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1

Trapping cold ground state argon atoms.

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)??C?m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)??cm(3)?s(-1). PMID:25396366

Edmunds, P D; Barker, P F

2014-10-31

2

Trapping Cold Ground State Argon Atoms

NASA Astrophysics Data System (ADS)

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4 s [3 /2 ]2 state to be (7.3 ±1.1 ) ×10-39 C m2/V . Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3 ±0.8 )×10-10 cm3 s-1 .

Edmunds, P. D.; Barker, P. F.

2014-10-01

3

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

4

A Dynamic Electric Trap for Ground-State Atoms

A new type of trap for ground-state atoms is proposed. It is based on the balancing of gravity and the electric-dipole attraction between the polarisable atom and a slowly oscillating electric charge. The stability of this dynamic trap is predicted for a narrow range of operating conditions. However, practical considerations result in a trap depth only comparable to the lowest

E. Riis; S. M. Barnett

1993-01-01

5

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

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

Photoionization of potassium atoms from the ground and excited states

The Dirac-based B-spline R-matrix method is used to investigate the photoionization of atomic potassium from the 4s ground and 4p, 5s-7s, 3d-5d excited states. The effect of the core polarization by the outer electron is included through the polarized pseudostates. Besides the dipole core polarization, we also found a noticeable influence of the quadrupole core polarization. We obtained excellent agreement with experiment for cross sections of the 4s photoionization, including accurate description of the near-threshold Cooper-Seaton minimum. We also obtained close agreement with experiment for the 4p photoionization, but there are unexpectedly large discrepancies with available experimental data for photoionization of the 5d and 7s excited states.

Zatsarinny, O. [Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311 (United States); Tayal, S. S. [Department of Physics, Clark Atlanta University, Atlanta, Georgia 30314 (United States)

2010-04-15

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

Raman cooling imaging: Detecting single atoms near their ground state of motion

NASA Astrophysics Data System (ADS)

We demonstrate imaging of neutral atoms via the light scattered during continuous Raman sideband cooling. We detect single atoms trapped in optical tweezers while maintaining a significant motional ground-state fraction. The techniques presented provide a framework for single-atom resolved imaging of a broad class of atomic species.

Lester, B. J.; Kaufman, A. M.; Regal, C. A.

2014-07-01

11

Differential polarizability in the ground state of the hydrogen atom

The differential polarizabilities in the ground states of hydrogen and the alkalis are discussed. General angular momentum arguments are used to separate the contributions from the different hyperfine-structure interactions. Three separate polarizabilities are introduced and their contributions to the quadratic Stark effect are given. Explicit expressions for the polarizabilities are found for hydrogen.

P G H Sandars

1967-01-01

12

The linear Stark effect shows that the first excited state of hydrogen atom has large permanent electric dipole moment (EDM), d(H)=3eao (ao is Bohr radius). Using special capacitors our experiments discovered that the ground state K, Rb or Cs atom is polar atom with a large EDM of the order of eao as hydrogen atom of excited state. Their capacitance(C)

Pei-Lin You

2008-01-01

13

Cooling a Single Atom in an Optical Tweezer to Its Quantum Ground State

NASA Astrophysics Data System (ADS)

We report cooling of a single neutral atom to its three-dimensional vibrational ground state in an optical tweezer. After employing Raman sideband cooling for tens of milliseconds, we measure via sideband spectroscopy a three-dimensional ground-state occupation of about 90%. We further observe coherent control of the spin and motional state of the trapped atom. Our demonstration shows that an optical tweezer, formed simply by a tightly focused beam of light, creates sufficient confinement for efficient sideband cooling. This source of ground-state neutral atoms will be instrumental in numerous quantum simulation and logic applications that require a versatile platform for storing and manipulating ultracold single neutral atoms. For example, these results will improve current optical-tweezer experiments studying atom-photon coupling and Rydberg quantum logic gates, and could provide new opportunities such as rapid production of single dipolar molecules or quantum simulation in tweezer arrays.

Kaufman, A. M.; Lester, B. J.; Regal, C. A.

2012-10-01

14

Hyperfine splitting in non-relativistic QED: uniqueness of the dressed hydrogen atom ground state

We consider a free hydrogen atom composed of a spin-1/2 nucleus and a spin-1/2 electron in the standard model of non-relativistic QED. We study the Pauli-Fierz Hamiltonian associated with this system at a fixed total momentum. For small enough values of the fine-structure constant, we prove that the ground state is unique. This result reflects the hyperfine structure of the hydrogen atom ground state.

Laurent Amour; Jérémy Faupin

2011-12-02

15

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

16

Using the Voter and Chen version of the embedded-atom model, we performed molecular-dynamics simulations to determine the ground-state atomic configurations of Nin-xAlx clusters (n=13, 19, and 55) for all concentrations x. The lowest-energy structures of both the bimetallic and the pure (x=0 and n) clusters are icosahedral. In general, there is a tendency for Al atoms to be segregated at

C. Rey; J. García-Rodeja; L. J. Gallego

1996-01-01

17

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

18

Ground-State Cooling of a Single Atom at the Center of an Optical Cavity

NASA Astrophysics Data System (ADS)

A single neutral atom is trapped in a three-dimensional optical lattice at the center of a high-finesse optical resonator. Using fluorescence imaging and a shiftable standing-wave trap, the atom is deterministically loaded into the maximum of the intracavity field where the atom-cavity coupling is strong. After 5 ms of Raman sideband cooling, the three-dimensional motional ground state is populated with a probability of (89±2)%. Our system is the first to simultaneously achieve quantum control over all degrees of freedom of a single atom: its position and momentum, its internal state, and its coupling to light.

Reiserer, Andreas; Nölleke, Christian; Ritter, Stephan; Rempe, Gerhard

2013-05-01

19

Ground-state cooling of a single atom at the center of an optical cavity.

A single neutral atom is trapped in a three-dimensional optical lattice at the center of a high-finesse optical resonator. Using fluorescence imaging and a shiftable standing-wave trap, the atom is deterministically loaded into the maximum of the intracavity field where the atom-cavity coupling is strong. After 5 ms of Raman sideband cooling, the three-dimensional motional ground state is populated with a probability of (89±2)%. Our system is the first to simultaneously achieve quantum control over all degrees of freedom of a single atom: its position and momentum, its internal state, and its coupling to light. PMID:23767719

Reiserer, Andreas; Nölleke, Christian; Ritter, Stephan; Rempe, Gerhard

2013-05-31

20

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

21

The ground state properties of spin-aligned atomic hydrogen, deuterium, and tritium

NASA Technical Reports Server (NTRS)

The internal energy, pressure, and compressibility of ground-state, spin-aligned atomic hydrogen, deuterium, and tritium are calculated assuming that all pair interactions occur via the atomic triplet (spin-aligned) potential. The conditions required to obtain atomic hydrogen and its isotopes in bulk are discussed; such a development would be of value in propulsion systems because of the light mass and energetic recombination of atomic hydrogen. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K, and that tritium forms a liquid with a binding energy of approximately -0.75 K per atom at a molar volume of 130 cu cm per mole. The pair distribution function for these systems is calculated, and the predicted superfluid behavior of atomic triplet hydrogen and tritium is briefly discussed.

Etters, R. D.; Dugan, J. V., Jr.; Palmer, R. W.

1975-01-01

22

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

23

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

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. PMID:25557504

Xue, Peng; Zhan, Xiang; Bian, Zhihao

2015-01-01

24

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

25

The 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, can 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 or a superfluid, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the system is superfluid. These states could be realized in existing experimental setups.

Sonia Fernández-Vidal; Gabriele De Chiara; Jonas Larson; Giovanna Morigi

2010-01-26

26

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

27

Auxiliary Field Quantum Monte Carlo Study of Ground State Properties of Atoms and Molecules

NASA Astrophysics Data System (ADS)

We apply a recently developed quantum Monte Carlo (QMC) method ootnotetextShiwei Zhang, Henry Krakauer, Phys. Rev. Lett. 90. 136401 (2003). to calculate the ground state properties of several atoms and molecules. The QMC method projects the many-body ground state from a trial state by random walks in the space of Slater determants. The Hubbard-Stratonovich transformation is employed to decouple the Coulomb interaction between electrons. A trial wave function |?T> is used in the approximation to control the phase problem in QMC. We also carry out Hartree-Fock (HF) and density functional theory (with the local density approximation (LDA)) calculations. The generated single Slater determinant wave functions are used as |?T> in QMC. The dissociation and ionization energies are calculated for Aluminum, Silicon, Phosphorous, Sulfur, Chlorine and Arsenic atoms and molecules. The results are in good agreement with experimental values.

Suewattana, Malliga; Zhang, Shiwei; Krakauer, Henry; Walter, Eric

2005-03-01

28

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

29

Vibrational ground state cooling of a neutral atom in a tightly focused optical dipole trap

NASA Astrophysics Data System (ADS)

Recent experiments have shown that an efficient interaction between a single trapped atom and light can be established by concentrating light field at the location of the atom by focusing [1-3]. However, to fully exploit the benefits of strong focusing one has to localize the atom at the maximum of the field strength [4]. The position uncertainty due to residual kinetic energy of the atom in the dipole trap (depth 1mK) after molasses cooling is significant (few 100 nm). It limits the interaction between a focused light mode and an atom already for moderate focusing strength [2]. To address this problem we implement a Raman Sideband cooling technique, similar to the one commonly used in ion traps [5], to cool a single ^87Rb atom to the ground state of the trap. We have cooled the atom along the transverse trap axis (trap frequency ??=55,), to a mean vibrational state n?=0.55 and investigate the impact on atom-light interfaces.[4pt] [1] M. K. Tey, et al., Nature Physics 4 924 (2008)[0pt] [2] M. K. Tey et. al., New J. Phys. 11, 043011 (2009)[0pt] [3] S.A. Aljunid et al., PRL 103, 153601 (2009)[0pt] [4] C. Teo and V. Scarani Opt. Comm. 284 4485-4490 (2011)[0pt] [5] C. Monroe et al., PRL 75, 4011 (1995)

Aljunid, Syed; Maslennikov, Gleb; Paesold, Martin; Durak, Kadir; Leong, Victor; Kurtsiefer, Christian

2012-06-01

30

NASA Astrophysics Data System (ADS)

We report electromagnetically induced transparency (EIT) in cold 85Rb atoms, trapped in the lower hyperfine level F = 2, of the ground state 52S1/2 (Tiwari V B et al 2008 Phys. Rev. A 78 063421). Two steady-state ?-type systems of hyperfine energy levels are investigated using probe transitions into the levels F' = 2 and F' = 3 of the excited state 52P3/2 in the presence of coupling transitions F = 3 ? F' = 2 and F = 3 ? F' = 3, respectively. The effects of uncoupled magnetic sublevel transitions and coupling field's Rabi frequency on the EIT signal from these systems are studied using a simple theoretical model.

Tiwari, V. B.; Singh, S.; Rawat, H. S.; Singh, Manoranjan P.; Mehendale, S. C.

2010-05-01

31

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

32

Correlated wave functions for the ground and some excited states of the iron atom.

We study the states arising from the [Ar]4s(2)3d6 and [Ar]4s(1)3d7 configurations of iron atom with explicitly correlated wave functions. The variational wave function is the product of the Jastrow correlation factor times a model function obtained within the parametrized optimized effective potential framework. A systematic analysis of the dependence of both the effective potential and the correlation factor on the configuration and on the term is carried out. The ground state of both, the cation, Fe+, and anion, Fe-, are calculated with correlated wave functions and the ionization potential and the electron affinity are obtained. PMID:16674212

Buendía, E; Gálvez, F J; Sarsa, A

2006-04-21

33

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

34

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

35

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

36

Ground-state cooling of an oscillator in a hybrid atom-optomechanical system.

We investigate a hybrid quantum system combining cavity quantum electrodynamics and optomechanics, where a photon mode is coupled to a four-level tripod atom and to a mechanical mode via radiation pressure. We find that within the single-photon optomechanics and Lamb-Dicke limit, the presence of the tripod atom alters the optical properties of the cavity radiation field drastically, and gives rise to completely quantum destructive interference effects in the optical scattering. The heating rate can be dramatically suppressed via utilizing the completely destructive interference involving atom, photon and phonon, and the obtained result is analogous to that of the resolved sideband regime. The heating process is only connected to the scattering of cavity damping path, which is also far-off resonance. Meanwhile, the cooling rate assisted by the atomic transitions can be significantly enhanced, where the cooling process occurs through the cavity and atomic dissipation paths. Finally, the ground-state cooling of the movable mirror is achievable and even more robust to heating process and thermal noise. PMID:25321216

Yi, Zhen; Li, Gao-xiang; Wu, Shao-ping; Yang, Ya-ping

2014-08-25

37

NASA Astrophysics Data System (ADS)

The ground states of the ultracold spin-1 atoms trapped in a deep one-dimensional double-well optical superlattice in a weak magnetic field are obtained. It is shown that the ground-state diagrams of the reduced double-well model are remarkably different for the antiferromagnetic and ferromagnetic condensates. The transition between the singlet state and nematic state is observed for the antiferromagnetic interaction atoms, which can be realized by modulating the tunneling parameter or the quadratic Zeeman energy. An experiment to distinguish the different spin states is suggested.

Zheng, Gong-Ping; Qin, Shuai-Feng; Wang, Shou-Yang; Jian, Wen-Tian

2013-04-01

38

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

NASA Astrophysics Data System (ADS)

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|.

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

2014-12-01

39

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

40

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

NASA Astrophysics Data System (ADS)

Most of the important chemical reactions which occur in the very high temperature air produced around space vehicles as they enter the atmosphere were investigated both experimentally and theoretically, to some extent at least. One remaining reaction about which little is known, and which could be quite important at the extremely high temperatures that will be produced by the class of space vehicles now contemplated - such as the AOTV - is the excitation of bound electron states due to collisions between heavy gas particles. Rates of electronic excitation due to free electron collisions are known to be very rapid, but because these collisions quickly equilibrate the free and bound electron energy, the approach to full equilibrium with the heavy particle kinetic energy will depend primarily on the much slower process of bound electron excitation in heavy particle collisions and the subsequent rapid transfer to free electron energy. This may be the dominant mechanism leading to full equilibrium in the gas once the dissociation process has depleted the molecular states so the transfer between molecular vibrational energy and free electron energy is no longer available as a channel for equilibration of free electron and heavy particle kinetic energies. Two mechanisms seem probable in electronic excitation by heavy particle impact. One of these is the collision excitation and deexcitation of higher electronic states which are Rydberg like. A report, entitled 'Semi-Classical Theory of Electronic Excitation Rates', was submitted previously. This presented analytic expressions for the transition probabilities, assuming that the interaction potential is an exponential repulsion with a perturbation ripple due to the dipole-induced dipole effect in the case of neutral-neutral collisions, and to the ion-dipole interaction in the case of ion-neutral collisions. However the above may be, there is little doubt that excitation of ground state species by collision occurs at the point where the initial and final potentials cross, or at least come very close. Therefore, this mechanism would be applicable to the case where a gas is initially at very low temperature suddenly subjected to high energy heavy particle bombardment. This situation would model the measurement of excitation cross section by molecular beam techniques, for example. The purpose is to report values of cross sections and rate coefficients for collision excitation of ground state atoms estimated with the Landau-Zener transition theory and to compare results with measurement of excitation cross sections for a beam of Hydrogen atoms impacting Argon atom targets. Some very dubious approximations are used, and the comparison with measurement is found less than ideal, but results are at least consistent within order of magnitude. The same model is then applied to the case of N-N atom collisions, even though the approximations then become even more doubtful. Still the rate coefficients obtained are at least plausible in both magnitude and functional form, and as far as I am aware these are the only estimates available for such rate coefficients.

Hansen, C. Frederick

1993-06-01

41

Hydrogen maser frequency shifts, caused by the multiple quantum transition nonlinearities of a resonant multiple frequency excitation of the atomic hydrogen four level ground state system have been investigated. The oscillation characteristics of hydrogen maser operation with simultaneously excited, low frequency Deltam F =±1 transitions between the F=1 states of the atomic hydrogen ground state have been analysed theoretically and

Harro G. Andresen

1968-01-01

42

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

43

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

44

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 variant Planck's over 2 h omega a/2kB = 13 microK is occupied with probability P0 approximately 0.95. PMID:17026303

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

2006-08-25

45

Large Ground-State Entropy Changes for Hydrogen Atom Transfer Reactions of Iron Complexes

Reported herein are the hydrogen atom transfer (HAT) reactions of two closely related dicationic iron tris ?-diimine complexes. FeII(H2bip) (iron(II) tris[2,2?-bi-1,4,5,6-tetra-hydropyrimidine]diperchlorate) and FeII(H2bim) (iron(II) tris[2,2?-bi-2-imidazoline]diperchlorate) both transfer H• to TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) to yield the hydroxylamine, TEMPO-H, and the respective deprotonated iron(III) species, FeIII(Hbip) or FeIII(Hbim). The ground-state thermodynamic parameters in MeCN were determined for both systems using both static and kinetic measurements. For FeII(H2bip) + TEMPO: ?G° = ?0.3 ± 0.2 kcal mol?1, ?H° =?9.4 ± 0.6 kcal mol?1, ?S° = ?30 ± 2 cal mol?1 K?1. For FeII(H2bim) + TEMPO: ?G° = 5.0 ± 0.2 kcal mol?1, ?H° = ?4.1 ± 0.9 kcal mol?1, ?S° = ?30 ± 3 cal mol?1 K?1. The large entropy changes for these reactions, |T?S°| = 9 kcal mol?1 at 298 K, are exceptions to the traditional assumption that ?S° ? 0 for simple HAT reactions. Various studies indicate that hydrogen-bonding, solvent effects, ion-pairing, and iron spin-equilibria do not make major contributions to the observed ?S°HAT. Instead, this effect arises primarily from changes in vibrational entropy upon oxidation of the iron center. Measurement of the electron transfer half-reaction entropy, |?S° Fe(H2bim)/ET| = 29 ± 3 cal mol?1 K?1, is consistent with a vibrational origin. This conclusion is supported by UHF/6-31G* calculations on the simplified reaction [FeII(H2N=CHCH=NH2)2(H2bim)]2+•••ONH2 ? [FeII(H2N=CHCH=NH2)2(Hbim)]2+•••HONH2. The discovery that ?S°HAT can deviate significantly from zero has important implications on the study of HAT and proton-coupled electron transfer (PCET) reactions. For instance, these results indicate that free energies, rather than enthalpies, should be used to estimate the driving force for HAT when transition metal centers are involved. PMID:17402735

Mader, Elizabeth A.; Davidson, Ernest R.

2008-01-01

46

Hydrogen maser frequency shifts, caused by the multiple quantum transition nonlinearities of a resonant multiple frequency excitation of the atomic hydrogen four level ground state system have been investigated. The oscillation characteristics of hydrogen maser operation with simultaneously excited, low frequency?mF=±1 transitions between theF=1 states of the atomic hydrogen ground state have been analysed theoretically and explicit formulas for hydrogen

Harro G. Andresen

1968-01-01

47

Ground Levels and Ionization Energies for the Neutral Atoms

National Institute of Standards and Technology Data Gateway

SRD 111 Ground Levels and Ionization Energies for the Neutral Atoms (Web, free access) Data for ground state electron configurations and ionization energies for the neutral atoms (Z = 1-104) including references.

48

The properties of the electronic ground state of the polar and paramagnetic europium-$S$-state-atom molecules have been investigated. Ab initio techniques have been applied to compute the potential energy curves for the europium-alkali-metal-atom, Eu$X$ ($X$=Li, Na, K, Rb, Cs), europium-alkaline-earth-metal-atom, Eu$Y$ ($Y$=Be, Mg, Ca, Sr, Ba), and europium-ytterbium, EuYb, molecules in the Born-Oppenheimer approximation for the high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within the small-core energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large internuclear distances $C_6$ are also reported. The EuK, EuRb, and EuCs molecules are examples of species poss...

Tomza, Micha?

2014-01-01

49

NASA Astrophysics Data System (ADS)

The properties of the electronic ground state of the polar and paramagnetic europium-S-state-atom molecules have been investigated. Ab initio techniques have been applied to compute the potential energy curves for the europium-alkali-metal-atom, EuX(X=Li,Na,K,Rb,Cs), europium-alkaline-earth-metal-atom, EuY(Y=Be,Mg,Ca,Sr,Ba), and europium-ytterbium, EuYb, molecules in the Born-Oppenheimer approximation for the high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within the small-core energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large internuclear distances C6 are also reported. The EuK, EuRb, and EuCs molecules are examples of species possessing both large electric and magnetic dipole moments making them potentially interesting candidates for ultracold many-body quantum simulations when confined in an optical lattice in combined electric and magnetic fields.

Tomza, Micha?

2014-08-01

50

-Atom Temperatures in a Microwave Plasma Diamond Deposition Reactor A. Gicquel (~,*), M. Chenevier (~), Y. Breton in a microwave plasma diamond deposition reactor as a function of a low percentage of methane introducedD diffusive non equilibrium H2 plasma flow model and to ground electronic state rotational temperatures

Boyer, Edmond

51

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

52

NASA Astrophysics Data System (ADS)

A new hypothetical molecule, tetracyclo [3.3.3.1 3,101 7,10]tridecane, named bowlane, which should possess a pyramidal carbon atom in the ground state, is proposed. The influence of ring enlargement on the pyramidality of the central atom is estimated on the basis of molecular mechanics. The difference between inverted and pyramidal carbon atoms is briefly discussed and a measure of planarization and pyramidality of a tetracoordinated carbon atom is proposed.

Dodziuk, Helena

1990-10-01

53

In this study, we investigate the structure of the polar alkali-metal-atom-strontium diatomic molecules as possible candidates for the realization of samples of ultracold polar molecular species not yet investigated experimentally. Using a quantum chemistry approach based on effective core potentials and core polarization potentials, we model these systems as effective three-valence-electron systems, allowing for calculation of electronic properties with full configuration interaction. The potential curve and the permanent dipole moment of the {sup 2}{Sigma}{sup +} ground state are determined as functions of the internuclear distance for LiSr, NaSr, KSr, RbSr, and CsSr molecules. These molecules are found to exhibit a significant permanent dipole moment, though smaller than those of the alkali-metal-atom-Rb molecules.

Guerout, R. [Laboratoire Kastler-Brossel, CNRS, ENS, Univ Pierre et Marie Curie case 74, Campus Jussieu, F-75252 Paris Cedex 05 (France); Aymar, M.; Dulieu, O. [Laboratoire Aime Cotton, CNRS, UPR3321, Bat. 505, Univ Paris-Sud, F-91405 Orsay Cedex (France)

2010-10-15

54

NASA Astrophysics Data System (ADS)

We employ the closed-shell perturbed relativistic coupled-cluster (RCC) theory developed by us earlier [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.77.062516 77, 062516 (2008)] to evaluate the ground-state static electric dipole polarizabilities (?s) of several atomic systems. In this work, we have incorporated a class of higher-order many-body effects in our calculations that had not been taken into account in the above paper. We highlight their importance in improving the accuracies of ?s. We also calculate the ground state ?s of the inert gas atoms and several isoelectronic singly and doubly charged ions in order to make a comparative study of the trends of the correlation effects. Furthermore, we have developed a method to construct intermediate diagrams that are required for the computations of the unperturbed single and doubl coupled-cluster amplitudes. Our RCC results are compared with those of many-body perturbation theory at different orders to demonstrate the importance of higher-order correlation effects for the accurate determination of (?s) of the systems that we have considered.

Singh, Yashpal; Sahoo, B. K.; Das, B. P.

2013-12-01

55

A calculation of the ground-state energy and average distance between particles in the nonsymmetric muonic {sup 3}He atom is given. We have used a wave function with one free parameter, which satisfies boundary conditions such as the behavior of the wave function when two particles are close to each other or far away. In the proposed wave function, the electron-muon correlation function is also considered. It has a correct behavior for r{sub 12} tending to zero and infinity. The calculated values for the energy and expectation values of r{sup 2n} are compared with the multibox variational approach and the correlation function hyperspherical harmonic method. In addition, to show the importance and accuracy of approach used, the method is applied to evaluate the ground-state energy and average distance between the particles of nonsymmetric muonic {sup 4}He atom. Our obtained results are very close to the values calculated by the mentioned methods and giving strong indications that the proposed wave functions, in addition to being very simple, provide relatively accurate values for the energy and expectation values of r{sup 2n}, emphasizing the importance of the local properties of the wave function.

Eskandari, M.R. [Physics Department, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Fundamental Sciences of Tabriz (Iran, Islamic Republic of); Rezaie, B. [Physics Department, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

2005-07-15

56

number s : 34.20.Cf, 34.50.Rk, 32.80.Pj I. INTRODUCTION Recent developments in laser cooling and trapping that it is possible to trap and cool alkali-earth metal atoms, such as magnesium 3 , calcium 4,5 , and strontium 4Cold collisions of ground-state calcium atoms in a laser field: A theoretical study Be

Bussery-Honvault, Béatrice

57

A large 25-cps voltage is applied across two parallel metal plates situated between the loops of a Ramsey double-hairpin structure, in an atomic-beam magnetic-resonance apparatus adjusted to observe flop-in transitions. A beam of cesium atoms passes between the plates and is subject to an electric field of about 5×104 V\\/cm. The flop-in transition (4,-3)(4,-4) is observed at a low magnetic

J. P. Carrico; A. Adler; M. R. Baker; S. Legowski; E. Lipworth; P. G. Sandars; T. S. Stein; M. C. Weisskopf

1968-01-01

58

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

59

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

60

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

61

On the reaction of ground-state nitrogen atoms with bromomethyl radicals: A computational study

NASA Astrophysics Data System (ADS)

A computational study of the reaction of N(4S) with CH2Br radicals has been carried out. The reaction starts through the formation of a relatively stable intermediate which does not involve an energy barrier. The two most exothermic products are those resulting from the release of a bromine atom, H2C = N + Br and trans-HC = NH + Br. A kinetic study, within the framework of the statistical theories, shows that the most exothermic product, namely H2C = N + Br, is also the preferred product under kinetic control, whereas only minor fractions of HBrCN + H are predicted at all temperatures. Therefore, the mechanistic characteristics observed for the N(4S) + CH2Br reaction are very similar to the N(4S) + CH2Cl reaction, but quite different from those found in the case of N(4S) + CH2F, where the preferred channel corresponds to formation of HFCN through elimination of a hydrogen atom. The rate coefficient for the title reaction is estimated to be about 9 × 10-13 cm3 s-1 molecule-1 at 300 K, showing that should proceed with a high efficiency.

Cimas, Alvaro; Rayón, Víctor M.; Aschi, Massimiliano; Barrientos, Carmen; Sordo, José A.; Largo, Antonio

2006-03-01

62

Trilobites and other molecular animals: How Rydberg-electrons catch ground state atoms

NASA Astrophysics Data System (ADS)

We report on laser spectroscopy results obtained in a dense and frozen Rydberg gas. Novel molecular bonds resulting in ultralong-range Rydberg dimers were predicted [1] and dimers as well as trimers in different vibrational states were found [2]. Some of these states are predicted to be bound by quantum reflection. Lifetime measurements confirm this prediction. Coherent superposition between free and bound states have been investigated [3]. Recently we have also confirmed that in an electric field these homonuclear molecules develop a permanent dipole moment [4]. [4pt] [1] C. H. Greene, A. S. Dickinson, and H. R. Sadeghpour, Phys. Rev. Lett. 85, 2458 (2000). [0pt] [2] V. Bendkowsky, B. Butscher, J. Nipper, J. P. Shaffer, R. L"ow, T. Pfau, Nature 458, 1005 (2009), V. Bendkowsky, B. Butscher, J. Nipper, J. Balewski, J. P. Shaffer, R. L"ow, T. Pfau, W. Li, J. Stanojevic, T. Pohl, and J. M. Rost, Phys. Rev. Lett. 105, 163201 (2010). [0pt] [3] B. Butscher, J. Nipper, J. B. Balewski, L. Kukota, V. Bendkowsky, R. L"ow, and T. Pfau Nature Physics 6, 970--974 (2010). [0pt] [4] W. Li, T. Pohl, J. M. Rost, Seth T. Rittenhouse, H. R. Sadeghpour, J. Nipper, B. Butscher, J. B. Balewski, V. Bendkowsky, R. L"ow, T. Pfau, Science 334, 1110 (2011).

Pfau, Tilman

2012-06-01

63

Ground-state Configuration Ground-state Level Ionization Energy (eV) Based upon 12 C. () indicates.8640 43 Tc Technetium (98) 7.28 75 Re Rhenium 186.207 7.8335 44 Ru Ruthenium 101.07 7.3605 76 Os Osmium

Johnson, Walter R.

64

NASA Astrophysics Data System (ADS)

The both mass-dependent and field shift components of the isotopic shifts and the lowest order QED corrections for the ground (singlet) 11S(L = 0)-states of the 3He and 4He atoms are determined to high accuracy. For the same states we also evaluated the lowest-order QED corrections and the corresponding recoil (or finite mass) corrections. In our calculations we have used the new (corrected) formula for the recoil correction to the lowest-order QED correction which can be applied to atoms/ions with arbitrary nuclear charge Q ? 1.

Frolov, Alexei M.

2015-01-01

65

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

66

NASA Astrophysics Data System (ADS)

This work deals with the cooling and trapping of single cesium (Cs) atoms in a large-magnetic-gradient magneto-optical trap (MOT) and the confinement of single Cs atoms in a far-off-resonance optical dipole trap (FORT). The experiment setup is based on two large-numerical-aperture lens assemblies which allow us to strongly focus a 1064-nm TEM00-mode Gaussian laser beam to a 1/e2 radius of ~ 2.3 ?m to form a microscopic FORT for isolating single atom with environment and to efficiently collect the laser-induced-fluorescence photons emitted by single atoms for detecting and recognizing single atom's internal state. We have tried both of "bottom-up" and "top-down" loading schemes to confine single atoms in the microscopic FORT. In the "bottom-up" scheme, we have successfully prepared single Cs atoms in the MOT and transferred it into FORT with a probability of almost 100%. In the "top-down" scheme, we have achieved ~ 74% of single atom loading probability in the FORT using light-assisted collisions induced by blue detuning laser and with prepared many Cs atoms in the MOT. The relaxation time in hyperfine level of ground state of trapped single Cs atom is measured to be ~5.4 s. To coherently manipulate atomic quantum bits (qubit) encoded in the clock states (mF = 0 states in Fg = 3 and 4 hyperfine levels) of single Cs atom via the two-photon simulated Raman adiabatic passage (STIRAP), we have prepared two phase-locked laser beams with a frequency difference of ~ 9.192 GHz by optically injecting an 852-nm master laser to lock the +1-order sideband of a 9-GHz current-modulated slave diode laser. The two phase-locked laser beams are used to drive STIRAP process in the ?-type three-level system consists of Cs |6S1/2 Fg = 4, mF = 0> and |6S1/2 Fg = 3, mF = 0< long-lived clock states and Cs |6S1/2 Fe = 4, mF = +1 > excited state with the single-photon detuning of ~ -20 GHz. Rabi flopping experiments are in progress.

Diao, Wenting; He, Jun; Liu, Bei; Wang, Junmin

2012-11-01

67

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

68

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

69

This thesis describes an experiment in which a neutral atom laser trap loaded with radioactive {sup 21}Na was improved and then used for measurements. The sodium isotope (half-life=22 sec) is produced on line at the 88in cyclotron at Lawrence Berkeley National Laboratory. The author developed an effective magnesium oxide target system which is crucial to deliver a substantive beam of {sup 21}Na to the experiment. Efficient manipulation of the {sup 21}Na beam with lasers allowed 30,000 atoms to be contained in a magneto-optical trap. Using the cold trapped atoms, the author measured to high precision the hyperfine splitting of the atomic ground state of {sup 21}Na. She measured the 3S{sub 1/2}(F=1,m=0)-3S{sub 1/2}(F=2,m=0) atomic level splitting of {sup 21}Na to be 1,906,471,870{+-}200 Hz. Additionally, she achieved initial detection of beta decay from the trap and evaluated the prospects of precision beta decay correlation studies with trapped atoms.

Rowe, Mary A.

1999-05-24

70

In order to employ molecular dynamics (MD) methods, commonly used in condensed matter physics, we have derived the equations of motion for a beam of charged particles in the rotating rest frame of the reference particle. We include in the formalism that the particles are confined by the guiding and focusing magnetic fields, and that they are confined in a conducting vacuum pipe while interacting with each other via a Coulomb force. Numerical simulations using MD methods has been performed to obtain the equilibrium crystalline beam structure. The effect of the shearing force, centrifugal force, and azimuthal variation of the focusing strength are investigated. It is found that a constant gradient storage ring can not give a crystalline beam, but that an alternating-gradient (AG) structure can. In such a machine the ground state is, except for one-dimensional (1-D) crystals, time dependent. The ground state is a zero entropy state, despite the time-dependent, periodic variation of the focusing force. The nature of the ground state, similar to that found by Schiffer et al. depends upon the density and the relative focusing strengths in the transverse directions. At low density, the crystal is 1-D. As the density increases, it transforms into various kinds of 2-D and 3-D crystals. If the energy of the beam is higher than the transition energy of the machine, the crystalline structure can not be formed for lack of radial focusing.

Wei, Jie [Brookhaven National Lab., Upton, NY (United States); Li, Xiao-Ping [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics; Sessler, A.M. [Lawrence Berkeley Lab., CA (United States)

1993-06-11

71

NASA Astrophysics Data System (ADS)

Möller and Plesset in early work demonstrated quantitatively the high quality of the Hartree-Fock ground-state electron density ?HF(r) . Therefore, Cordero, March, and Alonso recently proposed, for atoms, a fine-tuning of ?HF(r) to satisfy both the known asymptotic behavior of the density far from the nucleus, as well as the Kato cusp condition at the nuclei. Here we extend the diagonal density ?(r) proposed by Cordero to an off-diagonal idempotent one-particle density matrix. The orthonormal orbitals used in this construction are then to be found from the solution of generalized Hartree-Fock equations. We report calculations on the Be isoelectronic series of atomic ions with Z from Li- to Ca16+ .

Amovilli, C.; March, N. H.; Talman, J. D.

2008-03-01

72

NASA Astrophysics Data System (ADS)

Following some studies of ?n(r )?V(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r ) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, ?n(r )?V(r)/?rdr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force -?V /?r is then related to the derivative of the exchange-correlation potential Vxc(r) by terms involving only the external potential in addition to n(r ). The resulting integral constraint should allow some test of the quality of currently used forms of Vxc(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell.

March, N. H.; Nagy, Á.

2008-11-01

73

We consider a Dirac one-electron atom placed in a weak, static, uniform magnetic field. We show that, to the first order in the strength $B$ of the perturbing field, the only electric multipole moment induced by the field in the ground state of the atom is the quadrupole one. Using the Sturmian expansion of the generalized Dirac-Coulomb Green function [R.

Radoslaw Szmytkowski; Patrycja Stefanska

2011-01-01

74

The charge-transfer cross sections between a gadolinium atom and its singly charged positive ion in metastable states have been measured with a crossed-beam apparatus. The primary ions are produced by photo- ionization with a tunable dye laser. The populations of primary ions in excited states have been measured by the laser-induced fluorescence method. By measuring the populations, the charge-transfer cross

M. Hashida; S. Sakabe; Y. Izawa

1996-01-01

75

NASA Astrophysics Data System (ADS)

In this letter, we assess to what extent Bader's atomic charges are appropriate to quantify charge transfers in photon absorption processes. We actually underline the fundamental role of the atomic dipole moment, which is indeed involved in the change of the electron density polarization upon excitation. This contribution cannot be neglected and enables to reproduce the total transition dipole moments with full accuracy if an enough tight integration quadrature is used. As this scheme allows separating intra-atomic density reorganization and interatomic charge transfer, it is well suited to describe through-space charge-transfer excitations.

Tognetti, Vincent; Joubert, Laurent

2013-02-01

76

NASA Astrophysics Data System (ADS)

Penicillium digitatum spores were inactivated using an oxygen-radical source that supplies only neutral oxygen radicals. Vacuum ultraviolet absorption spectroscopy was used to measure the ground-state atomic oxygen [O (3Pj)] densities and they were estimated to be in the range of 1014-1015 cm-3. The inactivation rate of P. digitatum spores was correlated with the O (3Pj) density. The result indicates that O (3Pj) is the dominant species in the inactivation. The inactivation rate constant of P. digitatum spores by O (3Pj) was estimated to be on the order of 10-17 cm3 s-1 from the measured O (3Pj) densities and inactivation rates.

Iseki, Sachiko; Hashizume, Hiroshi; Jia, Fengdong; Takeda, Keigo; Ishikawa, Kenji; Ohta, Takayuki; Ito, Masafumi; Hori, Masaru

2011-11-01

77

Existence of ground states of hydrogen-like atoms in relativistic QED II: The no-pair operator

We consider a hydrogen-like atom in a quantized electromagnetic field which is modeled by means of a no-pair operator acting in the positive spectral subspace of the free Dirac operator minimally coupled to the quantized vector potential. We prove that the infimum of the spectrum of the no-pair operator is an evenly degenerate eigenvalue. In particular, we show that the

Martin Könenberg; Oliver Matte; Edgardo Stockmeyer

2010-01-01

78

The linear boronisocyanide species, [BNC(X(1)Sigma(+))], represents the simplest triatomic molecule with three distinct, neighboring main group atoms of the second row of the periodic table of the elements: boron, carbon, and nitrogen. This makes boronisocyanide a crucial benchmark system to understand the chemical bonding and the electronic structure of small molecules, in particular when compared to the isoelectronic tricarbon molecule, [CCC(X(1)Sigma(g)(+))]. However, a clean, directed synthesis of boronisocyanide-a crucial prerequisite to study the properties of this molecule-has remained elusive so far. Here, we combine crossed molecular beam experiments of ground state boron atoms ((2)P(j)) with hydrogen cyanide with electronic structure calculations and reveal that the boronisocyanide molecule, [BNC(X(1)Sigma(+))], is formed as the exclusive product under gas phase single collision conditions. We also show that higher energy isomers such as the hitherto unnoticed, ring-strained cyclic BNC(X(3)A') structure, which is isoelectronic to the triplet, cyclic tricarbon molecule, [C(3)(X(3)A(2)')], do exist as local minima. Our studies present the first directed synthesis and observation of gas phase boronisocyanide providing a doorway for further fundamental studies on one of the simplest triatomic molecules composed solely of group III-V elements. PMID:20681533

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

2010-09-01

79

The photodetachment dynamics of the atomic oxygen anion O{sup -} has been investigated at 266 nm (4.67 eV) by photoelectron detection in a crossed-beam experiment using a magnetic-bottle electron spectrometer. Taking explicit advantage of the Doppler shift imposed by the moving ion beam on the photoelectron energies, we report both the final-state branching ratio and photoelectron angular distributions. After photoabsorption at 266 nm, the formed electron-oxygen scattering state disintegrates, forming either the excited {sup 1}D or the ground {sup 3}P state of oxygen with a partition of {sup 1}D:{sup 3}P=0.32 {+-} 0.06. The detachment leading to the production of O({sup 3}P) shows an angular distribution of photoelectrons characterized by {beta}{sub P}=0.00 {+-} 0.10 mimicking a pure s-wave detachment, while the detachment into excited O({sup 1}D) occurs with {beta}{sub D}=-0.90{+-}0.10, giving direct evidence of interference between the outgoing s and d waves.

Domesle, C.; Jordon-Thaden, B.; Wolf, A. [Max-Planck-Institut fuer Kernphysik, DE-69117 Heidelberg (Germany); Lammich, L.; Pedersen, H. B. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Foerstel, M. [Max-Planck-Institut fuer Kernphysik, DE-69117 Heidelberg (Germany); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, DE-85748 Garching (Germany); Hergenhahn, U. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, DE-85748 Garching (Germany)

2010-09-15

80

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.

81

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

82

Ground states of holographic superconductors

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

Gubser, Steven S.; Nellore, Abhinav [Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544 (United States)

2009-11-15

83

NASA Astrophysics Data System (ADS)

The density functional theory was applied to calculate the electronic structure, ground state energy, phonon frequencies at the center and at the boundary of the Brillouin zone, as well as the distribution of magnetic moment over d-orbitals of iron in the magnetically ordered phase of FeTe as functions of the magnetic moment—spin state of iron. It was shown that the ground state energy minimum is achieved at a certain distribution of the magnetic moment over d-orbitals and at a certain spin state of the iron ion. The impact of the new type of interaction ("the spin state-lattice" interaction) on the phonon subsystem was studied numerically. It was found that the high-frequency part of the phonon spectra undergoes the most significant changes upon changing the spin state. To describe the properties of iron-containing HTSC compounds, an integral parameter (spin state of iron ion) was suggested.

Pashkevich, Yu. G.; Shevtsova, T. N.; Gusev, A. A.; Gnezdilov, V. P.; Lemmens, P.

2012-09-01

84

Mean-field ground state of a spinor-1 condensate

We revisit the ground state structures of a spinor-1 condensate,taking into account the important constraints that atomic elastic collisions conserve both the total number of atoms (N) and the total magnetization (l M). The effect of a uniform magnetic field on the validity of the single mode approximation (SMA) is also studied. Our results highlight the important role of the

Wenxian Zhang; Su Yi; Li You

2003-01-01

85

Ground state of positronium hydride

The ground bound state in the positronium hydride molecule (HPs) is determined from extensive variational four-body calculations with the James-Coolidge four-body variational expansion in the relative coordinates r{sub 12},r{sub 13},r{sub 23},r{sub 14},r{sub 24}, and r{sub 34}. For the positronium hydride with the infinitely heavy nucleus ({sup {infinity}}HPs) the total energy found, E={minus}0.7891369 a.u., is one of the lowest variational values published to date. A number of bound-state properties have been calculated also, including the {delta}-function expectation values, two-body cusps, and the two-photon annihilation rate. {copyright} {ital 1997} {ital The American Physical Society}

Frolov, A.M.; Smith, V.H. , Jr. [Department of Chemistry, Queens University, Kingston, Ontario, K7L3N6 (CANADA)] [Department of Chemistry, Queens University, Kingston, Ontario, K7L3N6 (CANADA)

1997-09-01

86

Ground-State Spaces of Frustration-Free Hamiltonians

We study the ground-state space properties for frustration-free Hamiltonians. We introduce a concept of `reduced spaces' to characterize local structures of ground-state spaces. For a many-body system, we characterize mathematical structures for the set $\\Theta_k$ of all the $k$-particle reduced spaces, which with a binary operation called join forms a semilattice that can be interpreted as an abstract convex structure. The smallest nonzero elements in $\\Theta_k$, called atoms, are analogs of extreme points. We study the properties of atoms in $\\Theta_k$ and discuss its relationship with ground states of $k$-local frustration-free Hamiltonians. For spin-1/2 systems, we show that all the atoms in $\\Theta_2$ are unique ground states of some 2-local frustration-free Hamiltonians. Moreover, we show that the elements in $\\Theta_k$ may not be the join of atoms, indicating a richer structure for $\\Theta_k$ beyond the convex structure. Our study of $\\Theta_k$ deepens the understanding of ground-state space properties for frustration-free Hamiltonians, from a new angle of reduced spaces.

Jianxin Chen; Zhengfeng Ji; David Kribs; Zhaohui Wei; Bei Zeng

2011-12-04

87

NASA Astrophysics Data System (ADS)

We describe a set of experiments that investigate diffusion of barium 6s5d3D J metastable level and 6s2/ 1S0 ground state atoms through the noble gases: He, Ne, Ar, Kr, and Xe. The barium metastable levels were populated through optical pumping of the 6s2/ 1S0 /to 6s6p 3P1o intercombination transition with a pulsed laser, followed by spontaneous or stimulated emission into the 6s5d 3D1,2 levels. Collisional mixing then distributed population throughout the 6s5d 3D J levels. Since the pulsed laser beam propagated along the axis of the cylindrical heat-pipe oven with a beam diameter much smaller than the oven diameter, the metastable state atoms were initially localized only along the oven axis. A weak narrow-band cw laser was tuned to appropriate transitions to probe the spatial distribution of metastable level atoms, as well as the hole created in the ground state spatial distribution, by the pulsed laser. Time-dependent absorption coefficients were obtained by measuring the transmission of the probe laser at several different pump/probe spatial separations. From these absorption data, spatial number density profiles were mapped out for various times following the firing of the pump laser. These density profiles were used to determine the diffusion coefficient for each state at a particular buffer gas pressure and temperature. From these pressure and temperature dependent diffusion coefficients D, we determined the thermally averaged diffusion cross sections ? D(6s5d 3D J) and ? D(6s2/ 1S0) for the metastable and ground state atoms diffusing through the noble gases, respectively. We also report values for the scaled standard diffusion coefficients, D0. Our experimental values of the thermally averaged diffusion cross sections ? D(6s5d 3D J) and ? D(6s2/ 1S0) for barium-helium are compared to values calculated from published, theoretical barium-helium potentials, and the agreement is excellent.

Namiotka, Raychel Kristine

1998-05-01

88

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

89

Trapped Antihydrogen in Its Ground State

NASA Astrophysics Data System (ADS)

Antihydrogen atoms are confined in a magnetic quadrupole trap for 15 to 1000 s - long enough to ensure that they reach their ground state. This milestone brings us closer to the long-term goal of precise spectroscopic comparisons of antihydrogen and hydrogen for tests of CPT and Lorentz invariance. Realizing trapped antihydrogen requires characterization and control of the number, geometry, and temperature of the antiproton and positron plasmas from which antihydrogen is formed. An improved apparatus and implementation of plasma measurement and control techniques make available 107 antiprotons and 4 x 109 positrons for antihydrogen experiments - an increase of over an order of magnitude. For the first time, antiprotons are observed to be centrifugally separated from the electrons that cool them, indicating a low-temperature, high-density antiproton plasma. Determination of the antiproton temperature is achieved through measurement of the antiproton evaporation rate as their confining well is reduced, with corrections given by a particle-in-cell plasma simulation. New applications of electron and adiabatic cooling allow for the lossless reduction in antiproton temperature from thousands of Kelvin to 3.5 K or colder, the lowest ever reported. The sum of the 20 trials performed in 2011 in which antiprotons and positrons mix to form antihydrogen in the presence of a magnetic quadrupole trap reveals a total of 105 +/- 21 trapped antihydrogen atoms, or 5 +/- 1 per trial on average. This result paves the way towards the large numbers of simultaneously trapped antihydrogen atoms that will be necessary for laser spectroscopy.

Richerme, Philip John

90

Following some studies of integral(n)(r)inverted DeltaV(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, integral(n)(r) partial differential(V)(r)/partial differential(r)dr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force - partial differential(V)/ partial differential(r) is then related to the derivative of the exchange-correlation potential V(xc)(r) by terms involving only the external potential in addition to n(r). The resulting integral constraint should allow some test of the quality of currently used forms of V(xc)(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell. PMID:19026052

March, N H; Nagy, A

2008-11-21

91

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 inte...

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

2011-01-01

92

Chirped pulse excitation of two-atom Rydberg states

We analyze excitation of two ground state atoms to a double Rydberg state by a two-photon chirped optical pulse in the regime of adiabatic rapid passage. For intermediate Rydberg-Rydberg interaction strengths, relevant for atoms separated by $\\sim$ten $\\mu$m, adiabatic excitation can be achieved at experimentally feasible Rabi frequencies and chirp rates of the pulses, resulting in high transfer efficiencies. We also study the adiabatic transfer between ground and Rydberg states as a means to realize a controlled phase gate between atomic qubits.

Kuznetsova, Elena

2015-01-01

93

Entanglement and entropy engineering of atomic two-qubit States.

We propose a scheme employing quantum-reservoir engineering to controllably entangle the internal states of two atoms trapped in a high-finesse optical cavity. Using laser and cavity fields to drive two separate Raman transitions between stable atomic ground states, a system is realized corresponding to a pair of two-state atoms coupled collectively to a squeezed reservoir. Phase-sensitive reservoir correlations lead to entanglement between the atoms, and, via local unitary transformations and adjustment of the degree and purity of squeezing, one can prepare entangled mixed states with any allowed combination of linear entropy and entanglement of formation. PMID:12570464

Clark, S G; Parkins, A S

2003-01-31

94

Ground-State Quantum Discord in Coupled Cavities

NASA Astrophysics Data System (ADS)

We study two coupled cavities system, each of cavity containing a single two-level atom. Quantum entanglemt, quantum discord and quantum phase transition under ground state have been investigated. Atomic excitation number variance has used to characterize the quantum phase transition. We conclude that, in our model, quantum discord have nonzero values while quantum entanglement vanish and quantum discord is a more proper measure to characterize quantum transition.

Liu, Zhong Ju; Miao, Hai Ling; Jiang, Wei; Li, Zhi Jie

2015-03-01

95

NASA Astrophysics Data System (ADS)

The Hiller-Sucher-Feinberg (HSF) identity is combined with the three-parameter correlated wave function of Chandrasekhar in order to generate an alternative electron density ?(r) for the He atom. This and the conventional "local" operator form of ?(r) are then compared with a diffusion quantum Monte Carlo density. An exact limiting relation is also presented, via HSF identity, between the one-particle density matrix and the pair density in a many-electron atom, which transcends its Hartree-Fock counterpart and has no N-representability difficulties. For the Ne atom, the accuracy of the semiempirical correlated electron density recently obtained by Cordero et al. (Phys. Rev. A 2007, 75, 052502) using fine-tuning of Hartree-Fock theory was assessed by appealing to the ground-state density from diffusion quantum Monte Carlo. The high accuracy of the Cordero et al. density was thereby confirmed. A HSF calculation on neon, with a correlated many-body wave function as starting point, is a worthwhile future aim.

Amovilli, Claudio; March, Norman H.

96

Femtosecond stimulated emission pumping: Characterization ground state

effects inherent to negatively charged species induce rapid energy transfer that depends sensitively femtosecond stimulated emission pumping, and monitoring the resulting wave packet oscillations on the shape of the ground and excited state potentials.14,15 This is especially true for the ground state

Neumark, Daniel M.

97

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

98

Producing Squeezed Input States for an Atomic Clock Using an Optical Cavity

Producing Squeezed Input States for an Atomic Clock Using an Optical Cavity Ian D. Leroux, Monika H clock states (Figure 1c), such that the index of refraction of an atom in | |F = 2, mF = 0 blue: The field-insensitive states in the ground-state hyperfine manifold form an effective two-level atom (clock

Vuletic, Vladan

99

New techniques have been developed for atomic self-consistent-field calculations by numerical integration. For the origin and tail regions we present analytical expansions which can represent the solutions to high accuracy. For the numerical integration in the central region a five-point generalization of the Numerov formula is used; the error term is of the order hÂąÂ°. While this formula is unstable

C. C. J. Roothaan; G. A. Soukup

1979-01-01

100

We consider a hydrogen-like atom in a quantized electromagnetic field which is modeled by means of the semi-relativistic Pauli-Fierz operator and prove that the infimum of the spectrum of the latter operator is an eigenvalue. In particular, we verify that the bottom of its spectrum is strictly less than its ionization threshold. These results hold true, for arbitrary values of

Martin Könenberg; Oliver Matte; Edgardo Stockmeyer

2011-01-01

101

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

102

On the ground state of metallic hydrogen

NASA Technical Reports Server (NTRS)

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

Chakravarty, S.; Ashcroft, N. W.

1978-01-01

103

Simultaneous position and state measurement of Rydberg atoms

We present a technique for state-selective position detection of cold Rydberg atoms. Ground state Rb atoms in a magneto-optical trap are excited to a Rydberg state and are subsequently ionized with a tailored electric field pulse. This pulse selectively ionizes only atoms in e.g. the 54d state and not in the 53d state. The released electrons are detected after a slow flight towards a micro channel plate. From the time of flight of the electrons the position of the atoms is deduced. The state selectivity is about 20:1 when comparing 54d with 53d and the one-dimensional position resolution ranges from 6 to 40 $\\mu$m over a range of 300 $\\mu$m. This state selectivity and position resolution are sufficient to allow for the observation of coherent quantum excitation transport.

C. S. E. van Ditzhuijzen; A. F. Koenderink; L. D. Noordam; H. B. van Linden van den Heuvell

2007-05-22

104

Steady state theory of hot atom reactions

A simple steady state theory of hot atom reactions is developed based on the Boltzmann equation. The solution to this equation is approximated by a local Maxwell distribution involving the temperature of the hot atoms and steady state distributions are calculated by determining steady values of the hot atom temperature. General considerations imply the existence of steady state distributions with

Joel Keizer

1973-01-01

105

Storage States in Ultracold Collective Atoms

We present a complete theoretical description of atomic storage states in the multimode framework by including spatial coherence in atomic collective operators and atomic storage states. We show that atomic storage states are Dicke states with the maximum cooperation number. In some limits, a set of multimode atomic storage states has been established in correspondence with multimode Fock states of the electromagnetic field. This gives better understanding of both the quantum and coherent information of optical field can be preserved and recovered in ultracold medium. In this treatment, we discuss in detail both the adiabatic and dynamic transfer of quantum information between the field and the ultracold medium.

Kaige Wang; Shiyao Zhu

2002-07-27

106

Coherent excitation of a single atom to a Rydberg state

We present the coherent excitation of a single Rubidium atom to the Rydberg state 58d{sub 3/2} using a two-photon transition. The experimental setup is described in detail, as are experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between ground and Rydberg states of the atom. We analyze the observed oscillations in detail and compare them to numerical simulations which include imperfections of our experimental system. Strategies for future improvements on the coherent manipulation of a single atom in our settings are given.

Miroshnychenko, Y.; Gaeetan, A.; Evellin, C.; Grangier, P.; Wilk, T.; Browaeys, A. [Laboratoire Charles Fabry, Institut d'Optique, Centre National de la Recherche Scientifique, Universite Paris-Sud, Campus Polytechnique, RD 128, F-91127 Palaiseau CEDEX (France); Comparat, D.; Pillet, P. [Laboratoire Aime Cotton, Centre National de la Recherche Scientifique, Universite Paris-Sud, Batiment 505, Campus d'Orsay, F-91405 Orsay CEDEX (France)

2010-07-15

107

Optimal Control of Cold Ground-State Collisions by Shaped Laser Pulses

NASA Astrophysics Data System (ADS)

This works investigates the optimal laser control of the electronic ground-state collision of two cold atoms of distinct species. The control goal is to perform the photoassociation of the colliding pair of atoms along with the vibrational-rotational stabilization of the diatomic molecule taking advantage of the permanent dipole moment associated with the collision. Calculations are performed within a model system for the electronic ground state of Li+Cs. It is shown that an optimized laser pulse can induce the transition from the free state to the molecular rotational-vibrational ground state with high efficiency.

de Lima, Emanuel F.

2015-02-01

108

Breit-Rabi Zeeman states of atomic hydrogen

The magnetic field dependence of the isotropic nonrelativistic one-electron atom with nuclear spin-1\\/2, in its electronic ground state, is reviewed. Attention is called to the little-known fact that a level crossing exists (at field B~17 T for 1H) between the two members of the upper spin (MS=1\\/2) doublet. Anisotropy of such a hydrogenic atom, due to the presence of a

R. S. Dickson; J. A. Weil

1991-01-01

109

Breit--Rabi Zeeman states of atomic hydrogen

The magnetic field dependence of the isotropic nonrelativistic one-electron atom with nuclear spin-1\\/2, in its electronic ground state, is reviewed. Attention is called to the little-known fact that a level crossing exists (at field {ital B}{similar to}17 T for ÂąH) between the two members of the upper spin ({ital M}{sub {ital S}}=1\\/2) doublet. Anisotropy of such a hydrogenic atom, due

R. S. Dickson; J. A. Weil

1991-01-01

110

Mean field ground state of a spin-1 condensate in a magnetic field

We revisit the topic of the mean field ground state of a spin-1 atomic condensate inside a uniform magnetic field (B) under the constraints that both the total number of atoms (N) and the magnetization (M) are conserved. In the presence of an internal state (spin component) independent trap, we also investigate the dependence of the so-called single spatial mode

Wenxian Zhang; Su Yi; Li You

2003-01-01

111

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

112

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

113

Radio-frequency dressed state potentials for neutral atoms

Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronically excited states of an atom with light. Here we present an experimental investigation of the remarkable properties of potentials derived from radio-frequency (RF) coupling between electronic ground states. The coupling is magnetic and the vector character allows to design state dependent potential landscapes. On atom chips this enables robust coherent atom manipulation on much smaller spatial scales than possible with static fields alone. We find no additional heating or collisional loss up to densities approaching $10^{15}$ atoms / cm$^3$ compared to static magnetic traps. We demonstrate the creation of Bose-Einstein condensates in RF potentials and investigate the difference in the interference between two independently created and two coherently split condensates in identical traps. All together this makes RF dressing a powerful new tool for micro manipulation of atomic and molecular systems.

S. Hofferberth; I. Lesanovsky; B. Fischer; J. Verdu; J. Schmiedmayer

2006-08-29

114

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

115

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

G.-P. Zheng; Y.-G. Tong; F.-L. Wang

2010-01-01

116

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

117

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

118

Ground state energy of large polaron systems

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

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

2014-09-18

119

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

NASA Astrophysics Data System (ADS)

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.

2010-06-01

120

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

121

Sympathetic cooling of molecular ion motion to the ground state

NASA Astrophysics Data System (ADS)

We demonstrate sympathetic sideband cooling of a 40CaH+ molecular ion co-trapped with a 40Ca+ atomic ion in a linear Paul trap. Both axial modes of the two-ion chain are simultaneously cooled to near the ground state of motion. The center of mass mode is cooled to an average quanta of harmonic motion {{\\bar{n}}COM}=0.13+/- 0.03, corresponding to a temperature of 12.47+/- 0.03 ? K. The breathing mode is cooled to {{\\bar{n}}BM}=0.05+/- 0.02, corresponding to a temperature of 15.36+/- 0.01 ? K.

Rugango, R.; Goeders, J. E.; Dixon, T. H.; Gray, J. M.; Khanyile, N. B.; Shu, G.; Clark, R. J.; Brown, K. R.

2015-03-01

122

Photonic multiqubit states from a single atom

We propose a protocol for the creation of photonic Greenberger-Horne-Zeilinger and linear cluster states emitted from a single atom--or ion--coupled to an optical cavity field. The method is based on laser pulses with different polarizations and exploits the atomic transition amplitudes to state-selectively achieve the desired transitions. The scheme lies within reach of current technology.

Li Ying [Centre for Quantum Technologies, National University of Singapore, Singapore 117543 (Singapore); Aolita, Leandro [ICFO-Institut de Ciencies Fotoniques, Parc Mediterrani de la Tecnologia, 08860 Castelldefels, Barcelona (Spain); Kwek, L. C. [Centre for Quantum Technologies, National University of Singapore, Singapore 117543 (Singapore); Institute of Advanced Studies (IAS), Nanyang Technological University, Singapore 639673 (Singapore); National Institute of Education, Nanyang Technological University, Singapore 637616 (Singapore)

2011-03-15

123

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

124

Stable heteronuclear few-atom bound states in mixed dimensions

We study few-body problems in mixed dimensions where two or three heavy atoms are trapped individually in parallel one-dimensional tubes or two-dimensional disks and a single light atom travels freely in three dimensions. Using the Born-Oppenheimer approximation, we find three- and four-body bound states for a broad parameter region. Specifically, the existence of trimer and tetramer states persists to the negative scattering length regime, where no two-body bound state is present. As pointed out by Y. Nishida in an earlier work [Phys. Rev. A 82, 011605(R) (2010)], these few-body bound states are stable against three-body recombination due to geometric separation. In addition, we find that the binding energy of the ground trimer and tetramer state reaches its maximum value when the scattering lengths are comparable to the separation between the low-dimensional traps.

Yin Tao; Zhang Peng; Zhang Wei [Department of Physics, Renmin University of China, Beijing 100872 (China)

2011-11-15

125

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

126

Mean field ground state of a spin-1 condensate in a magnetic field

We revisit the topic of the mean field ground state of a spin-1 atomic condensate inside a uniform magnetic field ($B$) under the constraints that both the total number of atoms ($N$) and the magnetization ($\\cal M$) are conserved. In the presence of an internal state (spin component) independent trap, we also investigate the dependence of the so-called single spatial mode approximation (SMA) on the magnitude of the magnetic field and ${\\cal M}$. Our result indicate that the quadratic Zeeman effect is an important factor in balancing the mean field energy from elastic atom-atom collisions that are known to conserve both $N$ and $\\cal M$.

Wenxian Zhang; Su Yi; Li You

2003-06-03

127

The a-decay chains originating from the s1/2 and h11/2 states in 173Au have been investigated following fusion-evaporation reactions. Four generations of a radioactivities have been correlated with 173Aum leading to a measurement of the a decay of 161Tam. It has been found that the known a decay of 161Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt g rays feeding the ground state of 173Au. This prompt radiation was used to aid the study of the a-decay chain originating from the s1/2 state in 173Au. Three generations of a decays have been correlated with this state leading to the observation of a previously unreported activity which is assigned as the decay of 165Reg. This work also reports the excitation energy of an a-decaying isomer in 161Ta and the Q-value of the decay of 161Tag.

D. O'Donnell; R. D. Page; C. Scholey; L. Bianco; L. Capponi; R. J. Carroll; I. G. Darby; L. Donosa; M. Drummond; F. Ertugral; P. T. Greenlees; T. Grahn; K. Hauschild; A. Herzan; U. Jakobsson; P. Jones; D. T. Joss; R. Julin; S. Juutinen; S. Ketelhut; M. Labiche; M. Leino; A. Lopez-Martens; K. Mullholland; P. Nieminen; P. Peura; P. Rahkila; S. Rinta-Antila; P. Ruotsalainen; M. Sandzelius; J. Saren; B. Saygi; J. Simpson; J. Sorri; A. Thornthwaite; J. Uusitalo

2012-12-19

128

Teleportation of an atomic momentum state

. The momentum state that is to be transferred is defined as uCa&5cau1p0&1cbu2p0&, ~1! FIG. 1. Schematic diagram of the quantum controlled-NOT logic gate used for the atomic momentum state teleportation. If p0 is the moment of the incoming atom along the x... of atomic center-of-mass momentum m controlled-NOT gate via atomic scattering in the PACS number~s!: 03.67.2a, 42.50.Ct, 32.80.Qk where u1p0& and u2p0& are the momentum states of the incoming atoms in 6x directions, respectively ~see Fig. 1! and ca...

Qamar, S.; Zhu, S. Y.; Zubairy, M. Suhail.

2003-01-01

129

Teleportation of an atomic momentum state

In this paper, we propose a scheme for teleportating a superposition of atomic center-of-mass momentum states to a superposition of the cavity field using quantum controlled-NOT gate via atomic scattering in the Bragg regime and cavity quantum electrodynamics.

Qamar, Shahid [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad (Pakistan); Zhu Shiyao [Department of Physics, Hong Kong Baptist University, Hong Kong (China); Zubairy, M. Suhail [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States); Department of Electronics, Quaid-i-Azam University, Islamabad (Pakistan)

2003-04-01

130

Tensor polarizability of the ground-state hyperfine structure of thallium

The atomic-beam magnetic-resonance technique has been used to measure the hyperfine-structure tensor polarizability (quadratic Stark effect) in the 62P12 ground state of atomic thallium. Electric fields of up to 460 kV\\/cm were used to lift the degeneracy between the mF=0 and the mF=+\\/- 1 substates in the absence of an external magnetic field, and focusing transitions between these Stark-separated states

Harvey Gould

1976-01-01

131

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

132

Sideband cooling of micromechanical motion to the quantum ground state

NASA Astrophysics Data System (ADS)

The advent of laser cooling techniques revolutionized the study of many atomic-scale systems, fuelling progress towards quantum computing with trapped ions and generating new states of matter with Bose-Einstein condensates. Analogous cooling techniques can provide a general and flexible method of preparing macroscopic objects in their motional ground state. Cavity optomechanical or electromechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime--in which a system has less than a single quantum of motion--has been difficult because sideband cooling has not sufficiently overwhelmed the coupling of low-frequency mechanical systems to their hot environments. Here we demonstrate sideband cooling of an approximately 10-MHz micromechanical oscillator to the quantum ground state. This achievement required a large electromechanical interaction, which was obtained by embedding a micromechanical membrane into a superconducting microwave resonant circuit. To verify the cooling of the membrane motion to a phonon occupation of 0.34+/-0.05 phonons, we perform a near-Heisenberg-limited position measurement within (5.1+/-0.4)h/2?, where h is Planck's constant. 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. Because mechanical oscillators can couple to light of any frequency, they could also serve as a unique intermediary for transferring quantum information between microwave and optical domains.

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

2011-07-01

133

Sideband cooling of micromechanical motion to the quantum ground state.

The advent of laser cooling techniques revolutionized the study of many atomic-scale systems, fuelling progress towards quantum computing with trapped ions and generating new states of matter with Bose-Einstein condensates. Analogous cooling techniques can provide a general and flexible method of preparing macroscopic objects in their motional ground state. Cavity optomechanical or electromechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime--in which a system has less than a single quantum of motion--has been difficult because sideband cooling has not sufficiently overwhelmed the coupling of low-frequency mechanical systems to their hot environments. Here we demonstrate sideband cooling of an approximately 10-MHz micromechanical oscillator to the quantum ground state. This achievement required a large electromechanical interaction, which was obtained by embedding a micromechanical membrane into a superconducting microwave resonant circuit. To verify the cooling of the membrane motion to a phonon occupation of 0.34?±?0.05 phonons, we perform a near-Heisenberg-limited position measurement within (5.1?±?0.4)h/2?, where h is Planck's constant. 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. Because mechanical oscillators can couple to light of any frequency, they could also serve as a unique intermediary for transferring quantum information between microwave and optical domains. PMID:21734657

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

2011-07-21

134

Ground state blind quantum computation on AKLT state

The blind quantum computing protocols (BQC) enable a classical client with limited quantum technology to delegate a computation to the quantum server(s) in such a way that the privacy of the computation is preserved. Here we present a new scheme for BQC that uses the concept of the measurement based quantum computing with the novel resource state of Affleck-Kennedy-Lieb-Tasaki (AKLT) chains leading to more robust computation. AKLT states are physically motivated resource as they are gapped ground states of a physically natural Hamiltonian in condensed matter physics. Our BQC protocol can enjoy the advantages of AKLT resource states, such as the cooling preparation of the resource state, the energy-gap protection of the quantum computation, and the simple and efficient preparation of the resource state in linear optics with biphotons.

Tomoyuki Morimae; Vedran Dunjko; Elham Kashefi

2011-06-17

135

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

136

Probing the ground state in gauge theories

We consider two very different models of the flux tube linking two heavy quarks: a string linking the matter fields and a Coulombic description of two separately gauge invariant charges. We compare how close they are to the unknown true ground state in compact U(1) and the SU(2) Higgs model. Simulations in compact U(1) show that the string description is better in the confined phase but the Coulombic description is best in the deconfined phase; the last result is shown to agree with analytical calculations. Surprisingly in the nonabelian theory the Coulombic description is better in both the Higgs and confined phases. This indicates a significant difference in the width of the flux tubes in the two theories.

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Lutz, W. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2008-03-01

137

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

138

Color Neutral Ground State of 2SC Quark Matter

We construct a new color neutral ground state of two-flavor color superconducting quark matter. It is shown that, in contrast with the conventionally considered ground state with diquark pairing in only one color direction, this new state is stable against arbitrary diquark fluctuations. In addition, the thermodynamical potential is found to be lower for this new state than for the conventional one.

D. Blaschke; D. Gómez Dumm; A. G. Grunfeld; N. N. Scoccola

2005-07-25

139

Formylmethylene: the triplet ground state and the lowest singlet state.

The ground triplet state and lowest singlet state of formylmethylene have been proposed as important intermediates in the Wolff rearrangement of ?-diazo ketones into ketenes. The ground triplet state of formylmethylene has been examined experimentally, but the lowest singlet state has yet to be observed. We predict equilibrium geometries, energies, bonding, dipole moments, and harmonic vibrational frequencies for these two lowest states of formylmethylene at the cc-pVQZ CCSD(T) level of theory. The singlet-triplet energy difference [?E(S-T)] is quite sensitive to the level of theory. The highly accurate cc-pVQZ CCSD(T) level of theory yields the most reliable result of only 2.0 kcal mol(-1). An estimate based on the experimentally characterized CH2 molecule yields ?E(S-T) = 1.27 kcal mol(-1). In addition, accurate quartic force fields have been determined at the cc-pVTZ CCSD(T) level of theory. Fundamental vibrational frequencies, anharmonic constants, and vibration-rotation coupling constants were determined using vibrational second-order perturbation theory (VPT2). Our results should aid in experimental detection and characterization of the lowest singlet state of formylmethylene, which is highly desirable for better understanding the mechanism of the Wolff rearrangement. PMID:23406310

Guan, Jun; Randall, Katherine R; Schaefer, Henry F; Li, Huidong

2013-03-14

140

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

141

Product-state Approximations to Quantum Ground States

The local Hamiltonian problem consists of estimating the ground-state energy (given by the minimum eigenvalue) of a local quantum Hamiltonian. First, we show the existence of a good product-state approximation for the ground-state energy of 2-local Hamiltonians with one or more of the following properties: (1) high degree, (2) small expansion, or (3) a ground state with sublinear entanglement with respect to some partition into small pieces. The approximation based on degree is a surprising difference between quantum Hamiltonians and classical CSPs (constraint satisfaction problems), since in the classical setting, higher degree is usually associated with harder CSPs. The approximation based on low entanglement, in turn, was previously known only in the regime where the entanglement was close to zero. Since the existence of a low-energy product state can be checked in NP, the result implies that any Hamiltonian used for a quantum PCP theorem should have: (1) constant degree, (2) constant expansion, (3) a "volume law" for entanglement with respect to any partition into small parts. Second, we show that in several cases, good product-state approximations not only exist, but can be found in polynomial time: (1) 2-local Hamiltonians on any planar graph, solving an open problem of Bansal, Bravyi, and Terhal, (2) dense k-local Hamiltonians for any constant k, solving an open problem of Gharibian and Kempe, and (3) 2-local Hamiltonians on graphs with low threshold rank, via a quantum generalization of a recent result of Barak, Raghavendra and Steurer. Our work introduces two new tools which may be of independent interest. First, we prove a new quantum version of the de Finetti theorem which does not require the usual assumption of symmetry. Second, we describe a way to analyze the application of the Lasserre/Parrilo SDP hierarchy to local quantum Hamiltonians.

Fernando G. S. L. Brandăo; Aram W. Harrow

2014-12-15

142

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

143

Is the ground state of Yang-Mills theory Coulombic?

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

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Lutz, W. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2008-08-01

144

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

145

Ground and excited states calculations of 7-phenylamino-substituted coumarins

NASA Astrophysics Data System (ADS)

A theoretical calculation of the ground and first excited states of two 7-phenylamino-substituted coumarin compounds are performed. In order to study the effect of phenyl substituted in amino group and fluorine atoms substituted in methyl group, 7-amino-4-methyl coumarin (C120) and 7-amino-4-(trifluoromethyl) coumarin (C151) were also studied. The geometries of the ground state and the first ground state were optimized using density function theory and configuration interaction singles levels of theory. Molecular orbitals (MO) of the ground and first excited states of the four coumarin compounds were obtained to explain the change of the structures. ZINDO and TD-DFT methods with different basis sets were applied to predict the UV absorption spectra. The solvent effect had also been taken into account using self-consistent isodensity polarized continuum model. The predicted spectra are in agreement with the experimental data.

Xu, Bo; Yang, Jing; Jiang, Xuesong; Wang, Yuanlong; Sun, Huai; Yin, Jie

2009-01-01

146

NASA Astrophysics Data System (ADS)

We use the differential virial theorem (DVT) directly to display the approximate spatial dependence of the exchange-correlation (XC) force in He and Be, applying an exact integral constraint on the XC force, recently established by March and Nagy. In He, an analytic ground-state density n(r) , combined with the DVT plus the von Weizsäcker single-particle kinetic energy, suffices to determine an approximate XC force. For Be, the XC force is calculated for the semiempirical fine-tuned Hartree-Fock density, as proposed by Cordero [Phys. Rev. A 75, 052502 (2007)]. However, for the single-particle kinetic energy, following Dawson and March, a phase ?(r) must be obtained by solving numerically a nonlinear pendulumlike equation.

Bogár, Ferenc; Bartha, Ferenc; March, Norman H.

2009-01-01

147

Ground state properties of the group IV ionic compound silicon carbide

The basic ground state properties of cubic silicon carbide are calculated fully ab initio using the Local Density Functional method and norm-conserving pseudopotentials, with atomic numbers and the crystal structure as the only inputs. The distribution of the valence charge density suggests that the bonding in SiC is essentially ionic.

N. Churcher; K. Kunc; V. Heine

1985-01-01

148

Different approach to the Zeeman effect: Application to the hydrogen ground state

We present results obtained by the application of a semianalytical method to the ground and excited states associated with the Zeeman effect on a hydrogen atom. In this case, where the wave equation is not separable, we show that the method works very well for both weak and strong fields.

O. L. Silva Filho; A. L. A. Fonseca

1994-01-01

149

A potential energy surface for the ground state of formaldehyde, H2CO(A1)

A model potential energy function for the ground state of H2CO has been derived which covers the whole space of the six internal coordinates. This potential reproduces the experimental energy, geometry and quadratic force field of formaldehyde, and dissociates correctly to all possible atom, diatom and triatom fragments. Thus there are good reasons for believing it to be close to

S. Carter; I. M. Mills; J. N. Murrell

1980-01-01

150

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

151

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

152

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

153

Analyticity of The Ground State Energy For Massless Nelson Models

We show that the ground state energy of the translationally invariant Nelson model, describing a particle coupled to a relativistic field of massless bosons, is an analytic function of the coupling constant and the total momentum. We derive an explicit expression for the ground state energy which is used to determine the effective mass.

Abdelmalek Abdesselam; David Hasler

2011-08-03

154

Ground-state properties of ultracold trapped bosons with an immersed ionic impurity

NASA Astrophysics Data System (ADS)

We consider a trapped atomic ensemble of interacting bosons in the presence of a single trapped ion in a quasi-one-dimensional geometry. Our study is carried out by means of the newly developed multilayer-multiconfiguration time-dependent Hartree method for bosons, a numerical exact approach to simulate quantum many-body dynamics. In particular, we are interested in the scenario by which the ion is so strongly trapped that its motion can be effectively neglected. This enables us to focus on the atomic ensemble only. With the development of a model potential for the atom-ion interaction, we are able to numerically obtain the exact many-body ground state of the atomic ensemble in the presence of an ion. We analyze the influence of the atom number and the atom-atom interaction on the ground-state properties. Interestingly, for weakly interacting atoms, we find that the ion impedes the transition from the ideal gas behavior to the Thomas-Fermi limit. Furthermore, we show that this effect can be exploited to infer the presence of the ion both in the momentum distribution of the atomic cloud and by observing the interference fringes occurring during an expansion of the quantum gas. In the strong interacting regime, the ion modifies the fragmentation process in dependence of the atom number parity which allows a clear identification of the latter in expansion experiments. Hence, we propose in both regimes experimentally viable strategies to assess the impact of the ion on the many-body state of the atomic gas. This study serves as the first building block for systematically investigating the many-body physics of such hybrid system.

Schurer, J. M.; Schmelcher, P.; Negretti, A.

2014-09-01

155

Quantum-state transfer between tripod atoms over a dark fiber

NASA Astrophysics Data System (ADS)

In this work we introduce a model for quantum-state transfer between tripod atoms over a dark fiber. Two tripod atoms are confined in separate cavities linked by an optical fiber. The cavities and the fiber sustain two optical modes of opposite circular polarization. For each atom, the two ground states encode the quantum state to be transferred and are coupled to a common excited state by the cavity modes of opposite polarization. The remaining transition for each atom is used to control the transfer process. We demonstrate that by using laser pulses the dynamics of the system can be confined within a degenerate dark state subspace, with the different dark states interacting via nonadiabatic couplings. We solve analytically the dynamics in the dark state subspace, and determine the conditions on the pulse shape for the implementation of the quantum transfer. We identify a possible pulse shape which satisfies the required conditions, and demonstrate the quantum-state transfer via numerical simulations.

Bevilacqua, G.; Renzoni, F.

2013-09-01

156

Ground waves in atomic chains with bi-monomial double-well potential

Ground waves in atomic chains are traveling waves that corresponds to minimal non-trivial critical values of the underlying action functional. In this paper we study FPU-type chains with bi-monomial double-well potential and prove the existence of both periodic and solitary ground waves. To this end we minimize the action on the Nehari manifold and show that periodic ground waves converge to solitary ones. Finally, we compute ground waves numerically by a suitable discretization of a constrained gradient flow.

Michael Herrmann

2012-07-06

157

We discuss a model with ultra-cold atoms confined in optical superlattices. In particular, we study the ground-state properties of two spin-1 bosons trapped in a double-well potential. Depending on the external magnetic field and biquadratic interactions different phases of magnetic order are realized. Applying von Neumann entropy and number of relevant orbitals, we quantify the bipartite entanglement between particles. Changing the values of the parameters determining superlattices, we can switch the system between differently entangled states.

Artur Barasi?ski; Wies?aw Leo?ski; Tomasz Sowi?ski

2014-06-14

158

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

159

Ensemble Theory for Stealthy Hyperuniform Disordered Ground States

It has been shown numerically that systems of particles interacting with "stealthy" bounded, long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are, counterintuitively, disordered, hyperuniform and highly degenerate. Disordered hyperuniform systems have been receiving recent attention because they are distinguishable exotic states of matter poised between a crystal and liquid with novel properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in $d$-dimensional Euclidean space is highly nontrivial because the dimensionality of the configuration space depends on the number density $\\rho$ and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties that apply to any ground-state ensemble as a function of $\\rho$ in any $d$, and show how disordered degenerate ground states arise as part of the ground-state manifold. We then specialize our results to the canonical ensemble by exploiting an ansatz that stealthy states behave remarkably like "pseudo" equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for the structure and thermodynamic properties of the stealthy disordered ground states and associated excited states are in excellent agreement with computer simulations across the first three space dimensions. The development of this theory provides provide new insights regarding our fundamental understanding of the nature and formation of low-temperature states of amorphous matter. Our work also offers challenges to experimentalists to synthesize stealthy ground states at the molecular level.

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

2015-03-22

160

Ground electronic state of MgB2: Intrinsic nonadiabatic state at broken translation symmetry.

NASA Astrophysics Data System (ADS)

Study of the band structure of MgB2^ has shown that electron coupling to E2g phonon mode induces not only ?-bands splitting at ? point but also fluctuation of the top of one of ? band at the Fermi level, resulting in dramatic decrease of the Fermi energy. As a consequence, the original adiabatic state (?/EF < 1) corresponding to the equilibrium nuclear geometry has been changed to the intrinsic nonadiabatic state (?/EF >> 1) at distorted geometry, already at the displacement which is smaller than the rms. displacement of B-B atoms corresponding to zero-point energy of the E2g phonon mode. At these circumstances, not only Migdal theorem but also Born-Oppenheimer approximation has been broken, and standard treatment of EP interactions, including calculation of nonadiabatic corrections to adiabatic ground state by means of perturbation theory, can not be applied. Study of the electron-nuclear Hamiltonian by means of the quasiparticle unitary transformation (Q,P--dependent) which treats electrons and nuclei on the same footing, has revealed that EP interactions in the intrinsic nonadiabatic state stabilize the fermionic ground state of MgB2 at broken translation symmetry and corresponding wave function is dependent not only on nuclear coordinates, but it is strongly modulated mainly by nuclear momenta. From the results follow that in this case, instead of Cooper pairs formation, condensation process is represented rather by real-space, T-dependent formation of mobile bipolarons.

Banacky, Pavol

2006-03-01

161

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

162

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

2010-01-01

163

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

164

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 ...

165

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.

166

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=\\delt...

Sarkar, Resham; Fang, Renpeng; Tu, Yanfei; Shahriar, Selim M

2014-01-01

167

Ground-state properties of the periodic Anderson model

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

168

Chiral Ground States in a Frustrated Holographic Superconductor

Frustration is an important phenomenon in condensed matter physics because it can introduce a new order parameter such as chirality. Towards understanding a mechanism of the frustration in strongly correlated systems, we study a holographic superconductor model with three scalar fields and an interband Josephson coupling, which is important for the frustration. We analyze free energy of solutions of the model to determine ground states. We find chiral ground states, which have nonzero chirality.

Mitsuhiro Nishida

2015-02-28

169

Chiral Ground States in a Frustrated Holographic Superconductor

Frustration is an important phenomenon in condensed matter physics because it can introduce a new order parameter such as chirality. Towards understanding a mechanism of the frustration in strongly correlated systems, we study a holographic superconductor model with three scalar fields and an interband Josephson coupling, which is important for the frustration. We analyze free energy of solutions of the model to determine ground states. We find chiral ground states, which have nonzero chirality.

Nishida, Mitsuhiro

2015-01-01

170

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

171

Ground States Rotational Band in Deformed e-e Nuclei

In the frame work of the hydrodynamical model, a new model of the ground state rotational bands of deformed e-e nuclei is developed by introducing the variable moment of inertia, and the effect of beta- and gamma- vibrational bands. The model is applied to calculate the energies of the ground state band of 158Dy. The results of our calculations are in close agreement with data compared with other existing models.

Mohamed E. Kelabi; A. Y. Ahmed; Vikram Singh

2005-02-28

172

Ground States Rotational Band in Deformed e-e Nuclei

In the frame work of the hydrodynamical model, a new model of the ground state rotational bands of deformed e-e nuclei is developed by introducing the variable moment of inertia, and the effect of beta- and gamma- vibrational bands. The model is applied to calculate the energies of the ground state band of 158Dy. The results of our calculations are in close agreement with data compared with other existing models.

Kelabi, M E; Singh, V; Kelabi, Mohamed E.; Singh, Vikram

2005-01-01

173

Existence of Ground States of Nonlocal-Interaction Energies

NASA Astrophysics Data System (ADS)

We investigate which nonlocal-interaction energies have a ground state (global minimizer). We consider this question over the space of probability measures and establish a sharp condition for the existence of ground states. We show that this condition is closely related to the notion of stability (i.e. H -stability) of pairwise interaction potentials. Our approach uses the direct method of the calculus of variations.

Simione, Robert; Slep?ev, Dejan; Topaloglu, Ihsan

2015-02-01

174

Possible ground-state octupole deformation in /sup 229/Pa

Evidence is presented for the occurrence of a (5/2)/sup + -/ parity doublet as the ground state of /sup 229/Pa, in agreement with a previous theoretical prediction. The doublet splitting energy is measured to be 0.22 +- 0.05 keV. The relation of this doublet to ground-state octupole deformation is discussed. .ID LV2109 .PG 1762 1764

Ahmad, I.; Gindler, J.E.; Betts, R.R.; Chasman, R.R.; Friedman, A.M.

1982-12-13

175

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

176

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

2015-04-09

177

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

178

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

179

Ground state of stoichiometric B2 FeAl

NASA Astrophysics Data System (ADS)

The ground state of stoichiometric B2 FeAl has been controversial for decades in the literature, and the present first principles calculation is dedicated to have a systematic study of B2 FeAl with nonmagnetic (NM), ferromagnetic (FM), antiferromagnetic (AFM), and paramagnetic (PM) states. It is found that the energetic, mechanical, and electronic properties of FeAl are not sufficient to determine the ground state, and that it is lattice dynamics which fundamentally decides the ground state of NM for FeAl. In addition, it is also revealed that the electron-phonon interaction induces the negative phonon branches of AFM and PM states, and brings about much deeper phonon dips of FM than those of NM and experiments.

Ren, Q. Q.; Gong, H. R.

2013-09-01

180

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

181

Towards new states of matter with atoms and photons

Towards new states of matter with atoms and photons Jonas Larson Stockholm University and UniversitĂ¤t zu KĂ¶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

182

NASA Astrophysics Data System (ADS)

The extended Bose–Hubbard model for a double-well potential with pair tunneling is studied through both exact diagonalization and mean field theory (MFT). When pair tunneling is strong enough, the ground state wavefunction predicted by the MFT is complex and doubly degenerate while the quantum ground state wavefunction is always real and unique. The time reversal symmetry is spontaneously broken when the system transfers from the quantum ground state into one of the mean field ground states upon a small perturbation. As the gap between the lowest two levels decreases exponentially with particle number, the required perturbation inducing the spontaneous symmetry breaking (SSB) is infinitesimal for particle number of typical cold atom systems. The quantum ground state is further analyzed with the Penrose–Onsager criterion, and is found to be a fragmented condensate. The state also develops the pair correlation and has non-vanishing pair order parameter instead of the conventional single particle order parameter. When this model is generalized to optical lattice, a pair superfluid can be generated. The mean field ground state can be regarded as effective ground state in this simple model. The detailed computation for this model enables us to offer an in-depth discussion of the relation between SSB and effective ground state, giving a glimpse on how nonlinearity arises in the SSB of a quantum system.

Zhu, Qizhong; Zhang, Qi; Wu, Biao

2015-02-01

183

Nuclear Ground State Spins of the Francium Isotopes 208-213, 220-222Fr

The nuclear ground state spins of some francium isotopes have been measured using on-line atomic-beam magnetic resonance techniques. The following results have been obtained: 208Fr I = 7, 209Fr I = 9\\/2, 210Fr I = 6, 211Fr I = 9\\/2, 212Fr I = 5, 213Fr I = 9\\/2, 220Fr I = 1, 221Fr I = 5\\/2 and 222Fr I =

C. Ekström; S. Ingelman; G. Wannberg; M. Skarestad

1978-01-01

184

The acid–base properties of alloxazine (All) and its methyl derivatives have been studied in their ground and first excited singlet states. The concept of an effective electronic valence potential was applied to predict the changes in basicity and acidity of heteroatoms upon excitation and substitution. Changes in the acid–base properties of N(1) and N(10) nitrogen atoms are particularly important from

Ewa Sikorska; Henryk Szymusiak; Igor V Khmelinskii; Anna Kozio?owa; Jens Spanget-Larsen; Marek Sikorski

2003-01-01

185

Graph states as ground states of two-body frustration-free Hamiltonians

The framework of measurement-based quantum computation (MBQC) allows us to view the ground states of local Hamiltonians as potential resources for universal quantum computation. A central goal in this field is to find models with ground states that are universal for MBQC and that are also natural in the sense that they involve only two-body interactions and have a small local Hilbert space dimension. Graph states are the original resource states for MBQC, and while it is not possible to obtain graph states as exact ground states of two-body Hamiltonians here we construct two-body frustration-free Hamiltonians that have arbitrarily good approximations of graph states as unique ground states. The construction involves taking a two-body frustration-free model that has a ground state convertible to a graph state with stochastic local operations, then deforming the model such that its ground state is close to a graph state. Each graph state qubit resides in a subspace of a higher dimensional particle. This deformation can be applied to two-body frustration-free Affleck-Kennedy-Lieb-Tasaki (AKLT) models, yielding Hamiltonians that are exactly solvable with exact tensor network expressions for ground states. For the star-lattice AKLT model, the ground state of which is not expected to be a universal resource for MBQC, applying such a deformation appears to enhance the computational power of the ground state, promoting it to a universal resource for MBQC. Transitions in computational power, similar to percolation phase transitions, can be observed when Hamiltonians are deformed in this way. Improving the fidelity of the ground state comes at the cost of a shrinking gap. While analytically proving gap properties for these types of models is difficult in general, we provide a detailed analysis of the deformation of a spin-1 AKLT state to a linear graph state.

Andrew S. Darmawan; Stephen D. Bartlett

2014-07-10

186

Structure of ground and excited states of $^{12}$C

We studied the ground and excited states of $^{12}$C based on variational calculations after spin-parity projection in a framework of antisymmetrized molecular dynamics(AMD). The calculations systematically reproduce various experimental data. It was found that the sub-shell closure and SU(3)-limit $3\\alpha$ cluster components are contained in the ground state, while various $3\\alpha$ cluster structures develop in the excited states. We discussed effects of $\\alpha$ breaking and show the importance of coexistence of the cluster and shell-model-like aspects.

Y. Kanada-En'yo}

2006-05-20

187

Spin of the sup 219 Ra ground state

The {sup 208}Pb({sup 18}O,3{ital n}){sup 223}Th reaction at 83 MeV bombarding energy was used to populate the alpha-radioactive nucleus {sup 223}Th. Out-of-beam alpha-gamma coincidences were recorded at correlation angles of 90{degree} and 180{degree}. The {ital a}{sub 2} angular correlation coefficient was extracted for an alpha-gamma cascade to the {sup 215}Rn ground state via the 0.316 MeV excited state. This limited the assignment of the ground-state spin of {sup 219}Ra to ((7/2, 11) / 2 ){sup +}. .AE

Hackett, E.D.; Kuehner, J.A.; Waddington, J.C. (Tandem Accelerator Laboratory, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (CA)); Jones, G.D. (Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom)

1989-09-01

188

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

189

Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance

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

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

2011-01-01

190

Ground States for Mean Field Models with a Transverse Component

NASA Astrophysics Data System (ADS)

We investigate global logarithmic asymptotics of ground states for a family of quantum mean field models in transverse field. Our approach is based on a stochastic representation and a combination of large deviation and weak KAM techniques. We prove that asymptotic ground states are weak KAM (Fathi in C. R. Acad. Sci., Ser. I Math. 324(9):1043-1046, 1997; Fathi, The Weak KAM Theorem in Lagrangian Dynamics 10th Preliminary Version, 2008; Fathi in Nonlinear Differ. Equ. Appl. 14(1):1-27, 2007) and, in particular, viscosity (Capuzzo-Dolcetta and Lions in Trans. Am. Math. Soc. 318(2):643-683, 1990; Fathi, The Weak KAM Theorem in Lagrangian Dynamics 10th Preliminary Version, 2008, Chap. 7) solutions of certain stationary Hamilton-Jacobi equations. In general such solutions are not unique, and additional refined selection criteria are needed. The spin-1/2 model is worked out in more detail. We discuss phase transitions in the ground state as the strength of the transverse field varies. For a class of mean field interaction potentials this transition is of the first order. For all the models in question, asymptotic ground states with multiple wells necessarily develop shocks. A complete description of asymptotic ground states is derived for ferromagnetic p-body interactions.

Ioffe, Dmitry; Levit, Anna

2013-06-01

191

A single laser system for ground-state cooling of 25Mg+

NASA Astrophysics Data System (ADS)

We present a single solid-state laser system to cool, coherently manipulate and detect 25Mg+ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources.

Hemmerling, B.; Gebert, F.; Wan, Y.; Nigg, D.; Sherstov, I. V.; Schmidt, P. O.

2011-09-01

192

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

193

NASA Astrophysics Data System (ADS)

We propose a scheme for generation of the W state and the Greenberger-Horn-Zeilinger (GHZ) state of atomic ensembles. The scheme is based on the dynamics of a single control atom and atomic ensembles interacting with a nonresonant cavity mode. By choosing the appropriate parameters, the effective Hamiltonian describing the interaction between the control atom and the atomic modes shows complete analogy with the Jaynes-Cummings Hamiltonian. The required time for preparing the W state (GHZ state) keeps unchanged (increases linearly) with the increase of the number of atomic ensembles. The effects of dissipation and the detuning between the atomic modes and the control atom on the prepared states are analyzed by numerical simulation.

Zhang, Chun-Ling; Li, Wen-Zhang; Chen, Mei-Feng

2014-02-01

194

Degenerate ground state and quantum tunneling in rotating condensates

Quantum tunneling introduces a fundamental difference between classical and quantum mechanics. Whenever the classical ground state is non-unique (degenerate), quantum mechanics restore uniqueness thanks to tunneling. A condensate in a rotating trap with a vortex can have such a degenerate classical ground state, a degeneracy that is excluded in the absence of rotation at least when the Gross-Pitaevskii equation applies. If the rotating trap has a center of symmetry, like a figure eight (a peanut), the vortex may be on either side with the same energy yielding a degenerate ground state, a degeneracy lifted by quantum tunneling. We explain how to compute the rate of tunneling in the WKB limit by estimating the action of the trajectory in the Euclidean version of the dynamics.

Qiang Du; Martine Le Berre; Yves Pomeau

2012-09-07

195

Analysis of ground state in random bipartite matching

In human society, a lot of social phenomena can be concluded into a mathematical problem called the bipartite matching, one of the most well known model is the marriage problem proposed by Gale and Shapley. In this article, we try to find out some intrinsic properties of the ground state of this model and thus gain more insights and ideas about the matching problem. We apply Kuhn-Munkres Algorithm to find out the numerical ground state solution of the system. The simulation result proves the previous theoretical analysis using replica method. In the result, we also find out the amount of blocking pairs which can be regarded as a representative of the system stability. Furthermore, we discover that the connectivity in the bipartite matching problem has a great impact on the stability of the ground state, and the system will become more unstable if there were more connections between men and women.

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

2015-01-01

196

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

197

Ground-State Electromagnetic Moments of Calcium Isotopes

High-resolution bunched-beam collinear laser spectroscopy was used to measure the optical hyperfine spectra of the $^{43-51}$Ca isotopes. The ground state magnetic moments of $^{49,51}$Ca and quadrupole moments of $^{47,49,51}$Ca were measured for the first time, and the $^{51}$Ca ground state spin $I=3/2$ was determined in a model-independent way. Our results provide a critical test of modern nuclear theories based on shell-model calculations using phenomenological as well as microscopic interactions. The results for the neutron-rich isotopes are in excellent agreement with predictions using interactions derived from chiral effective field theory including three-nucleon forces, while lighter isotopes illustrate the presence of particle-hole excitations of the $^{40}$Ca core in their ground state.

Ruiz, R F Garcia; Blaum, K; Frommgen, N; Hammen, M; Holt, J D; Kowalska, M; Kreim, K; Menendez, J; Neugart, R; Neyens, G; Nortershauser, W; Nowacki, F; Papuga, J; Poves, A; Schwenk, A; Simonis, J; Yordanov, D T

2015-01-01

198

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

199

Correlation induced paramagnetic ground state in FeAl.

Experimentally the intermetallic compound FeAl is known to be nonmagnetic, whereas conventional density functional theory calculations within the local density approximation always yield a ferromagnetic ground state with a magnetic moment at the Fe site of about 0.7 mu(B). We show that a correlation correction within the LDA+U scheme yields a nonmagnetic ground state for U>or=3.7 eV using two different implementations. The disappearance of the magnetic ground state occurs since Fe-t(2g) and Fe-e(g) manifolds are affected differently by a common U. For large values of U a magnetic solution reappears as expected for strong correlation. PMID:11690436

Mohn, P; Persson, C; Blaha, P; Schwarz, K; Novák, P; Eschrig, H

2001-11-01

200

Ground states in non-relativistic quantum electrodynamics

. The excited states of a charged particle interacting with the quantized electromagnetic field and an external potential all\\u000a decay, but such a particle should have a true ground state – one that minimizes the energy and satisfies the Schrödinger equation.\\u000a We prove quite generally that this state exists for all values of the fine-structure constant and the ultraviolet cutoff.

Marcel Griesemer; Elliott H. Lieb; Michael Loss

2001-01-01

201

Ground states in non-relativistic quantum electrodynamics

The excited states of a charged particle interacting with the quantized electromagnetic field and an external potential all\\u000a decay, but such a particle should have a true ground state — one that minimizes the energy and satisfies the Schrödinger equation.\\u000a We prove quite generally that this state exists for all values of the fine-structure constant and the ultraviolet cutoff. We

Marcel Griesemer; Elliott H. Lieb; Michael Loss

202

Ground and Excited State Spectra of a Quantum Dot

NASA Astrophysics Data System (ADS)

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

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

1998-03-01

203

The ground state rotational spectrum of the fluorosulfate radical

NASA Astrophysics Data System (ADS)

The rotational spectra of the fluorosulfate (FSO3? ) molecular radical in its vibronic ground state were measured in the millimeter-wave region and analyzed in detail using the matrix elements of the rotational, fine, and hyperfine Hamiltonian terms. The analysis of the assigned transition frequencies made it possible to derive very precise values of the rotational, centrifugal distortion and fine structure constants and to confirm the C3 v molecular symmetry of the vibronic ground state unambiguously. In addition, an effective parameter of the "A1-A2 splitting" was determined. The rotational transitions of the FSO3? free radical were observed, identified, and analyzed for the first time.

Kolesniková, Lucie; Varga, Juraj; St?íteská, Lucie Nová; Beckers, Helmut; Willner, Helge; Aubke, Friedhelm; Urban, Št?pán

2009-05-01

204

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

205

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

206

Quantum ground states: Manipulation and approximation

NASA Astrophysics Data System (ADS)

The low energy spectrum of quantum many-body systems is often a subject of great interest to physicists. This thesis covers two subject areas, both involving the study of low energy eigenstates of quasi-local spin-1/2 Hamiltonians. Part I of the thesis is on numerical methods for condensed matter models. Among the many methods used by physicists to study low energy spectra, contractor renormalization (CORE) is a regularly used but poorly understood method. First, I show that its performance on finite Ising chains is comparable to the popular density matrix renormalization (DMRG) method, and that it bears slight theoretical resemblance to entanglement renormalization, a variant of DMRG. Moving on to two dimensions, I perform a series of numerical tests with the Heisenberg antiferromagnet to see the effect of different blocking schemes. I also propose a bootstrap method for approximating long-range terms in CORE. The tests show that on one hand, CORE is capable of revealing very interesting physical pictures. This includes renormalization group flows that reveal a phase transition in a two-dimensional frustrated antiferromagnet. On the other hand, the results also show that the accuracy of the method can be very sensitive to truncation schemes, blocking geometries and long-range terms, so there are important ambiguities and potential sources of error that researchers must pay attention to in using CORE. Part II of this thesis turns to some questions raised by two quantum computing paradigms: the adiabatic (linear interpolation) model and the holonomic model. First, I show that even though the two models appear very different, a well-known algorithm can be interpreted in terms of both. Secondly, I discuss in a general setting how the issue of locality affects the design of adiabatic algorithms. Finally, I propose a new type of adiabatic algorithm, called adiabatic rotation, which traces out arcs in the parameter space of Hamiltonians and has uses in implementing specific unitary transformations, generating known interesting states and solving search problems.

Siu, Ming-Ho Stewart

207

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

208

Generation of atomic NOON states via adiabatic passage

We propose a scheme for generating atomic NOON states via adiabatic passage. In the scheme, a double $\\Lambda$-type three-level atom is trapped in a bimodal cavity and two sets of $\\Lambda$-type three-level atoms are translated into and outside of two single mode cavities respectively. The three cavities connected by optical fibres are always in vacuum states. After a series of operations and suitable interaction time, we can obtain arbitrary large-$n$ NOON states of two sets of $\\Lambda$-type three-level atoms in distant cavities by performing a single projective measurement on the double $\\Lambda$-type three-level atom. Due to adiabatic elimination of atomic excited states and the application of adiabatic passage, our scheme is robust against the spontaneous emissions of atoms, the decays of fibres and cavities photon leakage. So the scheme has a high fidelity and feasibility under the current available techniques.

Qi-Gong Liu; Qi-Cheng Wu; Xin Ji; Shou Zhang

2014-05-24

209

Generation of atomic NOON states via adiabatic passage

NASA Astrophysics Data System (ADS)

We propose a scheme for generating atomic NOON states via adiabatic passage. In the scheme, a double -type three-level atom is trapped in a bimodal cavity, and two sets of -type three-level atoms are translated into and outside of two single-mode cavities, respectively. The three cavities connected by optical fibers are always in vacuum states. After a series of operations and suitable interaction time, we can obtain arbitrary large- NOON states of two sets of -type three-level atoms in distant cavities by performing a single projective measurement on the double -type three-level atom. Our scheme is robust against the spontaneous emissions of atoms, the decays of fibers, and photon leakage of cavities, due to the adiabatic elimination of atomic excited states and the application of adiabatic passage.

Liu, Qi-Gong; Wu, Qi-Cheng; Leng, Chun-Ling; Liang, Yan; Ji, Xin; Zhang, Shou

2014-12-01

210

Conditional Quantum Phase Gate between Two 3-State Atoms

NASA Astrophysics Data System (ADS)

We propose a scheme for conditional quantum logic between two 3-state atoms that share a quantum data bus such as a single mode optical field in cavity QED systems, or a collective vibrational state of trapped ions. Making use of quantum interference, our scheme achieves successful conditional phase evolution without any real transitions of atomic internal states or populating the quantum data bus. In addition, it requires only common addressing of the two atoms by external laser fields.

Yi, X. X.; Su, X. H.; You, L.

2003-03-01

211

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

212

Steady-State Two Atom Entanglement in a Pumped Cavity

In this paper we explore the possibility of a steady-state entanglement of two two-level atoms inside a pumped cavity by taking into account cavity leakage and the spontaneous emission of photons by the atoms. We describe the system in the dressed state picture in which the coherence is built into the dressed states while transitions between the dressed states are incoherent. Our model assumes the vacuum Rabi splitting of the dressed states to be much larger than any of the decay parameters of the system which allows atom-field coherence to build up before any decay process takes over. We show that, under our model, a pumping field cannot entangle two closed two-level atoms inside the cavity in the steady-state, but a steady-state entanglement can be achieved with two open two-level atoms.

Hideomi Nihira; C. R. Stroud Jr

2009-08-11

213

Asymptotics of Ground State Degeneracies in Quiver Quantum Mechanics

We study the growth of the ground state degeneracy in the Kronecker model of quiver quantum mechanics. This is the simplest quiver with two gauge groups and bifundamental matter fields, and appears universally in the context of BPS state counting in four-dimensional N=2 systems. For large ranks, the ground state degeneracy is exponential with slope a modular function that we are able to compute at integral values of its argument. We also observe that the exponential of the slope is an algebraic number and determine its associated algebraic equation explicitly in several examples. The speed of growth of the degeneracies, together with various physical features of the bound states, suggests a dual string interpretation.

Cordova, Clay

2015-01-01

214

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

215

GROUND STATES AND DYNAMICS OF SPIN-ORBIT-COUPLED ...

sical limit of the CGPEs in the linear case via the Wigner transform method. ... Numerical results are reported to demonstrate the efficiency and accuracy of ... At temperatures T much smaller than the critical temperature Tc, following the ..... when ?=0 the ground state is unique up to a constant phase factor if the matrix A.

2014-11-07

216

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 translationally invariant models in presence of an external uniform magnetic field can admit exact, fully factorized ground state solutions. Unentangled ground states occur at finite values of the Hamiltonian parameters satisfying well defined balancing conditions between the applied field and the 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 complexity, including translationally-invariant models with short, long, and infinite ranges of interaction, as well as systems with spatial anisotropies, in low and higher dimensions. We also illustrate how the general method, besides yielding a large series of novel exact results for complex models in any dimension, recovers, as particular cases, the results previously achieved on simple models in low dimensions exploiting direct methods based on factorized mean-field ansatz.

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

2009-06-04

217

Ground State Quantum Coherences: from Quantum Beats to Strong Control

Second order correlations reveal quantum beats from a coherent ground-state superposition on the undriven mode of a two-mode cavity QED system. Continuous drive induces decoherence due to Rayleigh scattering. We control this with feedback and explore postselection techniques to extract specific behavior.

Andres D. Cimmarusti; Burkley D. Patterson; Luis A. Orozco; Wanderson M. Pimenta; Pablo Barberis-Blostein; Howard J. Carmichael

2014-01-14

218

Ground-state entanglement in interacting bosonic graphs

We consider a collection of bosonic modes corresponding to the vertices of a graph Gamma. Quantum tunneling can occur only along the edges of Gamma and a local self-interaction term is present. Quantum entanglement of one vertex with respect to the rest of the graph (mode entanglement) is analyzed in the ground state of the system as a function of

Paolo Giorda; Paolo Zanardi

2004-01-01

219

Ground State Magnetic Moments of Mirror Nuclei Studied at NSCL

Progress in the measurement of the ground state magnetic moments of mirror nuclei at NSCL is presented. The systematic trend of the spin expectation value $$ and the linear behavior of $\\gamma_p$ versus $\\gamma_n$, both extracted from the magnetic moments of mirror partners, are updated to include all available data.

P. F. Mantica; K. Minamisono

2009-01-22

220

Ground states of a model in nonrelativistic quantum electrodynamics. II

The system of N-nonrelativistic spineless particles minimally coupled to a massless quantized radiation field with an ultraviolet cutoff is considered. The Hamiltonian of the system is defined for arbitrary coupling constants in terms of functional integrals. It is proved that the ground state of the system with a class of external potentials, if they exist, is unique. Moreover an expression

Fumio Hiroshima; Zentrum Mathematik

2000-01-01

221

On the Ground State Wave Function of Matrix Theory

We propose an explicit construction of the leading terms in the asymptotic expansion of the ground state wave function of BFSS SU(N) matrix quantum mechanics. Our proposal is consistent with the expected factorization property in various limits of the Coulomb branch, and involves a different scaling behavior from previous suggestions. We comment on some possible physical implications.

Ying-Hsuan Lin; Xi Yin

2014-02-01

222

By measurements of phosphorescence and transient absorption spectra as well as steady-state photolysis of the title compound (NNV), it is concluded as follows: (1) In benzene and ethanol, intersystem crossing from the lowest excited singlet (1NNV?) to triplet (3NNV?) states competes withvalence isomerization of 1NNV? yielding ground-state naphthoylnaphthalene (NN). (2) In ethanol, the NNV ketyl radical (generated by hydrogen-atom abstraction

Toshihiro Nakayama; Tetsuhiko Nagahara; Sadao Miki; Kumao Hamanoue

1997-01-01

223

Controlled probabilistic quantum key distribution using a ground state

NASA Astrophysics Data System (ADS)

In this paper, we propose two controlled probabilistic quantum key distribution protocols with AKLT states. An AKLT state is a gapped ground state with minimum energy, and owing to the properties of this special state, our proposed protocols incorporate not only the measurement uncertainty in quantum phenomena (entanglement swapping with 1/4 probability) but also additional randomness (Bell measurement on two physical particles with 1/3 probability), in comparison with other PQKD schemes. Therefore, our protocols are more suitable for use by two mutually untrusted communicants, with no authenticated intermediate channel, allowing them to obtain an unpredictable, and therefore secure, key.

Liu, Lin-Lin; Hwang, Tzonelih

2015-03-01

224

Sideband cooling while preserving coherences in the nuclear spin state in group-II-like atoms.

We propose a method for laser cooling group-II-like atoms without changing the quantum state of their nuclear spins, thus preserving coherences that are usually destroyed by optical pumping in the cooling process. As group-II-like atoms have a (1)S(0) closed-shell ground state, nuclear spin and electronic angular momentum are decoupled, allowing for their independent manipulation. The hyperfine interaction that couples these degrees of freedom in excited states can be suppressed through the application of external magnetic fields. Our protocol employs resolved-sideband cooling on the forbidden clock transition, (1)S(0) --> (3)P(0), with quenching via coupling to the rapidly decaying (1)P(1) state, deep in the Paschen-Back regime. This makes it possible to laser cool neutral atomic qubits without destroying the quantum information stored in their nuclear spins, as shown in two examples, (171)Yb and (87)Sr. PMID:17930500

Reichenbach, Iris; Deutsch, Ivan H

2007-09-21

225

Ground state correlations in 16O and 40Ca

NASA Astrophysics Data System (ADS)

We study the ground state properties of doubly closed shell nuclei 16O and 40Ca in the framework of correlated basis function theory using state dependent correlations, with central and tensor components. The realistic Argonne v14 and v'8 two-nucleon potentials and three-nucleon potentials of the Urbana class have been adopted. By means of the Fermi hypernetted chain integral equations, in conjunction with the single operator chain approximation, we evaluate the ground state energy, one- and two-body densities and electromagnetic and spin static responses for both nuclei. In 16O we compare our results with the available Monte Carlo and coupled cluster ones and find a satisfying agreement. As in the nuclear matter case with similar interactions and wave functions, the nuclei result underbound by 2-3 MeV/nucleon.

Fabrocini, A.; Arias de Saavedra, F.; Co', G.

2000-04-01

226

Ground state in the finite Dicke model for interacting qubits

NASA Astrophysics Data System (ADS)

We study the ground state of a finite-size ensemble of interacting qubits driven by a quantum field. We find a maximally entangled W state in the ensemble part of the system for a certain region of the coupling parameters. The area of this region decreases as the ensemble size increases and, in the classical limit, becomes the line in parameter space that defines the phase transition of the system. In the classical limit, we also study the dynamics of the system and its transition from order to disorder for initial energies close to the ground-state energy. We find that a critical energy providing this transition is related to the minimum of the projection of the total angular momentum of the quantum system in the z direction.

Robles Robles, R. A.; Chilingaryan, S. A.; Rodríguez-Lara, B. M.; Lee, Ray-Kuang

2015-03-01

227

Ground-State Degeneracy of Topological Phases on Open Surfaces

NASA Astrophysics Data System (ADS)

We relate the ground state degeneracy of a non-Abelian topological phase on a surface with boundaries to the anyon condensates that break the topological phase into a trivial phase. Specifically, we propose that gapped boundary conditions of the surface are in one-to-one correspondence with the sets of condensates, each being able to completely break the phase, and we substantiate this by examples. The ground state degeneracy 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-Tao-Wu charge-pumping argument for Abelian fractional quantum Hall states to encompass non-Abelian topological phases, in the sense that an anyon loop of a confined anyon winding a nontrivial cycle can pump a condensed anyon from one boundary to another. Such generalized pumping may find applications in quantum control of anyons, eventually realizing topological quantum computation.

Hung, Ling-Yan; Wan, Yidun

2015-02-01

228

The ground state torsion rotation spectrum of CH2DOH

NASA Astrophysics Data System (ADS)

The ground state torsion rotation spectrum of CH2DOH has been completely characterized through J = 30 and Ka = 10, 9, 9 in the three torsional sub-states of the ground state; e0, e1, and o1, respectively. Additional a-type assignments are presented to Ka = 11 in each of the torsional sub-states. The data has been analyzed with an empirical power series model as well as an empirical internal axis model. Over 8000 transitions have been assigned and fit with near experimental accuracy over the range of 4-1628 GHz. The characterization of the spectrum allows for a complete set of ground state term values enabling a better understanding of the infrared spectrum. Comparison of the torsional contributions of the Hamiltonian with normal methanol provides great insight into the nature of the asymmetric-top asymmetric-frame internal rotation problem. The comparison with normal methanol also provides a relatively straightforward transformation from the well understood C3V internal rotation problem to the completely asymmetric internal rotation problem. The data and analysis provide some practical wisdom on the impacts of breaking the symmetry and the choice of models for addressing the nearly three fold completely asymmetric internal rotation problem.

Pearson, John C.; Yu, Shanshan; Drouin, Brian J.

2012-10-01

229

Creation of Ultracold 87Rb 133Cs Molecules in the Rovibrational Ground State

NASA Astrophysics Data System (ADS)

We report the creation of a sample of over 1000 ultracold 87Rb 133Cs molecules in the lowest rovibrational ground state, from an atomic mixture of 87Rb and 133Cs, 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 h c ×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.

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.

2014-12-01

230

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

231

NASA Astrophysics Data System (ADS)

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 Schrödinger-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 ? 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 ? 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.; Salasnich, L.; Parola, A.; Toigo, F.

2011-05-01

232

A recent paper by Rutherford and Vroom (1971) showed that the charge transfer reaction of the metastable O+(2D) with N2 was significantly faster than the ground state, O+(4S), reaction. Similarly, Stebbings et al. (1966) showed that the charge transfer with O2 was at least an order of magnitude greater for the excited O+(2D) than the ground state atomic oxygen ion.

Ronald P. Rohrbaugh; Wesley E. Swartz; Romualdas Simonaitis; John S. Nisbet

1973-01-01

233

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

234

NASA Technical Reports Server (NTRS)

Semiclassical calculations are carried out for the quenching of excited-state fluorine atom by collinear collisions with hydrogen molecule. The overall quenching probability is the sum of two contributions: the reactive quenching probability associated with the formation of hydrogen fluoride and the nonreactive quenching probability leading to ground-state fluorine atom and hydrogen molecule. The reactive probability is greater in the threshold region of the collision energy, whereas the nonreactive probability dominates for energies above the threshold region.

Yuan, J.-M.; Skuse, B. M.; Jaffe, R. L.; Komornicki, A.; Morokuma, K.; George, T. F.

1980-01-01

235

Nuclear quadrupole moment of the {sup 99}Tc ground state

By combining first-principles calculations and existing nuclear magnetic resonance (NMR) experiments, we determine the quadrupole moment of the 9/2{sup +} ground state of {sup 99}Tc to be (-)0.14(3)b. This confirms the value of -0.129(20)b, which is currently believed to be the most reliable experimental determination, and disagrees with two earlier experimental values. We supply ab initio calculated electric-field gradients for Tc in YTc{sub 2} and ZrTc{sub 2}. If this calculated information would be combined with yet to be performed Tc-NMR experiments in these compounds, the error bar on the {sup 99}Tc ground state quadrupole moment could be further reduced.

Errico, Leonardo [Departamento de Fisica and Instituto de Fisica La Plata (IFLP, CCT-La Plata, CONICET-UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Coreo 67, 1900 La Plata (Argentina); Universidad Nacional del Noroeste Bonaerense (UNNOBA), Monteagudo 2772, 2700 Pergamino (Argentina); Darriba, German; Renteria, Mario [Departamento de Fisica and Instituto de Fisica La Plata (IFLP, CCT-La Plata, CONICET-UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Coreo 67, 1900 La Plata (Argentina); Tang Zhengning [Bayerisches Geoinstitut, Universitaet Bayreuth, DE-95440 Bayreuth (Germany); Emmerich, Heike [Computational Materials Engineering (CME), Institute for Minerals Engineering (GHI), Center for Computational Engineering Science - CCES and Juelich-Aachen Research Alliance - JARA, RWTH Aachen University, DE-52064 Aachen (Germany); Cottenier, Stefaan [Computational Materials Engineering (CME), Institute for Minerals Engineering (GHI), Center for Computational Engineering Science - CCES and Juelich-Aachen Research Alliance - JARA, RWTH Aachen University, DE-52064 Aachen (Germany) and Instituut voor Kern-en Stralingsfysica and INPAC, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, BE-3001 Leuven (Belgium)

2008-05-15

236

Nuclear Magnetic Moment of the 57Cu Ground State

The nuclear magnetic moment of the ground state of 57Cu has been measured to be 2.00 +/- 0.05 nuclear magnetons (nm) using the beta-NMR technique. Together with the known magnetic moment of the mirror partner 57Ni, the spin extraction value was extracted as -0.78 +/- 0.13. This is the heaviest isospin T=1/2 mirror pair above the 40Ca region, for which both ground state magnetic moments have been determined. Shell model calculations in full fp shell giving mu(57Cu)~2.4 nm and ~0.5 imply significant shell breaking at 56Ni with the neutron number N=28.

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

2006-02-16

237

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

238

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

239

Detecting topological order in a ground state wave function.

A large class of topological orders can be understood and classified using the string-net condensation picture. These topological orders can be characterized by a set of data (N, di, F(lmn)(ijk), delta(ijk). We describe a way to detect this kind of topological order using only the ground state wave function. The method involves computing a quantity called the "topological entropy" which directly measures the total quantum dimension D= Sum(id2i). PMID:16605803

Levin, Michael; Wen, Xiao-Gang

2006-03-24

240

Electron g Value in the Ground State of Deuterium

The ratio of the electron gJ in the deuterium ground state to the proton gp in a cylindrical mineral oil sample has been measured. The measurement was made using the microwave magnetic resonance absorption method and apparatus which Beringer and Heald used to determine -gJgp for hydrogen. The three strong-field Zeeman transitions having DeltamJ=+\\/-1, DeltamI=0 were observed at a frequency

J. S. Geiger; V. W. Hughes; H. E. Radford

1957-01-01

241

Perturbation Treatment of the Ground State of HeH+ +

Rayleigh—Schro¨dinger perturbation calculations are carried out for the ground state of the HeH+ + molecular ion. The zeroth-order wavefunction is &psgr;=Nexp(??ZArA??ZBrB). The expectation value of the Hamiltonian calculated with the wavefunction accurate through first order, E(1), is compared with the accurate series calculations of Bates and Carson and found to agree up to five places. Also the values of the

Robert L. Matcha; William D. Lyon; Joseph O. Hirschfelder

1965-01-01

242

Perturbation Treatment of the Ground State of H2+

Rayleigh—Schro¨dinger perturbation calculations are carried out for the ground state of the H2+ molecular ion. The zeroth-order wavefunction for this problem is chosen to be the Guillemin and Zener variational function &psgr;=N[exp(??rA??rB)+exp(??rA??rB)]. The energies through third order and the expectation value E(1) of the Hamiltonian calculated with the wavefunction accurate through first order are computed for various choices of the

William D. Lyon; Robert L. Matcha; William A. Sanders; William J. Meath; Joseph O. Hirschfelder

1965-01-01

243

Frustrated systems: Ground state properties via combinatorial optimization

An introduction to the application of combinatorial optimization methods to ground state calculations of frustrated, disordered\\u000a systems is given. We discuss the interface problem in the random bond Ising ferromagnet, the random field Ising model, the\\u000a diluted antiferromagnet in an external field, the spin glass problem, the solid-on-solid model with a disordered substrte\\u000a and other convex cost flow problems occurring

Heiko Rieger

1998-01-01

244

Lower bounds for ground states of condensed matter systems

NASA Astrophysics Data System (ADS)

Standard variational methods tend to obtain upper bounds on the ground state energy of quantum many-body systems. Here we study a complementary method that determines lower bounds on the ground state energy in a systematic fashion, scales polynomially in the system size and gives direct access to correlation functions. This is achieved by relaxing the positivity constraint on the density matrix and replacing it by positivity constraints on moment matrices, thus yielding a semi-definite programme. Further, the number of free parameters in the optimization problem can be reduced dramatically under the assumption of translational invariance. A novel numerical approach, principally a combination of a projected gradient algorithm with Dykstra's algorithm, for solving the optimization problem in a memory-efficient manner is presented and a proof of convergence for this iterative method is given. Numerical experiments that determine lower bounds on the ground state energies for the Ising and Heisenberg Hamiltonians confirm that the approach can be applied to large systems, especially under the assumption of translational invariance.

Baumgratz, Tillmann; Plenio, Martin B.

2012-02-01

245

Efficient determination of alloy ground-state structures

NASA Astrophysics Data System (ADS)

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

Seko, Atsuto; Shitara, Kazuki; Tanaka, Isao

2014-11-01

246

New approach to hyperfine structure - Application to the Li ground state

NASA Technical Reports Server (NTRS)

Global identities for delta functions, given by Hiller, Sucher and Feinberg (HSF) are applied to the calculation of the hyperfine structure (HFS) of the ground state of Li. It is shown that use of the HSF identity together with configuration interaction type wavefunctions can yield values of the HFS constant f which are comparable in accuracy to that obtained by Larsson with a 100-term Hylleraas-type wavefunction. The implications of this result for HFS calculations for atoms with many electrons are discussed.

Bhatia, A. K.; Sucher, J.

1980-01-01

247

ac Electric Trap for Ground-State Molecules

We here report on the realization of an electrodynamic trap, capable of trapping neutral atoms and molecules in both low-field and high-field seeking states. Confinement in three dimensions is achieved by switching between two electric field configurations that have a saddle point at the center of the trap, i.e., by alternating a focusing and a defocusing force in each direction.

Jacqueline van Veldhoven; Hendrick L. Bethlem; Gerard Meijer

2005-01-01

248

Quantum state manipulation of single-Cesium-atom qubit in a micro-optical trap

NASA Astrophysics Data System (ADS)

Based on single Cesium atoms trapped in a 1064 nm microscopic optical trap we have exhibited a single qubit encoded in the Cesium "clock states". The single qubit initialization, detection and the fast state rotation with high efficiencies are demonstrated and this state manipulation is crucial for quantum information processing. The ground states Rabi flopping rate of 229.0 ± 0.6 kHz is realized by a two-photon Raman process. A clock states dephasing time of 3.0±0.7 ms is measured, while an irreversible homogeneous dephasing time of 124±17 ms is achieved by using the spin-echo technique. This well-controlled single atom provides an idea quantum qubit and quantum node for quantum information processing.

Wang, Zhi-Hui; Li, Gang; Tian, Ya-Li; Zhang, Tian-Cai

2014-10-01

249

Ground states of spin-1 bosons in asymmetric double wells

NASA Astrophysics Data System (ADS)

In this work we investigate the different states of a system of spin-1 bosons in two potential wells connected by tunneling, with spin-dependent interaction. The model utilizes the well-known Bose-Hubbard Hamiltonian, adding a local interaction term that depends on the modulus of the total spin in a well, favoring a high- or low-spin state for different signs of the coupling constant. We employ the concept of fidelity to detect critical values of parameters for which the ground state undergoes significant changes. The nature of the states is investigated through evaluation of average occupation numbers in the wells and of spin correlations. A more detailed analysis is done for a two-particle system, but a discussion of the three-particle case and some results for larger numbers are also presented.

Carvalho, D. W. S.; Foerster, A.; Gusmăo, M. A.

2015-03-01

250

The reactions of excited Cs atoms with various gases have been studied in a quadrupole mass spectrometer ion source. The excited atoms are formed in a thermionic converter (TIC) plasma and are sampled into the ion source as a molecular beam. Direct field ionization of the excited states from the plasma at field strengths up to 600 V\\/cm in the

Joergen Lundin; Leif Holmlid

1991-01-01

251

Ground-state fine structure in the boron isoelectronic sequence

NASA Astrophysics Data System (ADS)

Reference is made to the study by Hata et al. (1983), which showed that MCDF-EAL calculations (Grant et al., 1980; McKenzie et al., 1980) largely remove the discrepancies between theory and experiment so long as pure hydrogenic corrections for electron self energy are used. Similar methods are applied here to the ground 2P interval in the boron isoelectronic sequence, and the results thus obtained are compared with experiment and with other recent calculations (Froese Fischer, 1983; Frye et al., 1983). It is found the the MCDF-EAL method gives very good quality results when the transition energies for delta n are equal to 0. The discrepancy between the three-configuration results and experiment is comparable with quoted experiment errors; in about half the cases it lies within the error limits, with no systematic dependence on atomic number.

Das, B. P.; Hata, J.; Grant, I. P.

1984-01-01

252

Starting with the indirect exchange model influenced by the Rashba and the Dresselhaus spin-orbit interactions, we derive the Dzyaloshinskii-Moriya interaction of localized spins. The strength of the Dzyaloshinskii-Moriya interaction is compared with that of the Heisenberg exchange term as a function of atomic distance. Using the calculated interaction strengths, we discuss the formation of various atomic ground states as a function of temperature and external magnetic field. By plotting the magnetic field-temperature phase diagram, we present approximate phase boundaries between the spiral, Skyrmion and ferromagnetic states of the two-dimensional weak ferromagnetic system. PMID:24762988

Oh, J H; Lee, K-J; Lee, Hyun-Woo; Shin, M

2014-05-14

253

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

254

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

The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He((3)S1) and Ne((3)P2), and of ground state N((4)S3/2) and O((3)P2) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C((3)P2; (1)D2) and N((2)D5/2; (2)P3/2) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)]. PMID:25770544

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

2015-03-14

255

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

NASA Astrophysics Data System (ADS)

The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He(3S1) and Ne(3P2), and of ground state N(4S3/2) and O(3P2) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C(3P2; 1D2) and N(2D5/2; 2P3/2) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)].

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

2015-03-01

256

Ground-state Stabilization of Open Quantum Systems by Dissipation

Control by dissipation, or environment engineering, constitutes an important methodology within quantum coherent control which was proposed to improve the robustness and scalability of quantum control systems. The system-environment coupling, often considered to be detrimental to quantum coherence, also provides the means to steer the system to desired states. This paper aims to develop the theory for engineering of the dissipation, based on a ground-state Lyapunov stability analysis of open quantum systems via a Heisenberg-picture approach. Algebraic conditions concerning the ground-state stability and scalability of quantum systems are obtained. In particular, Lyapunov stability conditions expressed as operator inequalities allow a purely algebraic treatment of the environment engineering problem, which facilitates the integration of quantum components into a large-scale quantum system and draws an explicit connection to the classical theory of vector Lyapunov functions and decomposition-aggregation methods for control of complex systems. The implications of the results in relation to dissipative quantum computing and state engineering are also discussed in this paper.

Yu Pan; Valery Ugrinovskii; Matthew R. James

2015-02-19

257

NASA Technical Reports Server (NTRS)

The effects of atomic oxygen on boron nitride (BN) and silicon nitride (Si3N4) were evaluated in a low Earth orbit (LEO) flight experiment and in a ground based simulation facility. In both the inflight and ground based experiments, these materials were coated on thin (approx. 250A) silver films, and the electrical resistance of the silver was measured in situ to detect any penetration of atomic oxygen through the BN and Si3N4 materials. 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, as indicated by an increase in the electrical resistance of the silver underneath, was observed in both the inflight and ground based experiments. In contrast, no permeation of atomic oxygen through Si3N4 was observed in either the inflight or ground based experiments. The ground based results show good qualitative correlation with the LEO flight results, indicating that ground based facilities such as the one at Los Alamos National Lab can reproduce space flight data from LEO.

Cross, J. B.; Lan, E. H.; Smith, C. A.; Whatley, W. J.

1990-01-01

258

The dissociation curve for the ground state of TlH was computed using a relativistic {omega}-{omega} coupling formalism. The relativistic effects represented by the Dirac equation were introduced using effective potentials generated from atomic Dirac-Fock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. The multiconfiguration SCF treatment used is a generalization of the two-component molecular spinor formalism of Lee, Ermler, and Pitzer. Using a five configuration wave function we were able to obtain approximately 85% of the experimental dissociation energy. Our computations indicate that the bond is principally sigma in form, despite the large spin-orbit splitting in atomic thallium. Furthermore the bond appears to be slightly ionic (Tl{sup +}H{sup -}) with about 0.3 extra electron charge on the hydrogen.

Christiansen, P.A.; Pitzer, K.S.

1980-07-01

259

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

260

Absence of Energy Level Crossing for the Ground State Energy of the Rabi Model

The Hamiltonian of the Rabi model is considered. It is shown that the ground state energy of the Rabi Hamiltonian is simple for all values of the coupling strength, which implies the ground state energy does not cross other energy

Masao Hirokawa; Fumio Hiroshima

2012-07-17

261

An atom diode, i.e., a device that lets the ground state atom pass in one direction but not in the opposite direction in a velocity range is devised. It is based on the adiabatic transfer achieved with two lasers and a third laser potential that reflects the ground state.

A. Ruschhaupt; J. G. Muga

2004-08-20

262

Calculation of electron scattering from the ground state of ytterbium

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

Bostock, Christopher J.; Fursa, Dmitry V.; Bray, Igor [ARC Centre for Antimatter-Matter Studies, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

2011-05-15

263

Basicity of coumarin derivatives in the ground and excited states

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

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

1985-07-01

264

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

265

The rotating wave approximation is used to obtain parametric expressions for the resonance cross section for the atomic ground state ionisation by linearly polarised probe radiation in the vicinity of an autoionisation state coupled resonantly to another autoionisation state through circularly polarised laser radiation. Calculations are made for the 2s2p {sup 1}P and 2s3d {sup 1}D states of the helium atom. It is shown that the structure of the photoionisation cross-section spectrum formed for circularly polarised laser radiation differs qualitatively from the structure formed in the case of linear polarisation. The dependence of this structure on the intensity and frequency of laser radiation and the direction of polarisation of the probe radiation is studied. (interaction of laser radiation with matter. laser plasma)

Gryzlova, E V [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Magunov, A I [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Rotter, I [Max-Planck-Institut fur Physik komplexer Systeme (Germany); Strakhova, S I [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2005-01-31

266

Ground-state electric quadrupole moment of Al31

NASA Astrophysics Data System (ADS)

The ground-state electric quadrupole moment of Al31(I?=5/2+,T1/2=644(25)ms) has been measured by means of ?-ray-detected nuclear magnetic resonance spectroscopy using a spin-polarized Al31 beam produced in the projectile fragmentation reaction. The obtained Q moment, |Qexp(Al31)|=112(32)emb, is in agreement with conventional shell model calculations within the sd valence space. Previous results on the magnetic moment also support the validity of the sd model in this isotope, and thus it is concluded that Al31 is located outside of the island of inversion.

Nagae, D.; Ueno, H.; Kameda, D.; Takemura, M.; Asahi, K.; Takase, K.; Yoshimi, A.; Sugimoto, T.; Shimada, K.; Nagatomo, T.; Uchida, M.; Arai, T.; Inoue, T.; Kagami, S.; Hatakeyama, N.; Kawamura, H.; Narita, K.; Murata, J.

2009-02-01

267

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

268

Inequalities between ground-state energies of Heisenberg models

The Lieb-Schupp inequality is the inequality between ground state en- ergies 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.

Jacek Wojtkiewicz; Rafa? Skolasi?ski

2014-10-20

269

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

270

Ground state of the one dimensional Gross-Pitaevskii equation with a Morse potential

We have studied the ground state of the Gross-Pitaevskii equation (nonlinear Schrodinger equation) for a Morse potential via a variational approach. It is seen that the ground state ceases to be bound when the coupling constant of the nonlinear term reaches a critical value. The disappearence of the ground state resembles a saddle node bifurcation.

Sukla Pal; Jayanta K. Bhattacharjee

2013-09-21

271

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.

272

Quantum Light Storage in Solid State Atomic Ensembles

In this chapter, we will describe the storage and retrieval of quantum light (heralded single photons and entangled photons) in atomic ensembles in a solid state environment. We will consider ensembles of rare-earth ions embedded in dielectric crystals. We will describe the methods used to create quantum light spectrally compatible with the narrow atomic transitions, as well as possible protocols based on dipole rephasing that can be used to reversibly map the quantum light onto collective atomic excitations. We will review the experimental state of the art and describe in more detail quantum light storage experiments in neodymium and praseodymium doped crystals.

Hugues de Riedmatten; Mikael Afzelius

2015-02-01

273

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

274

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

275

Microwave-dressed state-selective potentials for atom interferometry

We propose a novel and robust technique to realize a beam splitter for trapped Bose-Einstein condensates (BECs). The scheme relies on the possibility of producing different potentials simultaneously for two internal atomic states. The atoms are coherently transferred, via a Rabi coupling between the two long-lived internal states, from a single well potential to a double-well. We present numerical simulations supporting our proposal and confirming excellent efficiency and fidelity of the transfer process with realistic numbers for a BEC of $^{87}$Rb. We discuss the experimental implementation by suggesting state-selective microwave potentials as an ideal tool to be exploited for magnetically trapped atoms. The working principles of this technique are tested on our atom chip device which features an integrated coplanar micro-wave guide. In particular, the first realization of a double-well potential by using a microwave dressing field is reported. Experimental results are presented together with numerical simu...

Guarrera, V; Reichel, J; Rosenbusch, P

2015-01-01

276

NASA Technical Reports Server (NTRS)

The objective of this research was to calibrate the ground-to-space effective atomic oxygen fluence for DC 93-500 silicone in a thermal energy electron cyclotron resonance (ECR) oxygen plasma facility. Silicones, commonly used spacecraft materials, do not chemically erode with atomic oxygen attack like other organic materials but form an oxidized hardened silicate surface layer. Therefore, the effective atomic oxygen fluence in a ground test facility should not be determined based on mass loss measurements, as they are with organic polymers. A technique has been developed at the Glenn Research Center to determine the equivalent amount of atomic oxygen exposure in an ECR ground test facility to produce the same degree of atomic oxygen damage as in space. The approach used was to compare changes in the surface hardness of ground test (ECR) exposed DC 93-500 silicone with DC 93-500 exposed to low Earth orbit (LEO) atomic oxygen as part of a shuttle flight experiment. The ground to in-space effective atomic oxygen fluence correlation was determined based on the fluence in the ECR source that produced the same hardness for the fluence in-space. Nanomechanical hardness versus contact depth measurements were obtained for five ECR exposed DC 93-500 samples (ECR exposed for 18 to 40 hrs, corresponding to Kapton effective fluences of 4.2 x 10(exp 20) to 9.4 x 10(exp 20) atoms/sq cm, respectively) and for space exposed DC 93-500 from the Evaluation of Oxygen Interactions with Materials III (EOIM III) shuttle flight experiment, exposed to LEO atomic oxygen for 2.3 x 10(exp 20) atoms/sq cm. Pristine controls were also evaluated. A ground-to-space correlation value was determined based on correlation values for four contact depths (150, 200, 250, and 300 nm), which represent the near surface depth data. The results indicate that the Kapton effective atomic oxygen fluence in the ECR facility needs to be 2.64 times higher than in LEO to replicate equivalent exposure damage in the ground test silicone as occurred in the space exposed silicone.

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

2004-01-01

277

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

278

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 -> F'=3 transition of the D2 line to produce Zeeman pumping toward m=0. To avoid trap states, we implement the first laser in a 2D 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 -> F'=4 and F=4 -> F'=5 transitions of the D2 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 new mechanism improving both laser cooling and state preparation efficiency. A physical interpretation of this mechanism is discussed.

Gianni Di Domenico; Laurent Devenoges; Claire Dumas; Pierre Thomann

2010-11-07

279

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

280

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

281

A solid state low pulse power ground surveillance radar

NASA Astrophysics Data System (ADS)

The use of high-duty-ratio transmissions improves the efficiency and economy of solid state transmitter power amplifiers, while simultaneously reducing the detectability of a radar by conventional electronic surveillance receivers. A composite waveform, consisting of two orthogonally coded pulses radiated within the same pulse repetition interval, offers a combination of high transmission duty ratio and a pulse repetition rate low enough to avoid range ambiguity. Used with solid-state-transmitters, low-sidelobe antennas, and modern signal-processing techniques, this waveform provides the basis for a class of short-to-medium-range radars that combine good clutter discrimination with high survivability in a radar countermeasures environment. Following a short discussion of radar detectability and a description of the orthogonally coded pulse waveform, this paper outlines the design features of a practical ground surveillance radar that is being developed to evaluate these concepts.

McKillop, A.

282

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

2015-02-22

283

Approximating ground and excited state energies on a quantum computer

NASA Astrophysics Data System (ADS)

Approximating ground and a fixed number of excited state energies, or equivalently low-order Hamiltonian eigenvalues, is an important but computationally hard problem. Typically, the cost of classical deterministic algorithms grows exponentially with the number of degrees of freedom. Under general conditions, and using a perturbation approach, we provide a quantum algorithm that produces estimates of a constant number j of different low-order eigenvalues. The algorithm relies on a set of trial eigenvectors, whose construction depends on the particular Hamiltonian properties. We illustrate our results by considering a special case of the time-independent Schrödinger equation with d degrees of freedom. Our algorithm computes estimates of a constant number j of different low-order eigenvalues with error O(\\varepsilon ) and success probability at least 3/4 , with cost polynomial in 1/\\varepsilon and d . This extends our earlier results on algorithms for estimating the ground state energy. The technique we present is sufficiently general to apply to problems beyond the application studied in this paper.

Hadfield, Stuart; Papageorgiou, Anargyros

2015-01-01

284

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

285

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

286

The ground state rotational spectrum of SO 2F 2

NASA Astrophysics Data System (ADS)

The analysis of the ground state rotational spectrum of SO 2F 2 [K. Sarka, J. Demaison, L. Margulčs, I. Merke, N. Heineking, H. Bürger, H. Ruland, J. Mol. Spectrosc. 200 (2000) 55] has been performed with the Watson's Hamiltonian up to sextic terms but shows some limits due to the A and S reductions. Since SO 2F 2 is a quasi-spherical top, it can also be regarded as derived from an hypothetical XY 4 molecule. Thus we have developed a new tensorial formalism in the O(3)? Td? C2 v group chain (M. Rotger, V. Boudon, M. Loëte, J. Mol. Spectrosc. 216 (2002) 297]. We test it on the ground state of this molecule using the same experimental data (10 GHz-1 THz region, J up to 99). Both fits are comparable even if the formalisms are slightly different. This paper intends to establish a link between the classical approach and the tensorial formalism. In particular, our tensorial parameters at a given order of the development are related to the usual ones. Programs for spectrum simulation and fit using these methods are named C2 vTDS. They are freely available at the URL: http://www.u-bourgogne.fr/LPUB/c2vTDS.html.

Rotger, M.; Boudon, V.; Loëte, M.; Margulčs, L.; Demaison, J.; Mäder, H.; Winnewisser, G.; Müller, H. S. P.

2003-12-01

287

Lifetimes of Rydberg states of Eu atoms

NASA Astrophysics Data System (ADS)

The radiative lifetimes of the Eu 4f76snp (8PJ or 10PJ) Rydberg states with J = 5/2 and 11/2 are investigated with a combination of multi-step laser excitation and pulsed electric field ionization, from which their dependence on the effective principal quantum number is observed. The lifetimes of 21 states are reported along with an evaluation of their experimental uncertainty. The influence of blackbody radiation, due to the oven temperature, on the lifetime of the higher-n states is detected. The non-hydrogen behavior of the investigated states is also observed. Project supported by the National Natural Science Foundation of China (Grant No. 11174218).

Jing, Hua; Ye, Shi-Wei; Dai, Chang-Jian

2015-01-01

288

Hyperfine Structure of the Ground State of 3He+ by the Ion-Storage Exchange-Collision Technique

The hfs of the ground state of 3He+ has been studied using the spin-dependent collision processes between stored 3He+ ions and a polarized beam of Cs atoms. All possible hfs transitions have been measured in a magnetic field of about 7.13 G. A consecutive-pulse multiple-resonance scheme was developed to detect the only weakly field-dependent transition (F=0, mF=0)(F=1, mF=0) in an

H. A. Schuessler; E. N. Fortson; H. G. Dehmelt

1969-01-01

289

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

290

The acetochlor registration partnership state ground water monitoring program.

The Acetochlor Registration Partnership (ARP) conducted a 7-yr ground water monitoring program at a total of 175 sites in seven states: Illinois, Indiana, Iowa, Kansas, Minnesota, Nebraska, and Wisconsin. While acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide] was the primary focus, the analytical methods also quantified alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide], atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide], and two classes of soil degradates for acetochlor, alachlor, and metolachlor. Ground water samples were collected monthly for five years and quarterly for two additional years. All samples were analyzed for the presence of parent herbicides, and degradates were monitored during the last three years. Parent acetochlor was detected above 0.1 microg L(-1) in three or more samples at just seven sites. Alachlor and metolachlor were also rarely detected, but atrazine was detected in 36% of all samples analyzed. Even more widespread were the tertiary amide sulfonic acid (ethanesulfonic acid, ESA) degradates of acetochlor, alachlor, and metolachlor, which were detected at 81, 76, and 106 sites, respectively. The other class of monitored soil degradates (oxanilic acid, OXA) was detected less frequently, at 26, 16, and 63 sites for acetochlor OXA, alachlor OXA, and metolachlor OXA, respectively. The geographic distribution of detections did not follow the pattern originally expected when the study began. Rather than being a function primarily of soil texture, the detection of these herbicides in shallow ground water was related to site-specific factors associated with local topography, the occurrence of surface water drainage features, irrigation practices, and the vertical positioning of the well screen. PMID:15843642

de Guzman, Noel P; Hendley, Paul; Gustafson, David I; van Wesenbeeck, Ian; Klein, Andrew J; Fuhrman, John D; Travis, Kim; Simmons, Nick D; Teskey, Wendy E; Durham, Roger B

2005-01-01

291

MODFLOW-2005 Ground-Water Model User Guide to the Adjoint State Based Sensitivity

MODFLOW-2005 Ground-Water Model User Guide to the Adjoint State Based Sensitivity Process (ADJ-2005 modular ground-water model that uses the adjoint state method to calculate the sensitivity of the input files needed to define the ground-water flow simulation. The reader should refer to the MODFLOW

Barrash, Warren

292

NASA Astrophysics Data System (ADS)

By measurements of phosphorescence and transient absorption spectra as well as steady-state photolysis of the title compound (NNV), it is concluded as follows: (1) In benzene and ethanol, intersystem crossing from the lowest excited singlet ( 1NNV ?) to triplet ( 3NNV ?) states competes withvalence isomerization of 1NNV ? yielding ground-state naphthoylnaphthalene (NN). (2) In ethanol, the NNV ketyl radical (generated by hydrogen-atom abstraction of 3NNV ? from the solvent molecule) also undergoes rapid valence isomerization and recombination of two NN ketyl radicals thus formed yields 1,1,2,2-tetranaphthyl-1,2-ethanediol (naphthopinacol).

Nakayama, Toshihiro; Nagahara, Tetsuhiko; Miki, Sadao; Hamanoue, Kumao

1997-03-01

293

Stokes parameters for the electron-impact excitation of the 4P11 state of zinc atom

NASA Astrophysics Data System (ADS)

Theoretical results of differential Stokes parameters and electron impact coherence parameters for the excitation of 4P11 state of zinc atoms at the incident electron energy of 80 eV are reported in the light of the recent measurement (Piwi?ski et al. (2013) [8]). The results have been obtained from the calculated fully relativistic distorted wave T-matrix for the electron impact excitation of the 4P11 state in the zinc atom from the ground 4S01 state. The comparison of our results with the experimental data show excellent agreement.

Das, Tapasi; Dipti; Srivastava, Rajesh

2014-01-01

294

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

295

Vibrational dynamics. Experimental ground-state combination differences of CH??.

Protonation of methane (CH4), a rather rigid molecule well described by quantum mechanics, produces CH5(+), a prototypical floppy molecule that has eluded definitive spectroscopic description. Experimental measurement of high-resolution spectra of pure CH5(+) samples poses a formidable challenge. By applying two types of action spectroscopy predicated on photoinduced reaction with CO2 and photoinhibition of helium cluster growth, we obtained low-temperature, high-resolution spectra of mass-selected CH5(+). On the basis of the very high accuracy of the line positions, we determined a spectrum of combination differences. Analysis of this spectrum enabled derivation of equally accurate ground state-level schemes of the corresponding nuclear spin isomers of CH5(+), as well as tentative quantum number assignment of this enfant terrible of molecular spectroscopy. PMID:25792326

Asvany, Oskar; Yamada, Koichi M T; Brünken, Sandra; Potapov, Alexey; Schlemmer, Stephan

2015-03-20

296

On the DFT ground state of crystalline bromine and iodine.

We report on an erroneous ground state within common density functional theory (DFT) methods for the solid elements bromine and iodine. Phonon computations at the GGA level for both molecular crystals yield imaginary vibrational modes, erroneously indicating dynamic instability-that fact alone could easily pass as a computational artefact, but these imaginary modes lead to energetically more favorable and dynamically stable structures, made up of infinite monoatomic chains. In contrast, meta-GGA and hybrid functionals yield the correct energetic order for bromine, while for iodine, most global hybrids do not improve the GGA result significantly. The qualitatively correct answer, in both cases, is given by the long-range corrected hybrid LC-?PBE, the Minnesota functionals M06L and M06, and by periodic Hartree-Fock and MP2 theory. This poor performance of economic DFT functionals should be kept in mind, for example, during global structure optimizations of systems with significant contributions from halogen bonds. PMID:25639654

George, Janine; Reimann, Christoph; Deringer, Volker L; Bredow, Thomas; Dronskowski, Richard

2015-03-16

297

Ground state magnetic dipole moment of 35K

The ground state magnetic moment of 35K has been measured using the technique of nuclear magnetic resonance on beta-emitting nuclei. The short-lived 35K nuclei were produced following the reaction of a 36Ar primary beam of energy 150 MeV/nucleon incident on a Be target. The spin polarization of the 35K nuclei produced at 2 degrees relative to the normal primary beam axis was confirmed. Together with the mirror nucleus 35S, the measurement represents the heaviest T = 3/2 mirror pair for which the spin expectation value has been obtained. A linear behavior of gp vs. gn has been demonstrated for the T = 3/2 known mirror moments and the slope and intercept are consistent with the previous analysis of T = 1/2 mirror pairs.

T. J. Mertzimekis; P. F. Mantica; A. D. Davies; S. N. Liddick; B. E. Tomlin

2006-02-02

298

Quantum interference effects on ground-state optomechanical cooling

NASA Astrophysics Data System (ADS)

We propose a fast ground-state optomechanical cooling scheme through the use of a two-mode optical cavity with a quarter-wave plate inside. Two cavity modes are orthogonally polarized; one cavity mode dissipates to the external environment at a fast rate while the other dissipates at a slow rate. The quarter-wave plate provides linear mixing interaction between these two cavity modes. The cooling process is dominated by scattering process via the fast-decay channel, which is significantly enhanced as compared with that obtained in the resolved-sideband optomechanical cooling scheme. Meanwhile, the heating process is significantly suppressed by exploiting the destructive quantum interference between the two cavity modes with the help of the quarter-wave plate.

Gu, Wen-ju; Li, Gao-xiang

2013-02-01

299

Tuning the magnetic ground state of a triangular lattice system

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

Garlea, Vasile O [ORNL; Savici, Andrei T [ORNL; Jin, Rongying [Louisiana State University

2011-01-01

300

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

301

Neutral atoms are entangled in hyperfine states via Rydberg blockade

Ions and neutral atoms held in electromagnetic traps are two of many candidates that may one day become the qubits in a quantum computer: Their hyperfine states could serve as the computer's ones and zeroes. Ions interact via long-range Coulomb forces, which can facilitate creation of the entangled states that are the prerequisite for quantum computation. But that same Coulomb interaction gives rise to collective motions that can disrupt a qubit array. Atoms aren't susceptible to such disruptions. But they're also more difficult to entangle.

Miller, Johanna

2010-02-15

302

Ground state cooling, quantum state engineering and study of decoherence of ions in Paul traps

{ Norman Bridge Laboratory of Physics, Caltech, Pasadena, USA } Aarhus University, Denmark (Received 17 of vibration with up to 99:9% probability. Starting from this Fock state jn ^ 0i, we demonstrate coherent. Motional heating is measured to be as low as one vibrational quantum in 190 ms. We also report on ground

Blatt, Rainer

303

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

304

Ground State Destabilization from a Positioned General Base in the Ketosteroid Isomerase Active Site

Ground State Destabilization from a Positioned General Base in the Ketosteroid Isomerase Active, Stanford, California 94305, United States Â§ Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States *S Supporting Information ABSTRACT: We

Herschlag, Dan

305

Excited-state intramolecular proton transfer (ESIPT) between two highly electronegative atoms, for example, oxygen and nitrogen, has been intensely studied experimentally and computationally, whereas there has been much less theoretical work on ESIPT to other atoms such as carbon. We have employed CASSCF, MS-CASPT2, RI-ADC(2), OM2/MRCI, DFT, and TDDFT methods to study the mechanistic photochemistry of 2-phenylphenol, for which such an ESIPT has been observed experimentally. According to static electronic structure calculations, irradiation of 2-phenylphenol populates the bright S1 state, which has a rather flat potential in the Franck-Condon region (with a shallow enol minimum at the CASSCF level) and may undergo an essentially barrierless ESIPT to the more stable S1 keto species. There are two S1/S0 conical intersections that mediate relaxation to the ground state, one in the enol region and one in the keto region, with the latter one substantially lower in energy. After S1 ? S0 internal conversion, the transient keto species can return back to the S0 enol structure via reverse ground-state hydrogen transfer in a facile tautomerization. This mechanistic scenario is verified by OM2/MRCI-based fewest-switches surface-hopping simulations that provide detailed dynamic information. In these trajectories, ESIPT is complete within 118 fs; the corresponding S1 excited-state lifetime is computed to be 373 fs in vacuum. Most of the trajectories decay to the ground state via the S1/S0 conical intersection in the keto region (67%), and the remaining ones via the enol region (33%). The combination of static electronic structure computations and nonadiabatic dynamics simulations is expected to be generally useful for understanding the mechanistic photophysics and photochemistry of molecules with intramolecular hydrogen bonds. PMID:25711992

Xia, Shu-Hua; Xie, Bin-Bin; Fang, Qiu; Cui, Ganglong; Thiel, Walter

2015-04-01

306

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

307

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

308

Correction method for obtaining the variationally best ground-state pair density

We present a correction method for the pair density (PD) to get close to the ground-state one. The PD is corrected to be a variationally best PD within the search region that is extended by adding the uniformly scaled PDs to its elements. The corrected PD is kept N-representable and satisfies the virial relation rigorously. The validity of the present method is confirmed by numerical calculations of neon atom. It is shown that the root-mean-square error of the electron-electron interaction and external potential energies, which is a good benchmark for the error of the PD, is reduced by 69.7% without additional heavy calculations.

Higuchi, Masahiko; Higuchi, Katsuhiko [Department of Physics, Faculty of Science, Shinshu University, Matsumoto 390-8621 (Japan); Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan)

2011-10-15

309

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

310

Quantum Monte Carlo study of ground state properties of transition metal oxides

NASA Astrophysics Data System (ADS)

We apply a recently developed quantum Monte Carlo method ( S. Zhang and H. Krakauer, Phys. Rev. Lett. 90, 126401 (2003).) to study the transition metal oxides TiO and MnO. Starting from a trial wavefunction, this method uses much of the same machinery of density functional methods (single particle basis, non-local pseudopotentials) to project the system ground state by random walks in the space of Slater determinants, using auxiliary Hubbard-Stratonovich complex fields. The trial wave function, which is used to control the phase/sign problem, is a single Slater determinant generated using a density functional or Hartree-Fock type calculation. Our preliminary results as well as previous results show the robustness of this method for studying atoms, molecules, and solids. (Supported by ONR and NSF)

Al-Saidi, Wissam; Krakauer, Henry; Zhang, Shiwei

2004-03-01

311

Two-level lasers operating on the transitions to the ground state

NASA Astrophysics Data System (ADS)

We analyze in detail a model of two-level lasers with a thermal production of population inversion proposed by V. A. Gerasimov et al. (Phys. Rev. Lett., 2006, 96, 123902). We show that it is possible to obtain nine new laser lines on the transitions to the ground state in atoms of rare-earth metals (REMs) with an incomplete 4 f shell (Pr, Nd, Sm, Eu, and Tb-Tm). The laser line wavelengths are from the UV (Eu) to the middle IR (Tb and Er) regions of the spectrum. Based on the estimates of the specific laser energy parameters (power, power density, and efficiency), we conclude that only Sm, Eu, and Tm (among the REMs under study) are suited for the experimental prototypes of these lasers. The estimated maximum efficiency and specific power density of continuous lasing can reach the values of >40% and ~107÷109 W/cm2, respectively.

Gerasimov, V. A.; Gerasimov, V. V.

2011-08-01

312

Nonlinear ground-state pump-probe spectroscopy in an ultracold rubidium system

NASA Astrophysics Data System (ADS)

We present results of our experimental investigations of nonlinear ground-state pump-probe spectroscopy in ultracold 85Rb collected in a magneto-optical trap. These measurements represent an extension of a similar pump-probe spectroscopy in a two-level atomic system when strongly driven by a near-resonant pump beam. In the present three-level system, coherence-induced gain at the probe laser frequency can be observed at specific frequencies within the spectrum. The absorption or gain spectra that we observe resemble those of the two-level gain spectra, but different interference processes lead to features that are not present in the two-level case. We describe our measurements of this interaction in this work.

Mills, Arthur K.; Elliott, D. S.

2012-12-01

313

Combined Film Catalog, 1972, United States Atomic Energy Commission.

ERIC Educational Resources Information Center

A comprehensive listing of all current United States Atomic Energy Commission (USAEC) films, this catalog describes 232 films in two major film collections. Part One: Education-Information contains 17 subject categories and two series and describes 134 films with indicated understanding levels on each film for use by schools. The categories…

Atomic Energy Commission, Washington, DC.

314

Towards the creation of Fock states of atoms

NASA Astrophysics Data System (ADS)

Ultracold atoms have been successfully used to study numerous systems, previously unaccessible, but a precise control over the atom number of the sample still remains a challenge. This dissertation describes our progress towards achieving Fock states of atoms. The first three chapters cover the basic physics necessary to understand the techniques we use in our lab to manipulate atoms. We then summarize our experimental results from an earlier setup where we did two experiments. In the first experiment we compare the transport of cold atoms and a Bose Einstein Condensate (BEC) in a periodic potential. We find a critical potential height beyond which the condensate behavior deviates significantly from that of thermal atoms. In the second experiment we study the effect of periodic temporal kicks by a spatially periodic potential on a BEC in a quasi one dimensional trap. We observe a limit on the energy that the system can absorb from the kicks, which we conclude is due to the finite height of the trap rather than quantum effects. The majority of the dissertation discusses our experimental setup designed to produce Fock states. The setup is designed to use the method of laser culling to produce Fock states. We are able to create a BEC and transport it into a glass cell 25 cm away. We tried different innovative methods to reduce vibrations during transport before finally settling to a commercial air bearing translation stage. We create a high confinement one dimensional optical trap using the Hermite Gaussian TEM01 mode of a laser beam. Such a trap gives trapping frequencies comparable to an optical lattice and allows us to create a single one dimensional trap. We creating the TEM01 mode using an appropriate phase object (phase plate) in the path of a TEM00 mode beam. The method for producing the phase plate was very well controlled to obtain a good quality mode. Once the atoms are loaded into this one dimensional trap we can proceed to do laser culling to observe Sub-Poissonian number statistics and eventually create Fock states of few atoms. Finally, we describe a novel method to create a real time tunable optical lattice which would provide us with the ability of spatially resolved single atom detection.

Kelkar, Hrishikesh Vidyadhar

315

We study experimentally what is arguably the simplest yet non-trivial colloidal system: two-dimensional clusters of 6 spherical particles bound by depletion interactions. These clusters have multiple, degenerate ground states whose equilibrium distribution is determined by entropic factors, principally the symmetry. We observe the equilibrium rearrangements between ground states as well as all of the low-lying excited states. In contrast to the ground states, the excited states have soft modes and low symmetry, and their occupation probabilities depend on the size of the configuration space reached through internal degrees of freedom, as well as a single "sticky parameter" encapsulating the depth and curvature of the potential. Using a geometrical model that accounts for the entropy of the soft modes and the diffusion rates along them, we accurately reproduce the measured rearrangement rates. The success of this model, which requires no fitting parameters or measurements of the potential, shows that the free-energy landscape of colloidal systems and the dynamics it governs can be understood geometrically.

Rebecca W. Perry; Miranda C. Holmes-Cerfon; Michael P. Brenner; Vinothan N. Manoharan

2015-03-20

316

Ultracold scattering of Rb atoms and bound states of Rb2

NASA Astrophysics Data System (ADS)

The most accurate theoretical potentials available for the interaction of a pair of ground-state Rb atoms are used to evaluate their ultracold scattering properties. The close relation between the zero-energy scattering phase shifts and the number of bound states in the potential, by Levinson's theorem, is used to assign absolute values to the l = 0, 1 and 2 phase shifts. The number of bound states is compared with those resulting from detailed spectroscopic studies on the singlet potential and photoassociation results on the triplet potential. We review the scattering formulae needed to satisfy the Pauli principle for the fermion nuclei of 85Rb and 87Rb and their single unpaired electrons, for all possible initial hyperfine states. Scattering lengths are evaluated and their sensitivity to details of the asymptotic potentials is demonstrated.

Geltman, Sydney

2006-11-01

317

Making classical ground-state spin computing fault-tolerant.

We examine a model of classical deterministic computing in which the ground state of the classical system is a spatial history of the computation. This model is relevant to quantum dot cellular automata as well as to recent universal adiabatic quantum computing constructions. In its most primitive form, systems constructed in this model cannot compute in an error-free manner when working at nonzero temperature. However, by exploiting a mapping between the partition function for this model and probabilistic classical circuits we are able to show that it is possible to make this model effectively error-free. We achieve this by using techniques in fault-tolerant classical computing and the result is that the system can compute effectively error-free if the temperature is below a critical temperature. We further link this model to computational complexity and show that a certain problem concerning finite temperature classical spin systems is complete for the complexity class Merlin-Arthur. This provides an interesting connection between the physical behavior of certain many-body spin systems and computational complexity. PMID:21230024

Crosson, I J; Bacon, D; Brown, K R

2010-09-01

318

Thermal Ground State in Yang-Mills Thermodynamics

We derive an a useful priori estimate for the thermal ground state of deconfining phase of SU(2) Yang-Mills thermodynamics in four-dimensional, flat spacetime and discuss its implications. Upon a selfconsistent spatial coarse-graining over noninteracting, trivial-holonomy (BPS saturated)(anti)calorons of unit topological charge modulus an inert, adjoint scalar field |{phi}| and an effective pure-gauge configuration a{sub {mu}}{sup gs} emerge. The modulus |{phi}|>0 defines the maximal resolution in the coarse-grained theory and induces dynamical gauge-symmetry breaking. Thanks to perturbative renormalizability and the fact that |{phi}| can not absorb or emit energy-momentum the effective action is local and simple. The temperature dependence of the effective coupling is a consequence of thermodynamical consistency and describes the Coulomb screening of a static test charge due to short-lived monopole-antimonopole pairs. The latter occur unresolvably as small-holonomy excitations of (anti)calorons by the absorption of propagating fundamental gauge fields.

Hofmann, Ralf [ITP, Universitaet Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany)

2011-09-22

319

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

320

Making Classical Ground State Spin Computing Fault-Tolerant

We examine a model of classical deterministic computing in which the ground state of the classical system is a spatial history of the computation. This model is relevant to quantum dot cellular automata as well as to recent universal adiabatic quantum computing constructions. In its most primitive form, systems constructed in this model cannot compute in an error free manner when working at non-zero temperature. However, by exploiting a mapping between the partition function for this model and probabilistic classical circuits we are able to show that it is possible to make this model effectively error free. We achieve this by using techniques in fault-tolerant classical computing and the result is that the system can compute effectively error free if the temperature is below a critical temperature. We further link this model to computational complexity and show that a certain problem concerning finite temperature classical spin systems is complete for the complexity class Merlin-Arthur. This provides an interesting connection between the physical behavior of certain many-body spin systems and computational complexity.

Elizabeth Crosson; Dave Bacon; Kenneth R. Brown

2014-11-18

321

Making classical ground-state spin computing fault-tolerant

NASA Astrophysics Data System (ADS)

We examine a model of classical deterministic computing in which the ground state of the classical system is a spatial history of the computation. This model is relevant to quantum dot cellular automata as well as to recent universal adiabatic quantum computing constructions. In its most primitive form, systems constructed in this model cannot compute in an error-free manner when working at nonzero temperature. However, by exploiting a mapping between the partition function for this model and probabilistic classical circuits we are able to show that it is possible to make this model effectively error-free. We achieve this by using techniques in fault-tolerant classical computing and the result is that the system can compute effectively error-free if the temperature is below a critical temperature. We further link this model to computational complexity and show that a certain problem concerning finite temperature classical spin systems is complete for the complexity class Merlin-Arthur. This provides an interesting connection between the physical behavior of certain many-body spin systems and computational complexity.

Crosson, I. J.; Bacon, D.; Brown, K. R.

2010-09-01

322

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

323

Ground state properties of CeNi12B6

NASA Astrophysics Data System (ADS)

We report on the ground state features of the orthorhombic ternary compound CeNi12B6 which exhibits a large Ce-Ce interatomic distance of 6.07 Ĺ. Magnetic and electronic properties were studied by means of low temperature heat capacity and electrical resistivity measurements performed down to 0.4 K, high pressure resistivity studies and by magnetic susceptibility measurements. The low temperature heat capacity reveals a sharp second order type antiferromagnetic phase transition at TN = 1.85 K with an entropy gain of only 0.3R ln2 at TN. The initial temperature dependence of the heat capacity as well as resistivity data is well accounted for by a model for gapped antiferromagnetic magnons yielding an exceptionally large spin wave excitation gap ? ~ 2.2 TN. Single crystal magnetic susceptibility studies reveal a huge uni-axial single-ion crystal field anisotropy confining the moments along the orthorhombic c-axis. The application of quasi-hydrostatic pressure up to 1.4 GPa causes an increase of the Néel temperature to 2.3 K at 1.4 GPa.

Michor, H.; Markota, T.; Messner, I. M.; Özcan, S.; Schwarzböck, F.; Salamakha, L.; Tako, Z. S.; Bauer, E.; Sologub, O.

2015-03-01

324

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

325

A model potential energy function for the ground state of H2CO has been derived which covers the whole space of the six internal coordinates. This potential reproduces the experimental energy, geometry and quadratic force field of formaldehyde, and dissociates correctly to all possible atom, diatom and triatom fragments. Thus there are good reasons for believing it to be close to

S. Carter; I. M. Mills; J. N. Murrell

1980-01-01

326

On the quantum criticality in the ground and the thermal states of XX model

We compare the critical behavior of the ground state and the thermal state of the XX model. We analyze the full energy spectrum and the eigenstates to reconstruct the ground state and the thermally excited state. With the solutions, we discuss about several physical properties of the states, which are related to quantum phase transition, in various limits, at zero temperature as well as at a thermal equilibrium.

Wonmin Son; Vlatko Vedral

2009-05-19

327

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.

328

Generation of hyperentangled states between remote noninteracting atomic ions

We propose a scheme of generating four-qubit hyperentangled states between a pair of remote noninteracting atomic ions with a {Lambda} configuration that are confined in Paul traps. These hyperentangled states, different from the normal entangled states that are entangled in a single degree of freedom, are entangled in both spin and motion degrees of freedom. In our proposal, the entanglement is first generated in spin degrees of freedom using linear optics and then transferred to the motion degree of freedom using a sequence of laser pluses, including the stimulated Raman carrier transitions and sideband transitions. The proposal is completed with regenerating entanglement in spin degrees of freedom using linear optics.

Hu Baolin [School of Physics and Electronic Electrical Engineering, Huaiyin Normal University, Huaian 223001 (China); Zhan Youbang [School of Physics and Electronic Electrical Engineering, Huaiyin Normal University, Huaian 223001 (China); CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China)

2010-11-15

329

Transition Properties of Low Lying States in Atomic Indium

We present here the results of our relativistic many-body calculations of various properties of the first six low-lying excited states of indium. The calculations were performed using the relativistic coupled-cluster method in the framework of the singles, doubles and partial triples approximation. We obtain a large lifetime ~10s for the [4p^6]5s^2 5p_{3/2} state, which had not been known earlier. Our precise results could be used to shed light on the reliability of the lifetime measurements of the excited states of atomic indium that we have considered in the present work.

Sahoo, B K

2011-01-01

330

Pair supersolid with atom-pair hopping on the state-dependent triangular lattice

NASA Astrophysics Data System (ADS)

We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of large-scale quantum Monte Carlo simulations, the ground-state phase diagram is studied. We find a first-order transition between the atomic superfluid phase and the pair superfluid phase when the ratio of the atomic hopping and the atom-pair hopping is adapted. The first-order transition remains unchanged under various conditions. We then focus on the interplay among the atom-pair hopping, the on-site repulsion, and the nearest-neighbor repulsion. With on-site repulsion present, we observe first-order transitions between the Mott insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1, and 4/3 filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasihardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. Without on-site repulsion, the transitions between the pair supersolid and the atom superfluid or pair superfluid are first order, except for the particle-hole symmetric point. With weak on-site repulsion and atom hopping turning on, the transition between the pair supersolid and pair superfluid phase becomes continuous. The transition between solid and pair supersolid is three-dimensional XY university, with dynamical exponent z=1 and correlation exponent ?=0.67155. The thermal melting of pair supersolid belongs to the two-dimensional Ising university. We check both energetic and mechanical balance of pair supersolid phase. Lowering the three-body constraint, no pair supersolid is found due to the absence of degeneracy of pair solids in classical limits. We describe the experimental realization of pair tunneling on state dependent lattice.

Zhang, Wanzhou; Yin, Ruoxi; Wang, Yancheng

2013-11-01

331

NASA Astrophysics Data System (ADS)

We performed first-principles calculations of multiplet structures and the corresponding ground-state absorption and excited-state absorption spectra for ruby (Cr3+:?-Al2O3) and alexandrite (Cr3+:BeAl2O4) which included lattice relaxation. The lattice relaxation was estimated using the first-principles total energy and molecular-dynamics method of the CASTEP code. The multiplet structure and absorption spectra were calculated using the configuration-interaction method based on density-functional calculations. For both ruby and alexandrite, the theoretical absorption spectra, which were already in reasonable agreement with experimental spectra, were further improved by consideration of lattice relaxation. In the case of ruby, the peak positions and peak intensities were improved through the use of models with relaxations of 11 or more atoms. For alexandrite, the polarization dependence of the U band was significantly improved, even by a model with a relaxation of only seven atoms.

Watanabe, Shinta; Sasaki, Tomomi; Taniguchi, Rie; Ishii, Takugo; Ogasawara, Kazuyoshi

2009-02-01

332

The Ground State Energy and Density of Interacting Bosons in a Trap

. Reproduction of this work, in its entirety, by any means, is permitted for noncommercial purposes. #12 mass. A natural energy unit is given by the ground state energy ~! of the one particle Hamiltonian , with the ground state energy E QM = inf spec H. If v = 0, then \\Psi 0 (~x 1 ; : : : ; ~x N ) = Q N i=1 \\Phi 0 (~x

333

Ground state correlations and mean field using the exp(S) method

This document gives a detailed account of the terms used in the computation of the ground state mean field and the ground state correlations. While the general approach to this description is given in a separate paper (nucl-th/9802029) we give here the explicite expressions used.

Jochen H. Heisenberg; Bogdan Mihaila

1998-02-10

334

Theoretical Investigation of the Ground and Excited States of Coumarin 151 and Coumarin 120

Theoretical Investigation of the Ground and Excited States of Coumarin 151 and Coumarin 120 Robert of the ground and excited states of Coumarins 151 and 120. These and related coumarins are important effects on excitation energies, and (4) the properties of single Coumarin 151-water complexes. We test our

Burke, Kieron

335

Ground State of the Massless Nelson Model in a non-Fock Representation

Ground State of the Massless Nelson Model in a non-Fock Representation Itaru Sasaki Department Abstract We consider a model of a particle coupled to a massless scalar field (the massless Nelson model of Griesemer, Lieb and Loss. Key words: Nelson model; ground state. 1 Introduction The Nelson model

336

The problem of an electron immersed in a uniform magnetic field is viewed from the framework of the relativistic Dirac theory. Because of the simple mathematical structure of the ground state it is possible to evaluate the first-order transition rates to the ground state lambdan0 exactly. Explicit results for lambdan0 are given in analytical, tabular, and graphical form for a

D. White

1974-01-01

337

Ground-state energy and frustration of the Sherrington-Kirkpatrick model and related models

Ground-state energy and frustration of the Sherrington-Kirkpatrick model and related models S. Kobe dependence of the misfit parameter, which is a measure of frustration of the system. The results are compared. The main feature of the ground state is frustration. It is shown in [14], [15], [16] that for Ising spin

Kobe, Sigismund

338

NASA Astrophysics Data System (ADS)

We propose a scalable scheme for a unitary multimode operator using an optical cavity with an atomic ensemble. We exemplify three-mode and four-mode cases and engineer the squeeze operators that are decoupled from the atomic degrees of freedom. The squeeze parameters can be large since they are proportional to the number of atoms. Using the input-output theory we show that ideal squeezed states and perfect squeezing could be approached at the output. At the same time, we show that it is possible to obtain tripartite and quadripartite Greenberger-Horne-Zeilinger entangled states for continuous variables. The responsible mechanism for both the multimode squeezing and the genuine multipartite entanglement is based on the atomic coherence controlled parametric interactions. The scalability of the scheme is simply obtained by including more transitions in the atomic system.

Liang, Xiao; Hu, Xiangming; He, Chang

2012-03-01

339

An analytic theory of harmonic generation in the plasma produced from the gas of hydrogen-like atoms in excited states is considered for relatively intense radiation. The consideration of l-degeneracy of the electrons in these excited states allowed deriving the dependence of generation efficiency on the principal quantum number. In the context of the Bethe model of gas ionisation, we revealed the threshold nonlinear dependence of the maximum generation efficiency on the degree of circular polarisation of the pump field for its given intensity. Analytic calculations were performed for the fifth and seventh harmonics. The results of these calculations allowed generalising to the case of excited atoms the previously obtained results for the third harmonic in the plasma arising from hydrogen-like atoms in the ground state. (nonlinear optical phenomena)

Silin, Viktor P; Silin, Pavel V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2005-02-28

340

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...

341

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

NASA Astrophysics Data System (ADS)

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 2S(Cu) + 2S(Ag) and 2D(Cu) + 2S(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.

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-01

342

Steady-state superradiance with alkaline earth atoms

Earth-alkaline-like atoms with ultra-narrow transitions open the door to a new regime of cavity quantum electrodynamics. That regime is characterized by a critical photon number that is many orders of magnitude smaller than what can be achieved in conventional systems. We show that it is possible to achieve superradiance in steady state with such systems. We discuss the basic underlying mechanisms as well as the key experimental requirements

D. Meiser; M. J. Holland

2009-12-03

343

Steady-state superradiance with alkaline-earth-metal atoms

Alkaline-earth-metal-like atoms with ultranarrow transitions open the door to a new regime of cavity quantum electrodynamics. That regime is characterized by a critical photon number that is many orders of magnitude smaller than what can be achieved in conventional systems. We show that it is possible to achieve superradiance in steady state with such systems. We discuss the basic underlying mechanisms as well as the key experimental requirements.

Meiser, D.; Holland, M. J. [JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

2010-03-15

344

Electronic Structure of the Ground and Excited States of the CuA Site by NMR Spectroscopy

The electronic properties of Thermus thermophilus CuA in the oxidized form were studied by 1H and 13C NMR spectroscopy. All the 1H and 13C resonances from cysteine and imidazole ligands were observed and assigned in a sequence-specific fashion. The detection of net electron spin density on a peptide moiety is attributed to the presence of a H-bond to a coordinating sulfur atom. This hydrogen-bond is conserved in all natural CuA variants, and is important to maintain the electronic structure of the metal site, rendering the two Cys ligands nonequivalent. The anomalous temperature dependence of the chemical shifts is explained by the presence of a low-lying excited state located about 600 cm-1 above the ground state. The room temperature shifts can be described as the thermal average of a ?u* ground state and a ?u excited state. These results provide a detailed description of the electronic structure of the CuA site at atomic resolution in solution at physiologically relevant temperature. PMID:19146411

Abriata, Luciano A.; Ledesma, Gabriela N.; Pierattelli, Roberta; Vila, Alejandro J.

2009-01-01

345

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

346

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

Ground-state cooling and pure state preparation of a small object that is embedded in a thermal environment is an important challenge and a highly desirable quantum technology. This paper proves, with two different methods, that a fundamental constraint on the cooling dynamic implies that it is impossible to cool, via a unitary system-bath quantum evolution, a system that is embedded in a thermal environment down to its ground state, if the initial state is a factorized product of system and bath states. The latter is a crucial but artificial assumption included in numerous tools that treat system-bath dynamics, such as master equation approaches and Kraus operator based methods. Adopting these approaches to address ground state and even approximate ground state cooling dynamics should therefore be done with caution, considering the fundamental theorem exposed in this work. PMID:23661066

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

2013-01-01

347

Ultracold dense samples of dipolar RbCs molecules in the rovibrational and hyperfine ground state

We produce ultracold dense trapped samples of 87Rb133Cs molecules in their rovibrational ground state, with full nuclear hyperfine state control, by stimulated Raman adiabatic passage (STIRAP) with efficiencies of 90%. We observe the onset of hyperfine-changing collisions when the magnetic field is ramped so that the molecules are no longer in the hyperfine ground state. A strong quadratic shift of the transition frequencies as a function of applied electric field shows the strongly dipolar character of the RbCs ground-state molecule. Our results open up the prospect of realizing stable bosonic dipolar quantum gases with ultracold molecules.

Tetsu Takekoshi; Lukas Reichsöllner; Andreas Schindewolf; Jeremy M. Hutson; C. Ruth Le Sueur; Olivier Dulieu; Francesca Ferlaino; Rudolf Grimm; Hanns-Christoph Nägerl

2014-11-19

348

Metastable compound states of an antiproton and a hydrogen atom

NASA Astrophysics Data System (ADS)

The stability of antiproton-hydrogen compound states (pŻH) is investigated theoretically. The pŻH compound state has decay channels of atomic electron detachment (?e-+pŻp) and hadronic pair (pŻ-p) annihilation, and hence it cannot be permanently stable even if the dissociation channel (?pŻ+H) is energetically closed. In this paper, information on the metastable pŻH states at energies below the dissociation limit is obtained by analyzing low-energy resonances in e-+pŻp scattering. The scattering calculation is carried out by using an R-matrix method, which also allows for the annihilation channel simultaneously. The metastable states are found to be identified as vibrational levels supported by a Born-Oppenheimer (BO) potential. The energy-level widths attributed to the electron detachment and the annihilation are also calculated using a model based on the BO picture.

Sakimoto, Kazuhiro

2014-09-01

349

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

350

Breakdown of the Bardeen-Cooper-Schrieffer ground state at a quantum phase transtion.

Advances in solid-state and atomic physics are exposing the hidden relationships between conventional and exotic states of quantum matter. Prominent examples include the discovery of exotic superconductivity proximate to conventional spin and charge order, and the crossover from long-range phase order to preformed pairs achieved in gases of cold fermions and inferred for copper oxide superconductors. The unifying theme is that incompatible ground states can be connected by quantum phase transitions. Quantum fluctuations about the transition are manifestations of the competition between qualitatively distinct organizing principles, such as a long-wavelength density wave and a short-coherence-length condensate. They may even give rise to 'protected' phases, like fluctuation-mediated superconductivity that survives only in the vicinity of an antiferromagnetic quantum critical point. However, few model systems that demonstrate continuous quantum phase transitions have been identified, and the complex nature of many systems of interest hinders efforts to more fully understand correlations and fluctuations near a zero-temperature instability. Here we report the suppression of magnetism by hydrostatic pressure in elemental chromium, a simple cubic metal that demonstrates a subtle form of itinerant antiferromagnetism formally equivalent to the Bardeen-Cooper-Schrieffer (BCS) state in conventional superconductors. By directly measuring the associated charge order in a diamond anvil cell at low temperatures, we find a phase transition at pressures of 10 GPa driven by fluctuations that destroy the BCS-like state but preserve the strong magnetic interaction between itinerant electrons and holes. Chromium is unique among stoichiometric magnetic metals studied so far in that the quantum phase transition is continuous, allowing experimental access to the quantum singularity and a direct probe of the competition between conventional and exotic order in a theoretically tractable material.

Jaramillo, R.; Feng, Y.; Lang, J. C.; Islam, Z.; Srajer, G.; Littlewood, P. B.; Mc Whan, D. B.; Rosenbaum, T. F.; Univ. of Chicago; Univ. of Cambridge; Massachusetts Innst. of Tech.

2009-05-21

351

Dynamics of ground-state reverse proton transfer in the 7-azaindole\\/carboxylic acid systems

Dual-level direct dynamics calculation of the ground-state proton transfer reaction is reported for the 7-azaindole(7AI)\\/carboxylic acid system. The reaction path was calculated and the two-dimensional potential energy surface scan was performed at various levels of theory. Only one transition state geometry was resolved in the ground state from the ab initio calculation. The zero-point corrected barrier for the reverse proton

Wei-Ping Hu; Ru-Min You; Shih-Yao Yen; Fa-Tsai Hung; Po-Hung Chou; Pi-Tai Chou

2003-01-01

352

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

353

Evidence for Ground- and Excited-State Efimov Trimers in a Three-State Fermi Gas

We observe enhanced three-body recombination in an ultracold three-component $^6$Li Fermi gas with large but unequal scattering lengths attributable to an excited Efimov trimer state near the three-atom scattering threshold. We find excellent agreement between the measured three-body recombination rate and the recombination rate calculated in the zero-range approximation where the only free parameters are the Efimov parameters $\\kappa_*$ and $\\eta_*$. The value of $\\kappa_*$ determined by the location of the Efimov resonance we observe at 895 G also predicts the locations of loss features previously observed near 130 and 500 G \\cite{Jochim08,OHara09} suggesting that all three features are associated with universal Efimov trimer states. We also report on the first realization of a quantum degenerate three-state Fermi gas with approximate SU(3) symmetry.

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

2009-08-06

354

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

NASA Astrophysics Data System (ADS)

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

Szczepanik, Beata; Styrcz, Stanis?aw

2011-08-01

355

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

356

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

Bes, D. R. [Department of Physics, Tandar Labratory, Centro Atomico Constituyentes-Comision Nacional de Energia Atomica Avda Gral Paz 1499, 1650 Gral San Martin, Argentina and (Argentina); Civitarese, O. [Department of Physics, University of La Plata, Casilla de Correo 67 1900, La Plata (Argentina)

2010-01-15

357

Ground state and infrared response of triple concentric quantum ring structures

NASA Astrophysics Data System (ADS)

Within local-spin density-functional theory, we study the ground state and infrared response of two-dimensional, triple concentric quantum ring nanostructures. Changes in their physical properties are presented as a function of the number of electrons or the intensity of a perpendicularly applied magnetic field. We discuss the addition spectrum of few-electron triple quantum rings at zero magnetic field, as well as the physical appearance of the ground state and dipole response of selected systems containing up to 50 electrons. We also investigate the ground state, persistent currents, and charge- and spin-density responses of a system made of 30 electrons.

Escartín, José María; Barranco, Manuel; Pi, Martí

2010-11-01

358

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

359

NASA Technical Reports Server (NTRS)

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

Danilowicz, R.

1973-01-01

360

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

361

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

362

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.

Yong Wan; Florian Gebert; Fabian Wolf; Piet O. Schmidt

2015-01-28

363

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

364

A theoretical approach to simulation of the transient spectra in molecular systems with ultrafast photoinduced nonradiative electronic transitions is developed. The evolution of the excited and ground state populations as well as the nonradiative transitions between them are calculated in the framework of the stochastic multichannel point-transition model involving the reorganization of the medium and the intramolecular high frequency vibrational modes. Simulations of transient spectra of donor-acceptor pairs excited in the charge-transfer band that are accompanied by ultrafast charge recombination into the ground state demonstrate a possibility of positive band appearance in the transient absorption spectrum caused by those systems in the ground state, which returned there from the excited state. The region of the parameters of the donor-acceptor systems where a positive ground state absorption signal can be observed is discussed. A qualitative comparison of the simulated transient spectra with the experimental data on betaine-30 is presented. PMID:25686470

Fedunov, Roman G; Plotnikova, Anastasiia V; Ionkin, Vladimir N; Ivanov, Anatoly I

2015-03-12

365

The United States Geological Survey in cooperation with the Massachusetts Department of Public Works in 1938 began an investigation of the ground-water conditions in Massachusetts. This work is part of a larger cooperative program that includes surface-water investigations, geologic studies, and topographic mapping. The purpose of the ground-water studies is to obtain detailed information concerning the occurrence and availability of ground water throughout the State. The information is used by the Highway Division of the Department of Public Works in connection with design, construction, and maintenance of highways. These studies also provided a basis for the more effective utilization of the ground-water resources of the State. They indicate where additional developments can be made safely or where present use may be excessive. Reports covering the ground-water studies are listed in the appendix.

Brashears, M.L., Jr.

1950-01-01

366

In an effort to find a p-benzyne (1,4-didehydrobenzene) derivative with a triplet ground state, we have investigated tetrasubstitution by -F, -NH(2), -CH(3), and -NO(2) groups. These were predicted to reduce the singlet-triplet gap, but none led to a triplet ground state because of unexpected destabilization of one of the radical orbitals. This effect is likely the result of rehybridization of the substituted C atom, which has been observed for substituted benzene and perturbs the side sigma and sigma* orbital energies of the phenyl ring. The role of substituent rotation on the energy difference between the two nominally singly occupied orbitals (S and A) was then investigated. The energy of the A radical orbital was found to be much more sensitive to perturbations within the sigma C[bond]C framework than the S MO. Consequently, we believe that rehybridization of the ring carbons destabilizes the A radical orbital and can lead to large singlet-triplet splittings. To test this hypothesis, calculations on a p-benzyne with 2,6 substitution by oxygen were performed. Interestingly, a triplet ground state was predicted. Yet, examination of the geometry and wave function showed that 2,6-quinone p-benzyne is a very twisted molecule with a C3-C4-C5 allene linkage and a C1 triplet carbene center. PMID:12713336

Clark, Aurora E; Davidson, Ernest R

2003-05-01

367

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

368

Ground State of the Massless Nelson Model Without Infrared Cutoff in a NonFock Representation

Ground State of the Massless Nelson Model Without Infrared Cutoff in a NonFock Representation Asao the massless Nelson model, in a nonFock representation of the time zero fields which satisfy the canonical if no infrared cutoff is made. Key words: Nelson's model, massless quantum field, infrared divergence, ground

369

USGS Professional Paper 1703--Ground-Water Recharge in the Arid and Semiarid Southwestern United States-- Appendix--1 Thermal Methods for Investigating Ground-Water Recharge By Kyle W. Blasch, Jim is defined as the downward flux of water across the regional water table. The introduction of recharging

370

Ground-Water Recharge in the Arid and Semiarid Southwestern United States --

Ground-Water Recharge in the Arid and Semiarid Southwestern United States -- Climatic and Geologic Framework By David A. Stonestrom and James R. Harrill Abstract Ground-water recharge in the arid focused in time and space. Widespread water-table declines accompanied agricultural development during

371

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

372

Optical pumping of metastable NH radicals into the paramagnetic ground state

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

Meerakker, Sebastiaan Y.T. van de; Mosk, Allard P.; Jongma, Rienk T. [FOM-Institute for Plasmaphysics Rijnhuizen, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Sartakov, Boris G. [General Physics Institute RAS, Vavilov street 38, 119991 Moscow (Russian Federation); Meijer, Gerard [FOM-Institute for Plasmaphysics Rijnhuizen, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Department of Molecular and Laser Physics, University of Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen (Netherlands); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

2003-09-01

373

Antihydrogen Relaxation from High-n to Ground State.

NASA Astrophysics Data System (ADS)

We explore the rate at which magnetized, high-n Rydberg pairs formed in antihydrogen experiments relax to deep binding. While the theoretical three-body recombination rate scales favorably with low temperature (?TBRnb^3 (n v b^2 ) T-9/2), pairs form with binding energies ? near the (low) thermal level. Such atoms have classical drift orbits with negligible radiation. Collisions propel a cascade to deeper binding, but theory and simulation show an atom is unlikely to reach a radiating regime before it escapes the trap. However, simulations show that the energy-loss rate does not decrease as rapidly with increasing ? as previously expected. We also discuss the mean magnetic moment of guiding-center atoms, and energy loss from adiation at deep binding, based on the classical Larmour formula and a presumption of stochastic orbits. G. Gabrielse, N.S. Bowden, P. Oxley, et al., Phys. Rev. Lett. 89, 213401 (2002) M. Amoretti, C. Amsler, G. Bonomi, et al., Nature (London) 419, 456 (2002). ME. Glinsky and T.M. O'Neil, Phys. Fluids B 3, 1279 (1991). R. Robicheaux and J.D. Hanson, Phys. Rev. A 69, 010701 (2004). E.M. Bass and D.H.E. Dubin, Phys. Plasmas 11, 1240 (2004).

Bass, E. M.; Dubin, D. H. E.

2006-10-01

374

Precision study of ground state capture in the 14N(p,gamma)15O reaction

The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,gamma)15O, which proceeds by capture to the ground and several excited states in 15O. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S-factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S-factor.

Marta, M; Gyurky, Gy; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Elekes, Z; Fülöp, Z; Gervino, G; Guglielmetti, A; Gustavino, C; Imbriani, G; Junker, M; Kunz, R; Lemut, A; Limata, B; Mazzocchi, C; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Romano, M; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P; Vomiero, A

2008-01-01

375

Precision study of ground state capture in the 14N(p,gamma)15O reaction

The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,gamma)15O, which proceeds by capture to the ground and several excited states in 15O. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S-factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S-factor.

M. Marta; A. Formicola; Gy. Gyurky; D. Bemmerer; C. Broggini; A. Caciolli; P. Corvisiero; H. Costantini; Z. Elekes; Zs. Fulop; G. Gervino; A. Guglielmetti; C. Gustavino; G. Imbriani; M. Junker; R. Kunz; A. Lemut; B. Limata; C. Mazzocchi; R. Menegazzo; P. Prati; V. Roca; C. Rolfs; M. Romano; C. Rossi Alvarez; E. Somorjai; O. Straniero; F. Strieder; F. Terrasi; H. P. Trautvetter; A. Vomiero

2008-07-30

376

Frustration, interaction strength and ground-state entanglement in complex quantum systems

Entanglement in the ground state of a many-body quantum system may arise when the local terms in the system Hamiltonian fail to commute with the interaction terms in the Hamiltonian. We quantify this phenomenon, demonstrating an analogy between ground-state entanglement and the phenomenon of frustration in spin systems. In particular, we prove that the amount of ground-state entanglement is bounded above by a measure of the extent to which interactions frustrate the local terms in the Hamiltonian. As a corollary, we show that the amount of ground-state entanglement is bounded above by a ratio between parameters characterizing the strength of interactions in the system, and the local energy scale. Finally, we prove a qualitatively similar result for other energy eigenstates of the system.

Christopher M. Dawson; Michael A. Nielsen

2004-01-28

377

Evolution of dark state of an open atomic system in constant intensity laser field

We studied experimentally and theoretically the evolution of open atomic systems in the constant intensity laser field. The study is performed by analyzing the line shapes of Hanle electromagnetically induced transparency (EIT) obtained in different segments of a laser beam cross section of constant intensity, i.e., a {Pi}-shaped laser beam. Such Hanle EIT resonances were measured using a small movable aperture placed just in front of the photodetector, i.e., after the entire laser beam had passed through the vacuum Rb cell. The laser was locked to the open transition F{sub g}=2{yields}F{sub e}=1 at the D{sub 1} line of {sup 87}Rb with laser intensities between 0.5 and 4 mW/cm{sup 2}. This study shows that the profile of the laser beam determines the processes governing the development of atomic states during the interaction. The resonances obtained near the beam center are narrower than those obtained near the beam edge, but the significant changes of the linewidths occur only near the beam edge, i.e., right after the atom enters the beam. The Hanle EIT resonances obtained near the beam center exhibit two pronounced minima next to the central maximum. The theoretical model reveals that the occurrence of these transmission minima is a joint effect of the preparation of atoms into the dark state and the optical pumping into the uncoupled ground level F{sub g}=1. The appearance of the transmission minima, although similar to that observed in the wings of a Gaussian beam [A. J. Krmpot et al., Opt. Express 17, 22491 (2009)], is of an entirely different nature for the {Pi}-shaped laser beam.

Krmpot, A. J.; Radonjic, M.; Cuk, S. M.; Nikolic, S. N.; Grujic, Z. D.; Jelenkovic, B. M. [Institute of Physics, University of Belgrade, Pregrevica 118, RS-11080 Belgrade (Serbia)

2011-10-15

378

Two-Color Photoassociation Spectroscopy of the Triplet Ground State of Na2

NASA Astrophysics Data System (ADS)

We use a two-color cw photoassociation scheme to measure the position of vibrational levels of textNa2 with binding energies of 811 GHz with up to 30 MHz resolution. These levels are identified as belonging to the ``a'' sideset^3?_u^+ ground state: an improvement of three orders of magnitude over previous results. These vibrational levels are found by inducing an Autler-Townes splitting between an intermediate excited state and a particular ground state. For this purpose, we have identified a vibrational level in the sideset^3?_g^+ state (about 570 textcm-1 below the textS_1/2 + textP_1/2 limit) with a relatively large overlap with the ground states. By choosing states of different angular momentum characters within the excited vibrational level, we observed rotational and hyperfine features on the ground vibrational states. Totaling about 40 states identified this way. We also observed splitting of many of the ground-state lines. These splittings are compatible to what is expected from spin-spin dipolar interaction.

de Araujo, L.; Gensemer, S.; Weinstein, J.; Fatemi, F.; Jones, K.; Lett, P.; Tiesinga, E.

2002-05-01

379

Ground state cooling of quantum systems via a one-shot measurement

We prove that there exists a family of quantum systems that can be cooled to their ground states by a one-shot projective measurement on the ancillas coupled to these systems. Consequently, this proof gives rise to the conditions for achieving the one-shot measurement ground-state cooling (OSMGSC). We also propose a general procedure for finding unitary propagators and corresponding Hamiltonians to realize such cooling by means of inverse engineering technique.

P. V. Pyshkin; Da-Wei Luo; J. Q. You; Lian-Ao Wu

2015-03-13

380

Ground and electronically excited states of methyl hydroperoxide: Comparison with hydrogen peroxide

Equilibrium geometries of the ground states of hydrogen peroxide (H2O2) and methyl hydroperoxide (CH3OOH) have been obtained using quadratic configuration interaction methods with correlation-consistent basis sets. These results are compared with experiments and prior calculations. The dipole moments of the ground states of these two molecules have been calculated. The results illustrate the sensitivity of this quantity to molecular geometry.

John D. Watts; Joseph S. Francisco

2006-01-01

381

GGA and GGA+ U calculations of the ground state of SrMnO 3

A very recent experimental report suggests the ground state of SrMnO3 is orthorhombic with space group C2221. I perform spin-polarized generalized gradient approximation (GGA) calculations with\\/without on-site Coulomb interaction included (GGA+U) for this ground state of SrMnO3. In contrast to the latest theoretical report of cubic and hexagonal SrMnO3 where GGA method is considered to be able to reproduce the

Jian Ni

2010-01-01

382

Fermionized photons in the ground state of one-dimensional coupled cavities

NASA Astrophysics Data System (ADS)

The density matrix renormalization group algorithm is used to characterize the ground states of one-dimensional coupled cavities in the regime of low photon densities. Numerical results for photon and spin excitation densities, one- and two-body correlation functions, superfluid and condensate fractions, as well as the entanglement entropy and localizable entanglement are obtained for the Jaynes-Cummings-Hubbard (JCH) model and are compared with those for the Bose-Hubbard (BH) model where applicable. The results indicate that a Tonks-Girardeau phase, in which the photons are strongly fermionized, appears between the Mott-insulating and superfluid phases as a function of the intercavity coupling. In fact, the superfluid density is found to be zero in a wide region outside the Mott-insulator phase boundary. The presence of two different species of excitation (spin and photon) in the JCH model gives rise to properties with no analog in the BH model, such as the (quasi)condensation of spin excitations and the spontaneous generation of entanglement between the atoms confined to each cavity.

D'Souza, Adam G.; Sanders, Barry C.; Feder, David L.

2013-12-01

383

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

384

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

385

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

386

Detecting Positron-Atom Bound States through Resonant Annihilation V. A. Dzuba* and V. V. Flambaum

Detecting Positron-Atom Bound States through Resonant Annihilation V. A. Dzuba* and V. V. Flambaum) A method is proposed for detecting positron-atom bound states by observing enhanced positron annihilation of open-shell transition-metal atoms which are likely to bind the positron: Fe, Co, Ni, Tc, Ru, Rh, Sn, Sb

Gribakin, Gleb

387

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

388

We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for ? = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of ? = 1/2, which is highly mixed with (4)?(-) and (2)? states in ? - S notation. The two low-lying states 5/2 and 7/2 are nearly degenerate with the ground state and locate only 234 and 260 cm(-1) above, respectively. The equilibrium bond length 1.712 Ĺ and the harmonic vibrational frequency 903 cm(-1) of the 5/2 state are close to the experimental measurement of 1.724 Ĺ and 909 cm(-1), which suggests that the 5/2 state should be the low-lying state that contributes to the experimental spectra. Moreover, the electronic states that give rise to the observed transition bands are assigned for ? = 5/2 and 7/2 in terms of the obtained excited energies and oscillator strengths. PMID:25747077

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

2015-03-01

389

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

390

Atomic structure and electronic states of extended defects in silicon

NASA Astrophysics Data System (ADS)

Defects in silicon like dislocations, grain boundaries, silicide precipitates, etc. are spatially extended and associated with a large number of electronic states in the band gap. Our knowledge on the relation between atomic structure and electronic states of these extended defects presently starts to grow by applying high-resolution electron microscopy (HRTEM) and deep level transient spectroscopy (DLTS) in combination with numerical simulations. While by means of HRTEM details of structure can be studied, DLTS has been shown to allow for a classification of extended defect states into bandlike and localized. Moreover, this method opens the perspective to distinguish between trap-like and recombination-like electrical activity. In this paper, we emphasize the particular role of nickel and copper silicide precipitates, since in their cases structural features could be successfully related to specific DLTS line characteristics. Rapid quenching from high diffusion temperatures prevents decoration of platelet-shaped NiSi 2 and Cu 3Si precipitates with other impurities. This allows to study their intrinsic electrical activity. Comparison of experimental results with numerical simulations enables identification of structural units originating electrical activity and yields first evaluations of extended defect parameters. Accordingly, e.g., in the case of as-quenched NiSi 2 it is the dislocation bounding the platelet that provides a one-dimensional distribution of deep electronic states.

Riedel, Frank; Hedemann, Henrik; Schröter, Wolfgang

2002-01-01

391

Velocity distributions and relative populations in the fine-structure levels of the a/sup 5/D/sub J/ ground state of Fe atoms, produced by sputtering with 3 keV argon ions, have been investigated by Doppler shifted laser induced fluorescence. The laser system employs a single-mode, scanning ring dye laser, amplified by a sequence of three excimer-pumped flowing-dye cells. Frequency doubling in a KD*P crystal was used to produce high energy (> .5 mJ) pulses of narrowband tunable UV output near 300 nm. Laser power influence on effective velocity bandwidth was investigated. Favorable light-collection geometry minimized distortion of the velocity spectra from apparatus-averaging effects. In impurity flux diagnostic applications in fusion devices, substantial spatial averaging may occur. In the latter case, the narrow velocity bandwidth (70 m/s, transform limit) of the present laser system is particularly useful.

Young, C.E.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.

1983-01-01

392

Electronic states of s,p atoms in strong nonuniform electric fields

NASA Astrophysics Data System (ADS)

Different types of splitting of s,p-element AOs in a one-dimensional electronic potential, which can be represented as a series expansion ?= ?( z0)+ A( z- z0)+ B( z- z0) 2+⋯, ( z0 is the nuclear coordinate), were considered. The region of orbital degeneracy is established for the ground state of the O - radical-anion in the space of A and B parameters. The approach suggested can be used as a basis for determining the types and magnitudes of electric fields that are necessary for changing the AO positions (on the energy scale) in atoms and their chemical compounds, with the aim of controlling their physicochemical properties and reactivity.

Abronin, Igor'A.; Vorontsova, Irina K.; Mikheikin, Igor'D.

2003-01-01

393

NASA Astrophysics Data System (ADS)

A potential energy surface for the electronic ground state of ozone has been optimized by using a variational procedure with the exact vibrational Hamiltonian in bond length-bond angle coordinates. In the optimization, the ab initio force field of Borowski, P., Andersson, K., Malmquist, P.-A., and Roos, B. O., 1992, J. chem. Phys., 97, 5568 is taken as the starting point, and the recent observed vibrational band origins up to 4900 cm-1 reported by Floud, J.-M., Barbe, A., Camy-Peyret, C., and Plateaux, J. J., 1996, J. molec. Spectrosc., 177, 34 are involved. The root mean square error of this fit for the 39 observed vibrational energy levels is 0.83 cm-1. In order to test the refined potential, the rovibrational energy levels up to J=15 are calculated and compared with the observed values.

Yan, Guosen; Xian; Hui; Xie, Daiqian

394

Dissipative Preparation of Spin Squeezed Atomic Ensembles in a Steady State

We present and analyze a new approach for the generation of atomic spin-squeezed states. Our method involves the collective coupling of an atomic ensemble to a decaying mode of an open optical cavity. We demonstrate the ...

Dalla Torre, Emanuele G.

395

NASA Astrophysics Data System (ADS)

Nitrous oxide (N2O) is an intermediate compound formed during catalysis occurring in automobile exhaust pipes. Atomic Au in its ground state is unable to react with N2O, however, several Au excited states are bound to N2O, but not all of these states are able to activate N2O bonds. In this work, N2O capture and activation by a single Au atom are studied considering Au in the ground and excited states with multiplicities = 2, 4 and 6. The Au + N2O reactions are studied at multireference second-order perturbation level of theory using Cs symmetry. The AuN2O (4A', 4A'', 6A' and 6A'') adducts are spontaneously created from Au excited states. From these complexes, only the 4A', 6A' and 6A'' states exhibit N2O activation reaction paths yielding N2, NO and O atoms as end products when N2O approaches Au excited states side-on. Cations both ground and excited states, capture N2O although only the Au+ (5A') + N2O (1?+) ? NAuNO+ (5A') reaction (for the end-on and side-on approaches) shows N2O activation with N-N bond breaking. In the case of Au anions, the ground state and most of the excited states capture N2O and activation takes place according to Au- (3A', 5A', 5A'') + N2O (1?+) ? AuO- (3A', 5A', 5A'') + N2(g) for the N2O end-on approach by the oxygen atom. The reaction paths show a metal-gas dative covalent bonding character. Mulliken charge population analysis obtained for the active states shows that the binding is done through charge donation and retro-donation between the metal and the N2O molecule.

Olvera-Neria, Oscar; Bertin, Virineya; Poulain, Enrique

2010-12-01

396

We discuss the production of ultracold molecules in their electronic ground state by photoassociation employing electronically excited states with ion-pair character and strong spin-orbit interaction. A short photoassociation laser pulse drives a non-resonant three-photon transition for alkali atoms colliding in their lowest triplet state. The excited state wave packet is transferred to the ground electronic state by a second laser pulse, driving a resonant two-photon transition. After analyzing the transition matrix elements governing the stabilization step, we discuss the efficiency of population transfer using transform-limited and linearly chirped laser pulses. Finally, we employ optimal control theory to find the most efficient stabilization pathways. We find that the stabilization efficiency can be increased by one and two orders of magnitude for linearly chirped and optimally shaped laser pulses, respectively.

Tomza, Micha?; Musia?, Monika; Moszynski, Robert; Koch, Christiane P

2012-01-01

397

Regionalism picks up speed: New England states find common ground

Initiatives crossing northern New England state borders—including Amtrak’s Downeaster service, joint Maine and New Hampshire efforts to save Portsmouth Naval Shipyard jobs, and Northern Forest Center collaborations—suggest regional economic activity is bigger than ever.

Chuck Morgan

2008-01-01

398

Ground state of N=Z doubly closed shell nuclei in correlated basis function theory

NASA Astrophysics Data System (ADS)

The ground state properties of N=Z doubly closed shell nuclei are studied within correlated basis function theory. A truncated version of the Urbana v14 realistic potential, with spin, isospin, and tensor components, is adopted, together with state-dependent correlations. Fermi hypernetted chain integral equations are used to evaluate the density, distribution function, and ground state energy of 16O and 40Ca. The nuclear matter single operator chain approximation is extended to finite nuclear systems, to deal with the noncommuting part of the correlation operators. The results favorably compare with variational Monte Carlo estimates, when available, and provide a first substantial check of the accuracy of the cluster summation method for state-dependent correlations. We achieve in finite nuclei a treatment of noncentral interactions and correlations having, at least, the same level of accuracy as in nuclear matter. This opens the way for a microscopic study of the medium heavy nuclei ground state using present day realistic Hamiltonians.

Fabrocini, A.; Arias de Saavedra, F.; Co', G.; Folgarait, P.

1998-04-01

399

Ground-state properties of a triangular triple quantum dot connected to superconducting leads

NASA Astrophysics Data System (ADS)

We study ground-state properties of a triangular triple quantum dot connected to two superconducting (SC) leads. In this system orbital motion along the triangular configuration causes various types of quantum phases, such as the SU(4) Kondo state and the Nagaoka ferromagnetic mechanism, depending on the electron filling. The ground state also evolves as the Cooper pairs penetrate from the SC leads. We describe the phase diagram in a wide range of the parameter space, varying the gate voltage, the couplings between the dots and leads, and also the Josephson phase between the SC gaps. The results are obtained in the limit of large SC gap, carrying out exact diagonalization of an effective Hamiltonian. We also discuss in detail a classification of the quantum states according to the fixed point of the Wilson numerical renormalization group (NRG). Furthermore, we show that the Bogoliubov zero-energy excitation determines the ground state of a ? Josephson junction at small electron fillings.

Oguri, Akira; Sato, Izumi; Shimamoto, Masashi; Tanaka, Yoichi

2015-03-01

400

Exact ground states of a staggered supersymmetric model for lattice fermions

We study a supersymmetric model for strongly interacting lattice fermions in the presence of a staggering parameter. The staggering is introduced as a tunable parameter in the manifestly supersymmetric Hamiltonian. We obtain analytic expressions for the ground states in the limit of small and large staggering for the model on the class of doubly decorated lattices. On this type of lattice there are two ground states, each with a different density. In one limit we find these ground states to be a simple Wigner crystal and a valence bond solid state. In the other limit we find two types of quantum liquids. As a special case, we investigate the quantum liquid state on the one dimensional chain in detail. It is characterized by a massless kink that separates two types of order.

Huijse, L. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Moran, N. [Laboratoire Pierre Aigrain, ENS and CNRS, 24 rue Lhomond, F-75005 Paris (France); Department of Mathematical Physics, National University of Ireland, Maynooth (Ireland); Vala, J. [Department of Mathematical Physics, National University of Ireland, Maynooth (Ireland); School of Theoretical Physics, Dublin Institute for Advanced Studies, 10 Burlington Road, Dublin 4 (Ireland); Schoutens, K. [Institute for Theoretical Physics, University of Amsterdam, Science Park 904, P.O. Box 94485, NL-1090 GL Amsterdam (Netherlands)

2011-09-15

401

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

402

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.

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

2015-01-07

403

A theoretical study of TeOH in its electronic ground state

NASA Astrophysics Data System (ADS)

The ab initio multireference single- and double-excitation configuration interaction (MRD-CI) method has been used to calculate the potential surfaces for the six lowest-lying electronic states of the TeOH molecule. The 2A? ground state is predicted to have a bent equilibrium geometry. The first excited state, 2A', is calculated to lie 2695 cm -1 above the ground state. The MORBID program package has been used for the rotation-vibration analysis of the electronic ground state, for which the term values of the fundamental levels are calculated as 582 cm -1 for the Te-O stretching mode, 959 cm -1 for the bending mode, and 3655 cm -1 for the O-H stretching mode.

Rai-Constapel, Vidisha; Liebermann, Heinz-Peter; Buenker, Robert J.; Honigmann, Michael; Jensen, Per

2007-07-01

404

An N-atom Collective State Atomic Clock with Root-N Fold Increase in Effective Frequency and Root atomic clock and the detection scheme to observe the narrowed fringes of a collective state. Besides. This effect is routinely observed in systems such as microwave or Raman atomic clocks [1Â 5]. It is also well

Shahriar, Selim

405

Ground State Structure Search of Fluoroperovskites through Lattice Instability

NASA Astrophysics Data System (ADS)

Many Fluoroperovskite are capable of a ferroelectric transition from a cubic to a tetragonal and even lower-symmetry structures. In this work, we studied systematically the structural phase transitions of several fluoroperovskites ABF3 where A= Na, K and B= Ca, Sr. Combining the Self-Consistent Atom Deformation (SCAD) -- a density-functional method using localized densities -- and the frozen-phonon method which utilizes the isotropy subgroup operations, we calculate the phonon energies and find instabilities which lower the symmetry of the crystal. Following this scheme, we work down to lower symmetry structures until we no longer find instabilities. The final results are used to compare with those obtained from molecular dynamics based on Gordon-Kim potentials.

Mei, W. N.; Hatch, D. M.; Stokes, H. T.; Boyer, L. L.

2002-03-01

406

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

407

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

408

Cavity-based single atom preparation and high-fidelity hyperfine state readout

We prepare and detect the hyperfine state of a single 87Rb atom coupled to a fiber-based high finesse cavity on an atom chip. The atom is extracted from a Bose-Einstein condensate and trapped at the maximum of the cavity field, resulting in a reproducibly strong atom-cavity coupling. We use the cavity reflection and transmission signal to infer the atomic hyperfine state with a fidelity exceeding 99.92% in a read-out time of 100 microseconds. The atom is still trapped after detection.

Roger Gehr; Jürgen Volz; Guilhem Dubois; Tilo Steinmetz; Yves Colombe; Benjamin L. Lev; Romain Long; Jérôme Estčve; Jakob Reichel

2010-02-23

409

Monitoring the status and trends in the availability of the Nation's ground-water supplies is important to scientists, planners, water managers, and the general public. This is especially true in the semiarid to arid southwestern United States where rapid population growth and limited surface-water resources have led to increased use of ground-water supplies and water-level declines of several hundred feet in many aquifers. Individual well observations may only represent aquifer conditions in a limited area, and wells may be screened over single or multiple aquifers, further complicating single-well interpretations. Additionally, changes in ground-water conditions may involve time scales ranging from days to many decades, depending on the timing of recharge, soil and aquifer properties, and depth to the water table. The lack of an easily identifiable ground-water property indicative of current conditions, combined with differing time scales of water-level changes, makes the presentation of ground-water conditions a difficult task, particularly on a regional basis. One approach is to spatially present several indicators of ground-water conditions that address different time scales and attributes of the aquifer systems. This report describes several methods and indicators for presenting differing aspects of ground-water conditions using water-level observations in existing data-sets. The indicators of ground-water conditions developed in this study include areas experiencing water-level decline and water-level rise, recent trends in ground-water levels, and current depth to ground water. The computer programs written to create these indicators of ground-water conditions and display them in an interactive geographic information systems (GIS) format are explained and results illustrated through analyses of ground-water conditions for selected alluvial basins in the Lower Colorado River Basin in Arizona.

Tillman, Fred D.; Leake, Stanley A.; Flynn, Marilyn E.; Cordova, Jeffrey T.; Schonauer, Kurt T.; Dickinson, Jesse E.

2008-01-01

410

The ground and selected low-lying electronic states of the entire series of the first-row transition-metal neutral oxides are investigated by the use of an improved atom superposition and electron delocalization molecular orbital (ASED-MO) approach. Two quantities are found to be very important in achieving agreement with experiment: these are the ??, ?? parameter set-involved in the Wolfsberg-Helmholz constant, K —

Evangelos G Bakalbassis; Maria-Aglaia D Stiakaki; Athanasios C Tsipis; Constantinos A Tsipis

1996-01-01

411

The performance of an improved atom superposition and electron delocalization molecular orbital (ASED-MO) model has been investigated for the ground and selected low-lying excited states of the entire sequence of the highly-polar cationic and anionic first-row transition-metal oxide diatomics. In particular, in both series of compounds deep potential energy curves of an almost Morse-type shape were derived allowing for an

Evangelos G. Bakalbassis; Maria-Aglaia D. Stiakaki; Athanasios C. Tsipis; Constantinos A. Tsipis

1997-01-01

412

E. coli Alkaline Phosphatase (AP) can hydrolyze a variety of chemically diverse phosphate monoesters while making contacts solely to the transferred phosphoryl group and its incoming and outgoing atoms. Strong interactions between AP and the transferred phosphoryl group are not present in the ground state despite the apparent similarity of the phosphoryl group in the ground state and transition state. Such modest ground state affinity is required to curtail substrate saturation and product inhibition, and allow efficient catalysis. To investigate how AP achieves limited affinity for its ground state we first compared binding affinities of several related AP ligands. This comparison revealed a paradox: AP has a much stronger affinity for inorganic phosphate (Pi) than for related compounds that are similar to Pi geometrically and in overall charge but lack a transferable proton. We postulated that the Pi proton could play an important role via transfer to the nearby anion, the active site serine nucleophile (Ser102), resulting in the attenuation of electrostatic repulsion between bound Pi and the Ser102 oxyanion and the binding of Pi in its trianionic form adjacent to a now neutral Ser residue. To test this model, isotope-edited Fourier transform infrared (FTIR) spectroscopy was used to investigate the ionic structure of AP-bound Pi. The FTIR results indicate that the Pi trianion is bound and, in conjunction with previous studies of pH-dependent Pi binding and other results, suggest that Pi dianion transfers its proton to the Ser102 anion of AP. This internal proton transfer results in stronger Pi binding presumably because the additional negative charge on the trianionic Pi allows stronger electrostatic interactions within the AP active site and because the electrostatic repulsion between bound Pi and anionic Ser102 is eliminated when the transferred Pi proton neutralizes Ser102. Indeed, when Ser102 is neutralized the Pi trianion binds AP with a calculated Kd of ?290 fM. These results suggest that electrostatic repulsion between Ser102 and negatively charged phosphate ester substrates contributes to catalysis by the preferential destabilization of the reaction’s E•S ground state. PMID:21692505

Andrews, Logan D.; Deng, Hua; Herschlag, Daniel

2011-01-01

413

Directly measuring the concurrence of atomic two-qubit states through the detection of cavity decay

NASA Astrophysics Data System (ADS)

We present a scheme for directly measuring the concurrence of atomic two-qubit states (including pure states and mixed states) by detecting the photons leaking from the cavities where the atoms are located. We found that it is possible to encode the concurrence of two-atom entangled states in the photon detection results on the cavities. Cavity decay usually plays a passive role in quantum information processing, but in our scheme the decay of cavity mode plays a constructive role, and the state detection for trapped atoms were replaced by the photon detection. Our scheme is more implementable and may be feasible within the current technology.

Zhang, Li-Hua; Yang, Ming; Cao, Zhuo-Liang

2014-05-01

414

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

415

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

416

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

417

Using soil stress state transducers in freezing ground

Technology Transfer Automated Retrieval System (TEKTRAN)

Three instrumented test sections of sand, silt and clay, were constructed to monitor the impact of frost layers on vehicle-induced stresses and to assess the performance of the sensors used to measure such stresses. One of the instruments used to measure in-situ stress is the soil Stress State Tran...

418

Joint Accreditation and State Program Reviews: Breaking New Ground.

ERIC Educational Resources Information Center

To meet increasing demand, the State University System (SUS) of Florida has initiated joint program evaluations with the major professional accrediting bodies. As accreditation and program reviews typically demand similar information and similar procedures the two activities can be synchronized. The purpose of assessing and enhancing quality, a…

LeMon, R. E.; Pitter, Gita Wijesinghe

419

Ordered ground states of metallic hydrogen and deuterium

NASA Technical Reports Server (NTRS)

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

Ashcroft, N. W.

1981-01-01

420

Periodic ground state for the charged massive Schwinger model

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

Nagy, S.; Sailer, K. [Department for Theoretical Physics, University of Debrecen, Debrecen (Hungary); Polonyi, J. [Institute for Theoretical Physics, Louis Pasteur University, Strasbourg (France); Department of Atomic Physics, Lorand Eoetvoes University, Budapest (Hungary)

2004-11-15

421

Electronic structure of isoalloxazines in their ground and excited states

Electronic structures and transitions were calculated for a series of methyl derivatives of 10-methyl alloxazine using the time-dependent density-functional theory. Comparison of quantum chemical results to experimentally determined spectral and photophysical properties of these compounds indicates that these properties may be rationalised on the basis of the proximity effect, whereby two closely located n,?* and ?,?* lowest excited states are

Ewa Sikorska; Igor V. Khmelinskii; Jacek Koput; Jose L. Bourdelande; Marek Sikorski

2004-01-01

422

Ground- and excited-state proton transfers have been investigated with 8-hydroxy-1,3,6-pyrenetrisulfonate, POH, in sodium bis(2-ethylhexyl) sulfosuccinate, AOT, reversed micelle solubilized water pools in isooctane. Since POH is a much stronger acid in the singlet excited state, (POH)*, than in the ground state (pK\\/sub a\\/ = 7.2, pK\\/sub a\\/* = 0.5), excitation of POH by 1-5-mJ, 8-ns, 353-nm laser pulses, at pH

Mario J. Politi; Ogden Brandt; Janos H. Fendler

1985-01-01

423

Ground state energy and width of {sup 7}He from {sup 8}Li proton knockout

The ground state energy and width of {sup 7}He has been measured with the Modular Neutron Array (MoNA) and superconducting dipole Sweeper magnet experimental setup at the National Superconducting Cyclotron Laboratory. {sup 7}He was produced by proton knockout from a secondary {sup 8}Li 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({sub -15}{sup +40}) keV.

Denby, D. H.; DeYoung, P. A.; Hall, C. C. [Department of Physics, Hope College, Holland, Michigan 49423 (United States); Baumann, T.; Bazin, D.; Spyrou, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Breitbach, E.; Howes, R. [Department of Physics, Marquette University, Milwaukee, Wisconsin 53201 (United States); Brown, J. [Department of Physics, Wabash College, Crawfordsville, Indiana 47933 (United States); Frank, N.; Gade, A.; Mosby, S. M.; Peters, W. A.; Thoennessen, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Hinnefeld, J. [Department of Physics and Astronomy, Indiana University at South Bend, South Bend, Indiana 46634 (United States); Hoffman, C. R. [Department of Physics, Florida State University, Tallahassee, Florida 32303 (United States); Jenson, R. A.; Luther, B.; Olson, C. W. [Department of Physics, Concordia College, Moorhead, Minnesota 56562 (United States); Schiller, A. [Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States)

2008-10-15

424

Excited-state properties from ground-state DFT descriptors: A QSPR approach for dyes.

This work presents a quantitative structure-property relationship (QSPR)-based approach allowing an accurate prediction of the excited-state properties of organic dyes (anthraquinones and azobenzenes) from ground-state molecular descriptors, obtained within the (conceptual) density functional theory (DFT) framework. The ab initio computation of the descriptors was achieved at several levels of theory, so that the influence of the basis set size as well as of the modeling of environmental effects could be statistically quantified. It turns out that, for the entire data set, a statistically-robust four-variable multiple linear regression based on PCM-PBE0/6-31G calculations delivers a R(adj)(2) of 0.93 associated to predictive errors allowing for rapid and efficient dye design. All the selected descriptors are independent of the dye's family, an advantage over previously designed QSPR schemes. On top of that, the obtained accuracy is comparable to the one of the today's reference methods while exceeding the one of hardness-based fittings. QSPR relationships specific to both families of dyes have also been built up. This work paves the way towards reliable and computationally affordable color design for organic dyes. PMID:20036173

Fayet, Guillaume; Jacquemin, Denis; Wathelet, Valérie; Perpčte, Eric A; Rotureau, Patricia; Adamo, Carlo

2010-02-26

425

Correlations between ground and excited state spectra of a quantum Dot

The ground and excited state spectra of a semiconductor quantum dot with successive electron occupancy were studied with linear and nonlinear magnetoconductance measurements. A direct correlation was observed between the mth excited state of the N-electron system and the ground state of the (N + m)-electron system for m up to 4. The results are consistent with a single-particle picture in which a fixed spectrum of energy levels is successively filled, except for a notable absence of spin degeneracy. Further departures from the single-particle picture due to electron-electron interaction were also observed. Magnetoconductance fluctuations of ground states show anticrossings where wave function characteristics are exchanged between adjacent levels. PMID:9388178

Stewart; Sprinzak; Marcus; Duruoz; Harris

1997-12-01

426

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

427

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

428

Ultracold Dense Samples of Dipolar RbCs Molecules in the Rovibrational and Hyperfine Ground State

NASA Astrophysics Data System (ADS)

We produce ultracold dense trapped samples of

Takekoshi, Tetsu; Reichsöllner, Lukas; Schindewolf, Andreas; Hutson, Jeremy M.; Le Sueur, C. Ruth; Dulieu, Olivier; Ferlaino, Francesca; Grimm, Rudolf; Nägerl, Hanns-Christoph

2014-11-01

429

Ground-state entropy of the random vertex-cover problem.

Counting the number of ground states for a spin-glass or nondeterministic polynomial-complete combinatorial optimization problem is even more difficult than the already hard task of finding a single ground state. In this paper the entropy of minimum vertex covers of random graphs is estimated through a set of iterative equations based on the cavity method of statistical mechanics. During the iteration both the cavity entropy contributions and cavity magnetizations for each vertex are updated. This approach overcomes the difficulty of iterative divergence encountered in the zero-temperature first-step replica-symmetry-breaking (1RSB) spin-glass theory. It is still applicable when the 1RSB mean-field theory is no longer stable. The method can be extended to compute the entropies of ground states and metastable minimal-energy states for other random-graph spin-glass systems. PMID:19391695

Zhou, Jie; Zhou, Haijun

2009-02-01

430

The rotational excitation by helium of methanol in its ground and first excited torsional states

We have improved and extended our previous calculations of cross sections for the rotational excitation of methanol by helium. In the case of methanol in its torsional ground state, we extended our coupled states computations of the cross sections to higher collision energies and larger rotational basis sets. The accuracy of the rotational energy levels and eigenfunctions has been reviewed

J. T. Pottage; D. R. Flower; Stephen L. Davis

2002-01-01

431

Theoretical Studies of the Ground and Excited State Structures of Stilbene

NASA Astrophysics Data System (ADS)

Optimized geometries are evaluated for the ground and low lying excited states of cis-stilbene, trans-stilbene, and 4a,4b-dihydrophenanthrene (DHP) from calculations performed with the improved virtual orbital, complete active space configuration interaction (IVO-CASCI) method. The calculations indicate that a nonplanar conformer of trans-stilbene is the most stable among the isomers. The calculated ground and low lying excited state geometries agree well with experiment and with prior theoretical estimates where available. Our IVO-CASCI based multireference Möller-Plesset (MRMP) computations place the 1Bu state of trans stilbene to be -4.0 eV above the ground X1Ag state, which is in accord with experiment and with earlier theoretical estimates. The 11Bu state of trans-stilbene can be represented by the highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) transition (ionic type) from the ground state, whereas its 21Bu state is dominated by the HOMO - LUMO+1 and HOMO-1 - LUMO transitions (covalent type). Likewise, the 11B and 21B states of cis-stilbene and DHP are also found to be of ionic and covalent types, respectively.

Chaudhuri, Rajat K.; Freed, Karl F.; Chattopadhyay, Sudip; Mahapatra, Uttam Sinha

2013-10-01

432

A search was made within a 125-mile radius of Erie, Pennsylvania, to ; discover a possible site for a national land burial ground to receive and bury ; low and intermediate level radioactively contaminated waste. The new burial ; facility would serve a sixteen state section of the northeastern United States. ; Estimated unit burial costs and computed transportation charges

J. M. Jr

1956-01-01

433

NASA Astrophysics Data System (ADS)

Spin-orbit coupled Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel quantum devices. Here we consider a quasi-two-dimensional spin-orbit coupled Bose–Einstein condensate confined in an external harmonic potential, with emphasis on the effects of anisotropic spin-orbit coupling on the equilibrium ground-state structure of such a system. For the cases with spin-orbit coupling solely in x- or y-axis direction, the ground-state structure can develop to the well-known standing wave phase, in which the two components always form an alternative density arrangement. For a two-dimensional anisotropic spin-orbit coupling, the separated lumps first become bend, then form two rows of stripe structure along y direction with further increasing the strength of spin-orbit coupling in x-direction. Furthermore, the distance between these two rows of stripe structure is also investigated in detail. Supported by National Natural Science Foundation of China under Grant No. 61361002, the Applied Fundamental Research Projects of Yunnan Province under Grant No. 2013FZ121

He, Wan-Quan; Gao, Ri-Li; Zhang, Pei; Bi, Xiong-Wei; Pan, Qing-Shan; Xu, Shi-Juan

2015-03-01

434

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

435

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

436

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

437

Teleportation with insurance of an entangled atomic state via cavity decay

We propose a scheme to teleport an entangled state of two {lambda}-type three-level atoms via photons. The teleportation protocol involves the local redundant encoding protecting the initial entangled state and allowing for repeating the detection until quantum information transfer is successful. We also show how to manipulate a state of many {lambda}-type atoms trapped in a cavity.

Chimczak, Grzegorz; Tanas, Ryszard; Miranowicz, Adam [Nonlinear Optics Division, Physics Institute, Adam Mickiewicz University, 61-614 Poznan (Poland)

2005-03-01

438

NASA Technical Reports Server (NTRS)

Radiation simulation tests (protons and electrons) were performed along with atomic oxygen flight tests aboard the Shuttle to space qualify the surface protective coatings. The results, which contributed to the selection of indium-tin-oxide (ITO) coated polyester as the material for the thermal blankets of the Galileo Spacecraft, are given here. Two candidate materials, polyester and Fluorglas, were radiation-tested to determine changes at simulated Jovian radiation levels. The polyester exhibited a smaller weight loss (2.8) than the Fluorglas (8.8 percent). Other changes of polyester are given. During low-earth orbit, prior to transit to Jupiter, the thermal blankets would be exposed to atomic oxygen. Samples of uncoated and ITO-coated polyesters were flown on the Shuttle. Qualitative results are given which indicated that the ITO coating protected the underlying polyester.

Bouquet, Frank L.; Maag, Carl R.

1986-01-01

439

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

440

Reversible switching of the electronic ground state in a pentacoordinated Cu(II) complex.

An easy reversible switching of the electronic ground state in a pentacoordinated copper(II) complex is reported for the first time. The simple protonation of a carboxylic group in a Cu(II) complex with a {dx(2)-y(2)}(1) electronic configuration leads to a flip of the ground electronic configuration from {dx(2)-y(2)}(1) to {dz(2)}(1) in the metal ion. PMID:23884406

Sasmal, Ashok; Saha, Sandeepta; Gómez-García, Carlos J; Desplanches, Cédric; Garribba, Eugenio; Bauzá, Antonio; Frontera, Antonio; Scott, Reum; Butcher, Ray J; Mitra, Samiran

2013-09-14

441

Ground-state configuration of the N=157 nucleus 259No

NASA Astrophysics Data System (ADS)

The ground-state configuration of the N=157 nucleus 259No has been identified through ?-? coincidence and ?-singles measurements. Three ? transitions were observed for the first time in the ? decay of 259No, and its decay scheme was established. The neutron 9/2+[615] configuration was assigned to the ground state of 259No as well as to the 231.4 keV level in 255Fm. Ground-state deformations and neutron single-particle energies in Z=102 isotopes were calculated with the macroscopic-microscopic model. The 9/2+[615] orbital was calculated to be the highest among the five orbitals between the N=152 and 162 deformed shell gaps, which is consistent with the experimental one-quasiparticle energies in N=153 and 155 isotones, but is inconsistent with the present experimental result of the 9/2+[615] ground state at N=157. To reproduce the 9/2+[615] ground state at N=157, the order of the neutron orbitals should be different between the N=153 and 157 isotones.

Asai, M.; Tsukada, K.; Sakama, M.; Haba, H.; Ichikawa, T.; Ishii, Y.; Toyoshima, A.; Ishii, T.; Nishinaka, I.; Nagame, Y.; Kasamatsu, Y.; Shibata, M.; Kojima, Y.; Hayashi, H.

2013-01-01

442

Three-body correlations in the ground-state decay of 26O

NASA Astrophysics Data System (ADS)

Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound 26O can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration and 2 n halo structure. Purpose: To use the experimentally measured three-body correlations to gain insight into the properties of 26O , including the decay mechanism and ground-state resonance energy. Method: 26O was produced in a one-proton knockout reaction from 27F and the 24O+n +n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the 26O ground-state resonance decay were extracted. The experimental results were compared to Monte Carlo simulations in which the resonance energy and decay mechanism were varied. Results: The measured three-body correlations were well reproduced by the Monte Carlo simulations but were not sensitive to the decay mechanism due to the experimental resolutions. However, the three-body correlations were found to be sensitive to the resonance energy of 26O . A 1 ? upper limit of 53 keV was extracted for the ground-state resonance energy of 26O . Conclusions: Future attempts to measure the three-body correlations from the ground-state decay of 26O will be very challenging due to the need for a precise measurement of the 24O momentum at the reaction point in the target.

Kohley, Z.; Baumann, T.; Christian, G.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Luther, B.; Lunderberg, E.; Jones, M.; Mosby, S.; Smith, J. K.; Spyrou, A.; Thoennessen, M.

2015-03-01

443

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.

444

Educational Assistance Provided by the United States Atomic Energy Commission

The Atomic Energy Act of 1946, with its later amendments, directed the Atomic Energy Commission (AEC) to conduct research, development, and training in the field iof atomic energy. These activities were initially retained within the national laboratories and other AEC sites because the major portion of nuclear technology was classified. As declassification proceeded, the AEC started an intensive program of

Vincent E. Parker

1966-01-01

445

Donor-acceptor biradicals as ground state analogues of photoinduced charge separated states.

A Valence Bond Configuration Interaction (VBCI) model is used to relate the intraligand magnetic exchange interaction (J) to the electronic coupling matrix element (HAB) in Tp(Cum,MeZn)(SQNN), a compound that possesses a Donor-Acceptor (D-A) SemiQuinone-NitronylNitroxide (SQNN) biradical ligand. Within this framework, an SQ --> NN charge transfer state mixes with the ground state and stabilizes the spin triplet (S = 1). This charge-transfer transition is observed spectroscopically and probed using resonance Raman spectroscopy. In addition, the temperature-dependent electronic absorption spectrum of the Ni(II) complex, Tp(Cum,MeNi)(SQNN), has been studied. Exchange coupling between the S = 1 Ni(II) ion and S = 1 SQNN provides a mechanism for observing the formally spin-forbidden, ligand-based 3GC --> 1CTC transition. This provides a means of determining U, the mean GC --> CTC energy, and a one-center exchange integral, K(0). The experimental determination of J, U, and K(0) permits facile calculation of HAB, and we show that this methodology can be extended to determine the electronic coupling matrix element in related SQ-Bridge-NN molecules. As magnetic susceptibility measurements are easily acquired in the solid state, H(AB) may be effectively determined for single molecules in a known geometry, provided a crystal structure exists for the biradical complex. Thus, SQ-Bridge-NN molecules possess considerable potential for probing both geometric and electronic structure contributions to the magnitude of the electronic coupling matrix element associated with a given bridge fragment. PMID:17263528

Kirk, Martin L; Shultz, David A; Depperman, Ezra C; Brannen, Candice L

2007-02-21

446

The mechanism of nitrogen atom transfer from four-coordinate tris(carbene)borate iron(IV) nitrido complexes to phosphines and phosphites has been investigated. In the absence of limiting steric effects, the rate of nitrogen atom transfer to phosphines increases with decreasing phosphine ?-basicity. This trend has been quantified by a Hammett study with para-substituted triarylphosphines, and is contrary to the expectations of an electrophilic nitrido ligand. On the basis of electronic structure calculations, a dual-nature transition state for nitrogen atom transfer is proposed, in which a key interaction involves the transfer of electron density from the nitrido highest occupied molecular orbital (HOMO) to the phosphine lowest unoccupied molecular orbital (LUMO). Compared to analogous atom transfer reactions from a 5d metal, these results show how the electronic plasticity of a 3d metal results in rapid atom transfer from pseudotetrahedral late metal complexes. PMID:21902179

Scepaniak, Jeremiah J; Margarit, Charles G; Harvey, Jeremy N; Smith, Jeremy M

2011-10-01

447

Scalable solid-state quantum processor using subradiant two-atom states.

We propose a realization of a scalable, high-performance quantum processor whose qubits are represented by the ground and subradiant states of effective dimers formed by pairs of two-level systems coupled by resonant dipole-dipole interaction. The dimers are implanted in low-temperature solid host material at controllable nanoscale separations. The two-qubit entanglement either relies on the coherent excitation exchange between the dimers or is mediated by external laser fields. PMID:12443508

Petrosyan, David; Kurizki, Gershon

2002-11-11

448

Ground state of graphene slabs in an external electric field

NASA Astrophysics Data System (ADS)

Unlike graphene (AB) stacks, (ABC) stacks have two interesting properties: they are topological insulators with only surface states at the Fermi level, and they develop a tunable gap in an external electric field. The total energy of graphene (AB) stacks is lower than of (ABC) stacks which coincides with the empirical fact that graphite is mainly (AB) stacked. An external perpendicular electric field, however, makes (ABC) stacks energetically more favorable than (AB) stacks. Thus, growing or annealing stacks in an external electric field might become a device to increase the yield in (ABC) sequences or even to produce (ABC) stacks in a controlled way.

Taut, M.; Xiao, Ruijuan

2011-12-01

449

Symmetry breaking in the ground state of BNB: a high level multireference study.

A series of multireference approaches based on the SA-CASSCF wave function, i.e., CASPT2, MRCI, MRCI + Q, and MRAQCC with single- or multireference states, have been employed to investigate the symmetry breaking effect in the ground state X (2)Sigma(u)(+) of the triatomic BNB radical. We found that the mixing of the reference states contributes significantly to the dynamical correlation energy, which strongly affects the geometry of the ground state. Our results show that BNB in its ground state has a linear noncentrosymmetric structure with two equivalent global minima of the adiabatic potential energy surface and, respectively, two oppositely directed dipole moments of about 2 D. The barrier between the minima is about 20 cm(-1). The origin of the double-minimum potential in the ground state of BNB is explained as due to the pseudo-Jahn-Teller effect involving vibronic interaction with the first excited state A (2)Sigma(g)(+) via the asymmetric stretching vibrations. PMID:19449919

Liu, Yang; Zou, Wenli; Bersuker, Isaac B; Boggs, James E

2009-05-14

450

NASA Astrophysics Data System (ADS)

The interplay between frustration and quantum fluctuation in magnetic systems is known to be the origin of many exotic states in condensed matter physics. In this paper, we consider a frustrated four-leg spin tube under a magnetic field. This system is a prototype to study the emergence of a nonmagnetic ground state factorizable into local states and the associated order parameter without quantum fluctuation that appears in a wide variety of frustrated systems. The one-dimensional nature of the system allows us to apply various techniques: a path-integral formulation based on the notion of order by disorder, strong-coupling analysis where magnetic excitations are gapped, and density-matrix renormalization group. All methods point toward an interesting property of the ground state in the magnetization plateaus, namely, a quantized value of relative magnetizations between different sublattices (spin imbalance). The ground-state properties can be understood in terms of a direct product of local states on each rung, which is the exact ground state on certain plateaus in the strong-coupling limit.

Plat, X.; Fuji, Y.; Capponi, S.; Pujol, P.

2015-02-01

451

Breakdown of the Bardeen-Cooper-Schrieffer ground state at a quantum phase transition

Advances in solid-state and atomic physics are exposing the hidden relationships between conventional and exotic states of quantum matter. Prominent examples include the discovery of exotic superconductivity proximate to conventional spin and charge order, and the crossover from long-range phase order to preformed pairs achieved in gases of cold fermions and inferred for copper oxide superconductors. The unifying theme is

R. Jaramillo; Yejun Feng; J. C. Lang; Z. Islam; G. Srajer; P. B. Littlewood; D. B. McWhan; T. F. Rosenbaum

2009-01-01

452

Quantum electrodynamics near a photonic band gap: Photon bound states and dressed atoms

It is shown that in dielectrics exhibiting a complete photonic band gap, quantum electrodynamics predicts the occurrence of bound states of photons to hydrogenic atoms. When the atomic transition frequency lies near a photonic band edge, the excited atomic level experiences an anomalous Lamb shift and splits into a doublet. One member of this doublet exhibits resonance fluorescence whereas the

Sajeev John; Jian Wang

1990-01-01

453

Surface modification using low energy ground state ion beams

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

454

Global ab initio ground-state potential energy surface of N4

NASA Astrophysics Data System (ADS)

We present a global ground-state potential energy surface for N4 suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation in N2-N2 collisions. To obtain the surface, complete active space second-order perturbation theory calculations were performed for the ground singlet state with an active space of 12 electrons in 12 orbitals and the maug-cc-pVTZ triple zeta basis set. About 17 000 ab initio data points have been calculated for the N4 system, distributed along nine series of N2 + N2 geometries and three series of N3 + N geometries. The six-dimensional ground-state potential energy surface is fitted using least-squares fits to the many-body component of the electronic energies based on permutationally invariant polynomials in bond order variables.

Paukku, Yuliya; Yang, Ke R.; Varga, Zoltan; Truhlar, Donald G.

2013-07-01

455

The Network Source Location Problem: Ground State Energy, Entropy and Effects of Freezing

NASA Astrophysics Data System (ADS)

Ground state entropy of the network source location problem is evaluated at both the replica symmetric level and one-step replica symmetry breaking level using the entropic cavity method. The regime that is a focus of this study, is closely related to the vertex cover problem with randomly quenched covered nodes. The resulting entropic message passing inspired decimation and reinforcement algorithms are used to identify the optimal location of sources in single instances of transportation networks. The conventional belief propagation without taking the entropic effect into account is also compared. We find that in the glassy phase the entropic message passing inspired decimation yields a lower ground state energy compared to the belief propagation without taking the entropic effect. Using the extremal optimization algorithm, we study the ground state energy and the fraction of frozen hubs, and extend the algorithm to collect statistics of the entropy. The theoretical results are compared with the extremal optimization results.

Huang, Haiping; Raymond, Jack; Wong, K. Y. Michael

2014-07-01

456

Observation of the Ground State Bands in 109Pd and 111Pd

NASA Astrophysics Data System (ADS)

The neutron-rich nuclei 109 Pd and 111Pd were produced as fission fragments following the 30Si + 168Er reaction at a beam energy of 142 MeV. Using the identification based on the coincidences with the complementary fission fragments, the ground state bands in 109Pd and 111Pd were found. They are the only positive-parity bands observed so far in 109Pd and 111 Pd. A band, built on top of the 5/2+ ground state exhibiting ?I = 1 energy-level staggering was observed in each of these nuclei. Both nuclei of interest, 109Pd and 111 Pd, are suggested to lie in the transitional region of Pd isotopes of maximum ?-softness. The ground states of both nuclei are predicted by TRS calculations to be extremely ?-soft with shallow triaxial minima. The first crossing in the new bands is proposed to be due to an alignment of h211/2 neutrons.

Stefanova, E. A.; Lalkovski, S.; Korichi, A.; Kutsarova, T.; Lopez-Martens, A.; Xu, F. R.; Liu, H. L.; Kisyov, S.; Minkova, A.; Bazzaco, D.; Bergström, M.; Görgen, A.; Hannachi, F.; Herskind, B.; Hübel, H.; Jansen, A.; Khoo, T. L.; Podolyák, Zs; Schönwasser, G.

2014-09-01

457

Ground states and dynamics of a trapped charged particle in the magnetic field

A system of two charged particles in a harmonic trap with additional magnetic field is considered. The problem is reduced to a single-particle one in relative coordinates. The ground- and lowest excited-state energies and wave functions are found. The ground state exhibits non-zero expectation value of the velocity (kinetic momentum) and the probability current density does not vanish as well. When the ground state becomes degenerate the expectation value of velocity becomes discontinuous. The effects associated with turning on of the magnetic field are studied by solving the appropriate time-dependent Schr\\"odinger equation. No substantial differences between abrupt (discontinuous in time) and continuous switching on have been observed. Evolution of a wave packet which is initially Gaussian is also investigated. The wave packet loses its Gaussian nature and, after sufficiently large time, a system of diffractive maxima and minima is built.

Maciej Janowicz; Jan Mostowski

2013-10-15

458

Absence of ground state for the Nelson model on static space-times

We consider the Nelson model on some static space-times and investigate the problem of absence of a ground state. Nelson models with variable coefficients arise when one replaces in the usual Nelson model the flat Minkowski metric by a static metric, allowing also the boson mass to depend on position. We investigate the absence of a ground state of the Hamiltonian in the presence of the infrared problem, i.e. assuming that the boson mass $m(x)$ tends to $0$ at spatial infinity. Using path space techniques, we show that if $m(x)\\leq C |x|^{-\\mu}$ at infinity for some $C>0$ and $\\mu>1$ then the Nelson Hamiltonian has no ground state.

Christian Gérard; Fumio Hiroshima; Annalisa Panati; A. Suzuki

2010-12-13

459

Geometric control of ground state multiplicity in a copper(I) bis(verdazyl) complex.

A copper(I) complex of a 3-(6'-isopropylpyridyl)-substituted verdazyl was synthesized and characterized by X-ray crystallography and magnetic susceptibility. The complex crystallizes in the monoclinic space group C2/c with cell dimensions a = 22.544 A, b = 11.576 A, c = 17.157 A, ? = 123.907°, V = 3716.2 A(3). The coordination geometry at copper is distorted tetrahedral, with the two ligand planes separated by 75°. Magnetic susceptibility measurements indicate that the ground state of the diradical is a triplet at this geometry. Fitting to a simple Heisenberg Hamiltonian (H = -JS(1)·S(2)) gave J = 47(1) cm(-1). The triplet ground state results from exchange mediated by the copper ion; in particular, the direction of the distortion from tetrahedral geometry appears to be essential to maintain the high-spin ground state. PMID:20731362

Brook, David J R; Yee, Gordon T; Hundley, Mike; Rogow, David; Wong, Janice; Van-Tu, Khanh

2010-09-20

460

Ground state of the H{sub 2}{sup +} molecule in oblique magnetic fields

Calculations in the Born-Oppenheimer approximation of curves for the ground-state energy of the H{sub 2}{sup +} ion vs the separation, R, of its protons in magnetic fields making oblique angles {theta} with the line connecting the protons have recently been published. It is shown here that these curves are qualitatively incorrect. The variational trial function employed fails to approximate well the wave function of the H{sub 2}{sup +}