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Sample records for beam ground state

  1. Surface modification using low energy ground state ion beams

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1990-01-01

    A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.

  2. Evaluation of the CINDI-C/NOFS Ram Wind Sensor in a Ground State Atomic Oxygen Beam

    NASA Astrophysics Data System (ADS)

    Roddy, P. A.; Earle, G. D.; Stephen, T. M.; Heelis, R. A.

    2003-04-01

    The Ram Wind Sensor (RWS) is a flow-through retarding potential analyzer equipped with an ionization source that is designed to measure the ram component of neutral particle energy. RWS and the Cross-track wind sensor (XTRK) function together as the Neutral Wind Meter (NWM) being developed for NASA's Coupled Ion-Neutral Dynamics Investigation (CINDI) that will enable in-situ measurements of the 3-D neutral wind field. The CINDI mission will be launched in late 2003 aboard the US Air Force's Communications/Navigation Outage Forecast System (C/NOFS) satellite. The efficiency, energy resolution, and angular variability of RWS are being tested in a ground state atomic oxygen (AO) beam facility at the University of Denver in order to simulate the space environment. The AO beam has energies variable from 4 eV to 1000 eV with a 1.5 eV FWHM energy distribution and fluxes on the order of 1012 atoms/cm2 s. The instrument being tested is mechanically identical to the CINDI flight instrument, but is equipped with pulse counting electronics to enable measurements in the low flux AO beam system. The results of these laboratory tests along with their implications for the precision, accuracy, and overall effectiveness of RWS and NWM will be presented.

  3. Annihilation detector for an in-beam spectroscopy apparatus to measure the ground state hyperfine splitting of antihydrogen

    NASA Astrophysics Data System (ADS)

    Sauerzopf, Clemens; Capon, Aaron A.; Diermaier, Martin; Fleck, Markus; Kolbinger, Bernadette; Malbrunot, Chloé; Massiczek, Oswald; Simon, Martin C.; Vamosi, Stefan; Zmeskal, Johann; Widmann, Eberhard

    2017-02-01

    The matter-antimatter asymmetry observed in the universe today still lacks a quantitative explanation. One possible mechanism that could contribute to the observed imbalance is a violation of the combined Charge-, Parity- and Time symmetries (CPT). A test of CPT symmetry using anti-atoms is being carried out by the ASACUSA-CUSP collaboration at the CERN Antiproton Decelerator using a low temperature beam of antihydrogen-the most simple atomic system built only of antiparticles. While hydrogen is the most abundant element in the universe, antihydrogen is produced in very small quantities in a laboratory framework. A detector for in-beam measurements of the ground state hyperfine structure of antihydrogen has to be able to detect very low signal rates within high background. To fulfil this challenging task, a two layer barrel hodoscope detector was developed. It is built of plastic scintillators with double sided readout via Silicon Photomultipliers (SiPMs). The SiPM readout is done using novel, compact and cost efficient electronics that incorporate power supply, amplifier and discriminator on a single board. This contribution will evaluate the performance of the new hodoscope detector.

  4. Crossed Molecular Beam Study on the Ground State Reaction of Atomic Boron [B(P-2(j))] with Hydrogen Cyanide [HCN(X-1 Sigma(+))

    NASA Astrophysics Data System (ADS)

    Jones, Brant; Matsyutenko, Pavlo; Su, Nung C.; Chang, Agnes H. H.; Kaiser, Ralf I.

    2010-09-01

    The linear boronisocyanide species, [BNC(X(1)Sigma(+))], represents the simplest triatomic molecule with three distinct, neighboring main group atoms of the second row of the periodic table of the elements: boron, carbon, and nitrogen. This makes boronisocyanide a crucial benchmark system to understand the chemical bonding and the electronic structure of small molecules, in particular when compared to the isoelectronic tricarbon molecule, [CCC(X(1)Sigma(g)(+))]. However, a clean, directed synthesis of boronisocyanide-a crucial prerequisite to study the properties of this molecule-has remained elusive so far. Here, we combine crossed molecular beam experiments of ground state boron atoms ((2)P(j)) with hydrogen cyanide with electronic structure calculations and reveal that the boronisocyanide molecule, [BNC(X(1)Sigma(+))], is formed as the exclusive product under gas phase single collision conditions. We also show that higher energy isomers such as the hitherto unnoticed, ring-strained cyclic BNC(X(3)A') structure, which is isoelectronic to the triplet, cyclic tricarbon molecule, [C(3)(X(3)A(2)')], do exist as local minima. Our studies present the first directed synthesis and observation of gas phase boronisocyanide providing a doorway for further fundamental studies on one of the simplest triatomic molecules composed solely of group III-V elements.

  5. Molecular beam studies of weak interactions for open-shell systems: The ground and lowest excited states of ArF, KrF, and XeF

    SciTech Connect

    Aquilanti, V.; Luzzatti, E.; Pirani, F.; Volpi, G.G.

    1988-11-15

    Absolute integral cross sections for scattering of ground state fluorine atoms by argon, krypton, and xenon have been measured in the thermal velocity range. Information has been obtained on the long range interaction and using a technique for magnetic analysis of substates of F atoms, a characterization is given for the bonding in the ground and the two lowest excited states of these rare gas fluorides. The potentials are represented as a spherical part and an anisotropic component, which have been obtained in an adiabatic decoupling treatment, including also information from other scattering data. Nonadiabatic coupling matrix elements and other general features of these interactions are also presented.

  6. Ground states of holographic superconductors

    SciTech Connect

    Gubser, Steven S.; Nellore, Abhinav

    2009-11-15

    We investigate the ground states of the Abelian Higgs model in AdS{sub 4} with various choices of parameters, and with no deformations in the ultraviolet other than a chemical potential for the electric charge under the Abelian gauge field. For W-shaped potentials with symmetry-breaking minima, an analysis of infrared asymptotics suggests that the ground state has emergent conformal symmetry in the infrared when the charge of the complex scalar is large enough. But when this charge is too small, the likeliest ground state has Lifshitz-like scaling in the infrared. For positive mass quadratic potentials, Lifshitz-like scaling is the only possible infrared behavior for constant nonzero values of the scalar. The approach to Lifshitz-like scaling is shown in many cases to be oscillatory.

  7. Ground-state Dirac monopole

    SciTech Connect

    Ruokokoski, E.; Moettoenen, M.

    2011-12-15

    We show theoretically that a monopole defect, analogous to the Dirac magnetic monopole, may exist as the ground state of a dilute spin-1 Bose-Einstein condensate. The ground-state monopole is not attached to a single semi-infinite Dirac string but forms a point where the circulation of a single vortex line is reversed. Furthermore, the three-dimensional dynamics of this monopole defect is studied after the magnetic field pinning the monopole is removed and the emergence of antimonopoles is observed. Our scheme is realizable with the current experimental facilities.

  8. Molecular beam studies of weak interactions for open-shell systems: The ground and lowest excited states of rare gas oxides

    SciTech Connect

    Aquilanti, V.; Candori, R.; Pirani, F.

    1988-11-15

    Integral cross sections as a function of velocity for scattering of ground state oxygen atoms by the rare gases have been measured at thermal energy. Analysis of atomic sublevels by a Stern--Gerlach magnet allows a control of the relative contribution from different fine structure scattering channels. The results are analyzed using an adiabatic decoupling scheme to derive the interaction as a spherical part and an anisotropic component, from which information is obtained on the six lowest states of the rare gas oxides and on nonadiabatic coupling terms.

  9. Moving Toward the Ground State.

    PubMed

    Kumar, Ishan; Ivanova, Natalia

    2015-10-01

    Transferring mouse ESCs to a media supplemented with Mek and Gsk3β inhibitors (2i) provokes marked transcriptional and epigenetic changes, embodying a shift toward ground-state pluripotency. In this issue of Cell Stem Cell, Kolodziejczyk et al. (2015) examine population structures of ESCs while Galonska et al. (2015) unravel the mechanisms underlying regulatory network rewiring during 2i-mediated reprogramming. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Ground Base Skylab Electron Beam Welds in Tantalum

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Comparison of ground-based (left) and Skylab (right) electron beam welds in pure tantalum (Ta) (10X magnification). Residual votices left behind in the ground-based sample after the electron beam passed were frozen into the grain structure. These occurred because of the rapid cooling rate at the high temperature. Although the thermal characteristics and electron beam travel speeds were comparable for the skylab sample, the residual vortices were erased in the grain structure. This may have been due to the fact that final grain size of the solidified material was smaller in the Skylab sample compared to the ground-based sample. The Skylab sample was processed in the M512 Materials Processing Facility (MPF) during Skylab SL-2 Mission. Principal Investigator was Richard Poorman.

  11. A facility to produce an energetic, ground state atomic oxygen beam for the simulation of the Low-Earth Orbit environment

    NASA Technical Reports Server (NTRS)

    Ketsdever, Andrew D.; Weaver, David P.; Muntz, E. P.

    1994-01-01

    Because of the continuing commitment to activity in low-Earth orbit (LEO), a facility is under development to produce energetic atmospheric species, particularly atomic oxygen, with energies ranging from 5 to 80 eV. This relatively high flux facility incorporates an ion engine to produce the corresponding specie ion which is charge exchanged to produce a neutral atomic beam. Ion fluxes of around 10(exp 15) sec(exp -1) with energies of 20-70 eV have been achieved. A geometrically augmented inertially tethered charge exchanger (GAITCE) was designed to provide a large column depth of charge exchange gas while reducing the gas load to the low pressure portion of the atomic beam facility. This is accomplished using opposed containment jets which act as collisional barriers to the escape of the dense gas region formed between the jets. Leak rate gains to the pumping system on the order of 10 were achieved for moderate jet mass flows. This system provides an attractive means for the charge exchange of atomic ions with a variety of gases to produce energetic atomic beams.

  12. Guided-Ion-Beam and ab Initio Study of the Li+, K+, and Rb+ Association Reactions with Gas-Phase Butanone and Cyclohexanone in Their Ground Electronic States

    NASA Astrophysics Data System (ADS)

    Lucas, J. M.; de Andrés, J.; López, E.; Albertí, M.; Bofill, J. M.; Bassi, D.; Ascenzi, D.; Tosi, P.; Aguilar, A.

    2009-08-01

    The association reactions between Li+, K+, and Rb+ (M) and butanone and cyclohexanone molecules under single collision conditions have been studied using a radiofrequency-guided ion-beam apparatus, characterizing the adducts by mass spectrometry. The excitation function for the [M-(molecule)]+ adducts (in arbitrary units) has been obtained at low collision energies in the 0.10 eV up to a few eV range in the center of mass frame. The measured relative cross sections decrease when collision energy increases, showing the expected energy dependence for adduct formation. The energetics and structure of the different adducts have been calculated ab initio at the MP2(full) level, showing that the M+-molecule interaction takes place through the carbonyl oxygen atom, as an example of a nontypical covalent chemical bond. The cross-section energy dependence and the role of radiative cooling rates allowing the stabilization of the collision complexes are also discussed.

  13. Ion beam analysis of ground coffee and roasted coffee beans

    NASA Astrophysics Data System (ADS)

    Debastiani, R.; dos Santos, C. E. I.; Yoneama, M. L.; Amaral, L.; Dias, J. F.

    2014-01-01

    The way that coffee is prepared (using roasted ground coffee or roasted coffee beans) may influence the quality of beverage. Therefore, the aim of this work is to use ion beam techniques to perform a full elemental analysis of packed roasted ground coffee and packed roasted coffee beans, as well as green coffee beans. The samples were analyzed by PIXE (particle-induced X-ray emission). Light elements were measured through RBS (Rutherford backscattering spectrometry) experiments. Micro-PIXE experiments were carried out in order to check the elemental distribution in the roasted and green coffee beans. In general, the elements found in ground coffee were Mg, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Rb and Sr. A comparison between ground coffee and grinded roasted beans shows significant differences for several elements. Elemental maps reveal that P and K are correlated and practically homogeneously distributed over the beans.

  14. Ground states for nonuniform periodic Ising chains.

    PubMed

    Martínez-Garcilazo, J P; Ramírez, C

    2015-04-01

    We generalize Morita's works [J. Phys. A 7, 289 (1974); J. Phys. A 7, 1613 (1974)] on ground states of Ising chains, for chains with a periodic structure and different spins, to any interaction order. The main assumption is translational invariance. The length of the irreducible blocks is a multiple of the period of the chain. If there is parity invariance, it restricts the length in general only in the diatomic case. There are degenerated states and under certain circumstances there could be nonregular ground states. We illustrate the results and give the ground state diagrams in several cases.

  15. Macroscopic Superpositions as Quantum Ground States

    NASA Astrophysics Data System (ADS)

    Dakić, Borivoje; Radonjić, Milan

    2017-09-01

    We study the question of what kind of a macroscopic superposition can(not) naturally exist as a ground state of some gapped local many-body Hamiltonian. We derive an upper bound on the energy gap of an arbitrary physical Hamiltonian provided that its ground state is a superposition of two well-distinguishable macroscopic "semiclassical" states. For a large class of macroscopic superposition states we show that the gap vanishes in the macroscopic limit. This in turn shows that preparation of such states by simple cooling to the ground state is not experimentally feasible and requires a different strategy. Our approach is very general and can be used to rule out a variety of quantum states, some of which do not even exhibit macroscopic quantum properties. Moreover, our methods and results can be used for addressing quantum marginal related problems.

  16. Variable energy, high flux, ground-state atomic oxygen source

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Orient, Otto J. (Inventor)

    1987-01-01

    A variable energy, high flux atomic oxygen source is described which is comprised of a means for producing a high density beam of molecules which will emit O(-) ions when bombarded with electrons; a means of producing a high current stream of electrons at a low energy level passing through the high density beam of molecules to produce a combined stream of electrons and O(-) ions; means for accelerating the combined stream to a desired energy level; means for producing an intense magnetic field to confine the electrons and O(-) ions; means for directing a multiple pass laser beam through the combined stream to strip off the excess electrons from a plurality of the O(-) ions to produce ground-state O atoms within the combined stream; electrostatic deflection means for deflecting the path of the O(-) ions and the electrons in the combined stream; and, means for stopping the O(-) ions and the electrons and for allowing only the ground-state O atoms to continue as the source of the atoms of interest. The method and apparatus are also adaptable for producing other ground-state atoms and/or molecules.

  17. Triplet (S = 1) Ground State Aminyl Diradical

    SciTech Connect

    Rajca, Andrzej; Shiraishi, Kouichi; Pink, Maren; Rajca, Suchada

    2008-04-02

    Aminyl diradical, which is stable in solution at low temperatures, is prepared. EPR spectra and SQUID magnetometry indicate that the diradical is planar and it possesses triplet ground state, with strong ferromagnetic coupling.

  18. On the ground state of metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Chakravarty, S.; Ashcroft, N. W.

    1978-01-01

    A proposed liquid ground state of metallic hydrogen at zero temperature is explored and a variational upper bound to the ground state energy is calculated. The possibility that the metallic hydrogen is a liquid around the metastable point (rs = 1.64) cannot be ruled out. This conclusion crucially hinges on the contribution to the energy arising from the third order in the electron-proton interaction which is shown here to be more significant in the liquid phase than in crystals.

  19. Lattice QCD Beyond Ground States

    SciTech Connect

    Huey-Wen Lin; Saul D. Cohen

    2007-09-11

    In this work, we apply black box methods (methods not requiring input) to find excited-state energies. A variety of such methods for lattice QCD were introduced at the 3rd iteration of the numerical workshop series. We first review a selection of approaches that have been used in lattice calculations to determine multiple energy states: multiple correlator fits, the variational method and Bayesian fitting. In the second half, we will focus on a black box method, the multi-effective mass. We demonstrate the approach on a toy model, as well as on real lattice data, extracting multiple states from single correlators. Without complicated operator construction or specialized fitting programs, the black box method shows good consistency with the traditional approaches.

  20. Mimicking time evolution within a quantum ground state: Ground-state quantum computation, cloning, and teleportation

    SciTech Connect

    Mizel, Ari

    2004-07-01

    Ground-state quantum computers mimic quantum-mechanical time evolution within the amplitudes of a time-independent quantum state. We explore the principles that constrain this mimicking. A no-cloning argument is found to impose strong restrictions. It is shown, however, that there is flexibility that can be exploited using quantum teleportation methods to improve ground-state quantum computer design.

  1. Ground states for nonuniform periodic Ising chains

    NASA Astrophysics Data System (ADS)

    Martínez-Garcilazo, J. P.; Ramírez, C.

    2015-04-01

    We generalize Morita's works [J. Phys. A 7, 289 (1974), 10.1088/0305-4470/7/2/014; J. Phys. A 7, 1613 (1974), 10.1088/0305-4470/7/13/015] on ground states of Ising chains, for chains with a periodic structure and different spins, to any interaction order. The main assumption is translational invariance. The length of the irreducible blocks is a multiple of the period of the chain. If there is parity invariance, it restricts the length in general only in the diatomic case. There are degenerated states and under certain circumstances there could be nonregular ground states. We illustrate the results and give the ground state diagrams in several cases.

  2. Applications of power beaming from space-based nuclear power stations. [Laser beaming to airplanes; microwave beaming to ground

    SciTech Connect

    Powell, J.R.; Botts, T.E.; Hertzberg, A.

    1981-01-01

    Power beaming from space-based reactor systems is examined using an advanced compact, lightweight Rotating Bed Reactor (RBR). Closed Brayton power conversion efficiencies in the range of 30 to 40% can be achieved with turbines, with reactor exit temperatures on the order of 2000/sup 0/K and a liquid drop radiator to reject heat at temperatures of approx. 500/sup 0/K. Higher RBR coolant temperatures (up to approx. 3000/sup 0/K) are possible, but gains in power conversion efficiency are minimal, due to lower expander efficiency (e.g., a MHD generator). Two power beaming applications are examined - laser beaming to airplanes and microwave beaming to fixed ground receivers. Use of the RBR greatly reduces system weight and cost, as compared to solar power sources. Payback times are a few years at present prices for power and airplane fuel.

  3. Numerical Evaluation of 2D Ground States

    NASA Astrophysics Data System (ADS)

    Kolkovska, Natalia

    2016-02-01

    A ground state is defined as the positive radial solution of the multidimensional nonlinear problem \\varepsilon propto k_ bot 1 - ξ with the function f being either f(u) =a|u|p-1u or f(u) =a|u|pu+b|u|2pu. The numerical evaluation of ground states is based on the shooting method applied to an equivalent dynamical system. A combination of fourth order Runge-Kutta method and Hermite extrapolation formula is applied to solving the resulting initial value problem. The efficiency of this procedure is demonstrated in the 1D case, where the maximal difference between the exact and numerical solution is ≈ 10-11 for a discretization step 0:00025. As a major application, we evaluate numerically the critical energy constant. This constant is defined as a functional of the ground state and is used in the study of the 2D Boussinesq equations.

  4. Cavity optomechanics -- beyond the ground state

    NASA Astrophysics Data System (ADS)

    Meystre, Pierre

    2011-05-01

    The coupling of coherent optical systems to micromechanical devices, combined with breakthroughs in nanofabrication and in ultracold science, has opened up the exciting new field of cavity optomechanics. Cooling of the vibrational motion of a broad range on oscillating cantilevers and mirrors near their ground state has been demonstrated, and the ground state of at least one such system has now been reached. Cavity optomechanics offers much promise in addressing fundamental physics questions and in applications such as the detection of feeble forces and fields, or the coherent control of AMO systems and of nanoscale electromechanical devices. However, these applications require taking cavity optomechanics ``beyond the ground state.'' This includes the generation and detection of squeezed and other non-classical states, the transfer of squeezing between electromagnetic fields and motional quadratures, and the development of measurement schemes for the characterization of nanomechanical structures. The talk will present recent ``beyond ground state'' developments in cavity optomechanics. We will show how the magnetic coupling between a mechanical membrane and a BEC - or between a mechanical tuning fork and a nanoscale cantilever - permits to control and monitor the center-of-mass position of the mechanical system, and will comment on the measurement back-action on the membrane motion. We will also discuss of state transfer between optical and microwave fields and micromechanical devices. Work done in collaboration with Dan Goldbaum, Greg Phelps, Keith Schwab, Swati Singh, Steve Steinke, Mehmet Tesgin, and Mukund Vengallatore and supported by ARO, DARPA, NSF, and ONR.

  5. Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

    2007-01-01

    Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

  6. Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

    2007-01-01

    Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

  7. Individual Atoms in their Quantum Ground State

    NASA Astrophysics Data System (ADS)

    Schwartz, Eyal; Sompet, Pimonpan; Fung, Yin Hsien; Andersen, Mikkel F.

    2016-05-01

    An ultimate control of pure quantum states is an excellent platform for various quantum science and engineering. In this work, we perform quantum manipulation of individual Rubidium atoms in a tightly focus optical tweezer in order to cool them into their vibrational ground state via Raman sideband cooling. Our experimental scheme involves a combination of Raman sideband transitions and optical pumping of the atoms that couples two magnetic field sublevels indifferent to magnetic noise thus providing a much longer atomic coherence time compared to previous cooling schemes. By installing most of the atoms in their ground state, we managed to achieve two-dimensional cooling on the way to create a full nil entropy quantum state of single atoms and single molecules. We acknowledge the Marsden Fund, CORE and DWC for their support.

  8. Ground-state electromagnetic moments of calcium isotopes

    NASA Astrophysics Data System (ADS)

    Ruiz, R. F. Garcia; Bissell, M. L.; Blaum, K.; Frömmgen, N.; Hammen, M.; Holt, J. D.; Kowalska, M.; Kreim, K.; Menéndez, J.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Nowacki, F.; Papuga, J.; Poves, A.; Schwenk, A.; Simonis, J.; Yordanov, D. T.

    2015-04-01

    Background: The neutron-rich calcium isotopes have gained particular interest as evidence of closed-shell structures has recently been found in two exotic nuclei, at N =32 and N =34 . Additionally, the study of such neutron-rich systems has revealed new aspects of nuclear forces, in particular regarding the role of three-nucleon forces. Purpose: We study the electromagnetic properties of Ca isotopes around the neutron number N =32 . Methods: High-resolution bunched-beam collinear laser spectroscopy was used to measure the optical hyperfine spectra of the Ca-5143 isotopes. Results: The ground-state magnetic moments of Ca,5149 and quadrupole moments of Ca 47 ,49 ,51 were measured for the first time, and the 51Ca ground-state spin I = 3 /2 was determined in a model-independent way. Our experimental results are compared with state-of-the-art shell-model calculations using both phenomenological interactions and microscopic interactions derived from chiral effective field theory. Conclusions: The results for the ground-state moments of neutron-rich isotopes are in excellent agreement with predictions of interactions derived from chiral effective field theory including three-nucleon forces. Lighter isotopes illustrate the presence of particle-hole excitations of the 40Ca core in their ground state. Our results provide a critical test of modern nuclear theories, and give direct answer to the evolution of ground-state electromagnetic properties in the Ca isotopic chain across three doubly closed-shell configurations at N =20 , 28, 32 of this unique system.

  9. Trapping cold ground state argon atoms.

    PubMed

    Edmunds, P D; Barker, P F

    2014-10-31

    We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

  10. Intense steady state electron beam generator

    DOEpatents

    Hershcovitch, Ady; Kovarik, Vincent J.; Prelec, Krsto

    1990-01-01

    An intense, steady state, low emittance electron beam generator is formed by operating a hollow cathode discharge plasma source at critical levels in combination with an extraction electrode and a target electrode that are operable to extract a beam of fast primary electrons from the plasma source through a negatively biased grid that is critically operated to repel bulk electrons toward the plasma source while allowing the fast primary electrons to move toward the target in the desired beam that can be successfully transported for relatively large distances, such as one or more meters away from the plasma source.

  11. Triaxiality near the 110Ru ground state from Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.

    2017-03-01

    A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.

  12. Triaxiality near the 110Ru ground state from Coulomb excitation

    DOE PAGES

    Doherty, D. T.; Allmond, James M.; Janssens, R. V. F.; ...

    2017-01-20

    A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.

  13. First Observation of Ground State Dineutron Decay: Be16

    NASA Astrophysics Data System (ADS)

    Spyrou, A.; Kohley, Z.; Baumann, T.; Bazin, D.; Brown, B. A.; Christian, G.; Deyoung, P. A.; Finck, J. E.; Frank, N.; Lunderberg, E.; Mosby, S.; Peters, W. A.; Schiller, A.; Smith, J. K.; Snyder, J.; Strongman, M. J.; Thoennessen, M.; Volya, A.

    2012-03-01

    We report on the first observation of dineutron emission in the decay of Be16. A single-proton knockout reaction from a 53MeV/u B17 beam was used to populate the ground state of Be16. Be16 is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of Be16 was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region.

  14. Ground state structures in ferrofluid monolayers.

    PubMed

    Prokopieva, Taisia A; Danilov, Victor A; Kantorovich, Sofia S; Holm, Christian

    2009-09-01

    A combination of analytical calculations and Monte Carlo simulations is used to find the ground state structures in monodisperse ferrofluid monolayers. Taking into account the magnetic dipole-dipole interaction between all particles in the system we observe different topological structures that are likely to exist at low temperatures. The most energetically favored structures we find are rings, embedded rings, and rings side by side, and we are able to derive analytical expressions for the total energy of these structures. A detailed analysis of embedded rings and rings side by side shows that the interring interactions are negligible. We furthermore find that a single ideal ring is the ground state structure for a ferrofluid monolayer. We compared our theoretical predictions to the results of simulated annealing data and found them to be in excellent agreement.

  15. Electronic ground state of Ni2+

    NASA Astrophysics Data System (ADS)

    Zamudio-Bayer, V.; Lindblad, R.; Bülow, C.; Leistner, G.; Terasaki, A.; v. Issendorff, B.; Lau, J. T.

    2016-11-01

    The 9/2 4Φ ground state of the Ni2+ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of 7.4 ±0.2 K was reached by buffer gas cooling of the molecular ion. The contribution of the spin dipole operator to the x-ray magnetic circular dichroism spin sum rule amounts to 7 Tz =0.17 ± 0.06 μB per atom, approximately 11% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of 3d transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.

  16. Ground state energy of large polaron systems

    SciTech Connect

    Benguria, Rafael D.; Frank, Rupert L.; Lieb, Elliott H.

    2015-02-15

    The last unsolved problem about the many-polaron system, in the Pekar–Tomasevich approximation, is the case of bosons with the electron-electron Coulomb repulsion of strength exactly 1 (the “neutral case”). We prove that the ground state energy, for large N, goes exactly as −N{sup 7/5}, and we give upper and lower bounds on the asymptotic coefficient that agree to within a factor of 2{sup 2/5}.

  17. Ground state searches in fcc intermetallics

    SciTech Connect

    Wolverton, C.; de Fontaine, D.; Ceder, G.; Dreysse, H.

    1991-12-01

    A cluster expansion is used to predict the fcc ground states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. The intermetallic structures are not assumed, but derived regorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearized-muffin-tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration.

  18. Ground state searches in fcc intermetallics

    SciTech Connect

    Wolverton, C.; de Fontaine, D. ); Ceder, G. ); Dreysse, H. . Lab. de Physique du Solide)

    1991-12-01

    A cluster expansion is used to predict the fcc ground states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. The intermetallic structures are not assumed, but derived regorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearized-muffin-tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration.

  19. Ground Water Atlas of the United States

    USGS Publications Warehouse

    ,

    2000-01-01

    PrefaceThe Ground Water Atlas of the United States presents a comprehensive summary of the Nation's ground-water resources and is a basic reference for the location, geography, geology, and hydrologic characteristics of the major aquifers in the Nation. The information was collected by the U.S. Geological Survey and other agencies during the course of many years of study. Results of the Regional Aquifer-System Analysis Program, a systematic study of the Nation's major aquifers by the U.S. Geological Survey, were used as a major, but not exclusive, source of information of the Atlas. The Atlas, which is designed in a graphical format that is supported by descriptive discussions, includes 13 chapters, each representing areas that collectively cover the 50 States and Puerto Rico, as well as the U.S. Virgin Islands. Each chapter of the Atlas presents and describes hydrogeologic and hydrologic conditions for the major aquifers in each regional area. The scale of the Atlas does not allow portrayal of minor features of the geology or hydrology of each aquifer presented, nor does it include detailed discussion of minor aquifers. Those readers who seek detailed local information for the aquifers will find extensive lists of references at the end of each chapter. The introductory chapter in this volume presents an overview of ground-water conditions Nationwide and gives an example of an aquifer in each of six hydrogeologic settings.

  20. The polaron: Ground state, excited states, and far from equilibrium

    SciTech Connect

    Trugman, S.A.; Bonca, J. |

    1998-12-01

    The authors describe a variational approach for solving the Holstein polaron model with dynamical quantum phonons on an infinite lattice. The method is simple, fast, extremely accurate, and gives ground and excited state energies and wavefunctions at any momentum k. The method can also be used to calculate coherent quantum dynamics for inelastic tunneling and for strongly driven polarons far from equilibrium.

  1. Ground-state structures of Hafnium clusters

    SciTech Connect

    Ng, Wei Chun; Yoon, Tiem Leong; Lim, Thong Leng

    2015-04-24

    Hafnium (Hf) is a very large tetra-valence d-block element which is able to form relatively long covalent bond. Researchers are interested to search for substitution to silicon in the semi-conductor industry. We attempt to obtain the ground-state structures of small Hf clusters at both empirical and density-functional theory (DFT) levels. For calculations at the empirical level, charge-optimized many-body functional potential (COMB) is used. The lowest-energy structures are obtained via a novel global-minimum search algorithm known as parallel tempering Monte-Carlo Basin-Hopping and Genetic Algorithm (PTMBHGA). The virtue of using COMB potential for Hf cluster calculation lies in the fact that by including the charge optimization at the valence shells, we can encourage the formation of proper bond hybridization, and thus getting the correct bond order. The obtained structures are further optimized using DFT to ensure a close proximity to the ground-state.

  2. Optical pumping of metastable NH radicals into the paramagnetic ground state

    SciTech Connect

    Meerakker, Sebastiaan Y.T. van de; Mosk, Allard P.; Jongma, Rienk T.; Sartakov, Boris G.; Meijer, Gerard

    2003-09-01

    We here report on the optical pumping of both {sup 14}NH and {sup 15}NH radicals from the metastable a {sup 1}{delta} state into the X {sup 3}{sigma}{sup -} ground state in a molecular beam experiment. By inducing the hitherto unobserved spin-forbidden A {sup 3}{pi} <- a {sup 1}{delta} transition, followed by spontaneous emission to the X {sup 3}{sigma}{sup -} state, a unidirectional pathway for population transfer from the metastable state into the electronic ground state is obtained. The optical pumping scheme demonstrated here opens up the possibility to accumulate NH radicals in a magnetic or optical trap.

  3. Vector Beam Polarization State Spectrum Analyzer.

    PubMed

    Moreno, Ignacio; Davis, Jeffrey A; Badham, Katherine; Sánchez-López, María M; Holland, Joseph E; Cottrell, Don M

    2017-05-22

    We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from -3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.

  4. An experimental guided-ion-beam and ab initio study of the ion-molecule gas-phase reactions between Li{sup +} ions and iso-C{sub 3}H{sub 7}Cl in their ground electronic state

    SciTech Connect

    Lucas, J. M.; Andres, J. de; Sogas, J.; Alberti, M.; Aguilar, A.; Bofill, J. M.; Bassi, D.; Ascenzi, D.; Tosi, P.

    2009-07-14

    Reactive collisions between Li{sup +} ions and i-C{sub 3}H{sub 7}Cl molecules have been studied in the 0.20-12.00 eV center-of-mass energy range using an octopole radio frequency guided-ion beam apparatus recently developed in our laboratory. At low collision energies, dehydrohalogenation reactions giving rise to Li(C{sub 3}H{sub 6}){sup +} and Li(HCl){sup +} are the main reaction channels, while at higher ones C{sub 3}H{sub 7}{sup +} and C{sub 2}H{sub 3}{sup +} become dominant, all their reactive cross sections having been measured as a function of the collision energy. To obtain information about the potential energy surfaces (PESs) on which the reactive processes take place, ab initio calculations at the MP2 level have been performed. For dehydrohalogenations, the reactive ground singlet PES shows ion-molecule adduct formation in both the reactant and product sides of the surface. Following the minimum energy path connecting both minima, an unstable intermediate and the corresponding barriers, both lying below the reactant's energy, have been characterized. The entrance channel ion-molecule adduct is also involved in the formation of C{sub 3}H{sub 7}{sup +}, which then generates C{sub 2}H{sub 3}{sup +} via an CH{sub 4} unimolecular elimination. A qualitative interpretation of the experimental results based on ab initio calculations is also included.

  5. Thermodynamic ground states of platinum metal nitrides

    SciTech Connect

    Aberg, D; Sadigh, B; Crowhurst, J; Goncharov, A

    2007-10-09

    We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.

  6. Ground-state energies of simple metals

    NASA Technical Reports Server (NTRS)

    Hammerberg, J.; Ashcroft, N. W.

    1974-01-01

    A structural expansion for the static ground-state energy of a simple metal is derived. Two methods are presented, one an approach based on single-particle band structure which treats the electron gas as a nonlinear dielectric, the other a more general many-particle analysis using finite-temperature perturbation theory. The two methods are compared, and it is shown in detail how band-structure effects, Fermi-surface distortions, and chemical-potential shifts affect the total energy. These are of special interest in corrections to the total energy beyond third order in the electron-ion interaction and hence to systems where differences in energies for various crystal structures are exceptionally small. Preliminary calculations using these methods for the zero-temperature thermodynamic functions of atomic hydrogen are reported.

  7. Ground state of high-density matter

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Kolb, Edward W.; Lee, Kimyeong

    1988-01-01

    It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.

  8. Advantages of ground-to-space laser power beaming

    NASA Technical Reports Server (NTRS)

    Rather, John D. G.

    1992-01-01

    NASA's current research activities to evaluate laser power beaming systems are reviewed. Applications of such systems are considered, including communications satellites, radar and direct broadcast satellites, space transfer vehicles lunar base operations and exploration, and optical technologies. The current laser power beaming program within the NASA Headquarters Office of Aeronautics and Space Technology is addressed.

  9. Effect of spatial coherence on laser beam self-focusing from orbit to the ground in the atmosphere.

    PubMed

    Deng, Hanling; Ji, Xiaoling; Li, Xiaoqing; Zhang, Hao; Wang, Xianqu; Zhang, Yuqiu

    2016-06-27

    The effect of spatial coherence on laser beam self-focusing in the atmosphere to assist delivering powerful laser beams from orbit to the ground is studied. It is found that a fully coherent beam is more strongly compressed on the ground than a partially (spatial) coherent beam (PCB), even so, for a PCB the compressed spot size on the ground may be reduced below the diffraction limit due to self-focusing effect, and a PCB has higher threshold critical power than a fully coherent beam. Furthermore, an effective design rule for maximal compression without beam splitting of the transported PCB from orbit to the ground is presented.

  10. Ground state energy of N Frenkel excitons

    NASA Astrophysics Data System (ADS)

    Pogosov, W.; Combescot, M.

    2009-03-01

    By using the composite many-body theory for Frenkel excitons we have recently developed, we here derive the ground state energy of N Frenkel excitons in the Born approximation through the Hamiltonian mean value in a state made of N identical Q = 0 excitons. While this quantity reads as a density expansion in the case of Wannier excitons, due to many-body effects induced by fermion exchanges between N composite particles, we show that the Hamiltonian mean value for N Frenkel excitons only contains a first order term in density, just as for elementary bosons. Such a simple result comes from a subtle balance, difficult to guess a priori, between fermion exchanges for two or more Frenkel excitons appearing in Coulomb term and the ones appearing in the N exciton normalization factor - the cancellation being exact within terms in 1/Ns where Ns is the number of atomic sites in the sample. This result could make us naively believe that, due to the tight binding approximation on which Frenkel excitons are based, these excitons are just bare elementary bosons while their composite nature definitely appears at various stages in the precise calculation of the Hamiltonian mean value.

  11. On the Stable Ground State of Mackinawite

    NASA Astrophysics Data System (ADS)

    Kwon, K.; Refson, K.; Sposito, G.

    2009-12-01

    Mackinawite is a layer type iron monosulfide (FeS) with stacked sheets of edge-sharing FeS4 tetrahedra. An important player in iron and sulfur cycles, mackinawite is one of the first-formed metastable iron sulfides in anoxic environments, transforming into greigite (Fe3S4) and pyrite (FeS2) minerals or elemental sulfur (S0) and iron (Fe0) depending on redox conditions. Mackinawite also affects the mobility and oxidation states of toxic metals such as As, Hg, and Se. The mineral, typically found as a nanoparticle, has been characterized experimentally. Its fundamental conducting and magnetic properties, however, are still controversial; e.g., whether mackinawite is metallic and whether it has magnetic order. Mackinawite is believed to be metallic and without magnetic ordering down at 4 K based on Mössbauer spectroscopy studies. We examined these two issues by applying plane-wave density functional theory (DFT) to FeS geometry optimization under different magnetic orderings. We found that antiferromagnetic ordering among the Fe atoms is the stable ground state of mackinawite. In this presentation, we shall discuss this result and how it relates to previous experimental work.

  12. Strangeness in the baryon ground states

    NASA Astrophysics Data System (ADS)

    Semke, A.; Lutz, M. F. M.

    2012-10-01

    We compute the strangeness content of the baryon octet and decuplet states based on an analysis of recent lattice simulations of the BMW, PACS, LHPC and HSC groups for the pion-mass dependence of the baryon masses. Our results rely on the relativistic chiral Lagrangian and large-Nc sum rule estimates of the counter terms relevant for the baryon masses at N3LO. A partial summation is implied by the use of physical baryon and meson masses in the one-loop contributions to the baryon self energies. A simultaneous description of the lattice results of the BMW, LHPC, PACS and HSC groups is achieved. From a global fit we determine the axial coupling constants F ≃ 0.45 and D ≃ 0.80 in agreement with their values extracted from semi-leptonic decays of the baryons. Moreover, various flavor symmetric limits of baron octet and decuplet masses as obtained by the QCDSF-UKQCD group are recovered. We predict the pion- and strangeness sigma terms and the pion-mass dependence of the octet and decuplet ground states at different strange quark masses.

  13. Influence of beam wander on uplink of ground-to-satellite laser communication and optimization for transmitter beam radius.

    PubMed

    Guo, Hong; Luo, Bin; Ren, Yongxiong; Zhao, Sinan; Dang, Anhong

    2010-06-15

    We restudy the influence of beam wander on the uplink of ground-to-satellite laser communication, using the effective pointing error method, for a collimated untracked Gaussian beam under a weak atmospheric turbulence condition. It shows that the beam wander may cause significant increase in bit error rate (BER), and there exists an optimal transmitter radius for minimizing the value of BER. Further studies manifest that this optimal radius only changes with the laser wavelength and zenith angle, while independent on the satellite altitude and the fade threshold at the receiver. These results can be used in system design and optimization for the transmitter.

  14. Is the ground state of Yang-Mills theory Coulombic?

    SciTech Connect

    Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D.; Lutz, W.

    2008-08-01

    We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-Abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.

  15. Magnetic ground state of FeSe

    PubMed Central

    Wang, Qisi; Shen, Yao; Pan, Bingying; Zhang, Xiaowen; Ikeuchi, K.; Iida, K.; Christianson, A. D.; Walker, H. C.; Adroja, D. T.; Abdel-Hafiez, M.; Chen, Xiaojia; Chareev, D. A.; Vasiliev, A. N.; Zhao, Jun

    2016-01-01

    Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors exhibit Néel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts=90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here we report inelastic neutron-scattering experiments that reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ∼60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S=1 nematic quantum-disordered paramagnet interpolating between the Néel and stripe magnetic instabilities. PMID:27431986

  16. Magnetic ground state of FeSe.

    PubMed

    Wang, Qisi; Shen, Yao; Pan, Bingying; Zhang, Xiaowen; Ikeuchi, K; Iida, K; Christianson, A D; Walker, H C; Adroja, D T; Abdel-Hafiez, M; Chen, Xiaojia; Chareev, D A; Vasiliev, A N; Zhao, Jun

    2016-07-19

    Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors exhibit Néel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts=90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here we report inelastic neutron-scattering experiments that reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ∼60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S=1 nematic quantum-disordered paramagnet interpolating between the Néel and stripe magnetic instabilities.

  17. Neutrino ground state in a dense star

    SciTech Connect

    Kiers, K.; Tytgat, M.H. |

    1998-05-01

    It has recently been argued that long range forces due to the exchange of massless neutrinos give rise to a very large self-energy in a dense, finite-ranged, weakly charged medium. Such an effect, if real, would destabilize a neutron star. To address this issue we have studied the related problem of a massless neutrino field in the presence of an external, static electroweak potential of finite range. To be precise, we have computed to one loop the exact vacuum energy for the case of a spherical square well potential of depth {alpha} and radius R. For small wells, the vacuum energy is reliably determined by a perturbative expansion in the external potential. For large wells, however, the perturbative expansion breaks down. A manifestation of this breakdown is that the vacuum carries a non-zero neutrino charge. The energy and neutrino charge of the ground state are, to a good approximation for large wells, those of a neutrino condensate with chemical potential {mu}={alpha}. Our results demonstrate explicitly that long-range forces due to the exchange of massless neutrinos do not threaten the stability of neutron stars. {copyright} {ital 1998} {ital The American Physical Society}

  18. The ground state of molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Jennings, D. E.; Brault, J. W.

    1983-12-01

    The v = 0-0 quadrupole spectrum of H2 has been recorded using a 0.005-cm-1 resolution Fourier transform spectrometer. The rotational lines S(1) through S(5) are observable in the spectra, in the region 587 to 1447 cm-1. The spectral position for S(0) was also obtained from its v = 1-0 ground-state combination difference. The high accuracy of the H2 measurements has permitted a determination of four rotational constants. These are (in cm-1) B0 = 59.33455(6); D0 = 0.045682(4); H0 = 4.854(12) × 10-5 L0 = -5.41(12) × 10-8. The hydrogen line positions will facilitate studies of structure and dynamics in astrophysical objects exhibiting infrared H2 spectra. The absolute accuracy of frequency calibration over wide spectral ranges was verified using 10-μm CO2 and 3.39-μm CH4 laser frequencies. Standard frequencies for 5-μm CO were found to be high by 12 MHz (3.9 × 10-4 cm-1).

  19. Ground-water activation from the upcoming operation of MI40 beam absorber

    SciTech Connect

    Bhat, C.M.; Read, A.L.

    1996-09-01

    During the course of normal operation, a particle accelerator can produce radionuclides in the adjacent soil and in the beam line elements through the interactions of accelerated particles and/or secondary particles produced in the beam absorbers, targets, and sometimes elsewhere through routine beam losses. The production and concentration of these radionuclides depends on the beam parameters such as energy, intensity, particle type, and target configuration. The radionuclides produced in the soil can potentially migrate to the ground water. Soil activation and migration to the ground water depends on the details of the local hydrogeology. Generally, very few places such as the beam stops, target stations, injection and extraction sectors can have high enough radiation fields to produce radionuclides in the soil outside the enclosures. During the design, construction, or an upgrade in the intensity of existing beams, measures are taken to minimize the production of activated soil. The only leachable radionuclides known to be produced in the Fermilab soil are {sup 3}H, {sup 7}Be , {sup 22}Na, {sup 45}Ca and {sup 54}Mn and it has been determined that only {sup 3}H, and {sup 22}Na, because of their longer half lives and greater leachabilities, may significantly impact ground water resources.In the past, Fermilab has developed and used the Single Resident Well Model (SRWM) to estimate the ground water activation. Recently, the Concentration Model (CM), a more realistic method which depends on the site hydrogeology has been developed to decide the shielding requirements of the high radiation sites, and to calculate the ground water activation and its subsequent migration to the aquifer. In this report, the concentration of radionuclide released to the surface waters and the aquifer around the MI40 beam absorber are calculated. Subsequently, the ultimate limit on the primary proton beam intensity to be aborted on the Main Injector beam absorber is determined.

  20. On the ground state of Yang-Mills theory

    SciTech Connect

    Bakry, Ahmed S.; Leinweber, Derek B.; Williams, Anthony G.

    2011-08-15

    Highlights: > The ground state overlap for sets of meson potential trial states is measured. > Non-uniform gluonic distributions are probed via Wilson loop operator. > The locally UV-regulated flux-tube operators can optimize the ground state overlap. - Abstract: We investigate the overlap of the ground state meson potential with sets of mesonic-trial wave functions corresponding to different gluonic distributions. We probe the transverse structure of the flux tube through the creation of non-uniform smearing profiles for the string of glue connecting two color sources in Wilson loop operator. The non-uniformly UV-regulated flux-tube operators are found to optimize the overlap with the ground state and display interesting features in the ground state overlap.

  1. Polarization properties of Gaussian-Schell model beams propagating in a space-to-ground optical communication downlink.

    PubMed

    Ma, Jing; Wu, Jiajie; Tan, Liying; Yu, Siyuan

    2017-02-20

    Based on the extended Huygens-Fresnel principle, the element expression of a cross-spectral matrix of Gaussian-Schell-model (GSM) laser beams propagating in a space-to-ground optical communication downlink is derived analytically. With full consideration of both the source parameters and the zenith angle, the changes in the degree of polarization (DOP) and the state of polarization (SOP) are investigated. The simulation results indicate that the source parameters play a crucial role in determining both DOP and SOP in space-to-ground optical communication downlinks. Compared to the source parameters, the zenith angle has no obvious influence on the polarization properties when it is smaller than 88°. The results of this work provide a design basis for a polarization shift keying optical communication system with a GSM laser beam.

  2. Dissociative recombination of the ground state of N2(+)

    NASA Technical Reports Server (NTRS)

    Guberman, Steven L.

    1991-01-01

    Large-scale calculations of the dissociative recombination cross sections and rates for the v = 0 level of the N2(+) ground state are reported, and the important role played by vibrationally excited Rydberg states lying both below and above the v = 0 level of the ion is demonstrated. The large-scale electronic wave function calculations were done using triple zeta plus polarization nuclear-centered-valence Gaussian basis sets. The electronic widths were obtained using smaller wave functions, and the cross sections were calculated on the basis of the multichannel quantum defect theory. The DR rate is calculated at 1.6 x 10 to the -7th x (Te/300) to the -0.37 cu cm/sec for Te in the range of 100 to 1000 K, and is found to be in excellent agreement with prior microwave afterglow experiments but in disagreement with recent merged beam results. It is inferred that the dominant mechanism for DR imparts sufficient energy to the product atoms to allow for escape from the Martian atmosphere.

  3. Triaxiality of the ground states in the 174W

    NASA Astrophysics Data System (ADS)

    Ya, Tu; Chen, Y. S.; Liu, L.; Gao, Z. C.

    2016-05-01

    We have performed calculations for the ground states in 174W by using the projected total energy surface (PTES) calculations. Both the ground state (g.s.) band and its γ band reproduce the experimental data. Further discussion about the triaxiality in 174W has been made by transition quardrupole moment (Qt) and comparing between the PTES and TRS methods.

  4. Partially-grounded depressed beam collector for the O-MBK and beyond

    NASA Astrophysics Data System (ADS)

    Jiang, Yong; Teryaev, Vladimir E.; Shchelkunov, Sergey V.; Hirshfield, Jay L.

    2017-03-01

    To address RF source inefficiency, we present a design of an L-band multi-beam klystron with a new type of depressed collector. It comprises a grounded element, a magnetic lens, and an electrode held at negative potential. This collector allows recovery of a larger portion of energy in the spent electron beams than could a conventional depressed collector, and will increase the tube efficiency towards 80 % in a single stage.

  5. Ground state configurations in two-mode quantum Rabi models

    NASA Astrophysics Data System (ADS)

    Chilingaryan, Suren; Rodríguez-Lara, B. M.

    We study two models describing a single two-level system coupled to two boson field modes in either a parallel or orthogonal configuration. Both models may be feasible for experimental realization through Raman adiabatic driving in cavity QED. We study their ground state configurations; that is, we find the quantum precursors of the corresponding semi-classical phase transitions. We found that the ground state configurations of both models present the same critical coupling as the quantum Rabi model. Around this critical coupling, the ground state goes from the so-called normal configuration with no excitation, the qubit in the ground state and the fields in the quantum vacuum state, to a ground state with excitations, the qubit in a superposition of ground and excited state, while the fields are not in the vacuum anymore, for the first model. The second model shows a more complex ground state configuration landscape where we find the normal configuration mentioned above, two single-mode configurations, where just one of the fields and the qubit are excited, and a dual-mode configuration, where both fields and the qubit are excited. S A Chilingaryan acknowledges financial support from CONACYT.

  6. Ground state energy fluctuations in the nuclear shell model

    NASA Astrophysics Data System (ADS)

    Velázquez, Víctor; Hirsch, Jorge G.; Frank, Alejandro; Barea, José; Zuker, Andrés P.

    2005-05-01

    Statistical fluctuations of the nuclear ground state energies are estimated using shell model calculations in which particles in the valence shells interact through well-defined forces, and are coupled to an upper shell governed by random 2-body interactions. Induced ground-state energy fluctuations are found to be one order of magnitude smaller than those previously associated with chaotic components, in close agreement with independent perturbative estimates based on the spreading widths of excited states.

  7. Antibonding ground state of adatom molecules in bulk Dirac semimetals

    NASA Astrophysics Data System (ADS)

    Marques, Y.; Obispo, A. E.; Ricco, L. S.; de Souza, M.; Shelykh, I. A.; Seridonio, A. C.

    2017-07-01

    The ground state of the diatomic molecules in nature is inevitably bonding, and its first excited state is antibonding. We demonstrate theoretically that, for a pair of distant adatoms placed buried in three-dimensional-Dirac semimetals, this natural order of the states can be reversed and an antibonding ground state occurs at the lowest energy of the so-called bound states in the continuum. We propose an experimental protocol with the use of a scanning tunneling microscope tip to visualize the topographic map of the local density of states on the surface of the system to reveal the emerging physics.

  8. Ensemble Theory for Stealthy Hyperuniform Disordered Ground States

    NASA Astrophysics Data System (ADS)

    Torquato, Salvatore

    Disordered hyperuniform many-particle systems have been receiving recent attention because they are distinguishable exotic states of matter poised between a crystal and liquid that are endowed with novel thermodynamic and physical properties. It has been shown numerically that systems of particles interacting with ``stealthy'' bounded, long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are, counterintuitively, disordered, hyperuniform and highly degenerate. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in d-dimensional Euclidean space is highly nontrivial because the dimensionality of the configuration space depends on the number density and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure for finding a particular ground-state configuration. A new type of statistical-mechanical theory had to be invented to characterize these exotic states of matter. I report on some initial progress that we have made in this direction. We show that stealthy disordered ground states behave like ''pseudo''-equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for the structure and thermodynamic properties of the stealthy disordered ground states and associated excited states are in excellent agreement with computer simulations across dimensions.

  9. Ground states of stealthy hyperuniform potentials: I. Entropically favored configurations.

    PubMed

    Zhang, G; Stillinger, F H; Torquato, S

    2015-08-01

    Systems of particles interacting with "stealthy" pair potentials have been shown to possess infinitely degenerate disordered hyperuniform classical ground states with novel physical properties. Previous attempts to sample the infinitely degenerate ground states used energy minimization techniques, introducing algorithmic dependence that is artificial in nature. Recently, an ensemble theory of stealthy hyperuniform ground states was formulated to predict the structure and thermodynamics that was shown to be in excellent agreement with corresponding computer simulation results in the canonical ensemble (in the zero-temperature limit). In this paper, we provide details and justifications of the simulation procedure, which involves performing molecular dynamics simulations at sufficiently low temperatures and minimizing the energy of the snapshots for both the high-density disordered regime, where the theory applies, as well as lower densities. We also use numerical simulations to extend our study to the lower-density regime. We report results for the pair correlation functions, structure factors, and Voronoi cell statistics. In the high-density regime, we verify the theoretical ansatz that stealthy disordered ground states behave like "pseudo" disordered equilibrium hard-sphere systems in Fourier space. The pair statistics obey certain exact integral conditions with very high accuracy. These results show that as the density decreases from the high-density limit, the disordered ground states in the canonical ensemble are characterized by an increasing degree of short-range order and eventually the system undergoes a phase transition to crystalline ground states. In the crystalline regime (low densities), there exist aperiodic structures that are part of the ground-state manifold but yet are not entropically favored. We also provide numerical evidence suggesting that different forms of stealthy pair potentials produce the same ground-state ensemble in the zero

  10. State-selective electron capture in collisions of ground and metastable O2+ ions with H(1s)

    NASA Astrophysics Data System (ADS)

    Cabello, C. N.; Errea, L. F.; Fernández, L.; Méndez, L.; Macías, A.; Rabadán, I.; Riera, A.

    2003-01-01

    An ab initio calculation of the electron capture cross sections for collisions of ground and metastable states of O2+ with H(1s) is presented. For impact energies between 0.125 and 3.4 keV amu-1, we find good agreement between the cross sections from the ground state ion with the mixed beam experimental data of Phaneuf et al (Phaneuf A, Alvarez I, Meyer F W and Crandall D H 1982 Phys. Rev. A 26 1892).

  11. Handbook for state ground water managers

    SciTech Connect

    Not Available

    1992-05-01

    ;Table of Contents: Nonpoint Source Implementation; State Public Water System Supervision; State Underground Water Source Protection (Underground Injection Control); Water Pollution Control -- State and Interstate Program Support (106 Grants); Water Quality Management Planning; Agriculture in Concert with the Environment; Consolidated Pesticide Compliance Monitoring and Program Cooperative Agreements; Pollution Prevention Incentives for States; Hazardous Substance Response Trust Fund; Hazardous Waste Financial Assistance; Underground Storage Tank Program; Leaking Underground Storage Tank Trust Fund; State/EPA Data Management Financial Assistance Program; Environmental Education; and Multi-Media Assistance Agreements for Indian Tribes.

  12. Analysis of ground state in random bipartite matching

    NASA Astrophysics Data System (ADS)

    Shi, Gui-Yuan; Kong, Yi-Xiu; Liao, Hao; Zhang, Yi-Cheng

    2016-02-01

    Bipartite matching problems emerge in many human social phenomena. In this paper, we study the ground state of the Gale-Shapley model, which is the most popular bipartite matching model. We apply the Kuhn-Munkres algorithm to compute the numerical ground state of the model. For the first time, we obtain the number of blocking pairs which is a measure of the system instability. We also show that the number of blocking pairs formed by each person follows a geometric distribution. Furthermore, we study how the connectivity in the bipartite matching problems influences the instability of the ground state.

  13. Antifreeze acceptability for ground-coupled heat pump ground loops in the United States

    SciTech Connect

    Den Braven, K.R.

    1998-10-01

    When designing and installing closed-loop ground-coupled heat pumps systems, it is necessary to be aware of applicable environmental regulations. Within the United States, nearly half of the states have regulations specifying or restricting the use of particular antifreezes or other fluids within the ground loop of a ground-coupled heat pump system. A number of other states have regulations pending. While all of these regulations are based on the need to preserve groundwater and/or aquifer quality, the list of acceptable antifreezes varies among those states with specified fluids. Typical antifreezes in use include ethylene glycol, propylene glycol, brines, alcohols, and potassium acetate. Each of these has its benefits and drawbacks. The status of the regulations has been determined for all of the states. An overview of the regulations is presented in this paper, along with a summary of the states` concerns.

  14. VizieR Online Data Catalog: ATCA obs. of ground-state OH masers (Qiao+, 2016)

    NASA Astrophysics Data System (ADS)

    Qiao, H.-H.; Walsh, A. J.; Green, J. A.; Breen, S. L.; Dawson, J. R.; Ellingsen, S. P.; Gomez, J. F.; Jordan, C. H.; Shen, Z.-Q.; Lowe, V.; Jones, P. A.

    2017-01-01

    Observations were conducted with the ATCA from 2013 October 24 to 29, and 2015 January 27. At the frequency of the ground-state OH masers, the 6A array results in a synthesized beam between 4.07"x7.41" and 5.50"x12.53". Observational pointing centers were determined based on the Parkes OH maser detections introduced in Dawson+ (2014MNRAS.439.1596D). (1 data file).

  15. Hybrid onboard and ground based digital channelizer beam-forming for SATCOM interference mitigation and protection

    NASA Astrophysics Data System (ADS)

    Xiong, Wenhao; Wang, Gang; Tian, Xin; Pham, Khanh; Blasch, Erik; Chen, Genshe

    2016-05-01

    In this work, we propose a novel beam-forming power allocation method for a satellite communication (SATCOM) multiple-input multiple-output (MIMO) system to mitigate the co-channel interference (CCI) as well as limiting the signal leakage to the adversary users. In SATCOM systems, the beam-forming technique is a conventional way of avoiding interference, controlling the antenna beams, and mitigating undesired signals. We propose to use an advanced beam-forming technique which considers the number of independent channels used and transmitting power deployed to reduce and mitigate the unintentional interference effect. With certain quality of service (QoS) for the SATCOM system, independent channels components will be selected. It is desired to use less and stronger channel components when possible. On the other hand, considering that SATCOM systems often face the problem that adversary receiver detects the signal, a proposed power allocation method can efficiently reduce the received power at the adversary receiver. To reduce the computational burden on the transponder in order to minimize the size, mass, power consumption and delay for the satellite, we apply a hybrid onboard and ground based beam-forming design to distribute the calculation between the transponder and ground terminals. Also the digital channelizer beam-forming (DCB) technique is employed to achieve dynamic spatial control.

  16. Approximating the ground state of gapped quantum spin systems

    SciTech Connect

    Michalakis, Spyridon; Hamza, Eman; Nachtergaele, Bruno; Sims, Robert

    2009-01-01

    We consider quantum spin systems defined on finite sets V equipped with a metric. In typical examples, V is a large, but finite subset of Z{sup d}. For finite range Hamiltonians with uniformly bounded interaction terms and a unique, gapped ground state, we demonstrate a locality property of the corresponding ground state projector. In such systems, this ground state projector can be approximated by the product of observables with quantifiable supports. In fact, given any subset {chi} {contained_in} V the ground state projector can be approximated by the product of two projections, one supported on {chi} and one supported on {chi}{sup c}, and a bounded observable supported on a boundary region in such a way that as the boundary region increases, the approximation becomes better. Such an approximation was useful in proving an area law in one dimension, and this result corresponds to a multi-dimensional analogue.

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

    PubMed

    Katsura, Hosho; Tasaki, Hal

    2013-03-29

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

  18. Theory of ground state factorization in quantum cooperative systems.

    PubMed

    Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio

    2008-05-16

    We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows us to determine rigorously the existence, location, and exact form of separable ground states in a large variety of, generally nonexactly solvable, spin models belonging to different universality classes. The theory applies to translationally invariant systems, irrespective of spatial dimensionality, and for spin-spin interactions of arbitrary range.

  19. Ground-state properties of the periodic Anderson model

    NASA Technical Reports Server (NTRS)

    Blankenbecler, R.; Fulco, J. R.; Gill, W.; Scalapino, D. J.

    1987-01-01

    The ground-state energy, hybridization matrix element, local moment, and spin-density correlations of a one-dimensional, finite-chain, periodic, symmetric Anderson model are obtained by numerical simulations and compared with perturbation theory and strong-coupling results. It is found that the local f-electron spins are compensated by correlation with other f-electrons as well as band electrons leading to a nonmagnetic ground state.

  20. STATE WATER RESOURCES RESEARCH INSTITUTE PROGRAM: GROUND WATER RESEARCH.

    USGS Publications Warehouse

    Burton, James S.; ,

    1985-01-01

    This paper updates a review of the accomplishments of the State Water Resources Research Program in ground water contamination research. The aim is to assess the progress made towards understanding the mechanisms of ground water contamination and based on this understanding, to suggest procedures for the prevention and control of ground water contamination. The following research areas are covered: (1) mechanisms of organic contaminant transport in the subsurface environment; (2) bacterial and viral contamination of ground water from landfills and septic tank systems; (3) fate and persistence of pesticides in the subsurface; (4) leachability and transport of ground water pollutants from coal production and utilization; and (5) pollution of ground water from mineral mining activities.

  1. Model of a SNS Electrostatic LEBT with a Near-Ground Beam Chopper

    NASA Astrophysics Data System (ADS)

    Han, B. X.; Stockli, M. P.

    2009-03-01

    The low energy beam transport (LEBT) of the Spallation Neutron Source (SNS) accelerator consists of two electrostatic lenses, of which the second is split into four electrically-isolated segments. Adding fast pulsed voltages to the lens high voltage creates the transverse fields required for beam chopping. Electric sparks, however, create transients that enter the fast high-voltage switches, which are occasionally damaged and cause machine downtime. This work models a new configuration of the electrostatic LEBT, which chops the beam with four shielded, near-ground electrodes between the two lenses. The model shows that the new configuration can match the RFQ injection requirements and sufficiently deflect the beam in the phase-space using the same chopping voltages as in the baseline LEBT.

  2. Toward Space-like Photometric Precision from the Ground with Beam-shaping Diffusers

    NASA Astrophysics Data System (ADS)

    Stefansson, Gudmundur; Mahadevan, Suvrath; Hebb, Leslie; Wisniewski, John; Huehnerhoff, Joseph; Morris, Brett; Halverson, Sam; Zhao, Ming; Wright, Jason; O’rourke, Joseph; Knutson, Heather; Hawley, Suzanne; Kanodia, Shubham; Li, Yiting; Hagen, Lea M. Z.; Liu, Leo J.; Beatty, Thomas; Bender, Chad; Robertson, Paul; Dembicky, Jack; Gray, Candace; Ketzeback, William; McMillan, Russet; Rudyk, Theodore

    2017-10-01

    We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating {62}-16+26 ppm precision in 30 minute bins on a nearby bright star 16 Cygni A (V = 5.95) using the ARC 3.5 m telescope—within a factor of ∼2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V = 11.2) and TRES-3b (V = 12.4), where the residuals bin down to {180}-41+66 ppm in 30 minute bins for WASP-85-Ab—a factor of ∼4 of the precision achieved by the K2 mission on this target—and to 101 ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests demonstrated {137}-36+64 ppm precision for a K S = 10.8 star on the 200 inch Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets.

  3. Homogeneous binary trees as ground states of quantum critical Hamiltonians

    NASA Astrophysics Data System (ADS)

    Silvi, P.; Giovannetti, V.; Montangero, S.; Rizzi, M.; Cirac, J. I.; Fazio, R.

    2010-06-01

    Many-body states whose wave functions admit a representation in terms of a uniform binary-tree tensor decomposition are shown to obey power-law two-body correlation functions. Any such state can be associated with the ground state of a translationally invariant Hamiltonian which, depending on the dimension of the systems sites, involves at most couplings between third-neighboring sites. Under general conditions it is shown that they describe unfrustrated systems which admit an exponentially large degeneracy of the ground state.

  4. Toward Triplet Ground State NaLi Molecules

    NASA Astrophysics Data System (ADS)

    Ebadi, Sepehr; Jamison, Alan; Rvachov, Timur; Jing, Li; Son, Hyungmok; Jiang, Yijun; Zwierlein, Martin; Ketterle, Wolfgang

    2016-05-01

    The NaLi molecule is expected to have a long lifetime in the triplet ground-state due to its fermionic nature, large rotational constant, and weak spin-orbit coupling. The triplet state has both electric and magnetic dipole moments, affording unique opportunities in quantum simulation and ultracold chemistry. We have mapped the excited state NaLi triplet potential by means of photoassociation spectroscopy. We report on this and our further progress toward the creation of the triplet ground-state molecules using STIRAP. NSF, ARO-MURI, Samsung, NSERC.

  5. Estimation of ground state pentaquark masses

    NASA Astrophysics Data System (ADS)

    Xu, K.; Ritjoho, N.; Srisuphaphon, S.; Yan, Y.

    2014-04-01

    Permutation groups are applied to analyze the symmetries of multiquark systems and wave functions of pentaquark states are constructed systematically in the language of Yamanouchi basis. We estimate the mass of baryons in the constituent quark model with one-gluon-exchange interaction, assuming that baryons consist of the q3 component as well as the q4/line q pentaquark component.

  6. Ground-state geometric quantum computing in superconducting systems

    SciTech Connect

    Solinas, P.; Moettoenen, M.

    2010-11-15

    We present a theoretical proposal for the implementation of geometric quantum computing based on a Hamiltonian which has a doubly degenerate ground state. Thus the system which is steered adiabatically, remains in the ground-state. The proposed physical implementation relies on a superconducting circuit composed of three SQUIDs and two superconducting islands with the charge states encoding the logical states. We obtain a universal set of single-qubit gates and implement a nontrivial two-qubit gate exploiting the mutual inductance between two neighboring circuits, allowing us to realize a fully geometric ground-state quantum computing. The introduced paradigm for the implementation of geometric quantum computing is expected to be robust against environmental effects.

  7. Nature of ground and electronic excited states of higher acenes

    PubMed Central

    Yang, Yang; Yang, Weitao

    2016-01-01

    Higher acenes have drawn much attention as promising organic semiconductors with versatile electronic properties. However, the nature of their ground state and electronic excited states is still not fully clear. Their unusual chemical reactivity and instability are the main obstacles for experimental studies, and the potentially prominent diradical character, which might require a multireference description in such large systems, hinders theoretical investigations. Here, we provide a detailed answer with the particle–particle random-phase approximation calculation. The 1Ag ground states of acenes up to decacene are on the closed-shell side of the diradical continuum, whereas the ground state of undecacene and dodecacene tilts more to the open-shell side with a growing polyradical character. The ground state of all acenes has covalent nature with respect to both short and long axes. The lowest triplet state 3B2u is always above the singlet ground state even though the energy gap could be vanishingly small in the polyacene limit. The bright singlet excited state 1B2u is a zwitterionic state to the short axis. The excited 1Ag state gradually switches from a double-excitation state to another zwitterionic state to the short axis, but always keeps its covalent nature to the long axis. An energy crossing between the 1B2u and excited 1Ag states happens between hexacene and heptacene. Further energetic consideration suggests that higher acenes are likely to undergo singlet fission with a low photovoltaic efficiency; however, the efficiency might be improved if a singlet fission into multiple triplets could be achieved. PMID:27528690

  8. Nature of ground and electronic excited states of higher acenes.

    PubMed

    Yang, Yang; Davidson, Ernest R; Yang, Weitao

    2016-08-30

    Higher acenes have drawn much attention as promising organic semiconductors with versatile electronic properties. However, the nature of their ground state and electronic excited states is still not fully clear. Their unusual chemical reactivity and instability are the main obstacles for experimental studies, and the potentially prominent diradical character, which might require a multireference description in such large systems, hinders theoretical investigations. Here, we provide a detailed answer with the particle-particle random-phase approximation calculation. The (1)Ag ground states of acenes up to decacene are on the closed-shell side of the diradical continuum, whereas the ground state of undecacene and dodecacene tilts more to the open-shell side with a growing polyradical character. The ground state of all acenes has covalent nature with respect to both short and long axes. The lowest triplet state (3)B2u is always above the singlet ground state even though the energy gap could be vanishingly small in the polyacene limit. The bright singlet excited state (1)B2u is a zwitterionic state to the short axis. The excited (1)Ag state gradually switches from a double-excitation state to another zwitterionic state to the short axis, but always keeps its covalent nature to the long axis. An energy crossing between the (1)B2u and excited (1)Ag states happens between hexacene and heptacene. Further energetic consideration suggests that higher acenes are likely to undergo singlet fission with a low photovoltaic efficiency; however, the efficiency might be improved if a singlet fission into multiple triplets could be achieved.

  9. Ground-Water Availability in the United States

    USGS Publications Warehouse

    Reilly, Thomas E.; Dennehy, Kevin F.; Alley, William M.; Cunningham, William L.

    2008-01-01

    Ground water is among the Nation's most important natural resources. It provides half our drinking water and is essential to the vitality of agriculture and industry, as well as to the health of rivers, wetlands, and estuaries throughout the country. Large-scale development of ground-water resources with accompanying declines in ground-water levels and other effects of pumping has led to concerns about the future availability of ground water to meet domestic, agricultural, industrial, and environmental needs. The challenges in determining ground-water availability are many. This report examines what is known about the Nation's ground-water availability and outlines a program of study by the U.S. Geological Survey Ground-Water Resources Program to improve our understanding of ground-water availability in major aquifers across the Nation. The approach is designed to provide useful regional information for State and local agencies who manage ground-water resources, while providing the building blocks for a national assessment. The report is written for a wide audience interested or involved in the management, protection, and sustainable use of the Nation's water resources.

  10. Shear design of wood beams : state of the art

    Treesearch

    Lawrence A. Soltis; Terry D. Gerhardt

    1988-01-01

    Current shear design technology in the United States for lumber or glued- laminated beams is confusing. This report summarizes shear stress and strength research including both analytical and experimental approaches. Both checked and unchecked beams are included. The analytical work has been experimentally verified for only limited load conditions and span-to- depth...

  11. Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

    NASA Astrophysics Data System (ADS)

    Man, Zhongsheng; Du, Luping; Min, Changjun; Zhang, Yuquan; Zhang, Chonglei; Zhu, Siwei; Paul Urbach, H.; Yuan, X.-C.

    2014-07-01

    Vector beams, which have space-variant state of polarization (SOP) comparing with scalar beams with spatially homogeneous SOP, are used to manipulate surface plasmon polarizations (SPPs). We find that the excitation, orientation, and distribution of the focused SPPs excited in a high numerical aperture microscopic configuration highly depend on the space-variant polarization of the incident vector beam. When it comes to vector beam with axial symmetry, multi-foci of SPPs with the same size and uniform intensity can be obtained, and the number of foci is depending on the polarization order n. Those properties can be of great value in biological sensor and plasmonic tweezers applications.

  12. Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

    SciTech Connect

    Man, Zhongsheng; Zhang, Yuquan; Zhang, Chonglei; Du, Luping; Min, Changjun E-mail: xcyuan@szu.edu.cn; Yuan, X.-C. E-mail: xcyuan@szu.edu.cn; Zhu, Siwei; Paul Urbach, H.

    2014-07-07

    Vector beams, which have space-variant state of polarization (SOP) comparing with scalar beams with spatially homogeneous SOP, are used to manipulate surface plasmon polarizations (SPPs). We find that the excitation, orientation, and distribution of the focused SPPs excited in a high numerical aperture microscopic configuration highly depend on the space-variant polarization of the incident vector beam. When it comes to vector beam with axial symmetry, multi-foci of SPPs with the same size and uniform intensity can be obtained, and the number of foci is depending on the polarization order n. Those properties can be of great value in biological sensor and plasmonic tweezers applications.

  13. Ensemble Theory for Stealthy Hyperuniform Disordered Ground States

    NASA Astrophysics Data System (ADS)

    Torquato, S.; Zhang, G.; Stillinger, F. H.

    2015-04-01

    It has been shown numerically that systems of particles interacting with isotropic "stealthy" bounded long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are (counterintuitively) disordered, hyperuniform, and highly degenerate. Disordered hyperuniform systems have received attention recently because they are distinguishable exotic states of matter poised between a crystal and liquid that are endowed with novel thermodynamic and physical properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in d -dimensional Euclidean space Rd is highly nontrivial because the dimensionality of the configuration space depends on the number density ρ and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure for finding a particular ground-state configuration. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties (energy, pressure, and isothermal compressibility) that apply to any ground-state ensemble as a function of ρ in any d , and we show how disordered degenerate ground states arise as part of the ground-state manifold. We also derive exact integral conditions that both the pair correlation function g2(r ) and structure factor S (k ) must obey for any d . We then specialize our results to the canonical ensemble (in the zero-temperature limit) by exploiting an ansatz that stealthy states behave remarkably like "pseudo"-equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for g2(r ) and S (k ) are in excellent agreement with computer simulations across the first three space dimensions. These results are used to obtain order metrics, local number variance, and nearest-neighbor functions across dimensions. We also derive accurate analytical

  14. Highly Entangled Ground States in Tripartite Qubit Systems

    NASA Astrophysics Data System (ADS)

    Röthlisberger, Beat; Lehmann, Jörg; Saraga, D. S.; Traber, Philipp; Loss, Daniel

    2008-03-01

    We investigate the creation of highly entangled ground states in a system of three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic field configurations yielding approximate Greenberger-Horne-Zeilinger and exact W ground states are identified. The entanglement in the system is studied at finite temperature in terms of the mixed-state tangle τ. By generalizing a conjugate gradient optimization algorithm originally developed to evaluate the entanglement of formation, we demonstrate that τ can be calculated efficiently and with high precision. We identify the parameter regime for which the equilibrium entanglement of the tripartite system reaches its maximum.

  15. Magnetic field induced lattice ground states from holography

    NASA Astrophysics Data System (ADS)

    Bu, Yan-Yan; Erdmenger, Johanna; Shock, Jonathan P.; Strydom, Migael

    2013-03-01

    We study the holographic field theory dual of a probe SU(2) Yang-Mills field in a background (4 + 1)-dimensional asymptotically Anti-de Sitter space. We find a new ground state when a magnetic component of the gauge field is larger than a critical value. The ground state forms a triangular Abrikosov lattice in the spatial directions perpendicular to the magnetic field. The lattice is composed of superconducting vortices induced by the condensation of a charged vector operator. We perform this calculation both at finite temperature and at zero temperature with a hard wall cutoff dual to a confining gauge theory. The study of this state may be of relevance to both holographic condensed matter models as well as to heavy ion physics. The results shown here provide support for the proposal that such a ground state may be found in the QCD vacuum when a large magnetic field is present.

  16. Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance

    PubMed Central

    Li, Zhaokai; Yung, Man-Hong; Chen, Hongwei; Lu, Dawei; Whitfield, James D.; Peng, Xinhua; Aspuru-Guzik, Alán; Du, Jiangfeng

    2011-01-01

    Quantum ground-state problems are computationally hard problems for general many-body Hamiltonians; there is no classical or quantum algorithm known to be able to solve them efficiently. Nevertheless, if a trial wavefunction approximating the ground state is available, as often happens for many problems in physics and chemistry, a quantum computer could employ this trial wavefunction to project the ground state by means of the phase estimation algorithm (PEA). We performed an experimental realization of this idea by implementing a variational-wavefunction approach to solve the ground-state problem of the Heisenberg spin model with an NMR quantum simulator. Our iterative phase estimation procedure yields a high accuracy for the eigenenergies (to the 10−5 decimal digit). The ground-state fidelity was distilled to be more than 80%, and the singlet-to-triplet switching near the critical field is reliably captured. This result shows that quantum simulators can better leverage classical trial wave functions than classical computers PMID:22355607

  17. Quench of a symmetry-broken ground state

    NASA Astrophysics Data System (ADS)

    Giampaolo, S. M.; Zonzo, G.

    2017-01-01

    We analyze the problem of how different ground states associated with the same set of Hamiltonian parameters evolve after a sudden quench. To realize our analysis we define a quantitative approach to the local distinguishability between different ground states of a magnetically ordered phase in terms of the trace distance between the reduced density matrices obtained by projecting two ground states in the same subset. Before the quench, regardless of the particular choice of subset, any system in a magnetically ordered phase is characterized by ground states that are locally distinguishable. On the other hand, after the quench, the maximum distinguishability shows an exponential decay in time. Hence, in the limit of very long times, all the information about the particular initial ground state is lost even if the systems are integrable. We prove our claims in the framework of the magnetically ordered phases that characterize both the X Y and the N -cluster Ising models. The fact that we find similar behavior in models within different classes of symmetry makes us confident about the generality of our results.

  18. Beam and shell modes of buckling of buried pipes induced by compressive ground failure

    SciTech Connect

    Chiou, Y.J.; Chi, S.Y.

    1995-12-31

    The buckling of buried pipeline induced by compressive ground failure was investigated. Both the beam mode of buckling and local shell mode of buckling, and their interactions were studied. The pipeline response was analyzed numerically. The results agree qualitatively with past researches and possess satisfactory comparisons with actual case histories. The relations of critical buried depth versus ratio of pipe diameter to thickness for buried pipe with different imperfections and various soil foundations were established.

  19. Centrifugal stretching from lifetime measurements in the 170Hf ground state band

    NASA Astrophysics Data System (ADS)

    Smith, M. K.; Werner, V.; Terry, J. R.; Pietralla, N.; Petkov, P.; Berant, Z.; Casperson, R. J.; Heinz, A.; Henning, G.; Lüttke, R.; Qian, J.; Shoraka, B.; Rainovski, G.; Williams, E.; Winkler, R.

    2013-04-01

    Centrifugal stretching in the deformed rare-earth nucleus 170Hf is investigated using high-precision lifetime measurements, performed with the New Yale Plunger Device at Wright Nuclear Structure Laboratory, Yale University. Excited states were populated in the fusion-evaporation reaction 124Sn(50Ti,4n)170Hf at a beam energy of 195 MeV. Recoil distance doppler shift data were recorded for the ground state band through the J=16+ level. The measured B(E2) values and transition quadrupole moments improve on existing data and show increasing β deformation in the ground state band of 170Hf. The results are compared to descriptions by a rigid rotor and by the confined β-soft rotor model.

  20. Ground-Based Tests of Spacecraft Polymeric Materials under OXY-GEN Plasma-Beam

    NASA Astrophysics Data System (ADS)

    Chernik, Vladimir; Novikov, Lev; Gaidar, Anna

    2016-07-01

    Spacecraft LEO mission is accompanied by destruction of polymeric material surface under influence of atomic oxygen flow. Sources of molecular, plasma and ion beams are used for the accelerated ground-based tests of spacecraft materials. In the work application of oxygen plasma accelerator of a duoplasmatron type is described. Plasma particles have been accelerated up to average speed of 13-16 km/s. Influence of such beam on materials leads to more intensive destruction of polymers than in LEO. This fact allows to execute tests in the accelerated time scale by a method of an effective fluence. Special measures were given to decrease a concentration of both gaseous and electrode material impurities in the oxygen beam. In the work the results of simulative tests of spacecraft materials and experiments on LEO are considered. Comparison of plasma beam simulation with LEO data has shown conformity for structures of a number of polymeric materials. The relative erosion yields (normalized with respect to polyimide) of the tested materials are shown practically equal to those in LEO. The obtained results give grounds for using the plasma-generation mode with ion energies of 20-30 eV to accelerated testing of spacecraft materials for long -term LEO missions.

  1. Estimation of beryllium ground state energy by Monte Carlo simulation

    SciTech Connect

    Kabir, K. M. Ariful; Halder, Amal

    2015-05-15

    Quantum Monte Carlo method represent a powerful and broadly applicable computational tool for finding very accurate solution of the stationary Schrödinger equation for atoms, molecules, solids and a variety of model systems. Using variational Monte Carlo method we have calculated the ground state energy of the Beryllium atom. Our calculation are based on using a modified four parameters trial wave function which leads to good result comparing with the few parameters trial wave functions presented before. Based on random Numbers we can generate a large sample of electron locations to estimate the ground state energy of Beryllium. Our calculation gives good estimation for the ground state energy of the Beryllium atom comparing with the corresponding exact data.

  2. Variational Wave Functions and Their Overlap with the Ground State

    SciTech Connect

    Mora, Christophe; Waintal, Xavier

    2007-07-20

    An intrinsic measure of the quality of a variational wave function is given by its overlap with the ground state of the system. We derive a general formula to compute this overlap when quantum dynamics in imaginary time is accessible. The overlap is simply related to the area under the E({tau}) curve, i.e., the energy as a function of imaginary time. This has important applications to, for example, quantum Monte Carlo simulations where the overlap becomes as a simple by-product of routine simulations. As a result, we find that the practical definition of a good variational wave function for quantum Monte Carlo simulations, i.e., fast convergence to the ground state, is equivalent to a good overlap with the actual ground state of the system.

  3. The Yukawa potential: ground state energy and critical screening

    NASA Astrophysics Data System (ADS)

    Edwards, James P.; Gerber, Urs; Schubert, Christian; Trejo, Maria A.; Weber, Axel

    2017-08-01

    We study the ground state energy and the critical screening parameter of the Yukawa potential in nonrelativistic quantum mechanics. After a short review of the existing literature on these quantities, we apply fifth-order perturbation theory to the calculation of the ground state energy, using the exact solutions of the Coulomb potential together with a cutoff on the principal number summations. We also perform a variational calculation of the ground state energy using a Coulomb-like radial wave function and the exact solution of the corresponding minimization condition. For not too large values of the screening parameter, close agreement is found between the perturbative and variational results. For the critical screening parameter, we devise a novel method that permits us to determine it to 10 digits. This is the most precise calculation of this quantity to date, and allows us to resolve some discrepancies between previous results.

  4. Probing quantum frustrated systems via factorization of the ground state.

    PubMed

    Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio

    2010-05-21

    The existence of definite orders in frustrated quantum systems is related rigorously to the occurrence of fully factorized ground states below a threshold value of the frustration. Ground-state separability thus provides a natural measure of frustration: strongly frustrated systems are those that cannot accommodate for classical-like solutions. The exact form of the factorized ground states and the critical frustration are determined for various classes of nonexactly solvable spin models with different spatial ranges of the interactions. For weak frustration, the existence of disentangling transitions determines the range of applicability of mean-field descriptions in biological and physical problems such as stochastic gene expression and the stability of long-period modulated structures.

  5. Improved fair sampling of ground states in Ising spin glasses

    NASA Astrophysics Data System (ADS)

    Katzgraber, Helmut G.; Zhu, Zheng; Ochoa, Andrew J.

    2015-03-01

    Verifying that an optimization approach can sample all solutions that minimize a Hamiltonian is a stringent test for any newly-developed algorithm. While most solvers easily compute the minimum of a cost function for small to moderate input sizes, equiprobable sampling of all ground-state configurations (within Poissonian fluctuations) is much harder to obtain. Most notably, methods such as transverse-field quantum annealing fail in passing this test for certain highly-degenerate problems. Here we present an attempt to sample ground states for Ising spin glasses based on a combination of low-temperature parallel tempering Monte Carlo combined with the cluster algorithm by Houdayer. Because the latter is rejection free and obeys details balance, the ground-state manifold is efficiently sampled. We illustrate the approach for Ising spin glasses on the D-Wave Two quantum annealer topology, known as the Chimera graph, as well as two-dimensional Ising spin glasses.

  6. Ferromagnetic Ground States in Face-Centered Cubic Hubbard Clusters

    PubMed Central

    Souza, T. X. R.; Macedo, C. A.

    2016-01-01

    In this study, the ground state energies of face-centered cubic Hubbard clusters are analyzed using the Lanczos method. Examination of the ground state energy as a function of the number of particle per site n showed an energy minimum for face-centered cubic structures. This energy minimum decreased in n with increasing coulombic interaction parameter U. We found that the ground state energy had a minimum at n = 0.6, when U = 3W, where W denotes the non-interacting energy bandwidth and the face-centered cubic structure was ferromagnetic. These results, when compared with the properties of nickel, shows strong similarity with other finite temperature analyses in the literature and supports the Hirsh’s conjecture that the interatomic direct exchange interaction dominates in driving the system into a ferromagnetic phase. PMID:27583653

  7. Influence of beam wander on bit-error rate in a ground-to-satellite laser uplink communication system.

    PubMed

    Ma, Jing; Jiang, Yijun; Tan, Liying; Yu, Siyuan; Du, Wenhe

    2008-11-15

    Based on weak fluctuation theory and the beam-wander model, the bit-error rate of a ground-to-satellite laser uplink communication system is analyzed, in comparison with the condition in which beam wander is not taken into account. Considering the combined effect of scintillation and beam wander, optimum divergence angle and transmitter beam radius for a communication system are researched. Numerical results show that both of them increase with the increment of total link margin and transmitted wavelength. This work can benefit the ground-to-satellite laser uplink communication system design.

  8. Ground and Excited State Spectra of a Quantum Dot

    NASA Astrophysics Data System (ADS)

    Stewart, D. R.; Sprinzak, D.; Patel, S. R.; Marcus, C. M.; Duruoz, C. I.; Harris, J. S.

    1998-03-01

    We present linear and nonlinear magnetoconductance measurements of the ground and excited state spectra for successive electron occupancy in a gate defined lateral quantum dot. Previous measurementsfootnote D.R. Stewart, D. Sprinzak, C.M. Marcus, C.I. Duruoz and J.S. Harris Jr., Science 278, (1997). showed a direct correlation between the mth excited state of the N-electron system and the ground state of the (N+m)-electron system for m up to 4, consistent to a large degree with a single-particle picture. Here we report quantitative deviations of the excited state spectra from the spectrum of ground state magnetoconductances, attributed to many-body interactions in the finite system of N ~200 electrons. We also describe the behaviour of anticrossings in the ground state magnetoconductances. We acknowledge the support of JSEP (DAAH04-94-G-0058), ARO (DAAH04-95-1-0331), ONR-YIP (N00014-94-1-0622) and the NSF-PECASE program. D.S. acknowledges the support of MINERVA grant.

  9. Two-electron photoionization of ground-state lithium

    SciTech Connect

    Kheifets, A. S.; Fursa, D. V.; Bray, I.

    2009-12-15

    We apply the convergent close-coupling (CCC) formalism to single-photon two-electron ionization of the lithium atom in its ground state. We treat this reaction as single-electron photon absorption followed by inelastic scattering of the photoelectron on a heliumlike Li{sup +} ion. The latter scattering process can be described accurately within the CCC formalism. We obtain integrated cross sections of single photoionization leading to the ground and various excited states of the Li{sup +} ion as well as double photoionization extending continuously from the threshold to the asymptotic limit of infinite photon energy. Comparison with available experimental and theoretical data validates the CCC model.

  10. From local to global ground states in Ising spin glasses

    NASA Astrophysics Data System (ADS)

    Zintchenko, Ilia; Hastings, Matthew B.; Troyer, Matthias

    2015-01-01

    We consider whether it is possible to find ground states of frustrated spin systems by solving them locally. Using spin glass physics and Imry-Ma arguments in addition to numerical benchmarks we quantify the power of such local solution methods and show that for the average low-dimensional spin glass problem outside the spin glass phase the exact ground state can be found in polynomial time. In the second part we present a heuristic, general-purpose hierarchical approach which for spin glasses on chimera graphs and lattices in two and three dimensions outperforms, to our knowledge, any other solver currently around, with significantly better scaling performance than simulated annealing.

  11. A Remark on the Ground State Energy of Bosonic Atoms

    NASA Astrophysics Data System (ADS)

    Hogreve, H.

    2011-08-01

    Monotonicity properties of the ground state energy of bosonic atoms as established in a recent paper by M.K.H. Kiessling [J. Stat. Phys. 139:1063 (2009)] are studied. Symmetry and scaling arguments lead to a more direct proof of a slightly stronger result of this monotonicity and the behavior of the ground state energy as a function of the number of bosonic electrons. Furthermore, invoking appropriate lower and upper bounds on two-electron systems, the stability of the bosonics He- ion is rigorously demonstrated.

  12. Ground state microstructure of a ferrofluid thin layer

    SciTech Connect

    Prokopieva, T. A.; Danilov, V. A.; Kantorovich, S. S.

    2011-09-15

    Using a fine weave of theoretical analysis and computer simulations, we found various aggregates of magnetic single-domain nanoparticles, which can form in a quasi-two-dimensional (q2D) ferrofluid layer at low temperatures. Our theoretical investigation allowed us to obtain exact expressions and their asymptotes for the energies of each configuration. Thus, for ferrofluid q2D layers it proved possible to identify the ground states as a function of the particle number, size, and other system parameters. Our suggested approach can be used for the investigation of ground state structures in systems with more complex interparticle interactions.

  13. Ground states of the SU(N) Heisenberg model.

    PubMed

    Kawashima, Naoki; Tanabe, Yuta

    2007-02-02

    The SU(N) Heisenberg model with various single-row representations is investigated by quantum Monte Carlo simulations. While the zero-temperature phase boundary agrees qualitatively with the theoretical predictions based on the 1/N expansion, some unexpected features are also observed. For N> or =5 with the fundamental representation, for example, it is suggested that the ground states possess exact or approximate U(1) degeneracy. In addition, for the representation of Young tableau with more than one column, the ground state shows no valence-bond-solid order even at N greater than the threshold value.

  14. Characterizing Ground and Thermal States of Few-Body Hamiltonians

    NASA Astrophysics Data System (ADS)

    Huber, Felix; Gühne, Otfried

    2016-07-01

    The question whether a given quantum state is a ground or thermal state of a few-body Hamiltonian can be used to characterize the complexity of the state and is important for possible experimental implementations. We provide methods to characterize the states generated by two- and, more generally, k -body Hamiltonians as well as the convex hull of these sets. This leads to new insights into the question of which states are uniquely determined by their marginals and to a generalization of the concept of entanglement. Finally, certification methods for quantum simulation can be derived.

  15. Coherent Control of Ground State NaK Molecules

    NASA Astrophysics Data System (ADS)

    Yan, Zoe; Park, Jee Woo; Loh, Huanqian; Will, Sebastian; Zwierlein, Martin

    2016-05-01

    Ultracold dipolar molecules exhibit anisotropic, tunable, long-range interactions, making them attractive for the study of novel states of matter and quantum information processing. We demonstrate the creation and control of 23 Na40 K molecules in their rovibronic and hyperfine ground state. By applying microwaves, we drive coherent Rabi oscillations of spin-polarized molecules between the rotational ground state (J=0) and J=1. The control afforded by microwave manipulation allows us to pursue engineered dipolar interactions via microwave dressing. By driving a two-photon transition, we are also able to observe Ramsey fringes between different J=0 hyperfine states, with coherence times as long as 0.5s. The realization of long coherence times between different molecular states is crucial for applications in quantum information processing. NSF, AFOSR- MURI, Alfred P. Sloan Foundation, DARPA-OLE

  16. Dissociation energy of the ground state of NaH

    NASA Astrophysics Data System (ADS)

    Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen; Chang, Yung-Yung; Tsai, Chin-Chun

    2010-07-01

    The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9≤v″≤21 and 1≤J″≤14 were assigned to the X Σ1+ state of NaH. The highest vibrational level observed was only about 40 cm-1 from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation vD from the highest four vibrational levels yielded the dissociation energy De=15 815±5 cm-1. Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.

  17. Single-configuration descriptions of atomic ground and excited states - Ground states of He, Li, and Be

    NASA Astrophysics Data System (ADS)

    Fletcher, Graham D.; Doggett, Graham; Howard, Alan S.

    1992-11-01

    A first-derivative variational principle is applied to the optimization of a single-configuration spin-coupled wave function to determine the ground states of some atoms. An orbital is chosen and optimized, and an expansion is taken for the orbital over a set of primitive atomic orbitals. Expected values of spin-free and -dependent operators are developed, and optimum wave-function parameters are determined for evaluating radial moments and radial density functions from spin or spinless one-electron density functions. The method is applied to the ground-state properties of He, Li, and Be by means of even-tempered and Clementi-Roetti basis sets. Energy profiles are determined for spin-coupled and full configuration-interaction computations. The ground states of He, Li, and Be are found to have energy profiles with a global minimum and at least on local minimum.

  18. Striped spin liquid crystal ground state instability of kagome antiferromagnets.

    PubMed

    Clark, Bryan K; Kinder, Jesse M; Neuscamman, Eric; Chan, Garnet Kin-Lic; Lawler, Michael J

    2013-11-01

    The Dirac spin liquid ground state of the spin 1/2 Heisenberg kagome antiferromagnet has potential instabilities. This has been suggested as the reason why it does not emerge as the ground state in large-scale numerical calculations. However, previous attempts to observe these instabilities have failed. We report on the discovery of a projected BCS state with lower energy than the projected Dirac spin liquid state which provides new insight into the stability of the ground state of the kagome antiferromagnet. The new state has three remarkable features. First, it breaks spatial symmetry in an unusual way that may leave spinons deconfined along one direction. Second, it breaks the U(1) gauge symmetry down to Z(2). Third, it has the spatial symmetry of a previously proposed "monopole" suggesting that it is an instability of the Dirac spin liquid. The state described herein also shares a remarkable similarity to the distortion of the kagome lattice observed at low Zn concentrations in Zn-paratacamite and in recently grown single crystals of volborthite suggesting it may already be realized in these materials.

  19. High-precision quadrupole moment reveals significant intruder component in 20 13 33Al ground state

    NASA Astrophysics Data System (ADS)

    Heylen, H.; De Rydt, M.; Neyens, G.; Bissell, M. L.; Caceres, L.; Chevrier, R.; Daugas, J. M.; Ichikawa, Y.; Ishibashi, Y.; Kamalou, O.; Mertzimekis, T. J.; Morel, P.; Papuga, J.; Poves, A.; Rajabali, M. M.; Stödel, C.; Thomas, J. C.; Ueno, H.; Utsuno, Y.; Yoshida, N.; Yoshimi, A.

    2016-09-01

    The electric quadrupole moment of the 20 13 33Al ground state, located at the border of the island of inversion, was obtained using continuous-beam β -detected nuclear quadrupole resonance (β -NQR). From the measured quadrupole coupling constant νQ=2.31 (4 ) MHz in an α -Al2O3 crystal, a precise value for the electric quadrupole moment is extracted: 33Al>Qs 141 (3 ) mb. A comparison with large-scale shell model calculations shows that 33Al has at least 50% intruder configurations in the ground state wave function, favoring the excitation of two neutrons across the N =20 shell gap. 33Al therefore clearly marks the gradual transition north of the deformed Na and Mg nuclei towards the normal Z ≥14 isotopes.

  20. Scaling of solid state lasers for satellite power beaming applications

    SciTech Connect

    Friedman, H.W.; Albrecht, G.F.; Beach, R.J.

    1994-01-01

    The power requirements for a satellite power beaming laser system depend upon the diameter of the beam director, the performance of the adaptive optics system, and the mission requirements. For an 8 meter beam director and overall Strehl ratio of 50%, a 30 kW laser at 850 nm can deliver an equivalent solar flux to a satellite at geostationary orbit. Advances in Diode Pumped Solid State Lasers (DPSSL) have brought these small, efficient and reliable devices to high average power and they should be considered for satellite power beaming applications. Two solid state systems are described: a diode pumped Alexandrite and diode pumped Thulium doped YAG. Both can deliver high average power at 850 nm in a single aperture.

  1. Scaling of solid state lasers for satellite power beaming applications

    SciTech Connect

    Friedman, H.; Albrecht, G.; Beach, R.

    1994-12-31

    The power requirements for a satellite power beaming laser system depend upon the diameter of the beam director, the performance of the adaptive optics system, and the mission requirements. For an 8 meter beam director and overall Strehl ratio of 50%, a 30 kW laser at 850 nm can deliver an equivalent solar flux to a satellite at geostationary orbit. Advances in Diode Pumped Solid State Lasers (DPSSL) have brought these small, efficient and reliable devices to high average power and they should be considered for satellite power beaming applications. Two solid state systems are described: a diode pumped Alexandrite and diode pumped Thulium doped YAG. Both can deliver high average power at 850 nm in a single aperture.

  2. Arsenic in Ground Water of the United States

    MedlinePlus

    ... v. 20, issue 5, p. 747-762. (2011) Mapping arsenic in groundwater: A real need, but a hard problem : Geotimes Newsmagazine of the Earth Sciences, v.46 no.11, p.34-36. (2001) DATA Arsenic in ground-water resources of the United States : U.S. Geological Survey Fact Sheet 063-00. (2000) A retrospective ...

  3. Quantum mechanical ground state of hydrogen obtained from classical electrodynamics

    NASA Astrophysics Data System (ADS)

    Cole, Daniel C.; Zou, Yi

    2003-10-01

    The behavior of a classical charged point particle under the influence of only a Coulombic binding potential and classical electromagnetic zero-point radiation, is shown to agree closely with the probability density distribution of Schrödinger's wave equation for the ground state of hydrogen. These results again raise the possibility that the main tenets of stochastic electrodynamics (SED) are correct.

  4. Selected bibliography of ground-water in the United States

    SciTech Connect

    Ward-McLemore, E.

    1984-01-01

    This bibliography contains 899 records related to the hydrology of the US. Specific topics include, but are not limited to: aquifers; artesian wells; geophysics; ground water; flow models; pollution; tritium; water levels; water policy; and legal aspects. The subject index provides listings of records related to each state. Some of the items (81) are themselves bibliographies.

  5. Nuclear ground-state masses and deformations: FRDM(2012)

    DOE PAGES

    Moller, P.; Sierk, A. J.; Ichikawa, T.; ...

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensivemore » and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.« less

  6. Nuclear ground-state masses and deformations: FRDM(2012)

    SciTech Connect

    Moller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  7. Ground states of the massless Derezinski-Gerard model

    SciTech Connect

    Ohkubo, Atsushi

    2009-11-15

    We consider the massless Derezinski-Gerard model introduced by Derezinski and Gerard in 1999. We give a sufficient condition for the existence of a ground state of the massless Derezinski-Gerard model without the assumption that the Hamiltonian of particles has compact resolvent.

  8. The wave function for the ground state of H

    NASA Astrophysics Data System (ADS)

    Fontenelle, Marcia T.; Gallas, Jason A. C.; Gallas, Marcia R.

    1986-10-01

    The ground-state energy of H(-) is investigated using a variational function proposed by Wu and Tsai (1985). Contrary to the conclusions of Wu and Tsai, it is found that the Wu and Tsai function produces results comparable with a previous calculation of Williamson (1942). Furthermore, the explicit formulas given in the present paper can easily be applied to the helium isoelectronic series.

  9. Advantages of Unfair Quantum Ground-State Sampling.

    PubMed

    Zhang, Brian Hu; Wagenbreth, Gene; Martin-Mayor, Victor; Hen, Itay

    2017-04-21

    The debate around the potential superiority of quantum annealers over their classical counterparts has been ongoing since the inception of the field. Recent technological breakthroughs, which have led to the manufacture of experimental prototypes of quantum annealing optimizers with sizes approaching the practical regime, have reignited this discussion. However, the demonstration of quantum annealing speedups remains to this day an elusive albeit coveted goal. We examine the power of quantum annealers to provide a different type of quantum enhancement of practical relevance, namely, their ability to serve as useful samplers from the ground-state manifolds of combinatorial optimization problems. We study, both numerically by simulating stoquastic and non-stoquastic quantum annealing processes, and experimentally, using a prototypical quantum annealing processor, the ability of quantum annealers to sample the ground-states of spin glasses differently than thermal samplers. We demonstrate that (i) quantum annealers sample the ground-state manifolds of spin glasses very differently than thermal optimizers (ii) the nature of the quantum fluctuations driving the annealing process has a decisive effect on the final distribution, and (iii) the experimental quantum annealer samples ground-state manifolds significantly differently than thermal and ideal quantum annealers. We illustrate how quantum annealers may serve as powerful tools when complementing standard sampling algorithms.

  10. Nuclear ground-state masses and deformations: FRDM(2012)

    NASA Astrophysics Data System (ADS)

    Möller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-05-01

    We tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A = 339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient L, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  11. Tuning ground states and excitations in complex electronic materials

    SciTech Connect

    Bishop, A.R.

    1996-09-01

    Modern electronic materials are characterized by a great variety of broken-symmetry ground states and excitations. Their control requires understanding and tuning underlying driving forces of spin-charge-lattice coupling, critical to macroscopic properties and applications. We report representative model calculations which demonstrate some of the richness of the phenomena and the challenges for successful microscopic modeling.

  12. Electronic Ground and Excited State Spectral Diffusion of a Photocatalyst

    NASA Astrophysics Data System (ADS)

    Kiefer, Laura M.; King, John T.; Kubarych, Kevin J.

    2014-06-01

    Re(bpy)(CO)_3Cl is a well studied CO_2 reduction catalyst, known for its ability as both a photosensitizer and a catalyst with a high quantum yield and product selectivity. The catalysis reaction is initiated by a 400 nm excitation, followed by an intersystem crossing (ISC) and re-equilibration in the lowest triplet state. We utilize the quasi-equilibrium nature of this long-lived triplet metal-to-ligand charge-transfer (3MLCT) state to completely characterize the solvent dynamics using the technique of transient two-dimensional infrared (t-2DIR) spectroscopy to extract observables such as the frequency-frequency correlation function (FFCF), an equilibrium function. The electronic ground state solvent dynamics are characterized using equilibrium two-dimensional infrared spectroscopy (2D IR). Our technique allows us to independently observe the solvent dynamics of different electronic states and compare them. In this study, three carbonyl stretching modes were utilized to probe both the intramolecular and solvent environments in each electronic state. In the electronic ground state, the totally symmetric mode exhibits pure homogeneous broadening and a lack of spectral dynamics, while the two other modes have similar FFCF decay times of ˜ 1.5 ps. In the 3MLCT, however, all three modes experience similar spectral dynamics and have a FFCF decay time of ˜ 4.5 ps, three times slower than in the electronic ground state. Our technique allows us to directly observe the differences in spectral dynamics of the ground and excited electronic states and allows us to attribute the differences to specific origins such as solvent-solute coupling and molecular flexibility.

  13. Speed of Markovian relaxation toward the ground state

    SciTech Connect

    Vogl, Malte; Schaller, Gernot; Brandes, Tobias

    2010-01-15

    For sufficiently low reservoir temperatures, it is known that open quantum systems subject to decoherent interactions with the reservoir relax toward their ground state in the weak coupling limit. Within the framework of quantum master equations, this is formalized by the Born-Markov-secular (BMS) approximation, where one obtains the system Gibbs state with the reservoir temperature as a stationary state. When the solution to some problem is encoded in the (isolated) ground state of a system Hamiltonian, decoherence can therefore be exploited for computation. The computational complexity is then given by the scaling of the relaxation time with the system size n. We study the relaxation behavior for local and nonlocal Hamiltonians that are coupled dissipatively with local and nonlocal operators to a bosonic bath in thermal equilibrium. We find that relaxation is generally more efficient when coherences of the density matrix in the system energy eigenbasis are taken into account. In addition, the relaxation speed strongly depends on the matrix elements of the coupling operators between initial state and ground state. We show that Dicke superradiance is a special case of our relaxation models and can thus be understood as a coherence-assisted relaxation speedup.

  14. Assessing the Ability of Ground-Penetrating Radar to Detect Fungal Decay in Douglas-Fir Beams

    Treesearch

    Christopher Adam Senalik; James Wacker; Xiping Wang; F. Jalinoos

    2016-01-01

    This paper describes the testing plan and current progress for assessing the efficacy of using ground-penetrating radar (GPR) to detect fungal decay within Douglas-fir beams. Initially, the beams were assessed using a variety of physical, mechanical, and nondestructive evaluation (NDE) test methods including micro-resistance drilling, Janka hardness, ultrasonic...

  15. Ground state occupation probabilities of neutrinoless double beta decay candidates

    NASA Astrophysics Data System (ADS)

    Kotila, Jenni; Barea, Jose

    2015-10-01

    A better understanding of nuclear structure can offer important constraints on the calculation of 0 νββ nuclear matrix elements. A simple way to consider differences between initial and final states of neutrinoless double beta decay candidates is to look at the ground state occupation probabilities of initial and final nuclei. As is well known, microscopic interacting boson model (IBM-2) has found to be very useful in the description of detailed aspects of nuclear structure. In this talk I will present results for ground state occupation probabilities obtained using IBM-2 for several interesting candidates of 0 νββ -decay. Comparison with recent experimental results is also made. This work was supported Academy of Finland (Project 266437) and Chilean Ministry of Education (Fondecyt Grant No. 1150564),

  16. Quantum quenches in the thermodynamic limit. II. Initial ground states.

    PubMed

    Rigol, Marcos

    2014-09-01

    A numerical linked-cluster algorithm was recently introduced to study quantum quenches in the thermodynamic limit starting from thermal initial states [M. Rigol, Phys. Rev. Lett. 112, 170601 (2014)]. Here, we tailor that algorithm to quenches starting from ground states. In particular, we study quenches from the ground state of the antiferromagnetic Ising model to the XXZ chain. Our results for spin correlations are shown to be in excellent agreement with recent analytical calculations based on the quench action method. We also show that they are different from the correlations in thermal equilibrium, which confirms the expectation that thermalization does not occur in general in integrable models even if they cannot be mapped to noninteracting ones.

  17. Scintillation and beam-wander analysis in an optical ground station-satellite uplink.

    PubMed

    Dios, Federico; Rubio, Juan Antonio; Rodrfguez, Alejandro; Comerón, Adolfo

    2004-07-01

    In an optical communication link between an optical ground station and a geostationary satellite the main problems appear in the uplink and are due to beam wander and to scintillation. Reliable methods for modeling both effects simultaneously are needed to provide an accurate tool with which the robustness of the communication channel can be tested. Numerical tools, especially the split-step method (also referred to as the fast-Fourier-transform beam propagation method), have demonstrated their ability to deal with problems of optical propagation during atmospheric turbulence. However, obtaining statistically significant results with this technique is computationally intensive. We present an analytical-numerical hybrid technique that provides good information on the variance in optical irradiance with an important saving of time and computational resources.

  18. Towards photonic quantum simulation of ground states of frustrated Heisenberg spin systems.

    PubMed

    Ma, Xiao-song; Dakić, Borivoje; Kropatschek, Sebastian; Naylor, William; Chan, Yang-hao; Gong, Zhe-xuan; Duan, Lu-ming; Zeilinger, Anton; Walther, Philip

    2014-01-07

    Photonic quantum simulators are promising candidates for providing insight into other small- to medium-sized quantum systems. Recent experiments have shown that photonic quantum systems have the advantage to exploit quantum interference for the quantum simulation of the ground state of Heisenberg spin systems. Here we experimentally characterize this quantum interference at a tuneable beam splitter and further investigate the measurement-induced interactions of a simulated four-spin system by comparing the entanglement dynamics using pairwise concurrence. We also study theoretically a four-site square lattice with next-nearest neighbor interactions and a six-site checkerboard lattice, which might be in reach of current technology.

  19. Towards photonic quantum simulation of ground states of frustrated Heisenberg spin systems

    PubMed Central

    Ma, Xiao-song; Dakić, Borivoje; Kropatschek, Sebastian; Naylor, William; Chan, Yang-hao; Gong, Zhe-xuan; Duan, Lu-ming; Zeilinger, Anton; Walther, Philip

    2014-01-01

    Photonic quantum simulators are promising candidates for providing insight into other small- to medium-sized quantum systems. Recent experiments have shown that photonic quantum systems have the advantage to exploit quantum interference for the quantum simulation of the ground state of Heisenberg spin systems. Here we experimentally characterize this quantum interference at a tuneable beam splitter and further investigate the measurement-induced interactions of a simulated four-spin system by comparing the entanglement dynamics using pairwise concurrence. We also study theoretically a four-site square lattice with next-nearest neighbor interactions and a six-site checkerboard lattice, which might be in reach of current technology. PMID:24394808

  20. Permanent Electron Electric Dipole Moment Search in the X^3Δ_1 Ground State of Tungsten Carbide Molecules

    NASA Astrophysics Data System (ADS)

    Lee, Jeongwon; Chen, Jinhai; Leanhardt, Aaron

    2011-06-01

    We are developing an experiment to search for the permanent electric dipole moment (EDM) of the electron using the valence electrons in the X^3Δ_1 ground state of Tungsten Carbide (WC) molecules. Currently, we are detecting the molecules by Laser Induced Fluorescence spectroscopy at ˜75cm downstream of a pulsed ablation beam source. We have a detection rate of ˜10 182W12C molecules/second in X^3Δ_1, v"=0, J"=1 state with geometric detection efficiency of 0.004. A continuous WC molecular beam is under development. Additionally, preliminary measurements of the 183W12C hyperfine structure will be presented.

  1. Guidelines for ground motion definition for the eastern United States

    SciTech Connect

    Gwaltney, R.C.; Aramayo, G.A.; Williams, R.T.

    1985-06-01

    Guidelines for the determination of earthquake ground motion definition for the eastern United States are established here. Both far-field and near-field guidelines are given. The guidelines were based on an extensive review of the current procedures for specifying ground motion in the United States. Both empirical and theoretical procedures were used in establishing the guidelines because of the low seismicity in the eastern United States. Only a few large- to great-sized earthquakes (M/sub s/ > 7.5) have occurred in this region, no evidence of tectonic surface ruptures related to historic or Holocene earthquakes has been found, and no currently active plate boundaries of any kind are known in this region. Very little instrumented data have been gathered in the East. Theoretical procedures are proposed so that in regions of almost no data, a reasonable level of seismic ground motion activity can be assumed. The guidelines are to be used to develop the safe shutdown earthquake (SSE). A new procedure for establishing the operating basis earthquake (OBE) is proposed, in particular for the eastern United States. The OBE would be developed using a probabilistic assessment of the geological conditions and the recurrence of seismic events at a site. These guidelines should be useful in development of seismic design requirements for future reactors. 17 refs., figs., tabs.

  2. Periodic Striped Ground States in Ising Models with Competing Interactions

    NASA Astrophysics Data System (ADS)

    Giuliani, Alessandro; Seiringer, Robert

    2016-11-01

    We consider Ising models in two and three dimensions, with short range ferromagnetic and long range, power-law decaying, antiferromagnetic interactions. We let J be the ratio between the strength of the ferromagnetic to antiferromagnetic interactions. The competition between these two kinds of interactions induces the system to form domains of minus spins in a background of plus spins, or vice versa. If the decay exponent p of the long range interaction is larger than d + 1, with d the space dimension, this happens for all values of J smaller than a critical value J c ( p), beyond which the ground state is homogeneous. In this paper, we give a characterization of the infinite volume ground states of the system, for p > 2 d and J in a left neighborhood of J c ( p). In particular, we prove that the quasi-one-dimensional states consisting of infinite stripes ( d = 2) or slabs ( d = 3), all of the same optimal width and orientation, and alternating magnetization, are infinite volume ground states. Our proof is based on localization bounds combined with reflection positivity.

  3. Scintillation model of laser beam propagation in satellite-to-ground bidirectional atmospheric channels

    NASA Astrophysics Data System (ADS)

    Toyoshima, Morio; Sasaki, Takashi; Takenaka, Hideki; Takayama, Yoshihisa

    2012-11-01

    This paper discusses a scintillation model of laser beam propagation in satellite-to-ground bidirectional atmospheric channels. The frequency characteristics of the downlink were theoretically derived on the basis of measurements in low Earth orbit satellite-to-ground laser communication experiments. The speckle patterns were averaged and the frequency response of the received optical signal was filtered by a telescope aperture. The model parameters were obtained by fitting the results to the model. This paper introduces scaling factors for the uplink and extends the theory for the downlink to that for the uplink. The proposed model can generate time-varying optical signals based on the von Kármán spectrum for space-to-ground laser links. The scintillation index was estimated using the modified Hufnagel-Valley model, which was obtained from real measurements. The probability density function was fitted by the estimated scintillation index and compared to the gamma-gamma distribution under strong turbulence conditions. The scaling factor for the root mean square wind speed was newly introduced to fit the frequency spectra for the uplink. The simulation results are presented in this paper. The proposed scintillation model can contribute to improving the fading simulation of satellite-to-ground communication links as well as add to the future discussion of standards, like those proposed by the Consultative Committee for Space Data Systems.

  4. Bonding and electronic states of boron in silicon nanowires characterized by an infrared synchrotron radiation beam

    NASA Astrophysics Data System (ADS)

    Fukata, N.; Jevasuwan, W.; Ikemoto, Y.; Moriwaki, T.

    2015-04-01

    The infrared synchrotron radiation (IR-SR) beamline of SPring-8 as an IR light source was applied to characterize boron (B) atoms in silicon nanowires (SiNWs). The use of an IR-SR beam with much higher brilliance than conventional IR light sources and a wide range of wavenumbers from visible to far IR regions made it possible to detect a local vibrational mode of B in SiNWs. The use of this technique has also made it possible to detect other IR peaks related to transitions of a bound hole from the ground state of a B acceptor atom to excited states, clarifying the electronic state of B acceptors in SiNWs.The infrared synchrotron radiation (IR-SR) beamline of SPring-8 as an IR light source was applied to characterize boron (B) atoms in silicon nanowires (SiNWs). The use of an IR-SR beam with much higher brilliance than conventional IR light sources and a wide range of wavenumbers from visible to far IR regions made it possible to detect a local vibrational mode of B in SiNWs. The use of this technique has also made it possible to detect other IR peaks related to transitions of a bound hole from the ground state of a B acceptor atom to excited states, clarifying the electronic state of B acceptors in SiNWs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00427f

  5. Controlling laser beam irradiation area using an optical duplicate system to improve satellite-ground laser communications

    NASA Astrophysics Data System (ADS)

    Nakayama, Tomoko; Takayama, Yoshihisa; Fujikawa, Chiemi; Kodate, Kashiko

    2016-08-01

    To improve the quality of ground to satellite laser communications, we propose an optical duplicate system of the optical ground station. Our proposed approach can be used to control the beam irradiation area for a satellite position without changing the total power of the output beam and the mechanical drive unit; this is performed by controlling the input pattern of a liquid crystal filter inserted in the input plane of the optical duplicate system. Most of the power of the diffracted laser beam emitted from the ground is focused on the optical axis. By distributing the power to side lobes, it is possible to extend the coverage area for a satellite position. This system allows the laser beam irradiation area to be controlled by a sufficient degree by adjusting the threshold of the satellite reception level. We verify the efficacy of the system using wave optics numerical calculations.

  6. Coupled cluster calculation for ground state properties of closed-shell nuclei and single hole states.

    NASA Astrophysics Data System (ADS)

    Mihaila, Bogdan; Heisenberg, Jochen

    2000-04-01

    We continue the investigations of ground state properties of closed-shell nuclei using the Argonne v18 realistic NN potential, together with the Urbana IX three-nucleon interaction. The ground state wave function is used to calculate the charge form factor and charge density. Starting with the ground state wave function of the closed-shell nucleus, we use the equation of motion technique to calculate the ground state and excited states of a neighboring nucleus. We then generate the corresponding magnetic form factor. We correct for distortions due to the interaction between the electron probe and the nuclear Coulomb field using the DWBA picture. We compare our results with the available experimental data. Even though our presentation will focus mainly on the ^16O and ^15N nuclei, results for other nuclei in the p and s-d shell will also be presented.

  7. Preparation of state purified beams of He, Ne, C, N, and O atoms

    SciTech Connect

    Jankunas, Justin; Reisyan, Kevin S.; Osterwalder, Andreas

    2015-03-14

    The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He({sup 3}S{sub 1}) and Ne({sup 3}P{sub 2}), and of ground state N({sup 4}S{sub 3/2}) and O({sup 3}P{sub 2}) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C({sup 3}P{sub 2}; {sup 1}D{sub 2}) and N({sup 2}D{sub 5/2}; {sup 2}P{sub 3/2}) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)].

  8. Ground-state structures of atomic metallic hydrogen.

    PubMed

    McMahon, Jeffrey M; Ceperley, David M

    2011-04-22

    Ab initio random structure searching using density functional theory is used to determine the ground-state structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including proton zero-point motion within the harmonic approximation, we estimate that molecular hydrogen dissociates into a monatomic body-centered tetragonal structure near 500 GPa (r(s)=1.23) that remains stable to 1 TPa (r(s)=1.11). At higher pressures, hydrogen stabilizes in an …ABCABC… planar structure that is similar to the ground state of lithium, but with a different stacking sequence. With increasing pressure, this structure compresses to the face-centered cubic lattice near 3.5 TPa (r(s)=0.92).

  9. Ground State Energy of the Low Density Hubbard Model

    NASA Astrophysics Data System (ADS)

    Seiringer, Robert; Yin, Jun

    2008-06-01

    We derive a lower bound on the ground state energy of the Hubbard model for given value of the total spin. In combination with the upper bound derived previously by Giuliani (J. Math. Phys. 48:023302, [2007]), our result proves that in the low density limit the leading order correction compared to the ground state energy of a non-interacting lattice Fermi gas is given by 8 π a ϱ u ϱ d , where ϱ u( d) denotes the density of the spin-up (down) particles, and a is the scattering length of the contact interaction potential. This result extends previous work on the corresponding continuum model to the lattice case.

  10. The valence-fluctuating ground state of plutonium.

    PubMed

    Janoschek, Marc; Das, Pinaki; Chakrabarti, Bismayan; Abernathy, Douglas L; Lumsden, Mark D; Lawrence, John M; Thompson, Joe D; Lander, Gerard H; Mitchell, Jeremy N; Richmond, Scott; Ramos, Mike; Trouw, Frans; Zhu, Jian-Xin; Haule, Kristjan; Kotliar, Gabriel; Bauer, Eric D

    2015-07-01

    A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium's magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.

  11. Eliminating zebrafish pbx proteins reveals a hindbrain ground state.

    PubMed

    Waskiewicz, Andrew Jan; Rikhof, Holly A; Moens, Cecilia B

    2002-11-01

    The vertebrate hindbrain is divided into serially homologous segments, the rhombomeres (r). Pbx and Hox proteins are hypothesized to form heterodimeric, DNA binding transcription complexes which specify rhombomere identities. Here, we show that eliminating zebrafish Lzr/Pbx4 and Pbx2 function prevents hindbrain segmentation and causes a wholesale anterior homeotic transformation of r2-r6, to r1 identity. We demonstrate that Pbx proteins interact with Hox paralog group 1 proteins to specify segment identities broadly within the hindbrain, and that this process involves the Pbx:Hox-1-dependent induction of Fgf signals in r4. We propose that in the absence of Pbx function, r2-r6 acquire a homogeneous ground state identity, that of r1, and that Pbx proteins, functioning primarily with their Hox partners, function to modify this ground state identity during normal hindbrain development.

  12. The valence-fluctuating ground state of plutonium

    SciTech Connect

    Janoschek, Marc; Das, Pinaki; Chakrabarti, Bismayan; Abernathy, Douglas L.; Lumsden, Mark D.; Lawrence, John M.; Thompson, Joe D.; Lander, Gerard H.; Mitchell, Jeremy N.; Richmond, Scott; Ramos, Mike; Trouw, Frans; Zhu, Jian -Xin; Haule, Kristjan; Kotliar, Gabriel; Bauer, Eric D.

    2015-07-10

    A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. In addition, our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.

  13. NEW GROUND-STATE MEASUREMENTS OF ETHYL CYANIDE

    SciTech Connect

    Brauer, Carolyn S.; Pearson, John C.; Drouin, Brian J.; Yu, Shanshan

    2009-09-01

    The spectrum of ethyl cyanide, or propionitrile (CH{sub 3}CH{sub 2}CN), has been repeatedly observed in the interstellar medium with large column densities and surprisingly high temperatures in hot core sources. The construction of new, more sensitive, observatories accessing higher frequencies such as Herschel, ALMA, and SOFIA have made it important to extend the laboratory data for ethyl cyanide to coincide with the capabilities of the new instruments. We report extensions of the laboratory measurements of the rotational spectrum of ethyl cyanide in its ground vibrational state to 1.6 THz. A global analysis of the ground state, which includes all of the previous data and 3356 newly assigned transitions, has been fitted to within experimental error to J = 132, K = 36, using both Watson A-reduced and Watson S-reduced Hamiltonians.

  14. Room temperature skyrmion ground state stabilized through interlayer exchange coupling

    SciTech Connect

    Chen, Gong Schmid, Andreas K.; Mascaraque, Arantzazu; N'Diaye, Alpha T.

    2015-06-15

    Possible magnetic skyrmion device applications motivate the search for structures that extend the stability of skyrmion spin textures to ambient temperature. Here, we demonstrate an experimental approach to stabilize a room temperature skyrmion ground state in chiral magnetic films via exchange coupling across non-magnetic spacer layers. Using spin polarized low-energy electron microscopy to measure all three Cartesian components of the magnetization vector, we image the spin textures in Fe/Ni films. We show how tuning the thickness of a copper spacer layer between chiral Fe/Ni films and perpendicularly magnetized Ni layers permits stabilization of a chiral stripe phase, a skyrmion phase, and a single domain phase. This strategy to stabilize skyrmion ground states can be extended to other magnetic thin film systems and may be useful for designing skyrmion based spintronics devices.

  15. Ground-State Phase Diagram of S = 1 Diamond Chains

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'ichi

    2017-03-01

    We investigate the ground-state phase diagram of a spin-1 diamond chain. Owing to a series of conservation laws, any eigenstate of this system can be expressed using the eigenstates of finite odd-length chains or infinite chains with spins 1 and 2. The ground state undergoes quantum phase transitions with varying λ, a parameter that controls frustration. Exact upper and lower bounds for the phase boundaries between these phases are obtained. The phase boundaries are determined numerically in the region not explored in a previous work [Takano et al., J. Phys.: Condens. Matter 8, 6405 (1996)].

  16. Monte Carlo Ground State Energy for Trapped Boson Systems

    NASA Astrophysics Data System (ADS)

    Rudd, Ethan; Mehta, N. P.

    2012-06-01

    Diffusion Monte Carlo (DMC) and Green's Function Monte Carlo (GFMC) algorithms were implemented to obtain numerical approximations for the ground state energies of systems of bosons in a harmonic trap potential. Gaussian pairwise particle interactions of the form V0e^-|ri-rj|^2/r0^2 were implemented in the DMC code. These results were verified for small values of V0 via a first-order perturbation theory approximation for which the N-particle matrix element evaluated to N2 V0(1 + 1/r0^2)^3/2. By obtaining the scattering length from the 2-body potential in the perturbative regime (V0φ 1), ground state energy results were compared to modern renormalized models by P.R. Johnson et. al, New J. Phys. 11, 093022 (2009).

  17. The valence-fluctuating ground state of plutonium

    PubMed Central

    Janoschek, Marc; Das, Pinaki; Chakrabarti, Bismayan; Abernathy, Douglas L.; Lumsden, Mark D.; Lawrence, John M.; Thompson, Joe D.; Lander, Gerard H.; Mitchell, Jeremy N.; Richmond, Scott; Ramos, Mike; Trouw, Frans; Zhu, Jian-Xin; Haule, Kristjan; Kotliar, Gabriel; Bauer, Eric D.

    2015-01-01

    A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials. PMID:26601219

  18. Simulation of the hydrogen ground state in stochastic electrodynamics

    NASA Astrophysics Data System (ADS)

    Nieuwenhuizen, Theo M.; Liska, Matthew T. P.

    2015-10-01

    Stochastic electrodynamics is a classical theory which assumes that the physical vacuum consists of classical stochastic fields with average energy \\frac{1}{2}{{\\hslash }}ω in each mode, i.e., the zero-point Planck spectrum. While this classical theory explains many quantum phenomena related to harmonic oscillator problems, hard results on nonlinear systems are still lacking. In this work the hydrogen ground state is studied by numerically solving the Abraham-Lorentz equation in the dipole approximation. First the stochastic Gaussian field is represented by a sum over Gaussian frequency components, next the dynamics is solved numerically using OpenCL. The approach improves on work by Cole and Zou 2003 by treating the full 3d problem and reaching longer simulation times. The results are compared with a conjecture for the ground state phase space density. Though short time results suggest a trend towards confirmation, in all attempted modellings the atom ionises at longer times.

  19. Multichiral ground states in mesoscopic p -wave superconductors

    NASA Astrophysics Data System (ADS)

    Becerra, V. Fernández; Milošević, M. V.

    2016-11-01

    Using Ginzburg-Landau formalism, we investigate the effect of confinement on the ground state of mesoscopic chiral p -wave superconductors in the absence of magnetic field. We reveal stable multichiral states with domain walls separating the regions with different chiralities, as well as monochiral states with spontaneous currents flowing along the edges. We show that multichiral states can exhibit identifying signatures in the spatial profile of the magnetic field if those are not screened by edge currents in the case of strong confinement. Such magnetic detection of domain walls in topological superconductors can serve as long-sought evidence of broken time-reversal symmetry. Furthermore, when applying electric current to mesoscopic p -wave samples, we found a hysteretic behavior in the current-voltage characteristic that distinguishes states with and without domain walls, thereby providing another useful hallmark for indirect confirmation of chiral p -wave superconductivity.

  20. Tuning the Ground State Symmetry of Acetylenyl Radicals

    PubMed Central

    2015-01-01

    The lowest excited state of the acetylenyl radical, HCC, is a 2Π state, only 0.46 eV above the ground state, 2Σ+. The promotion of an electron from a π bond pair to a singly occupied σ hybrid orbital is all that is involved, and so we set out to tune those orbital energies, and with them the relative energetics of 2Π and 2Σ+ states. A strategy of varying ligand electronegativity, employed in a previous study on substituted carbynes, RC, was useful, but proved more difficult to apply for substituted acetylenyl radicals, RCC. However, π-donor/acceptor substitution is effective in modifying the state energies. We are able to design molecules with 2Π ground states (NaOCC, H2NCC (2A″), HCSi, FCSi, etc.) and vary the 2Σ+–2Π energy gap over a 4 eV range. We find an inconsistency between bond order and bond dissociation energy measures of the bond strength in the Si-containing molecules; we provide an explanation through an analysis of the relevant potential energy curves. PMID:27162981

  1. Ground state nonuniversality in the random-field Ising model

    SciTech Connect

    Duxbury, P. M.; Meinke, J. H.

    2001-09-01

    Two attractive and often used ideas, namely, universality and the concept of a zero-temperature fixed point, are violated in the infinite-range random-field Ising model. In the ground state we show that the exponents can depend continuously on the disorder and so are nonuniversal. However, we also show that at finite temperature the thermal order-parameter exponent 1/2 is restored so that temperature is a relevant variable. Broader implications of these results are discussed.

  2. Electronic and ground state properties of ThTe

    SciTech Connect

    Bhardwaj, Purvee Singh, Sadhna

    2016-05-06

    The electronic properties of ThTe in cesium chloride (CsCl, B2) structure are investigated in the present paper. To study the ground state properties of thorium chalcogenide, the first principle calculations have been calculated. The bulk properties, including lattice constant, bulk modulus and its pressure derivative are obtained. The calculated equilibrium structural parameters are in good agreement with the available experimental and theoretical results.

  3. The Fair in Unfair Quantum Ground-state Sampling

    NASA Astrophysics Data System (ADS)

    Hen, I.; Martin-Mayor, V.; Zhang, B.

    2016-12-01

    The debate around the potential superiority of quantum annealers over their classical counterparts has been ongoing since the inception of the field by Kadowaki and Nishimori close to two decades ago. Recent technological advancements in the field, which have led to the manufacture of experimental prototypes of quantum annealing optimizers with sizes approaching the practical regime have reignited this discussion. However, the demonstration of quantum annealing speedups remains to this day an elusive albeit coveted goal. Here, we examine the power of quantum annealers to provide quantum enhancements when used as samplers from distributions of bit configurations rather than as ground state optimizers. We study, both numerically by simulating stoquastic and as non-stoquastic quantum annealing processes, and experimentally using the D-Wave Two putative quantum annealing optimizer, the ability of quantum annealers to sample the ground state manifolds of spin glasses -- a type of problems that appears in diverse areas of science and technology such has circuit fault detection, verification & validation, graph isomorphism and more. We show that quantum annealers sample the ground state manifolds of spin glasses potentially very differently than classical algorithms, and may potentially serve as a powerful tool in complementing traditional approaches.

  4. Alternative ground states enable pathway switching in biological electron transfer

    SciTech Connect

    Abriata, Luciano A.; Alvarez-Paggi, Damian; Ledesma, Gabirela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.

    2012-10-10

    Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. In conclusion, these findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction.

  5. Available energy and ground states of collisionless plasmas

    NASA Astrophysics Data System (ADS)

    Helander, Per

    2017-08-01

    The energy budget of a collisionless plasma subject to electrostatic fluctuations is considered, and the excess of thermal energy over the minimum accessible to it under various constraints that limit the possible forms of plasma motion is calculated. This excess measures how much thermal energy is `available' for conversion into plasma instabilities, and therefore constitutes a nonlinear measure of plasma stability. A distribution function with zero available energy defines a `ground state' in the sense that its energy cannot decrease by any linear or nonlinear plasma motion. In a Vlasov plasma with small density and temperature fluctuations, the available energy is proportional to the mean square of these quantities, and exceeds the corresponding energy in ideal or resistive magnetohydrodynamics. If the first or second adiabatic invariant is conserved, ground states generally have inhomogeneous density and temperature. Magnetically confined plasmas are usually not in any ground state, but certain types of stellarator plasmas are so with respect to fluctuations that conserve both these adiabatic invariants, making the plasma linearly and nonlinearly stable to such fluctuations. Similar stability properties can also be enjoyed by plasmas confined by a dipole magnetic field.

  6. Ground state magnetic response of two coupled dodecahedra

    NASA Astrophysics Data System (ADS)

    Konstantinidis, N. P.

    2016-01-01

    The antiferromagnetic Heisenberg model on the dodecahedron possesses a number of ground state magnetization discontinuities in a field at the classical and quantum level, even though it lacks magnetic anisotropy. Here the model is considered for two dodecahedra coupled antiferromagnetically along one of their faces, as a first step to determine the magnetic response of collections of fullerene molecules. The magnetic response is determined from the competition among the intra-, interdodecahedral exchange and magnetic field energies. At the classical level the discontinuities of the isolated dodecahedron are renormalized by the interdodecahedral coupling, while new ones show up, with the maximum number of ground state discontinuities being six for a specific range of the coupling. In the full quantum limit where the individual spin magnitude s=\\frac{1}{2} , there are two ground state discontinuities originating in the single discontinuity of the isolated dodecahedron, and another one due to the intermolecular coupling, generating a total of three discontinuities which come one right after the other. These results show that the magnetic response of more than one dodecahedra interacting together is quite richer than the one of a single dodecahedron.

  7. Ground state magnetic response of two coupled dodecahedra.

    PubMed

    Konstantinidis, N P

    2016-01-13

    The antiferromagnetic Heisenberg model on the dodecahedron possesses a number of ground state magnetization discontinuities in a field at the classical and quantum level, even though it lacks magnetic anisotropy. Here the model is considered for two dodecahedra coupled antiferromagnetically along one of their faces, as a first step to determine the magnetic response of collections of fullerene molecules. The magnetic response is determined from the competition among the intra-, interdodecahedral exchange and magnetic field energies. At the classical level the discontinuities of the isolated dodecahedron are renormalized by the interdodecahedral coupling, while new ones show up, with the maximum number of ground state discontinuities being six for a specific range of the coupling. In the full quantum limit where the individual spin magnitude [Formula: see text], there are two ground state discontinuities originating in the single discontinuity of the isolated dodecahedron, and another one due to the intermolecular coupling, generating a total of three discontinuities which come one right after the other. These results show that the magnetic response of more than one dodecahedra interacting together is quite richer than the one of a single dodecahedron.

  8. Alternative ground states enable pathway switching in biological electron transfer

    DOE PAGES

    Abriata, Luciano A.; Alvarez-Paggi, Damian; Ledesma, Gabirela N.; ...

    2012-10-10

    Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronicmore » wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. In conclusion, these findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction.« less

  9. Alternative ground states enable pathway switching in biological electron transfer

    PubMed Central

    Abriata, Luciano A.; Álvarez-Paggi, Damián; Ledesma, Gabriela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.

    2012-01-01

    Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction. PMID:23054836

  10. Alternative ground states enable pathway switching in biological electron transfer.

    PubMed

    Abriata, Luciano A; Álvarez-Paggi, Damián; Ledesma, Gabriela N; Blackburn, Ninian J; Vila, Alejandro J; Murgida, Daniel H

    2012-10-23

    Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant Cu(A) redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or "invisible" electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein-protein interactions and membrane potential may optimize and regulate electron-proton energy transduction.

  11. Efficient determination of alloy ground-state structures

    NASA Astrophysics Data System (ADS)

    Seko, Atsuto; Shitara, Kazuki; Tanaka, Isao

    2014-11-01

    We propose an efficient approach to accurately finding the ground-state structures in alloys based on the cluster expansion method. In this approach, a small number of candidate ground-state structures are obtained without any information regarding the energy. To generate the candidates, we employ the convex hull constructed from the correlation functions of all possible structures by using an efficient algorithm. This approach is applicable to not only simple lattices, but also complex lattices. First, we evaluate the convex hulls for binary alloys with four types of simple lattice. Then we discuss the structures on the vertices. To examine the accuracy of this approach, we perform a set of density functional theory calculations and the cluster expansion for the Ag-Au alloy and compare the formation energies of the vertex structures with those of all possible structures. As applications, the ground-state structures of the intermetallic compounds CuAu, CuAg, CuPd, AuAg, AuPd, AgPd, MoTa, MoW, and TaW are similarly evaluated. Finally, the energy distribution is obtained for different cation arrangements in the MgAl2O4 spinel, for which long-range interactions are essential for the accurate description of its energetics.

  12. Condensed ground states of frustrated Bose-Hubbard models

    SciTech Connect

    Moeller, G.; Cooper, N. R.

    2010-12-15

    We study theoretically the ground states of two-dimensional Bose-Hubbard models which are frustrated by gauge fields. Motivated by recent proposals for the implementation of optically induced gauge potentials, we focus on the situation in which the imposed gauge fields give rise to a pattern of staggered fluxes of magnitude {alpha} and alternating in sign along one of the principal axes. For {alpha}=1/2 this model is equivalent to the case of uniform flux per plaquette n{sub {phi}=}1/2, which, in the hard-core limit, realizes the 'fully frustrated' spin-1/2 XY model. We show that the mean-field ground states of this frustrated Bose-Hubbard model typically break translational symmetry. Given the presence of both a non-zero superfluid fraction and translational symmetry breaking, these phases are supersolid. We introduce a general numerical technique to detect broken symmetry condensates in exact diagonalization studies. Using this technique we show that, for all cases studied, the ground state of the Bose-Hubbard model with staggered flux {alpha} is condensed, and we obtain quantitative determinations of the condensate fraction. We discuss the experimental consequences of our results. In particular, we explain the meaning of gauge invariance in ultracold-atom systems subject to optically induced gauge potentials and show how the ability to imprint phase patterns prior to expansion can allow very useful additional information to be extracted from expansion images.

  13. Charge-state enhancement for radioactive beam post-acceleration

    SciTech Connect

    Nolen, J.A.; Dooling, J.

    1995-08-01

    A critical question for an ISOL-type radioactive-beam facility, such as that being discussed by the North American Isospin Laboratory Committee, is the efficiency and q/m of the ion source for the radioactive species. ISOLDE at CERN demonstrated that high efficiency is obtained for a wide variety of species in the 1{sup +} charge state. These ion sources also generally have excellent transverse emittances and low energy spreads. One possibility is to use this proven technology plus an ionizer stage to increase the output of such sources to 2, 3, or 4{sup +} with high efficiency. We are currently investigating technical options for such charge-state enhancement. There is a proposal by a Heidelberg/ISOLDE collaboration to build a {open_quotes}charge-state breeder{close_quotes} as part of an experiment called REX-ISOLDE. This concept would deliver batches of radioactive ions with low duty cycle, optimized for relatively low-intensity secondary beams, on the order of 10{sup 6}/sec. We are independently doing simulations of an alternative approach, called the Electron-Beam Charge-State Amplifier (EBQA), which would yield DC beams with improved transverse emittance and would not have the intensity limitation of the batch transfer process. The cost and efficiency of the EBQA will have to be compared with those of a normally-conducting CW RFQ followed by ion stripping, as alternatives for the first stage of a secondary ion accelerator.

  14. A six-beam method to measure turbulence statistics using ground-based wind lidars

    NASA Astrophysics Data System (ADS)

    Sathe, A.; Mann, J.; Vasiljevic, N.; Lea, G.

    2014-10-01

    A so-called six-beam method is proposed to measure atmospheric turbulence using a ground-based wind lidar. This method requires measurement of the radial velocity variances at five equally spaced azimuth angles on the base of a scanning cone and one measurement at the center of the scanning circle, i.e.using a vertical beam at the same height. The scanning configuration is optimized to minimize the sum of the random errors in the measurement of the second-order moments of the components (u,v, w) of the wind field. We present this method as an alternative to the so-called velocity azimuth display (VAD) method that is routinely used in commercial wind lidars, and which usually results in significant averaging effects of measured turbulence. In the VAD method, the high frequency radial velocity measurements are used instead of their variances. The measurements are performed using a pulsed lidar (WindScanner), and the derived turbulence statistics (using both methods) such as the u and v variances are compared with those obtained from a reference cup anemometer and a wind vane at 89 m height under different atmospheric stabilities. The measurements show that in comparison to the reference cup anemometer, depending on the atmospheric stability and the wind field component, the six-beam method measures between 85-101% of the reference turbulence, whereas the VAD method measures between 66-87% of the reference turbulence.

  15. A six-beam method to measure turbulence statistics using ground-based wind lidars

    NASA Astrophysics Data System (ADS)

    Sathe, A.; Mann, J.; Vasiljevic, N.; Lea, G.

    2015-02-01

    A so-called six-beam method is proposed to measure atmospheric turbulence using a ground-based wind lidar. This method requires measurement of the radial velocity variances at five equally spaced azimuth angles on the base of a scanning cone and one measurement at the centre of the scanning circle, i.e.using a vertical beam at the same height. The scanning configuration is optimized to minimize the sum of the random errors in the measurement of the second-order moments of the components (u,v, w) of the wind field. We present this method as an alternative to the so-called velocity azimuth display (VAD) method that is routinely used in commercial wind lidars, and which usually results in significant averaging effects of measured turbulence. In the VAD method, the high frequency radial velocity measurements are used instead of their variances. The measurements are performed using a pulsed lidar (WindScanner), and the derived turbulence statistics (using both methods) such as the u and v variances are compared with those obtained from a reference cup anemometer and a wind vane at 89 m height under different atmospheric stabilities. The measurements show that in comparison to the reference cup anemometer, depending on the atmospheric stability and the wind field component, the six-beam method measures between 85 and 101% of the reference turbulence, whereas the VAD method measures between 66 and 87% of the reference turbulence.

  16. Ground states of fermionic lattice Hamiltonians with permutation symmetry

    NASA Astrophysics Data System (ADS)

    Kraus, Christina V.; Lewenstein, Maciej; Cirac, J. Ignacio

    2013-08-01

    We study the ground states of lattice Hamiltonians that are invariant under permutations, in the limit where the number of lattice sites N→∞. For spin systems, these are product states, a fact that follows directly from the quantum de Finetti theorem. For fermionic systems, however, the problem is very different, since mode operators acting on different sites do not commute, but anticommute. We construct a family of fermionic states, F, from which such ground states can be easily computed. They are characterized by few parameters whose number only depends on M, the number of modes per lattice site. We also give an explicit construction for M=1,2. In the first case, F is contained in the set of Gaussian states, whereas in the second it is not. Inspired by that construction, we build a set of fermionic variational wave functions, and apply it to the Fermi-Hubbard model in two spatial dimensions, obtaining results that go beyond the generalized Hartree-Fock theory.

  17. Two different ground states in K-intercalated polyacenes

    NASA Astrophysics Data System (ADS)

    Phan, Quynh T. N.; Heguri, Satoshi; Tamura, Hiroyuki; Nakano, Takehito; Nozue, Yasuo; Tanigaki, Katsumi

    2016-02-01

    The electronic states of potassium- (K-) intercalated zigzag-type polycyclic aromatic (PLA) hydrocarbon [polyacene PLAs] Kx(PLAs ) are studied for a series of the four smallest molecules: naphthalene (NN), anthracene (AN), tetracene (TN), and pentacene (PN), focusing on their 1:1 stoichiometric phases. Clear experimental differences are identified between the first group [K1(NN ) and K1(AN ) ] and the second group [K1(TN ) and K1(PN ) ] by magnetic, vibrational, and optical measurements. The first group is categorized as a Mott insulator with an antiferromagnetic ground state with energy of ˜10 meV, whereas the second group is classified as a band insulator via dimer formation due to the spin Peierls instability. In the latter system, the first thermally accessible triplet states are located far apart from the singlet ground states and are not detected by electron spin-resonance spectroscopy until 300 K being very different from what is observed for the hole-doped PN reported earlier. The results give a new systematic understanding on the electronic states of electron-doped PLAs sensitive to the energetic balance among on-site Coulomb repulsion, bandwidth, and the Peierls instability.

  18. Ground state energies from converging and diverging power series expansions

    NASA Astrophysics Data System (ADS)

    Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E.; Su, Q.; Grobe, R.

    2016-10-01

    It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh-Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state's spatial extension is comparable to L. Once the binding strength is so strong that the ground state's extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

  19. Continuous Vibrational Cooling of Ground State Rb2

    NASA Astrophysics Data System (ADS)

    Tallant, Jonathan; Marcassa, Luis

    2014-05-01

    The process of photoassociation generally results in a distribution of vibrational levels in the electronic ground state that is energetically close to the dissociation limit. Several schemes have appeared that aim to transfer the population from the higher vibrational levels to lower ones, especially the ground vibrational state. We demonstrate continuous production of vibrationally cooled Rb2 using optical pumping. The vibrationally cooled molecules are produced in three steps. First, we use a dedicated photoassociation laser to produce molecules in high vibrational levels of the X1Σg+ state. Second, a broadband fiber laser at 1071 nm is used to transfer the molecules to lower vibrational levels via optical pumping through the A1Σu+ state. This process transfers the molecules from vibrational levels around ν ~= 113 to a distribution of levels where ν < 35. The molecules may then be further cooled using a broadband superluminescent diode near 685 nm that has its frequency spectrum shaped. The resulting vibrational distributions are probed using resonance-enhanced multiphoton ionization with a pulsed dye laser near 670 nm. The results are presented and compared with theoretical simulations. This work was supported by Fapesp and INCT-IQ.

  20. Klf4 reverts developmentally programmed restriction of ground state pluripotency

    PubMed Central

    Guo, Ge; Yang, Jian; Nichols, Jennifer; Hall, John Simon; Eyres, Isobel; Mansfield, William; Smith, Austin

    2009-01-01

    Summary Mouse embryonic stem (ES) cells derived from pluripotent early epiblast contribute functionally differentiated progeny to all foetal lineages of chimaeras. By contrast, epistem cell (EpiSC) lines from post-implantation epithelialised epiblast are unable to colonise the embryo even though they express the core pluripotency genes Oct4, Sox2 and Nanog. We examined interconversion between these two cell types. ES cells can readily become EpiSCs in response to growth factor cues. By contrast, EpiSCs do not change into ES cells. We exploited PiggyBac transposition to introduce a single reprogramming factor, Klf4, into EpiSCs. No effect was apparent in EpiSC culture conditions, but in ground state ES cell conditions a fraction of cells formed undifferentiated colonies. These EpiSC-derived induced pluripotent stem (Epi-iPS) cells activated expression of ES cell-specific transcripts including endogenous Klf4, and downregulated markers of lineage specification. X chromosome silencing in female cells, a feature of the EpiSC state, was erased in Epi-iPS cells. They produced high-contribution chimaeras that yielded germline transmission. These properties were maintained after Cre-mediated deletion of the Klf4 transgene, formally demonstrating complete and stable reprogramming of developmental phenotype. Thus, re-expression of Klf4 in an appropriate environment can regenerate the naïve ground state from EpiSCs. Reprogramming is dependent on suppression of extrinsic growth factor stimuli and proceeds to completion in less than 1% of cells. This substantiates the argument that EpiSCs are developmentally, epigenetically and functionally differentiated from ES cells. However, because a single transgene is the minimum requirement to attain the ground state, EpiSCs offer an attractive opportunity for screening for unknown components of the reprogramming process. PMID:19224983

  1. Equatorial ground ice on Mars: Steady-state stability

    NASA Technical Reports Server (NTRS)

    Mellon, Michael T.; Jakosky, Bruce M.; Postawko, Susan E.

    1993-01-01

    Current Martian equatorial surface temperatures are too warm for water ice to exist at the surface for any appreciable length of time before subliming into the atmosphere. Subsurface temperatures are generally warmer still and, despite the presence of a diffusive barrier of porous regolith material, it has been shown by Smoluchowski, Clifford and Hillel, and Fanale et al. that buried ground ice will also sublime and be lost to the atmosphere in a relatively short time. We investigate the behavior of this subliming subsurface ice and show that it is possible for ice to maintain at a steady-state depth, where sublimation and diffusive loss to the atmosphere is balanced by resupply from beneath by diffusion and recondensation of either a deeper buried ice deposits or ground water. We examine the behavior of equatorial ground ice with a numercial time-marching molecular diffusion model. In our model we allow for diffusion of water vapor through a porous regolith, variations in diffusivity and porosity with ice content, and recondensation of sublimed water vapor. A regolith containing considerable amounts of ice can still be very porous, allowing water vapor to diffuse up from deeper within the ice layer where temperatures are warmer due to the geothermal gradient. This vapor can then recondense nearer to the surface where ice had previously sublimed and been lost to the atmosphere. As a result we find that ice deposits migrate to find a steady-state depth, which represents a balance between diffusive loss to the atmosphere through the overlying porous regolith and diffusive resupply through a porous icy regolith below. This depth depends primarily on the long-term mean surface temperature and the nature of the geothermal gradient, and is independent of the ice-free porosity and the regolith diffusivity. Only the rate of loss of ground ice depends on diffusive properties.

  2. Substrate ground state binding energy concentration is realized as transition state stabilization in physiological enzyme catalysis.

    PubMed

    Britt, Billy Mark

    2004-09-30

    Previously published kinetic data on the interactions of seventeen different enzymes with their physiological substrates are re-examined in order to understand the connection between ground state binding energy and transition state stabilization of the enzyme-catalyzed reactions. When the substrate ground state binding energies are normalized by the substrate molar volumes, binding of the substrate to the enzyme active site may be thought of as an energy concentration interaction; that is, binding of the substrate ground state brings in a certain concentration of energy. When kinetic data of the enzyme/substrate interactions are analyzed from this point of view, the following relationships are discovered: 1) smaller substrates possess more binding energy concentrations than do larger substrates with the effect dropping off exponentially, 2) larger enzymes (relative to substrate size) bind both the ground and transition states more tightly than smaller enzymes, and 3) high substrate ground state binding energy concentration is associated with greater reaction transition state stabilization. It is proposed that these observations are inconsistent with the conventional (Haldane) view of enzyme catalysis and are better reconciled with the shifting specificity model for enzyme catalysis.

  3. Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

    PubMed

    Yura, Harold T; Fields, Renny A

    2011-06-20

    Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

  4. Basicity of coumarin derivatives in the ground and excited states

    SciTech Connect

    Ponomarev, O.A.; Mitina, V.G.; Vasina, E.R.; Yarmolenko, S.N.

    1985-07-01

    The acid-base properties of coumarin luminophores are widely used for widening the optical spectrum generated by lasers. The aim of this work was a quantitative study of the proton-acceptor capacity of a series of substituted coumarins at the H-complex formation stage and during protonation, and also to evaluate the basicity of these compounds in the first excited singlet state. The compounds chosen were the 4- and 7-substituted coumarins, most widely used in laser technology. In the ground state the sensitivity of the carbonyl group to the effect of a substituent was twice as great in position 4 as in position 7; for the excited state the effect was reversed.

  5. Calculation of electron scattering from the ground state of ytterbium

    SciTech Connect

    Bostock, Christopher J.; Fursa, Dmitry V.; Bray, Igor

    2011-05-15

    We report on the application of the convergent close-coupling method, in both relativistic and nonrelativistic formulations, to electron scattering from ytterbium. Angle-differential and integrated cross sections are presented for elastic scattering and excitation of the states (6s6p){sup 3}P{sub 0,1,2}, (6s6p){sup 1}P{sub 1}{sup o}, (6s7p){sup 1}P{sub 1}{sup o}, and (6s5d){sup 1}D{sub 2}{sup e} for a range of incident electron energies. We also present calculations of the total cross section, and angle-differential Stokes parameters for excitation of the (6s6p){sup 3}P{sub 1}{sup o} state from the ground state. A comparison is made with the relativistic distorted-wave method and experiments.

  6. Ground state of the universe in quantum cosmology

    NASA Astrophysics Data System (ADS)

    Gorobey, Natalia; Lukyanenko, Alexander

    2016-01-01

    We find a physical state of a closed universe with the minimal excitation of the universe expansion energy in quantum gravity. It is an analog of the vacuum state of the ordinary quantum field theory in the Minkowsky space, but in our approach an energy of space of a closed universe together with the energy of its matter content are minimized. This ground state is chosen among an enlarged set of physical states, compared with the ordinary covariant quantum gravity. In our approach, physical states are determined by weak constraints: quantum mechanical averages of gravitational constraint operators equal zero. As a result, they appear to be non-static in such a modification of quantum gravity. Quantum dynamics of the universe is described by Schrödinger equation with a cosmic time determined by weak gravitational constraints. In order to obtain the observed megascopic universe with the inflation stage just after its quantum beginning, a lot of the energy in the form of the inflaton scalar field condensate is prescribed to the initial state. Parameters of the initial state for a homogeneous model of the universe are calculated.

  7. Population shuffling between ground and high energy excited states.

    PubMed

    Sabo, T Michael; Trent, John O; Lee, Donghan

    2015-11-01

    Stochastic processes powered by thermal energy lead to protein motions traversing time-scales from picoseconds to seconds. Fundamental to protein functionality is the utilization of these dynamics for tasks such as catalysis, folding, and allostery. A hierarchy of motion is hypothesized to connect and synergize fast and slow dynamics toward performing these essential activities. Population shuffling predicts a "top-down" temporal hierarchy, where slow time-scale conformational interconversion leads to a shuffling of the free energy landscape for fast time-scale events. Until now, population shuffling was only applied to interconverting ground states. Here, we extend the framework of population shuffling to be applicable for a system interconverting between low energy ground and high energy excited states, such as the SH3 domain mutants G48M and A39V/N53P/V55L from the Fyn tyrosine kinase, providing another tool for accessing the structural dynamics of high energy excited states. Our results indicate that the higher energy gauche - rotameric state for the leucine χ2 dihedral angle contributes significantly to the distribution of rotameric states in both the major and minor forms of the SH3 domain. These findings are corroborated with unrestrained molecular dynamics (MD) simulations on both the major and minor states of the SH3 domain demonstrating high correlations between experimental and back-calculated leucine χ2 rotameric populations. Taken together, we demonstrate how fast time-scale rotameric side-chain population distributions can be extracted from slow time-scale conformational exchange data further extending the scope and the applicability of the population shuffling model.

  8. Population shuffling between ground and high energy excited states

    PubMed Central

    Sabo, T Michael; Trent, John O; Lee, Donghan

    2015-01-01

    Stochastic processes powered by thermal energy lead to protein motions traversing time-scales from picoseconds to seconds. Fundamental to protein functionality is the utilization of these dynamics for tasks such as catalysis, folding, and allostery. A hierarchy of motion is hypothesized to connect and synergize fast and slow dynamics toward performing these essential activities. Population shuffling predicts a “top-down” temporal hierarchy, where slow time-scale conformational interconversion leads to a shuffling of the free energy landscape for fast time-scale events. Until now, population shuffling was only applied to interconverting ground states. Here, we extend the framework of population shuffling to be applicable for a system interconverting between low energy ground and high energy excited states, such as the SH3 domain mutants G48M and A39V/N53P/V55L from the Fyn tyrosine kinase, providing another tool for accessing the structural dynamics of high energy excited states. Our results indicate that the higher energy gauche− rotameric state for the leucine χ2 dihedral angle contributes significantly to the distribution of rotameric states in both the major and minor forms of the SH3 domain. These findings are corroborated with unrestrained molecular dynamics (MD) simulations on both the major and minor states of the SH3 domain demonstrating high correlations between experimental and back-calculated leucine χ2 rotameric populations. Taken together, we demonstrate how fast time-scale rotameric side-chain population distributions can be extracted from slow time-scale conformational exchange data further extending the scope and the applicability of the population shuffling model. PMID:26316263

  9. Ground state energies from converging and diverging power series expansions

    SciTech Connect

    Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E. Su, Q.; Grobe, R.

    2016-10-15

    It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh–Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state’s spatial extension is comparable to L. Once the binding strength is so strong that the ground state’s extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

  10. Spatial competition of the ground states in 1111 iron pnictides

    NASA Astrophysics Data System (ADS)

    Lang, G.; Veyrat, L.; Gräfe, U.; Hammerath, F.; Paar, D.; Behr, G.; Wurmehl, S.; Grafe, H.-J.

    2016-07-01

    Using nuclear quadrupole resonance, the phase diagram of 1111 R FeAsO1 -xFx (R =La , Ce, Sm) iron pnictides is constructed as a function of the local charge distribution in the paramagnetic state, which features low-doping-like (LD-like) and high-doping-like (HD-like) regions. Compounds based on magnetic rare earths (Ce, Sm) display a unified behavior, and comparison with La-based compounds reveals the detrimental role of static iron 3 d magnetism on superconductivity, as well as a qualitatively different evolution of the latter at high doping. It is found that the LD-like regions fully account for the orthorhombicity of the system, and are thus the origin of any static iron magnetism. Orthorhombicity and static magnetism are not hindered by superconductivity but limited by dilution effects, in agreement with two-dimensional (2D) (respectively three-dimensional) nearest-neighbor square lattice site percolation when the rare earth is nonmagnetic (respectively magnetic). The LD-like regions are not intrinsically supportive of superconductivity, contrary to the HD-like regions, as evidenced by the well-defined Uemura relation between the superconducting transition temperature and the superfluid density when accounting for the proximity effect. This leads us to propose a complete description of the interplay of ground states in 1111 pnictides, where nanoscopic regions compete to establish the ground state through suppression of superconductivity by static magnetism, and extension of superconductivity by proximity effect.

  11. Ground state of a resonantly interacting Bose gas

    SciTech Connect

    Diederix, J. M.; Heijst, T. C. F. van; Stoof, H. T. C.

    2011-09-15

    We show that a two-channel mean-field theory for a Bose gas near a Feshbach resonance allows for an analytic computation of the chemical potential, and therefore the universal constant {beta}, at unitarity. To improve on this mean-field theory, which physically neglects condensate depletion, we study a variational Jastrow ansatz for the ground-state wave function and use the hypernetted-chain approximation to minimize the energy for all positive values of the scattering length. We also show that other important physical quantities such as Tan's contact and the condensate fraction can be directly obtained from this approach.

  12. Tetraphenylhexaazaanthracenes: 16π Weakly Antiaromatic Species with Singlet Ground States.

    PubMed

    Constantinides, Christos P; Zissimou, Georgia A; Berezin, Andrey A; Ioannou, Theodosia A; Manoli, Maria; Tsokkou, Demetra; Theodorou, Eleni; Hayes, Sophia C; Koutentis, Panayiotis A

    2015-08-21

    Tetraphenylhexaazaanthracene, TPHA-1, is a fluorescent zwitterionic biscyanine with a closed-shell singlet ground state. TPHA-1 overcomes its weak 16π antiaromaticity by partitioning its π system into 6π positive and 10π negative cyanines. The synthesis of TPHA-1 is low yielding and accompanied by two analogous TPHA isomers: the deep red, non-charge-separated, quinoidal TPHA-2, and the deep green TPHA-3 that partitions into two equal but oppositely charged 8π cyanines. The three TPHA isomers are compared.

  13. Photoabsorption by ground-state alkali-metal atoms.

    NASA Technical Reports Server (NTRS)

    Weisheit, J. C.

    1972-01-01

    Principal-series oscillator strengths and ground-state photoionization cross sections are computed for sodium, potassium, rubidium, and cesium. The degree of polarization of the photoelectrons is also predicted for each atom. The core-polarization correction to the dipole transition moment is included in all of the calculations, and the spin-orbit perturbation of valence-p-electron orbitals is included in the calculations of the Rb and Cs oscillator strengths and of all the photoionization cross sections. The results are compared with recent measurements.

  14. Lee-Yang Polynomials and Ground States of Spin Systems

    NASA Astrophysics Data System (ADS)

    Slawny, Joseph

    2014-08-01

    We obtain two kinds of results on the region in the space of the interactions of lattice systems where the Lee-Yang property holds (LY domain). First we show that the LY domain is related to interactions with exactly two ground states. Then we give a description of the full LY domain of an extended "plaquette model" analyzed by Lebowitz and Ruelle (Commun Math Phys 304:711-722, 2011). This allows us to prove a permanence property of the system, which we conjecture to hold in general.

  15. Ground- and excited-state impurity bands in quantum wells

    NASA Astrophysics Data System (ADS)

    Ghazali, A.; Gold, A.; Serre, J.

    1989-02-01

    The density of states and the spectral density of electrons in quantum wells with charged impurities are calculated with use of a multiple-scattering method. The impurity-density-dependent broadening and the gradual merging of the ground (1s) and excited (2p+/-,2s) impurity levels into impurity bands are investigated. At low density the shapes of the 1s, 2p+/-, and 2s spectral densities are found to be in excellent agreement with the analytical results obtained for the ideal two-dimensional Coulomb problem.

  16. Computational schemes for the ground-state pair density.

    PubMed

    Higuchi, K; Higuchi, M

    2009-02-11

    We reconfirm the performance of the initial scheme for calculating the ground-state pair density (Higuchi and Higuchi 2007 Physica B 387 117, 2008 Phys. Rev. B 78 125101) by using the alternative approximation of the correlating kinetic energy functional. It is shown that about 20% of the correlation energy can be reproduced by the initial scheme, irrespective of the approximate form of the correlating kinetic energy functional. On the basis of the initial scheme, various kinds of schemes that go beyond the initial one can be developed. We illustrate two kinds of computational schemes.

  17. Quark-model identification of baryon ground and resonant states

    SciTech Connect

    Melde, T.; Plessas, W.; Sengl, B.

    2008-06-01

    We present a new classification scheme of baryon ground states and resonances into SU(3) flavor multiplets. The scheme is worked out along a covariant formalism with relativistic constituent quark models and it relies on detailed investigations of the baryon spectra, the spin-flavor structure of the baryon eigenstates, the behavior of their probability density distributions as well as covariant predictions for mesonic decay widths. The results are found to be quite independent of the specific types of relativistic constituent quark models employed. It turns out that a consistent classification requires one to include also resonances that are presently reported from experiments with only two-star status.

  18. The ground state of the Frenkel-Kontorova model

    NASA Astrophysics Data System (ADS)

    Babushkin, A. Yu.; Abkaryan, A. K.; Dobronets, B. S.; Krasikov, V. S.; Filonov, A. N.

    2016-09-01

    The continual approximation of the ground state of the discrete Frenkel-Kontorova model is tested using a symmetric algorithm of numerical simulation. A "kaleidoscope effect" is found, which means that the curves representing the dependences of the relative extension of an N-atom chain vary periodically with increasing N. Stairs of structural transitions for N ≫ 1 are analyzed by the channel selection method with the approximation N = ∞. Images of commensurable and incommensurable structures are constructed. The commensurable-incommensurable phase transitions are stepwise.

  19. Compilation of directly measured nuclear spins of ground states and long-lived isomers

    SciTech Connect

    MacDonald, Allison; Karamy, Babak; Setoodehnia, Kiana; Singh, Balraj

    2013-02-15

    A compilation of the nuclear spins of ground and isomeric states measured by direct methods is presented. The first compilation of direct measurements of nuclear spins and moments was published in 1976 (G. H. Fuller, J. Phys. Chem. Ref. Data 5, 835, (1976)) with literature covered up to 1974. To our knowledge, the present work is the first such compilation since then. It is anticipated that the area of direct spin measurement will continue to expand using the state-of-the-art radioactive ion-beam and laser techniques. Literature cutoff date for the present compilation is February 2013. It is intended that the present compilation will be kept updated in a timely manner.

  20. Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole.

    PubMed

    Wilke, Josefin; Wilke, Martin; Meerts, W Leo; Schmitt, Michael

    2016-01-28

    The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54(∘) showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.

  1. Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole

    SciTech Connect

    Wilke, Josefin; Wilke, Martin; Schmitt, Michael; Meerts, W. Leo

    2016-01-28

    The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.

  2. Universal crossover from ground-state to excited-state quantum criticality

    NASA Astrophysics Data System (ADS)

    Kang, Byungmin; Potter, Andrew C.; Vasseur, Romain

    2017-01-01

    We study the nonequilibrium properties of a nonergodic random quantum chain in which highly excited eigenstates exhibit critical properties usually associated with quantum critical ground states. The ground state and excited states of this system belong to different universality classes, characterized by infinite-randomness quantum critical behavior. Using strong-disorder renormalization group techniques, we show that the crossover between the zero and finite energy density regimes is universal. We analytically derive a flow equation describing the unitary dynamics of this isolated system at finite energy density from which we obtain universal scaling functions along the crossover.

  3. Magnetic ground states in nanocuboids of cubic magnetocrystalline anisotropy

    NASA Astrophysics Data System (ADS)

    Bonilla, F. J.; Lacroix, L.-M.; Blon, T.

    2017-04-01

    Flower and easy-axis vortex states are well-known magnetic configurations that can be stabilized in small particles. However, <111> vortex (V<111>), i.e. a vortex state with its core axis along the hard-axis direction, has been recently evidenced as a stable configuration in Fe nanocubes of intermediate sizes in the flower/vortex transition. In this context, we present here extensive micromagnetic simulations to determine the different magnetic ground states in ferromagnetic nanocuboids exhibiting cubic magnetocrystalline anisotropy (MCA). Focusing our study in the single-domain/multidomain size range (10-50 nm), we showed that V<111> is only stable in nanocuboids exhibiting peculiar features, such as a specific size, shape and magnetic environment, contrarily to the classical flower and easy-axis vortex states. Thus, to track experimentally these V<111> states, one should focused on (i) nanocuboids exhibiting a nearly perfect cubic shape (size distorsion <12%) made of (ii) a material which combines a zero or positive MCA and a high saturation magnetization, such as Fe or FeCo; and (iii) a low magnetic field environment, V<111> being only observed in virgin or remanent states.

  4. Charge transfer to ground-state ions produces free electrons

    NASA Astrophysics Data System (ADS)

    You, D.; Fukuzawa, H.; Sakakibara, Y.; Takanashi, T.; Ito, Y.; Maliyar, G. G.; Motomura, K.; Nagaya, K.; Nishiyama, T.; Asa, K.; Sato, Y.; Saito, N.; Oura, M.; Schöffler, M.; Kastirke, G.; Hergenhahn, U.; Stumpf, V.; Gokhberg, K.; Kuleff, A. I.; Cederbaum, L. S.; Ueda, K.

    2017-01-01

    Inner-shell ionization of an isolated atom typically leads to Auger decay. In an environment, for example, a liquid or a van der Waals bonded system, this process will be modified, and becomes part of a complex cascade of relaxation steps. Understanding these steps is important, as they determine the production of slow electrons and singly charged radicals, the most abundant products in radiation chemistry. In this communication, we present experimental evidence for a so-far unobserved, but potentially very important step in such relaxation cascades: Multiply charged ionic states after Auger decay may partially be neutralized by electron transfer, simultaneously evoking the creation of a low-energy free electron (electron transfer-mediated decay). This process is effective even after Auger decay into the dicationic ground state. In our experiment, we observe the decay of Ne2+ produced after Ne 1s photoionization in Ne-Kr mixed clusters.

  5. Ground states of partially connected binary neural networks

    NASA Technical Reports Server (NTRS)

    Baram, Yoram

    1990-01-01

    Neural networks defined by outer products of vectors over (-1, 0, 1) are considered. Patterns over (-1, 0, 1) define by their outer products partially connected neural networks consisting of internally strongly connected, externally weakly connected subnetworks. Subpatterns over (-1, 1) define subnetworks, and their combinations that agree in the common bits define permissible words. It is shown that the permissible words are locally stable states of the network, provided that each of the subnetworks stores mutually orthogonal subwords, or, at most, two subwords. It is also shown that when each of the subnetworks stores two mutually orthogonal binary subwords at most, the permissible words, defined as the combinations of the subwords (one corresponding to each subnetwork), that agree in their common bits are the unique ground states of the associated energy function.

  6. Centrifugal stretching along the ground state band of Hf168

    NASA Astrophysics Data System (ADS)

    Costin, A.; Reese, M.; Ai, H.; Casten, R. F.; Dusling, K.; Fitzpatrick, C. R.; Gürdal, G.; Heinz, A.; McCutchan, E. A.; Meyer, D. A.; Möller, O.; Petkov, P.; Pietralla, N.; Qian, J.; Rainovski, G.; Werner, V.

    2009-02-01

    The lifetimes of the Jπ=4+, 6+, 8+, and 10+ levels along the ground state band in Hf168 were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in Hf168 were populated using the Sn124(Ti48,4n) fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus Hf168. The data agree with the predictions from the geometrical confined β-soft (CBS) rotor model that involves centrifugal stretching in a soft potential.

  7. Cloning and variation of ground state intestinal stem cells.

    PubMed

    Wang, Xia; Yamamoto, Yusuke; Wilson, Lane H; Zhang, Ting; Howitt, Brooke E; Farrow, Melissa A; Kern, Florian; Ning, Gang; Hong, Yue; Khor, Chiea Chuen; Chevalier, Benoit; Bertrand, Denis; Wu, Lingyan; Nagarajan, Niranjan; Sylvester, Francisco A; Hyams, Jeffrey S; Devers, Thomas; Bronson, Roderick; Lacy, D Borden; Ho, Khek Yu; Crum, Christopher P; McKeon, Frank; Xian, Wa

    2015-06-11

    Stem cells of the gastrointestinal tract, pancreas, liver and other columnar epithelia collectively resist cloning in their elemental states. Here we demonstrate the cloning and propagation of highly clonogenic, 'ground state' stem cells of the human intestine and colon. We show that derived stem-cell pedigrees sustain limited copy number and sequence variation despite extensive serial passaging and display exquisitely precise, cell-autonomous commitment to epithelial differentiation consistent with their origins along the intestinal tract. This developmentally patterned and epigenetically maintained commitment of stem cells is likely to enforce the functional specificity of the adult intestinal tract. Using clonally derived colonic epithelia, we show that toxins A or B of the enteric pathogen Clostridium difficile recapitulate the salient features of pseudomembranous colitis. The stability of the epigenetic commitment programs of these stem cells, coupled with their unlimited replicative expansion and maintained clonogenicity, suggests certain advantages for their use in disease modelling and regenerative medicine.

  8. Charge transfer to ground-state ions produces free electrons

    PubMed Central

    You, D.; Fukuzawa, H.; Sakakibara, Y.; Takanashi, T.; Ito, Y.; Maliyar, G. G.; Motomura, K.; Nagaya, K.; Nishiyama, T.; Asa, K.; Sato, Y.; Saito, N.; Oura, M.; Schöffler, M.; Kastirke, G.; Hergenhahn, U.; Stumpf, V.; Gokhberg, K.; Kuleff, A. I.; Cederbaum, L. S.; Ueda, K

    2017-01-01

    Inner-shell ionization of an isolated atom typically leads to Auger decay. In an environment, for example, a liquid or a van der Waals bonded system, this process will be modified, and becomes part of a complex cascade of relaxation steps. Understanding these steps is important, as they determine the production of slow electrons and singly charged radicals, the most abundant products in radiation chemistry. In this communication, we present experimental evidence for a so-far unobserved, but potentially very important step in such relaxation cascades: Multiply charged ionic states after Auger decay may partially be neutralized by electron transfer, simultaneously evoking the creation of a low-energy free electron (electron transfer-mediated decay). This process is effective even after Auger decay into the dicationic ground state. In our experiment, we observe the decay of Ne2+ produced after Ne 1s photoionization in Ne–Kr mixed clusters. PMID:28134238

  9. Magnetic ground state of semiconducting transition-metal trichalcogenide monolayers

    SciTech Connect

    Sivadas, Nikhil; Daniels, Matthew W.; Swendsen, Robert H.; Okamoto, Satoshi; Xiao, Di

    2015-06-16

    Layered transition-metal trichalcogenides with the chemical formula ABX3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides.We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperature of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic N eel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. In conclusion, our study suggests that ABX3 can be a promising platform to explore two-dimensional magnetic phenomena.

  10. Magnetic ground state of semiconducting transition-metal trichalcogenide monolayers

    DOE PAGES

    Sivadas, Nikhil; Daniels, Matthew W.; Swendsen, Robert H.; ...

    2015-06-16

    Layered transition-metal trichalcogenides with the chemical formula ABX3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides.We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperaturemore » of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic N eel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. In conclusion, our study suggests that ABX3 can be a promising platform to explore two-dimensional magnetic phenomena.« less

  11. Nuclear Magnetic Moment of the {sup 57}Cu Ground State

    SciTech Connect

    Minamisono, K.; Mertzimekis, T.J.; Pereira, J.; Mantica, P.F.; Pinter, J.S.; Stoker, J.B.; Tomlin, B.E.; Weerasiri, R.R.; Davies, A.D.; Hass, M.; Rogers, W.F.

    2006-03-17

    The nuclear magnetic moment of the ground state of {sup 57}Cu(I{sup {pi}}=3/2{sup -},T{sub 1/2}=196.3 ms) has been measured to be vertical bar {mu}({sup 57}Cu) vertical bar =(2.00{+-}0.05){mu}{sub N} using the {beta}-NMR technique. Together with the known magnetic moment of the mirror partner {sup 57}Ni, the spin expectation value was extracted as <{sigma}{sigma}{sub z}>=-0.78{+-}0.13. This is the heaviest isospin T=1/2 mirror pair above the {sup 40}Ca region for which both ground state magnetic moments have been determined. The discrepancy between the present results and shell-model calculations in the full fp shell giving {mu}({sup 57}Cu){approx}2.4{mu}{sub N} and <{sigma}{sigma}{sub z}>{approx}0.5 implies significant shell breaking at {sup 56}Ni with the neutron number N=28.

  12. DNA-DNA interaction beyond the ground state

    NASA Astrophysics Data System (ADS)

    Lee, D. J.; Wynveen, A.; Kornyshev, A. A.

    2004-11-01

    The electrostatic interaction potential between DNA duplexes in solution is a basis for the statistical mechanics of columnar DNA assemblies. It may also play an important role in recombination of homologous genes. We develop a theory of this interaction that includes thermal torsional fluctuations of DNA using field-theoretical methods and Monte Carlo simulations. The theory extends and rationalizes the earlier suggested variational approach which was developed in the context of a ground state theory of interaction of nonhomologous duplexes. It shows that the heuristic variational theory is equivalent to the Hartree self-consistent field approximation. By comparison of the Hartree approximation with an exact solution based on the QM analogy of path integrals, as well as Monte Carlo simulations, we show that this easily analytically-tractable approximation works very well in most cases. Thermal fluctuations do not remove the ability of DNA molecules to attract each other at favorable azimuthal conformations, neither do they wash out the possibility of electrostatic “snap-shot” recognition of homologous sequences, considered earlier on the basis of ground state calculations. At short distances DNA molecules undergo a “torsional alignment transition,” which is first order for nonhomologous DNA and weaker order for homologous sequences.

  13. On the nature of the oligoacene ground state

    NASA Astrophysics Data System (ADS)

    Hachmann, Johannes; Dorando, Jonathan; Aviles, Michael; Kin-Lic Chan, Garnet

    2007-03-01

    The nature of the oligoacene ground state - its spin, singlet-triplet gap, and diradical character as a function of chain-length - is a question of ongoing theoretical and experimental interest with notable technological implications. Previous computational studies have given inconclusive answers to this challenging electronic structure problem (see e.g. [1]). In the present study we exploit the capabilities of the local ab initio Density Matrix Renormalization Group (DMRG) [2], which allows the numerically exact (FCI) solution of the Schr"odinger equation in a chosen 1-particle basis and active space for quasi-one-dimensional systems. We compute the singlet-triplet gap from first principles as a function of system length ranging from naphthalene to tetradecacene, correlating the full π-space (i.e. up to 58 electrons in 58 orbitals) and converging the results to a few μEh accuracy [3]. In order to study the diradical nature of the oligoacene ground state we calculate expectation values over different diradical occupation and pair-correlation operators. Furthermore we study the natural orbitals and their occupation. [1] Bendikov, Duong, Starkey, Houk, Carter, Wudl, JACS 126 (2004), 7416. [2] Hachmann, Cardoen, Chan, JCP 125 (2006), 144101. [3] Hachmann, Dorando, Avil'es, Chan, in preparation.

  14. Magnetic ground state of semiconducting transition-metal trichalcogenide monolayers

    NASA Astrophysics Data System (ADS)

    Sivadas, Nikhil; Daniels, Matthew W.; Swendsen, Robert H.; Okamoto, Satoshi; Xiao, Di

    2015-06-01

    Layered transition-metal trichalcogenides with the chemical formula A B X3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides. We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperature of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic Néel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. Our study suggests that A B X3 can be a promising platform to explore two-dimensional magnetic phenomena.

  15. The valence-fluctuating ground state of plutonium

    DOE PAGES

    Janoschek, Marc; Das, Pinaki; Chakrabarti, Bismayan; ...

    2015-07-10

    A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. In addition, our study reveals that the ground state of plutonium is governed bymore » valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.« less

  16. DNA-DNA interaction beyond the ground state.

    PubMed

    Lee, D J; Wynveen, A; Kornyshev, A A

    2004-11-01

    The electrostatic interaction potential between DNA duplexes in solution is a basis for the statistical mechanics of columnar DNA assemblies. It may also play an important role in recombination of homologous genes. We develop a theory of this interaction that includes thermal torsional fluctuations of DNA using field-theoretical methods and Monte Carlo simulations. The theory extends and rationalizes the earlier suggested variational approach which was developed in the context of a ground state theory of interaction of nonhomologous duplexes. It shows that the heuristic variational theory is equivalent to the Hartree self-consistent field approximation. By comparison of the Hartree approximation with an exact solution based on the QM analogy of path integrals, as well as Monte Carlo simulations, we show that this easily analytically-tractable approximation works very well in most cases. Thermal fluctuations do not remove the ability of DNA molecules to attract each other at favorable azimuthal conformations, neither do they wash out the possibility of electrostatic "snap-shot" recognition of homologous sequences, considered earlier on the basis of ground state calculations. At short distances DNA molecules undergo a "torsional alignment transition," which is first order for nonhomologous DNA and weaker order for homologous sequences.

  17. Au42: A possible ground-state noble metallic nanotube

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Ning, Hua; Ma, Qing-Min; Liu, Ying; Li, You-Cheng

    2008-10-01

    A large hollow tubelike Au42 is predicted as a new ground-state configuration based on the scalar relativistic density functional theory. The shape of this new Au42 cluster is similar to a (5,5) single-wall gold nanotube, the two ends of which are capped by half of a fullerenelike Au32. In the same way, a series of Aun (n =37,42,47,52,57,62,67,72,…, Δn =5) tubelike structures has been constructed. The highest occupied molecular orbital-lowest unoccupied molecular orbital gaps suggested a significant semiconductor-conductor alternation in n ɛ[32,47]. Similar to the predictions and speculation of Daedalus [D. E. H. Jones, New Sci. 32, 245 (1966); E. Osawa, Superaromaticity (Kagaku, Kyoto, 1970), Vol. 25, pp. 854-863; Z. Yoshida and E. Osawa, Aromaticity Chemical Monograph (Kagaku Dojin, Kyoto, Japan, 1971), Vol. 22, pp. 174-176; D. A. Bochvar and E. G. Gal'pern, Dokl. Akad. Nauk SSSR 209, 610 (1973)], here a large hollow ground-state gold nanotube was predicted theoretically.

  18. Au42: a possible ground-state noble metallic nanotube.

    PubMed

    Wang, Jing; Ning, Hua; Ma, Qing-Min; Liu, Ying; Li, You-Cheng

    2008-10-07

    A large hollow tubelike Au(42) is predicted as a new ground-state configuration based on the scalar relativistic density functional theory. The shape of this new Au(42) cluster is similar to a (5,5) single-wall gold nanotube, the two ends of which are capped by half of a fullerenelike Au(32). In the same way, a series of Au(n) (n = 37, 42, 47, 52, 57, 62, 67, 72, ..., Delta n = 5) tubelike structures has been constructed. The highest occupied molecular orbital-lowest unoccupied molecular orbital gaps suggested a significant semiconductor-conductor alternation in n is an element of [32,47]. Similar to the predictions and speculation of Daedalus [D. E. H. Jones, New Sci. 32, 245 (1966); E. Osawa, Superaromaticity (Kagaku, Kyoto, 1970), Vol. 25, pp. 854-863; Z. Yoshida and E. Osawa, Aromaticity Chemical Monograph (Kagaku Dojin, Kyoto, Japan, 1971), Vol. 22, pp. 174-176; D. A. Bochvar and E. G. Gal'pern, Dokl. Akad. Nauk SSSR 209, 610 (1973)], here a large hollow ground-state gold nanotube was predicted theoretically.

  19. Measurements of the ground-state polarizabilities of Cs, Rb, and K using atom interferometry

    NASA Astrophysics Data System (ADS)

    Gregoire, Maxwell D.; Hromada, Ivan; Holmgren, William F.; Trubko, Raisa; Cronin, Alexander D.

    2015-11-01

    We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms using a three-nanograting Mach-Zehnder atom beam interferometer. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity-nonconservation experiments. We measured αCs=4 π ɛ0×59.39 (9 ) Å3,αRb=4 π ɛ0×47.39 (8 ) Å3 , and αK=4 π ɛ0×42.93 (7 ) Å3 . In atomic units, these measurements are αCs=401.2 (7 ) ,αRb=320.1 (6 ) , and αK=290.0 (5 ) . We report ratios of polarizabilities αCs/αRb=1.2532 (10 ) ,αCs/αK=1.3834 (9 ) , and αRb/αK=1.1040 (9 ) with smaller fractional uncertainty because the systematic errors for individual measurements are largely correlated. Since Cs atom beams have short de Broglie wavelengths, we developed measurement methods that do not require resolved atom diffraction. Specifically, we used phase choppers to measure atomic beam velocity distributions, and we used electric field gradients to give the atom interference pattern a phase shift that depends on atomic polarizability.

  20. Interactions Between Ground-State Nitrogen Atoms and Molecules

    NASA Technical Reports Server (NTRS)

    Vanderslice, Joseph T.; Mason, Edward A.; Lippincott, Ellis R.

    1959-01-01

    Potential-energy curves for nitrogen atom (N-N) interactions corresponding to the X (1)Sigma(sup +, sub g), A (3)Sigma(sup +, sub u), (5)Sigma(sup +, sub g), (7)Sigma(sup +, sub u), B (3) Pi(sub g), C (3)(Pi(su u)and a (1)Pi(sub g) states of the nitrogen molecule N2 as well as curves for the atom-molecules (N-N2) and molecule-molecule (N2-N2) interactions have been calculated. All calculations have been based as nearly as possible on experimental data, including spectroscopically determined vibrational energy levels, scattering cross sections of atomic beams in gases, and measured vibrational relaxation times. In cases where experimental data were not available, approximate quantum-mechanical calculations have been made. Results obtained by these various methods are remarkably consistent with one another and are believed to have good accuracy.

  1. Studies on the ground state entropy of the Potts antiferromagnet

    NASA Astrophysics Data System (ADS)

    Tsai, Shan-Ho

    This dissertation reports recent results on the ground state degeneracy of the q-state antiferromagnetic Potts model. This model has a deep connection with graph theory in mathematics since the zero-temperature partition function of this model on a given lattice, or more generally on a graph G, is equal to the chromatic polynomial P(G, q), which expresses the number of ways of coloring the n vertices of a graph G using at most q colors such that no two adjacent vertices have the same color. The ground state degeneracy per site of the Potts antiferromagnet is given by W(\\{ G\\}, q) = limsb{n->infty}P(G, q)sp{1/n} (where \\{ G\\} denotes the limit as n-> infty of the family of n-vertex graphs of type G). Exact solutions for this problem are known in only very few special cases. We have obtained rigorous upper and lower bounds, large-q series expansions and Monte Carlo measurements of the ground state degeneracy W(Lambda,\\ q) of the antiferromagnetic Potts model on a number of two dimensional lattices. These bounds are shown to be very restrictive. In particular, the lower bounds coincide with many terms of the respective large-q series expansion and are very good approximations to the exact functions. Although q is an integer parameter in the definition of the initial model, it is instructive to generalize it to complex variable. We study the analytic structure of the function W(\\{ G\\}, q) in the complex q plane. We determine the exact locus {cal B} where W(\\{G\\}, q) is nonanalytic for a number of families of graphs G. We calculate chromatic polynomials on strip graphs of varying widths as a way of obtaining information on the two dimensional limit. For this purpose, we construct generating functions, which provide both the asymptotic limiting function W(\\{ G\\}, q) as well as chromatic polynomials for finite length strips. Exact calculation is presented for a number of families of strip graphs. Effects of different types of boundary conditions are examined

  2. Ground-State Proton Transfer Kinetics in Green Fluorescent Protein

    PubMed Central

    2015-01-01

    Proton transfer plays an important role in the optical properties of green fluorescent protein (GFP). While much is known about excited-state proton transfer reactions (ESPT) in GFP occurring on ultrafast time scales, comparatively little is understood about the factors governing the rates and pathways of ground-state proton transfer. We have utilized a specific isotopic labeling strategy in combination with one-dimensional 13C nuclear magnetic resonance (NMR) spectroscopy to install and monitor a 13C directly adjacent to the GFP chromophore ionization site. The chemical shift of this probe is highly sensitive to the protonation state of the chromophore, and the resulting spectra reflect the thermodynamics and kinetics of the proton transfer in the NMR line shapes. This information is complemented by time-resolved NMR, fluorescence correlation spectroscopy, and steady-state absorbance and fluorescence measurements to provide a picture of chromophore ionization reactions spanning a wide time domain. Our findings indicate that proton transfer in GFP is described well by a two-site model in which the chromophore is energetically coupled to a secondary site, likely the terminal proton acceptor of ESPT, Glu222. Additionally, experiments on a selection of GFP circular permutants suggest an important role played by the structural dynamics of the seventh β-strand in gating proton transfer from bulk solution to the buried chromophore. PMID:25184668

  3. Ground-state valency and spin configuration of the nickelates.

    NASA Astrophysics Data System (ADS)

    Petit, Leon; Stocks, George M.; Egami, Takeshi; Szotek, Zdzislawa; Temmerman, Walter M.

    2006-03-01

    The ab initio self-interaction-corrected local-spin-density approximation is used to study the electronic structure of both stoichiometric and non-stoichiometric nickelates. From total energy considerations it emerges that, in their ground-state, both LiNiO2, and NaNiO2 are insulators, with the Ni ion in the Ni^3+ low spin state (t2g^6eg^1) configuration. We find that the substitution of Li/Na atoms by divalent impurities, drives an equivalent number of Ni ions in the NiO2 layers from the JT-active trivalent low-spin state to the divalent JT-inactive state. We propose that an experimental study on MgxNa1-xNiO2 might clarify the role of Ni^2+ impurities with respect to the vanishing of long range orbital ordering in Li1-xNi1+xO2. (Work sponsored by the Laboratory Directed Research and Development Program (LDRD) program of ORNL (LP, GMS, TE), and by the DOE-OS through the Offices of Basic Energy Sciences (BES), Division of Materials Sciences and Engineering (LP, GMS, TE). Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the Department of Energy under Contract No. DE-AC05-00OR22725.)

  4. Intruder configurations in the ground state of 30Ne

    NASA Astrophysics Data System (ADS)

    Liu, H. N.; Lee, J.; Doornenbal, P.; Scheit, H.; Takeuchi, S.; Aoi, N.; Li, K. A.; Matsushita, M.; Steppenbeck, D.; Wang, H.; Baba, H.; Ideguchi, E.; Kobayashi, N.; Kondo, Y.; Lee, G.; Michimasa, S.; Motobayashi, T.; Poves, A.; Sakurai, H.; Takechi, M.; Togano, Y.; Tostevin, J. A.; Utsuno, Y.

    2017-04-01

    We report on the first detailed study of intruder configurations in the ground state of 30Ne by means of the 12C(30Ne, 29Ne+γ)X one-neutron knockout reaction at 228 MeV/nucleon. Using a combined analysis of individual parallel momentum distributions and partial cross sections we find: (a) comparable p- and d-wave removal strength to 29Ne final states with excitation energies below 200 keV, and (b) significant p-wave removal strength to the 620 keV state of 29Ne, and (c) no evidence for f-wave intruder strength leading to bound 29Ne final states. The SDPF-U-MIX shell model calculation in the sd- pf model space provides a better overall agreement with the measured energy levels of 29Ne and the fp-intruder amplitudes in 30Ne than the SDPF-M prediction, suggesting that the refinement of the sd- pf cross shell interaction and extension of the model space to include the 2p1/2 and 1f5/2 levels are important for understanding the island of inversion.

  5. Stability of quantum-dot excited-state laser emission under simultaneous ground-state perturbation

    SciTech Connect

    Kaptan, Y. Herzog, B.; Schöps, O.; Kolarczik, M.; Woggon, U.; Owschimikow, N.; Röhm, A.; Lingnau, B.; Lüdge, K.; Schmeckebier, H.; Arsenijević, D.; Bimberg, D.; Mikhelashvili, V.; Eisenstein, G.

    2014-11-10

    The impact of ground state amplification on the laser emission of In(Ga)As quantum dot excited state lasers is studied in time-resolved experiments. We find that a depopulation of the quantum dot ground state is followed by a drop in excited state lasing intensity. The magnitude of the drop is strongly dependent on the wavelength of the depletion pulse and the applied injection current. Numerical simulations based on laser rate equations reproduce the experimental results and explain the wavelength dependence by the different dynamics in lasing and non-lasing sub-ensembles within the inhomogeneously broadened quantum dots. At high injection levels, the observed response even upon perturbation of the lasing sub-ensemble is small and followed by a fast recovery, thus supporting the capacity of fast modulation in dual-state devices.

  6. Arsenic in ground water of the Western United States

    USGS Publications Warehouse

    Welch, Alan H.; Lico, Michael S.; Hughes, Jennifer L.

    1988-01-01

    Natural occurrences of ground water with moderate (10 to 50 micrograms per liter) to high (greater than 50 micrograms per liter) concentrations of arsenic are common throughout much of the Western United States. High concentrations of arsenic are generally associated with one of four geochemical environments: (1) basin-fill deposits of alluvial-lacustrine origin, particularly in semiarid areas, (2) volcanic deposits, (3) geothermal systems, and (4) uranium and gold-mining areas. These findings are based on an extensive literature review, compilation of unpublished reports and data, and the review of data bases containing more than 7,000 analyses of ground-water samples for arsenic. In the first two environments, arsenic appears to be associated with sediments derived, in part, from volcanic rocks of intermediate to acidic composition. Dissolved arsenic concentrations in water from volcanic aquifers in the same regions, however, may be low (less than 10 micrograms per liter). Solid phases (minerals, amorphous solids, and sedimentary organic matter) that supply the dissolved arsenic have not been identified in most areas. Alluvial and lacustrine sedimentary deposits appear to be an important source of arsenic in volcanic areas (such as Lane County, Oregon) and in areas underlain by basin-fill deposits (such as Carson Desert in Nevada and the Tulare Lake basin in California). Mobilization of arsenic in sedimentary aquifers may be, in part, a result of changes in the geochemical environment due to agricultural irrigation. In the deeper subsurface, elevated arsenic concentrations are associated with compaction caused by groundwater withdrawals.

  7. Tuning the magnetic ground state of a triangular lattice system

    SciTech Connect

    Garlea, Vasile O; Savici, Andrei T; Jin, Rongying

    2011-01-01

    The anisotropic triangular lattice of the crednerite system Cu(Mn$_{1-x}$Cu$_{x}$)O$_{2}$ is used as a basic model for studying the influence of spin disorder on the ground state properties of a two-dimensional frustrated antiferromagnet. Neutron diffraction measurements show that the undoped phase (x=0) undergoes a transition to antiferromagnetic long-range order that is stabilized by a frustration-relieving structural distortion. Small deviation from the stoichiometric composition alters the magnetoelastic characteristics and reduces the effective dimensionality of the magnetic lattice. Upon increasing the doping level, the interlayer coupling changes from antiferromagnetic to ferromagnetic, while the structural distortion is fully suppressed. Concomitantly, the long-range magnetic order is gradually transformed into a two-dimensional order.

  8. Ground state solutions for semilinear time-harmonic Maxwell equations

    NASA Astrophysics Data System (ADS)

    Tang, Xianhua; Qin, Dongdong

    2016-04-01

    This paper is concerned with the time-harmonic semilinear Maxwell equation: ∇ × (∇ × u) + λu = f(x, u) in Ω with the boundary condition ν × u = 0 on ∂Ω, where Ω ⊂ ℝ3 is a simply connected, smooth, bounded domain with connected boundary and ν : ∂Ω → ℝ3 is the exterior normal. Here ∇ × denotes the curl operator in ℝ3 and the boundary condition holds when Ω is surrounded by a perfect conductor. By using the generalized Nehari manifold method due to Szulkin and Weth [Handbook of Nonconvex Analysis and Applications (International Press, Somerville, 2010), pp. 597-632] and some new techniques, existence of ground state solutions for above equation is established under some generic conditions on f.

  9. Wilson operator algebras and ground states of coupled BF theories

    NASA Astrophysics Data System (ADS)

    Tiwari, Apoorv; Chen, Xiao; Ryu, Shinsei

    2017-06-01

    The multiflavor BF theories in (3+1) dimensions with cubic or quartic coupling are the simplest topological quantum field theories that can describe fractional braiding statistics between looplike topological excitations (three-loop or four-loop braiding statistics). In this paper, by canonically quantizing these theories, we study the algebra of Wilson loop and Wilson surface operators, and multiplets of ground states on the three-torus. In particular, by quantizing these coupled BF theories on the three-torus, we explicitly calculate the S and T matrices, which encode fractional braiding statistics and the topological spin of looplike excitations, respectively. In the coupled BF theories with cubic and quartic coupling, the Hopf link and Borromean ring of loop excitations, together with pointlike excitations, form composite particles.

  10. a New Phenomenological Formula for Ground-State Binding Energies

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, G.

    A phenomenological formula based on liquid drop model has been proposed for ground-state binding energies of nuclei. The effect due to bunching of single particle levels has been incorporated through a term resembling the one-body Hamiltonian. The effect of n-p interaction has been included through a function of valence nucleons. A total of 50 parameters has been used in the present calculation. The root mean square (r.m.s.) deviation for the binding energy values for 2140 nuclei comes out to be 0.376 MeV, and that for 1091 alpha decay energies is 0.284 MeV. The correspondence with the conventional liquid drop model is discussed.

  11. Ground-state correlations within a nonperturbative approach

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Herko, J.; Knapp, F.; Lo Iudice, N.; Veselý, P.

    2017-02-01

    The contribution of the two-phonon configurations to the ground state of 4He and 16O is evaluated nonperturbatively using a Hartree-Fock basis within an equation-of-motion phonon method using a nucleon-nucleon optimized chiral potential. Convergence properties of energies and root-mean-square radii versus the harmonic oscillator frequency and space dimensions are investigated. The comparison with the second-order perturbation theory calculations shows that the higher-order terms have an appreciable repulsive effect and yield too-small binding energies and nuclear radii. It is argued that four-phonon configurations, through their strong coupling to two phonons, may provide most of the attractive contribution necessary for filling the gap between theoretical and experimental quantities. Possible strategies for accomplishing such a challenging task are discussed.

  12. LABS problem and ground state spin glasses system

    NASA Astrophysics Data System (ADS)

    Leukhin, A. N.; Bezrodnyi, V. I.; Kozlova, Yu. A.

    2016-12-01

    In our work we demonstrate the new results of an exhaustive search for optimal binary sequences with minimum peak sidelobe (MPS) up to length N=85. The design problem for law autocorrelation binary sequences (LABS) is a notoriously difficult computational problem which is numbered as the problem number 005 in CSPLib. In statistical physics LABS problem can be interrepted as the energy of N iteracting Ising spins. This is a Bernasconi model. Due to this connection to physics we refer a binary sequence as one-dimensional spin lattice. At this assumption optimal binary sequences by merit factor (MF) criteria are the ground-state spin system without disorder which exhibits a glassy regime.

  13. First resonant tunneling via a light-hole ground state

    NASA Astrophysics Data System (ADS)

    Lampin, J. F.; Mollot, F.

    1998-07-01

    We report the demonstration of resonant tunneling of light-holes through an AlAs/GaAs 0.7P 0.3 double-barrier heterostructure. The tensile strain in the quantum well reverses the order of the light- and heavy-hole levels, the first light-hole level becoming the ground state. The I( V) characteristics are measured at different temperatures and compared to those of a standard AlAs/GaAs unstrained structure. The peak current density of the first light-hole resonance and its peak-to-valley current ratio are enhanced. They reach 28 A/cm 2 and 3.4 : 1 at 15 K. A negative differential resistance is observed up to 250 K.

  14. Absence of Quantum Time Crystals in Ground States

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruki; Oshikawa, Masaki

    2015-03-01

    In analogy with crystalline solids around us, Wilczek recently proposed the idea of ``time crystals'' as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state of a general Hamiltonian which consists of only short-range interactions.

  15. Masses of Ground- and Excited-State Hadrons

    NASA Astrophysics Data System (ADS)

    Roberts, Hannes L. L.; Chang, Lei; Cloët, Ian C.; Roberts, Craig D.

    2011-07-01

    We present the first Dyson-Schwinger equation calculation of the light hadron spectrum that simultaneously correlates the masses of meson and baryon ground- and excited-states within a single framework. At the core of our analysis is a symmetry-preserving treatment of a vector-vector contact interaction. In comparison with relevant quantities the root-mean-square-relative-error/degree-of freedom is 13%. Notable amongst our results is agreement between the computed baryon masses and the bare masses employed in modern dynamical coupled-channels models of pion-nucleon reactions. Our analysis provides insight into numerous aspects of baryon structure; e.g., relationships between the nucleon and Δ masses and those of the dressed-quark and diquark correlations they contain.

  16. The Ground and First Excited Torsional States of Acetic Acid.

    PubMed

    Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.; Podnos, S. V.; Kleiner, I.; Margulès, L.; Wlodarczak, G.; Demaison, J.; Cosléou, J.; Maté, B.; Karyakin, E. N.; Golubiatnikov, G. Yu.; Fraser, G. T.; Suenram, R. D.; Hougen, J. T.

    2001-02-01

    A global fit of microwave and millimeter-wave rotational transitions in the ground and first excited torsional states (v(t) = 0 and 1) of acetic acid (CH(3)COOH) is reported, which combines older measurements from the literature with new measurements from Kharkov, Lille, and NIST. The fit uses a model developed initially for acetaldehyde and methanol-type internal rotor molecules. It requires 34 parameters to achieve a unitless weighted standard deviation of 0.84 for a total of 2518 data and includes A- and E-species transitions with J

  17. Tensor Forces and the Ground-State Structure of Nuclei

    SciTech Connect

    Rocco Schiavilla

    2007-03-01

    Two-nucleon momentum distributions are calculated for the ground states of nuclei with mass number A {le} 8, using accurate variational Monte Carlo wave functions derived from a realistic Hamiltonian with two- and three-nucleon potentials. The momentum distribution of 'np' pairs is found to be much larger than that of 'pp' pairs for values of the relative momentum in the range (300--600) MeV/c and vanishing total momentum. This large difference, more than an order of magnitude, is seen in all nuclei considered, and has a universal character originating from the tensor components present in any realistic nucleon-nucleon potential. The correlations induced by the tensor force strongly influence the structure of 'np' pairs, which are known to be predominantly in deuteron-like states, while they are ineffective for 'pp' pairs, which are mostly in {sup 1}S{sub 0} states. These features should be easily observable in two-nucleon knock-out processes, for example in A(e,e{prime} np) and A(e,e{prime} pp) reactions.

  18. Damping of collective states in an extended random-phase approximation with ground-state correlations

    SciTech Connect

    Tohyama, Mitsuru

    2007-04-15

    Applications of an extended version of the Hartree-Fock theory and the random-phase approximation derived from the time-dependent density-matrix theory (TDDM) are presented. In this TDDM-based theory, the ground state is given as a stationary solution of the TDDM equations and the excited states are calculated using the small-amplitude limit of TDDM. The first application presented is an extended Lipkin model in which an interaction term describing a particle scattering is added to the original Hamiltonian so that the damping of a collective state is taken into account. It is found that the TDDM-based theory well reproduces the ground state and excited states of the extended Lipkin model. The quadrupole excitation of the oxygen isotopes {sup 16,20,22}O is also studied as realistic applications of the TDDM-based theory. It is found that large fragmentation of the giant quadrupole resonance in {sup 16}O is reproduced, and it is pointed out that the effects of ground-state correlations are quite important for fragmentation. It is also found that the quadrupole states in neutron-rich oxygen isotopes have small spreading widths.

  19. Polarization-dependent tuning of the Hanle effect in the ground state of Cs

    NASA Astrophysics Data System (ADS)

    Ravi, Harish; Bhattarai, Mangesh; Bharti, Vineet; Natarajan, Vasant

    2017-03-01

    We demonstrate that the Hanle effect can be tuned between magnetically induced absorption (MIA) and magnetically induced transmission (MIT) simply by changing the polarization of the input laser beam. The experiments are done using closed hyperfine transitions of the D2 line of 133Cs —F g = 3 → F e = 2 and F g = 4 → F e = 5. The former shows a transformation from MIT to MIA, while the latter shows the opposite behavior. A qualitative explanation based on optical pumping and coherences among the magnetic sublevels of the ground state is borne out by a detailed density-matrix calculation. To increase the coherence time, the experiments are done in a Cs vapor cell with paraffin coating on the walls. The observed linewidth is extremely narrow (∼ 0.1 mG) compared to previous work in this area, making this a promising technique for all kinds of precision measurements.

  20. Electron excitation from ground state to first excited state: Bohmian mechanics method

    NASA Astrophysics Data System (ADS)

    Yang, Song; Shuang, Zhao; Fu-Ming, Guo; Yu-Jun, Yang; Su-Yu, Li

    2016-03-01

    The excitation process of electrons from the ground state to the first excited state via the resonant laser pulse is investigated by the Bohmian mechanics method. It is found that the Bohmian particles far away from the nucleus are easier to be excited and are excited firstly, while the Bohmian particles in the ground state is subject to a strong quantum force at a certain moment, being excited to the first excited state instantaneously. A detailed analysis for one of the trajectories is made, and finally we present the space and energy distribution of 2000 Bohmian particles at several typical instants and analyze their dynamical process at these moments. Project supported by the Doctoral Research Start-up Funding of Northeast Dianli University, China (Grant No. BSJXM-201332), the National Natural Science Foundation of China (Grant Nos. 11547114, 11534004, 11474129, 11274141, 11447192, and 11304116), and the Graduate Innovation Fund of Jilin University, China (Grant No. 2015091).

  1. Ground state bromine atom density measurements by two-photon absorption laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Sirse, N.; Foucher, M.; Chabert, P.; Booth, J.-P.

    2014-12-01

    Ground state bromine atom detection by two-photon absorption laser-induced fluorescence (TALIF) is demonstrated. The (4p5) {^2Po3/2} bromine atoms are excited by two-photon absorption at 252.594 nm to the (5p) {^4So3/2} state and detected by 635.25 nm fluorescence to the (5s) 4P5/2 state. The atoms are generated in a radio-frequency inductively-coupled plasma in pure HBr. The excitation laser also causes some photodissociation of HBr molecules, but this can be minimized by not focussing the laser beam, still giving adequate signal levels. We determined the natural lifetime of the emitting (5p) {^4So3/2} state, τf^Br*=30.9 +/- 1.4 ns and the rate constant for quenching of this state by collision with HBr molecules, k_HBrQ = 1.02 +/- 0.07× 10-15 m3 s-1 .

  2. Antiferromagnetic ground state in NpCoGe

    NASA Astrophysics Data System (ADS)

    Colineau, E.; Griveau, J.-C.; Eloirdi, R.; Gaczyński, P.; Khmelevskyi, S.; Shick, A. B.; Caciuffo, R.

    2014-03-01

    NpCoGe, the neptunium analog of the ferromagnetic superconductor UCoGe, has been investigated by dc magnetization, ac susceptibility, specific heat, electrical resistivity, Hall effect, 237Np Mössbauer spectroscopy, and local spin-density approximation (LSDA) calculations. NpCoGe exhibits an antiferromagnetic ground state with a Néel temperature TN≈13 K and an average ordered magnetic moment <μNp>=0.80μB. The magnetic phase diagram has been determined and shows that the antiferromagnetic structure is destroyed by the application of a magnetic field (≈3 T). The value of the isomer shift suggests a Np3+ charge state (configuration 5f4). A high Sommerfeld coefficient value for NpCoGe (170 mJ mol-1 K-2) is inferred from specific heat. LSDA calculations indicate strong magnetic anisotropy and easy magnetization along the c axis. Mössbauer data and calculated exchange interactions support the possible occurrence of an elliptical spin-spiral structure in NpCoGe. The comparison with NpRhGe and uranium analogs suggests the leading role of 5f-d hybridization, the rather delocalized character of 5f electrons in NpCoGe, and the possible proximity of NpRuGe or NpFeGe to a magnetic quantum critical point.

  3. State estimators for tracking sharply-maneuvering ground targets

    NASA Astrophysics Data System (ADS)

    Visina, Radu S.; Bar-Shalom, Yaakov; Willett, Peter

    2017-05-01

    This paper presents an algorithm, based on the Interacting Multiple Model Estimator, that can be used to track the state of kinematic point targets, moving in two dimensions, that are capable of making sharp heading maneuvers over short periods of time, such as certain ground vehicles moving in an open field. The targets are capable of up to 60 °/s turn rates, while polar measurements are received at 1 Hz. We introduce the Non-Zero Mean, White Noise Turn-Rate IMM (IMM-WNTR) that consists of 3 modes based on a White Noise Turn Rate (WNTR) kinematic model that contains additive, white, Gaussian turn rate process noises. Two of the modes are considered maneuvering modes, and they have opposite (left/right), non-zero mean turn rate input noise. The need for non-zero mean turn rate process noise is explained, and Monte Carlo simulations compare this novel design to the traditional (single-mode) White Noise Acceleration Kalman Filter (WNA KF) and the two-mode White Noise Acceleration/Nearly-Coordinated Turn Rate IMM (IMM-CT). Results show that the IMM-WNTR filter achieves better accuracy and real-time consistency between expected error and actual error as compared to the (single-mode) WNA KF and the IMM-CT in all simulated scenarios, making it a very accurate state estimator for targets with sharp coordinated turn capability in 2D.

  4. Tracking the embryonic stem cell transition from ground state pluripotency.

    PubMed

    Kalkan, Tüzer; Olova, Nelly; Roode, Mila; Mulas, Carla; Lee, Heather J; Nett, Isabelle; Marks, Hendrik; Walker, Rachael; Stunnenberg, Hendrik G; Lilley, Kathryn S; Nichols, Jennifer; Reik, Wolf; Bertone, Paul; Smith, Austin

    2017-04-01

    Mouse embryonic stem (ES) cells are locked into self-renewal by shielding from inductive cues. Release from this ground state in minimal conditions offers a system for delineating developmental progression from naïve pluripotency. Here, we examine the initial transition process. The ES cell population behaves asynchronously. We therefore exploited a short-half-life Rex1::GFP reporter to isolate cells either side of exit from naïve status. Extinction of ES cell identity in single cells is acute. It occurs only after near-complete elimination of naïve pluripotency factors, but precedes appearance of lineage specification markers. Cells newly departed from the ES cell state display features of early post-implantation epiblast and are distinct from primed epiblast. They also exhibit a genome-wide increase in DNA methylation, intermediate between early and late epiblast. These findings are consistent with the proposition that naïve cells transition to a distinct formative phase of pluripotency preparatory to lineage priming.

  5. Tunable ground states in helical p-wave Josephson junctions

    NASA Astrophysics Data System (ADS)

    Cheng, Qiang; Zhang, Kunhua; Yu, Dongyang; Chen, Chongju; Zhang, Yinhan; Jin, Biao

    2016-07-01

    We study new types of Josephson junctions composed of helical p-wave superconductors with {k}x\\hat{x}+/- {k}y\\hat{y} and {k}y\\hat{x}+/- {k}x\\hat{y}-pairing symmetries using quasi-classical Green’s functions with generalized Riccati parametrization. The junctions can host rich ground states: π phase, 0 + π phase, φ 0 phase and φ phase. The phase transition can be tuned by rotating the magnetization in the ferromagnetic interface. We present the phase diagrams in the parameter space formed by the orientation of the magnetization or by the magnitude of the interfacial potentials. The selection rules for the lowest order current which are responsible for the formation of the rich phases are summarized from the current-phase relations based on the numerical calculation. We construct a Ginzburg-Landau type of free energy for the junctions with d-vectors and the magnetization, which not only reveals the interaction forms of spin-triplet superconductivity and ferromagnetism, but can also directly lead to the selection rules. In addition, the energies of the Andreev bound states and the novel symmetries in the current-phase relations are also investigated. Our results are helpful both in the prediction of novel Josephson phases and in the design of quantum circuits.

  6. Ground state and resonant states of helium in exponential cosine screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Ghoshal, Arijit; Ho, Y. K.

    2009-05-01

    We have investigated the ground state and a resonance state of normal helium atom in exponential cosine screened Coulomb potential (ECSCP) with screening parameterλ: V(r),,,1r,^-λr(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz's variational principle and making use of a highly correlated wave function, we have determined the ground state energies and wave functions of the helium atom for different values of the screening parameterλ. Furthermore, we have shown that the ground state energy of helium for a particular value of λ does converge with increasing number of terms in the wave function. In addition, using the stabilization method, we have investigated the doubly excited 2s^2 ^1S^e resonance state in helium with ECSCP. Resonance energy and width for various λ values are calculated. Our present work will play a useful role in the investigations of atomic structures in quantum plasmas [1]. [1]. P.K. Shukla and B. Eliasson, Phys. Lett. A 372, 2899 (2008).

  7. Ground-state splitting of ultrashallow thermal donors with negative central-cell corrections in silicon

    NASA Astrophysics Data System (ADS)

    Hara, Akito; Awano, Teruyoshi

    2017-06-01

    Ultrashallow thermal donors (USTDs), which consist of light element impurities such as carbon, hydrogen, and oxygen, have been found in Czochralski silicon (CZ Si) crystals. To the best of our knowledge, these are the shallowest hydrogen-like donors with negative central-cell corrections in Si. We observed the ground-state splitting of USTDs by far-infrared optical absorption at different temperatures. The upper ground-state levels are approximately 4 meV higher than the ground-state levels. This energy level splitting is also consistent with that obtained by thermal excitation from the ground state to the upper ground state. This is direct evidence that the wave function of the USTD ground state is made up of a linear combination of conduction band minimums.

  8. Arsenic in Ground-Water Resources of the United States

    USGS Publications Warehouse

    Welch, Alan H.; Watkins, Sharon A.; Helsel, Dennis R.; Focazio, Michael J.

    2000-01-01

    Arsenic is a naturally occurring element in rocks, soils, and the waters in contact with them. Recognized as a toxic element for centuries, arsenic today also is a human health concern because it can contribute to skin, bladder, and other cancers (National Research Council, 1999). Recently, the National Research Council (1999) recommended lowering the current maximum contaminant level (MCL) allowed for arsenic in drinking water of 50 ?g/L (micrograms per liter), citing risks for developing bladder and other cancers. The U.S. Environmental Protection Agency (USEPA) will propose a new, and likely lower, arsenic MCL during 2000 (U.S. Environmental Protection Agency, 2000). This fact sheet provides information on where and to what extent natural concentrations of arsenic in ground water exceed possible new standards. The U.S. Geological Survey (USGS) has collected and analyzed arsenic in potable (drinkable) water from 18,850 wells in 595 counties across the United States during the past two decades. These wells are used for irrigation, industrial purposes, and research, as well as for public and private water supply. Arsenic concentrations in samples from these wells are similar to those found in nearby public supplies (see Focazio and others, 1999). The large number of samples, broad geographic coverage, and consistency of methods produce a more accurate and detailed picture of arsenic concentrations than provided by any previous studies.

  9. Ground-state coding in partially connected neural networks

    NASA Technical Reports Server (NTRS)

    Baram, Yoram

    1989-01-01

    Patterns over (-1,0,1) define, by their outer products, partially connected neural networks, consisting of internally strongly connected, externally weakly connected subnetworks. The connectivity patterns may have highly organized structures, such as lattices and fractal trees or nests. Subpatterns over (-1,1) define the subcodes stored in the subnetwork, that agree in their common bits. It is first shown that the code words are locally stable stares of the network, provided that each of the subcodes consists of mutually orthogonal words or of, at most, two words. Then it is shown that if each of the subcodes consists of two orthogonal words, the code words are the unique ground states (absolute minima) of the Hamiltonian associated with the network. The regions of attraction associated with the code words are shown to grow with the number of subnetworks sharing each of the neurons. Depending on the particular network architecture, the code sizes of partially connected networks can be vastly greater than those of fully connected ones and their error correction capabilities can be significantly greater than those of the disconnected subnetworks. The codes associated with lattice-structured and hierarchical networks are discussed in some detail.

  10. New Ground-State Crystal Structure of Elemental Boron

    NASA Astrophysics Data System (ADS)

    An, Qi; Reddy, K. Madhav; Xie, Kelvin Y.; Hemker, Kevin J.; Goddard, William A.

    2016-08-01

    Elemental boron exhibits many polymorphs in nature based mostly on an icosahedral shell motif, involving stabilization of 13 strong multicenter intraicosahedral bonds. It is commonly accepted that the most thermodynamic stable structure of elemental boron at atmospheric pressure is the β rhombohedral boron (β -B ). Surprisingly, using high-resolution transmission electron microscopy, we found that pure boron powder contains grains of two different types, the previously identified β -B containing a number of randomly spaced twins and what appears to be a fully transformed twinlike structure. This fully transformed structure, denoted here as τ -B , is based on the C m c m orthorhombic space group. Quantum mechanics predicts that the newly identified τ -B structure is 13.8 meV /B more stable than β -B . The τ -B structure allows 6% more charge transfer from B57 units to nearby B12 units, making the net charge 6% closer to the ideal expected from Wade's rules. Thus, we predict the τ -B structure to be the ground state structure for elemental boron at atmospheric pressure.

  11. Ground-state properties of neutron-rich Mg isotopes

    NASA Astrophysics Data System (ADS)

    Watanabe, S.; Minomo, K.; Shimada, M.; Tagami, S.; Kimura, M.; Takechi, M.; Fukuda, M.; Nishimura, D.; Suzuki, T.; Matsumoto, T.; Shimizu, Y. R.; Yahiro, M.

    2014-04-01

    We analyze recently measured total reaction cross sections for 24-38Mg isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model and antisymmetrized molecular dynamics (AMD). The folding model well reproduces the measured reaction cross sections, when the projectile densities are evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation. Matter radii of 24-38Mg are then deduced from the measured reaction cross sections by fine tuning the parameters of the def-WS model. The deduced matter radii are largely enhanced by nuclear deformation. Fully microscopic AMD calculations with no free parameter well reproduce the deduced matter radii for 24-36Mg, but still considerably underestimate them for 37,38Mg. The large matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD also reproduces other existing measured ground-state properties (spin parity, total binding energy, and one-neutron separation energy) of Mg isotopes. Neutron-number (N) dependence of deformation parameter is predicted by AMD. Large deformation is seen from 31Mg with N =19 to a drip-line nucleus 40Mg with N =28, indicating that both the N =20 and 28 magicities disappear. N dependence of neutron skin thickness is also predicted by AMD.

  12. Short-range interaction energy for ground state H2+

    NASA Astrophysics Data System (ADS)

    Battezzati, Michele; Magnasco, Valerio

    2006-12-01

    Two of the Hermitian eigenvalue equations resulting from the separation of the three-dimensional Schroedinger equation for H2+ in spheroidals are solved perturbatively for the ground state by expanding the action in positive powers of the internuclear distance R near the united atom He+. The dispersion relations between the separation constants A and Ee are seen to have rigorous analytic solutions, the third-order equation leading to an exact expansion for the inner determinantal equation up to R10. The explicit form for the expansion coefficients is determined up to n = 10, and is seen to contain up to the third power of (γ + ln 4R) logarithmic terms. Even if the general range of validity of the short-range Rn-expansion is expected to be smaller than the corresponding long-range R-n-expansion, it is important to stress that such higher expansion coefficients are calculated exactly for the first time. These formulae give extremely accurate numerical results up to R cong 0.3a0.

  13. Antimatter Advances Include Trapped Antihydrogen in Its Ground State

    NASA Astrophysics Data System (ADS)

    Richerme, Phil

    2012-06-01

    Three recent advances in antimatter physics show significant progress towards precision tests of fundamental symmetries. The first and primary focus of this talk is ATRAP's observation of five simultaneously trapped antihydrogen atoms per trial, confined for long enough to ensure that they are in their ground state.ootnotetextG. Gabrielse et al. (ATRAP Collaboration). Phys. Rev. Lett. 108, 113002 (2012). Large numbers of simultaneously trapped atoms are crucial if laser cooling and spectroscopy of antihydrogen at high levels of precision are to be achieved. Fundamental to this result is the careful control and characterization of the geometry and temperature of the large-number antiproton and positron plasmas from which antihydrogen is formed, along with enhanced event detection and cosmic ray background rejection techniques. A second advance, by the ALPHA collaboration, is a demonstration that smaller numbers of simultaneously trapped antihydrogen atoms can be ejected from a magnetic trap when microwaves flip the spin of the atoms.ootnotetextC. Amole et al. (ALPHA Collaboration). Nature 483, 439 (2012). A third advance is a direct measurement of the proton magnetic moment to 2.5 parts per million using a technique that can be directly applied to an antiprotonootnotetextJ. DiSciacca and G. Gabrielse. Phys. Rev. Lett. 108, 153001 (2012). to improve the precision with which the antiproton magnetic moment is measured by a factor of 1000.

  14. Table of experimental nuclear ground state charge radii: An update

    SciTech Connect

    Angeli, I.; Marinova, K.P.

    2013-01-15

    The present table contains experimental root-mean-square (rms) nuclear charge radii R obtained by combined analysis of two types of experimental data: (i) radii changes determined from optical and, to a lesser extent, K{sub α} X-ray isotope shifts and (ii) absolute radii measured by muonic spectra and electronic scattering experiments. The table combines the results of two working groups, using respectively two different methods of evaluation, published in ADNDT earlier. It presents an updated set of rms charge radii for 909 isotopes of 92 elements from {sub 1}H to {sub 96}Cm together, when available, with the radii changes from optical isotope shifts. Compared with the last published tables of R-values from 2004 (799 ground states), many new data are added due to progress recently achieved by laser spectroscopy up to early 2011. The radii changes in isotopic chains for He, Li, Be, Ne, Sc, Mn, Y, Nb, Bi have been first obtained in the last years and several isotopic sequences have been recently extended to regions far off stability, (e.g., Ar, Mo, Sn, Te, Pb, Po)

  15. On-ground calibration of AGILE-GRID with a photon beam: results and lessons for the future

    NASA Astrophysics Data System (ADS)

    Cattaneo, P. W.; Rappoldi, A.

    2013-06-01

    On the AGILE satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs a calibration with a γ-ray beam to validate the simulation used to calculate the detector response versus the energy and the direction of the γ rays. A tagged γ-ray beam line was designed at the Beam Test Facility of the Laboratori Nazionali of Frascati, generated by an electron beam through bremsstrahlung in a position-sensitive target. The γ-ray energy is deduced by the difference with the post-bremsstrahlung electron energy [P. W. Cattaneo, et al., Characterization of a tagged γ-ray beam line at the daΦne beam test facility, Nucl. Instr. and Meth. A 674 (2012) 55-66; P. W. Cattaneo, et al., First results about on-ground calibration of the silicon tracker for the agile satellite, Nucl. Instr. and Meth. A 630(1) (2011) 251-257.]. The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). In this paper the setup and the calibration of AGILE performed in 2005 are described.

  16. Local reversibility and entanglement structure of many-body ground states

    NASA Astrophysics Data System (ADS)

    Kuwahara, Tomotaka; Arad, Itai; Amico, Luigi; Vedral, Vlatko

    2017-03-01

    The low-temperature physics of quantum many-body systems is largely governed by the structure of their ground states. Minimizing the energy of local interactions, ground states often reflect strong properties of locality such as the area law for entanglement entropy and the exponential decay of correlations between spatially separated observables. Here, we present a novel characterization of quantum states, which we call ‘local reversibility’. It characterizes the type of operations that are needed to reverse the action of a general disturbance on the state. We prove that unique ground states of gapped local Hamiltonian are locally reversible. This way, we identify new universal features of many-body ground states, which cannot be derived from the aforementioned properties. We use local reversibility to distinguish between states enjoying microscopic and macroscopic quantum phenomena. To demonstrate the potential of our approach, we prove specific properties of ground states, which are relevant both to critical and non-critical theories.

  17. Ground-State SiO Maser Emission Toward Evolved Stars

    DTIC Science & Technology

    2006-05-31

    emulateapj v. 11/12/01 GROUND-STATE SIO MASER EMISSION TOWARD EVOLVED STARS D. A. BOBOLTZ U.S. Naval Observatory, 3450 Massachusetts Ave., NW...Accepted by the Astrophysical Journal 2004 February 20 ABSTRACT We have made the first unambiguous detection of vibrational ground-state maser emission ...observed. Ground-state thermal emission was detected for one of the stars, RX Boo, with a peak brightness temperature of 200 K. Comparing the v = 0 and

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

    SciTech Connect

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

    2011-03-20

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

  19. A ground state depleted laser in neodymium doped yttrium orthosilicate

    SciTech Connect

    Beach, R.; Albrecht, G.; Solarz, R.; Krupke, W.; Comaskey, B.; Mitchell, S.; Brandle, C.; Berkstresser, G.

    1990-01-16

    A ground state depleted (GSD){sup 1,2} laser has been demonstrated in the form of a Q-switched oscillator operating at 912 nm. Using Nd{sup 3+} as the active ion and Y{sub 2}SiO{sub 5} as the host material, the laser transition is from the lowest lying stark level of the Nd{sup 3t}F{sub 3/2} level to a stark level 355 cm{sup {minus}1} above the lowest lying one in the {sup 4}I{sub 9/2} manifold. The necessity of depleting the ground {sup 4}I{sub 9/2} manifold is evident for this level scheme as transparency requires a 10% inversion. To achieve the high excitation levels required for the efficient operation of this laser, bleach wave pumping using an alexandrite laser at 745 nm has been employed. The existence of a large absorption feature at 810 nm also allows for the possibility of AlGaAs laser diode pumping. Using KNbO{sub 3}, noncritical phase matching is possible at 140{degree}C using d{sub 32} and has been demonstrated. The results of Q-switched laser performance and harmonic generation in KNbO{sub 3} will be presented. Orthosilicate can be grown in large boules of excellent optical quality using a Czochralski technique. Because of the relatively small 912 nm emission cross section of 2-3 {times} 10{sup {minus}20} cm{sup 2} (orientation dependent) fluences of 10-20 J/cm{sup 2} must be circulated in the laser cavity for the efficient extraction of stored energy. This necessitates very aggressive laser damage thresholds. Results from the Reptile laser damage facility at Lawrence Livermore National Laboratory (LLNL) will be presented showing Y{sub 2}SiO{sub 5} bulk and AR sol-gel coated surface damage thresholds of greater than 40 J/cm{sup 2} for 10 nsec, 10 Hz, 1.06 {mu} pulses. 16 refs., 18 figs., 6 tabs.

  20. Lower bounds for the ground-state degeneracies of frustrated systems on fractal lattices

    PubMed

    Curado; Nobre

    2000-12-01

    The total number of ground states for nearest-neighbor-interaction Ising systems with frustrations, defined on hierarchical lattices, is investigated. A simple method is presented, which allows one to factorize the ground-state degeneracy, at a given hierarchy level n, in terms of contributions due to all hierarchy levels. Such a method may yield the exact ground-state degeneracy of uniformly frustrated systems, whereas it works as an approximation for randomly frustrated models. In the latter cases, it is demonstrated that such an approximation yields lower-bound estimates for the ground-state degeneracies.

  1. Ground Water Quality Protection. State and Local Strategies.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC. Commission on Physical Sciences, Mathematics, and Resources.

    Using regional case studies, this document examines representative programs for dealing with ground water contamination. Section one describes the ground water protection strategy of the U.S. Environmental Protection Agency (EPA); (2) discusses the limited data available for determining the extent of contamination; (3) provides a listing of the…

  2. Ground Water Quality Protection. State and Local Strategies.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC. Commission on Physical Sciences, Mathematics, and Resources.

    Using regional case studies, this document examines representative programs for dealing with ground water contamination. Section one describes the ground water protection strategy of the U.S. Environmental Protection Agency (EPA); (2) discusses the limited data available for determining the extent of contamination; (3) provides a listing of the…

  3. Spontaneous fission half-lives of heavy nuclei in ground state and in isomeric state

    NASA Astrophysics Data System (ADS)

    Ren, Zhongzhou; Xu, Chang

    2005-09-01

    We generalize the formulas of spontaneous fission half-lives of even-even nuclei in their ground state to both the case of odd nuclei and the case of fission isomers [Phys. Rev. C 71 (2005) 014309]. The spontaneous fission half-lives of odd- A nuclei and of odd-odd nuclei in the ground state are calculated by Swiatecki's formula, by its generalized form, and by a new formula where the blocking effect of unpaired nucleon on the half-lives has been taken into account with different mechanisms. By introducing a blocking factor or a generalized seniority in the formulas of the half-lives of even-even nuclei, we can reasonably reproduce the experimental fission half-lives of odd- A nuclei and of odd-odd nuclei with the same parameters used in ground state of even-even nuclei. For spontaneous fission of the isomers in transuranium nuclei the new formula can be simplified into a three-parameter formula and the isomeric half-lives can be well reproduced by the formula. The new formula of the isomeric half-lives is as good as Metag's formula of fission isomers. The half-lives of isomers from these formulas are very accurate and therefore these formulas can give reliable predictions for half-lives of new isomers of neighboring nuclei.

  4. Derivation of novel human ground state naive pluripotent stem cells.

    PubMed

    Gafni, Ohad; Weinberger, Leehee; Mansour, Abed AlFatah; Manor, Yair S; Chomsky, Elad; Ben-Yosef, Dalit; Kalma, Yael; Viukov, Sergey; Maza, Itay; Zviran, Asaf; Rais, Yoach; Shipony, Zohar; Mukamel, Zohar; Krupalnik, Vladislav; Zerbib, Mirie; Geula, Shay; Caspi, Inbal; Schneir, Dan; Shwartz, Tamar; Gilad, Shlomit; Amann-Zalcenstein, Daniela; Benjamin, Sima; Amit, Ido; Tanay, Amos; Massarwa, Rada; Novershtern, Noa; Hanna, Jacob H

    2013-12-12

    Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3β signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, and global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters. Upon withdrawal of 2i/LIF, naive mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include predominant use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalent domain acquisition on lineage regulatory genes. The feasibility of establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in mouse ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation

  5. E2 transitions between excited single-phonon states: Role of ground-state correlations

    NASA Astrophysics Data System (ADS)

    Kamerdzhiev, S. P.; Voitenkov, D. A.

    2016-11-01

    The probabilities for E2 transitions between low-lying excited 3- and 5- single-phonon states in the 208Pb and 132Sn magic nuclei are estimated on the basis of the theory of finite Fermi systems. The approach used involves a new type of ground-state correlations, that which originates from integration of three (rather than two, as in the random-phase approximation) single-particle Green's functions. These correlations are shown to make a significant contribution to the probabilities for the aforementioned transitions.

  6. E2 transitions between excited single-phonon states: Role of ground-state correlations

    SciTech Connect

    Kamerdzhiev, S. P.; Voitenkov, D. A.

    2016-11-15

    The probabilities for E2 transitions between low-lying excited 3{sup −} and 5{sup −} single-phonon states in the {sup 208}Pb and {sup 132}Sn magic nuclei are estimated on the basis of the theory of finite Fermi systems. The approach used involves a new type of ground-state correlations, that which originates from integration of three (rather than two, as in the random-phase approximation) single-particle Green’s functions. These correlations are shown to make a significant contribution to the probabilities for the aforementioned transitions.

  7. A Shaky Road to Subnanometer Beams. NLC Ground Motion, Vibration and Stabilization Studies

    SciTech Connect

    Seryi, Andrei

    2001-05-03

    Ground motion and vibration can be a limiting factor in the performance of future linear colliders. Investigations of ground motion have been carried out around the world for several decades. In this review, results of recent investigations of ground motion as well as ongoing developments of stabilization methods are presented.

  8. The H 2O ++ Ground State Potential Energy Surface

    NASA Astrophysics Data System (ADS)

    Bunker, P. R.; Bludsky, Ota; Jensen, Per; Wesolowski, S. S.; Van Huis, T. J.; Yamaguchi, Y.; Schaefer, H. F.

    1999-12-01

    At the correlation-consistent polarized-valence quadruple-zeta complete active space self-consistent field second-order configuration interaction level of ab initio theory (cc-pVQZ CASSCF-SOCI), we calculated 129 points on the ground electronic state potential energy surface of the water dication H2O++; this calculation includes the energy of X3Σ- OH+ at equilibrium and the energy of the triplet oxygen atom. We determined the parameters in an analytical function that represents this surface out to the (OH+ + H+) and (O + 2H+) dissociation limits, for bending angles from 70 to 180°. There is a metastable minimum in this surface, at an energy of 43 600 cm-1 above the H+ + OH+ dissociation energy, and the geometry at this minimum is linear (D∞h), with an OH bond length of 1.195 Å. On the path to dissociation to H+ + OH+, there is a saddle point at an energy of 530 cm-1 above the minimum, and the geometry at the saddle point is linear (C∞ Kv) with OH bond lengths of 1.121 and 1.489 Å. Using the stabilization method, we calculated the lowest resonance on this surface. Relative to the metastable local minimum on the potential energy surface, the position of the lowest resonance for H2O++, D2O++, and T2O++ is 1977(85), 1473(25), and 1249(10) cm-1, respectively, where the width of each resonance (in cm-1) is given in parentheses.

  9. The state of the art in hadron beam cooling

    SciTech Connect

    Prost, L.R.; Derwent, P.; /Fermilab

    2008-09-01

    Cooling of hadron beams (including heavy-ions) is a powerful technique by which accelerator facilities around the world achieve the necessary beam brightness for their physics research. In this paper, we will give an overview of the latest developments in hadron beam cooling, for which high energy electron cooling at Fermilab's Recycler ring and bunched beam stochastic cooling at Brookhaven National Laboratory's RHIC facility represent two recent major accomplishments. Novel ideas in the field will also be introduced.

  10. Measuring OAM states of light beams with gradually-changing-period gratings.

    PubMed

    Dai, Kunjian; Gao, Chunqing; Zhong, Lei; Na, Quanxin; Wang, Qing

    2015-02-15

    A method to measure orbital angular momentum (OAM) states of light beams by using gradually-changing-period gratings is reported. Two kinds of gradually-changing-period gratings were used for the measurement of OAM states. The OAM states of the incident beam can be measured easily from the Hermite-Gaussian-like diffraction patterns. The simulation results agree well with the experiments.

  11. Derivation of the RPA (Random Phase Approximation) Equation of ATDDFT (Adiabatic Time Dependent Density Functional Ground State Response Theory) from an Excited State Variational Approach Based on the Ground State Functional.

    PubMed

    Ziegler, Tom; Krykunov, Mykhaylo; Autschbach, Jochen

    2014-09-09

    The random phase approximation (RPA) equation of adiabatic time dependent density functional ground state response theory (ATDDFT) has been used extensively in studies of excited states. It extracts information about excited states from frequency dependent ground state response properties and avoids, thus, in an elegant way, direct Kohn-Sham calculations on excited states in accordance with the status of DFT as a ground state theory. Thus, excitation energies can be found as resonance poles of frequency dependent ground state polarizability from the eigenvalues of the RPA equation. ATDDFT is approximate in that it makes use of a frequency independent energy kernel derived from the ground state functional. It is shown in this study that one can derive the RPA equation of ATDDFT from a purely variational approach in which stationary states above the ground state are located using our constricted variational DFT (CV-DFT) method and the ground state functional. Thus, locating stationary states above the ground state due to one-electron excitations with a ground state functional is completely equivalent to solving the RPA equation of TDDFT employing the same functional. The present study is an extension of a previous work in which we demonstrated the equivalence between ATDDFT and CV-DFT within the Tamm-Dancoff approximation.

  12. Ground-state and excited-state structures of tungsten-benzylidyne complexes.

    PubMed

    Lovaasen, Benjamin M; Lockard, Jenny V; Cohen, Brian W; Yang, Shujiang; Zhang, Xiaoyi; Simpson, Cheslan K; Chen, Lin X; Hopkins, Michael D

    2012-05-21

    The molecular structure of the tungsten-benzylidyne complex trans-W(≡CPh)(dppe)(2)Cl (1; dppe = 1,2-bis(diphenylphosphino)ethane) in the singlet (d(xy))(2) ground state and luminescent triplet (d(xy))(1)(π*(WCPh))(1) excited state (1*) has been studied using X-ray transient absorption spectroscopy, X-ray crystallography, and density functional theory (DFT) calculations. Molecular-orbital considerations suggest that the W-C and W-P bond lengths should increase in the excited state because of the reduction of the formal W-C bond order and decrease in W→P π-backbonding, respectively, between 1 and 1*. This latter conclusion is supported by comparisons among the W-P bond lengths obtained from the X-ray crystal structures of 1, (d(xy))(1)-configured 1(+), and (d(xy))(2) [W(CPh)(dppe)(2)(NCMe)](+) (2(+)). X-ray transient absorption spectroscopic measurements of the excited-state structure of 1* reveal that the W-C bond length is the same (within experimental error) as that determined by X-ray crystallography for the ground state 1, while the average W-P/W-Cl distance increases by 0.04 Å in the excited state. The small excited-state elongation of the W-C bond relative to the M-E distortions found for M(≡E)L(n) (E = O, N) compounds with analogous (d(xy))(1)(π*(ME))(1) excited states is due to the π conjugation within the WCPh unit, which lessens the local W-C π-antibonding character of the π*(WCPh) lowest unoccupied molecular orbital (LUMO). These conclusions are supported by DFT calculations on 1 and 1*. The similar core bond distances of 1, 1(+), and 1* indicates that the inner-sphere reorganization energy associated with ground- and excited-state electron-transfer reactions is small.

  13. Ground-state and excited-state structures of tungsten-benzylidyne complexes

    SciTech Connect

    Lovaasen, B. M.; Lockard, J. V.; Cohen, B. W.; Yang, S.; Zhang, X.; Simpson, C. K.; Chen, L. X.; Hopkins, M. D.

    2012-01-01

    The molecular structure of the tungsten-benzylidyne complex trans-W({triple_bond}CPh)(dppe){sub 2}Cl (1; dppe = 1,2-bis(diphenylphosphino)ethane) in the singlet (d{sub xy}){sup 2} ground state and luminescent triplet (d{sub xy}){sup 1}({pi}*(WCPh)){sup 1} excited state (1*) has been studied using X-ray transient absorption spectroscopy, X-ray crystallography, and density functional theory (DFT) calculations. Molecular-orbital considerations suggest that the W-C and W-P bond lengths should increase in the excited state because of the reduction of the formal W-C bond order and decrease in W {yields} P {pi}-backbonding, respectively, between 1 and 1*. This latter conclusion is supported by comparisons among the W-P bond lengths obtained from the X-ray crystal structures of 1, (d{sub xy}){sup 1}-configured 1{sup +}, and (d{sub xy}){sup 2} [W(CPh)(dppe){sub 2}(NCMe)]{sup +} (2{sup +}). X-ray transient absorption spectroscopic measurements of the excited-state structure of 1* reveal that the W-C bond length is the same (within experimental error) as that determined by X-ray crystallography for the ground state 1, while the average W-P/W-Cl distance increases by 0.04 {angstrom} in the excited state. The small excited-state elongation of the W-C bond relative to the M-E distortions found for M({triple_bond}E)L{sub n} (E = O, N) compounds with analogous (d{sub xy}){sup 1}({pi}*(ME)){sup 1} excited states is due to the {pi} conjugation within the WCPh unit, which lessens the local W-C {pi}-antibonding character of the {pi}*(WCPh) lowest unoccupied molecular orbital (LUMO). These conclusions are supported by DFT calculations on 1 and 1*. The similar core bond distances of 1, 1{sup +}, and 1* indicates that the inner-sphere reorganization energy associated with ground- and excited-state electron-transfer reactions is small.

  14. Optically induced rotation of Rayleigh particles by vortex beams with different states of polarization

    NASA Astrophysics Data System (ADS)

    Li, Manman; Yan, Shaohui; Yao, Baoli; Liang, Yansheng; Lei, Ming; Yang, Yanlong

    2016-01-01

    Optical vortex beams carry optical orbital angular momentum (OAM) and can induce an orbital motion of trapped particles in optical trapping. We show that the state of polarization (SOP) of vortex beams will affect the details of this optically induced orbital motion to some extent. Numerical results demonstrate that focusing the vortex beams with circular, radial or azimuthal polarizations can induce a uniform orbital motion on a trapped Rayleigh particle, while in the focal field of the vortex beam with linear polarization the particle experiences a non-uniform orbital motion. Among the formers, the vortex beam with circular polarization induces a maximum optical torque on the particle. Furthermore, by varying the topological charge of the vortex beams, the vortex beam with circular polarization gives rise to an optimum torque superior to those given by the other three vortex beams. These facts suggest that the circularly polarized vortex beam is more suitable for rotating particles.

  15. Ground beef consumption patterns in the United States, FoodNet, 2006 through 2007.

    PubMed

    Taylor, Ethel V; Holt, Kristin G; Mahon, Barbara E; Ayers, Tracy; Norton, Dawn; Gould, L Hannah

    2012-02-01

    Infection resulting from foodborne pathogens, including Escherichia coli O157:H7, is often associated with consumption of raw or undercooked ground beef. However, little is known about the frequency of ground beef consumption in the general population. The objective of this study was to describe patterns of self-reported ground beef and pink ground beef consumption using data from the 2006 through 2007 FoodNet Population Survey. From 1 July 2006 until 30 June 2007, residents of 10 FoodNet sites were contacted by telephone and asked about foods consumed within the previous week. The survey included questions regarding consumption of ground beef patties both inside and outside the home, the consumption of pink ground beef patties and other types of ground beef inside the home, and consumption of ground beef outside the home. Of 8,543 survey respondents, 75.3% reported consuming some type of ground beef in the home. Of respondents who ate ground beef patties in the home, 18.0% reported consuming pink ground beef. Consumption of ground beef was reported most frequently among men, persons with incomes from $40,000 to $75,000 per year, and persons with a high school or college education. Ground beef consumption was least often reported in adults ≥65 years of age. Men and persons with a graduate level education most commonly reported eating pink ground beef in the home. Reported consumption of ground beef and pink ground beef did not differ by season. Ground beef is a frequently consumed food item in the United States, and rates of consumption of pink ground beef have changed little since previous studies. The high rate of consumption of beef that has not been cooked sufficiently to kill pathogens makes pasteurization of ground beef an important consideration, especially for those individuals at high risk of complications from foodborne illnesses such as hemolytic uremic syndrome.

  16. Improved lower bounds on the ground-state entropy of the antiferromagnetic Potts model.

    PubMed

    Chang, Shu-Chiuan; Shrock, Robert

    2015-05-01

    We present generalized methods for calculating lower bounds on the ground-state entropy per site, S(0), or equivalently, the ground-state degeneracy per site, W=e(S(0)/k(B)), of the antiferromagnetic Potts model. We use these methods to derive improved lower bounds on W for several lattices.

  17. Study on the ground states of a square-lattice polymer by using exhaustive enumeration

    NASA Astrophysics Data System (ADS)

    Lee, Jae Hwan; Lee, Julian; Kim, Seung-Yeon

    2016-11-01

    We exhaustively enumerate the ground-state conformations of polymers with attractive nearest-neighbor interactions on a square lattice. We find that when the ground-state number is considered as a function of the chain length, local minima appear at magic lengths. However, the ground-state entropy per monomer does not vanish in the thermodynamic limit when an extrapolation is performed with the magic-length data, implying that the number of ground-state conformations grows exponentially. We also study the entropy difference between the ground and the first-excited states. The entropy difference per monomer diverges in the thermodynamic limit, indicating that the zero-tail of the specific heat is modified in the thermodynamic limit.

  18. Comparison of Quality of Bologna Sausage Manufactured by Electron Beam or X-Ray Irradiated Ground Pork

    PubMed Central

    Shin, Mee-Hye

    2014-01-01

    Ground lean pork was irradiated by an electron beam or X-rays to compare the effects of two types of radiation generated by a linear accelerator on the quality of Bologna sausage as a model meat product. Raw ground lean pork was vacuum packaged at a thickness of 1.5 cm and irradiated at doses of 2, 4, 6, 8, or 10 kGy by an electron beam (2.5 MeV) or X-rays (5 MeV). Solubility of myofibrillar proteins, bacterial counts, and thiobarbituric acid reactive substance (TBARS) values were determined for raw meat samples. Bologna sausage was manufactured using the irradiated lean pork, and total bacterial counts, TBARS values, and quality properties (color differences, cooking yield, texture, and palatability) were determined. Irradiation increased the solubility of myofibrillar proteins in a dose-dependent manner (p<0.05). Bacterial contamination of the raw meat was reduced as the absorbed dose increased, and the reduction was the same for both radiation types. Differences were observed only between irradiated and non-irradiated samples (p<0.05). X-ray irradiation may serve as an alternative to gamma irradiation and electron beam irradiation. PMID:26761284

  19. Temperature rise in objects due to optical focused beam through atmospheric turbulence near ground and ocean surface

    NASA Astrophysics Data System (ADS)

    Stoneback, Matthew; Ishimaru, Akira; Reinhardt, Colin; Kuga, Yasuo

    2013-03-01

    We consider an optical beam propagated through the atmosphere and incident on an object causing a temperature rise. In clear air, the physical characteristics of the optical beam transmitted to the object surface are influenced primarily by the effect of atmospheric turbulence, which can be significant near the ground or ocean surface. We use a statistical model to quantify the expected power transfer through turbulent atmosphere and provide guidance toward the threshold of thermal blooming for the considered scenarios. The bulk thermal characteristics of the materials considered are used in a thermal diffusion model to determine the net temperature rise at the object surface due to the incident optical beam. These results of the study are presented in graphical form and are of particular interest to operators of high power laser systems operating over large distances through the atmosphere. Numerical examples include a CO2 laser (λ=10.6 μm) with: aperture size of 5 cm, varied pulse duration, and propagation distance of 0.5 km incident on 0.1-mm copper, 10-mm polyimide, 1-mm water, and 10-mm glass/resin composite targets. To assess the effect of near ground/ocean laser propagation, we compare turbulent (of varying degrees) and nonturbulent atmosphere.

  20. Comparison of Quality of Bologna Sausage Manufactured by Electron Beam or X-Ray Irradiated Ground Pork.

    PubMed

    Shin, Mee-Hye; Lee, Ju-Woon; Yoon, Young-Min; Kim, Jong Heon; Moon, Byeong-Geum; Kim, Jae-Hun; Song, Beom-Suk

    2014-01-01

    Ground lean pork was irradiated by an electron beam or X-rays to compare the effects of two types of radiation generated by a linear accelerator on the quality of Bologna sausage as a model meat product. Raw ground lean pork was vacuum packaged at a thickness of 1.5 cm and irradiated at doses of 2, 4, 6, 8, or 10 kGy by an electron beam (2.5 MeV) or X-rays (5 MeV). Solubility of myofibrillar proteins, bacterial counts, and thiobarbituric acid reactive substance (TBARS) values were determined for raw meat samples. Bologna sausage was manufactured using the irradiated lean pork, and total bacterial counts, TBARS values, and quality properties (color differences, cooking yield, texture, and palatability) were determined. Irradiation increased the solubility of myofibrillar proteins in a dose-dependent manner (p<0.05). Bacterial contamination of the raw meat was reduced as the absorbed dose increased, and the reduction was the same for both radiation types. Differences were observed only between irradiated and non-irradiated samples (p<0.05). X-ray irradiation may serve as an alternative to gamma irradiation and electron beam irradiation.

  1. No-go theorem for ground state cooling given initial system-thermal bath factorization.

    PubMed

    Wu, Lian-Ao; Segal, Dvira; Brumer, Paul

    2013-01-01

    Ground-state cooling and pure state preparation of a small object that is embedded in a thermal environment is an important challenge and a highly desirable quantum technology. This paper proves, with two different methods, that a fundamental constraint on the cooling dynamic implies that it is impossible to cool, via a unitary system-bath quantum evolution, a system that is embedded in a thermal environment down to its ground state, if the initial state is a factorized product of system and bath states. The latter is a crucial but artificial assumption included in numerous tools that treat system-bath dynamics, such as master equation approaches and Kraus operator based methods. Adopting these approaches to address ground state and even approximate ground state cooling dynamics should therefore be done with caution, considering the fundamental theorem exposed in this work.

  2. Formation of High Charge State Heavy Ion Beams with intense Space Charge

    SciTech Connect

    Seidl, P.A.; Vay, J-L.

    2011-03-01

    High charge-state heavy-ion beams are of interest and used for a number of accelerator applications. Some accelerators produce the beams downstream of the ion source by stripping bound electrons from the ions as they pass through a foil or gas. Heavy-ion inertial fusion (HIF) would benefit from low-emittance, high current ion beams with charge state >1. For these accelerators, the desired dimensionless perveance upon extraction from the emitter is {approx}10{sup -3}, and the electrical current of the beam pulse is {approx}1 A. For accelerator applications where high charge state and very high current are desired, space charge effects present unique challenges. For example, in a stripper, the separation of charge states creates significant nonlinear space-charge forces that impact the beam brightness. We will report on the particle-in-cell simulation of the formation of such beams for HIF, using a thin stripper at low energy.

  3. The significant role of covalency in determining the ground state of cobalt phthalocyanines molecule

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Zhang, Linjuan; Hu, Zhiwei; Kuo, Changyang; Liu, Hengjie; Lin, Xiao; Wang, Yu; Pi, Tun-Wen; Wang, Jianqiang; Zhang, Shuo

    2016-03-01

    To shed some light on the metal 3d ground state configuration of cobalt phthalocyanines system, so far in debate, we present an investigation by X-ray absorption spectroscopy (XAS) at Co L2,3 edge and theoretical calculation. The density functional theory calculations reveal highly anisotropic covalent bond between central cobalt ion and nitrogen ligands, with the dominant σ donor accompanied by weak π-back acceptor interaction. Our combined experimental and theoretical study on the Co-L2,3 XAS spectra demonstrate a robust ground state of 2A1g symmetry that is built from 73% 3d7 character and 27% 3 d 8 L ¯ ( L ¯ denotes a ligand hole) components, as the first excited-state with 2Eg symmetry lies about 158 meV higher in energy. The effect of anisotropic and isotropic covalency on the ground state was also calculated and the results indicate that the ground state with 2A1g symmetry is robust in a large range of anisotropic covalent strength while a transition of ground state from 2A1g to 2Eg configuration when isotropic covalent strength increases to a certain extent. Here, we address a significant anisotropic covalent effect of short Co(II)-N bond on the ground state and suggest that it should be taken into account in determining the ground state of analogous cobalt complexes.

  4. Ground-state modulation-enhancement by two-state lasing in quantum-dot laser devices

    SciTech Connect

    Röhm, André; Lingnau, Benjamin; Lüdge, Kathy

    2015-05-11

    We predict a significant increase of the 3 dB-cutoff-frequency on the ground-state lasing wavelength for two-state-lasing quantum-dot lasers using a microscopically motivated multi-level rate-equation model. After the onset of the second lasing line, the excited state acts as a high-pass filter, improving the ground-state response to faster modulation frequencies. We present both numerically simulated small-signal and large-signal modulation results and compare the performance of single and two-state lasing devices. Furthermore, we give dynamical arguments for the advantages of two-state lasing on data-transmission capabilities.

  5. Development of three-dimensional state-space wake theory and application in dynamic ground effect

    NASA Astrophysics Data System (ADS)

    Yu, Ke

    In topics of rotorcraft wake analysis, state-space wake theory has a recognized reputation for advantages in real-time simulation, preliminary design and eigenvalue analysis. Developments in the past decades greatly improved range of validity and accuracy of the state-space modeling approach. This work focuses on further improvement of the state-space wake theory and applications in representing dynamic ground effect. Extended state-space model is developed to represent non-zero mass flux on rotor disk. Its instant practical application, representing ground effect with a mass source ground rotor, is evaluated in both steady and dynamic aspects. Investigations of partial ground effect simulation by state-space model are carried out in different rotor configurations. Additional work is done in improving simulation efficiency of practical application of state-space modeling.

  6. The Ground State of Monolayer Graphene in a Strong Magnetic Field

    PubMed Central

    Wu, Lian-Ao; Guidry, Mike

    2016-01-01

    Experiments indicate that the ground state of graphene in a strong magnetic field exhibits spontaneous breaking of SU(4) symmetry. However, the nature of the corresponding emergent state is unclear because existing theoretical methods approximate the broken-symmetry solutions, yielding nearly-degenerate candidate ground states having different emergent orders. Resolving this ambiguity in the nature of the strong-field ground state is highly desirable, given the importance of graphene for both fundamental physics and technical applications. We have discovered a new SO(8) symmetry that recovers standard graphene SU(4) quantum Hall physics, but predicts two new broken-SU(4) phases and new properties for potential ground states. Our solutions are analytical; thus we capture the essential physics of spontaneously-broken SU(4) states in a powerful yet solvable model useful both in correlating existing data and in suggesting new experiments. PMID:26927477

  7. Summary of informal workshop on state of ion beam facilities for atomic physics research

    SciTech Connect

    Jones, K.W.; Cocke, C.L.; Datz, S.; Kostroun, V.

    1984-11-13

    The present state of ion beam facilities for atomic physics research in the United States is assessed by means of a questionnaire and informal workshop. Recommendations for future facilities are given. 3 refs.

  8. Variational calculation of 4He tetramer ground and excited states using a realistic pair potential

    NASA Astrophysics Data System (ADS)

    Hiyama, E.; Kamimura, M.

    2012-02-01

    We calculated the 4He trimer and tetramer ground and excited states with the LM2M2 potential using our Gaussian expansion method for ab initio variational calculations of few-body systems. The method has been extensively used for a variety of three-, four-, and five-body systems in nuclear physics and exotic atomic and molecular physics. The trimer (tetramer) wave function is expanded in terms of symmetric three- (four-) body Gaussian basis functions, ranging from very compact to very diffuse, without assumption of any pair correlation function. The calculated results for the trimer ground and excited states are in excellent agreement with values reported in the literature. The binding energies of the tetramer ground and excited states are obtained as 558.98 and 127.33 mK (0.93 mK below the trimer ground state), respectively. We found that precisely the same shape of the short-range correlation (rij≲4 Å) in the dimer appears in the ground and excited states of the trimer and tetramer. The overlap function between the trimer excited state and the dimer ground state and that between the tetramer excited state and the trimer ground state are almost proportional to the dimer wave function in the asymptotic region (up to ˜1000 Å). Also, the pair correlation functions of trimer and tetramer excited states are almost proportional to the squared dimer wave function. We then propose a model which predicts the binding energy of the first excited state of 4HeN (N≥3) measured from the 4HeN-1 ground state to be nearly (N)/(2(N-1))B2 where B2 is the dimer binding energy.

  9. Solitons shedding from Airy beams and bound states of breathing Airy solitons in nonlocal nonlinear media

    PubMed Central

    Shen, Ming; Gao, Jinsong; Ge, Lijuan

    2015-01-01

    We investigate the spatially optical solitons shedding from Airy beams and anomalous interactions of Airy beams in nonlocal nonlinear media by means of direct numerical simulations. Numerical results show that nonlocality has profound effects on the propagation dynamics of the solitons shedding from the Airy beam. It is also shown that the strong nonlocality can support periodic intensity distribution of Airy beams with opposite bending directions. Nonlocality also provides a long-range attractive force between Airy beams, leading to the formation of stable bound states of both in-phase and out-of-phase breathing Airy solitons which always repel in local media. PMID:25900878

  10. Ground-state characterizations of systems predicted to exhibit L11 or L13 crystal structures

    NASA Astrophysics Data System (ADS)

    Nelson, Lance J.; Hart, Gus L. W.; Curtarolo, Stefano

    2012-02-01

    Despite their geometric simplicity, the crystal structures L11 (CuPt) and L13 (CdPt3) do not appear as ground states experimentally, except in Cu-Pt. We investigate the possibility that these phases are ground states in other binary intermetallic systems, but overlooked experimentally. Via the synergy between high-throughput and cluster-expansion computational methods, we conduct a thorough search for systems that may exhibit these phases and calculate order-disorder transition temperatures when they are predicted. High-throughput calculations predict L11 ground states in the systems Ag-Pd, Ag-Pt, Cu-Pt, Pd-Pt, Li-Pd, Li-Pt, and L13 ground states in the systems Cd-Pt, Cu-Pt, Pd-Pt, Li-Pd, Li-Pt. Cluster expansions confirm the appearance of these ground states in some cases. In the other cases, cluster expansion predicts unsuspected derivative superstructures as ground states. The order-disorder transition temperatures for all L11/L13 ground states were found to be sufficiently high that their physical manifestation may be possible.

  11. Exact ground states of large two-dimensional planar Ising spin glasses

    NASA Astrophysics Data System (ADS)

    Pardella, G.; Liers, F.

    2008-11-01

    Studying spin-glass physics through analyzing their ground-state properties has a long history. Although there exist polynomial-time algorithms for the two-dimensional planar case, where the problem of finding ground states is transformed to a minimum-weight perfect matching problem, the reachable system sizes have been limited both by the needed CPU time and by memory requirements. In this work, we present an algorithm for the calculation of exact ground states for two-dimensional Ising spin glasses with free boundary conditions in at least one direction. The algorithmic foundations of the method date back to the work of Kasteleyn from the 1960s for computing the complete partition function of the Ising model. Using Kasteleyn cities, we calculate exact ground states for huge two-dimensional planar Ising spin-glass lattices (up to 30002 spins) within reasonable time. According to our knowledge, these are the largest sizes currently available. Kasteleyn cities were recently also used by Thomas and Middleton in the context of extended ground states on the torus. Moreover, they show that the method can also be used for computing ground states of planar graphs. Furthermore, we point out that the correctness of heuristically computed ground states can easily be verified. Finally, we evaluate the solution quality of heuristic variants of the L. Bieche approach.

  12. Exact spin-cluster ground states in a mixed diamond chain

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    The mixed diamond chain is a frustrated Heisenberg chain composed of successive diamond-shaped units with two kinds of spins of magnitudes S and S/2 ( S : integer). Ratio λ of two exchange parameters controls the strength of frustration. With varying λ , the Haldane state and several spin-cluster states appear as the ground state. A spin-cluster state is a tensor product of exact local eigenstates of cluster spins. We prove that a spin-cluster state is the ground state in a finite interval of λ . For S=1 , we numerically determine the total phase diagram consisting of five phases.

  13. Protolytic dissociation of cyanophenols in ground and excited states in alcohol and water solutions

    NASA Astrophysics Data System (ADS)

    Szczepanik, Beata; Styrcz, Stanisław

    2011-08-01

    The effect of cyano substituents on acidity in ground and excited states of mono- and dicyanophenols was investigated. The equilibrium dissociation constants of 3,4-dicyanophenol in ground and lowest excited states in water solution and the change of these constants in the excited state during the transfer to the ground state for o-, m-, p-cyanophenol and 3,4-dicyanophenol in alcohol and water solutions were determined. It was shown that the cyano substitution increases the acidity of ortho-, meta- and dicyano-derivative in ground state in comparison to the phenol, which makes the anions of these derivatives appear in solutions from methanol to 1-butanol. In the excited state the acidity of investigated compounds changes significantly in comparison to the ground state. 3,4-Dicyanophenol is the strongest acid in the lowest excited singlet state, while p-cyanophenol is the weakest one in both alcohol and water solutions. The distribution of the electronic charge and dipole moments of all investigated cyanophenols in ground and excited states were determined on the basis of ab initio calculations using the GAMESS program.

  14. Slow ground state molecules from matrix isolation sublimation

    NASA Astrophysics Data System (ADS)

    Oliveira, A. N.; Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L.

    2014-12-01

    We describe the generation and properties of a cryogenic beam of 7Li2 dimers from sublimation of a neon matrix where lithium atoms have been implanted via laser ablation of solid precursors of metallic lithium or lithium hydride (LiH). Different sublimation regimes lead to pulsed molecular beams with different temperatures, densities and forward velocities. With laser absorption spectroscopy these parameters were measured using the molecular 7Li2 (R) transitions A1Σ u+(v\\prime =4,J\\prime =J\\prime\\prime +1) ≤ftarrow X 1Σ g+(v\\prime\\prime =0,J\\prime\\prime =0,1,3). In a typical regime, sublimating a matrix at 16 K, translational temperatures of 6-8 K with a drift velocity of 130 m s-1 in a free expanding pulsed beam with molecular density of 109 cm-3, averaged along the laser axis, were observed. Rotational temperatures around 5-7 K were obtained. In recent experiments we were able to monitor the atomic Li signal—in the D2 line—concomitantly with the molecular signal in order to compare them as a function of the number of ablation pulses. Based on the data and a simple model, we discuss the possibility that a fraction of these molecules are being formed in the matrix, by mating atoms from different ablation pulses, which would open up the way to formation of other more interesting and difficult molecules to be studied at low temperatures. Such a source of cryogenic molecules have possible applications encompassing fundamental physics tests, quantum information studies, cold collisions, chemistry, and trapping.

  15. Matrix elements for the ground-state to ground-state 2{nu}{beta}{sup -}{beta}{sup -} decay of Te isotopes in a hybrid model

    SciTech Connect

    Bes, D. R.; Civitarese, O.

    2010-01-15

    Theoretical matrix elements, for the ground-state to ground-state two-neutrino double-{beta}-decay mode (2{nu}{beta}{sup -}{beta}{sup -}gs->gs) of {sup 128,130}Te isotopes, are calculated within a formalism that describes interactions between neutrons in a superfluid phase and protons in a normal phase. The elementary degrees of freedom of the model are proton-pair modes and pairs of protons and quasineutrons. The calculation is basically a parameter-free one, because all relevant parameters are fixed from the phenomenology. A comparison with the available experimental data is presented.

  16. Off-diagonal long-range order (ODLRO) and ground state properties of liquid helium

    SciTech Connect

    Rodriguez-Gomez, J.R.

    1983-01-01

    An independent calculation of the condensate fraction and the ground state energy of liquid helium is given. The Froehlich ansatz for the second reduced density matrix in conjunction with the ODLORO hypothesis for liquid helium below the critical temperature is used. Froehlich's ansatz is shown to be consistent with numerical calculations of the ground state properties of liquid helium. The ground state energy was -5.10/sup 0/K, close to the experimental value. The condensate fraction turned out to be about 10% which is within the margin of error of recent neutron scattering experiments and agrees with other theoretical calculations.

  17. Ground state properties of superheavy nuclei with Z=117 and Z=119

    SciTech Connect

    Ren Zhongzhou; Chen Dinghan; Xu Chang

    2006-11-02

    We review the current studies on the ground-state properties of superheavy nuclei. It is shown that there is shape coexistence for the ground state of many superheavy nuclei from different models and many superheavy nuclei are deformed. This can lead to the existence of isomers in superheavy region and it plays an important role for the stability of superheavy nuclei. Some new results on Z=117 and Z=119 isotopes are presented. The agreement between theoretical results and experimental data clearly demonstrates the validity of theoretical models for the ground-state properties of superheavy nuclei.

  18. A molecular-field approximation for quantum crystals. Ph.D. Thesis; [considering ground state properties

    NASA Technical Reports Server (NTRS)

    Danilowicz, R.

    1973-01-01

    Ground-state properties of quantum crystals have received considerable attention from both theorists and experimentalists. The theoretical results have varied widely with the Monte Carlo calculations being the most successful. The molecular field approximation yields ground-state properties which agree closely with the Monte Carlo results. This approach evaluates the dynamical behavior of each pair of molecules in the molecular field of the other N-2 molecules. In addition to predicting ground-state properties that agree well with experiment, this approach yields data on the relative importance of interactions of different nearest neighbor pairs.

  19. Degenerated ground-states in a spin chain with pair interactions: a characterization by symbolic dynamics

    NASA Astrophysics Data System (ADS)

    Corona, L. A.; Salgado-García, R.

    2016-12-01

    In this paper we study a class of one-dimensional spin chain having a highly degenerated set of ground-state configurations. The model consists of spin chain having infinite-range pair interactions with a given structure. We show that the set of ground-state configurations of such a model can be fully characterized by means of symbolic dynamics. Particularly we found that the set ground-state configurations define what in symbolic dynamics is called sofic shift space. Finally we prove that this system has a non-vanishing residual entropy (the topological entropy of the shift space), which can be exactly calculated.

  20. Theoretical Study of Tautomerization Reactions for the Ground and First Excited Electronic States of Adenine

    NASA Technical Reports Server (NTRS)

    Salter, Latasha M.; Chaban, Galina M.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Geometrical structures and energetic properties for different tautomers of adenine are calculated in this study, using multi-configurational wave functions. Both the ground and the lowest singlet excited state potential energy surfaces are studied. Four tautomeric forms are considered, and their energetic order is found to be different on the ground and the excited state potential energy surfaces. Minimum energy reaction paths are obtained for hydrogen atom transfer (tautomerization) reactions in the ground and the lowest excited electronic states. It is found that the barrier heights and the shapes of the reaction paths are different for the ground and the excited electronic states, suggesting that the probability of such tautomerization reaction is higher on the excited state potential energy surface. This tautomerization process should become possible in the presence of water or other polar solvent molecules and should play an important role in the photochemistry of adenine.

  1. Ground-state energies of the nonlinear sigma model and the Heisenberg spin chains

    NASA Technical Reports Server (NTRS)

    Zhang, Shoucheng; Schulz, H. J.; Ziman, Timothy

    1989-01-01

    A theorem on the O(3) nonlinear sigma model with the topological theta term is proved, which states that the ground-state energy at theta = pi is always higher than the ground-state energy at theta = 0, for the same value of the coupling constant g. Provided that the nonlinear sigma model gives the correct description for the Heisenberg spin chains in the large-s limit, this theorem makes a definite prediction relating the ground-state energies of the half-integer and the integer spin chains. The ground-state energies obtained from the exact Bethe ansatz solution for the spin-1/2 chain and the numerical diagonalization on the spin-1, spin-3/2, and spin-2 chains support this prediction.

  2. Ground-state energies of the nonlinear sigma model and the Heisenberg spin chains

    NASA Technical Reports Server (NTRS)

    Zhang, Shoucheng; Schulz, H. J.; Ziman, Timothy

    1989-01-01

    A theorem on the O(3) nonlinear sigma model with the topological theta term is proved, which states that the ground-state energy at theta = pi is always higher than the ground-state energy at theta = 0, for the same value of the coupling constant g. Provided that the nonlinear sigma model gives the correct description for the Heisenberg spin chains in the large-s limit, this theorem makes a definite prediction relating the ground-state energies of the half-integer and the integer spin chains. The ground-state energies obtained from the exact Bethe ansatz solution for the spin-1/2 chain and the numerical diagonalization on the spin-1, spin-3/2, and spin-2 chains support this prediction.

  3. Molecular spectroscopy for producing ultracold ground-state NaRb molecules

    NASA Astrophysics Data System (ADS)

    Wang, Dajun; Guo, Mingyang; Zhu, Bing; Lu, Bo; Ye, Xin; Wang, Fudong; Vexiau, Romain; Bouloufa-Maafa, Nadia; Quéméner, Goulven; Dulieu, Olivier

    2016-05-01

    Recently, we have successfully created an ultracold sample of absolute ground-state NaRb molecules by two-photon Raman transfer of weakly bound Feshbach molecules. Here we will present the detailed spectroscopic investigations on both the excited and the rovibrational ground states for finding the two-photon path. For the excited state, we focus on the A1Σ+ /b3 Π singlet and triplet admixture. We discovered an anomalously strong coupling between the Ω =0+ and 0- components which renders efficient population transfer possible. In the ground state, the pure nuclear hyperfine levels have been clearly resolved, which allows us to create molecules in the absolute ground state directly with Raman transfer. This work is jointly supported by Agence Nationale de la Recherche (#ANR-13- IS04-0004-01) and Hong Kong Research Grant Council (#A-CUHK403/13) through the COPOMOL project.

  4. Electronic excitation of ground state atoms by collision with heavy gas particles

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1993-01-01

    point where the initial and final potentials cross, or at least come very close. Therefore, this mechanism would be applicable to the case where a gas is initially at very low temperature suddenly subjected to high energy heavy particle bombardment. This situation would model the measurement of excitation cross section by molecular beam techniques, for example. The purpose is to report values of cross sections and rate coefficients for collision excitation of ground state atoms estimated with the Landau-Zener transition theory and to compare results with measurement of excitation cross sections for a beam of Hydrogen atoms impacting Argon atom targets. Some very dubious approximations are used, and the comparison with measurement is found less than ideal, but results are at least consistent within order of magnitude. The same model is then applied to the case of N-N atom collisions, even though the approximations then become even more doubtful. Still the rate coefficients obtained are at least plausible in both magnitude and functional form, and as far as I am aware these are the only estimates available for such rate coefficients.

  5. Explaining the Temperature Dependence of Spirilloxanthin’s S* Signal by an Inhomogeneous Ground State Model

    PubMed Central

    2013-01-01

    We investigate the nature of the S* excited state in carotenoids by performing a series of pump–probe experiments with sub-20 fs time resolution on spirilloxanthin in a polymethyl-methacrylate matrix varying the sample temperature. Following photoexcitation, we observe sub-200 fs internal conversion of the bright S2 state into the lower-lying S1 and S* states, which in turn relax to the ground state on a picosecond time scale. Upon cooling down the sample to 77 K, we observe a systematic decrease of the S*/S1 ratio. This result can be explained by assuming two thermally populated ground state isomers. The higher lying one generates the S* state, which can then be effectively frozen out by cooling. These findings are supported by quantum chemical modeling and provide strong evidence for the existence and importance of ground state isomers in the photophysics of carotenoids. PMID:23577754

  6. Ground and excited state dipole moments of coumarin 337 laser dye

    NASA Astrophysics Data System (ADS)

    Raikar, U. S.; Tangod, V. B.; Mannopantar, S. R.; Mastiholi, B. M.

    2010-11-01

    This paper reports that the effects of spectral properties of coumarin 337 laser dye have been investigated in different solvents considering solvent parameters like dielectric constant ( є) and refractive index ( n) of different solvent polarities. The ground state ( μg) and excited state ( μe) dipole moments are calculated using Lippert's, Bakhshiev's, and Kawski-Chamma-Viallet's equations. In all these three equations the variation of Stokes shift was used to calculate the excited state ( μe) dipole moment. It is observed that the Bakhshiev method is comparatively better than the other two methods for ground state and excited state dipole moment calculations. The angle between the excited state and ground state dipole moments is also calculated.

  7. Estimation of ground and excited state dipole moments of some laser dyes

    NASA Astrophysics Data System (ADS)

    Biradar, D. S.; Siddlingeshwar, B.; Hanagodimath, S. M.

    2008-03-01

    The ground state ( μg) and the excited state ( μe) dipole moments of three laser dyes namely 2, 5-diphenyl-1, 3, 4- oxadiazole (PPD), 2, 2″-dimethyl-p-terphenyl (DMT) and 1, 3-diphenyl benzene (MT) were studied at room temperature in various solvents. The ground state dipole moments ( μg) of all the three laser dyes were determined experimentally by Guggenheim method. The excited state dipole moments ( μe) were estimated from Lippert's, Bakshiev's and Chamma Viallet's equations by using the variation of the Stokes shift with the solvent dielectric constant and refractive index. Ground and excited state dipole moments were evaluated by means of solvatochromic shift method and also the excited state dipole moments are determined in combination with ground state dipole moments. It was observed that dipole moment values of excited states ( μe) were higher than corresponding ground state values ( μg), indicating a substantial redistribution of the π-electron densities in a more polar excited state for all the dyes investigated.

  8. Switching between ground and excited states by optical feedback in a quantum dot laser diode

    SciTech Connect

    Virte, Martin; Breuer, Stefan; Sciamanna, Marc; Panajotov, Krassimir

    2014-09-22

    We demonstrate switching between ground state and excited state emission in a quantum-dot laser subject to optical feedback. Even though the solitary laser emits only from the excited state, we can trigger the emission of the ground state by optical feedback. We observe recurrent but incomplete switching between the two emission states by variation of the external cavity length in the sub-micrometer scale. We obtain a good qualitative agreement of experimental results with simulation results obtained by a rate equation that accounts for the variations of the feedback phase.

  9. Ground-based and space-based laser beam power applications

    SciTech Connect

    Bozek, J.M.

    1995-02-01

    A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth`s surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances from the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

  10. Ground-Based and Space-Based Laser Beam Power Applications

    NASA Technical Reports Server (NTRS)

    Bozek, John M.

    1995-01-01

    A space power system based on laser beam power is sized to reduce mass, increase operational capabilities, and reduce complexity. The advantages of laser systems over solar-based systems are compared as a function of application. Power produced from the conversion of a laser beam that has been generated on the Earth's surface and beamed into cislunar space resulted in decreased round-trip time for Earth satellite electric propulsion tugs and a substantial landed mass savings for a lunar surface mission. The mass of a space-based laser system (generator in space and receiver near user) that beams down to an extraterrestrial airplane, orbiting spacecraft, surface outpost, or rover is calculated and compared to a solar system. In general, the advantage of low mass for these space-based laser systems is limited to high solar eclipse time missions at distances inside Jupiter. The power system mass is less in a continuously moving Mars rover or surface outpost using space-based laser technology than in a comparable solar-based power system, but only during dust storm conditions. Even at large distances for the Sun, the user-site portion of a space-based laser power system (e.g., the laser receiver component) is substantially less massive than a solar-based system with requisite on-board electrochemical energy storage.

  11. Ground-state properties of hcp helium-4 on the basis of a cell model

    NASA Technical Reports Server (NTRS)

    Jacobi, N.; Zmuidzinas, J. S.

    1977-01-01

    A simple cell model is used to compute the ground-state energy and the volume-pressure relation for hcp He-4, in good agreement with experiments and with more sophisticated quantum mechanical calculations.

  12. Analytic models for the density of a ground-state spinor condensate

    NASA Astrophysics Data System (ADS)

    Gautam, Sandeep; Adhikari, S. K.

    2015-08-01

    We demonstrate that the ground state of a trapped spin-1 and spin-2 spinor ferromagnetic Bose-Einstein condensate (BEC) can be well approximated by a single decoupled Gross-Pitaevskii (GP) equation. Useful analytic models for the ground-state densities of ferromagnetic BECs are obtained from the Thomas-Fermi approximation (TFA) to this decoupled equation. Similarly, for the ground states of spin-1 antiferromagnetic and spin-2 antiferromagnetic and cyclic BECs, some of the spin-component densities are zero, which reduces the coupled GP equation to a simple reduced form. Analytic models for ground-state densities are also obtained for antiferromagnetic and cyclic BECs from the TFA to the respective reduced GP equations. The analytic densities are illustrated and compared with the full numerical solution of the GP equation with realistic experimental parameters.

  13. Coherent structures in the ground state of the quantum Frenkel-Kontorova model

    SciTech Connect

    Berman, G.P.; Bulgakov, E.N. Kirensky Institute of Physics, Research Educational Center for Nonlinear Processes at Krasnoyarsk Technical University, Theoretical Department at Krasnoyarsk State University, 660036, Krasnoyarsk ); Campbell, D.K. )

    1994-03-15

    We study the quantum ground state of the Frenkel-Kontorova model in the strongly nonlinear'' regime in which in the corresponding classical limit the coordinates of the atoms are distributed on Cantori.'' We identify (many) quasidegenerate configurations that contribute to the quantum ground state. When the characteristic quantum and classical energy scales are roughly equal (the intermediate'' quantum regime), we find, consistent with earlier numerical studies, that the standard map'' determining the coordinates in the classical ground state is renormalized to an effective sawtooth'' map, which determines the expectation values of the coordinates in the quantum ground state. We also discuss the dynamics of the model and estimate the characteristic time for various quantum tunneling effects.

  14. Trajectory approach to the Schrödinger–Langevin equation with linear dissipation for ground states

    SciTech Connect

    Chou, Chia-Chun

    2015-11-15

    The Schrödinger–Langevin equation with linear dissipation is integrated by propagating an ensemble of Bohmian trajectories for the ground state of quantum systems. Substituting the wave function expressed in terms of the complex action into the Schrödinger–Langevin equation yields the complex quantum Hamilton–Jacobi equation with linear dissipation. We transform this equation into the arbitrary Lagrangian–Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation is simultaneously integrated with the trajectory guidance equation. Then, the computational method is applied to the harmonic oscillator, the double well potential, and the ground vibrational state of methyl iodide. The excellent agreement between the computational and the exact results for the ground state energies and wave functions shows that this study provides a synthetic trajectory approach to the ground state of quantum systems.

  15. Ground-state properties of hcp helium-4 on the basis of a cell model

    NASA Technical Reports Server (NTRS)

    Jacobi, N.; Zmuidzinas, J. S.

    1977-01-01

    A simple cell model is used to compute the ground-state energy and the volume-pressure relation for hcp He-4, in good agreement with experiments and with more sophisticated quantum mechanical calculations.

  16. Ground-state information geometry and quantum criticality in an inhomogeneous spin model

    NASA Astrophysics Data System (ADS)

    Ma, Yu-Quan

    2015-09-01

    We investigate the ground-state Riemannian metric and the cyclic quantum distance of an inhomogeneous quantum spin-1/2 chain in a transverse field. This model can be diagonalized by using a general canonical transformation to the fermionic Hamiltonian mapped from the spin system. The ground-state Riemannian metric is derived exactly on a parameter manifold ring S1, which is introduced by performing a gauge transformation to the spin Hamiltonian through a twist operator. The cyclic ground-state quantum distance and the second derivative of the ground-state energy are studied in different exchange coupling parameter regions. Particularly, we show that, in the case of exchange coupling parameter Ja = Jb, the quantum ferromagnetic phase can be characterized by an invariant quantum distance and this distance will decay to zero rapidly in the paramagnetic phase. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404023 and 11347131).

  17. Features of simultaneous ground- and excited-state lasing in quantum dot lasers

    SciTech Connect

    Zhukov, A. E. Maximov, M. V.; Shernyakov, Yu. M.; Livshits, D. A.; Savelyev, A. V.; Zubov, F. I.; Klimenko, V. V.

    2012-02-15

    The lasing spectra and light-current (L-I) characteristics of an InAs/InGaAs quantum dot laser emitting in the simultaneous lasing mode at the ground- and excited-state optical transitions are studied. Lasing and spontaneous emission spectra are compared. It is shown that ground-state quenching of lasing is observed even in the absence of active region self-heating or an increase in homogeneous broadening with growth in the current density. It is found that the intensities of both lasing and spontaneous emission at the ground-state transition begin to decrease at a pump intensity that significantly exceeds the two-level lasing threshold. It is also found that different groups of quantum dots are involved in ground- and excited-state lasing.

  18. Mass coefficient and Grodzins relation for the ground-state band and {gamma} band

    SciTech Connect

    Jolos, R. V.; Brentano, P. von

    2006-12-15

    It is shown that the available experimental data on the energies of the first and the {gamma}-vibrational 2{sup +} states and the reduced E2 transition probabilities from these states to the ground state require for the explanation significantly different values of the mass coefficients for the rotational motion and {gamma}-vibrations.

  19. Expectation values of single-particle operators in the random phase approximation ground state.

    PubMed

    Kosov, D S

    2017-02-07

    We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.

  20. Ground state properties of solid and liquid spin-aligned atomic hydrogen

    NASA Technical Reports Server (NTRS)

    Danilowicz, R. L.; Dugan, J. V., Jr.; Etters, R. D.

    1976-01-01

    Calculations of the ground state energy in the solid phase were performed with the aid of a variational approach. The Morse potential form of the atomic triple potential computed by Kolos and Wolniewicz (1965) was employed for the calculations. The ground state energies of both the liquid and solid phases of spin-aligned atomic hydrogen around the volume of the transition are presented in a graph.

  1. The impact of bonded interactions on the ground-state geometries of a small flexible polymer

    NASA Astrophysics Data System (ADS)

    Koci, Tomas; Qi, Kai; Bachmann, Michael

    2016-10-01

    Bonded interactions in coarse-grained models of elastic polymers are commonly represented by the finitely extensible nonlinear elastic (FENE) potential. In this study, we perform parallel multicanonical Monte Carlo simulations to examine the impact of an additional Lennard-Jones term in the bonded potential on the geometry of ground-state structures of a short polymer. Employing microcanonical inflection point analysis and conformational analysis, we construct a hyper-phase diagram and identify ground-state structures with two distinct geometries.

  2. Expectation values of single-particle operators in the random phase approximation ground state

    NASA Astrophysics Data System (ADS)

    Kosov, D. S.

    2017-02-01

    We developed a method for computing matrix elements of single-particle operators in the correlated random phase approximation ground state. Working with the explicit random phase approximation ground state wavefunction, we derived a practically useful and simple expression for a molecular property in terms of random phase approximation amplitudes. The theory is illustrated by the calculation of molecular dipole moments for a set of representative molecules.

  3. Molecular beam study of the a 3Σ+ state of NaK up to the dissociation limit

    NASA Astrophysics Data System (ADS)

    Temelkov, I.; Knöckel, H.; Pashov, A.; Tiemann, E.

    2015-03-01

    We provide spectroscopic data for the a 3Σ+ state of the 23Na39K molecule. The experiment is done in an ultrasonic beam apparatus, starting from the ground state X 1Σ+and driving the population to the a 3Σ+ state, using a Λ scheme with fixed pump and scanning dump laser. The signals are observed as dips of the total fluorescence. The intermediate level is chosen to be strongly perturbed by the B 1Π/c 3Σ+ states mixing to overcome the singlet-triplet transfer prohibition. We observed highly resolved hyperfine spectra of various rovibrational levels of the a 3Σ+state from va=2 up to the highest vibrational levels for rotational quantum numbers Na=4 ,6 ,8 . By the typical experimental linewidth of 17 MHz, the vibrational dependence of the hyperfine splitting is clearly revealed for NaK. The absolute frequency measurements of the vibrational levels are used for improvement of the a 3Σ+ potential curve and of the derived scattering length of all natural isotope combinations. Applying the Λ scheme in the reverse direction can provide a pathway for efficient transfer of ultracold 23Na39K molecules from the Na(3 s )+K(4 s ) asymptote to the lowest levels of the ground state. We show spectra that couple the absolute ground state vX=0 ,J =0 with an appropriate intermediate state for direct realization of the reverse path. The refined theoretical model of the coupled excited states of the Na(3 s )+K(4 p ) asymptote allows predictions of efficient paths for 23Na40K ; one example is calculated.

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

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2014-11-01

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

  5. Ground states of the Ising model on an anisotropic triangular lattice: stripes and zigzags.

    PubMed

    Dublenych, Yu I

    2013-10-09

    A complete solution of the ground-state problem for the Ising model on an anisotropic triangular lattice with the nearest-neighbor interactions in a magnetic field is presented. It is shown that this problem can be reduced to the ground-state problem for an infinite chain with the interactions up to the second neighbors. In addition to the known ground-state structures (which correspond to full-dimensional regions in the parameter space of the model), new structures are found (at the boundaries of these regions), in particular, zigzagging stripes similar to those observed experimentally in colloidal monolayers. Though the number of parameters is relatively large (four), all the ground-state structures of the model are constructed and analyzed and therefore the paper can be considered as an example of a complete solution of a ground-state problem for classical spin or lattice-gas models. The paper can also help to verify the correctness of some results obtained previously by other authors and concerning the ground states of the model under consideration.

  6. Quasi-Bessel beams with longitudinally varying polarization state generated by employing spectrum engineering.

    PubMed

    Li, Peng; Zhang, Yi; Liu, Sheng; Han, Lei; Cheng, Huachao; Yu, Fan; Zhao, Jianlin

    2016-10-15

    We report on the generation and control of quasi-Bessel beams having not only a uniform axial intensity but also a longitudinally varying polarization state. Based on the optimization routine of the spatial spectrum of the so-called Durnin ring, we generate quasi-Bessel beams possessing longitudinally variant axial intensity with linear or sinusoidal envelopes. By utilizing a Sagnac interferometer, we create and coaxially composite two orthogonally polarized beams with complementary axial intensities to form quasi-Bessel beams with uniform axial intensity but a longitudinally varying polarization state. Furthermore, we demonstrate the possibility and flexibility of manipulating the trajectory, speed, and period of polarization state transformation upon propagation. Our results may enable Bessel beams to be used in other applications including optical communications, material processing, and polarimetry.

  7. Fuzzy analysis of serviceability limit state of slender steel beam under bending

    SciTech Connect

    Kala, Zdeněk; Valeš, Jan

    2015-03-10

    In the present paper, deformations of a beam under equal end moments solved with influence of lateral buckling are studied. It has been found by numerical studies that the lateral deflection of slender beam under major axis bending can be relatively high.The acceptability of high values of lateral deflections within the framework of serviceability limit state is discussed. In the next part of the paper, the limit value of maximum deflection was introduced as a fuzzy number. The fuzzy analysis of the maximum moment which causes the maximum deflection was carried out. The slendernesses of beams for which the serviceability limit state is the limiting state for design were identified.

  8. Discrete-Gauss states and the generation of focusing dark beams

    NASA Astrophysics Data System (ADS)

    Ferrando, Albert

    2014-08-01

    Discrete-Gauss states are a new class of Gaussian solutions of the free Schrödinger equation owning discrete rotational symmetry. They are obtained by acting with a discrete deformation operator onto Laguerre-Gauss modes. We present a general analytical construction of these states and show the necessary and sufficient condition for them to host embedded dark beam structures. We unveil the intimate connection between discrete rotational symmetry, orbital angular momentum, and the generation of focusing dark beams. The distinguishing features of focusing dark beams are discussed. The potential applications of discrete-Gauss states in advanced optical trapping and quantum information processing are also briefly discussed.

  9. Relativistic configuration interaction calculation on the ground and excited states of iridium monoxide

    SciTech Connect

    Suo, Bingbing; Yu, Yan-Mei; Han, Huixian

    2015-03-07

    We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for Ω = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of Ω = 1/2, which is highly mixed with {sup 4}Σ{sup −} and {sup 2}Π states in Λ − S notation. The two low-lying states 5/2 and 7/2 are nearly degenerate with the ground state and locate only 234 and 260 cm{sup −1} above, respectively. The equilibrium bond length 1.712 Å and the harmonic vibrational frequency 903 cm{sup −1} of the 5/2 state are close to the experimental measurement of 1.724 Å and 909 cm{sup −1}, which suggests that the 5/2 state should be the low-lying state that contributes to the experimental spectra. Moreover, the electronic states that give rise to the observed transition bands are assigned for Ω = 5/2 and 7/2 in terms of the obtained excited energies and oscillator strengths.

  10. Number-conserving interacting fermion models with exact topological superconducting ground states

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyuan; Xu, Youjiang; Pu, Han; Hazzard, Kaden R. A.

    2017-09-01

    We present a method to construct number-conserving Hamiltonians whose ground states exactly reproduce an arbitrarily chosen BCS-type mean-field state. Such parent Hamiltonians can be constructed not only for the usual s -wave BCS state, but also for more exotic states of this form, including the ground states of Kitaev wires and two-dimensional topological superconductors. This method leads to infinite families of locally interacting fermion models with exact topological superconducting ground states. After explaining the general technique, we apply this method to construct two specific classes of models. The first one is a one-dimensional double wire lattice model with Majorana-like degenerate ground states. The second one is a two-dimensional px+i py superconducting model, where we also obtain analytic expressions for topologically degenerate ground states in the presence of vortices. Our models may provide a deeper conceptual understanding of how Majorana zero modes could emerge in condensed matter systems, as well as inspire novel routes to realize them in experiment.

  11. Determination of the polarization states of an arbitrary polarized terahertz beam: Vectorial vortex analysis

    PubMed Central

    Wakayama, Toshitaka; Higashiguchi, Takeshi; Oikawa, Hiroki; Sakaue, Kazuyuki; Washio, Masakazu; Yonemura, Motoki; Yoshizawa, Toru; Tyo, J. Scott; Otani, Yukitoshi

    2015-01-01

    Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1–1.6 THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of Δ = 163° and are made of polytetrafluorethylene. Polarized THz beams are converted into THz vectorial vortex beams with no spatial or wavelength dispersion, and the unknown polarization states of the incident THz beams are reconstructed. The polarization determination is also demonstrated at frequencies of 0.16 and 0.36 THz. The results obtained by solving the inverse source problem agree with the values used in the experiments. This vectorial vortex analysis enables a determination of the polarization states of the incident THz beam from the THz image. The polarization states of the beams are estimated after they pass through the TAS plates. The results validate this new approach to polarization detection for intense THz sources. It could find application in such cutting edge areas of physics as nonlinear THz photonics and plasmon excitation, because TAS plates not only instantaneously elucidate the polarization of an enclosed THz beam but can also passively control THz vectorial vortex beams. PMID:25799965

  12. Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings

    PubMed Central

    Zheng, Shuang; Wang, Jian

    2017-01-01

    Measuring orbital angular momentum (OAM) states of vortex beams is of great importance in diverse applications employing OAM-carrying vortex beams. We present a simple and efficient scheme to measure OAM states (i.e. topological charge values) of vortex beams with annular gratings. The magnitude of the topological charge value is determined by the number of dark fringes after diffraction, and the sign of the topological charge value is distinguished by the orientation of the diffraction pattern. We first theoretically study the diffraction patterns using both annular amplitude and phase gratings. The annular phase grating shows almost 10-dB better diffraction efficiency compared to the annular amplitude grating. We then experimentally demonstrate the OAM states measurement of vortex beams using annular phase grating. The scheme works well even for high-order vortex beams with topological charge value as high as ± 25. We also experimentally show the evolution of diffraction patterns when slightly changing the fractional topological charge value of vortex beam from 0.1 to 1.0. In addition, the proposed scheme shows potential large tolerance of beam alignment during the OAM states measurement of vortex beams. PMID:28094325

  13. Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings.

    PubMed

    Zheng, Shuang; Wang, Jian

    2017-01-17

    Measuring orbital angular momentum (OAM) states of vortex beams is of great importance in diverse applications employing OAM-carrying vortex beams. We present a simple and efficient scheme to measure OAM states (i.e. topological charge values) of vortex beams with annular gratings. The magnitude of the topological charge value is determined by the number of dark fringes after diffraction, and the sign of the topological charge value is distinguished by the orientation of the diffraction pattern. We first theoretically study the diffraction patterns using both annular amplitude and phase gratings. The annular phase grating shows almost 10-dB better diffraction efficiency compared to the annular amplitude grating. We then experimentally demonstrate the OAM states measurement of vortex beams using annular phase grating. The scheme works well even for high-order vortex beams with topological charge value as high as ± 25. We also experimentally show the evolution of diffraction patterns when slightly changing the fractional topological charge value of vortex beam from 0.1 to 1.0. In addition, the proposed scheme shows potential large tolerance of beam alignment during the OAM states measurement of vortex beams.

  14. Measuring Orbital Angular Momentum (OAM) States of Vortex Beams with Annular Gratings

    NASA Astrophysics Data System (ADS)

    Zheng, Shuang; Wang, Jian

    2017-01-01

    Measuring orbital angular momentum (OAM) states of vortex beams is of great importance in diverse applications employing OAM-carrying vortex beams. We present a simple and efficient scheme to measure OAM states (i.e. topological charge values) of vortex beams with annular gratings. The magnitude of the topological charge value is determined by the number of dark fringes after diffraction, and the sign of the topological charge value is distinguished by the orientation of the diffraction pattern. We first theoretically study the diffraction patterns using both annular amplitude and phase gratings. The annular phase grating shows almost 10-dB better diffraction efficiency compared to the annular amplitude grating. We then experimentally demonstrate the OAM states measurement of vortex beams using annular phase grating. The scheme works well even for high-order vortex beams with topological charge value as high as ± 25. We also experimentally show the evolution of diffraction patterns when slightly changing the fractional topological charge value of vortex beam from 0.1 to 1.0. In addition, the proposed scheme shows potential large tolerance of beam alignment during the OAM states measurement of vortex beams.

  15. State-to-state inelastic and reactive molecular beam scattering from surfaces

    SciTech Connect

    Lykke, K.R. ); Kay, B.D. )

    1990-01-01

    Resonantly enhanced multiphoton ionization (REMPI) laser spectroscopic and molecular beam-surface scattering techniques are coupled to study inelastic and reactive gas-surface scattering with state-to-state specificity. Rotational, vibrational, translational and angular distributions have been measured for the inelastic scattering of HCI and N {sub 2} from Au(111). In both cases the scattering is direct-inelastic in nature and exhibits interesting dynamical features such as rotational rainbow scattering. In an effort to elucidate the dynamics of chemical reactions occurring on surfaces we have extended our quantum-resolved scattering studies to include the reactive scattering of a beam of gas phase H-atoms from a chlorinated metal surface M-CI. The nascent rotational and vibrational distributions of the HCI product are determined using REMPI. The thermochemistry for this reaction on Au indicates that the product formation proceeding through chemisorbed H-atoms is slightly endothermic while direct reaction of a has phase H-atom with M-CI is highly exothermic (ca. 50 kcal/mole). Details of the experimental techniques, results and implications regarding the scattering dynamics are discussed. 55 ref., 8 fig.

  16. Modeling of an Adjustable Beam Solid State Light Project

    NASA Technical Reports Server (NTRS)

    Clark, Toni

    2015-01-01

    This proposal is for the development of a computational model of a prototype variable beam light source using optical modeling software, Zemax Optics Studio. The variable beam light source would be designed to generate flood, spot, and directional beam patterns, while maintaining the same average power usage. The optical model would demonstrate the possibility of such a light source and its ability to address several issues: commonality of design, human task variability, and light source design process improvements. An adaptive lighting solution that utilizes the same electronics footprint and power constraints while addressing variability of lighting needed for the range of exploration tasks can save costs and allow for the development of common avionics for lighting controls.

  17. Separating the Spin States of a Free Electron Beam

    NASA Astrophysics Data System (ADS)

    Rifkin, Neil

    2008-10-01

    In 1922 Otto Stern and Walther Gerlach set out to test the spacial quantization of the electron by passing a beam of neutral silver atoms through a transverse magnetic field. The interaction of the two projections of the electron's magnetic moment with the magnetic field resulted in a splitting of the beam. However, for some sixty years it was generally accepted that the spin of free electrons, and thus their magnetic moment, could not be measured with an experiment similar to that of Stern and Gerlach. The reason being that the lorentz force on charged particles is far greater than the force due to the magnetic moment of the electron, thus blurring any desired results. To reduce the lorentz force, the electrons could be passed through a magnetic field whose gradient is in the direction of the electrons' momentum. This longitudinal Stern-Gerlach device, with a superconducting magnet, could polarize the tails of a low energy electron beam.

  18. Equilibrium states and ground state of two-dimensional fluid foams

    SciTech Connect

    Graner, F.; Jiang, Y.; Janiaud, E.; Flament, C.

    2001-01-01

    We study the equilibrium energies of two-dimensional (2D) noncoarsening fluid foams, which consist of bubbles with fixed areas. The equilibrium states correspond to local minima of the total perimeter. We present a theoretical derivation of energy minima; experiments with ferrofluid foams, which can be either highly distorted, locally relaxed, or globally annealed; and Monte Carlo simulations using the extended large-Q Potts model. For a dry foam with small size variance we develop physical insight and an electrostatic analogy, which enables us to (i) find an approximate value of the global minimum perimeter, accounting for (small) area disorder, the topological distribution, and physical boundary conditions; (ii) conjecture the corresponding pattern and topology: small bubbles sort inward and large bubbles sort outward, topological charges of the same signs ''repel'' while charges of the opposite signs ''attract;'' (iii) define local and global markers to determine directly from an image how far a foam is from its ground state; (iv) conjecture that, in a local perimeter minimum at prescribed topology, the pressure distribution and thus the edge curvature are unique. Some results also apply to 3D foams.

  19. Sharing Common Ground: Texas and the Common Core State Standards

    ERIC Educational Resources Information Center

    Vasinda, Sheri; Grote-Garcia, Stephanie; Durham, Patricia

    2013-01-01

    When browsing through professional catalogs or attending national conferences, one cannot help but notice the growing emphasis on the Common Core State Standards (CCSS). So, what does this mean for Texas teachers? As part of a special four-part series in our Texas Journal of Literacy Education, a special task force from the TALE Board will share…

  20. Periodic ground state for the charged massive Schwinger model

    SciTech Connect

    Nagy, S.; Sailer, K.; Polonyi, J.

    2004-11-15

    It is shown that the charged massive Schwinger model supports a periodic vacuum structure for arbitrary charge density, similar to the common crystalline layout known in solid state physics. The dynamical origin of the inhomogeneity is identified in the framework of the bosonized model and in terms of the original fermionic variables.

  1. Ordered ground states of metallic hydrogen and deuterium

    NASA Technical Reports Server (NTRS)

    Ashcroft, N. W.

    1981-01-01

    The physical attributes of some of the more physically distinct ordered states of metallic hydrogen and metallic deuterium at T = 0 and nearby are discussed. The likelihood of superconductivity in both is considered with respect to the usual coupling via the density fluctuations of the ions.

  2. Ground state of Ho atoms on Pt(111) metal surfaces: Implications for magnetism

    NASA Astrophysics Data System (ADS)

    Karbowiak, M.; Rudowicz, C.

    2016-05-01

    We investigated the ground state of Ho atoms adsorbed on the Pt(111) surface, for which conflicting results exist. The density functional theory (DFT) calculations yielded the Ho ground state as | Jz=±8 > . Interpretation of x-ray absorption spectroscopy and x-ray magnetic circular dichroism spectra and the magnetization curves indicated the ground state as | Jz=±6 > . Superposition model is employed to predict the crystal-field (CF) parameters based on the structural data for the system Ho/Pt(111) obtained from the DFT modeling. Simultaneous diagonalization of the free-ion (HFI) and the trigonal CF Hamiltonian (HCF) within the whole configuration 4 f10 of H o3 + ion was performed. The role of the trigonal CF terms, neglected in the pure uniaxial CF model used previously for interpretation of experimental spectra, is found significant, whereas the sixth-rank CF terms may be neglected in agreement with the DFT predictions. The results provide substantial support for the experimental designation of the | Jz=±6 > ground state, albeit with subtle difference due to admixture of other | Jz> states, but run against the DFT-based designation of the | Jz=±8 > ground state. A subtle splitting of the ground energy level with the state (predominantly), | Jz=±6 > is predicted. This paper provides better insight into the single-ion magnetic behavior of the Ho/Pt(111) system by helping to resolve the controversy concerning the Ho ground state. Experimental techniques with greater resolution powers are suggested for direct confirmation of this splitting and C3 v symmetry experienced by the Ho atom.

  3. Ground-water recharge in humid areas of the United States: A summary of Ground-Water Resources Program studies, 2003-2006

    USGS Publications Warehouse

    Delin, Geoffrey N.; Risser, Dennis W.

    2007-01-01

    Increased demands on water resources by a growing population and recent droughts have raised awareness about the adequacy of ground-water resources in humid areas of the United States. The spatial and temporal variability of ground-water recharge are key factors that need to be quantified to determine the sustainability of ground-water resources. Ground-water recharge is defined herein as the entry into the saturated zone of water made available at the water-table surface, together with the associated flow away from the water table within the saturated zone (Freeze and Cherry, 1979). In response to the need for better estimates of ground-water recharge, the Ground-Water Resources Program (GWRP) of the U.S. Geological Survey (USGS) began an initiative in 2003 to estimate ground-water recharge rates in the relatively humid areas of the United States.

  4. Determination and Comparison of Carbonyl Stretching Frequency of a Ketone in Its Ground State and the First Electronic Excited State

    ERIC Educational Resources Information Center

    Bandyopadhyay, Subhajit; Roy, Saswata

    2014-01-01

    This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…

  5. Determination and Comparison of Carbonyl Stretching Frequency of a Ketone in Its Ground State and the First Electronic Excited State

    ERIC Educational Resources Information Center

    Bandyopadhyay, Subhajit; Roy, Saswata

    2014-01-01

    This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…

  6. Degenerate ground states and multiple bifurcations in a two-dimensional q-state quantum Potts model.

    PubMed

    Dai, Yan-Wei; Cho, Sam Young; Batchelor, Murray T; Zhou, Huan-Qiang

    2014-06-01

    We numerically investigate the two-dimensional q-state quantum Potts model on the infinite square lattice by using the infinite projected entangled-pair state (iPEPS) algorithm. We show that the quantum fidelity, defined as an overlap measurement between an arbitrary reference state and the iPEPS ground state of the system, can detect q-fold degenerate ground states for the Z_{q} broken-symmetry phase. Accordingly, a multiple bifurcation of the quantum ground-state fidelity is shown to occur as the transverse magnetic field varies from the symmetry phase to the broken-symmetry phase, which means that a multiple-bifurcation point corresponds to a critical point. A (dis)continuous behavior of quantum fidelity at phase transition points characterizes a (dis)continuous phase transition. Similar to the characteristic behavior of the quantum fidelity, the magnetizations, as order parameters, obtained from the degenerate ground states exhibit multiple bifurcation at critical points. Each order parameter is also explicitly demonstrated to transform under the Z_{q} subgroup of the symmetry group of the Hamiltonian. We find that the q-state quantum Potts model on the square lattice undergoes a discontinuous (first-order) phase transition for q=3 and q=4 and a continuous phase transition for q=2 (the two-dimensional quantum transverse Ising model).

  7. Type A verification report for the high flux beam reactor stack and grounds, Brookhaven National Laboratory, Upton, New York

    SciTech Connect

    Harpenau, Evan M.

    2012-01-13

    The U.S. Department of Energy (DOE) Order 458.1 requires independent verification (IV) of DOE cleanup projects (DOE 2011). The Oak Ridge Institute for Science and Education (ORISE) has been designated as the responsible organization for IV of the High Flux Beam Reactor (HFBR) Stack and Grounds area at Brookhaven National Laboratory (BNL) in Upton, New York. The IV evaluation may consist of an in-process inspection with document and data reviews (Type A Verification) or a confirmatory survey of the site (Type B Verification). DOE and ORISE determined that a Type A verification of the documents and data for the HFBR Stack and Grounds: Survey Units (SU) 6, 7, and 8 was appropriate based on the initial survey unit classification, the walkover surveys, and the final analytical results provided by the Brookhaven Science Associates (BSA). The HFBR Stack and Grounds surveys began in June 2011 and were completed in September 2011. Survey activities by BSA included gamma walkover scans and sampling of the as-left soils in accordance with the BSA Work Procedure (BNL 2010a). The Field Sampling Plan - Stack and Remaining HFBR Outside Areas (FSP) stated that gamma walk-over surveys would be conducted with a bare sodium iodide (NaI) detector, and a collimated detector would be used to check areas with elevated count rates to locate the source of the high readings (BNL 2010b). BSA used the Mult- Agency Radiation Survey and Site Investigation Manual (MARSSIM) principles for determining the classifications of each survey unit. Therefore, SUs 6 and 7 were identified as Class 1 and SU 8 was deemed Class 2 (BNL 2010b). Gamma walkover surveys of SUs 6, 7, and 8 were completed using a 2X2 NaI detector coupled to a data-logger with a global positioning system (GPS). The 100% scan surveys conducted prior to the final status survey (FSS) sampling identified two general soil areas and two isolated soil locations with elevated radioactivity. The general areas of elevated activity identified

  8. Making Classical Ground State Spin Computing Fault-Tolerant

    DTIC Science & Technology

    2010-06-24

    teleportation ,” Phys. Rev. A, 70 (2004). [15] D. Aharonov, W. van Dam, J. Kempe, Z. Landau, S. Lloyd, and O. Regev, “Adiabatic quantum computation is equiv...Adiabatic gate teleportation ,” Phys. Rev. Lett., 103, 120504 (2009). [25] D. Bacon and S. T. Flammia, “Adiabatic cluster state quantum computing...is relevant to quantum dot cellular automata as well as to recent universal adiabatic quantum computing constructions. In its most primitive form

  9. Entanglement generation from deformed spin coherent states using a beam splitter

    NASA Astrophysics Data System (ADS)

    Berrada, K.; El Baz, M.; Saif, F.; Hassouni, Y.; Mnia, S.

    2009-07-01

    Using the linear entropy as a measure of entanglement, we investigate the effect of a beam splitter on the Perelomov coherent states for the q-deformed Uq(su(2)) algebra. We distinguish two cases: in the classical q → 1 limit, we find that the states become Glauber coherent states as the spin tends to infinity; whereas for q ≠ 1, the states, contrary to the earlier case, become entangled as they pass through a beam splitter. The entanglement strongly depends on the q-deformation parameter and the amplitude Z of the state.

  10. Beam splitting and entanglement: Generalized coherent states, group contraction, and the classical limit

    NASA Astrophysics Data System (ADS)

    Gerry, Christopher C.; Benmoussa, Adil

    2005-06-01

    Recently, Markham and Vedral [Phys. Rev. A 67, 042113 (2003)] investigated the effect of beam splitting on the spin, or SU(2), coherent states for a single mode field. The spin coherent state is a binomial coherent state related to the Holstein-Primakoff realization of the su(2) Lie algebra given in terms of a set of single mode bose annihilation and creation operators. Upon beam splitting, the ordinary (or Glauber) coherent states merely split into products of ordinary coherent states with reduced amplitudes without becoming entangled, as one would expect for a classical-like field. The above authors expected the spin coherent states to go over to the ordinary coherent states in the limit of high spin, j→∞ , and thus to become product states after beam splitting. But this expectation was not confirmed through numerical calculation of the entropy which, instead of going to zero, leveled off with increasing spin. In this paper we find similar behavior for SU(1,1) coherent states of the Perelomov type for large Bargman index k , but also find that the Barut-Girardello SU(1,1) coherent states appear to rapidly become product states after beam splitting for increasing k . We explain these results by showing that, in reality, neither the spin coherent states nor the Perelomov SU(1,1) coherent states go over to ordinary coherent states in the limits of large j or k , and that the Barut-Girardello coherent states merely go over to the vacuum in the large k limit. Finally, we examine the correct limiting procedure for obtaining separable states (i.e., products of coherent states) upon beam splitting by performing contractions of the su(2) and su(1,1) Lie algebras and of their associated coherent states.

  11. Beam splitting and entanglement: Generalized coherent states, group contraction, and the classical limit

    SciTech Connect

    Gerry, Christopher C.; Benmoussa, Adil

    2005-06-15

    Recently, Markham and Vedral [Phys. Rev. A 67, 042113 (2003)] investigated the effect of beam splitting on the spin, or SU(2), coherent states for a single mode field. The spin coherent state is a binomial coherent state related to the Holstein-Primakoff realization of the su(2) Lie algebra given in terms of a set of single mode bose annihilation and creation operators. Upon beam splitting, the ordinary (or Glauber) coherent states merely split into products of ordinary coherent states with reduced amplitudes without becoming entangled, as one would expect for a classical-like field. The above authors expected the spin coherent states to go over to the ordinary coherent states in the limit of high spin, j{yields}{infinity}, and thus to become product states after beam splitting. But this expectation was not confirmed through numerical calculation of the entropy which, instead of going to zero, leveled off with increasing spin. In this paper we find similar behavior for SU(1,1) coherent states of the Perelomov type for large Bargman index k, but also find that the Barut-Girardello SU(1,1) coherent states appear to rapidly become product states after beam splitting for increasing k. We explain these results by showing that, in reality, neither the spin coherent states nor the Perelomov SU(1,1) coherent states go over to ordinary coherent states in the limits of large j or k, and that the Barut-Girardello coherent states merely go over to the vacuum in the large k limit. Finally, we examine the correct limiting procedure for obtaining separable states (i.e., products of coherent states) upon beam splitting by performing contractions of the su(2) and su(1,1) Lie algebras and of their associated coherent states.

  12. Methods and Indicators for Assessment of Regional Ground-Water Conditions in the Southwestern United States

    USGS Publications Warehouse

    Tillman, Fred D; Leake, Stanley A.; Flynn, Marilyn E.; Cordova, Jeffrey T.; Schonauer, Kurt T.; Dickinson, Jesse E.

    2008-01-01

    Monitoring the status and trends in the availability of the Nation's ground-water supplies is important to scientists, planners, water managers, and the general public. This is especially true in the semiarid to arid southwestern United States where rapid population growth and limited surface-water resources have led to increased use of ground-water supplies and water-level declines of several hundred feet in many aquifers. Individual well observations may only represent aquifer conditions in a limited area, and wells may be screened over single or multiple aquifers, further complicating single-well interpretations. Additionally, changes in ground-water conditions may involve time scales ranging from days to many decades, depending on the timing of recharge, soil and aquifer properties, and depth to the water table. The lack of an easily identifiable ground-water property indicative of current conditions, combined with differing time scales of water-level changes, makes the presentation of ground-water conditions a difficult task, particularly on a regional basis. One approach is to spatially present several indicators of ground-water conditions that address different time scales and attributes of the aquifer systems. This report describes several methods and indicators for presenting differing aspects of ground-water conditions using water-level observations in existing data-sets. The indicators of ground-water conditions developed in this study include areas experiencing water-level decline and water-level rise, recent trends in ground-water levels, and current depth to ground water. The computer programs written to create these indicators of ground-water conditions and display them in an interactive geographic information systems (GIS) format are explained and results illustrated through analyses of ground-water conditions for selected alluvial basins in the Lower Colorado River Basin in Arizona.

  13. Beam charge and current neutralization of high-charge-state heavy ions

    SciTech Connect

    Logan, B.G.; Callahan, D.A.

    1997-10-29

    High-charge-state heavy-ions may reduce the accelerator voltage and cost of heavy-ion inertial fusion drivers, if ways can be found to neutralize the space charge of the highly charged beam ions as they are focused to a target in a fusion chamber. Using 2-D Particle-In- Cell simulations, we have evaluated the effectiveness of two different methods of beam neutralization: (1) by redistribution of beam charge in a larger diameter, preformed plasma in the chamber, and (2), by introducing a cold-electron-emitting source within the beam channel at the beam entrance into the chamber. We find the latter method to be much more effective for high-charge-state ions.

  14. Steady states of a diode with counterstreaming electron and positron beams

    SciTech Connect

    Ender, A. Ya.; Kuznetsov, V. I. Gruzdev, A. A.

    2016-10-15

    Steady states of a plasma layer with counterstreaming beams of oppositely charged particles moving without collisions in a self-consistent electric field are analyzed. The study is aimed at clarifying the mechanism of generation and reconstruction of pulsar radiation. Such a layer also models the processes occurring in Knudsen plasma diodes with counterstreaming electron and ion beams. The steady-state solutions are exhaustively classified. The existence of several solutions at the same external parameters is established.

  15. Exponentially Biased Ground-State Sampling of Quantum Annealing Machines with Transverse-Field Driving Hamiltonians

    NASA Astrophysics Data System (ADS)

    Mandrà, Salvatore; Zhu, Zheng; Katzgraber, Helmut G.

    2017-02-01

    We study the performance of the D-Wave 2X quantum annealing machine on systems with well-controlled ground-state degeneracy. While obtaining the ground state of a spin-glass benchmark instance represents a difficult task, the gold standard for any optimization algorithm or machine is to sample all solutions that minimize the Hamiltonian with more or less equal probability. Our results show that while naive transverse-field quantum annealing on the D-Wave 2X device can find the ground-state energy of the problems, it is not well suited in identifying all degenerate ground-state configurations associated with a particular instance. Even worse, some states are exponentially suppressed, in agreement with previous studies on toy model problems [New J. Phys. 11, 073021 (2009), 10.1088/1367-2630/11/7/073021]. These results suggest that more complex driving Hamiltonians are needed in future quantum annealing machines to ensure a fair sampling of the ground-state manifold.

  16. Towards Chemically Stable Fermionic Ground State Molecules with Strong Dipolar Interactions

    NASA Astrophysics Data System (ADS)

    Will, Sebastian; Park, Jee; Wu, Cheng-Hsun; Schloss, Jennifer; Zwierlein, Martin

    2013-05-01

    Quantum gases with dipolar interactions will open new avenues for the creation of novel quantum many-body systems with intriguing properties, ranging from crystalline over magnetic to topological phases. A promising route for the experimental realization of dipolar quantum gases is the formation of fermionic ground-state molecules with a large electric dipole moment, giving rise to long-range anisotropic interactions. With our experiment we work towards the realization of fermionic ground state molecules of 23Na40K. The NaK ground state molecule is chemically stable and possesses a large induced electric dipole moment of 2.72 Debye. In pioneering studies, we have created nearly degenerate samples of weakly bound 23Na40K Feshbach molecules. With a long lifetime and a significant admixture of the electronic spin singlet state, the Feshbach molecules are an ideal starting point to reach the singlet rovibrational ground state with a two-photon STIRAP transfer. Aiming for an efficient transfer path, we have performed spectroscopic studies on excited and ground state molecular potentials of 23Na40K and will report on our current progress. This work was supported by the NSF, AFOSR-MURI and -PECASE, ARO-MURI, ONR YIP, DARPA YFA, a grant from the Army Research Office with funding from the DARPA OLE program and the David and Lucille Packard Foundation.

  17. Two-Photon Pathway to Ultracold Fermionic Ground State Molecules of NaK

    NASA Astrophysics Data System (ADS)

    Park, Jee Woo; Schloss, Jennifer; Yan, Zoe; Loh, Huanqian; Will, Sebastian; Zwierlein, Martin

    2015-05-01

    Interactions beyond the simple contact interaction open up a new paradigm in the field of ultracold quantum gases. Fermionic ground state molecules with strong dipolar interactions serve as an ideal system to explore the rich physics of dipolar quantum gases with intriguing phenomena such as supersolidity and emergence of topological phases. Fermionic 23Na40K molecules are particularly well suited for this purpose. In their absolute ground state, these molecules are chemically stable and posses a large electric dipole moment of 2.72 Debye. In this talk, we report on a two-photon pathway to transfer loosely bound 23Na40K Feshbach molecules to the absolute ground state. We conducted high-resolution one- and two-photon spectroscopy of ultracold 23Na40K Feshbach molecules, and identified a pathway to the rovibrational singlet ground state via a resonantly mixed B1 Π ~c3Σ+ intermediate state. This pathway is used in our experiment to transfer loosely bound Feshbach molecules to the absolute ground state with high efficiency. Our work thus paves the way towards the creation of a strongly dipolar Fermi gas of chemically stable molecules.

  18. Exponentially Biased Ground-State Sampling of Quantum Annealing Machines with Transverse-Field Driving Hamiltonians.

    PubMed

    Mandrà, Salvatore; Zhu, Zheng; Katzgraber, Helmut G

    2017-02-17

    We study the performance of the D-Wave 2X quantum annealing machine on systems with well-controlled ground-state degeneracy. While obtaining the ground state of a spin-glass benchmark instance represents a difficult task, the gold standard for any optimization algorithm or machine is to sample all solutions that minimize the Hamiltonian with more or less equal probability. Our results show that while naive transverse-field quantum annealing on the D-Wave 2X device can find the ground-state energy of the problems, it is not well suited in identifying all degenerate ground-state configurations associated with a particular instance. Even worse, some states are exponentially suppressed, in agreement with previous studies on toy model problems [New J. Phys. 11, 073021 (2009)NJOPFM1367-263010.1088/1367-2630/11/7/073021]. These results suggest that more complex driving Hamiltonians are needed in future quantum annealing machines to ensure a fair sampling of the ground-state manifold.

  19. Ground-state configuration of neutron-rich 35Al via Coulomb breakup

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Datta, Ushasi; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chartier, M.; Cortina-Gil, D.; De Angelis, G.; Fernandez, P. Diaz; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Johansson, H.; Jonson, B.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, M. V.; Rigollet, C.; Rossi, D.; Scheidenberger, C.; Scheit, H.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Utsuno, Y.; Wagner, A.; Wamers, F.; Weick, H.; Winfield, J. S.

    2017-09-01

    The ground-state configuration of 35Al has been studied via Coulomb dissociation (CD) using the LAND-FRS setup (GSI, Darmstadt) at a relativistic energy of ˜403 MeV/nucleon. The measured inclusive differential CD cross section for 35Al, integrated up to 5.0 MeV relative energy between the 34Al core and the neutron using a Pb target, is 78(13) mb. The exclusive measured CD cross section that populates various excited states of 34Al is 29(7) mb. The differential CD cross section of 35Al→34Al+n has been interpreted in the light of a direct breakup model, and it suggests that the possible ground-state spin and parity of 35Al could be, tentatively, 1 /2+ or 3 /2+ or 5 /2+ . The valence neutrons, in the ground state of 35Al, may occupy a combination of either l =3 ,0 or l =1 ,2 orbitals coupled with the 34Al core in the ground and isomeric state(s), respectively. This hints of a particle-hole configuration of the neutron across the magic shell gaps at N =20 ,28 which suggests narrowing the magic shell gap. If the 5 /2+ is the ground-state spin-parity of 35Al as suggested in the literature, then the major ground-state configuration of 35Al is a combination of 34Al(g.s.;4-) ⊗νp3/2 and 34Al(isomer;1+) ⊗νd3/2 states. The result from this experiment has been compared with that from a previous knockout measurement and a calculation using the SDPF-M interaction.

  20. Ground State Destabilization by Anionic Nucleophiles Contributes to the Activity of Phosphoryl Transfer Enzymes

    PubMed Central

    Andrews, Logan D.; Fenn, Tim D.; Herschlag, Daniel

    2013-01-01

    Enzymes stabilize transition states of reactions while limiting binding to ground states, as is generally required for any catalyst. Alkaline Phosphatase (AP) and other nonspecific phosphatases are some of Nature's most impressive catalysts, achieving preferential transition state over ground state stabilization of more than 1022-fold while utilizing interactions with only the five atoms attached to the transferred phosphorus. We tested a model that AP achieves a portion of this preference by destabilizing ground state binding via charge repulsion between the anionic active site nucleophile, Ser102, and the negatively charged phosphate monoester substrate. Removal of the Ser102 alkoxide by mutation to glycine or alanine increases the observed Pi affinity by orders of magnitude at pH 8.0. To allow precise and quantitative comparisons, the ionic form of bound Pi was determined from pH dependencies of the binding of Pi and tungstate, a Pi analog lacking titratable protons over the pH range of 5–11, and from the 31P chemical shift of bound Pi. The results show that the Pi trianion binds with an exceptionally strong femtomolar affinity in the absence of Ser102, show that its binding is destabilized by ≥108-fold by the Ser102 alkoxide, and provide direct evidence for ground state destabilization. Comparisons of X-ray crystal structures of AP with and without Ser102 reveal the same active site and Pi binding geometry upon removal of Ser102, suggesting that the destabilization does not result from a major structural rearrangement upon mutation of Ser102. Analogous Pi binding measurements with a protein tyrosine phosphatase suggest the generality of this ground state destabilization mechanism. Our results have uncovered an important contribution of anionic nucleophiles to phosphoryl transfer catalysis via ground state electrostatic destabilization and an enormous capacity of the AP active site for specific and strong recognition of the phosphoryl group in the transition

  1. Complete Quantum State Selectivity in Cold Molecular Beams Using Deflection-Resistant Dark States in a STIRAP Configuration.

    PubMed

    Li, Xuan; Eilam, Asaf; Shapiro, Moshe

    2014-11-06

    One of the main goals of chemical dynamics is the creation of molecular beams composed of a single (vibrational, rotational, and magnetic) quantum state of choice. In this Letter, we propose a method to achieve complete quantum state selectivity by producing resistance to electromagnetically induced deflection (EID) and that the state to be selected can be "dialed in" at will. We illustrate the method by showing in detail how to purify thermal beams of the LiRb and IF molecules to yield molecular beams composed of a variety of prechosen single internal quantum states and/or superpositions of such states. We expect that this method will be implemented in all subsequent explorations of the fundamentals of chemical reactions and their control and the use of cold molecules as a vehicle for studying some of the most profound issues of quantum dynamics.

  2. Theoretical Calculations of XeF Ground State Kinetics.

    DTIC Science & Technology

    1988-03-01

    APPRVE FO PBC ELAE;AP 5981 This report was submitted by The Aerospace Corporation , El Segundo, CA 90245, under Contract No. F0701-85-C-0086-PO0016 with...the Space Division, P.O. Box 92960, Worldway Postal Center, Los Angeles, CA 90009-2960. It was reviewed and approved for The Aerospace Corporation by W...a. NAME OF MONITORING ORGANIZATION The Aerospace Corporation ( Space Division Laboratory Operations 6C. ADDRESS (Cly, State, and ZP Code) 7b ADDRESS

  3. Dimer-Monomer Ground State for Extended Spin-1/2 Diamond Chain

    NASA Astrophysics Data System (ADS)

    Takano, Ken'ichi

    2017-09-01

    We present a condition in which the dimer-monomer state is exactly the ground state of an extended diamond chain with spin magnitude 1/2. The Hamiltonian of the extended diamond chain includes next-nearest-neighbor exchange interactions and distortions, where the spin magnitude of the spin pair on a singlet dimer is not generally conserved. The method of deriving the condition is based on representing the Hamiltonian in a complete square form. The dimer-monomer ground state is found even if the Hamiltonian has no space-reflection symmetries.

  4. Ground state proton radioactivity from 121Pr: when was this exotic nuclear decay mode first discovered?

    PubMed

    Robinson, A P; Woods, P J; Seweryniak, D; Davids, C N; Carpenter, M P; Hecht, A A; Peterson, D; Sinha, S; Walters, W B; Zhu, S

    2005-07-15

    Ground-state proton radioactivity has been identified from 121Pr. A transition with a proton energy of E(p)=882(10) keV [Q(p)=900(10) keV] and half-life t(1/2)=10(+6)(-3) ms has been observed and is assigned to the decay of a highly prolate deformed 3/2(+) or 3/2(-) Nilsson state. The present result is found to be incompatible with a previously reported observation of ground-state proton radioactivity from 121Pr, which would have represented the discovery of this phenomenon.

  5. Exact many-electron ground states on the diamond Hubbard chain

    NASA Astrophysics Data System (ADS)

    Gulacsi, Zsolt; Kampf, Arno; Vollhardt, Dieter

    2008-03-01

    Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnetism, correlation induced metallic, half-metallic, or insulating behavior [1]. The properties of these ground states can be tuned by changing the magnetic flux, local potentials, or electron density.The results show that the studied simple one-dimensional structure displays remarkably complex physical properties. The virtue of tuning different ground states through external parameters points to new possibilities for the design of electronic devices which can switch between insulating or conducting and nonmagnetic or (fully or partially spin polarized) ferromagnetic states, open new routes for the design of spin-valve devices and gate induced ferromagnetism. [1] Z. Gulacsi, A. Kampf, D. Vollhardt, Phys. Rev. Lett. 99, 026404(2007).

  6. Correlations between ground and excited state spectra of a quantum Dot

    PubMed

    Stewart; Sprinzak; Marcus; Duruoz; Harris

    1997-12-05

    The ground and excited state spectra of a semiconductor quantum dot with successive electron occupancy were studied with linear and nonlinear magnetoconductance measurements. A direct correlation was observed between the mth excited state of the N-electron system and the ground state of the (N + m)-electron system for m up to 4. The results are consistent with a single-particle picture in which a fixed spectrum of energy levels is successively filled, except for a notable absence of spin degeneracy. Further departures from the single-particle picture due to electron-electron interaction were also observed. Magnetoconductance fluctuations of ground states show anticrossings where wave function characteristics are exchanged between adjacent levels.

  7. Fermionic Ground State Molecules NaK with Strong Dipolar Interactions

    NASA Astrophysics Data System (ADS)

    Park, Jee Woo; Schloss, Jennifer; Yan, Zoe; Loh, Huanqian; Will, Sebastian; Zwierlein, Martin

    2015-05-01

    23 Na40K is a fermionic molecule that is especially well suited for this purpose. In the rovibrational ground state, NaK molecules are chemically stable and possess a large electric dipole moment of 2.72 Debye. The poster will report on our progress at MIT that recently led us to the creation of the first dipolar ground state molecules of NaK, covering the formation of Feshbach molecules, spectroscopic investigation of the molecular structure of NaK as well as the successful coherent two-photon transfer of NaK to the absolute ground state. These advances bring the exploration of novel states of matter in strongly dipolar quantum matter within experimental reach.

  8. Short-range correlations in the magnetic ground state of Na4 Ir3 O8

    NASA Astrophysics Data System (ADS)

    Dally, Rebecca; Hogan, Tom; Amato, Alex; Luetkens, Hubertus; Baines, Chris; Rodriguez-Rivera, Jose; Graf, Michael; Wilson, Stephen

    2015-03-01

    The magnetic ground state of the candidate three-dimensional quantum spin liquid Na4 Ir3O8 has been studied through bulk magnetization, muon spin relaxation and neutron scattering measurements. Na4 Ir3O8 possesses a unique hyper-Kagome lattice of Ir moments that is potentially accompanied by a novel realization of Heisenberg-Kitaev exchange. This fact combined with the absence of previously reported magnetic ordering has led to its candidacy as a three-dimensional quantum spin liquid. Our combined experimental data show that a short-range, frozen, ground state comprised of quasi-static moments develops in this material below a characteristic temperature TF = 6 K , persisting down until at least 20 mK. The expected dynamical ground state of a quantum spin liquid was not observed but rather an inhomogeneous quasi-static spin state that survives with persistent long timescale fluctuations.

  9. Uniqueness of Positive Ground State Solutions of the Logarithmic Schrödinger Equation

    NASA Astrophysics Data System (ADS)

    Troy, William C.

    2016-12-01

    We prove the uniqueness of positive ground state solutions of the problem { {{d2u}/{dr2}} + {{n-1}/{r}}{du/dr}} + u ln(|u|) = 0}, {u(r) > 0 forall r ≥ 0}, and {(u(r),u'(r)) to (0, 0)} as {r to ∞}. This equation is derived from the logarithmic Schrödinger equation {iψt = {Δ} ψ + u ln (|u|2)}, and also from the classical equation {{{partial u}/{partial t}} = {Δ} u +u (|u|^{p-1}) -u}. For each {n ≥ 1}, a positive ground state solution is { u0(r) = exp (-{r^2/4} + {n/2}), 0 ≤ r < ∞}. We combine {u0(r)} with energy estimates and associated Ricatti equation estimates to prove that, for each {n in [1, 9 ]}, {u0(r)} is the only positive ground state. We also investigate the stability of {u0(r)}. Several open problems are stated.

  10. Spin-Orbit Coupling Controlled J =3 /2 Electronic Ground State in 5 d3 Oxides

    NASA Astrophysics Data System (ADS)

    Taylor, A. E.; Calder, S.; Morrow, R.; Feng, H. L.; Upton, M. H.; Lumsden, M. D.; Yamaura, K.; Woodward, P. M.; Christianson, A. D.

    2017-05-01

    Entanglement of spin and orbital degrees of freedom drives the formation of novel quantum and topological physical states. Here we report resonant inelastic x-ray scattering measurements of the transition metal oxides Ca3 LiOsO6 and Ba2 YOsO6 , which reveals a dramatic spitting of the t2 g manifold. We invoke an intermediate coupling approach that incorporates both spin-orbit coupling and electron-electron interactions on an even footing and reveal that the ground state of 5 d3-based compounds, which has remained elusive in previously applied models, is a novel spin-orbit entangled J =3 /2 electronic ground state. This work reveals the hidden diversity of spin-orbit controlled ground states in 5 d systems and introduces a new arena in the search for spin-orbit controlled phases of matter.

  11. Quantal Density Functional Theory(Q-DFT) of Degenerate Ground and Excited States

    NASA Astrophysics Data System (ADS)

    Sahni, Viraht; Pan, Xiaoyin

    2002-03-01

    We present here Q-DFT (V.Sahni et al, PRL 87), 113002 (2001), and references therein. of degenerate states with degeneracy g. We describe : (a) The transformation from a degenerate ground or excited pure state of the interacting system to an S (single Slater determinant) system of noninteracting Fermions with equivalent density, total energy, and ionization potential; (b) The construction of g S systems to reproduce a subspace ensemble density and energy. The density and energy are defined via the ensemble density matrix formed from the degenerate ground or excited pure states of the interacting system; (c) The construction of an S system with a g-fold degenerate highest occupied level, (which leads to g Slater determinants (C.A. Ullrich and W. Kohn, PRL 87), 093001(2001).), to reproduce the ground or excited state ensemble density and energy.

  12. Charge ordered normal ground state and its interplay with superconductivity in the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Sebastian, Suchitra

    2015-03-01

    Over the last few years, evidence has gradually built for a charge ordered normal ground state in the underdoped region of the cuprate high temperature superconductors. I will address the electronic structure of the normal ground state of the underdoped cuprates as accessed by quantum oscillations, and relate it to complementary measurements by other experimental techniques. The interplay of the charge ordered ground state with the antinodal gapped pseudogap state, and overarching magnetic and superconducting correlations will be further explored. This work was performed in collaboration with N. Harrison, G. G. Lonzarich, B. J. Ramshaw, B. S. Tan, P. A. Goddard, F. F. Balakirev, C. H. Mielke, R. Liang, D. A. Bonn, and W. N. Hardy

  13. Ground state of the hydrogen molecule in a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Kravchenko, Yu. P.; Liberman, M. A.

    1997-10-01

    The ground state of a hydrogen molecule in magnetic fields is investigated using a fully numerical Hartree-Fock approach. We found that between 4.2×104 T and 3×106 T the ground state is 3Σ+u with very weak interaction between atoms. In this field region the hydrogen can form a superfluid phase, predicted earlier [Korolev and Liberman, Phys. Rev. Lett. 72, 270 (1994)]; the state 3Πu is metastable and may be responsible for the unknown excitonic line observed by Timofeev and Chernenko [JETP Lett. 61, 617 (1995)]. For magnetic fields stronger than 3×106 T the ground state is the tightly bound 3Πu.

  14. Learning Approach on the Ground State Energy Calculation of Helium Atom

    SciTech Connect

    Shah, Syed Naseem Hussain

    2010-07-28

    This research investigated the role of learning approach on the ground state energy calculation of Helium atom in improving the concepts of science teachers at university level. As the exact solution of several particles is not possible here we used approximation methods. Using this method one can understand easily the calculation of ground state energy of any given function. Variation Method is one of the most useful approximation methods in estimating the energy eigen values of the ground state and the first few excited states of a system, which we only have a qualitative idea about the wave function.The objective of this approach is to introduce and involve university teacher in new research, to improve their class room practices and to enable teachers to foster critical thinking in students.

  15. Description of ground and excited electronic states by ensemble density functional method with extended active space

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Martínez, Todd J.; Kim, Kwang S.

    2017-08-01

    An extended variant of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, the REKS(4,4) method, designed to describe the ground electronic states of strongly multireference systems is modified to enable calculation of excited states within the time-independent variational formalism. The new method, the state-interaction state-averaged REKS(4,4), i.e., SI-SA-REKS(4,4), is capable of describing several excited states of a molecule involving double bond cleavage, polyradical character, or multiple chromophoric units. We demonstrate that the new method correctly describes the ground and the lowest singlet excited states of a molecule (ethylene) undergoing double bond cleavage. The applicability of the new method for excitonic states is illustrated with π stacked ethylene and tetracene dimers. We conclude that the new method can describe a wide range of multireference phenomena.

  16. Repumping ground-state population in a coherently driven atomic resonance.

    PubMed

    Sinay, Asif; Shuker, Moshe; Firstenberg, Ofer; Fisher, Amnon; Ben-Kish, Amit; Steinhauer, Jeff

    2010-08-30

    We experimentally demonstrate an optical pumping technique to pump a dilute rubidium vapor into the m(F) = 0 ground states. The technique utilizes selection rules that forbid the excitation of the m(F) = 0 states by linearly-polarized light. A substantial increase in the transparency contrast of the coherent-population-trapping resonance used for frequency standards is demonstrated.

  17. Origin of the Tetragonal Ground State of Heusler Compounds

    NASA Astrophysics Data System (ADS)

    Faleev, Sergey V.; Ferrante, Yari; Jeong, Jaewoo; Samant, Mahesh G.; Jones, Barbara; Parkin, Stuart S. P.

    2017-03-01

    We describe the general mechanism of tetragonal distortion in Heusler compounds X2Y Z . From 286 compounds studied using density-functional theory, 62% are found to be tetragonal at zero temperature. Such a large share of compounds with tetragonal distortions can be explained by the peak-and-valley character of the density of states (DOS) of these compounds in the cubic phase (arising from localized d bands and van Hove singularities) in conjunction with a smooth shift of peaky DOS structure relative to the Fermi energy, EF, when valence electrons are added to the system. A shift of the DOS in the Y or Z series leads to an alternation of stable and nonstable cubic phases that depends on the value of the DOS at EF in the cubic phase. Groups of compounds with a large share of tetragonal distortions are identified and explained.

  18. Restrictions on Medicaid abortions open to challenge on state constitutional grounds.

    PubMed

    Klassel, D

    1980-12-01

    The United States Court (June 30, 1980) held in Harris v. McRae and Williams V. Zbaraz that the federal government and the states may refuse to pay for most abortions needed by Medicaid-eligible women without violating the Constitution. These decisions brought to an end litigation to establish a federal constitutional right to public aid for poor women in deciding whether to continue or terminate a pregnancy. Decisions of a state's highest court resting solely on state law grounds are usually not reviewed by the U.S. Supreme Court, leaving each state free to curve out unique areas of rights and liberties for its population. Attention is directed here to the manner in which state courts may do so in the area of public funding for abortion with focus on the following: abortion and abortion funding under the federal constitution; challenging abortion restrictions on state constitutional grounds; establishing a state constitutional right to abortion; establishing denial of the right to abortion; justifying the interference; discrimination on the basis of wealth; and sex discrimination. The challenging of abortion funding restrictions on state constitutional grounds is a promising legal strategy for advocates of abortion rights. It has increased the chances for success in states that show a willingness to expand on federal constitutional law precedents: states that recognize principles of neutrality in granting government benefits or that provide special constitutional protection to the poor and to women.

  19. Studies of Compound States of Negative Ions Using Laser Beams

    DTIC Science & Technology

    1985-08-15

    Beams" under Office of Naval Research (ONR) task NR 393-071. The reader will note a change in the title of the proposal from that of the previous year...final results, referring the reader to the papers in Appendix I for details. We will separate discussions of the progress into two parts. Part I will...were observed. Thus, neither model could explain the also included. The reader is referred to the articles by Sel- enhanced doubly differential cross

  20. Ground-state energy of the q-state Potts model: The minimum modularity.

    PubMed

    Lee, J S; Hwang, S; Yeo, J; Kim, D; Kahng, B

    2014-11-01

    A wide range of interacting systems can be described by complex networks. A common feature of such networks is that they consist of several communities or modules, the degree of which may quantified as the modularity. However, even a random uncorrelated network, which has no obvious modular structure, has a finite modularity due to the quenched disorder. For this reason, the modularity of a given network is meaningful only when it is compared with that of a randomized network with the same degree distribution. In this context, it is important to calculate the modularity of a random uncorrelated network with an arbitrary degree distribution. The modularity of a random network has been calculated [Reichardt and Bornholdt, Phys. Rev. E 76, 015102 (2007)PLEEE81539-375510.1103/PhysRevE.76.015102]; however, this was limited to the case whereby the network was assumed to have only two communities, and it is evident that the modularity should be calculated in general with q(≥2) communities. Here we calculate the modularity for q communities by evaluating the ground-state energy of the q-state Potts Hamiltonian, based on replica symmetric solutions assuming that the mean degree is large. We found that the modularity is proportional to 〈sqrt[k]〉/〈k〉 regardless of q and that only the coefficient depends on q. In particular, when the degree distribution follows a power law, the modularity is proportional to 〈k〉^{-1/2}. Our analytical results are confirmed by comparison with numerical simulations. Therefore, our results can be used as reference values for real-world networks.

  1. Design considerations for the beam-waveguide retrofit of a ground antenna station

    NASA Technical Reports Server (NTRS)

    Veruttipong, T.; Withington, J.; Galindo-Israel, V.; Imbriale, W.; Bathker, D.

    1986-01-01

    Retrofitting an antenna that was originally designed without a beam waveguide introduces special difficulties because it is desirable to minimize alteration of the original mechanical truss work and to image the actual feed without distortion at the focal point of the dual-shaped reflector. To obtain an acceptable image, certain Geometrical Optics (GO) design criteria are followed as closely as possible. The problems associated with applying these design criteria to a 34-meter dual-shaped DSN (Deep Space Network) antenna are discussed. The use of various diffraction analysis techniques in the design process is also discussed. GTD and FFT algorithms are particularly necessary at the higher frequencies, while Physical Optics and Spherical Wave Expansions proved necessary at the lower frequencies.

  2. Ground Water Atlas of the United States: Introduction and National Summary

    USGS Publications Warehouse

    Miller, James A.

    1999-01-01

    The Ground Water Atlas of the United States provides a summary of the most important information available for each principal aquifer, or rock unit that will yield usable quantities of water to wells, throughout the 50 States, Puerto Rico, and the U.S. Virgin Islands. The Atlas is an outgrowth of the Regional Aquifer-System Analysis (RASA) program of the U.S. Geological Survey (USGS), a program that investigated 24 of the most important aquifers and aquifer systems of the Nation and one in the Caribbean Islands (fig. 1). The objectives of the RASA program were to define the geologic and hydrologic frameworks of each aquifer system, to assess the geochemistry of the water in the system, to characterize the ground-water flow system, and to describe the effects of development on the flow system. Although the RASA studies did not cover the entire Nation, they compiled much of the data needed to make the National assessments of ground-water resources presented in the Ground Water Atlas of the United States. The Atlas, however, describes the location, extent, and geologic and hydrologic characteristics of all the important aquifers in the United States, including those not studied by the RASA program. The Atlas is written so that it can be understood by readers who are not hydrologists. Simple language is used to explain technical terms. The principles that control the presence, movement, and chemical quality of ground water in different climatic, topographic, and geologic settings are clearly illustrated. The Atlas is, therefore, useful as a teaching tool for introductory courses in hydrology or hydrogeology at the college level and as an overview of ground-water conditions for consultants who need information about an individual aquifer. It also serves as an introduction to regional and National ground-water resources for lawmakers, personnel of local, State, or Federal agencies, or anyone who needs to understand ground-water occurrence, movement, and quality. The

  3. Entanglement of Photon-Added Nonlinear Coherent States Via a Beam Splitter

    NASA Astrophysics Data System (ADS)

    Honarasa, Gholamreza; Bagheri, Alireza; Gharaati, Abdolrasoul

    2016-10-01

    Nonlinear coherent states, photon-added coherent states and photon-added nonlinear coherent states are three of the important generalizations of standard coherent states. In this article, a photon-added nonlinear coherent state and a vacuum state are injected on two input modes of a beam splitter and the entanglement of the output state is investigated using linear entropy as the measure. Then, the impact of nonclassicality of the photon-added nonlinear coherent state on entanglement of the output state is studied.

  4. Hydrogeologic factors that influence ground water movement in the desert southwest United States

    USGS Publications Warehouse

    Chuang, Frank C.; McKee, Edwin H.; Howard, Keith A.

    2003-01-01

    A project to study ground-water and surface-water interactions in the desert southwestern United States was initiated in 2001 by the Tucson, Arizona office of the Water Resources Division, U.S. Geological Survey (USGS). One of the goals of the Southwest Ground-water Resources Project was to develop a regional synthesis that includes the use of available digital geologic data, which is growing rapidly due to the increasing use of Geographic Information Systems (GIS). Included in this report are the digital maps and databases of geologic information that should have a direct impact on the studies of ground-water flow and surface-water interaction. Ground-water flow is governed by many geologic factors or elements including rock and soil permeability, stratigraphy and structural features. These elements directly influence ground-water flow, which is key to understanding the possible inter-connectivity of aquifer systems in desert basins of the southwestern United States. We derive these elements from the evaluation of regional geology and localized studies of hydrogeologic basins. These elements can then be applied to other unstudied areas throughout the desert southwest. This report presents a regional perspective of the geologic elements controlling ground-water systems in the desert southwest that may eventually lead to greater focus on smaller sub-regions and ultimately, to individual ground-water basins.

  5. Arsenic in ground water of the United States: occurrence and geochemistry

    USGS Publications Warehouse

    Welch, Alan H.; Westjohn, D.B.; Helsel, Dennis R.; Wanty, Richard B.

    2000-01-01

    Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were 1 μg/L, about 10% exceeded 10 μg/L. At a broad regional scale, arsenic concentrations exceeding 10 μg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic Plain generally are very low ( 1 μg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System. Investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 μg/L are more widespread and common than previously recognized.Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 μg/L in ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations 10g/L in ground and surface water, particularly in the west.Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 µg/L a ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can

  6. Stability of the ground state of a harmonic oscillator in a monochromatic wave.

    PubMed

    Berman, Gennady P.; James, Daniel F. V.; Kamenev, Dmitry I.

    2001-09-01

    The stability of the ground state of a harmonic oscillator in a monochromatic wave is studied. This model describes, in particular, the dynamics of a cold ion in a linear ion trap, interacting with two laser fields with close frequencies. The stability of the "classical ground state"-the vicinity of the point (x=0,p=0)-is analyzed analytically and numerically. For the quantum case, a method for studying a stability of the quantum ground state is developed, based on the quasienergy representation. It is demonstrated that stability of the ground state may be substantially improved by increasing the resonance number, l, where l=Omega/omega+delta, Omega and omega are, respectively, the wave frequency and the oscillator frequency, l=1,2, em leader, mid R:deltamid R:<1; or by detuning the system from exact resonance, so that delta not equal 0. The influence of a large-amplitude wave (in the presence of chaos) on the stability of the ground state is analyzed for different parameters of the model in both the quantum and classical cases. (c) 2001 American Institute of Physics.

  7. Exact ground states and topological order in interacting Kitaev/Majorana chains

    NASA Astrophysics Data System (ADS)

    Katsura, Hosho; Schuricht, Dirk; Takahashi, Masahiro

    2015-09-01

    We study a system of interacting spinless fermions in one dimension that, in the absence of interactions, reduces to the Kitaev chain [Kitaev, Phys. Usp. 44, 131 (2001), 10.1070/1063-7869/44/10S/S29]. In the noninteracting case, a signal of topological order appears as zero-energy modes localized near the edges. We show that the exact ground states can be obtained analytically even in the presence of nearest-neighbor repulsive interactions when the on-site (chemical) potential is tuned to a particular function of the other parameters. As with the noninteracting case, the obtained ground states are twofold degenerate and differ in fermionic parity. We prove the uniqueness of the obtained ground states and show that they can be continuously deformed to the ground states of the noninteracting Kitaev chain without gap closing. We also demonstrate explicitly that there exists a set of operators each of which maps one of the ground states to the other with opposite fermionic parity. These operators can be thought of as an interacting generalization of Majorana edge zero modes.

  8. Like (CO)4, Do (CS)4 and (CSe)4 have a triplet ground state?

    PubMed

    Bao, Xiaoguang; Hrovat, David A; Borden, Weston Thatcher

    2013-04-26

    Cyclobutane-1,2,3,4-tetraone, (CO)4, was computationally predicted and, subsequently, experimentally confirmed to have a triplet ground state, in which a b2g σ MO and an a2u π MO were each singly occupied. In contrast, the (U)CCSD(T) calculations reported herein found that cyclobutane-1,2,3,4-tetrathione, (CS)4, and cyclobutane-1,2,3,4-tetraselenone, (CSe)4, both had singlet ground states, in which the b2g σ MO was doubly occupied and the a2u π MO was empty. Our calculations showed that both the longer C=X distances and smaller coefficients on the carbon atoms in the b2g and a2u MOs of (CS)4 and (CSe)4 contributed to the difference between the ground states of these two molecules and the ground state of (CO)4. An experimental test of the prediction of a singlet ground state for (CS)4 is proposed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Large-aperture laser beam scanner for inter-satellite laser communications ground test: assembly and test

    NASA Astrophysics Data System (ADS)

    Sun, Jianfeng; Yang, Lei; Liu, Liren; Shen, Qiande; Xu, Nan

    2006-08-01

    Inter-satellite laser communications attracted more and more attentions due to its excellent performances compared with the RF communications. But the test and verification of the communication terminals are very difficult because of the accuracy and aperture requirement. Large-aperture laser beam scanner was introduced to simulate the relative movement between satellites in the process of ground test for terminals. The scanner includes two same circular wedge prisms, which can scan an arbitrary position in a cone zone. The motivation of the assembly is to guarantee the accuracy of the scanner. Since the large-aperture and high-precision of the scanner, the assembly and test become a very troublesome problem. The test includes: (1) confirm the principal section of the wedge prisms; (2) test the optical quality of the wedge prisms; (3) confirm the scan range of the scanner; (5) test the scan accuracy of the scanner. The test results indicate the assembly process is reasonable. The scan range and accuracy can satisfy the requirement of the ground test of the inter-satellite laser communications terminals.

  10. The ground state of embryonic stem cell self-renewal

    PubMed Central

    Ying, Qi-Long; Wray, Jason; Nichols, Jennifer; Batlle-Morera, Laura; Doble, Bradley; Woodgett, James; Cohen, Philip; Smith, Austin

    2016-01-01

    In the three decades since pluripotent mouse embryonic stem (ES) cells were first described1,2 they have been derived and maintained by using various empirical combinations of feeder cells, conditioned media, cytokines, growth factors, hormones, fetal calf serum, and serum extracts1–7. Consequently ES-cell self-renewal is generally considered to be dependent on multifactorial stimulation of dedicated transcriptional circuitries, pre-eminent among which is the activation of STAT3 by cytokines (ref. 8). Here we show, however, that extrinsic stimuli are dispensable for the derivation, propagation and pluripotency of ES cells. Self-renewal is enabled by the elimination of differentiation-inducing signalling from mitogen-activated protein kinase. Additional inhibition of glycogen synthase kinase 3 consolidates biosynthetic capacity and suppresses residual differentiation. Complete bypass of cytokine signalling is confirmed by isolating ES cells genetically devoid of STAT3. These findings reveal that ES cells have an innate programme for self-replication that does not require extrinsic instruction. This property may account for their latent tumorigenicity. The delineation of minimal requirements for self-renewal now provides a defined platform for the precise description and dissection of the pluripotent state. PMID:18497825

  11. Effect of low-dose electron beam irradiation on quality of ground beef patties and raw, intact carcass muscle pieces.

    PubMed

    Kundu, Devapriya; Holley, Richard

    2013-06-01

    The objectives of this study were to determine the effects of a low-dose (≤1 kGy), low-penetration electron beam on the sensory qualities of (1) raw muscle pieces of beef and (2) cooked ground beef patties. Outside flat, inside round, brisket and sirloin muscle pieces were used as models to demonstrate the effect of irradiation on raw beef odor and color, as evaluated by a trained panel. Ground beef patties were also evaluated by a trained panel for tenderness, juiciness, beef flavor, and aroma at 10%, 20%, and 30% levels of fat, containing 0% (control), 10%, 20%, 50%, and 100% irradiated meat. With whole muscle pieces, the color of controls appeared more red (P < 0.05) than irradiated muscles, however, both control and treatments showed a gradual deterioration in color over 14 d aerobic storage at 4 °C. Off-aroma intensity of both control and treatments increased with storage time, but by day 14, the treated muscles showed significantly (P < 0.05) less off-aroma than the controls, presumably as a result of a lower microbial load. It was found that a 1 kGy absorbed dose had minimal effects on the sensory properties of intact beef muscle pieces. Irradiation did not have a significant effect (P > 0.05) on any of the sensory attributes of the patties. Low-dose irradiation of beef trim to formulate ground beef appears to be a viable alternative processing approach that does not affect product quality.

  12. Ground states of stealthy hyperuniform potentials. II. Stacked-slider phases.

    PubMed

    Zhang, G; Stillinger, F H; Torquato, S

    2015-08-01

    Stealthy potentials, a family of long-range isotropic pair potentials, produce infinitely degenerate disordered ground states at high densities and crystalline ground states at low densities in d-dimensional Euclidean space R^{d}. In the previous paper in this series, we numerically studied the entropically favored ground states in the canonical ensemble in the zero-temperature limit across the first three Euclidean space dimensions. In this paper, we investigate using both numerical and theoretical techniques metastable stacked-slider phases, which are part of the ground-state manifold of stealthy potentials at densities in which crystal ground states are favored entropically. Our numerical results enable us to devise analytical models of this phase in two, three, and higher dimensions. Utilizing this model, we estimated the size of the feasible region in configuration space of the stacked-slider phase, finding it to be smaller than that of crystal structures in the infinite-system-size limit, which is consistent with our recent previous work. In two dimensions, we also determine exact expressions for the pair correlation function and structure factor of the analytical model of stacked-slider phases and analyze the connectedness of the ground-state manifold of stealthy potentials in this density regime. We demonstrate that stacked-slider phases are distinguishable states of matter; they are nonperiodic, statistically anisotropic structures that possess long-range orientational order but have zero shear modulus. We outline some possible future avenues of research to elucidate our understanding of this unusual phase of matter.

  13. Formation of Triplet Positron-helium Bound State by Stripping of Positronium Atoms in Collision with Ground State Helium

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2006-01-01

    Formation of triplet positron-helium bound state by stripping of positronium atoms in collision with ground state helium JOSEPH DI RlENZI, College of Notre Dame of Maryland, RICHARD J. DRACHMAN, NASA/Goddard Space Flight Center - The system consisting of a positron and a helium atom in the triplet state e(+)He(S-3)(sup e) was conjectured long ago to be stable [1]. Its stability has recently been established rigorously [2], and the values of the energies of dissociation into the ground states of Ps and He(+) have also been reported [3] and [4]. We have evaluated the cross-section for this system formed by radiative attachment of a positron in triplet He state and found it to be small [5]. The mechanism of production suggested here should result in a larger cross-section (of atomic size) which we are determining using the Born approximation with simplified initial and final wave functions.

  14. Formation of Triplet Positron-helium Bound State by Stripping of Positronium Atoms in Collision with Ground State Helium

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2006-01-01

    Formation of triplet positron-helium bound state by stripping of positronium atoms in collision with ground state helium JOSEPH DI RlENZI, College of Notre Dame of Maryland, RICHARD J. DRACHMAN, NASA/Goddard Space Flight Center - The system consisting of a positron and a helium atom in the triplet state e(+)He(S-3)(sup e) was conjectured long ago to be stable [1]. Its stability has recently been established rigorously [2], and the values of the energies of dissociation into the ground states of Ps and He(+) have also been reported [3] and [4]. We have evaluated the cross-section for this system formed by radiative attachment of a positron in triplet He state and found it to be small [5]. The mechanism of production suggested here should result in a larger cross-section (of atomic size) which we are determining using the Born approximation with simplified initial and final wave functions.

  15. Recoil-Induced-Resonances in Nonlinear, Ground-State, Pump-Probe Spectroscopy

    DTIC Science & Technology

    2007-11-02

    spectrum by controlling the ratio of the Rabi frequencies of the two fields that comprise the two- photon pump field. Interference in a dressed state ...examine this question. In addition, we show that the interference persists even if the pump fields are in quantized, Fock states . The probe absorption...spectroscopy is developed in which optical fields drive two- photon Raman transitions between ground states of an ensemble of three-level atoms. Effects

  16. Van der Waals potential and vibrational energy levels of the ground state radon dimer

    NASA Astrophysics Data System (ADS)

    Sheng, Xiaowei; Qian, Shifeng; Hu, Fengfei

    2017-08-01

    In the present paper, the ground state van der Waals potential of the Radon dimer is described by the Tang-Toennies potential model, which requires five essential parameters. Among them, the two dispersion coefficients C6 and C8 are estimated from the well determined dispersion coefficients C6 and C8 of Xe2. C10 is estimated by using the approximation equation that C6C10/C82 has an average value of 1.221 for all the rare gas dimers. With these estimated dispersion coefficients and the well determined well depth De and Re the Born-Mayer parameters A and b are derived. Then the vibrational energy levels of the ground state radon dimer are calculated. 40 vibrational energy levels are observed in the ground state of Rn2 dimer. The last vibrational energy level is bound by only 0.0012 cm-1.

  17. Relativistic Quark-Model Results for Baryon Ground and Resonant States

    SciTech Connect

    Plessas, W.; Melde, T.

    2008-10-13

    Latest results from a study of baryon ground and resonant states within relativistic constituent quark models are reported. After recalling some typical spectral properties, the description of ground states, especially with regard to the nucleon and hyperon electromagnetic structures, is addressed. In the following, recent covariant predictions for pion, eta, and kaon partial decay widths of light and strange baryon resonances below 2 GeV are summarized. These results exhibit a characteristic pattern that is distinct from nonrelativistic or relativized decay studies performed so far. Together with a detailed analysis of the spin, flavor, and spatial structures of the wave functions, it supports a new and extended classification scheme of baryon ground and resonant states into SU(3) flavor multiplets.

  18. Ground State Properties of the 1/2 Flux Harper Hamiltonian

    NASA Astrophysics Data System (ADS)

    Kennedy, Colin; Burton, William Cody; Chung, Woo Chang; Ketterle, Wolfgang

    2015-05-01

    The Harper Hamiltonian describes the motion of charged particles in an applied magnetic field - the spectrum of which exhibits the famed Hofstadter's butterfly. Recent advances in driven optical lattices have made great strides in simulating nontrivial Hamiltonians, such as the Harper model, in the time-averaged sense. We report on the realization of the ground state of bosons in the Harper Hamiltonian for 1/2 flux per plaquette utilizing a tilted two-dimensional lattice with laser assisted tunneling. We detail progress in studying various ground state properties of the 1/2 flux Harper Hamiltonian including ground state degeneracies, gauge-dependent observables, effects of micromotion, adiabatic loading schemes, and emergence and decay of coherence. Additionally, we describe prospects for flux rectification using a period-tripled superlattice and generalizations to three dimensions. MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology.

  19. Broken vertex symmetry and finite zero-point entropy in the artificial square ice ground state

    SciTech Connect

    Gliga, Sebastian; Kákay, Attila; Heyderman, Laura J.; Hertel, Riccardo; Heinonen, Olle G.

    2015-08-26

    In this paper, we study degeneracy and entropy in the ground state of artificial square ice. In theoretical models, individual nanomagnets are typically treated as single spins with only two degrees of freedom, leading to a twofold degenerate ground state with intensive entropy and thus no zero-point entropy. Here, we show that the internal degrees of freedom of the nanostructures can result, through edge bending of the magnetization and breaking of local magnetic symmetry at the vertices, in a transition to a highly degenerate ground state with finite zero-point entropy, similar to that of the pyrochlore spin ices. Finally, we find that these additional degrees of freedom have observable consequences in the resonant spectrum of the lattice, and predict the occurrence of edge “melting” above a critical temperature at which the magnetic symmetry is restored.

  20. Broken vertex symmetry and finite zero-point entropy in the artificial square ice ground state

    DOE PAGES

    Gliga, Sebastian; Kákay, Attila; Heyderman, Laura J.; ...

    2015-08-26

    In this paper, we study degeneracy and entropy in the ground state of artificial square ice. In theoretical models, individual nanomagnets are typically treated as single spins with only two degrees of freedom, leading to a twofold degenerate ground state with intensive entropy and thus no zero-point entropy. Here, we show that the internal degrees of freedom of the nanostructures can result, through edge bending of the magnetization and breaking of local magnetic symmetry at the vertices, in a transition to a highly degenerate ground state with finite zero-point entropy, similar to that of the pyrochlore spin ices. Finally, wemore » find that these additional degrees of freedom have observable consequences in the resonant spectrum of the lattice, and predict the occurrence of edge “melting” above a critical temperature at which the magnetic symmetry is restored.« less

  1. Antibonding hole ground state in InAs quantum dot molecules

    SciTech Connect

    Planelles, Josep

    2015-01-22

    Using four-band k⋅p Hamiltonians, we study how strain and position-dependent effective masses influence hole tunneling in vertically coupled InAs/GaAs quantum dots. Strain reduces the tunneling and hence the critical interdot distance required for the ground state to change from bonding to antibonding. Variable mass has the opposite effect and a rough compensation leaves little affected the critical bonding-to-antibonding ground state crossover. An alternative implementation of the magnetic field in the envelope function Hamiltonian is given which retrieves the experimental denial of possible after growth reversible magnetically induced bonding-to-antibonding ground state transition, predicted by the widely used Luttinger-Kohn Hamiltonian.

  2. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet

    DOE PAGES

    Fu, Mingxuan; Imai, Takahashi; Han, Tian -Heng; ...

    2015-11-06

    Here, the kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χkagome, deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with themore » magnetic field dependence of χkagome that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.« less

  3. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet

    SciTech Connect

    Fu, M.; Imai, T.; Han, T. -H.; Lee, Y. S.

    2015-11-05

    The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum.We demonstrated that the intrinsic local spin susceptibility ckagome, deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of ckagome that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.

  4. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet.

    PubMed

    Fu, Mingxuan; Imai, Takashi; Han, Tian-Heng; Lee, Young S

    2015-11-06

    The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χ(kagome), deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of χ(kagome) that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.

  5. Electron beam fluorescence spectrometry of internal state populations in nozzle beams of nitrogen and nitrogen/rare gas mixtures

    SciTech Connect

    Faubel, M.; Weiner, E.R.

    1981-07-15

    Rotational level populations of N/sub 2/ were measured downstream from the skimmer in beams of pure N/sub 2/ and in mixtures of N/sub 2/ with He, Ne, and Ar expanded from room temperature nozzles. The range of p/sub 0/D was from 5 to 50 Torr cm. The formation of dimers and higher condensates of beam species was monitored during the runs. The effect of condensation energy release on rotational populations and parallel temperatures was readily observed. Two different methods for evaluating the rotational population distributions were compared. One method is based on a dipole-excitation model and the other on an excitation matrix obtained empirically. Neither method proved clearly superior. Both methods indicated nonequilibrium rotational populations for all of our room temperature nozzle expansion conditions. Much of the nonequilibrium character appears to be due to the behavior of the K = 2 and K = 4 levels, which may be accounted for in terms of the rotational energy level spacing. In particular, the overpopulation of the K = 4 level is explained by a near-resonant transfer of rotational energy between molecules in the K = 6 and K = 0 states, to give two molecules in the K = 4 state. Rotational and vibrational temperatures were determined for pure N/sub 2/ beams from nozzles heated up to 1700 /sup 0/K. The heated nozzle experiments indicated a 40% increase in the rotational collision number between 300 and 1700 /sup 0/K.

  6. Cold collisions of ground-state calcium atoms in a laser field: A theoretical study

    SciTech Connect

    Bussery-Honvault, Beatrice; Launay, Jean-Michel; Moszynski, Robert

    2003-09-01

    State-of-the-art ab initio techniques have been applied to compute the potential-energy curves for the ground X {sup 1}{sigma}{sub g}{sup +} and excited {sup 1}{pi}{sub g}(4s3d) states of the calcium dimer in the Born-Oppenheimer approximation. The weakly bound ground state was calculated by symmetry-adapted perturbation theory, while the strongly bound excited state was computed using a combination of the linear-response theory within the coupled-cluster singles and doubles framework for the core-valence electronic correlation and of the full configuration interaction for the valence-valence correlation. The ground-state potential has been corrected by considering the relativistic terms resulting from the first-order many-electron Breit theory, and the retardation corrections. The magnetic electronic transition dipole moment governing the {sup 1}{pi}{sub g}(leftarrow){sup 1}{sigma}{sub g}{sup +} transitions has been obtained as the first residue of the polarization propagator computed with the coupled-cluster method restricted to single and double excitations. The computed energies and transition moments have been analytically fitted and used in the dynamical calculations of the rovibrational energy levels, ground-state scattering length, photoassociation intensities at ultralow temperatures, and spontaneous emission coefficients from the {sup 1}{pi}{sub g}(4s3d) to the X {sup 1}{sigma}{sub g}{sup +} state. The spectroscopic constants of the theoretical ground-state potential are in a good agreement with the experimental values derived from the Fourier-transform spectra [O. Allard et al., Eur. Phys. J. D (to be published)]. The theoretical s-wave scattering length for the ground state is a=44 bohrs, suggesting that it should be possible to obtain a stable Bose-Einstein condensate of calcium atoms. Finally, the computed photoassociation intensities and spontaneous emission coefficients suggest that it should be possible to obtain cold calcium molecules by

  7. United States Air Force Academy get-away-special flexible beam experiment

    NASA Technical Reports Server (NTRS)

    Bubb, Keith W.; Lamberson, Steven E.; Lash, Thomas A.

    1989-01-01

    The Department of Astronautics at the United States Air Force Academy is currently planning to fly an experiment in a NASA Get-Away-Special (GAS) canister. The experiment was named the flex beam experiment. The primary technical objective of the flex beam experiment is to measure the damping of a thin beam in the vacuum and zero G environment of space. By measuring the damping in space, it is hoped to determine the amount of damping the beam normally experiences due to the gravitational forces present on Earth. This will allow validation of models which predict the dynamics of thin beams in the space environment. The experiment will also allow the Academy to develop and improve its ability to perform experiments within the confines of a NASA GAS canister. Several experiments, of limited technical difficulty, were flown by the Academy. More complex experiments are currently planned and it is hoped to learn techniques with each space shuttle flight.

  8. A combined IR/IR and IR/UV spectroscopy study on the proton transfer coordinate of isolated 3-hydroxychromone in the electronic ground and excited state.

    PubMed

    Stamm, A; Weiler, M; Brächer, A; Schwing, K; Gerhards, M

    2014-10-21

    In this paper the excited state proton transfer (ESPT) of isolated 3-hydroxychromone (3-HC), the prototype of the flavonols, is investigated for the first time by combined IR/UV spectroscopy in molecular beam experiments. The IR/UV investigations are performed both for the electronically excited and electronic ground state indicating a spectral overlap of transitions of the 3-HC monomer and clusters with water in the electronic ground state, whereas in the excited state only the IR frequencies of the proton-transferred monomer structure are observed. Due to the loss of isomer and species selectivity with respect to the UV excitations IR/IR techniques are applied in order to figure out the assignment of the vibrational transitions in the S0 state. In this context the quadruple resonance IR/UV/IR/UV technique (originally developed to distinguish different isomers in the electronically excited state) could be applied to identify the OH stretching vibration of the monomer in the electronic ground state. In agreement with calculations the OH stretching frequency differs significantly from the corresponding values of substituted hydroxychromones.

  9. Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

    NASA Astrophysics Data System (ADS)

    Borges, L. H. C.; Barone, F. A.

    2016-02-01

    Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.

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

    SciTech Connect

    Apaja, Vesa; Syljuaasen, Olav F.

    2006-09-15

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

  11. Simulation of the Hydrogen Ground State in Stochastic Electrodynamics-2: Inclusion of Relativistic Corrections

    NASA Astrophysics Data System (ADS)

    Nieuwenhuizen, Theodorus M.; Liska, Matthew T. P.

    2015-10-01

    In a recent paper the authors studied numerically the hydrogen ground state in stochastic electrodynamics (SED) within the the non-relativistic approximation. In quantum theory the leading non-relativistic corrections to the ground state energy dominate the Lamb shift related to the photon cloud that should cause the quantum-like behaviour of SED. The present work takes these corrections into account in the numerical modelling. It is found that they have little effect; the self-ionisation that occurs without them remains present. It is speculated that the point-charge approximation for the electron is the cause of the failure.

  12. Projected shell model study of ground state bands in 171-175Tm

    NASA Astrophysics Data System (ADS)

    Slathia, B.; Devi, R.; Khosa, S. K.

    2016-10-01

    The ground state bands of thulium isotopes with mass numbers (A), ranging from 171 to 175, have been investigated in the framework of the projected shell model. The theoretical results for the energy levels of ground state bands were found to be in reasonable agreement with the observed values. Predictably, E2 transition probabilities have got predicted vis-a-vis transitions with non-availability of experimental values. The E2 transition probability values have been observed to follow the same trend as seen in 171Tm.

  13. On stability of ground states for finite crystals in the Schrödinger-Poisson model

    NASA Astrophysics Data System (ADS)

    Komech, A.; Kopylova, E.

    2017-03-01

    We consider the Schrödinger-Poisson-Newton equations for finite crystals under periodic boundary conditions with one ion per cell of a lattice. The electrons are described by one-particle Schrödinger equation. Our main results are (i) the global dynamics with moving ions and (ii) the orbital stability of periodic ground state under a novel Jellium and Wiener-type conditions on the ion charge density. Under the Jellium condition, both ionic and electronic charge densities for the ground state are uniform.

  14. Ground state cooling of a nanomechanical resonator in the nonresolved regime via quantum interference.

    PubMed

    Xia, Keyu; Evers, Jörg

    2009-11-27

    Ground state cooling of a nanomechanical resonator coupled to a superconducting flux qubit is discussed. By inducing quantum interference to cancel unwanted heating excitations, ground state cooling becomes possible in the nonresolved regime. The qubit is modeled as a three-level system in Lambda configuration, and the driving fluxes are applied such that the qubit absorption spectrum exhibits electromagnetically induced transparency, thereby canceling the unwanted excitations. As our scheme allows the application of strong cooling fields, fast and efficient cooling can be achieved.

  15. On the Ground-State Energy and Local Pressure of an Inhomogeneous Bose Gas

    NASA Astrophysics Data System (ADS)

    Bobrov, V. B.; Trigger, S. A.

    2017-01-01

    The exact expression for the average kinetic energy of an inhomogeneous Bose gas in the ground state is obtained as a functional of the inhomogeneous density of the Bose-Einstein condensate. The result is based on existence of the off-diagonal long-range order in the single-particle density matrix for systems with a Bose-Einstein condensate. This makes it possible to avoid the use of anomalous averages. On this basis, the explicit expressions for the ground-state energy and the local pressure of an inhomogeneous Bose gas are derived within the self-consistent Hartree-Fock approximation.

  16. Determining the Parameters of the Ground Vibrational State of the 28SiH4 Molecule

    NASA Astrophysics Data System (ADS)

    Raspopova, N. I.; Gromova, O. V.; Bekhtereva, E. S.; Bauerecker, Z.

    2017-09-01

    For high-precision determination of the rotational-vibrational energies of the ground vibrational state of the SiH4 molecule, high-resolution rotational-vibrational spectrum of this molecule in the range 600-1200 cm-1 in which bands of the ν2/ ν4 dyad are located is analyzed. As a result, rotational and centrifugal distortion parameters of the ground vibrational state with a root-mean-square deviation of 2·10-4 cm-1 are obtained.

  17. Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study

    NASA Astrophysics Data System (ADS)

    Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony

    2017-02-01

    The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.

  18. Preparing ground States of quantum many-body systems on a quantum computer.

    PubMed

    Poulin, David; Wocjan, Pawel

    2009-04-03

    Preparing the ground state of a system of interacting classical particles is an NP-hard problem. Thus, there is in general no better algorithm to solve this problem than exhaustively going through all N configurations of the system to determine the one with lowest energy, requiring a running time proportional to N. A quantum computer, if it could be built, could solve this problem in time sqrt[N]. Here, we present a powerful extension of this result to the case of interacting quantum particles, demonstrating that a quantum computer can prepare the ground state of a quantum system as efficiently as it does for classical systems.

  19. First-principles prediction of a ground state crystal structure of magnesium borohydride.

    PubMed

    Ozolins, V; Majzoub, E H; Wolverton, C

    2008-04-04

    Mg(BH(4))(2) contains a large amount of hydrogen by weight and by volume, but its promise as a candidate for hydrogen storage is dependent on the currently unknown thermodynamics of H2 release. Using first-principles density-functional theory calculations and a newly developed prototype electrostatic ground state search strategy, we predict a new T=0 K ground state of Mg(BH(4))(2) with I4[over ]m2 symmetry, which is 5 kJ/mol lower in energy than the recently proposed P6(1) structure. The calculated thermodynamics of H(2) release are within the range required for reversible storage.

  20. Detecting ground-state degeneracy in many-body systems through qubit decoherence

    NASA Astrophysics Data System (ADS)

    Cui, Hai-Tao; Yi, Xue-Xi

    2017-02-01

    By coupling with a qubit, we demonstrate that qubit decoherence can unambiguously detect the occurrence of ground-state degeneracy in many-body systems. We first demonstrate universality using the two-band model. Consequently, several exemplifications, focused on topological condensed matter systems in one, two, and three dimensions, are presented to validate our proposal. The key point is that qubit decoherence varies significantly when energy bands touch each other at the Fermi surface. In addition, it can partially reflect the degeneracy inside the band. This feature implies that qubit decoherence can be used for reliable diagnosis of ground-state degeneracy.

  1. Preparing Ground States of Quantum Many-Body Systems on a Quantum Computer

    SciTech Connect

    Poulin, David; Wocjan, Pawel

    2009-04-03

    Preparing the ground state of a system of interacting classical particles is an NP-hard problem. Thus, there is in general no better algorithm to solve this problem than exhaustively going through all N configurations of the system to determine the one with lowest energy, requiring a running time proportional to N. A quantum computer, if it could be built, could solve this problem in time {radical}(N). Here, we present a powerful extension of this result to the case of interacting quantum particles, demonstrating that a quantum computer can prepare the ground state of a quantum system as efficiently as it does for classical systems.

  2. Model valence-fluctuation systems: variational ground states and magnetic responses

    SciTech Connect

    Brandow, B.H.

    1980-04-01

    Variational ground-state wavefunctions are presented and optimized for two model valence-fluctuation systems, based on Anderson lattice Hamiltonians in the U ..-->.. infinity limit. Although these wavefunctions are approximate, they are treated in an essentially exact manner. The )f/sup 0/, f/sup 1/; n = 1) system has an intuitively reasonable ground-state susceptibility, while the )f/sup 1/, f/sup 2/; n = 2) system is found to exhibit an insulating gap. Due to their different crystal symmetries, this gap should be realized in SmB/sub 6/ but not in SmS.

  3. Ground-state properties of third-row elements with nonlocal density functionals

    SciTech Connect

    Bagno, P.; Jepsen, O.; Gunnarsson, O.

    1989-07-15

    The cohesive energy, the lattice parameter, and the bulk modulus of third-row elements are calculated using the Langreth-Mehl-Hu (LMH), the Perdew-Wang (PW), and the gradient expansion functionals. The PW functional is found to give somewhat better results than the LMH functional and both are found to typically remove half the errors in the local-spin-density (LSD) approximation, while the gradient expansion gives worse results than the local-density approximation. For Fe both the LMH and PW functionals correctly predict a ferromagnetic bcc ground state, while the LSD approximation and the gradient expansion predict a nonmagnetic fcc ground state.

  4. On Asymptotic Stability in Energy Space of Ground States for Nonlinear Schrödinger Equations

    NASA Astrophysics Data System (ADS)

    Cuccagna, Scipio; Mizumachi, Tetsu

    2008-11-01

    We consider nonlinear Schrödinger equations iu_t +Δ u +β (|u|^2)u=0 , text{for} (t,x)in mathbb{R}× mathbb{R}^d, where d ≥ 3 and β is smooth. We prove that symmetric finite energy solutions close to orbitally stable ground states converge to a sum of a ground state and a dispersive wave as t → ∞ assuming the so called the Fermi Golden Rule (FGR) hypothesis. We improve the “sign condition” required in a recent paper by Gang Zhou and I.M.Sigal.

  5. Developing a state water plan: Ground-water conditions in Utah, spring of 1967

    USGS Publications Warehouse

    Baker, C.H.; Price, Don; Butler, R.G.; Mower, R.W.; Herbert, L.R.; Cordova, R.M.; Bolke, E.L.; Bjorklund, L.J.; Robinson, G.B. Jr.; Sandberg, G.W.

    1967-01-01

    This report is the fourth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series are prepared cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources and are designed to provide data to enable interested parties such as legislators, administrators, and planners to keep abreast of changing ground-water conditions.This report, like the others (see references, p. 89), contains information on well construction, ground-water withdrawals, water-level changes, and related changes in precipitation and streamflow. It also contains supplementary data that are related to ground-water use in some areas. In reports of this series, the inclusion of such supplementary data as graphs showing chemical quality of water and maps showing water-table configuration is intended only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.The report includes individual discussions of the most important areas of ground-water withdrawal in the State for the calendar year 1966. Water-level fluctuations, however, are described for the period spring 1966 to spring 1967. Many of the data used in the report were collected by the Geological Survey in cooperation with the Utah State Engineer.

  6. Developing a state water plan: Ground-water conditions in Utah, spring of 1966

    USGS Publications Warehouse

    Hood, J.W.; Herbert, L.R.; Butler, R.G.; Mower, R.W.; Handy, A.H.; Cordova, R.M.; Feltis, R.D.; Bjorklund, L.J.; Robinson, G.B. Jr.; Sandberg, G.W.

    1966-01-01

    This report is the third in a series of annual reports that describe ground-water conditions in Utah. Reports in this series are prepared cooperatively by the U.S. Geological Survey and the Utah Water and Power Board and are designed to provide data to enable interested parties such as legislators, administrators, and planners to keep abreast of changing ground-water conditions.This report, like the first two (Arnow and others, 1964, 1965), contains information on well construction, ground-water withdrawals, water-level changes, and related changes in precipitation and streamflow. It also contains supplementary data that are related to ground-water use in some individual areas. In reports of this series, the inclusion of such supplementary data as graphs showing chemical quality of water and maps showing water-table slope is intended only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.The report includes individual discussions of the most important areas of ground-water withdrawal in the State for the calendar year 1965. Water-level fluctuations, however, are described for the period spring 1965 through spring 1966. Many of the data used in the report were collected by the Geological Survey in cooperation with the Utah State Engineer.

  7. Estimation of ground and excited state dipole moments of Oil Red O by solvatochromic shift methods.

    PubMed

    Sıdır, İsa; Gülseven Sıdır, Yadigar

    2015-01-25

    Absorption and fluorescence spectra of Oil Red O (abbreviated as ORO) are recorded in various solvents with different polarity in the range of 250-900 nm, at room temperature. The solvatochromic shift methods have been used to determine the ground state (μg) and excited state (μe) dipole moments depending on dielectric constant and refractive index functions. It is observed that fluorescence spectra show positive solvatochromism whereas absorption spectra do not indicates sensitive behavior to solvent polarity. Excited state dipole moment is found as higher than those of ground state for all of the used methods and it is attributed to more polar excited state of ORO. Theoretical μg has been determined by quantum chemical calculations using DFT and semi empirical methods. HOMO, LUMO, molecular electrostatic potential (MEP) and solvent accessible surface of ORO are calculated by using DFT-B3LYP method.

  8. Estimation of ground and excited state dipole moments of Oil Red O by solvatochromic shift methods

    NASA Astrophysics Data System (ADS)

    Sıdır, İsa; Gülseven Sıdır, Yadigar

    2015-01-01

    Absorption and fluorescence spectra of Oil Red O (abbreviated as ORO) are recorded in various solvents with different polarity in the range of 250-900 nm, at room temperature. The solvatochromic shift methods have been used to determine the ground state (μg) and excited state (μe) dipole moments depending on dielectric constant and refractive index functions. It is observed that fluorescence spectra show positive solvatochromism whereas absorption spectra do not indicates sensitive behavior to solvent polarity. Excited state dipole moment is found as higher than those of ground state for all of the used methods and it is attributed to more polar excited state of ORO. Theoretical μg has been determined by quantum chemical calculations using DFT and semi empirical methods. HOMO, LUMO, molecular electrostatic potential (MEP) and solvent accessible surface of ORO are calculated by using DFT-B3LYP method.

  9. Ground and excited state chemistry of some hydrophilic thiazine dyes for possible photogalvanic applications

    SciTech Connect

    Burton, W.C.

    1982-08-01

    The research was designed to study the ground and excited state properties of hydrophilic analogues of the thiazine dye, thionine. The analogues were prepared by substituting ..beta..-hydroxyethyl or N-methylpiperazine groups onto the thiazine chromophore. Positive charges were introduced into the analogues containing the N-methylpiperazine groups by methylation of the N-methyl nitrogen atom of the piperazine ring. After purification and characterization of the analogues, ground state properties such as water solubility and aggregation were studied. Excited state studies involved determination of triplet state lifetimes (tau), and triplet state rate constants for, self quenching, (k/sub SQ/), ferrous quenching (k/sub Q/), and bromide and iodide (k/sub Br/ and K/sub I/) quenching. Oxidation and decay of the photoproducts, semireduced dyes and leuco dyes, was also studied.

  10. Electron impact ionization of helium from its ground and metastable states

    NASA Astrophysics Data System (ADS)

    Zhang-jin, Chen; Ke-zun, Xu

    1999-05-01

    The triple differential cross sections for the ionization of helium from its ground state 1 1S and metastable states 2 1S and 2 3S in coplanar asymmetric geometry by 150, 250 and 400 eV electrons have been calculated in the BBK model. The present results are compared with the experimental data and/or the other theoretical ones. It has been found that the structures for the metastable states differ markedly from those for the ground state. The collision mechanisms for the new structures appearing in the cross sections for the ionization from metastable states have been analysed. And it has been shown how the intensity of recoil peak changes due to the size of the electron orbital. In addition, the optimal kinematical situations for the cross sections are explored for future experiment.

  11. Synthesis of arbitrary Fock states via conditional measurement on beam splitters

    SciTech Connect

    Escher, B.M.; Baseia, B.; Avelar, A.T.

    2005-10-15

    In a previous work [Opt. Commun. 138, 71 (1997)] a scheme was proposed to create traveling fields in the Fock state |2{sup J}>. Here we show how to extend this result to arbitrary Fock states. The procedure combines one-photon states impinging on a sequence of distinct beam splitters, each one associated with a (zero detection) single-photon photodetector, with optimization of the success probability to get the desired state. Advantages and disadvantages of this scheme are discussed.

  12. Ground state spin and excitation energies in half-filled Lieb lattices

    NASA Astrophysics Data System (ADS)

    Ţolea, M.; Niţǎ, M.

    2016-10-01

    We present detailed spectral calculations for small Lieb lattices having up to N =4 number of cells, in the regime of half-filling, an instance of particular relevance for the nanomagnetism of discrete systems such as quantum dot arrays, due to the degenerate levels at midspectrum. While for the Hubbard interaction model—and even number of sites—the ground state spin is given by the Lieb theorem, the inclusion of long-range interaction—or odd number of sites—makes the spin state not known a priori, which justifies our approach. We calculate also the excitation energies, which are of experimental importance, and find significant variation induced by the interaction potential. One obtains insights on the mechanisms involved that impose as ground state the Lieb state with lower spin rather than the Hund one with maximum spin for the degenerate levels, showing this in the first and second orders of the interaction potential for the smaller lattices. The analytical results agree with the numerical ones, which are performed by exact diagonalization calculations or by a combined mean-field and configuration interaction method. While the Lieb state is always lower in energy than the Hund state, for strong long-range interaction, when possible, another minimal spin state is imposed as ground state.

  13. Measurements of Variable-Shaped Electron Beams with Solid-State Detector and Scattering Aperture

    NASA Astrophysics Data System (ADS)

    Sakakibara, Makoto; Ohta, Hiroya; Kanosue, Tadashi; Sohda, Yasunari; Ban, Naoma

    2007-09-01

    A highly accurate method for measuring beam properties in a variable-shaped electron beam (VSB) system has been developed. This method is based on a knife-edge method with a solid-state detector (SSD) and scattering apertures. In VSB system, it is necessary to measure both beam profile and beam position for a long time. To meet this requirement, many aperture marks on a silicon membrane were prepared in a measurement unit. Using this unit, the accuracy and stability of beam-size and beam position measurements were evaluated in VBS system (HL-7000D, Hitachi-HITEC). As a result, the repeatability error for beam size was obtained to be smaller than 2 nm (3σ) and the repeatability error for beam position was obtained to be 0.82 nm (3σ). Moreover, a multitude of repeat experiments showed that this measurement unit can be used for more than ten years. Consequently, it was confirmed that this measurement method is useful for the high accuracy of a VSB system.

  14. Ground-water indicators state pilot studies for Idaho, Minnesota, and New Jersey: Findings report

    SciTech Connect

    Not Available

    1991-09-30

    The Findings Report describes and presents general findings from the three ground-water indicator State pilot studies the U.S. Environmental Protection Agency conducted in Idaho, Minnesota, and New Jersey to investigate the use of indicators to track progress and trends in the ground-water protection effort. EPA evaluated the following five indicators in these studies: Maximum Contaminant Level (MCL) violations by public drinking water supplies; On-site and off-site contamination at hazardous waste sites; Volatile Organic Compound (VOC) concentrations in ground water (as an indicator of waste site and industrial site activity); Nitrate concentrations in ground water (as an indicator of area-wide sources of contamination); and Extent of pesticide use (as an indicator of area-wide pesticide contamination).

  15. Experimental generation of tripartite polarization entangled states of bright optical beams

    SciTech Connect

    Wu, Liang; Liu, Yanhong; Deng, Ruijie; Yan, Zhihui; Jia, Xiaojun Xie, Changde; Peng, Kunchi

    2016-04-18

    The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.

  16. Experimental generation of tripartite polarization entangled states of bright optical beams

    NASA Astrophysics Data System (ADS)

    Wu, Liang; Yan, Zhihui; Liu, Yanhong; Deng, Ruijie; Jia, Xiaojun; Xie, Changde; Peng, Kunchi

    2016-04-01

    The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.

  17. Formation and nonlinear dynamics of the squeezed state of a helical electron beam with additional deceleration

    SciTech Connect

    Egorov, E. N. Koronovskii, A. A.; Kurkin, S. A.; Hramov, A. E.

    2013-11-15

    Results of numerical simulations and analysis of the formation and nonlinear dynamics of the squeezed state of a helical electron beam in a vircator with a magnetron injection gun as an electron source and with additional electron deceleration are presented. The ranges of control parameters where the squeezed state can form in such a system are revealed, and specific features of the system dynamics are analyzed. It is shown that the formation of a squeezed state of a nonrelativistic helical electron beam in a system with electron deceleration is accompanied by low-frequency longitudinal dynamics of the space charge.

  18. Ground-state angular momentum, spectral asymmetry, and topology in chiral superfluids and superconductors

    NASA Astrophysics Data System (ADS)

    Ojanen, Teemu

    2016-05-01

    Recently, it was discovered that the ground-state orbital angular momentum in two-dimensional chiral superfluids with pairing symmetry (px+i py) ν depends on the winding number ν in a striking manner. The ground-state value for the ν =1 case is Lz=ℏ N /2 as expected by counting the Cooper pairs, while a dramatic cancellation takes place for ν >1 . The origin of the cancellation is associated with the topological edge states that appear in a finite geometry and give rise to a spectral asymmetry. Here, we study the reduction of orbital angular momentum for different potential profiles and pairing strengths, showing that the result Lz=ℏ N /2 is robust for ν =1 under all studied circumstances. We study how angular momentum depends on the gap size Δ /EF and obtain the result Lz=ℏ/ν 2 N (1 -μ/EF) for ν =2 ,3 . Thus, the gap dependence of Lz for ν <4 enters at most through the chemical potential while ν ≥4 is qualitatively different. In addition, we generalize the spectral asymmetry arguments to total angular momentum in the ground state of triplet superfluids where due to a spin-orbit coupling Lz is not a good quantum number. We find that the ground-state total angular momentum also behaves very differently depending on total angular momentum of the Cooper pairs.

  19. Calculated ground state potential surface and excitation energies for the copper trimer

    NASA Technical Reports Server (NTRS)

    Walch, S. P.; Laskowski, B. C.

    1986-01-01

    In the context of their relevance to catalysis and to materials science problems, transition metals and transition metal (TM) compounds are currently of considerable interest, and studies have been conducted of the copper trimer, Cu3. The present investigation is concerned with a study of the ground state surface and several groups of excited states in order to improve the understanding of the spectroscopy of Cu3. Differences of the current study from previous investigations are related to an employment of larger basis sets and a more extensive electron correlation. This was done with the objective to obtain a more accurate definition of the ground state surface. Features of the bonding in the copper dimer are considered to obtain a basis for an understanding of the copper trimer. Attention is given to calculational details, the ground state surface, and calculated vertical excitation energies. The results of SCF/SDCI calculations are reported for portions of the ground surface, for two groups of excited states, and for the ionization potential of Cu3.

  20. Polarization memory in the nonpolar magnetic ground state of multiferroic CuFeO2

    NASA Astrophysics Data System (ADS)

    Beilsten-Edmands, J.; Magorrian, S. J.; Foronda, F. R.; Prabhakaran, D.; Radaelli, P. G.; Johnson, R. D.

    2016-10-01

    We investigate polarization memory effects in single-crystal CuFeO2, which has a magnetically induced ferroelectric phase at low temperatures and applied B fields between 7.5 and 13 T. Following electrical poling of the ferroelectric phase, we find that the nonpolar collinear antiferromagnetic ground state at B =0 T retains a strong memory of the polarization magnitude and direction, such that upon reentering the ferroelectric phase a net polarization of comparable magnitude to the initial polarization is recovered in the absence of external bias. This memory effect is very robust: in pulsed-magnetic-field measurements, several pulses into the ferroelectric phase with reverse bias are required to switch the polarization direction, with significant switching only seen after the system is driven out of the ferroelectric phase and ground state either magnetically (by application of B >13 T) or thermally. The memory effect is also largely insensitive to the magnetoelastic domain composition, since no change in the memory effect is observed for a sample driven into a single-domain state by application of stress in the [1 1 ¯0 ] direction. On the basis of Monte Carlo simulations of the ground-state spin configurations, we propose that the memory effect is due to the existence of helical domain walls within the nonpolar collinear antiferromagnetic ground state, which would retain the helicity of the polar phase for certain magnetothermal histories.

  1. A projection gradient method for computing ground state of spin-2 Bose–Einstein condensates

    SciTech Connect

    Wang, Hanquan

    2014-10-01

    In this paper, a projection gradient method is presented for computing ground state of spin-2 Bose–Einstein condensates (BEC). We first propose the general projection gradient method for solving energy functional minimization problem under multiple constraints, in which the energy functional takes real functions as independent variables. We next extend the method to solve a similar problem, where the energy functional now takes complex functions as independent variables. We finally employ the method into finding the ground state of spin-2 BEC. The key of our method is: by constructing continuous gradient flows (CGFs), the ground state of spin-2 BEC can be computed as the steady state solution of such CGFs. We discretized the CGFs by a conservative finite difference method along with a proper way to deal with the nonlinear terms. We show that the numerical discretization is normalization and magnetization conservative and energy diminishing. Numerical results of the ground state and their energy of spin-2 BEC are reported to demonstrate the effectiveness of the numerical method.

  2. Entanglement dynamics of quantum states generated by a Kerr medium and a beam splitter

    NASA Astrophysics Data System (ADS)

    Rohith, M.; Sudheesh, C.; Rajeev, R.

    2016-01-01

    We study theoretically the dynamics of entangled states created in a beam splitter with a nonlinear Kerr medium placed into one input arm. Entanglement dynamics of initial classical and nonclassical states are studied and compared. Signatures of revival and fractional revival phenomena exhibited during the time evolution of states in the Kerr medium are captured in the entangled states produced by the beam splitter. Dynamics of entanglement shows local minima at the instants of fractional revivals. These minima correspond to the generation of two-component Schrödinger cat states or multi-component Schrödinger cat-like states if the initial state considered is a coherent state. Maximum entanglement is obtained at the instants of collapses of wave packets in the medium. Our analysis shows increase in entanglement with increase in the degree of nonclassicality of the initial states considered. We show that the states generated at the output of the beam splitter using initial nonclassical states are more robust against decoherence due to photon absorption by an environment than those formed by an initial classical state.

  3. Ground state destabilization from a positioned general base in the ketosteroid isomerase active site.

    PubMed

    Ruben, Eliza A; Schwans, Jason P; Sonnett, Matthew; Natarajan, Aditya; Gonzalez, Ana; Tsai, Yingssu; Herschlag, Daniel

    2013-02-12

    We compared the binding affinities of ground state analogues for bacterial ketosteroid isomerase (KSI) with a wild-type anionic Asp general base and with uncharged Asn and Ala in the general base position to provide a measure of potential ground state destabilization that could arise from the close juxtaposition of the anionic Asp and hydrophobic steroid in the reaction's Michaelis complex. The analogue binding affinity increased ~1 order of magnitude for the Asp38Asn mutation and ~2 orders of magnitude for the Asp38Ala mutation, relative to the affinity with Asp38, for KSI from two sources. The increased level of binding suggests that the abutment of a charged general base and a hydrophobic steroid is modestly destabilizing, relative to a standard state in water, and that this destabilization is relieved in the transition state and intermediate in which the charge on the general base has been neutralized because of proton abstraction. Stronger binding also arose from mutation of Pro39, the residue adjacent to the Asp general base, consistent with an ability of the Asp general base to now reorient to avoid the destabilizing interaction. Consistent with this model, the Pro mutants reduced or eliminated the increased level of binding upon replacement of Asp38 with Asn or Ala. These results, supported by additional structural observations, suggest that ground state destabilization from the negatively charged Asp38 general base provides a modest contribution to KSI catalysis. They also provide a clear illustration of the well-recognized concept that enzymes evolve for catalytic function and not, in general, to maximize ground state binding. This ground state destabilization mechanism may be common to the many enzymes with anionic side chains that deprotonate carbon acids.

  4. Electron Impact Excitation of Xenon from the Ground State and the Metastable State to the 5p57p Levels

    NASA Astrophysics Data System (ADS)

    Chen, Zhan-Bin; Dong, Chen-Zhong; Xie, Lu-You; Jiang, Jun

    2014-03-01

    Electron impact excitation cross sections from the ground state and the lowest metastable state 5p56s J = 2 to the excited states of the 5p57p configuration of xenon are calculated systematically using the fully relativistic distorted wave method. Special attention is paid to the configuration interaction effects in the wave-function expansion of target states. The results are in good agreement with the recent experimental data by Jung et al. [Phys. Rev. A 80 (2009) 062708] over the measured energy range. These accurate theoretical results can be used in the modeling and diagnosis of plasmas containing xenon.

  5. Autioionizing states in the photionization of the 3s(2)3p(4) (3)Pe ground state of sulfur

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    1988-01-01

    The partial and total photoionization cross sections for the S(3s/2/3p/4/ /3/Pe) ground state are calculated in both the dipole length and velocity forms. The prominent features in the cross sections are the autoionization Rydberg series converging to S+(3s/2/p/3/ /2/D/0/, /2/P/0/) excited-state thresholds. The results are pertinent to the study of sulfur in the plasma of Jupiter's satellite Io.

  6. A vacuum spark ion source: High charge state metal ion beams

    NASA Astrophysics Data System (ADS)

    Yushkov, G. Yu.; Nikolaev, A. G.; Oks, E. M.; Frolova, V. P.

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  7. A vacuum spark ion source: High charge state metal ion beams

    SciTech Connect

    Yushkov, G. Yu. Nikolaev, A. G.; Frolova, V. P.; Oks, E. M.

    2016-02-15

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  8. Production of Ultracold, Absolute Vibrational Ground State Sodium-Cesium Molecules

    NASA Astrophysics Data System (ADS)

    Zabawa, Patrick J.

    This dissertation describes a progression of experiments that are based on the association of ultracold (˜250 muK) Na and Cs atoms with laser light. One of the primary goals of the experiment is to form molecules in the absolute vibrational ground state. The work begins with our attempts to label, with certainty, spectral lines obtained from tuning either the photoassociation (PA formation) and Resonance Enhanced Multi-Photon Ionization (REMPI detection) lasers. To this end, we develop a technique that has heretofore never been used in the ultracold molecule community: pulsed depletion spectroscopy (PDS). Traditionally, depletion spectroscopy involves the use of narrow-linewidth CW lasers. However, the narrow linewidth and limited tuning ranges of diodes used for CW depletion spectroscopy mean that this technique is only helpful if the expected transitions are known to some degree in advance, and even then is primarily useful for determining closely-spaced rotational ground state populations. In contrast, the broad linewidth and flexible tuning range of a pulsed dye laser makes it suitable for the detection of vibrational progressions, allowing fast determination of ground state populations even without a priori knowledge of the transitions involved. We also use this technique in our investigation of excited state potential energy curves (PECs). We also investigate a range of PA resonances detuned from the Cs D1 and D2 lines. We find and label PA structure associated with at least 6, and possibly all 8 electronic states corresponding to both of the Cs 6P fine structure asymptotes. From the PA and depletion spectra, we obtain information on the PA scattering process and the excited electronic states. Among the PA spectra, we find several channels which directly form vibrational ground state molecules in the singlet electronic state. Finally, we manipulate the internal states of molecules created with PA using laser light. We use broadband laser sources to pump

  9. Rayleigh approximation to ground state of the Bose and Coulomb glasses

    NASA Astrophysics Data System (ADS)

    Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.

    2015-01-01

    Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Our findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties.

  10. Rayleigh approximation to ground state of the Bose and Coulomb glasses

    DOE PAGES

    Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; ...

    2015-01-16

    Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Ourmore » findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties.« less

  11. Historical Analysis and Charaterization of Ground Level Ozone for Canada and United State

    NASA Astrophysics Data System (ADS)

    Lin, H.; Li, H.; Auld, H.

    2003-12-01

    Ground-level ozone has long been recognized as an important health and ecosystem-related air quality concern in Canada and the United States. In this work we seek to understand the characteristics of ground level ozone conditions for Canada and United States to support the Ozone Annex under the Canada-U.S. Air Quality Agreement. Our analyses are based upon the data collected by Canadian National Air Pollution Surveillance (NAPS, the NAPS database has also been expanded to include U.S. EPA ground level ozone data) network. Historical ozone data from 1974 to 2002 at a total of 538 stations (253 Canadian stations and 285 U.S. stations) were statistically analyzed using several methodologies including the Canada Wide Standard (CWS). A more detailed analysis including hourly, daily, monthly, seasonally and yearly ozone concentration distributions and trends was undertaken for 54 stations.

  12. Bibliography on ground water in glacial-aquifer systems in the Northeastern United States

    USGS Publications Warehouse

    Wiltshire, Denise A.; Lyford, Forest P.; Cohen, A.J.

    1986-01-01

    The U.S. Geological Survey established the Regional Aquifer-System Analysis (RASA) program to evaluate major interconnected aquifers or groups of aquifers that share similar characteristics within a region. One of the objectives of the Northeastern Glacial RASA is to provide information on the occurrence and quality of ground water in glacial deposits in ten States: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, Ohio, Pennsylvania, and New Jersey. To help meet the objectives of the RASA program, an automated bibliographic data base was developed. The data base contains references to ground-water resources of glacial-aquifer systems in the ten States listed above. This bibliography contains more than 700 ground-water related references that date from 1839 through 1984. The bibliography lists books, journal articles, conference proceedings, government and other technical reports, theses, and maps. Unpublished manuscripts, publications in press, newspaper articles, and book reviews are omitted from the bibliography.

  13. Rayleigh approximation to ground state of the Bose and Coulomb glasses

    SciTech Connect

    Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.

    2015-01-16

    Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Our findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties.

  14. Systematic study of α preformation probability of nuclear isomeric and ground states

    NASA Astrophysics Data System (ADS)

    Sun, Xiao-Dong; Wu, Xi-Jun; Zheng, Bo; Xiang, Dong; Guo, Ping; Li, Xiao-Hua

    2017-01-01

    In this paper, based on the two-potential approach combining with the isospin dependent nuclear potential, we systematically compare the α preformation probabilities of odd-A nuclei between nuclear isomeric states and ground states. The results indicate that during the process of α particle preforming, the low lying nuclear isomeric states are similar to ground states. Meanwhile, in the framework of single nucleon energy level structure, we find that for nuclei with nucleon number below the magic numbers, the α preformation probabilities of high-spin states seem to be larger than low ones. For nuclei with nucleon number above the magic numbers, the α preformation probabilities of isomeric states are larger than those of ground states. Supported by National Natural Science Foundation of China (11205083), Construct Program of Key Discipline in Hunan Province, Research Foundation of Education Bureau of Hunan Province, China (15A159), Natural Science Foundation of Hunan Province, China (2015JJ3103, 2015JJ2123), Innovation Group of Nuclear and Particle Physics in USC, Hunan Provincial Innovation Foundation for Postgraduate (CX2015B398)

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

    NASA Astrophysics Data System (ADS)

    Wu, Ling-Na; You, Li

    2016-05-01

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

  16. Topological characterization of fractional quantum Hall ground states from microscopic Hamiltonians.

    PubMed

    Zaletel, Michael P; Mong, Roger S K; Pollmann, Frank

    2013-06-07

    We show how to numerically calculate several quantities that characterize topological order starting from a microscopic fractional quantum Hall Hamiltonian. To find the set of degenerate ground states, we employ the infinite density matrix renormalization group method based on the matrix-product state representation of fractional quantum Hall states on an infinite cylinder. To study localized quasiparticles of a chosen topological charge, we use pairs of degenerate ground states as boundary conditions for the infinite density matrix renormalization group. We then show that the wave function obtained on the infinite cylinder geometry can be adapted to a torus of arbitrary modular parameter, which allows us to explicitly calculate the non-Abelian Berry connection associated with the modular T transformation. As a result, the quantum dimensions, topological spins, quasiparticle charges, chiral central charge, and Hall viscosity of the phase can be obtained using data contained entirely in the entanglement spectrum of an infinite cylinder.

  17. Solvent dependence of ultrafast ground state recovery of the triphenylmethane dyes, brilliant green and malachite green

    NASA Astrophysics Data System (ADS)

    Nagasawa, Yutaka; Ando, Yoshito; Okada, Tadashi

    1999-10-01

    We have studied femtosecond ground state recovery dynamics of the triphenylmethane dyes brilliant green (BG) and malachite green (MG) by pump-probe spectroscopy at the center wavelength of 635 nm with a time resolution of 33 fs. The ultrafast recovery of the ground state bleach was highly nonexponential and depended on the solvent viscosity, although all time constants were shorter than the solvation times obtained from other measurements. We observed a plateau or a rise component in the signal, which indicates an intermediate state. The rise time showed a viscosity dependence, even in the ultrafast time domain. It should be noted that the decay times were always longer for BG than MG, while the rise time did not show a solute dependence. The torsional motion of the amino-substituted phenyl group may be involved in the ultrafast process to the intermediate state, but lack of a solute dependence indicates that only a small conformational change is involved.

  18. Optomechanical sideband cooling of a micromechanical oscillator close to the quantum ground state

    SciTech Connect

    Riviere, R.; Deleglise, S.; Weis, S.; Schliesser, A.; Kippenberg, T. J.; Gavartin, E.; Arcizet, O.

    2011-06-15

    Cooling a mesoscopic mechanical oscillator to its quantum ground state is elementary for the preparation and control of quantum states of mechanical objects. Here, we pre-cool a 70-MHz micromechanical silica oscillator to an occupancy below 200 quanta by thermalizing it with a 600-mK cold {sup 3}He gas. Two-level-system induced damping via structural defect states is shown to be strongly reduced and simultaneously serves as a thermometry method to independently quantify excess heating due to the cooling laser. We demonstrate that dynamical back action optical sideband cooling can reduce the average occupancy to 9{+-}1 quanta, implying that the mechanical oscillator can be found (10{+-}1)% of the time in its quantum ground state.

  19. Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

    SciTech Connect

    Ralchenko, Yu. Janev, R.K.; Kato, T.; Fursa, D.V.; Bray, I.; Heer, F.J. de

    2008-07-15

    Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n{<=}4 are treated individually, while the states with n{>=}5 are considered degenerate. For the processes involving transitions to and from n{>=}5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form.

  20. Microwave Spectroscopic Study of NiF in the Electronic Ground and Lowest Excited States.

    PubMed

    Tanimoto, Mitsutoshi; Sakamaki, Toru; Okabayashi, Toshiaki

    2001-05-01

    The rotational spectra of NiF in the electronic ground (2)Pi state and the lowest electronically excited (2)Sigma state have been observed. The source of nickel atom was sputtering from a nickel electrode or nickel powder placed on a stainless steel electrode. The molecular constants have been determined by a least-squares analysis of the observed transition frequencies. The rapid increase in the Lambda-type splittings in the ground state reveals that the observed rotational transitions are ascribed to the spin substate (2)Pi(3/2). The rotational transitions corresponding to the other substate,(2)Pi(1/2), have not been observed. The large spin-rotation interaction constant gamma in the electronically excited (2)Sigma state is consistent with that from the electronic spectroscopy. Copyright 2001 Academic Press.

  1. Effect of temperature on the single-particle ground-state energy of a polar quantum dot with Gaussian confinement

    SciTech Connect

    Jahan, Luhluh K. Chatterjee, Ashok

    2016-05-23

    The temperature and size dependence of the ground-state energy of a polaron in a Gaussian quantum dot have been investigated by using a variational technique. It is found that the ground-state energy increases with increasing temperature and decreases with the size of the quantum dot. Also, it is found that the ground-state energy is larger for a three-dimensional quantum dot as compared to a two-dimensional dot.

  2. Conserved prosegment residues stabilize a late-stage folding transition state of pepsin independently of ground states.

    PubMed

    Dee, Derek R; Horimoto, Yasumi; Yada, Rickey Y

    2014-01-01

    The native folding of certain zymogen-derived enzymes is completely dependent upon a prosegment domain to stabilize the folding transition state, thereby catalyzing the folding reaction. Generally little is known about how the prosegment accomplishes this task. It was previously shown that the prosegment catalyzes a late-stage folding transition between a stable misfolded state and the native state of pepsin. In this study, the contributions of specific prosegment residues to catalyzing pepsin folding were investigated by introducing individual Ala substitutions and measuring the effects on the bimolecular folding reaction between the prosegment peptide and pepsin. The effects of mutations on the free energies of the individual misfolded and native ground states and the transition state were compared using measurements of prosegment-pepsin binding and folding kinetics. Five out of the seven prosegment residues examined yielded relatively large kinetic effects and minimal ground state perturbations upon mutation, findings which indicate that these residues form strengthened and/or non-native contacts in the transition state. These five residues are semi- to strictly conserved, while only a non-conserved residue had no kinetic effect. One conserved residue was shown to form native structure in the transition state. These results indicated that the prosegment, which is only 44 residues long, has evolved a high density of contacts that preferentially stabilize the folding transition state over the ground states. It is postulated that the prosegment forms extensive non-native contacts during the process of catalyzing correct inter- and intra-domain contacts during the final stages of folding. These results have implications for understanding the folding of multi-domain proteins and for the evolution of prosegment-catalyzed folding.

  3. Conserved Prosegment Residues Stabilize a Late-Stage Folding Transition State of Pepsin Independently of Ground States

    PubMed Central

    Dee, Derek R.; Horimoto, Yasumi; Yada, Rickey Y.

    2014-01-01

    The native folding of certain zymogen-derived enzymes is completely dependent upon a prosegment domain to stabilize the folding transition state, thereby catalyzing the folding reaction. Generally little is known about how the prosegment accomplishes this task. It was previously shown that the prosegment catalyzes a late-stage folding transition between a stable misfolded state and the native state of pepsin. In this study, the contributions of specific prosegment residues to catalyzing pepsin folding were investigated by introducing individual Ala substitutions and measuring the effects on the bimolecular folding reaction between the prosegment peptide and pepsin. The effects of mutations on the free energies of the individual misfolded and native ground states and the transition state were compared using measurements of prosegment-pepsin binding and folding kinetics. Five out of the seven prosegment residues examined yielded relatively large kinetic effects and minimal ground state perturbations upon mutation, findings which indicate that these residues form strengthened and/or non-native contacts in the transition state. These five residues are semi- to strictly conserved, while only a non-conserved residue had no kinetic effect. One conserved residue was shown to form native structure in the transition state. These results indicated that the prosegment, which is only 44 residues long, has evolved a high density of contacts that preferentially stabilize the folding transition state over the ground states. It is postulated that the prosegment forms extensive non-native contacts during the process of catalyzing correct inter- and intra-domain contacts during the final stages of folding. These results have implications for understanding the folding of multi-domain proteins and for the evolution of prosegment-catalyzed folding. PMID:24983988

  4. Magnetostriction-driven ground-state stabilization in 2H perovskites

    DOE PAGES

    Porter, D. G.; Senn, M. S.; Khalyavin, D. D.; ...

    2016-10-04

    In this paper, the magnetic ground state of Sr3ARuO6, with A =(Li,Na), is studied using neutron diffraction, resonant x-ray scattering, and laboratory characterization measurements of high-quality crystals. Combining these results allows us to observe the onset of long-range magnetic order and distinguish the symmetrically allowed magnetic models, identifying in-plane antiferromagnetic moments and a small ferromagnetic component along the c axis. While the existence of magnetic domains masks the particular in-plane direction of the moments, it has been possible to elucidate the ground state using symmetry considerations. We find that due to the lack of local anisotropy, antisymmetric exchange interactions controlmore » the magnetic order, first through structural distortions that couple to in-plane antiferromagnetic moments and second through a high-order magnetoelastic coupling that lifts the degeneracy of the in-plane moments. Finally, the symmetry considerations used to rationalize the magnetic ground state are very general and will apply to many systems in this family, such as Ca3ARuO6, with A = (Li,Na), and Ca3LiOsO6 whose magnetic ground states are still not completely understood.« less

  5. Meta-Atom Behavior in Clusters Revealing Large Spin Ground States.

    PubMed

    Hernández Sánchez, Raúl; Betley, Theodore A

    2015-11-04

    The field of single molecule magnetism remains predicated on super- and double exchange mechanisms to engender large spin ground states. An alternative approach to achieving high-spin architectures involves synthesizing weak-field clusters featuring close M-M interactions to produce a single valence orbital manifold. Population of this orbital manifold in accordance with Hund's rules could potentially yield thermally persistent high-spin ground states under which the valence electrons remain coupled. We now demonstrate this effect with a reduced hexanuclear iron cluster that achieves an S = 19/2 (χ(M)T ≈ 53 cm(3) K/mol) ground state that persists to 300 K, representing the largest spin ground state persistent to room temperature reported to date. The reduced cluster displays single molecule magnet behavior manifest in both variable-temperature zero-field (57)Fe Mössbauer and magnetometry with a spin reversal barrier of 42.5(8) cm(-1) and a magnetic blocking temperature of 2.9 K (0.059 K/min).

  6. Magnetostriction-driven ground-state stabilization in 2H perovskites

    NASA Astrophysics Data System (ADS)

    Porter, D. G.; Senn, M. S.; Khalyavin, D. D.; Cortese, A.; Waterfield-Price, N.; Radaelli, P. G.; Manuel, P.; zur-Loye, H.-C.; Mazzoli, C.; Bombardi, A.

    2016-10-01

    The magnetic ground state of Sr3A RuO6 , with A =(Li ,Na ) , is studied using neutron diffraction, resonant x-ray scattering, and laboratory characterization measurements of high-quality crystals. Combining these results allows us to observe the onset of long-range magnetic order and distinguish the symmetrically allowed magnetic models, identifying in-plane antiferromagnetic moments and a small ferromagnetic component along the c axis. While the existence of magnetic domains masks the particular in-plane direction of the moments, it has been possible to elucidate the ground state using symmetry considerations. We find that due to the lack of local anisotropy, antisymmetric exchange interactions control the magnetic order, first through structural distortions that couple to in-plane antiferromagnetic moments and second through a high-order magnetoelastic coupling that lifts the degeneracy of the in-plane moments. The symmetry considerations used to rationalize the magnetic ground state are very general and will apply to many systems in this family, such as Ca3A RuO6 , with A =(Li ,Na ) , and Ca3LiOsO6 whose magnetic ground states are still not completely understood.

  7. Magnetic ground state of an individual Fe2+ ion in strained semiconductor nanostructure

    NASA Astrophysics Data System (ADS)

    Smoleński, T.; Kazimierczuk, T.; Kobak, J.; Goryca, M.; Golnik, A.; Kossacki, P.; Pacuski, W.

    2016-01-01

    Single impurities with nonzero spin and multiple ground states offer a degree of freedom that can be utilized to store the quantum information. However, Fe2+ dopant is known for having a single nondegenerate ground state in the bulk host semiconductors and thus is of little use for spintronic applications. Here we show that the well-established picture of Fe2+ spin configuration can be modified by subjecting the Fe2+ ion to high strain, for example, produced by lattice mismatched epitaxial nanostructures. Our analysis reveals that high strain induces qualitative change in the ion energy spectrum and results in nearly doubly degenerate ground state with spin projection Sz=+/-2. We provide an experimental proof of this concept using a new system: a strained epitaxial quantum dot containing individual Fe2+ ion. Magnetic character of the Fe2+ ground state in a CdSe/ZnSe dot is revealed in photoluminescence experiments by exploiting a coupling between a confined exciton and the single-iron impurity. We also demonstrate that the Fe2+ spin can be oriented by spin-polarized excitons, which opens a possibility of using it as an optically controllable two-level system free of nuclear spin fluctuations.

  8. Lossless anomalous dispersion and an inversionless gain doublet via dressed interacting ground states

    SciTech Connect

    Weatherall, James Owen; Search, Christopher P.

    2010-02-15

    Transparent media exhibiting anomalous dispersion have been of considerable interest since Wang, Kuzmich, and Dogariu [Nature 406, 277 (2000)] first observed light propagate with superluminal and negative group velocities without absorption. Here, we propose an atomic model exhibiting these properties, based on a generalization of amplification without inversion in a five-level dressed interacting ground-state system. The system consists of a {Lambda} atom prepared as in standard electromagnetically induced transparency (EIT), with two additional metastable ground states coupled to the {Lambda} atom ground states by two rf-microwave fields. We consider two configurations by which population is incoherently pumped into the ground states of the atom. Under appropriate circumstances, we predict a pair of new gain lines with tunable width, separation, and height. Between these lines, absorption vanishes but dispersion is large and anomalous. The system described here is a significant improvement over other proposals in the anomalous dispersion literature in that it permits additional coherent control over the spectral properties of the anomalous region, including a possible 10{sup 4}-fold increase over the group delay observed by Wang, Kuzmich, and Dogariu.

  9. Magnetostriction-driven ground-state stabilization in 2H perovskites

    SciTech Connect

    Porter, D. G.; Senn, M. S.; Khalyavin, D. D.; Cortese, A.; Waterfield-Price, N.; Radaelli, P. G.; Manuel, P.; zur-Loye, H. -C.; Mazzoli, C.; Bombardi, A.

    2016-10-04

    In this paper, the magnetic ground state of Sr3ARuO6, with A =(Li,Na), is studied using neutron diffraction, resonant x-ray scattering, and laboratory characterization measurements of high-quality crystals. Combining these results allows us to observe the onset of long-range magnetic order and distinguish the symmetrically allowed magnetic models, identifying in-plane antiferromagnetic moments and a small ferromagnetic component along the c axis. While the existence of magnetic domains masks the particular in-plane direction of the moments, it has been possible to elucidate the ground state using symmetry considerations. We find that due to the lack of local anisotropy, antisymmetric exchange interactions control the magnetic order, first through structural distortions that couple to in-plane antiferromagnetic moments and second through a high-order magnetoelastic coupling that lifts the degeneracy of the in-plane moments. Finally, the symmetry considerations used to rationalize the magnetic ground state are very general and will apply to many systems in this family, such as Ca3ARuO6, with A = (Li,Na), and Ca3LiOsO6 whose magnetic ground states are still not completely understood.

  10. Complete α6 m Corrections to the Ground State of H2

    NASA Astrophysics Data System (ADS)

    Puchalski, Mariusz; Komasa, Jacek; Czachorowski, Paweł; Pachucki, Krzysztof

    2016-12-01

    We perform the calculation of all relativistic and quantum electrodynamic corrections of the order of α6 m to the ground electronic state of a hydrogen molecule and present improved results for the dissociation and the fundamental transition energies. These results open the window for the high-precision spectroscopy of H2 and related low-energy tests of fundamental interactions.

  11. Magnetic ground state of an individual Fe2+ ion in strained semiconductor nanostructure

    PubMed Central

    Smoleński, T.; Kazimierczuk, T.; Kobak, J.; Goryca, M.; Golnik, A.; Kossacki, P.; Pacuski, W.

    2016-01-01

    Single impurities with nonzero spin and multiple ground states offer a degree of freedom that can be utilized to store the quantum information. However, Fe2+ dopant is known for having a single nondegenerate ground state in the bulk host semiconductors and thus is of little use for spintronic applications. Here we show that the well-established picture of Fe2+ spin configuration can be modified by subjecting the Fe2+ ion to high strain, for example, produced by lattice mismatched epitaxial nanostructures. Our analysis reveals that high strain induces qualitative change in the ion energy spectrum and results in nearly doubly degenerate ground state with spin projection Sz=±2. We provide an experimental proof of this concept using a new system: a strained epitaxial quantum dot containing individual Fe2+ ion. Magnetic character of the Fe2+ ground state in a CdSe/ZnSe dot is revealed in photoluminescence experiments by exploiting a coupling between a confined exciton and the single-iron impurity. We also demonstrate that the Fe2+ spin can be oriented by spin-polarized excitons, which opens a possibility of using it as an optically controllable two-level system free of nuclear spin fluctuations. PMID:26818580

  12. Use of ground-penetrating radar to study tree roots in the southeastern United States

    Treesearch

    John R. Butnor; J.A. Doolittle; L. Kress; Susan Cohen; Kurt H. Johnsen

    2001-01-01

    Summary: The objectives of our study were to assess the feasibility of using ground-penetrating radar (GPR) to study roots over a broad range of soil conditions in the southeastern United States. Study sites were located in the Southern Piedmont, Carolina Sandhills and Atlantic Coast Flatwoods. At each site, we tested for selection of the appropriate...

  13. Existence of ground state solutions to Dirac equations with vanishing potentials at infinity

    NASA Astrophysics Data System (ADS)

    Figueiredo, Giovany M.; Pimenta, Marcos T. O.

    2017-01-01

    In this work we study the existence of ground-state solutions of Dirac equations with potentials which are allowed to vanish at infinity. The approach is based on minimization of the energy functional over a generalized Nehari set. Some conditions on the potentials are given in order to overcome the lack of compactness.

  14. Measurement of rubidium ground-state hyperfine transition frequency using atomic fountains

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Yuri B.; Szymaniec, Krzysztof; Edris, Soliman

    2015-08-01

    The results of precision measurements of the 87Rb ground-state hyperfine transition frequency, which were conducted at NPL from 2009 to 2013, are reported. The resulting frequency, measured using NPL’s Cs and Rb atomic frequency standards, demonstrates reasonable agreement with the most recent measurements reported by LNE-SYRTE.

  15. Distribution of Elevated Nitrate Concentrations in Ground Water in Washington State

    USGS Publications Warehouse

    Frans, Lonna

    2008-01-01

    More than 60 percent of the population of Washington State uses ground water for their drinking and cooking needs. Nitrate concentrations in ground water are elevated in parts of the State as a result of various land-use practices, including fertilizer application, dairy operations and ranching, and septic-system use. Shallow wells generally are more vulnerable to nitrate contamination than deeper wells (Williamson and others, 1998; Ebbert and others, 2000). In order to protect public health, the Washington State Department of Health requires that public water systems regularly measure nitrate in their wells. Public water systems serving more than 25 people collect water samples at least annually; systems serving from 2 to 14 people collect water samples at least every 3 years. Private well owners serving one residence may be required to sample when the well is first drilled, but are unregulated after that. As a result, limited information is available to citizens and public health officials about potential exposure to elevated nitrate concentrations for people whose primary drinking-water sources are private wells. The U.S. Geological Survey and Washington State Department of Health collaborated to examine water-quality data from public water systems and develop models that calculate the probability of detecting elevated nitrate concentrations in ground water. Maps were then developed to estimate ground water vulnerability to nitrate in areas where limited data are available.

  16. Prevalence and Characterization of Salmonellae in Commercial Ground Beef in the United States

    USDA-ARS?s Scientific Manuscript database

    Commercially produced ground beef samples (n = 4,136) were collected from seven regions of the United States over a 24 month period (July 2005 to June 2007) and analyzed for the presence of Salmonella using methods to examine enumerable levels and total prevalence. All Salmonella isolated were sero...

  17. Hylleraas-configuration-interaction study of the {sup 1}S ground state of neutral beryllium

    SciTech Connect

    Sims, James S.; Hagstrom, Stanley A.

    2011-03-15

    Hylleraas-configuration-interaction (Hy-CI) method variational calculations are reported for the {sup 1}S ground state of neutral beryllium. The best nonrelativistic energy obtained was -14.667 356 4 hartree, which is estimated to be accurate to a tenth of a microhartree.

  18. On the ground state energy of the delta-function Fermi gas

    NASA Astrophysics Data System (ADS)

    Tracy, Craig A.; Widom, Harold

    2016-10-01

    The weak coupling asymptotics to order γ of the ground state energy of the delta-function Fermi gas, derived heuristically in the literature, is here made rigorous. Further asymptotics are in principle computable. The analysis applies to the Gaudin integral equation, a method previously used by one of the authors for the asymptotics of large Toeplitz matrices.

  19. Ground Based Reflectance Measurements of Arid Rangeland Vegetation Communities of the Southwestern United States

    USDA-ARS?s Scientific Manuscript database

    In 1997 a research program began using an Analytical Spectral Device (ASD-FR) spectroradiometer to collect ground based in situ radiance/reflectance measurements from vegetation communities typical of semiarid/arid rangelands of southwestern United States. Measurements were made after the spring (Ap...

  20. Creation of a strongly dipolar gas of ultracold ground-state 23 Na87 Rb molecules

    NASA Astrophysics Data System (ADS)

    Guo, Mingyang; Zhu, Bing; Lu, Bo; Ye, Xin; Wang, Fudong; Wang, Dajun; Vexiau, Romain; Bouloufa-Maafa, Nadia; Quéméner, Goulven; Dulieu, Olivier

    2016-05-01

    We report on successful creation of an ultracold sample of ground-state 23 Na87 Rb molecules with a large effective electric dipole moment. Through a carefully designed two-photon Raman process, we have successfully transferred the magneto-associated Feshbach molecules to the singlet ground state with high efficiency, obtaining up to 8000 23 Na87 Rb molecules with peak number density over 1011 cm-3 in their absolute ground-state level. With an external electric field, we have induced an effective dipole moment over 1 Debye, making 23 Na87 Rb the most dipolar ultracold particle ever achieved. Contrary to the expectation, we observed a rather fast population loss even for 23 Na87 Rb in the absolute ground state with the bi-molecular exchange reaction energetically forbidden. The origin for the short lifetime and possible ways of mitigating it are currently under investigation. Our achievements pave the way toward investigation of ultracold bosonic molecules with strong dipolar interactions. This work is supported by the Hong Kong RGC CUHK404712 and the ANR/RGC Joint Research Scheme ACUHK403/13.

  1. Mitigation of cross-beam energy transfer: Implication of two-state focal zooming on OMEGA

    SciTech Connect

    Froula, D. H.; Kessler, T. J.; Igumenshchev, I. V.; Betti, R.; Goncharov, V. N.; Huang, H.; Hu, S. X.; Hill, E.; Kelly, J. H.; Meyerhofer, D. D.; Shvydky, A.; Zuegel, J. D.

    2013-08-15

    Cross-beam energy transfer (CBET) during OMEGA low-adiabat cryogenic experiments reduces the hydrodynamic efficiency by ∼35%, which lowers the calculated one-dimensional (1-D) yield by a factor of 7. CBET can be mitigated by reducing the diameter of the laser beams relative to the target diameter. Reducing the diameter of the laser beams by 30%, after a sufficient conduction zone has been generated (two-state zooming), is predicted to maintain low-mode uniformity while recovering 90% of the kinetic energy lost to CBET. A radially varying phase plate is proposed to implement two-state zooming on OMEGA. A beam propagating through the central half-diameter of the phase plate will produce a large spot, while a beam propagating through the outer annular region of the phase plate will produce a narrower spot. To generate the required two-state near-field laser-beam profile, a picket driver with smoothing by spectral dispersion (SSD) would pass through an apodizer, forming a beam of half the standard diameter. A second main-pulse driver would co-propagate without SSD through its own apodizer, forming a full-diameter annular beam. Hydrodynamic simulations, using the designed laser spots produced by the proposed zooming scheme on OMEGA, show that implementing zooming will increase the implosion velocity by 25% resulting in a 4.5× increase in the 1-D neutron yield. Demonstrating zooming on OMEGA would validate a viable direct-drive CBET mitigation scheme and help establish a pathway to hydrodynamically equivalent direct-drive–ignition implosions by increasing the ablation pressure (1.6×), which will allow for more stable implosions at ignition-relevant velocities.

  2. The magnetic structure on the ground state of the equilateral triangular spin tube

    NASA Astrophysics Data System (ADS)

    Matsui, Kazuki; Goto, Takayuki; Manaka, Hirotaka; Miura, Yoko

    2016-12-01

    The ground state of the frustrated equilateral triangular spin tube CsCrF4 is still hidden behind a veil though NMR spectrum broaden into 2 T at low temperature. In order to investigate the spin structure in an ordered state by 19F-NMR, we have determined the anisotropic hyperfine coupling tensors for each three fluorine sites in the paramagnetic state. The measurement field was raised up to 10 T to achieve highest resolution. The preliminary analysis using the obtained hyperfine tensors has shown that the archetypal 120°-type structure in ab-plane does not accord with the NMR spectra of ordered state.

  3. Two-photon pathway to ultracold ground state molecules of 23Na40K

    NASA Astrophysics Data System (ADS)

    Park, Jee Woo; Will, Sebastian A.; Zwierlein, Martin W.

    2015-07-01

    We report on high-resolution spectroscopy of ultracold fermionic 23Na40K Feshbach molecules, and identify a two-photon pathway to the rovibrational singlet ground state via a resonantly mixed B1Π ˜ c3Σ+intermediate state. Photoassociation in a 23Na-40K atomic mixture and one-photon spectroscopy on 23Na40K Feshbach molecules reveal about 20 vibrational levels of the electronically excited c3Σ+state. Two of these levels are found to be strongly perturbed by nearby B1Π levels via spin-orbit coupling, resulting in additional lines of dominant singlet character in the perturbed complex {{{B}}}1\\Pi | v=4> ˜ {{{c}}}3{Σ }+| v=25> , or of resonantly mixed character in {{{B}}}1\\Pi | v=12> ˜ {{{c}}}3{Σ }+| v=35> . The dominantly singlet level is used to locate the absolute rovibrational singlet ground state {{{X}}}1{Σ }+| v=0,J=0> via Autler-Townes spectroscopy. We demonstrate coherent two-photon coupling via dark state spectroscopy between the predominantly triplet Feshbach molecular state and the singlet ground state. Its binding energy is measured to be 5212.0447(1) cm-1, a thousand-fold improvement in accuracy compared to previous determinations. In their absolute singlet ground state, 23Na40K molecules are chemically stable under binary collisions and possess a large electric dipole moment of 2.72 Debye. Our work thus paves the way towards the creation of strongly dipolar Fermi gases of NaK molecules.

  4. Evolution of the Hox gene complex from an evolutionary ground state.

    PubMed

    Gehring, Walter J; Kloter, Urs; Suga, Hiroshi

    2009-01-01

    In this chapter, we consider the question of how the ordered clusters of Hox genes arose during evolution. Since ordered Hox clusters are found in all major superphyla, we have to assume that the Hox clusters arose before the Cambrian "explosion" giving rise to all of these taxa. Based on his studies of the bithorax complex (BX-C) in Drosophila Lewis considered the ground state to be the mesothoracic segment (T2) since the deletion of all of the genes of the BX-C leads to a transformation of all segments from T3 to A8/9 (the last abdominal segment) into T2 segments. We define the developmental ground state genetically, by assuming that loss-of-function mutants lead to transformations toward the ground state, whereas gain-of-function mutants lead to homeotic transformations away from the ground state. By this definition, T2 also represents the developmental ground state, if one includes the anterior genes, that is, those of the Antennapedia complex. We have reconstructed the evolution of the Hox cluster on the basis of known genetic mechanisms which involve unequal crossover and lead from an urhox gene, first to an anterior and a posterior gene and subsequently to intermediate genes which are progressively inserted, between the anterior and posterior genes. These intermediate genes are recombinant due to unequal crossover, whereas the anterior and posterior genes are not affected and therefore had the longest time to diverge from the urhox gene. The molecular phylogenetic analysis strongly supports this model. We consider the ground state to be both developmental and evolutionary and to represent the prototypic body segment. It corresponds to T2 and is specified by Antennapedia or Hox6, respectively. Experiments in the mouse also suggest that the ground state is a thoracic segment. Evolution leads from the prototypic segment to segmental divergence in both the anterior and posterior direction. The most anterior head and tail segments are specified by homeobox genes

  5. B2N2O4: Prediction of a Magnetic Ground State for a Light Main-Group Molecule

    SciTech Connect

    Varga, Zoltan; Truhlar, Donald G.

    2015-09-08

    Cyclobutanetetrone, (CO)4, has a triplet ground state. Here we predict, based on electronic structure calculations, that the B2N2O4 molecule also has a triplet ground state and is therefore paramagnetic; the structure is an analogue of (CO)4 in which the carbon ring is replaced by a (BN)2 ring. Similar to (CO)4, the triplet ground-state structure of B2N2O4 is also thermodynamically unstable. Besides analysis of the molecular orbitals, we found that the partial atomic charges are good indicators for predicting magnetic ground states.

  6. Conservation relation of nonclassicality and entanglement for Gaussian states in a beam splitter

    NASA Astrophysics Data System (ADS)

    Ge, Wenchao; Tasgin, Mehmet Emre; Zubairy, M. Suhail

    2015-11-01

    We study the relation between single-mode nonclassicality and two-mode entanglement in a beam splitter. We show that single-mode nonclassicality (the entanglement potential) of incident light cannot be transformed into two-mode entanglement completely after a single beam splitter. Some of the entanglement potential remains as single-mode nonclassicality in the two entangled output modes. Two-mode entanglement generated in the process can be equivalently quantified as an increase in the minimum uncertainty widths (or decrease in the squeezing) of the output states compared to the input states. We use the nonclassical depth and logarithmic negativity as single-mode nonclassicality and entanglement measures, respectively. We realize that a conservation relation between the two quantities can be adopted for Gaussian states, if one works in terms of uncertainty width. This conservation relation is extended to many sets of beam splitters.

  7. Observation of acoustic valley vortex states and valley-chirality locked beam splitting

    NASA Astrophysics Data System (ADS)

    Ye, Liping; Qiu, Chunyin; Lu, Jiuyang; Wen, Xinhua; Shen, Yuanyuan; Ke, Manzhu; Zhang, Fan; Liu, Zhengyou

    2017-05-01

    We report an experimental observation of the classical version of valley polarized states in a two-dimensional hexagonal sonic crystal. The acoustic valley states, which carry specific linear momenta and orbital angular momenta, were selectively excited by external Gaussian beams and conveniently confirmed by the pressure distribution outside the crystal, according to the criterion of momentum conservation. The vortex nature of such intriguing bulk crystal states was directly characterized by scanning the phase profile inside the crystal. In addition, we observed a peculiar beam-splitting phenomenon, in which the separated beams are constructed by different valleys and locked to the opposite vortex chirality. The exceptional sound transport, encoded with valley-chirality locked information, may serve as the basis of designing conceptually interesting acoustic devices with unconventional functions.

  8. Steady state performance test analysis of actively cooled extractor grids for SST-1 neutral beam injector

    SciTech Connect

    Jana, M. R.; Mattoo, S. K.; Khan, M.

    2010-11-15

    Neutral beam injection (NBI) system is a workhorse to heat magnetically confined tokamak fusion plasma. The heart of any NBI system is an ion extractor system. Steady State Superconducting Tokamak-1 (SST-1) needs 0.5 MW of hydrogen beam power at 30 kV to raise the plasma ion temperature to {approx}1 keV and 1.7 MW of hydrogen beam power at 55 kV for future upgradation. To meet this requirement, an ion extractor system consisting of three actively cooled grids has been designed, fabricated, and its performance test has been done at MARION test stand, IPP, Julich, Germany. During long pulse (14 s) operation, hydrogen ion beam of energy 31 MJ has been extracted at 41 kV. In this paper, we have presented detailed analysis of calorimetric data of actively cooled extractor grids and showed that by monitoring outlet water temperature, grid material temperature can be monitored for safe steady state operation of a NBI system. Steady state operation of NBI is the present day interest of fusion research. In the present experimental case, performance test analysis indicates that the actively cooled grids attain steady state heat removal condition and the grid material temperature rise is {approx}18 deg. C and saturates after 10 s of beam pulse.

  9. Steady state performance test analysis of actively cooled extractor grids for SST-1 neutral beam injector.

    PubMed

    Jana, M R; Mattoo, S K; Khan, M

    2010-11-01

    Neutral beam injection (NBI) system is a workhorse to heat magnetically confined tokamak fusion plasma. The heart of any NBI system is an ion extractor system. Steady State Superconducting Tokamak-1 (SST-1) needs 0.5 MW of hydrogen beam power at 30 kV to raise the plasma ion temperature to ~1 keV and 1.7 MW of hydrogen beam power at 55 kV for future upgradation. To meet this requirement, an ion extractor system consisting of three actively cooled grids has been designed, fabricated, and its performance test has been done at MARION test stand, IPP, Julich, Germany. During long pulse (14 s) operation, hydrogen ion beam of energy 31 MJ has been extracted at 41 kV. In this paper, we have presented detailed analysis of calorimetric data of actively cooled extractor grids and showed that by monitoring outlet water temperature, grid material temperature can be monitored for safe steady state operation of a NBI system. Steady state operation of NBI is the present day interest of fusion research. In the present experimental case, performance test analysis indicates that the actively cooled grids attain steady state heat removal condition and the grid material temperature rise is ~18°C and saturates after 10 s of beam pulse.

  10. Developing a state water plan: Ground-water conditions in Utah, spring of 1970

    USGS Publications Warehouse

    Sumison, C.T.; Bjorklund, L.J.; Bolke, E.L.; Mower, R.W.; Herbert, L.R.; Cordova, R.M.; Butler, R.G.; Sandberg, G.W.

    1970-01-01

    This report is the seventh in a series of annual reports that describe ground-water conditions in Utah. Reports in this series are prepared cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources and are designed to provide data to enable interested parties such as legislators, administrators, and planners to keep abreast of changing ground-water conditions.This report, like the others (see references, p. 22), contains information on well construction, ground-water withdrawals, water-level changes, and related changes in precipitation and streamflow. It also contains supplementary data that are related to ground-water use in some areas. In reports of this series, the inclusion of such supplementary data as graphs showing chemical quality of water and maps showing water-table configuration is intended only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.The report includes individual discussions of the most important areas of ground-water withdrawal in the State for the calendar year 1969. Water-level fluctuations, however, are described for the period spring 1969 to spring 1970. Many of the data used in the report were collected by the Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  11. Developing a state water plan: Ground-water conditions in Utah, spring of 1969

    USGS Publications Warehouse

    Baker, C.H.; Bjorklund, L.J.; Bolke, E.L.; Mower, R.W.; Herbert, L.R.; Cordova, R.M.; Butler, R.G.; Sandberg, G.W.

    1969-01-01

    This report is the sixth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series are prepared cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources and are designed to provide data to enable interested parties such as legislators, administrators, and planners to keep abreast of changing ground-water conditions.This report, like the others (see references, p. 12), contains information on well construction, ground-water withdrawals, water-level changes, and related changes in precipitation and streamflow. It also contains supplementary data that are related to ground-water use in some areas. In reports of this series, the inclusion of such supplementary data as graphs showing chemical quality of water and maps showing water-table configuration is intended only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.The report includes individual discussions of the most important areas of ground-water withdrawal in the State for the calendar year 1968. Water-level fluctuations, however, are described for the period spring 1968 to spring 1969. Many of the data used in the report were collected by the Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  12. Developing a state water plan: Ground-water conditions in Utah, spring of 1971

    USGS Publications Warehouse

    Cordova, R.M.; Bjorklund, L.J.; McGreevy, L.J.; Bolke, E.L.; Sumison, C.T.; Herbert, L.R.; Butler, R.G.; Mower, R.W.; Sandberg, G.W.; Adams, D.B.

    1971-01-01

    This report is the eighth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series are prepared cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources and are designed to provide data to enable interested parties such as legislators, administrators, and planners to keep abreast of changing ground-water conditions.This report, like the others (see references, p. 21), contains information on well construction, ground-water withdrawals, water-level changes, and related changes in precipitation and streamflow. It also contains supplementary data that are related to ground-water use in some areas. In reports of this series, the inclusion of such supplementary data as graphs showing chemical quality of water and maps showing water-table configuration is intended only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.The report includes individual discussions of the most important areas of ground-water withdrawal in the State for the calendar year 1970. Water-level fluctuations, however, are described for the period spring 1970 to spring 1971. Many of the data used in the report were collected by the Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  13. Developing a state water plan: Ground-water conditions in Utah, spring of 1984

    USGS Publications Warehouse

    Avery, Charles; Herbert, L.R.; Bischoff, Donald A.; Clark, David W.; Seiler, Ralph L.; Guttormson, Kevin; Elizondo, Melanie S.; Jensen, V.L.; Enright, Michael; Emett, D.C.; Burden, Carole B.; Eckenwiler, M.R.; Sandberg, G.W.

    1984-01-01

    This is the twenty-first in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawals from wells, water-level changes, and related changes in precipitation and streamflow. Supplementary data such as graphs showing chemical quality of water and maps showing ground-water level contours are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected major areas of ground-water development in the State for the calendar year 1983. Water-level fluctuations, however, are described from the spring of 1983 to the spring of 1984. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  14. Developing a state water plan: Ground-water conditions in Utah, spring of 1983

    USGS Publications Warehouse

    Appel, Cynthia L.; Herbert, L.R.; Bischoff, Donald A.; Smith, Melanie E.; Seiler, Ralph L.; Guttormson, Kevin; Jensen, V.L.; Enright, Michael; Emett, D.C.; Burden, Carole B.; Beard, R.C.; Sultz, L.G.; Eckenwiler, M.R.; Sandberg, G.W.

    1983-01-01

    This is the twentieth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawals from wells, water-level changes, and related changes in precipitation and streamflow. Supplementary data such as graphs showing chemical quality of water and maps showing ground-water level contours are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected major areas of ground-water development in the State for the calendar year 1982. Water-level fluctuations, however, are described for spring 1982 to spring 1983 and spring 1963 to spring 1983. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  15. Developing a state water plan: Ground-water conditions in Utah, spring of 1982

    USGS Publications Warehouse

    Holmes, Walter F.; Herbert, L.R.; Bischoff, D.A.; Smith, Melanie E.; Seiler, R.L.; Steiger, Judy I.; Appel, Cynthia L.; Jensen, V.L.; Enright, Michael; Emett, D.C.; Burden, Carole B.; Beard, R.C.; Sultz, L.G.; Eckenwiler, M.R.; Sandberg, G.W.

    1982-01-01

    This is the nineteenth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawals from wells, water-level changes, and related changes in precipitation and streamflow. Supplementary data such as graphs showing chemical quality of water and maps showing ground-water level contours are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected major areas of ground-water development in the State for the calendar year 1981. Water-level fluctuations, however, are described for the periiod spring 1981 to spring 1982. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  16. Developing a state water plan: Ground-water conditions in Utah, spring of 1985

    USGS Publications Warehouse

    Seiler, Ralph L.; Herbert, L.R.; Bischoff, Donald A.; Clark, David W.; Pyper, George; Burden, Carole B.; Jensen, V.L.; Enright, Michael; Emett, D.C.; Sether, B.A.; Eckenwiler, M.R.; Sandberg, G.W.

    1985-01-01

    This is the twenty-second in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawals from wells, water-level changes, and related changes in precipitation and streamflow. Supplementary data such as graphs showing chemical quality of water and maps showing ground-water level contours are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected major areas of ground-water development in the State for the calendar year 1984. Water-level fluctuations, however, are described from the spring of 1984 to the spring of 1985. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

  17. Long-range interactions between polar bialkali ground-state molecules in arbitrary vibrational levels

    NASA Astrophysics Data System (ADS)

    Vexiau, R.; Lepers, M.; Aymar, M.; Bouloufa-Maafa, N.; Dulieu, O.

    2015-06-01

    We have calculated the isotropic C6 coefficients characterizing the long-range van der Waals interaction between two identical heteronuclear alkali-metal diatomic molecules in the same arbitrary vibrational level of their ground electronic state X1Σ+. We consider the ten species made up of 7Li, 23Na, 39K, 87Rb, and 133Cs. Following our previous work [Lepers et al., Phys. Rev. A 88, 032709 (2013)], we use the sum-over-state formula inherent to the second-order perturbation theory, composed of the contributions from the transitions within the ground state levels, from the transition between ground-state and excited state levels, and from a crossed term. These calculations involve a combination of experimental and quantum-chemical data for potential energy curves and transition dipole moments. We also investigate the case where the two molecules are in different vibrational levels and we show that the Moelwyn-Hughes approximation is valid provided that it is applied for each of the three contributions to the sum-over-state formula. Our results are particularly relevant in the context of inelastic and reactive collisions between ultracold bialkali molecules in deeply bound or in Feshbach levels.

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

    NASA Astrophysics Data System (ADS)

    Wu, Ling-Na; You, L.

    2016-03-01

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

  19. Long-range interactions between polar bialkali ground-state molecules in arbitrary vibrational levels

    SciTech Connect

    Vexiau, R.; Lepers, M. Aymar, M.; Bouloufa-Maafa, N.; Dulieu, O.

    2015-06-07

    We have calculated the isotropic C{sub 6} coefficients characterizing the long-range van der Waals interaction between two identical heteronuclear alkali-metal diatomic molecules in the same arbitrary vibrational level of their ground electronic state X{sup 1}Σ{sup +}. We consider the ten species made up of {sup 7}Li, {sup 23}Na, {sup 39}K, {sup 87}Rb, and {sup 133}Cs. Following our previous work [Lepers et al., Phys. Rev. A 88, 032709 (2013)], we use the sum-over-state formula inherent to the second-order perturbation theory, composed of the contributions from the transitions within the ground state levels, from the transition between ground-state and excited state levels, and from a crossed term. These calculations involve a combination of experimental and quantum-chemical data for potential energy curves and transition dipole moments. We also investigate the case where the two molecules are in different vibrational levels and we show that the Moelwyn-Hughes approximation is valid provided that it is applied for each of the three contributions to the sum-over-state formula. Our results are particularly relevant in the context of inelastic and reactive collisions between ultracold bialkali molecules in deeply bound or in Feshbach levels.

  20. Static Properties and Stark Effect of the Ground State of the HD Molecular Ion

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Drachman, Richard J.

    1999-01-01

    We have calculated static properties of the ground state of the HD(+) ion and its lowest-lying P-state without making use of the Born-Oppenheimer approximation, as was done in the case of H2(+) and D2(+) [Phys. Rev. A 58, 2787 (1998)]. The ion is treated as a three-body system whose ground state is spherically symmetric. The wavefunction is of generalized Hylleraas type, but it is necessary to include high powers of the internuclear distance to localize the nuclear motion. We obtain good values of the energies of the ground S-state and lowest P-state and compare them with earlier calculations. Expectation values are obtained for various operators, the Fermi contact parameters, and the permanent quadrupole moment. The cusp conditions are also calculated. The polarizability was then calculated using second-order perturbation theory with intermediate P pseudostates. Since the nuclei in HD(+) are not of equal mass there is dipole coupling between the lowest two rotational states, which are almost degenerate. This situation is carefully analyzed, and the Stark shift is calculated variationally as a function of the applied electric field.