of the system for infinitely repulsive interactions. For attractive interactions, the drag again increases the effective mass which quickly saturates to twice the mass of a single particle as a dimer of the impurity and one fermion is formed. For excited states with momentum comparable to number of particles, effective mass shows a resonant behavior. We argue that standard tools in cold-atom experiments can be used to test these predictions.

  20. First and second sound of a unitary Fermi gas in highly oblate harmonic traps

    International Nuclear Information System (INIS)

    Hu, Hui; Dyke, Paul; Vale, Chris J; Liu, Xia-Ji

    2014-01-01

    We theoretically investigate first and second sound modes of a unitary Fermi gas trapped in a highly oblate harmonic trap at finite temperatures. Following the idea by Stringari and co-workers (2010 Phys. Rev. Lett. 105 150402), we argue that these modes can be described by the simplified two-dimensional two-fluid hydrodynamic equations. Two possible schemes—sound wave propagation and breathing mode excitation—are considered. We calculate the sound wave velocities and discretized sound mode frequencies, as a function of temperature. We find that in both schemes, the coupling between first and second sound modes is large enough to induce significant density fluctuations, suggesting that second sound can be directly observed by measuring in situ density profiles. The frequency of the second sound breathing mode is found to be highly sensitive to the superfluid density. (paper)

  1. Nonequilibrium Spin Dynamics in a Trapped Fermi Gas with Effective Spin-Orbit Interactions

    International Nuclear Information System (INIS)

    Stanescu, Tudor D.; Zhang Chuanwei; Galitski, Victor

    2007-01-01

    We consider a trapped atomic system in the presence of spatially varying laser fields. The laser-atom interaction generates a pseudospin degree of freedom (referred to simply as spin) and leads to an effective spin-orbit coupling for the fermions in the trap. Reflections of the fermions from the trap boundaries provide a physical mechanism for effective momentum relaxation and nontrivial spin dynamics due to the emergent spin-orbit coupling. We explicitly consider evolution of an initially spin-polarized Fermi gas in a two-dimensional harmonic trap and derive nonequilibrium behavior of the spin polarization. It shows periodic echoes with a frequency equal to the harmonic trapping frequency. Perturbations, such as an asymmetry of the trap, lead to the suppression of the spin echo amplitudes. We discuss a possible experimental setup to observe spin dynamics and provide numerical estimates of relevant parameters

  2. Dynamic structure factor of the normal Fermi gas from the collisionless to the hydrodynamic regime

    International Nuclear Information System (INIS)

    Watabe, Shohei; Nikuni, Tetsuro

    2010-01-01

    The dynamic structure factor of a normal Fermi gas is investigated by using the moment method for the Boltzmann equation. We determine the spectral function at finite temperatures over the full range of crossover from the collisionless regime to the hydrodynamic regime. We find that the Brillouin peak in the dynamic structure factor exhibits a smooth crossover from zero to first sound as functions of temperature and interaction strength. The dynamic structure factor obtained using the moment method also exhibits a definite Rayleigh peak (ω∼0), which is a characteristic of the hydrodynamic regime. We compare the dynamic structure factor obtained by the moment method with that obtained from the hydrodynamic equations.

  3. One-dimensional plasma simulation studies

    International Nuclear Information System (INIS)

    Friberg, Ari; Virtamo, Jorma

    1976-01-01

    Some basic plasma phenomena are studied by a one-dimensional electrostatic simulation code. A brief description of the code and its application to a test problem is given. The experiments carried out include Landau damping of an excited wave, particle retardation by smoothed field and beam-plasma instability. In each case, the set-up of the experiment is described and the results are compared with theoretical predictions. In the theoretical discussions, the oscillatory behaviour found in the Landau damping experiment is explained, an explicit formula for the particle retardation rate is derived and a rudimentary picture of the beam-plasma instability in terms of quasilinear theory is given. (author)

  4. Solitons in one-dimensional antiferromagnetic chains

    International Nuclear Information System (INIS)

    Pires, A.S.T.; Talim, S.L.; Costa, B.V.

    1989-01-01

    We study the quantum-statistical mechanics, at low temperatures, of a one-dimensional antiferromagnetic Heisenberg model with two anisotropies. In the weak-coupling limit we determine the temperature dependences of the soliton energy and the soliton density. We have found that the leading correction to the sine-Gordon (SG) expression for the soliton density and the quantum soliton energy comes from the out-of-plane magnon mode, not present in the pure SG model. We also show that when an external magnetic field is applied, the chain supports a new type of kink, where the sublattices rotate in opposite directions

  5. One-dimensional hypersonic phononic crystals.

    Science.gov (United States)

    Gomopoulos, N; Maschke, D; Koh, C Y; Thomas, E L; Tremel, W; Butt, H-J; Fytas, G

    2010-03-10

    We report experimental observation of a normal incidence phononic band gap in one-dimensional periodic (SiO(2)/poly(methyl methacrylate)) multilayer film at gigahertz frequencies using Brillouin spectroscopy. The band gap to midgap ratio of 0.30 occurs for elastic wave propagation along the periodicity direction, whereas for inplane propagation the system displays an effective medium behavior. The phononic properties are well captured by numerical simulations. The porosity in the silica layers presents a structural scaffold for the introduction of secondary active media for potential coupling between phonons and other excitations, such as photons and electrons.

  6. Detecting Friedel oscillations in ultracold Fermi gases

    Science.gov (United States)

    Riechers, Keno; Hueck, Klaus; Luick, Niclas; Lompe, Thomas; Moritz, Henning

    2017-09-01

    Investigating Friedel oscillations in ultracold gases would complement the studies performed on solid state samples with scanning-tunneling microscopes. In atomic quantum gases interactions and external potentials can be tuned freely and the inherently slower dynamics allow to access non-equilibrium dynamics following a potential or interaction quench. Here, we examine how Friedel oscillations can be observed in current ultracold gas experiments under realistic conditions. To this aim we numerically calculate the amplitude of the Friedel oscillations which are induced by a potential barrier in a 1D Fermi gas and compare it to the expected atomic and photonic shot noise in a density measurement. We find that to detect Friedel oscillations the signal from several thousand one-dimensional systems has to be averaged. However, as up to 100 parallel one-dimensional systems can be prepared in a single run with present experiments, averaging over about 100 images is sufficient.

  7. Specificities of one-dimensional dissipative magnetohydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Popov, P. V., E-mail: popov.pv@mipt.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    One-dimensional dynamics of a plane slab of cold (β ≪ 1) isothermal plasma accelerated by a magnetic field is studied in terms of the MHD equations with a finite constant conductivity. The passage to the limit β → 0 is analyzed in detail. It is shown that, at β = 0, the character of the solution depends substantially on the boundary condition for the electric field at the inner plasma boundary. The relationship between the boundary condition for the pressure at β > 0 and the conditions for the electric field at β = 0 is found. The stability of the solution against one-dimensional longitudinal perturbations is analyzed. It is shown that, in the limit β → 0, the stationary solution is unstable if the time during which the acoustic wave propagates across the slab is longer than the time of magnetic field diffusion. The growth rate and threshold of instability are determined, and results of numerical simulation of its nonlinear stage are presented.

  8. Magnetic-Field Dependence of Raman Coupling Strength in Ultracold "4"0K Atomic Fermi Gas

    International Nuclear Information System (INIS)

    Huang Liang-Hui; Wang Peng-Jun; Meng Zeng-Ming; Peng Peng; Chen Liang-Chao; Li Dong-Hao; Zhang Jing

    2016-01-01

    We experimentally demonstrate the relation of Raman coupling strength with the external bias magnetic field in degenerate Fermi gas of "4"0K atoms. Two Raman lasers couple two Zeeman energy levels, whose energy splitting depends on the external bias magnetic field. The Raman coupling strength is determined by measuring the Rabi oscillation frequency. The characteristics of the Rabi oscillation is to be damped after several periods due to Fermi atoms in different momentum states oscillating with different Rabi frequencies. The experimental results show that the Raman coupling strength will decrease as the external bias magnetic field increases, which is in good agreement with the theoretical prediction. (paper)

  9. Exact pairing correlations in one-dimensional trapped fermions with stochastic mean-field wave-functions

    Energy Technology Data Exchange (ETDEWEB)

    Juillet, O.; Gulminelli, F. [Caen Univ., Lab. de Physique Corpusculaire (LPC/ENSICAEN), 14 (France); Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)

    2003-11-01

    The canonical thermodynamic properties of a one-dimensional system of interacting spin-1/2 fermions with an attractive zero-range pseudo-potential are investigated within an exact approach. The density operator is evaluated as the statistical average of dyadics formed from a stochastic mean-field propagation of independent Slater determinants. For an harmonically trapped Fermi gas and for fermions confined in a 1D-like torus, we observe the transition to a quasi-BCS state with Cooper-like momentum correlations and an algebraic long-range order. For few trapped fermions in a rotating torus, a dominant superfluid component with quantized circulation can be isolated. (author)

  10. One-dimensional nanomaterials for energy storage

    Science.gov (United States)

    Chen, Cheng; Fan, Yuqi; Gu, Jianhang; Wu, Liming; Passerini, Stefano; Mai, Liqiang

    2018-03-01

    The search for higher energy density, safer, and longer cycling-life energy storage systems is progressing quickly. One-dimensional (1D) nanomaterials have a large length-to-diameter ratio, resulting in their unique electrical, mechanical, magnetic and chemical properties, and have wide applications as electrode materials in different systems. This article reviews the latest hot topics in applying 1D nanomaterials, covering both their synthesis and their applications. 1D nanomaterials can be grouped into the categories: carbon, silicon, metal oxides, and conducting polymers, and we structure our discussion accordingly. Then, we survey the unique properties and application of 1D nanomaterials in batteries and supercapacitors, and provide comments on the progress and advantages of those systems, paving the way for a better understanding of employing 1D nanomaterials for energy storage.

  11. One-Dimensional Modelling of Internal Ballistics

    Science.gov (United States)

    Monreal-González, G.; Otón-Martínez, R. A.; Velasco, F. J. S.; García-Cascáles, J. R.; Ramírez-Fernández, F. J.

    2017-10-01

    A one-dimensional model is introduced in this paper for problems of internal ballistics involving solid propellant combustion. First, the work presents the physical approach and equations adopted. Closure relationships accounting for the physical phenomena taking place during combustion (interfacial friction, interfacial heat transfer, combustion) are deeply discussed. Secondly, the numerical method proposed is presented. Finally, numerical results provided by this code (UXGun) are compared with results of experimental tests and with the outcome from a well-known zero-dimensional code. The model provides successful results in firing tests of artillery guns, predicting with good accuracy the maximum pressure in the chamber and muzzle velocity what highlights its capabilities as prediction/design tool for internal ballistics.

  12. Stability model for one-dimensional FRCs

    International Nuclear Information System (INIS)

    Schwarzmeier, J.L.; Hewitt, T.G.; Lewis, H.R.; Seyler, C.E.; Symon, K.R.

    1982-01-01

    The subject of transport near the separatrix in FRC devices is important for determining the performance to be expected from an FRC reactor or from FRC experiments. A computer code was constructed for studying the micro-stability properties of FRCs near the separatrix as a first step in obtaining quasilinear transport coefficients that can be used in a transport code. We consider collisionless ions and electrons, without an expansion in powers of a parameter, like the electron or ion gyroradius, and we approximate the equilibrium with an infinitely long axially and translationally symmetric equilibrium. Thus, in our equilibria, there are only an axial magnetic field and a radial electric field. Our equilibria are collisionless, two-species, diffuse-profile, one-dimensional, theta-pinch equilibria. We allow the possibility that there be a magnetic field null in order to be able to model FRC devices more realistically

  13. One dimensional systems with singular perturbations

    International Nuclear Information System (INIS)

    Alvarez, J J; Gadella, M; Nieto, L M; Glasser, L M; Lara, L P

    2011-01-01

    This paper discusses some one dimensional quantum models with singular perturbations. Eventually, a mass discontinuity is added at the points that support the singular perturbations. The simplest model includes an attractive singular potential with a mass jump both located at the origin. We study the form of the only bound state. Another model exhibits a hard core at the origin plus one or more repulsive deltas with mass jumps at the points supporting these deltas. We study the location and the multiplicity of these resonances for the case of one or two deltas and settle the basis for a generalization. Finally, we consider the harmonic oscillator and the infinite square well plus a singular potential at the origin. We see how the energy of bound states is affected by the singular perturbation.

  14. Cohesive motion in one-dimensional flocking

    International Nuclear Information System (INIS)

    Dossetti, V

    2012-01-01

    A one-dimensional rule-based model for flocking, which combines velocity alignment and long-range centering interactions, is presented and studied. The induced cohesion in the collective motion of the self-propelled agents leads to unique group behavior that contrasts with previous studies. Our results show that the largest cluster of particles, in the condensed states, develops a mean velocity slower than the preferred one in the absence of noise. For strong noise, the system also develops a non-vanishing mean velocity, alternating its direction of motion stochastically. This allows us to address the directional switching phenomenon. The effects of different sources of stochasticity on the system are also discussed. (paper)

  15. Quasi-exact solvability of the one-dimensional Holstein model

    International Nuclear Information System (INIS)

    Pan Feng; Dai Lianrong; Draayer, J P

    2006-01-01

    The one-dimensional Holstein model of spinless fermions interacting with dispersionless phonons is solved by using a Bethe ansatz in analogue to that for the one-dimensional spinless Fermi-Hubbard model. Excitation energies and the corresponding wavefunctions of the model are determined by a set of partial differential equations. It is shown that the model is, at least, quasi-exactly solvable for the two-site case, when the phonon frequency, the electron-phonon coupling strength and the hopping integral satisfy certain relations. As examples, some quasi-exact solutions of the model for the two-site case are derived. (letter to the editor)

  16. Few quantum particles on one dimensional lattices

    International Nuclear Information System (INIS)

    Valiente Cifuentes, Manuel

    2010-01-01

    There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The lattice spacing is fixed by the wavelength of the laser field employed and the angle betwen the pair of laser beams; the lattice depth, defining the magnitude of the different band gaps, is tunable within a large interval of values. This flexibility permits the exploration of different regimes, ranging from the ''free-electron'' picture, modified by the effective mass for shallow optical lattices, to the tight-binding regime of a very deep periodic potential. In the latter case, effective single-band theories, widely used in condensed matter physics, can be implemented with unprecedent accuracy. The tunability of the lattice depth is nowadays complemented by the use of magnetic Feshbach resonances which, at very low temperatures, can vary the relevant atom-atom scattering properties at will. Moreover, optical lattices loaded with gases of effectively reduced dimensionality are experimentally accessible. This is especially important for one spatial dimension, since most of the exactly solvable models in many-body quantum mechanics deal with particles on a line; therefore, experiments with one-dimensional gases serve as a testing ground for many old and new theories which were regarded as purely academic not so long ago. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed. These are used to obtain, in closed form, the two-particle solutions of both the Hubbard and extended Hubbard models

  17. Few quantum particles on one dimensional lattices

    Energy Technology Data Exchange (ETDEWEB)

    Valiente Cifuentes, Manuel

    2010-06-18

    There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The lattice spacing is fixed by the wavelength of the laser field employed and the angle betwen the pair of laser beams; the lattice depth, defining the magnitude of the different band gaps, is tunable within a large interval of values. This flexibility permits the exploration of different regimes, ranging from the ''free-electron'' picture, modified by the effective mass for shallow optical lattices, to the tight-binding regime of a very deep periodic potential. In the latter case, effective single-band theories, widely used in condensed matter physics, can be implemented with unprecedent accuracy. The tunability of the lattice depth is nowadays complemented by the use of magnetic Feshbach resonances which, at very low temperatures, can vary the relevant atom-atom scattering properties at will. Moreover, optical lattices loaded with gases of effectively reduced dimensionality are experimentally accessible. This is especially important for one spatial dimension, since most of the exactly solvable models in many-body quantum mechanics deal with particles on a line; therefore, experiments with one-dimensional gases serve as a testing ground for many old and new theories which were regarded as purely academic not so long ago. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed. These are used to obtain, in closed form, the two-particle solutions of both the Hubbard and

  18. Neutron and photon (light) scattering on solitons in the quasi-one-dimensional magnetics

    CERN Document Server

    Abdulloev, K O

    1999-01-01

    The general expression we have found earlier for the dynamics form-factor is used to analyse experiments on the neutron and photon (light) scattering by the gas of solitons in quasi-one-dimensional magnetics (Authors)

  19. One dimensional benchmark calculations using diffusion theory

    International Nuclear Information System (INIS)

    Ustun, G.; Turgut, M.H.

    1986-01-01

    This is a comparative study by using different one dimensional diffusion codes which are available at our Nuclear Engineering Department. Some modifications have been made in the used codes to fit the problems. One of the codes, DIFFUSE, solves the neutron diffusion equation in slab, cylindrical and spherical geometries by using 'Forward elimination- Backward substitution' technique. DIFFUSE code calculates criticality, critical dimensions and critical material concentrations and adjoint fluxes as well. It is used for the space and energy dependent neutron flux distribution. The whole scattering matrix can be used if desired. Normalisation of the relative flux distributions to the reactor power, plotting of the flux distributions and leakage terms for the other two dimensions have been added. Some modifications also have been made for the code output. Two Benchmark problems have been calculated with the modified version and the results are compared with BBD code which is available at our department and uses same techniques of calculation. Agreements are quite good in results such as k-eff and the flux distributions for the two cases studies. (author)

  20. One-dimensional model of inertial pumping

    Science.gov (United States)

    Kornilovitch, Pavel E.; Govyadinov, Alexander N.; Markel, David P.; Torniainen, Erik D.

    2013-02-01

    A one-dimensional model of inertial pumping is introduced and solved. The pump is driven by a high-pressure vapor bubble generated by a microheater positioned asymmetrically in a microchannel. The bubble is approximated as a short-term impulse delivered to the two fluidic columns inside the channel. Fluid dynamics is described by a Newton-like equation with a variable mass, but without the mass derivative term. Because of smaller inertia, the short column refills the channel faster and accumulates a larger mechanical momentum. After bubble collapse the total fluid momentum is nonzero, resulting in a net flow. Two different versions of the model are analyzed in detail, analytically and numerically. In the symmetrical model, the pressure at the channel-reservoir connection plane is assumed constant, whereas in the asymmetrical model it is reduced by a Bernoulli term. For low and intermediate vapor bubble pressures, both models predict the existence of an optimal microheater location. The predicted net flow in the asymmetrical model is smaller by a factor of about 2. For unphysically large vapor pressures, the asymmetrical model predicts saturation of the effect, while in the symmetrical model net flow increases indefinitely. Pumping is reduced by nonzero viscosity, but to a different degree depending on the microheater location.

  1. Diffusiophoresis in one-dimensional solute gradients

    Energy Technology Data Exchange (ETDEWEB)

    Ault, Jesse T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Warren, Patrick B. [Unilever R& D Port Sunlight, Bebington (United Kingdom); Shin, Sangwoo [Univ. of Hawaii at Manoa, Honolulu, HI (United States); Stone, Howard A. [Princeton Univ., Princeton, NJ (United States)

    2017-11-06

    Here, the diffusiophoretic motion of suspended colloidal particles under one-dimensional solute gradients is solved using numerical and analytical techniques. Similarity solutions are developed for the injection and withdrawal dynamics of particles into semi-infinite pores. Furthermore, a method of characteristics formulation of the diffusion-free particle transport model is presented and integrated to realize particle trajectories. Analytical solutions are presented for the limit of small particle diffusiophoretic mobility Γp relative to the solute diffusivity Ds for particle motions in both semi-infinite and finite domains. Results confirm the build up of local maxima and minima in the propagating particle front dynamics. The method of characteristics is shown to successfully predict particle motions and the position of the particle front, although it fails to accurately predict suspended particle concentrations in the vicinity of sharp gradients, such as at the particle front peak seen in some injection cases, where particle diffusion inevitably plays an important role. Results inform the design of applications in which the use of applied solute gradients can greatly enhance particle injection into and withdrawal from pores.

  2. Diffusiophoresis in one-dimensional solute gradients

    International Nuclear Information System (INIS)

    Ault, Jesse T.; Warren, Patrick B.; Shin, Sangwoo; Stone, Howard A.

    2017-01-01

    Here, the diffusiophoretic motion of suspended colloidal particles under one-dimensional solute gradients is solved using numerical and analytical techniques. Similarity solutions are developed for the injection and withdrawal dynamics of particles into semi-infinite pores. Furthermore, a method of characteristics formulation of the diffusion-free particle transport model is presented and integrated to realize particle trajectories. Analytical solutions are presented for the limit of small particle diffusiophoretic mobility Γ p relative to the solute diffusivity D s for particle motions in both semi-infinite and finite domains. Results confirm the build up of local maxima and minima in the propagating particle front dynamics. The method of characteristics is shown to successfully predict particle motions and the position of the particle front, although it fails to accurately predict suspended particle concentrations in the vicinity of sharp gradients, such as at the particle front peak seen in some injection cases, where particle diffusion inevitably plays an important role. Results inform the design of applications in which the use of applied solute gradients can greatly enhance particle injection into and withdrawal from pores.

  3. Searching for perfect fluids: quantum viscosity in a universal Fermi gas

    International Nuclear Information System (INIS)

    Cao, C; Elliott, E; Wu, H; Thomas, J E

    2011-01-01

    We measure the shear viscosity in a two-component Fermi gas of atoms, tuned to a broad s-wave collisional (Feshbach) resonance. At resonance, the atoms strongly interact and exhibit universal behavior, where the equilibrium thermodynamic properties and transport coefficients are universal functions of density n and temperature T. We present a new calibration of the temperature as a function of global energy, which is directly measured from the cloud profiles. Using the calibration, the trap-averaged shear viscosity in units of ℎn is determined as a function of the reduced temperature at the trap center, from nearly the ground state to the unitary two-body regime. Low-temperature data are obtained from the damping rate of the radial breathing mode, whereas high-temperature data are obtained from hydrodynamic expansion measurements. We also show that the best fit to the high-temperature expansion data is obtained for a vanishing bulk viscosity. The measured trap-averaged entropy per particle and shear viscosity are used to estimate the ratio of shear viscosity to entropy density, which is compared with that conjectured for a perfect fluid.

  4. Comparative accuracy of thermodynamic description of properties of a gas plasma in the Thomas--Fermi and Saha approximations

    International Nuclear Information System (INIS)

    Iosilevskii, I.L.; Gryaznov, V.K.

    1982-01-01

    The relation between two methods of thermodynamical calculation of matter in the gas-plasma region is analyzed. These methods are the traditional one, which uses the Saha ionization equilibrium equation, and extrapolation of the Thomas--Fermi approximation with quantum and exchange corrections. These approximations are compared with one another, and also with the results of exact theory at the total ionization limit and with experimental data for a cesium plasma in the partial-ionization region

  5. Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization

    Science.gov (United States)

    Pu, Shi; Roy, Victor; Rezzolla, Luciano; Rischke, Dirk H.

    2016-04-01

    We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a nonzero magnetization. First, we assume a constant magnetic susceptibility χm and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with χm>0 ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with χmlaw ˜τ-a, two distinct solutions can be found depending on the values of a and χm. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the nonvanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. It is only for magnetic fields about an order of magnitude larger than expected for heavy-ion collisions that the system is substantially reheated and the lifetime of the quark phase might be extended.

  6. Greenberger-Horne-Zeilinger and W entanglement witnesses for the noninteracting Fermi gas

    International Nuclear Information System (INIS)

    Habibian, Hessam; Clark, John W.; Behbood, Naeimeh; Hingerl, Kurt

    2010-01-01

    The existence and nature of tripartite entanglement of a noninteracting Fermi gas (NIFG) is investigated. Three classes of parametrized entanglement witnesses (EWs) are introduced with the aim of detecting genuine tripartite entanglement in the three-body reduced density matrix and discriminating between the presence of the two types of genuine tripartite entanglement, W/B and GHZ/W (the convex set of B states is comprised of mixed states of product and biseparable states; that of W states is comprised of mixed states of B states and W-type pure entangled states; and the GHZ (Greenberger-Horne-Zeilinger) set contains generic mixtures of any kind for a tripartite system). By choosing appropriate EW operators, the problem of finding GHZ and W EWs is reduced to linear programming. Specifically, we devise W EWs based on a spin-chain model with periodic boundary conditions, and we construct a class of parametrized GHZ EWs by linearly combining projection operators corresponding to all the different state-vector types arising for a three-fermion system. A third class of EWs is provided by a GHZ stabilizer operator capable of distinguishing W/B from GHZ/B entanglement, which is not possible with W EWs. Implementing these classes of EWs, it is found that all states containing genuine tripartite entanglement are of W type, and hence states containing GHZ/W genuine tripartite entanglement do not arise. Some genuine tripartite entangled states that have a positive partial transpose (PPT) with respect to some bipartition are detected. Finally, it is demonstrated that a NIFG does not exhibit 'pure'W/B genuine tripartite entanglement: three-party entanglement without any separable or biseparable admixture does not occur.

  7. Dynamics of trapped two-component Fermi gas: Temperature dependence of the transition from collisionless to collisional regime

    International Nuclear Information System (INIS)

    Toschi, F.; Vignolo, P.; Tosi, M.P.; Succi, S.

    2003-01-01

    We develop a numerical method to study the dynamics of a two-component atomic Fermi gas trapped inside a harmonic potential at temperature T well below the Fermi temperature T F . We examine the transition from the collisionless to the collisional regime down to T=0.2 T F and find a good qualitative agreement with the experiments of B. DeMarco and D.S. Jin [Phys. Rev. Lett. 88, 040405 (2002)]. We demonstrate a twofold role of temperature on the collision rate and on the efficiency of collisions. In particular, we observe a hitherto unreported effect, namely, the transition to hydrodynamic behavior is shifted towards lower collision rates as temperature decreases

  8. Probing the exchange statistics of one-dimensional anyon models

    Science.gov (United States)

    Greschner, Sebastian; Cardarelli, Lorenzo; Santos, Luis

    2018-05-01

    We propose feasible scenarios for revealing the modified exchange statistics in one-dimensional anyon models in optical lattices based on an extension of the multicolor lattice-depth modulation scheme introduced in [Phys. Rev. A 94, 023615 (2016), 10.1103/PhysRevA.94.023615]. We show that the fast modulation of a two-component fermionic lattice gas in the presence a magnetic field gradient, in combination with additional resonant microwave fields, allows for the quantum simulation of hardcore anyon models with periodic boundary conditions. Such a semisynthetic ring setup allows for realizing an interferometric arrangement sensitive to the anyonic statistics. Moreover, we show as well that simple expansion experiments may reveal the formation of anomalously bound pairs resulting from the anyonic exchange.

  9. Capillary condensation in one-dimensional irregular confinement.

    Science.gov (United States)

    Handford, Thomas P; Pérez-Reche, Francisco J; Taraskin, Sergei N

    2013-07-01

    A lattice-gas model with heterogeneity is developed for the description of fluid condensation in finite sized one-dimensional pores of arbitrary shape. Mapping to the random-field Ising model allows an exact solution of the model to be obtained at zero-temperature, reproducing the experimentally observed dependence of the amount of fluid adsorbed in the pore on external pressure. It is demonstrated that the disorder controls the sorption for long pores and can result in H2-type hysteresis. Finite-temperature Metropolis dynamics simulations support analytical findings in the limit of low temperatures. The proposed framework is viewed as a fundamental building block of the theory of capillary condensation necessary for reliable structural analysis of complex porous media from adsorption-desorption data.

  10. MARCUSE’S ONE-DIMENSIONAL SOCIETY IN ONE-DIMENSIONAL MAN

    Directory of Open Access Journals (Sweden)

    MILOS RASTOVIC

    2013-05-01

    Full Text Available Nowadays, Marcuse’s main book One-Dimensional Man is almost obsolete, or rather passé. However, there are reasons to renew the reading of his book because of “the crisis of capitalism,” and the prevailing framework of technological domination in “advanced industrial society” in which we live today. “The new forms of control” in “advanced industrial societies” have replaced traditional methods of political and economic administration. The dominant structural element of “advanced industrial society” has become a technical and scientific apparatus of production and distribution of technology and administrative practice based on application of impersonal rules by a hierarchy of associating authorities. Technology has been liberated from the control of particular interests, and it has become the factor of domination in itself. Technological domination stems from the technical development of the productive apparatus that reproduces its ability into all spheres of social life (cultural, political, and economic. Based upon this consideration, in this paper, I will examine Marcuse’s ideas of “the new forms of control,” which creates a one–dimensional society. Marcuse’s fundamental thesis in One-Dimensional Man is that technological rationality is the most dominant factor in an “advanced industrial society,” which unites two earlier opposing forces of dissent: the bourgeoisie and the proletariat.

  11. Qualities of Wigner function and its applications to one-dimensional infinite potential and one-dimensional harmonic oscillator

    International Nuclear Information System (INIS)

    Xu Hao; Shi Tianjun

    2011-01-01

    In this article,the qualities of Wigner function and the corresponding stationary perturbation theory are introduced and applied to one-dimensional infinite potential well and one-dimensional harmonic oscillator, and then the particular Wigner function of one-dimensional infinite potential well is specified and a special constriction effect in its pure state Wigner function is discovered, to which,simultaneously, a detailed and reasonable explanation is elaborated from the perspective of uncertainty principle. Ultimately, the amendment of Wigner function and energy of one-dimensional infinite potential well and one-dimensional harmonic oscillator under perturbation are calculated according to stationary phase space perturbation theory. (authors)

  12. Universal relations of an ultracold Fermi gas with arbitrary spin-orbit coupling

    Science.gov (United States)

    Jie, Jianwen; Qi, Ran; Zhang, Peng

    2018-05-01

    We derive the universal relations for an ultracold two-component Fermi gas with a spin-orbit coupling (SOC) ∑α,β =x ,y ,zλα βσαpβ , where px ,y ,z and σx ,y ,z are the single-atom momentum and Pauli operators for pseudospin, respectively, and the SOC intensity λα β could take an arbitrary value. We consider the system with an s -wave short-range interspecies interaction, and ignore the SOC-induced modification for the value of the scattering length. Using the first-quantized approach developed by Tan [S. Tan, Phys. Rev. Lett. 107, 145302 (2011), 10.1103/PhysRevLett.107.145302], we obtain the short-range and high-momentum expansions for the one-body real-space correlation function and momentum distribution function, respectively. For our system these functions are a 2 ×2 matrix in the pseudospin basis. We find that the leading-order (1 /k4 ) behavior of the diagonal elements of the momentum distribution function, i.e., n↑↑(k ) and n↓↓(k ) , are not modified by the SOC. However, the SOC can significantly modify the large-k behaviors of the distribution difference δ n (k ) ≡n↑↑(k ) -n↓↓(k ) as well as the nondiagonal elements of the momentum distribution function, i.e., n↑↓(k ) and n↓↑(k ) . In the absence of the SOC, the leading order of δ n (k ) , n↑↓(k ) , and n↓↑(k ) is O (1 /k6) . When SOC appears, it can induce a term on the order of 1 /k5 for these elements. We further derive the adiabatic relation and the energy functional. Our results show that the SOC can induce an additional term in the energy functional, which describes the contribution from the SOC to the total energy. In addition, the form of the adiabatic relation for our system is not modified by the SOC. Our results are applicable for the systems with any type of single-atom trapping potential, which could be either diagonal or nondiagonal in the pseudospin basis.

  13. Non-equilibrium dynamics of one-dimensional Bose gases

    International Nuclear Information System (INIS)

    Langen, T.

    2013-01-01

    Understanding the non-equilibrium dynamics of isolated quantum many-body systems is an open problem on vastly different energy, length, and time scales. Examples range from the dynamics of the early universe and heavy-ion collisions to the subtle coherence and transport properties in condensed matter physics. However, realizations of such quantum many-body systems, which are both well isolated from the environment and accessible to experimental study are scarce. This thesis presents a series of experiments with ultracold one-dimensional Bose gases. These gases combine a nearly perfect isolation from the environment with many well-established methods to manipulate and probe their quantum states. This makes them an ideal model system to explore the physics of quantum many body systems out of equilibrium. In the experiments, a well-defined non-equilibrium state is created by splitting a single one-dimensional gas coherently into two parts. The relaxation of this state is probed using matter-wave interferometry. The Observations reveal the emergence of a prethermalized steady state which differs strongly from thermal equilibrium. Such thermal-like states had previously been predicted for a large variety of systems, but never been observed directly. Studying the relaxation process in further detail shows that the thermal correlations of the prethermalized state emerge locally in their final form and propagate through the system in a light-cone-like evolution. This provides first experimental evidence for the local relaxation conjecture, which links relaxation processes in quantum many-body systems to the propagation of correlations. Furthermore, engineering the initial state of the evolution demonstrates that the prethermalized state is described by a generalized Gibbs ensemble, an observation which substantiates the importance of this ensemble as an extension of standard statistical mechanics. Finally, an experiment is presented, where pairs of gases with an atom

  14. Quantum Monte Carlo calculation of the Fermi-liquid parameters in the two-dimensional electron gas

    International Nuclear Information System (INIS)

    Kwon, Y.; Ceperley, D.M.; Martin, R.M.

    1994-01-01

    Excitations of the two-dimensional electron gas, including many-body effects, are calculated with a variational Monte Carlo method. Correlated sampling is introduced to calculate small energy differences between different excitations. The usual pair-product (Slater-Jastrow) trial wave function is found to lack certain correlations entirely so that backflow correlation is crucial. From the excitation energies calculated here, we determine Fermi-liquid parameters and related physical quantities such as the effective mass and the Lande g factor of the system. Our results for the effective mass are compared with previous analytic calculations

  15. Decay of Polarons and Molecules in a Strongly Polarized Fermi Gas

    DEFF Research Database (Denmark)

    Bruun, Georg; Massignan, P.

    2010-01-01

    , and that it vanishes much faster than the energy difference between the two states, thereby confirming the first order nature of the polaron-molecule transition. In the regime where each state is metastable, we find quasiparticle lifetimes which are much longer than what is expected for a usual Fermi liquid. Our...

  16. Quantum Impurity in a One-dimensional Trapped Bose Gas

    DEFF Research Database (Denmark)

    Salami Dehkharghani, Amin; Volosniev, A. G.; Zinner, N. T.

    2015-01-01

    We present a new theoretical framework for describing an impurity in a trapped Bose system in one spatial dimension. The theory handles any external confinement, arbitrary mass ratios, and a weak interaction may be included between the Bose particles. To demonstrate our technique, we calculate th...... the ground state energy and properties of a sample system with eight bosons and find an excellent agreement with numerically exact results. Our theory can thus provide definite predictions for experiments in cold atomic gases....

  17. Large-scale behaviour of local and entanglement entropy of the free Fermi gas at any temperature

    Science.gov (United States)

    Leschke, Hajo; Sobolev, Alexander V.; Spitzer, Wolfgang

    2016-07-01

    The leading asymptotic large-scale behaviour of the spatially bipartite entanglement entropy (EE) of the free Fermi gas infinitely extended in multidimensional Euclidean space at zero absolute temperature, T = 0, is by now well understood. Here, we present and discuss the first rigorous results for the corresponding EE of thermal equilibrium states at T> 0. The leading large-scale term of this thermal EE turns out to be twice the first-order finite-size correction to the infinite-volume thermal entropy (density). Not surprisingly, this correction is just the thermal entropy on the interface of the bipartition. However, it is given by a rather complicated integral derived from a semiclassical trace formula for a certain operator on the underlying one-particle Hilbert space. But in the zero-temperature limit T\\downarrow 0, the leading large-scale term of the thermal EE considerably simplifies and displays a {ln}(1/T)-singularity which one may identify with the known logarithmic enhancement at T = 0 of the so-called area-law scaling. birthday of the ideal Fermi gas.

  18. Wideband absorption in one dimensional photonic crystal with graphene-based hyperbolic metamaterials

    Science.gov (United States)

    Kang, Yongqiang; Liu, Hongmei

    2018-02-01

    A broadband absorber which was proposed by one dimensional photonic crystal (1DPC) containing graphene-based hyperbolic metamaterials (GHMM) is theoretically investigated. For TM mode, it was demonstrated to absorb roughly 90% of all available electromagnetic waves at a 14 THz absorption bandwidth at normal incidence. The absorption bandwidth was affected by Fermi energy and thickness of dielectric layer. When the incident angle was increased, the absorption value decreased, and the absorption band had a gradual blue shift. These findings have potential applications for designing broadband optoelectronic devices at mid-infrared and THz frequency range.

  19. Study of one dimensional magnetic system via field theory

    International Nuclear Information System (INIS)

    Talim, S.L.

    1988-04-01

    We present a study of one-dimensional magnetic system using field theory methods. We studied the discreteness effects in a classical anisotropic one dimensional antiferromagnet in an external magnetic field. It is shown that for TMMC, at the temperatures and magnetic fields where most experiments have been done, the corrections are small and can be neglected. (author)

  20. Defects in quasi-one dimensional oxide conductors: K0.3MoO3

    International Nuclear Information System (INIS)

    Smith, K.E.; Breuer, K.; Goldberg, D.; Greenblatt, M.; McCarroll, W.; Hulbert, S.L.

    1995-01-01

    The electronic structure of the prototypical quasi-one dimensional (ID) conductor K 0.3 MoO 3 has been studied using high resolution photoemission spectroscopy. In particular, the electronic structure of defects was investigated in order to understand the mechanism for charge density wave pinning and destruction of the Peierls transition. Defects were found to radically alter the electronic structure close to the Fermi level (E F ), thus strongly modifying the structure of the Fermi surface. While a low emission intensity at E F has been interpreted as evidence for a Luttinger liquid ground state in a 1D metal, the authors show that non-stoichiometric surfaces lead to similar effects. The nature of the ground state is discussed in the context of these results

  1. Effect of population imbalance on the Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas

    International Nuclear Information System (INIS)

    Tempere, J.; Klimin, S. N.; Devreese, J. T.

    2009-01-01

    The Berezinskii-Kosterlitz-Thouless (BKT) mechanism describes the breakdown of superfluidity in a two-dimensional Bose gas or a two-dimensional gas of paired fermions. In the latter case, a population imbalance between the two pairing partners in the Fermi mixture is known to influence pairing characteristics. Here, we investigate the effects of imbalance on the two-dimensional BKT superfluid transition and show that superfluidity is even more sensitive to imbalance than for three-dimensional systems. Finite-temperature phase diagrams are derived using the functional integral formalism in combination with a hydrodynamic action functional for the phase fluctuations. This allows to identify a phase-separation region and tricritical points due to imbalance. In contrast to superfluidity in the three-dimensional case, the effect of imbalance is also pronounced in the strong-coupling regime.

  2. Energy Current Cumulants in One-Dimensional Systems in Equilibrium

    Science.gov (United States)

    Dhar, Abhishek; Saito, Keiji; Roy, Anjan

    2018-06-01

    A recent theory based on fluctuating hydrodynamics predicts that one-dimensional interacting systems with particle, momentum, and energy conservation exhibit anomalous transport that falls into two main universality classes. The classification is based on behavior of equilibrium dynamical correlations of the conserved quantities. One class is characterized by sound modes with Kardar-Parisi-Zhang scaling, while the second class has diffusive sound modes. The heat mode follows Lévy statistics, with different exponents for the two classes. Here we consider heat current fluctuations in two specific systems, which are expected to be in the above two universality classes, namely, a hard particle gas with Hamiltonian dynamics and a harmonic chain with momentum conserving stochastic dynamics. Numerical simulations show completely different system-size dependence of current cumulants in these two systems. We explain this numerical observation using a phenomenological model of Lévy walkers with inputs from fluctuating hydrodynamics. This consistently explains the system-size dependence of heat current fluctuations. For the latter system, we derive the cumulant-generating function from a more microscopic theory, which also gives the same system-size dependence of cumulants.

  3. RETRAN-02 one-dimensional kinetics model: a review

    International Nuclear Information System (INIS)

    Gose, G.C.; McClure, J.A.

    1986-01-01

    RETRAN-02 is a modular code system that has been designed for one-dimensional, transient thermal-hydraulics analysis. In RETRAN-02, core power behavior may be treated using a one-dimensional reactor kinetics model. This model allows the user to investigate the interaction of time- and space-dependent effects in the reactor core on overall system behavior for specific LWR operational transients. The purpose of this paper is to review the recent analysis and development activities related to the one dimensional kinetics model in RETRAN-02

  4. Plasma properties of quasi-one-dimensional ring

    CERN Document Server

    Shmelev, G M

    2001-01-01

    The plasma properties of the quasi-one-dimensional ring in the threshold cases of low and high frequencies, corresponding to the plasma oscillations and dielectric relaxation are studied within the frames of the classical approach. The plasma oscillations spectrum and the electron dielectric relaxation frequency in the quasi-one-dimensional ring are calculated. The plasmons spectrum equidistance is identified. It is shown , that in contrast to the three-dimensional case there takes place the dielectric relaxation dispersion, wherefrom there follows the possibility of studying the carriers distribution in the quasi-one-dimensional rings through the method of the dielectric relaxation spectroscopy

  5. Observation of Zero-Dimensional States in a One-Dimensional Electron Interferometer

    NARCIS (Netherlands)

    Wees, B.J. van; Kouwenhoven, L.P.; Harmans, C.J.P.M.; Williamson, J.G.; Timmering, C.E.; Broekaart, M.E.I.; Foxon, C.T.; Harris, J.J.

    1989-01-01

    We have studied the electron transport in a one-dimensional electron interferometer. It consists of a disk-shaped two-dimensional electron gas, to which quantum point contacts are attached. Discrete zero-dimensional states are formed due to constructive interference of electron waves traveling along

  6. One-dimensional simulation of a stirling three-stage pulse-tube refrigerator

    NARCIS (Netherlands)

    Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2009-01-01

    A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

  7. One-dimensional simulation of a Stirling three-stage pulse-tube refrigerator

    NARCIS (Netherlands)

    Etaati, M.A.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.

    2009-01-01

    A one-dimensional mathematical model is derived for a three-stage pulse-tube refrigerator (PTR) that is based on the conservation laws and the ideal gas law. The three-stage PTR is regarded as three separate single-stage PTRs that are coupled via proper junction conditions. At the junctions there

  8. Path-Integral Monte Carlo Determination of the Fourth-Order Virial Coefficient for a Unitary Two-Component Fermi Gas with Zero-Range Interactions.

    Science.gov (United States)

    Yan, Yangqian; Blume, D

    2016-06-10

    The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b_{4} of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b_{4}, our b_{4} agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.

  9. Explicit Solutions for One-Dimensional Mean-Field Games

    KAUST Repository

    Prazeres, Mariana

    2017-01-01

    In this thesis, we consider stationary one-dimensional mean-field games (MFGs) with or without congestion. Our aim is to understand the qualitative features of these games through the analysis of explicit solutions. We are particularly interested

  10. Negative differential resistance in a one-dimensional molecular wire ...

    Indian Academy of Sciences (India)

    voltage characteristics of a one-dimensional molecular wire with odd number of ... lem, although interesting both from a fundamental point of view and in terms of ..... SKP acknowledges the DST, Government of India, for financial support.

  11. The one-dimensional extended Bose–Hubbard model

    Indian Academy of Sciences (India)

    Unknown

    method to obtain the zero-temperature phase diagram of the one-dimensional, extended ... Progress in this field has been driven by an interplay between ... superconductor-insulator transition in thin films of superconducting materials like bis-.

  12. Analytical and numerical studies of Bose-Fermi mixtures in a one-dimensional harmonic trap

    DEFF Research Database (Denmark)

    Salami Dehkharghani, Amin; Bellotti, Filipe Furlan; Zinner, Nikolaj Thomas

    2017-01-01

    are confined externally by a harmonic oscillator one-body potential. For the case of four particles, two identical fermions and two identical bosons, we focus on the strongly interacting regime and analyze the system using both an analytical approach and density matrix renormalization group calculations using...... a discrete version of the underlying continuum Hamiltonian. This provides us with insight into both the ground state and the manifold of excited states that are almost degenerate for large interaction strength. Our results show great variation in the density profiles for bosons and fermions in different...

  13. One-dimensional reactor kinetics model for RETRAN

    International Nuclear Information System (INIS)

    Gose, G.C.; Peterson, C.E.; Ellis, N.L.; McClure, J.A.

    1981-01-01

    This paper describes a one-dimensional spatial neutron kinetics model that was developed for the RETRAN code. The RETRAN -01 code has a point kinetics model to describe the reactor core behavior during thermal-hydraulic transients. A one-dimensional neutronics model has been developed for RETRAN-02. The ability to account for flux shape changes will permit an improved representation of the thermal and hydraulic feedback effects for many operational transients. 19 refs

  14. One dimensional Bosons: From Condensed Matter Systems to Ultracold Gases

    OpenAIRE

    Cazalilla, M. A.; Citro, R.; Giamarchi, T.; Orignac, E.; Rigol, M.

    2011-01-01

    The physics of one-dimensional interacting bosonic systems is reviewed. Beginning with results from exactly solvable models and computational approaches, the concept of bosonic Tomonaga-Luttinger liquids relevant for one-dimensional Bose fluids is introduced, and compared with Bose-Einstein condensates existing in dimensions higher than one. The effects of various perturbations on the Tomonaga-Luttinger liquid state are discussed as well as extensions to multicomponent and out of equilibrium ...

  15. One dimensional models of excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Duclos, P.; Pedersen, Thomas Garm

    Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable.......Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable....

  16. Longitudinal and spin Hall conductance of a one-dimensional Aharonov-Bohm ring

    International Nuclear Information System (INIS)

    Moca, Catalin Pascu; Marinescu, D C

    2006-01-01

    The longitudinal and spin Hall conductances of an electron gas with Rashba-Dresselhaus spin-orbit interaction, confined to a quasi-one-dimensional Aharonov-Bohm ring, are studied as functions of disorder and magnetic flux. The system is mapped onto a one-dimensional virtual lattice and is described, in a tight binding approximation, by a Hamiltonian that depends parametrically on the nearest neighbour hopping integral t, the Rashba spin-orbit coupling V R , the Dresselhaus spin-orbit coupling V D and an Anderson-like, on-site disorder energy strength W. Numerical results are obtained within a spin dependent Landauer-Buettiker formalism

  17. GITTAM program for numerical simulation of one-dimensional targets TIS. Part 3

    International Nuclear Information System (INIS)

    Basko, M.M.; Sokolovskij, M.V.

    1989-01-01

    Results of testing calculations according to GITTAM program, developed for numeric simulation of one-dimensional thermonuclear targets of heavy-ion synthesis are presented. Finite-difference method for solving a system of one-dimensional hydrodynamics equations with heat conductivity, radiation diffusion and thermonuclear combustion is used in the GITTAM program. In the tests presented, based on simple automodel solutions, adiabatic motion as well as distribution of shock, thermal and radial waves in gas with simple polytron state equation is investigated. 3 refs.; 6 figs

  18. Ultracold atoms in one-dimensional optical lattices approaching the Tonks-Girardeau regime

    International Nuclear Information System (INIS)

    Pollet, L.; Rombouts, S.M.A.; Denteneer, P.J. H.

    2004-01-01

    Recent experiments on ultracold atomic alkali gases in a one-dimensional optical lattice have demonstrated the transition from a gas of soft-core bosons to a Tonks-Girardeau gas in the hard-core limit, where one-dimensional bosons behave like fermions in many respects. We have studied the underlying many-body physics through numerical simulations which accommodate both the soft-core and hard-core limits in one single framework. We find that the Tonks-Girardeau gas is reached only at the strongest optical lattice potentials. Results for slightly higher densities, where the gas develops a Mott-like phase already at weaker optical lattice potentials, show that these Mott-like short-range correlations do not enhance the convergence to the hard-core limit

  19. Universal Properties of a Trapped Two-Component Fermi Gas at Unitarity

    International Nuclear Information System (INIS)

    Blume, D.; Stecher, J. von; Greene, Chris H.

    2007-01-01

    We treat the trapped two-component Fermi system, in which unlike fermions interact through a two-body short-range potential having no bound state but an infinite scattering length. By accurately solving the Schroedinger equation for up to N=6 fermions, we show that no many-body bound states exist other than those bound by the trapping potential, and we demonstrate unique universal properties of the system: Certain excitation frequencies are separated by 2(ℎ/2π)ω, the wave functions agree with analytical predictions and a virial theorem is fulfilled. Further calculations up to N=30 determine the excitation gap, an experimentally accessible universal quantity, and it agrees with recent predictions based on a density functional approach

  20. Superfluidity of a dipolar Fermi gas in 2D optical lattices bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Guardian, A.; Paredes, R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico)

    2016-12-15

    Ultracold Fermi molecules lying in 2D square optical lattices bilayers with its dipole moment perpendicularly aligned to the layers, having interlayer finite range s-wave interactions, are shown to form superfluid phases, both, in the Bardeen, Cooper and Schrieffer (BCS) regime of Cooper pairs, and in the condensate regime of bound dimeric molecules. We demonstrate this result using a functional integral scheme within the Ginzburg-Landau theory. For the deep Berezinskii-Kosterlitz-Thouless (BKT) phase transition, we predict critical temperatures around 5 nK and 20 nK for {sup 23}Na{sup 40}K and OH molecules, which are within reach of current experiments [J. W. Park, S. Will and M. Zwierlein, Phys. Rev. Lett. 114, 205302 (2015)]. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: A two-fluid hydrodynamic description

    Science.gov (United States)

    Hu, Hui; Zou, Peng; Liu, Xia-Ji

    2018-02-01

    We provide a description of the dynamic structure factor of a homogeneous unitary Fermi gas at low momentum and low frequency, based on the dissipative two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is used to determine the regime where the hydrodynamic theory is applicable and to understand the nature of sound waves in the density response near the superfluid phase transition. By collecting the best knowledge on the shear viscosity and thermal conductivity known so far, we calculate the various diffusion coefficients and obtain the damping width of the (first and second) sounds. We find that the damping width of the first sound is greatly enhanced across the superfluid transition and very close to the transition the second sound might be resolved in the density response for the transferred momentum up to half of Fermi momentum. Our work is motivated by the recent measurement of the local dynamic structure factor at low momentum at Swinburne University of Technology and the ongoing experiment on sound attenuation of a homogeneous unitary Fermi gas at Massachusetts Institute of Technology. We discuss how the measurement of the velocity and damping width of the sound modes in low-momentum dynamic structure factor may lead to an improved determination of the universal superfluid density, shear viscosity, and thermal conductivity of a unitary Fermi gas.

  2. Observing the drop of resistance in the flow of a superfluid Fermi gas.

    Science.gov (United States)

    Stadler, David; Krinner, Sebastian; Meineke, Jakob; Brantut, Jean-Philippe; Esslinger, Tilman

    2012-11-29

    The ability of particles to flow with very low resistance is characteristic of superfluid and superconducting states, leading to their discovery in the past century. Although measuring the particle flow in liquid helium or superconducting materials is essential to identify superfluidity or superconductivity, no analogous measurement has been performed for superfluids based on ultracold Fermi gases. Here we report direct measurements of the conduction properties of strongly interacting fermions, observing the well-known drop in resistance that is associated with the onset of superfluidity. By varying the depth of the trapping potential in a narrow channel connecting two atomic reservoirs, we observed variations of the atomic current over several orders of magnitude. We related the intrinsic conduction properties to the thermodynamic functions in a model-independent way, by making use of high-resolution in situ imaging in combination with current measurements. Our results show that, as in solid-state systems, current and resistance measurements in quantum gases provide a sensitive probe with which to explore many-body physics. Our method is closely analogous to the operation of a solid-state field-effect transistor and could be applied as a probe for optical lattices and disordered systems, paving the way for modelling complex superconducting devices.

  3. Perron-Frobenius theorem on the superfluid transition of an ultracold Fermi gas

    Science.gov (United States)

    Sakumichi, Naoyuki; Kawakami, Norio; Ueda, Masahito

    2014-05-01

    The Perron-Frobenius theorem is applied to identify the superfluid transition of the BCS-BEC crossover based on a cluster expansion method of Lee and Yang. Here, the cluster expansion is a systematic expansion of the equation of state (EOS) in terms of the fugacity z = exp (βμ) as βpλ3 = 2 z +b2z2 +b3z3 + ⋯ , with inverse temperature β =(kB T) - 1 , chemical potential μ, pressure p, and thermal de Broglie length λ =(2 πℏβ / m) 1 / 2 . According to the method of Lee and Yang, EOS is expressed by the Lee-Yang graphs. A singularity of an infinite series of ladder-type Lee-Yang graphs is analyzed. We point out that the singularity is governed by the Perron-Frobenius eigenvalue of a certain primitive matrix which is defined in terms of the two-body cluster functions and the Fermi distribution functions. As a consequence, it is found that there exists a unique fugacity at the phase transition point, which implies that there is no fragmentation of Bose-Einstein condensates of dimers and Cooper pairs at the ladder-approximation level of Lee-Yang graphs. An application to a BEC of strongly bounded dimers is also made.

  4. A review on one dimensional perovskite nanocrystals for piezoelectric applications

    Directory of Open Access Journals (Sweden)

    Li-Qian Cheng

    2016-03-01

    Full Text Available In recent years, one-dimensional piezoelectric nanomaterials have become a research topic of interest because of their special morphology and excellent piezoelectric properties. This article presents a short review on one dimensional perovskite piezoelectric materials in different systems including Pb(Zr,TiO3, BaTiO3 and (K,NaNbO3 (KNN. We emphasize KNN as a promising lead-free piezoelectric compound with a high Curie temperature and high piezoelectric properties and describe its synthesis and characterization. In particular, details are presented for nanoscale piezoelectricity characterization of a single KNN nanocrystal by piezoresponse force microscopy. Finally, this review describes recent progress in applications based on one dimensional piezoelectric nanostructures with a focus on energy harvesting composite materials.

  5. Strong chaos in one-dimensional quantum system

    International Nuclear Information System (INIS)

    Yang, C.-D.; Wei, C.-H.

    2008-01-01

    According to the Poincare-Bendixson theorem, a minimum of three autonomous equations is required to exhibit deterministic chaos. Because a one-dimensional quantum system is described by only two autonomous equations using de Broglie-Bohm's trajectory interpretation, chaos in one-dimensional quantum systems has long been considered impossible. We will prove in this paper that chaos phenomenon does exist in one-dimensional quantum systems, if the domain of quantum motions is extended to complex space by noting that the quantum world is actually characterized by a four-dimensional complex spacetime according to the E (∞) theory. Furthermore, we point out that the interaction between the real and imaginary parts of complex trajectories produces a new chaos phenomenon unique to quantum systems, called strong chaos, which describes the situation that quantum trajectories may emerge and diverge spontaneously without any perturbation in the initial position

  6. Absorption in one-dimensional metallic-dielectric photonic crystals

    International Nuclear Information System (INIS)

    Yu Junfei; Shen Yifeng; Liu Xiaohan; Fu Rongtang; Zi Jian; Zhu Zhiqiang

    2004-01-01

    We show theoretically that the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced considerably over the corresponding constituent metal. By properly choosing the structural and material parameters, the absorption of one-dimensional metallic-dielectric photonic crystals can be enhanced by one order of magnitude in the visible and in the near infrared regions. It is found that the absorptance of such photonic crystals increases with increasing number of periods. Rules on how to obtain a absorption enhancement in a certain frequency range are discussed. (letter to the editor)

  7. One-dimensional models of excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia Decebal; Duclos, Pierre; Pedersen, Thomas Garm

    2004-01-01

    Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one-dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable.......Excitons in carbon nanotubes may be modeled by two oppositely charged particles living on the surface of a cylinder. We derive three one-dimensional effective Hamiltonians which become exact as the radius of the cylinder vanishes. Two of them are solvable....

  8. Analytical solutions of one-dimensional advection–diffusion

    Indian Academy of Sciences (India)

    Analytical solutions are obtained for one-dimensional advection –diffusion equation with variable coefficients in a longitudinal finite initially solute free domain,for two dispersion problems.In the first one,temporally dependent solute dispersion along uniform flow in homogeneous domain is studied.In the second problem the ...

  9. Underwater striling engine design with modified one-dimensional model

    Directory of Open Access Journals (Sweden)

    Daijin Li

    2015-05-01

    Full Text Available Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many researches on one-dimensional model is used to evaluate thermodynamic performance of Stirling engine, but in which there are still some aspects which cannot be modeled with proper mathematical models such as mechanical loss or auxiliary power. In this paper, a four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicles (UUVs is discussed. And a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is derived while referring to the Stirling engine computer model of National Aeronautics and Space Administration (NASA. The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of this one-dimensional model. It shows that the maximum error of output power of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9%. Finally, a Stirling engine for UUVs is designed with Schmidt analysis method and the modified one-dimensional model, and the results indicate this designed engine is capable of showing desired output power.

  10. Quantitative hyperbolicity estimates in one-dimensional dynamics

    International Nuclear Information System (INIS)

    Day, S; Kokubu, H; Pilarczyk, P; Luzzatto, S; Mischaikow, K; Oka, H

    2008-01-01

    We develop a rigorous computational method for estimating the Lyapunov exponents in uniformly expanding regions of the phase space for one-dimensional maps. Our method uses rigorous numerics and graph algorithms to provide results that are mathematically meaningful and can be achieved in an efficient way

  11. Quasi-one-dimensional scattering in a discrete model

    DEFF Research Database (Denmark)

    Valiente, Manuel; Mølmer, Klaus

    2011-01-01

    We study quasi-one-dimensional scattering of one and two particles with short-range interactions on a discrete lattice model in two dimensions. One of the directions is tightly confined by an arbitrary trapping potential. We obtain the collisional properties of these systems both at finite and zero...

  12. Structure Variation from One-Dimensional Chain to Three ...

    Indian Academy of Sciences (India)

    WEN-XUAN LI, XIAO-MIN GU, WEN-LI ZHANG and LIANG NI. School of Chemistry ... Compound 1 possesses one-dimensional chain structure, and expands into ..... sis of fine chemicals and pharmaceuticals.30 The results were summarized ...

  13. Current-Voltage Characteristics of Quasi-One-Dimensional Superconductors

    DEFF Research Database (Denmark)

    Vodolazov, D.Y.; Peeters, F.M.; Piraux, L.

    2003-01-01

    The current-voltage (I-V) characteristics of quasi-one-dimensional superconductors were discussed. The I-V characteristics exhibited an unusual S behavior. The dynamics of superconducting condensate and the existence of two different critical currents resulted in such an unusual behavior....

  14. Diffusive transport in a one dimensional disordered potential involving correlations

    International Nuclear Information System (INIS)

    Monthus, C.; Paris-6 Univ., 75

    1995-03-01

    Transport properties of one dimensional Brownian diffusion under the influence of a quenched random force, distributed as a two-level Poisson process is discussed. Large time scaling laws of the position of the Brownian particle, and the probability distribution of the stationary flux going through a sample between two prescribed concentrations are studied. (author) 14 refs.; 3 figs

  15. Appropriateness of one-dimensional calculations for repository analysis

    International Nuclear Information System (INIS)

    Eaton, R.R.

    1994-01-01

    This paper brings into focus the results of numerous studies that have addressed issues associated with the validity of assumptions which are used to justify reducing the dimensionality of numerical calculations of water flow through Yucca Mountain, NV. It is shown that in many cases, one-dimensional modeling is more rigorous than previously assumed

  16. One-dimensional position readout from microchannel plates

    International Nuclear Information System (INIS)

    Connell, K.A.; Przybylski, M.M.

    1982-01-01

    The development of a one-dimensional position readout system with microchannel plates, is described, for heavy ion detectors for use in a particle time-of-flight telescope and as a position sensitive device in front of an ionisation counter at the Nuclear Structure Facility. (U.K.)

  17. Lekhnitskii's formalism of one-dimensional quasicrystals and its ...

    Indian Academy of Sciences (India)

    To illustrate its utility, the generalized Lekhnitskii's formal- ism is used to analyse the coupled phonon and phason fields in an infinite quasicrystal medium con- taining an elliptic rigid inclusion. Keywords. Generalized Lekhnitskii's formalism; one-dimensional quasicrystals; plane problems; elliptic inclusion. PACS Nos 61.44.

  18. Simulation of the diffraction pattern of one dimensional quasicrystal ...

    African Journals Online (AJOL)

    The effects of the variation of atomic spacing ratio of a one dimensional quasicrystal material are investigated. The work involves the use of the solid state simulation code, Laue written by Silsbee and Drager. We are able to observe the general features of the diffraction pattern by a quasicrystal. In addition, it has been found ...

  19. Monte Carlo investigation of the one-dimensional Potts model

    International Nuclear Information System (INIS)

    Karma, A.S.; Nolan, M.J.

    1983-01-01

    Monte Carlo results are presented for a variety of one-dimensional dynamical q-state Potts models. Our calculations confirm the expected universal value z = 2 for the dynamic scaling exponent. Our results also indicate that an increase in q at fixed correlation length drives the dynamics into the scaling regime

  20. State reconstruction of one-dimensional wave packets

    Science.gov (United States)

    Krähmer, D. S.; Leonhardt, U.

    1997-12-01

    We review and analyze the method [U. Leonhardt, M.G. Raymer: Phys. Rev. Lett. 76, 1985 (1996)] for quantum-state reconstruction of one-dimensional non-relativistic wave packets from position observations. We illuminate the theoretical background of the technique and show how to extend the procedure to the continuous part of the spectrum.

  1. One-dimensional autonomous systems and dissipative systems

    International Nuclear Information System (INIS)

    Lopez, G.

    1996-01-01

    The Lagrangian and the Generalized Linear Momentum are given in terms of a constant of motion for a one-dimensional autonomous system. The possibility of having an explicit Hamiltonian expression is also analyzed. The approach is applied to some dissipative systems. Copyright copyright 1996 Academic Press, Inc

  2. Quantum transport in strongly interacting one-dimensional nanostructures

    NARCIS (Netherlands)

    Agundez, R.R.

    2015-01-01

    In this thesis we study quantum transport in several one-dimensional systems with strong electronic interactions. The first chapter contains an introduction to the concepts treated throughout this thesis, such as the Aharonov-Bohm effect, the Kondo effect, the Fano effect and quantum state transfer.

  3. Statistics of resonances in one-dimensional continuous systems

    Indian Academy of Sciences (India)

    Vol. 73, No. 3. — journal of. September 2009 physics pp. 565–572. Statistics of resonances in one-dimensional continuous systems. JOSHUA FEINBERG. Physics Department, University of Haifa at Oranim, Tivon 36006, Israel ..... relativistic quantum mechanics (Israel Program for Scientific Translations, Jerusalem,. 1969).

  4. Statistical mechanics of quantum one-dimensional damped harmonic oscillator

    International Nuclear Information System (INIS)

    Borges, E.N.M.; Borges, O.N.; Ribeiro, L.A.A.

    1985-01-01

    We calculate the thermal correlation functions of the one-dimensional damped harmonic oscillator in contact with a reservoir, in an exact form by applying Green's function method. In this way the thermal fluctuations are incorporated in the Caldirola-Kanai Hamiltonian

  5. Relativistic band gaps in one-dimensional disordered systems

    International Nuclear Information System (INIS)

    Clerk, G.J.; McKellar, B.H.J.

    1992-01-01

    Conditions for the existence of band gaps in a one-dimensional disordered array of δ-function potentials possessing short range order are developed in a relativistic framework. Both Lorentz vector and scalar type potentials are treated. The relationship between the energy gaps and the transmission properties of the array are also discussed. 20 refs., 2 figs

  6. The electromagnetic Brillouin precursor in one-dimensional photonic crystals

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.

    2008-01-01

    We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron

  7. On the quantisation of one-dimensional bags

    International Nuclear Information System (INIS)

    Fairley, G.T.; Squires, E.J.

    1976-01-01

    The quantisation of one-dimensional MIT bags by expanding the fields as a sum of classical modes and truncating the series after the first term is discussed. The lowest states of a bag in a world containing two scalar quark fields are obtained. Problems associated with the zero-point oscillations of the field are discussed. (Auth.)

  8. The appropriateness of one-dimensional Yucca Mountain hydrologic calculations

    International Nuclear Information System (INIS)

    Eaton, R.R.

    1993-07-01

    This report brings into focus the results of numerous studies that have addressed issues associated with the validity of assumptions which are used to justify reducing the dimensionality of numerical calculations of water flow through Yucca Mountain, NV. it is shown that, in many cases, one-dimensional modeling is more rigorous than previously assumed

  9. Light propagation in one-dimensional porous silicon complex systems

    NARCIS (Netherlands)

    Oton, C.J.; Dal Negro, L.; Gaburro, Z.; Pavesi, L.; Johnson, P.J.; Lagendijk, Aart; Wiersma, D.S.

    2003-01-01

    We discuss the optical properties of one-dimensional complex dielectric systems, in particular the time-resolved transmission through thick porous silicon quasiperiodic multi-layers. Both in numerical calculations and experiments we find dramatic distortion effects, i.e. pulse stretching and

  10. Analytical approach for collective diffusion: one-dimensional heterogeneous lattice

    Czech Academy of Sciences Publication Activity Database

    Tarasenko, Alexander

    2016-01-01

    Roč. 144, č. 14 (2016), 1-11, č. článku 144105. ISSN 0021-9606 Institutional support: RVO:68378271 Keywords : diffusion * Monte Carlo simulations * one-dimensional heterogeneous lattice Subject RIV: BE - Theoretical Physics Impact factor: 2.965, year: 2016

  11. Approximate Approaches to the One-Dimensional Finite Potential Well

    Science.gov (United States)

    Singh, Shilpi; Pathak, Praveen; Singh, Vijay A.

    2011-01-01

    The one-dimensional finite well is a textbook problem. We propose approximate approaches to obtain the energy levels of the well. The finite well is also encountered in semiconductor heterostructures where the carrier mass inside the well (m[subscript i]) is taken to be distinct from mass outside (m[subscript o]). A relevant parameter is the mass…

  12. Toward precise solution of one-dimensional velocity inverse problems

    International Nuclear Information System (INIS)

    Gray, S.; Hagin, F.

    1980-01-01

    A family of one-dimensional inverse problems are considered with the goal of reconstructing velocity profiles to reasonably high accuracy. The travel-time variable change is used together with an iteration scheme to produce an effective algorithm for computation. Under modest assumptions the scheme is shown to be convergent

  13. Probing exotic phases of interacting two-dimensional carriers using one-dimensional density modulation

    Science.gov (United States)

    Mueed, M. A.

    In this Thesis, we present low-temperature magnetotransport studies of two-dimensional (2D) electron and hole systems confined to GaAs quantum wells and subjected to a one-dimensional, periodic density modulation. The modulation is achieved through the piezo-electric effect in GaAs as we fabricate a periodic, strain-inducing superlattice on the sample surface. Under varying perpendicular magnetic field, whenever the carriers' cyclotron orbit becomes commensurate with the modulation period, the magnetoresistance exhibits a minimum value. The resulting oscillations, known as the commensurability oscillations, directly measure the carriers' Fermi wave vector. Imposing a density modulation thus allows us to study the Fermi contour properties of 2D electrons and holes near zero field, and composite fermions (CFs) near the half filling of the lowest Landau level, i.e., filling factor nu=1/2. The application of a parallel magnetic field (B||) also features extensively in the Thesis. First, we use commensurability oscillations to capture the B||-induced deformation and the eventual splitting of the Fermi contour of 2D electrons. We also deduce the scattering time anisotropy of hole-flux CFs whose Fermi contour is rendered anisotropic by B||. Moreover, we study the anisotropic (warped) Fermi contour of 2D holes and hole-flux CFs in wide quantum well samples at B||=0. The results provide evidence that CFs inherit Fermi contour properties from their zero-field counterparts. We further investigate the fate of CFs near the bilayer quantum Hall states at nu=1 and 1/2 induced by a large B||. We observe that the commensurability features of CFs near nu=1 are consistent with half the total carrier density, implying that CFs prefer to stay in separate layers and show a two-component behavior. In contrast, close to nu=1/2, CFs appear single-layer-like (single-component) as their commensurability features correspond to the total density. This finding sheds light on the different

  14. Quantum anomalous Hall phase in a one-dimensional optical lattice

    Science.gov (United States)

    Liu, Sheng; Shao, L. B.; Hou, Qi-Zhe; Xue, Zheng-Yuan

    2018-03-01

    We propose to simulate and detect quantum anomalous Hall phase with ultracold atoms in a one-dimensional optical lattice, with the other synthetic dimension being realized by modulating spin-orbit coupling. We show that the system manifests a topologically nontrivial phase with two chiral edge states which can be readily detected in this synthetic two-dimensional system. Moreover, it is interesting that at the phase transition point there is a flat energy band and this system can also be in a topologically nontrivial phase with two Fermi zero modes existing at the boundaries by considering the synthetic dimension as a modulated parameter. We also show how to measure these topological phases experimentally in ultracold atoms. Another model with a random Rashba and Dresselhaus spin-orbit coupling strength is also found to exhibit topological nontrivial phase, and the impact of the disorder to the system is revealed.

  15. Low-density, one-dimensional quantum gases in the presence of a localized attractive potential

    International Nuclear Information System (INIS)

    Goold, J; O'Donoghue, D; Busch, Th

    2008-01-01

    We investigate low-density, quantum-degenerate gases in the presence of a localized attractive potential in the centre of a one-dimensional harmonic trap. The attractive potential is modelled using a parameterized δ-function, allowing us to determine all single-particle eigenfunctions analytically. From these we calculate the ground-state many-body properties for a system of spin-polarized fermions and, using the Bose-Fermi mapping theorem, extend the results to strongly interacting bosonic systems. We discuss the single-particle densities, the pair-correlation functions, the reduced single-particle density matrices and the momentum distributions as a function of the particle number and strength of the attractive point potential. As an important experimental observable, we place special emphasis on spatial coherence properties of such samples.

  16. Renormalization of Fermi Velocity in a Composite Two Dimensional Electron Gas

    Science.gov (United States)

    Weger, M.; Burlachkov, L.

    We calculate the self-energy Σ(k, ω) of an electron gas with a Coulomb interaction in a composite 2D system, consisting of metallic layers of thickness d ≳ a0, where a0 = ħ2ɛ1/me2 is the Bohr radius, separated by layers with a dielectric constant ɛ2 and a lattice constant c perpendicular to the planes. The behavior of the electron gas is determined by the dimensionless parameters kFa0 and kFc ɛ2/ɛ1. We find that when ɛ2/ɛ1 is large (≈5 or more), the velocity v(k) becomes strongly k-dependent near kF, and v(kF) is enhanced by a factor of 5-10. This behavior is similar to the one found by Lindhard in 1954 for an unscreened electron gas; however here we take screening into account. The peak in v(k) is very sharp (δk/kF is a few percent) and becomes sharper as ɛ2/ɛ1 increases. This velocity renormalization has dramatic effects on the transport properties; the conductivity at low T increases like the square of the velocity renormalization and the resistivity due to elastic scattering becomes temperature dependent, increasing approximately linearly with T. For scattering by phonons, ρ ∝ T2. Preliminary measurements suggest an increase in vk in YBCO very close to kF.

  17. One-dimensional adiabatic model of waterhammer; Endodimenzionalni adiabatni model vodnega udara

    Energy Technology Data Exchange (ETDEWEB)

    Bizjak, S [Institut Jozef Stefan, Ljubljana (Yugoslavia)

    1984-07-01

    Program WH was developed to calculate transient pressure and velocities in hydraulic networks. It is based on one-dimensional approximation of conservation laws of mass and momentum. the energy equation is ignored which means that heat transfer effects are no included. When calculating the velocity of pressure wave, compressibility of liquid, elasticity of pipe and possible minimal presence of gas in bubble or dissolved form are included. (author)

  18. Anisotropic non-Fermi liquids

    Science.gov (United States)

    Sur, Shouvik; Lee, Sung-Sik

    2016-11-01

    We study non-Fermi-liquid states that arise at the quantum critical points associated with the spin density wave (SDW) and charge density wave (CDW) transitions in metals with twofold rotational symmetry. We use the dimensional regularization scheme, where a one-dimensional Fermi surface is embedded in (3 -ɛ ) -dimensional momentum space. In three dimensions, quasilocal marginal Fermi liquids arise both at the SDW and CDW critical points: the speed of the collective mode along the ordering wave vector is logarithmically renormalized to zero compared to that of Fermi velocity. Below three dimensions, however, the SDW and CDW critical points exhibit drastically different behaviors. At the SDW critical point, a stable anisotropic non-Fermi-liquid state is realized for small ɛ , where not only time but also different spatial coordinates develop distinct anomalous dimensions. The non-Fermi liquid exhibits an emergent algebraic nesting as the patches of Fermi surface are deformed into a universal power-law shape near the hot spots. Due to the anisotropic scaling, the energy of incoherent spin fluctuations disperse with different power laws in different momentum directions. At the CDW critical point, on the other hand, the perturbative expansion breaks down immediately below three dimensions as the interaction renormalizes the speed of charge fluctuations to zero within a finite renormalization group scale through a two-loop effect. The difference originates from the fact that the vertex correction antiscreens the coupling at the SDW critical point whereas it screens at the CDW critical point.

  19. Dynamical instability of a spin spiral in an interacting Fermi gas as a probe of the Stoner transition

    Science.gov (United States)

    Conduit, G. J.; Altman, E.

    2010-10-01

    We propose an experiment to probe ferromagnetic phenomena in an ultracold Fermi gas, while alleviating the sensitivity to three-body loss and competing many-body instabilities. The system is initialized in a small pitch spin spiral, which becomes unstable in the presence of repulsive interactions. To linear order the exponentially growing collective modes exhibit critical slowing down close to the Stoner transition point. Also, to this order, the dynamics are identical on the paramagnetic and ferromagnetic sides of the transition. However, we show that scattering off the exponentially growing modes qualitatively alters the collective mode structure. The critical slowing down is eliminated and in its place a new unstable branch develops at large wave vectors. Furthermore, long-wavelength instabilities are quenched on the paramagnetic side of the transition. We study the experimental observation of the instabilities, specifically addressing the trapping geometry and how phase-contrast imaging will reveal the emerging domain structure. These probes of the dynamical phenomena could allow experiments to detect the transition point and distinguish between the paramagnetic and ferromagnetic regimes.

  20. Dynamical instability of a spin spiral in an interacting Fermi gas as a probe of the Stoner transition

    International Nuclear Information System (INIS)

    Conduit, G. J.; Altman, E.

    2010-01-01

    We propose an experiment to probe ferromagnetic phenomena in an ultracold Fermi gas, while alleviating the sensitivity to three-body loss and competing many-body instabilities. The system is initialized in a small pitch spin spiral, which becomes unstable in the presence of repulsive interactions. To linear order the exponentially growing collective modes exhibit critical slowing down close to the Stoner transition point. Also, to this order, the dynamics are identical on the paramagnetic and ferromagnetic sides of the transition. However, we show that scattering off the exponentially growing modes qualitatively alters the collective mode structure. The critical slowing down is eliminated and in its place a new unstable branch develops at large wave vectors. Furthermore, long-wavelength instabilities are quenched on the paramagnetic side of the transition. We study the experimental observation of the instabilities, specifically addressing the trapping geometry and how phase-contrast imaging will reveal the emerging domain structure. These probes of the dynamical phenomena could allow experiments to detect the transition point and distinguish between the paramagnetic and ferromagnetic regimes.

  1. Dynamical vanishing of the order parameter in a confined Bardeen-Cooper-Schrieffer Fermi gas after an interaction quench

    Science.gov (United States)

    Hannibal, S.; Kettmann, P.; Croitoru, M. D.; Axt, V. M.; Kuhn, T.

    2018-01-01

    We present a numerical study of the Higgs mode in an ultracold confined Fermi gas after an interaction quench and find a dynamical vanishing of the superfluid order parameter. Our calculations are done within a microscopic density-matrix approach in the Bogoliubov-de Gennes framework which takes the three-dimensional cigar-shaped confinement explicitly into account. In this framework, we study the amplitude mode of the order parameter after interaction quenches starting on the BCS side of the BEC-BCS crossover close to the transition and ending in the BCS regime. We demonstrate the emergence of a dynamically vanishing superfluid order parameter in the spatiotemporal dynamics in a three-dimensional trap. Further, we show that the signal averaged over the whole trap mirrors the spatiotemporal behavior and allows us to systematically study the effects of the system size and aspect ratio on the observed dynamics. Our analysis enables us to connect the confinement-induced modifications of the dynamics to the pairing properties of the system. Finally, we demonstrate that the signature of the Higgs mode is contained in the dynamical signal of the condensate fraction, which, therefore, might provide a new experimental access to the nonadiabatic regime of the Higgs mode.

  2. To the theory of spin-charge separation in one-dimensional correlated electron systems

    International Nuclear Information System (INIS)

    Zvyagin, A.A.

    2004-01-01

    Spin-charge separation is considered to be one of the key properties that distinguish low-dimensional electron systems from others. Three-dimensional correlated electron systems are described by the Fermi liquid theory. There, low-energy excitations (quasiparticles) are reminiscent of noninteracting electrons: They carry charges -e and spins 1/2 . It is believed that for any one-dimensional correlated electron system, low-lying electron excitations carry either only spin and no charge, or only charge without spin. That is why recent experiments looked for such low-lying collective electron excitations, one of which carries only spin, and the other carries only charge. Here we show that despite the fact that for exactly solvable one-dimensional correlated electron models there exist excitations which carry only spin and only charge, in all these models with short-range interactions the low-energy physics is described by low-lying collective excitations, one of which carries both spin and charge

  3. Topological phases of interacting fermions in one-dimensional superconductor - normal metal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Meidan, Dganit [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universitaet Berlin, 14195 Berlin (Germany); Romito, Alessandro; Brouwer, Piet W. [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2015-07-01

    One-dimensional superconductors can be in non-trivial topological phases harboring Majorana end-states, which possess non-abelian statistics. It has been recently established that in the presence of interactions the classification of topological superconducting phases can be significantly altered. Specifically, for one-dimensional superconductors possessing a time reversal symmetry (BDI class), interactions reduce the infinitely many non-interacting phases (Z topological index) to eight distinct ones (Z{sub 8} topological index). In this talk I will consider multi-mode superconducting wires in such BDI class when probed by an external contact, and discuss their low temperature and voltage bias transport properties. I will first show that the Andreev reflection component of the scattering matrix of the probing lead provides a topological index, r=-4,.., 4, which distinguish the eight topological phases. The two topologically equivalent phases with r= 4,-4 support emergent many-body end states, which are identified to be a topologically protected Kondo-like resonance. The path in phase space that connects these equivalent phases crosses a non-fermi liquid fixed point where a multiple channel Kondo effect develops.

  4. Unexpected Magnetic Semiconductor Behavior in Zigzag Phosphorene Nanoribbons Driven by Half-Filled One Dimensional Band

    Science.gov (United States)

    Du, Yongping; Liu, Huimei; Xu, Bo; Sheng, Li; Yin, Jiang; Duan, Chun-Gang; Wan, Xiangang

    2015-01-01

    Phosphorene, as a novel two-dimensional material, has attracted a great interest due to its novel electronic structure. The pursuit of controlled magnetism in Phosphorene in particular has been persisting goal in this area. In this paper, an antiferromagnetic insulating state has been found in the zigzag phosphorene nanoribbons (ZPNRs) from the comprehensive density functional theory calculations. Comparing with other one-dimensional systems, the magnetism in ZPNRs display several surprising characteristics: (i) the magnetic moments are antiparallel arranged at each zigzag edge; (ii) the magnetism is quite stable in energy (about 29 meV/magnetic-ion) and the band gap is big (about 0.7 eV); (iii) the electronic and magnetic properties is almost independent on the width of nanoribbons; (iv) a moderate compressive strain will induce a magnetic to nonmagnetic as well as semiconductor to metal transition. All of these phenomena arise naturally due to one unique mechanism, namely the electronic instability induced by the half-filled one-dimensional bands which cross the Fermi level at around π/2a. The unusual electronic and magnetic properties in ZPNRs endow them possible potential for the applications in nanoelectronic devices. PMID:25747727

  5. Theory of a condensed charged-Bose, charged Fermi gas and Ginzburg--Landau studies of superfluid 3He

    International Nuclear Information System (INIS)

    Dahl, D.A.

    1976-01-01

    Two independent topics in the field of condensed matter physics are examined: the condensed charged-Bose, charged Fermi gas and superfluid 3 He. Green's function (field theoretic) methods are used to derive the low-temperature properties of a dense, neutral gas of condensed charged bosons and degenerate charged fermions. Restriction is made to the case where the fermion mass is much lighter than the boson mass. Linear response and the density-density correlation function are examined and shown to exhibit two collective modes: a plasmon branch and a phonon branch with speed equal to that of ionic sound in solids. Comparison with a possible astrophysical application (white dwarf stars) is made. The behavior near the superfluid transition temperature (Ginzburg--Landau regime) of 3 He is then studied. Gorkov equations are derived and studied in the weak-coupling limit. In this way the form and order of magnitude estimates of coefficients appearing in the Ginzburg--Landau theory are obtained. Weak-coupling particle and spin currents are derived. Various perturbations break the large degeneracy of the states and have experimental implications. The electric contribution to the Ginzburg--Landau free energy is studied for the proposed A and B phases. Imposition of an electric field orients the axial state, but does not give rise to shifts in the NMR resonances. Shifts and discontinuous jumps in the longitudinal and transverse signals are predicted for the Balian--Werthamer state, the details depending on the relative strengths of the fields, as well as the angle between them

  6. Bound states of Dipolar Bosons in One-dimensional Systems

    DEFF Research Database (Denmark)

    G. Volosniev, A.; R. Armstrong, J.; V. Fedorov, D.

    2013-01-01

    that in the weakly-coupled limit the inter-tube interaction is similar to a zero-range term with a suitable rescaled strength. This allows us to address the corresponding many-body physics of the system by constructing a model where bound chains with one molecule in each tube are the effective degrees of freedom......We consider one-dimensional tubes containing bosonic polar molecules. The long-range dipole-dipole interactions act both within a single tube and between different tubes. We consider arbitrary values of the externally aligned dipole moments with respect to the symmetry axis of the tubes. The few....... This model can be mapped onto one-dimensional Hamiltonians for which exact solutions are known....

  7. Quasi-One-Dimensional Intermittent Flux Behavior in Superconducting Films

    Directory of Open Access Journals (Sweden)

    A. J. Qviller

    2012-01-01

    Full Text Available Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa_{2}Cu_{3}O_{7-δ} deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a power law, and data collapse is obtained by finite-size scaling, with the depth of the flux front used as crossover length. The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching avalanches that are commonly found in superconducting films.

  8. Versatile hydrothermal synthesis of one-dimensional composite structures

    Science.gov (United States)

    Luo, Yonglan

    2008-12-01

    In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.

  9. Solitons in one-dimensional charge density wave systems

    International Nuclear Information System (INIS)

    Su, W.P.

    1981-01-01

    Theoretical research on one dimensional charge density wave systems is outlined. A simple coupled electron-photon Hamiltonian is studied including a Green's function approach, molecular dynamics, and Monte Carlo path integral method. As in superconductivity, the nonperturbative nature of the system makes the physical ground states and low energy excitations drastically different from the bare electrons and phonons. Solitons carry quantum numbers which are entirely different from those of the bare electrons and holes. The fractional charge character of the solitons is an example of this fact. Solitons are conveniently generated by doping material with donors or acceptors or by photon absorption. Most predictions of the theory are in qualitative agreement with experiments. The one dimensional charge density wave system has potential technological importance and a possible role in uncovering phenomena which might have implications in relativistic field theory and elementary particle physics

  10. Applications of one-dimensional models in simplified inelastic analyses

    International Nuclear Information System (INIS)

    Kamal, S.A.; Chern, J.M.; Pai, D.H.

    1980-01-01

    This paper presents an approximate inelastic analysis based on geometric simplification with emphasis on its applicability, modeling, and the method of defining the loading conditions. Two problems are investigated: a one-dimensional axisymmetric model of generalized plane strain thick-walled cylinder is applied to the primary sodium inlet nozzle of the Clinch River Breeder Reactor Intermediate Heat Exchanger (CRBRP-IHX), and a finite cylindrical shell is used to simulate the branch shell forging (Y) junction. The results are then compared with the available detailed inelastic analyses under cyclic loading conditions in terms of creep and fatigue damages and inelastic ratchetting strains per the ASME Code Case N-47 requirements. In both problems, the one-dimensional simulation is able to trace the detailed stress-strain response. The quantitative comparison is good for the nozzle, but less satisfactory for the Y junction. Refinements are suggested to further improve the simulation

  11. Thermoelectric properties of one-dimensional graphene antidot arrays

    International Nuclear Information System (INIS)

    Yan, Yonghong; Liang, Qi-Feng; Zhao, Hui; Wu, Chang-Qin; Li, Baowen

    2012-01-01

    We investigate the thermoelectric properties of one-dimensional (1D) graphene antidot arrays by nonequilibrium Green's function method. We show that by introducing antidots to the pristine graphene nanoribbon the thermal conductance can be reduced greatly while keeping the power factor still high, thus leading to an enhanced thermoelectric figure of merit (ZT). Our numerical results indicate that ZT values of 1D antidot graphene arrays can be up to unity, which means the 1D graphene antidot arrays may be promising for thermoelectric applications. -- Highlights: ► We study thermoelectric properties of one-dimensional (1D) graphene antidot arrays. ► Thermoelectric figure of merit (ZT) of 1D antidot arrays can exceed unity. ► ZT of 1D antidot arrays is larger than that of two-dimensional arrays.

  12. Scattering theory for one-dimensional step potentials

    International Nuclear Information System (INIS)

    Ruijsenaars, S.N.M.; Bongaarts, P.J.M.

    1977-01-01

    The scattering theory is treated for the one-dimensional Dirac equation with potentials that are bounded, measurable, real-valued functions on the real line, having constant values, not necessarily the same, on the left and on the right side of a compact interval. Such potentials appear in the Klein paradox. It is shown that appropriately modified wave operators exist and that the corresponding S-operator is unitary. The connection between time-dependent scattering theory and time-independent scattering theory in terms of incoming and outgoing plane wave solutions is established and some further properties are proved. All results and their proofs have a straightforward translation to the one-dimensional Schroedinger equation with the same class of step potentials

  13. Resonance Raman spectroscopy in one-dimensional carbon materials

    Directory of Open Access Journals (Sweden)

    Dresselhaus Mildred S.

    2006-01-01

    Full Text Available Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples.

  14. Impurity modes in the one-dimensional XXZ Heisenberg model

    International Nuclear Information System (INIS)

    Sousa, J.M.; Leite, R.V.; Landim, R.R.; Costa Filho, R.N.

    2014-01-01

    A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken.

  15. UNICIN - an one-dimensional computer code for reactor kinetics

    International Nuclear Information System (INIS)

    Rosa, M.A.P.; Alcantara, H.G. de; Nair, R.P.K.

    1984-01-01

    A program for the solution of the time- and space-dependent multigroup diffusion equations and the delayed-neutron precursors concentration equations in one dimensional geometries by the weighted residual method is described. The discretized equations are solved through an iterative procedure with convergence accelerated by the over-relaxation method. The system is perturbed through the variation of the nuclide concentrations in specified regions. Two feedback effects are included, namely, the temperature and the burnup. (Author) [pt

  16. Nonlinear acoustic wave propagating in one-dimensional layered system

    International Nuclear Information System (INIS)

    Yun, Y.; Miao, G.Q.; Zhang, P.; Huang, K.; Wei, R.J.

    2005-01-01

    The propagation of finite-amplitude plane sound in one-dimensional layered media is studied by the extended method of transfer matrix formalism. For the periodic layered system consisting of two alternate types of liquid, the energy distribution and the phase vectors of the interface vibration are computed and analyzed. It is found that in the pass-band, the second harmonic of sound wave can propagate with the characteristic modulation

  17. The analysis of one-dimensional reactor kinetics benchmark computations

    International Nuclear Information System (INIS)

    Sidell, J.

    1975-11-01

    During March 1973 the European American Committee on Reactor Physics proposed a series of simple one-dimensional reactor kinetics problems, with the intention of comparing the relative efficiencies of the numerical methods employed in various codes, which are currently in use in many national laboratories. This report reviews the contributions submitted to this benchmark exercise and attempts to assess the relative merits and drawbacks of the various theoretical and computer methods. (author)

  18. Heat transfer in a one-dimensional mixed convection loop

    International Nuclear Information System (INIS)

    Kim, Min Joon; Lee, Yong Bum; Kim, Yong Kyun; Kim, Jong Man; Nam, Ho Yun

    1999-01-01

    Effects of non-uniform heating in the core and additional forced circulation during decay heat removal operation are studied with a simplified mixed convection loop. The heat transfer coefficient is calculated analytically and measured experimentally. The analytic solution obtained from a one-dimensional heat equation is found to agree well with the experimental results. The effects of the non-uniform heating and the forced circulation are discussed

  19. Energy in one-dimensional linear waves in a string

    International Nuclear Information System (INIS)

    Burko, Lior M

    2010-01-01

    We consider the energy density and energy transfer in small amplitude, one-dimensional waves on a string and find that the common expressions used in textbooks for the introductory physics with calculus course give wrong results for some cases, including standing waves. We discuss the origin of the problem, and how it can be corrected in a way appropriate for the introductory calculus-based physics course. (letters and comments)

  20. Quasi-one-dimensional intermittent flux behavior in superconducting films

    OpenAIRE

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.; Vestgården, J. I.; Mozhaev, Peter; Hansen, Jørn Bindslev; Johansen, T. H.

    2012-01-01

    Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa_{2}Cu_{3}O_{7-δ} deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film. As the applied field is gradually increased, magneto-optical imaging reveals that flux penetrates via numerous quasi-one-dimensional jumps. The distribution of flux avalanche sizes follows a ...

  1. Variational iteration method for one dimensional nonlinear thermoelasticity

    International Nuclear Information System (INIS)

    Sweilam, N.H.; Khader, M.M.

    2007-01-01

    This paper applies the variational iteration method to solve the Cauchy problem arising in one dimensional nonlinear thermoelasticity. The advantage of this method is to overcome the difficulty of calculation of Adomian's polynomials in the Adomian's decomposition method. The numerical results of this method are compared with the exact solution of an artificial model to show the efficiency of the method. The approximate solutions show that the variational iteration method is a powerful mathematical tool for solving nonlinear problems

  2. Localization in a one-dimensional spatially correlated random potential

    International Nuclear Information System (INIS)

    Kasner, M.; Weller, W.

    1986-01-01

    The motion of an electron in a random one-dimensional spatially correlated potential is investigated. The spatial correlation is generated by a Markov chain. It is shown that the influence of the spatial correlation can be described by means of oscillating vertices usually neglected in the Berezinskii diagram technique. Correlation mainly leads to an increase of the localization length in comparison with an uncorrelated potential. However, there is a region of the parameter, where the localization decreases. (author)

  3. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    OpenAIRE

    Nikola Stefanović

    2007-01-01

    In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic ...

  4. Graphene-based one-dimensional photonic crystal

    OpenAIRE

    Berman, Oleg L.; Kezerashvili, Roman Ya.

    2011-01-01

    A novel type of one-dimensional (1D) photonic crystal formed by the array of periodically located stacks of alternating graphene and dielectric stripes embedded into a background dielectric medium is proposed. The wave equation for the electromagnetic wave propagating in such structure solved in the framework of the Kronig-Penney model. The frequency band structure of 1D graphene-based photonic crystal is obtained analytically as a function of the filling factor and the thickness of the diele...

  5. Negative Refraction Angular Characterization in One-Dimensional Photonic Crystals

    OpenAIRE

    Lugo, Jesus Eduardo; Doti, Rafael; Faubert, Jocelyn

    2011-01-01

    Background Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity de...

  6. Majorana fermion exchange in strictly one dimensional structures

    OpenAIRE

    Chiu, Ching-Kai; Vazifeh, M. M.; Franz, M.

    2014-01-01

    It is generally thought that adiabatic exchange of two identical particles is impossible in one spatial dimension. Here we describe a simple protocol that permits adiabatic exchange of two Majorana fermions in a one-dimensional topological superconductor wire. The exchange relies on the concept of "Majorana shuttle" whereby a $\\pi$ domain wall in the superconducting order parameter which hosts a pair of ancillary Majoranas delivers one zero mode across the wire while the other one tunnels in ...

  7. On a class of one-dimensional random walks

    NARCIS (Netherlands)

    O.J. Boxma (Onno); V.I. Lotov

    1995-01-01

    textabstractnoindent This paper studies a one-dimensional Markov chain ${X_n,n=0,1,dots$ that satisfies the recurrence relation $X_n = max(0, X_{n-1 + eta_n^{(m) )$ if $X_{n-1 =m leq a$; for $X_{n-1 > a$ it satisfies the same relation with $eta_n^{(m)$ replaced by $xi_n$. Here ${ eta_n^{(m) $ and ${

  8. Theory of the one-dimensional forest-fire model

    International Nuclear Information System (INIS)

    Paczuski, M.; Bak, P.

    1993-01-01

    Turbulent cascade processes are studied in terms of a one-dimensional forest-fire model. A hier- archy of steady-state equations for the forests and the holes between them is constructed and solved within a mean-field closure scheme. The exact hole distribution function is found to be N H (s)=4N/[s(s+1)(s+2)], where N is the number of forests

  9. Quantum logic using correlated one-dimensional quantum walks

    Science.gov (United States)

    Lahini, Yoav; Steinbrecher, Gregory R.; Bookatz, Adam D.; Englund, Dirk

    2018-01-01

    Quantum Walks are unitary processes describing the evolution of an initially localized wavefunction on a lattice potential. The complexity of the dynamics increases significantly when several indistinguishable quantum walkers propagate on the same lattice simultaneously, as these develop non-trivial spatial correlations that depend on the particle's quantum statistics, mutual interactions, initial positions, and the lattice potential. We show that even in the simplest case of a quantum walk on a one dimensional graph, these correlations can be shaped to yield a complete set of compact quantum logic operations. We provide detailed recipes for implementing quantum logic on one-dimensional quantum walks in two general cases. For non-interacting bosons—such as photons in waveguide lattices—we find high-fidelity probabilistic quantum gates that could be integrated into linear optics quantum computation schemes. For interacting quantum-walkers on a one-dimensional lattice—a situation that has recently been demonstrated using ultra-cold atoms—we find deterministic logic operations that are universal for quantum information processing. The suggested implementation requires minimal resources and a level of control that is within reach using recently demonstrated techniques. Further work is required to address error-correction.

  10. Gravitational anomalies and one-dimensional behavior of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Majhi, Bibhas Ranjan [Indian Institute of Technology Guwahati, Department of Physics, Guwahati, Assam (India)

    2015-12-15

    It has been pointed out by Bekenstein and Mayo that the behavior of the black hole's entropy or information flow is similar to information flow through one-dimensional channel. Here I analyze the same issue with the use of gravitational anomalies. The rate of the entropy change (S) and the power (P) of the Hawking emission are calculated from the relevant components of the anomalous stress tensor under the Unruh vacuum condition. I show that the dependence of S on the power is S ∝ P{sup 1/2}, which is identical to that for the information flow in a one-dimensional system. This is established by using the (1+1)-dimensional gravitational anomalies first. Then the fact is further bolstered by considering the (1+3)-dimensional gravitational anomalies. It is found that, in the former case, the proportionality constant is exactly identical to the one-dimensional situation, known as Pendry's formula, while in the latter situation its value decreases. (orig.)

  11. One-dimensional crystal with a complex periodic potential

    International Nuclear Information System (INIS)

    Boyd, John K.

    2001-01-01

    A one-dimensional crystal model is constructed with a complex periodic potential. A wave function solution for the crystal model is derived without relying on Bloch functions. The new wave function solution of this model is shown to correspond to the solution for the probability amplitude of a two-level system. The energy discriminant is evaluated using an analytic formula derived from the probability amplitude solution, and based on an expansion parameter related to the energy and potential amplitude. From the wave function energy discriminant the crystal band structure is derived and related to standard energy bands and gaps. It is also shown that several of the properties of the two-level system apply to the one-dimensional crystal model. The two-level system solution which evolves in time is shown to manifest as a spatial configuration of the one-dimensional crystal model. The sensitivity of the wave function probability density is interpreted in the context of the new solution. The spatial configuration of the wave function, and the appearance of a long wavelength in the wave function probability density is explained in terms of the properties of Bessel functions

  12. Multi-gas interaction modeling on decorated semiconductor interfaces: A novel Fermi distribution-based response isotherm and the inverse hard/soft acid/base concept

    Energy Technology Data Exchange (ETDEWEB)

    Laminack, William [Department of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Gole, James, E-mail: James.Gole@physics.gatech.edu [Department of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Department of Mechanical Engineering, Georgia Tech, Atlanta, GA 30332 (United States)

    2015-12-30

    Graphical abstract: Visual representation of the PS interface interacting with mixed gas configurations. The red dots correspond to nanostructured metal oxides. Each combination of distinct molecules are labeled below the pores, which are oversized in the figure. - Highlights: • First study of mixed gas analytes interacting with a micro-porous silicon substrate. • Responses are represented by a newly developed response absorption isotherm. • This isotherm is modeled on the basis of the Fermi distribution function. • The developing IHSAB concept explains multi-gas analyte–analyte interactions. - Abstract: A unique MEMS/NEMS approach is presented for the modeling of a detection platform for mixed gas interactions. Mixed gas analytes interact with nanostructured decorating metal oxide island sites supported on a microporous silicon substrate. The Inverse Hard/Soft acid/base (IHSAB) concept is used to assess a diversity of conductometric responses for mixed gas interactions as a function of these nanostructured metal oxides. The analyte conductometric responses are well represented using a combination diffusion/absorption-based model for multi-gas interactions where a newly developed response absorption isotherm, based on the Fermi distribution function is applied. A further coupling of this model with the IHSAB concept describes the considerations in modeling of multi-gas mixed analyte–interface, and analyte–analyte interactions. Taking into account the molecular electronic interaction of both the analytes with each other and an extrinsic semiconductor interface we demonstrate how the presence of one gas can enhance or diminish the reversible interaction of a second gas with the extrinsic semiconductor interface. These concepts demonstrate important considerations in the array-based formats for multi-gas sensing and its applications.

  13. Advanced One-Dimensional Entrained-Flow Gasifier Model Considering Melting Phenomenon of Ash

    Directory of Open Access Journals (Sweden)

    Jinsu Kim

    2018-04-01

    Full Text Available A one-dimensional model is developed to represent the ash-melting phenomenon, which was not considered in the previous one-dimensional (1-D entrained-flow gasifier model. We include sensible heat of slag and the fusion heat of ash in the heat balance equation. To consider the melting of ash, we propose an algorithm that calculates the energy balance for three scenarios based on temperature. We also use the composition and the thermal properties of anorthite mineral to express ash. gPROMS for differential equations is used to solve this algorithm in a simulation; the results include coal conversion, gas composition, and temperature profile. Based on the Texaco pilot plant gasifier, we validate our model. Our results show good agreement with previous experimental data. We conclude that the sensible heat of slag and the fusion heat of ash must be included in the entrained flow gasifier model.

  14. Lateral shift in one-dimensional quasiperiodic chiral photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Da, Jian, E-mail: dajian521@sina.com [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Mo, Qi, E-mail: moqiyueyang@163.com [School of Software, Yunnan University, Cuihu Bai Road, Kunming City, Yunnan Province 650091 (China); Cheng, Yaokun [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Liu, Taixiang [Taishan Vocational College of Nursing, Shandong Province 271000 (China)

    2015-02-01

    We investigate the lateral shift of a one-dimensional quasiperiodic photonic crystal consisting of chiral and conventional dielectric materials. The effect of structural irregularity on lateral shift is evaluated by stationary-phase approach. Our results show that the lateral shift can be modulated by varying the structural irregularity in quasiperiodic structure. Besides, the position of peak in lateral shift spectrum stays sensitive to the chiral factor of chiral materials. In comparison with that of periodic structure, quasiperiodic structure provides an extra degree of freedom to manipulate the lateral shift.

  15. Integrability of the one dimensional Schrödinger equation

    Science.gov (United States)

    Combot, Thierry

    2018-02-01

    We present a definition of integrability for the one-dimensional Schrödinger equation, which encompasses all known integrable systems, i.e., systems for which the spectrum can be explicitly computed. For this, we introduce the class of rigid functions, built as Liouvillian functions, but containing all solutions of rigid differential operators in the sense of Katz, and a notion of natural of boundary conditions. We then make a complete classification of rational integrable potentials. Many new integrable cases are found, some of them physically interesting.

  16. Inversion of reflection for the one-dimensional Dirac equation

    International Nuclear Information System (INIS)

    Clerk, G.L.; Davies, A.J.

    1991-01-01

    It is a general result of one-dimensional non-relativistic quantum mechanics that the coefficient of reflection (reflected flux) is the same irrespective of the direction of traversing a potential barrier, a result that is independent of the barrier shape. In this note, the authors consider the transmission coefficient instead, and derive a strong result, namely that the transmission amplitude is independent of the direction of barrier traversal. That is, the transmission amplitude has the same complex phase as well as being unchanged in magnitude by changing the barrier around. This process was called inversion of reflection. 2 refs

  17. Two-dimensional beam profiles and one-dimensional projections

    Science.gov (United States)

    Findlay, D. J. S.; Jones, B.; Adams, D. J.

    2018-05-01

    One-dimensional projections of improved two-dimensional representations of transverse profiles of particle beams are proposed for fitting to data from harp-type monitors measuring beam profiles on particle accelerators. Composite distributions, with tails smoothly matched on to a central (inverted) parabola, are shown to give noticeably better fits than single gaussian and single parabolic distributions to data from harp-type beam profile monitors all along the proton beam transport lines to the two target stations on the ISIS Spallation Neutron Source. Some implications for inferring beam current densities on the beam axis are noted.

  18. Optical Tamm states in one-dimensional magnetophotonic structures.

    Science.gov (United States)

    Goto, T; Dorofeenko, A V; Merzlikin, A M; Baryshev, A V; Vinogradov, A P; Inoue, M; Lisyansky, A A; Granovsky, A B

    2008-09-12

    We demonstrate the existence of a spectrally narrow localized surface state, the so-called optical Tamm state, at the interface between one-dimensional magnetophotonic and nonmagnetic photonic crystals. The state is spectrally located inside the photonic band gaps of each of the photonic crystals comprising this magnetophotonic structure. This state is associated with a sharp transmission peak through the sample and is responsible for the substantial enhancement of the Faraday rotation for the corresponding wavelength. The experimental results are in excellent agreement with the theoretical predictions.

  19. Exactly integrable analogue of a one-dimensional gravitating system

    International Nuclear Information System (INIS)

    Miller, Bruce N.; Yawn, Kenneth R.; Maier, Bill

    2005-01-01

    Exchange symmetry in acceleration partitions the configuration space of an N particle one-dimensional gravitational system (OGS) into N! equivalent cells. We take advantage of the resulting small angular separation between the forces in neighboring cells to construct a related integrable version of the system that takes the form of a central force problem in N-1 dimensions. The properties of the latter, including the construction of trajectories and possible continuum limits, are developed. Dynamical simulation is employed to compare the two models. For some initial conditions, excellent agreement is observed

  20. Acoustic and electronic properties of one-dimensional quasicrystals

    International Nuclear Information System (INIS)

    Nori, F.; Rodriguez, J.P.

    1986-01-01

    We study the acoustic and electronic properties of one-dimensional quasicrystals. Both numerical (nonperturbative) and analytical (perturbative) results are shown. The phonon and electronic spectra exhibit a self-similar hierarchy of gaps and many localized states in the gaps. We study quasiperiodic structures with any number of layers and several types of boundary conditions. We discuss the connection between our phonon model and recent experiments on quasiperiodic GaAs-AlAs superlattices. We predict the existence of many gap states localized at the surfaces

  1. Hidden symmetries in one-dimensional quantum Hamiltonians

    International Nuclear Information System (INIS)

    Curado, E.M.F.; Rego-Monteiro, M.A.; Nazareno, H.N.

    2000-11-01

    We construct a Heisenberg-like algebra for the one dimensional infinite square-well potential in quantum mechanics. The number-type and ladder operators are realized in terms of physical operators of the system as in the harmonic oscillator algebra. These physical operators are obtained with the help of variables used in a recently developed non commutative differential calculus. This square-well algebra is an example of an algebra in large class of generalized Heisenberg algebras recently constructed. This class of algebras also contains q-oscillators as a particular case. We also show here how this general algebra can address hidden symmetries present in several quantum systems. (author)

  2. Quantum quench in an atomic one-dimensional Ising chain.

    Science.gov (United States)

    Meinert, F; Mark, M J; Kirilov, E; Lauber, K; Weinmann, P; Daley, A J; Nägerl, H-C

    2013-08-02

    We study nonequilibrium dynamics for an ensemble of tilted one-dimensional atomic Bose-Hubbard chains after a sudden quench to the vicinity of the transition point of the Ising paramagnetic to antiferromagnetic quantum phase transition. The quench results in coherent oscillations for the orientation of effective Ising spins, detected via oscillations in the number of doubly occupied lattice sites. We characterize the quench by varying the system parameters. We report significant modification of the tunneling rate induced by interactions and show clear evidence for collective effects in the oscillatory response.

  3. Peierls' instability in a one-dimensional potentially metallic solid

    International Nuclear Information System (INIS)

    Valladares, A.A.; Cetina, E.A.; Sansores, L.E.

    1980-01-01

    The Peierls instability of one-dimensional potentially metallic lithium solid is investigated in the Hueckel and SCF approximations. In the Hueckel approximation Esub(F) is a monotonic increasing function of the displacement of every other atom of the lattice, whereas in the SCF approximation, where the filling of the bands is considered, Esub(F) shows the minimum predicted by Peierls. The energy gap (for the arrangement that minimizes Esub(F)) is 4.5 eV, indicating that this solid is an insulator. (author)

  4. One-dimensional radionuclide transport under time-varying conditions

    International Nuclear Information System (INIS)

    Gelbard, F.; Olague, N.E.; Longsine, D.E.

    1990-01-01

    This paper discusses new analytical and numerical solutions presented for one-dimensional radionuclide transport under time-varying fluid-flow conditions including radioactive decay. The analytical solution assumes that all radionuclides have identical retardation factors, and is limited to instantaneous releases. The numerical solution does not have these limitations, but is tested against the limiting case given for the analytical solution. Reasonable agreement between the two solutions was found. Examples are given for the transport of a three-member radionuclide chain transported over distances and flow rates comparable to those reported for Yucca Mountain, the proposed disposal site for high-level nuclear waste

  5. One-dimensional nonlinear inverse heat conduction technique

    International Nuclear Information System (INIS)

    Hills, R.G.; Hensel, E.C. Jr.

    1986-01-01

    The one-dimensional nonlinear problem of heat conduction is considered. A noniterative space-marching finite-difference algorithm is developed to estimate the surface temperature and heat flux from temperature measurements at subsurface locations. The trade-off between resolution and variance of the estimates of the surface conditions is discussed quantitatively. The inverse algorithm is stabilized through the use of digital filters applied recursively. The effect of the filters on the resolution and variance of the surface estimates is quantified. Results are presented which indicate that the technique is capable of handling noisy measurement data

  6. The quantum flux in quasis one-dimensional conductors

    International Nuclear Information System (INIS)

    Ventura, J.

    1989-01-01

    A method is presented which quantizes electromagnetic fluxes directly in flux space. It is based on the commutation law [φ B , φ E ] = i, where φ B is the magnetic flux, and φ E the longitudinal electric flux of a quasi one-dimensional conductor. The relevance of such a method for the description of the quantized Hall plateaus is discussed. In a second step, the polarization electric flux is introduced, together with a method for quantization of hybrid variables formed with pure electromagnetic fluxes plus electronic variables. (author) [pt

  7. Evaluation of one dimensional analytical models for vegetation canopies

    Science.gov (United States)

    Goel, Narendra S.; Kuusk, Andres

    1992-01-01

    The SAIL model for one-dimensional homogeneous vegetation canopies has been modified to include the specular reflectance and hot spot effects. This modified model and the Nilson-Kuusk model are evaluated by comparing the reflectances given by them against those given by a radiosity-based computer model, Diana, for a set of canopies, characterized by different leaf area index (LAI) and leaf angle distribution (LAD). It is shown that for homogeneous canopies, the analytical models are generally quite accurate in the visible region, but not in the infrared region. For architecturally realistic heterogeneous canopies of the type found in nature, these models fall short. These shortcomings are quantified.

  8. ONE-DIMENSIONAL AND TWO-DIMENSIONAL LEADERSHIP STYLES

    Directory of Open Access Journals (Sweden)

    Nikola Stefanović

    2007-06-01

    Full Text Available In order to motivate their group members to perform certain tasks, leaders use different leadership styles. These styles are based on leaders' backgrounds, knowledge, values, experiences, and expectations. The one-dimensional styles, used by many world leaders, are autocratic and democratic styles. These styles lie on the two opposite sides of the leadership spectrum. In order to precisely define the leadership styles on the spectrum between the autocratic leadership style and the democratic leadership style, leadership theory researchers use two dimensional matrices. The two-dimensional matrices define leadership styles on the basis of different parameters. By using these parameters, one can identify two-dimensional styles.

  9. Generalized entropy decay rates of one-dimensional maps

    International Nuclear Information System (INIS)

    Csordas, A.; Szepfalusy, P.

    1988-01-01

    A series of entropies, approaching the order-q Renyi's entropies when the length of orbits tends to infinity, is considered. Their scaling form is determined for chaotic one-dimensional maps. For the characteristic relaxation time a general expression is derived, and it is shown to be closely related to the eigenvalues of a generalized Frobenius-Perron operator. The case of intermittent maps is also considered, and the spectrum of relaxation time is found to reflect the phase transition at q = 1. Results of numerical experiments are also presented

  10. Entanglement entropy and complexity for one-dimensional holographic superconductors

    Science.gov (United States)

    Kord Zangeneh, Mahdi; Ong, Yen Chin; Wang, Bin

    2017-08-01

    Holographic superconductor is an important arena for holography, as it allows concrete calculations to further understand the dictionary between bulk physics and boundary physics. An important quantity of recent interest is the holographic complexity. Conflicting claims had been made in the literature concerning the behavior of holographic complexity during phase transition. We clarify this issue by performing a numerical study on one-dimensional holographic superconductor. Our investigation shows that holographic complexity does not behave in the same way as holographic entanglement entropy. Nevertheless, the universal terms of both quantities are finite and reflect the phase transition at the same critical temperature.

  11. Fragmented one dimensional man / El hombre unidimensional fragmentado

    Directory of Open Access Journals (Sweden)

    Juan Antonio Rodríguez del Pino

    2013-10-01

    Full Text Available Paraphrase the title of the famous essay by Herbert Marcuse, since the image has traditionally been generated of man, masculinity, has been one-dimensional. I mean, the man was characterized by traits and behaviors established and entrenched since ancient time, considering all other distinguishing signs as mere deviations from the normative improper. But observe that this undeniable reality, as analyzed various researchers through what has come to be called Men's studies, has proven to be a fallacy difficult to maintain throughout history and today turns into fallacious and ineffective against changes in our current existing corporate models.

  12. One-dimensional neutron imager for the Sandia Z facility.

    Science.gov (United States)

    Fittinghoff, David N; Bower, Dan E; Hollaway, James R; Jacoby, Barry A; Weiss, Paul B; Buckles, Robert A; Sammons, Timothy J; McPherson, Leroy A; Ruiz, Carlos L; Chandler, Gordon A; Torres, José A; Leeper, Ramon J; Cooper, Gary W; Nelson, Alan J

    2008-10-01

    A multiinstitution collaboration is developing a neutron imaging system for the Sandia Z facility. The initial system design is for slit aperture imaging system capable of obtaining a one-dimensional image of a 2.45 MeV source producing 5x10(12) neutrons with a resolution of 320 microm along the axial dimension of the plasma, but the design being developed can be modified for two-dimensional imaging and imaging of DT neutrons with other resolutions. This system will allow us to understand the spatial production of neutrons in the plasmas produced at the Z facility.

  13. One-dimensional computational modeling on nuclear reactor problems

    International Nuclear Information System (INIS)

    Alves Filho, Hermes; Baptista, Josue Costa; Trindade, Luiz Fernando Santos; Heringer, Juan Diego dos Santos

    2013-01-01

    In this article, we present a computational modeling, which gives us a dynamic view of some applications of Nuclear Engineering, specifically in the power distribution and the effective multiplication factor (keff) calculations. We work with one-dimensional problems of deterministic neutron transport theory, with the linearized Boltzmann equation in the discrete ordinates (SN) formulation, independent of time, with isotropic scattering and then built a software (Simulator) for modeling computational problems used in a typical calculations. The program used in the implementation of the simulator was Matlab, version 7.0. (author)

  14. Ordering phase transition in the one-dimensional Axelrod model

    Science.gov (United States)

    Vilone, D.; Vespignani, A.; Castellano, C.

    2002-12-01

    We study the one-dimensional behavior of a cellular automaton aimed at the description of the formation and evolution of cultural domains. The model exhibits a non-equilibrium transition between a phase with all the system sharing the same culture and a disordered phase of coexisting regions with different cultural features. Depending on the initial distribution of the disorder the transition occurs at different values of the model parameters. This phenomenology is qualitatively captured by a mean-field approach, which maps the dynamics into a multi-species reaction-diffusion problem.

  15. One-dimensional inverse problems of mathematical physics

    CERN Document Server

    Lavrent'ev, M M; Yakhno, V G; Schulenberger, J R

    1986-01-01

    This monograph deals with the inverse problems of determining a variable coefficient and right side for hyperbolic and parabolic equations on the basis of known solutions at fixed points of space for all times. The problems are one-dimensional in nature since the desired coefficient of the equation is a function of only one coordinate, while the desired right side is a function only of time. The authors use methods based on the spectral theory of ordinary differential operators of second order and also methods which make it possible to reduce the investigation of the inverse problems to the in

  16. One-dimensional energy flow model for poroelastic material

    International Nuclear Information System (INIS)

    Kim, Jung Soo; Kang, Yeon June

    2009-01-01

    This paper presents a one-dimensional energy flow model to investigate the energy behavior for poroelastic media coupled with acoustical media. The proposed energy flow model is expressed by an independent energy governing equation that is classified into each wave component propagating in poroelastic media. The energy governing equation is derived using the General Energetic Method (GEM). To facilitate a comparison with the classical solution based on the conventional displacement-base formulation, approximate solutions of energy density and intensity are obtained. Furthermore, the limitations and usability of the proposed energy flow model for poroelastic media are described.

  17. Lime Kiln Modeling. CFD and One-dimensional simulations

    Energy Technology Data Exchange (ETDEWEB)

    Svedin, Kristoffer; Ivarsson, Christofer; Lundborg, Rickard

    2009-03-15

    The incentives for burning alternative fuels in lime kilns are growing. An increasing demand on thorough investigations of alternative fuel impact on lime kiln performance have been recognized, and the purpose of this project has been to develop a lime kiln CFD model with the possibility to fire fuel oil and lignin. The second part of the project consists of three technical studies. Simulated data from a one-dimensional steady state program has been used to support theories on the impact of biofuels and lime mud dryness. The CFD simulations was carried out in the commercial code FLUENT. Due to difficulties with the convergence of the model the calcination reaction is not included. The model shows essential differences between the two fuels. Lignin gives a different flame shape and a longer flame length compared to fuel oil. Mainly this depends on how the fuel is fed into the combustion chamber and how much combustion air that is added as primary and secondary air. In the case of lignin combustion the required amount of air is more than in the fuel oil case. This generates more combustion gas and a different flow pattern is created. Based on the values from turbulent reaction rate for the different fuels an estimated flame length can be obtained. For fuel oil the combustion is very intense with a sharp peak in the beginning and a rapid decrease. For lignin the combustion starts not as intense as for the fuel oil case and has a smoother shape. The flame length appears to be approximately 2-3 meter longer for lignin than for fuel oil based on turbulent reaction rate in the computational simulations. The first technical study showed that there are many benefits of increasing dry solids content in the lime mud going into a kiln such as increased energy efficiency, reduced TRS, and reduced sodium in the kiln. However, data from operating kilns indicates that these benefits can be offset by increasing exit gas temperature that can limit kiln production capacity. Simulated

  18. Hydrogen peroxide stabilization in one-dimensional flow columns

    Science.gov (United States)

    Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

    2011-09-01

    Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

  19. Stopping time of a one-dimensional bounded quantum walk

    International Nuclear Information System (INIS)

    Luo Hao; Zhang Peng; Zhan Xiang; Xue Peng

    2016-01-01

    The stopping time of a one-dimensional bounded classical random walk (RW) is defined as the number of steps taken by a random walker to arrive at a fixed boundary for the first time. A quantum walk (QW) is a non-trivial generalization of RW, and has attracted a great deal of interest from researchers working in quantum physics and quantum information. In this paper, we develop a method to calculate the stopping time for a one-dimensional QW. Using our method, we further compare the properties of stopping time for QW and RW. We find that the mean value of the stopping time is the same for both of these problems. However, for short times, the probability for a walker performing a QW to arrive at the boundary is larger than that for a RW. This means that, although the mean stopping time of a quantum and classical walker are the same, the quantum walker has a greater probability of arriving at the boundary earlier than the classical walker. (paper)

  20. One-Dimensional Forward–Forward Mean-Field Games

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Diogo A., E-mail: diogo.gomes@kaust.edu.sa; Nurbekyan, Levon; Sedjro, Marc [King Abdullah University of Science and Technology (KAUST), CEMSE Division (Saudi Arabia)

    2016-12-15

    While the general theory for the terminal-initial value problem for mean-field games (MFGs) has achieved a substantial progress, the corresponding forward–forward problem is still poorly understood—even in the one-dimensional setting. Here, we consider one-dimensional forward–forward MFGs, study the existence of solutions and their long-time convergence. First, we discuss the relation between these models and systems of conservation laws. In particular, we identify new conserved quantities and study some qualitative properties of these systems. Next, we introduce a class of wave-like equations that are equivalent to forward–forward MFGs, and we derive a novel formulation as a system of conservation laws. For first-order logarithmic forward–forward MFG, we establish the existence of a global solution. Then, we consider a class of explicit solutions and show the existence of shocks. Finally, we examine parabolic forward–forward MFGs and establish the long-time convergence of the solutions.

  1. One-Dimensional Forward–Forward Mean-Field Games

    KAUST Repository

    Gomes, Diogo A.; Nurbekyan, Levon; Sedjro, Marc

    2016-01-01

    While the general theory for the terminal-initial value problem for mean-field games (MFGs) has achieved a substantial progress, the corresponding forward–forward problem is still poorly understood—even in the one-dimensional setting. Here, we consider one-dimensional forward–forward MFGs, study the existence of solutions and their long-time convergence. First, we discuss the relation between these models and systems of conservation laws. In particular, we identify new conserved quantities and study some qualitative properties of these systems. Next, we introduce a class of wave-like equations that are equivalent to forward–forward MFGs, and we derive a novel formulation as a system of conservation laws. For first-order logarithmic forward–forward MFG, we establish the existence of a global solution. Then, we consider a class of explicit solutions and show the existence of shocks. Finally, we examine parabolic forward–forward MFGs and establish the long-time convergence of the solutions.

  2. One-Dimensional Forward–Forward Mean-Field Games

    KAUST Repository

    Gomes, Diogo A.

    2016-11-01

    While the general theory for the terminal-initial value problem for mean-field games (MFGs) has achieved a substantial progress, the corresponding forward–forward problem is still poorly understood—even in the one-dimensional setting. Here, we consider one-dimensional forward–forward MFGs, study the existence of solutions and their long-time convergence. First, we discuss the relation between these models and systems of conservation laws. In particular, we identify new conserved quantities and study some qualitative properties of these systems. Next, we introduce a class of wave-like equations that are equivalent to forward–forward MFGs, and we derive a novel formulation as a system of conservation laws. For first-order logarithmic forward–forward MFG, we establish the existence of a global solution. Then, we consider a class of explicit solutions and show the existence of shocks. Finally, we examine parabolic forward–forward MFGs and establish the long-time convergence of the solutions.

  3. Interference of a thermal Tonks gas on a ring

    International Nuclear Information System (INIS)

    Das, Kunal K.; Girardeau, M.D.; Wright, E.M.

    2002-01-01

    A nonzero temperature generalization of the Fermi-Bose mapping theorem is used to study the exact quantum statistical dynamics of a one-dimensional gas of impenetrable bosons on a ring. We investigate the interference produced when an initially trapped gas localized on one side of the ring is released, split via an optical-dipole grating, and recombined on the other side of the ring. Nonzero temperature is shown not to be a limitation to obtaining high visibility fringes

  4. Resonant scattering induced thermopower in one-dimensional disordered systems

    Science.gov (United States)

    Müller, Daniel; Smit, Wilbert J.; Sigrist, Manfred

    2015-05-01

    This study analyzes thermoelectric properties of a one-dimensional random conductor which shows localization effects and simultaneously includes resonant scatterers yielding sharp conductance resonances. These sharp features give rise to a distinct behavior of the Seebeck coefficient in finite systems and incorporate the degree of localization as a means to enhance thermoelectric performance, in principle. The model for noninteracting electrons is discussed within the Landauer-Büttiker formalism such that analytical treatment is possible for a wide range of properties, if a special averaging scheme is applied. The approximations in the averaging procedure are tested with numerical evaluations showing good qualitative agreement, with some limited quantitative disagreement. The validity of low-temperature Mott's formula is determined and a good approximation is developed for the intermediate temperature range. In both regimes the intricate interplay between Anderson localization due to disorder and conductance resonances of the disorder potential is analyzed.

  5. Testing of a one dimensional model for Field II calibration

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2008-01-01

    Field II is a program for simulating ultrasound transducer fields. It is capable of calculating the emitted and pulse-echoed fields for both pulsed and continuous wave transducers. To make it fully calibrated a model of the transducer’s electro-mechanical impulse response must be included. We...... examine an adapted one dimensional transducer model originally proposed by Willatzen [9] to calibrate Field II. This model is modified to calculate the required impulse responses needed by Field II for a calibrated field pressure and external circuit current calculation. The testing has been performed...... to the calibrated Field II program for 1, 4, and 10 cycle excitations. Two parameter sets were applied for modeling, one real valued Pz27 parameter set, manufacturer supplied, and one complex valued parameter set found in literature, Alguer´o et al. [11]. The latter implicitly accounts for attenuation. Results show...

  6. One-dimensional reactor kinetics model for RETRAN

    International Nuclear Information System (INIS)

    Gose, G.C.; Peterson, C.E.; Ellis, N.L.; McClure, J.A.

    1981-01-01

    Previous versions of RETRAN have had only a point kinetics model to describe the reactor core behavior during thermal-hydraulic transients. The principal assumption in deriving the point kinetics model is that the neutron flux may be separated into a time-dependent amplitude funtion and a time-independent shape function. Certain types of transients cannot be correctly analyzed under this assumption, since proper definitions for core average quantities such as reactivity or lifetime include the inner product of the adjoint flux with the perturbed flux. A one-dimensional neutronics model has been included in a preliminary version of RETRAN-02. The ability to account for flux shape changes will permit an improved representation of the thermal and hydraulic feedback effects. This paper describes the neutronics model and discusses some of the analyses

  7. Lateral shifting in one dimensional chiral photonic crystal

    International Nuclear Information System (INIS)

    You Yuan; Chen Changyuan

    2012-01-01

    We report the lateral shifts of the transmitted waves in a one dimensional chiral photonic crystal by using the stationary-phase approach. It is revealed that two kinds of lateral shifts are observed due to the existence of cross coupling in chiral materials, which is different from what has been observed in previous non-chiral photonic crystals. Unlike the chiral slab, the positions of lateral shift peaks are closely related to the band edges of band gap characteristics of periodic structure and lateral shifts can be positive as well as negative. Besides, the lateral shifts show a strong dependence on the chiral factor, which varies the lateral shift peaks in both magnitudes and positions. These features are desirable for future device applications.

  8. Magnons in one-dimensional k-component Fibonacci structures

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C. H., E-mail: carloshocosta@hotmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Vasconcelos, M. S. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)

    2014-05-07

    We have studied the magnon transmission through of one-dimensional magnonic k-component Fibonacci structures, where k different materials are arranged in accordance with the following substitution rule: S{sub n}{sup (k)}=S{sub n−1}{sup (k)}S{sub n−k}{sup (k)} (n≥k=0,1,2,…), where S{sub n}{sup (k)} is the nth stage of the sequence. The calculations were carried out in exchange dominated regime within the framework of the Heisenberg model and taking into account the RPA approximation. We have considered multilayers composed of simple cubic spin-S Heisenberg ferromagnets, and, by using the powerful transfer-matrix method, the spin wave transmission is obtained. It is demonstrated that the transmission coefficient has a rich and interesting magnonic pass- and stop-bands structures, which depends on the frequency of magnons and the k values.

  9. One-dimensional Ising model with multispin interactions

    Science.gov (United States)

    Turban, Loïc

    2016-09-01

    We study the spin-1/2 Ising chain with multispin interactions K involving the product of m successive spins, for general values of m. Using a change of spin variables the zero-field partition function of a finite chain is obtained for free and periodic boundary conditions and we calculate the two-spin correlation function. When placed in an external field H the system is shown to be self-dual. Using another change of spin variables the one-dimensional Ising model with multispin interactions in a field is mapped onto a zero-field rectangular Ising model with first-neighbour interactions K and H. The 2D system, with size m × N/m, has the topology of a cylinder with helical BC. In the thermodynamic limit N/m\\to ∞ , m\\to ∞ , a 2D critical singularity develops on the self-duality line, \\sinh 2K\\sinh 2H=1.

  10. One-dimensional thermodynamical model for poling of ferroelectric ceramics

    International Nuclear Information System (INIS)

    Bassiouny, E.

    1990-11-01

    In this work, we use a model developed to deduce a one-dimensional model for the description of the poling of ferroelectric ceramics. This is built within the scheme of the thermodynamical theory of internal variables. The model produces both plastic and electric hysteresis effects in the form of ''plasticity'', i.e., rate-independent evolution equations for the plastic strain, and the residual electric polarization and both mechanical and electric hardenings. The influence of stresses on ferroelectric hysteresis loops through piezoelectricity and electrostriction is a natural outcome of this model. Some simple experimental methods for the determination of the material coefficients of the considered ceramics are suggested. (author). 21 refs, 3 figs

  11. NMR relaxation rate in quasi one-dimensional antiferromagnets

    Science.gov (United States)

    Capponi, Sylvain; Dupont, Maxime; Laflorencie, Nicolas; Sengupta, Pinaki; Shao, Hui; Sandvik, Anders W.

    We compare results of different numerical approaches to compute the NMR relaxation rate 1 /T1 in quasi one-dimensional (1d) antiferromagnets. In the purely 1d regime, recent numerical simulations using DMRG have provided the full crossover behavior from classical regime at high temperature to universal Tomonaga-Luttinger liquid at low-energy (in the gapless case) or activated behavior (in the gapped case). For quasi 1d models, we can use mean-field approaches to reduce the problem to a 1d one that can be studied using DMRG. But in some cases, we can also simulate the full microscopic model using quantum Monte-Carlo techniques. This allows to compute dynamical correlations in imaginary time and we will discuss recent advances to perform stochastic analytic continuation to get real frequency spectra. Finally, we connect our results to experiments on various quasi 1d materials.

  12. Quasi one dimensional transport in individual electrospun composite nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Avnon, A., E-mail: avnon@phys.fu-berlin.de; Datsyuk, V.; Trotsenko, S. [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Wang, B.; Zhou, S. [Research Center of Microperipheric Technologies, Technische Universität Berlin, TiB4/2-1, Gustav-Meyer-Allee 25, 13355 Berlin (Germany); Grabbert, N.; Ngo, H.-D. [Microsystem Engineering (FB I), University of Applied Sciences, Wilhelminenhofstr. 74 (C 525), 12459 Berlin (Germany)

    2014-01-15

    We present results of transport measurements of individual suspended electrospun nanofibers Poly(methyl methacrylate)-multiwalled carbon nanotubes. The nanofiber is comprised of highly aligned consecutive multiwalled carbon nanotubes. We have confirmed that at the range temperature from room temperature down to ∼60 K, the conductance behaves as power-law of temperature with an exponent of α ∼ 2.9−10.2. The current also behaves as power law of voltage with an exponent of β ∼ 2.3−8.6. The power-law behavior is a footprint for one dimensional transport. The possible models of this confined system are discussed. Using the model of Luttinger liquid states in series, we calculated the exponent for tunneling into the bulk of a single multiwalled carbon nanotube α{sub bulk} ∼ 0.06 which agrees with theoretical predictions.

  13. One-dimensional disk model simulation for klystron design

    International Nuclear Information System (INIS)

    Yonezawa, H.; Okazaki, Y.

    1984-05-01

    In 1982, one of the authors (Okazaki), of Toshiba Corporation, wrote a one-dimensional, rigid-disk model computer program to serve as a reliable design tool for the 150 MW klystron development project. This is an introductory note for the users of this program. While reviewing the so-called disk programs presently available, hypotheses such as gridded interaction gaps, a linear relation between phase and position, and so on, were found. These hypotheses bring serious limitations and uncertainties into the computational results. JPNDISK was developed to eliminate these defects, to follow the equations of motion as rigorously as possible, and to obtain self-consistent solutions for the gap voltages and the electron motion. Although some inaccuracy may be present in the relativistic region, JPNDISK, in its present form, seems a most suitable tool for klystron design; it is both easy and inexpensive to use

  14. One-dimensional reduction of viscous jets. II. Applications

    Science.gov (United States)

    Pitrou, Cyril

    2018-04-01

    In a companion paper [Phys. Rev. E 97, 043115 (2018), 10.1103/PhysRevE.97.043115], a formalism allowing to describe viscous fibers as one-dimensional objects was developed. We apply it to the special case of a viscous fluid torus. This allows to highlight the differences with the basic viscous string model and with its viscous rod model extension. In particular, an elliptic deformation of the torus section appears because of surface tension effects, and this cannot be described by viscous string nor viscous rod models. Furthermore, we study the Rayleigh-Plateau instability for periodic deformations around the perfect torus, and we show that the instability is not sufficient to lead to the torus breakup in several droplets before it collapses to a single spherical drop. Conversely, a rotating torus is dynamically attracted toward a stationary solution, around which the instability can develop freely and split the torus in multiple droplets.

  15. Lateral shifting in one dimensional chiral photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    You Yuan, E-mail: yctcyouyuan@163.com [School of Physics and Electronics, Yancheng Teachers University, Yancheng, 224002 Jiangsu (China); Chen Changyuan [School of Physics and Electronics, Yancheng Teachers University, Yancheng, 224002 Jiangsu (China)

    2012-07-01

    We report the lateral shifts of the transmitted waves in a one dimensional chiral photonic crystal by using the stationary-phase approach. It is revealed that two kinds of lateral shifts are observed due to the existence of cross coupling in chiral materials, which is different from what has been observed in previous non-chiral photonic crystals. Unlike the chiral slab, the positions of lateral shift peaks are closely related to the band edges of band gap characteristics of periodic structure and lateral shifts can be positive as well as negative. Besides, the lateral shifts show a strong dependence on the chiral factor, which varies the lateral shift peaks in both magnitudes and positions. These features are desirable for future device applications.

  16. One-Dimensional Time to Explosion (Thermal Sensitivity) of ANPZ

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hust, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McClelland, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gresshoff, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-12

    Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the recent ODTX experimental data and modeling results for 2,6-diamino-3,5-dintropyrazine (ANPZ).

  17. Dynamics of an impurity in a one-dimensional lattice

    International Nuclear Information System (INIS)

    Massel, F; Kantian, A; Giamarchi, T; Daley, A J; Törmä, P

    2013-01-01

    We study the non-equilibrium dynamics of an impurity in a harmonic trap that is kicked with a well-defined quasi-momentum, and interacts with a bath of free fermions or interacting bosons in a one-dimensional lattice configuration. Using numerical and analytical techniques we investigate the full dynamics beyond linear response, which allows us to quantitatively characterize states of the impurity in the bath for different parameter regimes. These vary from a tightly bound molecular state in a strongly interacting limit to a polaron (dressed impurity) and a free particle for weak interactions, with composite behaviour in the intermediate regime. These dynamics and different parameter regimes should be readily realizable in systems of cold atoms in optical lattices. (paper)

  18. The transmission probability method in one-dimensional cylindrical geometry

    International Nuclear Information System (INIS)

    Rubin, I.E.

    1983-01-01

    The collision probability method widely used in solving the problems of neutron transpopt in a reactor cell is reliable for simple cells with small number of zones. The increase of the number of zones and also taking into account the anisotropy of scattering greatly increase the scope of calculations. In order to reduce the time of calculation the transmission probability method is suggested to be used for flux calculation in one-dimensional cylindrical geometry taking into account the scattering anisotropy. The efficiency of the suggested method is verified using the one-group calculations for cylindrical cells. The use of the transmission probability method allows to present completely angular and spatial dependences is neutrons distributions without the increase in the scope of calculations. The method is especially effective in solving the multi-group problems

  19. Piezoelectric transducer vibrations in a one-dimensional approximation

    CERN Document Server

    Hilke, H J

    1973-01-01

    The theory of piezoelectric transducer vibrations, which may be treated as one-dimensional, is developed in detail for thin discs vibrating in a pure thickness extensional mode. An effort has been made to obtain relations of general validity, which include losses, and which are in a simple explicit form convenient for practical calculations. The behaviour of transducers is discussed with special attention to their characteristics at the two fundamental frequencies, the so-called parallel and series resonances. Several peculiarities occur when transducers are coupled to media with considerably different acoustic impedances. These peculiarities are discussed and illustrated by numerical results for quartz and PZT 4 piezoelectric discs radiating into water, air and liquid hydrogen. The application of the theory to different types of vibrations is briefly illustrated for thin bars vibrating longitudinally. Short discussions are included on compound transducer systems, and on the properties of thin discs as receiv...

  20. Experiment and simulation on one-dimensional plasma photonic crystals

    International Nuclear Information System (INIS)

    Zhang, Lin; Ouyang, Ji-Ting

    2014-01-01

    The transmission characteristics of microwaves passing through one-dimensional plasma photonic crystals (PPCs) have been investigated by experiment and simulation. The PPCs were formed by a series of discharge tubes filled with argon at 5 Torr that the plasma density in tubes can be varied by adjusting the discharge current. The transmittance of X-band microwaves through the crystal structure was measured under different discharge currents and geometrical parameters. The finite-different time-domain method was employed to analyze the detailed properties of the microwaves propagation. The results show that there exist bandgaps when the plasma is turned on. The properties of bandgaps depend on the plasma density and the geometrical parameters of the PPCs structure. The PPCs can perform as dynamical band-stop filter to control the transmission of microwaves within a wide frequency range

  1. Analytical models of optical response in one-dimensional semiconductors

    International Nuclear Information System (INIS)

    Pedersen, Thomas Garm

    2015-01-01

    The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron–hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed. - Highlights: • Optical response of one-dimensional semiconductors including excitons. • Analytical model of excitonic Franz–Keldysh effect. • Computation of optical response of impurity-localized excitons

  2. SUSY-hierarchy of one-dimensional reflectionless potentials

    CERN Document Server

    Maydanyuk, Sergei P

    2004-01-01

    A class of one-dimensional reflectionless potentials, an absolute transparency of which is concerned with their belonging to one SUSY-hierarchy with a constant potential, is studied. An approach for determination of a general form of the reflectionless potential on the basis of construction of such a hierarchy by the recurrent method is proposed. A general form of interdependence between superpotentials with neighboring numbers of this hierarchy, opening a possibility to find new reflectionless potentials, have a simple analytical view and are expressed through finite number of elementary functions (unlike some reflectionless potentials, which are constructed on the basis of soliton solutions or are shape invariant in one or many steps with involving scaling of parameters, and are expressed through series), is obtained. An analysis of absolute transparency existence for the potential which has the inverse power dependence on space coordinate (and here tunneling is possible), i.e. which has the form $V(x) = \\p...

  3. Strongly-Refractive One-Dimensional Photonic Crystal Prisms

    Science.gov (United States)

    Ting, David Z. (Inventor)

    2004-01-01

    One-dimensional (1D) photonic crystal prisms can separate a beam of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a ID photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1 D photonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The ID photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.

  4. Well-posedness of one-dimensional Korteweg models

    Directory of Open Access Journals (Sweden)

    Sylvie Benzoni-Gavage

    2006-05-01

    Full Text Available We investigate the initial-value problem for one-dimensional compressible fluids endowed with internal capillarity. We focus on the isothermal inviscid case with variable capillarity. The resulting equations for the density and the velocity, consisting of the mass conservation law and the momentum conservation with Korteweg stress, are a system of third order nonlinear dispersive partial differential equations. Additionally, this system is Hamiltonian and admits travelling solutions, representing propagating phase boundaries with internal structure. By change of unknown, it roughly reduces to a quasilinear Schrodinger equation. This new formulation enables us to prove local well-posedness for smooth perturbations of travelling profiles and almost-global existence for small enough perturbations. A blow-up criterion is also derived.

  5. A Reduced Order, One Dimensional Model of Joint Response

    Energy Technology Data Exchange (ETDEWEB)

    DOHNER,JEFFREY L.

    2000-11-06

    As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.

  6. Topologically protected states in one-dimensional systems

    CERN Document Server

    Fefferman, C L; Weinstein, M I

    2017-01-01

    The authors study a class of periodic Schrödinger operators, which in distinguished cases can be proved to have linear band-crossings or "Dirac points". They then show that the introduction of an "edge", via adiabatic modulation of these periodic potentials by a domain wall, results in the bifurcation of spatially localized "edge states". These bound states are associated with the topologically protected zero-energy mode of an asymptotic one-dimensional Dirac operator. The authors' model captures many aspects of the phenomenon of topologically protected edge states for two-dimensional bulk structures such as the honeycomb structure of graphene. The states the authors construct can be realized as highly robust TM-electromagnetic modes for a class of photonic waveguides with a phase-defect.

  7. A one-dimensional ice structure built from pentagons

    Science.gov (United States)

    Carrasco, Javier; Michaelides, Angelos

    2010-03-01

    Heterogeneous nucleation of water plays a key role in fields as diverse as atmospheric chemistry, astrophysics, and biology. Ice nucleation on metal surfaces offers an opportunity to watch this process unfold, providing a molecular-scale description at a well-defined, planar interface. We discuss a density-functional theory study on a metal surface specifically designed to understand such phenomena. Together with our colleges at the University of Liverpool, we found that the nanometer wide water-ice chains experimentally observed to nucleate and grow on Cu(110) are built from a face sharing arrangement of water pentagons [1]. The novel one-dimensional pentagon structure maximizes the water-metal bonding whilst simultaneously maintaining a strong hydrogen bonding network. These results reveal an unanticipated structural adaptability of water-ice films, demonstrating that the presence of the substrate can be sufficient to favor non-conventional structural units. [4pt] [1] J. Carrasco et al., Nature Mater. 8, 427 (2009).

  8. One-dimensional plasma photonic crystals with sinusoidal densities

    International Nuclear Information System (INIS)

    Qi, L.; Shang, L.; Zhang, S.

    2014-01-01

    Properties of electromagnetic waves with normal and oblique incidence have been studied for one-dimensional plasma layers with sinusoidal densities. Wave transmittance as a function of wave frequency exhibits photonic band gaps characteristic of photonic crystals. For periodic structures, increasing collision frequency is demonstrated to lead to greater absorption, increasing the modulation factor enlarges the gap width, and increasing incidence angle can change the gap locations of the two polarizations. If a defect layer is introduced by inserting a new plasma layer in the center, a defect mode may appear within the gap. Periodic number, collision frequency, and modulation factor can affect magnitude of the defect mode. The incidence angle enables the frequency to be tuned. Defect layer thickness affects both frequency and number of defect modes. These results may provide theoretical guidance in designing tunable narrow-band filters

  9. Relativistic collective diffusion in one-dimensional systems

    Science.gov (United States)

    Lin, Gui-Wu; Lam, Yu-Yiu; Zheng, Dong-Qin; Zhong, Wei-Rong

    2018-05-01

    The relativistic collective diffusion in one-dimensional molecular system is investigated through nonequilibrium molecular dynamics with Monte Carlo methods. We have proposed the relationship among the speed, the temperature, the density distribution and the collective diffusion coefficient of particles in a relativistic moving system. It is found that the relativistic speed of the system has no effect on the temperature, but the collective diffusion coefficient decreases to zero as the velocity of the system approaches to the speed of light. The collective diffusion coefficient is modified as D‧ = D(1 ‑w2 c2 )3 2 for satisfying the relativistic circumstances. The present results may contribute to the understanding of the behavior of the particles transport diffusion in a high speed system, as well as enlighten the study of biological metabolism at relativistic high speed situation.

  10. Asymmetrically doped one-dimensional trans-polymers

    International Nuclear Information System (INIS)

    Caldas, Heron

    2009-01-01

    More than 30 years ago [H. Shirakawa, E.J. Louis, A.G. MacDiarmid, C.K. Chiang, A.J. Heeger, J. Chem. Soc. Chem. Comm. 578 (1977); S. Etemad, A.J. Heeger, Ann. Rev. Phys. Chem. 33 (1982) 443] it was discovered that doped trans-polyacetylene (CH) x , a one-dimensional (1D) conjugated polymer, exhibits electrical conductivity. In this work we show that an asymmetrically doped 1D trans-polymer has non-conventional properties, as compared to symmetrically doped systems. Depending on the level of asymmetry between the chemical potentials of the two involved fermionic species, the polymer can be in a partially or fully spin polarized state. Some possible experimental consequences of doped 1D trans-polymers used as 1D organic polarized conductors are discussed.

  11. Explicit Solutions for One-Dimensional Mean-Field Games

    KAUST Repository

    Prazeres, Mariana

    2017-04-05

    In this thesis, we consider stationary one-dimensional mean-field games (MFGs) with or without congestion. Our aim is to understand the qualitative features of these games through the analysis of explicit solutions. We are particularly interested in MFGs with a nonmonotonic behavior, which corresponds to situations where agents tend to aggregate. First, we derive the MFG equations from control theory. Then, we compute explicit solutions using the current formulation and examine their behavior. Finally, we represent the solutions and analyze the results. This thesis main contributions are the following: First, we develop the current method to solve MFG explicitly. Second, we analyze in detail non-monotonic MFGs and discover new phenomena: non-uniqueness, discontinuous solutions, empty regions and unhappiness traps. Finally, we address several regularization procedures and examine the stability of MFGs.

  12. Charge and spin separation in one-dimensional systems

    International Nuclear Information System (INIS)

    Balseiro, C.A.; Jagla, E.A.; Hallberg, K.

    1995-01-01

    In this article we discuss charge and spin separation and quantum interference in one-dimensional models. After a short introduction we briefly present the Hubbard and Luttinger models and discuss some of the known exact results. We study numerically the charge and spin separation in the Hubbard model. The time evolution of a wave packet is obtained and the charge and spin densities are evaluated for different times. The charge and spin wave packets propagate with different velocities. The results are interpreted in terms of the Bethe-ansatz solution. In section IV we study the effect of charge and spin separation on the quantum interference in a Aharonov-Bohm experiment. By calculating the one-particle propagators of the Luttinger model for a mesoscopic ring with a magnetic field we calculate the Aharonov-Bohm conductance. The conductance oscillates with the magnetic field with a characteristic frequency that depends on the charge and spin velocities. (author)

  13. One-dimensional central-force problem, including radiation reaction

    International Nuclear Information System (INIS)

    Kasher, J.C.

    1976-01-01

    Two equal masses of equal charge magnitude (either attractive or repulsive) are held a certain distance apart for their entire past history. AT t = 0 one of them is either started from rest or given an initial velocity toward or away from the other charge. When the Dirac radiation-reaction force is included in the force equation, our Taylor-series numerical calculations lead to two types of nonphysical results for both the attractive and repulsive cases. In the attractive case, the moving charge either stops and moves back out to infinity, or violates energy conservation as it nears collision with the fixed charge. For the repulsive charges, the moving particle either eventually approaches and collides with the fixed one, or violates energy conservation as it goes out to infinity. These results lead us to conclude that the Lorentz-Dirac equation is not valid for the one-dimensional central-force problem

  14. Periodic transmission peak splitting in one dimensional disordered photonic structures

    Science.gov (United States)

    Kriegel, Ilka; Scotognella, Francesco

    2016-08-01

    In the present paper we present ways to modulate the periodic transmission peaks arising in disordered one dimensional photonic structures with hundreds of layers. Disordered structures in which the optical length nd (n is the refractive index and d the layer thickness) is the same for each layer show regular peaks in their transmission spectra. A proper variation of the optical length of the layers leads to a splitting of the transmission peaks. Notably, the variation of the occurrence of high and low refractive index layers, gives a tool to tune also the width of the peaks. These results are of highest interest for optical application, such as light filtering, where the manifold of parameters allows a precise design of the spectral transmission ranges.

  15. REVIEW One-Dimensional Dynamical Modeling of Earthquakes: A Review

    Directory of Open Access Journals (Sweden)

    Jeen-Hwa Wang

    2008-01-01

    Full Text Available Studies of the power-law relations of seismicity and earthquake source parameters based on the one-dimensional (1-D Burridge-Knopoff¡¦s (BK dynamical lattice model, especially those studies conducted by Taiwan¡¦s scientists, are reviewed in this article. In general, velocity- and/or state-dependent friction is considered to control faulting. A uniform distribution of breaking strengths (i.e., the static friction strength is taken into account in some studies, and inhomogeneous distributions in others. The scaling relations in these studies include: Omori¡¦s law, the magnitude-frequency or energy-frequency relation, the relation between source duration time and seismic moment, the relation between rupture length and seismic moment, the frequency-length relation, and the source power spectra. The main parameters of the one-dimensional (1-D Burridge-Knopoff¡¦s (BK dynamical lattice model include: the decreasing rate (r of dynamic friction strength with sliding velocity; the type and degree of heterogeneous distribution of the breaking strengths, the stiffness ratio (i.e., the ratio between the stiffness of the coil spring connecting two mass elements and that of the leaf spring linking a mass element and the moving plate; the frictional drop ratio of the minimum dynamic friction strength to the breaking strength; and the maximum breaking strength. For some authors, the distribution of the breaking strengths was considered to be a fractal function. Hence, the fractal dimension of such a distribution is also a significant parameter. Comparison between observed scaling laws and simulation results shows that the 1-D BK dynamical lattice model acceptably approaches fault dynamics.

  16. One-dimensional reduction of viscous jets. I. Theory

    Science.gov (United States)

    Pitrou, Cyril

    2018-04-01

    We build a general formalism to describe thin viscous jets as one-dimensional objects with an internal structure. We present in full generality the steps needed to describe the viscous jets around their central line, and we argue that the Taylor expansion of all fields around that line is conveniently expressed in terms of symmetric trace-free tensors living in the two dimensions of the fiber sections. We recover the standard results of axisymmetric jets and we report the first and second corrections to the lowest order description, also allowing for a rotational component around the axis of symmetry. When applied to generally curved fibers, the lowest order description corresponds to a viscous string model whose sections are circular. However, when including the first corrections, we find that curved jets generically develop elliptic sections. Several subtle effects imply that the first corrections cannot be described by a rod model since it amounts to selectively discard some corrections. However, in a fast rotating frame, we find that the dominant effects induced by inertial and Coriolis forces should be correctly described by rod models. For completeness, we also recover the constitutive relations for forces and torques in rod models and exhibit a missing term in the lowest order expression of viscous torque. Given that our method is based on tensors, the complexity of all computations has been beaten down by using an appropriate tensor algebra package such as xAct, allowing us to obtain a one-dimensional description of curved viscous jets with all the first order corrections consistently included. Finally, we find a description for straight fibers with elliptic sections as a special case of these results, and recover that ellipticity is dynamically damped by surface tension. An application to toroidal viscous fibers is presented in the companion paper [Pitrou, Phys. Rev. E 97, 043116 (2018), 10.1103/PhysRevE.97.043116].

  17. Inflation of the early cold Universe filled with a nonlinear scalar field and a nonideal relativistic Fermi gas

    Energy Technology Data Exchange (ETDEWEB)

    Pashitskii, E. A., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I., E-mail: pentegov@iop.kiev.ua [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

    2017-03-15

    We consider a possible scenario for the evolution of the early cold Universe born from a fairly large quantum fluctuation in a vacuum with a size a{sub 0} ≫ l{sub P} (where l{sub P} is the Planck length) and filled with both a nonlinear scalar field φ, whose potential energy density U(φ) determines the vacuum energy density λ, and a nonideal Fermi gas with short-range repulsion between particles, whose equation of state is characterized by the ratio of pressure P(n{sub F}) to energy density ε(n{sub F}) dependent on the number density of fermions n{sub F}. As the early Universe expands, the dimensionless quantity ν(n{sub F}) = P(n{sub F})/ε(n{sub F}) decreases with decreasing n{sub F} from its maximum value ν{sub max} = 1 for n{sub F} → ∞ to zero for n{sub F} → 0. The interaction of the scalar and gravitational fields, which is characterized by a dimensionless constant ξ, is proportional to the scalar curvature of four-dimensional space R = κ[3P(n{sub F})–ε(n{sub F})–4λ] (where κ is Einstein’s gravitational constant), and contains terms both quadratic and linear in φ. As a result, the expanding early Universe reaches the point of first-order phase transition in a finite time interval at critical values of the scalar curvature R = R{sub c} =–μ{sup 2}/ξ and radius a{sub c} ≫ a{sub 0}. Thereafter, the early closed Universe “rolls down” from the flat inflection point of the potential U(φ) to the zero potential minimum in a finite time. The release of the total potential energy of the scalar field in the entire volume of the expanding Universe as it “rolls down” must be accompanied by the production of a large number of massive particles and antiparticles of various kinds, whose annihilation plays the role of the Big Bang. We also discuss the fundamental nature of Newton’ gravitational constant G{sub N}.

  18. Inflation of the early cold Universe filled with a nonlinear scalar field and a nonideal relativistic Fermi gas

    International Nuclear Information System (INIS)

    Pashitskii, E. A.; Pentegov, V. I.

    2017-01-01

    We consider a possible scenario for the evolution of the early cold Universe born from a fairly large quantum fluctuation in a vacuum with a size a_0 ≫ l_P (where l_P is the Planck length) and filled with both a nonlinear scalar field φ, whose potential energy density U(φ) determines the vacuum energy density λ, and a nonideal Fermi gas with short-range repulsion between particles, whose equation of state is characterized by the ratio of pressure P(n_F) to energy density ε(n_F) dependent on the number density of fermions n_F. As the early Universe expands, the dimensionless quantity ν(n_F) = P(n_F)/ε(n_F) decreases with decreasing n_F from its maximum value ν_m_a_x = 1 for n_F → ∞ to zero for n_F → 0. The interaction of the scalar and gravitational fields, which is characterized by a dimensionless constant ξ, is proportional to the scalar curvature of four-dimensional space R = κ[3P(n_F)–ε(n_F)–4λ] (where κ is Einstein’s gravitational constant), and contains terms both quadratic and linear in φ. As a result, the expanding early Universe reaches the point of first-order phase transition in a finite time interval at critical values of the scalar curvature R = R_c =–μ"2/ξ and radius a_c ≫ a_0. Thereafter, the early closed Universe “rolls down” from the flat inflection point of the potential U(φ) to the zero potential minimum in a finite time. The release of the total potential energy of the scalar field in the entire volume of the expanding Universe as it “rolls down” must be accompanied by the production of a large number of massive particles and antiparticles of various kinds, whose annihilation plays the role of the Big Bang. We also discuss the fundamental nature of Newton’ gravitational constant G_N.

  19. Effects of weak localization in quasi-one-dimensional electronic system over liquid helium

    CERN Document Server

    Kovdrya, Y Z; Gladchenko, S P

    2001-01-01

    One measured rho sub x sub x magnetoresistance of a quasi-one-dimensional electronic system over liquid helium within gas scattering range (1.3-2.0 K temperature range). It is shown that with increase of magnetic field the magnetoresistance is reduced at first and them upon passing over minimum it begins to increase from rho sub x sub x approx B sup 2 law. One anticipated that the negative magnetoresistance detected in the course of experiments resulted from the effects of weak localization. The experiment results are in qualitative conformity with the theoretical model describing processes of weak localization in single-dimensional nondegenerate electronic systems

  20. Some application of the model of partition points on a one-dimensional lattice

    International Nuclear Information System (INIS)

    Mejdani, R.

    1991-07-01

    We have shown that by using a model of the gas of partition points on one-dimensional lattice, we can find some results about the enzyme kinetics or the average domain-size, which we have obtained before by using a correlated Walks' theory or a probabilistic (combinatoric) way. We have discussed also the problem related with the spread of an infection of disease and the stochastic model of partition points. We think that this model, as a very simple model and mathematically transparent, can be advantageous for other theoretical investigations in chemistry or modern biology. (author). 14 refs, 6 figs, 1 tab

  1. DNA denaturation through a model of the partition points on a one-dimensional lattice

    International Nuclear Information System (INIS)

    Mejdani, R.; Huseini, H.

    1994-08-01

    We have shown that by using a model of the partition points gas on a one-dimensional lattice, we can study, besides the saturation curves obtained before for the enzyme kinetics, also the denaturation process, i.e. the breaking of the hydrogen bonds connecting the two strands, under treatment by heat of DNA. We think that this model, as a very simple model and mathematically transparent, can be advantageous for pedagogic goals or other theoretical investigations in chemistry or modern biology. (author). 29 refs, 4 figs

  2. A one-dimensional collisional model for plasma-immersion ion implantation

    International Nuclear Information System (INIS)

    Vahedi, V.; Lieberman, M.A.; Alves, M.V.; Verboncoeur, J.P.; Birdsall, C.K.

    1991-01-01

    Plasma-immersion ion implantation (also known as plasma-source ion implantation) is a process in which a target is immersed in a plasma and a series of large negative-voltage pulses are applied to it to extract ions from the plasma and implant them into the target. A general one-dimensional model is developed to study this process in different coordinate systems for the case in which the pressure of the neutral gas is large enough that the ion motion in the sheath can be assumed to be highly collisional

  3. Multi-gas interaction modeling on decorated semiconductor interfaces: A novel Fermi distribution-based response isotherm and the inverse hard/soft acid/base concept

    Science.gov (United States)

    Laminack, William; Gole, James

    2015-12-01

    A unique MEMS/NEMS approach is presented for the modeling of a detection platform for mixed gas interactions. Mixed gas analytes interact with nanostructured decorating metal oxide island sites supported on a microporous silicon substrate. The Inverse Hard/Soft acid/base (IHSAB) concept is used to assess a diversity of conductometric responses for mixed gas interactions as a function of these nanostructured metal oxides. The analyte conductometric responses are well represented using a combination diffusion/absorption-based model for multi-gas interactions where a newly developed response absorption isotherm, based on the Fermi distribution function is applied. A further coupling of this model with the IHSAB concept describes the considerations in modeling of multi-gas mixed analyte-interface, and analyte-analyte interactions. Taking into account the molecular electronic interaction of both the analytes with each other and an extrinsic semiconductor interface we demonstrate how the presence of one gas can enhance or diminish the reversible interaction of a second gas with the extrinsic semiconductor interface. These concepts demonstrate important considerations in the array-based formats for multi-gas sensing and its applications.

  4. Stability of spinor Fermi gases in tight waveguides

    International Nuclear Information System (INIS)

    Campo, A. del; Muga, J. G.; Girardeau, M. D.

    2007-01-01

    The two- and three-body correlation functions of the ground state of an optically trapped ultracold spin-(1/2) Fermi gas (SFG) in a tight waveguide [one-dimensional (1D) regime] are calculated in the plane of even- and odd-wave coupling constants, assuming a 1D attractive zero-range odd-wave interaction induced by a 3D p-wave Feshbach resonance, as well as the usual repulsive zero-range even-wave interaction stemming from 3D s-wave scattering. The calculations are based on the exact mapping from the SFG to a 'Lieb-Liniger-Heisenberg' model with delta-function repulsions depending on isotropic Heisenberg spin-spin interactions, and indicate that the SFG should be stable against three-body recombination in a large region of the coupling constant plane encompassing parts of both the ferromagnetic and antiferromagnetic phases. However, the limiting case of the fermionic Tonks-Girardeau gas, a spin-aligned 1D Fermi gas with infinitely attractive p-wave interactions, is unstable in this sense. Effects due to the dipolar interaction and a Zeeman term due to a resonance-generating magnetic field do not lead to shrinkage of the region of stability of the SFG

  5. BERMUDA-1DG: a one-dimensional photon transport code

    International Nuclear Information System (INIS)

    Suzuki, Tomoo; Hasegawa, Akira; Nakashima, Hiroshi; Kaneko, Kunio.

    1984-10-01

    A one-dimensional photon transport code BERMUDA-1DG has been developed for spherical and infinite slab geometries. The purpose of development is to equip the function of gamma rays calculation for the BERMUDA code system, which was developed by 1983 only for neutron transport calculation as a preliminary version. A group constants library has been prepared for 30 nuclides, and it now consists of the 36-group total cross sections and secondary gamma ray yields by the 120-group neutron flux. For the Compton scattering, group-angle transfer matrices are accurately obtained by integrating the Klein-Nishina formula taking into account the energy and scattering angle correlation. The pair production cross sections are now calculated in the code from atomic number and midenergy of each group. To obtain angular flux distribution, the transport equation is solved in the same way as in case of neutron, using the direct integration method in a multigroup model. Both of an independent gamma ray source problem and a neutron-gamma source problem are possible to be solved. This report is written as a user's manual with a brief description of the calculational method. (author)

  6. Spin glasses and algorithm benchmarks: A one-dimensional view

    International Nuclear Information System (INIS)

    Katzgraber, H G

    2008-01-01

    Spin glasses are paradigmatic models that deliver concepts relevant for a variety of systems. However, rigorous analytical results are difficult to obtain for spin-glass models, in particular for realistic short-range models. Therefore large-scale numerical simulations are the tool of choice. Concepts and algorithms derived from the study of spin glasses have been applied to diverse fields in computer science and physics. In this work a one-dimensional long-range spin-glass model with power-law interactions is discussed. The model has the advantage over conventional systems in that by tuning the power-law exponent of the interactions the effective space dimension can be changed thus effectively allowing the study of large high-dimensional spin-glass systems to address questions as diverse as the existence of an Almeida-Thouless line, ultrametricity and chaos in short range spin glasses. Furthermore, because the range of interactions can be changed, the model is a formidable test-bed for optimization algorithms

  7. One-dimensional transient radiative transfer by lattice Boltzmann method.

    Science.gov (United States)

    Zhang, Yong; Yi, Hongliang; Tan, Heping

    2013-10-21

    The lattice Boltzmann method (LBM) is extended to solve transient radiative transfer in one-dimensional slab containing scattering media subjected to a collimated short laser irradiation. By using a fully implicit backward differencing scheme to discretize the transient term in the radiative transfer equation, a new type of lattice structure is devised. The accuracy and computational efficiency of this algorithm are examined firstly. Afterwards, effects of the medium properties such as the extinction coefficient, the scattering albedo and the anisotropy factor, and the shapes of laser pulse on time-resolved signals of transmittance and reflectance are investigated. Results of the present method are found to compare very well with the data from the literature. For an oblique incidence, the LBM results in this paper are compared with those by Monte Carlo method generated by ourselves. In addition, transient radiative transfer in a two-Layer inhomogeneous media subjected to a short square pulse irradiation is investigated. At last, the LBM is further extended to study the transient radiative transfer in homogeneous medium with a refractive index discontinuity irradiated by the short pulse laser. Several trends on the time-resolved signals different from those for refractive index of 1 (i.e. refractive-index-matched boundary) are observed and analysed.

  8. One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2016-11-01

    Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.

  9. Tunneling and resonant conductance in one-dimensional molecular structures

    International Nuclear Information System (INIS)

    Kozhushner, M.A.; Posvyanskii, V.S.; Oleynik, I.I.

    2005-01-01

    We present a theory of tunneling and resonant transitions in one-dimensional molecular systems which is based on Green's function theory of electron sub-barrier scattering off the structural units (or functional groups) of a molecular chain. We show that the many-electron effects are of paramount importance in electron transport and they are effectively treated using a formalism of sub-barrier scattering operators. The method which calculates the total scattering amplitude of the bridge molecule not only predicts the enhancement of the amplitude of tunneling transitions in course of tunneling electron transfer through onedimensional molecular structures but also allows us to interpret conductance mechanisms by calculating the bound energy spectrum of the tunneling electron, the energies being obtained as poles of the total scattering amplitude of the bridge molecule. We found that the resonant tunneling via bound states of the tunneling electron is the major mechanism of electron conductivity in relatively long organic molecules. The sub-barrier scattering technique naturally includes a description of tunneling in applied electric fields which allows us to calculate I-V curves at finite bias. The developed theory is applied to explain experimental findings such as bridge effect due to tunneling through organic molecules, and threshold versus Ohmic behavior of the conductance due to resonant electron transfer

  10. New Poisson–Boltzmann type equations: one-dimensional solutions

    International Nuclear Information System (INIS)

    Lee, Chiun-Chang; Lee, Hijin; Hyon, YunKyong; Lin, Tai-Chia; Liu, Chun

    2011-01-01

    The Poisson–Boltzmann (PB) equation is conventionally used to model the equilibrium of bulk ionic species in different media and solvents. In this paper we study a new Poisson–Boltzmann type (PB n ) equation with a small dielectric parameter ε 2 and non-local nonlinearity which takes into consideration the preservation of the total amount of each individual ion. This equation can be derived from the original Poisson–Nernst–Planck system. Under Robin-type boundary conditions with various coefficient scales, we demonstrate the asymptotic behaviours of one-dimensional solutions of PB n equations as the parameter ε approaches zero. In particular, we show that in case of electroneutrality, i.e. α = β, solutions of 1D PB n equations have a similar asymptotic behaviour as those of 1D PB equations. However, as α ≠ β (non-electroneutrality), solutions of 1D PB n equations may have blow-up behaviour which cannot be found in 1D PB equations. Such a difference between 1D PB and PB n equations can also be verified by numerical simulations

  11. Localization properties of one-dimensional electrified chains

    International Nuclear Information System (INIS)

    Ouasti, R.; Brezini, A.; Zekri, N.

    1993-08-01

    A Kronig-Penney model with a constant electric filed for a non-interacting electron is used to study the transmission properties of Anderson transition in one-dimensional (1-D) systems with disordered strengths of δ-function potentials. we examined the cases where the potential varies uniformly from O to W (barriers) or from -W to O (wells) for a given disorder W. Mainly, we observe unexpected abrupt transition at the points E + Fx = n 2 π 2 . However, these transitions are related to the small oscillations observed by Soukoulis et al. in the mixed case (wells and barriers). An interesting feature in the wells is that in the presence of a small field the states become more localized and the localization length decrease up to a minimum for a critical value F m . In the end, we have studied the effect of the disorder on the Anderson transition by the mean of the participation ratio and the localization length. (author). 27 refs, 6 figs

  12. SUSY-hierarchy of one-dimensional reflectionless potentials

    International Nuclear Information System (INIS)

    Maydanyuk, Sergei P.

    2005-01-01

    A class of one-dimensional reflectionless potentials is studied. It is found that all possible types of the reflectionless potentials can be combined into one SUSY-hierarchy with a constant potential. An approach for determination of a general form of the reflectionless potential on the basis of construction of such a hierarchy by the recurrent method is proposed. A general integral form of interdependence between superpotentials with neighboring numbers of this hierarchy, opening a possibility to find new reflectionless potentials, is found and has a simple analytical view. It is supposed that any possible type of the reflectionless potential can be expressed through finite number of elementary functions (unlike some presentations of the reflectionless potentials, which are constructed on the basis of soliton solutions or are shape invariant in one or many steps with involving scaling of parameters, and are expressed through series). An analysis of absolute transparency existence for the potential which has the inverse power dependence on space coordinate (and here tunneling is possible), i.e., which has the form V (x) = ± α/ vertical bar x-x 0 vertical bar n (where α and x 0 are constants, n is natural number), is fulfilled. It is shown that such a potential can be reflectionless at n = 2 only. A SUSY-hierarchy of the inverse power reflectionless potentials is constructed. Isospectral expansions of this hierarchy are analyzed

  13. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ujwal K. Thakur

    2017-04-01

    Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

  14. Periodic solutions for one dimensional wave equation with bounded nonlinearity

    Science.gov (United States)

    Ji, Shuguan

    2018-05-01

    This paper is concerned with the periodic solutions for the one dimensional nonlinear wave equation with either constant or variable coefficients. The constant coefficient model corresponds to the classical wave equation, while the variable coefficient model arises from the forced vibrations of a nonhomogeneous string and the propagation of seismic waves in nonisotropic media. For finding the periodic solutions of variable coefficient wave equation, it is usually required that the coefficient u (x) satisfies ess infηu (x) > 0 with ηu (x) = 1/2 u″/u - 1/4 (u‧/u)2, which actually excludes the classical constant coefficient model. For the case ηu (x) = 0, it is indicated to remain an open problem by Barbu and Pavel (1997) [6]. In this work, for the periods having the form T = 2p-1/q (p , q are positive integers) and some types of boundary value conditions, we find some fundamental properties for the wave operator with either constant or variable coefficients. Based on these properties, we obtain the existence of periodic solutions when the nonlinearity is monotone and bounded. Such nonlinearity may cross multiple eigenvalues of the corresponding wave operator. In particular, we do not require the condition ess infηu (x) > 0.

  15. Integral Transport Theory in One-dimensional Geometries

    Energy Technology Data Exchange (ETDEWEB)

    Carlvik, I

    1966-06-15

    A method called DIT (Discrete Integral Transport) has been developed for the numerical solution of the transport equation in one-dimensional systems. The characteristic features of the method are Gaussian integration over the coordinate as described by Kobayashi and Nishihara, and a particular scheme for the calculation of matrix elements in annular and spherical geometry that has been used for collision probabilities in earlier Flurig programmes. The paper gives a general theory including such things as anisotropic scattering and multi-pole fluxes, and it gives a brief description of the Flurig scheme. Annular geometry is treated in some detail, and corresponding formulae are given for spherical and plane geometry. There are many similarities between DIT and the method of collision probabilities. DIT is in many cases faster, because for a certain accuracy in the fluxes DIT often needs fewer space points than the method of collision probabilities needs regions. Several computer codes using DIT, both one-group and multigroup, have been written. It is anticipated that experience gained in calculations with these codes will be reported in another paper.

  16. Quantum one dimensional spin systems. Disorder and impurities

    International Nuclear Information System (INIS)

    Brunel, V.

    1999-01-01

    This thesis presents three studies that are respectively the spin-1 disordered chain, the non magnetic impurities in the spin-1/2 chain and the reaction-diffusion process. The spin-1 chain of weak disorder is performed by the Abelian bosonization and the renormalization group. This allows to take into account the competition between the disorder and the interactions and predicts the effects of various spin-1 anisotropy chain phases under many different disorders. A second work uses the non magnetic impurities as local probes of the correlations in the spin-1/2 chain. When the impurities are connected to the chain boundary, the author predicts a temperature dependence of the relaxation rate (1/T) of the nuclear spin impurities, different from the case of these impurities connected to the whole chain. The last work deals with one dimensional reaction-diffusion problem. The Jordan-Wigner transformation allows to consider a fermionic field theory that critical exponents follow from the renormalization group. (A.L.B.)

  17. One-dimensional two-phase thermal hydraulics (ENSTA course)

    International Nuclear Information System (INIS)

    Olive, J.

    1995-11-01

    This course is part of the ENSTA 3rd year thermal hydraulics program (nuclear power option). Its purpose is to provide the theoretical basis and main physical notions pertaining to two-phase flow, mainly focussed on water-steam flows. The introduction describes the physical specificities of these flows, emphasizing their complexity. The mathematical bases are then presented (partial derivative equations), leading to a one-dimensional type, simplified description. Balances drawn up for a pipe length volume are used to introduce the mass conservation. motion and energy equations for each phase. Various postulates used to simplify two-phase models are presented, culminating in homogeneous model definitions and equations, several common examples of which are given. The model is then applied to the calculation of pressure drops in two-phase flows. This involves presenting the models most frequently used to represent pressure drops by friction or due to pipe irregularities, without giving details (numerical values of parameters). This chapter terminates with a brief description of static and dynamic instabilities in two-phase flows. Finally, heat transfer conditions frequently encountered in liquid-steam flows are described, still in the context of a 1D model. This chapter notably includes reference to under-saturated boiling conditions and the various forms of DNB. The empirical heat transfer laws are not discussed in detail. Additional material is appended, some of which is in the form of corrected exercises. (author). 6 appends

  18. One-dimensional long-range percolation: A numerical study

    Science.gov (United States)

    Gori, G.; Michelangeli, M.; Defenu, N.; Trombettoni, A.

    2017-07-01

    In this paper we study bond percolation on a one-dimensional chain with power-law bond probability C /rd +σ , where r is the distance length between distinct sites and d =1 . We introduce and test an order-N Monte Carlo algorithm and we determine as a function of σ the critical value Cc at which percolation occurs. The critical exponents in the range 0 values for Cc are compared with a known exact bound, while the critical exponent ν is compared with results from mean-field theory, from an expansion around the point σ =1 and from the ɛ -expansion used with the introduction of a suitably defined effective dimension deff relating the long-range model with a short-range one in dimension deff. We finally present a formulation of our algorithm for bond percolation on general graphs, with order N efficiency on a large class of graphs including short-range percolation and translationally invariant long-range models in any spatial dimension d with σ >0 .

  19. Magnetic ordering in arrays of one-dimensional nanoparticle chains

    International Nuclear Information System (INIS)

    Serantes, D; Baldomir, D; Pereiro, M; Hernando, B; Prida, V M; Sanchez Llamazares, J L; Zhukov, A; Ilyn, M; Gonzalez, J

    2009-01-01

    The magnetic order in parallel-aligned one-dimensional (1D) chains of magnetic nanoparticles is studied using a Monte Carlo technique. If the easy anisotropy axes are collinear along the chains a macroscopic mean-field approach indicates antiferromagnetic (AFM) order even when no interparticle interactions are taken into account, which evidences that a mean-field treatment is inadequate for the study of the magnetic order in these highly anisotropic systems. From the direct microscopic analysis of the evolution of the magnetic moments, we observe spontaneous intra-chain ferromagnetic (FM)-type and inter-chain AFM-type ordering at low temperatures (although not completely regular) for the easy-axes collinear case, whereas a random distribution of the anisotropy axes leads to a sort of intra-chain AFM arrangement with no inter-chain regular order. When the magnetic anisotropy is neglected a perfectly regular intra-chain FM-like order is attained. Therefore it is shown that the magnetic anisotropy, and particularly the spatial distribution of the easy axes, is a key parameter governing the magnetic ordering type of 1D-nanoparticle chains.

  20. Validation and Comparison of One-Dimensional Ground Motion Methodologies

    International Nuclear Information System (INIS)

    B. Darragh; W. Silva; N. Gregor

    2006-01-01

    Both point- and finite-source stochastic one-dimensional ground motion models, coupled to vertically propagating equivalent-linear shear-wave site response models are validated using an extensive set of strong motion data as part of the Yucca Mountain Project. The validation and comparison exercises are presented entirely in terms of 5% damped pseudo absolute response spectra. The study consists of a quantitative analyses involving modeling nineteen well-recorded earthquakes, M 5.6 to 7.4 at over 600 sites. The sites range in distance from about 1 to about 200 km in the western US (460 km for central-eastern US). In general, this validation demonstrates that the stochastic point- and finite-source models produce accurate predictions of strong ground motions over the range of 0 to 100 km and for magnitudes M 5.0 to 7.4. The stochastic finite-source model appears to be broadband, producing near zero bias from about 0.3 Hz (low frequency limit of the analyses) to the high frequency limit of the data (100 and 25 Hz for response and Fourier amplitude spectra, respectively)

  1. Transmission properties of one-dimensional ternary plasma photonic crystals

    International Nuclear Information System (INIS)

    Shiveshwari, Laxmi; Awasthi, S. K.

    2015-01-01

    Omnidirectional photonic band gaps (PBGs) are found in one-dimensional ternary plasma photonic crystals (PPC) composed of single negative metamaterials. The band characteristics and transmission properties are investigated through the transfer matrix method. We show that the proposed structure can trap light in three-dimensional space due to the elimination of Brewster's angle transmission resonance allowing the existence of complete PBG. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material, and number of unit cells (N) for TE and TM polarizations. It is seen that PBG characteristics is apparent even in an N ≥ 2 system, which is weakly sensitive to the incident angle and completely insensitive to the polarization. Finite PPC could be used for multichannel transmission filter without introducing any defect in the geometry. We show that the locations of the multichannel transmission peaks are in the allowed band of the infinite structure. The structure can work as a single or multichannel filter by varying the number of unit cells. Binary PPC can also work as a polarization sensitive tunable filter

  2. Electroconvection in one-dimensional liquid crystal cells

    Science.gov (United States)

    Huh, Jong-Hoon

    2018-04-01

    We investigate the alternating current (ac) -driven electroconvection (EC) in one-dimensional cells (1DCs) under the in-plane switching mode. In 1DCs, defect-free EC can be realized. In the presence and absence of external multiplicative noise, the features of traveling waves (TWs), such as their Hopf frequency fH and velocity, are examined in comparison with those of conventional two-dimensional cells (2DCs) accompanying defects of EC rolls. In particular, we show that the defects significantly contribute to the features of the TWs. Additionally, owing to the defect-free EC in the 1DCs, the effects of the ac and noise fields on the TW are clarified. The ac field linearly increases fH, independent of the ac frequency f . The noise increases fH monotonically, but fH does not vary below a characteristic noise intensity VN*. In addition, soliton-like waves and unfamiliar oscillation of EC vortices in 1DCs are observed, in contrast to the localized EC (called worms) and the oscillation of EC rolls in 2DCs.

  3. 17th century treatments of one-dimensional collisions

    International Nuclear Information System (INIS)

    Goehring, G.D.

    1975-01-01

    The issue of conservation in the collisions of bodies aroused considerable interest in the period of its initial investigation. Descartes asserted that the quantity of motion, the scalar product of the mass and speed, was the quantity that was conserved. Huygens, with the aid of his relativity of motion principle, recognized that it was not Descartes' scalar quantity that was conserved, but instead another scalar quality, the product of the mass and the square of the speed, whose total remained constant. Newton discovered that Descartes' quantity was conserved if considered a vector quantity, and thereby announced the principle of conservation of momentum. Leibniz recognized the conservation of Newton's momentum, and also the conservation of vis viva, the same scalar quantity that Huygens has earlier proposed. Although recognition of the immense importance of these principles had to await further developments in physics, the original formulation of these conservation principles, resulting from the analysis of one-dimensional collisions, was completed by the end of the 17th century. (U.K.)

  4. Negative refraction angular characterization in one-dimensional photonic crystals.

    Directory of Open Access Journals (Sweden)

    Jesus Eduardo Lugo

    2011-04-01

    Full Text Available Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs.By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell's law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone.Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or for sensing applications.

  5. Negative refraction angular characterization in one-dimensional photonic crystals.

    Science.gov (United States)

    Lugo, Jesus Eduardo; Doti, Rafael; Faubert, Jocelyn

    2011-04-06

    Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity developed here. We also analytically derived the negative refraction correctness condition that gives the angular region where negative refraction occurs. By using standard photonic techniques we experimentally determined the relationship between incidence and negative refraction angles and found the negative refraction range by applying the correctness condition. In order to compare both theories with experimental results an output refraction correction was utilized. The correction uses Snell's law and an effective refractive index based on two effective dielectric constants. We found good agreement between experiment and both theories in the negative refraction zone. Since both theories and the experimental observations agreed well in the negative refraction region, we can use both negative refraction theories plus the output correction to predict negative refraction angles. This can be very useful from a practical point of view for space filtering applications such as a photonic demultiplexer or for sensing applications.

  6. One-dimensional quantum walk with a moving boundary

    International Nuclear Information System (INIS)

    Kwek, Leong Chuan; Setiawan

    2011-01-01

    Quantum walks are interesting models with potential applications to quantum algorithms and physical processes such as photosynthesis. In this paper, we study two models of one-dimensional quantum walks, namely, quantum walks with a moving absorbing wall and quantum walks with one stationary and one moving absorbing wall. For the former, we calculate numerically the survival probability, the rate of change of average position, and the rate of change of standard deviation of the particle's position in the long time limit for different wall velocities. Moreover, we also study the asymptotic behavior and the dependence of the survival probability on the initial particle's state. While for the latter, we compute the absorption probability of the right stationary wall for different velocities and initial positions of the left wall boundary. The results for these two models are compared with those obtained for the classical model. The difference between the results obtained for the quantum and classical models can be attributed to the difference in the probability distributions.

  7. Numerical modelling of random walk one-dimensional diffusion

    International Nuclear Information System (INIS)

    Vamos, C.; Suciu, N.; Peculea, M.

    1996-01-01

    The evolution of a particle which moves on a discrete one-dimensional lattice, according to a random walk low, approximates better the diffusion process smaller the steps of the spatial lattice and time are. For a sufficiently large assembly of particles one can assume that their relative frequency at lattice knots approximates the distribution function of the diffusion process. This assumption has been tested by simulating on computer two analytical solutions of the diffusion equation: the Brownian motion and the steady state linear distribution. To evaluate quantitatively the similarity between the numerical and analytical solutions we have used a norm given by the absolute value of the difference of the two solutions. Also, a diffusion coefficient at any lattice knots and moment of time has been calculated, by using the numerical solution both from the diffusion equation and the particle flux given by Fick's low. The difference between diffusion coefficient of analytical solution and the spatial lattice mean coefficient of numerical solution constitutes another quantitative indication of the similarity of the two solutions. The results obtained show that the approximation depends first on the number of particles at each knot of the spatial lattice. In conclusion, the random walk is a microscopic process of the molecular dynamics type which permits simulations precision of the diffusion processes with given precision. The numerical method presented in this work may be useful both in the analysis of real experiments and for theoretical studies

  8. Fractal geometry in an expanding, one-dimensional, Newtonian universe.

    Science.gov (United States)

    Miller, Bruce N; Rouet, Jean-Louis; Le Guirriec, Emmanuel

    2007-09-01

    Observations of galaxies over large distances reveal the possibility of a fractal distribution of their positions. The source of fractal behavior is the lack of a length scale in the two body gravitational interaction. However, even with new, larger, sample sizes from recent surveys, it is difficult to extract information concerning fractal properties with confidence. Similarly, three-dimensional N-body simulations with a billion particles only provide a thousand particles per dimension, far too small for accurate conclusions. With one-dimensional models these limitations can be overcome by carrying out simulations with on the order of a quarter of a million particles without compromising the computation of the gravitational force. Here the multifractal properties of two of these models that incorporate different features of the dynamical equations governing the evolution of a matter dominated universe are compared. For each model at least two scaling regions are identified. By employing criteria from dynamical systems theory it is shown that only one of them can be geometrically significant. The results share important similarities with galaxy observations, such as hierarchical clustering and apparent bifractal geometry. They also provide insights concerning possible constraints on length and time scales for fractal structure. They clearly demonstrate that fractal geometry evolves in the mu (position, velocity) space. The observed patterns are simply a shadow (projection) of higher-dimensional structure.

  9. MARG1D: One dimensional outer region matching data code

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Watanabe, Tomoko.

    1995-08-01

    A code MARG1D has been developed which computes outer region matching data of the one dimensional Newcomb equation. Matching data play an important role in the resistive (and non ideal) Magneto-hydrodynamic (MHD) stability analysis in a tokamak plasma. The MARG1D code computes matching data by using the boundary value method or by the eigenvalue method. Variational principles are derived for the problems to be solved and a finite element method is applied. Except for the case of marginal stability, the eigenvalue method is equivalent to the boundary value method. However, the eigenvalue method has the several advantages: it is a new method of ideal MHD stability analysis for which the marginally stable state can be identified, and it guarantees numerical stability in computing matching data close to marginal stability. We perform detailed numerical experiments for a model equation with analytical solutions and for the Newcomb equation in the m=1 mode theory. Numerical experiments show that MARG1D code gives the matching data with numerical stability and high accuracy. (author)

  10. Transmission properties of one-dimensional ternary plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shiveshwari, Laxmi [Department of Physics, K. B. Womens' s College, Hazaribagh 825 301 (India); Awasthi, S. K. [Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology, Noida 201 304 (India)

    2015-09-15

    Omnidirectional photonic band gaps (PBGs) are found in one-dimensional ternary plasma photonic crystals (PPC) composed of single negative metamaterials. The band characteristics and transmission properties are investigated through the transfer matrix method. We show that the proposed structure can trap light in three-dimensional space due to the elimination of Brewster's angle transmission resonance allowing the existence of complete PBG. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material, and number of unit cells (N) for TE and TM polarizations. It is seen that PBG characteristics is apparent even in an N ≥ 2 system, which is weakly sensitive to the incident angle and completely insensitive to the polarization. Finite PPC could be used for multichannel transmission filter without introducing any defect in the geometry. We show that the locations of the multichannel transmission peaks are in the allowed band of the infinite structure. The structure can work as a single or multichannel filter by varying the number of unit cells. Binary PPC can also work as a polarization sensitive tunable filter.

  11. One-dimensional magnetophotonic crystals with magnetooptical double layers

    International Nuclear Information System (INIS)

    Berzhansky, V. N.; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V.; Lukienko, I. N.; Kharchenko, Yu. N.; Golub, V. O.; Salyuk, O. Yu.; Belotelov, V. I.

    2016-01-01

    One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ F and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ F =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ F =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

  12. One-dimensional magnetophotonic crystals with magnetooptical double layers

    Energy Technology Data Exchange (ETDEWEB)

    Berzhansky, V. N., E-mail: v.n.berzhansky@gmail.com; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V. [V.I. Vernadsky Crimean Federal University (Russian Federation); Lukienko, I. N.; Kharchenko, Yu. N., E-mail: kharcenko@ilt.kharkov.ua [National Academy of Sciences of Ukraine, Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Golub, V. O., E-mail: v-o-golub@yahoo.com; Salyuk, O. Yu. [National Academy of Sciences of Ukraine, Institute of Magnetism (Ukraine); Belotelov, V. I., E-mail: belotelov@physics.msu.ru [Russian Quantum Center (Russian Federation)

    2016-11-15

    One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ{sub F} and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ{sub F} =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ{sub F} =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

  13. Approximate approaches to the one-dimensional finite potential well

    International Nuclear Information System (INIS)

    Singh, Shilpi; Pathak, Praveen; Singh, Vijay A

    2011-01-01

    The one-dimensional finite well is a textbook problem. We propose approximate approaches to obtain the energy levels of the well. The finite well is also encountered in semiconductor heterostructures where the carrier mass inside the well (m i ) is taken to be distinct from mass outside (m o ). A relevant parameter is the mass discontinuity ratio β = m i /m o . To correctly account for the mass discontinuity, we apply the BenDaniel-Duke boundary condition. We obtain approximate solutions for two cases: when the well is shallow and when the well is deep. We compare the approximate results with the exact results and find that higher-order approximations are quite robust. For the shallow case, the approximate solution can be expressed in terms of a dimensionless parameter σ l = 2m o V 0 L 2 /ℎ 2 (or σ = β 2 σ l for the deep case). We show that the lowest-order results are related by a duality transform. We also discuss how the energy upscales with L (E∼1/L γ ) and obtain the exponent γ. Exponent γ → 2 when the well is sufficiently deep and β → 1. The ratio of the masses dictates the physics. Our presentation is pedagogical and should be useful to students on a first course on elementary quantum mechanics or low-dimensional semiconductors.

  14. One-Dimensional Electron Transport Layers for Perovskite Solar Cells

    Science.gov (United States)

    Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

    2017-01-01

    The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

  15. Stepwise Nanopore Evolution in One-Dimensional Nanostructures

    KAUST Repository

    Choi, Jang Wook

    2010-04-14

    We report that established simple lithium (Li) ion battery cycles can be used to produce nanopores inside various useful one-dimensional (1D) nanostructures such as zinc oxide, silicon, and silver nanowires. Moreover, porosities of these 1D nanomaterials can be controlled in a stepwise manner by the number of Li-battery cycles. Subsequent pore characterization at the end of each cycle allows us to obtain detailed snapshots of the distinct pore evolution properties in each material due to their different atomic diffusion rates and types of chemical bonds. Also, this stepwise characterization led us to the first observation of pore size increases during cycling, which can be interpreted as a similar phenomenon to Ostwald ripening in analogous nanoparticle cases. Finally, we take advantage of the unique combination of nanoporosity and 1D materials and demonstrate nanoporous silicon nanowires (poSiNWs) as excellent supercapacitor (SC) electrodes in high power operations compared to existing devices with activated carbon. © 2010 American Chemical Society.

  16. Validation and Comparison of One-Dimensional Graound Motion Methodologies

    Energy Technology Data Exchange (ETDEWEB)

    B. Darragh; W. Silva; N. Gregor

    2006-06-28

    Both point- and finite-source stochastic one-dimensional ground motion models, coupled to vertically propagating equivalent-linear shear-wave site response models are validated using an extensive set of strong motion data as part of the Yucca Mountain Project. The validation and comparison exercises are presented entirely in terms of 5% damped pseudo absolute response spectra. The study consists of a quantitative analyses involving modeling nineteen well-recorded earthquakes, M 5.6 to 7.4 at over 600 sites. The sites range in distance from about 1 to about 200 km in the western US (460 km for central-eastern US). In general, this validation demonstrates that the stochastic point- and finite-source models produce accurate predictions of strong ground motions over the range of 0 to 100 km and for magnitudes M 5.0 to 7.4. The stochastic finite-source model appears to be broadband, producing near zero bias from about 0.3 Hz (low frequency limit of the analyses) to the high frequency limit of the data (100 and 25 Hz for response and Fourier amplitude spectra, respectively).

  17. Exotic superfluidity and pairing phenomena in atomic Fermi gases in mixed dimensions.

    Science.gov (United States)

    Zhang, Leifeng; Che, Yanming; Wang, Jibiao; Chen, Qijin

    2017-10-11

    Atomic Fermi gases have been an ideal platform for simulating conventional and engineering exotic physical systems owing to their multiple tunable control parameters. Here we investigate the effects of mixed dimensionality on the superfluid and pairing phenomena of a two-component ultracold atomic Fermi gas with a short-range pairing interaction, while one component is confined on a one-dimensional (1D) optical lattice whereas the other is in a homogeneous 3D continuum. We study the phase diagram and the pseudogap phenomena throughout the entire BCS-BEC crossover, using a pairing fluctuation theory. We find that the effective dimensionality of the non-interacting lattice component can evolve from quasi-3D to quasi-1D, leading to strong Fermi surface mismatch. Upon pairing, the system becomes effectively quasi-two dimensional in the BEC regime. The behavior of T c bears similarity to that of a regular 3D population imbalanced Fermi gas, but with a more drastic departure from the regular 3D balanced case, featuring both intermediate temperature superfluidity and possible pair density wave ground state. Unlike a simple 1D optical lattice case, T c in the mixed dimensions has a constant BEC asymptote.

  18. SU(N ) fermions in a one-dimensional harmonic trap

    Science.gov (United States)

    Laird, E. K.; Shi, Z.-Y.; Parish, M. M.; Levinsen, J.

    2017-09-01

    We conduct a theoretical study of SU (N ) fermions confined by a one-dimensional harmonic potential. First, we introduce a numerical approach for solving the trapped interacting few-body problem, by which one may obtain accurate energy spectra across the full range of interaction strengths. In the strong-coupling limit, we map the SU (N ) Hamiltonian to a spin-chain model. We then show that an existing, extremely accurate ansatz—derived for a Heisenberg SU(2) spin chain—is extendable to these N -component systems. Lastly, we consider balanced SU (N ) Fermi gases that have an equal number of particles in each spin state for N =2 ,3 ,4 . In the weak- and strong-coupling regimes, we find that the ground-state energies rapidly converge to their expected values in the thermodynamic limit with increasing atom number. This suggests that the many-body energetics of N -component fermions may be accurately inferred from the corresponding few-body systems of N distinguishable particles.

  19. Large-Scale Description of Interacting One-Dimensional Bose Gases: Generalized Hydrodynamics Supersedes Conventional Hydrodynamics

    Science.gov (United States)

    Doyon, Benjamin; Dubail, Jérôme; Konik, Robert; Yoshimura, Takato

    2017-11-01

    The theory of generalized hydrodynamics (GHD) was recently developed as a new tool for the study of inhomogeneous time evolution in many-body interacting systems with infinitely many conserved charges. In this Letter, we show that it supersedes the widely used conventional hydrodynamics (CHD) of one-dimensional Bose gases. We illustrate this by studying "nonlinear sound waves" emanating from initial density accumulations in the Lieb-Liniger model. We show that, at zero temperature and in the absence of shocks, GHD reduces to CHD, thus for the first time justifying its use from purely hydrodynamic principles. We show that sharp profiles, which appear in finite times in CHD, immediately dissolve into a higher hierarchy of reductions of GHD, with no sustained shock. CHD thereon fails to capture the correct hydrodynamics. We establish the correct hydrodynamic equations, which are finite-dimensional reductions of GHD characterized by multiple, disjoint Fermi seas. We further verify that at nonzero temperature, CHD fails at all nonzero times. Finally, we numerically confirm the emergence of hydrodynamics at zero temperature by comparing its predictions with a full quantum simulation performed using the NRG-TSA-abacus algorithm. The analysis is performed in the full interaction range, and is not restricted to either weak- or strong-repulsion regimes.

  20. Electrons, pseudoparticles, and quasiparticles in the one-dimensional many-electron problem

    International Nuclear Information System (INIS)

    Carmelo, J.M.; Castro Neto, A.H.

    1996-01-01

    We generalize the concept of quasiparticle for one-dimensional (1D) interacting electronic systems. The ↑ and ↓ quasiparticles recombine the pseudoparticle colors c and s (charge and spin at zero-magnetic field) and are constituted by one many-pseudoparticle topological-momentum shift and one or two pseudoparticles. These excitations cannot be separated. We consider the case of the Hubbard chain. We show that the low-energy electron-quasiparticle transformation has a singular character which justifies the perturbative and nonperturbative nature of the quantum problem in the pseudoparticle and electronic basis, respectively. This follows from the absence of zero-energy electron-quasiparticle overlap in 1D. The existence of Fermi-surface quasiparticles both in 1D and three dimensional (3D) many-electron systems suggests their existence in quantum liquids in dimensions 1 1 or whether it becomes finite as soon as we leave 1D remains an unsolved question. copyright 1996 The American Physical Society

  1. Ground-state properties of anyons in a one-dimensional lattice

    Science.gov (United States)

    Tang, Guixin; Eggert, Sebastian; Pelster, Axel

    2015-12-01

    Using the Anyon-Hubbard Hamiltonian, we analyze the ground-state properties of anyons in a one-dimensional lattice. To this end we map the hopping dynamics of correlated anyons to an occupation-dependent hopping Bose-Hubbard model using the fractional Jordan-Wigner transformation. In particular, we calculate the quasi-momentum distribution of anyons, which interpolates between Bose-Einstein and Fermi-Dirac statistics. Analytically, we apply a modified Gutzwiller mean-field approach, which goes beyond a classical one by including the influence of the fractional phase of anyons within the many-body wavefunction. Numerically, we use the density-matrix renormalization group by relying on the ansatz of matrix product states. As a result it turns out that the anyonic quasi-momentum distribution reveals both a peak-shift and an asymmetry which mainly originates from the nonlocal string property. In addition, we determine the corresponding quasi-momentum distribution of the Jordan-Wigner transformed bosons, where, in contrast to the hard-core case, we also observe an asymmetry for the soft-core case, which strongly depends on the particle number density.

  2. Hyperfine structure of the MnH X 7Sigma + state: A large gas-to-matrix shift in the Fermi contact interaction

    Science.gov (United States)

    Varberg, Thomas D.; Field, Robert W.; Merer, Anthony J.

    1990-06-01

    Sub-Doppler spectra of the A 7Π-X 7Σ+ (0,0) band of gas phase MnH near 5680 Å were recorded by intermodulated fluorescence spectroscopy. The spectra reveal hyperfine splittings arising from both the 55Mn and 1H nuclear spins. Internal hyperfine perturbations have been observed between the different spin components of the ground state at low N`. From a preliminary analysis of several rotational lines originating from the isolated and unperturbed F1(J`=3) spin component of the X 7Σ+(N`=0) level, the 55Mn Fermi contact interaction in the ground state has been measured as bF=Aiso =276(1) MHz. This value is 11% smaller than the value obtained by Weltner et al. from an electron-nuclear double resonance (ENDOR) study of MnH in an argon matrix at 4 K. This unprecedented gas-to-matrix shift in the Fermi contact parameter is discussed.

  3. Hyperfine structure of the MnH X 7Σ+ state: A large gas-to-matrix shift in the Fermi contact interaction

    International Nuclear Information System (INIS)

    Varberg, T.D.; Field, R.W.; Merer, A.J.

    1990-01-01

    Sub-Doppler spectra of the A 7 Π--X 7 Σ + (0,0) band of gas phase MnH near 5680 A were recorded by intermodulated fluorescence spectroscopy. The spectra reveal hyperfine splittings arising from both the 55 Mn and 1 H nuclear spins. Internal hyperfine perturbations have been observed between the different spin components of the ground state at low N double-prime. From a preliminary analysis of several rotational lines originating from the isolated and unperturbed F 1 (J double-prime=3) spin component of the X 7 Σ + (N double-prime=0) level, the 55 Mn Fermi contact interaction in the ground state has been measured as b F =A iso =276(1) MHz. This value is 11% smaller than the value obtained by Weltner et al. from an electron-nuclear double resonance (ENDOR) study of MnH in an argon matrix at 4 K. This unprecedented gas-to-matrix shift in the Fermi contact parameter is discussed

  4. Properties of one-dimensional anharmonic lattice solitons

    Science.gov (United States)

    Szeftel, Jacob; Laurent-Gengoux, Pascal; Ilisca, Ernest; Hebbache, Mohamed

    2000-12-01

    The existence of bell- and kink-shaped solitons moving at constant velocity while keeping a permanent profile is studied in infinite periodic monoatomic chains of arbitrary anharmonicity by taking advantage of the equation of motion being integrable with respect to solitons. A second-order, non-linear differential equation involving advanced and retarded terms must be solved, which is done by implementing a scheme based on the finite element and Newton's methods. If the potential has a harmonic limit, the asymptotic time-decay behaves exponentially and there is a dispersion relation between propagation velocity and decay time. Inversely if the potential has no harmonic limit, the asymptotic regime shows up either as a power-law or faster than exponential. Excellent agreement is achieved with Toda's model. Illustrative examples are also given for the Fermi-Pasta-Ulam and sine-Gordon potentials. Owing to integrability an effective one-body potential is worked out in each case. Lattice and continuum solitons differ markedly from one another as regards the amplitude versus propagation velocity relationship and the asymptotic time behavior. The relevance of the linear stability analysis when applied to solitons propagating in an infinite crystal is questioned. The reasons preventing solitons from arising in a diatomic lattice are discussed.

  5. Study on sensing property of one-dimensional ring mirror-defect photonic crystal

    Science.gov (United States)

    Chen, Ying; Luo, Pei; Cao, Huiying; Zhao, Zhiyong; Zhu, Qiguang

    2018-02-01

    Based on the photon localization and the photonic bandgap characteristics of photonic crystals (PCs), one-dimensional (1D) ring mirror-defect photonic crystal structure is proposed. Due to the introduction of mirror structure, a defect cavity is formed in the center of the photonic crystal, and then the resonant transmission peak can be obtained in the bandgap of transmission spectrum. The transfer matrix method is used to establish the relationship model between the resonant transmission peak and the structure parameters of the photonic crystals. Using the rectangular air gate photonic crystal structure, the dynamic monitoring of the detected gas sample parameters can be achieved from the shift of the resonant transmission peak. The simulation results show that the Q-value can attain to 1739.48 and the sensitivity can attain to 1642 nm ṡ RIU-1, which demonstrates the effectiveness of the sensing structure. The structure can provide certain theoretical reference for air pollution monitoring and gas component analysis.

  6. Interfacial Thermal Transport via One-Dimensional Atomic Junction Model

    Directory of Open Access Journals (Sweden)

    Guohuan Xiong

    2018-03-01

    Full Text Available In modern information technology, as integration density increases rapidly and the dimension of materials reduces to nanoscale, interfacial thermal transport (ITT has attracted widespread attention of scientists. This review introduces the latest theoretical development in ITT through one-dimensional (1D atomic junction model to address the thermal transport across an interface. With full consideration of the atomic structures in interfaces, people can apply the 1D atomic junction model to investigate many properties of ITT, such as interfacial (Kapitza resistance, nonlinear interface, interfacial rectification, and phonon interference, and so on. For the ballistic ITT, both the scattering boundary method (SBM and the non-equilibrium Green’s function (NEGF method can be applied, which are exact since atomic details of actual interfaces are considered. For interfacial coupling case, explicit analytical expression of transmission coefficient can be obtained and it is found that the thermal conductance maximizes at certain interfacial coupling (harmonic mean of the spring constants of the two leads and the transmission coefficient is not a monotonic decreasing function of phonon frequency. With nonlinear interaction—phonon–phonon interaction or electron–phonon interaction at interface, the NEGF method provides an efficient way to study the ITT. It is found that at weak linear interfacial coupling, the nonlinearity can improve the ITT, but it depresses the ITT in the case of strong-linear coupling. In addition, the nonlinear interfacial coupling can induce thermal rectification effect. For interfacial materials case which can be simulated by a two-junction atomic chain, phonons show interference effect, and an optimized thermal coupler can be obtained by tuning its spring constant and atomic mass.

  7. Shell-crossing in quasi-one-dimensional flow

    Science.gov (United States)

    Rampf, Cornelius; Frisch, Uriel

    2017-10-01

    Blow-up of solutions for the cosmological fluid equations, often dubbed shell-crossing or orbit crossing, denotes the breakdown of the single-stream regime of the cold-dark-matter fluid. At this instant, the velocity becomes multi-valued and the density singular. Shell-crossing is well understood in one dimension (1D), but not in higher dimensions. This paper is about quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence, the problem of the first shell-crossing, which is highly singular in Eulerian coordinates, has been desingularized by switching to Lagrangian coordinates, and can then be handled by perturbation theory. Here, all-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing, which is generically shown to be taking place earlier than for the unperturbed 1D flow. The time variable used for these statements is not the cosmic time t but the linear growth time τ ˜ t2/3. For simplicity, calculations are restricted to an Einstein-de Sitter universe in the Newtonian approximation, and tailored initial data are used. However it is straightforward to relax these limitations, if needed.

  8. Research on one-dimensional two-phase flow

    International Nuclear Information System (INIS)

    Adachi, Hiromichi

    1988-10-01

    In Part I the fundamental form of the hydrodynamic basic equations for a one-dimensional two-phase flow (two-fluid model) is described. Discussions are concentrated on the treatment of phase change inertial force terms in the equations of motion and the author's equations of motion which have a remarkable uniqueness on the following three points. (1) To express force balance of unit mass two-phase fluid instead of that of unit volume two-phase fluid. (2) To pick up the unit existing mass and the unit flowing mass as the unit mass of two-phase fluid. (3) To apply the kinetic energy principle instead of the momentum low in the evaluation of steady inertial force term. In these three, the item (1) is for excluding a part of momentum change or kinetic energy change due to mass change of the examined part of fluid, which is independent of force. The item (2) is not to introduce a phenomenological physical model into the evaluation of phase change inertial force term. And the item (3) is for correctly applying the momentum law taking into account the difference of representative velocities between the main flow fluid (vapor phase or liquid phase) and the phase change part of fluid. In Part II, characteristics of various kinds of high speed two-phase flow are clarified theoretically by the basic equations derived. It is demonstrated that the steam-water two-phase critical flow with violent flashing and the airwater two-phase critical flow without phase change can be described with fundamentally the same basic equations. Furthermore, by comparing the experimental data from the two-phase critical discharge test and the theoretical prediction, the two-phase discharge coefficient, C D , for large sharp-edged orifice is determined as the value which is not affected by the experimental facility characteristics, etc. (author)

  9. Fractal spectra in generalized Fibonacci one-dimensional magnonic quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C.H.O. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio grande do Norte, 59072-970 Natal-RN (Brazil); Vasconcelos, M.S., E-mail: manoelvasconcelos@yahoo.com.br [Escola de Ciencias e Tecnologia, Universidade Federal do Rio grande do Norte, 59072-970 Natal-RN (Brazil); Barbosa, P.H.R.; Barbosa Filho, F.F. [Departamento de Fisica, Universidade Federal do Piaui, 64049-550 Teresina-Pi (Brazil)

    2012-07-15

    In this work we carry out a theoretical analysis of the spectra of magnons in quasiperiodic magnonic crystals arranged in accordance with generalized Fibonacci sequences in the exchange regime, by using a model based on a transfer-matrix method together random-phase approximation (RPA). The generalized Fibonacci sequences are characterized by an irrational parameter {sigma}(p,q), which rules the physical properties of the system. We discussed the magnonic fractal spectra for first three generalizations, i.e., silver, bronze and nickel mean. By varying the generation number, we have found that the fragmentation process of allowed bands makes possible the emergence of new allowed magnonic bulk bands in spectra regions that were magnonic band gaps before, such as which occurs in doped semiconductor devices. This interesting property arises in one-dimensional magnonic quasicrystals fabricated in accordance to quasiperiodic sequences, without the need to introduce some deferent atomic layer or defect in the system. We also make a qualitative and quantitative investigations on these magnonic spectra by analyzing the distribution and magnitude of allowed bulk bands in function of the generalized Fibonacci number F{sub n} and as well as how they scale as a function of the number of generations of the sequences, respectively. - Highlights: Black-Right-Pointing-Pointer Quasiperiodic magnonic crystals are arranged in accordance with the generalized Fibonacci sequence. Black-Right-Pointing-Pointer Heisenberg model in exchange regime is applied. Black-Right-Pointing-Pointer We use a theoretical model based on a transfer-matrix method together random-phase approximation. Black-Right-Pointing-Pointer Fractal spectra are characterized. Black-Right-Pointing-Pointer We analyze the distribution of allowed bulk bands in function of the generalized Fibonacci number.

  10. Bose gases in one-dimensional harmonic trap

    Indian Academy of Sciences (India)

    dimensional Bose gas confined by a harmonic potential are studied using different ensemble approaches. Combining number theory methods, a new approach is presented to calculate the occupation numbers of different energy levels in ...

  11. One-Dimensional Hetero-Nanostructures for Rechargeable Batteries.

    Science.gov (United States)

    Mai, Liqiang; Sheng, Jinzhi; Xu, Lin; Tan, Shuangshuang; Meng, Jiashen

    2018-04-17

    Rechargeable batteries are regarded as one of the most practical electrochemical energy storage devices that are able to convert and store the electrical energy generated from renewable resources, and they function as the key power sources for electric vehicles and portable electronics. The ultimate goals for electrochemical energy storage devices are high power and energy density, long lifetime, and high safety. To achieve the above goals, researchers have tried to apply various morphologies of nanomaterials as the electrodes to enhance the electrochemical performance. Among them, one-dimensional (1D) materials show unique superiorities, such as cross-linked structures for external stress buffering and large draw ratios for internal stress dispersion. However, a homogeneous single-component electrode material can hardly have the characteristics of high electronic/ionic conductivity and high stability in the electrochemical environment simultaneously. Therefore, designing well-defined functional 1D hetero-nanostructures that combine the advantages and overcome the limitations of different electrochemically active materials is of great significance. This Account summarizes fabrication strategies for 1D hetero-nanostructures, including nucleation and growth, deposition, and melt-casting and electrospinning. Besides, the chemical principles for each strategy are discussed. The nucleation and growth strategy is suitable for growing and constructing 1D hetero-nanostructures of partial transition metal compounds, and the experimental conditions for this strategy are relatively accessible. Deposition is a reliable strategy to synthesize 1D hetero-nanostructures by decorating functional layers on 1D substrate materials, on the condition that the preobtained substrate materials must be stable in the following deposition process. The melt-casting strategy, in which 1D hetero-nanostructures are synthesizes via a melting and molding process, is also widely used. Additionally

  12. Bioinspired one-dimensional materials for directional liquid transport.

    Science.gov (United States)

    Ju, Jie; Zheng, Yongmei; Jiang, Lei

    2014-08-19

    One-dimensional materials (1D) capable of transporting liquid droplets directionally, such as spider silks and cactus spines, have recently been gathering scientists' attention due to their potential applications in microfluidics, textile dyeing, filtration, and smog removal. This remarkable property comes from the arrangement of the micro- and nanostructures on these organisms' surfaces, which have inspired chemists to develop methods to prepare surfaces with similar directional liquid transport ability. In this Account, we report our recent progress in understanding how this directional transport works, as well our advances in the design and fabrication of bioinspired 1D materials capable of transporting liquid droplets directionally. To begin, we first discuss some basic theories on droplet directional movement. Then, we discuss the mechanism of directional transport of water droplets on natural spider silks. Upon contact with water droplets, the spider silk undergoes what is known as a wet-rebuilt, which forms periodic spindle-knots and joints. We found that the resulting gradient of Laplace pressure and surface free energy between the spindle-knots and joints account for the cooperative driving forces to transport water droplets directionally. Next, we discuss the directional transport of water droplets on desert cactus. The integration of multilevel structures of the cactus and the resulting integration of multiple functions together allow the cactus spine to transport water droplets continuously from tip to base. Based on our studies of natural spider silks and cactus spines, we have prepared a series of artificial spider silks (A-SSs) and artificial cactus spines (A-CSs) with various methods. By changing the surface roughness and chemical compositions of the artificial spider silks' spindle-knots, or by introducing stimulus-responsive molecules, such as thermal-responsive and photoresponsive molecules, onto the spindle-knots, we can reversibly manipulate

  13. Energy Fluctuation of Ideal Fermi Gas Trapped under Generic Power Law Potential U=\\sum_{i=1}^{d} c_i\\vert x_{i}/a_{i}\\vert^{n_{i} } in d Dimensions

    Science.gov (United States)

    Mir, Mehedi Faruk; Muktadir Rahman, Md.; Dwaipayan, Debnath; Sakhawat Hossain Himel, Md.

    2016-04-01

    Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=\\sumi=1d ci \\vertxi/ai \\vert n_i has been calculated in arbitrary dimensions. Energy fluctuation is scrutinized further in the degenerate limit μ ≫ KBT with the help of Sommerfeld expansion. The dependence of energy fluctuation on dimensionality and power law potential is studied in detail. Most importantly our general result can not only exactly reproduce the recently published result regarding free and harmonically trapped ideal Fermi gas in d = 3 but also can describe the outcome for any power law potential in arbitrary dimension.

  14. Berry Fermi liquid theory

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing-Yuan, E-mail: chjy@uchicago.edu [Kadanoff Center for Theoretical Physics, University of Chicago, Chicago, IL 60637 (United States); Stanford Institute for Theoretical Physics, Stanford University, CA 94305 (United States); Son, Dam Thanh, E-mail: dtson@uchicago.edu [Kadanoff Center for Theoretical Physics, University of Chicago, Chicago, IL 60637 (United States)

    2017-02-15

    We develop an extension of the Landau Fermi liquid theory to systems of interacting fermions with non-trivial Berry curvature. We propose a kinetic equation and a constitutive relation for the electromagnetic current that together encode the linear response of such systems to external electromagnetic perturbations, to leading and next-to-leading orders in the expansion over the frequency and wave number of the perturbations. We analyze the Feynman diagrams in a large class of interacting quantum field theories and show that, after summing up all orders in perturbation theory, the current–current correlator exactly matches with the result obtained from the kinetic theory. - Highlights: • We extend Landau’s kinetic theory of Fermi liquid to incorporate Berry phase. • Berry phase effects in Fermi liquid take exactly the same form as in Fermi gas. • There is a new “emergent electric dipole” contribution to the anomalous Hall effect. • Our kinetic theory is matched to field theory to all orders in Feynman diagrams.

  15. One dimensional modeling of a diesel-CNG dual fuel engine

    Science.gov (United States)

    Azman, Putera Adam; Fawzi, Mas; Ismail, Muammar Mukhsin; Osman, Shahrul Azmir

    2017-04-01

    Some of the previous studies have shown that the use of compressed natural gas (CNG) in diesel engines potentially produce engine performance improvement and exhaust gas emission reduction, especially nitrogen oxides, unburned hydrocarbons, and carbon dioxide. On the other hand, there are other researchers who claimed that the use of CNG increases exhaust gas emissions, particularly nitrogen oxides. In this study, a one-dimensional model of a diesel-CNG dual fuel engine was made based on a 4-cylinder 2.5L common rail direct injection diesel engine. The software used is GT-Power, and it was used to analyze the engine performance and exhaust gas emissions of several diesel-CNG dual fuel blend ratios, i.e. 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50. The effect of 100%, 75%, 50% engine loads on the exhaust gas emissions were also studied. The result shows that all diesel-CNG fuel blends produces higher brake torque and brake power at engine speed of 2000-3000 rpm compared with 100% diesel. The 50:50 diesel-CNG blend produces the highest brake torque and brake power, but also has the highest brake specific fuel consumption. As a higher percentage of CNG added to the dual fuel blend, unburned hydrocarbons and carbon monoxide emission increased while carbon dioxide emission decreased. The nitrogen oxides emission concentration is generally unaffected by any change of the dual fuel ratio.

  16. One-dimensional acoustic modeling of thermoacoustic instabilities (on cd)

    NARCIS (Netherlands)

    van Kampen, J.F.; Huls, R.A.; Kok, Jacobus B.W.; van der Meer, Theodorus H.; Nilsson, A.; Boden, H.

    2003-01-01

    In this paper the acoustic stability of a premixed turbulent natural gas flame confined in a combustor is investigated. Specifically when the flame is operated in a lean premixed mode, the thermoacoustic system is known to exhibit instabilities. These arise from a feedback mechanism between the

  17. Spinons, Solitons, and Breathers in Quasi-One-Dimensional Magnets

    Science.gov (United States)

    Broholm, Collin

    2006-03-01

    By scattering neutrons from coordination polymer magnets, we contrast the effects of a uniform and a staggered magnetic field on the quantum critical state of a spin-1/2 chain. In a partially magnetized state of copper pyrazine dinitrate (CuPzN) we find bounded spectral continua indicating that neutrons scatter from spin-1/2 quasi-particle pairs [1]. The complex boundaries including an incommensurate soft spot result from a field induced shift in the Fermi points for these quasi-particles. The measurements indicate that the magnetized state of CuPzN remains quantum critical. Copper benzoate [2] and CuCl2^.2(dimethylsulfoxide) (CDC) [3] differ from CuPzN in that there are two spins per unit cell along the spin chain. Rather than continuous spectra, we find resolution limited gapped excitations when these materials are subject to high fields. So with two spins per unit cell, an applied field can drive the spin-1/2 chain away from criticality. The explanation for this effect was provided by Affleck and Oshikawa. The alternating coordination environment induces a transverse staggered field and spinon binding. The quantum sine-Gordon model is the relevant low energy field theory and it predicts soliton and breather excitations at specific energies and wave vectors that we compare to the experiments. We shall also compare a complete measurement of the dynamic spin correlation function for CDC in a field to exact diagonalization results for a spin-1/2 chain with a staggered and uniform magnetic field [4]. [1] M. B. Stone, D. H. Reich, C. Broholm, K. Lefmann, C. Rischel, C. P. Landee, and M. M. Turnbull, Phys. Rev. Lett. 91, 037205 (2003). [2] M. Kenzelmann, Y. Chien, C. Broholm, D. H. Reich, and Y. Qiu, Phys. Rev. Lett. 93, 017204 (2004). [3] D. C. Dender, P. R. Hammar, Daniel H. Reich, C. Broholm, and G. Aeppli, Phys. Rev. Lett. 79, 1750 (1997). [4] M. Kenzelmann, C. D. Batista, Y. Chen, C. Broholm, D. H. Reich, S. Park, and Y. Qiu, Phys. Rev. B 71, 094411 (2005).

  18. Ordering kinetics in quasi-one-dimensional Ising-like systems

    International Nuclear Information System (INIS)

    Mueller, M.; Paul, W.

    1993-01-01

    Results are presented of a Monte Carlo simulation of the kinetics of ordering in the two-dimensional nearest-neighbor Ising model in an L x M geometry with two free boundaries of length M much-gt L. This model can be viewed as representing an adsorbant on a stepped surface with mean terrace width L. The authors follow the ordering kinetics after quenches to temperatures 0.25 ≤T/T c ≤1 starting from a random initial configuration at a coverage of Θ=0.5 in the corresponding lattice gas picture. The systems evolve in time according to a Glauber kinetics with nonconserved order parameter. The equilibrium structure is given by a one-dimensional sequence of ordered domains. The ordering process evolves from a short initial two-dimensional ordering process through a crossover region to a quasi-one-dimensional behavior. The whole process is diffusive (inverse half-width of the structure factor peak 1/Δq parallel ∝ √t), in contrast to a model proposed by Kawasaki et al., where an intermediate logarithmic growth law is expected. All results are completely describable in the picture of an annihilating random walk (ARW) of domain walls. 36 refs., 16 figs

  19. BALDUR: a one-dimensional plasma transport code

    International Nuclear Information System (INIS)

    Singer, C.E.; Post, D.E.; Mikkelsen, D.R.

    1986-07-01

    The purpose of BALDUR is to calculate the evolution of plasma parameters in an MHD equilibrium which can be approximated by concentric circular flux surfaces. Transport of up to six species of ionized particles, of electron and ion energy, and of poloidal magnetic flux is computed. A wide variety of source terms are calculated including those due to neutral gas, fusion, and auxiliary heating. The code is primarily designed for modeling tokamak plasmas but could be adapted to other toroidal confinement systems

  20. Numerical solution of multigroup diffuse equations of one-dimensional geometry

    International Nuclear Information System (INIS)

    Pavelesku, M.; Adam, S.

    1975-01-01

    The one-dimensional diffuse theory is used for reactor physics calculations of fast reactors. Computer program based on the one-dimensional diffuse theory is speedy and not memory consuming. The algorithm is described for the three-zone fast reactor criticality computation in one-dimensional diffusion approximation. This algorithm is realised on IBM 370/135 computer. (I.T.)

  1. Phonons in a one-dimensional Yukawa chain: Dusty plasma experiment and model

    International Nuclear Information System (INIS)

    Liu Bin; Goree, J.

    2005-01-01

    Phonons in a one-dimensional chain of charged microspheres suspended in a plasma were studied in an experiment. The phonons correspond to random particle motion in the chain; no external manipulation was applied to excite the phonons. Two modes were observed, longitudinal and transverse. The velocity fluctuations in the experiment are analyzed using current autocorrelation functions and a phonon spectrum. The phonon energy was found to be unequally partitioned among phonon modes in the dusty plasma experiment. The experimental phonon spectrum was characterized by a dispersion relation that was found to differ from the dispersion relation for externally excited phonons. This difference is attributed to the presence of frictional damping due to gas, which affects the propagation of externally excited phonons differently from phonons that correspond to random particle motion. A model is developed and fit to the experiment to explain the features of the autocorrelation function, phonon spectrum, and the dispersion relation

  2. One-dimensional model of steady, compressible channel flow with mass, momentum, and energy addition

    International Nuclear Information System (INIS)

    Johnston, S.C.

    1976-09-01

    A one-dimensional model of steady, compressible channel flow with mass, momentum and energy addition is discussed. An exact solution to the governing equations was found and from it a similarity parameter relating dimensionless mass, momentum and energy addition identified. This similarity parameter is used to make two flows having different dimensionless mass, momentum and energy additions equivalent. Application of the similarity parameter to the LASL Intense Neutron Source experiment and the Sandia simulation of that experiment results in an expression relating the dimensionless mass addition of combustible gas required in the Sandia experiment to dimensionless energy addition in the LASL experiment. Results of the analysis indicate that the Sandia experiment can realistically simulate the energy addition in the LASL Intense Neutron Source experiment

  3. Thermally activated phase slips of one-dimensional Bose gases in shallow optical lattices

    Science.gov (United States)

    Kunimi, Masaya; Danshita, Ippei

    2017-03-01

    We study the decay of superflow via thermally activated phase slips in one-dimensional Bose gases in a shallow optical lattice. By using the Kramers formula, we numerically calculate the nucleation rate of a thermally activated phase slip for various values of the filling factor and flow velocity in the absence of a harmonic trapping potential. Within the local density approximation, we derive a formula connecting the phase-slip nucleation rate with the damping rate of a dipole oscillation of the Bose gas in the presence of a harmonic trap. We use the derived formula to directly compare our theory with the recent experiment done by the LENS group [L. Tanzi et al., Sci. Rep. 6, 25965 (2016), 10.1038/srep25965]. From the comparison, the observed damping of dipole oscillations in a weakly correlated and small velocity regime is attributed dominantly to thermally activated phase slips rather than quantum phase slips.

  4. Quench-Induced Breathing Mode of One-Dimensional Bose Gases

    Science.gov (United States)

    Fang, Bess; Carleo, Giuseppe; Johnson, Aisling; Bouchoule, Isabelle

    2014-07-01

    We measure the position- and momentum-space breathing dynamics of trapped one-dimensional Bose gases at finite temperature. The profile in real space reveals sinusoidal width oscillations whose frequency varies continuously through the quasicondensate to ideal Bose gas crossover. A comparison with theoretical models taking temperature into account is provided. In momentum space, we report the first observation of a frequency doubling in the quasicondensate regime, corresponding to a self-reflection mechanism due to the repulsive interactions. Such a mechanism is predicted for a fermionized system, and has not been observed to date. The disappearance of the frequency doubling through the crossover is mapped out experimentally, giving insights into the dynamics of the breathing evolution.

  5. Quench-induced breathing mode of one-dimensional Bose gases.

    Science.gov (United States)

    Fang, Bess; Carleo, Giuseppe; Johnson, Aisling; Bouchoule, Isabelle

    2014-07-18

    We measure the position- and momentum-space breathing dynamics of trapped one-dimensional Bose gases at finite temperature. The profile in real space reveals sinusoidal width oscillations whose frequency varies continuously through the quasicondensate to ideal Bose gas crossover. A comparison with theoretical models taking temperature into account is provided. In momentum space, we report the first observation of a frequency doubling in the quasicondensate regime, corresponding to a self-reflection mechanism due to the repulsive interactions. Such a mechanism is predicted for a fermionized system, and has not been observed to date. The disappearance of the frequency doubling through the crossover is mapped out experimentally, giving insights into the dynamics of the breathing evolution.

  6. Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

    CERN Document Server

    Nikolaenko, V A; Gladchenko, S P

    2002-01-01

    Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B 0.9 K) and the electron-ripplon scattering (T 1(here omega sub c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron syst...

  7. Fermi Large Area Telescope

    Science.gov (United States)

    are available to the public, along with standard analysis software, from NASA's Fermi Science Support Center. For general questions about Fermi, Fermi science, or Fermi classroom materials, please contact Fermi has its own music: a prelude and a symphony. Gamma Ray Bursts trasformed into visual music

  8. Pseudogap phenomena in ultracold atomic Fermi gases

    OpenAIRE

    Chen, Qijin; Wang, Jibiao

    2014-01-01

    The pairing and superfluid phenomena in a two-component ultracold atomic Fermi gas is an analogue of Cooper pairing and superconductivity in an electron system, in particular, the high $T_c$ superconductors. Owing to the various tunable parameters that have been made accessible experimentally in recent years, atomic Fermi gases can be explored as a prototype or quantum simulator of superconductors. It is hoped that, utilizing such an analogy, the study of atomic Fermi gases may shed light to ...

  9. IMPLODING IGNITION WAVES. I. ONE-DIMENSIONAL ANALYSIS

    International Nuclear Information System (INIS)

    Kushnir, Doron; Waxman, Eli; Livne, Eli

    2012-01-01

    We show that converging spherical and cylindrical shock waves may ignite a detonation wave in a combustible medium, provided the radius at which the shocks become strong exceeds a critical radius, R crit . An approximate analytic expression for R crit is derived for an ideal gas equation of state and a simple (power-law-Arrhenius) reaction law, and shown to reproduce the results of numerical solutions. For typical acetylene-air experiments we find R crit ∼ 100 μm (spherical) and R crit ∼ 1 mm (cylindrical). We suggest that the deflagration to detonation transition (DDT) observed in these systems may be due to converging shocks produced by the turbulent deflagration flow, which reaches sub- (but near) sonic velocities on scales >>R crit . Our suggested mechanism differs from that proposed by Zel'dovich et al., in which a fine-tuned spatial gradient in the chemical induction time is required to be maintained within the turbulent deflagration flow. Our analysis may be readily extended to more complicated equations of state and reaction laws. An order of magnitude estimate of R crit within a white dwarf at the pre-detonation conditions believed to lead to Type Ia supernova explosions is 0.1 km, suggesting that our proposed mechanism may be relevant for DDT initiation in these systems. The relevance of our proposed ignition mechanism to DDT initiation may be tested by both experiments and numerical simulations.

  10. One-Dimensional Vanadium Dioxide Nanostructures for Room Temperature Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Aline Simo

    2015-06-01

    Full Text Available In relation to hydrogen (H2 economy in general and gas sensing in particular, an extensive set of one dimensional (1-D nano-scaled oxide materials are being investigated as ideal candidates for potential gas sensing applications. This is correlated to their set of singular surface characteristics, shape anisotropy and readiness for integrated devices. Nanostructures of well- established gas sensing materials such as Tin Oxide (SnO2, Zinc Oxide (ZnO, Indium (III Oxide (In2O3, and Tungsten Trioxide (WO3 have shown higher sensitivity and gas selectivity, quicker response, faster time recovery, as well as an enhanced capability to detect gases at low concentrations. While the overall sensing characteristics of these so called 1-D nanomaterials are superior, they are efficient at high temperature; generally above 200 0C. This operational impediment results in device complexities in integration that limit their technological applications, specifically in their miniaturized arrangements. Unfortunately, for room temperature applications, there is a necessity to dope the above mentioned nano-scaled oxides with noble metals such as Platinum (Pt, Palladium (Pd, Gold (Au, Ruthenium (Ru. This comes at a cost. This communication reports, for the first time, on the room temperature enhanced H2 sensing properties of a specific phase of pure Vanadium Dioxide (VO2 phase A in their nanobelt form. The relatively observed large H2 room temperature sensing in this Mott type specific oxide seems to reach values as low as 14 ppm H2 which makes it an ideal gas sensing in H2 fuelled systems.

  11. Strongly interacting Fermi gases

    Directory of Open Access Journals (Sweden)

    Bakr W.

    2013-08-01

    Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

  12. GITTAM program for numerical simulation of one-dimensional targets TIS. Part 2

    International Nuclear Information System (INIS)

    Arpishkin, Yu.P.; Basko, M.M.; Sokolovskij, M.V.

    1989-01-01

    A finite-difference algorithm for numeric solution of a system of one-dimensional hydrodynamics equation with heat conductivity, radiation diffusion and thermonuclear combustion is considered. The algorithm presented allows one to simulate one-dimensional thermonuclear targets for heavy-ion synthesis (HIS), irradiated with heavy ion beams. A brief description of a complex of GITTAM programs in which finite-difference algorithm for one-dimensional thermonuclear HIS target simulation is used, is given. 5 refs.; 3 figs

  13. Modelling of Graphene Nanoribbon Fermi Energy

    International Nuclear Information System (INIS)

    Johari, Z.; Ahmadi, M.T.; Chek, D.C.Y.; Amin, N.A.; Ismail, R.

    2010-01-01

    Graphene nano ribbon (GNR) is a promising alternative to carbon nano tube (CNT) to overcome the chirality challenge as a nano scale device channel. Due to the one-dimensional behavior of plane GNR, the carrier statistic study is attractive. Research works have been done on carrier statistic study of GNR especially in the parabolic part of the band structure using Boltzmann approximation (nondegenerate regime). Based on the quantum confinement effect, we have improved the fundamental study in degenerate regime for both the parabolic and non parabolic parts of GNR band energy. Our results demonstrate that the band energy of GNR near to the minimum band energy is parabolic. In this part of the band structure, the Fermi-Dirac integrals are sufficient for the carrier concentration study. The Fermi energy showed the temperature-dependent behavior similar to any other one-dimensional device in nondegenerate regime. However in the degenerate regime, the normalized Fermi energy with respect to the band edge is a function of carrier concentration. The numerical solution of Fermi-Dirac integrals for non parabolic region, which is away from the minimum energy band structure of GNR, is also presented.

  14. Magnetotransport in a quasi-one-dimensional electron system over superfluid helium

    International Nuclear Information System (INIS)

    Nikolaenko, V.A.; Kovdrya, Yu.Z.; Gladchenko, S.P.

    2002-01-01

    Magnetotransport in a nondegenerate quasi-one-dimensional electron system (Q1D) over superfluid helium is investigated experimentally. The experiments were carried out at perpendicular magnetic fields, B xx of the conducting channels mainly grows with increasing B for both the electron-gas atom scattering (T > 0.9 K) and the electron-ripplon scattering (T c τ>1(here ω c is the cyclotron frequency and t is the relaxation time of the electron system) agree qualitatively with the self-consistent Born approximation theory for a 2D electron system over helium. It is supposed that the quantitative discrepancies in the experimental and theoretical data are connected with different peculiar features of the investigated and analyzed electron systems. The experimental data on electron mobility at low temperatures and small magnetic fields coincide with the theoretical calculation made for the Q1D system. The negative magnetoresistance of the channels observed both in the electron-gas scattering and electron-ripplon scattering regions is supposed to be due to weak localization of carriers in the investigated electron system

  15. Luttinger hydrodynamics of confined one-dimensional Bose gases with dipolar interactions

    International Nuclear Information System (INIS)

    Citro, R; Palo, S De; Orignac, E; Pedri, P; Chiofalo, M-L

    2008-01-01

    Ultracold bosonic and fermionic quantum gases confined to quasi-one-dimensional (1D) geometry are promising candidates for probing fundamental concepts of Luttinger liquid (LL) physics. They can also be exploited for devising applications in quantum information processing and precision measurements. Here, we focus on 1D dipolar Bose gases, where evidence of super-strong coupling behavior has been demonstrated by analyzing the low-energy static and dynamical structures of the fluid at zero temperature by a combined reptation quantum Monte Carlo (RQMC) and bosonization approach. Fingerprints of LL behavior emerge in the whole crossover from the already strongly interacting Tonks-Girardeau at low density to a dipolar density wave regime at high density. We have also shown that a LL framework can be effectively set up and utilized to describe this strongly correlated crossover physics in the case of confined 1D geometries after using the results for the homogeneous system in LL hydrodynamic equations within a local density approximation. This leads to the prediction of observable quantities such as the frequencies of the collective modes of the trapped dipolar gas under the more realistic conditions that could be found in ongoing experiments. The present paper provides a description of the theoretical framework in which the above results have been worked out, making available all the detailed derivations of the hydrodynamic Luttinger equations for the inhomogeneous trapped gas and of the correlation functions for the homogeneous system

  16. Effect of process operating conditions in the biomass torrefaction: A simulation study using one-dimensional reactor and process model

    International Nuclear Information System (INIS)

    Park, Chansaem; Zahid, Umer; Lee, Sangho; Han, Chonghun

    2015-01-01

    Torrefaction reactor model is required for the development of reactor and process design for biomass torrefaction. In this study, a one-dimensional reactor model is developed based on the kinetic model describing volatiles components and solid evolution and the existing thermochemical model considering the heat and mass balance. The developed reactor model used the temperature and flow rate of the recycled gas as the practical manipulated variables instead of the torrefaction temperature. The temperature profiles of the gas and solid phase were generated, depending on the practical thermal conditions, using developed model. Moreover, the effect of each selected operating variables on the parameters of the torrefaction process and the effect of whole operating variables with particular energy yield were analyzed. Through the results of sensitivity analysis, it is shown that the residence time insignificantly influenced the energy yield when the flow rate of recycled gas is low. Moreover, higher temperature of recycled gas with low flow rate and residence time produces the attractive properties, including HHV and grindability, of torrefied biomass when the energy yield is specified. - Highlights: • A one-dimensional reactor model for biomass torrefaction is developed considering the heat and mass balance. • The developed reactor model uses the temperature and flow rate of the recycled gas as the practical manipulated variables. • The effect of operating variables on the parameters of the torrefaction process is analyzed. • The results of sensitivity analysis represent notable discussions which were not done by the previous researches

  17. Wide applicability of high-Tc pairing originating from coexisting wide and incipient narrow bands in quasi-one-dimensional systems

    Science.gov (United States)

    Matsumoto, Karin; Ogura, Daisuke; Kuroki, Kazuhiko

    2018-01-01

    We study superconductivity in the Hubbard model on various quasi-one-dimensional lattices with coexisting wide and narrow bands originating from multiple sites within a unit cell, where each site corresponds to a single orbital. The systems studied are the two-leg and three-leg ladders, the diamond chain, and the crisscross ladder. These one-dimensional lattices are weakly coupled to form two-dimensional (quasi-one-dimensional) ones, and the fluctuation exchange approximation is adopted to study spin-fluctuation-mediated superconductivity. When one of the bands is perfectly flat and the Fermi level intersecting the wide band is placed in the vicinity of, but not within, the flat band, superconductivity arising from the interband scattering processes is found to be strongly enhanced owing to the combination of the light electron mass of the wide band and the strong pairing interaction due to the large density of states of the flat band. Even when the narrow band has finite bandwidth, the pairing mechanism still works since the edge of the narrow band, due to its large density of states, plays the role of the flat band. The results indicate the wide applicability of the high-Tc pairing mechanism due to coexisting wide and "incipient" narrow bands in quasi-one-dimensional systems.

  18. A general spectral method for the numerical simulation of one-dimensional interacting fermions

    Science.gov (United States)

    Clason, Christian; von Winckel, Gregory

    2012-08-01

    solution of the multi-particle one-dimensional Schrödinger equation in a quantum well is challenging due to the exponential growth in the number of degrees of freedom with increasing particles. Solution method: A nodal spectral Galerkin scheme is used where the basis functions are constructed to obey the antisymmetry relations of the fermionic wave function. The assembly of these matrices is performed efficiently by exploiting the combinatorial structure of the sparsity patterns. Reasons for new version: A Python implementation is now included. Summary of revisions: Added a Python implementation; small documentation fixes in Matlab implementation. No change in features of the package. Restrictions: Only one-dimensional computational domains with homogeneous Dirichlet or periodic boundary conditions are supported. Running time: Seconds to minutes.

  19. Matrix product state calculations for one-dimensional quantum chains and quantum impurity models

    International Nuclear Information System (INIS)

    Muender, Wolfgang

    2011-01-01

    This thesis contributes to the field of strongly correlated electron systems with studies in two distinct fields thereof: the specific nature of correlations between electrons in one dimension and quantum quenches in quantum impurity problems. In general, strongly correlated systems are characterized in that their physical behaviour needs to be described in terms of a many-body description, i.e. interactions correlate all particles in a complex way. The challenge is that the Hilbert space in a many-body theory is exponentially large in the number of particles. Thus, when no analytic solution is available - which is typically the case - it is necessary to find a way to somehow circumvent the problem of such huge Hilbert spaces. Therefore, the connection between the two studies comes from our numerical treatment: they are tackled by the density matrix renormalization group (DMRG) and the numerical renormalization group (NRG), respectively, both based on matrix product states. The first project presented in this thesis addresses the problem of numerically finding the dominant correlations in quantum lattice models in an unbiased way, i.e. without using prior knowledge of the model at hand. A useful concept for this task is the correlation density matrix (CDM) which contains all correlations between two clusters of lattice sites. We show how to extract from the CDM, a survey of the relative strengths of the system's correlations in different symmetry sectors as well as detailed information on the operators carrying long-range correlations and the spatial dependence of their correlation functions. We demonstrate this by a DMRG study of a one-dimensional spinless extended Hubbard model, while emphasizing that the proposed analysis of the CDM is not restricted to one dimension. The second project presented in this thesis is motivated by two phenomena under ongoing experimental and theoretical investigation in the context of quantum impurity models: optical absorption

  20. Matrix product state calculations for one-dimensional quantum chains and quantum impurity models

    Energy Technology Data Exchange (ETDEWEB)

    Muender, Wolfgang

    2011-09-28

    This thesis contributes to the field of strongly correlated electron systems with studies in two distinct fields thereof: the specific nature of correlations between electrons in one dimension and quantum quenches in quantum impurity problems. In general, strongly correlated systems are characterized in that their physical behaviour needs to be described in terms of a many-body description, i.e. interactions correlate all particles in a complex way. The challenge is that the Hilbert space in a many-body theory is exponentially large in the number of particles. Thus, when no analytic solution is available - which is typically the case - it is necessary to find a way to somehow circumvent the problem of such huge Hilbert spaces. Therefore, the connection between the two studies comes from our numerical treatment: they are tackled by the density matrix renormalization group (DMRG) and the numerical renormalization group (NRG), respectively, both based on matrix product states. The first project presented in this thesis addresses the problem of numerically finding the dominant correlations in quantum lattice models in an unbiased way, i.e. without using prior knowledge of the model at hand. A useful concept for this task is the correlation density matrix (CDM) which contains all correlations between two clusters of lattice sites. We show how to extract from the CDM, a survey of the relative strengths of the system's correlations in different symmetry sectors as well as detailed information on the operators carrying long-range correlations and the spatial dependence of their correlation functions. We demonstrate this by a DMRG study of a one-dimensional spinless extended Hubbard model, while emphasizing that the proposed analysis of the CDM is not restricted to one dimension. The second project presented in this thesis is motivated by two phenomena under ongoing experimental and theoretical investigation in the context of quantum impurity models: optical absorption

  1. One-dimensional electron liquid at a surface. Gold nanowires on Ge(001)

    Energy Technology Data Exchange (ETDEWEB)

    Blumenstein, Christian

    2012-09-11

    Self-organized nanowires at semiconductor surfaces offer the unique opportunity to study electrons in reduced dimensions. Notably the dimensionality of the system determines it's electronic properties, beyond the quasiparticle description. In the quasi-one-dimensional (1D) regime with weak lateral coupling between the chains, a Peierls instability can be realized. A nesting condition in the Fermi surface leads to a backfolding of the 1D electron band and thus to an insulating state. It is accompanied by a charge density wave (CDW) in real space that corresponds to the nesting vector. This effect has been claimed to occur in many surface-defined nanowire systems, such as the In chains on Si(111) or the Au reconstructions on the terraced Si(553) and Si(557) surfaces. Therefore a weak coupling between the nanowires in these systems has to be concluded. However theory proposes another state in the perfect 1D limit, which is completely destroyed upon slight coupling to higher dimensions. In this so-called Tomonaga-Luttinger liquid (TLL) state, the quasiparticle description of the Fermi liquid breaks down. Since the interaction between the electrons is enhanced due to the strong confinement, only collective excitations are allowed. This leads to novel effects like spin charge separation, where spin and charge degrees of freedom are decoupled and allowed to travel independently along the 1D-chain. Such rare state has not been realized at a surface until today. This thesis uses a novel approach to realize nanowires with improved confinement by studying the Au reconstructed Ge(001) surface. A new cleaning procedure using piranha solution is presented, in order to prepare a clean and long-range ordered substrate. To ensure optimal growth of the Au nanowires the phase diagram is extensively studied by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The structural elements of the chains are revealed and described in high detail. Remarkably

  2. One-dimensional calculation of flow branching using the method of characteristics

    International Nuclear Information System (INIS)

    Meier, R.W.; Gido, R.G.

    1978-05-01

    In one-dimensional flow systems, the flow often branches, such as at a tee or manifold. The study develops a formulation for calculating the flow through branch points with one-dimensional method of characteristics equations. The resultant equations were verified by comparison with experimental measurements

  3. One-dimensional treatment of polyatomic crystals by the Laplace transform method

    International Nuclear Information System (INIS)

    Rosato, A.; Santana, P.H.A.

    1976-01-01

    The one dimensional periodic potential problem is solved using the Laplace transform method and a condensed expression for the relation E x k and effective mass for one electron in a polyatomic structure is determined. Applications related to the effect of the asymmetry of the potential upon the one dimensional band structure are discussed [pt

  4. One-dimensional low spatial frequency LIPSS with rotating orientation on fused silica

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Simon, E-mail: simon.schwarz@h-ab.de; Rung, Stefan; Hellmann, Ralf

    2017-07-31

    Highlights: • Generation of one-dimensional low spatial frequency LIPSS on transparent material. • Varying the angle of incidence results in a rotation of the one-dimensional LSFL. • Rotation angle of LSFL decreases with increasing the applied fluence. • Orientation of the LSFL is mirror-inverted when reversing the scanning direction. - Abstract: We report on the generation of one-dimensional low spatial frequency LIPSS on transparent material. The influence of the applied laser fluence and angle of incidence on the periodicity, orientation and quality of the one-dimensional low spatial frequency LIPSS is investigated, facilitating the generation of highly uniform LIPSS alongside a line. Most strikingly, however, we observe a previously unreported effect of a pronounced rotation of the one-dimensional low spatial frequency LIPSS for varying angle of incidence upon inclined laser irradiation.

  5. Metal-Insulator Phase Transition in Quasi-One-Dimensional VO2 Structures

    Directory of Open Access Journals (Sweden)

    Woong-Ki Hong

    2015-01-01

    Full Text Available The metal-insulator transition (MIT in strongly correlated oxides has attracted considerable attention from both theoretical and experimental researchers. Among the strongly correlated oxides, vanadium dioxide (VO2 has been extensively studied in the last decade because of a sharp, reversible change in its optical, electrical, and magnetic properties at approximately 341 K, which would be possible and promising to develop functional devices with advanced technology by utilizing MITs. However, taking the step towards successful commercialization requires the comprehensive understanding of MIT mechanisms, enabling us to manipulate the nature of transitions. In this regard, recently, quasi-one-dimensional (quasi-1D VO2 structures have been intensively investigated due to their attractive geometry and unique physical properties to observe new aspects of transitions compared with their bulk counterparts. Thus, in this review, we will address recent research progress in the development of various approaches for the modification of MITs in quasi-1D VO2 structures. Furthermore, we will review recent studies on realizing novel functional devices based on quasi-1D VO2 structures for a wide range of applications, such as a gas sensor, a flexible strain sensor, an electrical switch, a thermal memory, and a nonvolatile electrical memory with multiple resistance.

  6. One-Dimensional SnO2 Nano structures: Synthesis and Applications

    International Nuclear Information System (INIS)

    Pan, J.; Shen, H.; Mathur, S.; Pan, J.

    2012-01-01

    Nano scale semiconducting materials such as quantum dots (0-dimensional) and one-dimensional (1D) structures, like nano wires, nano belts, and nano tubes, have gained tremendous attention within the past decade. Among the variety of 1D nano structures, tin oxide (SnO 2 ) semiconducting nano structures are particularly interesting because of their promising applications in optoelectronic and electronic devices due to both good conductivity and transparence in the visible region. This article provides a comprehensive review of the recent research activities that focus on the rational synthesis and unique applications of 1D SnO 2 nano structures and their optical and electrical properties. We begin with the rational design and synthesis of 1D SnO 2 nano structures, such as nano tubes, nano wires, nano belts, and some heterogeneous nano structures, and then highlight a range of applications (e.g., gas sensor, lithium-ion batteries, and nano photonics) associated with them. Finally, the review is concluded with some perspectives with respect to future research on 1D SnO 2 nano structures

  7. Analysis of one-dimensional nonequilibrium two-phase flow using control volume method

    International Nuclear Information System (INIS)

    Minato, Akihiko; Naitoh, Masanori

    1987-01-01

    A one-dimensional numerical analysis model was developed for prediction of rapid flow transient behavior involving boiling. This model was based on six conservation equations of time averaged parameters of gas and liquid behavior. These equations were solved by using a control volume method with an explicit time integration. This model did not use staggered mesh scheme, which had been commonly used in two-phase flow analysis. Because void fraction and velocity of each phase were defined at the same location in the present model, effects of void fraction on phase velocity calculation were treated directly without interpolation. Though non-staggered mesh scheme was liable to cause numerical instability with zigzag pressure field, stability was achieved by employing the Godunov method. In order to verify the present analytical model, Edwards' pipe blow down and Zaloudek's initially subcooled critical two-phase flow experiments were analyzed. Stable solutions were obtained for rarefaction wave propagation with boiling and transient two-phase flow behavior in a broken pipe by using this model. (author)

  8. One-dimensional model of oxygen transport impedance accounting for convection perpendicular to the electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mainka, J. [Laboratorio Nacional de Computacao Cientifica (LNCC), CMC 6097, Av. Getulio Vargas 333, 25651-075 Petropolis, RJ, Caixa Postal 95113 (Brazil); Maranzana, G.; Thomas, A.; Dillet, J.; Didierjean, S.; Lottin, O. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee (LEMTA), Universite de Lorraine, 2, avenue de la Foret de Haye, 54504 Vandoeuvre-les-Nancy (France); LEMTA, CNRS, 2, avenue de la Foret de Haye, 54504 Vandoeuvre-les-Nancy (France)

    2012-10-15

    A one-dimensional (1D) model of oxygen transport in the diffusion media of proton exchange membrane fuel cells (PEMFC) is presented, which considers convection perpendicular to the electrode in addition to diffusion. The resulting analytical expression of the convecto-diffusive impedance is obtained using a convection-diffusion equation instead of a diffusion equation in the case of classical Warburg impedance. The main hypothesis of the model is that the convective flux is generated by the evacuation of water produced at the cathode which flows through the porous media in vapor phase. This allows the expression of the convective flux velocity as a function of the current density and of the water transport coefficient {alpha} (the fraction of water being evacuated at the cathode outlet). The resulting 1D oxygen transport impedance neglects processes occurring in the direction parallel to the electrode that could have a significant impact on the cell impedance, like gas consumption or concentration oscillations induced by the measuring signal. However, it enables us to estimate the impact of convection perpendicular to the electrode on PEMFC impedance spectra and to determine in which conditions the approximation of a purely diffusive oxygen transport is valid. Experimental observations confirm the numerical results. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. A transient one-dimensional numerical model for kinetic Stirling engine

    International Nuclear Information System (INIS)

    Wang, Kai; Dubey, Swapnil; Choo, Fook Hoong; Duan, Fei

    2016-01-01

    Highlights: • A non-equilibrium thermal mode with considering loses is adopted in Stirling engine. • Good agreements are achieved for predicting various critical system parameters. • Differences between helium and hydrogen systems are highlighted and analyzed. • Pressure drop of helium system is much larger and more sensitive to frequency. - Abstract: A third-order numerical model based on one-dimensional computational fluid dynamics is developed for kinetic Stirling engines. Various loss mechanisms in Stirling engines, including gas spring hysteresis loss, shuttle loss, appendix displacer gap loss, gas leakage loss, finite speed loss, piston friction loss, pressure drop loss, heat conduction loss, mechanical loss and imperfect heat transfer, are considered and embedded into the basic control equations. The non-equilibrium thermal model is adopted for the regenerator to capture the oscillating features of the gas and solid temperatures. To improve the numerical stability and accuracy, the implicit second-order time difference scheme and the second-order upwind scheme are adopted for discretizing the time differential terms and convective terms, respectively. Experimental validations are then conducted on a beta-type Stirling engine with the extensive experimental data for diverse working conditions. The results show that the developed model has better accuracies than the previous second-order models. Good agreements are achieved for predicting various critical system parameters, including pressure-volume diagram, indicated power, brake power, indicated efficiency, brake efficiency and mechanical efficiency. In particular, both the experiments and simulations show that the Stirling engine charged with helium tends to have much lower optimal working frequencies and poorer performances compared to the hydrogen system. Based on the analyses of the losses, it reveals that the pressure drop in the flow channels plays a critical role in shaping the different

  10. Comment on "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit".

    Science.gov (United States)

    Carrillo-Bernal, M A; Núñez-Yépez, H N; Salas-Brito, A L; Solis, Didier A

    2015-02-01

    In the referred paper, the authors use a numerical method for solving ordinary differential equations and a softened Coulomb potential -1/√[x(2)+β(2)] to study the one-dimensional Coulomb problem by approaching the parameter β to zero. We note that even though their numerical findings in the soft potential scenario are correct, their conclusions do not extend to the one-dimensional Coulomb problem (β=0). Their claims regarding the possible existence of an even ground state with energy -∞ with a Dirac-δ eigenfunction and of well-defined parity eigenfunctions in the one-dimensional hydrogen atom are questioned.

  11. One-dimensional power spectrum and neutrino mass in the spectra of BOSS

    International Nuclear Information System (INIS)

    Borde, Arnaud

    2014-01-01

    -volume ones. Using a splicing technique, the resolution is further enhanced to reach the equivalent of simulations with 3072"3 = 29 billion particles of each type in a (100 Mpc/h)"3 box size, i.e. a mean mass per gas particle of 1.2x10"5 solar masses. We show that the resulting power spectrum is accurate at the 2% level over the full range from a few Mpc to several tens of Mpc. We explore the effect on the one-dimensional transmitted-flux power spectrum of 4 cosmological parameters (n_s, sigma_8, Omega_m,H_0), 2 astrophysical parameters (T_0, gamma) related to the heating rate of the IGM and the sum of the neutrino masses. By varying the input parameters around a central model chosen to be in agreement with the latest Planck results, we built a grid of simulations that allows the study of the impact on the flux power spectrum of these seven relevant parameters. We improve upon previous studies by not only measuring the effect of each parameter individually, but also probing the impact of the simultaneous variation of each pair of parameters. We thus provide a full second-order expansion, including cross-terms, around our central model. We check the validity of the second-order expansion with independent simulations obtained either with different cosmological parameters or different seeds for the initial condition generation. Finally, a comparison to the one-dimensional Lyman-alpha forest power spectrum obtained in the first part with BOSS data shows an excellent agreement. Eventually, even if there are still some potential biases and systematic errors that need to be studied in our simulation, we performed cosmological fits combining our measurement of the one-dimensional power spectrum and other cosmological probes such as the CMB results provided by Planck. These preliminary results are very encouraging as they lead to some of the tightest cosmological constraints as of today, especially on the sum of the neutrino masses with an upper limit of 0.1 eV. (author) [fr

  12. In-flight and collisional dissipation as a mechanism to suppress Fermi acceleration in a breathing Lorentz gas.

    Science.gov (United States)

    Oliveira, Diego F M; Leonel, Edson D

    2012-06-01

    Some dynamical properties for a time dependent Lorentz gas considering both the dissipative and non dissipative dynamics are studied. The model is described by using a four-dimensional nonlinear mapping. For the conservative dynamics, scaling laws are obtained for the behavior of the average velocity for an ensemble of non interacting particles and the unlimited energy growth is confirmed. For the dissipative case, four different kinds of damping forces are considered namely: (i) restitution coefficient which makes the particle experiences a loss of energy upon collisions; and in-flight dissipation given by (ii) F=-ηV(2); (iii) F=-ηV(μ) with μ≠1 and μ≠2 and; (iv) F=-ηV, where η is the dissipation parameter. Extensive numerical simulations were made and our results confirm that the unlimited energy growth, observed for the conservative dynamics, is suppressed for the dissipative case. The behaviour of the average velocity is described using scaling arguments and classes of universalities are defined.

  13. Prediction of inorganic superconductors with quasi-one-dimensional crystal structure

    International Nuclear Information System (INIS)

    Volkova, L M; Marinin, D V

    2013-01-01

    Models of superconductors having a quasi-one-dimensional crystal structure based on the convoluted into a tube Ginzburg sandwich, which comprises a layered dielectric–metal–dielectric structure, have been suggested. The critical crystal chemistry parameters of the Ginzburg sandwich determining the possibility of the emergence of superconductivity and the T c value in layered high-T c cuprates, which could have the same functions in quasi-one-dimensional fragments (sandwich-type tubes), have been examined. The crystal structures of known low-temperature superconductors, in which one can mark out similar quasi-one-dimensional fragments, have been analyzed. Five compounds with quasi-one-dimensional structures, which can be considered as potential parents of new superconductor families, possibly with high transition temperatures, have been suggested. The methods of doping and modification of these compounds are provided. (paper)

  14. Critical exponents in the transition to chaos in one-dimensional ...

    Indian Academy of Sciences (India)

    The transition from periodic to chaotic behavior in one-dimensional discrete dynamical systems .... consider the reverse sequence from µb to µ∞, a ... at which the change from one scaling region to another takes place, with the higher order. 12.

  15. Explicit solutions of one-dimensional, first-order, stationary mean-field games with congestion

    KAUST Repository

    Gomes, Diogo A.; Nurbekyan, Levon; Prazeres, Mariana

    2017-01-01

    Here, we consider one-dimensional first-order stationary mean-field games with congestion. These games arise when crowds face difficulty moving in high-density regions. We look at both monotone decreasing and increasing interactions and construct

  16. Solutions stability of one-dimensional parametric superconducting magnetic levitation model analysis by the first approximation

    International Nuclear Information System (INIS)

    Shvets', D.V.

    2009-01-01

    By the first approximation analyzing stability conditions of unperturbed solution of one-dimensional dynamic model with magnetic interaction between two superconducting rings obtained. The stability region in the frozen magnetic flux parameters space was constructed.

  17. Wave Transformation Over Reefs: Evaluation of One-Dimensional Numerical Models

    National Research Council Canada - National Science Library

    Demirbilek, Zeki; Nwogu, Okey G; Ward, Donald L; Sanchez, Alejandro

    2009-01-01

    Three one-dimensional (1D) numerical wave models are evaluated for wave transformation over reefs and estimates of wave setup, runup, and ponding levels in an island setting where the beach is fronted by fringing reef and lagoons...

  18. On symmetry reduction and exact solutions of the linear one-dimensional Schroedinger equation

    International Nuclear Information System (INIS)

    Barannik, L.L.

    1996-01-01

    Symmetry reduction of the Schroedinger equation with potential is carried out on subalgebras of the Lie algebra which is the direct sum of the special Galilei algebra and one-dimensional algebra. Some new exact solutions are obtained

  19. Ultra-refractive and extended-range one-dimensional photonic crystal superprisms

    Science.gov (United States)

    Ting, D. Z. Y.

    2003-01-01

    We describe theoretical analysis and design of one-dimensional photonic crystal prisms. We found that inside the photonic crystal, for frequencies near the band edges, light propagation direction is extremely sensitive to the variations in wavelength and incident angle.

  20. One-Dimensional Tunable Photonic-Crystal IR Filter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — MetroLaser proposes to design and develop an innovative narrowband tunable IR filter based on the properties of a one-dimensional photonic crystal structure with a...

  1. One-Dimensional Tunable Photonic-Crystal IR Filter, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — MetroLaser proposes to design and develop an innovative narrowband tunable IR filter based on the properties of a one-dimensional photonic crystal structure with a...

  2. A Large Class of Exact Solutions to the One-Dimensional Schrodinger Equation

    Science.gov (United States)

    Karaoglu, Bekir

    2007-01-01

    A remarkable property of a large class of functions is exploited to generate exact solutions to the one-dimensional Schrodinger equation. The method is simple and easy to implement. (Contains 1 table and 1 figure.)

  3. One dimensional Si/Sn - based nanowires and nanotubes for lithium-ion energy storage materials

    KAUST Repository

    Choi, Nam-Soon; Yao, Yan; Cui, Yi; Cho, Jaephil

    2011-01-01

    There has been tremendous interest in using nanomaterials for advanced Li-ion battery electrodes, particularly to increase the energy density by using high specific capacity materials. Recently, it was demonstrated that one dimensional (1D) Si

  4. One- and Two- Magnon Excitations in a One-Dimensional Antiferromagnet in a Magnetic Field

    DEFF Research Database (Denmark)

    Heilmann, I.U.; Kjems, Jørgen; Endoh, Y.

    1981-01-01

    We have carried out a comprehensive experimental and theoretical study of the inelastic scattering in the one-dimensional near-Heisenberg antiferromagnet (CD3)4NMnCl3 (TMMC) at low temperatures, 0.3...

  5. An Angular Leakage Correction for Modeling a Hemisphere, Using One-Dimensional Spherical Coordinates

    International Nuclear Information System (INIS)

    Schwinkendorf, K.N.; Eberle, C.S.

    2003-01-01

    A radially dependent, angular leakage correction was applied to a one-dimensional, multigroup neutron diffusion theory computer code to accurately model hemispherical geometry. This method allows the analyst to model hemispherical geometry, important in nuclear criticality safety analyses, with one-dimensional computer codes, which execute very quickly. Rapid turnaround times for scoping studies thus may be realized. This method uses an approach analogous to an axial leakage correction in a one-dimensional cylinder calculation. The two-dimensional Laplace operator was preserved in spherical geometry using a leakage correction proportional to 1/r 2 , which was folded into the one-dimensional spherical calculation on a mesh-by-mesh basis. Hemispherical geometry is of interest to criticality safety because of its similarity to piles of spilled fissile material and accumulations of fissile material in process containers. A hemisphere also provides a more realistic calculational model for spilled fissile material than does a sphere

  6. Solute transport with periodic input point source in one-dimensional ...

    African Journals Online (AJOL)

    JOY

    groundwater flow velocity is considered proportional to multiple of temporal function and ζ th ... One-dimensional solute transport through porous media with or without .... solute free. ... the periodic concentration at source of the boundary i.e.,. 0.

  7. Spin-zero sound in one- and quasi-one-dimensional 3He

    International Nuclear Information System (INIS)

    Hernandez, E.S.

    2002-01-01

    The zero sound spectrum of fluid 3 He confined to a cylindrical shell is examined for configurations characterizing strictly one-dimensional and quasi-one-dimensional regimes. It is shown that the restricted dimensionality makes room to the possibility of spin-zero sound for the attractive particle-hole interaction of liquid helium. This fact can be related to the suppression of phase instabilities and thermodynamic phase transitions in one dimension

  8. One-Dimensional Creativity: A Marcusean Critique of Work and Play in the Video Game Industry

    Directory of Open Access Journals (Sweden)

    Ergin Bulut

    2018-06-01

    Full Text Available Creativity is at the heart of the video game industry. Industry professionals, especially those producing blockbuster games for the triple-A market, speak fondly of their creative labour practices, flexible work schedules, and playful workplaces. However, a cursory glance at major triple-A franchises reveals the persistence of sequel game production and a homogeneity in genres and narratives. Herbert Marcuse’s critique of one-dimensionality may help to account for this discrepancy between the workers’ creative aspirations and the dominant homogeneity in game aesthetics. What I call ‘one-dimensional creativity’ defines the essence of triple-A game production. In the name of extolling the pleasure principle at work, one-dimensional creativity eliminates the reality principle, but only superficially. One-dimensional creativity gives game developers the opportunity to express themselves, but it is still framed by a particular technological rationality that prioritises profits over experimental art. One-dimensional creativity negates potential forms of creativity that might emerge outside the industry’s hit-driven logics. Conceptually, ‘one-dimensional creativity’ renders visible the instrumentalisation of play and the conservative design principles of triple-A game production – a production that is heavily structured with technological performance, better graphics, interactivity, and speed. Multi-dimensional video game production and aesthetics, the opposite of one-dimensional creativity, is emerging from the DIY game production scene, which is more invested in game narratives and aesthetics outside the dominant logics of one-dimensionality in triple-A game production.

  9. Effective one-dimensionality of universal ac hopping conduction in the extreme disorder limit

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Schrøder, Thomas

    1996-01-01

    A phenomenological picture of ac hopping in the symmetric hopping model (regular lattice, equal site energies, random energy barriers) is proposed according to which conduction in the extreme disorder limit is dominated by essentially one-dimensional "percolation paths." Modeling a percolation path...... as strictly one dimensional with a sharp jump rate cutoff leads to an expression for the universal ac conductivity that fits computer simulations in two and three dimensions better than the effective medium approximation....

  10. Simulation and detection of massive Dirac fermions with cold atoms in one-dimensional optical lattice

    Energy Technology Data Exchange (ETDEWEB)

    Yu Yafei, E-mail: yfyuks@hotmail.com [Laboratory of Nanophotonic Functional Materials and Devices, LQIT and SIPSE, South China Normal University, Guangzhou 510006 (China); Shan Chuanjia [Laboratory of Nanophotonic Functional Materials and Devices, LQIT and SIPSE, South China Normal University, Guangzhou 510006 (China); College of Physics and Electronic Science, Hubei Normal University, Huangshi 435002 (China); Mei Feng; Zhang Zhiming [Laboratory of Nanophotonic Functional Materials and Devices, LQIT and SIPSE, South China Normal University, Guangzhou 510006 (China)

    2012-09-15

    We propose a simple but feasible experimental scheme to simulate and detect Dirac fermions with cold atoms trapped in one-dimensional optical lattice. In our scheme, through tuning the laser intensity, the one-dimensional optical lattice can have two sites in each unit cell and the atoms around the low energy behave as massive Dirac fermions. Furthermore, we show that these relativistic quasiparticles can be detected experimentally by using atomic density profile measurements and Bragg scattering.

  11. Thermodynamics of ultracold Fermi gases

    International Nuclear Information System (INIS)

    Nascimbene, Sylvain

    2010-01-01

    Complex Hamiltonians from condensed matter, such as the Fermi-Hubbard model, can be experimentally studied using ultracold gases. This thesis describes a new method for determining the equation of state of an ultracold gas, making the comparison with many-body theories straightforward. It is based on the measurement of the local pressure inside a trapped gas from the analysis of its in situ image. We first apply this method to the study of a Fermi gas with resonant interactions, a weakly-interacting 7 Li gas acting as a thermometer. Surprisingly, none of the existing many-body theories of the unitary gas accounts for the equation of state deduced from our study over its full range. The virial expansion extracted from the high-temperature data agrees with the resolution of the three-body problem. At low temperature, we observe, contrary to some previous studies, that the normal phase behaves as a Fermi liquid. Finally we obtain the critical temperature for superfluidity from a clear signature on the equation of state. We also measure the pressure of the ground state as a function of spin imbalance and interaction strength - measure directly relevant to describe the crust of neutron stars. Our data validate Monte-Carlo simulations and quantify the Lee-Huang-Yang corrections to mean-field interactions in low-density fermionic or bosonic superfluids. We show that, in most cases, the partially polarized normal phase can be described as a Fermi liquid of polarons. The polaron effective mass extracted from the equation of state is in agreement with a study of collective modes. (author)

  12. Probing non-thermal density fluctuations in the one-dimensional Bose gas

    Directory of Open Access Journals (Sweden)

    Jacopo De Nardis, Miłosz Panfil, Andrea Gambassi, Leticia F. Cugliandolo, Robert Konik, Laura Foini

    2017-09-01

    Full Text Available Quantum integrable models display a rich variety of non-thermal excited states with unusual properties. The most common way to probe them is by performing a quantum quench, i.e., by letting a many-body initial state unitarily evolve with an integrable Hamiltonian. At late times, these systems are locally described by a generalized Gibbs ensemble with as many effective temperatures as their local conserved quantities. The experimental measurement of this macroscopic number of temperatures remains elusive. Here we show that they can be obtained by probing the dynamical structure factor of the system after the quench and by employing a generalized fluctuation-dissipation theorem that we provide. Our procedure allows us to completely reconstruct the stationary state of a quantum integrable system from state-of-the-art experimental observations.

  13. X-ray photoelectron spectra and electronic structure of quasi-one-dimensional SbSeI crystals

    Directory of Open Access Journals (Sweden)

    J.Grigas

    2007-01-01

    Full Text Available The paper presents the X-ray photoelectron spectra (XPS of the valence band (VB and of the principal core levels from the (110 and (001 crystal surfaces for the quasi-one-dimensional high permittivity SbSeI single crystal isostructural to ferroelectric SbSI. The XPS were measured with monochromatized Al Ka radiation in the energy range of 0-1400 eV at room temperature. The VB is located from 1.6 to 20 eV below the Fermi level. Experimental energies of the VB and core levels are compared with the results of theoretical ab initio calculations of the molecular model of the SbSeI crystal. The electronic structure of the VB is revealed. Shifts in the core-level binding energies of surface atoms relative to bulk ones, which show a dependency on surface crystallography, have been observed. The chemical shifts of the core levels (CL in the SbSeI crystal for the Sb, I and Se states are obtained.

  14. One-dimensional simulation of stratification and dissolved oxygen in McCook Reservoir, Illinois

    Science.gov (United States)

    Robertson, Dale M.

    2000-01-01

    As part of the Chicagoland Underflow Plan/Tunnel and Reservoir Plan, the U.S. Army Corps of Engineers, Chicago District, plans to build McCook Reservoir.a flood-control reservoir to store combined stormwater and raw sewage (combined sewage). To prevent the combined sewage in the reservoir from becoming anoxic and producing hydrogen sulfide gas, a coarse-bubble aeration system will be designed and installed on the basis of results from CUP 0-D, a zero-dimensional model, and MAC3D, a three-dimensional model. Two inherent assumptions in the application of MAC3D are that density stratification in the simulated water body is minimal or not present and that surface heat transfers are unimportant and, therefore, may be neglected. To test these assumptions, the previously tested, one-dimensional Dynamic Lake Model (DLM) was used to simulate changes in temperature and dissolved oxygen in the reservoir after a 1-in-100-year event. Results from model simulations indicate that the assumptions made in MAC3D application are valid as long as the aeration system, with an air-flow rate of 1.2 cubic meters per second or more, is operated while the combined sewage is stored in the reservoir. Results also indicate that the high biochemical oxygen demand of the combined sewage will quickly consume the dissolved oxygen stored in the reservoir and the dissolved oxygen transferred through the surface of the reservoir; therefore, oxygen must be supplied by either the rising bubbles of the aeration system (a process not incorporated in DLM) or some other technique to prevent anoxia.

  15. One-dimensional transient unequal velocity two-phase flow by the method of characteristics

    International Nuclear Information System (INIS)

    Rasouli, F.

    1981-01-01

    An understanding of two-phase flow is important when one is analyzing the accidental loss of coolant or when analyzing industrial processes. If a pipe in the steam generator of a nuclear reactor breaks, the flow will remain critical (or choked) for almost the entire blowdown. For this reason the knowledge of the two-phase maximum (critical) flow rate is important. A six-equation model--consisting of two continuity equations, two energy equations, a mixture momentum equation, and a constitutive relative velocity equation--is solved numerically by the method of characteristics for one-dimensional, transient, two-phase flow systems. The analysis is also extended to the special case of transient critical flow. The six-equation model is used to study the flow of a nonequilibrium sodium-argon system in a horizontal tube in which the nonequilibrium sodium-argon system in a horizontal tube in which the critical flow condition is at the entrance. A four-equation model is used to study the pressure-pulse propagation rate in an isothermal air-water system, and the results that are found are compared with the experimental data. Proper initial and boundary conditions are obtained for the blowdown problem. The energy and mass exchange relations are evaluated by comparing the model predictions with results of void-fraction and heat-transfer experiments. A simplified two-equation model is obtained for the special case of two incompressible phases. This model is used in the preliminary analysis of batch sedimentation. It is also used to predict the shock formation in the gas-solid fluidized bed

  16. Phase transitions and pairing signature in strongly attractive Fermi atomic gases

    International Nuclear Information System (INIS)

    Guan, X. W.; Bortz, M.; Batchelor, M. T.; Lee, C.

    2007-01-01

    We investigate pairing and quantum phase transitions in the one-dimensional two-component Fermi atomic gas in an external field. The phase diagram, critical fields, magnetization, and local pairing correlation are obtained analytically via the exact thermodynamic Bethe ansatz solution. At zero temperature, bound pairs of fermions with opposite spin states form a singlet ground state when the external field H c1 . A completely ferromagnetic phase without pairing occurs when the external field H>H c2 . In the region H c1 c2 , we observe a mixed phase of matter in which paired and unpaired atoms coexist. The phase diagram is reminiscent of that of type II superconductors. For temperatures below the degenerate temperature and in the absence of an external field, the bound pairs of fermions form hard-core bosons obeying generalized exclusion statistics

  17. A microscope for Fermi gases

    International Nuclear Information System (INIS)

    Omran, Ahmed

    2016-01-01

    This thesis reports on a novel quantum gas microscope to investigate many-body systems of fermionic atoms in optical lattices. Single-site resolved imaging of ultracold lattice gases has enabled powerful studies of bosonic quantum many-body systems. The extension of this capability to Fermi gases offers new prospects to studying complex phenomena of strongly correlated systems, for which numerical simulations are often out of reach. Using standard techniques of laser cooling, optical trapping, and evaporative cooling, ultracold Fermi gases of 6 Li are prepared and loaded into a large-scale 2D optical lattice of flexible geometry. The atomic distribution is frozen using a second, short-scaled lattice, where we perform Raman sideband cooling to induce fluorescence on each atom while maintaining its position. Together with high-resolution imaging, the fluorescence signals allow for reconstructing the initial atom distribution with single-site sensitivity and high fidelity. Magnetically driven evaporative cooling in the plane allows for producing degenerate Fermi gases with almost unity filling in the initial lattice, allowing for the first microscopic studies of ultracold gases with clear signatures of Fermi statistics. By preparing an ensemble of spin-polarised Fermi gases, we detect a flattening of the density profile towards the centre of the cloud, which is a characteristic of a band-insulating state. In one set of experiments, we demonstrate that losses of atom pairs on a single lattice site due to light-assisted collisions are circumvented. The oversampling of the second lattice allows for deterministic separation of the atom pairs into different sites. Compressing a high-density sample in a trap before loading into the lattice leads to many double occupancies of atoms populating different bands, which we can image with no evidence for pairwise losses. We therefore gain direct access to the true number statistics on each lattice site. Using this feature, we can

  18. Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

    Science.gov (United States)

    Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

    One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

  19. One-Dimensional Finite Elements An Introduction to the FE Method

    CERN Document Server

    Öchsner, Andreas

    2013-01-01

     This textbook presents finite element methods using exclusively  one-dimensional elements. The aim is to present the complex methodology in  an easily understandable but mathematically correct fashion. The approach of  one-dimensional elements enables the reader to focus on the understanding of  the principles of basic and advanced mechanical problems. The reader easily  understands the assumptions and limitations of mechanical modeling as well  as the underlying physics without struggling with complex mathematics. But  although the description is easy it remains scientifically correct.   The approach using only one-dimensional elements covers not only standard  problems but allows also for advanced topics like plasticity or the  mechanics of composite materials. Many examples illustrate the concepts and  problems at the end of every chapter help to familiarize with the topics.

  20. Method and apparatus for the electro-optic convolution of a one-dimensional signal

    International Nuclear Information System (INIS)

    1979-01-01

    Procedure for the electro-optic convolution of a signal and a filter function, whereby the one dimensional electro-optical signal would be portrayed as a line along which the clarity varies and whereby filter function is determined by one or more masks, whilst after each mask is placed a light detector, with which the light passing through the masks may be detected, whilst a one-dimensional portrayal of the signal along the masks will be developed, characterised in that a one dimensional portrayal of the signal, with the aid of an optical system in a direction across the line, will be enlarged, and that this enlarged signal in the direction of the line along the masks will be affected which the masks closing fields will contain, which are either fully transparent or are fully non-transparent. (Auth.)

  1. Synthesis and applications of one-dimensional nano-structured polyaniline: An overview

    International Nuclear Information System (INIS)

    Zhang Donghua; Wang Yangyong

    2006-01-01

    This paper summarizes and reviews the various synthesizing approaches of one-dimensional nano-structured polyaniline (PANI) and several potential applications of the nanomaterial. The synthesizing approaches can be generally categorized into template synthesis and non-template synthesis according to whether template(s), hard (physical template) or soft (chemical template), is (are) used or not. However, though the various approaches established, preparation of one-dimensional nano-structured PANI with controllable morphologies and sizes, especially well oriented arrays on a large scale is still a major challenge. Furthermore, the formation mechanisms of the nanostructures are still unclear. On the other hand, one-dimensional nano-structured PANI exhibits high surface area, high conductivity, as well as controllable chemical/physical properties and good environmental stability, rendering the nanomaterial promising candidate for application ranging from sensors, energy storage and flash welding to digital nonvolatile memory

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

    International Nuclear Information System (INIS)

    Zhu Jingmin

    2014-01-01

    We present a new model of quantum phase transitions in matrix product systems of one-dimensional spin-1 chains and study the phases coexistence phenomenon. We find that in the thermodynamic limit the proposed system has three different quantum phases and by adjusting the control parameters we are able to realize any phase, any two phases equal coexistence and the three phases equal coexistence. At every critical point the physical quantities including the entanglement are not discontinuous and the matrix product system has long-range correlation and N-spin maximal entanglement. We believe that our work is helpful for having a comprehensive understanding of quantum phase transitions in matrix product states of one-dimensional spin chains and of certain directive significance to the preparation and control of one-dimensional spin lattice models with stable coherence and N-spin maximal entanglement. (author)

  3. Quantum interference of ballistic carriers in one-dimensional semiconductor rings

    International Nuclear Information System (INIS)

    Bagraev, N.T.; Buravlev, A.D.; Klyachkin, L.E.; Malyarenko, A.M.; Ivanov, V.K.; Rykov, S.A.; Shelykh, I.A.

    2000-01-01

    Quantum interference of ballistic carriers has been studied for the first time, using one-dimensional rings formed by quantum wire pairs in self-assembled silicon quantum wells. Energy dependencies of the transmission coefficient is calculated as a function of the length and modulation of the quantum wire pairs separated by a unified drain-source system or the quantum point contacts. The quantum conductance is predicted to be increased by a factor of four using the unified drain-source system as a result of the quantum interference. Theoretical dependencies are revealed by the quantum conductance oscillations created by the deviations of both the drain-source voltage and external magnetic field inside the silicon one-dimensional rings. The results obtained put forward a basis to create the Aharonov-Bohm interferometer using the silicon one-dimensional ring [ru

  4. One dimensional neutron kinetics in the TRAC-BF1 code

    International Nuclear Information System (INIS)

    Weaver, W.L. III; Wagner, K.C.

    1987-01-01

    The TRAC-BWR code development program at the Idaho National Engineering Laboratory is developing a version of the TRAC code for the U.S. Nuclear Regulatory Commission (USNRC) to provide a best-estimate analysis capability for the simulation of postulated accidents in boiling water reactor (BWR) power systems and related experimental facilities. Recent development efforts in the TRAC-BWR program have focused on improving the computational efficiency through the incorporation of a hybrid Courant- limit-violating numerical solution scheme in the one-dimensional component models and on improving code accuracy through the development of a one-dimensional neutron kinetics model. Many other improvements have been incorporated into TRAC-BWR to improve code portability, accuracy, efficiency, and maintainability. This paper will describe the one- dimensional neutron kinetics model, the generation of the required input data for this model, and present results of the first calculations using the model

  5. Quantum Solitons and Localized Modes in a One-Dimensional Lattice Chain with Nonlinear Substrate Potential

    International Nuclear Information System (INIS)

    Li Dejun; Mi Xianwu; Deng Ke; Tang Yi

    2006-01-01

    In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solitons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j 0 .

  6. A one-dimensional plasma and impurity transport model for reversed field pinches

    International Nuclear Information System (INIS)

    Veerasingam, R.

    1991-11-01

    In this thesis a one-dimensional (1-D) plasma and impurity transport model is developed to address issues related to impurity behavior in Reversed Field Pinch (RFP) fusion plasmas. A coronal non-equilibrium model is used for impurities. The impurity model is incorporated into an existing one dimensional plasma transport model creating a multi-species plasma transport model which treats the plasma and impurity evolution self-consistently. Neutral deuterium particles are treated using a one-dimensional (slab) model of neutral transport. The resulting mode, RFPBI, is then applied to existing RFP devices such as ZT-40M and MST, and also to examine steady state behavior of ZTH based on the design parameters. A parallel algorithm for the impurity transport equations is implemented and tested to determine speedup and efficiency

  7. The one-dimensional Gross-Pitaevskii equation and its some excitation states

    Energy Technology Data Exchange (ETDEWEB)

    Prayitno, T. B., E-mail: trunk-002@yahoo.com [Physics Department, Faculty of Mathematics and Natural Science, Universitas Negeri Jakarta, Jl. Pemuda Rawamangun no. 10, Jakarta, 13220 (Indonesia)

    2015-04-16

    We have derived some excitation states of the one-dimensional Gross-Pitaevskii equation coupled by the gravitational potential. The methods that we have used here are taken by pursuing the recent work of Kivshar et. al. by considering the equation as a macroscopic quantum oscillator. To obtain the states, we have made the appropriate transformation to reduce the three-dimensional Gross-Pitaevskii equation into the one-dimensional Gross-Pitaevskii equation and applying the time-independent perturbation theory in the general solution of the one-dimensional Gross-Pitaevskii equation as a linear superposition of the normalized eigenfunctions of the Schrödinger equation for the harmonic oscillator potential. Moreover, we also impose the condition by assuming that some terms in the equation should be so small in order to preserve the use of the perturbation method.

  8. Apparent destruction of superconductivity in the disordered one-dimensional limit

    International Nuclear Information System (INIS)

    Graybeal, J.M.; Mankiewich, P.M.; Dynes, R.C.; Beasley, M.R.

    1987-01-01

    We present the results of a model-system study of the competition between superconductivity and disorder in narrow superconducting wires. As one moves from the two-dimensional regime toward the one-dimensional limit, large and systematic reductions in the superconducting transition temperature are obtained. The observed behavior extrapolates to the total destruction of superconductivity in the disordered one-dimensional limit. Our findings are in clear disagreement with a recent theoretical treatment. In addition, the superconducting fluctuations appear to be modified by disorder for the narrowest samples

  9. Optimally localized Wannier functions for quasi one-dimensional nonperiodic insulators

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, A.; Nenciu, Gheorghe

    2008-01-01

    It is proved that for general, not necessarily periodic, quasi one-dimensional systems the band position operator corresponding to an isolated part of the energy spectrum has discrete spectrum and its eigenfunctions have the same spatial localization as the corresponding spectral projection....... As a consequence, an eigenbasis of the band position operator provides a basis of optimally localized (generalized) Wannier functions for quasi one-dimensional systems, and this proves the strong Marzari-Vanderbilt conjecture. If the system has some translation symmetries (e.g. usual translations, screw...

  10. Optimally localized Wannier functions for quasi one-dimensional nonperiodic insulators

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, A.; Nenciu, Gheorghe

    It is proved that for general, not necessarily periodic quasi one dimensional systems, the band position operator corresponding to an isolated part of the energy spectrum has discrete spectrum and its eigenfunctions have the same spatial localization as the corresponding spectral projection....... As a consequence, an eigenbasis of the band position operator provides a basis of optimally localized (generalized) Wannier functions for quasi one dimensional systems. If the system has some translation symmetries (e.g. usual translations, screw transformations), they are "inherited" bythe Wannier basis....

  11. Von Neumann Entropy of an Electron in One-Dimensional Determined Potentials

    Institute of Scientific and Technical Information of China (English)

    GONG Long-Yan; TONG Pei-Qing

    2005-01-01

    @@ By using the measure of von Neumann entropy, we numerically investigate quantum entanglement of an electronmoving in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. Thedelocalized and localized eigenstates can be distinguished by von Neumann entropy of the individual eigenstates.There are drastic decreases in yon Neumann entropy of the individual eigenstates at mobility edges. In the curveof the spectrum averaged yon Neumann entropy as a function of potential parameter λ, a sharp transition existsat the metal-insulator transition point λc = 2. It is found that the yon Neumann entropy is a good quantity toreflect localization and metal-insulator transition.

  12. On the conductivity of a one-dimensional system of interacting fermions in a random potential

    International Nuclear Information System (INIS)

    Apel, W.

    1981-01-01

    A one-dimensional system of interacting fermions in an external potential is studied. The problem was for this purpose transformed to two classical models of statistical mechanics in two dimensions in which occasionally results were found in complementary ranges of the interaction constants of the fermion system. The conductivity appeared as a simple correlation function in both classical models. It was shown that the interaction in a one-dimensional polluted fermion system can cause an isolator-metal transition. (orig./HSI) [de

  13. Pseudo-Random Sequences Generated by a Class of One-Dimensional Smooth Map

    Science.gov (United States)

    Wang, Xing-Yuan; Qin, Xue; Xie, Yi-Xin

    2011-08-01

    We extend a class of a one-dimensional smooth map. We make sure that for each desired interval of the parameter the map's Lyapunov exponent is positive. Then we propose a novel parameter perturbation method based on the good property of the extended one-dimensional smooth map. We perturb the parameter r in each iteration by the real number xi generated by the iteration. The auto-correlation function and NIST statistical test suite are taken to illustrate the method's randomness finally. We provide an application of this method in image encryption. Experiments show that the pseudo-random sequences are suitable for this application.

  14. Pseudo-Random Sequences Generated by a Class of One-Dimensional Smooth Map

    International Nuclear Information System (INIS)

    Wang Xing-Yuan; Qin Xue; Xie Yi-Xin

    2011-01-01

    We extend a class of a one-dimensional smooth map. We make sure that for each desired interval of the parameter the map's Lyapunov exponent is positive. Then we propose a novel parameter perturbation method based on the good property of the extended one-dimensional smooth map. We perturb the parameter r in each iteration by the real number x i generated by the iteration. The auto-correlation function and NIST statistical test suite are taken to illustrate the method's randomness finally. We provide an application of this method in image encryption. Experiments show that the pseudo-random sequences are suitable for this application. (general)

  15. Generalized space-charge limited current and virtual cathode behaviors in one-dimensional drift space

    International Nuclear Information System (INIS)

    Yang, Zhanfeng; Liu, Guozhi; Shao, Hao; Chen, Changhua; Sun, Jun

    2013-01-01

    This paper reports the space-charge limited current (SLC) and virtual cathode behaviors in one-dimensional grounded drift space. A simple general analytical solution and an approximate solution for the planar diode are given. Through a semi-analytical method, a general solution for SLC in one-dimensional drift space is obtained. The behaviors of virtual cathode in the drift space, including dominant frequency, electron transit time, position, and transmitted current, are yielded analytically. The relationship between the frequency of the virtual cathode oscillation and the injected current presented may explain previously reported numerical works. Results are significant in facilitating estimations and further analytical studies

  16. Metal-insulator transition in one-dimensional lattices with chaotic energy sequences

    International Nuclear Information System (INIS)

    Pinto, R.A.; Rodriguez, M.; Gonzalez, J.A.; Medina, E.

    2005-01-01

    We study electronic transport through a one-dimensional array of sites by using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic sequence. The correlation degree between these energies is controlled by a parameter regulating the dynamic Lyapunov exponent measuring the degree of chaos. We observe the effect of chaotic sequences on the localization length, conductance, conductance distribution and wave function, finding evidence of a metal-insulator transition (MIT) at a critical degree of chaos. The one-dimensional metallic phase is characterized by a Gaussian conductance distribution and exhibits a peculiar non-selfaveraging

  17. On the effect of memory in one-dimensional K=4 automata on networks

    Science.gov (United States)

    Alonso-Sanz, Ramón; Cárdenas, Juan Pablo

    2008-12-01

    The effect of implementing memory in cells of one-dimensional CA, and on nodes of various types of automata on networks with increasing degrees of random rewiring is studied in this article, paying particular attention to the case of four inputs. As a rule, memory induces a moderation in the rate of changing nodes and in the damage spreading, albeit in the latter case memory turns out to be ineffective in the control of the damage as the wiring network moves away from the ordered structure that features proper one-dimensional CA. This article complements the previous work done in the two-dimensional context.

  18. Hopping transport and electrical conductivity in one-dimensional systems with off-diagonal disorder

    International Nuclear Information System (INIS)

    Ma Songshan; Xu Hui; Li Yanfeng; Song Zhaoquan

    2007-01-01

    In this paper, we present a model to describe hopping transport and electrical conductivity of one-dimensional systems with off-diagonal disorder, in which electrons are transported via hopping between localized states. We find that off-diagonal disorder leads to delocalization and drastically enhances the electrical conductivity of systems. The model also quantitatively explains the temperature and electrical field dependence of the conductivity in one-dimensional systems with off-diagonal disorder. In addition, we also show the dependence of the conductivity on the strength of off-diagonal disorder

  19. Metal-insulator transition in one-dimensional lattices with chaotic energy sequences

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, R.A. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela)]. E-mail: ripinto@ivic.ve; Rodriguez, M. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela); Gonzalez, J.A. [Laboratorio de Fisica Computacional, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela); Medina, E. [Laboratorio de Fisica Estadistica, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020-A (Venezuela)

    2005-06-20

    We study electronic transport through a one-dimensional array of sites by using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic sequence. The correlation degree between these energies is controlled by a parameter regulating the dynamic Lyapunov exponent measuring the degree of chaos. We observe the effect of chaotic sequences on the localization length, conductance, conductance distribution and wave function, finding evidence of a metal-insulator transition (MIT) at a critical degree of chaos. The one-dimensional metallic phase is characterized by a Gaussian conductance distribution and exhibits a peculiar non-selfaveraging.

  20. An Auxiliary Equation for the Bellman Equation in a One-Dimensional Ergodic Control

    International Nuclear Information System (INIS)

    Fujita, Y.

    2001-01-01

    In this paper we consider the Bellman equation in a one-dimensional ergodic control. Our aim is to show the existence and the uniqueness of its solution under general assumptions. For this purpose we introduce an auxiliary equation whose solution gives the invariant measure of the diffusion corresponding to an optimal control. Using this solution, we construct a solution to the Bellman equation. Our method of using this auxiliary equation has two advantages in the one-dimensional case. First, we can solve the Bellman equation under general assumptions. Second, this auxiliary equation gives an optimal Markov control explicitly in many examples