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1

The Ground State Energy of Heavy Atoms: the Leading Correction

For heavy atoms (large atomic number $Z$) described by no-pair operators in the Furry picture we find the ground state's leading energy correction. We compare the result with (semi-)empirical values and Schwinger's prediction showing more than qualitative agreement.

Michael Handrek; Heinz Siedentop

2014-11-21

2

Ground State Hyperfine Structure of Muonic Helium Atom

On the basis of the perturbation theory in the fine structure constant $\\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\\mu e ^4_2He)$. We obtain total result for the ground state hyperfine splitting $\\Delta \

A. A. Krutov; A. P. Martynenko

2008-07-21

3

Constrained molecular dynamics simulations of atomic ground states

The constrained molecular dynamics model, previously introduced for nuclear dynamics, has been extended to the atomic structure and collision calculations. Quantum effects, corresponding to the Pauli and Heisenberg principles, are enforced by constraints, following the idea of the Lagrange multiplier method. Our calculations for a small atomic system, H, He, Li, Be, and F reproduce the ground-state binding energies reasonably, compared with the experimental data. We discuss also the shell splitting due to e-e correlation.

Kimura, Sachie; Bonasera, Aldo [Laboratorio Nazionale del Sud, INFN, via Santa Sofia, 62, 95123 Catania (Italy)

2005-07-15

4

Determination of density of hydrogen atoms in the ground state

An improved electrical probe capable of measuring not only plasma density, electron temperature, and plasma potential, but also the density of neutral hydrogen atoms in the ground state is described. The probe is made of a small disc connected to a pair of thin thermo-couple wires. The disc is made of a material with a high recombination coefficient for the

M Mozeti?; M Drobni?; A Pregelj; K Zupan

1996-01-01

5

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

6

Measured atomic ground-state polarizabilities of 35 metallic elements

NASA Astrophysics Data System (ADS)

Advanced pulsed cryogenic molecular-beam electric deflection methods involving position-sensitive mass spectrometry and 7.87-eV ionizing radiation were used to measure the polarizabilities of more than half of the metallic elements in the Periodic Table. Concurrent Stern-Gerlach deflection measurements verified the ground-state condition of the measured atoms. Comparison with state-of-the-art calculations exposes significant systematic and isolated discrepancies throughout the Periodic Table.

Ma, Lei; Indergaard, John; Zhang, Baiqian; Larkin, Ilia; Moro, Ramiro; de Heer, Walt A.

2015-01-01

7

Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms

Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms from HCl,,v=2,J=1-of-flight mass spectrometry. The 35 Cl 2 P3/2 atoms are aligned by two mechanisms: 1 the time-dependent transfer is conserved during the photodissociation and thus contributes to the total 35 Cl 2 P3/2 photofragment atomic

Zare, Richard N.

8

Unraveling the chemical dynamics of bimolecular reactions of ground state boron atoms, B(2

Unraveling the chemical dynamics of bimolecular reactions of ground state boron atoms, B(2 PjArticle on the web 8th March 2004 The reaction dynamics of atomic boron, B(2 P), with acetylene, C2H2(X 1 Sg Ã¾ molecular beams technique. Only the atomic boron versus hydrogen atom exchange pathway was observed. Forward

Kaiser, Ralf I.

9

Rabi flopping between ground and Rydberg states with dipole-dipole atomic interactions

We demonstrate Rabi flopping of small numbers of $\\rm{^{87}Rb}$ atoms between ground and Rydberg states with $n\\le 43$. Coherent population oscillations are observed for single atom flopping, while the presence of two or more atoms decoheres the oscillations. We show that these observations are consistent with van der Waals interactions of Rydberg atoms.

T. A. Johnson; E. Urban; T. Henage; L. Isenhower; D. D. Yavuz; T. G. Walker; M. Saffman

2007-11-02

10

Parameterized potentials obtained within the relativistic, optimized, effective potential framework are reported for the ground state of the atoms He through Ra. The potentials are expressed in terms of Yukawian functions times a power of r. The total, kinetic, exchange, and single-particle energies and the expectation value of the spin-spin interaction are given for each atom.

Maldonado, P., E-mail: pablomaljim@gmail.co [Departamento de Fisica, Campus de Rabanales, Edificio C2, Universidad de Cordoba, E-14071 Cordoba (Spain); Sarsa, A. [Departamento de Fisica, Campus de Rabanales, Edificio C2, Universidad de Cordoba, E-14071 Cordoba (Spain); Buendia, E.; Galvez, F.J. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias, Universidad de Granada, E-18071 Granada (Spain)

2011-03-15

11

The role of correlation in the ground state energy of confined helium atom

We analyze the ground state energy of helium atom confined by spherical impenetrable walls, and the role of the correlation energy in the total energy. The confinement of an atom in a cavity is one way in which we can model the effect of the external pressure on an atom. The calculations of energy of the system are carried out by the variational method. We find that the correlation energy remains almost constant for a range values of size of the boxes analyzed.

Aquino, N. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, 09340 México Distrito Federal (Mexico)

2014-01-14

12

Is the electron stationary in the ground state of the Dirac hydrogen atom in Bohm's Theory?

We show that, in the relativistic Bohm model of a Dirac-like particle, the electron in the ground state of the hydrogen atom is moving, unlike the prediction for the case of a Schr\\"{o}dinger-like particle, where the electron is stationary. This accounts for the empirically observed dilation of the decay time of the muon in the ground state of muonium.

B. J. Hiley

2014-12-18

13

Comparison of near-threshold reactivity of ground-state and spin-orbit excited chlorine atoms of methane with atomic chlorine is initiated by photolysis of BrCl. Near 420 nm, the resulting mixture of ground- and excited-state chlorine atoms have spatial anisotropies of phot 0.7 for the Cl(2 P3/2) Br

Zare, Richard N.

14

NASA Astrophysics Data System (ADS)

The spin exchange and chemi-ionization cross sections for the metastable helium atom-lithium atom in the ground state system have been calculated. Using data on the interaction potentials obtained in this study, the spin exchange cross sections are determined for the first time for the He(23 S 1)-Li(22 S 1/2) system in the interval of collision energies from 5 × 10-3 to 16 eV.

Kartoshkin, V. A.

2007-12-01

15

We propose a cooling scheme for a trapped atom using the phenomenon of cavity-induced double electromagnetically induced transparency (EIT), where the atom comprising of four levels in tripod configuration is confined inside a high-finesse optical cavity. By exploiting one cavity-induced EIT, which involves one cavity photon and two laser photons, carrier transition can be eliminated due to the quantum destructive interference of excitation paths. Heating process originated from blue-sideband transition mediated by cavity field can also be prohibited due to the destructive quantum interference with the additional transition between the additional ground state and the excited state. As a consequence, the trapped atom can be cooled to the motional ground state in the leading order of the Lamb-Dicke parameters. In addition, the cooling rate is of the same order of magnitude as that obtained in the cavity-induced single EIT scheme. PMID:23481803

Yi, Zhen; Gu, Wen-ju; Li, Gao-xiang

2013-02-11

16

NASA Astrophysics Data System (ADS)

Experiments are conducted to verify the existence of amplified spontaneous emission (ASE) in ground state O atoms, and a kinetic model is developed to confirm the results. Both ASE and laser-induced fluorescence are observed at 845 nm, and the distributions observed at 845 are distorted by ASE. The atomic populations are depleted selectively from the original multiplet levels.

Huang, Yu-Lin; Gordon, Robert J.

1992-11-01

17

Spin-exchange narrowing of the atomic ground-state resonances

NASA Astrophysics Data System (ADS)

At the most fundamental level, the performance of atomic sensors is limited by quantum decoherence. The problem of decoherence has been addressed at low magnetic fields with atomic samples, where the limiting factor of the coherence lifetime arises from spin-exchange collisions. In this paper, we demonstrate the complex role of the collisions in the relaxation of quantum states of alkali-metal atoms. The detailed understanding of the collision role allows us to reduce the ground-state relaxation in stronger magnetic fields (tens ?T). Reduction of the relaxation rate enables improvement of the performance of atomic sensors. In particular, enhancement of the sensitivity of optical magnetometers in the detection of stronger magnetic fields may be obtained. Reduced transverse relaxation also enables increasing quantum-information storage time in atomic vapor.

Chalupczak, W.; Josephs-Franks, P.; Patton, B.; Pustelny, S.

2014-10-01

18

Simulation of the ground states of spin rings with cavity-assisted neutral atoms

NASA Astrophysics Data System (ADS)

Quantum phase transitions occur when the ground state of a Hamiltonian undergoes qualitative changes with a control parameter changing. In this paper we consider a particular system--an Isng-type spin ring with competing many-body interactions. Depending on the relative strength interactions, the ground state of the system is either a product state or entangled state. We implement the system in a cavity-assisted neutral atomic simulator and study the non-locality and entanglement of the simulated ground state of an Ising-type three-spin ring with the control parameter changing. The simplicity of the setup and its robustness to noise give it a great practicality within the framework of current experimental technology.

Xue, Peng; Zhan, Xiang; Bian, Zhihao

2015-01-01

19

Quantum ground state of self-organized atomic crystals in optical resonators

Cold atoms, driven by a laser and simultaneously coupled to the quantum field of an optical resonator, may self-organize in periodic structures. These structures are supported by the optical lattice, which emerges from the laser light they scatter into the cavity mode and form when the laser intensity exceeds a threshold value. We study theoretically the quantum ground state of these structures above the pump threshold of self-organization by mapping the atomic dynamics of the self-organized crystal to a Bose-Hubbard model. We find that the quantum ground state of the self-organized structure can be the one of a Mott insulator, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity-field intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the phase is compressible. These states could be realized in existing experimental setups.

Fernandez-Vidal, Sonia [Grup d'Optica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); De Chiara, Gabriele [Grup d'Optica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Grup de Fisica Teorica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Larson, Jonas [NORDITA, 106 91 Stockholm (Sweden); Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Morigi, Giovanna [Grup d'Optica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Theoretische Physik, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)

2010-04-15

20

Learning Approach on the Ground State Energy Calculation of Helium Atom

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.

Shah, Syed Naseem Hussain [Department of Physics, Federal Urdu University of Art, Sciences and Technology, Gulshan Campus Gulshan-e-Iqbal, University Road Karachi-75300 (Pakistan)

2010-07-28

21

Atoms and quantum dots with a large number of electrons: The ground-state energy

We compute the ground-state energy of atoms and quantum dots with a large number N of electrons. Both systems are described by a nonrelativistic Hamiltonian of electrons in a d-dimensional space. The electrons interact via the Coulomb potential. In the case of atoms (d=3), the electrons are attracted by the nucleus via the Coulomb potential. In the case of quantum dots (d=2), the electrons are confined by an external potential, whose shape can be varied. We show that the dominant terms of the ground-state energy are those given by a semiclassical Hartree-exchange energy, whose N{yields}{infinity} limit corresponds to Thomas-Fermi theory. This semiclassical Hartree-exchange theory creates oscillations in the ground-state energy as a function of N. These oscillations reflect the dynamics of a classical particle moving in the presence of the Thomas-Fermi potential. The dynamics is regular for atoms and some dots, but in general in the case of dots, the motion contains a chaotic component. We compute the correlation effects. They appear at the order NlnN for atoms, in agreement with available data. For dots, they appear at the order N.

Kunz, Herve; Rueedi, Rico [Institute of Theoretical Physics, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2010-03-15

22

NASA Technical Reports Server (NTRS)

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.

Drachman, Richard J.

2006-01-01

23

The Hartree limit of Born's ensemble for the ground state of a bosonic atom or ion

The non-relativistic bosonic ground state is studied for quantum N-body systems with Coulomb interactions, modeling atoms or ions made of N "bosonic point electrons" bound to an atomic point nucleus of Z "electron" charges, treated in Born--Oppenheimer approximation. It is shown that the (negative) ground state energy E(Z,N) yields the monotonically growing function (E(l N,N) over N cubed). By adapting an argument of Hogreve, it is shown that its limit as N to infinity for l > l* is governed by Hartree theory, with the rescaled bosonic ground state wave function factoring into an infinite product of identical one-body wave functions determined by the Hartree equation. The proof resembles the construction of the thermodynamic mean-field limit of the classical ensembles with thermodynamically unstable interactions, except that here the ensemble is Born's, with the absolute square of the ground state wave function as ensemble probability density function, with the Fisher information functional in the variational principle for Born's ensemble playing the role of the negative of the Gibbs entropy functional in the free-energy variational principle for the classical petit-canonical configurational ensemble.

Michael K. -H. Kiessling

2012-04-11

24

Studies of photoionization processes from ground-state and excited-state atoms and molecules

Recent triply-differential photoelectron spectroscopy experiments designed for the study of correlation effects in atoms and molecules are described. Final-state symmetry of the n=2 state of helium has been determined. The non-Franck-Condon behavior of vibrational branching ratios and large variations of the angular asymmetry parameter has been observed for shape resonances and autoionizing resonances in CO and other molecules. Recent observations of the photoionization of excited sodium atoms are also described.

Ederer, D.L.; Parr, A.C.; West, J.B.

1982-01-01

25

ERIC Educational Resources Information Center

In this paper, we accurately estimate the ground-state energy and the atomic radius of the helium atom and a helium-like Hookean atom by employing the uncertainty principle in conjunction with the variational approach. We show that with the use of the uncertainty principle, electrons are found to be spread over a radial region, giving an electron…

Harbola, Varun

2011-01-01

26

The Hartree limit of Born's ensemble for the ground state of a bosonic atom or ion

NASA Astrophysics Data System (ADS)

The non-relativistic bosonic ground state is studied for quantum N-body systems with Coulomb interactions, modeling atoms or ions made of N "bosonic point electrons" bound to an atomic point nucleus of Z absolute "electron" charges, treated in Born-Oppenheimer approximation (the nuclear mass M = ?). By adapting an argument of Hogreve, it is shown that the (negative) {B}osonic ground state energy E_{{infty }}^{{B}}(Z,N) yields the monotone non-decreasing function Nmapsto E_{{infty }}^{{B}}(? N,N)/N^3 for any ? > 0. The main part of the paper furnishes a proof that whenever ? ? ?* ? 1/1.21, then the limit \\varepsilon (? ):=lim _{NrArr infty }E_{{infty }}^{{B}}(? N,N)/N^3 is governed by Hartree theory, and the rescaled bosonic ground state wave function factors into an infinite product of identical one-body wave functions determined by the Hartree equation. The proof resembles the construction of the thermodynamic mean-field limit of the classical ensembles with thermodynamically unstable interactions, except that here the ensemble is Born's, with |?|2 as ensemble probability density function on {R}^{3N}, with the Fisher information functional in the variational principle for Born's ensemble playing the role of the negative Gibbs entropy functional in the free-energy variational principle for the classical petit-canonical configurational ensemble.

Kiessling, Michael K.-H.

2012-09-01

27

Asymptotics of the ground state energy for atoms and molecules in the self-generated magnetic field

Asymptotics of the ground state energy of the heavy atoms and molecules in the self-generated magnetic field has been derived and for minimal energy positions of nuclei remainder estimate $O(N^{16/9})$ has been recovered.

Ivrii, Victor

2011-01-01

28

Thermalization of fast cesium 5D3/2 atoms in collisions with ground-state cesium atoms A. Marks,1 A fast, excited Cs atoms produced by photodissociating Cs2 mol- ecules with a pulsed dye laser. The velocities of the atoms in the 5D state formed by the process Cs2 X 1 g + + pumpCs2 * Cs 5D +Cs 6S are much

Huennekens, John

29

Existence of a ground state for the confined hydrogen atom in non-relativistic QED

We consider a system of a hydrogen atom interacting with the quantized electromagnetic field. Instead of fixing the nucleus, we assume that the system is confined by its center of mass. This model is used in theoretical physics to explain the Lamb-Dicke effect. After a brief review of the literature, we explain how to verify some properly chosen binding conditions which lead to the existence of a ground state for our model, and for all values of the fine-structure constant.

Amour, Laurent [Laboratoire de Mathematiques EDPPM, UMR-CNRS 6056, Universite de Reims, Moulin de la Housse-BP 1039, 51687 REIMS Cedex 2 (France); Faupin, Jeremy [Laboratoire de Mathematiques EDPPM, UMR-CNRS 6056, Universite de Reims, Moulin de la Housse-BP 1039, 51687 REIMS Cedex 2 (France)

2008-04-03

30

Importance of complex orbitals in calculating the self-interaction-corrected ground state of atoms

The ground state of atoms from H to Ar was calculated using a self-interaction correction to local- and gradient-dependent density functionals. The correction can significantly improve the total energy and makes the orbital energies consistent with ionization energies. However, when the calculation is restricted to real orbitals, application of the self-interaction correction can give significantly higher total energy and worse results, as illustrated by the case of the Perdew-Burke-Ernzerhof gradient-dependent functional. This illustrates the importance of using complex orbitals for systems described by orbital-density-dependent energy functionals.

Kluepfel, Simon; Kluepfel, Peter; Jonsson, Hannes [Science Institute and Faculty of Science, VR-III, University of Iceland, Reykjavik (Iceland)

2011-11-15

31

Asymmetries in multiphoton ionization of the ground state of a hydrogen atom

NASA Astrophysics Data System (ADS)

This paper illustrates the study on asymmetry of the angular distribution of the ejected electrons in a multiphoton process from the ground state of a hydrogen atom. General expressions for the multiphoton ionization rates have been derived based on a variation of the Dalgarno-Lewis method for the evaluation of matrix elements in higher order perturbation theory. In addition, these analytical expressions for the various multiphoton transition rates and their variation as a function of polarization, phase, frequency and intensity of the incident radiation have been studied extensively. The general expression obtained can be used to analyse any number of incident beams with arbitrary polarization, phase and intensity.

Shrestha, Nilam; Radhakrishnan, R.; Babu Thayyullathil, Ramesh

2014-05-01

32

Accurate nonrelativistic ground-state energies of 3d transition metal atoms.

We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including the most prominent determinants of the full configuration interaction expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. To the best of our knowledge, the FN-DMC/(CIPSI nodes) ground-state energies presented here are the lowest variational total energies reported so far. They differ from the recently recommended non-variational values of McCarthy and Thakkar [J. Chem. Phys. 136, 054107 (2012)] only by a few percents of the correlation energy. Thanks to the variational property of FN-DMC total energies, our results provide exact lower bounds for the absolute value of all-electron correlation energies, |Ec|. PMID:25554136

Scemama, A; Applencourt, T; Giner, E; Caffarel, M

2014-12-28

33

Micro-mechanical oscillator ground state cooling via intracavity optical atomic excitations

We predict ground state cooling of a micro-mechanical oscillator, i.e. a vibrating end-mirror of an optical cavity, by resonant coupling of mirror vibrations to a narrow internal optical transition of an ensemble of two level systems. The particles represented by a collective mesoscopic spin model implement, together with the cavity, an efficient, frequency tailorable zero temperature loss channel which can be turned to a gain channel of pump. As opposed to the case of resolved-sideband cavity cooling requiring a small cavity linewidth, one can work here with low finesses and very small cavity volumes to enhance the light mirror and light atom coupling. The tailored loss and gain channels provide for efficient removal of vibrational quanta and suppress reheating. In a simple physical picture of sideband cooling, the atoms shape the cavity profile to enhance/inhibit scattering into higher/lower energy sidebands. The method should be applicable to other cavity based cooling schemes for atomic and molecular gases as for molecular ensembles coupled to stripline cavities.

C. Genes; H. Ritsch; D. Vitali

2009-06-19

34

Rubidium D1 and D2 atomic lines’ pressure broadened by ground-state helium atoms

NASA Astrophysics Data System (ADS)

Full quantum calculations are performed to determine the spectral broadening of the rubidium D1 and D2 lines induced by collisions with helium perturbers. The potential curves of the low-lying RbHe molecular states, as well as the corresponding transition dipole moments, are generated theoretically with ab initio methods based on SA-CASSCF-MRCI calculations, including the spin-orbit effects. The absorption and emission coefficients at wavelengths lying between 650 and 950\\;nm and temperatures ranging from 100 to 3000 K are determined. The absorption profile reveals it is dominated by the free-free transitions, whereas the emission spectral shape arises from the free-free and bound-free transitions. The resulting red- and blue-wing profiles are compared with previous experimental and theoretical works.

Bouhadjar, F.; Alioua, K.; Bouazza, M. T.

2014-09-01

35

Cooling to the Ground State of Axial Motion for One Atom Strongly Coupled to an Optical Cavity

Localization to the ground state of axial motion is demonstrated for a single, trapped atom strongly coupled to the field of a high finesse optical resonator. The axial atomic motion is cooled by way of coherent Raman transitions on the red vibrational sideband. An efficient state detection scheme enabled by strong coupling in cavity QED is used to record the Raman spectrum, from which the state of atomic motion is inferred. We find that the lowest vibrational level of the axial potential with zero-point energy 13uK is occupied with probability P0~0.95.

A. D. Boozer; A. Boca; R. Miller; T. E. Northup; H. J. Kimble

2006-06-13

36

We discuss a new technique of studying magnetic fields in diffuse astrophysical media, e.g. interstellar and intergalactic gas/plasma. This technique is based on the angular momentum alignment of atoms and ions in their ground or metastable states. As the life-time of atoms in such states is long, the alignment induced by anisotropic radiation is susceptible to weak magnetic fields ($1{\\rm G}\\gtrsim B\\gtrsim0.1\\mu$G). The alignment reveals itself in terms of the polarization of the absorbed and emitted light. A variety of atoms with fine or hyperfine splitting of the ground or metastable states exhibit the alignment and the resulting polarization degree in some cases exceeds 20%. We show that in the case of absorption the polarization direction is either parallel or perpendicular to magnetic field, while more complex dependencies emerge for the case of emission of aligned atoms. We show that the corresponding studies of magnetic fields can be performed with optical and UV polarimetry. A unique feature of these studies is that they can reveal the 3D orientation of magnetic field. In addition, we point out that the polarization of the radiation arising from the transitions between fine and hyperfine states of the ground level can provide yet another promising diagnostics of magnetic fields, including the magnetic fields in the Early Universe. We mention several cases of interplanetary, circumstellar and interstellar magnetic fields for which the studies of magnetic fields using ground state atomic alignment effect are promising.

Huirong Yan; A. Lazarian

2008-06-23

37

Feynman-Kac path integral calculation of the ground state energy of atoms

In a paper written in 1950, the mathematician, Marc Kac, established a rigorous basis for the Feynman path-integral formulation of quantum mechanics. The original Feynman path integral lacks mathematical rigor in the definition of [open quotes]summing over all paths[close quotes], which are infinite in number (a theorem by Cameron states that a finite, real or complex, Lebesgue measure of the path defined by Feynman does not exist). The difficulty of using Feynman's method in a computation is supported by the observation that an accurate path integral solution of the hydrogen groundstate was only recently computed (in 1984). Since its introduction in 1950, the Feynman-Kac path integral (FKPI) has received limited attention despite its simplicity and power in solving quantum many-body problems. This work demonstrates that the FKPI method can be used to find the ground state and excited states of small atomic systems to within experimental accuracy, and is ideally suited for the new massively parallel computer architectures, such as Thinking Machines CM-5, the INTEL Paragon, et al., or can be effectively used in a cluster of loosely-coupled workstations. It also demonstrates a simple procedure for incorporating into the FKPI computational method restrictions on the many-body wavefunction imposed by permutation symmetries of identical particles.

Orr, D.E.

1992-01-01

38

It is shown that the ground state energy of heavy atoms is, to leading order, given by the non-relativistic Thomas-Fermi energy. The proof is based on the relativistic Hamiltonian of Brown and Ravenhall which is derived from quantum electrodynamics yielding energy levels correctly up to order $\\alpha^2$Ry.

Roch Cassanas; Heinz Siedentop

2006-03-29

39

PHYSICAL REVIEW A 87, 063412 (2013) Rb atoms in a blue-detuned dipole trap: Coherence and ground) Blue-detuned dipole traps and their ability to preserve atomic coherences are interesting for precision of the ground-state hyperfine splitting in 87 Rb atoms confined in a dynamic blue-detuned dipole trap. We

Orozco, Luis A.

40

Trends in ground-state entropies for transition metal based hydrogen atom transfer reactions.

Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors M(II)LH and oxyl radicals. [Fe(II)(H(2)bip)(3)](2+), [Fe(II)(H(2)bim)(3)](2+), [Co(II)(H(2)bim)(3)](2+), and Ru(II)(acac)(2)(py-imH) [H(2)bip = 2,2'-bi-1,4,5,6-tetrahydropyrimidine, H(2)bim = 2,2'-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2'-pyridyl)imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or (t)Bu(3)PhO(*) (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex M(III)L and TEMPOH or (t)Bu(3)PhOH. Solution equilibrium measurements for the reaction of [Co(II)(H(2)bim)(3)](2+) with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer, -41 +/- 2 cal mol(-1) K(-1). This is even more negative than the DeltaS(o)(HAT) = -30 +/- 2 cal mol(-1) K(-1) for the two iron complexes and the DeltaS(o)(HAT) for Ru(II)(acac)(2)(py-imH) + TEMPO, 4.9 +/- 1.1 cal mol(-1) K(-1), as reported earlier. Calorimetric measurements quantitatively confirm the enthalpy of reaction for [Fe(II)(H(2)bip)(3)](2+) + TEMPO, thus also confirming DeltaS(o)(HAT). Calorimetry on TEMPOH + (t)Bu(3)PhO(*) gives DeltaH(o)(HAT) = -11.2 +/- 0.5 kcal mol(-1) which matches the enthalpy predicted from the difference in literature solution BDEs. A brief evaluation of the literature thermochemistry of TEMPOH and (t)Bu(3)PhOH supports the common assumption that DeltaS(o)(HAT) approximately 0 for HAT reactions of organic and small gas-phase molecules. However, this assumption does not hold for transition metal based HAT reactions. The trend in magnitude of |DeltaS(o)(HAT)| for reactions with TEMPO, Ru(II)(acac)(2)(py-imH) < [Fe(II)(H(2)bip)(3)](2+) = [Fe(II)(H(2)bim)(3)](2+) < [Co(II)(H(2)bim)(3)](2+), is surprisingly well predicted by the trends for electron transfer half-reaction entropies, DeltaS(o)(ET), in aprotic solvents. This is because both DeltaS(o)(ET) and DeltaS(o)(HAT) have substantial contributions from vibrational entropy, which varies significantly with the metal center involved. The close connection between DeltaS(o)(HAT) and DeltaS(o)(ET) provides an important link between these two fields and provides a starting point from which to predict which HAT systems will have important ground-state entropy effects. PMID:19275235

Mader, Elizabeth A; Manner, Virginia W; Markle, Todd F; Wu, Adam; Franz, James A; Mayer, James M

2009-04-01

41

Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions

Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors MIILH and oxyl radicals. [FeII(H2bip)3]2+, [FeII(H2bim)3]2+, [CoII(H2bim)3]2+ and RuII(acac)2(py-imH) [H2bip = 2,2’-bi-1,4,5,6-tetrahydropyrimidine, H2bim = 2,2’-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2’-pyridyl)-imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or tBu3PhO• (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex MIIIL, and TEMPOH or tBu3PhOH. Solution equilibrium measurements for the reaction of [CoII(H2bim)3]2+ with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer, ?41 ± 2 cal mol?1 K?1. This is even more negative than the ?SoHAT = ?30 ± 2 cal mol?1 K?1 for the two iron complexes and the ?SoHAT for RuII(acac)2(py-imH) + TEMPO, 4.9 ± 1.1 cal mol?1 K?1, as reported earlier. Calorimetric measurements quantitatively confirm the enthalpy of reaction for [FeII(H2bip)3]2+ + TEMPO, thus also confirming ?SoHAT. Calorimetry on TEMPOH + tBu3PhO• gives ?HoHAT = ?11.2 ± 0.5 kcal mol?1 which matches the enthalpy predicted from the difference in literature solution BDEs. A brief evaluation of the literature thermochemistry of TEMPOH and tBu3PhOH supports the common assumption that ?SoHAT ? 0 for HAT reactions of organic and small gas-phase molecules. However, this assumption does not hold for transition metal based HAT reactions. The trend in magnitude of |?SoHAT| for reactions with TEMPO, RuII(acac)2(py-imH) << [FeII(H2bip)3]2+ = [FeII(H2bim)3]2+ < [CoII(H2bim)3]2+, is surprisingly well predicted by the trends for electron transfer half-reaction entropies, ?SoET, in aprotic solvents. This is because both ?SoET and ?SoHAT have substantial contributions from vibrational entropy, which varies significantly with the metal center involved. The close connection between ?SoHAT and ?SoET provides an important link between these two fields and provides a starting point from which to predict which HAT systems will have important ground-state entropy effects. PMID:19275235

Mader, Elizabeth A.; Manner, Virginia W.; Markle, Todd F.; Wu, Adam; Franz, James A.; Mayer, James M.

2009-01-01

42

Vibrational Relaxation of Ground-State Oxygen Molecules With Atomic Oxygen and Carbon Dioxide

NASA Astrophysics Data System (ADS)

Vertical water vapor profiles are key to understanding the composition and energy budget in the mesosphere and lower thermosphere (MLT). The SABER instrument onboard NASA's TIMED satellite measures such profiles by detecting H2O(?2) emission in the 6.8 ?m region. Collisional deactivation of vibrationally excited O2, O2(X3?-g, ? = 1) + H2O ? O2(X3?-g, ? = 0) + H2O(?2), is an important source of H2O(?2). A recent study has identified two other processes involving excited O2 that control H2O(?2) population in the MLT: (1) the vibrational-translational (V-T) relaxation of O2(X3?-g, ? = 1) level by atomic oxygen and (2) the V-V exchange between CO2 and excited O2 molecules [1]. Over the past few years SRI researchers have measured the atomic oxygen removal process mentioned above at room temperature [2] and 240 K [3]. These measurements have been incorporated into the models for H2O(?2) emission [1]. Here we report laboratory studies of the collisional removal of O2(X3?-g, ? = 1) by O(3P) at room temperature and below, reaching temperatures relevant to mesopause and polar summer MLT (~150 K). Instead of directly detecting the O2(X3?-g, ? = 1) population, a technically simpler approach is used in which the ? = 1 level of the O2(a1?g) state is monitored. A two-laser method is employed, in which the pulsed output of the first laser near 285 nm photodissociates ozone to produce atomic oxygen and O2(a1?g, ? = 1), and the pulsed output of the second laser detects O2(a1?g, ? = 1) via resonance-enhanced multiphoton ionization. With ground-state O2 present, owing to the rapid equilibration of the O2(X3?-g, ? = 1) and O2(a1?g, ? = 1) populations via the processes O2(a1?g, ? = 1) + O2(X3?-g, ? = 0) ? O2(a1?g, ? = 0) + O2(X3?-g, ? = 1), the information on the O2(X3?-g, ? = 1) kinetics is extracted from the O2(a1?g, ? = 1) temporal evolution. In addition, measurements of the removal of O2(X3?-g, ? = 1) by CO2 at room temperature will also be presented. This work is supported by the Johns Hopkins University, Applied Physics Laboratory, under grant 939991 (under NASA grant NAG5-13002). [1] Feofilov, A., Kutepov, A. A., García-Comas, M., López-Puertas, M., Marshall, B. T., Gordley, L. L., Manuilova, R. O., Yankovsky, V. A., Pesnell, W. D., Goldberg, R. A., Petelina, S. V., and Russell III., J. M. 'SABER/TIMED Observations of Water Vapor in the Mesosphere: Retrieval Methodology and First Results'. Submitted to J. of Atmos. and Terrest. Phys., (2008). [2] Kalogerakis, K. S., Copeland, R. A., and Slanger, T. G., J. of Chem. Phys., 123, 194303, (2005). [3] Pejakovic, D. A., Campbell, Z., Kalogerakis, K. S., Copeland, R. A., and Slanger, T. G., Eos. Trans. AGU 85(47), Fall Meet. Suppl., Abstract SA41A-1032, (2004).

Saran, D. V.; Pejakovic, D. A.; Copeland, R. A.

2008-12-01

43

Switching between ground states of an InAs quantum dot doped with a single Mn atom

NASA Astrophysics Data System (ADS)

The ultrafast light-induced dynamics in an InAs quantum dot doped with a single Mn atom is studied theoretically. Due to the exchange interaction between the Mn atom and the acceptor hole in the quantum dot, an effective two-level system is formed in the ground-state manifold. We show that this two-level system can be controlled coherently on a picosecond time scale. The control involves an optical manipulation of the quantum dot exciton by using either a series of two ultrafast pulses or a single extended laser pulse. For the excitation with two pulses, we discuss the optical signals that could be used in time-resolved spectroscopy to monitor the dynamics. We compare these results to the spin dynamics in a CdTe quantum dot doped with a single Mn atom.

Thuberg, D.; Reiter, D. E.; Axt, V. M.; Kuhn, T.

2013-08-01

44

The molecular beam magnetic resonance method previously used for the study of molecules has been extended to the study of atoms. Transitions between the members of hyperfine structure multiplets of the ground state of atoms have been observed directly. In this way the hyperfine structure intervals of the normal states of Li6, Li7, K39 and K41 have been measured. Since

P. Kusch; S. Millman; I. I. Rabi

1940-01-01

45

NASA Technical Reports Server (NTRS)

The interactions of a He atom with a heavier atom are examined for 26 different elements, which are consecutive members selected from three rows (Li - Ne, Na - Ar, and K,Ca, Ga - Kr) and column 12 (Zn,Cd) of the periodic table. Interaction energies are determined wing high-quality ab initio calculations for the states of the molecule that would be formed from each pair of atoms in their ground states. Potential energies are tabulated for a broad range of Interatomic separation distances. The results show, for example, that the energy of an alkali interaction at small separations is nearly the same as that of a rare-gas interaction with the same electron configuration for the dosed shells. Furthermore, the repulsive-range parameter for this region is very short compared to its length for the repulsion dominated by the alkali-valence electron at large separations (beyond about 3-4 a(sub 0)). The potential energies in the region of the van der Waals minimum agree well with the most accurate results available. The ab initio energies are applied to calculate scattering cross sections and obtain the collision integrals that are needed to determine transport properties to second order. The theoretical values of Li-He total scattering cross sections and the rare-gas atom-He transport properties agree well (to within about 1%) with the corresponding measured data. Effective potential energies are constructed from the ab initio energies; the results have been shown to reproduce known transport data and can be readily applied to predict unknown transport properties for like-atom interactions.

Partridge, Harry; Stallcop, James R.; Levin, Eugene; Arnold, Jim (Technical Monitor)

2001-01-01

46

We measure inelastic collisional cross sections for the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He. We determine for Th ($^3$F$_2$) at 800 mK the ratio $\\gamma \\approx 500$ of the momentum-transfer to Zeeman relaxation cross sections for collisions with $^3$He. For Th ($^3$P$_0$), we study electronic inelastic processes and find no quenching even after $10^6$ collisions. We also determine the radiative lifetime of Th ($^3$P$_0$) to be $\\tau > 130$ ms. This great stability of the metastable state opens up the possibility for further study, including trapping.

Au, Yat Shan; Ketterle, Wolfgang; Doyle, John M

2013-01-01

47

The Ground State Energy of Relativistic One-Electron Atoms According to Jansen and He

successfull in describing heavy atoms. It is an approximate no-pair Hamiltonian in the Furry picture. We show by their external #12;eld (Furry picture). (See Sucher [16] for a review.) This strategy, however, meets immediate

48

NASA Technical Reports Server (NTRS)

It is pointed out that the investigated reaction of oxygen with dimethyl sulfide may play an important role in photochemical smog formation and in the chemical evolution of dense interstellar clouds. Kinetic data were obtained with the aid of the flash photolysis-resonance fluorescence method. The photodecomposition of molecular oxygen provided the oxygen atoms for the experiments. The decay of atomic oxygen was studied on the basis of resonance fluorescence observations. Both reactions investigated were found to be fast processes. A negative temperature dependence of the rate constants for reactions with dimethyl sulfide was observed.

Lee, J. H.; Timmons, R. B.; Stief, L. J.

1976-01-01

49

Nonadiabatic couplings in low-energy collisions of hydrogen ground-state atoms

The effect of nonadiabatic couplings on low-energy s-wave scattering of two hydrogen atoms is investigated. Coupling matrix elements are computed in a wide range of internuclear distances. The resulting scattering equations are numerically unstable and therefore are integrated only approximately. Computations are performed for H, D, and T atoms. The phase shifts in the zero velocity limit are inversely proportional to the nuclear reduced mass {delta}{sub 0}{approx_equal}0.392/{mu}. This leads to infinite scattering lengths.

Wolniewicz, L. [Institute of Physics, Nicolaus Copernicus University, 87-100 Torun (Poland)

2003-10-01

50

Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions

Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors MIILH and oxyl radicals. [FeII(H2bip)3]2+, [FeII(H2bim)3]2+, [CoII(H2bim)3]2+ and RuII(acac)2(py-imH) [H2bip = 2,2-bi-1,4,5,6-tetrahydro¬pyrimidine, H2bim = 2,2-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2-pyridyl)¬imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or tBu3PhO (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex MIIIL, and TEMPOH or tBu3PhOH. Solution equilibrium measurements

Elizabeth A. Mader; Virginia W. Manner; Todd F. Markle; Adam Wu; James A. Franz; James M. Mayer

2009-01-01

51

Rate constants for the reaction of ground state atomic oxygen with methanol

NASA Astrophysics Data System (ADS)

The reaction of O(3P) with methanol has been studied using the complementary discharge flow and flash photolysis techniques. In both cases, resonance fluorescence detection of atomic oxygen was employed. The discharge flow (DF) apparatus was used in a temperature range of 298-998 K while the flash photolysis (FP) apparatus was used in the overlapping range of 329-527 K. The apparent bimolecular rate constants for the O-atom/methanol reaction obtained from DF experiments at low temperatures (T?450 K) were independent of both the initial O-atom concentration and the mode of O-atom production. In addition, large excesses of O2 were added to the flow to intercept the primary reaction product (CH2OH), but had no apparent effect on the measured rate constant. Results from the two methods were in good agreement within this limited temperature range (˜300-500 K). At temperatures above ˜450 K, the apparent rate constants obtained from DF experiments were increasingly sensitive to the O2 concentration, with the rate constants being smaller when determined in the presence of large [O2]. Since the initial O-atom concentrations were on the order of 1011 or less, a simple stoichiometry effect can be ruled out. However, the results of the present kinetic experiments indicated that heterogeneous pyrolysis of CH3OH may have occurred in the flow system. This observation is consistent with studies of the adsorption of methanol on silica surfaces. This problem was apparently overcome by adding small amounts of O2 and the rate constants obtained in this way were seen to agree well with values extrapolated from the lower temperature DF and FP experiments. The rate data from DF and FP experiments were thus combined to obtain the following Arrhenius expression (298-998 K): k1 (T) = (2.70±0.50)×10-11 exp(-5030±160/RT cm3 molecule-1 s-1. This result is compared with those of previous studies, and kinetic complications (stoichiometry) and heterogeneous effects are further discussed.

Keil, David G.; Tanzawa, Tsuneo; Skolni, Edward G.; Klemm, R. Bruce; Michael, Joe V.

1981-09-01

52

Roothaan-Hartree-Fock (RHF) calculations have been carried out for the ground states of the atoms from helium to krypton using certain exponential-type functions, the B functions. The authors report a compilation of single- and double-zeta (SZ and DZ) wave functions. A comparison with the conventional SZ and DZ RHF wave functions is also presented. For each atom, the total energy, kinetic energy, potential energy, virial ratio, orbital energies, and orbital expansion coefficients and exponents are tabulated.

Ema, I.; Vega, J.M.G. de la; Miguel, B. [Univ. Autonoma, Madrid (Spain). Dept. de Quimica Fisica Applicada] [Univ. Autonoma, Madrid (Spain). Dept. de Quimica Fisica Applicada; Dotterweich, J.; Meissner, H.; Steinborn, E.O. [Univ. Regensburg (Germany). Inst. fuer Physikalische und Theoretische Chemie] [Univ. Regensburg (Germany). Inst. fuer Physikalische und Theoretische Chemie

1999-05-01

53

NASA Astrophysics Data System (ADS)

We take as a starting point the ground-state electron density in two-electron model atoms in which Coulomb confinement in the He atom is first replaced by harmonic restoring forces. Switching off electron-electron interactions, one readily constructs a third-order differential equation for the ground-state electron density, as in the recent work of March and Ludeña (2004 Phys. Lett. A 330 16). We then switch on two different model interactions, first in the so-called Hookean atom going back to Kestner and Sinanoglu (1962 Phys. Rev. 128 2687), in which e2/r12 is retained as in He, and secondly in the Moshinsky (1968 Am. J. Phys. 36 52) atom in which Kr212/2 is switched on. Some analyticity properties of the low-order linear homogeneous differential equations which result are next studied. He-like atomic ions are then treated in the limit of large atomic number Z. In this latter case, one identifies both the electron-nuclear cusp, or equivalently Kato's theorem, and the corresponding electron-electron cusp in the ground-state spatial wavefunction ?(r1, r2). A final comment concerns quantum information and entanglement in relation to the recent work of Amovilli and March (2004 Phys. Rev. A 69 054302).

March, N. H.; Negro, J.; Nieto, L. M.

2006-04-01

54

NASA Astrophysics Data System (ADS)

We study phase-sensitive amplification of electromagnetically induced transparency in a warm 85Rb vapor wherein a microwave driving field couples the two lower-energy states of a ? energy-level system thereby transforming into a ? system. Our theoretical description includes effects of ground-state coherence decay and temperature effects. In particular, we demonstrate that driving-field-enhanced electromagnetically induced transparency is robust against significant loss of coherence between ground states. We also show that for specific field intensities, a threshold rate of ground-state coherence decay exists at every temperature. This threshold separates the probe-transmittance behavior into two regimes: probe amplification vs probe attenuation. Thus, electromagnetically induced transparency plus amplification is possible at any temperature in a ? system.

Manjappa, Manukumara; Undurti, Satya Sainadh; Karigowda, Asha; Narayanan, Andal; Sanders, Barry C.

2014-10-01

55

Designing and optimizing cost functions and energy landscapes is a problem encountered in many fields of science and engineering. These landscapes and cost functions can be embedded and annealed in experimentally controllable spin Hamiltonians. Using an approach based on group theory and symmetries, we examine the embedding of Boolean logic gates into the ground state subspace of such spin systems. We describe parameterized families of diagonal Hamiltonians and symmetry operations which preserve the ground state subspace encoding the truth tables of Boolean formulas. The ground state embeddings of adder circuits are used to illustrate how gates are combined and simplified using symmetry. Our work is relevant for experimental demonstrations of ground state embeddings found in both classical optimization as well as adiabatic quantum optimization.

J. D. Whitfield; M. Faccin; J. D. Biamonte

2012-05-08

56

Rabi Oscillations between Ground and Rydberg States with Dipole-Dipole Atomic Interactions T. A November 2007; published 19 March 2008) We demonstrate Rabi oscillations of small numbers of 87 Rb atoms interaction effects between as few as two atoms and by observation of coherent Rabi oscillations between

Yavuz, Deniz

57

Exploration and manipulation of electronic states in low-dimensional systems are of great importance in the fundamental and practical aspects of nanomaterial and nanotechnology. Here, we demonstrate that the incorporation of vacancy defects into monatomic indium wires on n-type Si(111) can stabilize electronically phase-separated ground states where the insulating 8×2 and metallic 4×1 phases coexist. Furthermore, the areal ratio of the two phases in the phase-separated states can be tuned reversibly by electric field or charge doping, and such tunabilities can be quantitatively captured by first principles-based modeling and simulations. The present results extend the realm of electronic phase separation from strongly correlated d-electron materials typically in bulk form to weakly interacting sp-electron systems in reduced dimensionality. PMID:25415916

Zhang, Hui; Ming, Fangfei; Kim, Hyun-Jung; Zhu, Hongbin; Zhang, Qiang; Weitering, Hanno H; Xiao, Xudong; Zeng, Changgan; Cho, Jun-Hyung; Zhang, Zhenyu

2014-11-01

58

NASA Astrophysics Data System (ADS)

Here attention is first drawn to the importance of gaining insight into Fock's early proposal for expanding the ground-state wave function for He-like atomic ions in hyperspherical coordinates. We approach the problem via two solvable models, namely, (i) the s-term model put forth by Temkin [Phys. Rev.PHRVAO0031-899X10.1103/PhysRev.126.130 126, 130 (1962)] and (ii) the Hookean atom model proposed by Kestner and Sinanoglu [Phys. Rev.PHRVAO0031-899X10.1103/PhysRev.128.2687 128, 2687 (1962)]. In both cases the local kinetic energy can be obtained explicitly in hyperspherical coordinates. Separation of variables occurs in both model wave functions, though in a different context in the two cases. Finally, a k-space formulation is proposed that should eventually result in distinctive identifying characteristics of Fock's nonanalyticities for He-like atomic ions when both electrons are close to the nucleus.

Glasser, M. L.; March, N. H.; Nieto, L. M.

2011-12-01

59

NASA Astrophysics Data System (ADS)

One can easily obtain a good estimate of the total energy E(Z) of a ground-state neutral atom with Z (>>1) electrons, primarily because an effective central potential Veff(r) provides a very good starting point. A sufficient, if not necessary, condition for there to be such a Veff is for the ratio ?(Z)?Ve-e(Z)/Ve-?(Z) of the electron-electron and electron-nuclear contributions to E(Z) to be small, and it is found to be only about (1/7) for large Z. In the (statistical) nonrelativistic Thomas-Fermi (TF) model, which becomes exact as Z~?, E(Z) (in rydbergs) is approximated by ETF(Z)=-c7Z7/3 for all Z, with c7 a known constant, while ?(Z) is approximated by ?TF(Z)=(1/7) for all Z. A simple proof that ?(Z)~(1/7) as Z~?, by Rau (unpublished) and by Thirring [Quantum Mechanics of Large Systems (Springer-Verlag, New York, 1983)], used only the assumption (built into TF theory) that the binding energy of the last electron in a neutral atom is negligible. We use that fact, the (recently developed) corrected TF result E(Z) ~=-(c7Z7/3+c6Z6/3+c5X5/3) (with c7, c6, and c5 theoretically determined), and the virial theorem, and we show that Ve-?(Z)~=Z(dE/dZ) with an error that is at most of order Z4/3; we thereby obtain an expression for ?(Z) which approaches (1/7) as Z~?, the error for large Z being of order 1/Z, and is reasonably accurate even for moderate values of Z. One finds ?(Z)~=J(n-6)sn/Jnsn, where each sum is over n=7, 6, and 5, and where sn=cnZ(n-7)/3. The value of ?(Z) for heavy atoms in ``strong'' magnetic fields, those describable by a one-dimensional (statistical) TF-like theory, is discussed briefly. Some numerical studies are included. The results obtained are of interest in atomic theory itself, and in low-energy ?-decay processes for which the difference in atomic binding energies is important.

Chen, Zonghua; Spruch, Larry

1987-05-01

60

NASA Astrophysics Data System (ADS)

Quantal calculations are performed to determine the absorption profile of the broadened potassium resonance line 4p?4s in its far wings provoked by helium perturbers. First, the X2?+, A2?, and B2?+ potentials, as well as the transition dipole moments, are carefully computed through ab initio methods, based on state-averaged complete active space self-consistent field multireference configuration interaction (SA-CASSCF-MRCI) calculations involving the Davidson and basis-set superposition error (BSSE) corrections. The data are then used to generate the KHe photoabsorption spectra and to examine their behavior with temperature. The theoretical profile is dominated by the free-free transitions and exhibits, in the vicinity of the wavelength position of 693 nm, a satellite peak in the blue wing attributed to the B?X transitions. The results are compared with previous theoretical and experimental investigations and, in general, good agreement is found.

Boutarfa, H.; Alioua, K.; Bouledroua, M.; Allouche, A.-R.; Aubert-Frécon, M.

2012-11-01

61

Magnetic Field Measurement with Ground State Alignment

NASA Astrophysics Data System (ADS)

Observational studies of magnetic fields are crucial. We introduce a process "ground state alignment" as a new way to determine the magnetic field direction in diffuse medium. The alignment is due to anisotropic radiation impinging on the atom/ion. The consequence of the process is the polarization of spectral lines resulting from scattering and absorption from aligned atomic/ionic species with fine or hyperfine structure. The magnetic field induces precession and realign the atom/ion and therefore the polarization of the emitted or absorbed radiation reflects the direction of the magnetic field. The atoms get aligned at their low levels and, as the life-time of the atoms/ions we deal with is long, the alignment induced by anisotropic radiation is susceptible to extremely weak magnetic fields (1 G ? B ? 10^{-15} G). In fact, the effects of atomic/ionic alignment were studied in the laboratory decades ago, mostly in relation to the maser research. Recently, the atomic effect has been already detected in observations from circumstellar medium and this is a harbinger of future extensive magnetic field studies. A unique feature of the atomic realignment is that they can reveal the 3D orientation of magnetic field. In this chapter, we shall review the basic physical processes involved in atomic realignment. We shall also discuss its applications to interplanetary, circumstellar and interstellar magnetic fields. In addition, our research reveals that the polarization of the radiation arising from the transitions between fine and hyperfine states of the ground level can provide a unique diagnostics of magnetic fields in the Epoch of Reionization.

Yan, Huirong; Lazarian, A.

62

A model is proposed for the approximate calculation, starting with theoretical atoms-in-molecules-like composite functions (or linear combinations of valence bond structures) of potential-energy curves for ground and excited diatomic systems. The assumptions which define the model may be summarized as follows: (1) diatomic electronic eigenstates are represented by a linear combination of composite functions which, in their orbital approximation, are

Frank O. Ellison

1965-01-01

63

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.

Ruokokoski, E. [Department of Applied Physics/COMP, Aalto University, P.O. Box 14100, FI-00076 AALTO (Finland); Pietilae, V. [Physics Department, Harvard University, Cambridge, Massachusetts 02138 (United States); Moettoenen, M. [Department of Applied Physics/COMP, Aalto University, P.O. Box 14100, FI-00076 AALTO (Finland); Low Temperature Laboratory, Aalto University, P.O. Box 13500, FI-00076 AALTO (Finland)

2011-12-15

64

ccsd00000983 Quantum state transfer between elds and atoms

ccsdÂ00000983 (version 1) : 23 Dec 2003 Quantum state transfer between #12;elds and atoms show that a quasi-perfect quantum state transfer between an atomic ensemble and #12;elds in an optical can be mapped onto the long-lived atomic spin associated to the ground state sublevels of the #3;-type

65

Ground States of Magnetorheological Fluids

Through energy minimization and stability argument, we find the ground states of the magnetorheological fluids to consist of magnetic particles arranged in a body centered tetragonal structure inside spheroidal clusters. The width D of the clusters varies with the length L as D~Ln, where n = 0.62 for magnetically saturated particles. In the case of magnetically unsaturated particles, the power

Lei Zhou; Weijia Wen; Ping Sheng

1998-01-01

66

Multilevel Atomic Coherent States and Atomic Holomorphic Representation

NASA Technical Reports Server (NTRS)

The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

Cao, Chang-Qi; Haake, Fritz

1996-01-01

67

Interaction between DNA and Metalic NanoClusters (MNCs) in particular noble metals, have attracted attention in the last years due its unique and tunable optical characteristics. However despite the great experimental advances in this field, the theoretical explanation of its particular excited states remains unknown. In this work we present an exhaustive study of the stabilization and structural properties of the noble metal atoms: gold and silver in three charge states: anionic, neutral and cationic interacting with DNA/RNA by using a real-space DFT methodology. We have taken in account the effect of pairing between bases and the presence of the sugar backbone.

Leal, Leonardo Andres Espinosa

2014-01-01

68

Femtosecond stimulated emission pumping: Characterization ground state

Â1 vibrational fre- quency, resonance impulsive stimulated Raman scattering RISRS was used to create ground stateFemtosecond stimulated emission pumping: Characterization of the I2 Ã? ground state Martin T. Zanni to characterize the potential energy function of the I2 (X~ 2 u ) ground state up to vibrational energies within 2

Neumark, Daniel M.

69

We consider hyperfine splitting of 1s and, in part, of 2s levels in light hydrogen-like atoms: hydrogen, deuterium, tritium, helium-3 ion, muonium and positronium. We discuss present status of precision theory and experiment for the hfs intervals. We pay a special attention to a specific difference, D_{21} = 8 E_{hfs}(2s) - E_{hfs}(1s), which is known experimentally for hydrogen, deuterium and ^3He^+ ion. The difference is weakly affected by the effects of the nuclear structure and thus may be calculated with a high accuracy. We complete a calculation of the fourth order QED contributions to this difference and present here new results on corrections due to the nuclear effects. Our theoretical predictions appear to be in a fair agreement with available experimental data. Comparison of the experimental data with our examination of D_{21} allows to test the state-dependent sector of theory of the hfs separation of the 1s and 2s levels in the light hydrogen-like atoms up to 10^-8.

Savely G. Karshenboim; Vladimir G. Ivanov

2001-09-27

70

Atomic data for absorption lines from the ground level at wavelengths greater than 228A

We list wavelengths, statistical weigths and oscillator strengths for 2249 spectral lines arising from the ground states of atoms and ions. The compilation covers all wavelengths longward of the He II Lyman limit at 227.838A and all the ion states of all elements from hydrogen to bismuth (Z=83) for which reliable data are known. We assign experimental wavelengths to 1086

D. A. Verner; P. D. Barthel; D. Tytler

1994-01-01

71

Ground state terahertz quantum cascade lasers

A terahertz quantum cascade laser (THz QCL) architecture is presented in which only the ground state subbands of each quantum well are involved in the transport and lasing transition. Compared to state-of-the art THz QCLs ...

Hu, Qing

72

Langevin equation path integral ground state.

We propose a Langevin equation path integral ground state (LePIGS) approach for the calculation of ground state (zero temperature) properties of molecular systems. The approach is based on a modification of the finite temperature path integral Langevin equation (PILE) method (J. Chem. Phys. 2010, 133, 124104) to the case of open Feynman paths. Such open paths are necessary for a ground state formulation. We illustrate the applicability of the method using model systems and the weakly bound water-parahydrogen dimer. We show that the method can lead to converged zero point energies and structural properties. PMID:23738885

Constable, Steve; Schmidt, Matthew; Ing, Christopher; Zeng, Tao; Roy, Pierre-Nicholas

2013-08-15

73

Ground-state Bethe root densities and quantum phase transitions

NASA Astrophysics Data System (ADS)

Exactly solvable models provide a unique method, via qualitative changes in the distribution of the ground-state roots of the Bethe ansatz equations, to identify quantum phase transitions. Here we expand on this approach, in a quantitative manner, for two models of Bose–Einstein condensates. The first model deals with the interconversion of bosonic atoms and molecules. The second is the two-site Bose–Hubbard model, widely used to describe tunneling phenomena in Bose–Einstein condensates. For these systems we calculate the ground-state root density. This facilitates the determination of analytic forms for the ground-state energy, and associated correlation functions through the Hellmann–Feynman theorem. These calculations provide a clear identification of the quantum phase transition in each model. For the first model we obtain an expression for the molecular fraction expectation value. For the two-site Bose–Hubbard model we find that there is a simple characterization of condensate fragmentation.

Links, Jon; Marquette, Ian

2015-01-01

74

Lattice QCD Beyond Ground States

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

Huey-Wen Lin; Saul D. Cohen

2007-01-01

75

Dimethylcarbene: A singlet ground state?

Ab initio molecular electronic structure theory has been used to determine the energy separation between the lowest Â³Bâ and Â¹A states of dimethylcarbene. The geometries of both states have been optimized at the self-consistent Field(SCF) and the single and double excitation configurationinteraction (CISD) levels of theory using various basis sets. Single point energies at the coupled cluster with single and

Claude A. Richards; Seung-Joon Kim; Yukio Yamaguchi; Henry F. Schaefer

1995-01-01

76

An Ergodic Description of Ground States

NASA Astrophysics Data System (ADS)

Given a translation-invariant Hamiltonian , a ground state on the lattice is a configuration whose energy, calculated with respect to , cannot be lowered by altering its states on a finite number of sites. The set formed by these configurations is translation-invariant. Given an observable defined on the space of configurations, a minimizing measure is a translation-invariant probability which minimizes the average of . If is the mean contribution of all interactions to the site , we show that any configuration of the support of a minimizing measure is necessarily a ground state.

Garibaldi, Eduardo; Thieullen, Philippe

2015-01-01

77

Fractional Quantum Hall States of Atoms in Optical Lattices

NASA Astrophysics Data System (ADS)

We describe a method to create fractional quantum Hall states of atoms confined in optical lattices. We show that the dynamics of the atoms in the lattice is analogous to the motion of a charged particle in a magnetic field if an oscillating quadrupole potential is applied together with a periodic modulation of the tunneling between lattice sites. In a suitable parameter regime the ground state in the lattice is of the fractional quantum Hall type, and we show how these states can be reached by melting a Mott-insulator state in a superlattice potential. Finally, we discuss techniques to observe these strongly correlated states.

Sørensen, Anders S.; Demler, Eugene; Lukin, Mikhail D.

2005-03-01

78

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

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,

Gennady P. Berman; Evgeny N. Bulgakov; David K. Campbell

1994-01-01

79

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

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,

Gennady Berman; Evgeny Bulgakov; David Campbell

1994-01-01

80

Cavity optomechanics -- beyond the ground state

NASA Astrophysics Data System (ADS)

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.

Meystre, Pierre

2011-06-01

81

Ground State Structure of the Metallic Hydrogen

NASA Astrophysics Data System (ADS)

By using Heine-Abarencov pseudopotential method with mono-parameter rc, the expressions for ground state energy epsilon (rs), pressure P (rs), and bulk modulus B(rs) of metallic hydrogen (fcc, bcc, and hcp structures) are derived. Based on Gibbs free energy function criterion, the calculation shows that cold metallic hydrogen lattice (T = 0K) belongs to hcp structure.

Zhu, Zai-wan; Li, Jun-jie

1998-05-01

82

Sideband Cooling Micromechanical Motion to the Quantum Ground State

The advent of laser cooling techniques revolutionized the study of many atomic-scale systems. This has fueled progress towards quantum computers by preparing trapped ions in their motional ground state, and generating new states of matter by achieving Bose-Einstein condensation of atomic vapors. Analogous cooling techniques provide a general and flexible method for preparing macroscopic objects in their motional ground state, bringing the powerful technology of micromechanics into the quantum regime. Cavity opto- or electro-mechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime, less than a single quantum of motion, has been elusive because sideband cooling has not sufficiently overwhelmed the coupling of mechanical systems to their hot environments. Here, we demonstrate sideband cooling of the motion of a micromechanical oscillator to the quantum ground state. Entering the quantum regime requires a large electromechanical interaction, which is achieved by embedding a micromechanical membrane into a superconducting microwave resonant circuit. In order to verify the cooling of the membrane motion into the quantum regime, we perform a near quantum-limited measurement of the microwave field, resolving this motion a factor of 5.1 from the Heisenberg limit. Furthermore, our device exhibits strong-coupling allowing coherent exchange of microwave photons and mechanical phonons. Simultaneously achieving strong coupling, ground state preparation and efficient measurement sets the stage for rapid advances in the control and detection of non-classical states of motion, possibly even testing quantum theory itself in the unexplored region of larger size and mass.

J. D. Teufel; T. Donner; Dale Li; J. H. Harlow; M. S. Allman; K. Cicak; A. J. Sirois; J. D. Whittaker; K. W. Lehnert; R. W. Simmonds

2011-03-10

83

Ground state connectivity of local Hamiltonians

The study of ground spaces of local Hamiltonians is a fundamental task in condensed matter physics. In terms of computational complexity theory, a common focus has been to estimate a given Hamiltonian's ground state energy. However, from a physics perspective, it is often more relevant to understand the structure of the ground space itself. In this paper, we pursue this latter direction by introducing the physically well-motivated notion of "ground state connectivity" of local Hamiltonians, which captures problems in areas ranging from stabilizer codes to quantum memories. We show that determining how "connected" the ground space of a local Hamiltonian is can range from QCMA-complete to NEXP-complete. As a result, we obtain a natural QCMA-complete problem, a goal which has proven elusive since the conception of QCMA over a decade ago. Our proofs crucially rely on a new technical tool, the Traversal Lemma, which analyzes the Hilbert space a local unitary evolution must traverse under certain conditions, and which we believe may be of independent interest.

Sevag Gharibian; Jamie Sikora

2014-09-10

84

Optical Atomic Clocks for Ground and Space Applications

NASA Astrophysics Data System (ADS)

Optical atomic clocks on ground have now matured to a status where they compete favourably with the best caesium atomic clocks that realize the unit of time in the International System of Units (SI). Optical clocks can have orders of magnitude better short term stability than their radio-frequency counterparts. Even though optical clocks cannot realize the second in the SI better than the best caesium clocks (as long as the definition of the SI second is based on the caesium transition) they can realize the unperturbed center of a quantum transition with much better accuracy and stability. Optical atomic clocks now represent the most accurate measuring devices for applications in technology and basic science. Three alternative routes are followed by optical atomic clocks: In the first approach -the single ion clock -a single quantum absorber is trapped in a field-free region for virtually unlimited time. In neutral atom clocks a large number of atoms trapped in a light field can interrogated in parallel which allows for unprecedented high short-term stability. A very promising third avenue relies on ions where the quantum transition is read out by means of quantum logic techniques. This approach allows to use nearly ideal transitions that are otherwise not accessible. In the first part of this presentation the principles and status of the different types of clocks will be outlined using examples of the PTB's Y b+ single ion clock and the Sr neutral atom lattice clock. Particular emphasis is given to the application of such clocks for advanced applications in science and technology. A number of proposals has been made to utilize the superior properties of optical clocks also for novel science and applications in space and several attempts are under way to realize optical clocks for space applications. Thus, the second part of this contribution will deal with the special requirements for optical clocks in space and the associated similarities and differences of optical clocks for ground and space applications. Furthermore typical applications for optical space clocks for the different approaches will be given.

Riehle, Fritz

85

On the atomic state densities of plasmas produced by the “torche à injection axiale”

The atomic state densities of helium and argon plasmas produced by the microwave driven plasma torch called the “torche à injection axiale” are presented. They are obtained by absolute line intensity measurements of the excited states and by applying the ideal gas law to the ground state. It will be shown that the atomic state distribution function (ASDF) does not

J. Jonkers; H. P. C. Vos; Mullen van der JJAM; E. A. H. Timmermans

1996-01-01

86

Quantum Control and Tomography in the 16-Dimensional Ground Manifold of Atomic Cesium

NASA Astrophysics Data System (ADS)

The standard paradigm for Quantum Information Science involves a collection of qubits, whereas the physical building blocks of a quantum processor or simulator often have more than two accessible levels. Taking advantage of these higher dimensional Hilbert spaces (qudits) requires the development of good laboratory tools for qudit manipulation and readout. We have successfully implemented a protocol for quantum state-to-state mapping in the 16-dimensional hyperfine ground manifold of individual Cesium atoms, using only DC, rf and microwave magnetic fields to drive the atomic evolution. Our control waveforms (rf and ?w phases versus time) are found by numerical optimization, and designed to compensate for errors in the driving and background magnetic fields. Experimentally we achieve a state-to-state mapping fidelity of better than 99%, averaged over a sample of randomly chosen initial and target states. Preliminary results suggest that unitary transformations can be designed and implemented in a similar manner. To perform quantum state tomography, we drive an ensemble of identically prepared atoms with phase modulated rf and ?w fields while performing a continuous weak measurement of an atomic observable via polarization spectroscopy. The resulting measurement record is numerically inverted to obtain an estimate of the unknown quantum state. We have reconstructed the density matrices for a set of randomly chosen pure test states using algorithms based either on least squares fitting or compressed sensing. The latter is slightly more tolerant of experimental errors and achieves an average fidelity above 90%.

Jessen, Poul

2012-06-01

87

Ground-State Energetics of Spin-Aligned Deuterium

NASA Astrophysics Data System (ADS)

Current experimental efforts are aimed at stabilizing electron-spin-aligned atomic deuterium, D(DARR), at densities such that diverse quantum effects can be observed. From the viewpoint of computational many-body theory, the D(DARR) systems are extremely interesting since they provide new examples of strongly interacting fermion systems displaying a range of level degeneracies. Further, spin-aligned deuterium has the special advantage (with respect to helium or nuclear systems) that the pair potential is known to great accuracy. This thesis applies to this novel problem variational Monte Carlo and correlated basis function (CBF) methods which have been successful in describing the ground states of nuclear matter and the helium liquids. The elements of state-independent Jastrow theory are outlined, and we show how one applies Fermi hypernetted chain techniques to construct the radial distribution function leading to the evaluation of the Jastrow energy. We correct the Jastrow model by incorporating state-dependent effects by means of non-orthogonal CBF perturbation theory (only the most important terms of the perturbation expansion of the exact ground-state energy being considered). Accurate Monte Carlo evaluation of the Jastrow energy expectation value allows us to conclude that two species of D(DARR) are self-bound liquids. The variational wave function is then improved by incorporating non-Jastrow correlations, most notably three-body and momentum-dependent correlations. Equations of state for three species of D(DARR) are calculated. Additionally, we study the radial distribution function generated by the ground-state wave function and the related liquid structure function. Results for the momentum distribution and its transform, the one-body density matrix, are also presented. Finally, we compare and contrast the calculational methods used in this study to extract a reasonable procedure which may be applied with confidence in predicting ground -state properties of other new quantum systems.

Panoff, Robert Michael

88

Electronic structure and ground states of transition metals encapsulated in a Si12 hexagonal prism TM atom in a Si12 hexagonal prism cage. The cage geometry is remarkably stable regardless of the type being at the center ``Ar-like atom'' . They also found that for W@Si12 , a regu- lar hexagonal prism Si

Mitas, Lubos

89

Ground state Zeeman coherence effects in an optically pumped cesium beam

The population trapping in a cesium beam induced at low magnetic field by sigma polarized light from a broadband laser diode has been investigated. The dip observed in the fluorescence is interpreted in terms of Zeeman coherences in the ground state which trap the atomic populations. A quantitative description is given through the analysis of the atom light interaction with

G. Théobald; N. Dimarcq; V. Giordano; P. Cérez

1989-01-01

90

Coherent States for the Hydrogen Atom

The long-standing problem of finding coherent states for the (bound state portion of the) hydrogen atom is positively resolved. The states in question: (i) are normalized and are parameterized continuously, (ii) admit a resolution of unity with a positive measure, and (iii) enjoy the property that the temporal evolution of any coherent state by the hydrogen atom Hamiltonian remains a coherent state for all time.

John R. Klauder

1995-11-23

91

Ground states of spin-2 condensates in an external magnetic field

The possible ground states of spin-2 Bose-Einstein condensates in an external magnetic field are obtained analytically and classified systematically according to the population of the condensed atoms at the hyperfine sublevels. It is shown that the atoms can populate simultaneously at four hyperfine sublevels in a weak magnetic field with only the linear Zeeman energy, in contrast to that in a stronger magnetic field with the quadratic Zeeman energy, where condensed atoms can at most populate at three hyperfine sublevels in the ground states. Any spin configuration we obtained will give a closed subspace in the order parameter space of the condensates.

Zheng, G.-P.; Tong, Y.-G.; Wang, F.-L. [Department of Physics, Henan Normal University, Xinxiang, Henan 453007 (China)

2010-06-15

92

Lossless state detection of single neutral atoms.

We introduce lossless state detection of trapped neutral atoms based on cavity-enhanced fluorescence. In an experiment with a single 87Rb atom, a hyperfine-state-detection fidelity of 99.4% is achieved in 85???s. The quantum bit is interrogated many hundreds of times without loss of the atom while a result is obtained in every readout attempt. The fidelity proves robust against atomic frequency shifts induced by the trapping potential. Our scheme does not require strong coupling between the atom and cavity and can be generalized to other systems with an optically accessible quantum bit. PMID:20867026

Bochmann, J; Mücke, M; Guhl, C; Ritter, S; Rempe, G; Moehring, D L

2010-05-21

93

Atomic Fock State Preparation Using Rydberg Blockade

NASA Astrophysics Data System (ADS)

We use coherent excitation of 3-16 atom ensembles to demonstrate collective Rabi flopping mediated by Rydberg blockade. Using calibrated atom number measurements, we quantitatively confirm the expected ?N Rabi frequency enhancement to within 4%. The resulting atom number distributions are consistent with an essentially perfect blockade. We then use collective Rabi ? pulses to produce N =1, 2 atom number Fock states with fidelities of 62% and 48%, respectively. The N=2 Fock state shows the collective Rabi frequency enhancement without corruption from atom number fluctuations.

Ebert, Matthew; Gill, Alexander; Gibbons, Michael; Zhang, Xianli; Saffman, Mark; Walker, Thad G.

2014-01-01

94

Geometric renormalization below the ground state

The caloric gauge was introduced by Tao with studying large data energy critical wave maps mapping from $\\mathbf{R}^{2+1}$ to hyperbolic space $\\mathbf{H}^m$ in view. In \\cite{BIKT} Bejenaru, Ionescu, Kenig, and Tataru adapted the caloric gauge to the setting of Schr\\"odinger maps from $\\mathbf{R}^{d + 1}$ to the standard sphere $S^2 \\hookrightarrow \\mathbf{R}^3$ with initial data small in the critical Sobolev norm. Here we develop the caloric gauge in a bounded geometry setting with a construction valid up to the ground state energy.

Paul Smith

2011-12-06

95

Best Possible Strategy for Finding Ground States

Finding the ground state of a system with a complex energy landscape is important for many physical problems including protein folding, spin glasses, chemical clusters, and neural networks. Such problems are usually solved by heuristic search methods whose efficacy is judged by empirical performance on selected examples. We present a proof that, within the large class of algorithms that simulate a random walk on the landscape, threshold accepting is the best possible strategy. In particular, it can perform better than simulated annealing and Tsallis statistics. Our proof is the first example of a provably optimal strategy in this area.

Franz, Astrid; Hoffmann, Karl Heinz; Salamon, Peter

2001-06-04

96

Weak value amplification of atomic cat states

We show the utility of the weak value measurement to observe the quantum interference between two close lying atomic coherent states in a post-selected atomic cat state, produced in a system of $N$ identical two-level atoms weakly interacting with a single photon field. Through the observation of the negative parts of the Wigner distribution of the post-selected atomic cat state, we find that the post-selected atomic cat state becomes more nonclassical when the post-selected polarization state of the single photon field tends toward becoming orthogonal to its pre-selected state. We show that the small phase shift in the post-selected atomic cat state can be amplified via measuring the peak shift of its phase distribution when the postselected state of the single photon field is nearly orthogonal to its preselected state. We find that the amplification factor of of 15 [5] can be obtained for a sample of 10 [100] atoms.

Sumei Huang; Girish S. Agarwal

2015-01-10

97

Quantum Rabi Model for N-State Atoms

NASA Astrophysics Data System (ADS)

A tractable N-state Rabi Hamiltonian is introduced by extending the parity symmetry of the two-state model. The single-mode case provides a few-parameter description of a novel class of periodic systems, predicting that the ground state of certain four-state atom-cavity systems will undergo parity change at strong-coupling. A group-theoretical treatment provides physical insight into dynamics and a modified rotating wave approximation obtains accurate analytical energies. The dissipative case can be applied to study excitation energy transfer in molecular rings or chains.

Albert, Victor V.

2012-05-01

98

Quantum Rabi model for N-state atoms.

A tractable N-state Rabi Hamiltonian is introduced by extending the parity symmetry of the two-state model. The single-mode case provides a few-parameter description of a novel class of periodic systems, predicting that the ground state of certain four-state atom-cavity systems will undergo parity change at strong-coupling. A group-theoretical treatment provides physical insight into dynamics and a modified rotating wave approximation obtains accurate analytical energies. The dissipative case can be applied to study excitation energy transfer in molecular rings or chains. PMID:22681049

Albert, Victor V

2012-05-01

99

Testing quantum electrodynamics in the lowest singlet states of beryllium atom Mariusz Puchalski of the beryllium atom. Calcu- lations are performed using fully correlated Gaussian basis sets and taking predictions for the ionization potential of the beryllium ground state 75 192.696(8) cm-1 and the 21 P 21

Pachucki, Krzysztof

100

Time-dependent quantum Monte Carlo: preparation of the ground state

NASA Astrophysics Data System (ADS)

We study one-dimensional (1D) and 2D helium atoms using a new time-dependent quantum Monte Carlo (TDQMC) method. The TDQMC method employs random walkers, with a separate complex-valued guiding wave attached to each walker. The ground state is calculated by a self-consistent solution of complex-time Schrödinger equations for the guiding waves and of equations for the velocity fields of the walkers. Our results show that the many-body wavefunction and the ground state energy of the model atoms are very close to those predicted by the standard diffusion quantum Monte Carlo method. The obtained ground state can further be used to examine correlated time-dependent processes which include, for example, interaction of atoms and molecules with external electromagnetic fields.

Christov, I. P.

2007-03-01

101

The ground and excited states of hydrogen sulfide, methanethiol, and hydrogen selenide

Ab initio SCF and CI investigations of the ground and excited singlet electronic states of hydrogen sulfide 1, methanethiol 2, and hydrogen selenide 3 have been carried out. The moderately large atomic basis sets are augmented by bond functions for polarization and by sets of diffuse s and p functions to enable the description of the lower Rydberg excited states.

Arvi Rauk; Scott Collins

1984-01-01

102

Quantum States of Atoms and Molecules

NSDL National Science Digital Library

Quantum States of Atoms and Molecules is an introduction to quantum mechanics as it relates to spectroscopy, the electronic structure of atoms and molecules, and molecular properties. A digital, living textbook, it provides opportunities not found in conventional textbooks opportunities that allow students to develop skills in information processing, critical thinking or analytical reasoning, and problem solving that are so important for success.

103

Ground state of high-density matter

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

104

Thermodynamic ground states of platinum metal nitrides

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.

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

2007-10-09

105

Preparation and determination of spin-polarized states in multi-Zeeman-sublevel atoms

We demonstrate a simple, all-optical technique to prepare and determine the desired internal quantum states in multi-Zeeman-sublevel atoms. By choosing appropriate coupling and pumping laser beams, atoms can be easily prepared in a desired Zeeman sublevel with high purity or in any chosen ground-state population distributions (spin-polarized quantum-state engineering). The population distributions or state purities of such prepared atomic states can be determined by using a weak, circularly polarized probe beam due to differences in transition strengths among different Zeeman sublevels. This technique will have potential impact on quantum-information processing in multilevel atomic systems.

Wang, Bo; Han, Yanxu; Xiao, Jintao; Yang, Xudong; Zhang, Chunhong; Wang, Hai; Peng, Kunchi [The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Xiao, Min [The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

2007-05-15

106

NASA Astrophysics Data System (ADS)

We present a scheme for implementing the deterministic quantum state sharing of an arbitrary three-atom state by using a five-atom cluster state and a Bell-state in cavity QED. In the scheme, it does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of decoherence.

Nie, Yi-you; Xu, Yue; Li, Yuan-hua; Sang, Ming-huang

2014-04-01

107

Manipulation of Nonclassical Atomic Spin States

We report successful manipulation of nonclassical atomic spin states. We apply an off-resonant noncircularly-polarized light pulse to a measurement-induced squeezed spin state of a cold atomic ensemble. By changing the pulse duration, we clearly observe a rotation of the anisotropic quantum-noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum-noise distribution is always isotropic. This is an important step for quantum state tomography, quantum swapping, and precision spectroscopic measurement.

Takano, Tetsushi; Tanaka, Shin-Ichi-Ro; Namiki, Ryo [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Takahashi, Yoshiro [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

2010-01-08

108

Scattering length of the ground-state MgMg collision E. Tiesinga, S. Kotochigova, and P. S. Julienne

can be magneto- optically trapped. This offers many possible applications of cold Mg atoms for ultra coefficients. At temperatures below 5 mK ground state Mg collisions are in the s-wave scattering regime

Kotochigova, Svetlana

109

Strangeness in the baryon ground states

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

110

Preparation of ultralow atomic velocities by transforming bound states into tunneling resonances

A procedure is proposed to prepare the average and width of the velocity distribution of ultracold atoms. The atoms are set initially in the ground state of an optical trap formed by an inner red-detuned-laser well and an outer blue-detuned-laser barrier. Then the well and barrier parameters are changed until the ground state becomes a Breit-Wigner tunneling resonance. An optimal time dependence of the switching process, between the sudden and adiabatic limits, adjusts the final translational energies of the leaking atoms to the Lorentzian distribution of the resonance state.

Delgado, F. [Departamento de Fisica Basica, Universidad de La Laguna, La Laguna, Tenerife (Spain); Departamento de Quimica-Fisica, UPV-EHU, Apartado 644, 48080 Bilbao (Spain); Muga, J. G. [Departamento de Quimica-Fisica, UPV-EHU, Apartado 644, 48080 Bilbao (Spain); Ruschhaupt, A. [Institut fuer Mathematische Physik, TU Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig (Germany)

2006-12-15

111

Pyramidal atoms: Berylliumlike hollow states

Based on the idea that four excited electrons arrange themselves around the nucleus in the corners of a pyramid in order to minimize their mutual repulsion, we present an analytical model of quadruply excited states. The model shows excellent comparison with ab initio results and provides a clear physical picture of the intrinsic motion of the four electrons. The model is used to predict configuration-mixing fractions and spectra of these highly correlated states.

Poulsen, Marianne Dahlerup; Madsen, Lars Bojer [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)

2005-06-15

112

Creating collective many-body states with highly excited atoms

The collective excitation of a gas of highly excited atoms confined to a large spacing ring lattice is studied, where the ground and the excited states are resonantly coupled via a laser field. Attention is focused on the regime where the interaction between the highly excited atoms is very weak in comparison to the Rabi frequency of the laser. In this case, the many-body excitations of the system can be expressed in terms of free spinless fermions. The complex many-particle states arising in this regime are characterized and their properties, for example their correlation functions, are studied. Additional investigation into how some of these many-particle states can actually be experimentally accessed by a temporal variation of the laser parameters is performed.

Olmos, B. [Instituto 'Carlos I' de Fisica Teorica y Computacional and Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD United Kingdom (United Kingdom); Gonzalez-Ferez, R. [Instituto 'Carlos I' de Fisica Teorica y Computacional and Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Lesanovsky, I. [Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD United Kingdom (United Kingdom)

2010-02-15

113

Creating and probing coherent atomic states

The authors present a brief review of recent experimental and theoretical time resolved studies of the evolution of atomic wavepackets. In particular, wavepackets comprising a superposition of very-high-lying Rydberg states which are created either using a short half-cycle pulse (HCP) or by rapid application of a DC field. The properties of the wavepackets are probed using a second HCP that is applied following a variable time delay and ionizes a fraction of the atoms, much like a passing-by ion in atomic collisions.

Reinhold, C.O.; Burgdoerfer, J. [Oak Ridge National Lab., TN (United States). Physics Div.]|[Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Frey, M.T.; Dunning, F.B. [Rice Univ., Houston, TX (United States)

1997-06-01

114

Fisher-like atomic divergences: Mathematical grounds and physical applications

NASA Astrophysics Data System (ADS)

Two different local divergence measures, the Fisher (FD) and the Jensen-Fisher (JFD) ones, are compared in this work by applying them to atomic one-particle densities in position and momentum spaces. They are defined in terms of the absolute and the relative Fisher information functionals. The analysis here afforded includes not only neutral atoms, but also singly-charged cations. The results are interpreted and justified according to (i) shell-filling patterns, (ii) short- and long-range behaviors of the atomic densities, and (iii) the value of the atomic ionization potential. The strengths of the FD measure, as compared to the JFD one, are emphasized.

Martín, A. L.; Angulo, J. C.; Antolín, J.

2013-11-01

115

Rugged landscapes and the “Quantori” ground state of 1D quantum systems of adatoms on substrates

We study the landscape of the ground state (“Quantori”) of the quantum Frenkel-Kontorova (FK) model in the “strong coupling” regime in which in the corresponding classical limit the coordinates of the atoms are distributed on “Cantori”. For the intermediate quantum regime, defined as the region in which the natural quantum energy scale and the natural classical energy scale are comparable,

Gennady P. Berman; Evgeny N. Bulgakov; David K. Campbell

1997-01-01

116

Rugged landscapes and the ``Quantori'' ground state of 1D quantum systems of adatoms on substrates

We study the landscape of the ground state (``Quantori'') of the quantum Frenkel-Kontorova (FK) model in the ``strong coupling'' regime in which in the corresponding classical limit the coordinates of the atoms are distributed on ``Cantori''. For the intermediate quantum regime, defined as the region in which the natural quantum energy scale and the natural classical energy scale are comparable,

Gennady P. Berman; Evgeny N. Bulgakov; David K. Campbell

1997-01-01

117

Metastable Helium: A New Determination of the Longest Atomic Excited-State Lifetime

NASA Astrophysics Data System (ADS)

Exited atoms may relax to the ground state by radiative decay, a process which is usually very fast (of order nanoseconds). However, quantum-mechanical selection rules can prevent such rapid decay, in which case these “metastable” states can have lifetimes of order seconds or longer. In this Letter, we determine experimentally the lifetime of the longest-lived neutral atomic state—the first excited state of helium (the 2S13 metastable state)—to the highest accuracy yet measured. We use laser cooling and magnetic trapping to isolate a cloud of metastable helium (He*) atoms from their surrounding environment, and measure the decay rate to the ground 1S01 state via extreme ultraviolet (XUV) photon emission. This is the first measurement using a virtually unperturbed ensemble of isolated helium atoms, and yields a value of 7870(510) seconds, in excellent agreement with the predictions of quantum electrodynamic theory.

Hodgman, S. S.; Dall, R. G.; Byron, L. J.; Baldwin, K. G. H.; Buckman, S. J.; Truscott, A. G.

2009-07-01

118

On the ground state of Yang-Mills theory

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.

Bakry, Ahmed S., E-mail: abakry@physics.adelaide.edu.au [Special Research Center for the Subatomic Structure of Matter, Department of Physics, University of Adelaide, South Australia 5005 (Australia); Leinweber, Derek B.; Williams, Anthony G. [Special Research Center for the Subatomic Structure of Matter, Department of Physics, University of Adelaide, South Australia 5005 (Australia)

2011-08-15

119

Theory of Ground State Factorization in Quantum Cooperative Systems

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

Salvatore M. Giampaolo; Gerardo Adesso; Fabrizio Illuminati

2008-01-01

120

Interaction of Helium Rydberg State Atoms with Superfluid Helium

NASA Astrophysics Data System (ADS)

The pair potentials between ground state helium and Rydberg He atoms are calculated by the full configuration interaction electronic structure method for both the electronic singlet and the triplet manifolds. The obtained pair potentials are validated against existing experimental molecular and atomic data. Most states show remarkable energy barriers at long distances ( Å), which can effectively stabilize He against the formation of He at low nuclear kinetic energies. Bosonic density functional theory calculations, based on the calculated pair potential data, indicate that the triplet ground state He reside in spherical bubbles in superfluid helium with a barycenter radius of 6.1 Å at the liquid saturated vapor pressure. The pressure dependency of the relative He absorption line blue shift in the liquid was obtained through both the statistical line broadening theory as well as the dynamic adiabatic following method. The pronounced difference between the results from the static and dynamic models is attributed to the dynamic Jahn-Teller effect that takes places in the electronically excited state within the dephasing time of 150 fs. Transient non-thermalized liquid surroundings near He may contribute to an artificial reduction in the absorption line blue shift by up to 30 cm.

Fiedler, Steven L.; Eloranta, Jussi

2014-03-01

121

Atomic Schroedinger cat-like states

After a short overview of the basic mathematical structure of quantum mechanics we analyze the Schroedinger's antinomic example of a living and dead cat mixed in equal parts. Superpositions of Glauber kets are shown to approximate such macroscopic states. Then, two-level atomic states are used to construct mesoscopic kittens as appropriate linear combinations of angular momentum eigenkets for j = 1/2. Some general comments close the present contribution.

Enriquez-Flores, Marco [Departamento de Fisica, Escuela Superior de Fisica y Matematicas, IPN Edificio 9, Unidad Profesional Adolfo Lopez Mateos, Mexico D.F. 07738 (Mexico); Rosas-Ortiz, Oscar [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-364, Mexico D.F. 01000 (Mexico); Departamento de Fisica, Cinvestav, A.P. 14-740, Mexico D.F. 07000 (Mexico)

2010-10-11

122

Cold Rydberg atoms in circular states

NASA Astrophysics Data System (ADS)

Circular-state Rydberg atoms are interesting in that they exhibit a unique combination of extraordinary properties; long lifetimes (˜n^5), large magnetic moments (l=|m|=n-1) and no first order Stark shift. Circular states have found applications in cavity quantum electrodynamics and precision measurements [1,2], among other studies. In this work we present the production of circular states in an atom trapping apparatus using an adiabatic state-switching method (the crossed-field method [3]). To date, we have observed lifetimes of adiabatically prepared states of several milliseconds. Their relatively large ionization electric fields have been verified by time-of-flight signatures of ion trajectories. We intend to explore the magnetic trapping of circular state Rydberg atoms, as well as their production and interaction properties in ultra-cold and degenerate samples.[4pt] [1] P. Bertet et al., Phys. Rev. Lett., 88, 14 (2002)[0pt] [2] M. Brune et al., Phys. Rev. Lett., 72, 21 (1994)[0pt] [3] D. Delande and J.C. Gay, Europhys. Lett., 5, 303-308 (1988).

Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

2012-06-01

123

Radial ground states and singular ground states for a spatial-dependent p-Laplace equation

NASA Astrophysics Data System (ADS)

We consider the following equation ?u(x)+f(u,|x|)=0, where x?R, n>p>1, and we assume that f is negative for |u| small and lim{f(u,0)}/{u|}=a>0 where p={p(n-1)}/{n-p}2. We manage to prove the existence of a radial ground state, for more generic functions f(u,|x|) and also in the case p>2 and 1

ground states under very weak hypotheses. The proofs combine an energy analysis and a shooting method. We also make use of Wazewski's principle to overcome some difficulties deriving from the lack of regularity.

Franca, Matteo

124

Dissociative recombination of the ground state of N2(+)

NASA Technical Reports Server (NTRS)

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.

Guberman, Steven L.

1991-01-01

125

Ground state and excited state dipole moments of alkyl substituted para-nitroaniline derivatives.

The ground state and excited state dipole moment of a series of alkyl substituted para-nitroaniline derivatives is reported. Ground state dipole moment was determined by the Debye-Guggenheim method and the excited state dipole moment was estimated using the solvatochromic method. For all molecules under investigation, the excited state dipole moment was found to be higher than the ground state dipole moment. The molecules exhibited positive solvatochromism. PMID:18524672

Dhanya, R; Kishore, V C; Sudha Kartha, C; Sreekumar, K; Joseph, Rani

2008-12-15

126

NASA Astrophysics Data System (ADS)

Potential curves of the ground state of the KrXe molecule and its excited states that converge to the Kr(4 p 6 1 S 0) + Xe(5 p 56 s 3 P 1) atomic states are corrected and tested using the results of modeling published vacuum ultraviolet spectra of a gas-discharge plasma of a krypton/xenon mixture.

Loginov, A. V.

2013-09-01

127

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

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.

Apaja, Vesa; Syljuaasen, Olav F. [Institut fuer Theoretische Physik, Johannes-Kepler Universitaet, A-4040 Linz (Austria); Nordita, Blegdamsvej 17, DK-2100, Copenhagen O (Denmark)

2006-09-15

128

Ground State Instabilities and Entanglement in the Detuned Dicke Model

Ground state instabilities of the spin-boson model is studied in this work. The existence of sequential ground state instabilities is shown analytically for arbitrary detuning in the two-spin system. In this model, extra discontinuities of concurrence(entanglement measure) are found in the finite system, which do not appear in the on-resonant model. The above results remain intact by including extra boson modes. Moreover, by including extra modes, it is found that ground state entanglement can be obtained and enhanced even in the weak coupling regime.

Ru-Fen Liu; Chia-Chu Chen

2005-10-11

129

Designed Diamond Ground State via Optimized Isotropic Monotonic Pair Potentials

We apply inverse statistical-mechanical methods to find a simple family of optimized isotropic, monotonic pair potentials, under certain constraints, whose ground states for a wide range of pressures is the diamond crystal. These constraints include desirable phonon spectra and the widest possible pressure range for stability. We also ascertain the ground-state phase diagram for a specific optimized potential to show that other crystal structures arise for other pressures. Cooling disordered configurations interacting with our optimized potential to absolute zero frequently leads to the desired diamond crystal ground state, revealing that the capture basin for the global energy minimum is large and broad relative to the local energy minima basins.

Etienne Marcotte; Frank H. Stillinger; Salvatore Torquato

2012-12-15

130

We investigate the behavior of an ensemble of N non-interacting, identical atoms, excited by a laser with a wavelength of $\\lambda$. In general, the i-th atom sees a Rabi frequency $\\Omega_i$, an initial position dependent laser phase $\\phi_i$, and a motion induced Doppler shift of $\\delta_i$. When $\\Omega_i=\\Omega$ and $\\delta_i=\\delta$ for all atoms, the system evolves into a superposition of (N+1) symmetric collective states (SCS), independent of the values of $\\phi_i$. If $\\phi_i=\\phi$ for all atoms, these states simplify to the well-known Dicke collective states. When $\\Omega_i$ or $\\delta_i$ is distinct for each atom, the system evolves into a superposition of SCS as well as asymmetric collective states (ACS). For large N, the number of ACS's $(2^N-N-1)$ is far greater than that of the SCS. We show how to formulate the properties of all the collective states under various non-idealities, and use this formulation to understand the dynamics thereof. For the case where $\\Omega_i=\\Omega$ and $\\delta_i=\\delta$ for all atoms, we show how to determine the amplitudes of the generalized collective states in a simple manner. For the case where $\\Omega_i$ or $\\delta_i$ is distinct for each atom, we show how the SCS and ACS's can be treated on the same footing. Furthermore, we show that the collective states corresponding to the absorption of a given number of photons can be visualized as an abstract, multi-dimensional rotation in the Hilbert space spanned by the ordered product states of individual atoms. We also consider the effect of treating the center of mass degree of freedom of the atoms quantum mechanically on the description of the collective states. Specifically, we show that it is indeed possible to construct a generalized collective state, as needed for the collective state atomic interferometer we recently proposed, when each atom is assumed to be in a localized wave packet.

Resham Sarkar; May E. Kim; Renpeng Fang; Yanfei Tu; Selim M. Shahriar

2014-10-10

131

Internal state manipulation for neutral atom lithography

NASA Astrophysics Data System (ADS)

We examine how the manipulation of the internal states of atoms can be used for atom lithography. Metastable argon atoms pattern a substrate by activating the growth of a carbonaceous material on the surface. We develop resist/etch systems that support 20 nm feature sizes, 2:1 aspect ratios, and 103 feature height amplification. Gold, silver, silicon, silicon dioxide, and silicon nitride substrates are patterned. Standing wave quenching (SWQ) light masks are used to create 65nm- wide features spaced 401 nm apart. One application of SWQ is to create a length reference artifact. We present a detailed error budget for the pattern periodicity, and find that an accuracy of better than one part in 106 is possible. We demonstrate atom resonance lithography (ARL), the first use of frequency encoding of spatial information for atom lithography. ARL has the potential to create patterns in two dimensions whose feature size is smaller than 20 nm and whose spacing is not limited by the wavelength of the patterning light. We form features in silicon that are 2.2 ?m wide and spaced 20 ?m apart. Using multiple probe frequencies, we demonstrate that multiple features can be created over the area covered by a monotonic gradient. The appendices include original contributions to the theory of manipulating atoms using micro- electromagnets. We propose several ways to create a magnetic waveguide using microfabricated wire patterns on a surface. We also discuss several implications of tight confinement: single mode atom guides, elongated traps with quasi-one-dimensional energetics, and constrictions whose conductance is quantized.

Thywissen, Joseph Hermann

2000-11-01

132

GROUND-WATER POLLUTION PROBLEMS IN THE SOUTHEASTERN UNITED STATES

An evaluation of principal sources of ground-water contamination has been carried out in seven southeastern States--Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, and Virginia. Natural ground-water quality is good to excellent, except for the presence of ...

133

Unfavored ? decay from ground state to ground state in the range 53?Z?91

NASA Astrophysics Data System (ADS)

Within the density-dependent cluster model, we have systematically investigated partial ?-decay half-lives of ground-state (g.s.)-to-g.s. transitions. Emphasis is placed on the unfavored ? transitions in the range 53?Z?91 of both odd-A and odd-odd nuclei. The ?-preformation factor is estimated by means of the multiplication of the valence proton and neutron numbers NPNN, in addition to the constant formation factor for one kind of nuclei. By introducing a centrifugal term, the previous empirical relation for ?-decay half-lives of our group is improved to reproduce a large number of experimental data including these unfavored transitions. Whatever concerns the theoretical calculation or the analytical expression, the agreement between theory and experiment is satisfied. This indicates that these studied unfavored g.s.-to-g.s. ? decays can be reasonably described within the present approach extended from the treatment of favored ones.

Qian, Yibin; Ren, Zhongzhou

2012-02-01

134

Approximating the ground state of gapped quantum spin systems

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^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, X, of V the ground state projector can be approximated by the product of two projections, one supported on X and one supported on X^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.

Eman Hamza; Spyridon Michalakis; Bruno Nachtergaele; Robert Sims

2009-04-29

135

Separability and ground state factorization in quantum spin systems

We investigate the existence and the properties of fully separable (fully factorized) ground states in quantum spin systems. Exploiting techniques of quantum information and entanglement theory we extend a recently introduced method and construct a general, self-contained theory of ground state factorization in frustration-free quantum spin models defined on lattices in any spatial dimension and for interactions of arbitrary range. We show that, quite generally, non exactly solvable models in external field admit exact, fully factorized ground state solutions. Unentangled ground states occur at finite values of the Hamiltonian parameters satisfying well defined balancing conditions between external fields and interaction strengths. These conditions are analytically determined together with the type of magnetic orderings compatible with factorization and the corresponding values of the fundamental observables such as energy and magnetization. The method is applied to a series of examples of increasing complexi...

Giampaolo, S M; Illuminati, F

2009-01-01

136

Approximating the ground state of gapped quantum spin systems

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.

Michalakis, Spyridon [Los Alamos National Laboratory; Hamza, Eman [NON LANL; Nachtergaele, Bruno [NON LANL; Sims, Robert [NON LANL

2009-01-01

137

Multidomain and ground state configurations of two-phase vesicles

A simple model is used to study the equilibrium of lipid domains on two-phase vesicles. Two classes of configurations are considered: multidomain and ground state configurations. For multidomain configurations, the vesicle has a finite number of identical lipid domains. For ground state configurations, the vesicle is fully phase separated into two coexisting domains. Whereas the volume enclosed by a vesicle with multidomains is fixed, the volume enclosed by a vesicle in a ground state is allowed to vary with the osmotic pressure. Guided by experimental observations, all domains are assumed to be spherical caps. In a multidomain configuration, the line tension is found to decrease with the number of domains present, with possible exceptions when the number of domains is very small. The importance of a critical osmotic pressure and a critical excess radius on ground state configurations is explored. Emphasis is placed on understanding the variations of these critical quantities with relevant parameters. PMID:23516066

Maleki, Mohsen; Fried, Eliot

2013-01-01

138

Nonplanar ground states of frustrated antiferromagnets on an octahedral lattice

We consider methods to identify the classical ground state for an exchange-coupled Heisenberg antiferromagnet on a non-Bravais lattice with interactions J[subscript ij] to several neighbor distances. Here, we apply this ...

Henley, Christopher L.

139

G magnetic field. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman the Doppler effect broadens the range of the magnetic fields where the effect is visible and reduces the size superpositions of Zeeman sublevels of an atomic ground state. Such superpositions (Zeeman coher- ences) result

140

Theory of ground state factorization in quantum cooperative systems

We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows to determine rigorously existence, location, and exact form of separable ground states in a large variety of, generally non-exactly 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.

S. M. Giampaolo; G. Adesso; F. Illuminati

2008-04-01

141

Theory of ground state factorization in quantum cooperative systems

We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows to determine rigorously existence, location, and exact form of separable ground states in a large variety of, generally non-exactly 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.

Giampaolo, S M; Illuminati, F

2008-01-01

142

Theory of ground state factorization in quantum cooperative systems.

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. PMID:18518481

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

2008-05-16

143

Ground state hyperfine structure in muonic lithium ions

On the basis of perturbation theory in fine structure constant alpha and the ratio of electron to muon masses we calculate one-loop vacuum polarization, electron vertex corrections, nuclear structure and recoil corrections to hyperfine splitting of the ground state in muonic lithium ions $(\\mu\\ e\\ ^6_3Li)^+$ and $(\\mu\\ e\\ ^7_3Li)^+$. We obtain total results for the ground state small hyperfine splittings in $(\\mu\\ e\\ ^6_3Li)^+$ $\\Delta\

A. P. Martynenko; A. A. Ulybin

2014-11-21

144

Atomic state teleportation: from internal to external degrees of freedom

We suggest a simple method to teleport an unknown superposition of the atomic internal state of a two-level atom onto transverse atomic momenta of another atom during its flight. The scheme relies on the standard cavity QED techniques and is inherently deterministic with sufficiently high fidelity for the teleported state. It is further shown that the procedure can be straightforwardly

R. Ul-Islam; M. Ikram; R. Ahmed; A. H. Khosa; F. Saif

2009-01-01

145

On the atomic state densities of plasmas produced by the ``torche à injection axiale''

NASA Astrophysics Data System (ADS)

The atomic state densities of helium and argon plasmas produced by the microwave driven plasma torch called the "torche à injection axiale" are presented. They are obtained by absolute line intensity measurements of the excited states and by applying the ideal gas law to the ground state. It will be shown that the atomic state distribution function (ASDF) does not obey the Saha-Boltzmann law: the ASDF cannot be described by one temperature. From the shape of the ASDF it can be concluded that the plasma is ionising. By extrapolating the measured state densities towards the ionisation limit, a minimum value of the electron density can be determined.

Jonkers, J.; Vos, H. P. C.; van der Mullen, J. A. M.; Timmermans, E. A. H.

1996-04-01

146

Wave Function Microscopy of Quasibound Atomic States

NASA Astrophysics Data System (ADS)

In the 1980s Demkov, Kondratovich, and Ostrovsky and Kondratovich and Ostrovsky proposed an experiment based on the projection of slow electrons emitted by a photoionized atom onto a position-sensitive detector. In the case of resonant excitation, they predicted that the spatial electron distribution on the detector should represent nothing else but a magnified image of the projection of a quasibound electronic state. By exciting lithium atoms in the presence of a static electric field, we present in this Letter the first experimental photoionization wave function microscopy images where signatures of quasibound states are evident. Characteristic resonant features, such as (i) the abrupt change of the number of wave function nodes across a resonance and (ii) the broadening of the outer ring of the image (associated with tunneling ionization), are observed and interpreted via wave packet propagation simulations and recently proposed resonance tunneling mechanisms. The electron spatial distribution measured by our microscope is a direct macroscopic image of the projection of the microscopic squared modulus of the electron wave that is quasibound to the atom and constitutes the first experimental realization of the experiment proposed 30 years ago.

Cohen, S.; Harb, M. M.; Ollagnier, A.; Robicheaux, F.; Vrakking, M. J. J.; Barillot, T.; Lépine, F.; Bordas, C.

2013-05-01

147

Wave function microscopy of quasibound atomic states.

In the 1980s Demkov, Kondratovich, and Ostrovsky and Kondratovich and Ostrovsky proposed an experiment based on the projection of slow electrons emitted by a photoionized atom onto a position-sensitive detector. In the case of resonant excitation, they predicted that the spatial electron distribution on the detector should represent nothing else but a magnified image of the projection of a quasibound electronic state. By exciting lithium atoms in the presence of a static electric field, we present in this Letter the first experimental photoionization wave function microscopy images where signatures of quasibound states are evident. Characteristic resonant features, such as (i) the abrupt change of the number of wave function nodes across a resonance and (ii) the broadening of the outer ring of the image (associated with tunneling ionization), are observed and interpreted via wave packet propagation simulations and recently proposed resonance tunneling mechanisms. The electron spatial distribution measured by our microscope is a direct macroscopic image of the projection of the microscopic squared modulus of the electron wave that is quasibound to the atom and constitutes the first experimental realization of the experiment proposed 30 years ago. PMID:23683194

Cohen, S; Harb, M M; Ollagnier, A; Robicheaux, F; Vrakking, M J J; Barillot, T; Lépine, F; Bordas, C

2013-05-01

148

Ground-Water Availability in the United States

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.

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

2008-01-01

149

Analytical ground state for the Jaynes-Cummings model with ultrastrong coupling

We present a generalized variational method to analytically obtain the ground-state properties of the Jaynes-Cummings model with the ultrastrong coupling. An explicit expression for the ground-state energy, which agrees well with the numerical simulation in a wide range of the experimental parameters, is given. In particular, the introduced method can successfully solve this Jaynes-Cummings model with the positive detuning (the atomic resonant level is larger than the photon frequency), which cannot be treated in the adiabatical approximation and the generalized rotating-wave approximation. Finally, we also demonstrate analytically how to control the mean photon number by means of the current experimental parameters including the photon frequency, the coupling strength, and especially the atomic resonant level.

Zhang Yuanwei [State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006 (China); Institute of Theoretical Physics, Shanxi University, Taiyuan 030006 (China); Chen Gang [State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006 (China); Department of Physics, Shaoxing University, Shaoxing 312000 (China); Yu Lixian; Liang Qifeng [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Liang, J.-Q. [Institute of Theoretical Physics, Shanxi University, Taiyuan 030006 (China); Jia Suotang [State Key Laboratory of Quantum Optics and Quantum Optics Devices, College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006 (China)

2011-06-15

150

Estimation of ground state pentaquark masses

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

151

Nondestructive Fluorescent State Detection of Single Neutral Atom Qubits

We demonstrate non-destructive (loss-less) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one-and-the-same single atom.

Michael J. Gibbons; Christopher D. Hamley; Chung-Yu Shih; Michael S. Chapman

2010-12-08

152

Nondestructive Fluorescent State Detection of Single Neutral Atom Qubits

We demonstrate non-destructive (loss-less) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one-and-the-same single atom.

Gibbons, Michael J; Shih, Chung-Yu; Chapman, Michael S

2010-01-01

153

What is the ground electronic state of KO?

NASA Astrophysics Data System (ADS)

High-level, restricted coupled cluster with singles, doubles, and perturbative triples calculations are performed to determine the ground electronic state of KO. In the absence of spin-orbit coupling, we find that the ground state is a 2Sigma+ state, with a 2Pi state lying just over 200 cm-1 higher in energy. We ascertain that basis set extension, higher-order correlation energy, mass-velocity, and Darwin relativistic terms do not change this ordering. We then calculate the low-lying Omega states when spin-orbit coupling is turned on. The 2Sigma1/2+ state undergoes an avoided crossing with the 2Pi1/2 state, and we therefore designate the ground state as X1/2. This state is essentially 2Sigma1/2+ at short R, but essentially 2Pi1/2 at long R; there is a corresponding A1/2 state with the opposite behavior. These states have significantly different shapes and so spectroscopy from the adiabatic states. Finally, we calculate the dissociation energy D0, of KO as 66plus-or-minus1 kcal mol-1 and derive DeltaHf(KO, 0 K) as 13.6plus-or-minus1 kcal mol-1.

Lee, Edmond P. F.; Soldan, Pavel; Wright, Timothy G.

2002-11-01

154

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 state. PMID:23843744

Andrews, Logan D.; Fenn, Tim D.; Herschlag, Daniel

2013-01-01

155

A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has been developed and ported on a SIMDMIMD parallel platform. The SIMD part of the parallel platform is represented by a Quadrics\\/APE100 consisting of 512 floating point units while the MIMD part is formed by a cluster of workstations. The proposed algorithm contains a part where the genetic

N. Pucello; M. Rosati; Massimo Celino; G. D'agostino; F. Pisacane; Vittorio Rosato

1996-01-01

156

High-speed ground transportation development outside United States

This paper surveys the state of high-speed (in excess of 200 km/h) ground-transportation developments outside the United States. Both high-speed rail and Maglev systems are covered. Many vehicle systems capable of providing intercity service in the speed range 200--500 km/h are or will soon be available. The current state of various technologies, their implementation, and the near-term plans of countries that are most active in high-speed ground transportation development are reported.

Eastham, T.R. [Queen`s Univ., Kingston, Ontario (United Kingdom)

1995-09-01

157

Ground-state hyperfine measurement in laser-trapped radioactive Â²Â¹Na

We have measured the ground-state hyperfine splitting between the 3Sââ F=2,thinspm=0 and 3Sââ F=1,thinspm=0 levels of Â²Â¹Na. The measurement was performed with microwave spectroscopy on 40000 radioactive Â²Â¹Na atoms (tââ=22 sec) collected in a magneto-optical trap on-line at the 88-in cyclotron at LBNL. The transition was excited with microwaves directed at the atoms and detected with resonant probe fluorescence light.

M. A. Rowe; S. J. Freedman; B. K. Fujikawa; G. Gwinner; S.-Q. Shang; P. A. Vetter

1999-01-01

158

Nonlinear Faraday rotation and detection of superposition states in cold atoms

We report on the observation of nonlinear Faraday rotation with cold atoms at a temperature of {approx}100 {mu}K. The observed nonlinear rotation of the light polarization plane is up to 0.1 rad over the 1-mm-size atomic cloud in approximately 10-mG magnetic field. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman sublevels created by a near-resonant light. The method allows for creation, detection, and control of atomic superposition states. It also allows applications for precision magnetometry with high spatial and temporal resolution.

Wojciechowski, Adam; Zachorowski, Jerzy; Gawlik, Wojciech [Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Krakow (Poland); Joint Krakow-Berkeley Atomic Physics and Photonics Laboratory, Reymonta 4, PL-30-059 Krakow (Poland); Corsini, Eric [Department of Physics, University of California, Berkeley, California 94720-7300 (United States); Joint Krakow-Berkeley Atomic Physics and Photonics Laboratory, Reymonta 4, PL-30-059 Krakow (Poland)

2010-05-15

159

Protocol for Atomic Oxygen Testing of Materials in Ground-Based Facilities. No. 2

NASA Technical Reports Server (NTRS)

A second version of standard guidelines is proposed for improving materials testing in ground-based atomic oxygen environments for the purpose of predicting the durability of the tested materials in low Earth orbit (LEO). Accompanying these guidelines are background information and notes about testing. Both the guidelines and the additional information are intended to aid users who wish to evaluate the potential hazard of atomic oxygen in LEO to a candidate space component without actually flying the component in space, and to provide a framework for more consistent atomic oxygen testing in the future.

Minton, Timothy K.

1995-01-01

160

Reaction mixtures, containing Al atoms and methylethyl ether (MEE) or diethyl ether (DEE) in an adamantane matrix, were prepared with the aid of a metal-atom reactor known as a rotating cryostat. The EPR spectra of the resulting products were recorded from 77-260 K, at 10 K intervals. Al atoms were found to insert into methyl-O, ethyl-O, and C-C bonds to form CH(3)AlOCH(2)CH(3), CH(3)OAlCH(2)CH(3), and CH(3)OCH(2)AlCH(3), respectively, in the case of MEE while DEE produced CH(3)CH(2)AlOCH(2)CH(3) and CH(3)AlCH(2)OCH(2)CH(3), respectively. From the intensity of the transition lines attributed to the Al atom C-O insertion products of MEE, insertion into the methyl-O bond is preferred. The Al hyperfine interaction (hfi) extracted from the EPR spectra of the C-O insertion products was greater than that of the C-C insertion products, that is, 5.4% greater for the DEE system and 7% greater for the MEE system. The increase in Al hfi is thought to arise from the increased electron-withdrawing ability of the substituents bonded to Al. Besides HAlOH, resulting from the reaction of Al atoms with adventitious water, novel mixed HAlOH:MEE and HAlOH:DEE complexes were identified with the aid of isotopic studies involving H(2)(17)O and D(2)O. The Al and H hfi of HAlOH were found to decrease upon complex formation. These findings are consistent with the nuclear hfi calculated using a density functional theory (DFT) method with close agreement between theory and experiment occurring at the B3LYP level using a 6-311+G(2df,p) basis set. PMID:22299675

Brunet, François D; Feola, Julie C; Joly, Helen A

2012-03-15

161

Quantum insulating states of F=2 cold atoms in optical lattices

In this Letter we study various spin correlated insulating states of F=2 cold atoms in optical lattices. We find that the effective spin exchange interaction due to virtual hopping contains an {\\em octopole} coupling between two neighboring lattice sites. Depending on scattering lengths and numbers of particles per site the ground states are either rotationally invariant dimer or trimer Mott insulators or insulating states with various spin orders. Three spin ordered insulating phases are ferromagnetic, cyclic and nematic Mott insulators. We estimate the phase boundaries for states with different numbers of atoms per lattice site.

Fei Zhou; Gordon W. Semenoff

2006-11-09

162

Composition of the ^24O Ground State Wave Function

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical evidence points to a closed shell at N = 16 for the neutron-rich oxygen isotopes based on the measured and predicted excitation energy of the first-excited 2^+ state in ^24O and the energy gap between the ?(0d3/2) and ?(1s1/2) single-particle states. This work seeks to test this assertion by measuring the cross section for neutron knockout from the ^24O ground state to the ground and first-excited states of ^23O (which immediately decays to the ground state of ^22O through neutron emission). From this we can infer the composition of the ^24O ground state wave function. ^24O nuclei were produced at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University via fragmentation of a ^48Ca beam on a 1316 mg/cm^2 Be target, and bombarded a 481 mg/cm^2 Be target downstream to induce knockout reactions. Fragment nuclei (neutron decays) were detected by a system of charged-particle detectors (the Modular Neutron Array (MoNA)). The current status of the analysis will be discussed, including the identification of oxygen fragments, the calibrations for timing and position measurements using MoNA, and the determination of the relevant spectroscopic factors of interest.

Scotten, R. A.; Traynor, E.; Deyoung, P. A.; Islam, N. T.; Haring-Kaye, R. A.

2012-10-01

163

Soliton Atom Laser with Quantum State Transfer Property

We propose a scheme to obtain soliton atom laser with nonclassical atoms based on quantum state transfer process from light to matter waves in nonlinear case, which may find novel applications in, e.g., an atom interferometer. The dynamics of the atomic gray solitons and the accompanied frequency chirp effect are discussed.

Xiong-Jun Liu; Hui Jing; Mo-Lin Ge

2005-10-11

164

Towards new states of matter with atoms and photons

Towards new states of matter with atoms and photons Jonas Larson Stockholm University and UniversitÃ¤t zu KÃ¶ln Aarhus "Cold atoms and beyond" 26/6-2014 #12;Motivation Optical lattices + control QED = coupling between few material (atomic) and few electromagnetic degrees of freedom. Cavity atom

165

Probing Quantum Frustrated Systems via Factorization of the Ground State

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.

Salvatore M. Giampaolo; Gerardo Adesso; Fabrizio Illuminati

2010-05-20

166

Probing quantum frustrated systems via factorization of the ground state.

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. PMID:20867055

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

2010-05-21

167

Ground state alignment as a tracer of interplanetary magnetic field

NASA Astrophysics Data System (ADS)

We demonstrate a new way of studying interplanetary magnetic field -- spectropolarimetry based on ground state alignment. Ground state alignment is a new promising way of sub-gausian magnetic fields in radiation-dominated environment. The polarization of spectral lines that are pumped by the anisotropic radiation from the sun is influenced by the magnetic alignment, which happens for sub-gausian magnetic field. As a result, the linear polarization becomes an excellent tracer of the embedded magnetic field. The method is illustrated by our synthetic obser- vation of the Jupiter's Io and comet Halley. A uniform density distribution of Na was considered and polar- ization at each point was then constructed. Both spa- tial and temporal variations of turbulent magnetic field can be traced with this technique as well. Instead of sending thousands of space probes, ground state alignment allows magnetic mapping with any ground telescope facilities equipped with spectrometer and polarimeter. For remote regions like the the boundary of interstellar medium, ground state alignment provides a unique diagnostics of magnetic field, which is crucial for understanding the physical processes such as the IBEX ribbons.

Yan, H.

2012-12-01

168

The authors construct atomic models of molecular boron, carbon and nitrogen in order to study the thermodynamic activity and ground state configuration as well as transitions between ground and vibrational states, configuration interactions, electron density, spin, hyperfine splitting behavior, and other electronic and quantum properties of the molecules.

Beznosyuk, S.A.; Minaev, B.F.; Kul'zhanov, A.T.; Muldakhmetov, Z.M.

1987-07-01

169

Light pulse analysis with a multi-state atom interferometer

NASA Astrophysics Data System (ADS)

We present a controllable multi-state cold-atom interferometer that is easy-to-use and fully merged on an atom chip. We demonstrate its applications as a sensor of the fields whose interactions with atoms are state-dependent.

Herrera, I.; Petrovic, J.; Lombardi, P.; Schäfer, F.; Cataliotti, F. S.

2014-12-01

170

Ground state entanglement constrains low-energy excitations

For a general quantum many-body system, we show that its ground state entanglement imposes a fundamental constraint on the low-energy excitations. For two-dimensional systems, our result implies that any system that supports anyons must have a nonvanishing topological entanglement entropy. We demonstrate the generality of this argument by applying it to three-dimensional quantum many-body systems, and showing that there is a pair of ground state topological invariants that are associated to their physical boundaries. From the pair, one can determine whether the given boundary can or cannot absorb point-like or line-like excitations.

Isaac H. Kim; Benjamin J. Brown

2014-10-27

171

From local to global ground states in Ising spin glasses

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

172

Is Schrödinger's Conjecture for the Hydrogen Atom Coherent States Attainable

We construct the most general SO(4,2) hydrogen atom coherent states which are the counterpart of Schr\\"{o}dinger's harmonic oscillator coherent states. We show that these states cannot be localized and cannot follow the classical orbits. Thus, Schr\\"{o}dinger's conjecture for the hydrogen atom coherent states is unattainable.

Ivaylo Zlatev; Wei-Min Zhang; Da Hsuan Feng

1993-11-08

173

Entanglement reciprocation between atomic qubits and entangled coherent state

Introducing classical fields, we can transfer entanglement completely from discrete qubits into entangled coherent state. The entanglement also can be retrieved from the continuous-variable state of the cavities to the atomic qubits. Via postselection measure, atomic entangled state and entangled coherent state can be mutual transformed fully.

Ling Zhou; Guo-Hui Yang

2006-10-26

174

Generating atomic multi-dimensional entangled states under large atom-cavity detuning

We propose a scheme to deterministically generate atomic two-dimensional and three-dimensional entangled states by passing two 87Rb atoms through a high-Q bi-mode cavity alternately. The scheme is insensitive to atomic spontaneous decay because of large atom-cavity detuning, the influence of cavity decay is also discussed. Our strictly numerical simulation shows our proposal is good enough to demonstrate the generation of atomic entanglement with high fidelity and within the current experimental technologies.

Peng Shi; Li-Bo Chen; Wen-Dong Li; Chun-Nian Ren; Chun-Hong Zheng; Yong-Jian Gu

2012-09-25

175

We propose and investigate a hybrid optomechanical system consisting of a micro-mechanical oscillator coupled to the internal states of a distant ensemble of atoms. The interaction between the systems is mediated by a light field which allows to couple the two systems in a modular way over long distances. Coupling to internal degrees of freedom of atoms opens up the possibility to employ high-frequency mechanical resonators in the MHz to GHz regime, such as optomechanical crystal structures, and to benefit from the rich toolbox of quantum control over internal atomic states. Previous schemes involving atomic motional states are rather limited in both of these aspects. We derive a full quantum model for the effective coupling including the main sources of decoherence. As an application we show that sympathetic ground-state cooling and strong coupling between the two systems is possible.

B. Vogell; T. Kampschulte; M. T. Rakher; A. Faber; P. Treutlein; K. Hammerer; P. Zoller

2014-12-16

176

Dimerized ground states in spin-S frustrated systems

We study a family of frustrated anti-ferromagnetic spin-$S$ systems with a fully dimerized ground state. This state can be exactly obtained without the need to include any additional three-body interaction in the model. The simplest members of the family can be used as a building block to generate more complex geometries like spin tubes with a fully dimerized ground state. After present some numerical results about the phase diagram of these systems, we show that the ground state is robust against the inclusion of weak disorder in the couplings as well as several kinds of perturbations, allowing to study some other interesting models as a perturbative expansion of the exact one. A discussion on how to determine the dimerization region in terms of quantum information estimators is also presented. Finally, we explore the relation of these results with a the case of the a 4-leg spin tube which recently was proposed as the model for the description of the compound Cu$_2$Cl$_4$D$_8$C$_4$SO$_2$, delimiting the region of the parameter space where this model presents dimerization in its ground state.

C. A. Lamas; J. M. Matera

2015-01-25

177

Antiferromagnetic ground state with pair-checkerboard order in FeSe

NASA Astrophysics Data System (ADS)

A monolayer FeSe thin film grown on SrTiO3(001) (STO) shows the sign of Tc>77 K , which is higher than the Tc record of 56 K for bulk FeAs-based superconductors. However, little is known about the magnetic ground state of FeSe, which should be closely related to its unusual superconductivity. Previous studies presume the collinear stripe antiferromagnetic (AFM) state as the ground state of FeSe, the same as that in FeAs superconductors. Here we find a magnetic order named the "pair-checkerboard AFM" as the magnetic ground state of tetragonal FeSe. The pair-checkerboard order results from the interplay between the nearest-, next-nearest, and unnegligible next-next-nearest neighbor magnetic exchange couplings of Fe atoms. The monolayer FeSe in pair-checkerboard order shows an unexpected insulating behavior with a Dirac-cone-like band structure related to the specific orbital order of the dx z and dy z characters of Fe atoms, which could explain the recently observed insulator-superconductor transition. The present results cast insights on the magnetic ordering in FeSe monolayer and its derived superconductors.

Cao, Hai-Yuan; Chen, Shiyou; Xiang, Hongjun; Gong, Xin-Gao

2015-01-01

178

NASA Astrophysics Data System (ADS)

We investigate the ground-state of a new Kondo lattice model, where the free carriers interact repulsively between them and undergo an external superlattice potential. This model can be simulated with 171Yb atoms confined in optical lattices. We use the density matrix renormalization group method to evaluate the charge and spin gaps, and the structure factors. We found that the ground-state evolves from a Kondo spin liquid state to a charge-gapped antiferromagnetic state with zero spin gap, when the antiferromagnetic exchange increases. Also, we verify that the quantum critical point varies linearly with the repulsion and the exchange.

Silva-Valencia, J.; Franco, R.; Figueira, M. S.

2014-04-01

179

Ground states of a mixture of two species of spinor Bose gases with interspecies spin exchange

We consider a mixture of two species of spin-1 atoms with interspecies spin exchange, which may cooperate or compete with intraspecies spin exchanges and thus dramatically affect the ground state. It represents a new class of bosonic gases differing from single-species spinor gases. We determine the exact ground states in several parameter regimes and study the composite structures using the generating function method generalized here to be applicable to a mixture of two species of spinor gases. The most interesting phase is the so-called entangled Bose-Einstein condensation (BEC), which is fragmented BEC with quantum entanglement between the two species and with both interspecies and intraspecies singlet pairs. For comparison, we also apply the generating function method to a mixture of two species of pseudospin-(1/2) atoms, for which the total spin quantum number of each species is fixed as half of the atom number, in contrast with the case of spin 1, for which it is a variable determined by energetics. Consequently, singlet pairs in entangled BEC of a pseudospin-(1/2) mixture are all interspecies. Interspecies spin exchange leads to novel features beyond those of spinor BEC of a single species of atoms as well as mixtures without interspecies spin exchange.

Shi Yu [Department of Physics, Fudan University, Shanghai 200433 (China)

2010-08-15

180

NASA Astrophysics Data System (ADS)

Absolute line intensity measurements are performed on a metal-halide lamp. Several transitions of atomic and ionic Dy and atomic Hg are measured at different radial positions from which we obtain absolute atomic and ionic Dy intensity profiles. From these profiles we construct the radially resolved atomic state distribution function (ASDF) of the atomic and ionic Dy and the atomic Hg. From these ASDFs several quantities are determined as functions of radial position, such as the (excitation) temperature, the ion ratio Hg+/Dy+, the electron density, the ground state, and the total density of Dy atoms and ions. Moreover, these ASDFs give us insight about the departure from equilibrium. The measurements show a hollow density profile for the atoms and the ionization of atoms in the center. In the outer parts of the lamp molecules dominate.

Nimalasuriya, T.; Flikweert, A. J.; Stoffels, W. W.; Haverlag, M.; van der Mullen, J. J. A. M.; Pupat, N. B. M.

2006-03-01

181

? -Decay near the shell closure from ground and isomeric states

NASA Astrophysics Data System (ADS)

The modified two-potential approach (MTPA) is employed to study the exotic ?-decay near the closed shells Z=82 and N=82, 126 within a deformed version of the cluster model. We perform systematic calculations on favored ?-decay half-lives from both the ground states (g.s.) and the isomeric states (i.s.) by using the microscopic double-folding potential. The obtained ?-decay half-lives are found to be in good agreement with the experimental data. This indicates that four types of ? transitions among ground states and isomeric states (g.s. ? g.s., g.s. ? i.s., i.s. ? g.s., i.s. ? i.s.) are well described in a unified model. In addition, the unfavored ? transitions in the Bi isotopes are investigated to pursue a further understanding of ?-decay properties.

Qian, Yibin; Ren, Zhongzhou; Ni, Dongdong

2011-09-01

182

Fractional quantum numbers deduced from experimental ground state meson spectra

Based on the Caputo definition of the fractional derivative the ground state spectra of mesons are classified as multiplets of the fractional rotation group. The comparison with the experimental values leads to the conclusion, that quarks carry an up to now unrevealed fractional multiplicative quantum number, which we call fractional hyper charge.

Richard Herrmann

2010-03-26

183

Ground state of isotopic fermion-boson mixtures

An investigation of the ground-state configuration of isotopic fermion-boson mixtures is reported for both two and three dimensions. A detailed numerical study of systems interacting with Lennard-Jones-type potentials is presented, enabling one to interpert these results in terms of a picture of the fermion-boson mixture as being built up from an \\

R. A. Guyer; M. D. Miller

1980-01-01

184

A Constrained Path Monte Carlo Method for Fermion Ground States

We describe and discuss a recently proposed quantum Monte Carlo algorithm to compute the ground-state properties of various systems of interacting fermions. In this method, the ground state is projected from an initial wave function by a branching random walk in an over-complete basis of Slater determinants. By constraining the determinants according to a trial wave function $|\\psi_T\\rangle$, we remove the exponential decay of signal-to-noise ratio characteristic of the sign problem. The method is variational and is exact if $|\\psi_T\\rangle$ is exact. We illustrate the method by describing in detail its implementation for the two-dimensional one-band Hubbard model. We show results for lattice sizes up to $16\\times 16$ and for various electron fillings and interaction strengths. Besides highly accurate estimates of the ground-state energy, we find that the method also yields reliable estimates of other ground-state observables, such as superconducting pairing correlation functions. We conclude by discussing possible extensions of the algorithm.

Shiwei Zhang; J. Carlson; J. E. Gubernatis

1996-07-09

185

Parametric resonance of ground states in the nonlinear Schrodinger equation

. It is expected however that when the #3; DISMI, University of Modena and Reggio Emilia, Italy y Department, we show under some non-degeneracy assumptions that the solution approaches the pro#12;le, 14], when the solution u(t; x) was shown to approach to a periodically modulated ground state

186

Ground Control to Niels Bohr: Exploring Outer Space with Atomic Physics

We provided an introduction to transition state theory and the connections it provides between atomic and celestial physics. We include brief discussions of historical background, recent applications in space mission design, and current research efforts.

Mason A. Porter; Predrag Cvitanovic

2005-05-11

187

Classical limit states of the helium atom

The classical simplicity and intuitive appeal of Bohr's atomic model have given the classical hydrogen atom an important and pervasive role in atomic physics. Even today, the Bohr model remains as a cornerstone underlying quan- tum mechanics. However, the precise role of this classical foundation has been debated since the early days of quantum theory. Recently, a series of experimental

J. A. West; Z. D. Gaeta; C. R. Stroud

1998-01-01

188

Rydberg States of Atoms and Molecules

NASA Astrophysics Data System (ADS)

List of contributors; Preface; 1. Rydberg atoms in astrophysics A. Dalgarno; 2. Theoretical studies of hydrogen Rydberg atoms in electric fields R. J. Damburg and V. V. Kolosov; 3. Rydberg atoms in strong fields D. Kleppner, Michael G. Littman and Myron L. Zimmerman; 4. Spectroscopy of one- and two-electron Rydberg atoms C. Fabre and S. Haroche; 5. Interaction of Rydberg atoms with blackbody radiation T. F. Gallagher; 6. Theoretical approaches to low-energy collisions of Rydberg atoms with atoms and ions A. P. Hickman, R. E. Olson and J. Pascale; 7. Experimental studies of the interaction of Rydberg atoms with atomic species at thermal energies F. Gounand and J. Berlande; 8. Theoretical studies of collisions of Rydberg atoms with molecules Michio Matsuzawa; 9. Experimental studies of thermal-energy collisions of Rydberg atoms with molecules F. B. Dunning and R. F. Stebbings; 10. High-Rydberg molecules Robert S. Freund; 11. Theory of Rydberg collisions with electrons, ions and neutrals M. R. Flannery; 12. Experimental studies of the interactions of Rydberg atoms with charged particles J. -F. Delpech; 13. Rydberg studies using fast beams Peter M. Koch; Index.

Stebbings, R. F.; Dunning, F. B.

2011-03-01

189

Nanog is the gateway to the pluripotent ground state.

Pluripotency is generated naturally during mammalian development through formation of the epiblast, founder tissue of the embryo proper. Pluripotency can be recreated by somatic cell reprogramming. Here we present evidence that the homeodomain protein Nanog mediates acquisition of both embryonic and induced pluripotency. Production of pluripotent hybrids by cell fusion is promoted by and dependent on Nanog. In transcription factor-induced molecular reprogramming, Nanog is initially dispensable but becomes essential for dedifferentiated intermediates to transit to ground state pluripotency. In the embryo, Nanog specifically demarcates the nascent epiblast, coincident with the domain of X chromosome reprogramming. Without Nanog, pluripotency does not develop, and the inner cell mass is trapped in a pre-pluripotent, indeterminate state that is ultimately nonviable. These findings suggest that Nanog choreographs synthesis of the naive epiblast ground state in the embryo and that this function is recapitulated in the culmination of somatic cell reprogramming. PMID:19703398

Silva, Jose; Nichols, Jennifer; Theunissen, Thorold W; Guo, Ge; van Oosten, Anouk L; Barrandon, Ornella; Wray, Jason; Yamanaka, Shinya; Chambers, Ian; Smith, Austin

2009-08-21

190

Magnetic behavior of curium dioxide with a nonmagnetic ground state

NASA Astrophysics Data System (ADS)

In order to understand magnetic behavior observed in CmO2 with a nonmagnetic ground state, we numerically evaluate magnetic susceptibility on the basis of a seven-orbital Anderson model with spin-orbit coupling. Naively we do not expect magnetic behavior in CmO2, since Cm is considered to be a tetravalent ion with six 5f electrons and the ground state is characterized by J=0, where J is total angular momentum. However, there exists a magnetic excited state and the excitation energy is smaller than the value of the Landé interval rule due to the effect of crystalline electric-field potential. Then, we open a way to explain magnetic behavior in CmO2.

Niikura, Fumiaki; Hotta, Takashi

2011-05-01

191

Fock-state view of weak-value measurements and implementation with photons and atomic ensembles

Weak measurements in combination with postselection can give rise to a striking amplification effect (related to a large ''weak value''). We show that this effect can be understood by viewing the initial state of the pointer as the ground state of a fictional harmonic oscillator. This perspective clarifies the relationship between the weak-value regime and other measurement techniques and inspires a proposal to implement fully quantum weak-value measurements combining photons and atomic ensembles.

Simon, Christoph [Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, T2N 1N4 (Canada); Polzik, Eugene S. [Niels Bohr Institute, Danish Quantum Optics Center QUANTOP, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen O (Denmark)

2011-04-15

192

NASA Astrophysics Data System (ADS)

We present a detailed analysis of our recent observation of synchronous Rabi oscillations between the electronic ground state and Rydberg states in a mesoscopic ensemble containing roughly 100 ultracold atoms (Reetz-Lamour et al submitted, Preprint 0711.4321). The mesoscopic cloud is selected out of a sample of laser-cooled Rb atoms by optical pumping. The atoms are coupled to a Rydberg state with principal quantum number around 30 by a two-photon scheme employing flat-top laser beams. The influence of residual spatial intensity fluctuations as well as sources of decoherence such as redistribution to other states, radiative lifetime and laser bandwidth are analysed. The results open up new possibilities for the investigation of coherent many-body phenomena in dipolar Rydberg gases. As an example we demonstrate the van der Waals blockade, a variant of the dipole blockade, for a mesoscopic atom sample.

Reetz-Lamour, M.; Deiglmayr, J.; Amthor, T.; Weidemüller, M.

2008-04-01

193

We consider a bosonic Josephson junction made of N ultracold and dilute atoms confined by a quasi-one-dimensional double-well potential within the two-site Bose-Hubbard model framework. The behavior of the system is investigated at zero temperature by varying the interatomic interaction from the strongly attractive regime to the repulsive one. We show that the ground state exhibits a crossover from a macroscopic Schroedinger-cat state to a separable Fock state through an atomic coherent regime. By diagonalizing the Bose-Hubbard Hamiltonian we characterize the emergence of the macroscopic cat states by calculating the Fisher information F, the coherence by means of the visibility {alpha} of the interference fringes in the momentum distribution, and the quantum correlations by using the entanglement entropy S. Both Fisher information and visibility are shown to be related to the ground-state energy by employing the Hellmann-Feynman theorem. This result, together with a perturbative calculation of the ground-state energy, allows simple analytical formulas for F and {alpha} to be obtained over a range of interactions, in excellent agreement with the exact diagonalization of the Bose-Hubbard Hamiltonian. In the attractive regime the entanglement entropy attains values very close to its upper limit for a specific interaction strength lying in the region where coherence is lost and self-trapping sets in.

Mazzarella, G.; Toigo, F. [Dipartimento di Fisica 'Galileo Galilei' and Consorzio Nazionale Interuniversitario per la Scienze Fisiche della Materia (CNISM), Universita di Padova, Via Marzolo 8, I-35122 Padova (Italy); Salasnich, L. [Dipartimento di Fisica 'Galileo Galilei' and Consorzio Nazionale Interuniversitario per la Scienze Fisiche della Materia (CNISM), Universita di Padova, Via Marzolo 8, I-35122 Padova (Italy); Istituto Nazionale di Ottica (INO) del Consiglio Nazionale delle Ricerche (CNR), via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Parola, A. [Dipartimento di Fisica e Matematica and CNISM, Universita dell'Insubria, Via Valleggio 11, I-22100 Como (Italy)

2011-05-15

194

Ground states of helium to neon and their ions in strong magnetic fields

NASA Astrophysics Data System (ADS)

We use the combination of a two-dimensional Hartree-Fock and a diffusion quantum Monte Carlo method, both of which we recently presented in this journal [C. Schimeczek et al., Phys. Rev. A 88, 012509 (2013), 10.1103/PhysRevA.88.012509], for a thorough investigation of the ground state configurations of all atoms and ions with Z =2-10 with the exception of hydrogen-like systems in strong magnetic fields. We obtain the most comprehensive data set of ground state configurations as a function of the magnetic field strength currently available and hence are able to analyze and compare the properties of systems with different core charges and electron numbers in detail.

Boblest, Sebastian; Schimeczek, Christoph; Wunner, Günter

2014-01-01

195

Creation of ultracold ^{87}rb^{133}cs molecules in the rovibrational ground state.

We report the creation of a sample of over 1000 ultracold ^{87}Rb^{133}Cs molecules in the lowest rovibrational ground state, from an atomic mixture of ^{87}Rb and ^{133}Cs, by magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). We measure the binding energy of the RbCs molecule to be hc×3811.576(1)??cm^{-1} and the |v^{''}=0,J^{''}=0? to |v^{''}=0,J^{''}=2? splitting to be h×2940.09(6)??MHz. Stark spectroscopy of the rovibrational ground state yields an electric dipole moment of 1.225(3)(8) D, where the values in parentheses are the statistical and systematic uncertainties, respectively. We can access a space-fixed dipole moment of 0.355(2)(4) D, which is substantially higher than in previous work. PMID:25554891

Molony, Peter K; Gregory, Philip D; Ji, Zhonghua; Lu, Bo; Köppinger, Michael P; Le Sueur, C Ruth; Blackley, Caroline L; Hutson, Jeremy M; Cornish, Simon L

2014-12-19

196

Ground states and doubly excited resonance states of H- embedded in dense quantum plasmas

We have made an investigation on the ground states and the 2s21Se resonance states of H- in dense quantum plasmas. Exponential-cosine-screened Coulomb potentials (ECSCP) are used to represent the effective potential for a test charge in dense quantum plasmas. Ground-state energies and wavefunctions are determined within the framework of Ritz's variational principle by employing highly correlated wavefunctions to take into

Arijit Ghoshal; Y. K. Ho

2009-01-01

197

Incommensurate helical spin ground states on the hollandite lattice

NASA Astrophysics Data System (ADS)

We present a model of classical Heisenberg spins on a hollandite lattice, which has been developed to describe the magnetic properties of ?-MnO2 and similar compounds. The model has only nearest-neighbor interacting spins, however, the strength and the sign of spin-spin interactions is anisotropic and depends on the nature of the bonds. Our analysis shows that the hollandite lattice supports four different incommensurate and helical magnetic ground states depending on the relative strengths and signs of spin-spin interactions. We show that the incommensurate helical ground states appear due to the geometrical frustration present in the model. We demonstrate that each of the four helical incommensurate magnetic phases are continuously connected to four different collinear antiferromagnetic ground states as the strength of spin-spin interaction along some bonds is increased. The present results give support to the presence of helical states that have been previously suggested experimentally for hollandite compounds. We provide an in-depth analysis of the magnetic form factors for each helical phase and describe how it could be used to identify each of these phases in neutron diffraction experiments.

Mandal, S.; Andreanov, A.; Crespo, Y.; Seriani, N.

2014-09-01

198

Guidelines for ground motion definition for the eastern United States

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.

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

1985-06-01

199

The ground-state structure and physical properties of RuC: first-principles calculations

NASA Astrophysics Data System (ADS)

We have extensively explored the ground-state structure of RuC using the particle swarm optimization algorithm for crystal structural prediction. A hexagonal R-3m structure has been proposed as the best candidate, which is energetically more favorable than the previously proposed zinc blend structure. The R-3m-RuC possesses alternative stacking of double hexagonal close-packed Ru atom layers and C atom layers, and it is dynamically stable evidenced by the calculation of phonon dispersion. The calculated large bulk modulus, shear modulus, and elastic constant C44 reveal that it is an ultra-incompressible and hard material. The evidence of strong covalent bonding of Ru—C, which plays an important role to form a hard material, is manifested by the partial densities of states analysis.

Zhang, Mei-Guang; Yan, Hai-Yan; Zhang, Gang-Tai; Wang, Hui

2012-07-01

200

Highly polar states of Rydberg atoms in strong magnetic and weak electric fields

NASA Astrophysics Data System (ADS)

We study the spectra of diamagnetic rubidium Rydberg atoms in strong magnetic and weak electric parallel fields, in the n-mixing regime. Our emphasis is on isolated pairs of near-degenerate, opposite-parity, diamagnetic states that become mixed by the weak electric field. Such level pairs allow for the generation of nondegenerate states with large, tunable permanent electric dipole moments and large optical excitation cross sections from the atomic ground state. We investigate how the dipole moments and the zero-electric-field energy defects of these level pairs can be tuned using small variations of the electric and magnetic fields. Using calculations, we explore the abundance of such level pairs over wide spectral regions for several magnetic quantum numbers. Applications of polar, diamagnetic Rydberg states in Rydberg-atom interaction experiments are briefly discussed.

Paradis, E.; Zigo, S.; Raithel, G.

2013-01-01

201

Lamb Shift of Laser-Dressed Atomic States

We discuss radiative corrections to an atomic two-level system subject to an intense driving laser field. It is shown that the Lamb shift of the laser-dressed states, which are the natural state basis of the combined atom-laser system, cannot be explained in terms of the Lamb shift received by the atomic bare states which is usually observed in spectroscopic experiments. In the final part, we propose an experimental scheme to measure these corrections based on the incoherent resonance fluorescence spectrum of the driven atom.

U. D. Jentschura; J. Evers; M. Haas; C. H. Keitel

2003-07-07

202

Ground-state properties of a supersymmetric fermion chain

NASA Astrophysics Data System (ADS)

We analyze the ground state of a strongly interacting fermion chain with a supersymmetry. We conjecture a number of exact results, such as a hidden duality between weak and strong couplings. By exploiting a scale-free property of the perturbative expansions, we find exact expressions for the order parameters, yielding the critical exponents. We show that the ground state of this fermion chain and another model in the same universality class, the XYZ chain along a line of couplings, are both written in terms of the same polynomials. We demonstrate this explicitly for up to N = 24 sites and provide consistency checks for large N. These polynomials satisfy a recursion relation related to the Painlevé VI differential equation and, using a scale-free property of these polynomials, we derive a simple and exact formula for their N\\to \\infty limit.

Fendley, Paul; Hagendorf, Christian

2011-02-01

203

First evidence for a virtual 18B ground state

NASA Astrophysics Data System (ADS)

The decay of the neutron unbound ground state of 18B was studied for the first time through a single-proton knockout reaction from a 62 MeV/u 19C beam. The decay energy spectrum was reconstructed from coincidence measurements between the emitted neutron and the 17B fragment using the MoNA/Sweeper setup. An s-wave line shape was used to describe the experimental spectrum resulting in an upper limit for the scattering length of - 50 fm which corresponds to a decay energy <10 keV. Observing an s-wave decay of 18B provides an experimental verification that the ground state of 19C includes a large s-wave component. The presence of this s-wave component shows that s-d mixing is still present in 18B and that the s1 / 2 orbital has not moved significantly below the d5 / 2 orbital.

Spyrou, A.; Baumann, T.; Bazin, D.; Blanchon, G.; Bonaccorso, A.; Breitbach, E.; Brown, J.; Christian, G.; DeLine, A.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Mosby, S.; Peters, W. A.; Russel, A.; Schiller, A.; Strongman, M. J.; Thoennessen, M.

2010-01-01

204

First observation of the 13Li ground state

NASA Astrophysics Data System (ADS)

The ground state of neutron-rich unbound 13Li was observed for the first time in a one-proton removal reaction from 14Be at a beam energy of 53.6 MeV/u. The 13Li ground state was reconstructed from 11Li and two neutrons giving a resonance energy of 120-80+60 keV. All events involving single- and double-neutron interactions in the Modular Neutron Array (MoNA) were analyzed, simulated, and fitted self-consistently. The three-body (11Li+n+n) correlations within Jacobi coordinates showed strong dineutron characteristics. The decay energy spectrum of the intermediate 12Li system (11Li+n) was described with an s-wave scattering length of greater than -4 fm, which is a smaller absolute value than reported in a previous measurement.

Kohley, Z.; Lunderberg, E.; DeYoung, P. A.; Volya, A.; Baumann, T.; Bazin, D.; Christian, G.; Cooper, N. L.; Frank, N.; Gade, A.; Hall, C.; Hinnefeld, J.; Luther, B.; Mosby, S.; Peters, W. A.; Smith, J. K.; Snyder, J.; Spyrou, A.; Thoennessen, M.

2013-01-01

205

How to make the ?0?2 singlet the ground state of carbenes.

Successful strategies have previously been developed to stabilize the ?(2)?(0) singlet states of carbenes, relative to ?(1)?(1) triplet states. However, little or no attention has been paid to the stabilization of the ?(0)?(2) singlet states. We present two simple strategies to stabilize the ?(0)?(2) singlet states of carbenes, relative to both the ?(2)?(0) singlet and ?(1)?(1) triplet states. These strategies consist of destabilization of the carbene ? orbital by two, adjacent, sp(2) nitrogen lone pairs of electrons and stabilization of the carbene 2p-? orbital by incorporating it into a five-membered ring, containing two double bonds, or into a six-membered ring, containing two double bonds and a sixth atom that has a low-lying empty ? orbital. B3LYP, CASPT2, and CCSD(T) calculations have been performed in order to assess the success of these strategies in creating derivatives of cyclopenta-2,4-dienylidene and cyclohexa-2,5-dienylidene with ?(0)?(6) singlet ground states. Differences between the calculated geometries and binding energies of the Xe complexes of the ?(0)?(6) singlet ground state of 2,5-diazacyclopentadienylidene (5) and the ?(2)?(0) singlet states of CH2 and CF2 are discussed. PMID:24007553

Chen, Bo; Rogachev, Andrey Yu; Hrovat, David A; Hoffmann, Roald; Borden, Weston Thatcher

2013-09-18

206

Ground state solutions of asymptotically linear fractional Schrödinger equations

NASA Astrophysics Data System (ADS)

This paper is devoted to a time-independent fractional Schrödinger equation of the form (-? )^s u+V(x)u=f(x,u) in {R}N, where N ? 2, s ? (0, 1), (-?)s stands for the fractional Laplacian. We apply the variational methods to obtain the existence of ground state solutions when f(x, u) is asymptotically linear with respect to u at infinity.

Chang, Xiaojun

2013-06-01

207

Ground-state energy and relativistic corrections for positronium hydride

Variational calculations of the ground state of positronium hydride (HPs) are reported, including various expectation values, electron-positron annihilation rates, and leading relativistic corrections to the total and dissociation energies. The calculations have been performed using a basis set of 4000 thoroughly optimized explicitly correlated Gaussian basis functions. The relative accuracy of the variational energy upper bound is estimated to be of the order of 2x10{sup -10}, which is a significant improvement over previous nonrelativistic results.

Bubin, Sergiy; Varga, Kalman [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2011-07-15

208

Ground-state electronic destabilization via hyperconjugation in aspartate aminotransferase.

Binding isotope effects for l-aspartate reacting with the inactive K258A mutant of PLP-dependent aspartate aminotransferase to give a stable external aldimine intermediate are reported. They provide direct evidence for electronic ground-state destabilization via hyperconjugation. The smaller equilibrium isotope effect with deazaPLP-reconstituted K258A indicates that the pyridine nitrogen plays an important role in labilizing the C?-H bond. PMID:22551424

Griswold, Wait R; Castro, Joan Nieto; Fisher, Andrew J; Toney, Michael D

2012-05-23

209

Ground State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase

Binding isotope effects for L-aspartate reacting with the inactive K258A mutant of PLP-dependent aspartate aminotransferase to give a stable external aldimine intermediate are reported. They provide direct evidence for electronic ground state destabilization via hyperconjugation. The smaller equilibrium isotope effect with deazaPLP-reconstituted K258A indicates that the pyridine nitrogen plays an important role in labilizing the C?-H bond. PMID:22551424

Griswold, Wait R.; Castro, Joan Nieto; Fisher, Andrew J.; Toney, Michael D.

2012-01-01

210

Experimental Investigation of Excited-State Lifetimes in Atomic Ytterbium

Lifetimes of 21 excited states in atomic Yb were measured using time-resolved fluorescence detection following pulsed laser excitation. The lifetime of the 4f{sup 14}5d6s {sup 3}D{sub 1} state, which is of particular importance for a proposed study of parity nonconservation in atoms, was measured to be 380(30) ns.

Bowers, C.J.; Budker, D.; Commins, E.D.; DeMille, D.; Freedman, S.J.; Nguyen, A.-T.; Shang, S.-Q.; /UC, Berkeley; Zolotorev, M.; /SLAC

2011-11-15

211

Ground states of fermionic lattice Hamiltonians with permutation symmetry

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

212

Additional symmetry for the electronic shell in its ground state and many-electron effects

: The additional symmetry for the properties related to the ground state of the atom is considered taking into account many-electron\\u000a effects. Calculations of the I\\u000a 4f, I\\u000a 3d,I\\u000a 2p,I\\u000a 3p binding energies, 4f\\u000a N-15d - 4fN system differences and 2p, 3p electron affinities in the second order of perturbation theory and in the configuration interaction approximation have been\\u000a performed

P. Bogdanovich; A. Kyniene; R. Karazija; R. Karpuskiene; G. Gaigalas

2000-01-01

213

Ground state of naphthyl cation: Singlet or triplet?

We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (?,?) type, whereas in 2-naphthyl cation it is (?,?{sup ?}) type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz.

Dutta, Achintya Kumar; Vaval, Nayana, E-mail: np.vaval@ncl.res.in; Pal, Sourav, E-mail: s.pal@ncl.res.in [Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008 (India)] [Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008 (India); Manohar, Prashant U. [Department of Chemistry, BITS Pilani, Pilani Campus (India)] [Department of Chemistry, BITS Pilani, Pilani Campus (India)

2014-03-21

214

Ground state of naphthyl cation: singlet or triplet?

We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (?,?) type, whereas in 2-naphthyl cation it is (?,?') type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz. PMID:24655185

Dutta, Achintya Kumar; Manohar, Prashant U; Vaval, Nayana; Pal, Sourav

2014-03-21

215

Tuning of the ground state in electron doped anthracene.

High quality bulk samples of anthracene (AN) doped with potassium (K) in 1?:?1 and 2?:?1 stoichiometries were successfully prepared by a method involving a room temperature solid-state mechanical diffusion process prior to intercalation reactions during heat treatment, and their physical properties were studied using both magnetic and optical measurements. The transfer of almost one electron from K to AN in K1(AN) was confirmed by SQUID and ESR measurements. A pronounced magnetic hump centered at 150 K associated with antiferromagnetic interactions was observed, which can most likely be interpreted in terms of on-site Coulomb repulsions of the Mott insulating states. Optical spectra of K1(AN) clearly showed the insulating states, as well as the electron occupation of the LUMO-derived band of AN. Our results demonstrated tuning of the ground state of a typical bulk hydrocarbon by alkali metal intercalation. PMID:24867585

Phan, Quynh T N; Heguri, Satoshi; Tanabe, Yoichi; Shimotani, Hidekazu; Nakano, Takehito; Nozue, Yasuo; Tanigaki, Katsumi

2014-07-14

216

Study of interplanetary magnetic field with Ground State Alignment

NASA Astrophysics Data System (ADS)

We demonstrate a new way of studying interplanetary magnetic field—Ground State Alignment (GSA). Instead of sending thousands of space probes, GSA allows magnetic mapping with any ground telescope facilities equipped with spectropolarimeter. The polarization of spectral lines that are pumped by the anisotropic radiation from the Sun is influenced by the magnetic realignment, which happens for magnetic field (<1 G). As a result, the linear polarization becomes an excellent tracer of the embedded magnetic field. The method is illustrated by our synthetic observations of the Jupiter's Io and comet Halley. Polarization at each point was constructed according to the local magnetic field detected by spacecrafts. Both spatial and temporal variations of turbulent magnetic field can be traced with this technique as well. The influence of magnetic field on the polarization of scattered light is discussed in detail. For remote regions like the IBEX ribbons discovered at the boundary of interstellar medium, GSA provides a unique diagnostics of magnetic field.

Shangguan, Jinyi; Yan, Huirong

2013-01-01

217

Coulomb breakup of $^{37}$Mg and its ground state structure

We calculate Coulomb breakup of the neutron rich nucleus $^{37}$Mg on a Pb target at the beam energy of 244 MeV/nucleon within the framework of a finite range distorted wave Born approximation theory that is extended to include the effects of projectile deformation. In this theory, the breakup amplitude involves the full wave function of the projectile ground state. Calculations have been carried out for the total one-neutron removal cross section $(\\sigma_{-1n})$, the neutron-core relative energy spectrum, the parallel momentum distribution of the core fragment, the valence neutron angular, and energy-angular distributions. The calculated $\\sigma_{-1n}$ has been compared with the recently measured data to put constraints on the spin parity, and the one-neutron separation energy ($S_{-1n}$) of the $^{37}$Mg ground state ($^{37}$Mg$_{gs}$). The dependence of $\\sigma_{-1n}$ on the deformation of this state has also been investigated. Our study suggests that $^{37}$Mg$_{gs}$ is most likely to have a spin parity assignment of $3/2^-$. Using the shell model value for the spectroscopic factor for this configuration and without considering the projectile deformation effects, a $S_{-1n}$ of $0.10 \\pm 0.02$ MeV is extracted. Inclusion of the deformation effects increases the value of the deduced $S_{-1n}$. The narrow parallel momentum distribution of the core fragment and the strong forward peaking of the valence neutron angular distribution suggest a one-neutron halo configuration in the $2p_{3/2}$ ground state of $^{37}$Mg.

Shubhchintak; Neelam; R. Chatterjee; R. Shyam; K. Tsushima

2015-01-15

218

Earthquake Ground Motion Simulations in the Central United States

NASA Astrophysics Data System (ADS)

The Central United States (CUS) includes two of the major seismic zones east of the Rockies: the New Madrid and Wabash Valley Seismic Zones. The winter 1811-1812 New Madrid Seismic Zone (NMSZ) events were the largest intraplate sequence ever recorded in the United States. Together with their aftershocks, these earthquakes produced large areas of liquefaction, new lakes, and landslides in the region. Seismicity in the early 1800’s was dominated by the NMSZ activity, although three low magnitude 5 earthquakes occurred in the last 40 years in the Wabash Valley Seismic Zone (WVSZ). The population and infrastructure of the CUS have drastically changed from that of the early nineteenth century, and a large earthquake would now cause significant casualties and economic losses within the country’s heartland. In this study we present three sets of numerical simulations depicting earthquakes in the region. These hypothetical ruptures are located on the Reelfoot fault and the southern axial arm of the NMSZ and in the WVSZ. Our broad-band synthetic ground motions are calculated following the Liu et al. (2006) hybrid method. Using a finite element solver we calculate low frequency ground motion (< 1 Hz) which accounts for the heterogeneity and low velocity soils of the region by using a recently developed seismic velocity model (CUSVM1) and a minimum shear wave velocity of 300 m/s. The broad-band ground motions are then generated by combining high frequency synthetics computed in a 1D velocity model with the low frequency motions at a crossover frequency of 1 Hz. We primarily discuss the basin effects produced by the Mississippi embayment and investigate the effects of hypocentral location and slip distribution on ground motions in densely populated areas within the CUS.

Ramirez Guzman, L.; Boyd, O. S.; Hartzell, S.; Williams, R. A.

2010-12-01

219

Equatorial ground ice on Mars: Steady-state stability

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

220

Ground state and excitation dynamics in Ag doped helium clusters

NASA Astrophysics Data System (ADS)

We present a quantum Monte Carlo study of the structure and energetics of silver doped helium clusters AgHen for n up to 100. Our simulations show the first solvation shell of the Ag atom to include roughly 20 He atoms, and to possess a structured angular distribution. Moreover, the 2P1/2?2S1/2 and 2P3/2?2S1/2 electronic transitions of the embedded silver impurity have been studied as a function of the number of helium atoms. The computed spectra show a redshift for n?15 and an increasing blueshift for larger clusters, a feature attributed to the effect of the second solvation shell of He atoms. For the largest cluster, the computed excitation spectrum is found in excellent agreement with the ones recorded in superfluid He clusters and bulk. No signature of the direct formation of the proposed AgHe2 exciplex is present in the computed spectrum of AgHe100. To explain the absence of the fluorescent D2 line in the experiments, a relaxation mechanism between the 2P3/2 and the 2P1/2 states is proposed on the basis of the partial overlap of the excitation bands in the simulated spectra.

Mella, Massimo; Colombo, Maria Carola; Morosi, Gabriele

2002-12-01

221

End states in one-dimensional atom chains.

End states--the zero-dimensional analogs of the two-dimensional states that occur at a crystal surface--were observed at the ends of one-dimensional atom chains that were self-assembled by depositing gold on the vicinal Si(553) surface. Scanning tunneling spectroscopy measurements of the differential conductance along the chains revealed quantized states in isolated segments with differentiated states forming over end atoms. A comparison to a tight-binding model demonstrated how the formation of electronic end states transforms the density of states and the energy levels within the chains. PMID:15692047

Crain, J N; Pierce, D T

2005-02-01

222

Photoionization of Fe7+ from the ground and metastable states

NASA Astrophysics Data System (ADS)

The B -spline Breit-Pauli R -matrix method is used to investigate the photoionization of Fe7 + from the ground and metastable states in the energy region from ionization thresholds to 172 eV. The present calculations were designed to resolve the large discrepancies between recent measurements and available theoretical results. The multiconfiguration Hartree-Fock method in connection with B -spline expansions is employed for an accurate representation of the initial- and final-state wave functions. The close-coupling expansion includes 99 fine-structure levels of the residual Fe8 + ion in the energy region up to 3 s23 p54 s states. It includes levels of the 3 s23 p6,3 s23 p53 d ,3 s23 p54 s , and 3 s 3 p63 d configurations and some levels of the 3 s23 p43 d2 configuration which lie in the energy region under investigation. The present photoionization cross sections in the length and velocity formulations exhibit excellent agreement. The present photoionization cross sections agree well with the Breit-Pauli R -matrix calculation by Sossah et al. and the TOPbase data in the magnitude of the background nonresonant cross sections but show somewhat richer resonance structures, which qualitatively agree with the measurements. The calculated cross sections, however, are several times lower than the measured cross sections, depending upon the photon energy. The cross sections for photoionization of metastable states were found to have approximately the same magnitude as the cross sections for photoionization of the ground state, thereby the presence of metastable states in the ion beam may not be the reason for the enhancement of the measured cross sections.

Tayal, S. S.; Zatsarinny, O.

2015-01-01

223

Entanglement of large atomic samples: A Gaussian-state analysis

We present a Gaussian-state analysis of the entanglement generation between two macroscopic atomic ensembles due the continuous probing of collective spin variables by optical Faraday rotation. The evolution of the mean values and the variances of the atomic variables is determined, and the entanglement is characterized by the Gaussian entanglement of formation and the logarithmic negativity. The effects of induced opposite Larmor rotation of the samples and of light absorption and atomic decay are analyzed in detail.

Sherson, Jacob; Moelmer, Klaus [QUANTOP, Danish Research Foundation Center for Quantum Optics, Department of Physics and Astronomy, University of Aarhus, DK 8000 Aarhus C (Denmark)

2005-03-01

224

Coulomb breakup of $^{37}$Mg and its ground state structure

We calculate Coulomb breakup of the neutron rich nucleus $^{37}$Mg on a Pb target at the beam energy of 244 MeV/nucleon within the framework of a finite range distorted wave Born approximation theory that is extended to include the effects of projectile deformation. In this theory, the breakup amplitude involves the full wave function of the projectile ground state. Calculations have been carried out for the total one-neutron removal cross section $(\\sigma_{-1n})$, the neutron-core relative energy spectrum, the parallel momentum distribution of the core fragment, the valence neutron angular, and energy-angular distributions. The calculated $\\sigma_{-1n}$ has been compared with the recently measured data to put constraints on the spin parity, and the one-neutron separation energy ($S_{-1n}$) of the $^{37}$Mg ground state ($^{37}$Mg$_{gs}$). The dependence of $\\sigma_{-1n}$ on the deformation of this state has also been investigated. Our study suggests that $^{37}$Mg$_{gs}$ is most likely to have a spin parity ...

Shubhchintak,; Chatterjee, R; Shyam, R; Tsushima, K

2015-01-01

225

Microstructure of as-fabricated UMo/Al(Si) plates prepared with ground and atomized powder

NASA Astrophysics Data System (ADS)

UMo-Al based fuel plates prepared with ground U8wt%Mo, ground U8wt%MoX (X = 1 wt%Pt, 1 wt%Ti, 1.5 wt%Nb or 3 wt%Nb) and atomized U7wt%Mo have been examined. The first finding is that that during the fuel plate production the metastable ?-UMo phases partly decomposed into two different ?-UMo phases, U2Mo and ?'-U in ground powder or ??-U in atomized powder. Alloying small amounts of a third element to the UMo had no measurable effect on the stability of the ?-UMo phase. Second, the addition of some Si inside the Al matrix and the presence of oxide layers in ground and atomized samples is studied. In the case with at least 2 wt%Si inside the matrix a Silicon rich layer (SiRL) forms at the interface between the UMo and the Al during the fuel plate production. The SiRL forms more easily when an Al-Si alloy matrix - which is characterized by Si precipitates with a diameter ?1 ?m - is used than when an Al-Si mixed powder matrix - which is characterized by Si particles with some ?m diameter - is used. The presence of an oxide layer on the surface of the UMo particles hinders the formation of the SiRL. Addition of some Si into the Al matrix [7-11]. Application of a protective barrier at the UMo/Al interface by oxidizing the UMo powder [7,12]. Increase of the Mo content or use of UMo alloys with ternary element addition X (e.g. X = Nb, Ti, Pt) to stabilize the ?-UMo with respect to ?-U or to control the UMo-Al interaction layer kinetics [9,12-24]. Use of ground UMo powder instead of atomized UMo powder [10,25] The points 1-3 are to limit the formation of the undesired UMo/Al layer. Especially the addition of Si into the matrix has been suggested [3,7,8,10,11,26,27]. It has been often mentioned that Silicon is efficient in reducing the Uranium-Aluminum diffusion kinetics since Si shows a higher chemical affinity to U than Al to U. Si suppresses the formation of brittle UAl4 which causes a huge swelling during the irradiation. Furthermore it enhances the formation of more stable UAl3 within the diffusion layer [14]. In addition, Si will not notably influence the reactor neutronics due to its low absorption cross section for thermal neutrons of ?abs = 0.24 barn. Aluminum has ?abs = 0.23 barn.Williams [28], Bierlein [29], Green [30] and de Luca [31] showed the first time in the 1950s that alloying Aluminum with some Silicon reduces the Uranium-Aluminum diffusion kinetics in can-type fuel elements. However, up to now uncertainties remained about the most promising Si concentration and the involved mechanisms.Ground powder - possibility 4 - introduces a high density of defects like dislocations, oxide layers and impurities into UMo grains. Fuel prepared with this kind of powder exhibits a larger porosity. It may also be combined with an AlSi matrix. As a consequence, the degree of swelling due to high-burn up is reduced compared to fuel with atomized powder [5,6,25].This study focuses on the metallurgical characterization of as-fabricated samples prepared with ground UMo and UMoX (X = Ti, Nb, Pt) powders and atomized UMo powder. The influence of some Si into the Al matrix and the presence of oxide layers on the UMo is discussed. Details of the differences of samples with ground UMo from atomized UMo will be discussed.The examined samples originate from non-irradiated spare fuel plates from the IRIS-TUM irradiation campaign [5,6]. The samples containing ground UMoX powders and atomized UMo powders with Si addition into the matrix have been produced for this study [32]. Powder mixing: The UMo powder is mixed with Al powder. Compact production: UMo-Al powder is poured into a mould and undergoes compaction under large force. Plate-processing: An AlFeNi frame is placed on an AlFeNi plate and the UMo-Al compact is placed into the frame. Afterwards it is covered with a second AlFeNi plate. This assembly is hot-rolled to reduce the total thickness to 1.4 mm. Subsequently, a blister test (1-2 h at 400-450 °C) ensures that the fuelplate is sealed. After this step, the UMo particles are tightly covered with Al as shown in Fig. 1.

Jungwirth, R.; Palancher, H.; Bonnin, A.; Bertrand-Drira, C.; Borca, C.; Honkimäki, V.; Jarousse, C.; Stepnik, B.; Park, S.-H.; Iltis, X.; Schmahl, W. W.; Petry, W.

2013-07-01

226

Monogamy and ground-state entanglement in highly connected systems

We consider the ground-state entanglement in highly connected many-body systems consisting of harmonic oscillators and spin-1/2 systems. Varying their degree of connectivity, we investigate the interplay between the enhancement of entanglement, due to connections, and its frustration, due to monogamy constraints. Remarkably, we see that in many situations the degree of entanglement in a highly connected system is essentially of the same order as in a low connected one. We also identify instances in which the entanglement decreases as the degree of connectivity increases.

Ferraro, Alessandro; Garcia-Saez, Artur; Acin, Antonio [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona (Spain)

2007-11-15

227

Fragility of Thermodynamically-Abnormal Ground States of Finite Systems

We study a general macroscopic quantum system of a finite size, which will exhibit a symmetry breaking if the system size goes to infinity, when the system interacts with an environment. We evaluate the decoherence rates of the anomalously fluctuating vacuum (AFV), which is the symmetric ground state, and the pure phase vacua (PPVs). By making full use of the locality and huge degrees of freedom, we show that there can exist an interaction with an environment which makes the decoherence rate of the AFV anomalously fast, whereas PPVs are less fragile.

Takayuki Miyadera; Akira Shimizu

2001-09-14

228

Lee-Yang Polynomials and Ground States of Spin Systems

NASA Astrophysics Data System (ADS)

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,

Slawny, Joseph

2014-08-01

229

Inequalities between ground-state energies of Heisenberg models

NASA Astrophysics Data System (ADS)

The Lieb-Schupp inequality is the inequality between ground state energies of certain antiferromagnetic Heisenberg spin systems. In our paper, the numerical value of energy difference given by Lieb-Schupp inequality has been tested for spin systems in various geometries: chains, ladders and quasi-two-dimensional lattices. It turned out that this energy difference was strongly dependent on the class of the system. The relation between this difference and a fall-off of a correlation function has been empirically found and formulated as a conjecture.

Wojtkiewicz, Jacek; Skolasi?ski, Rafa?

2015-02-01

230

NASA Astrophysics Data System (ADS)

For Li+ and Na+ scattering from clean and cesium-covered Cu(001) surfaces, we have measured probabilities to form different final electronic states in the scattered flux as a function of the Cs-induced work-function shift [Delta][phi]. Specifically, positive and negative ion yields for 400 eV Li+ scattering, and the relative yields of excited neutral Li(2p) and Na(3p) for 400 and 100 eV Li+ and 1320 eV Na+ scattering were measured. As we lowered the work function from its clean (metal) surface value, we observed a monotonic decrease in the Li+ yield, a monotonic increase in the Li+ yield, and a peak in the minority Li(2p) channel yield (and the Na(3p) yield). The major trends in the Li/Cu(001) data (and likewise in the Na/Cu(001) data) can be reproduced by use of a multi-state model, developed by Marston and co-workers, of resonant charge transfer. Here we present a new, straightforward explanation of these trends, based upon an examination of the many-electron states of the atom--metal system. Much of the charge transfer dynamics can be understood through the ground state of the interacting Li/Cu(001) system, since the `atom probabilities'--the probabilities that the Li is a Li+, Li(2s), Li(2p), or Li+-tend to equilibrate towards their ground-state values throughout the atom's trajectory. In each of our experiments, the velocity is low enough that the Li/Cu(001) system electronically equilibrates close to the surface, where the atom--metal couplings are large; at small atom--metal separations z, the Li atom probabilities therefore track their ground-state values. As the atom moves along its outgoing trajectory, the couplings decrease exponentially, and eventually the atom probabilities lose track of their ground-state values. Qualitative arguments, based upon general principles of quantum mechanics, allow us to understand the dependence of the ground-state probabilities on the work function [phi] and z. To comprehend the origin of the Li(2p) peak we must consider both the ground-state probabilities and the conditions under which the dynamical probabilities lose track of their ground-state values.

Dahl, E. B.; Behringer, E. R.; Andersson, D. R.; Cooper, B. H.

1998-03-01

231

NASA Astrophysics Data System (ADS)

We present a simple and stable numerical method to approximate the ground state of a quantum many-body system by multiple determinant states. This method searches these determinant states one by one according to the matching pursuit algorithm. The first determinant state is identical to that of the Hartree-Fock theory. Calculations for a two-dimensional Hubbard model serve as a demonstration.

Jie, Quanlin

2008-02-01

232

We present a simple and stable numerical method to approximate the ground state of a quantum many-body system by multiple determinant states. This method searches these determinant states one by one according to the matching pursuit algorithm. The first determinant state is identical to that of the Hartree-Fock theory. Calculations for a two-dimensional Hubbard model serve as a demonstration. PMID:18352146

Jie, Quanlin

2008-02-01

233

Improved estimates of the total correlation energy in the ground state of the water molecule

Improved estimates of the total correlation energy in the ground state of the water molecule Arne calculations of the electronic energy of the ground state of the water molecule yield energies lower than those for the electronic energy of the ground state of the water molecule. The energy given by a fixed-node quantum Monte

Anderson, James B.

234

Entanglement concentration for unknown atomic entangled states via entanglement swapping

An entanglement concentration scheme for unknown atomic entanglement states is proposed via entanglement swapping in cavity QED. Because the interaction used here is a large-detuned one between two driven atoms and a quantized cavity mode, the effects of the cavity decay and thermal field have been eliminated. These advantages can warrant the experimental feasibility of the current scheme.

Yang Ming; Zhao Yan; Song Wei; Cao Zhuoliang [Anhui Key Laboratory of Information Material and Devices, School of Physics and Material Science, Anhui University, Hefei 230039 (China)

2005-04-01

235

Internal State Manipulation for Neutral Atom Lithography A thesis presented

Internal State Manipulation for Neutral Atom Lithography A thesis presented by Joseph Hermann lithography (ARL), the first use of frequency encoding of spatial information for atom lithography. ARL has physics and teaching me how to write scientific papers. I would also like to thank Nynke Dekker, Kent

Thywissen, Joseph

236

From rotating atomic rings to quantum Hall states

an ordered vortex lattice is formed. For v , 10, the lattice melts because of quantum fluctuations, whichFrom rotating atomic rings to quantum Hall states M. Roncaglia1,2 , M. Rizzi2 & J. Dalibard3 1 are currently devoted to the preparation of ultracold neutral atoms in the strongly correlated quantum Hall

Dalibard, Jean

237

Ground State Degeneracy of Topological Phases on Open Surfaces

We relate the ground state degeneracy (GSD) of a non-Abelian topological phase on a surface with boundaries to the anyon condensates that break the topological phase to a trivial phase. Specifically, we propose that gapped boundary conditions of the surface are in one-to-one correspondence to the sets of condensates, each being able to completely break the phase, and we substantiate this by examples. The GSD resulting from a particular boundary condition coincides with the number of confined topological sectors due to the corresponding condensation. These lead to a generalization of the Laughlin-Wu-Tao (LWT) charge-pumping argument for Abelian fractional quantum Hall states (FQHS) to encompass non-Abelian topological phases, in the sense that an anyon loop of a confined anyon winding a non-trivial cycle can pump a condensate from one boundary to another. Such generalized pumping may find applications in quantum control of anyons, eventually realizing topological quantum computation.

Ling-Yan Hung; Yidun Wan

2014-07-31

238

The Transcriptional and Epigenomic Foundations of Ground State Pluripotency

Summary Mouse embryonic stem (ES) cells grown in serum exhibit greater heterogeneity in morphology and expression of pluripotency factors than ES cells cultured in defined medium with inhibitors of two kinases (Mek and GSK3), a condition known as “2i” postulated to establish a naive ground state. We show that the transcriptome and epigenome profiles of serum- and 2i-grown ES cells are distinct. 2i-treated cells exhibit lower expression of lineage-affiliated genes, reduced prevalence at promoters of the repressive histone modification H3K27me3, and fewer bivalent domains, which are thought to mark genes poised for either up- or downregulation. Nonetheless, serum- and 2i-grown ES cells have similar differentiation potential. Precocious transcription of developmental genes in 2i is restrained by RNA polymerase II promoter-proximal pausing. These findings suggest that transcriptional potentiation and a permissive chromatin context characterize the ground state and that exit from it may not require a metastable intermediate or multilineage priming. PMID:22541430

Marks, Hendrik; Kalkan, Tüzer; Menafra, Roberta; Denissov, Sergey; Jones, Kenneth; Hofemeister, Helmut; Nichols, Jennifer; Kranz, Andrea; Francis Stewart, A.; Smith, Austin; Stunnenberg, Hendrik G.

2012-01-01

239

The ground state far infrared spectrum of NH3

NASA Technical Reports Server (NTRS)

The NH3 far infrared spectrum is particularly useful for the study of planetary composition and atmospheric dynamics. Studies of this spectrum were conducted by Dowling (1969), Helminger et al. (1971), and Urban et al. (1981). Sattler et al. (1981) have reported measurements of a few nu2 lines with tunable diode lasers. By using simple sum rules, these lines and accurate ground state inversion lines considered by Poynter and Kakar (1975) have been employed in the present investigation to deduce a few of the far infrared ground state transitions. An extensive set of high signal/noise, high resolution (0.0048 per cm) scans of the nu2 bands of NH3 from about 600 per cm through about 1300 per cm ait a series of low pressures have been made in order to accurately determine both the line positions and strengths. The obtained data provide line positions with an absolute accuracy of about 0.0001 per cm in the more favorable cases.

Poynter, R. L.; Margolis, J. S.

1983-01-01

240

The ground and first excited torsional states of methyl carbamate

NASA Astrophysics Data System (ADS)

A global fit within experimental accuracy of microwave and millimeter-wave transitions in the ground and first excited torsional states of methyl carbamate (H 2NC(O)OCH 3) is presented. The data set consisting of 995 vt = 0 and 731 vt = 1 transition frequencies combines 1544 new measurements from Kharkov with previously published vt = 0 microwave lines. In this study the so-called "rho axis method" that treats simultaneously both A and E species of the ground and first excited torsional states is applied to the methyl carbamate data set for the first time. The final fit requires only 32 parameters to achieve a unitless weighted standard deviation for the whole fit of 0.89 for a total of 1726 transitions with rotational quantum numbers up to J ? 20 and Ka ? 10. The barrier to internal rotation of the methyl group obtained in this study, V3 = 359.141(24) cm -1, is in good agreement with previously published values but more accurate.

Ilyushin, V.; Alekseev, E.; Demaison, J.; Kleiner, I.

2006-11-01

241

NASA Technical Reports Server (NTRS)

The effects of atomic oxygen on boron nitride (BN), silicon nitride (Si3N4), Intelsat 6 solar cell interconnects, organic polymers, and MoS2 and WS2 dry lubricant, were studied in Low Earth Orbit (LEO) flight experiments and in a ground based simulation facility. Both the inflight and ground based experiments employed in situ electrical resistance measurements to detect penetration of atomic oxygen through materials and Electron Spectroscopy for Chemical Analysis (ESCA) analysis to measure chemical composition changes. Results are given. The ground based results on the materials studied to date show good qualitative correlation with the LEO flight results, thus validating the simulation fidelity of the ground based facility in terms of reproducing LEO flight results. In addition it was demonstrated that ground based simulation is capable of performing more detailed experiments than orbital exposures can presently perform. This allows the development of a fundamental understanding of the mechanisms involved in the LEO environment degradation of materials.

Cross, Jon B.; Koontz, Steven L.; Lan, Esther H.

1993-01-01

242

Efficient excitation of Rydberg states in ultracold lithium-7 atoms

NASA Astrophysics Data System (ADS)

This work is aimed at preparing highly excited optically cooled lithium-7 atoms for producing a strongly nonideal plasma and Rydberg matter. A setup implementing a novel nondestructive technique for preparation and diagnostics of highly excited Rydberg atomic states is constructed. The operation of this setup is based on the usage of a cw high-power ultraviolet laser combined with a magneto-optical trap. The diagnostics of highly excited states is performed by the direct recording of the variations in the fluorescence of ultracold lithium-7 atoms in the magneto-optical trap.

Zelener, B. B.; Saakyan, S. A.; Sautenkov, V. A.; Manykin, E. A.; Zelener, B. V.; Fortov, V. E.

2014-11-01

243

Manipulation of Non-classical Atomic Spin States

We report successful manipulation of non-classical atomic spin states. We generate squeezed spin states by a spin quantum nondemolition measurement, and apply an off-resonant circularly-polarized light pulse to the atoms. By changing the pulse duration, we have clearly observed a rotation of anisotropic quantum noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum noise distribution is always isotropic. This is an important step for quantum state tomography, quantum swapping, and precision spectroscopic measurement.

Tetsushi Takano; Shin-Ichi-Ro Tanaka; Ryo Namiki; Yoshiro Takahashi

2009-09-13

244

Single-Atom Gating of Quantum State Superpositions

The ultimate miniaturization of electronic devices will likely require local and coherent control of single electronic wavefunctions. Wavefunctions exist within both physical real space and an abstract state space with a simple geometric interpretation: this state space - or Hilbert space - is spanned by mutually orthogonal state vectors corresponding to the quantized degrees of freedom of the real-space system. Measurement of superpositions is akin to accessing the direction of a vector in Hilbert space, determining an angle of rotation equivalent to quantum phase. Here we show that an individual atom inside a designed quantum corral1 can control this angle, producing arbitrary coherent superpositions of spatial quantum states. Using scanning tunnelling microscopy and nanostructures assembled atom-by-atom we demonstrate how single spins and quantum mirages can be harnessed to image the superposition of two electronic states. We also present a straightforward method to determine the atom path enacting phase rotations between any desired state vectors. A single atom thus becomes a real-space handle for an abstract Hilbert space, providing a simple technique for coherent quantum state manipulation at the spatial limit of condensed matter.

Moon, Christopher

2010-04-28

245

Combined quantum-state preparation and laser cooling of a continuous beam of cold atoms

We use two-laser optical pumping on a continuous atomic fountain in order to prepare cold cesium atoms in the same quantum ground state. A first laser excites the F=4 ground state to pump the atoms toward F=3 while a second {pi}-polarized laser excites the F=3{yields}F{sup '}=3 transition of the D{sub 2} line to produce Zeeman pumping toward m=0. To avoid trap states, we implement the first laser in a two-dimensional optical lattice geometry, thereby creating polarization gradients. This configuration has the advantage of simultaneously producing Sisyphus cooling when the optical lattice laser is tuned between the F=4{yields}F{sup '}=4 and F=4{yields}F{sup '}=5 transitions of the D{sub 2} line, which is important to remove the heat produced by optical pumping. Detuning the frequency of the second {pi}-polarized laser reveals the action of a mechanism improving both laser cooling and state-preparation efficiency. A physical interpretation of this mechanism is discussed.

Di Domenico, Gianni; Devenoges, Laurent; Dumas, Claire; Thomann, Pierre [Laboratoire Temps-Frequence, Universite de Neuchatel, Avenue de Bellevaux 51, CH-2009 Neuchatel (Switzerland)

2010-11-15

246

Ground state of small mixed helium and spin-polarized tritium clusters: A quantum Monte Carlo study

We report results for the ground-state energy and structural properties of small 4He-T? clusters consisting of up to four T? and eight 4He atoms. These results have been obtained using very well-known 4He-4He and T?- T? interaction potentials and several models for the 4He- T? interatomic potential. All the calculations have been performed with variational and diffusion Monte Carlo methods.

P. Stipanovic; L. Vranjes Markic; J. Boronat; B. Kezic

2011-01-01

247

Ground state of small mixed helium and spin-polarized tritium clusters: A quantum Monte Carlo study

We report results for the ground-state energy and structural properties of small 4He–T? clusters consisting of up to four T? and eight 4He atoms. These results have been obtained using very well-known 4He–4He and T?– T? interaction potentials and several models for the 4He– T? interatomic potential. All the calculations have been performed with variational and diffusion Monte Carlo methods.

P. Stipanovic´; J. Boronat

2011-01-01

248

The GeH radical has been detected in its ground 2 Pi state in the gas phase reaction of fluorine atoms with GeH4 by laser magnetic resonance techniques. Rotational transitions within both 2 Pi 1\\/2 and 2 Pi 3\\/2 manifolds have been observed at far-infrared wavelengths and rotational transitions between the two fine structure components have been detected at infrared wavelengths

J. M. Brown; K. M. Evenson; T. J. Sears

1985-01-01

249

The GeH radical has been detected in its ground 2&Pgr; state in the gas phase reaction of fluorine atoms with GeH4 by laser magnetic resonance techniques. Rotational transitions within both 2&Pgr;1\\/2 and 2&Pgr;3\\/2 manifolds have been observed at far-infrared wavelengths and rotational transitions between the two fine structure components have been detected at infrared wavelengths (10 ?m). Signals have been

John M. Brown; K. M. Evenson; Trevor J. Sears

1985-01-01

250

Ground-Laboratory to In-Space Effective Atomic-Oxygen Fluence Determined for DC 93-500 Silicone

NASA Technical Reports Server (NTRS)

Surfaces on the leading edge of spacecraft in low Earth orbit (e.g., surface facing the velocity direction), such as on the International Space Station, are subject to atomic oxygen attack, and certain materials are susceptible to erosion. Therefore, ground-based laboratory testing of the atomic oxygen durability of spacecraft materials is necessary for durability assessment when flight data are not available. For accurate space simulation, the facility is commonly calibrated on the basis of the mass loss of Kapton (DuPont, Wilmington, DE) as a control sample for effective fluence determination. This is because Kapton has a well-characterized atomic oxygen erosion yield (E(sub y), in cubic centimeters per atom) in the low Earth orbit (LEO) environment. Silicones, a family of commonly used spacecraft materials, do not chemically erode away with atomic oxygen attack like other organic materials that have volatile oxidation products. Instead, silicones react with atomic oxygen and form an oxidized hardened silicate surface layer. Often the loss of methyl groups causes shrinkage of the surface skin and "mud-tile" crazing degradation. But silicones often do not lose mass, and some silicones actually gain mass during atomic oxygen exposure. Therefore, the effective atomic oxygen fluence for silicones in a ground-test facility should not be determined on the basis of traditional mass-loss measurements, as it is with polymers that erode. Another method for determining effective fluence needs to be employed for silicones. A new technique has been developed at the NASA Glenn Research Center for determining the effective atomic oxygen fluence for silicones in ground-test facilities. This technique determines the equivalent amount of atomic oxygen oxidation on the basis of changes in the surface-oxide hardness. The specific approach developed was to compare changes in the surface hardness of ground-laboratory-exposed DC93-500 silicone with DC93-500 exposed to LEO atomic oxygen as part of a shuttle flight experiment. The on-the-ground to in-space effective atomic oxygen fluence was determined on the basis of the Kapton effective fluence in the ground-laboratory facility that produced the same hardness for the fluence in space.

deGroh, Kim K.; Banks, Bruce A.; Ma, David

2005-01-01

251

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

252

Ground states of dispersion-managed nonlinear Schrodinger equation

An exact pulse for the parametrically forced nonlinear Schrodinger equation (NLS) is isolated. The equation governs wave envelope propagation in dispersion-managed fiber lines with positive residual dispersion. The pulse is obtained as a ground state of an averaged variational principle associated with the equation governing pulse dynamics. The solutions of the averaged and original equations are shown to stay close for a sufficiently long time. A properly adjusted pulse will therefore exhibit nearly periodic behavior in the time interval of validity of the averaging procedure. Furthermore, we show that periodic variation of dispersion can stabilize spatial solitons in a Kerr medium and one-dimensional solitons in the NLS with quintic nonlinearity. The results are confirmed by numerical simulations. PMID:11102097

Zharnitsky; Grenier; Turitsyn; Jones; Hesthaven

2000-11-01

253

Antiferromagnetic Spin-S Chains with Exactly Dimerized Ground States

NASA Astrophysics Data System (ADS)

We show that spin S Heisenberg spin chains with an additional three-body interaction of the form (Si-1·Si)(Si·Si+1)+H.c. possess fully dimerized ground states if the ratio of the three-body interaction to the bilinear one is equal to 1/[4S(S+1)-2]. This result generalizes the Majumdar-Ghosh point of the J1-J2 chain, to which the present model reduces for S=1/2. For S=1, we use the density matrix renormalization group method to show that the transition between the Haldane and the dimerized phases is continuous with a central charge c=3/2. Finally, we show that such a three-body interaction appears naturally in a strong-coupling expansion of the Hubbard model, and we discuss the consequences for the dimerization of actual antiferromagnetic chains.

Michaud, Frédéric; Vernay, François; Manmana, Salvatore R.; Mila, Frédéric

2012-03-01

254

Nondegeneracy of the ground state for nonrelativistic Lee model

NASA Astrophysics Data System (ADS)

In the present work, we first briefly sketch the construction of the nonrelativistic Lee model on Riemannian manifolds, introduced in our previous works. In this approach, the renormalized resolvent of the system is expressed in terms of a well-defined operator, called the principal operator, so as to obtain a finite formulation. Then, we show that the ground state of the nonrelativistic Lee model on compact Riemannian manifolds is nondegenerate using the explicit expression of the principal operator that we obtained. This is achieved by combining heat kernel methods with positivity improving semi-group approach and then applying these tools directly to the principal operator, rather than the Hamiltonian, without using cut-offs.

Erman, Fatih; Malkoç, Berkin; Turgut, O. Teoman

2014-08-01

255

Masses of ground and excited-state hadrons

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 Delta masses and those of the dressed-quark and diquark correlations they contain.

H. L. L. Roberts; L. Chang; I. C. Cloet; C. D. Roberts

2011-01-21

256

Energy dependence of scattering ground-state polar molecules

We explore the total collisional cross section of ground-state polar molecules in an electric field at various energies, focusing on RbCs and RbK. An external electric field polarizes the molecules and induces strong dipolar interactions, leading to nonzero partial waves contributing to the scattering even as the collision energy goes to zero. This results in the need to compute scattering problems with many different values of total M to converge the total cross section. An accurate and efficient approximate total cross section is introduced and used to study the low-field temperature dependence. To understand the scattering of the polar molecules we compare a semiclassical cross section with the quantum unitarity limit. This comparison leads to the ability to characterize the scattering based on the value of the electric field and the collision energy. General and simple forms of the characteristic electric field and energy are given, enabling characterization of the scattering.

Ticknor, Christopher [ARC Centre of Excellence for Quantum-Atom Optics and Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

2007-11-15

257

Measuring atomic NOON-states and using them to make precision measurements

A scheme for creating NOON-states of the quasi-momentum of ultra-cold atoms has recently been proposed [New J. Phys. 8, 180 (2006)]. This was achieved by trapping the atoms in an optical lattice in a ring configuration and rotating the potential at a rate equal to half a quantum of angular momentum . In this paper we present a scheme for confirming that a NOON-state has indeed been created. This is achieved by spectroscopically mapping out the anti-crossing between the ground and first excited levels by modulating the rate at which the potential is rotated. Finally we show how the NOON-state can be used to make precision measurements of rotation.

David W. Hallwood; Adam Stokes; Jessica J. Cooper; Jacob Dunningham

2009-07-18

258

Thermodynamic ground state of MgB{sub 6} predicted from first principles structure search methods

Crystalline structures of magnesium hexaboride, MgB{sub 6}, were investigated using unbiased structure searching methods combined with first principles density functional calculations. An orthorhombic Cmcm structure was predicted as the thermodynamic ground state of MgB{sub 6}. The energy of the Cmcm structure is significantly lower than the theoretical MgB{sub 6} models previously considered based on a primitive cubic arrangement of boron octahedra. The Cmcm structure is stable against the decomposition to elemental magnesium and boron solids at atmospheric pressure and high pressures up to 18.3 GPa. A unique feature of the predicted Cmcm structure is that the boron atoms are clustered into two forms: localized B{sub 6} octahedra and extended B{sub ?} ribbons. Within the boron ribbons, the electrons are delocalized and this leads to a metallic ground state with vanished electric dipoles. The present prediction is in contrast to the previous proposal that the crystalline MgB{sub 6} maintains a semiconducting state with permanent dipole moments. MgB{sub 6} is estimated to have much weaker electron-phonon coupling compared with that of MgB{sub 2}, and therefore it is not expected to be able to sustain superconductivity at high temperatures.

Wang, Hui [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China) [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); LeBlanc, K. A. [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)] [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Gao, Bo [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)] [State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Yao, Yansun, E-mail: yansun.yao@usask.ca [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada) [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Canadian Light Source, Saskatoon, Saskatchewan S7N 0X4 (Canada)

2014-01-28

259

On the hydrino state of the relativistic hydrogen atom

The Klein-Gordon equation of the hydrogen atom has a low-lying eigenstate, called hydrino state, with square integrable wavefunction. The corresponding spinor solution of Dirac's equation is not square integrable. For this reason the hydrino state has been rejected in the early days of quantum mechanics as being unphysical. Maybe it is time to change opinion.

Jan Naudts

2005-08-05

260

Macroscopical Entangled Coherent State Generator in V configuration atom system

In this paper, we propose a scheme to produce pure and macroscopical entangled coherent state. When a three-level ''V'' configuration atom interacts with a doubly reasonant cavity, under the strong classical driven condition, entangled coherent state can be generated from vacuum fields. An analytical solution for this system under the presence of cavity losses is also given.

Ling Zhou; Han Xiong

2007-11-26

261

Calculation of the positron bound state with the copper atom

A new relativistic method for calculation of positron binding to atoms is presented. The method combines a configuration interaction treatment of the valence electron and the positron with a many-body perturbation theory description of their interaction with the atomic core. We apply this method to positron binding by the copper atom and obtain the binding energy of 170 meV (+ - 10%). To check the accuracy of the method we use a similar approach to calculate the negative copper ion. The calculated electron affinity is 1.218 eV, in good agreement with the experimental value of 1.236 eV. The problem of convergence of positron-atom bound state calculations is investigated, and means to improve it are discussed. The relativistic character of the method and its satisfactory convergence make it a suitable tool for heavier atoms.

Dzuba, V A; Gribakin, G F; Harabati, C

1999-01-01

262

Transmission-line decelerators for atoms in high Rydberg states

Beams of helium atoms in Rydberg states with principal quantum number $n=52$, and traveling with an initial speed of 1950 m/s, have been accelerated, decelerated and guided while confined in moving electric traps generated above a curved, surface-based electrical transmission line with a segmented center conductor. Experiments have been performed with atoms guided at constant speed, and with accelerations exceeding $10^7$ m/s$^2$. In each case the manipulated atoms were detected by spatially resolved, pulsed electric field ionization. The effects of tangential and centripetal accelerations on the effective trapping potentials experienced by the atoms in the decelerator have been studied, with the resulting observations highlighting contributions from the density of excited Rydberg atoms to the acceleration, deceleration and guiding efficiencies in the experiments.

Lancuba, P

2014-01-01

263

Subwavelength atom localization via coherent population trapping

We present an atom localization scheme based on coherent population trapping. We consider atomic transitions in a Lambda configuration where the control field is a standing-wave field. The probe field and the control field produce coherence between the two ground states and prepare the atom in a pure state. We show that the population in one of the ground states

G S Agarwal; K T Kapale

2006-01-01

264

State-labeling Wannier-Stark atomic interferometers

NASA Astrophysics Data System (ADS)

Using cold 87Rb atoms trapped in a one-dimensional (1D)-optical lattice, atomic interferometers involving coherent superpositions between different Wannier-Stark atomic states are realized. Two different kinds of trapped interferometer schemes are presented: a Ramsey-type interferometer sensitive both to clock frequency and external forces, and a symmetric accordion-type interferometer, sensitive to external forces only. We evaluate the limits in terms of sensitivity and accuracy of those schemes and discuss their application as force sensors. As a first step, we apply these interferometers to the measurement of the Bloch frequency and the demonstration of a compact gravimeter.

Pelle, B.; Hilico, A.; Tackmann, G.; Beaufils, Q.; Pereira dos Santos, F.

2013-02-01

265

Ground-state depleted solid-state lasers: principles, characteristics and scaling

A novel class of rare-earth-doped solid-state lasers is described. The ground-state depleted laser is pumped by an intense (more than tens of kW cm?2) narrow-band (less than a few nm) laser source and is characterized by: (1) an unusually low laser ion doping density (5 to 10×1018ion cm?3), (2) an unusually large fractional excited population inversion density (4 to 8×1018

William F. Krupke; L. L. Chase

1990-01-01

266

Proton-coupled electron transfer (PCET) processes are elementary chemical reactions involved in a broad range of radical and redox reactions. Elucidating fundamental PCET reaction mechanisms are thus of central importance for chemical and biochemical research. Here we use quantum chemical density functional theory (DFT), time-dependent density functional theory (TDDFT), and the algebraic diagrammatic-construction through second-order (ADC(2)) to study the mechanism, thermodynamic driving force effects, and reaction barriers of both ground state proton transfer (pT) and photoinduced proton-coupled electron transfer (PCET) between nitrosylated phenyl-phenol compounds and hydrogen-bonded t-butylamine as an external base. We show that the obtained reaction barriers for the ground state pT reactions depend linearly on the thermodynamic driving force, with a Brønsted slope of 1 or 0. Photoexcitation leads to a PCET reaction, for which we find that the excited state reaction barrier depends on the thermodynamic driving force with a Brønsted slope of 1/2. To support the mechanistic picture arising from the static potential energy surfaces, we perform additional molecular dynamics simulations on the excited state energy surface, in which we observe a spontaneous PCET between the donor and the acceptor groups. Our findings suggest that a Brønsted analysis may distinguish the ground state pT and excited state PCET processes. PMID:25485993

Gamiz-Hernandez, Ana P; Magomedov, Artiom; Hummer, Gerhard; Kaila, Ville R I

2015-02-12

267

Ground-state neutron decay of ^21C

NASA Astrophysics Data System (ADS)

The ground state of neutron-unbound ^21C was measured for the first time in a neutron-fragment coincidence experiment at the National Superconducting Cyclotron Laboratory at Michigan State University. This is the heaviest neutron-unbound N = 15 nucleus and provides a measurement of the ?(1s1/2) - ?(0d5/2) shell gap in the presence of proton holes in the p shell. ^21C was produced via one-proton knockout from a ^22N secondary beam at 69.7 MeV/u. The Modular Neutron Array (MoNA) was used to measure the time-of-flight and position of emitted neutrons, while ^20C fragments were detected in a series of position and energy-sensitive detectors behind the MSU/FSU Sweeper magnet. The decay of ^21C was then reconstructed event-by-event from the four-momentum vectors of the neutron and fragment. Preliminary results will be presented.

Mosby, S.; Thoennessen, M.; Deyoung, P.

2010-11-01

268

Antiferromagnetic ground state in NpCoGe

NASA Astrophysics Data System (ADS)

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 =0.80?B. 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.

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

2014-03-01

269

NASA Astrophysics Data System (ADS)

Antihydrogen production has reached such a level that precision spectroscopic measurements of its properties are within reach. In particular, the ground-state level population is of central interest for experiments aiming at antihydrogen spectroscopy. The positron density and temperature dependence of the ground-state yield is a result of the interplay between recombination, collisional, and radiative processes. Considering the fact that antihydrogen atoms with the principal quantum number n =15 or lower quickly cascade down to the ground state within 1 ms, the number of such states is adopted as a measure of useful antihydrogen atoms. It has been found that the scaling behavior of the useful antihydrogen yield is different depending on the positron density and positron temperature.

Radics, B.; Murtagh, D. J.; Yamazaki, Y.; Robicheaux, F.

2014-09-01

270

NASA Technical Reports Server (NTRS)

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were 41 different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although spaceflight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground-laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground-laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground-based durability testing, ground-laboratory to in-space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio-frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground laboratory erosion yield values. Using the PEACE polymers asher to in-space erosion yield ratios will allow more accurate in-space materials performance predictions to be made based on plasma asher durability evaluation.

Stambler, Arielle H.; Inoshita, Karen E.; Roberts, Lily M.; Barbagallo, Claire E.; deGroh, Kim K.; Banks, Bruce A.

2011-01-01

271

The ground state phase diagrams and low-energy excitation of dimer XXZ spin ladder

NASA Astrophysics Data System (ADS)

We study the ground state and low-energy excitation of dimer XXZ spin ladder with Heisenberg and XXZ interactions along the rung and rail directions, respectively. Using a bond operator method, we get low-energy effective Hamiltonians in different parameter regions. Based on those low-energy effective Hamiltonians, we set up the ground state phase diagrams and investigate the properties of low-energy excitation in each phase. We will show that the results are exact one when the XXZ interactions along rail reduce to the Ising type. The quantum Monte Carlo and exact diagonalization methods are also applied to the finite system to verify the exact nature of the phases, the phase transitions and the low-energy excitation. Of all the phases, we pay a special attention to the gapped antiferromagnetic phase, which is disclosed to be a non-trivial one that exhibits the time-reversal symmetry. We also discuss how our findings could be realized and detected by using cold atoms in optical lattice.

Chen, Qi-Hui; Guo, Long-Fei; Li, Peng

2014-11-01

272

Radial profiles of ground-state transitions of heliumlike argon from the Alcator-C tokamak

Spectra of the complete series of ground-state transitions in heliumlike Ar/sup 16+/ (1snp-1s/sup 2/, for 2less than or equal ton<50) have been obtained from the Alcator-C tokamak with use of a compact x-ray crystal spectrometer. Radial profiles of these transitions have been measured and have been compared with the results of a transport model which includes the basic atomic processes. In the plasma center, collisional excitation is the most important population mechanism for the upper levels. For the outer regions of the plasma (r/a/sub L/>0.5), recombination of Ar/sup 17+/ is the dominant population process for upper levels of most transitions, and preferentially populates the n = 2 triplet levels. Impurity transport provides sufficient amounts of hydrogenlike argon at the cooler, outer radii. For the high-n transitions 1s9p-1s/sup 2/ and 1s10p-1s/sup 2/, charge-exchange recombination is the dominant population mechanism at the plasma edge under certain operating conditions. The intensities of these lines have been used to determine neutral-hydrogen density profiles. For ground-state transitions with n>13, charge transfer from excited neutral hydrogen is the only important population process for r/a/sub L/>0.5.

Rice, J.E.; Marmar, E.S.; Kaellne, E.; Kaellne, J.

1987-04-01

273

Structural expansions for the ground state energy of a simple metal

NASA Technical Reports Server (NTRS)

A structural expansion for the static ground state energy of a simple metal is derived. An approach based on single particle band structure which treats the electron gas as a non-linear dielectric is presented, along with 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.

Hammerberg, J.; Ashcroft, N. W.

1973-01-01

274

Spectral stochastic processes arising in quantum mechanical models with a non- L 2 ground state

A functional integral representation is given for a large class of quantum mechanical models with a non- L 2 ground state. As a prototype, the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure ( spectral stochastic process) is constructed on trajectories taking

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

275

Spectral stochastic processes arising in quantum mechanical models with a non- L 2 ground state

A functional integral representation is given for a large class of quantum mechanical models with a non-L2 ground state. As a prototype, the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure (spectral stochastic process) is constructed on trajectories taking values in the

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

276

Spectral stochastic processes arising in quantum mechanical models with a non-L2 ground state

A functional integral representation is given for a large class of quantum mechanical models with a non-L2 ground state. As a prototype the particle in a periodic potential is discussed: a unique ground state is shown to exist as a state on the Weyl algebra, and a functional measure (spectral stochastic process) is constructed on trajectories taking values in the

J. Loffelholz; G. Morchio; F. Strocchi

1994-01-01

277

Testing quantum electrodynamics in the lowest singlet states of beryllium atom

High-precision results are reported for the energy levels of $2{^1S}$ and $2{^1P}$ states of the beryllium atom. Calculations are performed using fully correlated Gaussian basis sets and taking into account the relativistic, quantum electrodynamics (QED), and finite nuclear mass effects. Theoretical predictions for the ionization potential of the beryllium ground state $75\\,192.699(7) \\icm$ and the $2{^1P} \\rightarrow 2{^1S}$ transition energy $42\\,565.441(11) \\icm$ are compared to the known but less accurate experimental values. The accuracy of the four-electron computations approaches that achieved for the three-electron atoms, which enables determination of the nuclear charge radii and precision tests of QED.

Puchalski, Mariusz; Komasa, Jacek

2013-01-01

278

Preparing ground states and squeezed states of nanomechanical cantilevers by fast dissipation

NASA Astrophysics Data System (ADS)

We propose a protocol that enables strong coupling between a flux qubit and the quantized motion of a magnetized nanomechanical cantilever. The flux qubit is driven by microwave fields with suitable parameters to induce sidebands, which will lead to the desired coupling. We show that the nanomechanical modes can be cooled to the ground states and the single-mode squeezed vacuum states can be generated via fast dissipation of the flux qubit. In our scheme, the qubit decay plays a positive role and can help drive the system to the target states.

Wang, Xin; Li, Hong-rong; Li, Peng-bo; Jiang, Chen-wei; Gao, Hong; Li, Fu-li

2014-07-01

279

Theoretical studies of the first-row transition metals: Ground state and thermal properties

NASA Astrophysics Data System (ADS)

Theoretical studies of the ground state properties of the first-row transition metals (Sc to Zn) are conducted using the Stuttgart TB-LMTO ESC program. The standard deviation of the calculation precision errors (CPE's) and the magnitude of the systematic calculation errors (SCE's) in the output of the TB-LMTO ESC program are estimated. The ground state lattice parameters, local atomic magnetic moment magnitudes and bulk moduli of the first-row transition metals are calculated. Lattice parameters are found to be within 5% to 10% of experimental values, and magnetic moment magnitudes are found to be within 10% to 20% of experimental values. Bulk moduli are found to be within 60% of experimental values. Lattice parameter and magnetic moment magnitude calculations are most accurate when the non-local exchange-correlation functional of Hu and Langreth is used. Bulk modulus calculations are most accurate when conducted using the exchange-correlation functional of Perdew and Yue. The TB-LMTO ESC program is also used to study the volume-controlled low-moment to high-moment (LM-HM) transition of the first-row transition metals (Sc to Ni) when they are constrained to take the FCC crystal structure. A LM-HM transition is predicted to occur in all FCC first-row transition metals if their lattice parameter is sufficiently increased. FCC Fe is found to occupy a unique position in the first-row transition metal series, as its LM-HM transition occurs when its lattice parameter is less than 2.5% larger than its ground state value. The LM-HM transition of the other FCC first-row transition metals occur when their lattice parameters are much larger or much smaller than their ground state values. It is argued that when the lattice parameters of the FCC first-row transition metals are too small, the energy bands of their valence electrons are too wide to allow magnetic moments to form within these metals. A method is proposed for calculating the Helmholtz' free energy of non-magnetic, bulk, crystalline solids consisting of a single chemical species. The method assumes only that an inter-atomic interaction potential can be derived from the minimum total energy versus lattice parameter curve of a solid using results published by Chen, Chen and Wei, and that this potential can accurately reproduce the energy increase that occurs when the atomic nuclei of the solid move away from their equilibrium positions as they undergo small amplitude thermal oscillations. The method is entirely theoretical as the minimum total energy versus lattice parameter curve of a solid can be calculated entirely from first principles using an ESC program. Within the method, the atomic nuclei of a solid are treated in a quasi-harmonic approximation, either as independent harmonic oscillators, or as coupled harmonic oscillators. The thermal expansion of metallic Cu is studied using the proposed method for calculating the Helmholtz' free energy of solids in conjunction with the TB-LMTO ESC program. The lattice parameter versus temperature curve of metallic Cu can be accurately calculated using the method, but its accuracy is sensitive to the functional form of the calculated minimum total energy versus lattice parameter curve of FCC Cu and to the range of the inter-atomic interaction potential. The results of these calculations suggest that the range of the inter-atomic interaction potential extends only to first nearest neighbour atomic nuclei in the metallic Cu solid. These results also suggest that the curvature of the minimum total energy versus lattice parameter curve of FCC Cu is most accurate when the curve is calculated using the exchange-correlation functional of Perdew and Yue even though the ground state lattice parameter of metallic Cu is most accurately predicted using the exchange-correlation functional of Hu and Langreth. However, it may be that imposing a short range to the inter-atomic interaction potential and that using the minimum total energy versus lattice parameter curve obtained with the exchange-correlation functional of Perdew and Yue simply bet

Prevost, Jean-Paul L.

280

Initial results from ground-based testing of an atomic oxygen sensor designed for use in earth orbit

Many sensors have been applied to the problem of measuring neutral atomic oxygen fluxes in low Earth orbit. The techniques used to date tend to suffer from several key disadvantages, variously: large mass and power budgets, large size, high cost, the ability to make only one measurement and poor time resolution. In this article preliminary results from ground-based testing of

J. J. Osborne; G. T. Roberts; A. R. Chambers; S. B. Gabriel

1999-01-01

281

Probing ground and low-lying excited states for HIO2 isomers

NASA Astrophysics Data System (ADS)

We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10-3).

de Souza, Gabriel L. C.; Brown, Alex

2014-12-01

282

Probing ground and low-lying excited states for HIO2 isomers.

We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10(-3)). PMID:25527931

de Souza, Gabriel L C; Brown, Alex

2014-12-21

283

Ground-state coding in partially connected neural networks

NASA Technical Reports Server (NTRS)

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.

Baram, Yoram

1989-01-01

284

Arsenic in Ground-Water Resources of the United States

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.

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

2000-01-01

285

Regularities in molecular properties of ground state stable diatomics

NASA Astrophysics Data System (ADS)

A simple relationship is reported between vibrational frequencies, bond lengths, and reduced masses for many families of stable, ground state diatomics: the frequency is proportional to the reciprocal of the product of the bond length and the square root of the reduced mass. This is demonstrated with each of the following related families: the alkali metal diatomics, the group 15 diatomics, the group 16 diatomics, the halogen diatomics, the alkali metal hydrides, the alkaline earth oxides, the group 14 oxides and their sulfides, the diatomics of carbon, of silicon and of germanium with group 16 elements, the hydrogen halides, the halides of lithium, of sodium, of potassium, of rubidium and of cesium, the chlorides of the alkali metals and of silver, and the polyatomic hydrides of groups 14 and 15. Although correlation coefficients of 0.99 or greater in each of the 21 families examined demonstrate the validity of the correlation, the deviations found are significantly larger than can be attributed to experimental uncertainties.

Zavitsas, Andreas A.

2004-06-01

286

Classifying and measuring geometry of a quantum ground state manifold

NASA Astrophysics Data System (ADS)

From the Aharonov-Bohm effect to general relativity, geometry plays a central role in modern physics. In quantum mechanics, many physical processes depend on the Berry curvature. However, recent advances in quantum information theory have highlighted the role of its symmetric counterpart, the quantum metric tensor. In this paper, we perform a detailed analysis of the ground state Riemannian geometry induced by the metric tensor, using the quantum XY chain in a transverse field as our primary example. We focus on a particular geometric invariant, the Gaussian curvature, and show how both integrals of the curvature within a given phase and singularities of the curvature near phase transitions are protected by critical scaling theory. For cases where the curvature is integrable, we show that the integrated curvature provides a new geometric invariant, which like the Chern number characterizes individual phases of matter. For cases where the curvature is singular, we classify three types (integrable, conical, and curvature singularities) and detail situations where each type of singularity should arise. Finally, to connect this abstract geometry to experiment, we discuss three different methods for measuring the metric tensor: via integrating a properly weighted noise spectral function or by using leading-order responses of the work distribution to ramps and quenches in quantum many-body systems.

Kolodrubetz, Michael; Gritsev, Vladimir; Polkovnikov, Anatoli

2013-08-01

287

Ground-state properties of neutron-rich Mg isotopes

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 ?ne-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 defor...

Watanabe, Shin; Shimada, Mitsuhiro; Tagami, Shingo; Kimura, Masaaki; Takechi, Maya; Fukuda, Mitsunori; Nishimura, Daiki; Suzuki, Takeshi; Matsumoto, Takuma; Shimizu, Yoshifumi R; Yahiro, Masanobu

2014-01-01

288

States of antimony and tin atoms in lead chalcogenides

It is shown by Moessbauer spectroscopy of the {sup 119}Sb({sup 119m}Sn) isotope that impurity antimony atoms in PbS, PbSe, and PbTe lattices are distributed between cation and anion sublattices. In n-type samples, the greatest part of antimony is located in the anion sublattice; in hole ones, in the cation sublattice. The tin atoms formed as a result of radioactive decay of {sup 119}Sb (antisite state) are electrically inactive in the anion sub-lattice of PbS and PbSe, while, in the cation sublattice, they form donor U{sup -} centers. Electron exchange between the neutral and doubly ionized tin U{sup -} centers via the allowed band states is observed. The tin atoms formed after radioactive decay of {sup 119}Sb are electrically inactive in the anion and cation sublattices of PbTe.

Bordovsky, G. A. [Herzen State Pedagogical University (Russian Federation); Nemov, S. A. [St. Petersburg State Polytechnical University (Russian Federation); Marchenko, A. V.; Zaiceva, A. V.; Kozhokar, M. Yu.; Seregin, P. P., E-mail: ppseregin@mail.ru [Herzen State Pedagogical University (Russian Federation)

2011-04-15

289

Ground Water Quality Protection. State and Local Strategies.

ERIC Educational Resources Information Center

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…

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

290

Positron spectroscopy in atomic and solid state physics

Basic research problems in Atomic Physics with positrons (total cross sections, Ramsauer minima, positronium formation, selective ionization) and some benchmark measurements in Solid State Physics using positron annihilation (He-created nano-voids in Si, Oxygen precipitates in Si, low ? materials) are discussed.

G. P. Karwasz; R. S. Brusa; A. Zecca

2003-01-01

291

ccsd00002401, Teleportation of an atomic ensemble quantum state

, needs two simultaneous measurements to achieve real-time quantum telepor- tation, and can easily is well- adapted. They interact with a coherent control #12;eld i and with a vacuum #12;eld A i . During quasiperfect quantum state transfer processes between light and atoms. Our protocol relies on optical joint

292

We consider the semi-relativistic Pauli-Fierz Hamiltonian and a no-pair model of a hydrogen-like atom interacting with a quantized photon field at the respective critical values of the Coulomb coupling constant. For arbitrary values of the fine-structure constant and the ultra-violet cutoff, we prove the existence of normalizable ground states of the atomic system in both models. This complements earlier results on the existence of ground states in (semi-)relativistic models of quantum electrodynamics at sub-critical coupling by E. Stockmeyer and the present authors. Technically, the main new achievement is an improved estimate on the spatial exponential localization of low-lying spectral subspaces yielding uniform bounds at large Coulomb coupling constants. In the semi-relativistic Pauli-Fierz model our exponential decay rate given in terms of the binding energy reduces to the one known from the electronic model when the radiation field is turned off. In particular, an increase of the binding energy due to the radiation field is shown to improve the localization of ground states.

Martin Könenberg; Oliver Matte

2012-04-16

293

Derivation of novel human ground state naive pluripotent stem cells.

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 GSK3? 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 of cross-species chimaeric mouse embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. PMID:24172903

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

294

Robustness of fractional quantum Hall states with dipolar atoms in artificial gauge fields

The robustness of fractional quantum Hall states is measured as the energy gap separating the Laughlin ground state from excitations. Using thermodynamic approximations for the correlation functions of the Laughlin state and the quasihole state, we evaluate the gap in a two-dimensional system of dipolar atoms exposed to an artificial gauge field. For Abelian fields, our results agree well with the results of exact diagonalization for small systems but indicate that the large value of the gap predicted [Phys. Rev. Lett. 94, 070404 (2005)] was overestimated. However, we are able to show that the small gap found in the Abelian scenario dramatically increases if we turn to non-Abelian fields squeezing the Landau levels.

Grass, T. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Baranov, M. A. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); RRC ''Kurchatov Institute,'' Kurchatov Square 1, 123182 Moscow (Russian Federation); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)

2011-10-15

295

Electro-optic control of atom-light interactions using Rydberg dark-state polaritons

NASA Astrophysics Data System (ADS)

We demonstrate a multiphoton Rydberg dark resonance where a ? system is coupled to a Rydberg state. This N -type level scheme combines the ability to slow and store light pulses associated with long-lived ground-state superpositions with the strongly interacting character of Rydberg states. For the nd5/2 Rydberg state in R87b (with n=26 or 44) and a beam size of 1 mm, we observe a resonance linewidth of less than 100 kHz in a room-temperature atomic ensemble limited by transit-time broadening. The resonance is switchable with an electric field of order 1Vcm-1 . Applications in electro-optic switching and photonic phase gates are discussed.

Bason, M. G.; Mohapatra, A. K.; Weatherill, K. J.; Adams, C. S.

2008-03-01

296

XUV frequency-comb metrology on the ground state of helium

The operation of a frequency comb at extreme ultraviolet (xuv) wavelengths based on pairwise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency-comb laser in the near-infrared range is reported. It is experimentally demonstrated that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p {sup 1} P{sub 1} states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited-state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium atom as a precision phase ruler, yields an estimated timing jitter between the two upconverted-comb laser pulses of 50 attoseconds, which is equivalent to a phase jitter of 0.38 (6) cycles in the xuv at 51 nm. This sets a quantitative figure of merit for the operation of the xuv comb and indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5 740 806 993 (10) and 5 814 248 672 (6) MHz for excitation of the 1s4p and 1s5p {sup 1} P{sub 1} states, respectively. This constitutes an important frequency measurement in the xuv, attaining high accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold-improved {sup 4}He ionization energy of 5 945 204 212 (6) MHz is derived. Also, a new value for the {sup 4}He ground-state Lamb shift is found of 41 247 (6) MHz. This experimental value is in agreement with recent theoretical calculations up to order m{alpha}{sup 6} and m{sup 2}/M{alpha}{sup 5}, but with a six-times-higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.

Kandula, Dominik Z.; Gohle, Christoph; Pinkert, Tjeerd J.; Ubachs, Wim; Eikema, Kjeld S. E. [LaserLaB Amsterdam, VU University, De Boelelaan 1081, NL-1081HV Amsterdam (Netherlands)

2011-12-15

297

Ground states and dynamics of rotating Bose-Einstein condensates

Since its realization in dilute bosonic atomic gases [7], [23], Bose-Einstein condensation of alkali atoms and hydrogen has been produced and studied extensively in the laboratory [1], and has permitted an intriguing glimpse into the macroscopic quantum world. In view of potential applications [38], [61], [63], the study of quantized vortices, which are well-known signatures of superfluidity, is one of

Weizhu Bao

298

Dressed states for a multilevel atom and localized field in a photonic band-gap crystal

An excited atom in a photonic band-gap crystal can emit a photon that is then reabsorbed and reemitted by the atom, to form a dressed atom-field state. We discuss the existence conditions for such a trapped photon dressed state with a general multilevel atom driven by coherent fields and show that more than one such trapped state can exist. The

Hu Huang; Xing-Hua Lu; Shi-Yao Zhu

1998-01-01

299

From rotating atomic rings to quantum Hall states.

Considerable efforts are currently devoted to the preparation of ultracold neutral atoms in the strongly correlated quantum Hall regime. However, the necessary angular momentum is very large and in experiments with rotating traps this means spinning frequencies extremely near to the deconfinement limit; consequently, the required control on parameters turns out to be too stringent. Here we propose instead to follow a dynamic path starting from the gas initially confined in a rotating ring. The large moment of inertia of the ring-shaped fluid facilitates the access to large angular momenta, corresponding to giant vortex states. The trapping potential is then adiabatically transformed into a harmonic confinement, which brings the interacting atomic gas in the desired quantum-Hall regime. We provide numerical evidence that for a broad range of initial angular frequencies, the giant-vortex state is adiabatically connected to the bosonic ? = 1/2 Laughlin state. PMID:22355562

Roncaglia, M; Rizzi, M; Dalibard, J

2011-01-01

300

From rotating atomic rings to quantum Hall states

Considerable efforts are currently devoted to the preparation of ultracold neutral atoms in the strongly correlated quantum Hall regime. However, the necessary angular momentum is very large and in experiments with rotating traps this means spinning frequencies extremely near to the deconfinement limit; consequently, the required control on parameters turns out to be too stringent. Here we propose instead to follow a dynamic path starting from the gas initially confined in a rotating ring. The large moment of inertia of the ring-shaped fluid facilitates the access to large angular momenta, corresponding to giant vortex states. The trapping potential is then adiabatically transformed into a harmonic confinement, which brings the interacting atomic gas in the desired quantum-Hall regime. We provide numerical evidence that for a broad range of initial angular frequencies, the giant-vortex state is adiabatically connected to the bosonic ? = 1/2 Laughlin state. PMID:22355562

Roncaglia, M.; Rizzi, M.; Dalibard, J.

2011-01-01

301

Some Correlation Functions in Matrix Product Ground States of One-Dimensional Two-State Chains

NASA Astrophysics Data System (ADS)

Consider one-dimensional chains with nearest neighbour interactions, for which to each site correspond two independent states (say up and down), and the ground state is a matrix product state. It has been shown [23] that for such systems, the ground states are linear combinations of specific vectors which are essentially direct products of specific numbers of ups and downs, symmetrized in a generalized manner. By a generalized manner, it is meant that the coefficient corresponding to the interchange of states of two sites, in not necessarily plus one or minus one, but a phase which depends on the Hamiltonian and the position of the two sites. Such vectors are characterized by a phase ?, the N-th power of which is one (where N is the number of sites), and an integer. Corresponding to ?, there is another integer M which is the smallest positive integer that ?M is one. Two classes of correlation functions for such systems (basically correlation functions for such vectors) are calculated. The first class consists of correlation functions of tensor products of one-site diagonal observables; the second class consists of correlation functions of tensor products of less than M one-site observables (but not necessarily diagonal).

Shariati, Ahmad; Aghamohammadi, Amir; Fatollahi, Amir H.; Khorrami, Mohammad

2014-04-01

302

Triviality of the Ground State Structure in Ising Spin Glasses Matteo Palassini and A. P. Young

state in three dimensions we use a hybrid genetic algorithm introduced by Pal 20;21 . Starting from there are efficient algorithms for determining ground states, even though P (q) is trivial in this limit (for a con

Young, A. Peter

303

Nonmetal ordering in TiC1-xNx : Ground-state structure and the effects of finite temperature

NASA Astrophysics Data System (ADS)

The TiC1-xNx system has long been prized in industry because of its desirable thermodynamic and hardness characteristics. Previous studies have not produced comprehensive results describing the ordering tendencies of TiC1-xNx at any temperature. We apply the mixed-basis cluster expansion and Monte Carlo methods to the problem and find a fascinating array of ground-state structures occurring at precise nitrogen-concentration intervals of ?x=1/16 and related to each other by simple (201) quasisuperlattice motifs. Thermodynamic Monte Carlo results indicate that the critical ordering temperatures at all concentrations are well below room temperature. Short-range ordering develops at T?800K and exhibits the characteristic motifs of the predicted ground-state structures. Bulk modulus optimization is not feasible since this quantity shows little sensitivity to atomic configuration.

Kolb, Brian; Hart, Gus L. W.

2005-12-01

304

GROUND WATER MANAGEMENT IN THE SOUTHEASTERN UNITED STATES

This study characterizes current and potential ground-water resource problems in North and South Carolina, Georgia, Florida, Alabama, Mississippi, Tennessee, and Kentucky. It discusses those issues that could constrain development or adversely affect environmental quality or huma...

305

Finding Ground States of Sherrington-Kirkpatrick Spin Glasses with Hierarchical BOA and Genetic- erarchical Bayesian optimization algorithm (hBOA) to reli- ably identify ground states of SK instances. Performance of hBOA is compared to that of the genetic algorithm with two common crossover operators

Kobe, Sigismund

306

Ground states of a ternary fcc lattice model with nearest- and next-nearest-neighbor interactions

The possible ground states of a ternary fcc lattice model with nearest- and next-nearest-neighbor pair interactions are investigated by constructing an eight-dimensional configuration polytope and enumerating its vertices. Although a structure could not be constructed for most of the vertices, 31 ternary ground states are found, some of which correspond to structures that have been observed experimentally.

G. Ceder; G. D. Garbulsky; D. Avis; K. Fukuda

1994-01-01

307

Scaling of ground motion parameters, state of stress, and focal depth

The ground motion parameters Rv and rhoRa, where R is hypocentral distance, v is peak velocity, rho is density, and a is peak acceleration, are found observationally to be strong functions of stress state and linearly related to focal depth z. If the stress state and focal depth are properly taken into account, then the ground motion parameters depend on

A. McGarr

1984-01-01

308

Reformulation of the covering and quantizer problems as ground states of interacting particles S of the ground states of interacting particles in Rd that generally involve single-body, two-body, three optimization problems involving the "void" nearest-neighbor functions that arise in the theory of random media

Torquato, Salvatore

309

The variational principle and simple properties of the ground-state wave function

The variational principle is used to show that the ground-state wave function of a one-body Schrödinger equation with a real potential is real, does not change sign, and is nondegenerate. As a consequence, if the Hamiltonian is invariant under rotations and parity transformations, the ground state must have positive parity and zero angular momentum.

J. Mur-Petit; A. Polls; F. Mazzanti

2002-01-01

310

Initial results from ground-based testing of an atomic oxygen sensor designed for use in earth orbit

NASA Astrophysics Data System (ADS)

Many sensors have been applied to the problem of measuring neutral atomic oxygen fluxes in low Earth orbit. The techniques used to date tend to suffer from several key disadvantages, variously: large mass and power budgets, large size, high cost, the ability to make only one measurement and poor time resolution. In this article preliminary results from ground-based testing of a novel atomic oxygen sensor based on a semiconducting metal oxide are reported. Such sensors are simple and relatively cheap while also requiring small power and mass budgets and, most importantly, are reusable. The sensors have been used in laboratory experiments to investigate the axial variation of atomic oxygen flux in a pulsed laser atomic oxygen source; the results compare well with readings taken with a carbon-coated quartz crystal microbalance. A small instrument based on these sensors has been designed and built for application on the UK's STRV-1c microsatellite.

Osborne, J. J.; Roberts, G. T.; Chambers, A. R.; Gabriel, S. B.

1999-05-01

311

Potential energy curves for the ground and low-lying excited states of CuAg.

The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding ? components correlating with the separated atom limits (2)S(Cu) + (2)S(Ag) and (2)D(Cu) + (2)S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0(+) state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results. PMID:25338890

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-21

312

NASA Astrophysics Data System (ADS)

We introduce a class of spin models with long-range interactions—in the sense that they extend significantly beyond their nearest neighbors—whose ground states can be constructed analytically and that have a simple matrix product state representation. This enables the detailed study of ground state properties, such as correlation functions and entanglement, in the thermodynamic limit. The spin models presented here are closely related to lattice gases of strongly interacting polar molecules, or Rydberg atoms that feature an excluded volume or blockade interaction. While entanglement is only present between spins that are separated by no more than a blockade length, we show that non-classical correlations can extend much further, and we analyze them through quantum discord. We furthermore identify a set of seemingly critical points where the ground state approaches a crystalline state with a filling fraction that is given by the inverse of the blockade length. We analyze the scaling properties in the vicinity of this parameter region and show that the correlation length possesses a non-trivial dependence on the blockade length.

Levi, E.; Lesanovsky, I.

2014-09-01

313

NASA Astrophysics Data System (ADS)

We show theoretically that it is possible to create and manipulate a pair of bound states in the continuum in ultracold atoms by two lasers in the presence of a magnetically tunable Feshbach resonance. These bound states are formed due to coherent superposition of two electronically excited molecular bound states and a quasibound state in the ground-state potential. These superposition states are decoupled from the continuum of two-atom collisional states. Hence, in the absence of other damping processes they are nondecaying. We analyze in detail the physical conditions that can lead to the formation of such states in cold collisions between atoms and discuss the possible experimental signatures of such states. An extremely narrow and asymmetric shape with a distinct minimum of the photoassociative absorption spectrum or the scattering cross section as a function of collision energy will indicate the occurrence of a bound state in the continuum (BIC). We prove that the minimum will occur at the energy at which the BIC is formed. We discuss how a BIC will be useful for efficient the creation of Feshbach molecules and manipulation of cold collisions. Experimental realizations of BIC will pave the way for a new kind of bound-bound spectroscopy in ultracold atoms.

Deb, Bimalendu; Agarwal, G. S.

2014-12-01

314

Atomic homodyne detection of continuous-variable entangled twin-atom states.

Historically, the completeness of quantum theory has been questioned using the concept of bipartite continuous-variable entanglement. The non-classical correlations (entanglement) between the two subsystems imply that the observables of one subsystem are determined by the measurement choice on the other, regardless of the distance between the subsystems. Nowadays, continuous-variable entanglement is regarded as an essential resource, allowing for quantum enhanced measurement resolution, the realization of quantum teleportation and quantum memories, or the demonstration of the Einstein-Podolsky-Rosen paradox. These applications rely on techniques to manipulate and detect coherences of quantum fields, the quadratures. Whereas in optics coherent homodyne detection of quadratures is a standard technique, for massive particles a corresponding method was missing. Here we report the realization of an atomic analogue to homodyne detection for the measurement of matter-wave quadratures. The application of this technique to a quantum state produced by spin-changing collisions in a Bose-Einstein condensate reveals continuous-variable entanglement, as well as the twin-atom character of the state. Our results provide a rare example of continuous-variable entanglement of massive particles. The direct detection of atomic quadratures has applications not only in experimental quantum atom optics, but also for the measurement of fields in many-body systems of massive particles. PMID:22139418

Gross, C; Strobel, H; Nicklas, E; Zibold, T; Bar-Gill, N; Kurizki, G; Oberthaler, M K

2011-12-01

315

Heralded generation of Bell states using atomic ensembles

NASA Astrophysics Data System (ADS)

We propose a scheme that utilizes the collective enhancement of a photonic mode inside an atomic ensemble together with a proper Zeeman manifold to achieve a heralded polarization entangled Bell state. The entanglement is between two photons that are separated in time and can be used as a postselected deterministic source for applications such as quantum repeaters where a subsequent entanglement swapping measurement is employed. We present a detailed analysis of the practical limitation of the scheme.

Shwa, David; Cohen, Raphael D.; Retzker, Alex; Katz, Nadav

2013-12-01

316

NASA Astrophysics Data System (ADS)

As a representative lanthanide endohedral metallofullerene, Gd@C82 has attracted a widespread attention among theorists and experimentalists ever since its first synthesis. Through comprehensive comparisons and discussions, as well as references to the latest high precision experiments, we evaluated the performance of different computational methods. Our results showed that the appropriate choice of the exchange-correlation functionals is the decisive factor to accurately predict both geometric and electronic structures for Gd@C82. The electronic structure of the ground state and energy gap between the septet ground state and the nonet low-lying state obtained from pure density functional methods, such as PBE and PW91, are in good agreement with current experiment. Unlike pure functionals, the popularly used hybrid functionals in previous studies, such as B3LYP, could infer the qualitative correct ground state only when small basis set for C atoms is employed. Furthermore, we also highlighted that other geometric structures of Gd@C82 with the Gd staying at different positions are either not stable or with higher energies. This work should provide some useful references for various theoretical methodologies in further density functional studies on Gd@C82 and its derivatives in the future.

Dai, Xing; Gao, Yang; Xin, Minsi; Wang, Zhigang; Zhou, Ruhong

2014-12-01

317

Ground state of small mixed helium and spin-polarized tritium clusters: a quantum Monte Carlo stud

We report results for the ground-state energy and structural properties of\\u000asmall $^4$He-T$\\\\downarrow$ clusters consisting of up to 4 T$\\\\downarrow$ and 8\\u000a$^4$He atoms. These results have been obtained using very well-known\\u000a$^4$He-$^4$He and T$\\\\downarrow$-T$\\\\downarrow$ interaction potentials and\\u000aseveral models for the $^4$He-T$\\\\downarrow$ interatomic potential. All the\\u000acalculations have been performed with variational and diffusion Monte Carlo\\u000amethods. It takes

P. Stipanovi?; L. Vranjevs Marki?; J. Boronat; B. Kevzi?

2010-01-01

318

Ionization potential for excited S states of the lithium atom

Nonrelativistic, relativistic, quantum electrodynamic, and finite nuclear mass corrections to the energy levels are obtained for the nS{sub 1/2},n=3,...,9 states of the lithium atom. Computational approach is based on the explicitly correlated Hylleraas functions with the analytic integration and recursion relations. Theoretical predictions for the ionization potential of nS{sub 1/2} states and transition energies nS{sub 1/2{yields}}2S{sub 1/2} are compared to known experimental values for {sup 6,7}Li isotopes.

Puchalski, M. [Faculty of Physics, University of Warsaw, Hoza 69, PL-00681 Warsaw (Poland); Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60780 Poznan (Poland); KePdziera, D. [Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, PL-87100 Torun (Poland); Pachucki, K. [Faculty of Physics, University of Warsaw, Hoza 69, PL-00681 Warsaw (Poland)

2010-12-15

319

Yang-Mills Ground State in 2+1 Dimensions and Temporal Gauge

A gauge-invariant wavefunctional is proposed as an approximation to the ground state of Yang-Mills theory in 2+1 dimensions, quantized in temporal gauge. The proposed vacuum state is the true ground state of the appropriate Hamiltonian in both the free-field limit, and in a zero mode strong-field limit. Confinement, in this approach, arises via dimensional reduction, and we present numerical results for the mass gap. The issue of color screening is briefly discussed.

J. Greensite; S. Olejnik

2007-09-14

320

Characterization of ground state entanglement by single-qubit operations and excitation energies

We consider single-qubit unitary operations and study the associated excitation energies above the ground state of interacting quantum spins. We prove that there exists a unique operation such that the vanishing of the corresponding excitation energy determines a necessary and sufficient condition for the separability of the ground state. We show that the energy difference associated to factorization exhibits a monotonic behavior with the one-tangle and the entropy of entanglement, including non analiticity at quantum critical points. The single-qubit excitation energy thus provides an independent, directly observable characterization of ground state entanglement, and a simple relation connecting two universal physical resources, energy and nonlocal quantum correlations.

Giampaolo, S M; Illuminati, F; Verrucchi, P; Giampaolo, Salvatore M.; Illuminati, Fabrizio; Siena, Silvio De; Verrucchi, Paola

2006-01-01

321

NASA Astrophysics Data System (ADS)

Ground state cooling of massive mechanical objects remains a difficult task restricted by the unresolved mechanical sidebands. We propose an optomechanically-induced-transparency cooling scheme to achieve ground state cooling of mechanical motion without the resolved sideband condition in a pure optomechanical system with two mechanical modes coupled to the same optical cavity mode. We show that ground state cooling is achievable for sideband resolution ? m/? as low as ˜ 0.003. This provides a new route for quantum manipulation of massive macroscopic devices and high-precision measurements.

Liu, Yong-Chun; Xiao, Yun-Feng; Luan, Xingsheng; Wong, Chee Wei

2015-01-01

322

Bulk-edge correspondence of entanglement spectrum in two-dimensional spin ground states

NASA Astrophysics Data System (ADS)

General local spin S ground states, described by a valence bond solid (VBS) on a two-dimensional lattice are studied. The norm of these ground states is mapped to a classical O(3) model on the same lattice. Using this quantum-to-classical mapping, we obtain the partial density matrix ?A associated with a subsystem A of the original ground state. We show that the entanglement spectrum of ?A in a translation invariant lattice is related with the spectrum of a quantum XXX Heisenberg model and all its conserved charges on the boundary of the region A.

Santos, Raul A.

2013-01-01

323

Time-resolved probing of the ground state coherence in rubidium

NASA Astrophysics Data System (ADS)

We demonstrate the preparation and probing of the coherence between the hyperfine ground states |S1/2,F=1> and |5S1/2,F=2> of the Rb87 isotope. The effects of various coherence control techniques, i.e., fractional stimulated Raman adiabatic passage and coherent population return, on the coherence are investigated. These techniques are implemented using nearly degenerate pump and Stokes lasers at 795 nm (Rb D1 transition), which couple the two hyperfine ground states via the excited state |5P1/2,F=1> through a resonant two-photon process in which a coherent superposition of the two hyperfine ground states is established. The medium is probed by an additional weak laser, which generates a four-wave mixing signal proportional to the ground state coherence and allows us to monitor its evolution in time. The experimental data are compared with numerical simulations.

Oberst, Martin; Vewinger, Frank; Lvovsky, A. I.

2007-06-01

324

Time-resolved probing of the ground state coherence in rubidium.

We demonstrate the preparation and probing of the coherence between the hyperfine ground states |S(1/2),F=1> and |5S(1/2),F=2> of the Rb87 isotope. The effects of various coherence control techniques, i.e., fractional stimulated Raman adiabatic passage and coherent population return, on the coherence are investigated. These techniques are implemented using nearly degenerate pump and Stokes lasers at 795 nm (Rb D1 transition), which couple the two hyperfine ground states via the excited state |5P(1/2),F=1> through a resonant two-photon process in which a coherent superposition of the two hyperfine ground states is established. The medium is probed by an additional weak laser, which generates a four-wave mixing signal proportional to the ground state coherence and allows us to monitor its evolution in time. The experimental data are compared with numerical simulations. PMID:17572770

Oberst, Martin; Vewinger, Frank; Lvovsky, A I

2007-06-15

325

Efficient sympathetic motional ground-state cooling of a molecular ion

Cold molecular ions are promising candidates in various fields ranging from precision spectroscopy and test of fundamental physics to ultra-cold chemistry. Control of internal and external degrees of freedom is a prerequisite for many of these applications. Motional ground state cooling represents the starting point for quantum logic-assisted internal state preparation, detection, and spectroscopy protocols. Robust and fast cooling is crucial to maximize the fraction of time available for the actual experiment. We optimize the cooling rate of ground state cooling schemes for single $^{25}\\mathrm{Mg}^{+}$ ions and sympathetic ground state cooling of $^{24}\\mathrm{MgH}^{+}$. In particular, we show that robust cooling is achieved by combining pulsed Raman sideband cooling with continuous quench cooling. Furthermore, we experimentally demonstrate an efficient strategy for ground state cooling outside the Lamb-Dicke regime.

Wan, Yong; Wolf, Fabian; Schmidt, Piet O

2015-01-01

326

Manipulating Frequency-Bin Entangled States in Cold Atoms

Optical manipulation of entanglement harnessing the frequency degree of freedom is important for encoding of quantum information. We here devise a phase-resonant excitation mechanism of an atomic interface where full control of a narrowband single-photon two-mode frequency entangled state can be efficiently achieved. We illustrate the working physical mechanism for an interface made of cold 87Rb atoms where entanglement is well preserved from degradation over a typical 100??m length scale of the interface and with fractional delays of the order of unity. The scheme provides a basis for efficient multi-frequency and multi-photon entanglement, which is not easily accessible to polarization and spatial encoding. PMID:24487523

Zavatta, A.; Artoni, M.; Viscor, D.; La Rocca, G.

2014-01-01

327

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

2013-01-01

328

Optically detected nuclear resonance of excited and ground states of YPO 4:Pr 3+

NASA Astrophysics Data System (ADS)

The hyperfine structure and nuclear magnetic moments of Pr 3+:YPO 4 in the ground state and lowest component of the 1D 2 excited state have been measured using laser holeburning and optically detected nuclear resonance. For the ground state, the quadrupole coupling constants are Dg=3.079 MHz, ?<0.01 and the magnetic splitting factors ?g|/2 ?=2.308 kHz/ G, ?g?/2 ?=5.41 kHz/ G. The corresponding excited state values are De=2.272 MHz, ?<0.002 and?e|/2 ?=1.42 kHz / G, ?e?/2 ?=1.72 kHz/ G. Model calculations of the splitting factors assuming pure 4f 2 electron states agree well with the ground state values but rather poorly with those in the excited state.

Shelby, R. M.; Burum, D. P.; Macfarlane, R. M.

1984-12-01

329

Rayleigh scattering from n=3 states of hydrogenlike atoms

NASA Astrophysics Data System (ADS)

An exact analytic evaluation of the Kramers-Heisenberg matrix elements for Rayleigh scattering from n=3 states of hydrogenlike atoms is performed in the nonrelativistic dipole approximation, using the Green's function method. The results are given separately for each subshell. The possibility of 3 s?3 d transitions is also considered. The dependence on the photon energy is contained in six invariant amplitudes. The formulas needed for the evaluation of the various cross sections are presented. The numerical results are contained in tables from which partial and total cross sections can be easily built, covering the energy range from zero up to 20 times the K threshold energy. In the vicinity of Balmer ? frequency the cross section is large and comparable with that for excited n=2 states, confirming an earlier hypothesis of Röhr. At other energies the cross sections for n=2 and n=3 states are comparable, too. The results should be useful in plasma diagnostics.

Florescu, Viorica; Cionga, Aurelia

1985-06-01

330

Relaxation of an unstable state in parametrically excited cold atoms.

We investigate the scaling behavior of the relaxation process for an unstable state near a subcritical Hopf bifurcation point. When the parametric modulation is applied to a magneto-optical trap, the atomic cloud becomes unstable and decays to the dynamic bistable states. Near the subcritical Hopf bifurcation point, we experimentally show that the relaxation process exhibits the scaling behavior; the relaxation time shows a scaling exponent of -1.002 (±0.024). We also present the passage time distribution for the statistical interpretation of the escape process associated with the relaxation of the unstable state. We compare the experimental results to the numerical and analytic results, demonstrating the good agreement between them. PMID:22060485

Moon, Geol; Kim, Yonghee; Heo, Myoung-Sun; Park, Jina; Yum, Dahyun; Lee, Wanhee; Noh, Heung-Ryoul; Jhe, Wonho

2011-09-01

331

States-- Appendix--1 Thermal Methods for Investigating Ground-Water Recharge By Kyle W. Blasch, Jim of hydrologic processes have appeared elsewhere (Stonestrom and Blasch, 2003; Niswonger and Prudic, 2003

332

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

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.

Zhukov, A. E., E-mail: zhukov@beam.ioffe.ru; Maximov, M. V.; Shernyakov, Yu. M. [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation); Livshits, D. A. [Innolume GmbH (Germany); Savelyev, A. V.; Zubov, F. I.; Klimenko, V. V. [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Center (Russian Federation)

2012-02-15

333

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

NASA Technical Reports Server (NTRS)

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.

Jacobi, N.; Zmuidzinas, J. S.

1977-01-01

334

substrate. Removal of the Ser102 alkoxide by mutation to glycine or alanine increases the observed Pi for ground state destabilization. Comparisons of X-ray crystal structures of AP with and without Ser102

Herschlag, Dan

335

Disparity of measured gyromagnetic ratios of ground- and excited-band states in 184 W

Gyromagnetic ratios of levels in the ground-band and of the 22+ state in184W were measured by means of the transient magnetic field perturbed?-ray angular distribution technique. The levels of interest were Coulomb excited by beams of 220-MeV58Ni and63Cu ions. The results show theg-factor of the 22+ state to be approximately half the effectively constant value found for the ground-band levels.

A. E. Stuchbery; H. H. Bolotin; C. E. Doran; A. P. Byrne

1985-01-01

336

Stability of the ground state of a harmonic oscillator in a monochromatic wave

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,

Gennady P. Berman; Daniel F. V. James; Dmitry I. Kamenev

2001-01-01

337

Stability of the ground state of a harmonic oscillator in a monochromatic wave

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,

Gennady P. Berman; Daniel F. V. James; Dimitry I. Kamenev

2001-01-01

338

Magnetic and non-magnetic ground states of the Kondo lattice

We use the variational method to investigate the ground state phase diagram of the Kondo lattice Hamiltonian for arbitraryJ\\/W, and conduction electron concentrationnc (J is the Kondo coupling andW the bandwidth). We are particularly interested in the question under which circumstances the globally singlet (collective Kondo) Fermi liquid type ground state becomes unstable against magnetic ordering. For the collective Kondo

P. Fazekas; E. Müller-Hartmann

1991-01-01

339

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

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.

Jolos, R. V. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Institut fuer Theoretische Physik, Justus-Liebig-Universitaet Giessen, D-35392 Giessen (Germany); Brentano, P. von [Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Cologne (Germany)

2006-12-15

340

LASSP: The Laboratory of Atomic and Solid State Physics

NSDL National Science Digital Library

The Laboratory of Atomic and Solid State Physics (LASSP) at Cornell University is a center for research in condensed matter physics. Scientists can read about the work of the thirty faculty members in topics such as theoretical condensed matter physics, low temperature physics, experimental liquid physics, and experimental soft-condensed matter and biological physics. With a number of images and animations at the website, students can learn about diffraction patterns of an icosahedral quasicrystal, Coarsening, and Spiral Defect Turbulence. Physicists can find employment opportunities at LASSP as well as information on upcoming seminars, conferences, and meetings.

341

Process-chain approach to the Bose-Hubbard model: Ground-state properties and phase diagram

We carry out a perturbative analysis, of high order in the tunneling parameter, of the ground state of the homogeneous Bose-Hubbard model in the Mott insulator phase. This is made possible by a diagrammatic process-chain approach, derived from Kato's representation of the many-body perturbation series, which can be implemented numerically in a straightforward manner. We compute ground-state energies, atom-atom correlation functions, density-density correlations, and occupation number fluctuations, for one-, two-, and three-dimensional lattices with arbitrary integer filling. A phenomenological scaling behavior is found which renders the data almost independent of the filling factor. In addition, the process-chain approach is employed for calculating the boundary between the Mott insulator phase and the superfluid phase with high accuracy. We also consider systems with dimensionalities d>3, thus monitoring the approach to the mean-field limit. The versatility of the method suggests further applications to other systems which are less well understood.

Teichmann, Niklas; Hinrichs, Dennis; Holthaus, Martin; Eckardt, Andre [Institut fuer Physik, Carl von Ossietzky Universitaet, D-26111 Oldenburg (Germany); ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain)

2009-06-01

342

Slow ground state molecules from matrix isolation sublimation

NASA Astrophysics Data System (ADS)

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 A1? u+(v\\prime =4,J\\prime =J\\prime\\prime +1) ?ftarrow X 1? 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.

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

2014-12-01

343

NASA Astrophysics Data System (ADS)

In the first paper of this series [DiStasio, Jr., Marcotte, Car, Stillinger, and Torquato, Phys. Rev. B10.1103/PhysRevB.88.134104 88, 134104 (2013)], we applied inverse statistical-mechanical techniques to study the extent to which targeted spin configurations on the square lattice can be ground states of finite-ranged radial spin-spin interactions. In this sequel, we enumerate all of the spin configurations within a unit cell on the one-dimensional integer lattice and the two-dimensional square lattice up to some modest size under periodic boundary conditions. We then classify these spin configurations into those that can or cannot be unique classical ground states of the aforementioned radial pair spin interactions and found the relative occurrences of these ground-state solution classes for different system sizes. As a result, we also determined the minimal radial extent of the spin-spin interaction potentials required to stabilize those configurations whose ground states are either unique or degenerate (i.e., those sharing the same radial spin-spin correlation function). This enumeration study has established that unique ground states are not limited to simple target configurations. However, we also found that many simple target spin configurations cannot be unique ground states.

Marcotte, Étienne; DiStasio, Robert A., Jr.; Stillinger, Frank H.; Torquato, Salvatore

2013-11-01

344

Exotic Ground States of Directional Pair Potentials via Collective-Density Variables

NASA Astrophysics Data System (ADS)

Collective-density variables have proved to be a useful tool in the prediction and manipulation of how spatial patterns form in the classical many-body problem. Previous work has employed properties of collective-density variables along with a robust numerical optimization technique to find the classical ground states of many-particle systems subject to radial pair potentials in one, two and three dimensions. That work led to the identification of ordered and disordered classical ground states. In this paper, we extend these collective-coordinate studies by investigating the ground states of directional pair potentials in two dimensions. Our study focuses on directional potentials whose Fourier representations are non-zero on compact sets that are symmetric with respect to the origin and zero everywhere else. We choose to focus on one representative set that has exotic ground-state properties: two circles whose centers are separated by some fixed distance. We obtain ground states for this "two-circle" potential that display large void regions in the disordered regime. As more degrees of freedom are constrained the ground states exhibit a collapse of dimensionality characterized by the emergence of filamentary structures and linear chains. This collapse of dimensionality has not been observed before in related studies.

Martis, Stephen; Marcotte, Étienne; Stillinger, Frank H.; Torquato, Salvatore

2013-02-01

345

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

NASA Astrophysics Data System (ADS)

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.

Hida, Kazuo

2014-11-01

346

As stated in the original proposal, the goal of the project has been to perform electron-scattering experiments on a few model systems with emphasis on resolving all the quantum-state variables possible. The purpose of these experimental studies has been to provide a set of measurements of unprecedented accuracy and completeness that can be used as benchmarks for comparison with theoretical calculations. During the period covered by this report, the work has concentrated on measuring low-energy electron scattering from sodium and chromium. Sodium provides an ideal one-electron test case, since it has a single loosely bound valence electron, making it approachable by even the most complex electron scattering calculations. In addition, the atom has a strong optical transition from the 3{sup 2}S{sub 1/2} ground state to the 3{sup 2}P{sub 3/2} excited state whose wavelength (589 nm) matches the peak output of the laser dye rhodamine 6G. Thus optical pumping techniques can be readily applied in the laboratory, leading to either a population of ground state atoms in which the spin of the valence electron is oriented either up or down in the laboratory, or a spin polarized pure angular momentum state of the excited 3{sup 2}P{sub 3/2} state. Such an excited state makes possible superelastic scattering, where the internal energy of the atom is transferred to the electron during the collision. This turns out to be a very efficient way to study the inelastic scattering process. Unlike sodium, chromium provides an extremely exacting test for theoretical methods because of its very complex electronic structure, not because it is simple. With a valence configuration consisting of five electrons in a half-filled 3d shell, plus another electron in a 4s shell, this atom provides a test case that can challenge even the simplest approximations.

Kelley, M.H.; McClelland, J.J.

1998-03-15

347

COLD ATOMS AND CREATION OF NEW STATES OF MATTER: BOSE- EINSTEIN CONDENSATES, KAPITZA STATES, AND '2D MAGNETIC HYDROGEN ATOMS' LENE VESTERGAARD HAU, B. D. BUSCH, CHIEN LIU, MICHAEL M. BURNS, AND J. A, Electronic and Atomic Collisions (Invited papers of the Twentieth International Conference on the Physics

Hau, Lene Vestergaard

348

Unified description of ground and excited states of finite systems: the self-consistent GW approach

NASA Astrophysics Data System (ADS)

Fully self-consistent GW calculations -- based on the iterative solution of the Dyson equation -- provide an approach for consistently describing ground and excited states on the same quantum mechanical level. Based on our implementation in the all-electron localized basis code FHI-aims [1], we show that for finite systems self-consistent GW reaches the same final Green function regardless of the starting point. The results show that self-consistency systematically improves ionization energies and total energies of closed shell systems compared to perturbative GW calculations (G0W0) based on Hartree-Fock or (semi)local density-functional theory. These improvements also translate to the electron density as demonstrated by a better description of the dipole moments of hetero-atomic dimers and the similarity with the coupled cluster singles doubles (CCSD) density. The starting-point independence of the self-consistent Green function facilitates a systematic and unbiased assessment of the performance of the GW approximation for finite systems. It therefore constitutes an unambiguous reference for the future development of vertex corrections and beyond GW schemes. [1] V. Blum et al., Comp. Phys. Comm. 180, 2175 (2009).

Caruso, Fabio; Rinke, Patrick; Ren, Xinguo; Rubio, Angel; Scheffler, Matthias

2012-02-01

349

Neutron polarization analysis study of the frustrated magnetic ground state of ?-Mn1-xAlx

NASA Astrophysics Data System (ADS)

We have performed a neutron polarization analysis study of the short-range nuclear and magnetic correlations present in the dilute alloy, ?-Mn1-xAlx with 0.03?x?0.16 , in order to study the evolution of the magnetic ground state of this system as it achieves static spin-glass order at concentrations x>0.09 . To this end we have developed a reverse-Monte Carlo algorithm which has enabled us to extract Warren-Cowley nuclear short-range order parameters and magnetic spin correlations. Using conventional neutron powder diffraction, we show that the nonmagnetic Al substituents preferentially occupy the magnetic site II Wyckoff positions in the ?-Mn structure—resulting in a reduction of the magnetic topological frustration of the Mn atoms. These Al impurities are found to display strong anticlustering behavior. The magnetic spin correlations are predominantly antiferromagnetic, persisting over a short range which is similar for all the samples studied—above and below the spin-liquid-spin-glass boundary—while the observed static (disordered) moment is shown to increase with increasing Al concentration.

Stewart, J. R.; Andersen, K. H.; Cywinski, R.

2008-07-01

350

Earthquake Ground Motion Simulations in the Central United States

The Central United States (CUS) includes two of the major seismic zones east of the Rockies: the New Madrid and Wabash Valley Seismic Zones. The winter 1811-1812 New Madrid Seismic Zone (NMSZ) events were the largest intraplate sequence ever recorded in the United States. Together with their aftershocks, these earthquakes produced large areas of liquefaction, new lakes, and landslides in

L. Ramirez Guzman; O. S. Boyd; S. Hartzell; R. A. Williams

2010-01-01

351

Slow ground state molecules from matrix isolation sublimation

We describe the generation and properties of a cryogenic beam of $^7$Li$_2$ 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 $^7$Li$_2$ (R) transitions A$^1\\Sigma_u^+(v'=4,J'=J''+1)\\leftarrow $X$^1\\Sigma_g^+ (v''=0,J''=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 10$^9$ 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 funct...

Oliveira, Alvaro N; Alves, Bruno X; Silva, Bruno A; Wolff, Wania; Cesar, Claudio L

2014-01-01

352

The effects of atomic oxygen on boron nitride, silicon nitride, solar cell interconnects used on the Intelsat 6 satellite, organic polymers, and MoS{sub 2} and WS{sub 2} dry lubricant have been studied in low Earth orbit (LEO) flight experiments and in our ground-based simulation facility at Los Alamos National Laboratory. Both the in-flight and ground-based experiments employed in situ electrical resistance measurements to detect penetration of atomic oxygen through materials and ESCA analysis to measure chemical composition changes. In the presence of atomic oxygen, silver oxidizes to form silver oxide, which has a much higher electrical resistance than pure silver. Permeation of atomic oxygen through BN overcoated on thin silver was observed. No permeation of atomic oxygen through Si{sub 3}N{sub 4} was observed. Test results on the Intelsat 6 satellite interconnects used on its photovoltaic array indicate that more than 60--80% of the original thickness of silver should remain after completion of the proposed Space Shuttle rescue/reboost mission. Gas phase reaction products produced by the interaction of high kinetic energy atomic oxygen (AO) with Kapton were found to be H{sub 2}, H{sub 2}O, CO, and CO{sub 2} with NO being a possible secondary product. Hydrogen abstraction at high AO kinetic energy is postulated to be the key reaction controlling the erosion rate of Kapton. An Arrhenius-like expression having an activation barrier of 0.4 eV can be fit to the data, which suggests that the rate limiting step in the AO/Kapton reaction mechanism can be overcome by translational energy. Oxidation of MoS{sub 2} and WS{sub 2} dry lubricants in both ground-based and orbital exposures indicated the formation of MoO{sub 3} and WO{sub 3} respectively. A protective oxide layer is formed {approx}30 monolayers thick which has a high initial friction coefficient until the layer is worn off.

Cross, J.B. (Los Alamos National Lab., NM (United States)); Koontz, S.L. (National Aeronautics and Space Administration, Houston, TX (United States). Lyndon B. Johnson Space Center); Lan, E.H. (McDonnell Douglas Space Systems Co., Huntington Beach, CA (United States))

1991-01-01

353

Constraints on the total and kinetic energy of ground states in a class of potential models

NASA Astrophysics Data System (ADS)

It is shown that the ground state energy in a central potential is a concave (convex) function of angular momentum l when this potential is a concave (convex) function of r2. A result stronger than concavity is obtained when the Laplacian of the potential is negative. New bounds in the kinetic energy of these states are derived in terms of energy differences and for s states in terms of the wave function at the origin. These bounds can be used to give good estimates of the ground state energies for power law potentials.

Common, A. K.; Martin, A.

1989-03-01

354

For a wide range of confinement strengths ?, explicitly-correlated calculations afford approximate energies E(?) of the ground and low-lying excited states of the four-electron harmonium atom that are within few ?hartree of the exact values, the errors in the respective energy components being only slightly higher. This level of accuracy constitutes an improvement of several orders of magnitude over the previously published data, establishing a set of benchmarks for stringent calibration and testing of approximate electronic structure methods. Its usefulness is further enhanced by the construction of differentiable approximants that allow for accurate computation of E(?) and its components for arbitrary values of ?. The diversity of the electronic states in question, which involve both single- and multideterminantal first-order wavefunctions, and the availability of the relevant natural spinorbitals and their occupation numbers make the present results particularly useful in research on approximate density-matrix functionals. The four-electron harmonium atom is found to possess the (3)P+ triplet ground state at strong confinements and the (5)S- quintet ground state at the weak ones, the energy crossing occurring at ??? 0.0240919. PMID:25084902

Cioslowski, Jerzy; Strasburger, Krzysztof; Matito, Eduard

2014-07-28

355

An output coupler for Bose condensed atoms The observations of BEC have stimulated interest in atom lasers, coherent sources of atomic matter waves. The build-up of atoms in the ground state of a magnetic. We demonstrated a scheme for doing this with Bose condensed atoms [1]. A variable fraction of atoms

356

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 states for four spin-orbit components 1/2, 3/2, 5/2, and 7/2 are calculated intensively to clarify the ground state of IrO. Our calculation suggests that the ground state is of 1/2 spin-orbit component, which is highly mixed with $^4\\Sigma^-$ and $^2\\Pi$ states in $\\Lambda-S$ notation. The two low-lying states of the 5/2 and 7/2 spin-orbit components are nearly degenerate with the ground state and locate only 234 and 260 cm$^{-1}$ above, respectively. The equilibrium bond length 1.712 \\AA \\ and harmonic vibrational frequency 903 cm$^{-1}$ of the 5/2 spin-orbit component are close to the experimental measurement of 1.724 \\AA \\ and 909 cm$^{-1}$, which suggests the 5/2 state should be the low-lying state contributed to spectra in experimental study. Moreover, the electronic states that give rise to the observed trans...

Suo, Bingbing; Han, Huixian

2014-01-01

357

Ground-state properties of boron-doped diamond

Boron-doped diamond undergoes an insulator-metal or even a superconducting transition at some critical value of the dopant concentration. We study the equilibrium lattice parameter and bulk modulus of boron-doped diamond experimentally and in the framework of the density functional method for different levels of boron doping. We theoretically consider the possibility for the boron atoms to occupy both substitutional and interstitial positions and investigate their influence on the electronic structure of the material. The data suggest that boron softens the lattice, but softening due to substitutions of carbon with boron is much weaker than due to incorporation of boron into interstitial positions. Theoretical results obtained for substitution of carbon are in very good agreement with our experiment. We present a concentration dependence of the lattice parameter in boron-doped diamond, which can be used for to identify the levels of boron doping in future experiments.

Zarechnaya, E. Yu., E-mail: ezarechnaya@yahoo.com; Isaev, E. I. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation)], E-mail: eyvaz_isaev@yahoo.com; Simak, S. I. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden); Vekilov, Yu. Kh. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation); Dubrovinsky, L. S. [University of Bayreuth, Bayerisches Geoinstitut (Germany); Dubrovinskaia, N. A. [University of Heidelberg, Mineralogisches Institut (Germany); Abrikosov, I. A. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden)

2008-04-15

358

Ground-state cooling of a trapped ion using long-wavelength radiation

We demonstrate ground-state cooling of a trapped ion using long-wavelength radiation. This is a powerful tool for the implementation of quantum operations, where long-wavelength radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of $\\overline{n} = 0.13(4)$ after sideband cooling, corresponding to a ground-state occupation probability of 88(7)\\%. After preparing in the vibrational Fock state $\\left|n=0\\right\\rangle$, we implement sideband Rabi oscillations which last for more than 10 ms, demonstrating the long coherence time of our system. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost two orders of magnitude compared to our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system.

Weidt, S; Webster, S C; Standing, E D; Rodriguez, A; Webb, A E; Lekitsch, B; Hensinger, W K

2015-01-01

359

Ground states at the filling factors ?=7/3 and 8/3 in the second Landau level

NASA Astrophysics Data System (ADS)

The Laughlin state successfully describe the fractional quantum Hall state at ?=1/3 in the lowest Landau level. However, it is known that the Laughlin wavefunction has little overlap with the ground state wavefunction at ?=7/3 in the second Landau level. The ground states at ?=7/3 and 8/3 are still unknown.To determine the ground states at these fillings, we use the exact diagonalization method and density-matrix renormalization group (DMRG) method. We calculate overlaps between the ground state and the trial wavefunctions, the ground state energies, and the ground-state pair-correlation functions. We find that the ground state wavefunction at ?=8/3 have very high overlap between the parafermion state, and the ground state energy of the parafermion state is lower than that of the Laughlin state. Further, the short-range structures of pair-correlation functions are significantly different from that of the Lauglin state.From these results, we consider that the parafermion state is a strong candidate of the ground state at ?=7/3 and ?=8/3.

Ito, Toru; Shibata, Naokazu; Nomura, Kentaro

2013-03-01

360

The ground electronic state of KCs studied by Fourier transform spectroscopy

NASA Astrophysics Data System (ADS)

We present here the first analysis of laser induced fluorescence (LIF) of the KCs molecule obtaining highly accurate data and perform a direct potential construction for the X 1?+ ground state in a wide range of internuclear distances. KCs molecules were produced by heating a mixture of K and Cs metals in a heat pipe at a temperature of about 270 °C. KCs fluorescence was induced by different laser sources: the 454.5, 457.9, 465.8, and 472.7 nm lines of an Ar+ laser, a dye laser with Rhodamine 6G dye (excitation at around 16 870 cm-1), and 850 and 980 nm diode lasers (11 500-11 900 and 10 200-10 450 cm-1 tuning ranges, respectively). The LIF to the ground state was recorded by a Bruker IFS-125HR Fourier transform spectrometer with a spectral resolution of 0.03 cm-1. Particularly, by applying the 850 nm laser diode we were able to observe LIF progressions to very high vibrational levels of the ground state close to the dissociation limit. The present data field contains 7226 term values for the ground state X 1?+ and covers a range from v''=0 to 97 with J'' varying from 12 to 209. More than 10 000 fluorescence lines were used to fit the ground state potential energy curve via the inverted perturbation approach procedure. The present empirical potential extends up to approximately 12.6 A? and covers more than 99% of the potential well depth, it describes most of the spectral lines with an accuracy of about 0.003 cm-1 and yields a dissociation energy of 4069.3+/-1.5 cm-1 for the ground state X 1?+. First observations of the triplet ground state a 3?+ of KCs are presented, and preliminary values of few main molecular constants could be derived.

Ferber, R.; Klincare, I.; Nikolayeva, O.; Tamanis, M.; Knöckel, H.; Tiemann, E.; Pashov, A.

2008-06-01

361

We propose a scheme for generating a genuine $\\chi$-type four-particle entangled state of superconducting artificial atoms with broken symmetry by using one-dimensional transmission line resonator as a data bus. The $\\Delta$-type three-level artificial atom we use in the scheme is different from natural atom and has cyclic transitions. After suitable interaction time and simple operations, the desired entangled state can be obtained. Since artificial atomic excited states and photonic states are adiabatically eliminated, our scheme is robust against the spontaneous emissions of artificial atoms and the decays of transmission line resonator.

Chun-Ling Leng; Qi Guo; Xin Ji; Shou Zhang

2014-12-11

362

Atomic coherent state in Schwinger bosonic realization for optical Raman coherent effect

For optical Raman coherent effect we introduce the atomic coherent state (or the angular momentum coherent state with various angular momemtum values) in Schwinger bosonic realization, they are the eigenvectors of the Hamiltonian describing the Raman effect. Similar to the fact that the photon coherent state describes laser light, the atomic coherent state is related to Raman process.

Hong-Yi Fan; Xue-xiang Xu; Li-yun Hu

2009-12-04

363

Ground states and dynamics of spin-orbit-coupled Bose-Einstein condensates

We study analytically and asymptotically as well as numerically ground states and dynamics of two-component spin-orbit-coupled Bose-Einstein condensates (BECs) modeled by the coupled Gross-Pitaevskii equations (CGPEs). In fact, due to the appearance of the spin-orbit (SO) coupling in the two-component BEC with a Raman coupling, the ground state structures and dynamical properties become very rich and complicated. For the ground states, we establish the existence and non-existence results under different parameter regimes, and obtain their limiting behaviors and/or structures with different combinations of the SO and Raman coupling strengths. For the dynamics, we show that the motion of the center-of-mass is either non-periodic or with different frequency to the trapping frequency when the external trapping potential is taken as harmonic and the initial data is chosen as a stationary state (e.g. ground state) with a shift, which is completely different from the case of a two-component BEC without the SO coupling, and obtain the semiclassical limit of the CGPEs in the linear case via the Wigner transform method. Efficient and accurate numerical methods are proposed for computing the ground states and dynamics, especially for the case of box potentials. Numerical results are reported to demonstrate the efficiency and accuracy of the numerical methods and show the rich phenomenon in the SO-coupled BECs.

Weizhu Bao; Yongyong Cai

2014-07-22

364

First-principles study of ground-state properties of U2Mo.

By means of first-principles calculations, we have systematically investigated the structural, elastic, vibrational, thermal and electronic properties of the ground-state phase for the intermetallic compound U2Mo. Our results reveal that the previously synthesized I4/mmm structure of U2Mo is a metastable phase and unstable, neither thermodynamically nor vibrationally at the ground state. In combination with the evolutionary structural searches, our first-principles calculations suggest a new ground-state Pmmn phase, which has been confirmed theoretically to be stable, both thermodynamically and vibrationally. Moreover, through the DFT + D technique we have discussed the influence of van der Waals interactions on the structural, elastic and vibrational properties, revealing a weak effect in pure U and Mo solids and U2Mo alloy. The analysis of the electronic band structures evidences its electronic stabilities with the appearance of a deep valley in the density of states at the Fermi level. Moreover, we have investigated further the temperature-dependent structural, thermal expansion and elastic properties of our proposed Pmmn ground-state phase. These results are expected to stimulate further experimental investigations of the ground-state phase of U2Mo. PMID:25380409

Wang, Xin; Cheng, Xiyue; Zhang, Yuting; Li, Ronghan; Xing, Weiwei; Zhang, Pengcheng; Chen, Xing-Qiu

2014-12-28

365

Ground-state properties of linear-exchange quantum spin models

NASA Astrophysics Data System (ADS)

We study a class of one-dimensional antiferromagnetic quantum spin-1/2 models using DMRG. The exchange interaction in these models decreases linearly with the separation between the spins, Jij = R - |i - j| for |i - j| < R, where R is a positive integer ?2. For |i - j| ? R, the interaction is zero. It is known that all the odd-R models have the same exact dimer ground state as the Majumdar-Ghosh (MG) model. In fact, R = 3 is the MG model. However, for an even R, the exact ground state is not known in general, except for R = 2 (the integrable nearest-neighbor Heisenberg chain) and the asymptotic limit of R in which the MG dimer state emerges as the exact ground state. Therefore, we numerically study the ground-state properties of the finite even-R ? 2 models, particularly for R = 4, 6 and 8. We find that, unlike R = 2, the higher even-R models are spin-gapped, and exhibit robust dimer order of the MG type in the ground state. The spin-spin correlations decay rapidly to zero, albeit showing weak periodic revivals.

Danu, Bimla; Kumar, Brijesh; Pai, Ramesh V.

2012-10-01

366

Gaining Ground: Poverty in the Postwar United States

Official measures of poverty in the United States are compiled by the Census Bureau by comparing a household's income level to a prespecified threshold. From a theoretical perspective it is more appropriate to evaluate the level of poverty using a consumption-based measure of household welfare. This paper evaluate s the level of poverty using expenditure data from the Consumer Expenditure

Daniel T. Slesnick

1993-01-01

367

Bell States of Atoms with Ultralong Lifetimes and Their Tomographic State Analysis

Arbitrary atomic Bell states with two trapped ions are generated in a deterministic and preprogrammed way. The resulting entanglement is quantitatively analyzed using various measures of entanglement. For this, we reconstruct the density matrix using single qubit rotations and subsequent measurements with near-unity detection efficiency. This procedure represents the basic building block for future process tomography of quantum computations. As

C. F. Roos; G. P. Lancaster; M. Riebe; H. Häffner; W. Hänsel; S. Gulde; C. Becher; J. Eschner; F. Schmidt-Kaler; R. Blatt

2004-01-01

368

In the strong interaction limit, attractive fermions with N-component hyperfine states in a one-dimensional waveguide form unbreakable bound cluster states. We demonstrate that the ground state of strongly attractive SU(N) Fermi gases can be effectively described by a super Tonks-Girardeau gaslike state composed of bosonic cluster states with strongly attractive cluster-cluster interaction for even N and a Fermi duality of a super Tonks-Girardeau gaslike state composed of fermionic cluster states with weakly interacting cluster-cluster p-wave interaction for odd N.

Yin Xiangguo; Chen Shu [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Guan Xiwen [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Batchelor, M. T. [Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Mathematical Sciences Institute, Australian National University, Canberra ACT 0200 (Australia)

2011-01-15

369

ERIC Educational Resources Information Center

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…

Bandyopadhyay, Subhajit; Roy, Saswata

2014-01-01

370

1083 Exciton Bose condensation : the ground state of an electron-hole gas II. Spin states, incorporant la condensation de Bose des paires Ã©lectron-trou. Nous Ã©tudions en dÃ©tail la limite diluÃ©e, et incorporates Bose condensation of bound electron-hole pairs. We discuss in detail the low density limit

Boyer, Edmond

371

Production and decay of ground-state Pb(g) from the 308-nm photodissociation of PbI[sub 2](g)

An extensive investigation of the production and decay of ground-state lead atoms from the 308-nm XeCl excimer laser photodissociation of PbI[sub 2](g) is reported. The laser fluence dependences of the Pb(g) and PbI(g) yields along with energetic considerations suggest that Pb(g) is produced by a two-photon process and PbI(g) is produced by a one-photon process. Pb decay profiles as a

R. E. McClean; J. W. Simons; R. C. Oldenborg

1991-01-01

372

Ground state energy and width of He7 from Li8 proton knockout

NASA Astrophysics Data System (ADS)

The ground state energy and width of He7 has been measured with the Modular Neutron Array (MoNA) and superconducting dipole Sweeper magnet experimental setup at the National Superconducting Cyclotron Laboratory. He7 was produced by proton knockout from a secondary Li8 beam. The measured decay energy spectrum is compared to simulations based on Breit-Wigner line shape with an energy-dependent width for the resonant state. The energy of the ground state is found to be 400(10) keV with a full-width at half-maximum of 125(-15+40) keV.

Denby, D. H.; Deyoung, P. A.; Baumann, T.; Bazin, D.; Breitbach, E.; Brown, J.; Frank, N.; Gade, A.; Hall, C. C.; Hinnefeld, J.; Hoffman, C. R.; Howes, R.; Jenson, R. A.; Luther, B.; Mosby, S. M.; Olson, C. W.; Peters, W. A.; Schiller, A.; Spyrou, A.; Thoennessen, M.

2008-10-01

373

Ground-state phase in the three-dimensional topological Dirac semimetal Na3Bi

NASA Astrophysics Data System (ADS)

By means of the first-principles calculations, we found that the early characterized 3D topological Dirac semimetal P63/mmc-Na3Bi is dynamically unstable at the ground state due to the presence of the large imaginary phonon frequencies around the K point. Alternatively, our calculations suggested a new ground-state phase crystalizing in a P3¯c1 structure with buckled graphite-like Na/Bi sheets, which is both energetically and dynamically stable. Moreover, the calculations also uncovered that the P3¯c1 phase is a 3D topological Dirac semimetal, with exactly the same electronic states of the metastable P63/mmc phase.

Cheng, Xiyue; Li, Ronghan; Sun, Yan; Chen, Xing-Qiu; Li, Dianzhong; Li, Yiyi

2014-06-01

374

Heat of formation determination of the ground and excited state of cyanomethylene (HCCN) radical

NASA Technical Reports Server (NTRS)

Ab initio electronic structure theory has been used to characterize the structure of the ground triplet and lowest singlet excited states of cyanomethylene. The geometries, vibrational frequencies, and heats of formation have been determined using second-order Moller-Plesset perturbation, single and double excitation configuration interaction, and quadratic configuration interaction theory. The heat of formation is predicted with isodesmic reaction and Gaussian-2 theory (G2) for the ground triplet and first excited singlet states of cyanomethylene. For the ground state Delta-H(sub 0)(sup f,0) is 114.8+/-2 kcal/mol while for the excited single state it is 126.5+/-2 kcal/mol.

Francisco, Joseph S.

1994-01-01

375

Is there a maser in the silicon monoxide ground state. [thermal emission of Orion molecular clouds

NASA Technical Reports Server (NTRS)

Observations are reported of weak emission from the ground vibrational state of SiO in the Orion molecular cloud. It is shown that this emission has a rather smooth low-intensity profile extending over a large velocity range and is present at velocities where maser emissions from the first and second vibrational states are absent. Based on this difference, the present emission is interpreted as thermal emission in the ground state in regions where there is insufficient excitation to produce the vibrationally excited masers. Possible origins are considered for the Orion SiO maser, and it is noted that only VY CMa shows a profile that could be interpreted as ground-state maser emission.

Buhl, D.; Snyder, L. E.; Lovas, F. J.; Johnson, D. R.

1975-01-01

376

From Spin Glass to Quantum Spin Liquid Ground States in Molybdate Pyrochlores

NASA Astrophysics Data System (ADS)

We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu2Mo2O7 and S=1/2 oxynitride Lu2Mo2O5N2. Lu2Mo2O7 undergoes a transition to an unconventional spin glass ground state at Tf˜16 K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from spin glass to quantum spin liquid. The comparison of the static and dynamic spin correlations within the oxide and oxynitride phases presented here reveals the crucial role played by quantum fluctuations in the selection of a ground state. Furthermore, we estimate an upper limit for a gap in the spin excitation spectrum of the quantum spin liquid state of the oxynitride of ? ˜0.05 meV or ? /|?|˜0.004, in units of its antiferromagnetic Weiss constant ? ˜-121 K.

Clark, L.; Nilsen, G. J.; Kermarrec, E.; Ehlers, G.; Knight, K. S.; Harrison, A.; Attfield, J. P.; Gaulin, B. D.

2014-09-01

377

Bounds on the energy densities of ground states on static spacetimes of compact objects

In this paper we investigate quantum fields propagating on given, static, spherically symmetric spacetimes, which are isometric to a part of the Schwarzschild spacetime. Without specifying the internal geometry we show, that there exist bounds on the energy densities of ground states of a quantum scalar field on such spacetimes. The bounds (from above and below) come from the so-called Quantum Energy Inequalities, and are centered around the energy density of the Boulware state (the ground state for Schwarzschild spacetime). The specific value of the bound from below depends critically on the distance $\\ell$ from the horizon, where the spacetimes of compact objects cease to be isometric to the Schwarzschild spacetime. In the limit of small $\\ell$ we prove, that the energy densities of ground states cannot be below the Boulware level.

P. Marecki

2005-07-20

378

From spin glass to quantum spin liquid ground states in molybdate pyrochlores.

We present new magnetic heat capacity and neutron scattering results for two magnetically frustrated molybdate pyrochlores: S=1 oxide Lu_{2}Mo_{2}O_{7} and S=1/2 oxynitride Lu_{2}Mo_{2}O_{5}N_{2}. Lu_{2}Mo_{2}O_{7} undergoes a transition to an unconventional spin glass ground state at T_{f}?16??K. However, the preparation of the corresponding oxynitride tunes the nature of the ground state from spin glass to quantum spin liquid. The comparison of the static and dynamic spin correlations within the oxide and oxynitride phases presented here reveals the crucial role played by quantum fluctuations in the selection of a ground state. Furthermore, we estimate an upper limit for a gap in the spin excitation spectrum of the quantum spin liquid state of the oxynitride of ??0.05??meV or ?/|?|?0.004, in units of its antiferromagnetic Weiss constant ??-121??K. PMID:25260001

Clark, L; Nilsen, G J; Kermarrec, E; Ehlers, G; Knight, K S; Harrison, A; Attfield, J P; Gaulin, B D

2014-09-12

379

Quantum ground state and single-phonon control of a mechanical resonator.

Quantum mechanics provides a highly accurate description of a wide variety of physical systems. However, a demonstration that quantum mechanics applies equally to macroscopic mechanical systems has been a long-standing challenge, hindered by the difficulty of cooling a mechanical mode to its quantum ground state. The temperatures required are typically far below those attainable with standard cryogenic methods, so significant effort has been devoted to developing alternative cooling techniques. Once in the ground state, quantum-limited measurements must then be demonstrated. Here, using conventional cryogenic refrigeration, we show that we can cool a mechanical mode to its quantum ground state by using a microwave-frequency mechanical oscillator-a 'quantum drum'-coupled to a quantum bit, which is used to measure the quantum state of the resonator. We further show that we can controllably create single quantum excitations (phonons) in the resonator, thus taking the first steps to complete quantum control of a mechanical system. PMID:20237473

O'Connell, A D; Hofheinz, M; Ansmann, M; Bialczak, Radoslaw C; Lenander, M; Lucero, Erik; Neeley, M; Sank, D; Wang, H; Weides, M; Wenner, J; Martinis, John M; Cleland, A N

2010-04-01

380

Long-range interaction between metastable helium and ground state helium.

NASA Technical Reports Server (NTRS)

Results of analysis for the long-range interaction between ground state helium and triplet metastable helium, which shows that the long-range coefficient is the same for both gerade and ungerade states. Those terms which lead to the second term on the right hand side of a developed equation vanish through spin selection rules.

Victor, G. A.; Sando, K.

1971-01-01

381

The First Calculation for the Mass of the Ground $4^{++}$ Glueball State on Lattice

Under the quenched approximation, we perform a lattice calculation for the mass of the ground $4^{++}$ glueball state in $E^{++}$ channel on a $D=3+1$ lattice. Our calculation shows that the mass of this state is $M_G(4^{++})=3.65(6)(18)GeV$, which rules out the $4^{++}$ or mainly $4^{++}$ glueball interpretation for $\\xi(2230)$.

Da Qing Liu; Ji Min Wu

2001-05-18

382

GROUND WATER CONTAMINANTS AND THEIR SOURCES - A REVIEW OF STATE REPORTS

Pursuant to section 305(B) of the Clean Water Act of 1987, each state submits biennially a water quality report to the U.S. Environmental Protection Agency (EPA). his paper contains a review of 42 such reports in relation to public ground water supplies. ineteen states provided m...

383

Gain recovery dynamics are studied in electrically pumped quantum dot (QD) based semiconductor optical amplifiers (SOAs) after amplification of double femtosecond laser pulses using ultrafast pump-probe spectroscopy with heterodyne detection. The authors observe a distinct change in gain recovery in the ground state when a significant excited state population is achieved. A complete gain recovery is found when two 150

Sabine Dommers; Vasily V. Temnov; Ulrike Woggon; Jordi Gomis; Juan Martinez-Pastor; Matthias Laemmlin; Dieter Bimberg

2007-01-01

384

Magnetic dipole moments of the145 149Eu ground states

NASA Astrophysics Data System (ADS)

Nuclear orientation measurements at low temperatures have been carried out on radioactive isotopes of145 149Eu in Fe and of147,149Eu in Gd. The initial-state orientation coefficients determined from the measured gamma-ray anisotropies yield the magnetic dipole moments of the europium nuclei with A=145, 146, 147, 148 and 149 to be 3.2(5), 1.7(3), 3.1(4), 2.1(3) and 2.5(5), ?N, respectively. The values obtained for odd-A nuclei follow the systematics of the 5/2+ state magnetic moments of the nuclei in this region and are close to the values given by the single-particle model.

Kraciková, T. I.; Davaa, S.; Finger, M.; Deryuga, V. A.

1983-12-01

385

Theory of Zeeman Effect in the Ground Multiplets of Rare-Earth Atoms

A number of corrections are made to the simple Landé formula for the g values of levels deriving from the ground term of configurations of the type 4fn. These include (a) the Schwinger correction, to give an accurate value of the gyromagnetic ratio for the electron spin; (b) a correction to allow for the deviations from perfect RS coupling; (c)

B. R. Judd; I. Lindgren

1961-01-01

386

Hydrogeologic factors that influence ground water movement in the desert southwest United States

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.

Chuang, Frank C.; McKee, Edwin H.; Howard, Keith A.

2003-01-01

387

Quantum fluctuations and the magnetic ground state of Ce3Pd20Si6

NASA Astrophysics Data System (ADS)

The temperature and magnetic field dependence of neutron-scattering studies on the heavy fermion compound Ce3Pd20Si6 are reported. Inelastic neutron scattering reveals two crystal-field excitations corresponding to the environments of the two distinct rare-earth locations within this cubic compound. Surprisingly, the ground states of the two individual Ce sites are inequivalent with the 4a site having a ?7 ground state, while the 8c site reveals a ?8 ground state. This is in contrast to the situation found in the analogous compound Ce3Pd20Ge6 , where the ?8 ground state is realized for both Ce sites. In addition, these results reveal an interaction between the 8c and 4a sites previously believed to be absent. The ground state was probed with uniaxial polarization analysis across the region in which field-induced quantum criticality has previously been determined. In zero applied magnetic field no long-range magnetic order could be determined. However, further evidence of field-induced quantum criticality is presented with the observation of diffuse scattering consistent with quantum fluctuations due to nearest-neighbor spin correlations between the two Ce sites.

Deen, P. P.; Strydom, A. M.; Paschen, S.; Adroja, D. T.; Kockelmann, W.; Rols, S.

2010-02-01

388

Localization of Cold Atoms in State-Dependent Optical Lattices via a Rabi Pulse

We propose a novel realization of Anderson localization in nonequilibrium states of ultracold atoms in an optical lattice. A Rabi pulse transfers part of the population to a different internal state with infinite effective mass. These frozen atoms create a quantum superposition of different disorder potentials, localizing the mobile atoms. For weakly interacting mobile atoms, Anderson localization is obtained. The localization length increases with increasing disorder and decreasing interaction strength, contrary to the expectation for equilibrium localization.

Horstmann, Birger; Duerr, Stephan [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany); Roscilde, Tommaso [Laboratoire de Physique, CNRS UMR 5672, Ecole Normale Superieure de Lyon, Universite de Lyon, 46 Allee d'Italie, Lyon, F-69364 (France)

2010-10-15

389

An N-atom Collective State Atomic Clock with Root-N Fold Increase in Effective Frequency and Root IN PROGRESS. VERSION 1.5) The short term stability of atomic frequency standards is limited by the transit time. However, the Ramsey fringes of the collective state of an N atom system become narrower by N

Shahriar, Selim

390

NASA Astrophysics Data System (ADS)

This paper deals with the electronic structure of RbSr, a molecule possessing both a magnetic dipole moment and an electric dipole moment in its own frame, allowing its manipulation with external fields. Two complementary ab initio approaches are used for the ground and lowest excited states: first, an approach relying on optimized effective core potentials with core polarization potentials based on a full configuration interaction involving three valence electrons and second, an approach using a small-size effective core potential with 19 correlated electrons in the framework of coupled-cluster theory. We have found excellent agreement between these two approaches for the ground-state properties including the permanent dipole moment. We have focused on studies of excited states correlated to the two lowest asymptotes Rb (5p2P)+Sr(5s21S) and Rb (5s2S)+Sr(5s5p3P) relevant for ongoing experiments on ultracold quantum degenerate gases. We also present approximate potential curves including spin-orbit interaction based on atomic spin-orbit constants. These potential curves are an excellent starting point for experimental studies of molecular structure of RbSr using high-resolution spectroscopy.

?uchowski, Piotr S.; Guérout, R.; Dulieu, O.

2014-07-01

391

NASA Technical Reports Server (NTRS)

The GeH radical has been detected in its ground 2 Pi state in the gas phase reaction of fluorine atoms with GeH4 by laser magnetic resonance techniques. Rotational transitions within both 2 Pi 1/2 and 2 Pi 3/2 manifolds have been observed at far-infrared wavelengths and rotational transitions between the two fine structure components have been detected at infrared wavelengths (10 microns). Signals have been observed for all five naturally occurring isotopes of germanium. Nuclear hyperfine structure for H-1 and Ge-73 has also been observed. The data for the dominant isotope (/Ge-74/H) have been fitted to within experimental error by an effective Hamiltonian to give a set of molecular parameters for the X 2 Pi state which is very nearly complete. In addition, the dipole moment of GeH in its ground state has been estimated from the relative intensities of electric and magnetic dipole transitions in the 10 micron spectrum to be 1.24(+ or - 0.10) D.

Brown, J. M.; Evenson, K. M.; Sears, T. J.

1985-01-01

392

Synopsis: The ground access problem at United States airports will be discussed in general terms. Those characteristics of airport users relative to ground transportation will be analyzed to provide a clear picture of the ...

Munds, Allan J.

1969-01-01

393

Anomalous magnetic ground state in PrSi evidenced by the magnetocaloric effect

NASA Astrophysics Data System (ADS)

Previous investigations into the physical properties of PrSi have shown this compound to order ferromagnetically at 54 K. However, the magnetic ground state has not yet been determined unambiguously. PrSi crystallizes in the orthorhombic FeB-type structure. Typically, the crystalline electric field (CEF) would uplift the degeneracy of the J =4 Pr3+ free-ion ground state multiplet, yielding nine (normally non-magnetic) singlets. It is known that magnetic order in such systems may be established via the admixture of two singlets into a doublet state, analogous to TmNi, which crystallizes in the same structure. From symmetry considerations, collinear ferromagnetically ordered moments should lie parallel to the crystallographic b-axis. However, neutron diffraction experiments have shown that the easy magnetic axis lies in the ac-plane. This is the first suggestion that the ground state in PrSi is not determined by the CEF alone. Here, we investigate the ground state properties of PrSi by analyzing its specific heat. A Schottky contribution associated with the thermal population of CEF-split energy levels is absent from the 4f-electron contribution to the specific heat and the magnetic configurational entropy points to a full nine-fold degenerate J =4 multiplet magnetic ground state. The strongest evidence for such a ground state is found when the magnetocaloric effect (MCE) in this system is considered. Furthermore, the MCE indicates the presence of a significant higher order exchange term in the magnetic Hamiltonian.

Snyman, J. L.; Strydom, A. M.

2012-04-01

394

Ground state of small mixed helium and spin-polarized tritium clusters: a quantum Monte Carlo study.

We report results for the ground-state energy and structural properties of small (4)He-T? clusters consisting of up to four T? and eight (4)He atoms. These results have been obtained using very well-known (4)He-(4)He and T?- T? interaction potentials and several models for the (4)He- T? interatomic potential. All the calculations have been performed with variational and diffusion Monte Carlo methods. It takes at least three atoms to form a mixed bound state. In particular, for small clusters the binding energies are significantly affected by the precise form of the (4)He- T? interatomic potential but the stability limits remain unchanged. The only exception is the (4)He(2)T? trimer whose stability in the case of the weakest (4)He- T? interaction potential is uncertain while it seems stable for other potentials. The mixed trimer (4)He(T?)(2), a candidate for the Borromean state, is not bound. All other studied clusters are stable. Some of the weakest bound clusters can be classified as quantum halo as a consequence of having high probability of being in a classically forbidden region. PMID:21303140

Stipanovi?, P; Marki?, L Vranješ; Boronat, J; Keži?, B

2011-02-01

395

Deformation change between isomeric and ground states in the {sup 184}Au and {sup 183}Pt isotones

Deformation changes {delta}{beta} have been found out between isomeric and ground states of the {sup 183}Pt and {sup 184}Au isotones. Atomic spectroscopy measurements by laser were carried out using the COMPLIS setup. Hyperfine structure (HFS) spectra and isotope shift (IS) were obtained for the 5d{sup 9}6s {sup 3}D{sub 3}{yields}5d{sup 9}6p {sup 3}P{sub 2} and 5d{sup 10}6s {sup 2}S{sub 1/2}{yields}5d{sup 10}6p {sup 2}P{sub 3/2} optical transitions in Pt and Au atoms respectively, providing deformation parameters {beta} and nuclear moments {mu} and Q{sub s}. The influence of the proton-neutron coupling on the {delta}{beta} value in {sup 184}Au relatively to its isotone {sup 183}Pt has been determined. Besides, the h9/2 proton state that is decoupled from the core in {sup 183,185}Au, becomes the 3/2[532] state (h9/2 parentage) strongly coupled in the doubly-odd {sup 184}Au nucleus.

Sauvage, J.; Le Blanc, F.; Obert, J.; Oms, J.; Putaux, J. C.; Roussiere, B. [Institut de Physique Nucleaire, 91406 Orsay cedex (France); Boos, N.; Huber, G.; Krieg, M.; Sebastian, V. [Institut fuer Physik der Universitaet Mainz, 55099 Mainz (Germany); Cabaret, L.; Duong, H. T.; Pinard, J. [Laboratoire Aime Cotton, 91405 Orsay cedex (France); Crawford, J.; Lee, J. K. P. [Foster Radiation Laboratory, McGill University, H3A2T8 Montreal (Canada); Genevey, J.; Ibrahim, F. [Institut des Sciences Nucleaires, 38026 Grenoble cedex (France); Girod, M. [Service de Physique Nucleaire, CEA, BP 12, 91680 Bruyeres-le-Chatel (France); Libert, J. [Centre d'Etudes Nucleaires de Bordeaux Gradignan, 33175 Gradignan cedex (France); Zemlyanoi, S. [Flerov Laboratory of Nuclear Reaction, JINR, Dubna 141980, Moscow Region (Russian Federation)

1998-12-21

396

A triplet ground state for cationic polyaromatic hydrocarbons after hydrogen loss

NASA Astrophysics Data System (ADS)

i-system into the empty ?-orbital, although this compromises the aromaticity of the system and leads to a triplet state. While a singlet state has now been firmly established for the phenyl cation, the stability of the triplet in larger polyaromatic species increases as result of the growing %B i-system, thus reducing the energy required to transfer an electron to the empty ?-orbital. Observation of the triplet state of isolated naphthyl+, phenanthyl+ and pyrenyl+ systems is undertaken by IR multiple-photon dissociation (IRMPD) spectroscopy using a tunable free electron laser. The establishment of a triplet ground state for these PAH species possibly invokes new scenarios to be considered, such as regarding the triplet-state chemistry of PAH molecules and the altered optical properties. After reviewing the experimental aspects of this work, possible consequences of a triplet ground state of PAH species are briefly outlined.

Galue, H. A.; Oomens, J.

2011-05-01

397

Arsenic in ground water of the United States: occurrence and geochemistry

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 0 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 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 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.

Welch, Alan H.; Westjohn, D.B.; Helsel, Dennis R.; Wanty, Richard B.

2000-01-01

398

Ground state energy of electrons in a static point-ion lattice

NASA Technical Reports Server (NTRS)

The ground state energy of a neutral collection of protons and electrons was investigated under the assumption that in the ground state configuration, static protons occupy the sites of a rigid Bravais lattice. The Wigner-Seitz method was used in conjunction with three postulated potentials: bare Coulomb, Thomas-Fermi screening, and screening by a uniform bare background charge. Within these approximations, the exact band-minimum energy and wave functions are derived. For each of the three potentials, the approximate minimum ground state energy per proton (relative to isolated electrons and protons) is, respectively, -1.078 Ry, -1.038 Ry, and -1.052 Ry. These three minima all fall at a density of about 0.60 gm/cu cm, which is thus an approximate lower bound on the density of metallic hydrogen at its transition pressure.

Styer, D. F.; Ashcroft, N. W.

1983-01-01

399

Essentially exact ground-state calculations by superpositions of nonorthogonal Slater determinants

An essentially exact ground-state calculation algorithm for few-electron systems based on superposition of nonorthogonal Slater determinants (SDs) is described, and its convergence properties to ground states are examined. A linear combination of SDs is adopted as many-electron wave functions, and all one-electron wave functions are updated by employing linearly independent multiple correction vectors on the basis of the variational principle. The improvement of the convergence performance to the ground state given by the multi-direction search is shown through comparisons with the conventional steepest descent method. The accuracy and applicability of the proposed scheme are also demonstrated by calculations of the potential energy curves of few-electron molecular systems, compared with the conventional quantum chemistry calculation techniques. PMID:23634829

2013-01-01

400

Improved Quantum Hard-Sphere Ground-State Equations of State

The London ground-state energy formula as a function of number density for a system of identical boson hard spheres, corrected for the reduced mass of a pair of particles in a sphere-of-influence picture, and generalized to fermion hard-sphere systems with two and four intrinsic degrees of freedom, has a double-pole at the ultimate \\textit{regular} (or periodic, e.g., face-centered-cubic) close-packing density usually associated with a crystalline branch. Improved fluid branches are contructed based upon exact, field-theoretic perturbation-theory low-density expansions for many-boson and many-fermion systems, appropriately extrapolated to intermediate densities, but whose ultimate density is irregular or \\textit{random} closest close-packing as suggested in studies of a classical system of hard spheres. Results show substantially improved agreement with the best available Green-function Monte Carlo and diffusion Monte Carlo simulations for bosons, as well as with ladder, variational Fermi hypernetted chain, and so-called L-expansion data for two-component fermions.

M. A. Solís; M. de Llano; J. W. Clark; George A. Baker Jr

2007-10-26

401

NASA Astrophysics Data System (ADS)

We report a new approach to investigating the mechanisms of fast peptide cation-radical dissociations based on an analysis of time-resolved reaction progress by Ehrenfest dynamics, as applied to an Ala-Arg cation-radical model system. Calculations of stationary points on the ground electronic state that were carried out with effective CCSD(T)/6-311++G(3df,2p) could not explain the experimental branching ratios for loss of a hydrogen atom, ammonia, and N-C? bond dissociation in (AR + 2H)+?. The Ehrenfest dynamics results indicate that the ground and low-lying excited electronic states of (AR + 2H)+? follow different reaction courses in the first 330 femtoseconds after electron attachment. The ground ( X) state undergoes competing loss of N-terminal ammonia and isomerization to an aminoketyl radical intermediate that depend on the vibrational energy of the charge-reduced ion. The A and B excited states involve electron capture in the Arg guanidine and carboxyl groups and are non-reactive on the short time scale. The C state is dissociative and progresses to a fast loss of an H atom from the Arg guanidine group. Analogous results were obtained by using the B3LYP and CAM-B3LYP density functionals for the excited state dynamics and including the universal M06-2X functional for ground electronic state calculations. The results of this Ehrenfest dynamics study indicate that reaction pathway branching into the various dissociation channels occurs in the early stages of electron attachment and is primarily determined by the electronic states being accessed. This represents a new paradigm for the discussion of peptide dissociations in electron based methods of mass spectrometry.

Moss, Christopher L.; Liang, Wenkel; Li, Xiaosong; Ture?ek, František

2012-03-01

402

Ground-state energy of the q -state Potts model: The minimum modularity

NASA Astrophysics Data System (ADS)

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), 10.1103/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 /

Lee, J. S.; Hwang, S.; Yeo, J.; Kim, D.; Kahng, B.

2014-11-01

403

Historically grounded spatial population projections for the continental United States

NASA Astrophysics Data System (ADS)

Large-scale spatial population projections are of growing importance to the global change community. Spatial settlement patterns are a key determinant of vulnerability to climate-related hazards as well as to land-use and its consequences for habitat, energy use, and emissions of greenhouse gases and air pollutants. Few projections exist of spatial distribution at national or larger scales, and while recent efforts improve on earlier approaches that simply scaled or extrapolated existing spatial patterns, important methodological shortcomings remain and models have not been calibrated to nor validated against historical trends. Here we present spatially explicit 100-year projections for the continental United States consistent with two different scenarios of possible socio-economic development. The projections are based on a new model that is calibrated to observed changes in regional population distribution since 1950, corrects for distorting effects at borders, and employs a spatial mask for designating protected or uninhabitable land. Using new metrics for comparing spatial outcomes, we find that our projections anticipate more moderate trends in urban expansion and coastal settlement than widely used existing projections. We also find that differences in outcomes across models are much larger than differences across alternative socio-economic scenarios for a given model, emphasizing the importance of better understanding of methods of spatial population projection for improved integrated assessments of social and environmental change.

Jones, Bryan; O'Neill, Brian C.

2013-12-01

404

NASA Technical Reports Server (NTRS)

The atomic oxygen erosion yields of 26 materials (all polymers except for pyrolytic graphite) were measured in two directed hyperthermal radio frequency (RF) plasma ashers operating at 30 or 35 kHz with air. The hyperthermal asher results were compared with thermal energy asher results and low Earth orbital (LEO) results from the Materials International Space Station Experiment 2 and 7 (MISSE 2 and 7) flight experiments. The hyperthermal testing was conducted to a significant portion of the atomic oxygen fluence similar polymers were exposed to during the MISSE 2 and 7 missions. Comparison of the hyperthermal asher prediction of LEO erosion yields with thermal energy asher erosion yields indicates that except for the fluorocarbon polymers of PTFE and FEP, the hyperthermal energy ashers are a much more reliable predictor of LEO erosion yield than thermal energy asher testing, by a factor of four.

Banks, Bruce A.; Dill, Grace C.; Loftus, Ryan J.; deGroh, Kim K.; Miller, Sharon K.

2013-01-01

405

A theoretical study of FeCN in the 6? electronic ground state

NASA Astrophysics Data System (ADS)

The three-dimensional potential energy and dipole moment surfaces for the electronic ground state 6? of FeCN have been computed at the MR-SDCI + Q + Erel/[Roos ANO (Fe), aug-cc-pVQZ (C, N)] level of theory, where MR-SDCI means 'multi-reference single and double excitation configuration interaction' and ANO means 'atomic natural orbital'. Based on these potential energy and dipole moment surfaces, the spectroscopic parameters, rovibronic energies, structural parameters, vibrational transition moments, and the wavenumbers and intensities of selected rotation-vibration transitions have been calculated. The equilibrium structure is linear with re(Fe-C) = 2.048 Å and re(C-N) = 1.168 Å, and the zero-point averaged structure is bent with < r(Fe-C)> 0 = 2.082 Å, < r(C-N)> 0 = 1.172 Å, and 0 = 170(5)°. At all the MR-SDCI + Q and the size-extensive multi-reference averaged quadratic coupled-cluster (MR-AQCC) levels of theory, with and without relativistic correction Erel, that were employed in the present work, 6? FeCN is predicted to be slightly more stable than 6? FeNC. For example, the energy difference between the two isomers is approximately 150 cm -1 at the highest level of theory employed, MR-AQCC + Erel/[Roos ANO (Fe), aug-cc-pVQZ (C, N)] with zero-point energy correction. The electronic structure of 6? FeCN has also been compared with that of 6? FeNC. At present, no experimental spectroscopic data are available for 6? FeCN. It is hoped that the present work will stimulate experimental investigations of this molecule.

Hirano, Tsuneo; Amano, Michiko; Mitsui, Yukari; Itono, Sachiko S.; Okuda, Rei; Nagashima, Umpei; Jensen, Per

2007-06-01

406

Nuclear Matrix Elements in the First-Forbidden Beta Decay of the Eu152 Ground State

The degree of circular polarization Pc(thetabetagamma) and the directional correlation W(thetabetagamma)=1+A2(W)P2(thetabetagamma) were measured in the 3-(1.49-MeV beta-)-->2+(0.344- MeV gamma)-->0+beta-gamma cascade leading from the ground state of Eu152 to the Sm152 ground state. The angle thetabetagamma is the angle between the beta and gamma momentum vectors. Representative values of Pc(thetabetagamma) measured at W¯=3.20 (in units mc2) for some average angles theta¯betagamma

P. Alexander; R. M. Steffen

1962-01-01

407

Ground State of Magnetic Dipoles on a Two-Dimensional Lattice: Structural Phases in Complex Plasmas

We study analytically and by molecular dynamics simulations the ground state configuration of a system of magnetic dipoles fixed on a two-dimensional lattice. We find different phases, in close agreement with previous results. Building on this result and on the minimum energy requirement we determine the equilibrium lattice configuration, the magnetic order (ferromagnetic versus antiferromagnetic), and the magnetic polarization direction of a system of charged mesoscopic particles with magnetic dipole moments, in the domain where the strong electrostatic coupling leads to a crystalline ground state. Orders of magnitudes of the parameters of the system relevant to possible future dusty plasma experiments are discussed.

Feldmann, J. D.; Kalman, G. J. [Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts, 02467 (United States); Hartmann, P. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California-San Diego, La Jolla, California, 92093 (United States)

2008-02-29

408

Analysis of the Energy Spectra of Ground States of Deformed Nuclei in rare-earth region

The 62Sm, 64Gd, 64Dy, 70Y b, 72Hf and 74W nuclei are classified as deformed nuclei. Low-lying bands are one of the most fundamental excitation modes in the energy spectra of deformed nuclei. In this paper a theoretical analysis of the experimental data within the phenomenological model is presented. The energy spectra of ground states are calculated. It is found the low-lying spectra of ground band states are in good agreement with the experimental data.

Abdurahim A. Okhunov; G. I. Turaeva; M. U. Khandaker; Noora B. Rosli

2014-05-28

409

Ground-state properties of third-row elements with nonlocal density functionals

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.

Bagno, P.; Jepsen, O.; Gunnarsson, O.

1989-07-15

410

Ground state mass of 81Kr and the solar neutrino problem

NASA Astrophysics Data System (ADS)

The 81Br(3He,t)81Kr, reaction has been used to determine an improved value for the ground state mass of 81Kr. A comparison is made with 51V(3He,t)51Cr and the implications for calibration of the proposed bromine solar neutrino detector are presented. NUCLEAR REACTIONS 81Br(3He,t)81Kr, 51V(3He,t)51Cr, 87Rb(3He,t)87Sr, 85Rb(3He,t)85Sr, E(3He)=24.7 MeV; Q values measured, ground state 81Kr mass inferred.

Kouzes, R. T.; Lowry, M. M.; Bennett, C. L.

1982-02-01

411

On Asymptotic Stability in Energy Space of Ground States for Nonlinear Schrödinger Equations

NASA Astrophysics Data System (ADS)

We consider nonlinear Schrödinger equations iu_t +? u +? (|u|^2)u=0 , text{for} (t,x)in mathbb{R}× mathbb{R}^d, where d ? 3 and ? 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.

Cuccagna, Scipio; Mizumachi, Tetsu

2008-11-01

412

New Journal of Physics An ellipsoidal mirror for focusing of neutral atomic and

-neutral, ground-state particles with very weak polarizability and no spin, such as ground-state helium-4 and neutral atom microscopy. The manipulation of charge-neutral beams of limited polarisability, spin time and we demonstrate focusing of a beam of neutral, ground state helium atoms down

Boyer, Edmond

413

The two-electron atomic systems. S-states

NASA Astrophysics Data System (ADS)

A simple Mathematica program for computing the S-state energies and wave functions of two-electron (helium-like) atoms (ions) is presented. The well-known method of projecting the Schrödinger equation onto the finite subspace of basis functions was applied. The basis functions are composed of the exponentials combined with integer powers of the simplest perimetric coordinates. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of results and computation time depend on the basis size. The precise energy values of 7-8 significant figures along with the corresponding wave functions can be computed on a single processor within a few minutes. The resultant wave functions have a simple analytical form consisting of elementary functions, that enables one to calculate the expectation values of arbitrary physical operators without any difficulties. Program summaryProgram title: TwoElAtom-S Catalogue identifier: AEFK_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFK_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10 185 No. of bytes in distributed program, including test data, etc.: 495 164 Distribution format: tar.gz Programming language: Mathematica 6.0; 7.0 Computer: Any PC Operating system: Any which supports Mathematica; tested under Microsoft Windows XP and Linux SUSE 11.0 RAM:?10 bytes Classification: 2.1, 2.2, 2.7, 2.9 Nature of problem: The Schrödinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or other physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple basis set in three perimetric coordinates. Method of projecting the two-electron Schrödinger equation (for atoms/ions) onto a subspace of the basis functions enables one to obtain the set of homogeneous linear equations F.C=0 for the coefficients C of the above expansion. The roots of equation det(F)=0 yield the bound energies. Restrictions: First, the too large length of expansion (basis size) takes the too large computation time giving no perceptible improvement in accuracy. Second, the order of polynomial ? (input parameter) in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Additional comments: The CPC Program Library includes "A program to calculate the eigenfunctions of the random phase approximation for two electron systems" (AAJD). It should be emphasized that this fortran code realizes a very rough approximation describing only the averaged electron density of the two electron systems. It does not characterize the properties of the individual electrons and has a number of input parameters including the Roothaan orbitals. Running time: ˜10 minutes (depends on basis size and computer speed)

Liverts, Evgeny Z.; Barnea, Nir

2010-01-01

414

NASA Astrophysics Data System (ADS)

The relation between scattering potential and ground-state energy shift of a helium atom (ion) close to a surface is investigated through use of a model of spatial limitation whereby the surface is represented by an infinitely rigid planar boundary. The model of an atom confined in a semi-infinite space with a plane boundary allows the variational evaluation of the ground-state energies and wave functions for He and He+ at different positions from the surface. The respective Born-Oppenheimer energy curves serve to model the ground-state energy shift for the elastic scattering channel in atom (ion) surface interactions. Independent calculations for the He-graphite and He-Al (111), (110), and (100) continuous planar potentials are carried out using high-quality ab initio calculations reported in the literature for the lowest He-C and He-Al binary interaction potentials. It is shown in this case that the He ground-state energy shift obtained within this model corresponds to an upper limit to the usual continuous planar potential. A discussion on the physical origin of this agreement is presented in terms of the static nature for the surface considered in both the hard-wall model and the atomic binary interactions used to construct the planar potentials, i.e., no account of the dynamic surface response is allowed as the projectile approaches. This is done by taking a reference pilot calculations based on electron nuclear dynamics for 100eV He (He+) -benzene (C6H6) interactions by considering the benzene molecule as a rough approximation to a local graphitic surface sector. It is found that the static planar potential provides a reasonable average representation of the interaction for neutral He, and supporting evidence for the use of the static O’Connor-Biersack potential is given. Finally, the effective scattering potential for He/He+-Al (111) is constructed through the use of the static planar potential for He-Al (111) considering the energy shift due to the classical image interaction for He+ approaching a perfectly Al (111) conducting plane before charge neutralization takes place. It is concluded that this scattering potential is directly related with the ground-state energy shift of the emerging already neutralized He atoms in He/He+-Al(111) grazing scattering experiments.

Cruz, S. A.; Ley-Koo, E.; Cabrera-Trujillo, R.

2008-09-01

415

Estimation of ground and excited state dipole moments of Oil Red O by solvatochromic shift methods

NASA Astrophysics Data System (ADS)

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 (?g) and excited state (?e) 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 ?g 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.

S?d?r, ?sa; Gülseven S?d?r, Yadigar

2015-01-01

416

Ultra-cold atomic matter and quantum information My group studies various many-body states of ultra cold atoms and investigates possible applications towards quantum computation. Two subjects studies of nematic Mott states and dimerized valence bond states of spin-one atoms. We also have

Plotkin, Steven S.

417

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

Bao, Weizhu, E-mail: mathbaowz@nus.edu.sg [Department of Mathematics and Center for Computational Science and Engineering, National University of Singapore, Singapore 119076 (Singapore)] [Department of Mathematics and Center for Computational Science and Engineering, National University of Singapore, Singapore 119076 (Singapore); Chern, I-Liang, E-mail: chern@math.nctu.edu.tw [Department of Applied Mathematics and Center of Mathematical Modeling and Scientific Computing, National Chiao Tung University, Hsinchu 30010, Taiwan (China) [Department of Applied Mathematics and Center of Mathematical Modeling and Scientific Computing, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Mathematics, National Taiwan University, Taipei 10617, Taiwan (China); Zhang, Yanzhi, E-mail: zhangyanz@mst.edu [Department of Mathematics and Statistics, Missouri University of Science and Technology, Rolla, MO 65409-0020 (United States)] [Department of Mathematics and Statistics, Missouri University of Science and Technology, Rolla, MO 65409-0020 (United States)

2013-11-15

418

Absolute line intensity measurements are performed on a metal-halide lamp. Several transitions of atomic and ionic Dy and atomic Hg are measured at different radial positions from which we obtain absolute atomic and ionic Dy intensity profiles. From these profiles we construct the radially resolved atomic state distribution function (ASDF) of the atomic and ionic Dy and the atomic Hg.

T. Nimalasuriya; A. J. Flikweert; W. W. Stoffels; M. Haverlag; J. J. A. M. van der Mullen; N. B. M. Pupat

2006-01-01

419

LOCAL ORDER AND MEAN VIBRATIONAL STATE OF ATOMS IN SUBSTITUTIONAL METALLIC SOLID SOLUTIONS

787. LOCAL ORDER AND MEAN VIBRATIONAL STATE OF ATOMS IN SUBSTITUTIONAL METALLIC SOLID SOLUTIONS, Czechoslovakia. RÃ©sumÃ©. 2014 Le carrÃ© moyen de l'amplitude effective des vibrations thermiques des atomes dans le vibrations of atoms in the usual Debye-Waller temperature factor has been calculated using the nearest

Boyer, Edmond

420

Accurate Potential Energy Curves for the Ground Electronic States of NeH^{+} and ArH^{+}

NASA Astrophysics Data System (ADS)

All available microwave and infrared spectroscopic line positions for the ground electronic states of the molecular cations NeH^{+} and ArH^{+} were employed in a direct potential fitting procedure to determine compact analytical potential curves and radial functions describing breakdown of the Born-Oppenheimer approximation. For NeH^{+}, 17 adjustable parameters were required to represent a total of 183 line positions for 4 isotopologues, whereas for ArH^{+}, 23 adjustable parameters were required to represent 440 line positions for 6 isotopologues. The MLR3 potential energy functional form was employed, taking full account of the proper 1/r{^4} limiting long-range dependence of the ion-atom dispersion energy interactions. Accurate vibrational energies, rotational constants and centrifugal distortion constants have been calculated for both diatomic cations.

Coxon, John A.; Hajigeorgiou, Photos G.

2013-06-01

421

To protect the photosynthetic apparatus against photo-damage in high sunlight, the photosynthetic antenna of oxygenic organisms can switch from a light-harvesting to a photoprotective mode through the process of non-photochemical quenching (NPQ). There is growing evidence that light-harvesting proteins of photosystem II participate in photoprotection by a built-in capacity to switch their conformation between light-harvesting and energy-dissipating states. Here we applied high-resolution Magic-Angle Spinning Nuclear Magnetic Resonance on uniformly (13)C-enriched major light-harvesting complex II (LHCII) of Chlamydomonas reinhardtii in active or quenched states. Our results reveal that the switch into a dissipative state is accompanied by subtle changes in the chlorophyll (Chl) a ground-state electronic structures that affect their NMR responses, particularly for the macrocycle (13)C4, (13)C5 and (13)C6 carbon atoms. Inspection of the LHCII X-ray structures shows that of the Chl molecules in the terminal emitter domain, where excited-state energy accumulates prior to further transfer or dissipation, the C4, 5 and 6 atoms are in closest proximity to lutein; supporting quenching mechanisms that involve altered Chl-lutein interactions in the dissipative state. In addition the observed changes could represent altered interactions between Chla and neoxanthin, which alters its configuration under NPQ conditions. The Chls appear to have increased dynamics in unquenched, detergent-solubilized LHCII. Our work demonstrates that solid-state Nuclear Magnetic Resonance is applicable to investigate high-resolution structural details of light-harvesting proteins in varied functional conditions, and represents a valuable tool to address their molecular plasticity associated with photoprotection. PMID:23466337

Pandit, Anjali; Reus, Michael; Morosinotto, Tomas; Bassi, Roberto; Holzwarth, Alfred R; de Groot, Huub J M

2013-06-01

422

We report on a novel experiment to generate non-classical atomic states via quantum non-demolition (QND) measurements on cold atomic samples prepared in a high-finesse ring cavity. The heterodyne technique developed for QND detection exhibits an optical shot-noise limited behavior for local oscillator optical power of a few hundred muW, and a detection bandwidth of several GHz. This detection tool is

S. Bernon; T. Vanderbruggen; R. Kohlhaas; A. Bertoldi; A. Landragin; P. Bouyer

2011-01-01

423

Rayleigh approximation to ground state of the Bose and Coulomb glasses

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. PMID:25592417

Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.

2015-01-01

424

Rayleigh approximation to ground state of the Bose and Coulomb glasses.

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. PMID:25592417

Ryan, S D; Mityushev, V; Vinokur, V M; Berlyand, L

2015-01-01

425

Rayleigh approximation to ground state of the Bose and Coulomb glasses

NASA Astrophysics Data System (ADS)

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.

Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.

2015-01-01

426

Resetting transcription factor control circuitry toward ground-state pluripotency in human.

Current human pluripotent stem cells lack the transcription factor circuitry that governs the ground state of mouse embryonic stem cells (ESC). Here, we report that short-term expression of two components, NANOG and KLF2, is sufficient to ignite other elements of the network and reset the human pluripotent state. Inhibition of ERK and protein kinase C sustains a transgene-independent rewired state. Reset cells self-renew continuously without ERK signaling, are phenotypically stable, and are karyotypically intact. They differentiate in vitro and form teratomas in vivo. Metabolism is reprogrammed with activation of mitochondrial respiration as in ESC. DNA methylation is dramatically reduced and transcriptome state is globally realigned across multiple cell lines. Depletion of ground-state transcription factors, TFCP2L1 or KLF4, has marginal impact on conventional human pluripotent stem cells but collapses the reset state. These findings demonstrate feasibility of installing and propagating functional control circuitry for ground-state pluripotency in human cells. PMID:25215486

Takashima, Yasuhiro; Guo, Ge; Loos, Remco; Nichols, Jennifer; Ficz, Gabriella; Krueger, Felix; Oxley, David; Santos, Fatima; Clarke, James; Mansfield, William; Reik, Wolf; Bertone, Paul; Smith, Austin

2014-09-11

427

Resetting Transcription Factor Control Circuitry toward Ground-State Pluripotency in Human

Summary Current human pluripotent stem cells lack the transcription factor circuitry that governs the ground state of mouse embryonic stem cells (ESC). Here, we report that short-term expression of two components, NANOG and KLF2, is sufficient to ignite other elements of the network and reset the human pluripotent state. Inhibition of ERK and protein kinase C sustains a transgene-independent rewired state. Reset cells self-renew continuously without ERK signaling, are phenotypically stable, and are karyotypically intact. They differentiate in vitro and form teratomas in vivo. Metabolism is reprogrammed with activation of mitochondrial respiration as in ESC. DNA methylation is dramatically reduced and transcriptome state is globally realigned across multiple cell lines. Depletion of ground-state transcription factors, TFCP2L1 or KLF4, has marginal impact on conventional human pluripotent stem cells but collapses the reset state. These findings demonstrate feasibility of installing and propagating functional control circuitry for ground-state pluripotency in human cells. PMID:25215486

Takashima, Yasuhiro; Guo, Ge; Loos, Remco; Nichols, Jennifer; Ficz, Gabriella; Krueger, Felix; Oxley, David; Santos, Fatima; Clarke, James; Mansfield, William; Reik, Wolf; Bertone, Paul; Smith, Austin

2014-01-01

428

NASA Astrophysics Data System (ADS)

The magnetization ground states (MGSs) for a nanosized Co hollow sphere, with the outer radius, R <50 nm, have been studied numerically by micromagnetic simulation using object oriented micromagnetic framework (OOMMF). In addition to the originally known single domain and vortex-curling states, a three dimensional "onion" state with a corresponding analytical expression is proposed and confirmed as one of the ground states. Two phase diagrams, one for a single crystalline and the other for a polycrystalline nanosphere, are obtained for the three MGSs. The result reveals that the magnetic anisotropy has a significant effect on the phase line in the diagrams. The finite temperature effect and the blocking properties of the nanosphere for the magnetization reversal are discussed.

Kong, Desheng; Wang, Siming; Chen, Chinping

2008-07-01

429

This paper discusses the excess polarizabilities upon excitation from the ground state to the first dipole-allowed excited state (S1) of diphenylpolyenes by using the time-dependent density functional theory. Two hybrid exchange-correlation (xc) potentials Becke-3 Lee-Yang-Parr (B3LYP) and Perdew-Burke-Ernzerhof (PBE1PBE) were employed. Our calculations indicate that the magnitude of the excess polarizability will decrease while the molecule evolves from the unrelaxed

J. F. Ye; H. Chen; H. Mizuseki; Y. Kawazoe

2007-01-01

430

Topological Characterization of Fractional Quantum Hall Ground States from Microscopic Hamiltonians

NASA Astrophysics Data System (ADS)

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.

Zaletel, Michael P.; Mong, Roger S. K.; Pollmann, Frank

2013-06-01

431

Topological characterization of fractional quantum Hall ground states from microscopic Hamiltonians.

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. PMID:25167520

Zaletel, Michael P; Mong, Roger S K; Pollmann, Frank

2013-06-01

432

The laboratory millimeter-wave spectrum of methyl formate in its ground torsional E state

NASA Technical Reports Server (NTRS)

Over 250 rotational transitions of the internal rotor methyl formate (HCOOCH3) in its ground v(t) = 0 degenerate (E) torsional substate have been measured in the millimeter-wave spectral region. These data and a number of E-state lines identified by several other workers have been analyzed using an extension of the classical principal-axis method in the high barrier limit. The resulting rotational constants allow accurate prediction of the v(t) = 0 E substate methyl formate spectrum below 300 GHz between states with angular momentum J not greater than 30 and rotational energy of not more than 350/cm. The calculated transition frequencies for the E state, when combined with the results of the previous analysis of the ground-symmetric, nondegenerate state, account for over 200 of the emission lines observed toward Orion in a recent survey of the 215-265 GHz band.

Plummer, G. M.; Herbst, E.; De Lucia, F. C.; Blake, G. A.

1986-01-01

433

Holonomic quantum computing in symmetry-protected ground states of spin chains

NASA Astrophysics Data System (ADS)

While solid-state devices offer naturally reliable hardware for modern classical computers, thus far quantum information processors resemble vacuum tube computers in being neither reliable nor scalable. Strongly correlated many body states stabilized in topologically ordered matter offer the possibility of naturally fault tolerant computing, but are both challenging to engineer and coherently control and cannot be easily adapted to different physical platforms. We propose an architecture which achieves some of the robustness properties of topological models but with a drastically simpler construction. Quantum information is stored in the symmetry-protected degenerate ground states of spin-1 chains, while quantum gates are performed by adiabatic non-Abelian holonomies using only single-site fields and nearest-neighbor couplings. Gate operations respect the symmetry, and so inherit some protection from noise and disorder from the symmetry-protected ground states.

Renes, Joseph M.; Miyake, Akimasa; Brennen, Gavin K.; Bartlett, Stephen D.

2013-02-01

434

Design of Solid-state Transmitter for Some HF Ground-wave Radar

According to the demand for the full solid-state transmitter in some high frequency ground-wave radar, it mainly discusses the design of the core parts of the transmitter, which are the power amplifier module as well the control and protection system. It presents a method to optimize the design of power amplifier module, some aspects related with both the final power

Hong Tao; Chen Baixiao; Zhang Shouhong

2006-01-01

435

Ground-state properties of microcavity polariton condensates at arbitrary excitation density

The ground state of microcavity polariton Bose-Einstein condensates (BEC's) is determined as a function of experimentally tunable parameters (the excitation density and the detuning of cavity photons), and also a material parameter (the ultraviolet cutoff). To obtain the ground state at an arbitrary excitation density, an interpolation method for the BEC-BCS crossover of excitonic insulators is extended to microcavity polariton systems in two or three dimensions. The ground state of the condensate changes from excitonic to photonic with an increase in the excitation density. This change is accompanied by several interesting features: (i) A laserlike input (excitation density) and output (photon density) relation with a sharp onset for largely detuned systems, which changes to that with a smooth onset for slightly detuned systems. (ii) The origin of the binding force of electron-hole pairs changes from Coulomb attraction to photon-mediated interactions, resulting in the formation of strongly bound pairs with a small radius, such as Frenkel excitons, in the photonic regime. The change in the ground state can be a crossover or a first-order transition, depending on the above-mentioned parameters, and is studied by plotting phase diagrams.

Kamide, Kenji; Ogawa, Tetsuo [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2011-04-15

436

The ground state problem for a quantum Hamiltonian model describing friction

The ground state problem for a quantum Hamiltonian model describing friction Laurent Bruneau friction introduced in [4]. This model consists of a particle which interacts with a bosonic reservoir is violated in the case of linear friction, but satis#28;ed when the friction force is proportional

437

A Simple Form for the Ground State Rotational Band of even-even Actinide nuclei

From Bohr-Mottelson model, a three parametric simple expression for the ground state rotational band of deformed even-even nuclei is deduced by incorporating the variable moment of inertia and the softness parameter. Our obtained results show good agreement with data in comparison with other existing models.

Mohamed E. Kelabi; Khaled A. Mazuz; Eman O. Farhat; Howida K. Elgowiry; Samira E. Abushnag

2010-01-03

438

The ground state energy of a polaron in a strong magnetic field

We show that the ground state of a polaron in a homogeneous magnetic field $B$ and its energy are described by an effective one-dimensional minimization problem in the limit $B\\to\\infty$. This holds both in the linear Fr\\"ohlich and in the non-linear Pekar model and makes rigorous an argument of Kochetov, Leschke and Smondyrev.

Rupert L. Frank; Leander Geisinger

2013-03-10

439

N'eel Order in the Ground State of Spin1/2 Heisenberg

N'eel Order in the Ground State of SpinÂ1/2 Heisenberg Antiferromagnetic Multilayer Systems J.O. Box 66318 05389Â970 S~ao Paulo Brazil July, 1996 Abstract We show existence of N'eel order by CAPES. y Supported by FAPESP. z Partially supported by CNPq. 1 #12; 1 Introduction The existence of N'eel

440

Transient state of polarization in optical ground wire caused by lightning and impulse current

NASA Astrophysics Data System (ADS)

This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.

Kurono, Masahiro; Isawa, K.; Kuribara, Masayuki

1996-08-01

441

First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo

First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo Arne Lu to or better than the best previous ab initio results can be obtained using the fixed-node quantum Monte Carlo, the dissociation energies are consistent with experimental values. The fixed-node quantum Monte Carlo method can

Anderson, James B.

442

A quantum Monte Carlo calculation of the ground state energy of the hydrogen molecule

A quantum Monte Carlo calculation of the ground state energy of the hydrogen molecule Carol A of the hydrogen molecule using the quantum Monte Carlo (QMC) method of solving the Schrodinger equation, without protons). Two different methods were employed: the diffusion quantum Monte Carlo (DQMC) method

Anderson, James B.

443

Searching for Ground States of Ising Spin Glasses with Hierarchical BOA and Cluster

1 Searching for Ground States of Ising Spin Glasses with Hierarchical BOA and Cluster Exact@physik.uniÂgoettingen.de Summary. This chapter applies the hierarchical Bayesian optimization algorithm (hBOA) to the problem. The performance of hBOA is comÂ pared to that of the simple genetic algorithm (GA) and the univariate marginal

Hartmann, Alexander K.

444

Reversible Tuning of the Heavy-Fermion Ground State in CeCoIn5

Cadmium doping the heavy-fermion superconductor CeCoIn5 at the percent level acts as an electronic tuning agent, sensitively shifting the balance between superconductivity and antiferromagnetism and opening new ambient-pressure phase space in the study of heavy-fermion ground states.

L. D. Pham; Tuson Park; S. Maquilon; J. D. Thompson; Z. Fisk

2006-01-01

445

Many-particle ground states and excitations in nanometer-size quantum structures

Many-particle ground states and excitations in nanometer-size quantum structures Axel Lorke *, Richard J. Luyken Sektion Physik, LMU Munchen, Geschwister-Scholl-Platz 1, 80539 Munchen, Germany Abstract 256Â±258 (1998) 424Â±430 * Corresponding author. Fax: +49 89 2180 3182; e-mail: axel

Lorke, Axel

446

Hylleraas-configuration-interaction study of the {sup 1}S ground state of neutral beryllium

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.

Sims, James S.; Hagstrom, Stanley A. [National Institute of Standards and Technology, Gaithersburg, Maryland 20878-9957 (United States); Departments of Chemistry and Computer Science, Indiana University, Bloomington, Indiana 47405 (United States)

2011-03-15

447

Relaxation and frequency shifts in the ground state of Rb-85

NASA Technical Reports Server (NTRS)

Results are presented on the relaxation and frequency shifts measured for the 0-0 transition of the ground state of Rb-85 at 3.03 GHz in various physical environments. These results include data on spin-exchange, buffer-gas, and wall interactions.

Vanier, J.; Simard, J.-F.; Boulanger, J.-S.

1974-01-01

448

Ground state of the asymmetric Rabi model in the ultrastrong coupling regime

We study the ground states of the single- and two-qubit asymmetric Rabi models, in which the qubit-oscillator coupling strengths for the counterrotating-wave and corotating-wave interactions are unequal. We take the transformation method to obtain the approximately analytical ground states for both models and numerically verify its validity for a wide range of parameters under the near-resonance condition. We find that the ground-state energy in either the single- or two-qubit asymmetric Rabi model has an approximately quadratic dependence on the coupling strengths stemming from different contributions of the counterrotating-wave and corotating-wave interactions. For both models, we show that the ground-state energy is mainly contributed by the counterrotating-wave interaction. Interestingly, for the two-qubit asymmetric Rabi model, we find that, with the increase of the coupling strength in the counterrotating-wave or corotating-wave interaction, the two-qubit entanglement first reaches its maximum then drops to zero. Furthermore, the maximum of the two-qubit entanglement in the two-qubit asymmetric Rabi model can be much larger than that in the two-qubit symmetric Rabi model.

Li-Tuo Shen; Zhen-Biao Yang; Mei Lu; Rong-Xin Chen; Huai-Zhi Wu

2014-09-20

449

Theory of Heating of the Quantum Ground State of Trapped Ions

Using a displacement operator formalism, I analyze the depopulation of the vibrational ground state of trapped ions. Two heating times, one characterizing short time behavior and the other long time behavior, are found. The long time behavior is analyzed for both single and multiple ions, and a formula for the relative heating rates of different modes is derived. The possibility

Daniel F. V. James

1998-01-01

450

On the ground state energy of the translation invariant Pauli-Fierz model

In this note, we determine the ground state energy of the translation invariant Pauli-Fierz model to subleading order $O(\\\\alpha^3)$ with respect to powers of the finestructure constant $\\\\alpha$, and prove rigorous error bounds of order $O(\\\\alpha^{4})$. A main objective of our argument is its brevity.

Jean-Marie Barbaroux; Thomas Chen; Vitali Vougalter; Semjon Vugalter

2007-01-01

451

Classical disordered ground states: Super-ideal gases and stealth and equi-luminous materials

Classical disordered ground states: Super-ideal gases and stealth and equi-luminous materials University, Princeton, New Jersey, 08544, USA 3 Princeton Institute for the Science and Technology focus on three classes of configurations with unique radiation scattering characteristics: i "stealth

Torquato, Salvatore

452

Ground state of a hydrogen ion molecule immersed in an inhomogeneous electron gas

In this work we have calculated the ground state energy of the hydrogen molecule, H2+, immersed in the highly inhomogeneous electron gas around a metallic surface within the local density approximation. The molecule is perturbed by the electron density of a crystalline surface of Au with the internuclear axis parallel to the surface. The surface spatial electron density is calculated

J. Diaz-Valdes; F. A. Gutierrez; A. R. Matamala; C. D. Denton; P. Vargas; J. E. Valdes

2007-01-01

453

Ground state of a hydrogen ion molecule immersed in an inhomogeneous electron gas

In this work we have calculated the ground state energy of the hydrogen molecule, H2+, immersed in the highly inhomogeneous electron gas around a metallic surface within the local density approximation. The molecule is perturbed by the electron density of a crystalline surface of Au ?100? with the internuclear axis parallel to the surface. The surface spatial electron density is

J. Diaz-Valdes; F. A. Gutierrez; A. R. Matamala; C. D. Denton; P. Vargas; J. E. Valdes

2007-01-01

454

Evolution of the Hox gene complex from an evolutionary ground state.

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 localized outside of the cluster. PMID:19651301

Gehring, Walter J; Kloter, Urs; Suga, Hiroshi

2009-01-01

455

Using superconducting quantum circuit elements, we propose an approach to experimentally construct a Kitaev lattice, which is an anisotropic spin model on a honeycomb lattice with three types of nearest-neighbor interactions and having topologically protected ground states. We study two particular parameter regimes to demonstrate both vortex and bond-state excitations. Our proposal outlines an experimentally realizable artificial many-body system that exhibits exotic topological properties.

J. Q. You; Xiao-Feng Shi; Xuedong Hu; Franco Nori

2009-12-03

456

Cooling a micro-mechanical resonator to its ground state by measurement back-action

We present an analysis of the cooling of a micro-mechanical resonator by means of measurements and back action. The measurements are performed via the coupling to a Cooper-pair box, and although the coupling does not lead to net cooling, the extraction of information and hence entropy from the system leads to a pure quantum state. Under suitable circumstances, the states become very close to coherent states, conditioned on the measurement record, and can hence be displaced to the oscillator ground state.

Christian Bergenfeldt; Klaus Molmer

2009-06-10

457

Detecting two-dimensional symmetry-protected topological order in a ground-state wave function

NASA Astrophysics Data System (ADS)

Symmetry-protected topological states cannot be deformed to a trivial state so long as the symmetry is preserved, yet there is no local order parameter that can distinguish them from a trivial state. We demonstrate how to detect whether a two-dimensional ground state has symmetry-protected topological order; the measurements play a similar role as the topological entanglement entropy does for detecting anyons. For any finite Abelian onsite symmetry, the measurement completely determines the third cohomology class that characterizes the order. The proposed measurement is validated numerically using the infinite density matrix renormalization group for a model with Z2 symmetry-protected order.

Zaletel, Michael P.

2014-12-01

458

Steady-state light-induced forces for atom lithography

The light-induced force on an atom is calculated for an arbitrary field configuration, taking into account the spontaneous emission and optical pumping processes as well as the degeneracy of atomic energy levels. Two types of the optical transitions are analyzed: J{yields}J with J a half-integer and J{yields}J+1 with J an arbitrary. Though the force is not potential in the general case, we introduce a scalar function {psi}, which plays a role of the potential energy, determining regions of localization of atoms. Applications of these results to atom nanolithography are discussed.

Bezverbny, A.V.; Prudnikov, O.N.; Taichenachev, A.V.; Tumaikin, A.M.; Yudin, V.I. [Maritime State University, Vladivostok 690059 (Russian Federation); Novosibirsk State University, Pirogova 2, Novosibirsk 630090 (Russian Federation); Institute of Laser Physics SB RAS, Lavrentyeva 13/3, Novosibirsk 630090 (Russian Federation)

2005-08-15

459

Ground and Excited Electronic State Analysis of PrF(2+) and PmF(2+)

The ground state and excited state manifolds are computed for PrF(2+) and PmF(2+) at the CASSCF (n,8) level of theory where the active space spans the Ln 4f orbitals as well as the F 2pz orbital. Dynamical correlation is included using second-order multireference quasidegenerate perturbation theory (MCQDPT2). The spin-orbit multiplets for each of the excited states are resolved, and spin-orbit coupling constants are computed using the Breit-Pauli spin-orbit operator. Equilibrium geometries for each of the ground and excited states are computed, and the nature of the Ln-F bond is examined. Potential energy curves for the lowest four triplet states and lowest two quintet states are computed for PrF(2+), which split into 14 levels upon application of the spin-orbit Hamiltonian. Likewise, the lowest six quintet states are computed for PmF(2+) as well as the lowest triplet state and the lowest two septet states. These nine states split into 43 terms upon application of the spin-orbit Hamiltonian. PMID:25397590

Schoendorff, George; Chi, Benjamin; Ajieren, Hans; Wilson, Angela K

2014-11-26

460

NASA Technical Reports Server (NTRS)

The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.

Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon; DiFilippo, Frank J.

1996-01-01