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1

Trapping Cold Ground State Argon Atoms  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

2

Electronic configuration in the ground state of atomic lawrencium  

Microsoft Academic Search

Self-consistent relativistic Dirac-Hartree-Fock calculations have been made of some lowlying electronic energies for the atoms of all elements in ground-state ds2 electron configurations. The results indicate that, contrary to some previous estimates, the ground electronic state of atomic Lr could be in either the 5f146d7s2 or the 5f147p7s2 electron configuration. The separation between the lowest energy level of the 5f146d7s2

L. J. Nugent; K. L. Sluis; Burkhard Fricke; J. B. Mann

1974-01-01

3

Ultracold Heteronuclear Mixture of Ground and Excited State Atoms  

E-print Network

We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in the excited metastable 3P2 state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K'2 measurements at 1064nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.

Khramov, Alexander; Dowd, William; Roy, Richard; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana; Gupta, Subhadeep

2014-01-01

4

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

E-print Network

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

Zare, Richard N.

5

Photoabsorption by ground-state alkali-metal atoms.  

NASA Technical Reports Server (NTRS)

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

Weisheit, J. C.

1972-01-01

6

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

7

Monotonicity of Quantum Ground State Energies: Bosonic Atoms and Stars  

Microsoft Academic Search

The N-dependence of the non-relativistic bosonic ground state energy ?\\u000a B\\u000a (N) is studied for quantum N-body systems with either Coulomb or Newton interactions. The Coulomb systems are “bosonic atoms,” with their nucleus fixed,\\u000a and it is shown that \\u000a \\u000a grows monotonically in N>1, where ?\\u000a C\\u000a (N)=N\\u000a 2(N?1). The Newton systems are “bosonic stars,” and it is shown that when

Michael K.-H. Kiessling

2009-01-01

8

Ultracold Heteronuclear Mixture of Ground and Excited State Atoms  

NASA Astrophysics Data System (ADS)

We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in an excited metastable (P23) state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K2'<3×10-12 cm3/s for the P23 mJ=-1 substate. We calculate the dynamic polarizabilities of the Yb(P23) magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064 nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.

Khramov, Alexander; Hansen, Anders; Dowd, William; Roy, Richard J.; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana; Gupta, Subhadeep

2014-01-01

9

Relativistic prediction of the ground state of atomic Lawrencium J.-P. Desclaux and B. Fricke (*)  

E-print Network

943 Relativistic prediction of the ground state of atomic Lawrencium J.-P. Desclaux and B. Fricke, mais en accord avec les suggestions antérieures de Brewer et de Mann, la configuration de l with earlier suggestions by Brewer and Mann, the ground state configuration of atomic Lawrencium (Z = 103

Boyer, Edmond

10

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

E-print Network

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

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

2007-11-02

11

Interactions Between Ground-State Nitrogen Atoms and Molecules  

NASA Technical Reports Server (NTRS)

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

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

1959-01-01

12

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

13

The theory of two-electron atoms: between ground state and complete fragmentation  

Microsoft Academic Search

Since the first attempts to calculate the helium ground state in the early days of Bohr-Sommerfeld quantization, two-electron atoms have posed a series of unexpected challenges to theoretical physics. Despite the seemingly simple problem of three charged particles with known interactions, it took more than half a century after quantum mechanics was established to describe the spectra of two-electron atoms

Gregor Tanner; Klaus Richter; Jan-Michael Rost

2000-01-01

14

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

15

Diffusion quantum Monte Carlo calculation of nondifferential properties for atomic ground states  

Microsoft Academic Search

An algorithm to sample the exact (within the nodal error) ground state distribution to find nondifferential properties of multielectron systems is developed and applied to first-row atoms. Calculated properties are the distribution moments and the electronic density at the nucleus (expected value of the ? operator). For this purpose compact trial functions are developed and optimized, and a new estimator

Peter Langfelder; Stuart M. Rothstein; Jan Vrbik

1997-01-01

16

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`.

17

Spin-exchange narrowing of the atomic ground-state resonances  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

18

Role of Electronic Excitations in Ground-State-Forbidden Inelastic Collisions Between Ultracold Atoms and Ions  

NASA Astrophysics Data System (ADS)

The role of electronic excitation in inelastic collisions between ultracold Ca atoms and Ba+ ions, confined in a hybrid trap, is studied for the first time. Unlike previous investigations, this system is energetically precluded from undergoing inelastic collisions in its ground state, allowing a relatively simple experimental determination and interpretation of the influence of electronic excitation. It is found that while the electronic state of the ion can critically influence the inelastic collision rate, the polarizability mismatch of the neutral atom electronic states suppresses short-range collisions, and thus inelastic processes, involving electronically excited neutral atoms. As a result of these features, it is experimentally demonstrated that it is possible to mitigate inelastic collision loss mechanisms in these systems, marking an important step toward long-lived hybrid atom-ion devices.

Sullivan, Scott T.; Rellergert, Wade G.; Kotochigova, Svetlana; Hudson, Eric R.

2012-11-01

19

Learning Approach on the Ground State Energy Calculation of Helium Atom  

SciTech Connect

This research investigated the role of learning approach on the ground state energy calculation of Helium atom in improving the concepts of science teachers at university level. As the exact solution of several particles is not possible here we used approximation methods. Using this method one can understand easily the calculation of ground state energy of any given function. Variation Method is one of the most useful approximation methods in estimating the energy eigen values of the ground state and the first few excited states of a system, which we only have a qualitative idea about the wave function.The objective of this approach is to introduce and involve university teacher in new research, to improve their class room practices and to enable teachers to foster critical thinking in students.

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

2010-07-28

20

Formation of Triplet Positron-helium Bound State by Stripping of Positronium Atoms in Collision with Ground State Helium  

NASA Technical Reports Server (NTRS)

Formation of triplet positron-helium bound state by stripping of positronium atoms in collision with ground state helium JOSEPH DI RlENZI, College of Notre Dame of Maryland, RICHARD J. DRACHMAN, NASA/Goddard Space Flight Center - The system consisting of a positron and a helium atom in the triplet state e(+)He(S-3)(sup e) was conjectured long ago to be stable [1]. Its stability has recently been established rigorously [2], and the values of the energies of dissociation into the ground states of Ps and He(+) have also been reported [3] and [4]. We have evaluated the cross-section for this system formed by radiative attachment of a positron in triplet He state and found it to be small [5]. The mechanism of production suggested here should result in a larger cross-section (of atomic size) which we are determining using the Born approximation with simplified initial and final wave functions.

Drachman, Richard J.

2006-01-01

21

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

E-print Network

We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI method (Configuration Interaction using a Perturbative Selection made Iteratively) and including the most prominent determinants of the full CI expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. The FN-DMC/(CIPSI nodes) ground-state energies presented here are, to the best of our knowledge, the most accurate values reported so far. Thanks to the variational property of FN-DMC total energies, the results also provide lower bounds for the absolute value of all-electron correlation energies, $|E_c|$.

Scemama, A; Giner, E; Caffarel, M

2014-01-01

22

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

E-print Network

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) at different voltage (V) was measured. The C-V curve shows that the saturation polarization of K, Rb or Cs vapor has be observed when the field E more than ten to the fifth power V/m. When the saturation polarization appeared, nearly all K, Rb or Cs atoms(more than 98 percent) turned toward the direction of the field, and C is approximately equal to Co (Co is vacuum capacitance) or their dielectric constant is nearly the same as vacuum! K, Rb or Cs vapor just exist in the lowest energy state, so we see the vacuum state containing a large number of atoms! Due to the saturation polarization of hydrogen vapor of excited state is easily appears, we conjecture that ...

You, Pei-Lin

2008-01-01

23

Ground State Energy of Large Atoms in a Self-Generated Magnetic Field  

Microsoft Academic Search

We consider a large atom with nuclear charge Z described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute\\u000a ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic\\u000a Thomas-Fermi theory to leading order in the simultaneous Z ? ?, ? ? 0 limit if Z\\u000a ?

László Erdos; Jan Philip Solovej

2010-01-01

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

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

26

Thermalization of fast cesium 5D3/2 atoms in collisions with ground-state cesium atoms A. P. Hickman,1  

E-print Network

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

Huennekens, John

27

Ground state energy of large atoms in a self-generated magnetic field  

E-print Network

We consider a large atom with nuclear charge $Z$ described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic Thomas-Fermi theory to leading order in the simultaneous $Z\\to \\infty$, $\\al\\to 0$ limit if $Z\\al^2\\leq \\kappa$ for some universal $\\kappa$, where $\\al$ is the fine structure constant.

Laszlo Erdos; Jan Philip Solovej

2009-03-10

28

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

PubMed

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

Yi, Zhen; Li, Gao-Xiang; Wu, Shao-Ping; Yang, Ya-Ping

2014-08-25

29

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

30

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

E-print Network

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

Huirong Yan; A. Lazarian

2008-06-23

31

arXiv:quant-ph/99050166May1999 A simple formula for ground state energy of a two-electron atom  

E-print Network

arXiv:quant-ph/99050166May1999 A simple formula for ground state energy of a two-electron atom M () A simple expression for a ground state energy for a two-electron atom is derived. For this assumption based upon the Niels Bohr "old" quantum mechanics idea about electron correlation in a two-electron atom

Auzinsh, Marcis

32

Diffusion Monte Carlo calculations for the ground states of atoms and ions in neutron star magnetic fields  

E-print Network

The diffusion quantum Monte Carlo method is extended to solve the old theoretical physics problem of many-electron atoms and ions in intense magnetic fields. The feature of our approach is the use of adiabatic approximation wave functions augmented by a Jastrow factor as guiding functions to initialize the quantum Monte Carlo prodecure. We calcula te the ground state energies of atoms and ions with nuclear charges from Z= 2, 3, 4, ..., 26 for magnetic field strengths relevant for neutron stars.

S. Bucheler; D. Engel; J. Main; G. Wunner

2007-11-30

33

The Ground State Energy of Heavy Atoms According to Brown and Ravenhall: Absence of Relativistic Effects in Leading Order  

E-print Network

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

Roch Cassanas; Heinz Siedentop

2006-03-29

34

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

PubMed Central

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

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

2009-01-01

35

Repumping ground-state population in a coherently driven atomic resonance  

E-print Network

We experimentally demonstrate an optical pumping technique to pump a dilute rubidium vapor into the mF = 0 ground states. The technique utilizes selection rules that forbid the excitation of the mF = 0 state by linearly-polarized light. A substantial increase in the transparency contrast of coherent population trapping in the clock transition is demonstrated.

Asif Sinay; Moshe Shuker; Ofer Firstenberg; Amnon Fisher; Amit Ben-Kish; Jeff Steinhauer

2010-03-14

36

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

37

Entanglement entropies in the ground states of helium-like atoms  

E-print Network

We examine the entanglement in the ground states of helium and helium-like ions using an original Hylleraas expansion. The von Neumann and linear entropies of the reduced density matrix are accurately computed by performing the Schmidt decomposition of the S singlet spatial wavefunctions. The results presented are more accurate than currently available in published literature.

Przemyslaw Koscik; Anna Okopinska

2014-04-18

38

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

PubMed Central

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

Mader, Elizabeth A.; Davidson, Ernest R.

2008-01-01

39

Ab initio properties of the ground-state polar and paramagnetic europium-alkali-metal-atom and europium-alkaline-earth-metal-atom molecules  

NASA Astrophysics Data System (ADS)

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

Tomza, Micha?

2014-08-01

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

Index of refraction engineering in five-level dressed interacting ground states atoms  

NASA Astrophysics Data System (ADS)

We present a five-level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the atoms with a control laser and rf/microwave fields. By weak incoherent pumping of the population into a single metastable state, one can create several narrow amplifying resonances. At frequencies between these gain lines and additional absorption lines, there exist regions of vanishing absorption but resonantly enhanced index of refraction. In Rb vapors with density N in units of cm-3, we predict an index of refraction up to n?1+1.2×10-14N for the D1 line, which is more than an order of magnitude larger than other proposals for index of refraction enhancement. Furthermore, the index can be readily reduced below 1 by simply changing the sign of the probe or rf field detunings. This enhancement is robust with respect to homogeneous and inhomogeneous broadening.

Sagona-Stophel, Steven A.; Weatherall, James Owen; Search, Christopher P.

2011-08-01

42

Index of refraction engineering in five-level dressed interacting ground states atoms.  

PubMed

We present a five-level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the atoms with a control laser and rf/microwave fields. By weak incoherent pumping of the population into a single metastable state, one can create several narrow amplifying resonances. At frequencies between these gain lines and additional absorption lines, there exist regions of vanishing absorption but resonantly enhanced index of refraction. In Rb vapors with density N in units of cm(-3), we predict an index of refraction up to n??(1+1.2×10(-14)N) for the D1 line, which is more than an order of magnitude larger than other proposals for index of refraction enhancement. Furthermore, the index can be readily reduced below 1 by simply changing the sign of the probe or rf field detunings. This enhancement is robust with respect to homogeneous and inhomogeneous broadening. PMID:21847183

Sagona-Stophel, Steven A; Weatherall, James Owen; Search, Christopher P

2011-08-15

43

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

44

Calculation of the ground-state energy and average distance between particles for the nonsymmetric muonic {sup 3}He atom  

SciTech Connect

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

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

2005-07-15

45

Measurement of the 87Rb ground-state hyperfine splitting in an atomic fountain  

Microsoft Academic Search

The new atomic Rb-Cs fountain should confirm the recent theoretical calculations relating to the collisions of rubidium atoms. According to this theory, the displacement of the frequency of clock due to the collisional shift was predicted to be 15 times lower for 87Rb than for 133Cs at equal density. Using Rb instead of Cs in a foundation standard may lead

S. Bize; Yvan Sortais; Marilde T. Santos; Cipriana Mandache; A. Clairon; C. Salomon

2000-01-01

46

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

NASA Astrophysics Data System (ADS)

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

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

1981-09-01

47

Crossed Molecular Beam Study on the Ground State Reaction of Atomic Boron [B(2 with Hydrogen Cyanide [HCN(X1  

E-print Network

Cyanide [HCN(X1 + )] Brant Jones,, Pavlo Matsyutenko, Nung C. Su, Agnes H. H. Chang,§ and Ralf I. Kaiser combine crossed molecular beam experiments of ground state boron atoms (2 Pj) with hydrogen cyanide Langmuir's fundamental isoelectronic concept,23,24 it is easy to rationalize that boroniso- cyanide

Kaiser, Ralf I.

48

Ground State Quantum Computation  

E-print Network

We formulate a novel ground state quantum computation approach that requires no unitary evolution of qubits in time: the qubits are fixed in stationary states of the Hamiltonian. This formulation supplies a completely time-independent approach to realizing quantum computers. We give a concrete suggestion for a ground state quantum computer involving linked quantum dots.

Ari Mizel; M. W. Mitchell; Marvin L. Cohen

1999-08-11

49

Ground State Spin Logic  

E-print Network

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

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

2012-05-08

50

Heavy atom nitroxyl radicals. I: An ab initio study of the ground and lower electronic excited states of the H2As=O free radical  

NASA Astrophysics Data System (ADS)

A series of ab initio calculations have been undertaken to predict the spectroscopic properties of the ground and first two excited states of the recently discovered arsenyl (H2AsO) free radical. This 13 valence electron species can be viewed as similar to the formaldehyde radical anion with a ground state electron configuration of ...(?)2(n)2(?*)1. The arsenyl radical is nonplanar (pyramidal) in the ground state with a 59° out-of-plane angle and a 1.67 A? AsO bond length. It has a low-lying n-?*(A~ 2A'') excited state (Te~5000 cm-1) which has a much larger out-of-plane angle (86°) and longer AsO bond length (1.81 A?). The ?-?*(B~ 2A') excited state at ~20 500 cm-1 is less pyramidal (out-of-plane angle=70°) and has a somewhat shorter AsO bond (1.77 A?). Similar trends are found for the H2PO and H2NO free radicals, although the latter has a planar ground state, due to sp2 hybridization of the N atom, and a very long B~ state AsO bond length. The geometric variations of the ground and excited states of the H2EO (E=N, P, As) radicals, as well as the ground states of the corresponding anions and cations, can be readily rationalized from the Walsh diagram of the anion. The variations in the E-O bond length are a result of changes in both the orbital occupancy and pyramidalization of the molecule. The results of the present work have been employed in the analysis of the B~ 2A'-X~ 2A' electronic band system of the H2AsO free radical as reported in the companion paper.

Tarroni, Riccardo; Clouthier, Dennis J.

2009-09-01

51

Heavy atom nitroxyl radicals. I: An ab initio study of the ground and lower electronic excited states of the H(2)As=O free radical.  

PubMed

A series of ab initio calculations have been undertaken to predict the spectroscopic properties of the ground and first two excited states of the recently discovered arsenyl (H(2)AsO) free radical. This 13 valence electron species can be viewed as similar to the formaldehyde radical anion with a ground state electron configuration of cdots, three dots, centered(pi)(2)(n)(2)(pi( *))(1). The arsenyl radical is nonplanar (pyramidal) in the ground state with a 59 degrees out-of-plane angle and a 1.67 A AsO bond length. It has a low-lying n-pi( *)(A (2)A(")) excited state (T(e) approximately 5000 cm(-1)) which has a much larger out-of-plane angle (86 degrees ) and longer AsO bond length (1.81 A). The pi-pi( *)(B (2)A(')) excited state at approximately 20 500 cm(-1) is less pyramidal (out-of-plane angle=70 degrees ) and has a somewhat shorter AsO bond (1.77 A). Similar trends are found for the H(2)PO and H(2)NO free radicals, although the latter has a planar ground state, due to sp(2) hybridization of the N atom, and a very long B state AsO bond length. The geometric variations of the ground and excited states of the H(2)EO (E=N, P, As) radicals, as well as the ground states of the corresponding anions and cations, can be readily rationalized from the Walsh diagram of the anion. The variations in the E-O bond length are a result of changes in both the orbital occupancy and pyramidalization of the molecule. The results of the present work have been employed in the analysis of the B (2)A(')-X (2)A(') electronic band system of the H(2)AsO free radical as reported in the companion paper. PMID:19778116

Tarroni, Riccardo; Clouthier, Dennis J

2009-09-21

52

Towards coherent manipulation of the ground states of single cesium atom confined in a microscopic far-off-resonance optical dipole trap  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

53

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

Microsoft Academic Search

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 nu87 = 6 834 682 610.90429(9) Hz. This value differs from previously published values (see Essen L.,

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

1999-01-01

54

Stabilization and manipulation of electronically phase-separated ground States in defective indium atom wires on silicon.  

PubMed

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

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

2014-11-01

55

Rabi Oscillations between Ground and Rydberg States with Dipole-Dipole Atomic Interactions T. A. Johnson, E. Urban, T. Henage, L. Isenhower, D. D. Yavuz, T. G. Walker, and M. Saffman  

E-print Network

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

Yavuz, Deniz

56

A simple polynomial approach to the exact perturbative evaluation of low-frequency dynamic polarizabilities for a ground-state hydrogen atom  

NASA Astrophysics Data System (ADS)

An exact perturbative method is presented for evaluating frequency-dependent multipole polarizabilities for a ground-state hydrogen atom in the range of low frequencies. The first-order correction to the unperturbed wavefunction (wf) is expanded in a power series of the frequency with radial coefficients determined by simple polynomial techniques. Almost all real frequencies having physical importance, and the corresponding imaginary frequencies, fall in the range of convergence that has been observed for the dynamic polarizability. In this range, a moderate number of terms accounts for nine decimal figure results for dipole, quadrupole and octopole FDPs of H(1s).

Figari, Giuseppe; Magnasco, Valerio

2001-07-01

57

The far-zone interatomic Casimir-Polder potential between two ground-state atoms outside a Schwarzschild black hole  

E-print Network

Based on the idea that the vacuum fluctuations of electromagnetic fields can induce instantaneous correlated dipoles, we study the far-zone Casimir-Polder potential between two atoms in the Boulware, Unruh and Hartle-Hawking vacua outside a Schwarzschild black hole. We show that, at spatial infinity, the Casimir-Polder potential in the Boulware vacuum is similar to that in the Minkowski vacuum in flat spacetime with a behavior of $R^{-7}$, so is in the Unruh vacuum as a result of the backscattering of the Hawking radiation from the black hole off the spacetime curvature. However, the interatomic Casimir-Polder potential in the Hartle-Hawking vacuum behaves like that in a thermal bath at the Hawking temperature. In the region near the event horizon of the black hole, the modifications caused by the space-time curvature make the interatomic Casimir-Polder potential smaller in all three vacuum states.

Jialin Zhang; Hongwei Yu

2014-01-20

58

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

59

Quantum fluid dynamics approach for electronic structure calculation: application to the study of ground-state properties of rare gas atoms  

NASA Astrophysics Data System (ADS)

We explore the usefulness of a quantum fluid dynamics (QFD) approach for quantitative electronic structure calculations of many-electron systems. By combining QFD and density functional theory, a single time-dependent nonlinear QFD equation can be derived. The equation is further transformed into a diffusion-type form by an imaginary-time evolution method, whose asymptotic solution reaches a global minimum and the many-body ground-state wavefunction. The time-dependent generalized pseudospectral method is extended to solve the diffusion equation in spherical coordinates, allowing optimal and nonuniform spatial discretization and accurate and efficient solution of the diffusion function in space and time. The procedure is applied to the study of electronic energies, densities and other ground-state properties of noble gas atoms (He, Ne, Ar, Kr, Xe). The results are in good agreement with other best available values. The method offers a conceptually appealing and computationally practical procedure for the treatment of many-electron systems beyond the Hartree-Fock level.

Roy, Amlan K.; Chu, Shih-I.

2002-05-01

60

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

61

Reaction of cyanoacetylene HCCCN(X 1Sigma+) with ground-state carbon atoms C(3P) in cold molecular clouds.  

PubMed

The reaction of the simplest cyanopolyyne, cyanoacetylene [HCCCN(X (1)Sigma(+))], with ground-state atomic carbon C((3)P) is investigated theoretically to explore the probable routes for the depletion of the famed interstellar molecule HCCCN, and the formation of carbon-nitrogen-bearing species in extraterrestrial environments particularly of ultralow temperature. Six collision complexes (c1-c6) without entrance barrier as a result of the carbon atom addition to the pi systems of HCCCN are located. The optimized geometries and harmonic frequencies of the intermediates, transition states, and products along the isomerization and dissociation pathways of each collision complex are obtained by utilizing the unrestricted B3YLP6-311G(d,p) level of theory, and the corresponding CCSD(T)/cc-pVTZ energies are calculated. Subsequently, with the facilitation of Rice-Ramsperger-Kassel-Marcus (RRKM) and variational RRKM rate constants at collision energy of 0-10 kcal/mol, the most probable paths for the titled reaction are determined, and the product yields are estimated. Five collision complexes (c1-c3, c5, and c6) are predicted to give the same products, a chained CCCCN (p2)+H, via the linear and most stable intermediate, HCCCCN (i2), while collision complex c4 is likely to dissociate back to C+HCCCN. The study suggests that this class of reaction is an important route to the destruction of cyanoacetylene and cyanopolyynes in general, and to the synthesis of linear carbon-chained nitriles at the temperature as low as 10 K to be incorporated in future chemical models of interstellar clouds. PMID:16460162

Li, H Y; Cheng, W C; Liu, Y L; Sun, B J; Huang, C Y; Chen, K T; Tang, M S; Kaiser, R I; Chang, A H H

2006-01-28

62

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

63

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

64

ccsd00000983 Quantum state transfer between elds and atoms  

E-print Network

ccsd­00000983 (version 1) : 23 Dec 2003 Quantum state transfer between #12;elds and atoms show that a quasi-perfect quantum state transfer between an atomic ensemble and #12;elds in an optical can be mapped onto the long-lived atomic spin associated to the ground state sublevels of the #3;-type

65

Diffusion of barium atoms in the 6s5d triplet-D(J) levels and the 6s(2) singlet-S(0) ground state through noble gas perturbers  

Microsoft Academic Search

We describe a set of experiments that investigate diffusion of barium 6s5d3D J metastable level and 6s2\\/ 1S0 ground state atoms through the noble gases: He, Ne, Ar, Kr, and Xe. The barium metastable levels were populated through optical pumping of the 6s2\\/ 1S0 \\/to 6s6p 3P1o intercombination transition with a pulsed laser, followed by spontaneous or stimulated emission into

Raychel Kristine Namiotka

1998-01-01

66

Spin state of iron--the control parameter of iron-containing HTSC: Dependence of ground state energy, phonon energies and atom positions on the spin state of iron ion in FeTe  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

67

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

68

A theoretical study of the of DNA/RNA nucleobases interacting with noble metal atoms: the gold and silver cases. Part I: Ground state properties  

E-print Network

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

Leal, Leonardo Andres Espinosa

2014-01-01

69

Physics 216 Spring 2012 The Variational Computation of the Ground State Energy of Helium  

E-print Network

Physics 216 Spring 2012 The Variational Computation of the Ground State Energy of Helium I. Introduction to the variational computation The Hamiltonian for the two­electron system of the helium atom is principle to compute the ground state energy of the helium atom. The ground state wave function

California at Santa Cruz, University of

70

Physics 139B Fall 2009 The Variational Computation of the Ground State Energy of Helium  

E-print Network

Physics 139B Fall 2009 The Variational Computation of the Ground State Energy of Helium I. Introduction to the variational computation The Hamiltonian for the two­electron system of the helium atom is principle to compute the ground state energy of the helium atom. The ground state wave function

California at Santa Cruz, University of

71

Physics 139B Fall 2009 The Variational Computation of the Ground State Energy of Helium  

E-print Network

Physics 139B Fall 2009 The Variational Computation of the Ground State Energy of Helium I. Introduction to the variational computation The Hamiltonian for the two-electron system of the helium atom is state energy of the helium atom. The ground state wave function of the helium atom is of the form: 1 2

California at Santa Cruz, University of

72

Physics 216 Spring 2012 The Variational Computation of the Ground State Energy of Helium  

E-print Network

Physics 216 Spring 2012 The Variational Computation of the Ground State Energy of Helium I. Introduction to the variational computation The Hamiltonian for the two-electron system of the helium atom is state energy of the helium atom. The ground state wave function of the helium atom is of the form: 1 2

California at Santa Cruz, University of

73

Properties of the ground 3F2 state and the excited 3P0 state of atomic thorium in cold collisions with He3  

NASA Astrophysics Data System (ADS)

Inelastic cross sections for collisions between thorium (Th) and helium (He3) are measured. For Th[3F2]-He3, we determine the ratio of momentum transfer to Zeeman relaxation cross sections to be ? ˜500 at 800 mK. For Th[3P0]-He3, we find no quenching of this metastable state during 106 collisions. We measure the radiative lifetime of Th[3P0] to be ? >130 ms. The observed stability of Th[3P0] opens up the possibility of trapping this metastable species.

Au, Yat Shan; Connolly, Colin B.; Ketterle, Wolfgang; Doyle, John M.

2014-09-01

74

Atomic and Molecular Calculations with the Pseudopotential Method. V. Two-Valence-Electron Energy Values and Oscillator Strengths for Some (ns)2 Ground States and (nsml) Singly Excited States  

Microsoft Academic Search

The pseudopotential method is applied to a number of two-valence-electron ground states and singly excited states. For the (ns)2 ground-state configurations of Li?, Na?, K?, Rb?, Cu?, Ag?, Be, Mg, Ca, Zn, and Al+ a two-electron pseudopotential equation equivalent to the Hartree–Fock equation is solved. For Be and Ca a number of singly excited states of the form (nsml) are

George McGinn

1969-01-01

75

Communication: First observation of ground state I({sup 2}P{sub 3/2}) atoms from the CH{sub 3}I photodissociation in the B-band  

SciTech Connect

The photodissociation of CH{sub 3}I in the second absorption band (the B-band) has been studied at the wavelength 199.11 nm, coincident with the 3{sub 0}{sup 1} {sup 3}R{sub 1}(E)(leftarrow)X(tilde sign)({sup 1}A{sub 1}) CH{sub 3}I vibronic transition, using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the CH{sub 3} fragment. The kinetic energy and angular distributions of the recoiling CH{sub 3} fragment confirm a major predissociation dynamics channel as a result of the interaction between the bound {sup 3}R{sub 1} Rydberg state and the repulsive {sup 3}A{sub 1}(E) state - ascribed to the A-band - yielding CH{sub 3} fragments in correlation with spin-orbit excited I*({sup 2}P{sub 1/2}) atoms. In addition, first evidence of a non-negligible population of ground state I({sup 2}P{sub 3/2}) atoms in the CH{sub 3} fragment slice images, suggests a secondary predissociation mechanism via interaction between the {sup 3}R{sub 1} Rydberg state and the repulsive A-band {sup 1}Q{sub 1} state.

Gonzalez, M. G.; Rodriguez, J. D.; Rubio-Lago, L.; Banares, L. [Departamento de Quimica Fisica I, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

2011-07-14

76

Ground-State Spaces of Frustration-Free Hamiltonians  

E-print Network

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

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

2011-12-04

77

PEPS as ground states: Degeneracy and topology  

SciTech Connect

We introduce a framework for characterizing Matrix Product States (MPS) and Projected Entangled Pair States (PEPS) in terms of symmetries. This allows us to understand how PEPS appear as ground states of local Hamiltonians with finitely degenerate ground states and to characterize the ground state subspace. Subsequently, we apply our framework to show how the topological properties of these ground states can be explained solely from the symmetry: We prove that ground states are locally indistinguishable and can be transformed into each other by acting on a restricted region, we explain the origin of the topological entropy, and we discuss how to renormalize these states based on their symmetries. Finally, we show how the anyonic character of excitations can be understood as a consequence of the underlying symmetries.

Schuch, Norbert, E-mail: norbert.schuch@googlemail.co [California Institute of Technology, Institute for Quantum Information, MC 305-16, Pasadena, CA 91125 (United States); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching (Germany); Cirac, Ignacio [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching (Germany); Perez-Garcia, David [Dpto. Analisis Matematico and IMI, Universidad Complutense de Madrid, 28040 Madrid (Spain)

2010-10-15

78

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

79

Ground state terahertz quantum cascade lasers  

E-print Network

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

Hu, Qing

80

A theoretical study for the reaction of vinyl cyanide C2H3CN(X1A') with the ground state carbon atom C(3P) in cold molecular clouds.  

PubMed

The reaction of the ground state atomic carbon, C(3P), with simple unsaturated nitrile, C2H3CN(X1A' (vinyl cyanide), is investigated theoretically to explore the probable routes for the formation of carbon-nitrogen-bearing species in extraterrestrial environments particularly of ultralow temperature. Five collision complexes without entrance barrier as a result of the carbon atom addition to the pi systems of C2H3CN are characterized. The B3YLP/6-311G(d,p) level of theory is utilized in obtaining the optimized geometries, harmonic frequencies, and energies of the intermediates, transition states, and products along the isomerization and dissociation pathways of each collision complex. Subsequently, with the facilitation of computed RRKM rate constants at collision energy of 0-10 kcal/mol, the most probable paths for each collision complexes are determined, of which the CCSD(T)/6-311G(d,p) energies are calculated. The major products predicted are exclusively due to the hydrogen atom dissociations, while the products of H2, CN, and CH2 decompositions are found negligible. Among many possible H-elimination products, cyano propargyl (p4) and 3-cyano propargyl (p5) are the most probable, in which p5 can be formed via two intermediates, cyano allene (i8) and cyano vinylmethylene (i6), while p4 is yielded from i8. The study suggests this class of reaction is an important route to the synthesis of unsaturated nitriles at the temperature as low as 10 K, and the results are valuable for future chemical models of interstellar clouds. PMID:15743245

Su, Hsiu-Fen; Kaiser, R I; Chang, A H H

2005-02-15

81

Variational calculation of ground-state energy of iron atoms and condensed matter in strong magnetic fields. [at neutron star surfaces  

NASA Technical Reports Server (NTRS)

Variational calculations of the binding energies of iron atoms and condensed matter in strong magnetic fields (greater than 10 to the 12th gauss). These calculations include the electron exchange energy. The cohesive energy of the condensed matter, which is the difference between these two binding energies, is of interest in pulsar theories and in the description of the surfaces of neutron stars. It is found that the cohesive energy ranges from 2.6 keV to 8.0 keV.

Flowers, E. G.; Ruderman, M. A.; Lee, J.-F.; Sutherland, P. G.; Hillebrandt, W.; Mueller, E.

1977-01-01

82

Ground States of Two-Dimensional Polyampholytes  

E-print Network

We perform an exact enumeration study of polymers formed from a (quenched) random sequence of charged monomers $\\pm q_0$, restricted to a 2-dimensional square lattice. Monomers interact via a logarithmic (Coulomb) interaction. We study the ground state properties of the polymers as a function of their excess charge $Q$ for all possible charge sequences up to a polymer length N=18. We find that the ground state of the neutral ensemble is compact and its energy extensive and self-averaging. The addition of small excess charge causes an expansion of the ground state with the monomer density depending only on $Q$. In an annealed ensemble the ground state is fully stretched for any excess charge $Q>0$.

Eilon Brenner; Yacov Kantor

1997-08-01

83

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

84

Mimicking Time Evolution within a Quantum Ground State: Ground-State Quantum Computation, Cloning, and Teleportation  

E-print Network

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

Ari Mizel

2003-12-09

85

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

86

Cavity optomechanics -- beyond the ground state  

NASA Astrophysics Data System (ADS)

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

Meystre, Pierre

2011-06-01

87

Coherent States for the Hydrogen Atom  

E-print Network

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

John R. Klauder

1995-11-23

88

The Ground State Rotational Spectrum of Formaldehyde  

Microsoft Academic Search

The ground state rotational spectrum has been measured from 1 to 2600 GHz. These new measurements together with the older ones have been fitted to a standardA-reduced Watson-type Hamiltonian. The accuracy of the rotational and centrifugal distortion (including some octic ones) constants has been notably improved. The experimental constants are compared to theab initioones.

R. Bocquet; J. Demaison; L. Poteau; M. Liedtke; S. Belov; K. M. T. Yamada; G. Winnewisser; C. Gerke; J. Gripp; Th. Köhler

1996-01-01

89

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

90

Product-state approximations to quantum ground states  

E-print Network

The local Hamiltonian problem consists of estimating the ground-state energy (given by the minimum eigenvalue) of a local quantum Hamiltonian. It can be considered as a quantum generalization of constraint satisfaction ...

Brandao, Fernando G.S.L.

91

Ground state connectivity of local Hamiltonians  

E-print Network

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

Sevag Gharibian; Jamie Sikora

2014-09-10

92

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

93

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

94

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

95

Testing quantum electrodynamics in the lowest singlet states of beryllium atom Mariusz Puchalski and Jacek Komasa  

E-print Network

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

Pachucki, Krzysztof

96

Condensed ground states of frustrated Bose-Hubbard models  

SciTech Connect

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

Moeller, G.; Cooper, N. R. [Theory of Condensed Matter Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2010-12-15

97

Geometric renormalization below the ground state  

E-print Network

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

Paul Smith

2010-09-30

98

State-independent teleportation of an atomic state between two cavities  

E-print Network

A scheme is presented for the teleportation of an unknown atomic state between two separated cavities. The scheme involves two interaction-detection cycles and uses resonantly coupled atoms with an additional ground state not coupled to the cavity field. Remarkably, the damping of one basis state is balanced by that of the other basis state and the state with photon loss in the first interaction-detection cycle is eliminated by the second cycle. Therefore, the fidelity of teleportation is independent of the teleported state and insensitive to the atomic spontaneous emission, cavity decay, and detection inefficiency, which is obviously in contrast to the original scheme by Bose et al. Phys. Rev. Lett. 83 5158 (1999).

Zheng, Shi-Biao

2012-01-01

99

A Model Ground State of Polyampholytes  

E-print Network

The ground state of randomly charged polyampholytes is conjectured to have a structure similar to a necklace, made of weakly charged parts of the chain, compacting into globules, connected by highly charged stretched `strings'. We suggest a specific structure, within the necklace model, where all the neutral parts of the chain compact into globules: The longest neutral segment compacts into a globule; in the remaining part of the chain, the longest neutral segment (the 2nd longest neutral segment) compacts into a globule, then the 3rd, and so on. We investigate the size distributions of the longest neutral segments in random charge sequences, using analytical and Monte Carlo methods. We show that the length of the n-th longest neutral segment in a sequence of N monomers is proportional to N/(n^2), while the mean number of neutral segments increases as sqrt(N). The polyampholyte in the ground state within our model is found to have an average linear size proportional to sqrt(N), and an average surface area proportional to N^(2/3).

Shay Wolfling; Yacov Kantor

1998-01-01

100

Antimatter Advances Include Trapped Antihydrogen in Its Ground State  

NASA Astrophysics Data System (ADS)

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

Richerme, Phil

2012-06-01

101

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

2013-04-26

102

Different ground-state potentials for the same ultracold-collision outcome  

Microsoft Academic Search

For ultracold strontium atoms colliding at 1 ?K, we search for and determine a class of continuous deformations of the ground-state potential curve, under which scattering results are invariant. We search for these potential transformations by keeping track of the changes in the scattering length and photoassociation probabilities (X1?g+?1?u+), as we systematically vary a suitable parametric description of the ground-state

E. M. S. Ribeiro; A. L. M. Zanelatto; R. d. J. Napolitano

2004-01-01

103

Teleportation of an atomic momentum state  

E-print Network

of the Bragg diffraction of atoms from the cavity field @20# and the possibility of generating photon number states inside a high-Q cavity @21# makes the proposed scheme experimentally realizable. We would like to thank Tomas Opatrny for useful discus... of the Bragg diffraction of atoms from the cavity field @20# and the possibility of generating photon number states inside a high-Q cavity @21# makes the proposed scheme experimentally realizable. We would like to thank Tomas Opatrny for useful discus...

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

2003-01-01

104

Ground state of high-density matter  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

105

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

106

Quantum state manipulation of trapped atomic ions  

E-print Network

discussed in this paper. In figure 1, we show schematically a `linear' Paul trap. This trap is based computation; quantum optics; quantum state engineering; trapped atoms 1. Introduction Currently, a major theme oscillating electric fields. The operation of these traps is discussed in various reviews (for example, see

107

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

108

Quantum state transfer between field and atoms in Electromagnetically Induced Transparency  

E-print Network

We show that a quasi-perfect quantum state transfer between an atomic ensemble and fields in an optical cavity can be achieved in Electromagnetically Induced Transparency (EIT). A squeezed vacuum field state can be mapped onto the long-lived atomic spin associated to the ground state sublevels of the Lambda-type atoms considered. The EIT on-resonance situation show interesting similarities with the Raman off-resonant configuration. We then show how to transfer the atomic squeezing back to the field exiting the cavity, thus realizing a quantum memory-type operation.

Aurelien Dantan; Michel Pinard

2003-12-23

109

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

110

Simulations of Ground and Space-Based Oxygen Atom Experiments  

NASA Technical Reports Server (NTRS)

A low-earth orbit (LEO) materials erosion scenario and the ground-based experiment designed to simulate it are compared using the direct-simulation Monte Carlo (DSMC) method. The DSMC model provides a detailed description of the interactions between the hyperthermal gas flow and a normally oriented flat plate for each case. We find that while the general characteristics of the LEO exposure are represented in the ground-based experiment, multi-collision effects can potentially alter the impact energy and directionality of the impinging molecules in the ground-based experiment. Multi-collision phenomena also affect downstream flux measurements.

Finchum, A. (Technical Monitor); Cline, J. A.; Minton, T. K.; Braunstein, M.

2003-01-01

111

Two interpretations of the cerocene electronic ground state  

NASA Astrophysics Data System (ADS)

Two alternative interpretations are given for the electronic ground state of bis-?8-annulene[8] cerium, cerocene, based on the same relativistic Douglas-Kroll-Hess complete active space all-electron wavefunction. Rotations in the spaces of the one- and many-electron wavefunctions, leaving the total energy invariant, show that the system can be viewed as a complex of a closed-shell Ce(IV) ion sandwiched by two aromatic annulene[8] dianions and bonded with a significant Ce 4f - ring ? covalency, or as a Ce(III) ion with an almost atomic-like 4f1 subconfiguration, coupled to the unpaired electron in the rings highest energy occupied ? orbitals in a Kondo-type fashion.

Mooßen, Oliver; Dolg, Michael

2014-02-01

112

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

2013-07-12

113

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

114

Ground-state energies for the helium isoelectronic series  

SciTech Connect

Variational calculations are reported for the ground state of the helium isoelectronic series. An ansatz is introduced and it achieves an accuracy comparable to that hitherto achieved only with basis functions containing logarithmic terms. Energies accurate to better than one part in 10[sup 14] are obtained for the ground states of He through Ne[sup 8+] using 308-term expansions, and the ground state of H[sup [minus

Thakkar, A.J. (Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 6E2 (Canada)); Koga, T. (Department of Applied Chemistry, Muroran Institute of Technology, Muroran, Hokkaido 050 (Japan))

1994-07-01

115

Atomic Fock State Preparation Using Rydberg Blockade Matthew Ebert,*  

E-print Network

Atomic Fock State Preparation Using Rydberg Blockade Matthew Ebert,* Alexander Gill, Michael 2014) We use coherent excitation of 3­16 atom ensembles to demonstrate collective Rabi flopping mediated by Rydberg blockade. Using calibrated atom number measurements, we quantitatively confirm

Yavuz, Deniz

116

Quantum diffusion computations of two-electron ground-state energies  

SciTech Connect

A quantum Monte Carlo technique to compute ground-state energies of He, H/sup -/, and Ps/sup -/ is described. Coordinates appropriate to a molecular description of atoms are used, and results with good accuracy are obtained upon input of essentially just reduced masses and the nuclear charge. The method minimizes the need to construct sophisticated variational or basis functions.

Beckmann, C.E.; Feagin, J.M.

1987-11-01

117

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

118

Coherent States for the Hydrogen Atom John R. Klauder  

E-print Network

) enjoy the property that the temporal evolution of any coherent state by the hydrogen atom HamiltonianCoherent States for the Hydrogen Atom by John R. Klauder Departments of Physics and Mathematics for the (bound state portion of the) hydrogen atom is positively resolved. The states in question: (i

119

Photoelectron imaging of NCCCN-: The triplet ground state and the  

E-print Network

; accepted 5 May 2010; published online 8 June 2010 The photoelectron spectra of NCCCN- have been measured, corresponding to the ground and first excited states of dycianocarbene. With support from theoretical calculations using the spin-flip coupled-cluster methods, the ground electronic state of HCCCN is assigned

Sanov, Andrei

120

Theory of Ground State Factorization in Quantum Cooperative Systems  

Microsoft Academic Search

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

Salvatore M. Giampaolo; Gerardo Adesso; Fabrizio Illuminati

2008-01-01

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

122

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

E-print Network

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

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

2014-07-14

123

Arsenic in ground water of the United States  

NSDL National Science Digital Library

From the USGS National Analysis of Trace Elements, this new page offers a recent, much publicized map "that shows where and to what extent arsenic occurs in ground water across the country," a new fact sheet ("Arsenic in ground-water resources of the United States"), and a detailed report ("A retrospective analysis on the occurrence of arsenic in ground-water resources of the US and limitations in drinking-water-supply characterizations"). The site also contains data of arsenic concentrations for 18,850 ground-water samples collected between 1973 and 1997. In addition, users will find links to other sites with information on arsenic in ground water.

124

Ground state configurations in antiferromagnetic ultrathin films with dipolar anisotropy  

NASA Astrophysics Data System (ADS)

The formalism developed in a previous work to calculate the dipolar energy in quasi-two-dimensional crystals with ferromagnetic order is now extended to collinear antiferromagnetic order. Numerical calculations of the dipolar energy are carried out for systems with tetragonally distorted fcc [001] structures, the case of NiO and MnO ultrathin film grown in non-magnetic substrates, where the magnetic phase is a consequence of superexchange and dipolar interactions. The employed approximation allows to demonstrate that dipolar coupling between atomic layers is responsible for the orientation of the magnetization when it differs from the one in a single layer. The ground state energy of a given NiO or MnO film is found to depend not only on the strain, but also on how much the interlayer separation and the 2D lattice constant are changed with respect to the ideal values corresponding to the non-distorted cubic structure. Nevertheless, it is shown that the orientation of the magnetization in the magnetic phase of any of these films is determined by the strain exclusively. A striped phase with the magnetization along the [112¯] direction appears as the ground state configuration of NiO and MnO ultrathin films. In films with equally oriented stripes along the layers this magnetic phase is twofold degenerate, while in films with multidomain layers it is eightfold degenerate. These results are not in contradiction with experimentally observed out-of-plane or in-plane magnetization of striped phases in NiO and MnO ultrathin films.

León, H.

2013-02-01

125

Inequivalent electron densities derived from an approximate correlated ground-state wave function using the Hiller-Sucher-Feinberg identity: Comparisons with quantum Monte Carlo densities for He and Ne atoms  

Microsoft Academic Search

The Hiller-Sucher-Feinberg (HSF) identity is combined with the three-parameter correlated wave function of Chandrasekhar in order to generate an alternative electron density rho(r) for the He atom. This and the conventional \\

Claudio Amovilli; Norman H. March

2009-01-01

126

Ground state cooling in a bad cavity  

E-print Network

We study the mechanical effects of light on an atom trapped in a harmonic potential when an atomic dipole transition is driven by a laser and it is strongly coupled to a mode of an optical resonator. We investigate the cooling dynamics in the bad cavity limit, focussing on the case in which the effective transition linewidth is smaller than the trap frequency, hence when sideband cooling could be implemented. We show that quantum correlations between the mechanical actions of laser and cavity field can lead to an enhancement of the cooling efficiency with respect to sideband cooling. Such interference effects are found when the resonator losses prevail over spontaneous decay and over the rates of the coherent processes characterizing the dynamics.

Stefano Zippilli; Giovanna Morigi; Wolfgang P. Schleich

2006-03-27

127

On the ground state of Yang-Mills theory  

E-print Network

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.

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

2011-02-17

128

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

2012-07-01

129

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

NASA Astrophysics Data System (ADS)

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

Qian, Yibin; Ren, Zhongzhou

2012-02-01

130

Handbook for state ground water managers  

SciTech Connect

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

Not Available

1992-05-01

131

GROUND-WATER PROTECTION IN THE UNITED STATES  

Microsoft Academic Search

Ground water is a vital natural resource in the United States. It is a major source for drinking water, agriculture, and industry; and is the source of drinking water for 50 percent of the Nation's population and 95 percent of the rural population. We have relied on ground water for generations with little thought given to the possibility of contaminating

John E. Moore

132

Discriminating 16 Mutually Orthogonal 4-ATOM Cluster States via Cavity QED in Teleporting Arbitrary Unknown Two-Atom State with a 4-ATOM Cluster State as Quantum Channel  

NASA Astrophysics Data System (ADS)

We propose a scheme for discriminating 16 mutually orthogonal 4-atom cluster entangled states (CES) via cavity QED in teleporting an arbitrary unknown two-atom state with a 4-atom CES as quantum channel. Utilizing the interaction of atoms with cavity and classical field, the complicated 4-atom CESs are transformed into the simple 4-atom product states. Hence the difficulty of measurement during the teleportation process is degraded. In the present scheme, we allow for the case of a strong classical driving field and the detuning between the atoms and the cavity is assumed large enough. Thereby the photon-number-dependent parts in the effective Hamiltonian can be neglected, and the scheme is insensitive to both the cavity decay and the thermal field.

Zhang, Wen; Liu, Yi-Min; Wang, Zhang-Yin; Zhang, Zhan-Jun

133

Quantum states of a hydrogen atom adsorbed on Cu(100) and (110) surfaces  

NASA Astrophysics Data System (ADS)

Quantum states of a hydrogen atom adsorbed on Cu(100) and Cu(110) are studied theoretically. In calculating eigenenergies and wave functions of hydrogen atom motion, three-dimensional adiabatic potential energy surfaces (PESs) are constructed within density functional theory and the Schrödinger equation for hydrogen atom motion on the PESs is solved by the variation method. The wave function on Cu(100) indicates a localized mode on the hollow (HL) site at the ground state. Wave functions of the first few excited states indicate vibrational modes on the HL site and suggest migration from an HL site to a neighboring HL site over the bridge (BR) site. In the case of Cu(110) , the ground state wave function is spread from the short bridge (SB) site and to the pseudothreefold (PT) site. The first few excited states are vibrational modes centered at the SB and long bridge (LB) sites. The excited state wave function of the hydrogen atom motion on Cu(110) show isotope effects as follows. The fourth excited state wave function for the H atom motion shows a localized character on the LB site, and those for D and T atom motion show vibrational modes parallel to the surface. On the other hand, the fifth excited state wave functions for D and T atom motion show localized characters on the LB site and that for H atom motion shows a vibrational mode parallel to the surface. Our calculated eigenenergies of the hydrogen atom motion in excited states on Cu(100) and Cu(110) are fairly in agreement with their corresponding experimental findings.

Ozawa, Nobuki; Roman, Tanglaw; Nakanishi, Hiroshi; Diño, Wilson Agerico; Kasai, Hideaki

2007-03-01

134

Separability and ground state factorization in quantum spin systems  

E-print Network

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

Giampaolo, S M; Illuminati, F

2009-01-01

135

Nonplanar ground states of frustrated antiferromagnets on an octahedral lattice  

E-print Network

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

Henley, Christopher L.

136

Nonlinear Faraday rotation and detection of superposition states in cold atoms  

SciTech Connect

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

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

2010-05-15

137

STATE WATER RESOURCES RESEARCH INSTITUTE PROGRAM: GROUND WATER RESEARCH.  

USGS Publications Warehouse

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

Burton, James, S.

1985-01-01

138

Magnetic Moment of the Ground State of 17C  

Microsoft Academic Search

Based on the beta-NMR method on spin-polarized radioactive-isotope beams, magnetic moments of the ground state of light unstable nuclei have been measured. In this paper, we report on a recent result obtained in the g-factor measurement for the 17C ground state. In the case of 17C, the g-factor is extremely sensitive to whether the spin-parity is 1\\/2+ or 3\\/2+, which

H. Ueno; A. Yoshimi; W. Sato; H. Watanabe; K. Yoneda; Y. Kobayashi; A. Yoshida; T. Kubo; M. Ishihara; K. Asahi; H. Ogawa; H. Miyoshi; D. Kameda; T. Suga; K. Ohno; K. Sakai; K. Yogo; N. Imai

2002-01-01

139

Ground state hyperfine structure in muonic lithium ions  

E-print Network

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

Martynenko, A P

2014-01-01

140

Ground state hyperfine structure in muonic lithium ions  

E-print Network

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

A. P. Martynenko; A. A. Ulybin

2014-11-12

141

Theory of ground state factorization in quantum cooperative systems  

E-print Network

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

Giampaolo, S M; Illuminati, F

2008-01-01

142

Theory of ground state factorization in quantum cooperative systems  

E-print Network

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

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

2008-04-01

143

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

E-print Network

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

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

2012-09-25

144

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

NASA Technical Reports Server (NTRS)

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

Minton, Timothy K.

1995-01-01

145

Exploring chaos in the Dicke model using ground-state fidelity and Loschmidt echo  

NASA Astrophysics Data System (ADS)

We study the quantum critical behavior of the Dicke Hamiltonian with finite number of atoms and explore the signature of quantum chaos using measures like the ground-state fidelity and the Loschmidt echo and the time-averaged Loschmidt echo. We show that these quantities clearly point to the classically chaotic nature of the system in the superradiant (SR) phase. While the ground-state fidelity shows aperiodic oscillations as a function of the coupling strength, the echo shows aperiodic oscillations in time and decays rapidly when the system is in the SR phase. We clearly demonstrate how the time-averaged value of the echo already incorporates the information about the ground-state fidelity and stays much less than unity, indicating the classically chaotic nature of the model in the SR phase.

Bhattacharya, Utso; Dasgupta, Sayak; Dutta, Amit

2014-08-01

146

Population Inversion between Uncoupled Atomic States through Cavity Modes  

Microsoft Academic Search

A theory for the position-dependent dynamics of an atom confined in a cavity with a movable-boundary mirror is developed. The mirror motion induces substantial transition between two optically uncoupled atomic states.

Takashi Taneichi; Takayoshi Kobayashi

1998-01-01

147

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

148

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

149

PHYSICAL REVIEW A 84, 062512 (2011) XUV frequency-comb metrology on the ground state of helium  

E-print Network

PHYSICAL REVIEW A 84, 062512 (2011) XUV frequency-comb metrology on the ground state of helium in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p 1 P with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium

150

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

151

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

152

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

153

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

NASA Astrophysics Data System (ADS)

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

Darmawan, Andrew S.; Bartlett, Stephen D.

2014-07-01

154

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

E-print Network

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

Andrew S. Darmawan; Stephen D. Bartlett

2014-03-10

155

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

156

All-optical scheme for strongly enhanced production of a Bose-Einstein condensate of dipolar molecules in the vibronic ground state  

SciTech Connect

We consider two-color heteronuclear photoassociation of a dual-species Bose-Einstein condensate into a Bose-Einstein condensate of dipolar molecules in the J=1 vibronic ground state, where a free-ground laser couples atoms directly to the ground state and a free-bound laser couples the atoms to an electronically excited state. This problem raises an interest because heteronuclear photoassociation from atoms to near-ground-state molecules is limited by the small size of the target state. Nevertheless, the addition of the electronically excited state creates a second pathway for creating molecules in the vibronic ground state, leading to quantum interference between direct photoassociation and photoassociation via the excited molecular state, as well as a dispersivelike shift of the free-ground resonance position. Using LiNa as an example, these results are shown to depend on the detuning and intensity of the free-bound laser, as well as the semiclassical size of both molecular states. Whereas strong enhancement enables saturation of the free-ground transition, coherent conversion from a two-species condensate of atoms to a condensate of dipolar molecules in the vibronic ground state is only possible for a limited range of free-bound detunings near resonance.

Mackie, Matt [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Debrosse, Catherine [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Department of Biology, Temple University, Philadelphia, Pennsylvania 19122 (United States)

2010-04-15

157

Metastable Dark States Enable Ground State Depletion Microscopy of Nitrogen Vacancy  

E-print Network

(triplet or redox) state. In the variant called SSIM (saturable structured illumination microscopy),14Metastable Dark States Enable Ground State Depletion Microscopy of Nitrogen Vacancy Centers with a resolution >10 times beyond the diffraction barrier (Microscopy, color center, diamond

Hell, Stefan W.

158

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. PMID:23843744

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

2013-01-01

159

Ground state destabilization by anionic nucleophiles contributes to the activity of phosphoryl transfer enzymes.  

PubMed

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 P(i) was determined from pH dependencies of the binding of Pi and tungstate, a P(i) analog lacking titratable protons over the pH range of 5-11, and from the ³¹P chemical shift of bound P(i). 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 ?10?-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 P(i) binding geometry upon removal of Ser102, suggesting that the destabilization does not result from a major structural rearrangement upon mutation of Ser102. Analogous Pi binding measurements with a protein tyrosine phosphatase suggest the generality of this ground state destabilization mechanism. Our results have uncovered an important contribution of anionic nucleophiles to phosphoryl transfer catalysis via ground state electrostatic destabilization and an enormous capacity of the AP active site for specific and strong recognition of the phosphoryl group in the transition state. PMID:23843744

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

2013-07-01

160

Ground-state hyperfine splitting in the Be+ ion  

NASA Astrophysics Data System (ADS)

Relativistic and QED corrections are calculated for the hyperfine splitting (hfs) in the 2S1/2 ground state of Be9+ ions with an exact account for electronic correlations. The achieved accuracy is sufficient to determine the finite nuclear size effects from the comparison to the experimental hfs value. The obtained results establish the ground to determine the neutron halo in Be11.

Puchalski, Mariusz; Pachucki, Krzysztof

2014-03-01

161

Ground States for Mean Field Models with a Transverse Component  

NASA Astrophysics Data System (ADS)

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

Ioffe, Dmitry; Levit, Anna

2013-06-01

162

Probing Quantum Frustrated Systems via Factorization of the Ground State  

E-print Network

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

Salvatore M. Giampaolo; Gerardo Adesso; Fabrizio Illuminati

2009-06-24

163

Emergent Structure of Multidislocation Ground States in Curved Crystals  

NASA Astrophysics Data System (ADS)

We study the structural features and underlying principles of multidislocation ground states of a crystalline spherical cap. In the continuum limit where the ratio of crystal size to lattice spacing W/a diverges, dislocations proliferate and ground states approach a characteristic sequence of structures composed of radial grain boundaries ("neutral scars"), extending radially from the boundary and terminating in the bulk. Employing a combination of numerical simulations and asymptotic analysis of continuum elasticity theory, we prove that an energetic hierarchy gives rise to a structural hierarchy, whereby dislocation number and scar number diverge as a/W?0 while scar length and dislocation number per scar become independent of lattice spacing. We characterize a secondary transition occurring as scar length grows, where the n-fold scar symmetry is broken and ground states are characterized by polydisperse, forked-scar morphologies.

Azadi, Amir; Grason, Gregory M.

2014-06-01

164

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

E-print Network

Comment on "Scheme for teleportation of an unknown atomic state without the Bell-state measurement, 054303 2004 have presented a scheme for implementing quantum teleportation of atomic states in cavity QED presented a scheme for implementing quantum teleportation 2 of an unknown atomic state in cavity QED

Wójcik, Antoni

165

Ground state alignment as a tracer of interplanetary magnetic field  

NASA Astrophysics Data System (ADS)

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

Yan, H.

2012-12-01

166

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

E-print Network

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

Mason A. Porter; Predrag Cvitanovic

2005-05-11

167

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

Microsoft Academic Search

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

Mason A. Porter; Predrag Cvitanovic

2005-01-01

168

Molecular vortex generated from an atom-molecule dark state  

SciTech Connect

We consider a Raman photoassociation model in a field configuration in which a Gaussian and a first-order Laguerre Gaussian laser field are applied between the bound-bound and free-bound transitions, respectively. We show that such a configuration can lead to a coherent population trapping superposition of an atomic condensate and a ground molecular vortex of unit winding number. We develop stimulated Raman adiabatic passages that minimize the effect of mean-field shifts due to collisions, for optimal conversion of an atomic condensate into a ground molecular vortex.

Ling, H. Y. [Key Laboratory of Optical and Magnetic Resonance Spectroscopy (Ministry of Education), Department of Physics, East China Normal University, Shanghai 200062 (China); Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028-1700 (United States); Yi, S. [Department of Physics and Astronomy, and Rice Quantum Institute, Rice University, Houston, Texas 77251-1892 (United States); Institute of Theoretical Physics, The Chinese Academy of Science, Beijing 100080 (China); Pu, H. [Department of Physics and Astronomy, and Rice Quantum Institute, Rice University, Houston, Texas 77251-1892 (United States); Grochowski, D. E. [Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028-1700 (United States); Zhang Weiping [Key Laboratory of Optical and Magnetic Resonance Spectroscopy (Ministry of Education), Department of Physics, East China Normal University, Shanghai 200062 (China)

2006-05-15

169

Ground-state masses and magnetic moments of heavy baryons  

NASA Astrophysics Data System (ADS)

In this work, we study single, double and triple heavy-flavor baryons using the hypercentral approach in the framework of the non-relativistic quark model. Considering two different confining potentials and an improved form of the hyperfine interaction, we calculate the ground-state masses of heavy baryons and also the ground-state magnetic moments of single charm and beauty baryons with JP = 3/2+. The obtained results are in good agreement with experimental data and those of other works.

Ghalenovi, Zahra; Rajabi, Ali Akbar; Qin, Si-Xue; Rischke, Dirk H.

2014-06-01

170

From local to global ground states in Ising spin glasses  

E-print Network

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

Ilia Zintchenko; Matthew B. Hastings; Matthias Troyer

2014-08-08

171

ccsd00002401, Teleportation of an atomic ensemble quantum state  

E-print Network

ccsd­00002401, version 1 ­ 30 Jul 2004 Teleportation of an atomic ensemble quantum state A. Dantan a protocol to achieve high #12;delity quantum state teleportation of a macroscopic atomic ensemble using for a practical implementation [2]. Several continuous variable teleportation experiments with op- tical #12;elds

172

Engineering steady-state entanglement for two atoms held in separate cavities through laser cooling  

NASA Astrophysics Data System (ADS)

We propose a scheme to prepare the steady-state entanglement for two atoms, which are held in separate cavities that are coupled through a short optical fiber or optical resonator. The entangled steady-state with a high fidelity can be achieved even with a low cooperativity parameter, by making use of the driving laser fields. Such a cooling mechanism is based on a resonant laser pump of the unwanted ground states to the excited states, which finally decay to the desired steady-state.

Shen, Li-Tuo; Chen, Rong-Xin; Wu, Huai-Zhi; Yang, Zhen-Biao

2014-04-01

173

Quantum states of hydrogen atom motion on the Pd(111) surface and in the subsurface  

NASA Astrophysics Data System (ADS)

We investigate the quantum states of hydrogen atom motion on Pd(111) surface and in its subsurface by calculating the wavefunctions and the eigenenergies for hydrogen atom motion within the framework of the variation method on an adiabatic potential energy surface (PES), obtained through first-principles calculations, for the hydrogen atom motion. The calculated results show that the ground-state wavefunction for the hydrogen atom motion localizes on the face-centered cubic (fcc) hollow site of the surface. The higher excited state wavefunctions are distributed between the first and second layers, and subsequently delocalized under the second atom layer. These suggest that an effective diffusion path of the hydrogen atom into the subsurface area passes through the fcc hollow site to the octahedral sites in the subsurface. Moreover, activation energies for diffusion of H and D atoms over the saddle point of the PES between the fcc hollow site and the first (second) octahedral site are estimated as 598 (882) meV and 646 (939) meV, respectively. Furthermore, the activation energies for diffusion of H and D atoms over the saddle point of the PES between the first (second) octahedral site and the fcc hollow site are estimated as 285 (483) meV and 323 (532) meV, respectively.

Ozawa, Nobuki; Arboleda, Nelson B., Jr.; Roman, Tanglaw A.; Nakanishi, Hiroshi; Diño, Wilson A.; Kasai, Hideaki

2007-09-01

174

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

175

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

176

Ground State Magnetic Moments of Mirror Nuclei Studied at NSCL  

E-print Network

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

P. F. Mantica; K. Minamisono

2009-01-22

177

Ground State Magnetic Moments of Mirror Nuclei Studied at NSCL  

E-print Network

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

Mantica, P F

2009-01-01

178

Ground State Magnetic Moments of Mirror Nuclei Studied at NSCL  

Microsoft Academic Search

Progress in the measurement of the ground state magnetic moments of mirror nuclei at NSCL is presented. The systematic trend of the spin expectation value < s rangle and the linear behavior of gamma p versus gamma n, both extracted from the magnetic moments of mirror partners, are updated to include all available data.

P. F. Mantica; K. Minamisono

2009-01-01

179

Ground states of dispersion-managed nonlinear Schrödinger equation  

Microsoft Academic Search

An exact pulse for the parametrically forced nonlinear Schrödinger 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

Vadim Zharnitsky; Emmanuel Grenier; Sergei K. Turitsyn; Christopher K. R. T. Jones; Jan S. Hesthaven

2000-01-01

180

Predictive State Representations for Grounding Human-Robot Communication  

E-print Network

Predictive State Representations for Grounding Human-Robot Communication Eric. Meisner, Sanmay Das, Volkan Isler, Jeff Trinkle, Selma Sabanovi´c and Linnda R. Caporeal Abstract-- Allowing robots to communicate naturally with humans is a major goal for social robotics. Most approaches have focused

Das, Sanmay

181

Predictive State Representations for Grounding Human-Robot Communication  

E-print Network

their quality of life by letting them remain independent for longer. However, in order for robotsPredictive State Representations for Grounding Human-Robot Communication Eric Meisner1 , Sanmay Das-- Allowing robots to communicate naturally with humans is an important goal for social robotics. Most ap

Isler, Ibrahim Volkan

182

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

183

GROUND STATES AND DYNAMICS OF MULTICOMPONENT BOSEEINSTEIN CONDENSATES  

E-print Network

a multicomponent Bose­Einstein condensate (BEC) at zero or a very low temperature. In preparation for the numerics a continuous normalized gradient flow (CNGF) to compute ground states of multicomponent BEC, prove energy diminishing property in the lin- ear case. Then we use a time-splitting sine-spectral (TSSP) method

Bao, Weizhu

184

On the ground states of vector nonlinear Schrodinger equations.  

E-print Network

On the ground states of vector nonlinear Schr¨odinger equations. Thierry Colin (1) (2) and Michael of vector nonlinear Schr¨odinger equations, which arise in the infinite ion acoustic speed limit solutions ) constructed by Brezis and Lieb [1]. Sur les ´etats fondamentaux d'´equations de Schr¨odinger non

Colin, Thierry

185

Ground State Quantum Coherences: from Quantum Beats to Strong Control  

E-print Network

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

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

2014-01-14

186

Spin and magnetic moment of 31Al ground state  

Microsoft Academic Search

The g-factor of the ground state of 31Al (T1\\/2=640 ms) has been measured by the ?-NMR technique on a polarized secondary fragment beam at GANIL, Caen, France. The measured value of |g|=1.517(20) is compared with sd-shell model calculations, which allows the assignment of spin and parity I?=5\\/2+ to this state. The spectroscopy of neutron-rich Al isotopes on the border of the

D. Borremans; S. Teughels; N. A Smirnova; D. L Balabanski; N. Coulier; J.-M Daugas; G. Georgiev; M. Lewitowicz; I. Matea; Yu. E Penionzhkevich; W.-D Schmidt-Ott; Yu. Sobolev; M. Stanoiu; K. Vyvey; G. Neyens

2002-01-01

187

Reversible state transfer between superconducting qubits and atomic ensembles  

E-print Network

We examine the possibility of coherent, reversible information transfer between solid-state superconducting qubits and ensembles of ultra-cold atoms. Strong coupling between these systems is mediated by a microwave transmission line resonator that interacts near-resonantly with the atoms via their optically excited Rydberg states. The solid-state qubits can then be used to implement rapid quantum logic gates, while collective metastable states of the atoms can be employed for long-term storage and optical read-out of quantum information.

D. Petrosyan; G. Bensky; G. Kurizki; I. Mazets; J. Majer; J. Schmiedmayer

2009-02-05

188

Reversible state transfer between superconducting qubits and atomic ensembles  

E-print Network

We examine the possibility of coherent, reversible information transfer between solid-state superconducting qubits and ensembles of ultra-cold atoms. Strong coupling between these systems is mediated by a microwave transmission line resonator that interacts near-resonantly with the atoms via their optically excited Rydberg states. The solid-state qubits can then be used to implement rapid quantum logic gates, while collective metastable states of the atoms can be employed for long-term storage and optical read-out of quantum information.

Petrosyan, D; Kurizki, G; Mazets, I; Majer, J; Schmiedmayer, J

2009-01-01

189

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)] [Faculty of Science, Northern Territory University, Darwin NT 0909 (Australia)

1997-11-01

190

Speed of Markovian relaxation toward the ground state  

SciTech Connect

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

Vogl, Malte; Schaller, Gernot; Brandes, Tobias [Institut fuer Theoretische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)

2010-01-15

191

? decay of nuclei in the range 67?Z?91 from the ground state and isomeric state  

NASA Astrophysics Data System (ADS)

The Coulomb and proximity potential model for deformed nuclei (CPPMDN) is used to study the favored and unfavored ? decay of nuclei in the range 67 ? Z ? 91 from both the ground state (g.s.) and isomeric state (i.s.). The computed half-lives are in good agreement with experimental data. The standard deviation of half-life is found to be 0.44. Geiger-Nuttall (GN) plots for various parent isotopes are studied. It is found that all four types of transitions (g.s.?g.s., g.s.?i.s., i.s.?g.s., i.s.?i.s.) lie on a straight line. The isomeric state ? decay shows a behavior similar to that of the ground state and the nuclear structure of the isomeric states imitates that of the ground states. Some predictions are done for ? transition from both ground and isomeric states, which will be useful for future experiments.

Santhosh, K. P.; Joseph, Jayesh George; Sahadevan, Sabina

2010-12-01

192

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

NASA Astrophysics Data System (ADS)

A numerical linked-cluster algorithm was recently introduced to study quantum quenches in the thermodynamic limit starting from thermal initial states [M. Rigol, Phys. Rev. Lett. 112, 170601 (2014), 10.1103/PhysRevLett.112.170601]. Here, we tailor that algorithm to quenches starting from ground states. In particular, we study quenches from the ground state of the antiferromagnetic Ising model to the XXZ chain. Our results for spin correlations are shown to be in excellent agreement with recent analytical calculations based on the quench action method. We also show that they are different from the correlations in thermal equilibrium, which confirms the expectation that thermalization does not occur in general in integrable models even if they cannot be mapped to noninteracting ones.

Rigol, Marcos

2014-09-01

193

The Leading Behaviour of The Ground-State Energy of Heavy Ions According to Brown and Ravenhall  

E-print Network

In this article we prove the absence of relativistic effects in leading order for the ground-state energy according to Brown-Ravenhall operator. We obtain this asymptotic result for negative ions and for systems with the number of electrons proportional to the nuclear charge. In the case of neutral atoms the analogous result was obtained earlier by Cassanas and Siedentop [4].

Xiao Liu

2010-08-12

194

Dynamics of ground and excited state vibrational relaxation and energy transfer in transition metal carbonyls.  

PubMed

Nonlinear vibrational spectroscopy provides insights into the dynamics of vibrational energy transfer in and between molecules, a crucial phenomenon in condensed phase physics, chemistry, and biology. Here we use frequency-domain 2-dimensional infrared (2DIR) spectroscopy to investigate the vibrational relaxation (VR) and vibrational energy transfer (VET) rates in different solvents in both the electronic ground and excited states of Re(Cl)(CO)3(4,4'-diethylester-2,2'-bipyridine), a prototypical transition metal carbonyl complex. The strong C?O and ester C?O stretch infrared reporters, located on opposite sides of the molecule, were monitored in the 1600-2100 cm(-1) spectral region. VR in the lowest charge transfer triplet excited state ((3)CT) is found to be up to eight times faster than in the ground state. In the ground state, intramolecular anharmonic coupling may be solvent-assisted through solvent-induced frequency and charge fluctuations, and as such VR rates are solvent-dependent. In contrast, VR rates in the solvated (3)CT state are surprisingly solvent-insensitive, which suggests that predominantly intramolecular effects are responsible for the rapid vibrational deactivation. The increased VR rates in the excited state are discussed in terms of intramolecular electrostatic interactions helping overcome structural and thermodynamic barriers for this process in the vicinity of the central heavy atom, a feature which may be of significance to nonequilibrium photoinduced processes observed in transition metal complexes in general. PMID:25198700

Delor, Milan; Sazanovich, Igor V; Towrie, Michael; Spall, Steven J; Keane, Theo; Blake, Alexander J; Wilson, Claire; Meijer, Anthony J H M; Weinstein, Julia A

2014-10-01

195

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

196

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

NASA Astrophysics Data System (ADS)

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

Boblest, Sebastian; Schimeczek, Christoph; Wunner, Günter

2014-01-01

197

Boron aggregation in the ground states of boron-carbon fullerenes  

NASA Astrophysics Data System (ADS)

We present unexpected structural motifs for boron-carbon nanocages of the stoichiometries B12C48 and B12C50, based on first-principles calculations. These configurations are distinct from those proposed so far because the boron atoms are not isolated and distributed over the entire surface of the cages, but rather aggregate at one location to form a patch. Our putative ground state of B12C48 is 1.8 eV lower in energy than the previously proposed ground state and violates all the suggested empirical rules for constructing low-energy fullerenes. The B12C50 configuration is energetically even more favorable than B12C48, showing that structures derived from the C60 buckminsterfullerene are not necessarily magic sizes for heterofullerenes.

Mohr, Stephan; Pochet, Pascal; Amsler, Maximilian; Schaefer, Bastian; Sadeghi, Ali; Genovese, Luigi; Goedecker, Stefan

2014-01-01

198

Incommensurate helical spin ground states on the hollandite lattice  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

199

Generation of Macroscopic Singlet States in a Cold Atomic Ensemble  

NASA Astrophysics Data System (ADS)

We report the generation of a macroscopic singlet state in a cold atomic sample via quantum nondemolition measurement-induced spin squeezing. We observe 3 dB of spin squeezing and detect entanglement with 5? statistical significance using a generalized spin-squeezing inequality. The degree of squeezing implies at least 50% of the atoms have formed singlets.

Behbood, N.; Martin Ciurana, F.; Colangelo, G.; Napolitano, M.; Tóth, Géza; Sewell, R. J.; Mitchell, M. W.

2014-08-01

200

Generation of macroscopic singlet states in a cold atomic ensemble.  

PubMed

We report the generation of a macroscopic singlet state in a cold atomic sample via quantum nondemolition measurement-induced spin squeezing. We observe 3 dB of spin squeezing and detect entanglement with 5? statistical significance using a generalized spin-squeezing inequality. The degree of squeezing implies at least 50% of the atoms have formed singlets. PMID:25215981

Behbood, N; Martin Ciurana, F; Colangelo, G; Napolitano, M; Tóth, Géza; Sewell, R J; Mitchell, M W

2014-08-29

201

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

202

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

203

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

204

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

SciTech Connect

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{approx}400 bosons.

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

2004-11-01

205

Edge state modulation of bilayer Bi nanoribbons by atom adsorption.  

PubMed

We investigated the behavior of edge states in two-dimensional bilayered Bi nanoribbons by atom adsorption based on the density functional method. We found that for a clean Bi zigzag ribbon the penetration depth of well-localized edge states is a function of the momentum-space width of the edge-state dispersion. Depending on the density of adsorbed H, Br and I atoms, respectively, the edge state can be changed from localized within a very narrow region to delocalized over the whole region in real space. Changes in atomic and electronic structures and topological insulator properties associated with the atomic adsorption on the edges of zigzag bilayer nanoribbon (ZBNR) are discussed. Our work suggests that ZBNR could be a possible candidate for nanoelectronic devices under some special conditions. PMID:25012680

Chen, Li; Cui, Guangliang; Zhang, Pinhua; Wang, Xiaoli; Liu, Hongmei; Wang, Dongchao

2014-08-28

206

Ground state properties of an anisotropic bilinear-biquadratic model  

NASA Astrophysics Data System (ADS)

In this paper, we consider anisotropic properties of a one-dimensional bilinear-biquadratic spin model with S = 1. The Hamiltonian with anisotropic parameter is studied numerically by using Lanczos exact diagonalization method at a critical point. It is found that the momentum corresponding to the ground state is affected by anisotropic parameter regularly, especially when total spin z-component is not zero.

Wang, Jinlong

2014-08-01

207

Ground-state electronic structure of actinide monocarbides and mononitrides  

Microsoft Academic Search

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)

Leon Petit; Axel Svane; Zdzislawa Szotek; Walter M Temmerman; George Malcolm Stocks

2009-01-01

208

The 15N ground state studied with elastic electron scattering  

Microsoft Academic Search

The C0 elastic electron scattering form factor of 15N has been measured over a momentum transfer range q=0.4-3.2 fm-1. From these form factor data the ground state charge density and its RMS radius (2.612+\\/-0.009 fm) were determined. This charge density as well as its difference with that of 16O were compared to recent large-basis shell-model calculations. Although these calculations describe

J. W. de Vries; D. Doornhof; C. W. de Jager; R. P. Singhal; S. Salem; G. A. Peterson; R. S. Hicks

1988-01-01

209

On the Ground State of Two Flavor Color Superconductor  

E-print Network

The diquark condensate susceptibility in neutral color superconductor at moderate baryon density is calculated in the frame of two flavor Nambu-Jona-Lasinio model. When color chemical potential is introduced to keep charge neutrality, the diquark condensate susceptibility is negative in the directions without diquark condensate in color space, which may be regarded as a signal of the instability of the conventional ground state with only diquark condensate in the color 3 direction.

Lianyi He; Meng Jin; Pengfei Zhuang

2005-05-09

210

Ground state energy in a wormhole space-time  

Microsoft Academic Search

The ground state energy of the massive scalar field with nonconformal coupling xi on a short-throat flat-space wormhole background is calculated by using the zeta renormalization approach. We discuss the renormalization and relevant heat kernel coefficients in detail. We show that a stable configuration of wormholes can exist for xi>0.123. In the particular case of a massive conformal scalar field

Nail R. Khusnutdinov; Sergey V. Sushkov

2002-01-01

211

Relativistic ground state of a hydrogenlike molecular ion  

NASA Astrophysics Data System (ADS)

In this preliminary Brief Report we explore a method for examining relativistic effects in one-electron molecules that avoids the evaluation of multicenter integrals. Here the Dirac equation for a simplified version of the H2+ ion is solved exactly for the ground-state Schrödinger and Dirac energy levels. The model consists of representing the electron-proton Coulomb interaction as a projection operator onto a linear subspace of Hilbert space.

Glasser, M. L.

2014-05-01

212

Complete population transfer in degenerate n-state atoms  

E-print Network

We find a set of conditions to achieve complete population transfer, via coherent population trapping, from an initial state to a designated final state at a designated time in a degenerate n-state atom, where the transitions are caused by an external interaction.

J. H. McGuire; Kh. Kh. Shakov; Kh. Yu. Rakhimov

2003-06-03

213

Resonance States of Atomic Anions ALEXEI V. SERGEEV, SABRE KAIS  

E-print Network

Resonance States of Atomic Anions ALEXEI V. SERGEEV, SABRE KAIS Department of Chemistry, Purdue with decrease of its nuclear charge. By analytic continuation from bound to resonance states, we obtain complex Quantum Chem 82: 255­261, 2001 Key words: resonance states; negative ions; complex rotation method

Kais, Sabre

214

Alternative ground states enable pathway switching in biological electron transfer  

PubMed Central

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

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

2012-01-01

215

Just one more approach to calculating the QCD ground state  

E-print Network

The quark behaviour in the background of intensive stochastic gluon field is studied. An approximate procedure for calculating the effective Hamiltonian is developed and the corresponding ground state within the Hartree-Fock-Bogolyubov approach is found. The comparative analysis of various model Hamiltonian is given and transition to the chiral limit in the Keldysh model is discused in detail. We study response to the process of filling up the Fermi sphere with quarks, calculate the vacuum pressure and demonstrate the existence of filled-in state degenerate with the vacuum one.

S. V. Molodtsov; G. M. Zinovjev

2009-08-12

216

Optimal preparation of quantum states on an atom chip device  

E-print Network

Atom chips provide compact and robust platforms towards practical quantum technologies. A quick and faithful preparation of arbitrary input states for these systems is crucial but represents a very challenging experimental task. This is especially difficult when the dynamical evolution is noisy and unavoidable setup imperfections have to be considered. Here, we experimentally prepare with very high small errors different internal states of a Rubidium Bose-Einstein condensate realized on an atom chip. As a possible application of our scheme, we apply it to improve the sensitivity of an atomic interferometer.

Lovecchio, Cosimo; Cherukattil, Shahid; Murtaza, Ali Khan; Herrera, Ivan; Cataliotti, Francesco Saverio; Calarco, Tommaso; Montangero, Simone; Caruso, Filippo

2014-01-01

217

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

218

Ground State Magnetic Properties of Fe Nanoislands on Cu(111)  

NASA Astrophysics Data System (ADS)

We investigate magnetic properties of Fe nanoislands on Cu(111) in the relaxed structure within the density functional theory. We observe that the nanoislands exhibit the ferromagnetic properties with large magnetic moment. We find that the change in the magnetic moment of each Fe atom is induced by deposition on Cu(111) and structure relaxation of Fe nanoislands. Moreover, we examine the stability of ferromagnetic states of Fe nanoislands by performing the total energy calculations.

Kishi, Tomoya; David, Melanie; Diño, Wilson Agerico; Nakanishi, Hiroshi; Kasai, Hideaki; Komori, Fumio

2005-11-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

220

Steady state of atoms in a resonant field with elliptical polarization  

NASA Astrophysics Data System (ADS)

We present a complete set of analytical and invariant expressions for the steady-state density matrix of atoms in a resonant radiation field with arbitrary intensity and polarization. The field drives the closed dipole transition with arbitrary values of the angular momenta Jg and Je of the ground and excited state. The steady-state density matrix is expressed in terms of spherical harmonics of a complex direction given by the field polarization vector. The generalization to the case of broadband radiation is given. We indicate various applications of these results.

Taichenachev, A. V.; Tumaikin, A. M.; Yudin, V. I.; Nienhuis, G.

2004-03-01

221

Creation and manipulation of bound states in continuum with lasers: Applications to cold atoms and molecules  

E-print Network

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

Deb, Bimalendu

2014-01-01

222

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

223

Atomic oxygen effects on boron nitride and silicon nitride: A comparison of ground based and space flight data  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

224

A comparison of ground-based and space flight data: Atomic oxygen reactions with boron nitride and silicon nitride  

NASA Technical Reports Server (NTRS)

The effects of atomic oxygen on boron nitride (BN) and silicon nitride (Si3N4) have been studied in low Earth orbit (LEO) flight experiments and in a ground-based simulation facility at Los Alamos National Laboratory. Both the in-flight and ground-based experiments employed the materials coated over thin (approx 250 Angstrom) silver films whose electrical resistance was measured in situ to detect penetration of atomic oxygen through the BN and Si3N4 materials. In the presence of atomic oxygen, silver oxidizes to form silver oxide, which has a much higher electrical resistance than pure silver. Permeation of atomic oxygen through BN, as indicated by an increase in the electrical resistance of the silver underneath, was observed in both the in-flight and ground-based experiments. In contrast, no permeation of atomic oxygen through Si3N4 was observed in either the in-flight or ground-based experiments. The ground-based results show good qualitative correlation with the LEO flight results, thus validating the simulation fidelity of the ground-based facility in terms of reproducing LEO flight results.

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

1990-01-01

225

Anomalous Ground State of the Electrons in Nanoconfined Water  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

226

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

227

Near-UV Photodissociation Dynamics of Thiomethoxy Radical via Ã2A1 State: H-atom Product Channel  

NASA Astrophysics Data System (ADS)

Photodissociation dynamics of jet-cooled thiomethoxy radical (CH3S) via the Ã2A1 <-- tilde X2E transition is investigated near 352 nm. The H-atom product channel is observed directly for the first time by H-atom product yield spectrum and photofragment translational spectroscopy. The 2132 vibrational level of the Ã2A1 state dissociates to the H+H2CS products. The H+H2CS product translational energy release is modest and peaks around 33 kJ/mol; the H-atom angular distribution is isotropic. The dissociation mechanism is consistent with internal conversion of the excited Ã2A1 state to the tilde X2E ground state and subsequent unimolecular dissociation on the ground state to the H+H2CS products.

Zheng, Xian-feng; Song, Yu; Wu, Jing-ze; Zhang, Jing-song

2007-08-01

228

Equatorial ground ice on Mars: Steady-state stability  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

229

Effects of Rashba and Dresselhaus spin-orbit interactions on the ground state of two-dimensional localized spins.  

PubMed

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

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

2014-05-14

230

Long-Range Adiabatic Corrections to the Ground Molecular State of Alkali-Metal Dimers.  

NASA Astrophysics Data System (ADS)

The structure of the long-range limit of the diagonal adiabatic corrections to the ground molecular state of diatomic molecules, may be expressed as a series of inverse powers of internuclear distance, R. The coefficients of this expansion are proportional to the inverse of the nuclear mass. Thus, they may be interpreted as a nuclear mass-dependent corrections to the dispersion coefficients. Using perturbation theory we have calculated the long-range coefficients of the diagonal adiabatic corrections up to the order of R-10. The final expressions are in terms of integrals over imaginary frequencies of products of atomic matrix elements involving Green's functions of complex energy. Thus, in our approach the molecular problem is reduced to an atomic one. Numerical evaluations have been done for all alkali-metal dimers. We acknowledge the support of the U.S. Dept. of Energy.

Marinescu, M.; Dalgarno, A.

1997-04-01

231

Observing the Ground-State Properties of an Interacting Homogeneous Bose Gas  

E-print Network

We study the ground-state properties of a homogeneous atomic Bose gas, produced in an optical box trap, using high-resolution Bragg spectroscopy. For a range of box sizes, up to $70\\,\\mu$m, we directly observe Heisenberg-limited momentum uncertainty of Bose-condensed atoms. We measure the condensate interaction energy with a precision of $k_B \\times 100$ pK and study, both experimentally and numerically, the dynamics of free expansion of the interacting condensate released from the box potential. All our measurements are in good agreement with theoretical expectations for a perfectly homogeneous gas, which also establishes the uniformity of our optical-box system on a sub-nK energy scale.

Gotlibovych, Igor; Gaunt, Alexander L; Navon, Nir; Smith, Robert P; Hadzibabic, Zoran

2014-01-01

232

Antiferromagnetic triangular Ising model: Critical behavior of the ground state  

NASA Astrophysics Data System (ADS)

The critical ground state of the antiferromagnetic triangular Ising model is studied with finite-size scaling, with the use of exact techniques and numerical transfer-matrix methods. Exact solution of the model in zero field yields a conformal anomaly equal to 1, and values of critical exponents. For nonzero fields, dominant eigenvalues of the transfer matrix are computed for systems with linear dimensions up to 27 with the use of an efficient coding of spin states as a system of nonintersecting strings. The results are in perfect agreement with the Gaussian-model-Coulomb-gas scenario proposed by Nienhuis et al. for this model. Quantitative agreement is found with the predictions for exponents of spin-wave and vortex operators. Furthermore, we locate the field-induced Kosterlitz-Thouless transition to a long-range-ordered state at a field Hc=0.266+/-0.010.

Blöte, Henk W. J.; Nightingale, M. Peter

1993-06-01

233

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

234

Boron: do we know the ground state structure?  

NASA Astrophysics Data System (ADS)

Boron is only the fifth element in the periodic table, having a simple electronic configuration, yet, it is known to form one of the most complicated crystal structures, ?-rhombohedral structure. Up to date, the best estimate on the number of atoms in its hexagonal unit cell is 320.1, not even an integer number. The key concept to understand its complexity is covalency and electron deficiency: It does not have enough valence electrons to form a simple covalent crystal, like carbon or silicon. Instead it forms a complicated packing of icosahedrons. The structural model of ?-boron was developed in the 1960s based on X-ray experiment. Although this model structure captures the most of the structural characteristics of ?-boron, it has a crucial pitfall; the number of atoms per cell estimated by X-ray experiment does not agree with the number of atoms estimated by the pycnometric density. In 1988, Slack et al. discovered four more POS, by which the discrepancy in the number of atoms is reconciled [J. of Solid State Chem. 76, 52 (1988)]. There still remains an unanswered question; how are these POS atoms configured? Is it completely random? Or there is some kind of order as it has been suggested in Slack’s paper? A major challenge here is the astronomical number of possible configurations, roughly 150 million even for the irreducible cell. We tackle this problem using ab-initio simulated annealing coupled with a Lattice Model Monte Carlo simulated annealing. Our results reveal that the stable structure, indeed, has a certain type of correlation in its POS configuration. More detail on the structural property and its impact on electronic property of ?-boron will be discussed at the presentation. This work was performed under the auspices of the U.S. Dept. of Energy at the University of California/ LLNL under contract no. W-7405-Eng-48.

Ogitsu, Tadashi

2006-03-01

235

Preparation of Entangled States and Quantum Teleportation with Atomic Qubits  

E-print Network

Preparation of Entangled States and Quantum Teleportation with Atomic Qubits Dissertation zur with such precision that it was possible to realize a deterministic quantum state teleportation between ions teleportation protocol. This was the first demonstration of a completely deterministic teleportation protocol

Blatt, Rainer

236

On the hydrino state of the relativistic hydrogen atom  

E-print Network

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

Jan Naudts

2005-07-27

237

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

SciTech Connect

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

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

2010-11-15

238

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

239

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

E-print Network

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

Masao Hirokawa; Fumio Hiroshima

2012-07-17

240

Ground State and Excitation Properties of Soft-Core Bosons  

NASA Astrophysics Data System (ADS)

We study the physics of soft-core bosons at zero temperature in two dimensions for a class of potentials that could be realised in experiments with Rydberg dressed Bose-Einstein condensates. We analyze the ground state properties of the system in detail and provide a complete description of the excitation spectra in both superfluid, supersolid and crystalline phase for a wide range of interaction strengths and densities. In addition we describe a method to extract the transverse gapless excitation modes in the phases with broken translational symmetry within the framework of path integral Monte Carlo methods.

Macrì, Tommaso; Saccani, Sebastiano; Cinti, Fabio

2014-10-01

241

Inequalities between ground-state energies of Heisenberg models  

E-print Network

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

Jacek Wojtkiewicz; Rafa? Skolasi?ski

2014-10-20

242

Quantum disordered ground state for the frustrated square lattice  

NASA Astrophysics Data System (ADS)

We present Quantum Monte-Carlo simulations of an exchange-anisotropic spin-1/2 Heisenberg model on a square lattice with nearest and next-nearest neighbor interactions. The ground state phase diagram shows two classical magnetically ordered phases for dominating antiferromagnetic Sz-interactions and for large quantum fluctuations a ferromagnetic order in the x-y plane. In between a finite region is detected where neither classical nor quantum mechanical order, e.g. long-ranged dimer correlations, are found.

Kalz, A.; Honecker, A.; Fuchs, S.; Pruschke, T.

2012-12-01

243

Lee-Yang Polynomials and Ground States of Spin Systems  

NASA Astrophysics Data System (ADS)

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

Slawny, Joseph

2014-08-01

244

The ground state in a spin-one color superconductor  

E-print Network

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 $^3$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.

Andreas Schmitt

2004-12-09

245

Quantum telecloning of an optical coherent state to atomic ensembles  

NASA Astrophysics Data System (ADS)

A scheme for symmetrically telecloning a coherent light state onto two atomic ensembles is proposed. Using the generated multipartite entanglement as the quantum channel, we achieve a fidelity for each clone of F = 0.58 in the case of single feedback, while it is 0.63 for the double feedback case. Furthermore, we also explored the implementation of our scheme with a different quantum channel and find that the optimal fidelity 2/3 can be reached. Atom-atom quantum telecloning is finally studied, showing that only small coupling constants are required for the achievement of high fidelities.

Wang, Ming-Feng; Wang, Yan-Wei; Ni, Mang-Mang; Zheng, Yi-Zhuang

2008-11-01

246

Full-dimensional quantum calculations of ground-state tunneling splitting of malonaldehyde using an accurate ab initio potential energy surface  

Microsoft Academic Search

Quantum calculations of the ground vibrational state tunneling splitting of H-atom and D-atom transfer in malonaldehyde are performed on a full-dimensional ab initio potential energy surface (PES). The PES is a fit to 11 147 near basis-set-limit frozen-core CCSD(T) electronic energies. This surface properly describes the invariance of the potential with respect to all permutations of identical atoms. The saddle-point

Yimin Wang; Bastiaan J. Braams; Joel M. Bowman; Stuart Carter; David P. Tew

2008-01-01

247

Determination of Ground-Laboratory to In-Space Effective Atomic Oxygen Fluence for DC 93?500 Silicone  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

248

Understanding many-electron fermionic ground states as bosonic excited states  

NASA Astrophysics Data System (ADS)

We consider the novel question of, ``Which state in the spectrum of a system of distinguishable particles is the ground state of the same system made up of indistinguishable fermions?'' We discuss how this can be approximated for many-electron systems and illustrate its importance in our new semiclassical method correlated Thomas-Fermi (CTF).

Landry, Brian; Wasserman, Adam; Heller, Eric

2010-03-01

249

Eigenvectors in the Superintegrable Model II: Ground State Sector  

E-print Network

In 1993, Baxter gave $2^{m_Q}$ eigenvalues of the transfer matrix of the $N$-state superintegrable chiral Potts model with spin-translation quantum number $Q$, where $m_Q=\\lfloor(NL-L-Q)/N\\rfloor$. In our previous paper we studied the Q=0 ground state sector, when the size $L$ of the transfer matrix is chosen to be a multiple of $N$. It was shown that the corresponding $\\tau_2$ matrix has a degenerate eigenspace generated by the generators of $r=m_0$ simple $sl_2$ algebras. These results enable us to express the transfer matrix in the subspace in terms of these generators $E_m^{\\pm}$ and $H_m$ for $m=1,...,r$. Moreover, the corresponding $2^r$ eigenvectors of the transfer matrix are expressed in terms of rotated eigenvectors of $H_m$.

Helen Au-Yang; Jacques H. H. Perk

2008-03-20

250

The ground state rotational spectrum of SO 2F 2  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

251

Atomic cluster state build-up with macroscopic heralding  

NASA Astrophysics Data System (ADS)

We describe a measurement-based state preparation scheme for the efficient build-up of cluster states in atom-cavity systems. As in a recent proposal for the generation of maximally entangled atom pairs [Metz , Phys. Rev. Lett. 97, 040503 (2006)], we use an electron shelving technique to avoid the necessity for the detection of single photons. Instead, the successful fusion of smaller into larger clusters is heralded by an easy-to-detect macroscopic fluorescence signal. High fidelities are achieved even in the vicinity of the bad cavity limit and are essentially independent of the concrete size of the system parameters.

Metz, Jeremy; Schön, Christian; Beige, Almut

2007-11-01

252

States of antimony and tin atoms in lead chalcogenides  

SciTech Connect

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

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

2011-04-15

253

Magnetic ground states of RMn 4Al 8, R=La, Pr, Y  

NASA Astrophysics Data System (ADS)

Yamasaki et al. (Solid State Commun. 119 (2001) 415) have suggested that LaMn 4Al 8 is a nearly antiferromagnetic metal with linear chains of Mn atoms. We present evidence from ZF-?SR measurements that both LaMn 4Al 8 and the related compound PrMn 4Al 8 display antiferromagnetic order at low temperatures. In LaMn 4Al 8 the ?SR relaxation rate rises to a peak at 4.5 K; below this temperature the asymmetry decreases smoothly. In PrMn 4Al 8 well-defined oscillations appear below 35 K. Neutron crystal field spectroscopy suggests a singlet ground state for the Pr 3+ ion, so it is likely that the internal field seen by the muons arises from ordered Mn moments. YMn 4Al 8 shows no sign of magnetic correlations down to 1.2 K.

Rainford, B. D.; Leavey, C. J.; Hillier, A. D.; Stewart, J. R.

2005-04-01

254

Testing quantum electrodynamics in the lowest singlet states of beryllium atom  

E-print Network

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

Puchalski, Mariusz; Komasa, Jacek

2013-01-01

255

REFRACTIVE INDEX ENHANCEMENT AND ATOMIC STATE LOCALIZATION IN RUBIDIUM  

E-print Network

REFRACTIVE INDEX ENHANCEMENT AND ATOMIC STATE LOCALIZATION IN RUBIDIUM BY NICHOLAS A. PROITE teacher and scientist to work with throughout my graduate career and his research skill is remarkable both in and out of the lab. His amazing ability to break down even the most difficult problems into simple

Yavuz, Deniz

256

Single-atom gating of quantum-state superpositions  

E-print Network

LETTERS Single-atom gating of quantum-state superpositions CHRISTOPHER R. MOON1 , CHRISTOPHER P intersections along the perimeter (these map to the radial and angular momentum quantum numbers in a circle). By judiciously choosing an ellipse's deformation and size, two target wavefunctions can be made degenerate at any

Loss, Daniel

257

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

258

Geometrical phase of thermal state in hydrogen atom  

E-print Network

In this paper, the geometric phase of thermal state in hydrogen atom under the effects of external magnetic field is considered. Especially the effects of the temperature upon the geometric phase is discussed. Also we discuss the time evolution of entanglement of the system. They show some similar behaviors.

Guo-Qiang Zhu

2006-05-08

259

Modularity, Atomicity and States in Archimedean Lattice Effect Algebras  

Microsoft Academic Search

Effect algebras are a generalization of many structures which arise in quantum physics and in mathematical economics. We show that, in every modular Archimedean atomic lattice effect algebra $E$ that is not an orthomodular lattice there exists an $(o)$-continuous state $\\\\omega$ on $E$, which is subadditive. Moreover, we show properties of finite and compact elements of such lattice effect algebras.

Jan Paseka

2010-01-01

260

Quantum corrections to the ground state energy of trapped Bose-Einstein condensates: A diffusion Monte Carlo calculation  

Microsoft Academic Search

The diffusion Monte Carlo method is applied to describe a Bose-Einstein condensate at zero temperature in a spherical trap, fully quantum mechanically and nonperturbatively. Our calculations confirm that the exact ground state energy for a sum of two-body interactions depends to a good approximation on only one atomic physics parameter, the s-wave scattering length a, and no other details of

Doerte Blume; Chris H. Greene

2001-01-01

261

Ground state magnetic dipole moment of 35K  

E-print Network

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

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

2006-02-02

262

Absence of Quantum Time Crystals in Ground States  

E-print Network

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

Watanabe, Haruki

2014-01-01

263

Masses of ground and excited-state hadrons  

E-print Network

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

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

2011-01-21

264

Nondegeneracy of the ground state for nonrelativistic Lee model  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

265

A new phenomenological formula for ground state binding energies  

E-print Network

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

G. Gangopadhyay

2010-07-09

266

Ground-Laboratory to In-Space Atomic Oxygen Correlation for the Polymer Erosion and Contamination Experiment (PEACE) Polymers  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

267

Thermodynamic ground state of MgB6 predicted from first principles structure search methods  

NASA Astrophysics Data System (ADS)

Crystalline structures of magnesium hexaboride, MgB6, were investigated using unbiased structure searching methods combined with first principles density functional calculations. An orthorhombic Cmcm structure was predicted as the thermodynamic ground state of MgB6. The energy of the Cmcm structure is significantly lower than the theoretical MgB6 models previously considered based on a primitive cubic arrangement of boron octahedra. The Cmcm structure is stable against the decomposition to elemental magnesium and boron solids at atmospheric pressure and high pressures up to 18.3 GPa. A unique feature of the predicted Cmcm structure is that the boron atoms are clustered into two forms: localized B6 octahedra and extended B? ribbons. Within the boron ribbons, the electrons are delocalized and this leads to a metallic ground state with vanished electric dipoles. The present prediction is in contrast to the previous proposal that the crystalline MgB6 maintains a semiconducting state with permanent dipole moments. MgB6 is estimated to have much weaker electron-phonon coupling compared with that of MgB2, and therefore it is not expected to be able to sustain superconductivity at high temperatures.

Wang, Hui; LeBlanc, K. A.; Gao, Bo; Yao, Yansun

2014-01-01

268

Broadband optical cooling of molecular rotors from room temperature to the ground state.  

PubMed

Laser cycling of resonances can remove entropy from a system via spontaneously emitted photons, with electronic resonances providing the fastest cooling timescales because of their rapid spontaneous relaxation. Although atoms are routinely laser-cooled, even simple molecules pose two interrelated challenges for cooling: every populated rotational-vibrational state requires a different laser frequency, and electronic relaxation generally excites vibrations. Here we cool trapped AlH(+) molecules to their ground rotational-vibrational quantum state using an electronically exciting broadband laser to simultaneously drive cooling resonances from many different rotational levels. Undesired vibrational excitation is avoided because of vibrational-electronic decoupling in AlH(+). We demonstrate rotational cooling on the 140(20) ms timescale from room temperature to 3.8(-0.3)(+0.9) K, with the ground-state population increasing from ~3 to 95.4(-2.1)(+1.3)%. This cooling technique could be applied to several other neutral and charged molecular species useful for quantum information processing, ultracold chemistry applications and precision tests of fundamental symmetries. PMID:25179449

Lien, Chien-Yu; Seck, Christopher M; Lin, Yen-Wei; Nguyen, Jason H V; Tabor, David A; Odom, Brian C

2014-01-01

269

Theoretical study of the ground-state structures and properties of niobium hydrides under pressure  

NASA Astrophysics Data System (ADS)

As part of a search for enhanced superconductivity, we explore theoretically the ground-state structures and properties of some hydrides of niobium over a range of pressures and particularly those with significant hydrogen content. A primary motivation originates with the observation that under normal conditions niobium is the element with the highest superconducting transition temperature (Tc), and moreover some of its compounds are metals again with very high Tc's. Accordingly, combinations of niobium with hydrogen, with its high dynamic energy scale, are also of considerable interest. This is reinforced further by the suggestion that close to its insulator-metal transition, hydrogen may be induced to enter the metallic state somewhat prematurely by the addition of a relatively small concentration of a suitable transition metal. Here, the methods used correctly reproduce some ground-state structures of niobium hydrides at even higher concentrations of niobium. Interestingly, the particular stoichiometries represented by NbH4 and NbH6 are stabilized at fairly low pressures when proton zero-point energies are included. While no paired H2 units are found in any of the hydrides we have studied up to 400 GPa, we do find complex and interesting networks of hydrogens around the niobiums in high-pressure NbH6. The Nb-Nb separations in NbHn are consistently larger than those found in Nb metal at the respective pressures. The structures found in the ground states of the high hydrides, many of them metallic, suggest that the coordination number of hydrogens around each niobium atom grows approximately as 4n in NbHn (n = 1-4), and is as high as 20 in NbH6. NbH4 is found to be a plausible candidate to become a superconductor at high pressure, with an estimated Tc ˜ 38 K at 300 GPa.

Gao, Guoying; Hoffmann, Roald; Ashcroft, N. W.; Liu, Hanyu; Bergara, Aitor; Ma, Yanming

2013-11-01

270

From rotating atomic rings to quantum Hall states  

PubMed Central

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

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

2011-01-01

271

Variational Monte Carlo calculations of ground states of liquid /sup 4/He and /sup 3/He drops  

SciTech Connect

Variational Monte Carlo calculations of the ground states of drops containing 8--728 atoms of /sup 4/He and 20--240 atoms of /sup 3/He have been made. The variational wave functions include two- and three-body correlations and (for the Fermi drops) Feynman-Cohen backflow. We discuss the wave functions, their relation to modern variational wave functions for liquid /sup 4/He and /sup 3/He, the calculational techniques, and the results for the ground-state energies and density profiles. Our calculations indicate that /sup 3/He drops with more than 40 atoms are bound, while a drop with 20 atoms is in a metastable state that has positive energy but negative chemical potential. The surface tensions of both liquid /sup 4/He and /sup 3/He are obtained by liquid-drop fits to the calculated binding energies. From the density profiles of the largest drops we estimate the surface thickness of liquid /sup 4/He to be 7 A while that for liquid /sup 3/He is 8 A.

Pandharipande, V.R.; Pieper, S.C.; Wiringa, R.B.

1986-10-01

272

Ground and first excited torsional states of acetamide  

NASA Astrophysics Data System (ADS)

We present a first global study involving rotational levels in the lowest three torsional states of acetamide (CH 3CONH 2). New measurements of this spectrum, consisting of approximately 1600 lines and involving torsion-rotation transitions with J up to 20 and Ka up to 11, have been carried out between 49 and 149 GHz using the millimeter-wave spectrometer in Kharkov. After removing the observed quadrupole hyperfine splittings, the new data were combined with previously published measurements and fitted using a rho-axis-method (RAM) torsion-rotation Hamiltonian in conjunction with a new computer-automated vt and K labeling algorithm. The final fit used 48 parameters to give an overall weighted standard deviation of 0.72 for 759, 587, and 265 lines belonging, respectively, to the ground, first, and second excited torsional states and 95 lines corresponding to ? vt=1 transitions falling in the millimeter wave range. Separate root-mean-square (rms) deviations for the A (25 kHz) and E (27 kHz) species, as well as for the vt=0 state (26 kHz), vt=1 (25 kHz), vt=2 (22 kHz), and ? vt=1 transitions (35 kHz) indicate a similar quality of the fit for the two symmetry species and for the three torsional states. The RAM Hamiltonian was found to have rather good predictive ability when fits of only vt=0 (or only vt=0 and 1) transitions were used to calculate vt=1 (or vt=2) lines. In addition, the combination of this Hamiltonian and the computer-automated vt and K labeling algorithm seems to provide a rather powerful tool for the precise assignment and fitting of torsion-rotation transitions in C3 v internal-rotor molecules with low torsional potential barriers.

Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.; Kleiner, I.; Hougen, J. T.

2004-10-01

273

Antiferromagnetic ground state in NpCoGe  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

274

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

NASA Astrophysics Data System (ADS)

We have made an investigation on the ground states and the 2s21Se resonance states of H- in dense quantum plasmas. Exponential-cosine-screened Coulomb potentials (ECSCP) are used to represent the effective potential for a test charge in dense quantum plasmas. Ground-state energies and wavefunctions are determined within the framework of Ritz's variational principle by employing highly correlated wavefunctions to take into account the correlation effect of the charged particles. Ground-state energies are shown to converge with the increase of terms in the wavefunctions. We also report various expectation values of the coordinates of electrons in H-. Resonance energies and widths for the doubly excited H- for various values of the screening parameter are determined using the stabilization method by calculating the density of the resonance states. Results for resonance energies and widths are reported for the screening parameter in the range 0.0-0.15. Such a calculation for H- is reported for the first time in the literature.

Ghoshal, Arijit; Ho, Y. K.

2009-09-01

275

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

276

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

277

Scaling behavior of the ground-state antihydrogen yield as a function of positron density and temperature from classical-trajectory Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

278

Ground-State Pressure of Quasi-2D Fermi and Bose Gases  

NASA Astrophysics Data System (ADS)

Using an ultracold gas of atoms, we have realized a quasi-two-dimensional Fermi system with widely tunable s-wave interactions nearly in a ground state. Pressure and density are measured. The experiment covers physically different regimes: weakly and strongly attractive Fermi gases and a Bose gas of tightly bound pairs of fermions. In the Fermi regime of weak interactions, the pressure is systematically above a Fermi-liquid-theory prediction, maybe due to mesoscopic effects. In the opposite Bose regime, the pressure agrees with a bosonic mean-field scaling in a range beyond simplest expectations. In the strongly interacting regime, measurements disagree with a purely 2D model. Reported data may serve for sensitive testing of theoretical methods applicable across different quantum physics disciplines.

Makhalov, Vasiliy; Martiyanov, Kirill; Turlapov, Andrey

2014-01-01

279

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

280

Steady-state superradiance with alkaline earth atoms  

E-print Network

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

D. Meiser; M. J. Holland

2009-12-03

281

Majorana edge States in atomic wires coupled by pair hopping.  

PubMed

We present evidence for Majorana edge states in a number conserving theory describing a system of spinless fermions on two wires that are coupled by pair hopping. Our analysis is based on a combination of a qualitative low energy approach and numerical techniques using the density matrix renormalization group. In addition, we discuss an experimental realization of pair-hopping interactions in cold atom gases confined in optical lattices. PMID:24206486

Kraus, Christina V; Dalmonte, Marcello; Baranov, Mikhail A; Läuchli, Andreas M; Zoller, P

2013-10-25

282

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

283

Ground state of the geometrically frustrated compound Tb2Sn2O7  

Microsoft Academic Search

Despite the observation of magnetic neutron reflections at low temperatures, muon-spin experiments have suggested the ground state of the geometrically frustrated magnetic material Tb2Sn2O7 to be dynamical. This unique situation requires additional characterizations of this magnetic ground state. Here we report a neutron spin-echo investigation which supports the existence of a dynamical component in the ground state. This result is

Y. Chapuis; A. Yaouanc; P. Dalmas de Réotier; S. Pouget; P. Fouquet; A. Cervellino; A. Forget

2007-01-01

284

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

285

Ground-state properties of neutron-rich Mg isotopes  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

286

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

287

Table of experimental nuclear ground state charge radii: An update  

SciTech Connect

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

Angeli, I. [Institute of Experimental Physics, University of Debrecen, H-4010 Debrecen Pf. 105 (Hungary)] [Institute of Experimental Physics, University of Debrecen, H-4010 Debrecen Pf. 105 (Hungary); Marinova, K.P., E-mail: marinova@nrmail.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation)

2013-01-15

288

Magnetic Charge of the Stark States of Hydrogen Atoms  

E-print Network

It is conjectured that Stark states of excited hydrogen atom posses magnetic charge for which the quantum mechanical operator is $${\\cal G}_{op} = {e\\over \\hbar} (\\vec\\sigma\\cdot\\vec A)$$ where $\\vec A$ is the Runge-Lenz vector. The expectation value $g$ of this operator for Stark states is found to be $$ g = e(n_1-n_2)$$ which obeys a Dirac-Saha type quantization formula $${eg\\over c} = (n_1-n_2)\\alpha$$ where $\\alpha$ is the fine structure constant and $n_1$ and $n_2$ are parabolic quantum numbers. An experimental arrangement is outlined to test this conjecture.

T. Pradhan

2008-09-28

289

Ground Water Quality Protection. State and Local Strategies.  

ERIC Educational Resources Information Center

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

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

290

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

PubMed

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((3)P(0,1,2)) 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 Å in equilibrium bond distance (R(e)) and 200 cm(-1) in dissociation energy (D(e)). 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((2)P) excited states are quite close to experimental atomic TDMs as compared to the Yb((3)P) and Yb((1)P) excited states. The information obtained from this work would be useful for ultracold photoassociation experiments on LiYb. PMID:20886942

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

2010-09-28

291

Ordinary atom-mirror atom bound states: A new window on the mirror world  

E-print Network

Mirror symmetry is a plausible candidate for a fundamental symmetry of particle interactions which can be exactly conserved if a set of mirror particles exist. The properties of the mirror particles seem to provide an excellent candidate to explain the inferred dark matter of the Universe and might also be responsible for a variety of other puzzles in particle physics, astrophysics, meteoritics and planetary science. One such puzzle -- the orthopositronium lifetime problem -- can be explained if there is a small kinetic mixing of ordinary and mirror photons. We show that this kinetic mixing implies the existence of ordinary atom - mirror atom bound states with interesting terrestrial and astrophysical implications. We suggest that sensitive mass spectroscopic studies of ordinary samples containing heavy elements such as lead might reveal the presence of these bound states, as they would appear as anomalously heavy elements. In addition to the effects of single mirror atoms, collective effects from embedded fragments of mirror matter (such as mirror iron microparticles) are also possible. We speculate that such mirror matter fragments might explain a mysterious UV photon burst observed coming from a laser irradiated lead target in a recent experiment.

R. Foot; S. Mitra

2002-04-22

292

Derivation of novel human ground state naive pluripotent stem cells.  

PubMed

Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3? signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, and global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters. Upon withdrawal of 2i/LIF, naive mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include predominant use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalent domain acquisition on lineage regulatory genes. The feasibility of establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in mouse ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation of cross-species chimaeric mouse embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. PMID:24172903

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

2013-12-12

293

Ground State Valency and Spin Configuration of the Ni Ions in Nickelates  

SciTech Connect

The ab initio self-interaction-corrected local-spin-density approximation is used to study the electronic structure of both stoichiometric and nonstoichiometric nickelates. From total energy considerations it emerges that, in their ground state, both LiNiO2 and NaNiO2 are insulators, with the Ni ion in the Ni3+ low-spin state (t2g6eg1) configuration. It is established that a substitution of a number of Li/Na atoms by divalent impurities drives an equivalent number of Ni ions in the NiO2 layers from the Jahn-Teller (JT)-active trivalent low-spin state to the JT-inactive divalent state. We describe how the observed considerable differences between LiNiO2 and NaNiO2 can be explained through the creation of Ni2+ impurities in LiNiO2. The indications are that the random distribution of the Ni2+ impurities might be responsible for the destruction of the long-range orbital ordering in LiNiO2.

Petit, Leon [ORNL; Egami, Takeshi [ORNL; Stocks, George Malcolm [ORNL; Temmerman, Walter M [Daresbury Laboratory, UK; Szotek, Zdzislawa [Daresbury Laboratory, UK

2006-01-01

294

High-fidelity atomic-state teleportation protocol with non-maximally-entangled states Grzegorz Chimczak and Ryszard Tana  

E-print Network

High-fidelity atomic-state teleportation protocol with non-maximally-entangled states Grzegorz-distance atomic-state teleportation via cavity decay, which allows for high-fidelity teleportation even teleportation has been proposed 8­19 . Next step would be to accomplish the long-distance atomic

Tanas, Ryszard

295

Deterministic generation of singlet states for -atoms in coupled cavities via quantum Zeno dynamics  

NASA Astrophysics Data System (ADS)

We propose an efficient scheme to drive two atoms in two coupled cavities into a two-atom singlet state via quantum Zeno dynamics and virtual excitations by one step. Then, we convert the two-atom singlet state into a three-atom singlet state in three coupled bimodal cavities with the same principle. We also discuss the influence of decoherence induced by cavity decay and atomic spontaneous emission by numerical calculation. This scheme is robust against both the cavity decay and atomic spontaneous emission since there are no excited cavity fields involved during the operation process, and the atoms are only virtually excited. Actually, if multi-level atoms and multi-mode cavities are applicable, we can convert the ()-atom () singlet state into a -atom singlet state in coupled cavity arrays with the same principle in theory.

Chen, Ye-Hong; Xia, Yan; Song, Jie

2014-08-01

296

Shape of polygonal quantum dots and ground-state instability in the spin polarization  

NASA Astrophysics Data System (ADS)

We theoretically investigate the ground-state electronic structure and the spin polarization of four electrons confined in two-dimensional (2D) polygonal quantum dots. We employ standard mean-field theory approaches using unrestricted Hartree-Fock (UHF) and density functional theory (DFT) calculations. Resonant UHF configuration interaction (res-UHF CI) calculations were also performed to incorporate the electron correlation more intuitively. Odd polygons (trigons and pentagons) preferentially generate the ground-state triplet as predicted by Hund's rule, whereas even polygons (tetragons, hexagons, and octagons) promote ground-state instability in the spin multiplicity and tend to produce an anti-Hund state of the ground-state singlet with strengthening of the interelectron interaction. The circle, a limited polygon having an infinite number of apexes, divides these odd and even polygons, and the ground-state instability can be well classified by the area of the polygon apexes that protrudes from an equisized circle.

Ishizuki, Masamu; Takemiya, Hannyo; Okunishi, Takuma; Takeda, Kyozaburo; Kusakabe, Kouichi

2012-04-01

297

Ground-state ammonia and water in absorption towards Sgr B2  

Microsoft Academic Search

Context. Observations of transitions to the ground-state of a molecule are essential to obtain a complete picture of its excitation and chemistry in the interstellar medium, especially in diffuse and\\/or cold environments. For the important interstellar molecules H2O and NH3, these ground-state transitions are heavily absorbed by the terrestrial atmosphere, hence not observable from the ground. Aims: We attempt to

E. S. Wirström; P. Bergman; J. H. Black; Å. Hjalmarson; B. Larsson; A. O. H. Olofsson; P. J. Encrenaz; E. Falgarone; U. Frisk; M. Olberg; Aa. Sandqvist

2010-01-01

298

Exact ground state Monte Carlo method for Bosons without importance sampling  

Microsoft Academic Search

Generally ``exact'' quantum Monte Carlo computations for the ground state of many bosons make use of importance sampling. The importance sampling is based either on a guiding function or on an initial variational wave function. Here we investigate the need of importance sampling in the case of path integral ground state (PIGS) Monte Carlo. PIGS is based on a discrete

M. Rossi; M. Nava; L. Reatto; D. E. Galli

2009-01-01

299

Nature of Ground State Incongruence in Two-Dimensional Spin Glasses  

E-print Network

We rigorously rule out the appearance of multiple domain walls between ground states in 2D Edwards-Anderson Ising spin glasses (with periodic boundary conditions and, e.g., Gaussian couplings). This supports the conjecture that there is only a single pair of ground states in these models.

C. M. Newman; D. L. Stein

2000-03-06

300

Ground-state correlation effects in extended random phase approximation calculations  

SciTech Connect

We study normalization problems associated with the use of perturbatively correlated ground states in extended random phase approximation schemes in the context of a specific but typical example. The sensitivity of the results to the amount of two-particle--two-hole admixtures to the correlated ground state is also investigated in terms of a modification of the standard perturbative approach.

Mariano, A.; Krmpotic, F. (Departmento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C. C. 67, 1900 La Plata (Argentina)); de Toledo Piza, A.F.R. (Instituto de Fisica, Universidade de Sao Paulo, C. P. 20516, 01498 Sao Paulo (Brazil))

1994-05-01

301

The nu sub 2 band CHD3; ground state parameters for CHD3 from combination differences  

NASA Technical Reports Server (NTRS)

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 parameters were used in the determination of the alpha and beta molecular parameters for nu sub 2.

Jennings, D. E.; Blass, W. E.

1974-01-01

302

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.

303

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

NASA Astrophysics Data System (ADS)

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

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-01

304

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

PubMed

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

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-21

305

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

306

Excitation of {sup 1}S and {sup 3}S Metastable Helium Atoms to Doubly Excited States  

SciTech Connect

We present spectra of triplet and singlet metastable helium atoms resonantly photoexcited to doubly excited states. The first members of three dipole-allowed {sup 1,3}P{sup o} series have been observed and their relative photoionization cross sections determined, both in the triplet (from 1s2s {sup 3}S{sup e}) and singlet (from 1s2s {sup 1}S{sup e}) manifolds. The intensity ratios are drastically different with respect to transitions from the ground state. When radiation damping is included the results for the singlets are in agreement with theory, while for triplets spin-orbit interaction must also be taken into account.

Alagia, M. [CNR-ISMN Sezione Roma, Piazzale A. Moro 5, I-00185 Roma (Italy); Laboratorio Nazionale TASC, CNR-INFM, I-34012 Trieste (Italy); Coreno, M. [CNR-IMIP, Montelibretti, I-00016 Roma (Italy); Farrokhpour, H.; Omidyan, R.; Tabrizchi, M. [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Franceschi, P. [Dipartimento di Fisica, Universita di Trento, I-38050 Povo (Tunisia) (Italy); Mihelic, A.; Zitnik, M. [Jozef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); Moise, A.; Prince, K. C.; Richter, R. [Sincrotrone Trieste, in Area Science Park, I-34012 Basovizza, Trieste (Italy); Soederstroem, J. [Department of Physics, Uppsala University, Box 530, S-75121 Uppsala (Sweden); Synchrotron SOLEIL, l'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex (France); Stranges, S. [Dipartimento di Chimica, Universita'La Sapienza', I-00185 Roma (Italy); Laboratorio Nazionale TASC, CNR-INFM, I-34012 Trieste (Italy)

2009-04-17

307

Non-classical correlations in a class of spin chains with long-range interactions and exactly solvable ground states  

NASA Astrophysics Data System (ADS)

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

Levi, E.; Lesanovsky, I.

2014-09-01

308

Ground-State Properties of Extended Two-Channel Kondo Model  

NASA Astrophysics Data System (ADS)

Ground-state properties are examined for an extended two-channel Kondomodel where the Hilbert space of the localized states is extended to include a singlet state in addition to thedoublet states.By means of zero-th order variational wavefunctions with differentsymmetries, which are associated with the non-Fermi-liquid and theFermi-liquid ground states, we demonstrate that the channel exchange coupling via the localized singlet statestabilizes the Fermi-liquid wavefunction. The ground-state phase diagrams, which are in qualitative agreement with theprevious study performed by Koga and Shiba, are obtained.The comparison to the structure of the resultant wavefunctions suggests thata unique non-Fermi-liquid (Fermi-liquid) fixed point exists, irrespective ofthe localized ground state.

Kusunose, Hiroaki

1998-01-01

309

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. PMID:23661066

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

2013-01-01

310

Optical Feshbach resonances through a molecular dark state: Efficient manipulation of p-wave resonances in fermionic Yb171 atoms  

NASA Astrophysics Data System (ADS)

In a recent experiment by Yamazaki et al. [Phys. Rev. A 87, 010704(R) (2013), 10.1103/PhysRevA.87.010704], a p-wave optical Feshbach resonance in fermionic Yb171 atoms using purely long-range molecular excited states has been demonstrated. We show theoretically that, if two purely long-range excited states of Yb171 are coupled to the ground-state continuum of scattering states with two lasers, then it is possible to significantly suppress photoassociative atom loss by a dark resonance in the excited states. We present a general theoretical framework for creating a dark state in an electronically excited molecular potential for the purpose of increasing the efficiency of the optical Feshbach resonance. This can be accomplished by properly adjusting the relative intensity, phase, polarizations, and frequency detunings of two lasers. We present selected numerical results for atom-loss spectra and p-wave elastic- and inelastic-scattering cross sections of Yb171 atoms to illustrate the effects of the molecular dark state on the optical Feshbach resonance.

Saha, Subrata; Rakshit, Arpita; Chakraborty, Debashree; Pal, Arpita; Deb, Bimalendu

2014-07-01

311

Analysis of two simultaneous EITs in a four-level atomic system in a W-scheme using a dressed-state representation  

NASA Astrophysics Data System (ADS)

A four-level atomic system in a W-scheme is used for slowing down simultaneously two circularly polarized optical fields using a linearly polarized coupling field. Our four-level atomic system is composed by the ^1S0 ground state and three Zeeman levels of the ^1P1 excited state of any alkali-metal atom introduced in a weak magnetic field. When the coupling field is stronger than both probe fields, the electromagnetic induced transparency (EIT) is observed in the coherences associated to the two probes, while the coherence associated to the coupling field shows opacity. We calculate the quantum coherences from the steady-state solutions of the density matrix master equation, in which we neglect the collisional dephasing (we consider ultra-cold atoms), but we include the radiative decays from each Zeeman state to the ground state. The coupling mechanism between the atomic states and the optical fields in our W-system and the evolution of the EIT features with the intensity of the coupling field is done using an intuitive dressed state representation. We also analyze the transit time from the normal dispersive region to the EIT region: when a weak probe field is used, the transit time is the shortest and the width of the Autler-Townes doublet equals the lifetime of the excited atomic state which experiences EIT, but it increases rapidly as the intensity of the probe field increase.

Bahrim, Cristian

2011-03-01

312

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

PubMed

We produce ultracold dense trapped samples of ^{87}Rb^{133}Cs molecules in their rovibrational ground state, with full nuclear hyperfine state control, by stimulated Raman adiabatic passage (STIRAP) with efficiencies of 90%. We observe the onset of hyperfine-changing collisions when the magnetic field is ramped so that the molecules are no longer in the hyperfine ground state. A strong quadratic shift of the transition frequencies as a function of applied electric field shows the strongly dipolar character of the RbCs ground-state molecule. Our results open up the prospect of realizing stable bosonic dipolar quantum gases with ultracold molecules. PMID:25432045

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

2014-11-14

313

COLD ATOMS AND CREATION OF NEW STATES OF MATTER: BOSE-EINSTEIN CONDENSATES, KAPITZA STATES, AND '2D MAGNETIC  

E-print Network

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

Hau, Lene Vestergaard

314

Unmanned Ground Vehicle State Estimation using an Unmanned Air Vehicle  

Microsoft Academic Search

Unmanned Air Vehicles (UAVs) have several advantages and disadvantages compared with Unmanned Ground Vehicles (UGVs). Both systems have different mobility and perception abilities. UAV systems have extended perception, tracking, and mobility capabilities compared with UGVs. UGVs have more intimate mobility and manipulation capabilities. This paper presents the research that has been conducted in the collaboration of UAVs and UGVs. This

Donald K. Macarthur; Carl D. Crane

2007-01-01

315

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

316

Extreme ground-state deformation of the N=Z nucleus ^76Sr  

NASA Astrophysics Data System (ADS)

The shape of the atomic nucleus is determined by the interplay of macroscopic and microscopic effects within this quantum mechanical many-body system. Self-conjugate nuclei give an opportunity to study the role of np correlations in deformation and have attracted a great interest due to drastic shape evolution along the N=Z line. Strong ground-state deformation is expected to occur for N=Z nuclei above Z=36 from the 2^+ energy systematic as well as from theoretical predictions. Reduced transition strengths B(E2) can guide our understanding of the onset of collectivity along N=Z line. Here, we report on the first determination of B(E2; 2^+ ->0^+) for the N=Z=38 nucleus ^76Sr obtained from the measurement of the 2^+ state lifetime using a line shape technique. ^76Sr nuclei were produced at the NSCL in charge exchange reaction from fast secondary ^76Rb beam. ?-rays emitted at the reaction target position were measured with the SeGA HPGe array in coincidence with reaction residues detected in the S800 spectrometer. Results will be discussed in the light of available data and theoretical predictions to provide insight into the evolution of shell structure and deformation in this region.

Lemasson, A.; Iwasaki, H.; Morse, C.; Baugher, T.; Bazin, D.; Berryman, J.; Gade, A.; McDaniel, S.; Ratkiewicz, A.; Stroberg, S.; Weisshaar, D.; Wimmer, K.; Winkler, R.; Dewald, A.; Fransen, C.; Nichols, A.; Wadsworth, R.

2011-10-01

317

Ground-state Properties of Inhomogeneous Graphene Sheets  

NASA Astrophysics Data System (ADS)

When inter-valley scattering is weak and gauge fields due to e.g. ripples are neglected, doped and gated graphene sheets can be described using an envelope-function Hamiltonian with a new sublattice pseudospin degree-of freedom, an ultrarelativistic massless-Dirac free-fermion term, a pseudospin scalar disorder potential, and a non-relativistic instantaneous Coulombic interaction term. There is considerable evidence from experiment that this simplified description of a honeycomb lattice of Carbon atoms is usually a valid starting point for theories of those observables that depend solely on the electronic properties of ?-electrons near the graphene Dirac point [1]. Although the use of this model simplifies the physics considerably it still leaves us with a many-body problem without translational invariance, which we do not know how to solve. In this talk we present a Kohn-Sham-Dirac density-functional-theory (DFT) scheme for graphene sheets that treats slowly-varying inhomogeneous scalar external potentials and electron-electron interactions on an equal footing [2]. The theory is able to account for the unusual property that the exchange-correlation contribution to chemical potential increases with carrier density in graphene [3,4]. Consequences of this property, and advantages and disadvantages of using the DFT approach to describe it, are discussed. The approach is illustrated by solving the Kohn-Sham-Dirac equations self-consistently for a model random potential describing charged point-like impurities located close to the graphene plane. The influence of electron-electron interactions on these non-linear screening calculations is discussed at length, in the light of recent experiments [5,6] reporting evidence for the presence of electron-hole puddles in nearly-neutral graphene sheets. [4pt] [1] A.K. Geim and K.S. Novoselov, Nature Mater. 6, 183 (2007); A.K. Geim and A.H. MacDonald, Phys. Today 60, 35 (2007); A.H. Castro Neto, F. Guinea, N.M.R. Peres, K.S. Novoselov, and A.K. Geim, arXiv:0709.1163v2 (2007).[0pt] [2] M. Polini, A. Tomadin, R. Asgari, and A.H. MacDonald, Phys. Rev. B 78, 115426 (2008).[0pt] [3] Y. Barlas, T. Pereg-Barnea, M. Polini, R. Asgari, and A.H. MacDonald, Phys. Rev. Lett. 98, 236601 (2007); M. Polini, R. Asgari, Y. Barlas, T. Pereg-Barnea, and A.H. MacDonald, Solid State Commun. 143, 58 (2007). [0pt] [4] E.H. Hwang, B.Y.-K. Hu, and S. Das Sarma, Phys. Rev. Lett. 99, 226801 (2007).[0pt] [5] J. Martin, N. Akerman, G. Ulbricht, T. Lohmann, J.H. Smet, K. von Klitzing, and A. Yacoby, Nature Phys. 4, 144 (2008).[0pt] [6] V.W. Brar, Y. Zhang, C. Girit, F. Wang, A. Zettl, and M. Crommie, Bull. Am. Phys. Soc. 53 (2), 443 (2008).

Polini, Marco

2009-03-01

318

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

319

Characterization of high-energy photoionization in terms of the singularities of the atomic potential. II. Beyond K-shell ionization in a many-electron atom, using the example of a two-electron atom in an excited state  

SciTech Connect

We describe single photoionization of excited states of two-electron atoms by photoabsorption at high incident photon energies {omega} (but still {omega}<states of the simplest many-body system is also, however, applicable for the characterization of high-energy photoionization of a many-electron atom from any subshell. We are using an approach [Suric et al., Phys. Rev. A 67, 022709 (2003)] based on asymptotic Fourier-transform (AFT) theory, in which the matrix elements for photoabsorption processes at high energies are understood in terms of the singularities of the many-body Coulomb potential. We obtain the dependence of the total cross section for single ionization of a two-electron atom in any initial state on photon energy. This energy dependence, for a general initial two-electron state, is generally different from the predictions of independent-particle approximation, and it is in qualitative agreement with recent experimental observations of L-shell photoionization in Ne and M-shell ionization in Ar. As in ground-state ionization, the energy dependence of the dominant contribution to the matrix element is connected, through AFT, with the e-N singularity; and it is determined by the amplitude of the lowest angular momentum l{sub min} with which one electron can approach the e-N singularity. When l{sub min}=0, as in the cases considered experimentally, this gives a factor for the dominant part of the total cross section, which is the same as for the ground state, (1/{omega}{sup 7/2}). The final state interaction reduces this energy dependence by just one additional factor of 1/{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

320

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

E-print Network

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

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

2006-01-01

321

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

NASA Technical Reports Server (NTRS)

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

Danilowicz, R.

1973-01-01

322

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

323

Inhomogenous magnetic ground state in CeAgGa  

Microsoft Academic Search

CeAgGa crystallizes in CeCu2 Imma structure with Ag and Ga atoms randomly distributed at 8 h sites. The magnetic and transport properties of the orthorhombic CeAgGa compound have been obtained from the analysis of ac magnetic susceptibility chi ac , magnetization M vs. magnetic field, specific heat C and electrical resistivity rho. The results provide evidence for the formation of

J. Goraus; A. Slebarski; M. Fijalkowski; L. Hawelek

2011-01-01

324

Collisional and thermal ionization of sodium Rydberg atoms: II. Theory for nS, nP and nD states with n = 5 25  

Microsoft Academic Search

A stochastic model of associative ionization in collisions of Rydberg atoms with ground-state atoms is presented. The conventional Duman-Shmatov-Mihajlov-Janev (DSMJ) model treats the ionization as excitation of Rydberg electron to the continuum by the electric-dipole field generated by exchange interaction within the quasi-molecular ion. The stochastic model essentially extends this treatment by taking into account redistribution of population over a

K. Miculis; I. I. Beterov; N. N. Bezuglov; I. I. Ryabtsev; D. B. Tretyakov; A. Ekers; A. N. Klucharev

2005-01-01

325

Dissipative Preparation of Spin Squeezed Atomic Ensembles in a Steady State  

E-print Network

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

Dalla Torre, Emanuele G.

326

Electronically Nonalloyed State of a Statistical Single Atomic Layer Semiconductor Alloy  

E-print Network

Electronically Nonalloyed State of a Statistical Single Atomic Layer Semiconductor Alloy Ph. Ebert overlayer. KEYWORDS: Single atomic layer semiconductor alloy, electronic structure, scanning tunneling spectroscopy Alloying different semiconductor compounds attracted wide attention, since the material properties

Dunin-Borkowski, Rafal E.

327

Raman - Nath approximation for diffraction of atoms in the laser field taking into account spontaneous emission of atoms for ground and high energy level  

NASA Astrophysics Data System (ADS)

The problem of resonant Kapitza - Dirac diffraction is solved in Raman - Nath approximation out of familiar Bessel function approximation (applicable in zero and very large resonance detuning cases). It shows new and promising results for the atom optics and atom interferometry if the atomic momentum state has been prepared in a form of discrete Gaussian distribution. Namely, instead of monotonic broadening within the Bessel function approximation, our formula yields in splitting of initial distribution into two identical peaks, whith preserving form, which symmetrically move away from the distribution center for the interaction time. A table-shaped form for the ultimate momentum distribution also is in frame of new distributions. As to relaxation processes, they have only quantitative influence on the pattern of diffraction.

Hovhannisayan, L.; Muradyan, A. Zh

2012-03-01

328

Entanglement of orbital angular momentum states between an ensemble of cold atoms and a photon  

E-print Network

Various atom-photon entangled states can be generated by utilizing corresponding conservation law. In particular, higher-dimensional entanglement between an atomic ensemble and a photon is expected to arise from angular momentum conservation law. Here we demonstrate entanglement of orbital angular momentum states by utilizing atomic collective excitation and Laguerre-Gaussian modes of light. Generation of higher-dimensional entanglement between remote atomic ensembles and an application to condensed matter physics are also discussed.

Inoue, R; Yonehara, T; Miyamoto, Y; Koashi, M; Kozuma, M

2006-01-01

329

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

330

An N-atom Collective State Atomic Clock with Root-N Fold Increase in Effective Frequency and Root-N Fold Reduction in  

E-print Network

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

Shahriar, Selim

331

An output coupler for Bose condensed atoms The observations of BEC have stimulated interest in atom lasers, coherent sources of  

E-print Network

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

332

Bott periodicity for Z2 symmetric ground states of gapped free-fermion systems  

E-print Network

Building on the symmetry classification of disordered fermions, we give a proof of the proposal by Kitaev, and others, for a "Bott clock" topological classification of free-fermion ground states of gapped systems with symmetries. Our approach differs from previous ones in that (i) we work in the standard framework of Hermitian quantum mechanics over the complex numbers, (ii) we directly formulate a mathematical model for ground states rather than spectrally flattened Hamiltonians, and (iii) we use homotopy-theoretic tools rather than K-theory. Key to our proof is a natural transformation that squares to the standard Bott map and relates the ground state of a d-dimensional system in symmetry class s to the ground state of a (d+1)-dimensional system in symmetry class s+1. This relation gives a new vantage point on topological insulators and superconductors.

Kennedy, Ricardo

2014-01-01

333

Calculation of ground state energy of harmonically confined two dipolar fermions  

E-print Network

We calculate the ground state energies of a system of two dipolar fermions trapped in a harmonic oscillator potential. The dipoles are assumed to be aligned parallel to each other. We perform the calculations of ground state energy as a function of strength of interaction between two fermions by employing variational method with Hylleraas-like explicitly correlated wave function. Furthermore, we perform calculations of ground state energy within Hartree-Fock approximation and the magnitude of correlation energy is estimated by subtracting these results from the corresponding wave function based results. We also carry out calculations of ground state energies within the realm of density functional theory by using recently reported expressions for exchange and correlation energies under local density approximation. By comparing correlated wave function based results with those obtained using density functional theory approach we examine the role of fermion-fermion correlation and assess the accuracy of local de...

Das, Amit K

2014-01-01

334

Ground-state structure in a highly disordered spin-glass model  

SciTech Connect

We propose a new Ising spin-glass model on Z{sup d} of Edwards-Anderson type, but with highly disordered coupling magnitudes, in which a greedy algorithm for producing ground states is exact. We find that the procedure for determining (infinite-volume) ground states for this model can be related to invasion percolation with the number of ground states identified as 2{sup N}, where N = N (d) is the number of distinct global components in the {open_quotes}invasion forest{close_quotes}. We prove that N(d)= {infinity} is d{sub c}=8. When N(d)={infinity}, we consider free or periodic boundary conditions on cubes of side length L and show that frustration leads to chaotic L dependence with all pairs of ground states occurring as subsequence limits. We briefly discuss applications of our results to random walk problems on rugged landscapes.

Newman, C.M. [New York Univ., NY (United States); Stein, D.L. [Univ. of Arizona, Tucson, AZ (United States)

1996-02-01

335

Vacuum polarization screening corrections to the ground state energy of two-electron ions  

E-print Network

Vacuum polarization screening corrections to the ground state energy of two-electron ions are calculated in the range $Z=20-100$. The calculations are carried out for a finite nucleus charge distribution.

A. N. Artemyev; V. M. Shabaev; V. A. Yerokhin

1997-07-06

336

Bott periodicity for Z2 symmetric ground states of gapped free-fermion systems  

E-print Network

Building on the symmetry classification of disordered fermions, we give a proof of the proposal by Kitaev, and others, for a "Bott clock" topological classification of free-fermion ground states of gapped systems with symmetries. Our approach differs from previous ones in that (i) we work in the standard framework of Hermitian quantum mechanics over the complex numbers, (ii) we directly formulate a mathematical model for ground states rather than spectrally flattened Hamiltonians, and (iii) we use homotopy-theoretic tools rather than K-theory. Key to our proof is a natural transformation that squares to the standard Bott map and relates the ground state of a d-dimensional system in symmetry class s to the ground state of a (d+1)-dimensional system in symmetry class s+1. This relation gives a new vantage point on topological insulators and superconductors.

Ricardo Kennedy; Martin R. Zirnbauer

2014-09-08

337

Ground State and Resonances in the Standard Model of the Non-relativistic QED  

E-print Network

Ground State and Resonances in the Standard Model of the Non-relativistic QED Israel Michael Sigal of the system under consideration is Supported by NSERC Grant No. NA7901 webpage: www.math.toronto.edu/sigal 1

338

Slow ground state molecules from matrix isolation sublimation  

E-print Network

We describe the generation and properties of a cryogenic beam of $^7$Li$_2$ dimers from sublimation of a neon matrix where lithium atoms have been implanted via laser ablation of solid precursors of metallic lithium or lithium hydride (LiH). Different sublimation regimes lead to pulsed molecular beams with different temperatures, densities and forward velocities. With laser absorption spectroscopy these parameters were measured using the molecular $^7$Li$_2$ (R) transitions A$^1\\Sigma_u^+(v'=4,J'=J''+1)\\leftarrow $X$^1\\Sigma_g^+ (v''=0,J''=0,1,3)$. In a typical regime, sublimating a matrix at 16 K, translational temperatures of 6--8 K with a drift velocity of 130 m$\\,$s$^{-1}$ in a free expanding pulsed beam with molecular density of 10$^9$ cm$^{-3}$, averaged along the laser axis, were observed. Rotational temperatures around 5--7 K were obtained. In recent experiments we were able to monitor the atomic Li signal -- in the D2 line -- concomitantly with the molecular signal in order to compare them as a funct...

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

2014-01-01

339

A Kind of Atomic Coherent State as a Two-Mode Squeezed State  

NASA Astrophysics Data System (ADS)

We find that a kind of atomic coherent state, formed as exp[?J+ - ?*J-] |00>, when the SU(2) generators J± are taken as Fan's form, J+ = (1/2)(a1 - a2†)(a1† - a2), J- = (1/2)(a†1 + a2) (a1 + a2†), and J0 = (1/2)(a1†a2† - a1a2), is simultaneously a two-mode squeezed state. We analyse this squeezed state's physical properites, such as the cross-correlation function, the Wigner function, and its marginal distribution as well as the Husimi function.

Ma, Shan-Jun; Wang, Shu-Jing

2009-09-01

340

Historical Analysis and Charaterization of Ground Level Ozone for Canada and United State  

Microsoft Academic Search

Ground-level ozone has long been recognized as an important health and ecosystem-related air quality concern in Canada and the United States. In this work we seek to understand the characteristics of ground level ozone conditions for Canada and United States to support the Ozone Annex under the Canada-U.S. Air Quality Agreement. Our analyses are based upon the data collected by

H. Lin; H. Li; H. Auld

2003-01-01

341

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

Microsoft Academic Search

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

Wirawan Purwanto; Shiwei Zhang

2004-01-01

342

The magnetic ground state of CaMn2Sb2  

NASA Astrophysics Data System (ADS)

We have determined the ground state of the layered compound CaMn 2Sb 2 which crystalizes in the CaAl 2Si 2 structure. We have performed specific heat and neutron powder diffraction measurements at different temperatures. The neutron powder diffraction results reveal that the system orders antiferromagnetically at 88 K which agrees with the specific heat measurements. The ground state magnetic structure is consistent with previous theoretical calculations.

Ratcliff, W., II; Lima Sharma, A. L.; Gomes, A. M.; Gonzalez, J. L.; Huang, Q.; Singleton, J.

2009-09-01

343

The eta-pairing ground states in the negative-U Hubbard model are supersolid  

Microsoft Academic Search

Since Yang [Phys. Rev. Lett 63 (1989) 2144] proposed the possible existence of the eta-pairing off-diagonal long-range order (ODLRO) in the ground states of the negative-U Hubbard model, this problem has been studied by many physicists. In this article, based on our previous work, we shall rigorously show that all the ground states, which have the eta-pairing ODLRO, are actually

Guang-Shan Tian

1994-01-01

344

Ground-state and excitation spectra of the negative- U Hubbard model  

Microsoft Academic Search

We study the negative-{ital U} Hubbard model by exact diagonalization of a 4Ã4 cluster with different numbers of particles. We calculate the ground-state energy and wave function as well as the one-particle, charge- and spin-excitation spectra. We show that the BCS approximation gives results in good agreement with the exact ones for the ground-state energy and wave function in the

H. E. Castillo; C. A. Balseiro

1992-01-01

345

Ground-state and excitation spectra of the negative-U Hubbard model  

Microsoft Academic Search

We study the negative-U Hubbard model by exact diagonalization of a 4×4 cluster with different numbers of particles. We calculate the ground-state energy and wave function as well as the one-particle, charge- and spin-excitation spectra. We show that the BCS approximation gives results in good agreement with the exact ones for the ground-state energy and wave function in the whole

H. E. Castillo; C. A. Balseiro

1992-01-01

346

The ?-pairing ground states in the negative-U Hubbard model are supersolid  

NASA Astrophysics Data System (ADS)

Since Yang [Phys. Rev. Lett 63 (1989) 2144] proposed the possible existence of the ?-pairing off-diagonal long-range order (ODLRO) in the ground states of the negative- U Hubbard model, this problem has been studied by many physicists. In this article, based on our previous work, we shall rigorously show that all the ground states, which have the ?-pairing ODLRO, are actually supersolid rather than superfluid as one expected before.

Tian, Guang-Shan

1994-09-01

347

On crystal ground state in the Schrödinger-Poisson model: point ions  

E-print Network

A space-periodic ground state is shown to exist for lattices of point ions in $\\R^3$ coupled to the Schr\\"odinger and scalar fields. The coupling requires the renormalization of the selfaction because of the singularity of the Coulomb potential. The ground state is constructed by minimization of the renormalized energy per cell. This energy is bounded from below when the charge of each ion is positive. The elementary cell is necessarily neutral.

A. I. Komech

2014-09-05

348

Toward ferromagnetic materials: prediction of a triplet ground state for heterocyclic polyacenes  

NASA Astrophysics Data System (ADS)

Bis-1,2,4-triazines were explored as potential ground-state triplet molecules which might serve as components of ferromagnetic materials. Relationships between numbers of rings and singlet-triplet gaps were explored by hybrid density functional theory for a series of heterocyclic polyacenes. Available X-ray structures of bis-triazines are compared to computed model compounds and used to check the methodology. A hexacyclic bis-1,2,4-triazine is predicted to have a triplet ground state.

Strassner, Th.; Weitz, Amir; Rose, Jefferson; Wudl, Fred; Houk, K. N.

2000-05-01

349

High-fidelity rapid ground-state loading of an ultracold gas into an optical lattice  

E-print Network

A protocol is proposed for the rapid coherent loading of a Bose-Einstein condensate into the ground state of an optical lattice, without residual excitation associated with the breakdown of adiabaticity. The driving potential required to assist the rapid loading is derived using the fast forward technique, and generates the ground state in any desired short time. We propose an experimentally feasible loading scheme using a bichromatic lattice potential, which approximates the fast-forward driving potential with high fidelity.

Masuda, Shumpei; del Campo, Adolfo

2014-01-01

350

Many electron variational ground state of the two dimensional Anderson lattice  

SciTech Connect

A variational upper bound of the ground state energy of two dimensional finite Anderson lattices is determined as a function of lattice size (up to 16 x 16). Two different sets of many-electron basis vectors are used to determine the ground state for all values of the coulomb integral U. This variational scheme has been successfully tested for one dimensional models and should give good estimates in two dimensions.

Zhou, Y.; Bowen, S.P. [Argonne National Lab., IL (United States). Materials Science Div.; Mancini, J.D. [Fordham Univ., Bronx, NY (United States). Dept. of Physics

1991-02-01

351

Formation of nonstationary atomic states by microwave field  

NASA Astrophysics Data System (ADS)

We have excited Li atoms to np (55?85) Rydberg states and exposed them to a MW field of 17.5 GHz. We detect time-dependent motion of the electron through the ionization by subpicosecond half-cycle field pulses which are sensitive to the time-varying momentum of the electron. We have observed the evolution of energy eigenstates to a wave packet which is periodic and nondispersive in time domain, in contrast to a radial Rydberg wave packet coherently created by short optical pulses. Its oscillation period exactly matches the MW field cycle or the classical orbit time, ˜57 ps, of Li Rydberg states of n=72 at the scaled angular frequency ?_0=n^3 ?=1, where n is the principal quantum number and ? is the MW angular frequency. At n=56 we observe an oscillation in the electron motion having a ˜28-ps period, corresponding to half of the MW cycle or the classical orbit time at ?_0=1/2. These observations indicate that a nondispersive wave packet is created synchronized with the MW field, as was suggested in Refs. [1] and [2]. [1] A. Buchleitner and D. Delande, Phys. Rev. Lett. 75, 1487 (1995). [2] M.W. Noel et al., Phys. Rev. A 62, 063201 (2000).

Maeda, H.; Gallagher, T. F.

2003-05-01

352

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

353

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

PubMed

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

Petrosyan, David; Kurizki, Gershon

2002-11-11

354

Improving fidelity in atomic state teleportation via cavity decay Grzegorz Chimczak and Ryszard Tana  

E-print Network

Improving fidelity in atomic state teleportation via cavity decay Grzegorz Chimczak and Ryszard a modified protocol of atomic state teleportation for the scheme proposed by Bose et al. Phys. Rev. Lett. 83 it possible to obtain a high fidelity of teleported state for cavities that are much worse than that required

Tanas, Ryszard

355

Gauge-invariant ground state for canonically quantized Yang-Mills theory  

E-print Network

We use Hamilton-Jacobi theory to construct a gauge-invariant zero-energy candidate ground state for canonically quantized Yang-Mills theory with a "nonlinear normal" factor ordering, generalizing an analogous ordering introduced by Moncrief and Ryan for problems with finitely many degrees of freedom. Invariance under spatial rotations and translations is immediate; boost invariance remains under investigation. The motivation is to find a model for constructing a candidate ground state in general relativity, canonically quantized a la the Ashtekar variables. We seek to avoid replicating some of the more troublesome features of the Kodama state, inherited from the Chern-Simons state.

Rachel Lash Maitra

2008-04-18

356

Solvatochromic study of quinidine: Determination of ground and excited state dipole moments  

NASA Astrophysics Data System (ADS)

The absorption and fluorescence spectra of quinidine (QD) have been recorded at room temperature in wide range of solvents of different polarities. The absorption maximum remains almost unchanged with the increase in solvent polarity, whereas a red shift in fluorescence emission maximum was observed. Ground and excited state dipole moments of probe quinidine (QD) was obtained using Solvatochromic shift method. Higher dipole moment is observed for excited state as compared to the ground state which is attributed to the higher polarity of excited state.

Joshi, Sunita; Pant, Debi D.

2013-06-01

357

Fragmented Metastable States Exist in an Attractive Bose-Einstein Condensate for Atom Numbers Well above the Critical Number of the Gross-Pitaevskii Theory  

SciTech Connect

It is well known that attractive condensates do not posses a stable ground state in three dimensions. The widely used Gross-Pitaevskii theory predicts the existence of metastable states up to some critical number N{sub cr}{sup GP} of atoms. It is demonstrated here that fragmented metastable states exist for atom numbers well above N{sub cr}{sup GP}. The fragments are strongly overlapping in space. The results are obtained and analyzed analytically as well as numerically. The implications are discussed.

Cederbaum, Lorenz S.; Streltsov, Alexej I.; Alon, Ofir E. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

2008-02-01

358

Ultra-cold atomic matter and quantum information My group studies various many-body states of ultra cold atoms and  

E-print Network

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

Plotkin, Steven S.

359

Ground and ionic states of 1,2,5-thiadiazoles: An UV-photoelectron spectroscopic and theoretical study  

NASA Astrophysics Data System (ADS)

Electronic structures of 1,2,5-thiadiazoles (X 2C 2N 2S, where X = H, F, Cl, CH 3, CN) have been investigated in the gas phase by He I and He II UV-photoelectron spectroscopy, as well as by calculations at the B3LYP and SAC-CI levels using aug-cc-pV(T+d)Z basis sets. The ground state geometry of the neutral molecules has been obtained from quantum-chemical calculations at the B3LYP level. Thiadiazoles are predicted to be planar, not considering methyl-group hydrogen atoms, with C 2v symmetry. Equilibrium structures of the four lowest energy cationic states have been determined at the UB3LYP level, and calculations predicted that the sequence of ionic states is 2B 1(ground state) < 2B 2 < 2A 2 < 2A 1. Photoelectron spectroscopy and theory applied to thiadiazoles has provided information on the valence occupied levels, on the ionisation energies, and on the fundamental vibrations of the cations.

Pasinszki, Tibor; Krebsz, Melinda; Vass, Gábor

2010-03-01

360

Ordered ground states of metallic hydrogen and deuterium  

NASA Technical Reports Server (NTRS)

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

Ashcroft, N. W.

1981-01-01

361

Gaining Ground: Poverty in the Postwar United States  

Microsoft Academic Search

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

Daniel T. Slesnick

1993-01-01

362

Coherent Atom Interactions Mediated by Dark-State Polaritons  

E-print Network

We suggest a technique to induce effective, controllable interactions between atoms that is based on Raman scattering into an optical mode propagating with a slow group velocity. The resulting excitation corresponds to the creation of spin-flipped atomic pairs in a way that is analogous to correlated photon emission in optical parametric amplification. The technique can be used for fast generation of entangled atomic ensembles, spin squeezing and applications in quantum information processing.

A. Andre; L. -M. Duan; M. D. Lukin

2001-07-14

363

Ground radiation tests and flight atomic oxygen tests of ITO protective coatings for Galileo Spacecraft  

NASA Technical Reports Server (NTRS)

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

Bouquet, Frank L.; Maag, Carl R.

1986-01-01

364

Solvent effect on the absorption and fluorescence spectra of 7-acetoxy-6-(2,3-dibromopropyl)-4,8-dimethylcoumarin: Determination of ground and excited state dipole moments  

NASA Astrophysics Data System (ADS)

The ground state (?g) and excited state (?e) dipole moments of 7-acetoxy-6-(2,3-dibromopropyl)-4,8-dimethylcoumarin (abbreviated as 7ADDC) are estimated from solvatochromic shifts of absorption and fluorescence spectra as a function of the dielectric constant (?) and refractive index (n). While the ground state dipole moment is determined by using Bilot-Kawski method, the excited state dipole moment is calculated by using Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet and Reichardt correlation methods. Excited state dipole moment is observed as larger than the ground state dipole moment due to substantial ?-electron density redistribution. The ground state and excited state dipole moments are observed as parallel to each other with angle of 0°. Solute-solvent interactions are analyzed by means of linear solvation free energy relationships (LSER) using dielectric constant function (f(?)), refractive index function (f(n)) and Kamlet-Taft parameters (? and ?). Atomic charges, electron densities and molecular orbitals are calculated in vacuum and with solvent effect by using both DFT and TDDFT methods. Solvent accessible surface, molecular electrostatic potential (MEP) and electrostatic potential (ESP) are visualized as a result of DFT calculations.

Gülseven S?d?r, Yadigar; S?d?r, ?sa

2013-02-01

365

Squeezed-state generation via nonlinear atom-atom interaction in the atomic field of a Bose-Einstein condensate interacting with an optical cavity  

E-print Network

In this paper, we investigate theoretically a system consisting of a one dimensional Bose-Einstein condensate trapped inside the optical lattice of an optical cavity. In the weak-interaction regime and under the Bogoliubov approximation, the wave function of the Bose-Einstein condensate can be described by a classical field (condensate mode) having some quantum fluctuations (the Bogoliubov mode) about the mean value. Such a system behaves as a so-called atomic parametric amplifier, similar to an optical parametric amplifier, where the condensate and the Bogoliubov modes play respectively, the roles of the pump field and the signal mode in the degenerate parametric amplifier and the s-wave scattering frequency of atom-atom interaction plays the role of the nonlinear gain parameter. We show that using the nonlinear effect of atomic collisions, how one can manipulate and control the state of the Bogoliubov mode and produce squeezed states.

A. Dalafi; M. H. Naderi; M. Soltanolkotabi

2014-03-29

366

Exciton Bose condensation : the ground state of an electron-hole gas II. Spin states, screening and band structure effects  

E-print Network

1083 Exciton Bose condensation : the ground state of an electron-hole gas II. Spin states : screening corrections do not change the sign of the compressibility, which remains positive, in contrast expect a first order transition with a liquid-gas phase separation. J. Physique 43 (1982) 1083

Boyer, Edmond

367

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

E-print Network

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

Weizhu Bao; Yongyong Cai

2014-07-22

368

Hall response of interacting bosonic atoms in strong gauge fields: From condensed to fractional-quantum-Hall states  

NASA Astrophysics Data System (ADS)

Interacting bosonic atoms under strong gauge fields undergo a series of phase transitions that take the cloud from a simple Bose-Einstein condensate all the way to a family of fractional-quantum-Hall-type states [M. Popp, B. Paredes, and J. I. Cirac, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.70.053612 70, 053612 (2004)]. In this work we demonstrate that the Hall response of the atoms can be used to locate the phase transitions and characterize the ground state of the many-body state. Moreover, the same response function reveals within some regions of the parameter space, the structure of the spectrum and the allowed transitions to excited states. We verify numerically these ideas using exact diagonalization for a small number of atoms, and provide an experimental protocol to implement the gauge fields and probe the linear response using a periodically driven optical lattice. Finally, we discuss our theoretical results in relation to recent experiments with condensates in artificial magnetic fields [L. J. LeBlanc, K. Jimenez-Garcia, R. A. Williams, M. C. Beeler, A. R. Perry, W. D. Phillips, and I. B. Spielman, Proc. Natl. Acad. Sci. USAPNASA60027-842410.1073/pnas.1202579109 109, 10811 (2012)] and we analyze the role played by vortex states in the Hall response.

Pino, H.; Alba, E.; Taron, J.; Garcia-Ripoll, J. J.; Barberán, N.

2013-05-01

369

Bound states of positrons with atoms and molecules: Theory  

Microsoft Academic Search

Calculations of the binding energies and annihilation rates of bound atomic and molecular systems which contain a positron are reviewed. Emphasis is placed on methods of calculation and the quality of the numerical results. In this article we limit our attention to positrons interacting with atoms, diatomic molecules, and their ions.

D. M. Schrader

1998-01-01

370

Coherent Quantum StateManipulation Of Trapped Atomic Ions'  

E-print Network

in thispaper. In Fig. 1we show schematically a "linear"Paul trap. Thistrap is based on the one described in;42 D.J.Wineland et 01. 1. INTRODUCTION Currently, a major theme in atomic, molecular, and optical this creates an oscillating potential of the form #12;ManipulationofTrappedAtomic Ions 43 v - v o 1 + R'), x

371

Hartree theory for the negative-U extended Hubbard model: Ground state  

NASA Astrophysics Data System (ADS)

We have investigated the ground-state properties of the negative-U extended Hubbard model in the weak-coupling regime with the Hartree theory formulated in terms of the Bogoliubov variational approach. While the pure phases of charge order (CO), singlet superconducting (SS), and nonordered can be solved analytically with a model density of states, the mixed phase of CO and SS requires numerical computation. The ground-state phase diagram is derived, and the order parameters and the chemical potential of the ground state are analyzed. The characteristic difference between the behaviors of the SS and the CO order parameters at very weak coupling suggests a complicated competition between various interactions. Present results are compared with those derived earlier for the strong-coupling regime.

Robaszkiewicz, S.; Micnas, R.; Chao, K. A.

1981-10-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

373

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

374

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

PubMed

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

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

2014-09-12

375

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

E-print Network

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

P. Marecki

2005-07-20

376

Determination of ground and excited state dipole moments of dipolar laser dyes by solvatochromic shift method.  

PubMed

The absorption and fluorescence spectra of three medium sized dipolar laser dyes: coumarin 478 (C478), coumarin 519 (C519) and coumarin 523 (C523) have been recorded and studied comprehensively in various solvents at room temperature. The absorption and fluorescence spectra of C478, C519 and C523 show a bathochromic and hypsochromic shifts with increasing solvent polarity indicate that the transitions involved are ???(?) and n??(?). Onsager radii determined from ab initio calculations were used in the determination of dipole moments. The ground and excited state dipole moments were evaluated by using solvatochromic correlations. It is observed that the dipole moment values of excited states (?e) are higher than corresponding ground state values (?g) for the solvents studied. The ground and excited state dipole moments of these probes computed from ab initio calculations and those determined experimentally are compared and the results are discussed. PMID:24394528

Patil, S K; Wari, M N; Panicker, C Yohannan; Inamdar, S R

2014-04-01

377

Tracing masses of ground-state light-quark mesons  

E-print Network

We describe a symmetry-preserving calculation of the meson spectrum, which combines a description of pion properties with reasonable estimates of the masses of heavier light-quark mesons, including axial-vector states. The kernels used in formulating the problem are essentially nonperturbative. They incorporate effects of dynamical chiral symmetry breaking (DCSB) that were not previously possible to express. Our analysis clarifies a causal connection between DCSB and the splitting between vector and axial-vector mesons, and exposes a key role played by the anomalous chromomagnetic moment of dressed-quarks in forming the spectrum.

Lei Chang; Craig D. Roberts

2011-04-25

378

Ground state energy of solid molecular hydrogen at high pressure  

NASA Technical Reports Server (NTRS)

The present status of the theoretical equation of state of solid molecular hydrogen is reviewed. Different quantum mechanical calculations by several groups lead to results which generally agree with each other but which disagree systematically with the measured pressure-volume curve at pressures larger than about 3000 atm. A new calculation of this curve is presented including the effect of the anisotropic interaction between H2 molecules within a completely quantum-mechanical formalism. The results show that inclusion of this interaction removes the discrepancy between theory and experiment at high pressures and that a quantum-mechanical treatment is necessary to realize its full effect.

Ebner, C.; Sung, C. C.

1972-01-01

379

Ground state of a tightly bound composite dimer immersed in a Fermi Sea Christophe Mora1  

E-print Network

investigation for the ground state of an impurity immersed in a Fermi sea. The molecular regime is considered where a two-body bound state between the impurity and one of the fermions is formed. Both interaction of the normal com- ponent persists between the two groups, both observe a shell structure in the density profile

Boyer, Edmond

380

A Spectroscopic Model for the Study of Preferential in the Ground and Excited Electronic States  

Microsoft Academic Search

The preferential solvation of a solute molecule in mixed solvents is analysed in terms of the spectral solvent shifts. A spectroscopic model is developed in order to know the preferential solvation degree in the ground electronic state as well as in the first excited electronic state by measuring the absorption and fluorescence spectra respec tively.Triphenylene was found to be a

RaÚL G. E. Morales

1983-01-01

381

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

EPA Science Inventory

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

382

{alpha} decay of nuclei in the range 67{<=}Z{<=}91 from the ground state and isomeric state  

SciTech Connect

The Coulomb and proximity potential model for deformed nuclei (CPPMDN) is used to study the favored and unfavored {alpha} decay of nuclei in the range 67{<=}Z{<=}91 from both the ground state (g.s.) and isomeric state (i.s.). The computed half-lives are in good agreement with experimental data. The standard deviation of half-life is found to be 0.44. Geiger-Nuttall (GN) plots for various parent isotopes are studied. It is found that all four types of transitions (g.s.{yields}g.s., g.s.{yields}i.s., i.s.{yields}g.s., i.s.{yields}i.s.) lie on a straight line. The isomeric state {alpha} decay shows a behavior similar to that of the ground state and the nuclear structure of the isomeric states imitates that of the ground states. Some predictions are done for {alpha} transition from both ground and isomeric states, which will be useful for future experiments.

Santhosh, K. P.; Joseph, Jayesh George; Sahadevan, Sabina [School of Pure and Applied Physics, Kannur University, Payyanur Campus, Payyanur 670 327 (India)

2010-12-15

383

Ground Water Atlas of the United States: Introduction and National Summary  

USGS Publications Warehouse

The Ground Water Atlas of the United States provides a summary of the most important information available for each principal aquifer, or rock unit that will yield usable quantities of water to wells, throughout the 50 States, Puerto Rico, and the U.S. Virgin Islands. The Atlas is an outgrowth of the Regional Aquifer-System Analysis (RASA) program of the U.S. Geological Survey (USGS), a program that investigated 24 of the most important aquifers and aquifer systems of the Nation and one in the Caribbean Islands (fig. 1). The objectives of the RASA program were to define the geologic and hydrologic frameworks of each aquifer system, to assess the geochemistry of the water in the system, to characterize the ground-water flow system, and to describe the effects of development on the flow system. Although the RASA studies did not cover the entire Nation, they compiled much of the data needed to make the National assessments of ground-water resources presented in the Ground Water Atlas of the United States. The Atlas, however, describes the location, extent, and geologic and hydrologic characteristics of all the important aquifers in the United States, including those not studied by the RASA program. The Atlas is written so that it can be understood by readers who are not hydrologists. Simple language is used to explain technical terms. The principles that control the presence, movement, and chemical quality of ground water in different climatic, topographic, and geologic settings are clearly illustrated. The Atlas is, therefore, useful as a teaching tool for introductory courses in hydrology or hydrogeology at the college level and as an overview of ground-water conditions for consultants who need information about an individual aquifer. It also serves as an introduction to regional and National ground-water resources for lawmakers, personnel of local, State, or Federal agencies, or anyone who needs to understand ground-water occurrence, movement, and quality. The purpose of the Ground Water Atlas of the United States is to summarize, in one publication with a common format, the most important ground-water information that has been collected over many years by the USGS, other Federal agencies, and State and local water management agencies. The purpose of this introductory chapter is to describe the content of the Atlas; to discuss the characteristics, use, and limitations of the maps and other types of illustrations used in the different chapters of the book; to summarize the locations of the principal aquifers on a Nationwide map; and to give an example of an aquifer in each principal hydrogeologic setting.

Miller, James A.

1999-01-01

384

Simple model of self-supported deformed states of isolated atoms  

SciTech Connect

We propose a simple three-body model of an atom in which one electron on a circular Rydberg orbit is treated as an independent particle and the remaining core electrons are collectively described as a single object. Within this model we predict the existence of stable deformed states of atoms. The deformation is generated by a bootstrap mechanism. The atomic core is polarized by the excited electron and the induced dipole moment keeps this electron localized. The deformed stable states of the atom are similar to the Trojan states observed in recent experiments. However, in the present case the breaking of the rotational symmetry does not require the presence of external fields.

Bialynicki-Birula, Iwo; Bialynicka-Birula, Zofia [Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2010-01-15

385

Toward an improved ground state potential energy surface of ozone.  

PubMed

A systematic study of the ozone potential energy surface was performed by means of high level ab initio techniques. The methods include icMR-CISD and icMR-AQCC with all electrons correlated using a full valence CAS reference space and basis sets up to sextuple-? quality along with extrapolation to the complete basis set limit. We computed a dense 3D grid as well as 1D cuts along stretching and bending coordinates around the open (C(2v)) equilibrium structure as well as along the minimum energy path to dissociation including the transition state and the van der Waals minimum region. The detailed analysis of our results confirms earlier calculations by the Schinke group and assures that these are not biased by deficiencies of the basis set, lack of relativistic corrections, or core correlation effects. Finally, we discuss possible sources of error that may explain the remaining discrepancies compared to experimental findings. PMID:20825243

Holka, Filip; Szalay, Péter G; Müller, Thomas; Tyuterev, Vladimir G

2010-09-16

386

Ground- and excited-state properties of the polar and paramagnetic RbSr molecule: A comparative study  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

387

Ground and excited state properties of the polar and paramagnetic RbSr molecule: a comparative study  

E-print Network

This paper deals with the electronic structure of RbSr, a molecule possessing both a permanent magnetic and electric dipole moment in its own frame allowing its manipulation with external fields. Two complementary ab-initio approaches are used for the ground and lowest excited states: first, an approach relying on optimized effective core potentials with core polarization potentials based on a full configuration interaction involving three valence electrons, and second, an approach using a small-size effective core potential with 19 correlated electrons in the framework of coupled-cluster theory. We have found excellent agreement between these two approaches for the ground state properties including the permanent dipole moment. We have focused on studies of excited states correlated to the two lowest asymptotes Rb(5p)+Sr(5s) and Rb(5s)+Sr(5s5p) relevant for ongoing experiments on quantum degenerate gases. We present also the Hund c) case potential curves obtained using atomic spin-orbit constants. These poten...

?uchowski, Piotr S; Dulieu, Olivier

2014-01-01

388

Beam Splitter-Mediated Quantum Information Processing Employing Momentum States of the Neutral Atoms  

NASA Astrophysics Data System (ADS)

We propose various schemes for the generation and manipulation of a variety of atomic external transverse momentum states. The fundamental ingredient of all such states is a simple bipartite cavity field-atomic momentum entangled state generated through second order, off-resonant Bragg diffraction of the neutral two-level atoms. Further multipartite entangled state engineering and manipulation including Bell, GHZ, Dicke and W-state production, remote state-assisted entanglement swapping, and teleportation of a cavity field superposition as well as the entanglement onto atomic momentum states are carried out by simultaneously projecting the cavity field(s) over symmetric beam splitter(s). It is further discussed that generation and manipulation of such decoherence resistant momentum states is quite feasible under prevailing experimental research scenario in cavity QED.

Abbas, Tasawar; Ul-Islam, Rameez; Ikram, Manzoor

2014-08-01

389

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

SciTech Connect

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

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

1984-11-13

390

Synergistic Mechanisms of DNA Demethylation during Transition to Ground-State Pluripotency  

PubMed Central

Summary Pluripotent stem cells (PSCs) occupy a spectrum of reversible molecular states ranging from a naive ground-state in 2i, to metastable embryonic stem cells (ESCs) in serum, to lineage-primed epiblast stem cells (EpiSCs). To investigate the role of DNA methylation (5mC) across distinct pluripotent states, we mapped genome-wide 5mC and 5-hydroxymethycytosine (5hmC) in multiple PSCs. Ground-state ESCs exhibit an altered distribution of 5mC and 5hmC at regulatory elements and dramatically lower absolute levels relative to ESCs in serum. By contrast, EpiSCs exhibit increased promoter 5mC coupled with reduced 5hmC, which contributes to their developmental restriction. Switch to 2i triggers rapid onset of both the ground-state gene expression program and global DNA demethylation. Mechanistically, repression of de novo methylases by PRDM14 drives DNA demethylation at slow kinetics, whereas TET1/TET2-mediated 5hmC conversion enhances both the rate and extent of hypomethylation. These processes thus act synergistically during transition to ground-state pluripotency to promote a robust hypomethylated state. PMID:24371807

Hackett, Jamie A.; Dietmann, Sabine; Murakami, Kazuhiro; Down, Thomas A.; Leitch, Harry G.; Surani, M. Azim

2013-01-01

391

State-selective electron transfer and ionization in collisions of highly charged ions with ground-state Na(3s) and laser-excited Na*(3p)  

NASA Astrophysics Data System (ADS)

Single electron transfer and ionization in collisions of N5+ and Ne8+ with ground state Na(3s) and laser excited Na*(3p) are investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu, which includes the classical orbital velocity of the valence electron. State-selective partial cross sections are obtained using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. A strong dependence of the cross sections on the collision energy is observed. In general, both the relative magnitude and the energy dependence are found to be in good agreement with classical-trajectory Monte Carlo calculations.

Blank, I.; Otranto, S.; Meinema, C.; Olson, R. E.; Hoekstra, R.

2012-02-01

392

ccsd-00002401,version1-30Jul2004 Teleportation of an atomic ensemble quantum state  

E-print Network

ccsd-00002401,version1-30Jul2004 Teleportation of an atomic ensemble quantum state A. Dantan , N to achieve high fidelity quantum state teleportation of a macroscopic atomic ensemble using a pair of quantum [2]. Several continuous variable teleportation experiments with op- tical fields [3] have shown

Paris-Sud XI, Université de

393

Computational model of solid-state, molecular, or atomic media for FDTD simulation based on a  

E-print Network

Computational model of solid-state, molecular, or atomic media for FDTD simulation based on a multi Fermi-Dirac Thermalization, enabling it to treat various solid-state, molecular, or atomic media, "Simple treatment of multi-term dispersion in FDTD," IEEE Microwave Guid. Wave Lett. 7, 121-123 (1997

Ho, Seng-Tiong

394

Collective photon emission from symmetric states created with Rydberg atoms on a ring lattice  

Microsoft Academic Search

We discuss the creation of nonclassical light from collective atomic states that are prepared in a ring-shaped lattice. These states are realized by exploiting the strong interaction between atoms in high-lying energy levels---the so-called Rydberg states---and yield a resource for creating excitations of the electromagnetic field that carry few photons. We characterize the properties of these photonic states showing that

B. Olmos; I. Lesanovsky

2010-01-01

395

Collective photon emission from symmetric states created with Rydberg atoms on a ring lattice  

Microsoft Academic Search

We discuss the creation of nonclassical light from collective atomic states that are prepared in a ring-shaped lattice. These states are realized by exploiting the strong interaction between atoms in high-lying energy levels--the so-called Rydberg states--and yield a resource for creating excitations of the electromagnetic field that carry few photons. We characterize the properties of these photonic states showing that

B. Olmos; I. Lesanovsky

2010-01-01

396

Solvent effects on the absorption and fluorescence spectra of quinine sulphate: Estimation of ground and excited-state dipole moments  

NASA Astrophysics Data System (ADS)

Ground and excited state dipole moments of probe quinine sulphate (QS) was obtained using Solvatochromic shift method. Higher dipole moment is observed for excited state as compared to the ground state which is attributed to the higher polarity of excited state.

Joshi, Sunita; Pant, Debi D.

2012-06-01

397

State-specific heavy-atom effect on intersystem crossing processes in 2-thiothymine: A potential photodynamic therapy photosensitizer  

NASA Astrophysics Data System (ADS)

Thiothymidine has a potential application as a photosensitizer in cancer photodynamic therapy (PDT). As the chromophore of thiothymidine, 2-thiothymine exhibits ultrahigh quantum yield of intersystem crossing to the lowest triplet state T1 (ca. 100%), which contrasts with the excited-state behavior of the natural thymine that dissipates excess electronic energy via ultrafast internal conversion to the ground state. In this work, we employed high-level complete-active space self-consistent field and its second-order perturbation methods to explore the photophysical mechanism of a 2-thiothymine model. We have optimized the minimum energy structures in the low-lying seven electronic states, as well as ten intersection points. On the basis of the computed potential energy profiles and spin-orbit couplings, we proposed three competitive, efficient nonadiabatic pathways to the lowest triplet state T1 from the initially populated singlet state S2. The suggested mechanistic scenario explains well the recent experimental phenomena. The origin responsible for the distinct photophysical behaviors between thymine and 2-thiothymine is ascribed to the heavy-atom effect, which is significantly enhanced in the latter. Additionally, this heavy-atom effect is found to be state-specific, which could in principle be used to tune the photophysics of 2-thiothymine. The present high-level electronic structure calculations also contribute to understand the working mechanism of thiothymidine in PDT.

Cui, Ganglong; Fang, Wei-hai

2013-01-01

398

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

USGS Publications Warehouse

Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were ? 1 µg/L, about 10% exceeded 0 µg/L. At a broad regional scale, arsenic concentrations exceeding 10 µg/L appear to be more frequently observed in the western United States than in the eastern half. Arsenic concentrations in ground water of the Appalachian Highlands and the Atlantic plain generally are very low (? 1 µg/L). Concentrations are somewhat greater in the Interior Plains and the Rocky Mountain System, investigations of ground water in New England, Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin within the last decade suggest that arsenic concentrations exceeding 10 µg/L are more widespread and common than previously recognized. Arsenic release from iron oxide appears to be the most common cause of widespread arsenic concentrations exceeding 10 µg/L a ground water. This can occur in response to different geochemical conditions, including release of arsenic to ground water through reaction of iron oxide with either natural or anthropogenic (i.e., petroleum products) organic carbon. Iron oxide also can release arsenic to alkaline ground water, such as that found in some felsic volcanic rocks and alkaline aquifers of the Western United States. Sulfide minerals are both a source and sink for arsenic. Geothermal water and high evaporation rates also are associated with arsenic concentrations ? 10g/L in ground and surface water, particularly in the west.

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

2000-01-01

399

Emergent structure of multi-dislocation ground states in curved crystals  

E-print Network

We study the structural features and underlying principles of multi-dislocation ground states of a crystalline spherical cap. In the continuum limit where the ratio of crystal size to lattice spacing $W/a$ diverges, dislocations proliferate and ground states approach a characteristic sequence of structures composed of radial grain boundaries ("neutral scars"), extending radially from the boundary and terminating in the bulk. Employing a combination of numerical simulations and asymptotic analysis of continuum elasticity theory, we prove that an energetic hierarchy gives rise to a structural hierarchy, whereby dislocation number and scar number diverge as $a/W \\to 0$ while scar length and dislocation number per scar become {\\it independent} of lattice spacing. We characterize a secondary transition occurring as scar length grows, where the $n$-fold scar symmetry is broken and ground states are characterized by polydisperse, forked-scar morphologies.

Amir Azadi; Gregory M. Grason

2013-12-17

400

Decoherence induced deformation of the ground state in adiabatic quantum computation  

PubMed Central

Despite more than a decade of research on adiabatic quantum computation (AQC), its decoherence properties are still poorly understood. Many theoretical works have suggested that AQC is more robust against decoherence, but a quantitative relation between its performance and the qubits' coherence properties, such as decoherence time, is still lacking. While the thermal excitations are known to be important sources of errors, they are predominantly dependent on temperature but rather insensitive to the qubits' coherence. Less understood is the role of virtual excitations, which can also reduce the ground state probability even at zero temperature. Here, we introduce normalized ground state fidelity as a measure of the decoherence-induced deformation of the ground state due to virtual transitions. We calculate the normalized fidelity perturbatively at finite temperatures and discuss its relation to the qubits' relaxation and dephasing times, as well as its projected scaling properties. PMID:23528821

Deng, Qiang; Averin, Dmitri V.; Amin, Mohammad H.; Smith, Peter

2013-01-01

401

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

402

Ground-state depleted laser in neodymium-doped yttrium orthosilicate  

NASA Astrophysics Data System (ADS)

A ground state depleted (GSD)1,2 laser has been demonstrated in the form of a Q-switched oscillator operating at 912 nm. Using Nd3+ as the active ion and Y2SiO5 as the host material, the laser transition is from the lowest lying stark level of the Nd3+4F3/2 level to a stark level 355 cm-1 above the lowest lying one in the 4I9/2 manifold. The necessity of depleting the ground 4I9/2 manifold is evident for this level scheme as transparency requires a 10% inversion. To achieve the high excitation levels required for the efficient operation of this laser, bleach wave pumping using an alexandrite laser at 745 nm has been employed. The existence of a large absorption feature at 810 nm also allows for the possibility of A1GaAs laser diode pumping. Using KNbO3, noncritical phase matching is possible at 140°C using d32 and has been demonstrated. The results of Q-switched laser performance and harmonic generation in KNbO3 will be presented. Orthosilicate is a monoclinic biaxial crystal. An oriented spectroscopic evaluation consisting of a Judd-Ofelt analysis of oriented absorption spectra and the measurements of oriented emission spectra has been completed and will be presented. Results of modeling using these spectroscopically determined parameters will be compared with the actual laser performance. The performance of this laser at 911 nm which allows accessing Cs atomic resonance filters through harmonic doubling will also be discussed. Orthosilicate can be grown in large boules of excellent optical quality using a Czochralski technique. Because of the relatively small 912 nm emission cross section of 2-3 x 10-20cm2 (orientation dependent) fluences of 10-20 J/cm2 must be circulated in the laser cavity for the efficient extraction of stored energy. This necessitates very aggressive laser damage thresholds. Results from the Reptile laser damage facility at Lawrence Livermore National Laboratory (LLNL) will be presented showing Y2SiO5 bulk and AR sol-gel coated surface damage thresholds of greater than 40 J/cm2 for 10 nsec, 10 Hz, 1.06 ? pulses.

Beach, Raymond J.; Albrecht, George F.; Solarz, Richard W.; Krupke, William F.; Comaskey, Brian J.; Mitchell, Scott C.; Brandle, Charles D.; Berkstresser, George W.

1990-04-01

403

Disordered Quantum Spin Ice Ground State of Tb2Sn2-xTixO7  

NASA Astrophysics Data System (ADS)

Inelastic neutron scattering, AC magnetic susceptibility and ?SR measurements have been performed on polycrystalline solid solutions of the pyrochlore magnet, Tb2Sn2-xTixO7 for seven samples with x between 0 and 2. These measurements probe the crystal field states, low energy spin dynamics and phase behavior to temperatures less than 0.1K. Tb2Ti2O7 is proposed to display a quantum variant of the spin ice ground state, stabilized by virtual excitations between the Tb^3+ crystal field ground state doublet and its low lying excited state doublet. Isostructural, Tb2Sn2O7, displays ``soft'' spin ice order and its Tb^3+ ground and excited crystal field states are known to be interchanged relative to those in Tb2Ti2O7. These measurements of the solid solutions of Tb2Sn2-xTixO7 focus on crystal field excitations between 1meV and 50meV, and show greatly enhanced spin dynamics at low energies for samples with intermediate x. All magnetic order is absent for x>0.1, leaving behind a highly fluctuating, disordered spin ice ground state.

Zhang, Jimin; Gaulin, B. D.; Dahlberg, M. L.; Matthews, M. J.; Bert, F.; Kermarrec, E.; Fritsch, K.; Granroth, G. E.; Jiramongkolchai, P.; Amato, A.; Baines, C.; Cava, R. J.; Mendels, P.; Schiffer, P.

2013-03-01

404

Exact ground state of a frustrated integer-spin modified Shastry-Sutherland model  

NASA Astrophysics Data System (ADS)

We consider a two-dimensional geometrically frustrated integer-spin Heisenberg system that admits an exact ground state. The system corresponds to a decorated square lattice with two coupling constants J1 and J2, and it can be understood as a generalized Shastry-Sutherland model. Main elements of the spin model are suitably coupled antiferromagnetic spin trimers with integer spin quantum numbers s and their ground state ? will be the product state of the local singlet ground states of the trimers. We provide exact numerical data for finite lattices as well as analytical considerations to estimate the range of the existence in dependence on the ratio of the two couplings constants J2 and J1 and on the spin quantum number s. Moreover, we find that the magnetization curves as a function of the applied magnetic field shows plateaus and jumps. In the classical limit s ? ? the model exhibits phases of three- and two-dimensional ground states separated by a one-dimensional (collinear) plateau state at 1/3 of the saturation magnetization.

Richter, J.; Schmidt, H.-J.

2012-06-01

405

Preparing ground states of quantum many-body systems on a quantum computer  

NASA Astrophysics Data System (ADS)

The simulation of quantum many-body systems is a notoriously hard problem in condensed matter physics, but it could easily be handled by a quantum computer [4,1]. There is however one catch: while a quantum computer can naturally implement the dynamics of a quantum system --- i.e. solve Schr"odinger's equation --- there was until now no general method to initialize the computer in a low-energy state of the simulated system. We present a quantum algorithm [5] that can prepare the ground state and thermal states of a quantum many-body system in a time proportional to the square-root of its Hilbert space dimension. This is the same scaling as required by the best known algorithm to prepare the ground state of a classical many-body system on a quantum computer [3,2]. This provides strong evidence that for a quantum computer, preparing the ground state of a quantum system is in the worst case no more difficult than preparing the ground state of a classical system. 1 D. Aharonov and A. Ta-Shma, Adiabatic quantum state generation and statistical zero knowledge, Proc. 35th Annual ACM Symp. on Theo. Comp., (2003), p. 20. F. Barahona, On the computational complexity of ising spin glass models, J. Phys. A. Math. Gen., 15 (1982), p. 3241. C. H. Bennett, E. Bernstein, G. Brassard, and U. Vazirani, Strengths and weaknessess of quantum computing, SIAM J. Comput., 26 (1997), pp. 1510--1523, quant-ph/9701001. S. Lloyd, Universal quantum simulators, Science, 273 (1996), pp. 1073--1078. D. Poulin and P. Wocjan, Preparing ground states of quantum many-body systems on a quantum computer, 2008, arXiv:0809.2705.

Poulin, David

2009-03-01

406

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

E-print Network

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

Okhunov, Abdurahim A; Khandaker, M U; Rosli, Noora B

2014-01-01

407

Model valence-fluctuation systems: variational ground states and magnetic responses  

SciTech Connect

Variational ground-state wavefunctions are presented and optimized for two model valence-fluctuation systems, based on Anderson lattice Hamiltonians in the U ..-->.. infinity limit. Although these wavefunctions are approximate, they are treated in an essentially exact manner. The )f/sup 0/, f/sup 1/; n = 1) system has an intuitively reasonable ground-state susceptibility, while the )f/sup 1/, f/sup 2/; n = 2) system is found to exhibit an insulating gap. Due to their different crystal symmetries, this gap should be realized in SmB/sub 6/ but not in SmS.

Brandow, B.H.

1980-04-01

408

Electronic ground state conformers of ?-carotene and their role in ultrafast spectroscopy  

NASA Astrophysics Data System (ADS)

We present a study of ground state conformations of all-trans ?-carotene using Density Functional Theory (DFT). To reproduce the carotenoid spectrum, the DFT approach was combined with the Multi-Reference Configuration Interaction. Our results show that the global minimum corresponds to an asymmetric structure where the ?-ionone rings are twisted with respect to the polyene chain. The next higher-lying conformer is more s-cis symmetric and is populated at room temperature (30%). We discuss the relation of these conformers to S ? and show that our model readily explains the temperature dependence and the narrowing of the ground state bleach at long population times.

Lukeš, Vladimír; Christensson, Niklas; Milota, Franz; Kauffmann, Harald F.; Hauer, Jürgen

2011-04-01

409

High-fidelity rapid ground-state loading of an ultracold gas into an optical lattice.  

PubMed

A protocol is proposed for the rapid coherent loading of a Bose-Einstein condensate into the ground state of an optical lattice, without residual excitation associated with the breakdown of adiabaticity. The driving potential required to assist the rapid loading is derived using the fast-forward technique, and generates the ground state in any desired short time. We propose an experimentally feasible loading scheme using a bichromatic lattice potential, which approximates the fast-forward driving potential with high fidelity. PMID:25148323

Masuda, Shumpei; Nakamura, Katsuhiro; Del Campo, Adolfo

2014-08-01

410

Ground-state and finite-temperature energetics and topologies of germanium microclusters  

NASA Astrophysics Data System (ADS)

We have investigated the ground-state and finite-temperature properties of Ge microclusters (N=2 to 14) using molecular dynamics (MD) simulation along with the method of steepest-descent quench (SDQ). The interaction potential adopted is the three-body Stillinger-Weber potential as modified by Ding and Andersen for amorphous Ge. Our results indicate that the experimentally observed greater stability of certain cluster sizes can be explained by the topology and energetics of the clusters at finite temperature rather than by the binding energies of the ground-state structures.

Antonio, Giomal A.; Feuston, Bradley P.; Kalia, Rajiv K.; Vashishta, P.

1988-06-01

411

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

E-print Network

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

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

2014-05-28

412

Uniqueness of Ground States for Short-Range Spin Glasses in the Half-Plane  

E-print Network

We consider the Edwards-Anderson Ising spin glass model on the half-plane $Z \\times Z^+$ with zero external field and a wide range of choices, including mean zero Gaussian, for the common distribution of the collection J of i.i.d. nearest neighbor couplings. The infinite-volume joint distribution $K(J,\\alpha)$ of couplings J and ground state pairs $\\alpha$ with periodic (respectively, free) boundary conditions in the horizontal (respectively, vertical) coordinate is shown to exist without need for subsequence limits. Our main result is that for almost every J, the conditional distribution $K(\\alpha|J)$ is supported on a single ground state pair.

Louis-Pierre Arguin; Michael Damron; Charles Newman; Daniel Stein

2009-11-21

413

The Nature of the Ground States of Cobalt(II) and Nickel(II) Carboxypeptidase A  

PubMed Central

The magnetic susceptibilities of cobalt(II) and nickel(II) derivaties of carboxypeptidase A (CPA) follow the Curie law over a wide temperature range. The observed magnetic moments of Co(II)CPA and Ni(II)CPA are 4.77 ± 0.15 and 2.53 ± 0.10 Bohr Magnetons, respectively. The magnetic and spectral properties of Ni(II)CPA are consistent only with an octahedral ground-state geometry, whereas Co(II)CPA has a probable five-coordinate structure. The results establish ordinary metal-ion ground states for two metallocarboxypeptidase A derivatives which exhibit full peptidase activity. PMID:4509646

Rosenberg, Robert C.; Root, Charles A.; Wang, Run-Han; Cerdonio, Massimo; Gray, Harry B.

1973-01-01

414

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

NASA Astrophysics Data System (ADS)

We consider nonlinear Schrödinger equations iu_t +? u +? (|u|^2)u=0 , text{for} (t,x)in mathbb{R}× mathbb{R}^d, where d ? 3 and ? is smooth. We prove that symmetric finite energy solutions close to orbitally stable ground states converge to a sum of a ground state and a dispersive wave as t ? ? assuming the so called the Fermi Golden Rule (FGR) hypothesis. We improve the “sign condition” required in a recent paper by Gang Zhou and I.M.Sigal.

Cuccagna, Scipio; Mizumachi, Tetsu

2008-11-01

415

Ground State Degeneracy in the Levin-Wen Model for Topological Phases  

E-print Network

We study properties of topological phases by calculating the ground state degeneracy (GSD) of the 2d Levin-Wen (LW) model. Here it is explicitly shown that the GSD depends only on the spatial topology of the system. Then we show that the ground state on a sphere is always non-degenerate. Moreover, we study an example associated with a quantum group, and show that the GSD on a torus agrees with that of the doubled Chern-Simons theory, consistent with the conjectured equivalence between the LW model associated with a quantum group and the doubled Chern-Simons theory.

Yuting Hu; Spencer D. Stirling; Yong-Shi Wu

2011-05-29

416

On the ground and some low-lying excited states of ScB: a multiconfigurational study.  

PubMed

The electronic structure of a series of low-lying excited triplet and quintet states of scandium boride (ScB) was examined using multireference configuration interaction (including Davidson's correction for quadruple excitations) and single-reference coupled cluster (CC) methods with averaged natural orbital (ANO) basis sets. The CC approach was used only for the lowest quintet state. The authors have analyzed eight low-lying triplets 3Sigma-(2), 3Sigma+, 3Pi(3), and 3Delta(2) dissociating to Sc(2D)/B(2P) atoms and eight low-lying quintet states 5Sigma-, 5Sigma+, 5Pi(2), 5Phi, and 5Delta(3) dissociating to Sc(4F)/B(2P) atoms. They report the potential energy curves and spectroscopic parameters of ScB obtained with the multireference configuration interaction (MRCI) technique including all singly and doubly excited configurations obtained with the ANO-S basis set. For the two lowest states they obtained also improved ANO-L spectroscopic constants, dipole and quadrupole moments as well as scalar relativistic effects based on the Douglas-Kroll-Hess Hamiltonian. They provide the analysis of the bonding based on Mulliken populations and occupation numbers. Since the two lowest states, 3Sigma- and 5Sigma-, lie energetically very close, their principal goal was to resolve the nature of the ground state of ScB. Their nonrelativistic MRCI(Q) (including Davidson correction) results indicate that the quintet is more stable than the triplet by about 800 cm(-1). Inclusion of scalar relativistic effects reduces this difference to about 240 cm(-1). The dissociation energies for 5Sigma- ScB range from 3.20 to 3.30 eV while those for the 3Sigma- range from 1.70 to 1.80 eV. PMID:17567200

Cernusák, Ivan; Dallos, Michal; Lischka, Hans; Müller, Thomas; Uhlár, Milan

2007-06-01

417

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

PubMed

Absorption and fluorescence spectra of Oil Red O (abbreviated as ORO) are recorded in various solvents with different polarity in the range of 250-900 nm, at room temperature. The solvatochromic shift methods have been used to determine the ground state (?g) and excited state (?e) dipole moments depending on dielectric constant and refractive index functions. It is observed that fluorescence spectra show positive solvatochromism whereas absorption spectra do not indicates sensitive behavior to solvent polarity. Excited state dipole moment is found as higher than those of ground state for all of the used methods and it is attributed to more polar excited state of ORO. Theoretical ?g has been determined by quantum chemical calculations using DFT and semi empirical methods. HOMO, LUMO, molecular electrostatic potential (MEP) and solvent accessible surface of ORO are calculated by using DFT-B3LYP method. PMID:25123946

S?d?r, ?sa; Gülseven S?d?r, Yadigar

2015-01-25

418

Nitrate in Ground Waters of the United States--Assessing the Risk  

USGS Publications Warehouse

Using data compiled by the National Water Quality Assessment Program (NAWQA), the USGS has evaluated the potential for nitrate contamination of ground waters in the United States. Soil-drainage characteristics and the amount of nitrogen contributed by fertilizer, manure, and atmospheric sources were found to markedly influence the concentration of nitrate in ground water. These two characteristics were compiled in a national map that shows patterns of risk for nitrate contamination of ground water. Areas with well-drained soils and high nitrogen input have the highest risk. Ground-water nitrate data generally verified the risk patterns shown on the national map. The verification analysis is based on over 10,000 samples collected through 1992.

Nolan, Bernard T.; Ruddy, Barbara C.

1998-01-01

419

Accurate calculations of the ground state and low-lying excited states of the (RbBa)+ molecular ion: a proposed system for ultracold reactive collisions  

NASA Astrophysics Data System (ADS)

Collisions of ultracold Ba+ ions on a Rb Bose-Einstein condensate have been suggested as a possible benchmark system for ultracold ion-neutral collision experiments. However, a priori knowledge of the possible processes is desirable. For this purpose, we here present high-level four-component coupled cluster and multi-reference configuration interaction calculations of potential energy curves, dipole moments and spectroscopic constants of the experimentally interesting low-lying electronic states of the (RbBa)+ molecule. Our results show significant avoided crossings between the ^3 \\Sigma ^+_{1,0^-} Rb + Ba+ entrance channels and low-lying charge transfer ^3 \\Pi _{1,0^-} states of the Rb+ and Ba_{6\\rm{s}^1 5\\rm{d}^1}(3D) atomic channels, indicating that a fast non-radiative charge transfer is possible. Population analysis shows that a partially covalent polar bond is formed in the ground state, which thus deviates significantly from a pure Rb+ + Ba interaction. This finding is corroborated by the electric dipole moment which is found only to be 4.5 D at the equilibrium bond distance, compared with the 14 D for a pure Rb+ + Ba interaction, thereby supporting the view of a partial charge transfer between the two atoms.

Knecht, S.; Sørensen, L. K.; Jensen, H. J. Aa; Fleig, T.; Marian, C. M.

2010-03-01

420

Symplectic group structure of the Cr48,Ru88, and Pd92 ground states  

NASA Astrophysics Data System (ADS)

The ground states of Cr48,Ru88, and Pd92 are studied in the 1f7/2 or 1g9/2 shell model with effective interactions from the literature. They are found to be composed, quite independently of the shell and the interaction, roughly of 75% of (s,t)=(0,0) and 25% of (s,t)=(4,0), where s is the seniority and t the reduced isospin. Other irreps of the symplectic group Sp (2j+1), where j is the single-nucleon angular momentum, make only very small contributions. The state ? obtained by antisymmetrization and normalization of the ground state in the stretch scheme of Danos and Gillet [M. Danos and V. Gillet, Phys. Rev. 161, 1034 (1967), 10.1103/PhysRev.161.1034] has a very different structure where the Sp (2j+1) irreps other than (s,t)=(0,0) and (4,0) contribute 20% and 41% for j =7/2 and 9/2, respectively. The contributions of ? and the s =0 state to the calculated states are about equal for Cr48. For Ru88 and Pd92 the s =0 state is unambigously a better approximation to the calculated states than ?. A state ?' obtained by antisymmetrization and normalization of the product of two stretch-scheme ground states of the system with two valence nucleons or nucleon holes of each type has much larger overlaps with the calculated ground states than ? but a deviating Sp (2j+1) decomposition.

Neergârd, K.

2014-07-01

421

Reactive ground-state pathways are not ubiquitous in red/green cyanobacteriochromes.  

PubMed

Recent characterization of the red/green cyanobacteriochrome (CBCR) NpR6012g4 revealed a high quantum yield for its forward photoreaction [J. Am. Chem. Soc. 2012, 134, 130-133] that was ascribed to the activity of hidden, productive ground-state intermediates. The dynamics of the pathways involving these ground-state intermediates was resolved with femtosecond dispersed pump-dump-probe spectroscopy, the first such study reported for any CBCR. To address the ubiquity of such second-chance initiation dynamics (SCID) in CBCRs, we examined the closely related red/green CBCR NpF2164g6 from Nostoc punctiforme. Both NpF2164g6 and NpR6012g4 use phycocyanobilin as the chromophore precursor and exhibit similar excited-state dynamics. However, NpF2164g6 exhibits a lower quantum yield of 32% for the generation of the isomerized Lumi-R primary photoproduct, compared to 40% for NpR6012g4. This difference arises from significantly different ground-state dynamics between the two proteins, with the SCID mechanism deactivated in NpF2164g6. We present an integrated inhomogeneous target model that self-consistently fits the pump-probe and pump-dump-probe signals for both forward and reverse photoreactions in both proteins. This work demonstrates that reactive ground-state intermediates are not ubiquitous phenomena in CBCRs. PMID:23725062

Chang, Che-Wei; Gottlieb, Sean M; Kim, Peter W; Rockwell, Nathan C; Lagarias, J Clark; Larsen, Delmar S

2013-09-26

422

A projection gradient method for computing ground state of spin-2 Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

In this paper, a projection gradient method is presented for computing ground state of spin-2 Bose-Einstein condensates (BEC). We first propose the general projection gradient method for solving energy functional minimization problem under multiple constraints, in which the energy functional takes real functions as independent variables. We next extend the method to solve a similar problem, where the energy functional now takes complex functions as independent variables. We finally employ the method into finding the ground state of spin-2 BEC. The key of our method is: by constructing continuous gradient flows (CGFs), the ground state of spin-2 BEC can be computed as the steady state solution of such CGFs. We discretized the CGFs by a conservative finite difference method along with a proper way to deal with the nonlinear terms. We show that the numerical discretization is normalization and magnetization conservative and energy diminishing. Numerical results of the ground state and their energy of spin-2 BEC are reported to demonstrate the effectiveness of the numerical method.

Wang, Hanquan

2014-10-01

423

Efficient numerical methods for computing ground states of spin-1 Bose–Einstein condensates based on their characterizations  

SciTech Connect

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

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

2013-11-15

424

Bose-Einstein Condensation of Yb atoms  

SciTech Connect

We could recently achieve the Bose Einstein condensation (BEC) of Yb atoms. Yb differs from most of the elements that have previously been condensed, because it is a two-electron atom with the singlet S ground state. Furthermore the Bosonic isotopes of Yb, like 174Yb which we succeeded to condensate, has no nuclear spin, so that the ground state is completely spin-less state and hence insensitive to magnetic fields. Thus a new type of atom could join the group of atoms for BEC studies. We would like to report how we could achieve the BEC of Yb atoms.

Takasu, Y.; Maki, K.; Komori, K.; Takano, T.; Honda, K.; Kumakura, M.; Yabuzaki, T.; Takahashi, Y. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

2005-05-05

425

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

PubMed Central

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

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

2014-01-01

426

First measurement of the partial widths of $^{209}$Bi decay to the ground and to the first excited states  

E-print Network

$^{209}$Bi alpha decay to the ground and to the first excited state have been contemporary observed for the first time with a large BGO scintillating bolometer. The half-life of $^{209}$Bi is determined to be $\\tau_{1/2}$=(2.01$\\pm$0.08)$\\cdot10^{19}$ years while the branching ratio for the ground-state to ground-state transition is (98.8$\\pm$0.3)%.

J. W. Beeman; M. Biassoni; C. Brofferio; C. Bucci; S. Capelli; L. Cardani; M. Carrettoni; M. Clemenza; O. Cremonesi; E. Ferri; A. Giachero; L. Gironi; P. Gorla; C. Gotti; C. Maiano; A. Nucciotti; L. Pattavina; M. Pavan; G. Pessina; S. Pirro; E. Previtali; M. Sisti; L. Zanotti

2011-10-14

427

Generation and application of a controllable multi-atom entangled state  

NASA Astrophysics Data System (ADS)

In this paper, we present a scheme to prepare a set of the multi-atom entangled states by the cavity quantum electrodynamics (QED) technology. The multi-atom entangled states have some particular entanglement properties. For example, the remaining reduced density matrices ?ij still retain entanglement or disentanglement when any N-2 atoms of the N atoms are traced out, which can be chosen freely according to our need and the relative entanglement strength of any pair of atoms (measured by the concurrence) can be arbitrarily adjusted. In addition, they may be completely symmetric under the exchange of any two atoms and perform certain quantum information tasks, such as telecloning, teleportation, secret sharing and so on.

Huang, Yan-Xia; Zhan, Ming-Sheng

2004-12-01

428

Ground state and low excitations of an integrable chain with alternating spins  

E-print Network

An anisotropic integrable spin chain, consisting of spins $s=1$ and $s=\\frac{1}{2}$, is investigated \\cite{devega}. It is characterized by two real parameters $\\bar{c}$ and $\\tilde{c}$, the coupling constants of the spin interactions. For the case $\\bar{c}<0$ and $\\tilde{c}<0$ the ground state configuration is obtained by means of thermodynamic Bethe ansatz. Furthermore the low excitations are calculated. It turns out, that apart from free magnon states being the holes in the ground state rapidity distribution, there exist bound states given by special string solutions of Bethe ansatz equations (BAE) in analogy to \\cite{babelon}. The dispersion law of these excitations is calculated numerically.

St. Meissner; B. -D. Doerfel

1996-05-07

429

Ground state and low excitations of an integrable chain with alternating spins  

NASA Astrophysics Data System (ADS)

An anisotropic integrable spin chain, consisting of spins s = 1 and 0305-4470/29/9/010/img1, is investigated [1]. It is characterized by two real parameters 0305-4470/29/9/010/img2 and 0305-4470/29/9/010/img3, the coupling constants of the spin interactions. For the case 0305-4470/29/9/010/img4 and 0305-4470/29/9/010/img5 the ground-state configuration is obtained by means of thermodynamic Bethe ansatz. Furthermore, the low excitations are calculated. It turns out that apart from free magnon states being the holes in the ground-state rapidity distribution, there exist bound states given by special string solutions of Bethe ansatz equations (BAE) in analogy to [13]. The dispersion law of these excitations is calculated numerically.

Meiß ner, St.; Dörfel, B.-D.

1996-05-01

430

Analytic approach to the ground-state energy of charged anyon gases  

Microsoft Academic Search

We derive an approximate analytic formula for the ground-state energy of the charged anyon gas. Our approach is based on the harmonically confined two-dimensional (2D) Coulomb anyon gas and a regularization procedure for vanishing confinement. To take into account the fractional statistics and Coulomb interaction we introduce a function, which depends on both the statistics and density parameters ( nu

B. Abdullaev; U. Rössler; M. Musakhanov

2007-01-01

431

Anharmonic Ground state selection in the pyrochlore antiferromagnet and C. L. Henley  

E-print Network

Anharmonic Ground state selection in the pyrochlore antiferromagnet U. Hizi and C. L. Henley: January 22, 2009) In the pyrochlore lattice Heisenberg antiferromagnet, for large spin length S, and discuss why it (as well as the kagom�e lattice) behave differently than the pyrochlore at anharmonic

Henley, Christopher L.

432

Ground States of the Classical Antiferromagnet on the Pyrochlore Lattice Matthew F. Lapa1,2  

E-print Network

Ground States of the Classical Antiferromagnet on the Pyrochlore Lattice Matthew F. Lapa1 on the Pyrochlore lattice, a non-Bravais lattice made of corner-sharing tetrahedra. In particular, we map out neighbor interactions on the Pyrochlore lattice. In this region of parameter space we again find

Henley, Christopher L.

433

Ground state properties of a fully frustrated quantum spin system Elliott H. Lieb and Peter Schupp  

E-print Network

of the quantum Heisenberg antiferromagnet on the geometrically frus­ trated pyrochlore checkerboard lattice, the pyrochlore lattice, which consists of tetrahe­ dra that share sites, was identified as a lattice on which sytems. The ground state and low energy properties of the classical pyrochlore antiferromagnet -- whose

434

Distribution of Elevated Nitrate Concentrations in Ground Water in Washington State  

USGS Publications Warehouse

More than 60 percent of the population of Washington State uses ground water for their drinking and cooking needs. Nitrate concentrations in ground water are elevated in parts of the State as a result of various land-use practices, including fertilizer application, dairy operations and ranching, and septic-system use. Shallow wells generally are more vulnerable to nitrate contamination than deeper wells (Williamson and others, 1998; Ebbert and others, 2000). In order to protect public health, the Washington State Department of Health requires that public water systems regularly measure nitrate in their wells. Public water systems serving more than 25 people collect water samples at least annually; systems serving from 2 to 14 people collect water samples at least every 3 years. Private well owners serving one residence may be required to sample when the well is first drilled, but are unregulated after that. As a result, limited information is available to citizens and public health officials about potential exposure to elevated nitrate concentrations for people whose primary drinking-water sources are private wells. The U.S. Geological Survey and Washington State Department of Health collaborated to examine water-quality data from public water systems and develop models that calculate the probability of detecting elevated nitrate concentrations in ground water. Maps were then developed to estimate ground water vulnerability to nitrate in areas where limited data are available.

Frans, Lonna

2008-01-01

435

sition from a localized solvent-bound ground state to the continuum of the solvent conduc-  

E-print Network

sition from a localized solvent-bound ground state to the continuum of the solvent conduc- tion of the free es . Although the spectra are similar, the stark contrast between the differ- ence signals species account for es in the immediate and solvent-separated contact pairs. The ET reaction being

Kuhl, Tonya L.

436

[4Fe4S]2+ Clusters Exhibit Ground-State Paramagnetism  

PubMed Central

Two proteins involved in nitrogen fixation contain ferredoxin-type [4Fe4S] clusters that exist in paramagnetic ground state upon oxidation, a property never observed since the discovery of ferredoxins 50 years ago. This unique characteristic suggests a specific coupling in these clusters necessary for nitrogen fixation and implies an evolutionary connection between the clusters in the two proteins. PMID:21488637

Rupnik, Kresimir; Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W.; Hales, Brian J.

2011-01-01

437

Ground states of two-dimensional polyampholytes Eilon Brenner and Yacov Kantor  

E-print Network

sequences up to a polymer length N 18. We find that the ground state of the neutral ensemble is compact fluctuations along the chain induce a net attractive interaction between segments of the chain, leading-range attraction interaction 14 . The application of the Debye-Hu¨ckel theory requires the strict neutrality

Kantor, Yacov

438

Ground-State Energy of the Electron Liquid in Ultrathin Wires Michael M. Fogler  

E-print Network

Ground-State Energy of the Electron Liquid in Ultrathin Wires Michael M. Fogler Department liquid in a thin one- dimensional wire are computed. The calculation is based on an approximate mapping.22.­f Recently much attention has been devoted to a class of one-dimensional (1D) conductors that can

Fogler, Michael

439

A Simple Volcano Potential with an Analytic, Zero-Energy, Ground State  

E-print Network

We describe a simple volcano potential, which is supersymmetric and has an analytic, zero-energy, ground state. (The KK modes are also analytic.) It is an interior harmonic oscillator potential properly matched to an exterior angular momentum-like tail. Special cases are given to elucidate the physics, which may be intuitively useful in studies of higher-dimensional gravity.

Michael Martin Nieto

2000-05-30

440

Ground state of two-dimensional Yukawa bosons: Applications to vortex melting  

SciTech Connect

Using variational and diffusion Monte Carlo techniques, we investigate the ground state of bosons interacting in the continuum through a repulsive modified-Bessel-function potential, [epsilon][ital K][sub 0]([ital r]/[sigma]), in two dimensions. This is a simplified model for flux lines in high-[ital T][sub [ital c

Magro, W.R.; Ceperley, D.M. (National Center for Supercomputing Applications and Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States))

1993-07-01

441

Managing United States Public Lands in Response to Climate Change: A View From the Ground Up  

E-print Network

Managing United States Public Lands in Response to Climate Change: A View From the Ground Up on public lands. Though climate change is now well recognized by federal agencies and their local land and resource managers, it is not yet clear how issues related to climate change will be incorporated into on

Neff, Jason

442

Spatially non-uniform ground state and quantized vortices in a two-component  

E-print Network

of Cambridge, Wilberforce Road, Cambridge, CB3 WA0, United Kingdom. A gas of magnons in magnetic films differsSpatially non-uniform ground state and quantized vortices in a two-component Bose these defects as quantized vortices. B ose-Einstein condensation (BEC), predicted by Einstein1 in 1925, is one

Demokritov, S.O.

443

Numerical studies of the ground state of strongly correlated electron systems  

Microsoft Academic Search

The ground state of two-dimensional CuO2 models, a class of strongly correlated electron systems, is studied to extract a pairing mechanism for high-Tc superconductivity. Detailed examinations are made on how and in what situation an attractive interaction between two doped holes arises.

Hiroyuki Shiba; Masao Ogata

1988-01-01

444

Exact ground state of strongly correlated electron systems from symmetry-entangled wave-functions  

NASA Astrophysics Data System (ADS)

The four-site Hubbard model is considered from the exact diagonalisation and variational method points of view. It is shown that the exact ground-state can be recovered by a symmetry projected Slater determinant, irrespective of the interaction strength. This is in contrast to the Gutzwiller wave-function, which is calculated as well.

Leprévost, Alexandre; Juillet, Olivier; Frésard, Raymond

2014-10-01

445

Ground state of the asymmetric Rabi model in the ultrastrong coupling regime  

NASA Astrophysics Data System (ADS)

We study the ground states of the single- and two-qubit asymmetric Rabi models, in which the qubit-oscillator coupling strengths for the counterrotating-wave and corotating-wave interactions are unequal. We take the transformation method to obtain the approximately analytical ground states for both models and numerically verify its validity for a wide range of parameters under the near-resonance condition. We find that the ground-state energy in either the single- or two-qubit asymmetric Rabi model has an approximately quadratic dependence on the coupling strengths stemming from different contributions of the counterrotating-wave and corotating-wave interactions. For both models, we show that the ground-state energy is mainly contributed by the counterrotating-wave interaction. Interestingly, for the two-qubit asymmetric Rabi model, we find that, with the increase in the coupling strength in the counterrotating-wave or corotating-wave interaction, the two-qubit entanglement first reaches its maximum and then drops to zero. Furthermore, the maximum of the two-qubit entanglement in the two-qubit asymmetric Rabi model can be much larger than that in the two-qubit symmetric Rabi model.

Shen, Li-Tuo; Yang, Zhen-Biao; Lu, Mei; Chen, Rong-Xin; Wu, Huai-Zhi

2014-10-01

446

Ground and Excited State Intramolecular Proton Transfer in Salicylic Acid: an Ab Initio Electronic Structure Investigation  

E-print Network

emission in the fluorescence spectrum of salicylic acid and methyl salicylate and attributedGround and Excited State Intramolecular Proton Transfer in Salicylic Acid: an Ab Initio Electronic in salicylic acid have been studied by ab initio molecular orbital calculations using the 6-31G** basis set

Chowdhury, Arindam

447

Ground State D, Dissociation Energy from the Near-dissociation Behaviorof Rotational Level Spacings1  

E-print Network

near-dissociation behavior of the rotational constants BI.,Dl.,Hi,,... etc., to the asymptoticallyGround State D, Dissociation Energy from the Near-dissociation Behaviorof Rotational Level Spacings the dissociation energy of a diatomic molecule from the rotational term value(s) of a single vibrational level

Le Roy, Robert J.

448

A fast algorithm for approximating the ground state energy on a quantum computer Anargyros Papageorgiou,1,  

E-print Network

, Columbia University, New York, NY 10027, USA. (Dated: May 11, 2011) Estimating the ground state energy of a multiparticle system with relative error using deter- ministic classical algorithms has cost that grows algorithm that achieves relative error using a number of qubits C d log -1 with total cost (number

449

The ground state problem for a quantum Hamiltonian model describing friction  

E-print Network

The ground state problem for a quantum Hamiltonian model describing friction Laurent Bruneau friction introduced in [4]. This model consists of a particle which interacts with a bosonic reservoir is violated in the case of linear friction, but satis#28;ed when the friction force is proportional

450

Singlet ground states of the bilinear-biquadratic exchange Hamiltonian with reflection symmetry  

NASA Astrophysics Data System (ADS)

We apply the Lieb-Schupp method to the isotropic spin-S Hamiltonian with bilinear (-J/S2) and biquadratic (-J'/S4) exchange interactions on finite lattices with reflection-symmetry to prove that finite volume ground states of the models are spin singlet in the parameter region J' >= 2S2J, J' >= 0.

Tanaka, Kengo

2011-09-01

451

Cloud-to-Ground Lightning Activity in the Contiguous United States from 1995 to 1999  

Microsoft Academic Search

The spatial and temporal distributions of cloud-to-ground lightning are examined over the contiguous United States from 1995 to 1999 usin