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1

Collisions of dressed ground-state atoms  

SciTech Connect

We study collisions between dressed ground-state atoms in a full coupled-channel approach. In this way we examine collisions in the microwave trap, in the cryogenic hydrogen maser, and in the context of rf-induced evaporative cooling. The results for dressed H atoms confirm earlier results obtained within the so-called degenerate internal states approximation. {copyright} {ital 1996 The American Physical Society.}

Moerdijk, A.J.; Verhaar, B.J.; Nagtegaal, T.M. [Eindhoven University of Technology, Box 513, 5600 MB Eindhoven (The Netherlands)

1996-06-01

2

Constrained molecular dynamics simulations of atomic ground states  

SciTech Connect

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

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

2005-07-15

3

Ground states of extended Hubbard models in the atomic limit  

Microsoft Academic Search

The possible ground states of an extended Hubbard model in the atomic limit, augmented by an additional nearest neighbour Ising-like interaction and an external magnetic field, are rigorously determined for arbitrary values of the coupling parameters and arbitrary chemical potential. The method used requires only simple convexity arguments and the examination of all possible configurations of small clusters of lattice

U. Brandt; J. Stolze

1986-01-01

4

All-optical reconstruction of atomic ground-state population  

SciTech Connect

The population distribution within the ground state of an atomic ensemble is of great significance in a variety of quantum-optics processes. We present a method to reconstruct the detailed population distribution from a set of absorption measurements with various frequencies and polarizations, by utilizing the differences between the dipole matrix elements of the probed transitions. The technique is experimentally implemented on a thermal rubidium vapor, demonstrating a population-based analysis in two optical-pumping examples. The results are used to verify and calibrate an elaborated numerical model, and the limitations of the reconstruction scheme, which result from the symmetry properties of the dipole matrix elements, are discussed.

London, P.; Firstenberg, O.; Shuker, M.; Ron, A. [Department of Physics, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2010-04-15

5

A probable vacuum state containing a large number of hydrogen atom of excited state or ground state K, Rb or Cs atom  

Microsoft Academic Search

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

6

The Static Dipole Polarizabilities of All the Neutral Atoms in Their Ground States  

Microsoft Academic Search

Values of the static dipole polarizabilities of all neutral atoms in ; their ground electronic states were collected and tabulated. A bibliography for ; both theoretical and experimental determinations is included. (auth);

R. R. Teachout; R. T. Pack

1971-01-01

7

Long-range interactions of excited He atoms with ground-state noble-gas atoms  

NASA Astrophysics Data System (ADS)

The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2?n?10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition operators. The large-n expansions for the sums over the He oscillator strength divided by the corresponding transition energy are presented for these series. Using the expansions, the C6 coefficients for the systems involving He(131,3S) and He(131,3P) are calculated and found to be in good agreement with directly calculated values.

Zhang, J.-Y.; Qian, Y.; Yan, Z.-C.; Schwingenschlögl, U.

2013-10-01

8

Influence of an External Electric Field on Thermal Collisions Between Circular Rydberg-State Atoms and Ground-State Helium.  

National Technical Information Service (NTIS)

The influence of an external electric field on thermal collisions between a sodium atom excited in a ''circular'' Rydberg state and a ground-state helium atom is studied numerically within the framework of the impulse approximation. The effect of the fiel...

E. Prunele

1986-01-01

9

Helium AtomSCF-LCAO Calculation of the (1s)2 Ground State of the  

NSDL National Science Digital Library

Using a double-zeta basis of Slater-type orbitals [STOs], this Java applet calculates the single determinant singlet ground state 1s2 wavefunction of the helium atom. The doubly occupied orbital is expanded in terms of two basis functions, 1s and 1s`.

10

Ground-state cooling for a trapped atom using cavity-induced double electromagnetically induced transparency.  

PubMed

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

11

Merit of ground-state electronegativities; a reply to ``Comments on `Introduction to the chemistry of fractionally charged atoms: Electronegativity' ''  

Microsoft Academic Search

The arguments presented in the Comment by Liebman and Huheey are shown to be incorrect. The operational equivalence of Mulliken ground-state electronegativities and Pauling electronegativities is demonstrated for neutral atoms. It is shown that ground-state electronegativities and valence-state electronegativities for both neutral atoms and ions are also operationally equivalent. A single electronegativity scale based on Mulliken ground-state electronegativities may therefore

Klaus S. Lackner; George Zweig

1987-01-01

12

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

SciTech Connect

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

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

2010-04-15

13

Merit of ground-state electronegativities; a reply to ''Comments on 'Introduction to the chemistry of fractionally charged atoms: Electronegativity' ''  

SciTech Connect

The arguments presented in the Comment by Liebman and Huheey are shown to be incorrect. The operational equivalence of Mulliken ground-state electronegativities and Pauling electronegativities is demonstrated for neutral atoms. It is shown that ground-state electronegativities and valence-state electronegativities for both neutral atoms and ions are also operationally equivalent. A single electronegativity scale based on Mulliken ground-state electronegativities may therefore be used for neutral atoms, ions, and fractionally charged atoms, as originally implied in the paper by Lackner and Zweig.

Lackner, K.S.; Zweig, G.

1987-09-01

14

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

15

Ground-state properties of artificial bosonic atoms, Bose interaction blockade, and the single-atom pipette  

SciTech Connect

We analyze the ground-state properties of an artificial atom made out of repulsive bosons attracted to a center for the case that all the interactions are short ranged. Such bosonic atoms could be created by optically trapping ultracold particles of alkali-metal vapors; we present the theory describing how their properties depend on experimentally adjustable strength of 'nuclear' attraction and interparticle repulsion. The binding ability of the short-range potential increases with space dimensionality, only a limited number of particles can be bound in one dimension, while in two and three dimensions the number of bound bosons can be chosen at will. Particularly in three dimensions we find an unusual effect of enhanced resonant binding: for not very strong interparticle repulsion the equilibrium number of bosons bound to a nuclear potential having a sufficiently shallow single-particle state increases without bound as the nuclear potential becomes less attractive. As a consequence of the competing nuclear attraction enhanced by the Bose statistics and interparticle repulsions, the dependence of the ground-state energy of the atom on the number of particles has a minimum whose position is experimentally tunable. This implies a staircase dependence of the equilibrium number of bound bosons on external parameters which may be used to create a single-atom pipette--an arrangement which allows the transport of atoms into and out of a reservoir, one at a time.

Kolomeisky, Eugene B.; Kalas, Ryan M. [Department of Physics, University of Virginia, 382 McCormick Rd., P.O. Box 400714, Charlottesville, Virginia 22904-4714 (United States); Straley, Joseph P. [Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)

2004-06-01

16

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

17

Cesium atom ground state coherence created by an optical frequency comb laser  

NASA Astrophysics Data System (ADS)

Quantum interference resolved by the coherent laser modes from a mode-locked laser is significant in demonstrating femtosecond-laser based high resolution spectroscopy. Moreover, the high Q frequency discriminator resulted from quantum interference phenomenon could possibly serve for comb laser repetition rate stabilization. We discovered a 5-Hz width transparent window when the repetition rate of our optical frequency comb laser [1] was adjusted to be on resonance of cesium atom ground state hyperfine transition. We showed that cesium atom ground state coherence might be created by the comb laser modes, based on the observation of Zeeman effects. We performed our experiment with 8700 Pascal Neon buffer gas and 100^oC (1 mK instability) wall temperature. Frequency shift by wall temperature and the other effects will be presented.[3pt] [1] Appl. Phys. B 92, 13-18 (2008).

Cheng, Wang-Yau; Wu, Tsung-Han; Lu, Sheng-Huei

2009-05-01

18

Gas flow dependence of ground state atomic oxygen in plasma needle discharge at atmospheric pressure  

SciTech Connect

We present clear evidence that ground state atomic oxygen shows two patterns near a surface in the helium plasma needle discharge. Two-photon absorption laser-induced fluorescence spectroscopy, combined with gas flow simulation, was employed to obtain spatially-resolved ground state atomic oxygen densities. When the feed gas flow rate is low, the radial density peaks along the axis of the needle. At high flow rate, a ring-shaped density distribution appears. The peak density is on the order of 10{sup 21} m{sup -3} in both cases. The results are consistent with a previous report of the flow-dependent bacterial killing pattern observed under similar conditions.

Sakiyama, Yukinori; Graves, David B. [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Knake, Nikolas; Schroeder, Daniel; Winter, Joerg; Schulz-von der Gathen, Volker [Institut fuer Experimentalphysik II, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

2010-10-11

19

The fine-structure splitting of the thallium atomic ground state: LS versus jj-coupling  

Microsoft Academic Search

We examine the spin-orbit splitting of the 2P electronic ground state of the Tl atom by two different approaches, both of which incorporate relativistic effects: namely, a four-component method involving the Dirac-Coulomb-Breit Hamiltonian, and a two-component method which makes use of the Douglas-Kroll transformed no-pair Hamiltonian. The former method operates by definition in the jj-coupling scheme, while the latter uses

Frank Rakowitz; Christel M. Marian

1996-01-01

20

Four-quantum RF-resonance in the ground state of an alkaline atom  

Microsoft Academic Search

The multiple-quantum resonances in Zeeman structure of the ground state of Potassium atoms can be observed in Earth magnetic field under intense RF excitation. They complicate the magnetic resonance spectrum and can lead to errors in the magnetic field measurement by Potassium magnetometer. On the other hand, the highest-order 4-quantum resonance F = 2, mF = Leftrightarrow mF' = -2

E. Alexandrov; A. Pazgalev

1997-01-01

21

Evolution of an Optically Pumped Ensemble of Cold Ground-State Atoms in Weak Light Fields  

SciTech Connect

The evolution of multipole moments is analyzed for optically pumped cold ground-state atoms in the limit of low saturation of a closed j{sub 0} {yields} j{sub 1} dipole transition. The longest multipole-moment relaxation times are analyzed as functions of ellipticity and frequency detuning from resonance for transitions with j{sub 0} < or approx. 5. The qualitative difference between the evolution toward steady-state Zeeman sublevel populations and dynamics of transient spontaneous emission is demonstrated for transitions of the following types: j {yields} j - 1, j {yields} j with integer j, j {yields} j with half-integer j, and j {yields} j + 1.

Bezverbnyi, A.V. [Admiral Nevelskii Maritime State University, Vladivostok, 690059 (Russian Federation); Tomsk State University, Tomsk, 634050 (Russian Federation)

2005-05-01

22

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) osonic ground state energy ?(Z,N) yields the monotone non-decreasing function N|-->?(?N,N)/N3 for any ? > 0. The main part of the paper furnishes a proof that whenever ? >= ?* ~ 1/1.21, then the limit ?(?):=limN-->??(?N,N)/N3 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 R3N, 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

23

Using Uncertainty Principle to Find the Ground-State Energy of the Helium and a Helium-like Hookean Atom  

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

24

Correlation effects in the ground state of trapped atomic Bose gases  

SciTech Connect

We study the effects of many-body correlations in trapped ultracold atomic Bose gases. We calculate the ground state of the gas using a ground-state auxiliary-field quantum Monte Carlo (QMC) method [Phys. Rev. E 70, 056702 (2004)]. We examine the properties of the gas, such as the energetics, condensate fraction, real-space density, and momentum distribution, as a function of the number of particles and the scattering length. We find that the mean-field Gross-Pitaevskii (GP) approach gives qualitatively incorrect result of the kinetic energy as a function of the scattering length. We present detailed QMC data for the various quantities, and discuss the behavior of GP, modified GP, and the Bogoliubov method under a local density approximation (LDA)

Purwanto, Wirawan; Zhang Shiwei [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187 (United States)

2005-11-15

25

Time dependence of desorbed ground-state lithium atoms following pulsed-electron-beam irradiation of lithium fluoride  

Microsoft Academic Search

Recent experiments have shown that during the irradiation of lithium fluoride crystals by a chopped electron beam the signal of desorbed ground-state lithium atoms continues for times up to seconds in the beam-off period. A quantitative model is presented which connects the desorption of lithium atoms with the diffusion of lithium fluoride F centers to the surface. The model thus

T. A. Green; G. M. Loubriel; P. M. Richards; N. H. Tolk; Haglund R. F. Jr

1987-01-01

26

Particle-localized ground state of atom-molecule Bose-Einstein condensates in a double-well potential  

SciTech Connect

We study the effect of atom-molecule internal tunneling on the ground state of atom-molecule Bose-Einstein condensates in a double-well potential. In the absence of internal tunneling between atomic and molecular states, the ground state is symmetric, which has equal-particle populations in two wells. From the linear stability analysis, we show that the symmetric stationary state becomes dynamically unstable at a certain value of the atom-molecule internal tunneling strength. Above the critical value of the internal tunneling strength, the ground state bifurcates to the particle-localized ground states. The origin of this transition can be attributed to the effective attractive interatomic interaction induced by the atom-molecule internal tunneling. This effective interaction is similar to that familiar in the context of BCS-BEC crossover in a Fermi gas with Feshbach resonance. Furthermore, we point out the possibility of reentrant transition in the case of the large detuning between the atomic and molecular states.

Motohashi, Atsushi; Nikuni, Tetsuro [Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

2010-09-15

27

Using uncertainty principle to find the ground-state energy of the helium and a helium-like Hookean atom  

NASA Astrophysics Data System (ADS)

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 cloud. Our calculation also shows how the Coulomb interaction between electrons affects their distribution. This leads to a physical picture of how electrons are located with respect to each other in these atoms. Finally, we also obtain through our calculations a general formula for the estimate of ground-state energy and radius of two electron atoms and ions with atomic number Z.

Harbola, Varun

2011-11-01

28

High precision calculations on the sup 2 S ground state of the lithium atom  

SciTech Connect

The results of a detailed variational calculation on the {sup 2}{ital S} ground state of the lithium atom are reported. The wave function was constructed using Hylleraas-type functions with extensive exponent optimization being employed. The calculated nonrelativistic ground state energy obtained was {minus}7.478 059 53 a.u., which is the lowest upper bound estimate for this quantity obtained to date. The discrepancy with semi-empirical estimates of this quality is discussed. The hyperfine coupling constant for {sup 7}Li is calculated to be 401.795 MHz, which compares favorably with the experimental result of 401.752 043 3 MHz. Expectation values are reported for the individual energy components, as well as the electron density at the nucleus, and the specific mass shift operator. The transition isotope shift is also evaluated. The convergence characteristics of the calculations are discussed, along with the effect of retaining only one of the two possible spin eigenfunctions in the basis set.

King, F.W.; Bergsbaken, M.P. (Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin 54702 (USA))

1990-08-15

29

Specific mass shift for the sup2S ground state of the lithium atom  

SciTech Connect

The absolute specific mass shifts for the /sup 2/S ground state of the lithium atom are calculated using a 352-term Hylleraas-type wave function. The specific mass shifts for /sup 7/Li and /sup 6/Li are 5.180 and 6.042 cm/sup -1/, respectively, using first-order perturbation theory, and 5.177 cm/sup -1/ (/sup 7/Li) and 6.039 cm/sup -1/ (/sup 6/Li) from a nonperturbative approach. With use of Pekeris's accurate values for the specific mass shifts of Li/sup +/, the transition isotope shift of Li relative to Li/sup +/ is calculated to be 1.101 GHz, using first-order perturbation theory, and 1.071 GHz from a nonperturbative procedure. The calculated shift is in very close agreement with the experimental value of 1.111 +- 0.006 GHz obtained by Lorenzen and Niemax.

King, F.W.

1986-12-01

30

Ground-state alignment of atoms and ions: New Diagnostics of Astrophysical Magnetic Field in Diffuse Medium  

Microsoft Academic Search

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 (

H. Yan; A. Lazarian

2009-01-01

31

Four-quantum RF-resonance in the ground state of an alkaline atom  

NASA Astrophysics Data System (ADS)

The multiple-quantum resonances in Zeeman structure of the ground state of Potassium atoms can be observed in Earth magnetic field under intense RF excitation. They complicate the magnetic resonance spectrum and can lead to errors in the magnetic field measurement by Potassium magnetometer. On the other hand, the highest-order 4-quantum resonance F = 2, mF = Leftrightarrow mF' = -2 shows up special features which make it attractive for application in Earth field magnetometry. Unlike any other single- or multiple-quantum resonances, the frequency of this one is strictly linear with the magnetic field strength and practically independent of the driving RF-field amplitude. Besides, this resonance has the greatest resolving power and can be very easy selected on the back-ground of the other broadened resonances. The problem of the magnetic resonance in 8-level system has been solved numerically without any restriction on the RF-field intensity. The experimentally recorded spectra match the theory.

Alexandrov, E.; Pazgalev, A.

1997-01-01

32

Long-range interactions between an atom in its ground S state and an open-shell linear molecule  

NASA Astrophysics Data System (ADS)

Theory of long-range interactions between an atom in its ground S state and a linear molecule in a degenerate state with a nonzero projection of the electronic orbital angular momentum is presented. It is shown how the long-range coefficients can be related to the first and second-order molecular properties. The expressions for the long-range coefficients are written in terms of all components of the static and dynamic multipole polarizability tensor, including the nondiagonal terms connecting states with the opposite projection of the electronic orbital angular momentum. It is also shown that for the interactions of molecules in excited states that are connected to the ground state by multipolar transition moments additional terms in the long-range induction energy appear. All these theoretical developments are illustrated with the numerical results for systems of interest for the sympathetic cooling experiments: interactions of the ground state Rb(2S) atom with CO(3?), OH(2?), NH(1?), and CH(2?) and of the ground state Li(2S) atom with CH(2?).

Skomorowski, Wojciech; Moszynski, Robert

2011-03-01

33

Long-range interactions between an atom in its ground S state and an open-shell linear molecule.  

PubMed

Theory of long-range interactions between an atom in its ground S state and a linear molecule in a degenerate state with a nonzero projection of the electronic orbital angular momentum is presented. It is shown how the long-range coefficients can be related to the first and second-order molecular properties. The expressions for the long-range coefficients are written in terms of all components of the static and dynamic multipole polarizability tensor, including the nondiagonal terms connecting states with the opposite projection of the electronic orbital angular momentum. It is also shown that for the interactions of molecules in excited states that are connected to the ground state by multipolar transition moments additional terms in the long-range induction energy appear. All these theoretical developments are illustrated with the numerical results for systems of interest for the sympathetic cooling experiments: interactions of the ground state Rb((2)S) atom with CO((3)?), OH((2)?), NH((1)?), and CH((2)?) and of the ground state Li((2)S) atom with CH((2)?). PMID:21456655

Skomorowski, Wojciech; Moszynski, Robert

2011-03-28

34

ATOMIC AND MOLECULAR PHYSICS: Elastic Collisions Between two Ground-State P and D Atoms at Low and Ultralow Temperatures  

NASA Astrophysics Data System (ADS)

The PD(X3?-) interaction potential is constructed using the CCSD(T) theory and the basis set, aug-cc-pV5Z. Using this potential, the spectroscopic parameters are accurately determined. The present Do, De, Re, ?e, ?e?e, ?e, and Be are of 3.056 99 eV, 3.161 75 eV, 0.142 39 nm, 1701.558 cm-1, 23.6583 cm-1, 0.085 99 cm-1, and 4.3963 cm-1, respectively, which almost perfectly conform with the measurements. A total of 26 vibrational states is predicted when J = 0 by solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which favorably agree with the experiments. The total and various partial-wave cross sections are calculated for the elastic impact between two ground-state P and D atoms at 1.0 × 10-12 - 1.0 × 10-4 a.u. when they approach each other along the PD(X3?-) potential. No shape resonances exist in the total elastic cross sections, though the peaks can be found for each partial wave until l = 6. The shape of the total elastic cross sections is dominated by the s partial wave at very low temperatures. Due to the weakness of the shape resonances of each partial wave, they are all passed into oblivion by the strong total elastic cross sections.

Shi, De-Heng; Zhang, Jin-Ping; Sun, Jin-Feng; Ma, Heng; Liu, Yu-Fang; Zhu, Zun-Lue

2010-02-01

35

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

36

Optical pumping method for squeezing and entanglement in the ground-state spin subsystems of macroscopic atomic ensembles  

SciTech Connect

We describe the mechanism of squeezing and entanglement in the ground-state spin subsystems of macroscopic atomic ensembles via the process of stimulated cooperative Raman-type scattering of correlated photon pairs. This mechanism is analogous to common optical pumping techniques normally used for depopulation of Zeeman sublevels in macroscopic atomic ensembles. We show that, by the excitation of atoms, oriented in their angular momenta, with nonclassical light consisting of a rare flux of strongly correlated photon pairs, essential correlations in the macroscopic spin fluctuations can be transferred and accumulated. In turn this leads to squeezing or entanglement in the quasispin (alignment) subsystems of macroscopic ensembles. We discuss in particular a scheme for an interferometer that would be available for the control or teleportation of quantum states created in quasispin subsystems. Such squeezed and entangled states can be stored in long-lived spin subsystems and can be further used in quantum information protocols based on the continuous variable technique.

Kupriyanov, D.V.; Sokolov, I.M.; Slavgorodskii, A.V. [Department of Theoretical Physics, State Technical University, 195251, St. Petersburg (Russian Federation)

2003-10-01

37

Crossed beam study of the atom-radical reaction of ground state carbon atoms (C(3P)) with the vinyl radical (C2H3(X2A')).  

PubMed

The atom-radical reaction of ground state carbon atoms (C((3)P)) with the vinyl radical (C(2)H(3)(X(2)A')) was conducted under single collision conditions at a collision energy of 32.3 ± 2.9 kJ mol(-1). The reaction dynamics were found to involve a complex forming reaction mechanism, which is initiated by the barrier-less addition of atomic carbon to the carbon-carbon-double bond of the vinyl radical forming a cyclic C(3)H(3) radical intermediate. The latter has a lifetime of at least 1.5 times its rotational period and decomposes via a tight exit transition state located about 45 kJ mol(-1) above the separated products through atomic hydrogen loss to the cyclopropenylidene isomer (c-C(3)H(2)) as detected toward cold molecular clouds and in star forming regions. PMID:22120638

Wilson, Antony V; Parker, Dorian S N; Zhang, Fangtong; Kaiser, Ralf I

2011-11-25

38

Investigation of ionization processes in subthermal collisions of rubidium n{sup 2}P atoms with one another and with the ground-state Rb atoms  

SciTech Connect

The chemoionization processes in Rydberg-Rydberg and Rydberg-ground-state rubidium collisions at 60 K were investigated for the principal quantum number n=11. The ratio of the rate constant k{sub 2} for atomic ion formation in Rydberg-Rydberg collisions to the rate constant k{sub 1} for associative ionization in Rydberg-ground-state atomic collisions was measured. The value k{sub 2}=(1.5 {plus_minus} 0.4) X 10{sup -8} cm{sup 3} s{sup -1} was determined using the literature data for k{sub 1}. The value obtained coincides to a factor of two with that calculated within the Katsuura-Smirnov model. 16 refs., 4 figs.

Borodin, V.M.; Dobrolezh, B.V.; Klyucharev, A.N.; Tsyganov, A.B. [St. Petersburg State Univ., Peterhof (Russian Federation)

1995-01-01

39

Anomalies in the shape of atomic resonant absorption lines under conditions of strong optical pumping of hyperfine structure components of the ground state  

Microsoft Academic Search

The ground electronic state of even such simple atoms as those of alkali elements has the set of sublevels. These sublevels are hyperfine (HF) components and magnetic sublevels. The collisions with particles of nonmagnetic buffer gas or even with walls (when walls have proper coating) do not mix practically the populations of ground state HF sublevels, if the orbital moment

A. I. Parkhomenko; S. P. Pod'Yachev; T. I. Privalov; A. M. Shalagin

1998-01-01

40

Hydrogen maser wall shift experiments and determination of the unperturbed hyperfine frequency of the ground state of the hydrogen atom  

SciTech Connect

Experiments on hydrogen maser wall shift are described in detail. Values of K(40 C) -293 + or - 17 mHz.cm and a(40 C) (-17 + or 2) x 10 to the -3rd per deg C were obtained. The unperturbed hyperfine frequency of the ground state of the hydrogen atom was obtained by comparing five hydrogen masers to Loran C signals for one month. The average value with respect to TAI is 1,420,405,751.768 + or - 0.002 Hz.

Cheng, Y.M.; Hua, Y.L.; Chen, C.B.; Gao, J.H.; Shen, W.

1980-12-01

41

Correlated-Gaussian calculations of the ground and low-lying excited states of the boron atom  

SciTech Connect

Benchmark variational calculations of the four lowest {sup 2}P and {sup 2}S states of the boron atom (including the ground state) have been performed. The wave functions of the states have been expanded in terms of all-particle explicitly correlated Gaussian basis functions and the finite mass of the nucleus has been explicitly accounted for. Variational upper bounds for the nonrelativistic finite- and infinite-nuclear-mass energies of all considered states have been obtained with the relative convergence of the order of 10{sup -7}-10{sup -8}. Expectation values of the powers of the inter-particle distances and Dirac {delta} functions depending on those distances have also been computed. These calculations provide reference values that can be used to test other high-level quantum chemistry methods.

Bubin, Sergiy [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Adamowicz, Ludwik [Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721 (United States); Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States)

2011-02-15

42

Ground state of the polar alkali-metal-atom-strontium molecules: Potential energy curve and permanent dipole moment  

SciTech Connect

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

43

Ground-state properties of one-dimensional matter and the Zel'dovich effect in Rydberg atoms  

NASA Astrophysics Data System (ADS)

The following dissertation consists of three parts. The first two concern ground-state properties of one-dimensional matter, while the third describes an experimental realization of the Zel'dovich effect in Rydberg atoms. Motivated by emerging experimental possibilities to confine atoms and molecules in quasi-one-dimensional geometries, in Chapters 1 and 2 we analyze ground-state properties of strictly one-dimensional molecular matter comprised of identical particles of mass m interacting by a Morse potential between nearest neighbors. We find that due to zero-point motion, the system first undergoes a discontinuous evaporation transition into a diatomic gas followed by a continuous dissociation transition into a monoatomic gas. In particular we find that spin-polarized isotopes of hydrogen and 3He are monoatomic gases, 4He is a diatomic gas, while molecular hydrogen and heavier substances are Luttinger liquids. We also investigate the effect of finite pressure on the properties of the liquid and monoatomic gas phases. In particular we estimate a pressure at which molecular hydrogen undergoes an inverse Peierls transition into a metallic state which is a one-dimensional analog of the transition predicted by Wigner and Huntington in 1935. In Chapter 2, we show that dissociation of the Luttinger liquid is a process initiated at the system edge. The latter becomes unstable against quantum fluctuations at a value of De Boer's number which is smaller than that of the bulk instability which parallels the classical phenomenon of surface melting. In 1959 Ya. B. Zel'dovich predicted that the bound-state spectrum of the non-relativistic Coulomb problem distorted at small distances by a short-range potential undergoes a peculiar reconstruction whenever this potential alone supports a low-energy scattering resonance. However documented experimental evidence of this effect has been lacking. In Chapter 3 we demonstrate that along the Periodic Table of elements the Zel'dovich effect manifests itself as a systematic periodic variation of the Rydberg spectra with a period proportional to the cubic root of the atomic number. This dependence, which is supported by analysis of experimental and numerical data, has its origin in the binding properties of the ionic core of the atom.

Timmins, Michael Anthony

44

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

Microsoft Academic Search

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

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

2009-01-01

45

Current DFT vs. Ordinary DFT for Atomic Ground States in External Magnetic Fields  

NASA Astrophysics Data System (ADS)

Current Density Functional Theory (CDFT) is the relatively unexplored extension of ordinary DFT to include magnetic fields B via the gauge-invariant combination nabla × ( j_p/n) of the paramagnetic current density jp and the density n. On occasion, ordinary DFT has been used with external B fields by simple use of the mapping p arrow p - (e/c) A. To understand the relative importance of terms that enter from this mapping compared to those intrinsic to CDFT (e.g. A_xc), as well as to understand issues of representation of CDFT quantities in gaussian-type basis functions, we have implemented CDFT in our gaussian-basis atomic code GATOM. We discuss both the change from spherical (central field) to cylindrical symmetry and basis set size, compare magnitudes of the various magnetic contributions, compare available A_xc approximations, and compare both forms of DFT with Hartree-Fock calculations for light atoms. This effort is part of our complete reworking of ``GTOFF'', our gaussian-type-orbital, all-electron, periodic system code [S.B. Trickey, J.A. Alford, and J.C. Boettger, in Theoretical and Computational Chemistry vol. 8 of ``Computational Materials Science'', J. Leszczynski ed. (Elsevier) in press] to include CDFT for periodic systems.

Zhu, Wuming; Trickey, S. B.; Alford, J. A.

2004-03-01

46

The reaction of benzene with a ground state carbon atom, C({sup 3}P{sub j})  

SciTech Connect

The reaction between benzene and a single ground state carbon atom, C({sup 3}P{sub j}), which yields a C{sub 7}H{sub 5} radical without a barrier in the exit channel, has been studied using density functional theory (B3LYP), Moeller-Plesset perturbation theory, and the G2(B3LYP/MP2) and complete basis set (CBS) model chemistries. Comparing the computed reaction energies for the formation of various C{sub 7}H{sub 5} radicals with experimental data suggests that the 1,2-didehydrocycloheptatrienyl radical (15) is observed in crossed-beams experiments at collision energies between 2 and 12 kcal mol{sup -1}. The carbon atom attacks the {pi}-electron density of benzene and forms without entrance barrier a C{sub s} symmetric complex (17T) in which the carbon atom is bound to the edge of benzene. From 17T, the insertion of the C atom into a benzene CC bond to yield triplet cycloheptatrienylidene (9T) is associated with a much lower barrier than the insertion into a CH bond to give triplet phenylcarbene (7T). As both steps are strongly exothermic, high energy vinyl carbene rearrangements on the triplet C{sub 7}H{sub 6} potential energy surface provide pathways between 9T and 7T below the energy of separated reactants. In addition, intersystem crossing in the vicinity of 17T and 9T might give rise to singlet cycloheptatetraene (12S). The monocyclic seven-membered ring compounds 9T or 12S are precursors of the 1,2-didehydrocycloheptatrienyl radical: the dissociation of a CH bond {alpha} to the divalent carbon atom proceeds without an exit barrier, in agreement with experiment. In contrast, a direct carbon-hydrogen exchange reaction pathway analogous to the aromatic electrophilic substitution followed by rearrangement of phenylcarbyne (13) to 15 involves high barriers (39 kcal mol-1 with respect to separated reactants) and is thus not viable under the experimental conditions. (c) 2000 American Institute of Physics.

Bettinger, Holger F. [Institut fuer Organische Chemie, Universitaet Erlangen-Nuernberg, Henkestr. 42, D-91054 Erlangen, (Germany); Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Schleyer, Paul v. R. [Institut fuer Organische Chemie, Universitaet Erlangen-Nuernberg, Henkestr. 42, D-91054 Erlangen, (Germany); Schaefer, Henry F. III [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Schreiner, Peter R. [Institut fuer Organische Chemie, Universitaet Goettingen, Tammannstr. 2, D-37077 Goettingen, (Germany); Kaiser, Ralf I. [Institute of Atomic and Molecular Sciences I, Section 4, Roosevelt Rd., 107 Taipei, Taiwan, Republic of China (China); Lee, Yuan T. [Institute of Atomic and Molecular Sciences I, Section 4, Roosevelt Rd., 107 Taipei, Taiwan, Republic of China (China)

2000-09-08

47

Optical control of ground-state atomic orbital alignment: Cl({sup 2}P{sub 3/2}) atoms from HCl(v=2,J=1) photodissociation  

SciTech Connect

H{sup 35}Cl(v=0,J=0) molecules in a supersonic expansion were excited to the H{sup 35}Cl(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7 {mu}m. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220 nm after a time delay, and the velocity-dependent alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The {sup 35}Cl({sup 2}P{sub 3/2}) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the H{sup 35}Cl(v=2,J=1,M=0) molecule to the {sup 35}Cl({sup 2}P{sub 3/2}) nuclear spin [which is conserved during the photodissociation and thus contributes to the total {sup 35}Cl({sup 2}P{sub 3/2}) photofragment atomic polarization] and (2) the alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state {sup 35}Cl({sup 2}P{sub 3/2}) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.

Sofikitis, Dimitris; Rubio-Lago, Luis; Martin, Marion R.; Ankeny Brown, Davida J.; Bartlett, Nathaniel C.-M.; Alexander, Andrew J.; Zare, Richard N.; Rakitzis, T. Peter [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete, Greece and Department of Physics, University of Crete, P.O. Box 2208, 71003 Voutes-Heraklion (Greece); Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete (Greece); Department of Chemistry, Stanford University, Stanford, California 94305-5080 (United States); School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ (United Kingdom); Department of Chemistry, Stanford University, Stanford, California 94305-5080 (United States); Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete, Greece and Department of Physics, University of Crete, P.O. Box 2208, 71003 Voutes-Heraklion (Greece)

2007-10-14

48

Optical control of ground-state atomic orbital alignment: Cl(2P3/2) atoms from HCl(v=2,J=1) photodissociation  

NASA Astrophysics Data System (ADS)

H35Cl(v=0,J=0) molecules in a supersonic expansion were excited to the H35Cl(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7 ?m. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220 nm after a time delay, and the velocity-dependent alignment of the 35Cl(2P3/2) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The 35Cl(2P3/2) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the H35Cl(v=2,J=1,M=0) molecule to the 35Cl(2P3/2) nuclear spin [which is conserved during the photodissociation and thus contributes to the total 35Cl(2P3/2) photofragment atomic polarization] and (2) the alignment of the 35Cl(2P3/2) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the 35Cl(2P3/2) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state 35Cl(2P3/2) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.

Sofikitis, Dimitris; Rubio-Lago, Luis; Martin, Marion R.; Ankeny Brown, Davida J.; Bartlett, Nathaniel C.-M.; Alexander, Andrew J.; Zare, Richard N.; Rakitzis, T. Peter

2007-10-01

49

Electric field of a pointlike charge in a strong magnetic field and ground state of a hydrogenlike atom  

SciTech Connect

In an external constant magnetic field, so strong that the electron Larmour length is much shorter than its Compton length, we consider the modification of the Coulomb potential of a point charge owing to the vacuum polarization. We establish a short-range component of the static interaction in the Larmour scale, expressed as a Yukawa-like law, and reveal the corresponding 'photon mass' parameter. The electrostatic force regains its long-range character in the Compton scale: the tail of the potential follows an anisotropic Coulomb law, decreasing away from the charge slower along the magnetic field and faster across. In the infinite-magnetic-field limit the potential is confined to an infinitely thin string passing though the charge parallel to the external field. This is the first evidence for dimensional reduction in the photon sector of quantum electrodynamics. The one-dimensional form of the potential on the string is derived that includes a {delta} function centered in the charge. The nonrelativistic ground-state energy of a hydrogenlike atom is found with its use and shown not to be infinite in the infinite-field limit, contrary to what was commonly accepted before, when the vacuum polarization had been ignored. These results may be useful for studying properties of matter at the surface of extremely magnetized neutron stars.

Shabad, A. E.; Usov, V. V. [P.N. Lebedev Physics Institute, Moscow (Russian Federation); Center for Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel)

2008-01-15

50

High accuracy ab initio studies of electron-densities for the ground state of Be-like atomic systems.  

PubMed

Benchmark results for electron densities in the ground states of Li(-), Be, C(2+), Ne(6+), and Ar(14+) have been generated from very accurate variational wave functions represented in terms of extensive basis sets of exponentially correlated Gaussian functions. For Ne(6+), and Ar(14+), the upper bounds to the energies improve over previous results known from the literature. For the remaining systems our bounds are from 0.1 to 1.1 ?hartree higher than the most accurate ones. We present in graphical and, partially, numerical form results both for the radial electron densities and for the difference radial density distributions (DRD) (defined with respect to the Hartree-Fock radial density) that highlight the impact of correlation effects on electron densities. Next, we have employed these DRD distributions in studies of the performance of several broadly used orbital-based quantum-chemical methods in accounting for correlation effects on the density. Our computed benchmark densities for Be have been also applied for testing the possibility of using the mathematically strict result concerning exact atomic electron densities, obtained by Ahlrichs et al. [Phys. Rev. A 23, 2106 (1981)], for the determination of the reliability range of computed densities in the long-range asymptotic region. The results obtained for Be are encouraging. PMID:23635137

Komasa, J; S?upski, R; Jankowski, K; Wasilewski, J; Teale, A M

2013-04-28

51

Two-parameter partially correlated ground-state electron density of some light spherical atoms from Hartree-Fock theory with nonintegral nuclear charge  

SciTech Connect

Partially correlated ground-state electron densities for some spherical light atoms are calculated, into which nonrelativistic ionization potentials represent essential input data. The nuclear cusp condition of Kato is satisfied precisely. The basic theoretical starting point, however, is Hartree-Fock (HF) theory for the N electrons under consideration but with nonintegral nuclear charge Z{sup '} slightly different from the atomic number Z (=N). This HF density is scaled with a parameter {lambda}, near to unity, to preserve normalization. Finally, some tests are performed on the densities for the atoms Ne and Ar, as well as for Be and Mg.

Cordero, Nicolas A.; March, Norman H.; Alonso, Julio A. [Departamento de Fisica, Universidad de Burgos, C/ Villadiego s/n, E-09001 Burgos (Spain); Department of Physics, University of Antwerp (RUCA), 171 Groenenborgerlaan, B-2020 Antwerp (Belgium); Oxford University, Oxford, England (United Kingdom); Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, E-47011 Valladolid (Spain)

2007-05-15

52

Ground-state alignment of atoms and ions: New Diagnostics of Astrophysical Magnetic field in diffuse medium  

Microsoft Academic Search

We discuss a new technique of studying magnetic fields in diffuse\\u000aastrophysical media, e.g. interstellar and intergalactic gas\\/plasma. This\\u000atechnique is based on the angular momentum alignment of atoms and ions in their\\u000aground or metastable states. As the life-time of atoms in such states is long,\\u000athe alignment induced by anisotropic radiation is susceptible to weak magnetic\\u000afields ($1{\\\\rm

Huirong Yan; A. Lazarian

2008-01-01

53

Ground State Spin Logic  

NASA Astrophysics Data System (ADS)

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.

Whitfield, James; Faccin, Mauro; Biamonte, Jacob

2013-03-01

54

Experimental investigation of the longitudinal relaxation time of electronic polarization of the ground state of potassium atoms in a cell with an antirelaxation coating on the walls  

Microsoft Academic Search

We report the results of an experimental investigation of the longitudinal relaxation time T\\u000a 1 of the electronic polarization of the ground state of potassium atoms in cells with an antirelaxation coating on the walls.\\u000a Investigations were performed for a number of cells at temperature T=24C. The maximum recorded relaxation times ? are 3.6, 4.3, and 5.2 s for cells

M. V. Balabas; M. I. Karuzin; A. S. Pazgalev

1999-01-01

55

Towards a differential equation for the nonrelativistic ground-state electron density of the He-like sequence of atomic ions  

SciTech Connect

The early study of Schwartz [Ann. Phys. (N.Y.) 6, 156 (1959)] led to an explicit expression for the ground-state electron density {rho}(r) of He-like atomic ions with nuclear charge Ze in the limit of large Z. Much later, Gal, March, and Nagy [Chem. Phys. Lett. 305, 429 (1999)] derived a third-order linear homogeneous differential equation satisfied by the Schwartz limiting density. Our aim here has been to solve a still correlated model more closely related to the He atom itself. Motivated by semiclassical studies (as by Handke [Phys. Rev. A 50, R3561 (1994)]), we have solved a fully quantal model in which the Coulomb repulsion energy e{sup 2}/r{sub 12} of the two electrons at separation r{sub 12} is expanded in a one-center form about the atomic nucleus and only the s-wave term is retained. From the resulting analytical ground-state density, a differential equation has been derived, which is contrasted with that satisfied by the large-Z limiting form of Schwartz. Suggestions are finally made as to the way the density of the He atomic ion series may be characterized, the ionization potential I(Z) being proposed as crucial input data.

Howard, I.A. [Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); March, N.H. [Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Oxford University, Oxford (United Kingdom)

2005-04-01

56

Models including electron correlation in relation to Fock's proposed expansion of the ground-state wave function of He-like atomic ions  

SciTech Connect

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

Glasser, M. L.; March, N. H.; Nieto, L. M. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, ES-47011 Valladolid, Spain and Department of Physics, Clarkson University, Potsdam, New York 13699 (United States); Department of Physics, University of Antwerp, BE-2020 Antwerp, Belgium and Department of Theoretical Chemistry, University of Oxford, Oxford OX1 2JD (United Kingdom); Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, ES-47011 Valladolid (Spain)

2011-12-15

57

Quantum control of linear susceptibility in five level atoms via dressed interacting ground states, with a focus on group velocity control  

NASA Astrophysics Data System (ADS)

Electromagnetically induced transparency (EIT) is a quantum coherence effect by which a strong laser is used to cancel absorption for a second, weaker laser propagating in the same medium. Within the transparency window, dispersion is large, permitting the observation of very small group velocities and other effects. We generalize EIT to a five level atom in which two driven ground state doublets, denoted {|b>, |b>} and {|c>, |c'>}, interact with an excited state, |a>. We call systems with this level configuration "dressed interacting ground states (DIGS) systems. We study the DIGS configuration under two sets of initial conditions. In the first, we consider a closed system that is initially in the ground state |b>. We find that the EIT spectrum is modified to include two new features located within the transparency window, whose widths and locations can be tuned by the external fields. In the vicinity of these features, we find small windows of very large dispersion and suppressed absorption, permitting group velocities up to two orders of magnitude smaller than an identically configured EIT system without the additional couplings. In the second case, we permit population to accrue in the second ground state doublet by introducing incoherent pumping terms. When the population of | c'> exceeds the population of |b>, the absorption resonances already described become amplification resonances. For larger populations in |c'>, the dispersion between these amplification lines changes sign, leading to a prediction of superluminal and negative group velocities. Varying the pumping rate can smoothly change the group velocity in the system from sub- to superluminal. In all cases, we derive analytic solutions. Our results for the pumped atom are of particular relevance because they describe as a limiting case a system that has received wide attention in the literature, but has only been studied numerically. We also consider a manifestation of the DIGS level configuration in a double well Bose-Einstein condensate. Here, coherent tunneling between the wells replaces the electromagnetic couplings between ground states. In this case, the new features could be used for precision measurements of atomic tunneling, thermometry, and non-local control of light propagation.

Weatherall, James Owen

58

Investigations of the ground-state hyperfine atomic structure and beta decay measurement prospects of {sup 21}Na with improved laser trapping techniques  

SciTech Connect

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

59

Rotating Ground States of a One-Dimensional Spin-Polarized Gas of Fermionic Atoms with Attractive p-Wave Interactions on a Mesoscopic Ring  

SciTech Connect

The major finding of this Letter is that a one-dimensional spin-polarized gas composed of an even number of fermionic atoms interacting via attractive p-wave interactions and confined to a mesoscopic ring has a degenerate pair of ground states that are oppositely rotating. In any realization the gas will be measured to rotate one way or the other in spite of the fact that there is no external rotation or bias fields. Our goal is to show that this counterintuitive finding is a natural consequence of the combined effects of quantum statistics, ring topology, and exchange interactions.

Girardeau, M. D. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Wright, E. M. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States)

2008-05-23

60

High-accuracy measurement of the 87Rb ground-state hyperfine splitting in an atomic fountain  

NASA Astrophysics Data System (ADS)

We describe the operation of a laser-cooled rubidium 87Rb frequency standard. We present a new measurement of the 87Rb hyperfine frequency with a 1.3 × 10-14 relative accuracy, by comparison with a Cs fountain primary standard. The measured 87Rb ground-state hyperfine splitting is ?87 = 6 834 682 610.90429(9) Hz. This value differs from previously published values (see Essen L., Hope E. G. and Sutcliffe D., Nature 189 1961 298; Penselin S., Moran T., Cohen W. and Wscinkler G., Phys. Rev. 127 1962 524; Arditi M. and Cerez P. IEEE Trans. Instrum. Meas. IM-21 1972 391) by about 2 - 3 Hz and is 104 times more accurate. Because of the low collisional shift in 87Rb, future improvements may lead to a stability of 1 × 10-14?-1/2 and a relative accuracy in the 10-17 range.

Bize, S.; Sortais, Y.; Santos, M. S.; Mandache, C.; Clairon, A.; Salomon, C.

1999-03-01

61

Roothaan-Hartree-Fock ground-state atomic wave functions: Slater-type orbital expansions and expectation values for Z = 2-54  

SciTech Connect

Roothaan-Hartree-Fock orbitals expressed in a Slater-type basis are reported for the ground states of He through Xe. Energy accuracy ranges between 8 and 10 significant figures, reducing by between 21 and 2,770 times the energy errors of the previous such compilation (E. Clementi and C. Roetti, Atomic Data and Nuclear Data Tables 14, 177, 1974). For each atom, the total energy, kinetic energy, potential energy, virial ratio, electron density at the nucleus, and the Kato cusp are given together with radial expectation values [l angle]r[sup n][r angle] with n from [minus]3 to 2 for each orbital, orbital energies, and orbital expansion coefficients. 29 refs., 1 tab.

Bunge, C.F.; Barrientos, J.A. (Universidad Nacional Autonoma de Mexico, Mexico City (Mexico)); Bunge, A.V. (Universidad Autonoma Metropolitana, Iztapalapa (Mexico))

1993-01-01

62

FAST TRACK COMMUNICATION: Generalized geometrical model for photoionization of polarized atoms: II. Magnetic dichroism in the 3p photoemission from the K 3p64s 2S1/2 ground state  

NASA Astrophysics Data System (ADS)

The generalized geometrical model for photoionization from polarized atoms is extended to include mixing of configurations in the initial atomic and/or the final photoion states. The theoretical results for angle-resolved linear and circular magnetic dichroism are in good agreement with new high-resolution photoelectron data for 3p-1 photoionization of potassium atoms polarized in the K 3p64s 2S1/2 ground state by laser optical pumping.

Grum-Grzhimailo, A. N.; Cubaynes, D.; Heinecke, E.; Hoffmann, P.; Zimmermann, P.; Meyer, M.

2010-10-01

63

Dynamics of neutral gas depletion investigated by time- and space-resolved measurements of xenon atom ground state density  

NASA Astrophysics Data System (ADS)

The dynamics of neutral gas depletion in high-density plasmas is investigated by time- and space-resolved measurements of the xenon ground state density. Two-photon absorbed laser induced fluorescence experiments were carried out in a helicon reactor operating at 10 mTorr in xenon gas. When the plasma is magnetized, a plasma column is formed from the bottom of the chamber up to the pumping region. In this situation it is found that two phenomena, with different time scales, are responsible for the neutral gas depletion. The magnetized plasma column is ignited in a short (millisecond) time scale leading to a neutral gas depletion at the discharge centre and to an increase of neutral gas density at the reactor walls. This is explained both by neutral gas heating and by the rise of the plasma pressure at the discharge centre. Then, on a much longer (second) time scale, the overall neutral gas density in the reactor decreases due to higher pumping efficiency when the magnetized plasma column is ignited. The pumping enhancement is not observed when the plasma is not magnetized, probably because in this case the dense plasma column vanishes and the plasma is more localized near the antenna.

Liard, L.; Aanesland, A.; Chabert, P.

2012-06-01

64

Dual Magneto-Optical Trap of Sodium Atoms in Ground Hyperfine F=1 and F=2 States  

Microsoft Academic Search

Sodium atoms were trapped in a dual-operation magneto-optical trap using laser light whose frequency was tuned at 18 MHz to the red of the F=2 to F'=3 transition and laser light whose frequency was tuned at 11 MHz to the red of the F=1 to F'=0 transition. The number of trapped atoms increased to 1.2× 1010 atoms, which is a

Hideki Tanaka; Hiromitsu Imai; Katsuki Furuta; Yukihide Kato; Susumu Tashiro; Masayuki Abe; Ryousuke Tajima; Atsuo Morinaga

2007-01-01

65

Inactivation of Penicillium digitatum Spores by a High-Density Ground-State Atomic Oxygen-Radical Source Employing an Atmospheric-Pressure Plasma  

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

66

The production of O(3P) and ground state OH in the reaction of hydrogen atoms with ozone  

Microsoft Academic Search

The production of significant concentrations of O(3P) in the gas phase reaction of hydrogen atoms with ozone in a fast flow discharge system at 1.1±0.1 Torr total pressure in Ar and at room temperature has been reported earlier. These yields were observed to be independent of the concentration of known deactivators of OH† (v = 9) such as O2 and

B. J. Finlayson-Pitts; T. E. Kleindienst; M. J. Ezell; D. W. Toohey

1981-01-01

67

Ground State of Anderson Hamiltonian  

NASA Astrophysics Data System (ADS)

Following the Wiegmann approach the exact expression of the ground state energy for the symmetric Anderson Hamiltonian was obtained. In this paper the calculation is done for the asymmetric Anderson Hamiltonian, of the ground state energy, of the average number of localized electrons and of the charge susceptibility.

Kawakami, Norio; Okiji, Ayao

1982-04-01

68

High-energy tail of the linear momentum distribution in the ground state of hydrogen atoms or hydrogen-like ions  

NASA Astrophysics Data System (ADS)

A long-standing dispute concerning the high-energy tail of the linear momentum distribution (HTMD) in the ground state of hydrogen atoms/hydrogen-like ions (GSHA) has been unresolved up to now. A possible resolution of the above dispute might be connected to the problem of the role of singular solutions of quantal equations, which is a fundamental problem in its own right. The paradigm is that, even allowing for finite nuclear sizes, singular solutions of the Dirac equation for the Coulomb problem should be rejected for nuclear charges Z < 1/??137. In this paper we break this paradigm. First, we derive a general condition for matching a regular interior solution with a singular exterior solution of the Dirac equation for arbitrary interior and exterior potentials. Then we find explicit forms of several classes of potentials that allow such a match. Finally, we show that, as an outcome, the HTMD for the GSHA acquires terms falling off much slower than the 1/p6-law prescribed by the previously adopted quantal result. Our results open up a unique way to test intimate details of the nuclear structure by performing atomic (rather than nuclear) experiments and calculations.

Oks, E.

2001-06-01

69

Photoelectron spectroscopy of O{sup -} at 266 nm: Ratio of ground- and excited-state atomic oxygen production and channel-resolved photoelectron anisotropy parameters  

SciTech Connect

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

70

Selective-state charge transfer in a collision between a Li sup 3+ ion and a ground-state Li atom: A molecular-state approach (US)  

SciTech Connect

The semiclassical, impact-parameter method, based on a 15-state molecular-orbital expansion, is employed to calculate the cross sections for charge transfer in Li{sup 3+}-Li collisions. Electron-translation effects have been taken into account. In addition to total capture, cross sections for capture into individual states have also been calculated. The present results show qualitative agreement with the other available theory; details, however, are different. It is found that this reaction, through state-selective capture into the {ital n}=4 manifold of Li{sup 2+}, may provide a useful mechanism to achieve population inversion necessary for short-wavelength lasers.

Kumar, A.; Lane, N.F. (Department of Physics, Rice Quantum Institute, Rice University, Houston, Texas 77251 (USA)); Kimura, M. (Argonne National Laboratory, Argonne, Illinois 60439 (USA) Department of Physics, Rice Quantum Institute, Rice University, Houston, Texas 77251 (USA))

1991-01-01

71

Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density  

NASA Astrophysics Data System (ADS)

Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3 4S3/2) atom density is around 3 × 1014 cm-3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N (2p3 4S3/2) density is strongly affected by the N2O and O2 addition. Indeed, the density still increases exponentially with the energy dissipated in the gas but an increase in N2O and O2 amounts (a few hundreds of ppm) leads to a decrease in nitrogen atom density. No discrepancy in the order of magnitude of N (2p3 4S3/2) density is observed when comparing results obtained in N2/N2O and N2/O2 mixtures. Compared with pure nitrogen, for an energy of ˜90 mJ cm-3, the maximum of N (2p3 4S3/2) density drops by a factor of 3 when 100 ppm of N2O and O2 are added and it reduces by a factor of 5 for 200 ppm, to reach values close to our TALIF detection sensitivity for 400 ppm (1 × 1013 cm-3 at atmospheric pressure).

Es-sebbar, Et; Gherardi, N.; Massines, F.

2013-01-01

72

Photoabsorption profile and satellite features of the potassium 4s?4p transition perturbed by ground-state helium atoms  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

73

Ground-state spin logic  

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

74

An experimental and computational study of the reaction of ground-state sulfur atoms with carbon disulfide  

NASA Astrophysics Data System (ADS)

The pulsed laser photolysis/resonance fluorescence technique was used to study the reaction of S(3PJ) with CS2 in an Ar bath gas. Over 290-770 K pressure-dependent kinetics were observed and low- and high-pressure limiting rate constants were derived as k0 = (11.5-0.0133 T/K) × 10-31 cm6 molecule-2 s-1 (error limits +/- 20%) and k? = (2.2 +/- 0.6) × 10-12 cm3 molecule-1 s-1. Equilibration observed at 690-770 K yields a CS2-S bond dissociation enthalpy of 131.7 +/- 4.0 kJ mol-1 at 298 K. This agrees with computed thermochemistry for a spin-forbidden C2V adduct, estimated at the coupled-cluster single double triple level extrapolated to the infinite basis set limit. A pressure-independent pathway, assigned to abstraction, was observed from 690 to 1040 K and can be summarized as 1.14 × 10-10 exp(-37.0 kJ mol-1/RT) cm3 molecule-1 s-1 with error limits of +/- 40%. The results are rationalized in terms of a computed potential energy surface and transition state theory and Troe's unimolecular formalism.

Gao, Yide; Marshall, Paul

2011-10-01

75

Characterization of high-energy photoionization in terms of the singularities of the atomic potential. I. Photoionization of the ground state of a two-electron atom  

SciTech Connect

We describe single and double photoionization of two-electron atoms by photoabsorption at high incident photon energies {omega} (but still {omega}<

Suric, T. [R. Boskovic Institute, Zagreb, P.O. Box 180, Zagreb 10000 (Croatia); Drukarev, E.G. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300 (Russian Federation); Pratt, R.H. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2003-02-01

76

Tracing magnetic fields with ground state alignment  

NASA Astrophysics Data System (ADS)

Observational studies of magnetic fields are vital as magnetic fields play a crucial role in various astrophysical processes, including star formation, accretion of matter, transport processes (e.g. transport of heat), and cosmic rays. The existing ways of magnetic field studies have their limitations. Therefore, it is important to explore new effects that can bring information about magnetic field. We identified a process “ground state alignment” as a new way to determine the magnetic field direction in diffuse medium. 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 alignment is due to anisotropic radiation impinging on the atom/ion, while 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 (1G?B?10-15G). Compared to the upper level Hanle effect, atomic realignment is most suitable for the studies of magnetic field in the diffuse medium, where magnetic field is relatively weak. The corresponding physics of alignment is based on solid foundations of quantum electrodynamics and in a different physical regime the alignment has become a part of solar spectroscopy. In fact, the effects of atomic/ionic alignment, including the realignment in magnetic field, 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. It is very encouraging that 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%. A unique feature of the atomic realignment is that they can reveal the 3D orientation of magnetic field. In this paper, 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, including those in the early universe.

Yan, Huirong; Lazarian, A.

2012-08-01

77

Collective generation of quantum states of light by entangled atoms  

Microsoft Academic Search

We present a theoretical framework to describe the collective emission of light by entangled atomic states. Our theory applies to the low-excitation regime, where most of the atoms are initially in the ground state, and relies on a bosonic description of the atomic excitations. In this way, the problem of light emission by an ensemble of atoms can be solved

D. Porras; J. I. Cirac

2008-01-01

78

Ground-state Dirac monopole  

SciTech Connect

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

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

2011-12-15

79

Absolute rate data for reactions of ground-state atomic calcium, Ca(4s sup 2 sup 1 S sub 0 ), at elevated temperatures determined by time-resolved atomic resonance absorption spectroscopy  

SciTech Connect

This paper reports on reactions of ground-state atomic calcium, Ca(4s{sup 2}{sup 1}S{sub 0}), with a large number of collision partners investigated by direct spectroscopic measurement using atomic resonance absorption spectroscopy in the time-domain. Ca(4{sup 1}S{sub 0}) was generated by the pulsed irradiation of CaI{sub 2} vapor at elevated temperatures and monitored photoelectrically in the single-shot mode using the resonance transition at {lambda} = 422.7 nm Ca(4{sup 1}P{sub 1}) {l arrow} Ca(4{sup 1}S{sub 0}). Decay profiles in the presence of the gases CH{sub 3}Cl, C{sub 2}H{sub 5}Cl, CF{sub 3}Cl, CF{sub 3}Br, CF{sub 2}Cl{sub 2}, CH{sub 3}F, CF{sub 3}H, CR{sub 4}, SF{sub 6}, HCl, HBr, N{sub 2}O with excess helium buffer gas were captured in a transient recorder and transferred either directly to a microcomputer or mainly to an XY-recorder for subsequent kinetic analysis. The development of the present method was principally feasible because of the construction here of an extremely intense, high-current hollow cathode atomic resonance source for the calcium transition employed in the investigation. Although the kinetic measurements for the removal of Ca(4{sup 1}S{sub 0}) with H{sub 2}O showed consistent plots, these yielded a value of k{sub R}(T = 911 K) = (3.4 {plus minus} 0.2) {times} 10{sup {minus}12} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}, which is viewed with caution as it implies a bond dissociation energy of D(Ca-OH) of a magnitude at the extreme limits of the largest value reported from various analyses on calcium in premixed H{sub 2}-O{sub 2}-N{sub 2} flames.

Clay, R.S.; Husain, D. (Dept. of Chemistry, Univ. of Cambridge, Cambridge CB2 1 EW (GB))

1991-09-01

80

Chemical dynamics of the formation of the ethynylsilylidyne radical (SiCCH(X 2?)) in the crossed beam reaction of ground state silicon atoms (Si(3P)) with acetylene (C2H2(X 1?g+))  

NASA Astrophysics Data System (ADS)

The reaction dynamics of ground state silicon atoms (Si(3P)) with the acetylene molecule (C2H2(X 1?g+)) were investigated at a collision energy of 101.6+/-1.6 kJ mol-1 under single collision conditions in a crossed molecular beam machine. We found that the reaction dynamics proceeded via an addition of the silicon atom to the ?-electrons of the acetylene molecule at a single carbon atom forming a Cs symmetric SiC2H2(X 3A'') intermediate. The latter either emitted a hydrogen atom leading to the linear SiCCH(X 2?) product or underwent a hydrogen migration to the SiCCH2(X 3A2) isomer prior to the decomposition of the latter to SiCCH(X 2?) plus atomic hydrogen. The overall reaction to form the SiCCH(X 2?) plus atomic hydrogen products was determined to be highly endoergic by 84+/-6 kJ mol-1. No evidence of a molecular hydrogen elimination channel was found at this collision energy. Our study predicts that this endoergic neutral-neutral reaction can lead to the formation of an organosilicon transient species, i.e., the linear SiCCH(X 2?) radical, in high-temperature environments like in the circumstellar envelope of the carbon star IRC+10 216, where temperatures of a few 1000 K exist close to the central star.

Kaiser, R. I.; Gu, X.

2009-09-01

81

Spin domains in ground-state Bose-Einstein condensates  

Microsoft Academic Search

Bose-Einstein condensates - a low-temperature form of matter in which a macroscopic population of bosons occupies the quantum-mechanical ground state - have been demonstrated for weakly interacting, dilute gases of alkali-metal and hydrogen atoms. Magnetic traps are usually employed to confine the condensates, but have the drawback that spin flips in the atoms lead to untrapped states. For this reason,

J. Stenger; S. Inouye; D. M. Stamper-Kurn; H.-J. Miesner; A. P. Chikkatur; W. Ketterle

1998-01-01

82

Ground-state spaces of frustration-free Hamiltonians  

NASA Astrophysics Data System (ADS)

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 ?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 ?k, called atoms, are analogs of extreme points. We study the properties of atoms in ?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 ?2 are unique ground states of some 2-local frustration-free Hamiltonians. Moreover, we show that the elements in ?k may not be the join of atoms, indicating a richer structure for ?k beyond the convex structure. Our study of ?k deepens the understanding of ground-state space properties for frustration-free Hamiltonians, from the new perspective of reduced spaces.

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

2012-10-01

83

Coherent Transfer of Photoassociated Molecules into the Rovibrational Ground State  

SciTech Connect

We report on the direct conversion of laser-cooled {sup 41}K and {sup 87}Rb atoms into ultracold {sup 41}K{sup 87}Rb molecules in the rovibrational ground state via photoassociation followed by stimulated Raman adiabatic passage. High-resolution spectroscopy based on the coherent transfer revealed the hyperfine structure of weakly bound molecules in an unexplored region. Our results show that a rovibrationally pure sample of ultracold ground-state molecules is achieved via the all-optical association of laser-cooled atoms, opening possibilities to coherently manipulate a wide variety of molecules.

Aikawa, K.; Hayashi, M.; Oasa, K. [Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Akamatsu, D.; Kobayashi, J. [Institute of Engineering Innovation, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Naidon, P. [JST, ERATO, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Kishimoto, T. [Center for Frontier Science and Engineering, University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Ueda, M. [JST, ERATO, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Inouye, S. [Institute of Engineering Innovation, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); JST, ERATO, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

2010-11-12

84

Collision-Produced Atomic States.  

National Technical Information Service (NTIS)

The last 10-15 years have witnessed the development of a new, powerful class of experimental techniques for atomic collision studies, allowing partial or complete determination of the state of the atoms after a collision event, i.e. the full set of quantu...

N. Andersen

1988-01-01

85

Coherent manipulation of single atom qubits using Rydberg states  

NASA Astrophysics Data System (ADS)

This thesis presents experimental observations of the coherent manipulations of Rubidium-87 atoms via two photon excitations. Atoms are cooled using a magneto-optical trap (MOT) into two far off resonance traps (FORT) that are separated by 10 micrometers. State sensitive single atom detection is performed by gathering the fluorescence signal of two atoms trapped in the FORT potentials with an electron-multiplying CCD camera. A custom built multiplexing optical system is used to individually address the FORT potentials. A microwave modulated 780nm laser is used to coherently Rabi flop atoms between the F=1 and F=2 hyperfine ground states via two photon excitations. Cavity stabilized lasers at 780nm and 480nm are used to conduct two photon excitations of F=2 hyperfine ground state atoms to Rydberg states with principal quantum numbers ranging from n=43 to n=97. This experiment is the first to observe coherent Rabi oscillations at megahertz rates between ground and Rydberg levels. These coherent Rydberg Rabi oscillations are used to demonstrate Rydberg blockade at a single atom level for the first time. The Rydberg Rabi oscillations of a target atom are observed to be 75% blockaded by the presence of a Rydberg atom more than 10 micrometers away. This paper reports on the preliminary work towards the first neutral atom controlled-NOT (CNOT) gate, and on preliminary experiments working towards deterministic loading of single atoms in a FORT potential.

Urban, Erich

86

Atomic entangled states  

Microsoft Academic Search

Quantum communication holds a promise for absolutely secure transmission of secret messages and faithful transfer of unknown quantum states. Photonic channels appear to be very attractive for physical implementation of quantum communication. However, due to losses and decoherence in the channel, the communication fidelity decreases exponentially with the channel length. We describe a scheme that allows to implement robust quantum

L. M. Duan; M. Lukin; P. Zoller; J. I. Cirac

2002-01-01

87

Ground state properties and applications of dipolar ultracold gases  

Microsoft Academic Search

This thesis contains a study of ultracold paramagnetic atoms or polar molecules characterized by a long-range anisotropic dipolar interaction. We particularly focus on two aspects of ultracold dipolar gases. In the first problem the ground state properties of dipolar Bose-Einstein condensates (BEC) are investigated. This problem has gained importance due to recent experimental advances in achieving a condensate of Chromium

Omjyoti Dutta

2008-01-01

88

Unfrustrated qudit chains and their ground states  

SciTech Connect

We investigate chains of d-dimensional quantum spins (qudits) on a line with generic nearest-neighbor interactions without translational invariance. We find the conditions under which these systems are not frustrated, that is, when the ground states are also the common ground states of all the local terms in the Hamiltonians. The states of a quantum spin chain are naturally represented in the matrix product states (MPS) framework. Using imaginary time evolution in the MPS ansatz, we numerically investigate the range of parameters in which we expect the ground states to be highly entangled and find them hard to approximate using our MPS method.

Movassagh, Ramis; Shor, Peter W. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Farhi, Edward; Goldstone, Jeffrey [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Nagaj, Daniel [Research Center for Quantum Information, Institute of Physics, Slovak Academy of Sciences, Bratislava (Slovakia); Osborne, Tobias J. [Institute for Advanced Study, Wissenschaftskolleg zu Berlin, Berlin (Germany)

2010-07-15

89

On the Ground State of Metallic Hydrogen.  

National Technical Information Service (NTIS)

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) cann...

S. Chakravarty N. W. Ashcroft

1978-01-01

90

From Ground States to Local Hamiltonians  

Microsoft Academic Search

Traditional quantum physics solves ground states for a given Hamiltonian, while quantum information science asks for the existence and construction of certain Hamiltonians for given ground states. In practical situations, one would be mainly interested in local Hamiltonians with certain interaction patterns, such as nearest neighbour interactions on some type of lattices. We show that a necessary condition for a

Jianxin Chen; Zhengfeng Ji; Bei Zeng; Duanlu Zhou

2011-01-01

91

Ground-state entanglement in coupled qubits  

NASA Astrophysics Data System (ADS)

We study a system of qubits that are coupled to each other via only one degree of freedom, represented, e.g., by ?z operators. We prove that if, by changing the Hamiltonian parameters, a nondegenerate ground state of the system is continuously transformed in such a way that the expectation values of ?z operators of at least two coupled qubits change, this ground state is entangled. Using this proof, we discuss connection between energy level anticrossings and ground-state entanglement. Following the same line of thought, we introduce entanglement witnesses, based on cross susceptibilities, that can detect ground-state entanglement for any bipartition of the multiqubit system. A witness for global ground-state entanglement is also introduced.

Smirnov, A. Yu.; Amin, M. H.

2013-08-01

92

Ground-state stability and criticality of two-electron atoms with screened Coulomb potentials using the B-splines basis set  

NASA Astrophysics Data System (ADS)

We applied the finite-size scaling method using the B-splines basis set to construct the stability diagram for two-electron atoms with a screened Coulomb potential. The results of this method for two-electron atoms are very accurate in comparison with previous calculations based on Gaussian, Hylleraas and finite-element basis sets. The stability diagram for the screened two-electron atoms shows three distinct regions, i.e. a two-electron region, a one-electron region and a zero-electron region, which correspond to stable, ionized and double ionized atoms, respectively. In previous studies, it was difficult to extend the finite-size scaling calculations to large molecules and extended systems because of the computational cost and the lack of a simple way to increase the number of Gaussian basis elements in a systematic way. Motivated by recent studies showing how one can use B-splines to solve Hartree-Fock and Kohn-Sham equations, this combined finite-size scaling using the B-splines basis set might provide an effective systematic way to treat criticality of large molecules and extended systems. As benchmark calculations, the two-electron systems show the feasibility of this combined approach and provide an accurate reference for comparison.

Serra, Pablo; Kais, Sabre

2012-12-01

93

Ground-based laboratory atomic oxygen calibration experiments  

Microsoft Academic Search

Existing devices and analysis techniques for the monitoring of space and laboratory simulated Atomic Oxygen (AO) environments have been investigated and improved to enable more accurate and reliable measurement and calibration of AO flux and fluences than previously possible. This research was based on experimental work carried out in a ground based AO facility designed to simulate the low Earth

Jeremy Stephen Matcham

1998-01-01

94

Scheme for the generation of entangled atomic state in cavity QED  

Microsoft Academic Search

We propose a scheme to generate the entangled state of two Lambda -type three-level atoms trapped in a cavity. The atoms are initially prepared in their excited state and the cavity in vacuum state. Each atom has two possibilities to deexcite to one of the ground states. If two different polarized photons are detected subsequently, it is sure that both

Z.-L. Duan; Z.-Y. Chen; J.-T. Zhang; X.-L. Feng; Z.-Z. Xu

2004-01-01

95

Scheme for the generation of entangled atomic state in cavity QED  

Microsoft Academic Search

We propose a scheme to generate the entangled state of two $\\\\Lambda $ -type three-level atoms trapped in a cavity. The atoms are initially prepared in their excited state and the cavity in vacuum state. Each atom has two possibilities to deexcite to one of the ground states. If two different polarized photons are detected subsequently, it is sure that

Z.-L. Duan; Z.-Y. Chen; J.-T. Zhang; X.-L. Feng; Z.-Z. Xu

2004-01-01

96

Atomic quantum state teleportation and swapping.  

PubMed

A set of protocols for atoms-photons and atoms-atoms quantum state teleportation and swapping utilizing Einstein-Podolsky-Rosen light is proposed. The protocols work for polarization quantum states of multiphoton light pulses and macroscopic samples of atoms, i.e., for continuous quantum variables. A simple free space interaction of polarized light with a spin polarized atomic ensemble is shown to suffice for these protocols. Feasibility of experimental realization using gas samples of atoms is analyzed. PMID:11136066

Kuzmich, A; Polzik, E S

2000-12-25

97

Electronic Structure and Ground State Properties of Ozone Molecule  

Microsoft Academic Search

The ground-state properties of ozone, including its geometry, energy for dissociation into oxygen molecule and oxygen atom and ^17O nuclear quadrupole interaction tensors are being studied by the Hartree-Fock Roothaan procedure together with many-body effects incorporated by both many-body perturbation theory and configuration interaction procedures. Careful examination is being made of the convergence with respect to the sizes of variational

Shekhar Gurung; M. M. Aryal; D. D. Paudyal; B. Dhakal; R. H. Scheicher; Junho Jeong; T. P. Das

2003-01-01

98

From ground states to local Hamiltonians  

NASA Astrophysics Data System (ADS)

Traditional quantum physics solves ground states for a given Hamiltonian, while quantum information science asks for the existence and construction of certain Hamiltonians for given ground states. In practical situations, one would be mainly interested in local Hamiltonians with certain interaction patterns, such as nearest-neighbor interactions on some types of lattices. A necessary condition for a space V to be the ground-state space of some local Hamiltonian with a given interaction pattern is that the maximally mixed state supported on V is uniquely determined by its reduced density matrices associated with the given pattern, based on the principle of maximum entropy. However, it is unclear whether this condition is in general also sufficient. We examine the situations for the existence of such a local Hamiltonian to have V satisfying the necessary condition mentioned above as its ground-state space by linking to faces of the convex body of the local reduced states. We further discuss some methods for constructing the corresponding local Hamiltonians with given interaction patterns, mainly from physical points of view, including constructions related to perturbation methods, local frustration-free Hamiltonians, as well as thermodynamical ensembles.

Chen, Jianxin; Ji, Zhengfeng; Zeng, Bei; Zhou, D. L.

2012-08-01

99

Collinear laser spectroscopy on the ground state and an excited state in neutral 55Mn  

NASA Astrophysics Data System (ADS)

Collinear laser spectroscopy was performed on an atomic beam of stable 55Mn. An ion beam of 55Mn+ was generated in an ion source, accelerated to 15 keV, and neutralized via charge-exchange reactions with a Na vapor. A long-lived metastable state of Mn i, near-resonantly populated in the charge-exchange process, was investigated via laser probing in addition to a laser excitation from the ground state in Mn i. The relative population of the Mn i metastable state compared to that of the ground state was found to be 0.7±0.3. A theoretical calculation, which included feeding to the ground state and the metastable state from higher-energy excited electronic states populated in the charge-exchange process, agreed with the present result. The deduced A and B hyperfine coupling constants agreed with literature values, where available.

Klose, A.; Minamisono, K.; Mantica, P. F.

2013-10-01

100

Atomic Quantum State Teleportation and Swapping  

Microsoft Academic Search

A set of protocols for atoms-photons and atoms-atoms quantum state teleportation and swapping utilizing Einstein-Podolsky-Rosen light is proposed. The protocols work for polarization quantum states of multiphoton light pulses and macroscopic samples of atoms, i.e., for continuous quantum variables. A simple free space interaction of polarized light with a spin polarized atomic ensemble is shown to suffice for these protocols.

A. Kuzmich; E. S. Polzik

2000-01-01

101

Ground state number fluctuations of trapped particles  

NASA Astrophysics Data System (ADS)

This thesis encompasses a number of problems related to the number fluctuations from the ground state of ideal particles in different statistical ensembles. In the microcanonical ensemble most of these problems may be solved using number theory. Given an energy E, the well-known problem of finding the number of ways of distributing N bosons over the excited levels of a one-dimensional harmonic spectrum, for instance, is equivalent to the number of restricted partitions of E. As a result, the number fluctuation from the ground state in the microcanonical ensemble for this system may be found analytically. When the particles are fermions instead of bosons, however, it is difficult to calculate the exact ground state number fluctuation because the fermionic ground state consists of many levels. By breaking up the energy spectrum into particle and hole sectors, and mapping the problem onto the classic number partitioning theory, we formulate a method of calculating the particle number fluctuation from the ground state in the microcanonical ensemble for fermions. The same quantity is calculated for particles interacting via an inverse-square pairwise interaction in one dimension. In the canonical ensemble, an analytical formula for the ground state number fluctuation is obtained by using the mapping of this system onto a system of noninteracting particles obeying the Haldane-Wu exclusion statistics. In the microcanonical ensemble, however, the result can be obtained only for a limited set of values of the interacting strength parameter. Usually, for a discrete set of a mean-field single-particle quantum spectrum and in the microcanonical ensemble, there are many combinations of exciting particles from the ground state. The spectrum given by the logarithms of the prime number sequence, however, is a counterexample to this rule. Here, as a consequence of the fundamental theorem of arithmetic, there is a one-to-one correspondence between the microstate and the macrostate, resulting in the vanishing of number fluctuation for all excitations. The use of the canonical or grand canonical ensembles, on the other hand, gives a substantial number fluctuation from the ground state. For a related spectrum, that given by the logarithms of an integer n, the microcanonical number fluctuation is non-zero but the application of the other ensembles is still not valid. These two spectra are examples of systems where canonical and grand canonical ensembles averagings yield answers different from the microcanonical result. (Abstract shortened by UMI.)

Tran, Muoi N.

102

Macroscopic Atom-Molecule Dark State and Its Collective Excitations in Fermionic Systems  

SciTech Connect

We show that a robust macroscopic atom-molecule dark state can exist in fermionic systems, which represents a coherent superposition between the ground molecular Bose-Einstein condensates and the atomic BCS paired state. We take advantage of the tunability offered by external laser fields, and explore this superposition for demonstrating coherent oscillations between ground molecules and atom pairs. We interpret the oscillation frequencies in terms of the collective excitations of the dark state.

Robertson, Andrew; Ling, Hong Y. [Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey, 08028-1700 (United States); Jiang Lei; Pu Han [Department of Physics and Astronomy, and Rice Quantum Institute, Rice University, Houston, Texas 77251-1892 (United States); Zhang Weiping [State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China)

2007-12-21

103

Coherent excitation of a single atom to a Rydberg state  

SciTech Connect

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

104

Ground State of High-Density Matter.  

National Technical Information Service (NTIS)

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...

E. Copeland E. W. Kolb K. Lee

1988-01-01

105

Possible nature of ground state of HTSC  

NASA Astrophysics Data System (ADS)

A qualitative model describing the ground state and the mechanism of superconducting pairing in Cu- and Fe-based high-temperature superconductors (HTSCs) is suggested. In this model, doping by localized charges is supposed to be responsible for the closing of the gap between the occupied anionic band and unoccupied states of the cation band and for the formation of the electron-excitonic band of unusual nature.

Mitsen, K. V.; Ivanenko, O. M.

2012-12-01

106

The Ground State of the Bose Gas  

Microsoft Academic Search

Now that the low temperature properties of quantum-mechanical many-body\\u000asystems (bosons) at low density, $\\\\rho$, can be examined experimentally it is\\u000aappropriate to revisit some of the formulas deduced by many authors 4-5 decades\\u000aago. For systems with repulsive (i.e. positive) interaction potentials the\\u000aexperimental low temperature state and the ground state are effectively\\u000asynonymous -- and this fact is

Elliott H. Lieb; Robert Seiringer; Jan Philip Solovej; Jakob Yngvason

2002-01-01

107

State of atoms and interatomic interactions in complex perovskite-like oxides: I. State of manganese atoms in LaSrMnâAlâ-âOâ solid solutions  

Microsoft Academic Search

Study of the temperature and concentration dependences of the magnetic properties of solid solutions of layered oxides containing manganese and aluminum atoms in similar crystallographic positions revealed a change in the ground state of part of the manganese atoms. Such an effect was previously observed for iron, cobalt, and nickel atoms in similar solid solutions. In the case of manganese,

N. P. Bobrysheva; N. V. Chezhina

1994-01-01

108

Optical Atomic Clocks for Ground and Space Applications  

NASA Astrophysics Data System (ADS)

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

Riehle, Fritz

109

State-selective imaging of cold atoms  

Microsoft Academic Search

Atomic coherence phenomena are usually investigated using single beam techniques without spatial resolution. Here we demonstrate state-selective imaging of cold R85b atoms in a three-level ladder system, where the atomic refractive index is sensitive to the quantum coherence state of the atoms. We use a phase-sensitive diffraction contrast imaging (DCI) technique which depends on the complex refractive index of the

David V. Sheludko; Simon C. Bell; Russell Anderson; Christoph S. Hofmann; Edgar J. D. Vredenbregt; Robert E. Scholten

2008-01-01

110

Teleportation of atomic states via position measurements  

SciTech Connect

We present a scheme for conditionally teleporting an unknown atomic state in cavity QED, which requires two atoms and one cavity mode. The translational degrees of freedom of the atoms are taken into account using the optical Stern-Gerlach model. We show that successful teleportation with probability 1/2 can be achieved through local measurements of the cavity photon number and atomic positions. Neither direct projection onto highly entangled states nor holonomous interaction-time constraints are required.

Tumminello, Michele [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, I-90128 Palermo (Italy); Ciccarello, Francesco [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, I-90128 Palermo (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Unita di Palermo (Italy); NEST and Dipartimento di Scienze Fisiche ed Astronomiche, Universita di Palermo, Via Archirafi 36, I-90123 Palermo (Italy)

2008-02-15

111

Creation of a six-atom `Schrödinger cat' state  

NASA Astrophysics Data System (ADS)

Among the classes of highly entangled states of multiple quantum systems, the so-called `Schrödinger cat' states are particularly useful. Cat states are equal superpositions of two maximally different quantum states. They are a fundamental resource in fault-tolerant quantum computing and quantum communication, where they can enable protocols such as open-destination teleportation and secret sharing. They play a role in fundamental tests of quantum mechanics and enable improved signal-to-noise ratios in interferometry. Cat states are very sensitive to decoherence, and as a result their preparation is challenging and can serve as a demonstration of good quantum control. Here we report the creation of cat states of up to six atomic qubits. Each qubit's state space is defined by two hyperfine ground states of a beryllium ion; the cat state corresponds to an entangled equal superposition of all the atoms in one hyperfine state and all atoms in the other hyperfine state. In our experiments, the cat states are prepared in a three-step process, irrespective of the number of entangled atoms. Together with entangled states of a different class created in Innsbruck, this work represents the current state-of-the-art for large entangled states in any qubit system.

Leibfried, D.; Knill, E.; Seidelin, S.; Britton, J.; Blakestad, R. B.; Chiaverini, J.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Langer, C.; Ozeri, R.; Reichle, R.; Wineland, D. J.

2005-12-01

112

Graphical probabilistic inference for ground state and near-ground state computing in QCA circuits  

Microsoft Academic Search

We propose a graphical probabilistic Bayesian Network based modeling and inference scheme for Clocked Quantum-dot Cellar Automata (QCA) based circuit design that not only specify just the binary discrete states (0 or 1) of the individual cells, but also the probabilities of observing these states for Ground (Most Likely) state computing. The nodes of the Bayesian Network (BN) are the

Sanjukta Bhanja; S. Sarkar

2005-01-01

113

Ground-state energy of nuclear matter  

NASA Astrophysics Data System (ADS)

The low-density expansion of the ground-state energy for spin-dependent forces is given, through order k6F for the ladder approximation and through order k6FlnkF for the complete energy, in terms of derivatives with respect to the strength of the attractive part of the interaction defined by the Baker-Hind-Kahane potential. The ladder approximation is also computed by the numerical solution of the K-matrix equation. The resulting series gives a satisfactory representation of the energy at interesting densities. Using Padé extrapolation techniques, both in the density and in the attractive part of the interaction, we obtain the ground-state energy of nuclear matter.

Baker, George A., Jr.; Benofy, L. P.; Fortes, Mauricio

1988-07-01

114

Ground state properties of nuclear matter  

Microsoft Academic Search

The ground state properties of nuclear matter are calculated in the?11-approximation1. A nucleon-nucleon interaction of the Yamaguchi-type and thes-wave part ofTabakin's potential have been considered. In both cases too large values for the density of nuclear matter and the binding energy per nucleon are found. The momentum distribution turns out to be very small for momenta larger than the Fermi

G. Wegmann

1968-01-01

115

Configuration interaction benchmark for Be ground state  

Microsoft Academic Search

A set of 432 energy-optimized Slater-type radial orbitals together with spherical harmonics up to ? = 30 is used to approximate\\u000a the corresponding full configuration interaction (CI) expansion for Be ground state. An analysis of radial and angular patterns\\u000a of convergence for the energy yields a basis set incompleteness error of 8.7 ?hartree of which 85% comes from radial basis\\u000a truncations for ? ? 30.

Carlos F. Bunge

2010-01-01

116

Ground State Fidelity from Tensor Network Representations  

Microsoft Academic Search

For any D-dimensional quantum lattice system, the fidelity between two ground state many-body wave functions is mapped onto the partition function of a D-dimensional classical statistical vertex lattice model with the same lattice geometry. The fidelity per lattice site, analogous to the free energy per site, is well defined in the thermodynamic limit and can be used to characterize the

Huan-Qiang Zhou; Roman Orús; Guifre Vidal

2008-01-01

117

Ground-State Energetics of Spin-Aligned Deuterium  

NASA Astrophysics Data System (ADS)

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

Panoff, Robert Michael

118

Formation of Ultracold Ground-State RbCs via Photoassociated 1^1? State  

NASA Astrophysics Data System (ADS)

Two electronic states, 1^1? and 2^1^+, of the Rb(5s) + Cs(6p) atomic asymptote can be used to directly populate the RbCs ground state X^1^+ at short range following heteronuclear photoassociation of laser-cooled Rb and Cs atoms. Our Franck-Condon factor calculation shows that the 1^1? state (dissociating to the Rb(5s) + Cs(6p3/2) asymptote) is more favorable than the 2^1^+ state (dissociating to the Rb(5s) + Cs(6p1/2) atomic limit) for forming ultracold ground-state RbCs in low vibrational levels (v < 20), which can be further efficiently transferred to the v = 0, J = 0 lowest quantum state of the molecule through a simple one-photon optical pumping process. Experimentally we have observed ultracold RbCs molecules in a Rb-Cs dual MOT by two-photon ionization and time-of-flight mass spectroscopy. Efforts are underway on heteronuclear photoassociation to the 1^1? state (? = 1 state at long range) and formation of ultracold RbCs in the singlet ground X^1^+ state. In this paper we present our Franck-Condon calculation on the transition scheme of using photoassociated 1^1? rovibrational levels to make ground state RbCs and report our experimental results and progress in heteronuclear photoassociation, detection and trapping of ultracold RbCs molecules. This work was supported under The Aerospace Corporations's Independent Research and Development Program.

Wang, H.

2005-03-01

119

Ground State Structure of Supersymmetric Yang - Theory.  

NASA Astrophysics Data System (ADS)

In this thesis we will develop a new technique to determine whether super-symmetry is dynamically broken in supersymmetric Yang-Mills theory. This problem requires a nonperturbative approach. The presence of supersymmetry endows a quantum field theory with several properties which we can exploit to gain nonperturbative information about the theory. We begin by examining five examples of previous attempts to solve this problem. In these examples, the features of supersymmetric theories are exploited in different ways to determine the ground state structure of the theory and to reveal whether supersymmetry is dynamically broken. These examples are (1) an exact solution for the ground state of supersymmetric quantum mechanics, (2) the computation of the Witten Index, (3) an effective Lagrangian calculation based on a nonanomalous symmetry, (4) the calculation of condensates in an instanton background, and (5) a reconsideration of the first example by a method which can reveal whether supersymmetry is broken without actually solving for the ground state. In our method, the Witten Index computation is refined by incorporating the techniques of the fifth example. Several of the assumptions (the validity of which we question) employed in Witten's computation of the value of the Index are removed. We observe that it is possible to remove yet more assumptions and obtain better information about the ground state of the quantum field theory under examination. We may either use supersymmetry to catapult an essentially perturbative analysis into a nonperturbative one, or as we will argue, we could start with a nonperturbative analysis from the start. The features of supersymmetric theories which permit us to be so bold are: a positive -semidefinite Hamiltonian, the equivalence of zero energy states and supersymmetry invariant states, the pairing of bosonic and fermionic states of energy greater than zero, new symmetries which may be combined to cancel anomalies, the suppression of quantum corrections to the superpotential (the nonrenormalization theorem), the cancelation of determinants in the path integral between vectors, fermions, and ghosts, additional Ward identities on the Green functions, and constraints on the transformation properties of composite operators.

Razzaghe-Ashrafi, Babak

120

Recoil-Induced-Resonances in Nonlinear, Ground-State, Pump-Probe Spectroscopy.  

National Technical Information Service (NTIS)

A theory of pump-probe spectroscopy is developed in which optical fields drive two-photon Raman transitions between ground states of an ensemble of three-level atoms. Effects related to the recoil the atoms undergo as a result of their interactions with t...

C. P. Search P. R. Berman

2001-01-01

121

Atomic Coherent States in Quantum Optics  

Microsoft Academic Search

For the description of an assembly of two-level atoms, atomic coherent states can be defined which have properties analogous to those of the field coherent states. The analogy is not fortuitous, but is shown to be related to the group contraction of exponential operators based on the angular momentum algebra to exponential operators based on the harmonic-oscillator algebra. The derivation

F. T. Arecchi; Eric Courtens; Robert Gilmore; Harry Thomas

1972-01-01

122

Condensed ground states of frustrated Bose-Hubbard models  

NASA Astrophysics Data System (ADS)

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

Möller, G.; Cooper, N. R.

2010-12-01

123

Best Possible Strategy for Finding Ground States  

SciTech Connect

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

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

2001-06-04

124

Ground state fidelity from tensor network representations.  

PubMed

For any D-dimensional quantum lattice system, the fidelity between two ground state many-body wave functions is mapped onto the partition function of a D-dimensional classical statistical vertex lattice model with the same lattice geometry. The fidelity per lattice site, analogous to the free energy per site, is well defined in the thermodynamic limit and can be used to characterize the phase diagram of the model. We explain how to compute the fidelity per site in the context of tensor network algorithms, and demonstrate the approach by analyzing the two-dimensional quantum Ising model with transverse and parallel magnetic fields. PMID:18352611

Zhou, Huan-Qiang; Orús, Roman; Vidal, Guifre

2008-02-28

125

Interactions Between Thermal Ground or Excited Atoms in the Vapor Phase: Many-Body Dipole–Dipole Effects, Molecular Dissociation, and Photoassociation Probed By Laser Spectroscopy  

Microsoft Academic Search

Atom–atom and atom–molecule interactions in the absence or presence of an optical radiation field are among the fundamental processes in atomic, molecular, and optical physics. This review addresses recent advances that provide insight into the dynamics of many-body fipole–dipole interactions between excited atoms at long range, and the production of a transient molecule from a pair of thermal, ground state

J. G. Eden; B. J. Ricconi; Y. Xiao; F. Shen; A. A. Senin

2008-01-01

126

Spontaneous skyrmion ground states in magnetic metals.  

PubMed

Since the 1950s, Heisenberg and others have addressed the problem of how to explain the appearance of countable particles in continuous fields. Stable localized field configurations were searched for an ingredient for a general field theory of elementary particles, but the majority of nonlinear field models were unable to predict them. As an exception, Skyrme succeeded in describing nuclear particles as localized states, so-called 'skyrmions'. Skyrmions are a characteristic of nonlinear continuum models ranging from microscopic to cosmological scales. Skyrmionic states have been found under non-equilibrium conditions, or when stabilized by external fields or the proliferation of topological defects. Examples are Turing patterns in classical liquids, spin textures in quantum Hall magnets, or the blue phases in liquid crystals. However, it has generally been assumed that skyrmions cannot form spontaneous ground states, such as ferromagnetic or antiferromagnetic order, in magnetic materials. Here, we show theoretically that this assumption is wrong and that skyrmion textures may form spontaneously in condensed-matter systems with chiral interactions without the assistance of external fields or the proliferation of defects. We show this within a phenomenological continuum model based on a few material-specific parameters that can be determined experimentally. Our model has a condition not considered before: we allow for softened amplitude variations of the magnetization, characteristic of, for instance, metallic magnets. Our model implies that spontaneous skyrmion lattice ground states may exist generally in a large number of materials, notably at surfaces and in thin films, as well as in bulk compounds, where a lack of space inversion symmetry leads to chiral interactions. PMID:16915285

Rössler, U K; Bogdanov, A N; Pfleiderer, C

2006-08-17

127

Spontaneous skyrmion ground states in magnetic metals  

NASA Astrophysics Data System (ADS)

Since the 1950s, Heisenberg and others have addressed the problem of how to explain the appearance of countable particles in continuous fields. Stable localized field configurations were searched for an ingredient for a general field theory of elementary particles, but the majority of nonlinear field models were unable to predict them. As an exception, Skyrme succeeded in describing nuclear particles as localized states, so-called `skyrmions'. Skyrmions are a characteristic of nonlinear continuum models ranging from microscopic to cosmological scales. Skyrmionic states have been found under non-equilibrium conditions, or when stabilized by external fields or the proliferation of topological defects. Examples are Turing patterns in classical liquids, spin textures in quantum Hall magnets, or the blue phases in liquid crystals. However, it has generally been assumed that skyrmions cannot form spontaneous ground states, such as ferromagnetic or antiferromagnetic order, in magnetic materials. Here, we show theoretically that this assumption is wrong and that skyrmion textures may form spontaneously in condensed-matter systems with chiral interactions without the assistance of external fields or the proliferation of defects. We show this within a phenomenological continuum model based on a few material-specific parameters that can be determined experimentally. Our model has a condition not considered before: we allow for softened amplitude variations of the magnetization, characteristic of, for instance, metallic magnets. Our model implies that spontaneous skyrmion lattice ground states may exist generally in a large number of materials, notably at surfaces and in thin films, as well as in bulk compounds, where a lack of space inversion symmetry leads to chiral interactions.

Rößler, U. K.; Bogdanov, A. N.; Pfleiderer, C.

2006-08-01

128

Rayleigh scattering from excited states of atoms and ions  

SciTech Connect

Elastic photon scattering from the ground state and various excited states of carbon atoms and ions has been investigated, using the S-matrix formalism, for incident photon energies ranging from 100 eV to 10 keV, contrasting the results obtained for different configurations. The excited states considered include hollow-atom states, where one or more inner shells are completely vacated. Ionic cases are considered as a limit of excitation. Results demonstrate how cross sections for different excited states group together according to shared properties of the configurations, such as the number of K electrons. Cross sections may exhibit deep dips below the K edge, depending on the occupation of the subshells corresponding to the strongest transitions. Scattering from excited states can have significantly larger cross sections than scattering from the ground state, particularly just below the K resonance region, and therefore it needs to be considered in situations where there is a large population of these excited states. Results are interpreted in terms of form-factor arguments and the qualitative behavior of individual subshell amplitudes. The angular dependence of cross sections can be understood in terms of angle-dependent form factors and anomalous scattering factors, taken to be angle independent. Cases are identified for which excited-state total integrated cross sections are much larger than the corresponding cross sections for scattering from the ground state. Our main results use an averaging over magnetic substates at the level of the amplitude, exact only for fully filled subshells, but generally appropriate for the carbon case considered, which simplifies the discussion and explains most of the general features. We also present results for a hollow lithium atom with and without this approximation to illustrate the differences that can arise in certain circumstances. (c) 2000 The American Physical Society.

Carney, J. P. J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Pratt, R. H. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Kissel, Lynn [Physics and Space Technology, Lawrence Livermore National Laboratory, Livermore, California 94551-0808 (United States); Roy, S. C. [Department of Physics, Bose Institute, Calcutta 700009, West Bengal, (India); Sen Gupta, S. K. [University Science Instrumentation Centre, North Bengal University, Darjeeling 734430, (India)

2000-05-01

129

Nonlinear ground-state pump-probe spectroscopy in ultracold rubidium: Raman-coupled dressed state spectroscopy  

Microsoft Academic Search

We present our experimental investigations of nonlinear ground-state pump-probe spectroscopy in ultracold rubidium 85 produced in a magneto-optical trap (MOT). Nonlinear ground-state pump-probe spectroscopy is a two-photon analog of traditional two-level pump-probe spectroscopy. When a two-level atom is driven with an intense, single frequency near-resonant laser field the absorption spectrum of a weak probe field exhibits absorption and gain features

Arthur K. Mills

2007-01-01

130

Ground States of Silicon-Multisubstituted Fullerene: First-Principles Calculations and Monte Carlo Simulations  

NASA Astrophysics Data System (ADS)

We present a systematical study on the possible stable structures of C60?xSix(x = 1?12) fullerenes using first-principles calculations combined with Monte-Carlo simulations. The initial fullerenes randomly substituting with silicon atoms are firstly generated and then their total energies are calculated quickly. The ground-state structures are found by the annealing process where Si atoms exchange their positions with C atoms. The stable structures are finally obtained through first-principles calculations with high precision. For the cases with a small amount of Si atoms (x<=4), results similar to those report previously are achieved. Some new stable Si-doped fullerenes with more Si atoms are also predicated. The results show that Si atoms in the C60?xSix(x<=4) fullerenes have a trend of segregation with C atoms. The minimum-energy structure changes from a chemical unstable state to a chemical stable state when x>=8.

Fan, Bing-Bing; Shi, Chun-Yan; Zhang, Rui; Jia, Yu

2013-10-01

131

Spin-1 bosons with coupled ground states in optical lattices  

SciTech Connect

The superfluid-Mott-insulator phase transition of ultracold spin-1 bosons with ferromagnetic and antiferromagnetic interactions in an optical lattice is theoretically investigated. Two counterpropagating linearly polarized laser beams with the angle {theta} between the polarization vectors (lin-{theta}-lin configuration), driving an F{sub g}=1 to F{sub e}=1 internal atomic transition, create the optical lattice and at the same time couple atomic ground states with magnetic quantum numbers m={+-}1. Due to the coupling the system can be described as a two-component one. At {theta}=0 the system has a continuous isospin symmetry, which can be spontaneously broken, thereby fixing the number of particles in the atomic components. The phase diagram of the system and the spectrum of collective excitations, which are density waves and isospin waves, are worked out. In the case of ferromagnetic interactions, the superfluid-Mott-insulator phase transition is always second order, but in the case of antiferromagnetic interactions for some values of system parameters it is first order and the superfluid and Mott phases can coexist. Varying the angle {theta} one can control the populations of atomic components and continuously turn on and tune their asymmetry.

Krutitsky, K.V.; Graham, R. [Fachbereich Physik der Universitaet Duisburg-Essen, Campus Essen, Universitaetsstr. 5, D-45117 Essen (Germany)

2004-12-01

132

First studies of state selective electron capture from atomic hydrogen by state prepared doubly charged ions  

Microsoft Academic Search

Electron Capture by multiply charged ions in atomic hydrogen and nitrogen is an important process in planetary atmospheres and in many astrophysical and technological plasmas. Excited state formation and decay results in photon emission in the optical, UV, and X-ray regions. In these studies doubly charged ions of carbon or nitrogen and oxygen have been prepared in either ground or

D. R. Gillen; D. M. Kearns; D. Voulot; R. W. McCullough; H. B. Gilbody

2001-01-01

133

Schroedinger cat states and multilevel atoms  

SciTech Connect

We demonstrate that the generalization of the two-level Jaynes-Cummings model (JCM) to an N-level atom leads to the creation of up to N macroscopically distinct field states. These field states are Schmidt-orthogonalized superpositions of Fock states. They correspond to macroscopic states of the field, attainable with large mean photon numbers. Unlike the situation with a two-level atom and a coherent-state field, which evolves into a macroscopic coherent superposition state (a Schrodinger cat), we find that when the additional levels participate strongly in the excitation (e.g all transitions are resonant with equal dipole moments) then the system does not evolve into a pure state. We will present some examples of special cases, giving insight into the behavior of three-level atoms and the two-level two-photon JCM.

Shore, B.W. [Lawrence Livermore National Laboratory, CA (United States); Knight, P.L. [Imperial College, London (United Kingdom)

1993-05-01

134

Teleportation of an atomic momentum state  

SciTech Connect

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

135

Quantum States of Atoms and Molecules  

NSDL National Science Digital Library

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

136

Control of resonant interaction between electronic ground and excited states.  

PubMed

We observe magnetic Feshbach resonances in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly occupied sites of an atomic Mott-insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a magnetic field of about 1.1 G for the energetically lowest magnetic sublevel of 170Yb, as well as around 360 mG for the energetically highest magnetic sublevel of 174Yb. The observed Feshbach resonance can only be induced by an anisotropic interatomic interaction. This scheme will open the door to a variety of studies using two-electron atoms with tunable interaction. PMID:23679722

Kato, Shinya; Sugawa, Seiji; Shibata, Kosuke; Yamamoto, Ryuta; Takahashi, Yoshiro

2013-04-23

137

Control of Resonant Interaction between Electronic Ground and Excited States  

NASA Astrophysics Data System (ADS)

We observe magnetic Feshbach resonances in a collision between the ground and metastable states of two-electron atoms of ytterbium (Yb). We measure the on-site interaction of doubly occupied sites of an atomic Mott-insulator state in a three-dimensional optical lattice as a collisional frequency shift in a high-resolution laser spectroscopy. The observed spectra are well fitted by a simple theoretical formula, in which two particles with an s-wave contact interaction are confined in a harmonic trap. This analysis reveals a wide variation of the interaction with a resonance behavior around a magnetic field of about 1.1 G for the energetically lowest magnetic sublevel of Yb170, as well as around 360 mG for the energetically highest magnetic sublevel of Yb174. The observed Feshbach resonance can only be induced by an anisotropic interatomic interaction. This scheme will open the door to a variety of studies using two-electron atoms with tunable interaction.

Kato, Shinya; Sugawa, Seiji; Shibata, Kosuke; Yamamoto, Ryuta; Takahashi, Yoshiro

2013-04-01

138

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

139

Spin systems with dimerized ground states  

NASA Astrophysics Data System (ADS)

In view of the numerous examples in the literature I attempt to outline a theory of Heisenberg spin systems possessing dimerized ground states ('DGS systems') which comprises all known examples. Whereas classical DGS systems can be completely characterized, it was only possible to provide necessary or sufficient conditions for the quantum case. First, for all DGS systems the interaction between the dimers must be balanced in a certain sense. Moreover, one can identify four special classes of DGS systems: (i) uniform pyramids, (ii) systems close to isolated dimer systems, (iii) classical DGS systems, and (iv), in the case of s = 1/2, systems of two dimers satisfying four inequalities. Geometrically, the set of all DGS systems may be visualized as a convex cone in the linear space of all exchange constants. Hence one can generate new examples of DGS systems by positive linear combinations of examples from the above four classes.

Schmidt, Heinz-Jürgen

2005-03-01

140

Probing the ground state in gauge theories  

SciTech Connect

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

141

Ground-based investigations of atomic oxygen interactions with space station surfaces  

SciTech Connect

High strength to weight ratio fiber organic epoxy materials are primary candidates as structural members for Space Station construction but preliminary STS exposure experiments have shown that many of these materials experience extensive etching by oxygen atoms present in low earth orbit (LEO). Oxygen atoms colliding with ram directed surfaces have energies of 5 eV (due to 8 km/s orbital velocity) and produce etching rates of 0.1 micron/orbit, i.e., 10% of the incoming O-atom flux reacts with organic based surfaces causing surface recession; while ram surface reflected O-atoms (thermal), react with rates 3 to 4 times lower. In order to investigate this problem ground-based simulation and testing facilities have been developed which include a high kinetic energy O-atom source, a sample exposure chamber and a high sensitivity molecular beam apparatus. The sample exposure chamber is suited for surveying materials for their O-atom reactivity through weight loss measurements. The high sensitivity molecular beam apparatus will be used for determining reaction mechanisms through measurements of reaction product identity, translational and internal state of products, and angular distribution of reaction products. The O-atom source, based on the use of a laser sustained discharge, has demonstrated O-atom translational temperatures of 8 to 9000 K and is presently operating with 50% oxygen in argon using 500 watts of CO/sub 2/ laser power which is expected to produce velocities of 4 to 5 km/s. One hour exposures of kapton, two types of fiber glass epoxy materials, and MgF/sub 2/ coated optics have been accomplished and preliminary results indicate that the coated aluminium optics have very low reaction rates while kapton has the highest rate.

Cross, J.B.; Cremers, D.A.; Tucker, D.F.

1985-01-01

142

Toward Trapped Ultracold RbCs Molecules in the Absolute Ground State  

NASA Astrophysics Data System (ADS)

We report on an improved apparatus for production of ultracold, optically trapped RbCs molecules, aiming to achieve an ultracold sample of polar molecules in the rovibrational ground state. Starting with a spin-polarized sample of Rb and Cs atoms, molecules are formed by photoassociation and decay into high vibrational levels of the triplet ground state. We plan to transfer these molecules to the absolute ground state via an electronically excited state of mixed singlet and triplet character, as previously demonstrated in our lab with pulsed lasers. Currently, we are working on high resolution spectroscopy of this state using cw diode lasers, to identify a suitable level for a subsequent STIRAP transfer to the ground state with control over rotational and hyperfine structure. We will present our latest results, and will also report on efforts to directly image a molecular sample with resolution by photoionization and subsequent detection on a phospor screen behind a microchannel plate.

Gustavsson, Mattias; Bruzewicz, Colin; Gaëtan, Alpha; Gilfoy, Nathan; Falke, Stephan; Shimasaki, Toshihiko; Demille, David

2010-03-01

143

GROUND FAILURE IN AREAS OF SUBSIDENCE DUE TO GROUND-WATER DECLINE IN THE UNITED STATES  

Microsoft Academic Search

Ground failure related to the extraction of ground water occurs in several areas of land subsidence in the United States—Arizona, California, Raft River Valley (Idaho), Houston-Galveston (Texas), and Las Vegas Valley (Nevada). The nature of the ground failure ranges from fissuring (formation of an open crack) to faulting (differential offset of the opposite sides of the failure plane parallel to

Thomas L. Holzer

144

Strangeness in the baryon ground states  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

145

Is the ground state of Yang-Mills theory Coulombic?  

SciTech Connect

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

146

Ground-based laboratory atomic oxygen calibration experiments  

NASA Astrophysics Data System (ADS)

Existing devices and analysis techniques for the monitoring of space and laboratory simulated Atomic Oxygen (AO) environments have been investigated and improved to enable more accurate and reliable measurement and calibration of AO flux and fluences than previously possible. This research was based on experimental work carried out in a ground based AO facility designed to simulate the low Earth orbit (LEO) AO space environment, an environment which contributes significantly to the degradation of spacecraft materials. Three types of AO measuring device, referred to as 'silver film', 'bulk polymer mass loss' and 'polymer overlay' devices, were used in the experiments and were based on the following principles for detection of AO, respectively: (1) The electrical resistivity characteristics of oxidising, thin silver films. (2) The mass loss of bulk polymeric materials. (3) The combination of both the above phenomena. In calibrating the responses of these devices upon exposure to AO, it was necessary to improve an existing technique to establish reference measurements of AO fluences based on the mass loss of the polymeric material 'Kapton-H'. Experiments showed that the most significant disturbance factor affecting accurate measurements of mass loss was atmospheric humidity, which was found to be responsible for a disturbance of 0.012(±0.002)mg per percent change in atmospheric humidity level for the particular samples used in this research. Experiments also revealed a novel technique which indicated the relative stability of conditions within a simulated AO environment by the ratio of mass losses of a set of polymeric test samples, including polyethylene, polytetrafluoroethylene and Kapton-H, described as a 'signature analysis technique'. Interactions occurring between AO and a variety of polyethylene related polymeric materials were shown to be influenced by the methods used to manufacture and process the polymers. This influence has been related to changes in polymeric material density and crystallinity. In addition, the limitations in protecting a polymeric material from AO erosion by insertion of fluorine into the side-chain group chemistry has been indicated. Of most significance to the development of polymer overlay devices was the discovery that the overlay material AO erosion yield was dependent upon the rate at which the polymer overlay material was sputter deposited. These devices were also shown to detect AO fluences that were linearly dependent upon the initial thickness of the overlay material up to certain thicknesses, beyond which the effects of overlay porosity or fracturing weakened the linear relationship. A novel method for analysing silver film device electrical resistances under AO exposure has been developed from a combination of existing fundamental theories concerning the electrical resistivity phenomena in thin metallic films. Validation of this analysis method revealed that experimental silver film data were consistently in disagreement with the existing theories due to a factor influencing the conduction electron mean free path length in the silver films. Final validation of this analysis technique was performed by comparing results derived from the same set of experimental silver film device data using the new technique and an example of a previous technique. It was confirmed that the novel analysis technique produced far more consistent values for the oxidation yield of silver, 3/pm0.5×10-24cm3.atom-1, than the previously used technique, 6/pm3×10- 24cm3.atom-1. The novel analysis technique has been demonstrated to be theoretically more accurate for the analysis of silver film resistance data than any previously applied theories.

Matcham, Jeremy Stephen

1998-12-01

147

Link atom bond length effect in ONIOM excited state calculations  

NASA Astrophysics Data System (ADS)

We investigate how the choice of the link atom bond length affects an electronic transition energy calculation with the so-called our own N-layer integrated molecular orbital molecular mechanics (ONIOM) hybrid method. This follows our previous paper [M. Caricato et al., J. Chem. Phys. 131, 134105 (2009)], where we showed that ONIOM is able to accurately approximate electronic transition energies computed at a high level of theory such as the equation of motion coupled cluster singles and doubles (EOM-CCSD) method. In this study we show that the same guidelines used in ONIOM ground state calculations can also be followed in excited state calculations, and that the link atom bond length has little effect on the ONIOM energy when a sensible model system is chosen. We also suggest further guidelines for excited state calculations which can help in checking the effectiveness of the definition of the model system and controlling the noise in the calculation.

Caricato, Marco; Vreven, Thom; Trucks, Gary W.; Frisch, Michael J.

2010-08-01

148

p-Difluorobenzene-argon ground state intermolecular potential energy surface.  

PubMed

The ground state intermolecular potential energy surface for the p-difluorobenzene-Ar van der Waals complex is evaluated using the coupled cluster singles and doubles including connected triple excitations [CCSD(T)] model and the augmented correlation consistent polarized valence double-zeta basis set extended with a set of 3s3p2d1f1g midbond functions. The surface minima are characterized by the Ar atom located above and below the difluorobenzene center of mass at a distance of 3.5290 A. The corresponding binding energy is -398.856 cm(-1). The surface is used in the evaluation of the intermolecular level structure of the complex. The results clearly improve previously available data and show the importance of using a good correlation method and basis set when dealing with van der Waals complexes. PMID:16354053

Cagide Fajín, José Luis; Fernández, Berta; Felker, Peter M

2005-12-22

149

Creating and probing coherent atomic states  

SciTech Connect

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

150

Fisher-like atomic divergences: Mathematical grounds and physical applications  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

151

On the ground state of Yang-Mills theory  

SciTech Connect

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

152

Recent progress in simulation of the ground state of many Boson systems  

NASA Astrophysics Data System (ADS)

We present two recent advances in the simulation of 4He in the condensed phase at zero temperature. Within the variational theory of strongly interacting bosons we have studied a cluster of 4He atoms with one alkali ion K+. For the wave function we have used a new shadow wave function (SWF) in which the coupling between one 4He atom and its shadow variable depends on its distance from the ion. This substantially improves the energy. The first shell around the ion contains 14 atoms which are spatially ordered. However the atoms of the first shell are not completely localized and frequent exchanges with atoms which are further from the ion take place. This also suggests that at least for the ion K+ the atoms of the first shell participate in the superfluidity. We have also introduced a new extension of the path integral ground state (PIGS) method which is able to compute exact ground state expectation values without extrapolations and with a SWF as the trial variational wave function to project on the ground state. This is an important extension which opens up the possibility of studying disorder phenomena in the solid phase by an exact method at zero temperature. We have applied this technique to compute the energy of formation of a vacancy at different densities in the solid phase of 4He. This computation confirms the variational result that a vacancy is a delocalized defect in the low density helium solid.

Galli, D. E.; Reatto, L.

2003-01-01

153

Study of the Electronic Structure of Molecules. III. Pyrrole Ground-State Wavefunction  

Microsoft Academic Search

An SCF LCAO MO ground-state wavefunction is presented for the pyrrole molecule. All electrons, ? and ?, are considered, and all the necessary many-center integrals are included in this work. The analysis of the wavefunction reveals that there is a strong two-way charge transfer on the nitrogen atom. (This reopens the problem of the validity of ?-electron computations, as discussed

E. Clementi; H. Clementi; D. R. Davis

1967-01-01

154

The 4He tetramer ground state in the Faddeev-Yakubovsky differential equations formalism  

SciTech Connect

The characteristics of the four 4He atom cluster are investigated using the differential equations for Yakubovsky components. The binding energy, mean-square radius and density function are calculated for the ground state. The spatial properties of the cluster and its subsystems are studied.

I N Filikhin; S L Yakovlev; V A Roudnev; B Vlahovic

2002-02-14

155

Lossless anomalous dispersion and an inversionless gain doublet via dressed interacting ground states  

SciTech Connect

Transparent media exhibiting anomalous dispersion have been of considerable interest since Wang, Kuzmich, and Dogariu [Nature 406, 277 (2000)] first observed light propagate with superluminal and negative group velocities without absorption. Here, we propose an atomic model exhibiting these properties, based on a generalization of amplification without inversion in a five-level dressed interacting ground-state system. The system consists of a {Lambda} atom prepared as in standard electromagnetically induced transparency (EIT), with two additional metastable ground states coupled to the {Lambda} atom ground states by two rf-microwave fields. We consider two configurations by which population is incoherently pumped into the ground states of the atom. Under appropriate circumstances, we predict a pair of new gain lines with tunable width, separation, and height. Between these lines, absorption vanishes but dispersion is large and anomalous. The system described here is a significant improvement over other proposals in the anomalous dispersion literature in that it permits additional coherent control over the spectral properties of the anomalous region, including a possible 10{sup 4}-fold increase over the group delay observed by Wang, Kuzmich, and Dogariu.

Weatherall, James Owen [Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States); Department of Mathematical Sciences, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States); Department of Logic and Philosophy of Science, University of California Irvine, 3151 Social Science Plaza A, Irvine, California 92697 (United States); Search, Christopher P. [Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, New Jersey 07030 (United States)

2010-02-15

156

A nonlinear programming approach to lower bounds for the ground-state energy of helium  

SciTech Connect

Lower-bound estimates for the ground-state energy of the helium atom are determined using nonlinear programming techniques. Optimized lower bounds are determined for single-particle, radially correlated, and general correlated wave functions. The local nature of the method employed makes it a very severe test of the accuracy of the wave function.

Porras, I.; Feldmann, D.M.; King, F.W. [Univ. of Wisconsin, Eau Claire, WI (United States). Dept. of Chemistry

1999-02-20

157

Exact superconducting ground states of the extended Anderson model  

NASA Astrophysics Data System (ADS)

We obtain exact ground states of an extended periodic Anderson model (EPAM) with non-local hybridization and Coulomb repulsion between f and c electrons (Falicov-Kimball term) in one dimension. We show that for a range of parameter values these ground states exhibit composite hole pairing and superconductivity that originate from purely electronic interactions.

Sarasua, L. G.

2011-10-01

158

Analyticity of the Ground State Energy for Massless Nelson Models  

NASA Astrophysics Data System (ADS)

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.

Abdesselam, Abdelmalek; Hasler, David

2012-03-01

159

Solving satisfiability problems by the ground-state quantum computer  

SciTech Connect

A quantum algorithm is proposed to solve the satisfiability (SAT) problems by the ground-state quantum computer. The scale of the energy gap of the ground-state quantum computer is analyzed for the 3-bit exact cover problem. The time cost of this algorithm on the general SAT problems is discussed.

Mao Wenjin [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA and 20 Hearthstone Drive, Edison, New Jersey 08820 (United States)

2005-11-15

160

Periodic Table of Ground-State Elementary Particles  

Microsoft Academic Search

We will present a poster that represents a periodic table of all the possible ground-state elementary particles - quarks, leptons, mesons, baryons and the force carriers. This will be the first time, a comprehensive periodic table of all the possible ground-state elementary particles (similar to the periodic table of elements) will be shown to the physics community in public.

Akhtar Mahmood; Allan Figueroa

2002-01-01

161

Fidelity of the ground state in adiabatic quantum computation  

NASA Astrophysics Data System (ADS)

The energy gap between the ground and excited states of a qubit register performing an adiabatic quantum computation (AQC) algorithm is expected to provide additional stability against decoherence by environmental noise. However, the precise quantitative magnitude of this effect is still an open question. In this work, we show that fidelity of the ground state provides the ultimate quantitative measure of the AQC stability against decoherence. Even if the qubit register is not driven out of the ground state by the time evolution of the algorithm, the ground state is deformed by the qubit-environment interaction. The extent of this deformation can be characterized by the same noise correlators that determine the relaxation rates in the gate-model QC. We derive finite-temperature expression for the ground-state fidelity and calculate it numerically for the 16-qubit instances of adiabatic quantum optimization.

Deng, Qiang; Averin, Dmitri; Amin, Mohammad; Smith, Peter

2012-02-01

162

Ground state of a quasi-two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

The ground state of a quasi-two-dimensional electron gas (Q-2DEG) is investigated within a framework of the local spin density approximation (LSDA) with Perdew-Zunger type exchange-correlation energy. The ground state in a Q-2DEG is given as a function of film thickness and electron density. The Wigner rod ground state in a very thin film with low electron areal density is discussed in detail. In addition, the ground state of a two-dimensional electron gas (2DEG) is investigated using the LSDA with Tanatar-Ceperley and Attaccalite-Moroni-Georgi-Bachelet types of exchange-correlation energy. The ground state is found to show a phase transition from a nonmagnetic fluid to a spin-fully-polarized ferromagnetic Wigner ribbon with decreasing areal density. The difference between a 2DEG and a Q-2DEG with infinitesimal film thickness is discussed.

Ito, Yasumitsu; Okazaki, Kazuyuki; Teraoka, Yoshihiro

2004-04-01

163

Atomic Schroedinger cat-like states  

SciTech Connect

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

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

2010-10-11

164

Atomic Schrödinger cat-like states  

NASA Astrophysics Data System (ADS)

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

Enriquez-Flores, Marco; Rosas-Ortiz, Oscar

2010-10-01

165

Many-body spin interactions and the ground state of a dense Rydberg lattice gas.  

PubMed

We study a one-dimensional atomic lattice gas in which Rydberg atoms are excited by a laser and whose external dynamics is frozen. We identify a parameter regime in which the Hamiltonian is well approximated by a spin Hamiltonian with quasilocal many-body interactions which possesses an exact analytic ground state solution. This state is a superposition of all states of the system that are compatible with an interaction induced constraint weighted by a fugacity. We perform a detailed analysis of this state which exhibits a crossover between a paramagnetic phase with short-ranged correlations and a crystal. This study also leads us to a class of spin models with many-body interactions that permit an analytic ground state solution. PMID:21405236

Lesanovsky, Igor

2011-01-11

166

Many-Body Spin Interactions and the Ground State of a Dense Rydberg Lattice Gas  

NASA Astrophysics Data System (ADS)

We study a one-dimensional atomic lattice gas in which Rydberg atoms are excited by a laser and whose external dynamics is frozen. We identify a parameter regime in which the Hamiltonian is well approximated by a spin Hamiltonian with quasilocal many-body interactions which possesses an exact analytic ground state solution. This state is a superposition of all states of the system that are compatible with an interaction induced constraint weighted by a fugacity. We perform a detailed analysis of this state which exhibits a crossover between a paramagnetic phase with short-ranged correlations and a crystal. This study also leads us to a class of spin models with many-body interactions that permit an analytic ground state solution.

Lesanovsky, Igor

2011-01-01

167

Many-Body Spin Interactions and the Ground State of a Dense Rydberg Lattice Gas  

SciTech Connect

We study a one-dimensional atomic lattice gas in which Rydberg atoms are excited by a laser and whose external dynamics is frozen. We identify a parameter regime in which the Hamiltonian is well approximated by a spin Hamiltonian with quasilocal many-body interactions which possesses an exact analytic ground state solution. This state is a superposition of all states of the system that are compatible with an interaction induced constraint weighted by a fugacity. We perform a detailed analysis of this state which exhibits a crossover between a paramagnetic phase with short-ranged correlations and a crystal. This study also leads us to a class of spin models with many-body interactions that permit an analytic ground state solution.

Lesanovsky, Igor [Midlands Ultracold Atom Research Centre (MUARC), School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2011-01-14

168

The Ground State of D2  

NASA Astrophysics Data System (ADS)

By combining our experimental data with the data of others, these spectra of hydrogen and its isotopic variants will be analyzed simultaneously to obtain a measure of the breakdown of the Born-Oppenheimer approximation. We will employ a variant of the Bunker-Watson extension, which accounts for this breakdown through the nuclear mass dependence of the Dunham coefficients. The first step in this process is to assemble and confirm accuracy of the data set and to assign appropriate statistical weights. Along these lines we have combined our data with the data of others on D2 and H2. A total of 31 D2 lines and 54 H2 were fit to a Dunham expansion. These data were analyzed using a modified version of the iterative bi-weighting, stepwise regression system. Termination of the bi-weighting iterations was controlled by an expected-variance-driven Komolgrov-Smirnov (K-S) test. When a maximum probability that the residuals of the non-zero weighted observations are drawn from a normal distribution is achieved in the bi-weighting iterations, the process is terminated. The maximum probability is often above 90% and the variance of the hypothetical parent distribution is generally quite close to the expected value for the experimental data. The D2 data set was fit to a standard deviation of 0.00163 cm-1, an improvement over current literature fits. The H2 data were fit to a standard deviation of 0.00458 cm-1. The ultimate goal of this research effort is to obtain a single parameter set which can be used to calculate vibrational-rotational energy levels for H2 and its isotopic variants D2, T2, HD, HT and DT in the 1 ? ground electronic state. This analysis will culminate in the first determination of isotopically invariant vibration-rotation constants for the hydrogen molecule. Such a parameter set does not presently exist to our knowledge. Molecular hydrogen isotopes are of fundamental importance in the molecular sciences, especially molecular astrophysics including stellar, planetary and galactic studies. This effort has been partially funded by the NASA Planetary Atmospheres Program.

Hillman, J. J.; Blass, W. E.; Reuter, D.; Jennings, D. E.

2004-11-01

169

A quantum gas of ground state molecules in an optical lattice  

NASA Astrophysics Data System (ADS)

Ultracold samples of molecules are ideally suited for fundamental studies in physics and chemistry. For many of the proposed experiments full molecular state control and high phase space densities are needed. We create a dense quantum gas of ground state Cs2 molecules trapped at the wells of a 3D optical lattice, i.e. a molecular Mott-insulator-like state with ground state molecules with vibrational quantum number v = 0. We first efficiently produce weakly bound molecules with v 155 on a Feshbach resonance out of an atomic Mott-insulator state that is obtained from a Bose-Einstein condensate (BEC) of Cs atoms. These molecules are then (coherently) transferred to the ground state by two sequential two-photon STIRAP processes via the intermediate vibrational level v 73 ^1. The molecule production efficiency and the single-step STIRAP transfer efficiency reach 50% and 80%, respectively. We discuss the stability of the system and our progress towards the creation of a BEC of ground state molecules, which is expected to form when the molecular Mott-like state is ``melted'' upon lowering the lattice depth and releasing the molecules from the wells into a large volume trap. ^1J. G. Danzl, E. Haller, M. Gustavsson, M. Mark, R. Hart, N. Bouloufa, O. Dulieu, H. Ritsch, H.-C. Nägerl, Science 321, 1062 (2008).

Danzl, Johann; Mark, Manfred; Haller, Elmar; Gustavsson, Mattias; Hart, Russell; Nägerl, Hanns-Christoph

2009-05-01

170

Nanoscale atoms in solid-state chemistry.  

PubMed

We describe a solid-state material formed from binary assembly of atomically precise molecular clusters. [Co6Se8(PEt3)6][C60]2 and [Cr6Te8(PEt3)6][C60]2 assembled into a superatomic relative of the cadmium iodide (CdI2) structure type. These solid-state materials showed activated electronic transport with activation energies of 100 to 150 millielectron volts. The more reducing cluster Ni9Te6(PEt3)8 transferred more charge to the fullerene and formed a rock-salt-related structure. In this material, the constituent clusters are able to interact electronically to produce a magnetically ordered phase at low temperature, akin to atoms in a solid-state compound. PMID:23744780

Roy, Xavier; Lee, Chul-Ho; Crowther, Andrew C; Schenck, Christine L; Besara, Tiglet; Lalancette, Roger A; Siegrist, Theo; Stephens, Peter W; Brus, Louis E; Kim, Philip; Steigerwald, Michael L; Nuckolls, Colin

2013-06-06

171

Ground water contamination in the United States  

Microsoft Academic Search

This book demonstrates an exhaustive research effort into published reports and legal documents of which 344 are cited. From the literature, the authors selected 84 tables and 41 figures and maps, adding to the value of the collected body of information provided within the text. These summarize and graphically illustrate the 10 major ground water regions, population served by source

R. Patrick; E. Ford; J. Quarles

1987-01-01

172

ON THE RATIOS BETWEEN THE ISOMERIC AND GROUND STATE YIELDS OF Zn⁶⁹ PRODUCED IN VARIOUS NUCLEAR REACTIONS  

Microsoft Academic Search

The ratio between the amounts of Zn⁶⁹ atoms produced in the ; isomeric and ground states in the Zn⁶⁸(d,p)Zn⁶⁹, Ga⁶⁹(n,p)Zn\\/; sup 69\\/, and Ga⁷¹(d, alpha )Zn⁶⁹ reactions were studied. In the ; first reaction the relative yield of the isomeric state first increases with the ; deuteron energy and then remains constant (about 0.5 of the ground state yield). ;

K. I. Zherebtsova; T. P. Makarova; Yu. A. Nemilov; B. L. Funstein

1958-01-01

173

Ground state geometry of binary condensates in axisymmetric traps  

NASA Astrophysics Data System (ADS)

We show that the ground state interface geometry of binary condensates in the phase-separated regime undergoes a smooth transition from planar to ellipsoidal to cylindrical geometry. This occurs for the condensates with repulsive interactions as the trapping potential is changed from prolate to oblate. The correct ground state geometry emerges when the interface energy is included in the energy minimization, whereas energy minimization based on the Thomas-Fermi approximation gives incorrect geometry. The planar and cylindrical interface geometries have less interface area and minimize the interface energy. These are the preferred ground states in the cigar- and pan-cake-shaped trap configurations.

Gautam, S.; Angom, D.

2010-05-01

174

Encoding universal computation in the ground states of Ising lattices.  

PubMed

We characterize the set of ground states that can be synthesized by classical two-body Ising Hamiltonians. We then construct simple Ising planar blocks that simulate efficiently a universal set of logic gates and connections, and hence any Boolean function. We therefore provide a new method of encoding universal computation in the ground states of Ising lattices and a simpler alternative demonstration of the known fact that finding the ground state of a finite Ising spin glass model is NP complete. We relate this with our previous result about emergent properties in infinite lattices. PMID:23005377

Gu, Mile; Perales, Álvaro

2012-07-13

175

Selection of the Ground State for Nonlinear SCHRÖDINGER Equations  

NASA Astrophysics Data System (ADS)

We prove for a class of nonlinear Schrödinger systems (NLS) having two nonlinear bound states that the (generic) large time behavior is characterized by decay of the excited state, asymptotic approach to the nonlinear ground state and dispersive radiation. Our analysis elucidates the mechanism through which initial conditions which are very near the excited state branch evolve into a (nonlinear) ground state, a phenomenon known as ground state selection. Key steps in the analysis are the introduction of a particular linearization and the derivation of a normal form which reflects the dynamics on all time scales and yields, in particular, nonlinear master equations. Then, a novel multiple time scale dynamic stability theory is developed. Consequently, we give a detailed description of the asymptotic behavior of the two bound state NLS for all small initial data. The methods are general and can be extended to treat NLS with more than two bound states and more general nonlinearities including those of Hartree-Fock type.

Soffer, A.; Weinstein, M. I.

176

Ground Water Pollution Problems in the Northwestern United States.  

National Technical Information Service (NTIS)

An evaluation of ground-water problems has been carried out in six states in the northwest: Colorado, Idaho, Montana, Oregon, Washington and Wyoming. There is a need for baseline water quality data and systematic evaluation of overall ground-water conditi...

D. W. Miller F. van der Leeden L. A. Cerrillo

1975-01-01

177

Ground water pollution problems in the northwestern United States  

Microsoft Academic Search

An evaluation of ground-water problems has been carried out in six states in the northwest: Colorado, Idaho, Montana, Oregon, Washington and Wyoming. There is a need for baseline water quality data and systematic evaluation of overall ground-water conditions, especially in urban zones, in areas of petroleum exploration and development, and at locations of mining and industrial activity. The most common

F. van der Leeden; L. A. Cerrillo; D. W. Miller

1975-01-01

178

GROUND-WATER POLLUTION PROBLEMS IN THE SOUTHEASTERN UNITED STATES  

EPA Science Inventory

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 ...

179

Entangled states of trapped atomic ions  

Microsoft Academic Search

To process information using quantum-mechanical principles, the states of individual particles need to be entangled and manipulated. One way to do this is to use trapped, laser-cooled atomic ions. Attaining a general-purpose quantum computer is, however, a distant goal, but recent experiments show that just a few entangled trapped ions can be used to improve the precision of measurements. If

Rainer Blatt; David Wineland

2008-01-01

180

Atomic charge state determination by AFM  

Microsoft Academic Search

We investigated the charge state switching of individual gold and silver adatoms on ultrathin NaCl films on Cu(111) using a qPlus tuning fork atomic force microscope (AFM) operated at 5 Kelvin with oscillation amplitudes in the sub-ångstrom regime. Charging of a gold adatom by one electron charge increased the force on the AFM tip by a few piconewtons. Employing Kelvin

Leo Gross; Fabian Mohn; Peter Liljeroth; Jascha Repp; Franz Giessibl; Gerhard Meyer

2010-01-01

181

Approximating the ground state of gapped quantum spin systems  

SciTech Connect

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

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

2009-01-01

182

Ground States of Lattice Gases with “Almost” Convex Repulsive Interactions  

Microsoft Academic Search

To the best of our knowledge there is only one example of a lattice system with long-range two-body interactions whose ground states have been determined exactly: the one-dimensional lattice gas with purely repulsive and strictly convex interactions. Its ground-state particle configurations do not depend on any other details of the interactions and are known as the generalized Wigner lattices or

2000-01-01

183

Dielectronic recombination of ground-state and metastable Li+ ions  

Microsoft Academic Search

Dielectronic recombination has been investigated for Deltan=1 resonances of ground-state Li+(1s2) and for Deltan=0 resonances of metastable Li+(1s2s 3S). The ground-state spectrum shows three prominent transitions between 53 and 64 eV, while the metastable spectrum exhibits many transitions with energies <3.2 eV. Reasonably good agreement of R-matrix, LS coupling calculations with the measured recombination rate coefficient is obtained. The time

A. A. Saghiri; J. Linkemann; M. Schmitt; D. Schwalm; A. Wolf; T. Bartsch; A. Hoffknecht; A. Müller; W. G. Graham; A. D. Price; N. R. Badnell; T. W. Gorczyca; J. A. Tanis

1999-01-01

184

Stimulated Raman scattering in atomic ensembles: Toward quantum state entanglement  

NASA Astrophysics Data System (ADS)

Entanglement generation and verification are essential steps to achieve long-distance quantum communication with atomic ensembles according to some protocols. In this dissertation, new schemes for generating quantum state entanglement between two atomic ensembles by stimulated Raman scattering are proposed and analyzed under various practical factors such as linear dispersion, readout losses, and detector noise. In the photon-number-state entanglement scheme, new regimes of discrete-variable entanglement are found to be achievable at microscopic and mesoscopic excitation levels. In the field-quadrature-amplitude entanglement scheme, the inequality of quadrature variance satisfies the entanglement criteria for bipartite Gaussian state entanglement, even at low readout efficiency. Significant progress towards the experimental generation of such entanglement is reported. Population transfer between the atomic ground states is a prerequisite step to prepare the gain medium for stimulated Raman scattering. The high transfer efficiency is achieved through broadband optical pumping. The Stokes and time-delayed anti-Stokes scattering are observed, which is a primary step to verify the quantum memory effect in the atomic vapor. The photon statistics of the Stokes field is measured with a photon-number detection system operating at below the shot-noise level. The pulse energy dependence of Stokes fields on several practical factors is explored. Some new features and phenomena of stimulated Raman scattering in rubidium vapor are observed and analyzed. The simultaneous generation of Stokes and anti-Stokes scattering is observed in the cooperative Raman scattering process, in which only a single strong pump field is present. An enhanced Raman scattering process is also observed, in which the Stokes signal generated by the time-delayed second pump is enhanced by the presence of the first pump when the two pumps are in the Stokes pump frequency range. In addition, we observe very large pulse delay during propagation through 85Rb cell, and we explain it with a theoretical linear dispersion model.

Ji, Wenhai

185

Ground State of the H3+ Molecular Ion: Physics Behind  

NASA Astrophysics Data System (ADS)

Five physics mechanisms of interaction leading to the binding of the H3+ molecular ion are identified. They are realized in a form of variational trial functions, and their respective total energies are calculated. Each of them provides subsequently the most accurate approximation for the Born-Oppenheimer (BO) ground state energy among (two-three-seven)-parametric trial functions being, correspondingly, H2-molecule plus proton (two variational parameters), H2+-ion plus H-atom (three variational parameters), and generalized Guillemin-Zener (seven variational parameters). These trial functions are chosen following a criterion of physical adequacy. They include the electronic correlation in the exponential form, exp(-r12), where - is a variational parameter. Superpositions of two different mechanisms of binding are investigated, and a particular one, which is a generalized Guillemin-Zener plus H2-molecule plus proton (ten variational parameters), provides the total energy at the equilibrium of E = -1.3432 au. The superposition of three mechanisms, generalized Guillemin-Zener plus (H2-molecule plus proton) plus (H2+-ion plus H) (14 parameters) leads to the total energy, which deviates from the best known BO energy to -0.0004 au, it reproduces two-three significant digits in exact, non-BO total energy. In general, our variational energy agrees in two-three-four significant digits with the most accurate results available at present as well as major expectation values.

Turbiner, A. V.; Lopez Vieyra, J. C.

2013-10-01

186

Homogeneous binary trees as ground states of quantum critical Hamiltonians  

SciTech Connect

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

Silvi, P. [International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste (Italy); Giovannetti, V. [NEST, Scuola Normale Superiore and Istituto di Nanoscienze-CNR, I-56127 Pisa (Italy); Montangero, S. [Institut fuer Quanteninformationsverarbeitung, Universitaet Ulm, D-89069 Ulm (Germany); Rizzi, M.; Cirac, J. I. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Fazio, R. [NEST, Scuola Normale Superiore and Istituto di Nanoscienze-CNR, I-56127 Pisa (Italy); Center for Quantum Technologies, National University of Singapore, 119077 (Singapore)

2010-06-15

187

Ground-Water Availability in the United States  

USGS Publications Warehouse

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

188

Efficient algorithm for approximating one-dimensional ground states  

NASA Astrophysics Data System (ADS)

The density-matrix renormalization-group method is very effective at finding ground states of one-dimensional (1D) quantum systems in practice, but it is a heuristic method, and there is no known proof for when it works. In this article we describe an efficient classical algorithm which provably finds a good approximation of the ground state of 1D systems under well-defined conditions. More precisely, our algorithm finds a matrix product state of bond dimension D whose energy approximates the minimal energy such states can achieve. The running time is exponential in D, and so the algorithm can be considered tractable even for D, which is logarithmic in the size of the chain. The result also implies trivially that the ground state of any local commuting Hamiltonian in 1D can be approximated efficiently; we improve this to an exact algorithm.

Aharonov, Dorit; Arad, Itai; Irani, Sandy

2010-07-01

189

Efficient algorithm for approximating one-dimensional ground states  

SciTech Connect

The density-matrix renormalization-group method is very effective at finding ground states of one-dimensional (1D) quantum systems in practice, but it is a heuristic method, and there is no known proof for when it works. In this article we describe an efficient classical algorithm which provably finds a good approximation of the ground state of 1D systems under well-defined conditions. More precisely, our algorithm finds a matrix product state of bond dimension D whose energy approximates the minimal energy such states can achieve. The running time is exponential in D, and so the algorithm can be considered tractable even for D, which is logarithmic in the size of the chain. The result also implies trivially that the ground state of any local commuting Hamiltonian in 1D can be approximated efficiently; we improve this to an exact algorithm.

Aharonov, Dorit; Arad, Itai; Irani, Sandy [School of Computer Science and Engineering, Hebrew University, Jerusalem (Israel); School of Computer Science, Tel-Aviv University, Tel-Aviv (Israel); Computer Science Department, University of California, Irvine, California (United States)

2010-07-15

190

Ground-state geometric quantum computing in superconducting systems  

SciTech Connect

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

Solinas, P. [Department of Applied Physics/COMP, Aalto University, P. O. Box 15100, FI-00076 Aalto (Finland); Pirkkalainen, J.-M. [Department of Applied Physics/COMP, Aalto University, P. O. Box 15100, FI-00076 Aalto (Finland); Low Temperature Laboratory, Aalto University, P. O. Box 13500, FI-00076 Aalto (Finland); Moettoenen, M. [Department of Applied Physics/COMP, Aalto University, P. O. Box 15100, FI-00076 Aalto (Finland); Low Temperature Laboratory, Aalto University, P. O. Box 13500, FI-00076 Aalto (Finland); Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia)

2010-11-15

191

Creation of Ultracold Sr2 Molecules in the Electronic Ground State  

NASA Astrophysics Data System (ADS)

We report on the creation of ultracold Sr284 molecules in the electronic ground state. The molecules are formed from atom pairs on sites of an optical lattice using stimulated Raman adiabatic passage (STIRAP). We achieve a transfer efficiency of 30% and obtain 4×104 molecules with full control over the external and internal quantum state. STIRAP is performed near the narrow S01-P13 intercombination transition, using a vibrational level of the 1(0u+) potential as an intermediate state. In preparation of our molecule association scheme, we have determined the binding energies of the last vibrational levels of the 1(0u+), 1(1u) excited-state and the X?g+1 ground-state potentials. Our work overcomes the previous limitation of STIRAP schemes to systems with magnetic Feshbach resonances, thereby establishing a route that is applicable to many systems beyond alkali-metal dimers.

Stellmer, Simon; Pasquiou, Benjamin; Grimm, Rudolf; Schreck, Florian

2012-09-01

192

Toward internal cooling of trapped molecular ions using a spin-orbit split ground state  

NASA Astrophysics Data System (ADS)

Preparation of state-selected trapped molecular ensembles is a promising starting point for precision measurements on trapped molecular samples. Translational cooling of trapped molecular ions can be accomplished sympathetically by laser cooling a co-trapped atomic species. To date, in situ cooling of rotational degrees of freedom has been demonstrated only for polar hydrides, by optical pumping into an excited vibrational level. However, with increasing reduced mass, the time for vibrational relaxation within the ground state increases, making this scheme problematic for heavy species. We introduce a new cooling scheme, exploiting the diagonal Franck-Condon factors present for molecular ions with spin-orbit split ground states, applicable to certain heavy as well as non-polar species. Progress towards the experimental realization of this scheme for cooling IF?+, including the molecular ion production technique, details of the state-preparation, and the proposed state-resolved detection scheme will be discussed.

Rajagopal, V.; Marler, J. P.; Ruth, L. C.; Seck, C. M.; Odom, B. C.

2011-06-01

193

Hyperfine interaction in the ground state of the negatively charged nitrogen vacancy center in diamond  

NASA Astrophysics Data System (ADS)

The N14 , N15 , and C13 hyperfine interactions in the ground state of the negatively charged nitrogen vacancy (NV-) center have been investigated using electron-paramagnetic-resonance spectroscopy. The previously published parameters for the N14 hyperfine interaction do not produce a satisfactory fit to the experimental NV- electron-paramagnetic-resonance data. The small anisotropic component of the NV- hyperfine interaction can be explained from dipolar interaction between the nitrogen nucleus and the unpaired-electron probability density localized on the three carbon atoms neighboring the vacancy. Optical spin polarization of the NV- ground state was used to enhance the electron-paramagnetic-resonance sensitivity enabling detailed study of the hyperfine interaction with C13 neighbors. The data confirmed the identification of three equivalent carbon nearest neighbors but indicated the next largest C13 interaction is with six, rather than as previously assumed three, equivalent neighboring carbon atoms.

Felton, S.; Edmonds, A. M.; Newton, M. E.; Martineau, P. M.; Fisher, D.; Twitchen, D. J.; Baker, J. M.

2009-02-01

194

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

SciTech Connect

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

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

2011-06-15

195

High-speed ground transportation development outside United States  

SciTech Connect

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

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

1995-09-01

196

Magnetic field induced lattice ground states from holography  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

197

Ground State Destabilization by Anionic Nucleophiles Contributes to the Activity of Phosphoryl Transfer Enzymes  

PubMed Central

Enzymes stabilize transition states of reactions while limiting binding to ground states, as is generally required for any catalyst. Alkaline Phosphatase (AP) and other nonspecific phosphatases are some of Nature's most impressive catalysts, achieving preferential transition state over ground state stabilization of more than 1022-fold while utilizing interactions with only the five atoms attached to the transferred phosphorus. We tested a model that AP achieves a portion of this preference by destabilizing ground state binding via charge repulsion between the anionic active site nucleophile, Ser102, and the negatively charged phosphate monoester substrate. Removal of the Ser102 alkoxide by mutation to glycine or alanine increases the observed Pi affinity by orders of magnitude at pH 8.0. To allow precise and quantitative comparisons, the ionic form of bound Pi was determined from pH dependencies of the binding of Pi and tungstate, a Pi analog lacking titratable protons over the pH range of 5–11, and from the 31P chemical shift of bound Pi. The results show that the Pi trianion binds with an exceptionally strong femtomolar affinity in the absence of Ser102, show that its binding is destabilized by ?108-fold by the Ser102 alkoxide, and provide direct evidence for ground state destabilization. Comparisons of X-ray crystal structures of AP with and without Ser102 reveal the same active site and Pi binding geometry upon removal of Ser102, suggesting that the destabilization does not result from a major structural rearrangement upon mutation of Ser102. Analogous Pi binding measurements with a protein tyrosine phosphatase suggest the generality of this ground state destabilization mechanism. Our results have uncovered an important contribution of anionic nucleophiles to phosphoryl transfer catalysis via ground state electrostatic destabilization and an enormous capacity of the AP active site for specific and strong recognition of the phosphoryl group in the transition state.

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

2013-01-01

198

Ground state properties of halo nuclei  

Microsoft Academic Search

By a rescaling both the kinetic and potential energy terms of the harmonic oscillator in conventional shell model(SM) and\\u000a a mean field imitating, a self-similar-structure shell model(SSM) in which the single-particle orbits have state- or orbit-dependent\\u000a frequencies was proposed to extend the SM calculations to light nuclei near the neutron drip line.

Zhengda Wang; Xiaodong Zhang; Xiaochun Wang; Xiaobin Wang

1996-01-01

199

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

Microsoft Academic Search

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

200

Creating Ground State Molecules with Optical Feshbach Resonances in Tight Traps  

SciTech Connect

We propose to create ultracold ground state molecules in an atomic Bose-Einstein condensate by adiabatic crossing of an optical Feshbach resonance. We envision a scheme where the laser intensity and possibly also frequency are linearly ramped over the resonance. Our calculations for {sup 87}Rb show that for sufficiently tight traps it is possible to avoid spontaneous emission while retaining adiabaticity, and conversion efficiencies of up to 50% can be expected.

Koch, Christiane P. [Laboratoire Aime Cotton, CNRS, Ba circumflex t. 505, Campus d'Orsay, 91405 Orsay Cedex (France); Department of Physical Chemistry and Fritz Haber Research Center, Hebrew University, Jerusalem 91904 (Israel); Masnou-Seeuws, Francoise [Laboratoire Aime Cotton, CNRS, Bat. 505, Campus d'Orsay, 91405 Orsay Cedex (France); Kosloff, Ronnie [Department of Physical Chemistry and Fritz Haber Research Center, Hebrew University, Jerusalem 91904 (Israel)

2005-05-20

201

Ground-state proton radioactivity in the domain of neutron-poor nuclei heavier than tin  

Microsoft Academic Search

The ground-state proton radioactivity in the domain of neutron-poor nuclei with an atomic number above 50 was investigated. In order to allow the observation of short-lived decays in the nsec range, a large-area, annular gas detector system with a parallel-plate avalanche counter was built, it has a detection probability better than 90% for protons. A 250 MeV Ni58-beam was used

Albrecht Gillitzer

1985-01-01

202

Activation of C-O and C-C bonds and formation of novel HAlOH-ether complexes: an EPR study of the reaction of ground-state Al atoms with methylethyl ether and diethyl ether.  

PubMed

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

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

2012-03-01

203

Nonlinear Faraday rotation and detection of superposition states in cold atoms  

NASA Astrophysics Data System (ADS)

We report on the observation of nonlinear Faraday rotation with cold atoms at a temperature of ~100 ?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; Corsini, Eric; Zachorowski, Jerzy; Gawlik, Wojciech

2010-05-01

204

Solving quantum ground-state problems with nuclear magnetic resonance.  

PubMed

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?? 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

2011-09-09

205

Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

206

Quantum Insulating States of F=2 Cold Atoms in Optical Lattices  

SciTech Connect

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

Zhou Fei; Semenoff, Gordon W. [Pacific Institute of Theoretical Physics and the Department of Physics and Astronomy, The University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

2006-11-03

207

Generation of squeezed atomic states in cavity QED  

Microsoft Academic Search

A squeezed atomic state is that state of a system of two-level atoms for which the intrinsic quantum noise in a process of\\u000a measurement is less than the minimum noise obtained by using a spin coherent state. It is shown that such a state is generated\\u000a in certain time intervals when a non-squeezed atomic state evolves on interaction with a

Aditi Ray; R. R. Puri

1998-01-01

208

Glueballs and mesons: The ground states  

SciTech Connect

We provide a new, independent, and analytic estimate of the lowest glueball mass, and we found it at 1661 MeV within a relativistic quantum-field model based on analytic confinement. The conventional mesons and the weak decay constants are described to extend the consideration. For the spectra of two-gluon and two-quark bound states we solve the ladder Bethe-Salpeter equation. By using a minimal set of model parameters (the quark masses, the coupling constant, and the confinement scale) we obtain numerical results which are in reasonable agreement with experimental evidence in the wide range of energy scale. The model serves a reasonable framework to describe simultaneously different sectors in low-energy particle physics.

Ganbold, G. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Institute of Physics and Technology, 210651 Ulaanbaatar (Mongolia)

2009-02-01

209

Magnetic dipole moments of the 147, 149 Gd ground states  

Microsoft Academic Search

Nuclear orientation measurements at low temperatures have been carried out on radioactive isotopes147, 149Gd in Fe and Gd. The initial-state orientation coefficients determined from the measured gamma-ray anisotropies yield the magnetic dipole moments of the147Gd and149Gd ground states to be 1.02(9) and 0.88(4), ?N, respectively. These values follow the systematics of the 7\\/2? state magnetic moments of the odd-A nuclei

T. I. Kracíková; S. Davaa; M. Finger

1987-01-01

210

Ground state isomerization of a model green fluorescent protein chromophore  

Microsoft Academic Search

The relationship between ground state cis–trans isomerization and protonation state is explored for a model green fluorescent protein chromophore, 4-hydroxybenzylidene-1,2-dimethylimidazolinone (HBDI). We find that the protonation state has only a modest effect on the free energy differences between cis and trans isomers and on the activation energies for isomerization. Specifically, the experimental free energy differences are 3.3, 8.8, and 9.6

Xiang He; Alasdair F. Bell; Peter J. Tonge

2003-01-01

211

Cavity enhanced spin measurement of the ground state spin of an NV center in diamond  

NASA Astrophysics Data System (ADS)

A key step in the use of diamond nitrogen vacancy (NV) centers for quantum computational tasks is a single shot quantum non-demolition measurement of the electronic spin state. Here, we propose a high fidelity measurement of the ground state spin of a single NV center, using the effects of cavity quantum electrodynamics. The scheme we propose is based in the one-dimensional atom or Purcell regime, removing the need for high Q cavities that are challenging to fabricate. The ground state spin of the NV center has a splitting of ?6-10 ?eV, which can be resolved in a high-resolution absorption measurement. By incorporating the center in a low-Q and low volume cavity we show that it is possible to perform single shot readout of the ground state spin using a weak laser with an error rate of ?7×10-3, when realistic experimental parameters are considered. Since very low levels of light are used to probe the state of the spin we limit the number of florescence cycles, which dramatically reduces the measurement induced decoherence approximating a non-demolition measurement of ground state spin.

Young, A.; Hu, C. Y.; Marseglia, L.; Harrison, J. P.; O'Brien, J. L.; Rarity, J. G.

2009-01-01

212

Atomic-state teleportation by using a quantum switch  

Microsoft Academic Search

We present a scheme of atomic-state teleportation by using a quantum switch (QS). Based on the principle of QS and the quantum interference effect, a controlled-NOT operation between atom and cavity is proposed and used to transform the joint measurement of the von Neumann type into the discrete measurements. A detection method using several atoms resonantly interacting with field state

Zhong-Yang Wang; Xun-Li Feng; Shang-Qing Gong; Zhi-Zhan Xu

2001-01-01

213

Ground state microstructure of a ferrofluid thin layer  

SciTech Connect

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

Prokopieva, T. A.; Danilov, V. A.; Kantorovich, S. S., E-mail: sofia@icp.uni-stuttgart.de [Ural State University (Russian Federation)

2011-09-15

214

Frustration and ground state entanglement in 2D lattices  

NASA Astrophysics Data System (ADS)

We investigate frustrated 2D lattice systems with an Ising-type interaction using exact diagonalization and Tensor Network techniques. The geometric frustration in these systems is controlled by the couplings of the Hamiltonian. We study the ground state entanglement for the combination of model parameters inducing a higher degree of frustrated interactions, showing relations between the frustration and the amount of quantum correlations present along different partitions of the lattice. Using the connection between ground state entanglement and the classical simulation of quantum systems, these results point to scenarios where simulating local systems is supposed to be hard.

Garcia, Artur; Latorre, Jose I.

2013-03-01

215

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Alternative Scheme for Generation of Atomic Schrödinger Cat States and Entangled Coherent States in an Optical Cavity  

NASA Astrophysics Data System (ADS)

We propose an alternative scheme for generation of atomic Schrödinger cat states in an optical cavity. In the scheme the atoms are always populated in the two ground states and the cavity remains in the vacuum state. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. The scheme may be generalized to the deterministic generation of entangled coherent states for two atomic samples. In contrast with the previously proposed schemes of [Commun. Theor. Phys. 40 (2003) 103 and Chin. Phys. B 18 (2009) 1045], the required interaction time in our scheme is greatly shortened and thus the decoherence can be effectively suppressed.

Lin, Xiu

2010-05-01

216

Dissociation energy of the ground state of NaH  

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

217

Steady atomic entanglement in cavity QED without state initialization  

SciTech Connect

We present a scheme for realizing a steady entanglement state between two trapped atoms, without requiring the initialization of atom-cavity system nor fine time-controlling of evolution dynamics. We show that high-fidelity entanglement of atomic state can be obtained in a period of time equal to a few times the inverse of atomic's spontaneous decay rate. The robustness against cavity decay kappa and cavity thermal field n{sub T} has also been examined.

Zhang Shengli [Key Laboratory of Quantum Information, University of Science and Technology of China (CAS), Hefei 230026 (China); Electronic Technology Institute, Information Engineering University, Zhengzhou, Henan 450004 (China); Zou Xubo; Yang Song; Li Chuanfeng; Guo Guangcan [Key Laboratory of Quantum Information, University of Science and Technology of China (CAS), Hefei 230026 (China); Jin Chenhui [Electronic Technology Institute, Information Engineering University, Zhengzhou, Henan 450004 (China)

2009-12-15

218

Towards real spin glasses: Ground states and dynamics  

NASA Astrophysics Data System (ADS)

Spin glasses are paradigmatic examples of systems with quenched disorder. They fall out of equilibrium at sufficiently low temperatures, at which point their dynamics becomes extremely history-dependent. Despite thirty years of study, the nature of the possible spin glass phase remains controversial as does its relation to the way in which spatial structures and correlations evolve over time in an out-of-equilibrium spin glass. This thesis frames a set of broad underlying questions about spin-glass ground states and spin-glass dynamics and provides answers to some among them. First, the basic form of the spin-glass phase diagram is considered. A new scaling approach to experimental magnetic susceptibility data is introduced to investigate the controversial question of whether three-dimensional spin glasses undergo a phase transition in a field. Next, the nature of the spin glass phase is considered. A possible phase in short-range spin glasses exhibiting infinitely many equilibrium states is proposed and characterized in real space. Some models with correlations in their exchange interactions are argued to exhibit this phase and their potential relation to infinite-range models is discussed. The relation of out-of-equilibrium dynamics to underlying ground state structure is then explored. As time passes, a length scale over which the system is locally equilibrated must grow as must a length scale associated with regions of infinite system order. The relation between these two length scales is examined. Equilibration dynamics is considered for particular examples of spin-glass-like systems both with two ground states and with many ground states. Experiments with scanning probes in equilibrating systems are proposed. Identifying experimental signatures associated with different ground state structures are discussed and experimental ways to quantify the history-dependence of dynamics are suggested.

White, Olivia Lawrence

219

Electromagnetic Properties of the Three-Nucleon Ground State.  

National Technical Information Service (NTIS)

The electromagnetic form factors of the three-nucleon ground state are calculated on the base of an exact solution of the Faddeev equations. In a Hilbert space of nucleons and a possible delta -isobar the effects of a non-perturbative description of the d...

W. Strueve

1985-01-01

220

A Multilevel Model of XeF Ground State Kinetics.  

National Technical Information Service (NTIS)

A multilevel model of energy transfer is presented in the XeF ground electronic state due to collision-induced VT and dissociation processes. The model, whose parameters are based on experimental results presented here and on other recent data, should be ...

S. F. Fulghum M. S. Feld A. Javan

1977-01-01

221

Ground State Phase Diagram of Extended Attractive Hubbard Model.  

National Technical Information Service (NTIS)

The ground state phase diagram of the extended Hubbard model with intraatomic attraction has been derived in the Hartree-Fock approximation formulated in terms of the Bogoliubov variational approach. For a given value of electron density, the nature of th...

S. Robaszkiewicz K. A. Chao R. Micnas

1980-01-01

222

Regionalization of ground motion attenuation in the conterminous United States  

Microsoft Academic Search

Attenuation results from geometric spreading and from absorption. The former is almost independent of crustal geology or physiographic region. The latter depends strongly on crustal geology and the state of the earth's upper mantle. Except for very high-frequency waves, absorption does not affect ground motion at distances less than 25 to 50 km. Thus, in the near-field zone, the attenuation

D. H. Chung; D. L. Bernreuter

1979-01-01

223

Nitrate Behavior in Ground Waters of the Southeastern United States  

Microsoft Academic Search

Principal components analysis (PCA) was performed with water-quality data from studies conducted during 1993-1995 to explore potential nitrate-attenuation processes in ground waters of the southeastern United States. Nitrate reduction is an important attenuation process in selected areas of the Southeast. A \\

Bernard T. Nolan

224

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 (-?)su+V(x)u=f(x,u) in RN, 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

225

Rigorous lower bounds for the ground state energy of matter  

Microsoft Academic Search

Rigorous lower bounds are derived for the exact ground state energy of neutral matter of bosonic and fermionic types with Coulomb interactions with fixed positive charges by using, in the process, lower bounds for the kinetic energies as some power of an integral of ?2 rather than of the familiar ?5\\/3, where ? is the particle density. This method, while

E. B. Manoukian; S. Sirininlakul

2004-01-01

226

Intermolecular Raman bands in the ground state of benzene dimer  

SciTech Connect

Mass-selective, ionization-detected stimulated Raman spectroscopies have been applied to a study of low-frequency structure in the ground states of benzene dimer isotopomers. The results reveal two Raman bands below 10 cm[sup [minus]1], as well as structure in the range of 47 to 53 cm[sup [minus]1]. Tentative assignments for the bands are proposed.

Venturo, V.A.; Felker, P.M. (Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569 (United States))

1993-07-01

227

VOLUME PROPERTIES OF GROUND-STATE NUCLEAR MATTER  

Microsoft Academic Search

An approximation for treating macroscopic bound systems in the ground ; state is applied to a homogeneous system of nuclear matter using a simple ; separable potential. More extensive numerical results are given for the density, ; energy density, chemical potential, effective potential, momentum distribution, ; pressure, and density correlation function. In addition, an ambiguity in the ; calculation of

John Reynolds; Robert Puff

1963-01-01

228

Ground-state properties of nanographite systems with zigzag edges  

NASA Astrophysics Data System (ADS)

A ?-electron network in nanographite systems with zigzag edges exhibits strongly localized edge states, which are expected to have peculiar properties. We study effects of electron-electron interactions on ground-state properties of zigzag nanographite ribbons and open-ended zigzag nanotubes by means of the weak-coupling renormalization group and the density-matrix renormalization-group method. It is shown that the ground state is a spin-singlet Mott insulator with finite charge and spin gaps. We also find that the edge states are robust against the electronic correlations, resulting in edge-effective spins that can flip almost freely. The schematic picture for the low-energy physics of the systems is discussed.

Hikihara, Toshiya; Hu, Xiao; Lin, Hsiu-Hau; Mou, Chung-Yu

2003-07-01

229

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

230

Experimental evidence for the 8B ground state configuration  

Microsoft Academic Search

The 7Be fragments produced in one-proton removal from relativistic 8B nuclei of 936 MeV\\/nucleon in a carbon target have been detected in coincidence with ? rays emitted by these fragments at the reaction target. It is found that 13±3% of the 7Be fragments are released in the 429 keV excited state, 7Be?, which gives direct experimental information on the ground state configuration of 8B.

D. Cortina-Gil; K. Markenroth; F. Attallah; T. Baumann; J. Benlliure; M. J. G. Borge; L. V. Chulkov; U. Datta Pramanik; J. Fernandez-Vazquez; C. Forssén; L. M. Fraile; H. Geissel; J. Gerl; F. Hammache; K. Itahashi; R. Janik; B. Jonson; S. Karlsson; H. Lenske; S. Mandal; M. Meister; X. Mocko; G. Münzenberg; T. Ohtsubo; A. Ozawa; Y. Parfenova; V. Pribora; K. Riisager; H. Scheit; R. Schneider; K. Schmidt; G. Schrieder; H. Simon; B. Sitar; A. Stolz; P. Strmen; K. Sümmerer; I. Szarka; S. Wan; H. Weick; M. Zhukov

2002-01-01

231

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

SciTech Connect

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

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

2010-08-15

232

On the triplet ground state of tetrahedral X4 clusters (X = Li, Na, K, Cu).  

PubMed

The lowest electronic state of distorted tetrahedral X(4) clusters (with X = Li, Na, K, Cu) is studied at coupled-cluster level using high-quality atomic basis sets. The ground state is found to have a triplet spin symmetry for this kind of geometry and for all the considered atomic species. The equilibrium geometries correspond to Jahn-Teller-distorted oblate tetrahedra having D(2d) symmetry, and tetrahedric structures are local minima on the potential-energy surfaces for the triplet states. Their energies lie between 0.2 eV (for the K(4) cluster) and 0.9 eV (for Cu(4)) above the absolute minimum of the corresponding systems, which is a spin singlet having a rhombus geometry. PMID:22401434

Verdicchio, Marco; Evangelisti, Stefano; Leininger, Thierry; Monari, Antonio

2012-03-01

233

Positronic Lithium, an Electronically Stable Li-{ital e}{sup + } Ground State  

SciTech Connect

Calculations of the positron-Li system were performed using the stochastic variational method, yielding a minimum energy of {minus}7.53208 hartree for the L=0 ground state. In contrast with previous calculations of this system, the system was found to be stable against dissociation into the Ps+Li{sup +} channel with a binding energy of 0.00217 hartree; it is therefore electronically stable. This is the first instance of a rigorous calculation predicting that it is possible to combine a positron with a neutral atom to form an electronically stable bound state. {copyright} {ital 1997} {ital The American Physical Society}

Ryzhikh, G.G.; Mitroy, J. [Faculty of Science, Northern Territory University, Darwin NT 0909 (Australia)

1997-11-01

234

Slow-light probe of Fermi pairing through an atom-molecule dark state  

SciTech Connect

We consider the two-color photoassociation of a quantum degenerate atomic gas into ground-state diatomic molecules via a molecular dark state. This process can be described in terms of a {Lambda} level scheme that is formally analogous to the situation in electromagnetically induced transparency in atomic systems and therefore can result in slow-light propagation. We show that the group velocity of the light field depends explicitly on whether the atoms are bosons or fermions, as well as on the existence or absence of a pairing gap in the case of fermions, so that the measurement of the group velocity realizes a nondestructive diagnosis of the atomic state and the pairing gap.

Jing, H. [Department of Physics, Henan Normal University, Xinxiang 453007 (China); B2 Institute, Department of Physics and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Deng, Y. [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Meystre, P. [B2 Institute, Department of Physics and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States)

2011-06-15

235

Magnetic behavior of curium dioxide with a nonmagnetic ground state  

NASA Astrophysics Data System (ADS)

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

Niikura, Fumiaki; Hotta, Takashi

2011-05-01

236

Producing translationally cold, ground-state CO molecules.  

PubMed

Carbon monoxide molecules in their electronic, vibrational, and rotational ground state are highly attractive for trapping experiments. The optical or ac electric traps that can be envisioned for these molecules will be very shallow, however, with depths in the sub-milliKelvin range. Here, we outline that the required samples of translationally cold CO (X(1)?(+), v'' = 0, N'' = 0) molecules can be produced after Stark deceleration of a beam of laser-prepared metastable CO (a(3)?(1)) molecules followed by optical transfer of the metastable species to the ground state via perturbed levels in the A(1)? state. The optical transfer scheme is experimentally demonstrated and the radiative lifetimes and the electric dipole moments of the intermediate levels are determined. PMID:21950855

Blokland, Janneke H; Riedel, Jens; Putzke, Stephan; Sartakov, Boris G; Groenenboom, Gerrit C; Meijer, Gerard

2011-09-21

237

Ground-state properties of fermionic mixtures with mass imbalance in optical lattices  

NASA Astrophysics Data System (ADS)

Ground-state properties of fermionic mixtures confined in a one-dimensional optical lattice are studied numerically within the spinless Falicov-Kimball model with a harmonic trap. A number of remarkable results are found. i) At low particle filling the system exhibits phase separation with heavy atoms in the center of the trap and light atoms in the surrounding regions. ii) Insulating phases always coexist with metallic phases. iii) Atomic-density waves are observed in the insulating regions for all particle fillings near the half-filled lattice case. iv) The variance of the local density exhibits universal behavior (independent of the particle filling, the Coulomb interaction and the strength of a confining potential) over the whole region of the local density values.

Farkašovský, P.

2008-11-01

238

Observation of dynamical localization in atomic momentum transfer: A new testing ground for quantum chaos  

NASA Astrophysics Data System (ADS)

We report a direct observation of dynamical localization. This effect is a quantum suppression of diffusion in a system that is classically chaotic. Our experiment measures the momentum transferred from a modulated standing wave of a near-resonant laser to a sample of ultracold atoms and is a realization of a periodically driven rotor. The conceptual simplicity and experimental control over the time dependent Hamiltonian make this system an ideal testing ground for the predictions of quantum chaos.

Moore, F. L.; Robinson, J. C.; Bharucha, C.; Williams, P. E.; Raizen, M. G.

1994-11-01

239

Reply to 'Comment on 'Ground state of octahedral platinum hexafluoride''  

SciTech Connect

It is shown that the comments of Gabuda and Kozlova [Phys. Rev. A 79, 056501 (2009)] are in conflict with their earlier work [S. P. Gabuda et al., JETP Lett. 73, 35 (2001)], where they stated that there is no indication of the structural distortions in PtF{sub 6}. In their original publication they also stated that qualitative electrostatic considerations suggest that the electronic 5d{sup 4} configuration remains spin paired as the ground state in the octahedral field00.

Alvarez-Thon, Luis [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avenida Republica 275, 8370146 Santiago (Chile); Arratia-Perez, Ramiro [Departamento de Ciencias Quimicas, Universidad Andres Bello, Avenida Republica 275, 8370146 Santiago (Chile); Seppelt, Konrad [Institut fur Biochemie, Freie Universitaet Berlin, Fabeckstrasse 34/36, 14195 Berlin (Germany)

2009-05-15

240

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

Microsoft Academic Search

We investigate single ions of $^{40}Ca^+$ in Paul traps for quantum information processing. Superpositions of the S$_{1\\/2}$ electronic ground state and the metastable D$_{5\\/2}$ state are used to implement a qubit. Laser light on the S$_{1\\/2} \\\\leftrightarrow$ D$_{5\\/2}$ transition is used for the manipulation of the ion's quantum state. We apply sideband cooling to the ion and reach the ground

F. Schmidt-Kaler; Ch. Roos; H. C. Nägerl; H. Rohde; S. Gulde; A. Mundt; M. Lederbauer; G. Thalhammer; Th. Zeiger; P. Barton; L. Hornekaer; G. Reymond; D. Leibfried; J. Eschner; R. Blatt

2000-01-01

241

Coherence and entanglement in the ground state of a bosonic Josephson junction: From macroscopic Schroedinger cat states to separable Fock states  

SciTech Connect

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

242

Dynamical generation of electron motions in ground state H2+, in ground state H2 and in the first excited state of H2  

Microsoft Academic Search

Using the recent formulation of Gell-Mann and Hartle for approximating quantum dynamical phenomena by means of classical equations, we simulate electron motions in ground state H2+, in ground state H2, and in the first excited state of H2. The approach develops approximate initial data first by mathematical bisection. The dynamical calculations are then carried out over short time intervals only,

David Greenspan

1997-01-01

243

Ground-state properties of a Bose-Einstein condensate in an optomechanical cavity  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the ground-state properties of a Bose-Einstein condensate in an optomechanical cavity, in which a nonlinear photon-phonon interaction is created through the radiation pressure. We find that this nonlinear photon-phonon interaction can enhance the macroscopic collective excitations, and more importantly, it can generate a phase, called the dynamical unstable phase, in a regime of strong interaction. Moreover, the transition from the superradiant phase to the dynamical unstable phase shows no breaking of symmetry but is an intrinsic transition governed only by the ground-state stability. The possible physical explanation is also illustrated. These predictions can be detected by measuring the atom population, the mean photon number, or the mean phonon number in experiments.

Lian, Jinling; Liu, Ni; Liang, J.-Q.; Chen, Gang; Jia, Suotang

2013-10-01

244

Guidelines for ground motion definition for the eastern United States  

SciTech Connect

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

245

Determination of ground state in potassium intercalated polyacenes  

NASA Astrophysics Data System (ADS)

Intercalated compounds of polycyclic aromatic hydrocarbons have been drawing much attention from the view point of new type of organic superconductors. The mechanism of superconductivity in these materials is still unclear, and therefore the true ground states with various carrier concentrations must be understood. The antiferromagnetic ground states were reported particularly on K-doped pentacene, a typical polyacene. In the present study, we focus on the synthesis and the magnetic properties of K-intercalated polyacenes, such as anthracene, tetracene, and pentacene. The improved synthetic method based on the conventional solid state reaction was employed to obtain high quality bulk samples. The X-ray powder diffraction profiles of doped samples showed new stable phases. Interestingly, a pronounced hump at 150 K was observed in the temperature dependence of magnetic susceptibility of K1anthracene. In ESR measurements the linewidth of the signals decreased significantly with a decrease in temperature below 150 K and no Pauli magnetic contribution was detected. These results clearly indicate that charge transfer occurs but the most stable ground state is still insulating via antiferromagnetic interactions. Further discussion will be made among these K-intercalated polyacenes.

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

2013-03-01

246

Quantum storage on subradiant states in an extended atomic ensemble  

SciTech Connect

A scheme for coherent manipulation of collective atomic states is developed such that total subradiant states, in which spontaneous emission is suppressed into all directions due to destructive interference between neighbor atoms, can be created in an extended atomic ensemble. The optimal conditions for creation of such states and suitability of them for quantum storage are discussed. It is shown that in order to achieve the maximum signal-to-noise ratio the shape of a light pulse to be stored and reconstructed using a homogeneously broadened absorption line of an atomic system should be a time-reversed regular part of the response function of the system. In the limit of high optical density, such pulses allow one to prepare collective subradiant atomic states with near flat spatial distribution of the atomic excitation in the medium.

Kalachev, Alexey [Zavoisky Physical-Technical Institute of the Russian Academy of Sciences, Sibirsky Trakt 10/7, Kazan 420029 (Russian Federation)

2007-10-15

247

Monte Carlo Ground State Energy for Trapped Boson Systems  

NASA Astrophysics Data System (ADS)

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

Rudd, Ethan; Mehta, N. P.

2012-06-01

248

Nuclear magnetic moment of the 143Ce ground state  

NASA Astrophysics Data System (ADS)

The nuclear magnetic moment of the 143Ce ground state (T1/2=33.0 h, I?=3/2-) has been measured with the technique of nuclear magnetic resonance on oriented nuclei (NMR-ON) at low temperature. A sample (143CeFe) was prepared by implanting into an Fe foil nuclei of mass number 143, which were separated from fission products with an on-line isotope separator. The NMR-ON spectra were obtained by detecting specific ? and ? rays, and the resonance frequency was thereby determined to be 84.3(1) MHz. Using the reported value of the hyperfine magnetic field at other Ce nuclei in Fe, the nuclear magnetic moment of the 143Ce ground state was determined to be \\|?\\|=0.43(1) ?N. This value is discussed based on a systematics of the magnetic moments of other N=85 nuclei.

Taniguchi, A.; Kawase, Y.; Ohkubo, Y.; Goto, J.; Ohtsubo, T.; Ohya, S.

2002-01-01

249

NEW GROUND-STATE MEASUREMENTS OF ETHYL CYANIDE  

SciTech Connect

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

Brauer, Carolyn S.; Pearson, John C.; Drouin, Brian J.; Yu, Shanshan [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)], E-mail: Carolyn.S.Brauer@jpl.nasa.gov

2009-09-01

250

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

SciTech Connect

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

251

First observation of the 13Li ground state  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

252

Quantum Discord in the Ground State of Spin Chains  

NASA Astrophysics Data System (ADS)

The ground state of a quantum spin chain is a natural playground for investigating correlations. Nevertheless, not all correlations are genuinely of quantum nature. Here we review the recent progress to quantify the "quantumness" of the correlations throughout the phase diagram of quantum spin systems. Focusing to one spatial dimension, we discuss the behavior of quantum discord (QD) close to quantum phase transitions (QPT). In contrast to the two-spin entanglement, pairwise discord is effectively long-ranged in critical regimes. Besides the features of QPT, QD is especially feasible to explore the factorization phenomenon, giving rise to nontrivial ground classical states in quantum systems. The effects of spontaneous symmetry breaking are also discussed as well as the identification of quantum critical points through correlation witnesses.

Sarandy, Marcelo S.; de Oliveira, Thiago R.; Amico, Luigi

2012-08-01

253

Quantum Discord in the Ground State of Spin Chains  

NASA Astrophysics Data System (ADS)

The ground state of a quantum spin chain is a natural playground for investigating correlations. Nevertheless, not all correlations are genuinely of quantum nature. Here we review the recent progress to quantify the "quantumness" of the correlations throughout the phase diagram of quantum spin systems. Focusing to one spatial dimension, we discuss the behavior of quantum discord (QD) close to quantum phase transitions (QPT). In contrast to the two-spin entanglement, pairwise discord is effectively long-ranged in critical regimes. Besides the features of QPT, QD is especially feasible to explore the factorization phenomenon, giving rise to nontrivial ground classical states in quantum systems. The effects of spontaneous symmetry breaking are also discussed as well as the identification of quantum critical points through correlation witnesses.

Sarandy, Marcelo S.; de Oliveira, Thiago R.; Amico, Luigi

2013-01-01

254

Ground State Electronic Destabilization via Hyperconjugation in Aspartate Aminotransferase  

PubMed Central

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

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

2012-01-01

255

Ground State Properties and Bubble Structure of Synthesized Superheavy Nuclei  

NASA Astrophysics Data System (ADS)

We calculate the ground state properties of recently synthesized superheavy elements (SHEs) from Z = 105-118 along with the predicted proton magic Z = 120. The relativistic and nonrelativistic mean field formalisms are used to evaluate the binding energy (BE), charge radius, quadrupole deformation parameter and the density distribution of nucleons. We analyzed the stability of the nuclei based on BE and neutron to proton ratio. We also studied the bubble structure which reveals the special features of the superheavy nuclei.

Singh, S. K.; Ikram, M.; Patra, S. K.

2013-01-01

256

Supplementary Information for: 'Spontaneous Skyrmion Ground States in Magnetic Metals'  

Microsoft Academic Search

Supplementary information for our manuscript, entitled 'Spontaneous Skyrmion Ground States of Magnetic Metals', cond-mat\\/0603103, is presented. The physical nature of the gradient terms of our generalized micromagnetic model for ferromagnets with softened longitudinal fluctuations is explained. The relationship of our micromagnetic model with the spin fluctuation theory of itinerant-electron magnets is discussed. Experimental estimates of the parameter eta, which accounts

U. K. Roessler; A. N. Bogdanov; C. Pfleiderer

2006-01-01

257

Quasi Gamma8 ground state of titanium-substituted alums  

Microsoft Academic Search

Due to the Jahn-Teller coupling of the Gamma 5g vibrational mode, the first-order contribution to the trigonal splitting is opposite and nearly equal to the second-order contribution. The resulting ground state is a quasi Gamma 8 quartet with a very small trigonal splitting. This model also explains the low-temperature magnetic properties of other titanium-substituted alums.

Y. H. Shing; D. Walsh

1974-01-01

258

Achieving ground state and enhancing entanglement by recovering information  

Microsoft Academic Search

For cavity-assisted optomechanical cooling experiments, it has been shown in\\u000athe literature that the cavity bandwidth needs to be smaller than the\\u000amechanical frequency in order to achieve the quantum ground state of the\\u000amechanical oscillator, which is the so-called resolved-sideband or good-cavity\\u000alimit. We provide a new but physically equivalent insight into the origin of\\u000asuch a limit: that

Haixing Miao; Stefan Danilishin; Helge Mueller-Ebhardt; Yanbei Chen

2010-01-01

259

Atomic dark states and motional entanglement in cavity QED  

Microsoft Academic Search

A destructive interference mechanism that protects atomic dark states from entanglement with undesirable motional degrees of freedom for atoms trapped inside an optical cavity is described in a number of examples. Estimates of the motional decoherence rate for dark states are given, and the rates are shown to be slower than naive Lamb-Dicke estimates would suggest. This may be practically

T. A. B. Kennedy; Peng Zhou

2001-01-01

260

Experimental Investigation of Excited-State Lifetimes in Atomic Ytterbium  

SciTech Connect

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

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

2011-11-15

261

Resonant collisions of sodium atoms in Rydberg states  

Microsoft Academic Search

A careful numerical solution of the equations of the two-state theory of resonant collisions is presented. The particular process investigated is that of collisions of two sodium atoms in Rydberg states in the presence of a weak static electric field for which measurements have been carried out recently. Dipole-dipole interaction between the atoms is assumed as the interaction responsible for

E. Fiordilino; G. Ferrante; B. M. Smirnov

1987-01-01

262

The liquid state of large clusters with pairwise atomic interactions  

Microsoft Academic Search

Formation of the liquid state for clusters with a pair interaction between atoms is examined within the framework of the void model, in which configurational excitation of atoms results from formation of voids. Void parameters are found from computer simulation by molecular dynamics methods for Lennard-Jones clusters and from real thermodynamic parameters of the liquid states of condensed inert gases.

R. S. Berry; B. M. Smirnov

2005-01-01

263

Quantum Monte Carlo method for the ground state of many-boson systems.  

PubMed

We formulate a quantum Monte Carlo (QMC) method for calculating the ground state of many-boson systems. The method is based on a field-theoretical approach, and is closely related to existing fermion auxiliary-field QMC methods which are applied in several fields of physics. The ground-state projection is implemented as a branching random walk in the space of permanents consisting of identical single-particle orbitals. Any single-particle basis can be used, and the method is in principle exact. We illustrate this method with a trapped atomic boson gas, where the atoms interact via an attractive or repulsive contact two-body potential. We choose as the single-particle basis a real-space grid. We compare with exact results in small systems and arbitrarily sized systems of untrapped bosons with attractive interactions in one dimension, where analytical solutions exist. We also compare with the corresponding Gross-Pitaevskii (GP) mean-field calculations for trapped atoms, and discuss the close formal relation between our method and the GP approach. Our method provides a way to systematically improve upon GP while using the same framework, capturing interaction and correlation effects with a stochastic, coherent ensemble of noninteracting solutions. We discuss various algorithmic issues, including importance sampling and the back-propagation technique for computing observables, and illustrate them with numerical studies. We show results for systems with up to N approximately 400 bosons. PMID:15600791

Purwanto, Wirawan; Zhang, Shiwei

2004-11-09

264

Scheme for approximate conditional teleportation of an unknown atomic state without the Bell-state measurement  

SciTech Connect

We propose a scheme for approximately and conditionally teleporting an unknown atomic state in cavity QED. Our scheme does not involve the Bell-state measurement and thus an additional atom is unnecessary. Only two atoms and one single-mode cavity are required. The scheme may be used to teleport the state of a cavity mode to another mode using a single atom. The idea may also be used to teleport the state of a trapped ion.

Zheng Shibiao [Department of Electronic Science and Applied Physics, Fuzhou University, Fuzhou 350002 (China)

2004-06-01

265

Exact Ground States of Correlated Electrons on Pentagon Chains  

NASA Astrophysics Data System (ADS)

We construct a class of exact ground states for correlated electrons on pentagon chains in the high density region and discuss their physical properties. In this procedure the Hamiltonian is first cast in a positive semidefinite form using composite operators as a linear combination of creation operators acting on the sites of finite blocks. In the same step, the interaction is also transformed to obtain terms which require for their minimum eigenvalue zero at least one electron on each site. The transformed Hamiltonian matches the original Hamiltonian through a nonlinear system of equations whose solutions place the deduced ground states in restricted regions of the parameter space. In the second step, nonlocal product wave functions in position space are constructed. They are proven to be unique ground states which describe non-saturated ferromagnetic and correlated half metallic states. These solutions emerge when the strength of the Hubbard interaction Ui is site-dependent inside the unit cell. In the deduced phases, the interactions tune the bare dispersive band structure such to develop an effective upper flat band. We show that this band flattening effect emerges for a broader class of chains and is not restricted to pentagon chains. For the characterization of the deduced solutions, uniqueness proofs, exact ground state expectation values for long-range hopping amplitudes and correlation functions are also calculated. The study of physical reasons which lead to the appearance of ferromagnetism has revealed a new mechanism for the emergence of an ordered phase, described here in detail. This works as follows: starting from a completely dispersive bare band structure, the interactions quench the kinetic energy, hence the ordered phase is obtained solely by a drastic decrease of the interaction energy. Since Ui are site dependent, this determinative decrease is obtained by a redistribution of the double occupancy di such to attain small di where the on-site Coulomb repulsion Ui is high, and vice versa. The kinetic energy quench leads to the upper effective flat band, whose role is to enhance by its degeneracy the switching to the ordered phase dictated and stabilized by the interactions present. It is shown that for this phenomenon to occur, a given degree of complexity is needed for the chain, and the mechanism becomes inactive when the Ui interactions are homogeneous, or are missing from the ground state wave function.

Gulácsi, Zsolt

2013-06-01

266

Ground-state degeneracy of correlated insulators with edges  

NASA Astrophysics Data System (ADS)

Using the topological flux insertion procedure, the ground-state degeneracy of an insulator on a periodic lattice with filling factor ?=p/q was found to be at least q -fold. Applying the same argument in a lattice with edges, we show that the degeneracy is modified by the additional edge density ?E associated with the open boundaries. To carry out this generalization we demonstrate how to distinguish between bulk and edge states, and follow how an edge modifies the thermodynamic limit of Oshikawa’s original argument. In particular, we also demonstrate that these edge corrections may even make an insulator with integer bulk filling degenerate.

Refael, Gil; Lin, Hsiu-Hau

2005-08-01

267

Dissociation energy of the ground state of NaH  

SciTech Connect

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

Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen [Department of Chemistry, National Cheng-Kung University, Tainan 70101, Taiwan (China); Chang, Yung-Yung; Tsai, Chin-Chun [Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan (China)

2010-07-28

268

Ground states of fermionic lattice Hamiltonians with permutation symmetry  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

269

Atom-Molecule Dark States in a Bose-Einstein Condensate  

SciTech Connect

We have created a dark quantum superposition state of a Rb Bose-Einstein condensate and a degenerate gas of Rb{sub 2} ground-state molecules in a specific rovibrational state using two-color photoassociation. As a signature for the decoupling of this coherent atom-molecule gas from the light field, we observe a striking suppression of photoassociation loss. In our experiment the maximal molecule population in the dark state is limited to about 100 Rb{sub 2} molecules due to laser induced decay. The experimental findings can be well described by a simple three mode model.

Winkler, K.; Thalhammer, G.; Theis, M.; Denschlag, J. Hecker [Institut fuer Experimentalphysik, Universitaet Innsbruck, 6020 Innsbruck (Austria); Ritsch, H. [Institut fuer Theoretische Physik, Universitaet Innsbruck, 6020 Innsbruck (Austria); Grimm, R. [Institut fuer Experimentalphysik, Universitaet Innsbruck, 6020 Innsbruck (Austria); Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck (Austria)

2005-08-05

270

Recording quantum properties of light in a long-lived atomic spin state: towards quantum memory.  

PubMed

We report an experiment on mapping a quantum state of light onto the ground state spin of an ensemble of Cs atoms with the lifetime of 2 ms. Recording of one of the two quadrature phase operators of light is demonstrated with vacuum and squeezed states of light. The sensitivity of the mapping procedure at the level of approximately 1 photon/sec per Hz is shown. The results pave the road towards complete (storing both quadrature phase observables) quantum memory for Gaussian states of light. The experiment also sheds new light on fundamental limits of sensitivity of the magneto-optical resonance method. PMID:12144466

Schori, C; Julsgaard, B; Sørensen, J L; Polzik, E S

2002-07-15

271

Ground states and resonance states of Ps- and He interacting with screened Coulomb (Yukawa) potentials  

NASA Astrophysics Data System (ADS)

We present a brief review for the recent investigations on the ground states and resonance states for dense plasma-embedded Ps- and He using screened Coulomb (Yukawa) potentials for the plasma effects. New results for the 1,3Se resonance states of He in plasmas are also reported.

Kar, Sabyasachi; Ho, Y. K.

2007-06-01

272

Ground-state configurations and unresolved transition arrays in extreme ultraviolet spectra of lanthanide ions  

SciTech Connect

Theoretical ground-state configurations of lanthanide ions calculated with the Cowan suite of codes are presented. Theoretical 4d-4f and 4p-4d spectra of Pd-like to Rb-like lanthanide ions calculated using the relativistic flexible atomic code are also shown. The effects of configuration interaction are investigated, and the results compare favorably with experiments in which, for increasing nuclear charge, strong emission peaks are observed to move toward shorter wavelength. The application of these strong emitters as extreme ultraviolet radiation sources, a topic of emerging interest, is discussed.

Kilbane, D.; O'Sullivan, G. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2010-12-15

273

Ground-state properties of Fermi gases in the strongly interacting regime.  

PubMed

The ground-state energies and pairing gaps in dilute superfluid Fermi gases have now been calculated with the quantum Monte Carlo method without detailed knowledge of their wave functions. However, such knowledge is essential to predict other properties of these gases such as density matrices and pair distribution functions. We present a new and simple method to optimize the wave functions of quantum fluids using the Green's function Monte Carlo method. It is used to calculate the pair distribution functions and potential energies of Fermi gases over the entire regime from atomic Bardeen-Cooper-Schrieffer superfluid to molecular Bose-Einstein condensation, spanned as the interaction strength is varied. PMID:16196838

Chang, S Y; Pandharipande, V R

2005-08-17

274

Ground-State Properties of Fermi Gases in the Strongly Interacting Regime  

SciTech Connect

The ground-state energies and pairing gaps in dilute superfluid Fermi gases have now been calculated with the quantum Monte Carlo method without detailed knowledge of their wave functions. However, such knowledge is essential to predict other properties of these gases such as density matrices and pair distribution functions. We present a new and simple method to optimize the wave functions of quantum fluids using the Green's function Monte Carlo method. It is used to calculate the pair distribution functions and potential energies of Fermi gases over the entire regime from atomic Bardeen-Cooper-Schrieffer superfluid to molecular Bose-Einstein condensation, spanned as the interaction strength is varied.

Chang, S.Y.; Pandharipande, V.R. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green St., Urbana, Illinois 61801 (United States)

2005-08-19

275

Ground state isomerization of a model green fluorescent protein chromophore.  

PubMed

The relationship between ground state cis-trans isomerization and protonation state is explored for a model green fluorescent protein chromophore, 4-hydroxybenzylidene-1,2-dimethylimidazolinone (HBDI). We find that the protonation state has only a modest effect on the free energy differences between cis and trans isomers and on the activation energies for isomerization. Specifically, the experimental free energy differences are 3.3, 8.8, and 9.6 kJ/mol for cationic, neutral, and anionic forms of HBDI, respectively, and the activation energies are 48.9, 54.8, and 54.8 kJ/mol for cationic, neutral, and anionic forms, respectively. Furthermore, these activation energies are much smaller than might be expected based on comparison with similar systems. These results suggest that there may be a sub-population of the chromophore, which is nearly equally accessible to all three protonation states, through which thermal isomerization may proceed. PMID:12914920

He, Xiang; Bell, Alasdair F; Tonge, Peter J

2003-08-14

276

Ground state analysis of magnetic nanographene molecules with modified edge  

NASA Astrophysics Data System (ADS)

We study spin states of edge modified nanographene molecules with rectangular and triangular shapes by first principle calculations using density functional theory (DFT) and Hartree-Fock (HF) methods with Møller-Plesset (MP) correlation energy correction at different levels. Anthracene (C14H10) and phenalenyl (C13H9), which contain three benzene rings combined in two different ways, can be considered as fragments of a graphene sheet. Carbon-based ferromagnetic materials are of great interest both in fundamental science and technological potential in organic spintronics devices. We show that non-magnetic rectangular molecules such as C14H10 can become ferromagnetic with high-spin state as the ground state by dihydrogenization of one of the zigzag edges, while triangular molecules such as C13H9 become ferromagnetic with high-spin state by dehydrogenization of one of the zigzag edges.

Gorjizadeh, Narjes; Ota, Norio; Kawazoe, Yoshiyuki

2013-03-01

277

Anomalous magnetic ground states of the cerium germanide system  

NASA Astrophysics Data System (ADS)

The temperature and magnetic field dependence of the electrical resistivity, specific heat and magnetization has been carried out for the highly correlated CeGex system with 1.518 ? x ? 2.0. This system exhibits a variety of remarkable physical properties. We have found five distinct regions with the same type of crystal structure with different sets of lattice parameters across this series. Interestingly, each of these regions has a different magnetic ground state. Samples in region I with 1.713 ? x ? 2.0 crystallize in an orthorhombically distorted tetragonal structure and exhibit two magnetic transitions with an antiferromagnetic transition at TN = 7.0 K and subsequently a ferromagnetic transition at TC = 4.3 K. The remaining four regions are isomorphic and crystallize in a tetragonal structure. Samples in region II with 1.664 ? x ? 1.711 have a single antiferromagnetic transition at TN = 7.0 K. Samples in regions III with 1.627 ? x ? 1.664 are ferromagnetic with TC = 5.3 K. Samples in region IV with 1.59 ? x ? 1.627 are also ferromagnetic at a higher transition temperature TC = 7.0 K. Samples in region V with 1.518 ? x ? 1.59 return to a two magnetic transition scheme, similar to region I, with an antiferromagnetic transition at TN = 11.5 K and a ferromagnetic transition at TC = 7.0 K. The results of the high temperature susceptibility show that the cerium ions are trivalent throughout the series. Calculations of the entropy removal from the specific heat measurements indicate a doublet ground state for the 4f electrons. Moreover, the electronic specific heat coefficients deduced from temperatures above the magnetic phase transitions are enhanced compared to those of normal metals. The antiferromagnetic state in regions I, II and V undergoes a metamagnetic transition at a high magnetic field. This together with the change in magnetic ordered states across the CeGex series show that this is a magnetically frustrated system. It is believed that the change in Ce-Ce inter ion spacing leads to the change in the magnetic ground state across the series. The variation of antiferromagnetic and ferromagnetic ground states can best be described by the RKKY interaction between the localized 4f electrons mediated by the conduction electrons.

Zan, Jason A.

278

Observing quantum oscillation of ground states in single molecular magnet.  

PubMed

Single molecular magnets (SMMs) are among the potential systems for quantum memory and quantum information processing. Quantum coherence and oscillation are critical for these applications. The ground-state quantum coherence and Rabi oscillations of the SMM V15 ([V15(IV)As6(III)O42(H2O)]6-) have been studied in this context. We have affirmatively measured at 2.4 K the Rabi quantum oscillations and coherence time T2 for the ground states of the V15 ion of collective spin S=1/2, in addition to confirming the previously reported results for the S=3/2 excited states. The oscillations of S=3/2 and S=1/2 states are of different frequencies, and so can be separately selected for purposive manipulations. T2 of 188±4??ns (S=3/2) and 149±10??ns (S=1/2) are much less than T1?12???s and are further extendible via various approaches for qubit implementations. PMID:23003928

Yang, Jiahui; Wang, Ya; Wang, Zixiang; Rong, Xing; Duan, Chang-Kui; Su, Ji-Hu; Du, Jiangfeng

2012-06-04

279

Anomalous ground state of the electrons in nanoconfined water.  

PubMed

Water confined on the scale of 20 Å, is known to have different transport and thermodynamic properties from that of bulk water, and the proton momentum distribution has recently been shown to have qualitatively different properties from that exhibited in bulk water. The electronic ground state of nanoconfined water must be responsible for these anomalies but has so far not been investigated. We show here for the first time, using x-ray Compton scattering and a computational model, that the ground state configuration of the valence electrons in a particular nanoconfined water system, Nafion, is so different from that of bulk water that the weakly electrostatically interacting molecule model of water is clearly inapplicable. We argue that this is a generic property of nanoconfinement. The present results demonstrate that the electrons, and hence the protons as well, of nanoconfined water are in a distinctly different quantum state from that of bulk water. Biological cell function must make use of the properties of this state and cannot be expected to be described correctly by empirical models based on the weakly interacting molecules model. PMID:23909351

Reiter, G F; Deb, Aniruddha; Sakurai, Y; Itou, M; Krishnan, V G; Paddison, S J

2013-07-19

280

Scheme for teleportation of atomic states within cavities in thermal states  

NASA Astrophysics Data System (ADS)

An experimentally feasible scheme is proposed for the teleportation of an atomic state and of a two-atom entangled state within the microwave cavity quantum electrodynamics with unit probability of success. Our scheme is based on the interaction between atoms and a single-mode nonresonant cavity with the assistance of a strong classical driving field. Thus the teleportation scheme is insensitive to the thermal state. This idea can also be used to teleport an arbitrary two-atom pure state via two pairs of atomic Einstein-Podolsky-Rosen states in a straightforward way.

Liu, Jin-Ming; Weng, Bo; Xia, Yong

2006-08-01

281

Klf4 reverts developmentally programmed restriction of ground state pluripotency.  

PubMed

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

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

2009-02-18

282

Earthquake Ground Motion Simulations in the Central United States  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

283

Reversible State Transfer between Light and a Single Trapped Atom  

SciTech Connect

We demonstrate the reversible mapping of a coherent state of light with a mean photon number n{approx_equal}1.1 to and from the hyperfine states of an atom trapped within the mode of a high-finesse optical cavity. The coherence of the basic processes is verified by mapping the atomic state back onto a field state in a way that depends on the phase of the original coherent state. Our experiment represents an important step toward the realization of cavity QED-based quantum networks, wherein coherent transfer of quantum states enables the distribution of quantum information across the network.

Boozer, A. D.; Boca, A.; Miller, R.; Northup, T. E.; Kimble, H. J. [Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, California 91125 (United States)

2007-05-11

284

Quantum state restoration and single-copy tomography for ground states of Hamiltonians.  

PubMed

Given a single copy of an unknown quantum state, the no-cloning theorem limits the amount of information that can be extracted from it. Given a gapped Hamiltonian, in most situations it is impractical to compute properties of its ground state, even though in principle all the information about the ground state is encoded in the Hamiltonian. We show in this Letter that if you know the Hamiltonian of a system and have a single copy of its ground state, you can use a quantum computer to efficiently compute its local properties. Specifically, in this scenario, we give efficient algorithms that copy small subsystems of the state and estimate the full statistics of any local measurement. PMID:21231156

Farhi, Edward; Gosset, David; Hassidim, Avinatan; Lutomirski, Andrew; Nagaj, Daniel; Shor, Peter

2010-11-04

285

Chemical generation of a population inversion between the spin-orbit states of atomic iodine  

Microsoft Academic Search

An experiment is described in which metastable O2 was produced chemically by the reaction between chlorine fluorosulfate and hydrogen peroxide. Molecular iodine was then injected into a flowing stream of this oxygen, and the resulting population inversion between ground-state and excited iodine atoms was monitored by means of an optical double-resonance technique. Experimental data are presented which indicate that a

A. T. Pritt Jr.; R. D. Coombe; D. Pilipovich; R. I. Wagner; D. Benard; C. Dymek

1977-01-01

286

Quantum Storage in Solid State Atomic Ensembles  

Microsoft Academic Search

Reversible and coherent mapping of quantum information between light and matter is an important experimental challenge in quantum information science. In particular such quantum memories are necessary for the implementation of quantum repeaters that would extend the range of quantum communication. In recent years, atomic ensembles have proven to be a promising system in order to implement such a task.

Hugues de Riedmatten

2008-01-01

287

Adiabatic creation of atomic squeezing in dark states versus decoherences  

SciTech Connect

We study the multipartite correlations of the multiatom dark states, which are characterized by the atomic squeezing beyond the pairwise entanglement. It is shown that, in the photon storage process with atomic ensemble via the electromagnetically induced transparency (EIT) mechanism, the atomic squeezing and the pairwise entanglement can be created by adiabatically manipulating the Rabi frequency of the classical light field on the atomic ensemble. We also consider the sudden death for the atomic squeezing and the pairwise entanglement under various decoherence channels. An optimal time for generating the greatest atomic squeezing and pairwise entanglement is obtained by studying in detail the competition between the adiabatic creation of quantum correlation in the atomic ensemble and the decoherence that we describe with three typical decoherence channels.

Gong, Z. R.; Sun, C. P. [Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang Xiaoguang [Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027 (China)

2010-07-15

288

Nonplanar ground states of frustrated antiferromagnets on an octahedral lattice  

NASA Astrophysics Data System (ADS)

We consider methods to identify the classical ground state for an exchange-coupled Heisenberg antiferromagnet on a non-Bravais lattice with interactions Jij to several neighbor distances. Here, we apply this to the unusual “octahedral” lattice in which spins sit on the edge midpoints of a simple cubic lattice. Our approach is informed by the eigenvectors of Jij, taken as a matrix, having the largest eigenvalues. We discovered two families of noncoplanar states: (i) two kinds of commensurate states with cubic symmetry, each having twelve sublattices with spins pointing in (1,1,0) directions in spin space (modulo a global rotation) and (ii) varieties of incommensurate conic spiral. The latter family is addressed by projecting the three-dimensional lattice to a one-dimensional chain, with a basis of two (or more) sites per unit cell.

Sklan, Sophia R.; Henley, Christopher L.

2013-07-01

289

Calculation of electron scattering from the ground state of ytterbium  

SciTech Connect

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

290

Parity Effect in Ground State Energies of Ultrasmall Superconducting Grains  

SciTech Connect

We study the superconductivity in small grains in the regime when the quantum level spacing {delta}{var_epsilon} is comparable to the gap {Delta}. As {delta}{var_epsilon} is increased, the system crosses over from superconducting to normal state. This crossover is studied by calculating the dependence of the ground state energy of a grain on the parity of the number of electrons. The states with odd numbers of particles carry an additional energy {Delta}{sub P}, which shows nonmonotonic dependence on {delta}{var_epsilon}. Our predictions can be tested experimentally by studying the parity-induced alternation of Coulomb blockade peak spacings in grains of different sizes. {copyright} {ital 1997} {ital The American Physical Society}

Matveev, K. [Department of Physics, Duke University, Durham, North Carolina 27708-0305 (United States); Matveev, K. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Larkin, A. [Theoretical Physics Institute, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Larkin, A. [L.D. Landau Institute for Theoretical Physics, 117940 Moscow (Russia)

1997-05-01

291

Hartree-Fock Ground State Phase Diagram of Jellium  

NASA Astrophysics Data System (ADS)

We calculate the ground state phase diagram of the homogeneous electron gas in three dimensions within the Hartree-Fock approximation and show that broken symmetry states are energetically favored at any density against the homogeneous Fermi gas state with isotropic Fermi surface. At high density, we find metallic spin-unpolarized solutions where electronic charge and spin density form an incommensurate crystal having more crystal sites than electrons. For rs?0, our solutions approach pure spin-density waves, whereas the commensurate Wigner crystal is favored at lower densities, rs?3.4. Decreasing the density, the system undergoes several structural phase transitions with different lattice symmetries. The polarization transition occurs around rs?8.5.

Baguet, L.; Delyon, F.; Bernu, B.; Holzmann, M.

2013-10-01

292

Hartree-Fock Study on Magnetic Ground State of Uranium 5f Orbital in Ferromagnetic US  

NASA Astrophysics Data System (ADS)

We study the magnetic ground state of the uranium 5f orbital of ferromagnetic US on the basis of a realistic multi-band tight-binding Hartree-Fock (HF) model, in which uranium 5f, 6d and 7s and sulfur 3s and 3p orbitals and full degeneracy of each orbital are considered. The multipole 5f-5f Coulomb interaction on the uranium site is treated within HF approximation and the spin-orbit interaction of the uranium 5f electron is explicitly included. The magnetic moment of US is widely believed to be dominated by its orbital component M_l, which is about twice as large as the spin counterpart Ms with the opposite sign, indicating that the magnetic ground state is not close to the atomic limit. Our HF model can describe well the magnetic ground state of US ( M_total ~= 1.8?B and Ml / Ms ~= -2), while an LSDA band-structure calculation underestimates the orbital moment considerably (T. Kraft et al.), Phys. Rev. B52, 3561 (1995). Calculations of the XMCD spectrum at uranium M_4,5 edge (S. P. Collins et al.), J. Phys.: Condens. Matter 7, 9325 (1995) are presented and the validity of our model for US is discussed. This work is supported by JSPS Research Fellowships for Young Scientists.

Shishidou, T.; Oguchi, T.; Jo, T.

1997-03-01

293

7-Hydroxyquinoline-8-carbaldehydes. 1. Ground- and Excited-State Long-Range Prototropic Tautomerization.  

PubMed

Ground- and excited-state long-range prototropic tautomerization were studied for a series of 7-hydroxyquinoline-8-carbaldehydes (7-HQCs) by (1)H and (13)C NMR spectroscopy, photostationary and time-resolved UV-vis spectroscopic methods, and quantum chemical computations. These molecules represent trifunctional proton-donating/accepting systems that have been proposed to serve as models of a reversible optically driven molecular switch composed of two moieties: a molecular "frame" (7-hydroquinolines, 7-HQs) and a proton "crane" (carbaldehyde group). The NMR and electronic absorption spectra indicate a solvent-dependent equilibrium between two tautomeric forms, OH (7-quinolinol)) and NH (7(1H)-quinolinone), already in the ground state of all the compounds under study (7-hydroxy-2-methoxy-4-methylquinoline-8-carbaldehyde, HMMQC, shows only a trace of the NH form in highly polar and/or protic media). Electronic absorption and fluorescence of 7-HQCs are rationalized in terms of the ground- and excited-state hydrogen atom transfer (HAT). This process was identified by comparing the UV-vis spectroscopic properties of 7-HQCs with those of 7-HQs, synthetic precursors of the former, as well as with the characteristics of corresponding protonated cations and deprotonated anions (part 2). The experimental results are corroborated by the density functional theory (DFT) and ab initio computations, which shed some light on the differences in photophysics between variously substituted 7-HQCs. PMID:24025131

Vetokhina, Volha; Nowacki, Jacek; Pietrzak, Mariusz; Rode, Micha? F; Sobolewski, Andrzej L; Waluk, Jacek; Herbich, Jerzy

2013-09-11

294

Quantum teleportation of an arbitrary superposition of atomic Dicke states  

SciTech Connect

We propose a scheme for teleporting an arbitrary superposition of entangled Dicke states of any number of atoms (qubits) between two distant cavities. Our method relies on adiabatic passage using multi-atom dark states in each cavity, and a conditional detection of photons leaking out of both cavities. The ideal success probability of the protocol decreases polynomially in the number of atoms. The fidelity is unity for a single Dicke state, and can be optimized for the superposition by unitary postprocessing. Issues of experimental feasibility and applications to quantum informatics are discussed.

Di Tiegang; Muthukrishnan, Ashok; Zubairy, M. Suhail [Department of Physics and Institute for Quantum Studies, Texas A and M University, Texas 77843 (United States); Scully, Marlan O. [Department of Physics and Institute for Quantum Studies, Texas A and M University, Texas 77843 (United States); Departments of Chemistry and Aerospace and Mechanical Engineering, Princeton University, New Jersey 08544 (United States)

2005-06-15

295

Entanglement of large atomic samples: A Gaussian-state analysis  

SciTech Connect

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

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

2005-03-01

296

Ground-state electronic structure of actinide monocarbides and mononitrides  

NASA Astrophysics Data System (ADS)

The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm) , and the actinide mononitrides, AN. The electronic structure is characterized by a gradually increasing degree of f electron localization from U to Cm, with the tendency toward localization being slightly stronger in the (more ionic) nitrides compared to the (more covalent) carbides. The itinerant band picture is found to be adequate for UC and acceptable for UN, while a more complex manifold of competing localized and delocalized f -electron configurations underlies the ground states of NpC, PuC, AmC, NpN, and PuN. The fully localized 5f -electron configuration is realized in CmC (f7) , CmN (f7) , and AmN (f6) . The observed sudden increase in lattice parameter from PuN to AmN is found to be related to the localization transition. The calculated valence electron densities of states are in good agreement with photoemission data.

Petit, L.; Svane, A.; Szotek, Z.; Temmerman, W. M.; Stocks, G. M.

2009-07-01

297

Ground-state Electronic Structure of Actinide Monocarbides and Mononitrides  

SciTech Connect

The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm), and the actinide mononitrides, AN. The electronic structure is characterized by a gradually increasing degree of f electron localization from U to Cm, with the tendency toward localization being slightly stronger in the (more ionic) nitrides compared to the (more covalent) carbides. The itinerant band picture is found to be adequate for UC and acceptable for UN, while a more complex manifold of competing localized and delocalized f-electron configurations underlies the ground states of NpC, PuC, AmC, NpN, and PuN. The fully localized 5f-electron configuration is realized in CmC (f{sup 7}), CmN (f{sup 7}), and AmN (f{sup 6}). The observed sudden increase in lattice parameter from PuN to AmN is found to be related to the localization transition. The calculated valence electron densities of states are in good agreement with photoemission data.

Petit, Leon [ORNL; Svane, Axel [University of Aarhus, Denmark; Szotek, Zdzislawa [Daresbury Laboratory, UK; Temmerman, Walter M [Daresbury Laboratory, UK; Stocks, George Malcolm [ORNL

2009-01-01

298

Controlling the Hyperfine State of Rovibronic Ground-State Polar Molecules  

SciTech Connect

We report the preparation of a rovibronic ground-state molecular quantum gas in a single hyperfine state and, in particular, the absolute lowest quantum state. This addresses the last internal degree of freedom remaining after the recent production of a near quantum degenerate gas of molecules in their rovibronic ground state, and provides a crucial step towards full control over molecular quantum gases. We demonstrate a scheme that is general for bialkali polar molecules and allows the preparation of molecules in a single hyperfine state or in an arbitrary coherent superposition of hyperfine states. The scheme relies on electric-dipole, two-photon microwave transitions through rotationally excited states and makes use of electric nuclear quadrupole interactions to transfer molecular population between different hyperfine states.

Ospelkaus, S.; Ni, K.-K.; Quemener, G.; Neyenhuis, B.; Wang, D.; Miranda, M. H. G. de; Bohn, J. L.; Ye, J.; Jin, D. S. [JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

2010-01-22

299

Detecting Topological Order in a Ground State Wave Function  

SciTech Connect

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,d{sub i},F{sub lmn}{sup ijk},{delta}{sub 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=id{sub i}{sup 2}.

Levin, Michael; Wen Xiaogang [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2006-03-24

300

Modulated ground state of gravity theories with stabilized conformal factor  

NASA Astrophysics Data System (ADS)

We discuss the stabilization of the conformal factor by higher derivative terms in a conformally reduced R+R2 Euclidean gravity theory. The flat spacetime is unstable towards the condensation of modes with nonzero momentum, and they “condense” in a modulated phase above a critical value of the coupling ? of the R2 term. By employing a combination of variational, numerical and lattice methods, we show that in the semiclassical limit the corresponding functional integral is dominated by a single nonlinear plane wave of frequency ?1/??Pl. We argue that the ground state of the theory is characterized by a spontaneous breaking of translational invariance at Planckian scales.

Bonanno, A.; Reuter, M.

2013-04-01

301

Ground state of a resonantly interacting Bose gas  

SciTech Connect

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

Diederix, J. M.; Heijst, T. C. F. van; Stoof, H. T. C. [Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, NL-3584 CE Utrecht (Netherlands)

2011-09-15

302

Ground state of a resonantly interacting Bose gas  

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

303

Monogamy and ground-state entanglement in highly connected systems  

SciTech Connect

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

304

Ground state in a spin-one color superconductor  

SciTech Connect

Color superconductors in which quarks of the same flavor form Cooper pairs are investigated. These Cooper pairs carry total spin one. A systematic group-theoretical classification of possible phases in a spin-one color superconductor is presented, revealing parallels and differences to the theory of superfluid {sup 3}He. General expressions for the gap parameter, the critical temperature, and the pressure are derived and evaluated for several spin-one phases, with special emphasis on the angular structure of the gap equation. It is shown that the (transverse) color-spin-locked phase is expected to be the ground state.

Schmitt, Andreas [Institut fuer Theoretische Physik, J. W. Goethe-Universitaet, D-60054 Frankfurt (Germany)

2005-03-01

305

Experimental nuclear masses and the ground state of cold dense matter  

Microsoft Academic Search

We study the consequences of recent progress in the experimental determination of masses of neutron rich nuclei for our knowledge of the ground state of cold dense matter. The most recent experimental data determine the ground state of cold dense matter up to rho approximately equal to 1011 g cm-3. The composition and the equation of state of the ground

P. Haensel; B. Pichon

1994-01-01

306

Probabilistic teleportation of an unknown atomic state  

Microsoft Academic Search

We propose two schemes for teleporting an unknown state. In our schemes, a three-particle Greenberger-Horne-Zeilinger state is used as a quantum channel. We show that the probabilistic teleportation of an unknown quantum state can be realized.

Liu Ye; Guang-Can Guo

2002-01-01

307

Atoms versus photons as carriers of quantum states  

NASA Astrophysics Data System (ADS)

The problem of the complete transfer of quantum states and entanglement in a four-qubit system composed of two single-mode cavities and two two-level atoms is investigated. The transfer of single and double excitation states is discussed for two different coupling configurations between the qubits. In the first, the coupling is mediated by the atoms that simultaneously couple to the cavity modes. In the second configuration, each atom resides inside one of the cavities and the coupling between the cavities is mediated by the overlapping field modes. A proper choice of basis states makes it possible to identify states that could be completely transferred between themselves. Simple expressions are derived for the conditions for the complete transfer of quantum states and entanglement. These conditions impose severe constraints on the evolution of the system in the form of constants of motion. The constrains on the evolution of the system imply that not all states can evolve in time, and we find that the evolution of the entire system can be confined into that occurring among two states only. Detailed analysis show that in the case where the interaction is mediated by the atoms, only symmetric superposition states can be completely and reversibly transferred between the atoms and the cavity modes. In the case where the interaction is mediated by the overlapping field modes, both symmetric and antisymmetric superposition states can be completely transferred. We also show that the system is capable of generating purely photonic NOON states, but only if the coupling is mediated by the atoms, and demonstrate that the ability to generate the NOON states relies on perfect transfer of an entanglement from the atoms to the cavity modes.

Bougouffa, Smail; Ficek, Zbigniew

2013-08-01

308

Scheme for teleportation of an unknown atomic state without the Bell-state measurement  

SciTech Connect

We propose a scheme for teleporting an unknown atomic state in cavity QED. Our scheme does not involve the Bell-state measurement. During the interaction between atom and cavity, the cavity is only virtually excited and thus the scheme is insensitive to the cavity field states and cavity decay. The idea can also be used in the case of teleporting an unknown atomic entangled state.

Ye Liu [Key Laboratory of Quantum Information, University of Science and Technology of China and Chinese Academy of Sciences, Hefei 230026 (China); Department of Physics, Anhui University, Hefei 230039 (China); Guo Guangcan [Key Laboratory of Quantum Information, University of Science and Technology of China and Chinese Academy of Sciences, Hefei 230026 (China)

2004-11-01

309

Two-photon-two-atom excitation by correlated light states  

NASA Astrophysics Data System (ADS)

We study the efficiency of different two-photon states of light to induce the simultaneous excitation of two atoms of different kinds when the sum of the energies of the two photons matches the sum of the energies of the two atomic transitions, while no photons are resonant with each individual transition. We find that entangled two-photon states produced by an atomic cascade are indeed capable of enhancing by a large factor the simultaneous excitation probability as compared to uncorrelated photons, as predicted some years ago by Muthukrishnan , but that several unentangled, separable, correlated states, produced either by an atomic cascade or parametric down-conversion, or even appropriate combinations of coherent states, have comparable efficiencies. We show that the key ingredient for the increase of simultaneous excitation probability is the presence of strong frequency anticorrelation and neither time correlation nor time-frequency entanglement.

Zheng, Zhan; Saldanha, Pablo L.; Rios Leite, José R.; Fabre, Claude

2013-09-01

310

Atomic Hydrogen Maser Investigations of Hydrogen Atom Interactions from 4 K to 12 K.  

National Technical Information Service (NTIS)

Techniques developed during previous studies of the ground state hyperfine resonance of hydrogen atoms intermittently adsorbed on molecular hydrogen surfaces were used to develop a cryogenic atomic hydrogen maser using a 5 K state-selected H atom beam and...

S. B. Crampton

1986-01-01

311

Stimulated Raman scattering in atomic ensembles: Toward quantum state entanglement  

Microsoft Academic Search

Entanglement generation and verification are essential steps to achieve long-distance quantum communication with atomic ensembles according to some protocols. In this dissertation, new schemes for generating quantum state entanglement between two atomic ensembles by stimulated Raman scattering are proposed and analyzed under various practical factors such as linear dispersion, readout losses, and detector noise. In the photon-number-state entanglement scheme, new

Wenhai Ji

2007-01-01

312

On the nature of the oligoacene ground state  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

313

DNA-DNA interaction beyond the ground state  

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

314

Global analysis of chloromethane: determinability of ground state constants  

NASA Astrophysics Data System (ADS)

As part of a global analyis of the infrared spectrum of chloromethane, the region of the fifth polyad involving the upper states of seven interacting bands 2?6, ?2+?3, ?3+?5, 3?3, ?2+?6, ?5+?6, 2?3+?6, from 1900 to 2600 cm-1 has been re-investigated. More than 20 000 transitions for each isotopomer 12CH335Cl and 12CH337Cl have been assigned and fitted with a standard deviation better than 4 10-4 cm-1 close to the experimental precision. The present paper is focussed on the determination of the ground state constants of 12CH337Cl by exploiting in a global theoretical model perturbation-allowed transitions already observed for 12CH335Cl by Di Lauro and Alamichel (J. Mol. Spectrosc. 81, 390-412 (1980)).

Nikitin, Andrei V.; Champion, Jean-Paul; Burger, Hans

2004-01-01

315

Term energies of 1s2nf high Rydberg states for the lithium atom  

NASA Astrophysics Data System (ADS)

Ionization potentials and quantum defects of 1s2nf bound states and their adjacent continuum states for the lithium atom are calculated with the R-matrix theory; then the quantum defect function (QDF) of the 1s2nf channel is obtained, which varies smoothly with the energy based on the quantum defect theory. The original QDF is calibrated from a more accurate literature value and used to calculate quantum defects, ionization potentials and term energies (relative to the 1s22s ground state) of 1s2nf high Rydberg states of the lithium atom. The term energies in this work are, on the whole, in good agreement with the experimental data in the literature.

Chen, Chao

2013-10-01

316

The perfect atom: Bound states of supersymmetric quantum electrodynamics  

NASA Astrophysics Data System (ADS)

We study hydrogen-like atoms in N=1 supersymmetric quantum electrodynamics with an electronic and a muonic family. These atoms are bound states of an anti-muon and an electron or their superpartners. The exchange of a photino converts different bound states into each other. We determine the energy eigenstates and calculate the spectrum to fourth order in the fine structure constant. A difference between these perfect atoms and non-supersymmetric ones is the absence of hyperfine structure. We organize the eigenstates into supermultiplets of the underlying symmetry algebra.

Herzog, Christopher P.; Klose, Thomas

2010-11-01

317

Atomic states in optical traps near a planar surface  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the atomic states in a vertical optical lattice in proximity of a surface. We study the modifications to the ordinary Wannier-Stark states in the presence of a surface, and we characterize the energy shifts produced by the Casimir-Polder interaction between atom and mirror. In this context, we introduce an effective model describing the finite size of the atom in order to regularize the energy corrections. In addition, the modifications to the energy levels due to a hypothetical non-Newtonian gravitational potential as well as their experimental observability are investigated.

Messina, Riccardo; Pelisson, Sophie; Angonin, Marie-Christine; Wolf, Peter

2011-05-01

318

Atomic states in optical traps near a planar surface  

SciTech Connect

In this paper, we discuss the atomic states in a vertical optical lattice in proximity of a surface. We study the modifications to the ordinary Wannier-Stark states in the presence of a surface, and we characterize the energy shifts produced by the Casimir-Polder interaction between atom and mirror. In this context, we introduce an effective model describing the finite size of the atom in order to regularize the energy corrections. In addition, the modifications to the energy levels due to a hypothetical non-Newtonian gravitational potential as well as their experimental observability are investigated.

Messina, Riccardo; Pelisson, Sophie; Angonin, Marie-Christine; Wolf, Peter [LNE-SYRTE, Observatoire de Paris, CNRS UMR8630, UPMC 61 avenue de l'Observatoire, F-75014 Paris (France)

2011-05-15

319

Entangled states and information induced by the atom field interaction  

NASA Astrophysics Data System (ADS)

Some aspects of the entangled states generated through an atom field interaction through the Jaynes Cummings model are discussed. The separability and inseparability of these states are studied for different parameters of the model concerning the field and the atom. We calculated the minimum amount of entanglement contained in the inseparable state and compared it with the total correlation through the mutual entropy of the system. This entangled state is used in a teleportation procedure to send information from one place to another. The role played by the parameters of the Jaynes Cummings model in the entanglement and teleportation is investigated.

Metwally, N.; Abdelaty, M.; Obada, A.-S. F.

2005-06-01

320

Spin Correlations in Electron-Impact Excitation of the 2P-STATE of Atomic Hydrogen.  

NASA Astrophysics Data System (ADS)

Calculations have been carried out in the distorted -wave Born approximation for electron-impact excitation of the individual 2p fine-structure states of the hydrogen atom. Results are given for 54.4, 100, and 200 eV. The purpose was not to improve on existing more elaborate calculations of the state multipoles of the excited 2p states, but rather to investigate spin-related phenomena, such as an incident polarized beam, polarized target atoms, and the polarization of the scattered electrons when unpolarized electrons are incident on unpolarized target atoms. The bound state wave functions are constructed using the total angular momentum scheme, | JM_{J} > = sumlimits_{M_ {L}M_{S}}C(LSJ;M_ {L}M_{S}M_{J}) | LM_{L}SM_{S} >, and the Percival-Seaton hypothesis is not used. We then construct explicitly-spin-dependent scattering amplitudes. This approach is to be contrasted with previous calculations which use | LM_{L}SM_{S}> wave functions and assume that the sum of the electron spin projections is conserved in the collision, or with calculations which use uncoupled wave functions. The spin polarization of the scattered electrons resulting from scattering unpolarized electrons on unpolarized ground state hydrogen atoms (the 'fine-structure effect') is found to result here from interference of the direct and exchange scattering amplitudes. Distortion of the scattered waves by the atomic potential produces a nonzero component of the transferred angular momentum perpendicular to the scattering plane. This orbital angular momentum orientation of the excited atom is then transferred to the scattered electron via angular momentum algebra. The spin-orbit interaction in the excited atom is the origin of the spin polarization, since it produces a sufficient energy separation of the fine structure states to allow them to be studied separately.

Jain, Babu Lal

1995-01-01

321

Fractional quantum Hall states of a few bosonic atoms in geometric gauge fields  

NASA Astrophysics Data System (ADS)

We use the exact diagonalization method to analyze the possibility of generating strongly correlated states in two-dimensional clouds of ultracold bosonic atoms that are subjected to a geometric gauge field that was created by coupling two internal atomic states to a laser beam. On tuning the gauge field strength, the system undergoes stepwise transitions between different ground states (GSs), which we describe by using analytical trial wave functions, including the Pfaffian (Pf), the Laughlin and a Laughlin quasiparticle many-body state. Whereas for an infinitely strong laser field, the internal degree of freedom of the atoms can adiabatically follow their center-of-mass movement, a finite laser intensity gives rise to non-adiabatic transitions between the internal states, which are shown to break the cylindrical symmetry of the Hamiltonian. We study the influence of the asymmetry on the GS properties of the system. The main effect is to reduce the overlap of the numerical solutions with the analytical trial expressions by occupying states with higher angular momentum. Thus, we propose generalized wave functions arising from the Laughlin and Pf wave functions by including components where extra Jastrow factors appear while preserving important features of these states. We analyze quasihole excitations over the Laughlin and generalized Laughlin states and show that they possess effective fractional charge and obey anyonic statistics. Finally, we discuss the observability of the Laughlin state for increasing numbers of particles.

Juliá-Díaz, B.; Graß, T.; Barberán, N.; Lewenstein, M.

2012-05-01

322

Ground-state spin dynamics of ErCo2  

NASA Astrophysics Data System (ADS)

We have studied the ground-state magnetic excitation spectrum of ErCo2 at 4.2 K using neutron inelastic scattering. Four modes were observed, two which are nondispersive and two which are weakly dispersive. Each of the weakly dispersive modes is degenerate with one of the nondispersive modes at the zone boundary, but falls lower in energy at the zone center. From the dynamic structure factor of the excitations we conclude that the nondispersive modes correspond to out-of-phase precession of the two rare-earth spins in the primitive cell, while the weakly dispersive modes correspond to in-phase precession. The results are described very well by a Green's-function random-phase-approximation theory using standard basis operators to account for the crystalline electric fields, which we find to be comparable in strength to the exchange interactions. The observed excitation modes are associated with transitions from the Er3+ ground state to the second and fourth excited states. By fitting the energies and intensities of the modes we determine JEr-Er=0+/-0.01 meV, JEr-Co=-0.153 meV, A04=4.3 meV/a40, and A06=-0.142 meV/a60. We did not observe a predominantly Co spin-wave mode predicted by the theory, which may indicate a breakdown of the Heisenberg model when applied to the Co spins. Calculations for the observed modes, however, are nearly independent of the dynamics assumed for the Co sublattice.

Koon, N. C.; Rhyne, J. J.

1981-01-01

323

Single-Atom Gating of Quantum State Superpositions  

SciTech Connect

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

324

Schemes for atomic-state teleportation  

SciTech Connect

We present two schemes employing cavity QED phenomena to realize the teleportation of quantum states following the principle outlined by Bennett [ital et] [ital al]. [Phys. Rev. Lett. [bold 70], 1895 (1993)].

Cirac, J. (Departamento de Fisica Aplicada, Facultad de Ciencias Quimicas, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)); Parkins, A. (Fakultaet fuer Physik, Universitaet Konstanz, D-78434 Konstanz (Germany))

1994-12-01

325

Approximate and Conditional Teleportation of an Unknown Atomic-Entangled State Without Bell-State Measurement  

Microsoft Academic Search

A scheme for approximately and conditionally teleporting an unknown atomic-entangled state in cavity QED is proposed. It is the novel extension of the scheme of [Phys. Rev. A 69 (2004) 064302], where the state to be teleported is an unknown atomic state and where only a time point of system evolution and the corresponding fidelity implementing the teleportation are given.

Chen Chang-Yong; Li Shao-Hua

2007-01-01

326

Atomic quantum states with maximum localization on classical elliptical orbits  

Microsoft Academic Search

We show how to build atomic states that mimic the classical Bohr-Sommerfeld elliptic orbits with minimum quantum fluctuations. These elliptic states are uniquely defined from symmetry considerations. They are the coherent states of the SO(4) symmetry group of the Coulomb interaction in three dimensions and are superpositions of the usual spherical states with well-defined weights and phases. They can be

Jean-Claude Gay; Dominique Delande; Antoine Bommier

1989-01-01

327

Unexpected 5/2- spin of the ground state in 147Ba: No octupole deformation in ground states of odd-A Ba isotopes  

NASA Astrophysics Data System (ADS)

The 147Ba nucleus has been studied in prompt ?-ray spectroscopy using the EUROGAM2 Ge array. Spin and parity of the ground state has been determined to be 5/2-. The unexpected, 5/2- ground state results from interaction with other negative-parity configurations. A new ground-state band has been established in 147Ba and some previously reported levels have been arranged into a 3/2- band, which may correspond to the 3/2-[532] configuration. The new spin assignments in 147Ba suggest that the theoretical predictions of static octupole deformation in the ground state of 147Ba may not be be valid. No candidates for parity doublets have been found in 147Ba. Instead, an octupole band built on the ground state has been proposed.

Rz?ca-Urban, T.; Urban, W.; Smith, A. G.; Ahmad, I.; Syntfeld-Ka?uch, A.

2013-03-01

328

Ultraviolet photodissociation of the SD radical in vibrationally ground and excited states.  

PubMed

Ultraviolet (UV) photodissociation dynamics of the SD radical in vibrationally ground and excited states (X (2)Pi(3/2), v'' = 0-5) are investigated in the photolysis wavelength region of 220 to 244 nm using the high-n Rydberg atom time-of-flight (HRTOF) technique. The UV photodissociation dynamics of SD (X (2)Pi(3/2)) from v'' = 0-5 are similar to each other and to that of SH studied previously. The anisotropy parameter of the D-atom product is approximately -1; the spin-orbit branching fractions of the S((3)P(J)) products are essentially constant, with an average S((3)P(2)) : S((3)P(1)) : S((3)P(0)) = 0.51 : 0.37 : 0.12. The UV photolysis of SD is a direct dissociation from the repulsive (2)Sigma(-) state following the perpendicular (2)Sigma(-)-X (2)Pi excitation. The S((3)P(J)) product fine-structure state distributions approach that in the sudden limit dissociation on the single repulsive (2)Sigma(-) curve, but they are also affected by nonadiabatic couplings among the repulsive (4)Sigma(-), (2)Sigma(-), and (4)Pi states. A bond dissociation energy D(0)(S-D) = 29 660 +/- 25 cm(-1) is obtained. PMID:19492130

Zheng, Xianfeng; Wu, Jingze; Song, Yu; Zhang, Jingsong

2009-03-18

329

Atom laser based on Raman transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state is pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to another cavity for the atomic ground state. Above a certain threshold pumping rate a large

G. M. Moy; J. J. Hope; C. M. Savage

1997-01-01

330

An Atom Laser Based on Raman Transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state $|1 >$ are pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to a single mode of another cavity for the ground atomic state, $|2 >$.

G. M. Moy; J. J. Hope; C. M. Savage

1996-01-01

331

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Investigation of the populations of excited states of barium atoms in a laser plasma  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence was used in an investigation of the populations of the ground and excited (6s5d 3D1 and 3D2) states of Ba atoms in a plasma formed by laser ablation of Y—Ba—Cu—O target. A nonequilibrium velocity distribution of the atoms was detected. At large distances from the target about 4% of the atoms were in an excited state.

Burimov, V. N.; Zherikhin, A. N.; Popkov, V. L.

1995-02-01

332

Simultaneous benchmarking of ground- and excited-state properties with long-range-corrected density functional theory  

Microsoft Academic Search

We present benchmark calculations using several long-range-corrected (LRC) density functionals, in which Hartree–Fock exchange is incorporated asymptotically using a range-separated Coulomb operator, while local exchange is attenuated using an ansatz introduced by Iikura &etal; [J. Chem. Phys. 115, 3540 (2001)]. We calculate ground-state atomization energies, reaction barriers, ionization energies, and electron affinities, each as a function of the range-separation parameter

Mary A. Rohrdanz; John M. Herbert

2008-01-01

333

Simultaneous benchmarking of ground- and excited-state properties with long-range-corrected density functional theory  

Microsoft Academic Search

We present benchmark calculations using several long-range-corrected (LRC) density functionals, in which Hartree-Fock exchange is incorporated asymptotically using a range-separated Coulomb operator, while local exchange is attenuated using an ansatz introduced by Iikura et al. [J. Chem. Phys. 115, 3540 (2001)]. We calculate ground-state atomization energies, reaction barriers, ionization energies, and electron affinities, each as a function of the range-separation

Mary A. Rohrdanz; John M. Herbert

2008-01-01

334

Ground-state electric quadrupole moment of {sup 31}Al  

SciTech Connect

The ground-state electric quadrupole moment of {sup 31}Al(I{sup {pi}}=5/2{sup +},T{sub 1/2}=644(25) ms) has been measured by means of {beta}-ray-detected nuclear magnetic resonance spectroscopy using a spin-polarized {sup 31}Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q{sub exp}({sup 31}Al)|=112(32) e mb, 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 {sup 31}Al is located outside of the island of inversion.

Nagae, D.; Takemura, M.; Asahi, K.; Takase, K.; Shimada, K.; Uchida, M.; Arai, T.; Inoue, T.; Kagami, S.; Hatakeyama, N. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Ueno, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan); Kameda, D.; Yoshimi, A.; Sugimoto, T.; Nagatomo, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawamura, H.; Narita, K.; Murata, J. [Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan)

2009-02-15

335

Sideband cooling micromechanical motion to the quantum ground state  

NASA Astrophysics Data System (ADS)

Accessing the full quantum nature of a macroscopic mechanical oscillator first requires elimination of its classical, thermal motion. The flourishing field of cavity opto- and electromechanics provides a nearly ideal architecture for both preparation and detection of mechanical motion at the quantum level. We realize such a system by coupling the motion of an aluminum membrane to the resonance frequency of a superconducting, microwave circuit. By exciting the microwave circuit below its resonance frequency, we damp and cool the membrane motion with radiation pressure forces, analogous to laser cooling of trapped ions. The microwave excitation serves not only to cool, but also to monitor the displacement of the drum. A nearly shot-noise limited, microwave Josephson parametric amplifier is used to detect the mechanical sidebands of this microwave excitation and quantify the thermal motion of the oscillator as it is cooled with radiation pressure forces to its quantum ground state.

Teufel, John; Donner, Tobias; Li, Dale; Lehnert, Konrad; Simmonds, Raymond

2011-03-01

336

Antiferromagnetic Spin-S Chains with Exactly Dimerized Ground States  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

337

Ground states of dispersion-managed nonlinear Schrodinger equation  

PubMed

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

Zharnitsky; Grenier; Turitsyn; Jones; Hesthaven

2000-11-01

338

Unresolved Question of the He10 Ground State Resonance  

NASA Astrophysics Data System (ADS)

The ground state of He10 was populated using a 2p2n-removal reaction from a 59MeV/u Be14 beam. The decay energy of the three-body system, He8+n+n, was measured and a resonance was observed at E=1.60(25)MeV with a 1.8(4) MeV width. This result is in agreement with previous invariant mass spectroscopy measurements, using the Li11(-p) reaction, but is inconsistent with recent transfer reaction results. The proposed explanation that the difference, about 500 keV, is due to the effect of the extended halo nature of Li11 in the one-proton knockout reaction is no longer valid as the present work demonstrates that the discrepancy between the transfer reaction results persists despite using a very different reaction mechanism, Be14(-2p2n).

Kohley, Z.; Snyder, J.; Baumann, T.; Christian, G.; DeYoung, P. A.; Finck, J. E.; Haring-Kaye, R. A.; Jones, M.; Lunderberg, E.; Luther, B.; Mosby, S.; Simon, A.; Smith, J. K.; Spyrou, A.; Stephenson, S. L.; Thoennessen, M.

2012-12-01

339

Improved ground state rotational parameters of deuterium fluoride, DF  

NASA Astrophysics Data System (ADS)

The rotational spectrum of DF in the 1.3 3.3 THz frequency region has been observed by means of a tunable far-infrared spectrometer. The J + 1 ? J, with J = 1 4, rotational transitions of DF have been recorded with an accuracy of the order of 50 200 kHz. These measurements, in conjunction with the hyperfine components of the J = 1 ? 0 transition recently observed [Cazzoli and Puzzarini, J. Mol. Spectrosc. 231 (2005) 124 130] and the rotational transitions up to J = 47 [R.S. Ram, Z. Morbi, B. Guo, K.-Q. Zhang, P.F. Bernath, J. Vander Auwera, J.W.C. Johns, S.P. Davies, Astrophys. J. Suppl. Series 103 (1996) 247 254] consented to improve the ground state rotational parameters of DF.

Cazzoli, Gabriele; Puzzarini, Cristina; Tamassia, Filippo; Borri, Simone; Bartalini, Saverio

2006-02-01

340

Frustrated systems: Ground state properties via combinatorial optimization  

NASA Astrophysics Data System (ADS)

An introduction to the application of combinatorial optimization methods to ground state calculations of frustrated, disordered systems is given. We discuss the interface problem in the random bond Ising ferromagnet, the random field Ising model, the diluted antiferromagnet in an external field, the spin glass problem, the solid-on-solid model with a disordered substrte and other convex cost flow problems occurring in superconducting flux line lattices and traffic flow networks. On the algorithmic side we present a concise introduction to a number of elementary algorithms in combinatorial optimization, in particular network flows: the shortest path algorithm, the maximum-flow algorithms and minimum-cost-flow algorithms. We also take a glance at the minimum weighted matching and branch-and-cut algorithms.

Rieger, Heiko

341

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

342

Transition properties of low-lying states in atomic indium  

NASA Astrophysics Data System (ADS)

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. The lifetime of the [4p6]5s25p3/2 state in this atom is determined. Our 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.; Das, B. P.

2011-07-01

343

Transition properties of low-lying states in atomic indium  

SciTech Connect

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. The lifetime of the [4p{sup 6}]5s{sup 2}5p{sub 3/2} state in this atom is determined. Our 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.; Das, B. P. [Theoretical Physics Division, Physical Research Laboratory, Ahmedabad-380009 (India); Theoretical Astrophysics Group, Indian Institute of Astrophysics, Bangalore-560034 (India)

2011-07-15

344

Tensor Forces and the Ground-State Structure of Nuclei  

SciTech Connect

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

Rocco Schiavilla

2007-03-01

345

Ground state of gapless two flavor color superconductors  

SciTech Connect

This paper is devoted to the study of some aspects of the instability of two flavor color-superconductive quark matter. We find that, beside color condensates, the Goldstone boson related to the breaking of U(1){sub A} suffers from a velocity instability. We relate this wrong sign problem, which implies the existence of a Goldstone current in the ground state or of gluonic condensation, to the negative squared Meissner mass of the 8th gluon in the gapless two flavor color superconductor (g2SC) phase. Moreover we investigate the Meissner masses of the gluons and the squared velocity of the Goldstone in the multiple-plane-wave Larkin-Ovchinnikov-Fulde-Ferrel (LOFF) states, arguing that in such phases both the chromomagnetic instability and the velocity instability are most probably removed. We also do not expect Higgs instability in such multiple-plane-wave LOFF, at least when one considers fluctuations with small momenta. The true vacuum of gapless two flavor superconductors is thus expected to be a multiple-plane-wave LOFF state.

Gatto, R.; Ruggieri, M. [Depart. de Physique Theorique, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Dipartimento di Fisica, Universita di Bari, I-70126 Bari, Italy and INFN, Sezione di Bari, I-70126 Bari (Italy)

2007-06-01

346

Proposal for Teleportation of an Atomic State via Cavity Decay  

Microsoft Academic Search

We show how the state of an atom trapped in a cavity can be teleported to a\\u000asecond atom trapped in a distant cavity simply by detecting photon decays from\\u000athe cavities. This is a rare example of a decay mechanism playing a\\u000aconstructive role in quantum information processing. The scheme is\\u000acomparatively easy to implement, requiring only the ability

S. Bose; P. L. Knight; M. B. Plenio; V. Vedral

1999-01-01

347

Anomalous Zeno effect for sharply localized atomic states  

NASA Astrophysics Data System (ADS)

We analyze the nonquadratic in time Zeno effect which arises when a few-atom state initially trapped between two high laser-induced barriers is briefly released to free evolution. We identify the Zeno time, analyze the energy distributions of those atoms which have escaped and those that remained inside the trap, and obtain a simple relation between the survival and nonescape probabilities. The relevant time scales are such that the effect would be observable for the atomic species used in current laser experiments.

Sokolovski, D.; Pons, M.; Kamalov, T.

2012-08-01

348

Atomic oxygen interaction with spacecraft materials: Relationship between orbital and ground-based testing for materials certification  

Microsoft Academic Search

The effects of atomic oxygen on boron nitride, silicon nitride, solar cell interconnects used on the Intelsat 6 satellite, organic polymers, and MoSâ and WSâ dry lubricant have been studied in low Earth orbit (LEO) flight experiments and in our ground-based simulation facility at Los Alamos National Laboratory. Both the in-flight and ground-based experiments employed in situ electrical resistance measurements

J. B. Cross; S. L. Koontz; E. H. Lan

1991-01-01

349

Initial State in RHIC and Ground-State Properties of Nuclei  

NASA Astrophysics Data System (ADS)

The influence of ground-state properties of nuclei on the initial state geometry of strongly interacting matter in relativistic heavy ion collisions is discussed. Self-orientation effect in very-high-multiplicity collisions of deformed nuclei is explained. Deformation and wave function of Au, Cu nuclei are discussed in connection to the initial excentricity simulations. Suggestion for colliding selected isotopes of Sm, Zr and Ru nuclei is presented.

Filip, Peter

2013-09-01

350

Electronic structure and proton transfer in ground-state hexafluoroacetylacetone.  

PubMed

The ground electronic state (X(1)A(1)) of hexafluoroacetylacetone (HFAA) has been subjected to synergistic experimental and theoretical investigations designed to resolve controversies surrounding the nature of intramolecular hydrogen bonding for the enol tautomer. Cryogenic (93K) X-ray diffraction studies were conducted on single HFAA crystals grown in situ by means of the zone-melting technique, with the resulting electron density maps affording clear evidence for distinguishable O(1)-H and H...O(2) bonds that span an interoxygen distance of 2.680 +/- 0.003 A. Such laboratory findings have been corroborated by a variety of quantum chemical methods including Hartree-Fock (HF), density functional [DFT (B3LYP)], Møller-Plesset perturbation (MPn), and coupled cluster [CCSD, CCSD(T)] treatments built upon extensive sets of correlation-consistent basis functions. Geometry optimizations performed at the CCSD(T)/aug-cc-pVDZ level of theory predict an asymmetric (C(s)) equilibrium configuration characterized by an O...O donor-acceptor separation of 2.628 A. Similar analyses of the transition state for proton transfer reveal a symmetric (C(2v)) structure that presents a potential barrier of 21.29 kJ/mol (1779.7 cm(-1)) height. The emerging computational description of HFAA is in reasonable accord with crystallographic measurements and suggests a weakening of hydrogen-bond strength relative to that of the analogous acetylacetone molecule. PMID:20507165

Chatterjee, Chandrima; Incarvito, Christopher D; Burns, Lori A; Vaccaro, Patrick H

2010-06-24

351

Correlated eikonal initial state in ion-atom collisions  

SciTech Connect

An approximation is developed to deal with the ionization of atoms by bare charged ions. In this method the transition amplitude describing the three-body final state is evaluated using a continuum correlated wave and that for the initial state by an analytical continuation of the {phi}{sub 2} model to complex momenta. This procedure introduces in the atomic bound state a kinematical correlation with the projectile motion. Doubly differential cross sections (DDCS's) are computed for collisions of H{sup +} and F{sup 9+} ions with He atoms. Results for the DDCS's in the forward direction are compared with experimental data and other theoretical models. We find an enhancement of the distribution for low energy electrons and that the asymmetry of the electron capture to the continuum (ECC) peak is correctly described.

Ciappina, M.F.; Otranto, S. [Centro Atomico Bariloche and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Departamento de Fisica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Garibotti, C.R. [Centro Atomico Bariloche and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8400 San Carlos de Bariloche, Rio Negro (Argentina)

2002-11-01

352

Method for preparing two-atom entangled states in circuit QED and probing it via quantum nondemolition measurements  

NASA Astrophysics Data System (ADS)

We propose a probabilistic scheme to prepare a maximally entangled state between a pair of two-level atoms coupled to a leaking cavity mode in circuit QED, without requiring precise time control of the system evolution and initial atomic state. We show that the steady state of this dissipative system is a mixture of two parts, where the atoms are either in their ground state or in a maximally entangled one. Then, by applying a weak probe field to the cavity mode, we are able to discriminate those states without disturbing the atomic system, i.e., to perform a quantum nondemolition measurement via the cavity transmission. In this scheme, one has maximum cavity transmission only when the atomic system is in an entangled state, so that a single click in the detector is enough to be sure that the atoms are in a maximally entangled state. Our scheme relies on an interference effect as it happens in an electromagnetically induced transparency phenomenon so that it works even in the limit of a cavity decay rate much stronger than the atom-field coupling.

Rossatto, D. Z.; Villas-Boas, C. J.

2013-10-01

353

Quantum-confined-atom-based nanophosphors for solid state lighting  

NASA Astrophysics Data System (ADS)

When an atomic impurity is incorporated in a nanoparticle of size 2 to 10 nm, the quantum-confinement provided by the dielectric-boundary of the host-nanoparticle modulates the properties of the atom. This Quantum Confined Atom (QCA) shows extraordinary changes in its luminescent properties and is associated with the modulation of the excited states of the caged atom. These "atomically engineered nanomaterials," pioneered and developed by Nanocrystals Technology, yield several novel properties and are expected to be a major contributor to the future of nanotechnology. Efficient QCA-Nanophosphors that emit different colors depending on the specific choice of the 'caged atom' are being developed for applications to solid-state lighting. We have made two key contributions to development of SSL. (1) By embedding nanoparticles in the encapsulant, the refractive index is enhanced to 1.8 that allows us to enhance Light Extraction Efficiency (LEE) of the LED chip. (2) Incorporation of appropriate nanophosphors enables efficient down-conversion with high color-quality. The combination of an optically transparent downconverter and high refractive index in an encapsulant has yielded Phosphor-Converted LEDs (PC-LEDs) that yield higher package optical efficiency at lower package-level cost. The LEE and wall plug efficiency enhancement due to the HRI encapsulant is applicable across the entire visible spectrum of monochromatic HB-LED lamps.

Taskar, Nikhil R.; Bhargava, Ramesh N.; Barone, Juanita; Chhabra, Vishal; Chabra, Vipin; Dorman, Donald; Ekimov, Alexei; Herko, Samuel; Kulkarni, Bharati

2004-01-01

354

Orientation and alignment of collisionally excited atomic states  

SciTech Connect

The orientation and alignment parameters of atomic excited states of hydrogen and helium atoms formed in collisions with electrons, positrons, protons, and antiprotons are examined. For the orientation parameter (defined to be the expectation value of the electronic angular momentum perpendicular to the collision plane), it is found that the signs of for proton and positron impact are negative, consistent with the prediction of the classical model with a repulsive force. For electron and antiproton impact, except for electron scattering at large angles, the signs of are positive, consistent with the classical model with an attractive force. A simple semiempirical scaling of for electron-impact excitations to 2p states was found. The orientation of 2p states formed in electron capture in proton--hydrogen-atom collisions and in positron--hydrogen-atom collisions are also studied and the angular dependences of are found to show similar behavior. We also examine the orientation parameters for excitation and capture to 3d states and the alignment angles for excitation and capture to 2p states. It is found that in the latter cases these parameters do not show similar simple dependences with scattering angles.

Lin, C.D.; Shingal, R.; Jain, A.; Fritsch, W.

1989-05-01

355

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

Microsoft Academic Search

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

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

356

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

Microsoft Academic Search

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

J. Löffelholz; G. Morchio; F. Strocchi

1995-01-01

357

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

Microsoft Academic Search

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

J. Loffelholz; G. Morchio; F. Strocchi

1994-01-01

358

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

359

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

360

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

SciTech Connect

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

361

Ground-state proton radioactivity in the domain of neutron-poor nuclei heavier than tin  

NASA Astrophysics Data System (ADS)

The ground-state proton radioactivity in the domain of neutron-poor nuclei with an atomic number above 50 was investigated. In order to allow the observation of short-lived decays in the nsec range, a large-area, annular gas detector system with a parallel-plate avalanche counter was built, it has a detection probability better than 90% for protons. A 250 MeV Ni58-beam was used to bombard Ni58, Fe54, and Cr50 targets. The dependence of the measured half life on the decay energy and on the angular momentum of the emitted protons was investigated using a WKB calculation for an optical-model-potential; the agreement between measurement and calculation is variable.

Gillitzer, Albrecht

362

Ground-State Energies of Spinless Free Fermions and Hard-Core Bosons  

NASA Astrophysics Data System (ADS)

We compare the ground-state energies of bosons and fermions with the same form of the Hamiltonian. If both are noninteracting, the ground-state energy of bosons is always lower, owing to Bose-Einstein condensation. However, the comparison is nontrivial when bosons do interact. We first prove that, when the hopping is unfrustrated (all the hopping amplitudes are non-negative), hard-core bosons still must have a lower ground-state energy than fermions. If the hopping is frustrated, bosons can have a higher ground-state energy than fermions. We prove rigorously that this inversion indeed occurs in several examples.

Nie, Wenxing; Katsura, Hosho; Oshikawa, Masaki

2013-09-01

363

Ground-state properties of one-dimensional matter and quantum dissociation of a Luttinger liquid  

NASA Astrophysics Data System (ADS)

Motivated by emerging experimental possibilities to confine atoms and molecules in quasi-one-dimensional geometries, we analyze ground-state properties of strictly one-dimensional molecular matter comprised of identical particles of mass m. Such a class of systems can be described by an additive two-body potential whose functional form is common to all substances which only differ in the energy ? and range l scales of the potential. With this choice De Boer’s quantum theorem of corresponding states holds and the ground-state properties expressed in appropriate reduced form are only determined by the dimensionless parameter ?20˜?2/ml2?, measuring the strength of zero-point motion in the system. The presence of a minimum in the two-body interaction potential leads to a many-body bound state which is a Luttinger liquid stable for not very large ?0. As ?0 increases, the asymmetry of the two-body potential causes quantum expansion, softening, and eventual evaporation of the Luttinger liquid into a gas phase. Selecting the pair interaction potential in the Morse form we analytically compute the properties of the Luttinger liquid and its range of existence. We find that as ?0 increases, the system first undergoes a discontinuous evaporation transition into a diatomic gas followed by a continuous dissociation transition into a monoatomic gas. In particular we find that spin-polarized isotopes of hydrogen and 3He are monoatomic gases, 4He is a diatomic gas, while molecular hydrogen and heavier substances are Luttinger liquids. We also investigate the effect of finite pressure on the properties of the liquid- and monoatomic gas phases. In particular we estimate a pressure at which molecular hydrogen undergoes an inverse Peierls transition into a metallic state which is a one-dimensional analog of the transition predicted by Wigner and Huntington in 1935 [E. Wigner and H.B. Huntington, J. Chem Phys. 3, 764 (1935)].

Kolomeisky, Eugene B.; Qi, Xiaoya; Timmins, Michael

2003-04-01

364

Relaxation of antihydrogen from Rydberg to ground state  

SciTech Connect

Atoms formed in highly-magnetized, cryogenic Penning trap plasmas, such as those used in the Athena and ATRAP antihydrogen experiments, form in the guiding-center atom regime. In this regime, the positron orbit is well described by classical guiding-center drift dynamics. Electromagnetic radiation from such atoms is minimal, and energy loss is accomplished primarily through collisions between the atom and free positrons. With Fokker-Planck theory and Monte-Carlo simulation, we calculate the mean energy change an ensemble of such atoms experiences after the atom has been formed. Using this result, we show that the bulk of atoms formed in antihydrogen experiments do not relax out of the guiding-center regime to binding energies where radiation can become important.

Bass, Eric M.; Dubin, Daniel H. E. [Department of Physics, University of California at San Diego, La Jolla, CA 92093-0319 (United States)

2006-10-18

365

Ground-state magneto-optical resonances in cesium vapor confined in an extremely thin cell  

NASA Astrophysics Data System (ADS)

Experimental and theoretical studies are presented related to the ground-state magneto-optical resonance observed in cesium vapor confined in an extremely thin cell (ETC), with thickness equal to the wavelength of the irradiating light. It is shown that utilization of the ETC allows one to examine the formation of a magneto-optical resonance on the individual hyperfine transitions, thus distinguishing processes resulting in dark (reduced absorption) or bright (enhanced absorption) resonance formation. We report experimental evidence of bright magneto-optical resonance sign reversal in Cs atoms confined in an ETC. A theoretical model is proposed based on the optical Bloch equations that involves the elastic interaction processes of atoms in the ETC with its walls, resulting in depolarization of the Cs excited state, which is polarized by the exciting radiation. This depolarization leads to the sign reversal of the bright resonance. Using the proposed model, the magneto-optical resonance amplitude and width as a function of laser power are calculated and compared with the experimental ones. The numerical results are in good agreement with those of experiment.

Andreeva, C.; Atvars, A.; Auzinsh, M.; Blush, K.; Cartaleva, S.; Petrov, L.; Slavov, D.

2007-12-01

366

Cooling atom-cavity systems into entangled states  

SciTech Connect

Generating entanglement by simply cooling a system into a stationary state which is highly entangled has many advantages. Schemes based on this idea are robust against parameter fluctuations, tolerate relatively large spontaneous decay rates, and achieve high fidelities independent of their initial state. A possible implementation of this idea in atom-cavity systems has recently been proposed by Kastoryano et al., [Kastoryano et al., Phys. Rev. Lett. 106, 090502 (2011).]. Here we propose an improved entanglement cooling scheme for two atoms inside an optical cavity which achieves higher fidelities for comparable single-atom cooperativity parameters C. For example, we predict fidelities above 90% even for C as low as 20 without having to detect photons.

Busch, J.; De, S.; Spiller, T. P.; Beige, A. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Ivanov, S. S.; Torosov, B. T. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Department of Physics, Sofia University, James Bourchier 5 Boulevard, 1164 Sofia (Bulgaria)

2011-08-15

367

Regularities in molecular properties of ground state stable diatomics.  

PubMed

A simple relationship is reported between vibrational frequencies, bond lengths, and reduced masses for many families of stable, ground state diatomics: the frequency is proportional to the reciprocal of the product of the bond length and the square root of the reduced mass. This is demonstrated with each of the following related families: the alkali metal diatomics, the group 15 diatomics, the group 16 diatomics, the halogen diatomics, the alkali metal hydrides, the alkaline earth oxides, the group 14 oxides and their sulfides, the diatomics of carbon, of silicon and of germanium with group 16 elements, the hydrogen halides, the halides of lithium, of sodium, of potassium, of rubidium and of cesium, the chlorides of the alkali metals and of silver, and the polyatomic hydrides of groups 14 and 15. Although correlation coefficients of 0.99 or greater in each of the 21 families examined demonstrate the validity of the correlation, the deviations found are significantly larger than can be attributed to experimental uncertainties. PMID:15268024

Zavitsas, Andreas A

2004-06-01

368

Thermal Ground State in Yang-Mills Thermodynamics  

SciTech Connect

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

369

Table of experimental nuclear ground state charge radii: An update  

NASA Astrophysics Data System (ADS)

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

Angeli, I.; Marinova, K. P.

2013-01-01

370

Arsenic in Ground-Water Resources of the United States  

USGS Publications Warehouse

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

371

Mott-Insulator States of Ultracold Atoms in Optical Resonators  

SciTech Connect

We study the low temperature physics of an ultracold atomic gas in the potential formed inside a pumped optical resonator. Here, the height of the cavity potential, and hence the quantum state of the gas, depends not only on the pump parameters, but also on the atomic density through a dynamical ac-Stark shift of the cavity resonance. We derive the Bose-Hubbard model in one dimension and use the strong coupling expansion to determine the parameter regime in which the system is in the Mott-insulator state. We predict the existence of overlapping, competing Mott-insulator states, and bistable behavior in the vicinity of the shifted cavity resonance, controlled by the pump parameters. Outside these parameter regions, the state of the system is in most cases superfluid.

Larson, Jonas [ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); Damski, Bogdan [Theory Division, Los Alamos National Laboratory, MS-B213, Los Alamos, New Mexico 87545 (United States); Morigi, Giovanna [Departament de Fisica, Grup d'Optica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Lewenstein, Maciej [ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); ICREA-Institucio Catalana di Recerca i Estudis Avancats, Pg Lluis Companys 23, E-08010 Barcelona (Spain)

2008-02-08

372

Non-Fermi liquid ground states in certain heavy fermions  

NASA Astrophysics Data System (ADS)

For the past four decades, Landau's phenomenological theory of an interacting Fermi system has served as a paradigm for our understanding of metallic behaviour. However, some recent experiments on Ce and U compounds have opened up the possibility of a metallic state which is not a Fermi-liquid. Our objective in this thesis is to try and understand this breakdown of Fermi-liquid theory, and we start with a brief review of Landau's theory in Chap. 2. We begin with the notion of a "quasiparticle" and state how the low-energy transport and thermodynamic response functions depend on the effective mass msp* of the quasiparticles. We also discuss a slightly different incarnation of the Fermi-liquid that shows up at low temperatures in the Kondo and Anderson models, of magnetic impurities in metals. Here the low-energy excitations can be parametrized with the effective mass as well, which is now related to the inverse of the Kondo temperature Tsb{K}. In Chap. 3 we present an overview of the experimental scenario, mostly in Ce and U intermetallics which definitely exhibit Kondo-esque logarithmic scattering behaviour at high temperatures. The ground state in these compounds is a paramagnetic metal with a high residual resistivity, but they seem to violate the canonical Fermi-liquid description. We concentrate on two possible mechanisms that can give rise to these anomalous metallic states, namely disorder and Kondo over-screening. The effect of disorder is to create rare regions in the system with a Kondo scale that is essentially zero, thereby destroying the Fermi-liquid. Chap. 4 outlines the methods of solution of correlated impurity and lattice problems; dynamical mean-field theory maps the lattice onto a self-consistently determined Anderson impurity, then Quantum Monte Carlo solves the impurity problem. Using these techniques, the consequences of Kondo disorder in dynamics and magneto-transport are calculated in Chaps. 5 and 6 respectively. Kondo overscreening results from the inability of the conducting host to screen out the magnetic impurity at the largest length scales, or equivalently, the smallest temperatures. Dynamics of an over-screened Kondo lattice is studied in Chap. 7.

Chattopadhyay, Amitava

373

Quantum Information Splitting of an Arbitrary Three-Atom State with ?-state in Cavity QED  

NASA Astrophysics Data System (ADS)

We propose a scheme for implementing the deterministic quantum information splitting (QIS) of an arbitrary three-atom state in cavity QED. In the scheme, a four-atom ?-state and a three-atom GHZ state are used as quantum channel. In comparison with the QIS scheme by using the same quantum channel (Luo and Deng in Quantum. Inf. Process. 12:773, 2013), our scheme does not involve joint Bell-state measurements, one only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of experiment.

Nie, Yi-you; Li, Yuan-hua; Wang, Xian-ping; Sang, Ming-huang

2013-11-01

374

Positron spectroscopy in atomic and solid state physics  

Microsoft Academic Search

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

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

2003-01-01

375

Ice sheet grounding line dynamics: Steady states, stability, and hysteresis  

Microsoft Academic Search

The ice sheet–ice shelf transition zone plays an important role in controlling marine ice sheet dynamics, as it determines the rate at which ice flows out of the grounded part of the ice sheet. Together with accumulation, this outflow is the main control on the mass balance of the grounded sheet. In this paper, we verify the results of a

Christian Schoof

2007-01-01

376

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.

377

Relativistic calculations of ground and excited states of LiYb molecule for ultracold photoassociation spectroscopy studies  

NASA Astrophysics Data System (ADS)

We report a series of quantum-chemical calculations for the ground and some of the low-lying excited states of an isolated LiYb molecule by the spin-orbit multistate complete active space second-order perturbation theory (SO-MS-CASPT2). Potential energy curves, spectroscopic constants, and transition dipole moments (TDMs) at both spin-free and spin-orbit levels are obtained. Large spin-orbit effects especially in the TDMs of the molecular states dissociating to Yb(3P0,1,2) excited states are found. To ensure the reliability of our calculations, we test five types of incremental basis sets and study their effect on the equilibrium distance and dissociation energy of the ground state. We also compare CASPT2 and CCSD(T) results for the ground state spectroscopic constants at the spin-free relativistic level. The discrepancies between the CASPT2 and CCSD(T) results are only 0.01 A? in equilibrium bond distance (Re) and 200 cm-1 in dissociation energy (De). Our CASPT2 calculation in the supermolecular state (R=100 a.u.) with the largest basis set reproduces experimental atomic excitation energies within 3% error. Transition dipole moments of the super molecular state (R=100 a.u.) dissociating to Li(2P) excited states are quite close to experimental atomic TDMs as compared to the Yb(3P) and Yb(1P) excited states. The information obtained from this work would be useful for ultracold photoassociation experiments on LiYb.

Gopakumar, Geetha; Abe, Minori; Das, Bhanu Pratap; Hada, Masahiko; Hirao, Kimihiko

2010-09-01

378

Metastable atoms in gasdynamic and atomic beams: Velocity distribution and state density by laser diagnostics  

SciTech Connect

The velocity distributions and state densities of metastable Ca(4s4p /sup 3/P/sub 2/) atoms emerging from discharge beam sources were measured by probing the Doppler shift in laser induced fluorescence. In order to cover the widely spread distribution of the longitudinal velocity component a single-mode dye laser was used in mode hopping technique. In this way up to 4 A can be covered in steps of 182 MHz distance. The longitudinal and transverse components are sampled simultaneously. For the gasdynamic jet the transfer velocities were measured from some 10 m/s up to supersonic values. Using the transverse laser beam the absorption caused by Ca in the /sup 3/P/sub 2/ state was tested. Absorptions up to 0.995 could be achieved in the free jet. A /sup 3/P density of 7 x 10/sup 11/ cm/sup -3/ is calculated. Similarly for the atomic beam 2 x 10/sup 10/ cm/sup -3/ is found, the flux being 4.7 x 10/sup 15/ metastable atoms/s sr. Details of the atomic beam source for metastable atoms are given.

Brinkmann, U.; Kluge, J.; Pippert, K.

1980-09-01

379

Ionization of Polarized Hydrogen Atoms.  

National Technical Information Service (NTIS)

Methods are discussed for the production of polarized H exp - ions from polarized atoms produced in ground state atomic beam sources. Present day sources use ionizers of two basic types - electron ionizers for H exp + Vector production followed by double ...

J. G. Alessi

1983-01-01

380

Ground-state fidelity and tensor network states for quantum spin tubes  

Microsoft Academic Search

An efficient algorithm is developed for quantum spin tubes in the context of the tensor network representations. It allows to efficiently compute the ground-state fidelity per lattice site, which in turn enables us to identify quantum critical points, at which quantum spin tubes undergo quantum phase transitions. As an illustration, we investigate the isosceles spin 1\\/2 antiferromagnetic three-leg Heisenberg tube.

Ai-Min Chen; Qian-Qian Shi; Jin-Hua Liu; Huan-Qiang Zhou

2011-01-01

381

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

SciTech Connect

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

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

2011-10-15

382

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

NASA Astrophysics Data System (ADS)

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

Ren, Zhongzhou; Xu, Chang

2005-09-01

383

Evolution of a quantum spin system to its ground state: Role of entanglement and interaction symmetry  

SciTech Connect

We study the decoherence of two ferro- and antiferromagnetically coupled spins that interact with a frustrated spin-bath environment in its ground state. The conditions under which the two-spin system relaxes from the initial spin-up-spin-down state toward its ground state are determined. It is shown that the two-spin system relaxes to its ground state for narrow ranges of the model parameters only. It is demonstrated that the symmetry of the coupling between the two-spin system and the environment has an important effect on the relaxation process. In particular, we show that, if this coupling conserves the magnetization, the two-spin system readily relaxes to its ground state, whereas a nonconserving coupling prevents the two-spin system from coming close to its ground state.

Yuan, Shengjun [Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands); Katsnelson, Mikhail I. [Institute of Molecules and Materials, Radboud University of Nijmegen, 6525 ED Nijmegen (Netherlands); De Raedt, Hans [Department of Applied Physics, Materials Science Centre, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands)

2007-05-15

384

Quantum teleportation of an arbitrary superposition of atomic states  

NASA Astrophysics Data System (ADS)

This paper proposes a scheme to teleport an arbitrary multi-particle two-level atomic state between two parties or an arbitrary zero- and one-photon entangled state of multi-mode between two high-Q cavities in cavity QED. This scheme is based on the resonant interaction between atom and cavity and does not involve Bell-state measurement. It investigates the fidelity of this scheme and find out the case of this unity fidelity of this teleportation. Considering the practical case of the cavity decay, this paper finds that the condition of the unity fidelity is also valid and obtains the effect of the decay of the cavity on the successful probability of the teleportation.

Chen, Qiong; Fang, Xi-Ming

2008-05-01

385

XUV frequency-comb metrology on the ground state of helium  

SciTech Connect

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

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

2011-12-15

386

Grundzustands-Protonenradioaktivitaet im Gebiet Neutronenarmer Kerne Oberhalb des Zinns (Ground-State Proton Radioactivity in the Domain of Neutron-Poor Nuclei Heavier Than Tin).  

National Technical Information Service (NTIS)

The ground-state proton radioactivity in the domain of neutron-poor nuclei with an atomic number above 50 was investigated. In order to allow the observation of short-lived decays in the nsec range, a large-area, annular gas detector system with a paralle...

A. Gillitzer

1985-01-01

387

Ground states and dynamics of rotating Bose-Einstein condensates  

Microsoft Academic Search

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

Weizhu Bao

388

Generation of hyperentangled states between remote noninteracting atomic ions  

SciTech Connect

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

389

Macroscopic two-state systems in trapped atomic condensates  

NASA Astrophysics Data System (ADS)

We consider a macroscopic two-state system based on persistent current states of a Bose-Einstein condensate (BEC) of interacting neutral atoms confined in a ring with a weak Josephson link. We demonstrate that macroscopic superpositions of different BEC flows are energetically favorable in this system. Moreover, a macroscopic two-state dynamics emerges in the low-energy limit. We also investigate fundamental limitations due to the noise inherent in the interacting BEC of Josephson-ring geometry. We show that the coherent macroscopic dynamics is readily measurable for an experimentally accessible range of parameters.

Solenov, Dmitry; Mozyrsky, Dmitry

2010-12-01

390

Topological quantum computation away from the ground state using Majorana fermions  

NASA Astrophysics Data System (ADS)

We relax one of the requirements for topological quantum computation with Majorana fermions. Topological quantum computation was discussed so far as manipulation of the wave function within degenerate many-body ground state. The simplest particles providing degenerate ground state, Majorana fermions, often coexist with extremely low-energy excitations so keeping the system in the ground state may be hard. We show that the topological protection extends to the excited states, as long as the Majorana fermions do not interact neither directly nor via the excited states. This protection relies on the fermion parity conservation and so it is generic to any implementation of Majorana fermions.

Akhmerov, A. R.

2010-07-01

391

Skyrmions as the ground states of quantum dots in strong magnetic fields  

Microsoft Academic Search

We note that the properties of skyrmions capture many features of the ground states of quantum dots in strong magnetic fields. Therefore, in the present work we choose skyrmions with high winding numbers as trial ground states. In our results, we find that the occurrence of skyrmions fits an instability criterion of maximum density droplet very well. Interesting spin structures

Her-Lih Chiueh; Der-San Chuu

1999-01-01

392

The nu sub 2 Band CHD3; Ground State Parameters for CHD3 from Combination Differences.  

National Technical Information Service (NTIS)

The nu sub 2 fundamental band of CHD3, centered near 2143/cm, was recorded at a resolution of 0.015-0.25/cm. Analysis of ground state combination differences yielded well-determined values for the ground state molecular parameters for CHD3. These paramete...

D. E. Jennings W. E. Blass

1974-01-01

393

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

Microsoft Academic Search

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

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

1994-01-01

394

Ground state energy of the polaron in the relativistic quantum electrodynamics  

SciTech Connect

We consider the polaron model in the relativistic quantum electrodynamics. We prove that the ground state energy of the model is finite for all values of the fine-structure constant and the ultraviolet cutoff {lambda}. Moreover we give an upper bound and a lower bound of the ground state energy.

Sasaki, Itaru [Department of Mathematics, Hokkaido University, Sapporo 060-0810 (Japan)

2005-10-01

395

The ground-state tunneling splitting of various carboxylic acid dimers  

Microsoft Academic Search

Carboxylic acid dimers in gas phase reveal ground-state tunneling splittings due to a double proton transfer between the two subunits. In this study we apply a recently developed accurate semiclassical method to determine the ground-state tunneling splittings of eight different carboxylic acid derivative dimers (formic acid, benzoic acid, carbamic acid, fluoro formic acid, carbonic acid, glyoxylic acid, acrylic acid, and

Christofer S. Tautermann; Andreas F. Voegele; Klaus R. Liedl

2004-01-01

396

Exact expression of the ground-state energy for the symmetric anderson model  

NASA Astrophysics Data System (ADS)

The exact expression of the ground-state energy for the symmetric Anderson model is obtained with the use of the Wiegmann approach. It is found that some of the quasi-momenta appearing in Wiegmann's paper are necessarily complex to obtain the expression of the ground-state energy.

Kawakami, Norio; Okiji, Ayao

1981-12-01

397

Approximate Teleportation of an Unknown Atomic-Entangled State with Dissipative Atom-Cavity Resonant Jaynes Cummings Model  

Microsoft Academic Search

We propose a scheme for approximately and conditionally teleporting an unknown atomic-entangled state in dissipative cavity QED. It is the further development of the scheme of [Phys. Rev. A 69 (2004) 064302], where the cavity mode decay has not been considered and the state teleportated is an unknown atomic state. In this paper, we investigate the influence of the decay

Zong-Liang Liu; Shao-Hua Li; Chang-Yong Chen

2008-01-01

398

First-principles calculation of the phase stability and elastic properties of ZrPt compounds at ground state  

NASA Astrophysics Data System (ADS)

The phase stability, elastic properties, electronic structure and thermodynamics properties of ZrPt compounds are investigated by first-principles approach. The calculated formation enthalpies show that the CrB-type phase at ground state is more stable than that of CsCl-type, which is in good agreement with the experimental phenomena. The bulk modulus of CrB-type is close to the CsCl-type phase. However, the shear constant C44 and shear modulus for the former are two times larger than the latter. Furthermore, we found that the Debye temperature of CrB-type (288.5 K) is higher than that of CsCl-type (186 K) phase, indicates that the atomic cohesion of the former is stronger than the latter at ground state.

Pan, Y.; Guan, W. M.; Zhang, K. H.

2013-10-01

399

Quantum State Tomography via Continuous Measurement of Laser Cooled Cesium Atoms  

NASA Astrophysics Data System (ADS)

Quantum State Tomography (QST) is the process of reconstructing an unknown quantum state from the outcomes of a sufficiently complete series of measurements. To improve the speed and accuracy of QST, we have developed and implemented a new protocol based on weak continuous measurement and dynamical control. In our experiment, an ensemble of Cs atoms are prepared in identical quantum states within the ground hyperfine manifold, driven by a combination of static, rf and ?w magnetic fields, and simultaneously probed by coupling the atomic spin to the polarization of a near-resonant optical probe field. A continuous measurement of the probe polarization yields an informationally complete measurement record that can be inverted to obtain an estimate of the unknown hyperfine state. We have reconstructed the full density matrix for a number of randomly chosen test states, using computer algorithms based either on least squares fitting or compressed sensing. Both approaches perform similarly and reconstruct our test states with an average fidelity around 90%, limited primarily by errors in the applied drive fields.

Smith, Aaron; Anderson, Brian; Sosa, Hector; Jessen, Poul; Riofrio, Carlos; Deutsch, Ivan

2011-10-01

400

ATOMIC AND MOLECULAR PHYSICS: Generation of a Super Strong Attosecond Pulse from an Atomic Superposition State Irradiated by a Shape-Optimized Short Pulse  

NASA Astrophysics Data System (ADS)

Using a linearly polarized, phase-stabilized 3-fs driving pulse of 800 nm central wavelength shape-optimized on its ascending edge by its an amplitude-reduced pulse irradiating on a superposition state of the helium atom, we demonstrate theoretically the generation of a super strong isolated 176-attosecond pulse in the spectral region of 93-124 eV. The unusually high intensity of this attosecond pulse is marked by the Rabi-like oscillations emerging in the time-dependent populations of the ground state and the continuum during the occurrence of the electron recombination, which is for the first time observed in this work.

Guo, Fu-Ming; Yang, Yu-Jun; Jin, Ming-Xing; Ding, Da-Jun; Zhu, Qi-Ren

2009-11-01

401

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

SciTech Connect

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

Lovaasen, B. M.; Lockard, J. V.; Cohen, B. W.; Yang, S.; Zhang, X.; Simpson, C. K.; Chen, L. X.; Hopkins, M. D. (Chemical Sciences and Engineering Division); ( XSD); (The Univ. of Chicago)

2012-01-01

402

Non-magnetic Ground State of a Pr-based Caged Compound PrRu2Zn20  

NASA Astrophysics Data System (ADS)

Recently there has been considerable interest in rare-earth based compounds with caged structures, because they show a variety of ground states originating from the caged structures, for example, heavy-fermion superconductivity in PrOs4Sb12, a phase transition attributed to scalar-type multipolar degrees of freedom in PrFe4P12, etc. We have studied Pr-based caged compounds of PrRu2Zn20 crystallizing in the cubic CeCr2Al20-type structure, where a Pr-ion is encapsulated in a cage formed of sixteen zinc atoms. In analogy of the filled-skutterudite structure, the large coordination number of the Pr-ion, CN=16, suggests weak crystalline electric field (CEF) effect and strong hybridization of the cage and f electrons of the Pr-ion. In PrRu2Zn20, the magnetic susceptibility obeys the Curie-Weiss law above 25 K, suggesting the trivalent state of the Pr-ion suffering from weak CEF effect. A Schottky peak of the specific heat appearing at 2.5 K is the manifestation of a first excited state located around 7 K above the CEF ground state. No phase transition has been observed down to 0.4 K, indicating the non-mangnetic singlet ground state.

Onimaru, Takahiro; Matsumoto, Keisuke; Inoue, Yukihiro F.; Umeo, Kazunori; Saiga, Yuta; Takabatake, Toshiro; Matsushita, Yoshitaka; Nishimoto, Kazue; Tamura, Ryuji

2010-03-01

403

Generation of atom-photon entangled states in atomic Bose-Einstein condensate via electromagnetically induced transparency  

SciTech Connect

In this paper, we present a method to generate continuous-variable-type entangled states between photons and atoms in atomic Bose-Einstein condensate (BEC). The proposed method involves an atomic BEC with three internal states, a weak quantized probe laser, and a strong classical coupling laser, which form a three-level {lambda}-shaped BEC system. We consider a situation where the BEC is in electromagnetically induced transparency with the coupling laser being much stronger than the probe laser. In this case, the upper and intermediate levels are unpopulated, so that their adiabatic elimination enables an effective two-mode model involving only the atomic field at the lowest internal level and the quantized probe laser field. Atom-photon quantum entanglement is created through laser-atom and interatomic interactions, and two-photon detuning. We show how to generate atom-photon entangled coherent states and entangled states between photon (atom) coherent states and atom-(photon-) macroscopic quantum superposition (MQS) states, and between photon-MQS and atom-MQS states.

Kuang Leman [Department of Physics, Hunan Normal University, Changsha 410081 (China); Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, Trieste 34014 (Italy); Zhou Lan [Department of Physics, Hunan Normal University, Changsha 410081 (China)

2003-10-01

404

State-resolved study of keV sputtered neutral atoms by resonance ionization spectroscopy  

SciTech Connect

We have performed simultaneous measurements of energy-, and angle-resolved distributions of Ni atoms desorbed from a single crystal Ni{l_brace}100{r_brace} surface bombarded by 5 keV Ar{sup +} ions. Ground state and six low-lying excited states from the a{sup 3}FJ (J=4,3,2) and a{sup 3}DJ (J=3,2,1) manifolds as well as a{sup 1}D2 have been investigated along different azimuths. Both a{sup 3}FJ and a{sup 1}D2 states have closed shell electronic structure, 3d{sup 8}4s{sup 2}, while the a{sup 3}DJ states are open shell electronic states, 3d{sup 9}4s{sup 1}. Angle-integrated energy distributions demonstrate a strong dependence on the electronic structure while the magnitude of the excitation energy does not significantly alter the results. This is the first conclusive evidence that electronic structure rather than excitation energy is the primary factor in determining kinetic energy distributions of sputtered neutral species. Population distribution among the seven electronic states are obtained through two sets of measurements performed on two experimental apparati: one measures the energy- and angle-integrated resonance ionization signal intensities of the sputtered Ni; the other measures the resonance ionization signal intensities of thermally evaporated Ni atoms with a known heating temperature. The experiment results show that the population distribution is very different from Boltzman-type distribution with a{sup 3}D3 and a{sup 3}D2 states more intensely populated. The work also illustrates the power of RIS to perform quantum state specific measurements on fast moving atoms.

He Chun; Postawa, Z.; Rosencrance, S.; Chatterjee, R.; Garrison, B. J.; Winograd, N. [Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

1995-04-01

405

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

PubMed Central

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.

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

2013-01-01

406

Sturmian expansions for two-electron atomic systems: Singly and doubly excited states  

SciTech Connect

We present a configuration interaction (CI) method based on the Sturmian expansion for bound states of a two-electron atomic system. These Sturmian functions are solutions of one-electron quantum mechanical problems, where the eigenvalue is the magnitude of a short-range potential. Also, they fulfill the long-range boundary conditions of Coulomb potentials. We choose to expand the Sturmians of the CI basis using L{sup 2} Laguerre-type functions. We compute ground and single-excited states energies for He and H{sup -}. Moreover, we are able to obtain energies and widths of double excited states of He, using a Sturmian basis with outgoing boundary conditions. In all cases, our ansatz outperforms other CI calculations, for similar basis size.

Frapiccini, A. L.; Randazzo, J. M.; Colavecchia, F. D. [Division Colisiones Atomicas, Centro Atomico Bariloche and CONICET, 8400 S. C. de Bariloche, Rio Negro (Argentina); Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur and CONICET, 8000 Bahia Blanca, Buenos Aires (Argentina)

2010-10-15

407

First-principles calculation of ground and excited-state absorption spectra of ruby and alexandrite considering lattice relaxation  

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

408

Dynamic stabilization of ground-state hydrogen in superintense circularly polarized laser pulses  

NASA Astrophysics Data System (ADS)

We present a comprehensive calculation of 3D dynamic stabilization (DS) of ground-state hydrogen in superintense circularly polarized laser pulses. Three laser-pulse envelopes have been considered: Gaussian, sech, and Lorentzian. The ionization probability at the end of the pulse Pion was calculated for a range of high frequencies ohgr ranging from 0.65 to 8 au, for peak fields up to about 60 au (depending on ohgr), and for full width at half maximum pulse lengths tgrp extending from 0.25 to 100 cycles (depending on ohgr). This is a very accurate calculation, very much more time consuming than its linear polarization counterpart. For Gaussian and sech pulses we find prominent DS and substantial atomic survival under conditions where our nonrelativistic, dipole approximation calculation is expected to be valid. For Lorentzian pulses there is no DS in the range studied, and we explain the reasons. We find that the evolution of the atom is adiabatic and amenable to single-state Floquet theory, up to very large peak fields (several au), and down to very short pulses (few cycle, subfemtosecond). The general case of nonadiabatic pulses is interpreted in terms of the multistate Floquet theory. We compare the results for Pion in the cases of circular and linear polarization and find a surprising resemblance, when represented as a function of the peak intensity. Our results indicate the possibility of observing DS experimentally with the VUV-FEL light sources that are now in test operation, or with the attosecond pulses obtained from high harmonic generation, in a state-of-the-art experiment, however.

Boca, M.; Muller, H. G.; Gavrila, M.

2004-01-01

409

75 FR 6069 - Idaho State University; Establishment of Atomic Safety and Licensing Board  

Federal Register 2010, 2011, 2012, 2013

...Idaho State University; Establishment of Atomic Safety and Licensing Board Pursuant to...321, notice is hereby given that an Atomic Safety and Licensing Board (Board) is...judges: Alan S. Rosenthal, Chair, Atomic Safety and Licensing Board Panel,...

2010-02-05

410

77 FR 58591 - Northern States Power Company; Establishment of Atomic Safety and Licensing Board  

Federal Register 2010, 2011, 2012, 2013

...States Power Company; Establishment of Atomic Safety and Licensing Board Pursuant to...321, notice is hereby given that an Atomic Safety and Licensing Board (Board) is...Hawkens, Chief Administrative Judge, Atomic Safety and Licensing Board Panel...

2012-09-21

411

Ground state energy of mean field model of interacting bosons in Bernoulli potential  

NASA Astrophysics Data System (ADS)

This paper explores the ground state energy of a system of interacting ``soft core'' bosons in a random Bernoulli potential in the Gross-Pitaevskii mean-field approximation. First, we prove a condition for a state to delocalize due to interaction. Using this condition, asymptotics for ground state energy per particle are derived in the large system limit for small values of the coupling constant. Our methods directly describe the shape of the ground state in a given realization of the random potential.

Bishop, M.; Wehr, J.

2013-08-01

412

Plasma screening within Rydberg atoms in circular states  

NASA Astrophysics Data System (ADS)

A Rydberg atom embedded in a plasma can experience penetration by slowly moving electrons within its volume. The original pure Coulomb potential must now be replaced by a screened Coulomb potential which contains either a screening length Rs or a screening factor A = Rs -1 . For any given discrete energy level, there is a Critical Screening Factor (CSF) Ac beyond which the energy level disappears (by merging into the continuum). Analytical results are obtained for the classical dependence of the energy on the screening factor, for the CSF, and for the critical radius of the electron orbit for Circular Rydberg States (CRS) in this screened Rydberg atom. The results are derived for any general form of the screened Coulomb potential and are applied to the particular case of the Debye potential. We also show that CRS can temporarily exist above the ionization threshold and are therefore the classical counterparts of quantal discrete states embedded into continuum. The results are significant not only to Rydberg plasmas, but also to fusion plasmas, where Rydberg states of multi-charged hydrogen-like ions result from charge exchange with hydrogen or deuterium atoms, as well as to dusty/complex plasmas.

Flannery, M. R.; Oks, E.

2008-04-01

413

Quantum State Sharing by Using an Eight-Atom Composite W-Bell State in Cavity QED  

NASA Astrophysics Data System (ADS)

We demonstrate that an eight-atom composite W-Bell state can be used to realize the deterministic quantum state sharing of an arbitrary two-atom state in cavity QED. In the scheme, it does not involve Bell-state measurement and only needs to perform the single-atom measurements. Our scheme is not sensitive to both the cavity decay and the atom radiation, which is of importance in view of decoherence.

Liu, Zhong-min; Zhou, Lin

2013-10-01

414

Total cross sections for the double photoionization of Li from the ground and excited states  

SciTech Connect

Two nonperturbative approaches are used to calculate the total cross sections for the double photoionization of Li from its ground and first excited states. From the ground state, both the time-dependent close coupling and R matrix with pseudostate approaches find reasonable agreement with experimental data, and from the first excited state (where no measurements are available), the two approaches are also in reasonable agreement.

Colgan, J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Griffin, D. C. [Department of Physics, Rollins College, Winter Park, Florida 32789 (United States); Ballance, C. P.; Pindzola, M. S. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

2009-12-15

415

Ground state and excitations of the supersymmetric extended Hubbard model with long-range interaction  

SciTech Connect

We examine the ground state and excitations of the one-dimensional supersymmetric extended Hubbard model with long-range interaction. The ground state wave-function and low lying excitations are given explicitly in the form of a Jastrow product of two-body terms. This result motivates an asymptotic Bethe ansatz solution for the model. We present evidence that this solution is in fact exact and spans the complete spectrum of states. {copyright} {ital 1996 The American Physical Society.}

Wang, D.F. [Institut de Physique Theorique, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne (Switzerland); Liu, J.T. [Department of Physics, The Rockefeller University, 1230 York Avenue, New York, New York 10021-6399 (United States)

1996-07-01

416

Rigorous results on superconducting ground states for attractive extended Hubbard models  

Microsoft Academic Search

We show that the exact ground state for a class of extended Hubbard models including bond-charge, exchange, and pair-hopping terms, is the Yang ``eta-paired'' state for any nonvanishing positive value of the pair-hopping amplitude, at least when the on-site Coulomb interaction is attractive enough and the remaining physical parameters satisfy a single constraint. The ground state is thus rigorously superconducting.

Arianna Montorsi; David K. Campbell

1996-01-01

417

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

Microsoft Academic Search

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

418

Experimental Nuclear Masses and the Ground State of Cold Dense Matter  

Microsoft Academic Search

We study the consequences of recent progress in the experimental\\u000adetermination of masses of neutron rich nuclei for our knowledge of the ground\\u000astate of cold dense matter. The most recent experimental data determine the\\u000aground state of cold dense matter up to $ \\\\rho \\\\simeq 10^{11}~{\\\\rm g~cm^{-3}}\\u000a$. The composition and the equation of state of the ground state

Pawel HAENSEL; B. Pichon

1993-01-01

419

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

NASA Astrophysics Data System (ADS)

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

Pardella, G.; Liers, F.

2008-11-01

420

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

SciTech Connect

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

421

Electron-Impact Ionization of C+ in Both Ground and Metastable States  

SciTech Connect

Electron-impact ionization cross sections are calculated for the ground and metastable states of C{sup +}. Comparisons between perturbative distorted-wave and nonperturbative time-dependent close-coupling calculations find reductions in the peak direct ionization cross sections due to electron coupling effects of approximately 5% for ground state C{sup +} and approximately 15% for metastable state C{sup +}. Fairly small excitation-autoionization contributions are found for ground state C{sup +}, while larger excitation-autoionization contributions are found for metastable state C{sup +}. Comparisons between perturbative distorted-wave and nonperturbative R-matrix with pseudostates calculations find reductions in the peak total ionization cross sections due to electron coupling effects of approximately 15-20% for ground state C{sup +} and approximately 25-35% for metastable state C{sup +}. Finally, comparisons between theory and experiment find that present and previous C{sup +} crossed-beam measurements are in excellent agreement with ground state nonperturbative R-matrix with pseudostates calculations for total ionization cross sections. Combined with previous non-perturbative calculations for C, C{sup 2+}, and C{sup 3+}, accurate ionization cross sections and rate coefficients are now available for the ground and metastable states of all carbon ion stages.

Ludlow, J. A. [Auburn University, Auburn, Alabama; Loch, S. D. [Auburn University, Auburn, Alabama; Pindzola, Michael S. [Auburn University, Auburn, Alabama; Ballance, C. P. [Rollins College, Winter Park, FL; Griffin, D. C. [Rollins College, Winter Park, FL; Bannister, Mark E [ORNL; Fogle, Jr., Michael R [ORNL

2008-01-01

422

Measurement of longitudinal and transverse spin relaxation rates using the ground-state Hanle effect  

SciTech Connect

We present a theoretical and experimental study of the resonant circularly-polarized-light-induced Hanle effect in the ground state of Cs vapor atoms in a paraffin-coated cell. The effect manifests itself as a narrow resonance (centered at B=0) in the dependence of the optical transmission coefficient of the vapor on the magnitude of an external magnetic field B(vector sign). We develop a theoretical model that yields an algebraic expression for the shape of these resonances for arbitrary field orientations and arbitrary angular momenta of the states coupled by the exciting light, provided that the light power is kept sufficiently small. An experimental procedure for assessing the range of validity of the model is given. Experiments were carried out on the laser-driven Cs D{sub 1} transition both in longitudinal and transverse field geometries, and the observed line shapes of the corresponding bright and dark resonances give an excellent confirmation of the model predictions. The method is applied for determining the intrinsic longitudinal and transverse relaxation rates of the vector magnetization in the vapor and their dependence on light power.

Castagna, N.; Weis, A. [Departement de Physique, Universite de Fribourg, Chemin du Musee 3, CH-1700 Fribourg (Switzerland)

2011-11-15

423

Vibrational specificity of proton-transfer dynamics in ground-state tropolone.  

PubMed

The vibrational dependence of large-amplitude proton transfer taking place in the ground electronic state (X1A1) of tropolone has been explored by implementing a coherent variant of the stimulated emission pumping (SEP) technique within the framework of two-color resonant four-wave mixing (TC-RFWM) spectroscopy. The lowest 1700 cm(-1) portion of this potential surface has been interrogated under ambient bulk-gas conditions, enabling rotationless term energies (Tv+) and tunneling-induced bifurcations Delta(v)X to be extracted for 43 assigned vibrational features of a1 and b2 symmetry. The resulting values of Delta(v)X reflect the state-specificity long attributed to the hydron-migration pathways of tropolone and range in magnitude from 0.0 cm(-1) to 17.8 cm(-1), where the former implies essentially complete quenching of unimolecular dynamics whilst the latter represents nearly a twenty-fold increase in reaction rate over that of the zero-point level. This vibrational mediation of tunneling behavior is discussed in terms of attendant atomic displacements and permutation-inversion symmetries, with choreographed motion of the five-member reaction site (C-O-H...O=C) found to exert the most significant influence on the efficacy of proton transfer. PMID:20567783

Murdock, Daniel; Burns, Lori A; Vaccaro, Patrick H

2010-06-21

424

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

SciTech Connect

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

425

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

SciTech Connect

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

Ren Zhongzhou [Department of Physics, Nanjing University, Nanjing 210008 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator, Lanzhou 730000 (China); Chen Dinghan; Xu Chang [Department of Physics, Nanjing University, Nanjing 210008 (China)

2006-11-02

426

The Ground State Energy of the Multi-Polaron in the Strong Coupling Limit  

NASA Astrophysics Data System (ADS)

We consider the Fröhlich N-polaron Hamiltonian in the strong coupling limit and bound its ground state energy from below. In particular, our lower bound confirms that the ground state energy of the Fröhlich polaron and the ground state energy of the associated Pekar-Tomasevich variational problem are asymptotically equal in the strong coupling limit. We generalize the operator approach that was used to prove a similar result in the N = 1 case in Lieb and Thomas (Commun. Math. Phys. 183:511-519, 1997) and apply a Feynman-Kac formula to obtain the same result for an arbitrary particle number N ? 1.

Anapolitanos, Ioannis; Landon, Benjamin

2013-08-01

427

Ground state and constrained domain walls in Gd/Fe multilayers  

NASA Astrophysics Data System (ADS)

The magnetic ground state of antiferromagnetically coupled Gd/Fe multilayers and the evolution of in-plane domain walls is modeled with micromagnetics. The twisted state is characterized by a rapid decrease of the interface angle with increasing magnetic field. We found that for certain ratios MFe:MGd, the twisted state is already present at low fields. However, the magnetic ground state is not only determined by the ratio MFe:MGd but also by the thicknesses of the layers; that is by the total moments of the layer. The dependence of the magnetic ground state is explained by the amount of overlap of the domain walls at the interface. Thicker layers suppress the Fe-aligned and the Gd-aligned state in favor of the twisted state. On the other hand, ultrathin layers exclude the twisted state, since wider domain walls cannot form in these ultrathin layers.

van Aken, Bas B.; Prieto, José L.; Mathur, Neil D.

2005-03-01

428

Comment on 'Scheme for teleportation of an unknown atomic state without the Bell-state measurement'  

SciTech Connect

Recently, Ye and Guo [Phys. Rev. A 70, 054303 (2004)] have presented a scheme for implementing quantum teleportation of atomic states in cavity QED. In this Comment, we show that contrary to the authors' claim, the scheme is based on Bell-state measurement.

Chhajlany, Ravindra W.; Wojcik, Antoni [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)

2006-01-15

429

Relaxation of an unstable state in parametrically excited cold atoms.  

PubMed

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

2011-09-30

430

Ground-state cooling of a mechanical oscillator and detection of a weak force using a Bose-Einstein condensate  

NASA Astrophysics Data System (ADS)

We investigate the possibility of cooling a mechanical oscillator to its ground state and using it to detect a weak coherent force by means of a hybrid optomechanical quantum device formed by a Bose-Einstein condensate (BEC) confined in a high quality factor optical cavity with an oscillatory end mirror. We show using the stochastic cooling technique that the atomic two-body interaction can be utilized to cool the mirror and achieve position squeezing essential for making sensitive measurements of weak forces. We further show that for certain values of the system parameters and spectral range, the atomic two-body interaction can also increase the signal-to-noise ratio and decrease the noise of the off-resonant stationary spectral measurements. We show that the minimum noise is obtained only in the presence of BEC.

Mahajan, Sonam; Kumar, Tarun; Bhattacherjee, Aranya B.; ManMohan

2013-01-01

431

Ground-state properties of a Bose-Einstein condensate tuned by a far-off-resonant optical field  

SciTech Connect

In this paper, we explore a scheme to tackle a challenging problem of stable Bose-Einstein condensates (BECs) with attractive atom interactions. In this scheme, the s-wave scattering length is tuned in space, rather than in time as previously studied, by a far-off-resonant Gaussian optical field, from negative to positive in the center region of the potential well. We find that this tuning leads to coexisting repulsive and attractive interactions within a single atomic gas and consequently a stable BEC in the repulsive region. We investigate the ground-state properties of the tuned BECs and show them to exhibit a strikingly different spatial density distribution from a conventional one with a positive s-wave scattering length. The tuned BEC is formed only when the condensed number is less than a critical number. We derive a formula for the critical number.

Dong Guangjiong [Physics Department, Center for Nonlinear Studies and the Beijing-Hong Kong-Singapore Joint Center for Nonlinear and Complex Systems, Hong Kong, Kowloon Tong, Hong Kong (China); Hu Bambi [Physics Department, Center for Nonlinear Studies and the Beijing-Hong Kong-Singapore Joint Center for Nonlinear and Complex Systems, Hong Kong, Kowloon Tong, Hong Kong (China); Department of Physics, University of Houston, Houston, Texas 77204-5005 (United States); Lu Weiping [Department of Physics, Heriot-Watt University, Edinburgh, Scotland (United Kingdom)

2006-12-15

432

Exact spin liquid ground states of the quantum dimer model on the square and honeycomb lattices.  

PubMed

We study a generalized quantum hard-core dimer model on the square and honeycomb lattices, allowing for first and second neighbor dimers. At generalized Rokhsar-Kivelson points, the exact ground states can be constructed, and ground-state correlation functions can be equated to those of interacting (1+1)-dimensional Grassmann fields. When the concentration of second neighbor dimers is small, the ground-state correlations are shown to be short ranged corresponding to a (gaped) spin liquid phase. On a 2-torus, the ground states exhibit fourfold topological degeneracy. On a finite cylinder we have found a dramatic even-odd effect depending on the circumference and propose that this can be used as a numerical diagnostic of gapped spin-liquid phases, more generally. PMID:23004318

Yao, Hong; Kivelson, Steven A

2012-06-13

433

Three-Dimensional Quantum Calculations on the Ground and Excited State Vibrations of Ethylene.  

National Technical Information Service (NTIS)

Three dimensional potential energy surfaces of the ground and excited states of ethylene were calculated at the MRCEPA (Multi Reference Coupled Electronic Pair Approximation) level. The modes included are the torsion, the CC stretch, and the symmetric sci...

G. C. Groenenboom

1991-01-01

434

Imaging of quantum Hall states in ultracold atomic gases  

SciTech Connect

We examine off-resonant light scattering from ultracold atoms in the quantum Hall regime. When the light scattering is spin dependent, we show that images formed in the far field can be used to distinguish states of the system. The spatial dependence of the far-field images is determined by the two-particle spin-correlation functions, which the images are related to by a transformation. Quasiholes in the system appear in images of the density formed by collecting the scattered light with a microscope, where the quasihole statistics are revealed by the reduction in density at the quasihole position.

Douglas, James S.; Burnett, Keith [University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom)

2011-11-15

435

LASSP: The Laboratory of Atomic and Solid State Physics  

NSDL National Science Digital Library

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

436

Relativistic potential energy surfaces of initial oxidations of Si(100) by atomic oxygen: The importance of surface dimer triplet state  

NASA Astrophysics Data System (ADS)

The non-relativistic and relativistic potential energy surfaces (PESs) of the symmetric and asymmetric reaction paths of Si(100)-2×1 oxidations by atomic oxygen were theoretically explored. Although only the singlet PES turned out to exist as a major channel leading to ``on-dimer'' product, both the singlet and triplet PESs leading to ``on-top'' products are attractive. The singlet PESs leading to the two surface products were found to be the singlet combinations (open-shell singlet) of the low-lying triplet state of surface silicon dimer and the ground 3P state of atomic oxygen. The triplet state of the ``on-top'' product can also be formed by the ground singlet state of the surface silicon dimer and the same 3P oxygen. The attractive singlet PESs leading to the ``on-dimer'' and ``on-top'' products made neither the intersystem crossings from triplet to singlet PES nor high energy 1D of atomic oxygen necessary. Rather, the low-lying triplet state of surface silicon dimer plays an important role in the initial oxidations of silicon surface.

Kim, Tae-Rae; Shin, Seokmin; Choi, Cheol Ho

2012-06-01

437

Ground state study of spin-1/2 Falicov-Kimball model on a triangular lattice  

NASA Astrophysics Data System (ADS)

The ground state magnetic properties of two dimensional spin-1/2 Falicov-Kimball model on a triangular lattice are studied using numerical diagonalization with Monte Carlo simulation techniques. In the ground state we observe large range magnetic ordered phases like anti-ferromagnetic and ferromagnetic depending on different values of parameters of onsite Coulomb repulsion U and exchange correlation J. The variation of the magnetization of d- and f-electron with J is also studied.

Yadav, Umesh K.; Kumar, Sant; Maitra, T.; Singh, Ishwar

2012-06-01

438

On the Rotational Analysis of the Ground Vibrational State of CH3D Molecule  

Microsoft Academic Search

The rotational analysis in the ground vibrational state has been carried out for CH3D by using the ground state combination differences. More than 1500 allowed and 2500 forbidden transitions from the fundamental bands nu3, nu5, and nu6were used to determine 12 rotational parameters, which reproduce the observed combination differences within an accuracy of 1.0 × 10-4cm-1. Altogether ten independenta1-a2(K= 3)

O. N. Ulenikov; G. A. Onopenko; N. E. Tyabaeva; J. Schroderus; S. Alanko

1999-01-01

439

Quantum numbers for relative ground states of antiferromagnetic Heisenberg spin rings  

NASA Astrophysics Data System (ADS)

We suggest a general rule for the shift quantum numbers k of the relative ground states of antiferromagnetic Heisenberg spin rings. This rule generalizes the well-known results of Marshall, Peierls, Lieb, Schultz, and Mattis for even rings. Our rule is confirmed by numerical investigations and rigorous proofs for special cases, including systems with a Haldane gap for N??. Implications for the total spin quantum number S of relative ground states are discussed as well as generalizations to the XXZ model.

Bärwinkel, Klaus; Hage, Peter; Schmidt, Heinz-Jürgen; Schnack, Jürgen

2003-08-01

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