Monotonicity of quantum ground state energies: Bosonic atoms and stars
Michael K. -H. Kiessling
2010-01-24
The N-dependence of the non-relativistic bosonic ground state energy is studied for quantum N-body systems with either Coulomb or Newton interactions. The Coulomb systems are "bosonic atoms," with their nucleus fixed, and the Newton systems are "bosonic stars". In either case there exists some third order polynomial in N such that the ratio of the ground state energy to the respective polynomial grows monotonically in N. Some applications of these new monotonicity results are discussed.
Ground State Hyperfine Structure of Muonic Helium Atom
A. A. Krutov; A. P. Martynenko
2008-07-21
On the basis of the perturbation theory in the fine structure constant $\\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\\mu e ^4_2He)$. We obtain total result for the ground state hyperfine splitting $\\Delta \
Monotonicity of quantum ground state energies: Bosonic atoms and stars
Kiessling, Michael K -H
2010-01-01
The N-dependence of the non-relativistic bosonic ground state energy is studied for quantum N-body systems with either Coulomb or Newton interactions. The Coulomb systems are "bosonic atoms," with their nucleus fixed, and the Newton systems are "bosonic stars". In either case there exists some third order polynomial in N such that the ratio of the ground state energy to the respective polynomial grows monotonically in N. Some applications of these new monotonicity results are discussed.
Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms
Zare, Richard N.
Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms from HCl,,v=2,J=1... photodissociation Dimitris Sofikitis Institute of Electronic Structure and Laser, Foundation of Research 2208, 71003 Voutes-Heraklion, Greece Luis Rubio-Lago Institute of Electronic Structure and Laser
All-optical reconstruction of atomic ground-state population
London, P.; Firstenberg, O.; Shuker, M.; Ron, A.
2010-04-15
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.
Photoabsorption by ground-state alkali-metal atoms.
NASA Technical Reports Server (NTRS)
Weisheit, J. C.
1972-01-01
Principal-series oscillator strengths and ground-state photoionization cross sections are computed for sodium, potassium, rubidium, and cesium. The degree of polarization of the photoelectrons is also predicted for each atom. The core-polarization correction to the dipole transition moment is included in all of the calculations, and the spin-orbit perturbation of valence-p-electron orbitals is included in the calculations of the Rb and Cs oscillator strengths and of all the photoionization cross sections. The results are compared with recent measurements.
Version 2.0 Ground state wave function and energy of the lithium atom
Pachucki, Krzysztof
Version 2.0 Ground state wave function and energy of the lithium atom Mariusz Puchalski Abstract Highly accurate nonrelativistic groundÂstate wave function and energy of the lithium atom# 6 corrections has been obtained for few low lying states of helium only [2, 3], not for lithium nor
Huennekens, John
Thermalization of fast cesium 5D3/2 atoms in collisions with ground-state cesium atoms A. Marks,1 A atoms. Photodissociation of Cs2 molecules into ground- and excited-state cesium atoms has been observed + is the ground state of the cesium molecule and Cs2 * represents an excited state or states that can be reached
Rabi flopping 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; M. Saffman
2007-11-02
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.
Interactions Between Ground-State Nitrogen Atoms and Molecules
NASA Technical Reports Server (NTRS)
Vanderslice, Joseph T.; Mason, Edward A.; Lippincott, Ellis R.
1959-01-01
Potential-energy curves for nitrogen atom (N-N) interactions corresponding to the X (1)Sigma(sup +, sub g), A (3)Sigma(sup +, sub u), (5)Sigma(sup +, sub g), (7)Sigma(sup +, sub u), B (3) Pi(sub g), C (3)(Pi(su u)and a (1)Pi(sub g) states of the nitrogen molecule N2 as well as curves for the atom-molecules (N-N2) and molecule-molecule (N2-N2) interactions have been calculated. All calculations have been based as nearly as possible on experimental data, including spectroscopically determined vibrational energy levels, scattering cross sections of atomic beams in gases, and measured vibrational relaxation times. In cases where experimental data were not available, approximate quantum-mechanical calculations have been made. Results obtained by these various methods are remarkably consistent with one another and are believed to have good accuracy.
Ground-State Entanglement Properties of Helium Atom in a Finite Spherical Cavity
NASA Astrophysics Data System (ADS)
Ko?cik, Przemys?aw; Saha, Jayanta K.
2015-10-01
The effects of the spatial confinement on the ground-state entanglement properties of the helium atom have been studied. The finite oscillator potential is used to represent the confining potential. The transition to the free atom regime and the harmonic confinement regime are discussed in detail in dependence of the control parameters of the system.
The role of correlation in the ground state energy of confined helium atom
Aquino, N.
2014-01-14
We analyze the ground state energy of helium atom confined by spherical impenetrable walls, and the role of the correlation energy in the total energy. The confinement of an atom in a cavity is one way in which we can model the effect of the external pressure on an atom. The calculations of energy of the system are carried out by the variational method. We find that the correlation energy remains almost constant for a range values of size of the boxes analyzed.
Derevianko, Andrei
2015-01-01
Spherically-symmetric ground states of alkali-metal atoms do not posses electric quadrupole moments. However, the hyperfine interaction between nuclear moments and atomic electrons distorts the spherical symmetry of electronic clouds and leads to non-vanishing atomic quadrupole moments. We evaluate these hyperfine-induced quadrupole moments using techniques of relativistic many-body theory and compile results for Li, Na, K, Rb, and Cs atoms. For heavy atoms we find that the hyperfine-induced quadrupole moments are strongly (two orders of magnitude) enhanced by correlation effects. We further apply the results of the calculation to microwave atomic clocks where the coupling of atomic quadrupole moments to gradients of electric fields leads to clock frequency uncertainties. We show that for $^{133}$Cs atomic clocks, the spatial gradients of electric fields must be smaller than $30 \\, \\mathrm{V}/\\mathrm{cm}^2$ to guarantee fractional inaccuracies below $10^{-16}$.
Is the electron stationary in the ground state of the Dirac hydrogen atom in Bohm's Theory?
B. J. Hiley
2014-12-18
We show that, in the relativistic Bohm model of a Dirac-like particle, the electron in the ground state of the hydrogen atom is moving, unlike the prediction for the case of a Schr\\"{o}dinger-like particle, where the electron is stationary. This accounts for the empirically observed dilation of the decay time of the muon in the ground state of muonium.
Spin exchange upon collision of two cesium atoms in the ground state
NASA Astrophysics Data System (ADS)
Dmitriev, S. P.; Dovator, N. A.; Kartoshkin, V. A.
2015-06-01
The spin exchange cross sections and the magnetic resonance frequency shift upon collision of two cesium atoms in the ground state are calculated. The calculations are carried out on the basis of the interaction potentials for the singlet ( X -1?+) and triplet ( a 3?+) states of the Cs2 dimer, reported in the literature in recent years. The results are compared with earlier data.
Parniak, Micha?; Wasilewski, Wojciech
2015-01-01
We demonstrate an interface between light coupled to transition between excited states of rubidium and long-lived ground-state atomic coherence. In our proof-of-principle experiment a non-linear process of four-wave mixing in an open-loop configuration is used to achieve light emission proportional to independently prepared ground-state atomic coherence. We demonstrate strong correlations between Raman light heralding generation of ground-state coherence and the new four-wave mixing signal. Dependance of the efficiency of the process on laser detunings is studied.
Zare, Richard N.
Comparison of near-threshold reactivity of ground-state and spin-orbit excited chlorine atoms of methane with atomic chlorine is initiated by photolysis of BrCl. Near 420 nm, the resulting mixture of ground- and excited-state chlorine atoms have spatial anisotropies of phot 0.7 for the Cl(2 P3/2) Br
The Ground State Energy of Relativistic One-Electron Atoms According to Jansen and He
1 The Ground State Energy of Relativistic One-Electron Atoms According to Jansen and He#25; Raymond of Dou- glas and Kroll { have derived a (pseudo-)relativistic energy expres- sion which is very that their energy in the one-particle Coulomb case, and thus the resulting self-adjoint Hamiltonian and its spectrum
Loading Bose-Einstein-condensed atoms into the ground state of an optical lattice P. S. Julienne,1
Band, Yehuda B.
Loading Bose-Einstein-condensed atoms into the ground state of an optical lattice P. S. Julienne,1-on function S t so as to load a Bose-Einstein condensate into the ground state of the optical lattice of depth with an optimal turn-on function S t that the ground state of the optical lattice can be loaded
Simulation of the ground states of spin rings with cavity-assisted neutral atoms.
Xue, Peng; Zhan, Xiang; Bian, Zhihao
2015-01-01
Quantum phase transitions occur when the ground state of a Hamiltonian undergoes qualitative changes with a control parameter changing. In this paper we consider a particular system--an Isng-type spin ring with competing many-body interactions. Depending on the relative strength interactions, the ground state of the system is either a product state or entangled state. We implement the system in a cavity-assisted neutral atomic simulator and study the non-locality and entanglement of the simulated ground state of an Ising-type three-spin ring with the control parameter changing. The simplicity of the setup and its robustness to noise give it a great practicality within the framework of current experimental technology. PMID:25557504
Quantum ground state of self-organized atomic crystals in optical resonators
Fernandez-Vidal, Sonia; De Chiara, Gabriele; Larson, Jonas; Morigi, Giovanna
2010-04-15
Cold atoms, driven by a laser and simultaneously coupled to the quantum field of an optical resonator, may self-organize in periodic structures. These structures are supported by the optical lattice, which emerges from the laser light they scatter into the cavity mode and form when the laser intensity exceeds a threshold value. We study theoretically the quantum ground state of these structures above the pump threshold of self-organization by mapping the atomic dynamics of the self-organized crystal to a Bose-Hubbard model. We find that the quantum ground state of the self-organized structure can be the one of a Mott insulator, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity-field intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the phase is compressible. These states could be realized in existing experimental setups.
The quantum ground state of self-organized atomic crystals in optical resonators
Sonia Fernández-Vidal; Gabriele De Chiara; Jonas Larson; Giovanna Morigi
2010-01-26
Cold atoms, driven by a laser and simultaneously coupled to the quantum field of an optical resonator, can self-organize in periodic structures. These structures are supported by the optical lattice, which emerges from the laser light they scatter into the cavity mode, and form when the laser intensity exceeds a threshold value. We study theoretically the quantum ground state of these structures above the pump threshold of self-organization, by mapping the atomic dynamics of the self-organized crystal to a Bose-Hubbard model. We find that the quantum ground state of the self-organized structure can be the one of a Mott-insulator or a superfluid, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the system is superfluid. These states could be realized in existing experimental setups.
NASA Astrophysics Data System (ADS)
Lackner, Klaus S.; Zweig, George
1987-09-01
The arguments presented in the Comment by Liebman and Huheey are shown to be incorrect. The operational equivalence of Mulliken ground-state electronegativities and Pauling electronegativities is demonstrated for neutral atoms. It is shown that ground-state electronegativities and valence-state electronegativities for both neutral atoms and ions are also operationally equivalent. A single electronegativity scale based on Mulliken ground-state electronegativities may therefore be used for neutral atoms, ions, and fractionally charged atoms, as originally implied in the paper by Lackner and Zweig.
Learning Approach on the Ground State Energy Calculation of Helium Atom
Shah, Syed Naseem Hussain
2010-07-28
This research investigated the role of learning approach on the ground state energy calculation of Helium atom in improving the concepts of science teachers at university level. As the exact solution of several particles is not possible here we used approximation methods. Using this method one can understand easily the calculation of ground state energy of any given function. Variation Method is one of the most useful approximation methods in estimating the energy eigen values of the ground state and the first few excited states of a system, which we only have a qualitative idea about the wave function.The objective of this approach is to introduce and involve university teacher in new research, to improve their class room practices and to enable teachers to foster critical thinking in students.
Measurements of the ground-state polarizabilities of Cs, Rb, and K using atom interferometry
NASA Astrophysics Data System (ADS)
Gregoire, Maxwell D.; Hromada, Ivan; Holmgren, William F.; Trubko, Raisa; Cronin, Alexander D.
2015-11-01
We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms using a three-nanograting Mach-Zehnder atom beam interferometer. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity-nonconservation experiments. We measured ?Cs=4 ? ?0×59.39 (9 ) Å3,?Rb=4 ? ?0×47.39 (8 ) Å3 , and ?K=4 ? ?0×42.93 (7 ) Å3 . In atomic units, these measurements are ?Cs=401.2 (7 ) ,?Rb=320.1 (6 ) , and ?K=290.0 (5 ) . We report ratios of polarizabilities ?Cs/?Rb=1.2532 (10 ) ,?Cs/?K=1.3834 (9 ) , and ?Rb/?K=1.1040 (9 ) with smaller fractional uncertainty because the systematic errors for individual measurements are largely correlated. Since Cs atom beams have short de Broglie wavelengths, we developed measurement methods that do not require resolved atom diffraction. Specifically, we used phase choppers to measure atomic beam velocity distributions, and we used electric field gradients to give the atom interference pattern a phase shift that depends on atomic polarizability.
Vibrational ground state cooling of a neutral atom in a tightly focused optical dipole trap
NASA Astrophysics Data System (ADS)
Aljunid, Syed; Maslennikov, Gleb; Paesold, Martin; Durak, Kadir; Leong, Victor; Kurtsiefer, Christian
2012-06-01
Recent experiments have shown that an efficient interaction between a single trapped atom and light can be established by concentrating light field at the location of the atom by focusing [1-3]. However, to fully exploit the benefits of strong focusing one has to localize the atom at the maximum of the field strength [4]. The position uncertainty due to residual kinetic energy of the atom in the dipole trap (depth ˜1mK) after molasses cooling is significant (few 100 nm). It limits the interaction between a focused light mode and an atom already for moderate focusing strength [2]. To address this problem we implement a Raman Sideband cooling technique, similar to the one commonly used in ion traps [5], to cool a single ^87Rb atom to the ground state of the trap. We have cooled the atom along the transverse trap axis (trap frequency ??=55,), to a mean vibrational state n?=0.55 and investigate the impact on atom-light interfaces.[4pt] [1] M. K. Tey, et al., Nature Physics 4 924 (2008)[0pt] [2] M. K. Tey et. al., New J. Phys. 11, 043011 (2009)[0pt] [3] S.A. Aljunid et al., PRL 103, 153601 (2009)[0pt] [4] C. Teo and V. Scarani Opt. Comm. 284 4485-4490 (2011)[0pt] [5] C. Monroe et al., PRL 75, 4011 (1995)
NASA Technical Reports Server (NTRS)
Drachman, Richard J.
2006-01-01
Formation of triplet positron-helium bound state by stripping of positronium atoms in collision with ground state helium JOSEPH DI RlENZI, College of Notre Dame of Maryland, RICHARD J. DRACHMAN, NASA/Goddard Space Flight Center - The system consisting of a positron and a helium atom in the triplet state e(+)He(S-3)(sup e) was conjectured long ago to be stable [1]. Its stability has recently been established rigorously [2], and the values of the energies of dissociation into the ground states of Ps and He(+) have also been reported [3] and [4]. We have evaluated the cross-section for this system formed by radiative attachment of a positron in triplet He state and found it to be small [5]. The mechanism of production suggested here should result in a larger cross-section (of atomic size) which we are determining using the Born approximation with simplified initial and final wave functions.
Cold collisions of ground-state calcium atoms in a laser field: A theoretical study
Bussery-Honvault, Beatrice; Launay, Jean-Michel; Moszynski, Robert
2003-09-01
State-of-the-art ab initio techniques have been applied to compute the potential-energy curves for the ground X {sup 1}{sigma}{sub g}{sup +} and excited {sup 1}{pi}{sub g}(4s3d) states of the calcium dimer in the Born-Oppenheimer approximation. The weakly bound ground state was calculated by symmetry-adapted perturbation theory, while the strongly bound excited state was computed using a combination of the linear-response theory within the coupled-cluster singles and doubles framework for the core-valence electronic correlation and of the full configuration interaction for the valence-valence correlation. The ground-state potential has been corrected by considering the relativistic terms resulting from the first-order many-electron Breit theory, and the retardation corrections. The magnetic electronic transition dipole moment governing the {sup 1}{pi}{sub g}(leftarrow){sup 1}{sigma}{sub g}{sup +} transitions has been obtained as the first residue of the polarization propagator computed with the coupled-cluster method restricted to single and double excitations. The computed energies and transition moments have been analytically fitted and used in the dynamical calculations of the rovibrational energy levels, ground-state scattering length, photoassociation intensities at ultralow temperatures, and spontaneous emission coefficients from the {sup 1}{pi}{sub g}(4s3d) to the X {sup 1}{sigma}{sub g}{sup +} state. The spectroscopic constants of the theoretical ground-state potential are in a good agreement with the experimental values derived from the Fourier-transform spectra [O. Allard et al., Eur. Phys. J. D (to be published)]. The theoretical s-wave scattering length for the ground state is a=44 bohrs, suggesting that it should be possible to obtain a stable Bose-Einstein condensate of calcium atoms. Finally, the computed photoassociation intensities and spontaneous emission coefficients suggest that it should be possible to obtain cold calcium molecules by photoassociation of cold atoms to the first {sup 1}{pi}{sub g} state followed by a spontaneous emission to the ground state.
ERIC Educational Resources Information Center
Harbola, Varun
2011-01-01
In this paper, we accurately estimate the ground-state energy and the atomic radius of the helium atom and a helium-like Hookean atom by employing the uncertainty principle in conjunction with the variational approach. We show that with the use of the uncertainty principle, electrons are found to be spread over a radial region, giving an electron…
Measurements of the Ground-State Polarizabilities of Cs, Rb, and K using Atom Interferometry
Gregoire, Maxwell D; Holmgren, William F; Trubko, Raisa; Cronin, Alexander D
2015-01-01
We measured the ground-state static electric-dipole polarizabilities of Cs, Rb, and K atoms using a three-nanograting Mach-Zehnder atom beam interferometer. Our measurements provide benchmark tests for atomic structure calculations and thus test the underlying theory used to interpret atomic parity non-conservation experiments. We measured $\\alpha_{\\mathrm{Cs}} = 4\\pi\\epsilon_0 \\times 59.45(11) \\AA^3$, $\\alpha_{\\mathrm{Rb}} = 4\\pi\\epsilon_0 \\times 47.44(9) \\AA^3$, and $\\alpha_{\\mathrm{K}} = 4\\pi\\epsilon_0 \\times 42.97(8) \\AA^3$. In atomic units, these measurements are $\\alpha_{\\mathrm{Cs}} = 401.2(7)$, $\\alpha_{\\mathrm{Rb}} = 320.1(6)$, and $\\alpha_{\\mathrm{K}} = 290.0(5)$. We report ratios of polarizabilities $\\alpha_{\\mathrm{Cs}}/\\alpha_{\\mathrm{Rb}} = 1.2532(10)$, $\\alpha_{\\mathrm{Cs}}/\\alpha_{\\mathrm{K}} = 1.3835(9)$, and $\\alpha_{\\mathrm{Rb}}/\\alpha_{\\mathrm{K}} = 1.1040(9)$ with smaller fractional uncertainty because the systematic errors for individual measurements are largely correlated. Since Cs atom...
Importance of complex orbitals in calculating the self-interaction-corrected ground state of atoms
Kluepfel, Simon; Kluepfel, Peter; Jonsson, Hannes
2011-11-15
The ground state of atoms from H to Ar was calculated using a self-interaction correction to local- and gradient-dependent density functionals. The correction can significantly improve the total energy and makes the orbital energies consistent with ionization energies. However, when the calculation is restricted to real orbitals, application of the self-interaction correction can give significantly higher total energy and worse results, as illustrated by the case of the Perdew-Burke-Ernzerhof gradient-dependent functional. This illustrates the importance of using complex orbitals for systems described by orbital-density-dependent energy functionals.
Existence of a ground state for the confined hydrogen atom in non-relativistic QED
Amour, Laurent; Faupin, Jeremy
2008-04-03
We consider a system of a hydrogen atom interacting with the quantized electromagnetic field. Instead of fixing the nucleus, we assume that the system is confined by its center of mass. This model is used in theoretical physics to explain the Lamb-Dicke effect. After a brief review of the literature, we explain how to verify some properly chosen binding conditions which lead to the existence of a ground state for our model, and for all values of the fine-structure constant.
Bradley, T D; McFerran, J J; Jouin, J; Debord, B; Alharbi, M; Thomas, P; Gerome, F; Benabid, F
2015-01-01
We report on the measurement of ground state atomic polarization relaxation tile of Rb vapor confined in five different hypocycloidal core shape Kagome hollow core photonic crystal fibers made with uncoated silica glass. We are able to distinguish between wall-collision and transit-time effects in optical waveguide and deduce the contribution of the atom's dwell time at the core wall surface. In contrast with convetional macroscopic atomic cell configuration, and in agreement with Monte Carlo simulations, the measured relaxation times were found to be at least one order of magnitude longer than the limit set by the atom-wall collisional relaxation from thermal atoms. This extended relaxation time is explained by the combination of a stronger contribution of the slow atoms in the atomic polarization build-up, and of the relatively significant contribution of dwell time to the relaxation process of the ground state polarization.
Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions
Mader, Elizabeth A.; Manner, Virginia W.; Markle, Todd F.; Wu, Adam; Franz, James A.; Mayer, James M.
2009-03-10
Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors MIILH and oxyl radicals. [FeII(H2bip)3]2+, [FeII(H2bim)3]2+, [CoII(H2bim)3]2+ and RuII(acac)2(py-imH) [H2bip = 2,2’-bi-1,4,5,6-tetrahydro¬pyrimidine, H2bim = 2,2’-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2’-pyridyl)¬imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or tBu3PhO• (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex MIIIL, and TEMPOH or tBu3PhOH. Solution equilibrium measurements for the reactions of Co and Fe complexes with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer: ?SºHAT = -30 ± 2 cal mol-1 K-1 for the two iron complexes and -41 ± 2 cal mol-1 K-1 for [CoII(H2bim)3]2+. The ?SºHAT for TEMPO + RuII(acac)2(py-imH) is much closer to zero, 4.9 ± 1.1 cal mol-1 K-1. 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. An evaluation of the literature BDEs of both TEMPOH and tBu3PhOH is briefly presented and new estimates are included on the relative enthalpy of solvation for tBu3PhO• vs. tBu3PhOH. The primary contributor to the large magnitude of the ground-state entropy |?SºHAT| for the metal complexes is vibrational entropy, ?Sºvib. The common assumption that ?SºHAT ? 0 for HAT reactions, developed for organic and small gas phase molecules, 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. ?SºET and ?SºHAT are both affected by ?Sºvib and vary 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. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.
Achieving ground-state polar molecular condensates by chainwise atom-molecule adiabatic passage
Qian Jing; Zhang Weiping; Ling, Hong Y.
2010-01-15
We generalize the idea of chainwise stimulated Raman adiabatic passage (STIRAP) [Kuznetsova et al., Phys. Rev. A 78, 021402(R) (2008)] to a photoassociation-based chainwise atom-molecule system, with the goal of directly converting two-species atomic Bose-Einstein condensates (BEC) into a ground polar molecular BEC. We pay particular attention to the intermediate Raman laser fields, a control knob inaccessible to the usual three-level model. We find that an appropriate exploration of both the intermediate laser fields and the stability property of the atom-molecule STIRAP can greatly reduce the power demand on the photoassociation laser, a key concern for STIRAPs starting from free atoms due to the small Franck-Condon factor in the free-bound transition.
Nephtali Garrido; Hector H. Hernandez
2012-01-19
We put to the test an effective three-dimensional electrostatic potential, obtained effectively by considering an electrostatic source inside a (5+$p$)-dimensional braneworld scenario with $p$ compact and one infinite spacial extra dimensions in the RS II-$p$ model, for $p=1$ and $p=2$. This potential is regular at the source and matches the standard Coulomb potential outside a neighborhood. We use variational and perturbative approximation methods to calculate corrections to the ground energy of the Helium atom modified by this potential, by making use of a 6 and 39-parameter trial wave function of Hylleraas type for the ground state. These corrections to the ground-state energy are compared with experimental data for Helium atom in order to set bounds for the extra dimensions length scale. We find that these bounds are less restrictive than the ones obtained by Morales et. al. through a calculation using the Lamb shift in Hydrogen.
NASA Astrophysics Data System (ADS)
Shi, De-Heng; Zhang, Jin-Ping; Sun, Jin-Feng; Ma, Heng; Liu, Yu-Fang; Zhu, Zun-Lue
2010-02-01
The PD(X3?-) interaction potential is constructed using the CCSD(T) theory and the basis set, aug-cc-pV5Z. Using this potential, the spectroscopic parameters are accurately determined. The present Do, De, Re, ?e, ?e?e, ?e, and Be are of 3.056 99 eV, 3.161 75 eV, 0.142 39 nm, 1701.558 cm-1, 23.6583 cm-1, 0.085 99 cm-1, and 4.3963 cm-1, respectively, which almost perfectly conform with the measurements. A total of 26 vibrational states is predicted when J = 0 by solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which favorably agree with the experiments. The total and various partial-wave cross sections are calculated for the elastic impact between two ground-state P and D atoms at 1.0 × 10-12 - 1.0 × 10-4 a.u. when they approach each other along the PD(X3?-) potential. No shape resonances exist in the total elastic cross sections, though the peaks can be found for each partial wave until l = 6. The shape of the total elastic cross sections is dominated by the s partial wave at very low temperatures. Due to the weakness of the shape resonances of each partial wave, they are all passed into oblivion by the strong total elastic cross sections.
NASA Astrophysics Data System (ADS)
Krim, Lahouari; Nourry, Sendres
2015-06-01
In the last few years, ambitious programs were launched to probe the interstellar medium always more accurately. One of the major challenges of these missions remains the detection of prebiotic compounds and the understanding of reaction pathways leading to their formation. These complex heterogeneous reactions mainly occur on icy dust grains, and their studies require the coupling of laboratory experiments mimicking the extreme conditions of extreme cold and dilute media. For that purpose, we have developed an original experimental approach that combine the study of heterogeneous reactions (by exposing neutral molecules adsorbed on ice to non-energetic radicals H, OH, N...) and a neon matrix isolation study at very low temperatures, which is of paramount importance to isolate and characterize highly reactive reaction intermediates. Such experimental approach has already provided answers to many questions raised about some astrochemically-relevant reactions occurring in the ground state on the surface of dust grain ices in dense molecular clouds. The aim of this new present work is to show the implication of ground state atomic nitrogen on hydrogen atom abstraction reactions from some astrochemically-relevant species, at very low temperatures (3K-20K), without providing any external energy. Under cryogenic temperatures and with high barrier heights, such reactions involving N(4S) nitrogen atoms should not occur spontaneously and require an initiating energy. However, the detection of some radicals species as byproducts, in our solid samples left in the dark for hours at 10K, proves that hydrogen abstraction reactions involving ground state N(4S) nitrogen atoms may occur in solid phase at cryogenic temperatures. Our results show the efficiency of radical species formation stemming from non-energetic N-atoms and astrochemically-relevant molecules. We will then discuss how such reactions, involving nitrogen atoms in their ground states, might be the first key step towards complex organic molecules production in the interstellar medium.
Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions
Mader, Elizabeth A.; Manner, Virginia W.; Markle, Todd F.; Wu, Adam; Franz, James A.; Mayer, James M.
2009-01-01
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
Gu, Bing; Hinde, Robert J; Rassolov, Vitaly A; Garashchuk, Sophya
2015-07-14
Evolution with energy dissipation can be used to obtain the ground state of a quantum-mechanical system. This dissipation is introduced in the quantum trajectory framework by adding an empirical friction force to the equations of motion for the trajectories, which, as an ensemble, represent a wave function. The quantum effects in dynamics are incorporated via the quantum force derived from the properties of this ensemble. For scalability to large systems, the quantum force is computed approximately yet with sufficient accuracy to describe the strongly anharmonic ground state of solid (4)He represented by a simulation cell of 180 atoms. PMID:26575727
NASA Astrophysics Data System (ADS)
Redondo, C.; Sanchez Rayo, M. N.; Fernandez, J. A.; Husain, D.; Castaño, F.
2001-02-01
Intramultiplet collisionally induced mixing within the Sr[5s5p( 3P 0,1,2)] manifold is investigated by time-resolved laser-induced fluorescence (LIF) following the pulsed dye-laser generation of Sr( 3P 1) of the electronic ground state {Sr[5s5p( 3P 0,1,2)]?Sr[5s 2( 1S 0)], ?=689.26 nm} at elevated temperatures. The population profiles of the three spin-orbit states were individually monitored by LIF as well as that of Sr( 3P 1) by spontaneous emission at the resonance wavelength. A kinetic model is employed that enables the process of spontaneous emission from Sr( 3P 1) to be isolated initially and characterised by experiment. Particular emphasis is placed on the modelling procedure itself in which the separate kinetic component due to spontaneous emission and the positions of the maxima in the 3P 0 and 3P 2 population profiles constitute severe constraints on the model. The collisional components within the model are reduced to three rate constants where pairs of J states are connected in this context by detailed balance. Thus k10 and k12, and, by detailed balance, k01 and k21 are quantified at various temperatures and pressures to yield the absolute value of these collision properties for Sr( 3P J) with He and Ar. Rate data for collisionally induced intramultiplet mixing in Sr( 3P J) by Sr( 1S 0) itself is also reported found to proceed at close to unit collisional efficiencies in all cases. Thus, at elevated temperatures, variations in atomic profiles are dominated by the differing vapour pressures of atomic strontium. Estimates of the activation energies associated with k10 and k12 for the noble gases observed against this large competing background are found to be of the order of the spin-orbit splittings. The model overall is found to be insensitive to k02 and k20 whose magnitudes are small by comparison with those for the collisional rate data connecting adjacent J states. Whilst collisional processes for He are some two orders of magnitude more efficient than those for Ar, all of these are seen to be 'adiabatic', in contrast with the gas kinetic rate constants of ground Sr, considered to be 'sudden' in character. The results are compared with analogous data derived by atomic resonance absorption spectroscopy following pulsed generation of Sr( 3P 1) and are considered in the context of theoretical calculations employing quantum close coupling calculations.
Meta-Atom Behavior in Clusters Revealing Large Spin Ground States.
Hernández Sánchez, Raúl; Betley, Theodore A
2015-11-01
The field of single molecule magnetism remains predicated on super- and double exchange mechanisms to engender large spin ground states. An alternative approach to achieving high-spin architectures involves synthesizing weak-field clusters featuring close M-M interactions to produce a single valence orbital manifold. Population of this orbital manifold in accordance with Hund's rules could potentially yield thermally persistent high-spin ground states under which the valence electrons remain coupled. We now demonstrate this effect with a reduced hexanuclear iron cluster that achieves an S = 19/2 (?MT ? 53 cm(3) K/mol) ground state that persists to 300 K, representing the largest spin ground state persistent to room temperature reported to date. The reduced cluster displays single molecule magnet behavior manifest in both variable-temperature zero-field (57)Fe Mössbauer and magnetometry with a spin reversal barrier of 42.5(8) cm(-1) and a magnetic blocking temperature of 2.9 K (0.059 K/min). PMID:26440452
Ground Levels and Ionization Energies for the Neutral Atoms
National Institute of Standards and Technology Data Gateway
SRD 111 Ground Levels and Ionization Energies for the Neutral Atoms (Web, free access) Data for ground state electron configurations and ionization energies for the neutral atoms (Z = 1-104) including references.
A simple, radially correlated ground state wavefunction for two electron atoms.
NASA Technical Reports Server (NTRS)
Altick, P. L.
1972-01-01
A one parameter function is presented as an approximation to the ground state wavefunction of the two electron radial hamiltonian. The parameter may be fixed by a nonvariational criterion. The resulting expectation value of the radial hamiltonian differs from its exact eigenvalue by about 2 parts in 3000 for helium while the 'local energy' never differs by more than 10% from the exact value over the entire r1-r2 plane. The cases Z = 1 and Z = 3 are also investigated.
NASA Astrophysics Data System (ADS)
Mohallem, J. R.; Trsic, M.
1985-12-01
It is shown that the Griffin-Hill-Wheeler equation for the ground state of the hydrogen atom can be solved analytically for a Gaussian trial function. Both the exact eigenfunction and eigenvalue can be generated.
Guerout, R.; Aymar, M.; Dulieu, O.
2010-10-15
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.
NASA Astrophysics Data System (ADS)
Nandy, D. K.; Sahoo, B. K.
2015-06-01
High-accuracy calculations of the forbidden transition amplitudes for the np 2P1/2 ? np 2P3/2 transitions with the ground-state principal quantum number n in singly charged inert gas atoms, which are of astrophysical interest, have been carried out using sophisticated relativistic many-body methods. Using these amplitudes, the line strengths, oscillator strengths and transition probabilities of the above transitions and lifetimes of the np 2P1/2 states are estimated precisely. Most of these transition wavelengths lie in the infrared region, while the corresponding Rn II line is the optical one, and they can be observed in the stellar and interstellar media, where the abundances of these ions have already been identified. The above forbidden transitions can also be very useful for astrophysical plasma diagnostics and can guide experiments to measure the lifetimes of the above np 2P1/2 states.
Eskandari, M.R.; Rezaie, B.
2005-07-15
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.
NASA Technical Reports Server (NTRS)
Partridge, Harry; Stallcop, James R.; Levin, Eugene; Arnold, Jim (Technical Monitor)
2001-01-01
The interactions of a He atom with a heavier atom are examined for 26 different elements, which are consecutive members selected from three rows (Li - Ne, Na - Ar, and K,Ca, Ga - Kr) and column 12 (Zn,Cd) of the periodic table. Interaction energies are determined wing high-quality ab initio calculations for the states of the molecule that would be formed from each pair of atoms in their ground states. Potential energies are tabulated for a broad range of Interatomic separation distances. The results show, for example, that the energy of an alkali interaction at small separations is nearly the same as that of a rare-gas interaction with the same electron configuration for the dosed shells. Furthermore, the repulsive-range parameter for this region is very short compared to its length for the repulsion dominated by the alkali-valence electron at large separations (beyond about 3-4 a(sub 0)). The potential energies in the region of the van der Waals minimum agree well with the most accurate results available. The ab initio energies are applied to calculate scattering cross sections and obtain the collision integrals that are needed to determine transport properties to second order. The theoretical values of Li-He total scattering cross sections and the rare-gas atom-He transport properties agree well (to within about 1%) with the corresponding measured data. Effective potential energies are constructed from the ab initio energies; the results have been shown to reproduce known transport data and can be readily applied to predict unknown transport properties for like-atom interactions.
Ground State Properties of Cold Bosonic Atoms at Large Scattering Lengths
Song Junliang; Zhou Fei
2009-07-10
In this Letter, we study bosonic atoms at large scattering lengths using a variational method where the condensate amplitude is a variational parameter. We further examine momentum distribution functions, chemical potentials, the speed of sound, and spatial density profiles of cold bosonic atoms in a trap in this limit. The latter two properties turn out to bear similarities to those of Fermi gases. The estimates obtained here are applicable near Feshbach resonances, particularly when the fraction of atoms forming three-body structures is small and can be tested in future cold atom experiments.
Au, Yat Shan; Ketterle, Wolfgang; Doyle, John M
2013-01-01
We measure inelastic collisional cross sections for the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He. We determine for Th ($^3$F$_2$) at 800 mK the ratio $\\gamma \\approx 500$ of the momentum-transfer to Zeeman relaxation cross sections for collisions with $^3$He. For Th ($^3$P$_0$), we study electronic inelastic processes and find no quenching even after $10^6$ collisions. We also determine the radiative lifetime of Th ($^3$P$_0$) to be $\\tau > 130$ ms. This great stability of the metastable state opens up the possibility for further study, including trapping.
Stefano Zippilli; Giovanna Morigi
2007-03-21
We investigate theoretically the mechanical effects of light on atoms trapped by an external potential, whose dipole transition couples to the mode of an optical resonator and is driven by a laser. We derive an analytical expression for the quantum center-of-mass dynamics, which is valid in presence of a tight external potential. This equation has broad validity and allows for a transparent interpretation of the individual scattering processes leading to cooling. We show that the dynamics are a competition of the mechanical effects of the cavity and of the laser photons, which may mutually interfere. We focus onto the good-cavity limit and identify novel cooling schemes, which are based on quantum interference effects and lead to efficient ground state cooling in experimentally accessible parameter regimes.
Klemm, R.B.; Nesbitt, F.L.; Skolnik, E.G.; Lee, J.H.; Smalley, J.F.
1987-03-12
The rate constant for the reaction of ground-state atomic oxygen with ethylene was determined by using two techniques: flash photolysis-resonance fluorescence (FP-RF, 244-1052 K) and discharge flow-resonance fluorescence (DF-RF, 298-1017 K). Kinetic complications due to the presence of molecular oxygen in the FP-RF experiments at high temperatures (T > 800 K) were overcome by using NO as the photolytic source of the O atoms. The rate constant, k/sub 1/ (T), derived in this study exhibits extreme non-Arrhenius behavior, but it can be successfully fit to the sum of exponentials expression, 244-1052 K, k/sub 1/(T) = (1.02 +/- 0.06) x 10/sup -11/ exp(-753 +/- 17 K/T) + (2.75 +/- 0.26) x 10/sup -10/ exp(-4220 +/- 550 K/T), in units of cm/sup 3/ molecule/sup -1/ s/sup -1/. Additionally, a fit of the results of this work to a simple transition-state theory expression and the comparison of these results with those of other workers are discussed.
Nonadiabatic couplings in low-energy collisions of hydrogen ground-state atoms
Wolniewicz, L.
2003-10-01
The effect of nonadiabatic couplings on low-energy s-wave scattering of two hydrogen atoms is investigated. Coupling matrix elements are computed in a wide range of internuclear distances. The resulting scattering equations are numerically unstable and therefore are integrated only approximately. Computations are performed for H, D, and T atoms. The phase shifts in the zero velocity limit are inversely proportional to the nuclear reduced mass {delta}{sub 0}{approx_equal}0.392/{mu}. This leads to infinite scattering lengths.
NASA Technical Reports Server (NTRS)
Lee, J. H.; Timmons, R. B.; Stief, L. J.
1976-01-01
It is pointed out that the investigated reaction of oxygen with dimethyl sulfide may play an important role in photochemical smog formation and in the chemical evolution of dense interstellar clouds. Kinetic data were obtained with the aid of the flash photolysis-resonance fluorescence method. The photodecomposition of molecular oxygen provided the oxygen atoms for the experiments. The decay of atomic oxygen was studied on the basis of resonance fluorescence observations. Both reactions investigated were found to be fast processes. A negative temperature dependence of the rate constants for reactions with dimethyl sulfide was observed.
Rioux, Frank
Why Isn't the Ground State Electronic Structure of the Lithium Atom 1s3? The purpose of this tutorial is to point out that if all that mattered in the determination of atomic structure was energy minimization, the electronic structure of lithium would be 1s3, rather than 1s22s1. To deal with this issue we
State-selective capture in collisions between ions and ground- and excited-state alkali-metal atoms
Pascale, J. ); Olson, R.E.; Reinhold, C.O. )
1990-11-01
Total cross sections for state-selective electron capture in collisions between ions and alkali-metal atoms have been calculated by means of a three-body classical-trajectory Monte Carlo (CTMC) method using model potentials to describe the electron--ionic-core interactions. Calculations have been performed for Na{sup +}-Na(28{ital d}) collisions and for N{sup 5+} and Ar{sup 8+}-Cs(6{ital s}) collisions. The collision velocity range corresponds to 0.5{approx lt}{ital v}{sub {ital p}}/{ital v}{sub {ital e}}{approx lt}2, where {ital v}{sub {ital p}} is the projectile velocity in the laboratory frame and {ital v}{sub {ital e}} is the initial orbital velocity of the electron bound to the alkali-metal core. In the case of Na{sup +}+Na(28{ital d}) collisions, calculations of the final {ital n},{ital l},{ital m} distributions show the importance of the electron-capture cross sections into states with {ital m}{gt}1. For the case of multiply charged ion--Cs(6{ital s}) collisions, a predominance of electron capture to nearly circular states (large {ital l} values) is predicted for cross sections near the maximum of the {ital n} distribution. When the {ital e}{sup {minus}}-Cs{sup +} interaction is described by a realistic model potential, the CTMC calculations are found to be in good agreement with recent measurements of the final {ital n} values that are predominantly populated after single-electron capture.
Ground State and Charge Renormalization in a Nonlinear Model of Relativistic Atoms
Philippe Gravejat; Mathieu Lewin; Eric Sere
2007-12-18
We study the reduced Bogoliubov-Dirac-Fock (BDF) energy which allows to describe relativistic electrons interacting with the Dirac sea, in an external electrostatic potential. The model can be seen as a mean-field approximation of Quantum Electrodynamics (QED) where photons and the so-called exchange term are neglected. A state of the system is described by its one-body density matrix, an infinite rank self-adjoint operator which is a compact perturbation of the negative spectral projector of the free Dirac operator (the Dirac sea). We study the minimization of the reduced BDF energy under a charge constraint. We prove the existence of minimizers for a large range of values of the charge, and any positive value of the coupling constant $\\alpha$. Our result covers neutral and positively charged molecules, provided that the positive charge is not large enough to create electron-positron pairs. We also prove that the density of any minimizer is an $L^1$ function and compute the effective charge of the system, recovering the usual renormalization of charge: the physical coupling constant is related to $\\alpha$ by the formula $\\alpha_{\\rm phys}\\simeq \\alpha(1+2\\alpha/(3\\pi)\\log\\Lambda)^{-1}$, where $\\Lambda$ is the ultraviolet cut-off. We eventually prove an estimate on the highest number of electrons which can be bound by a nucleus of charge $Z$. In the nonrelativistic limit, we obtain that this number is $\\leq 2Z$, recovering a result of Lieb. This work is based on a series of papers by Hainzl, Lewin, Sere and Solovej on the mean-field approximation of no-photon QED.
Dudarev, A. M.; Raizen, M. G.; Niu Qian
2007-02-09
We propose a method to produce a definite number of ground-state atoms by adiabatic reduction of the depth of a potential well that confines a degenerate Bose gas with repulsive interactions. Using a variety of methods, we map out the maximum number of particles that can be supported by the well as a function of the well depth and interaction strength, covering the limiting case of a Tonks gas as well as the mean-field regime. We also estimate the time scales for adiabaticity and discuss the recent observation of atomic number squeezing [Chuu et al., Phys. Rev. Lett. 95, 260403 (2005)].
NASA Astrophysics Data System (ADS)
Liu, Ya-Wei; Mei, Xiao-Xun; Kang, Xu; Yang, Ke; Xu, Wei-Qing; Peng, Yi-Geng; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhang, Peng-Fei; Zhu, Lin-Fan
2014-01-01
The high-resolution x-ray-scattering technique is used to study the elastic scattering of atoms and molecules in the gas phase. The elastic squared form factor, which is the square of the Fourier transformation of the electron density distribution in position space and reveals the pure electronic structure of atoms and molecules in the ground state, of molecular hydrogen is measured at an incident photon energy of about 9889 eV and an energy resolution of about 70 meV. Although it is generally thought that the x-ray-scattering technique is identical to high-energy electron scattering, at least for elastic scattering these two techniques have an apparent difference, i.e., the pure electronic structure of a molecule in the ground state can be determined by x-ray scattering while it cannot be obtained by the high-energy electron impact method due to the interference between the scattering of separate nuclei and of the electrons in the target. The present experimental results match the theoretical calculations very well, which demonstrates that high-resolution x-ray scattering is a powerful tool to study the electronic structure of atoms and molecules in the ground state.
NASA Astrophysics Data System (ADS)
Diao, Wenting; He, Jun; Liu, Bei; Wang, Junmin
2012-11-01
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.
Yavuz, Deniz
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
Glasser, M. L.; March, N. H.; Nieto, L. M.
2011-12-15
Here attention is first drawn to the importance of gaining insight into Fock's early proposal for expanding the ground-state wave function for He-like atomic ions in hyperspherical coordinates. We approach the problem via two solvable models, namely, (i) the s-term model put forth by Temkin [Phys. Rev. 126, 130 (1962)] and (ii) the Hookean atom model proposed by Kestner and Sinanoglu [Phys. Rev. 128, 2687 (1962)]. In both cases the local kinetic energy can be obtained explicitly in hyperspherical coordinates. Separation of variables occurs in both model wave functions, though in a different context in the two cases. Finally, a k-space formulation is proposed that should eventually result in distinctive identifying characteristics of Fock's nonanalyticities for He-like atomic ions when both electrons are close to the nucleus.
Richard G. Forbes
2015-07-01
Technical applications using electrostatic field ionization (ESFI) need a formula for the rate-constant K_e for the free-space ESFI of a hydrogenic atom in its ground electronic state. This formula must indicate the dependence on ionization energy I. Existing formulae were derived using atomic units. However, many scientists work with ESFI as an important technical process, but are not familiar with the Gaussian or atomic units systems. In the 1970s, the present International System of Quantities (ISQ), which includes the equations behind SI units, was designated as the main system for university teaching and the communication of scientific equations. 40 years on, ISQ derivations of ESFI rate-constant formulae are still not easily found, but are now needed. This tutorial paper gives a detailed ISQ derivation of a formula for K_e. The derivation is closely modelled on the Landau and Lifshitz (LL) approach used in their 1958 work (in atomic units) on hydrogen atom ESFI. The ISQ derivation confirms that, for hydrogenic atoms, ionization energy appears in the pre-exponential as I^(5/2), and defines a universal "field ionization constant". It also shows how the ISQ formula relates to the Gurney and Condon "attempt frequency" form for tunnelling rate-constants, and an ISQ formula is given for the motive energy in the related JWKB integral. The ISQ derivation uses a motive-energy transformation analogous to a transformation used by LL. The need for this transformation in ESFI theory raises questions as to the correctness of theoretical treatments of field electron emission from non-planar emitters, which do not make this transformation.
Ground State Electroluminescence
Mauro Cirio; Simone De Liberato; Neill Lambert; Franco Nori
2015-08-24
Electroluminescence, the emission of light in the presence of an electric current, provides information on the allowed electronic transitions of a given system. It is commonly used to investigate the physics of strongly-coupled light-matter systems, whose eigenfrequencies are split by the strong coupling with the photonic field of a cavity. Here we show that, together with the usual electroluminescence, systems in the ultrastrong light-matter coupling regime emit a uniquely quantum radiation when a flow of current is driven through them. While standard electroluminescence relies on the population of excited states followed by spontaneous emission, the process we describe herein extracts bound photons by the dressed ground state and it has peculiar features that unequivocally distinguish it from usual electroluminescence.
Trapped antihydrogen in its ground state.
Gabrielse, G; Kalra, R; Kolthammer, W S; McConnell, R; Richerme, P; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Fitzakerley, D W; George, M C; Hessels, E A; Storry, C H; Weel, M; Müllers, A; Walz, J
2012-03-16
Antihydrogen atoms (H¯) are confined in an Ioffe trap for 15-1000 s-long enough to ensure that they reach their ground state. Though reproducibility challenges remain in making large numbers of cold antiprotons (p¯) and positrons (e(+)) interact, 5±1 simultaneously confined ground-state atoms are produced and observed on average, substantially more than previously reported. Increases in the number of simultaneously trapped H¯ are critical if laser cooling of trapped H¯ is to be demonstrated and spectroscopic studies at interesting levels of precision are to be carried out. PMID:22540471
Kaiser, Ralf I.
and carbonaceous nanoparticles in combustion processes, chemical vapour deposition and the out¯ows of carbon stars bonds 339 5.2. Reactions of atomic carbon with hydrocarbons carrying carbon±carbon double bonds 340 5
NASA Astrophysics Data System (ADS)
Nourry, Sendres; Krim, Lahouari
2015-07-01
We have characterized the CH4 + N(4S) reaction in solid phase, at very low temperature, under non-energetic conditions and where the CH4 and N reactants are in their ground states. A microwave-driven atomic source has been used to generate ground-state nitrogen atoms N(4S), and experiments have been carried out at temperatures as low as 3 K to reduce the mobility of the trapped species in solid phase and hence to freeze the first step of the CH4 + N reaction pathway. Leaving the formed solid sample in the dark for a while allows all trapped reactants to relax to the ground state, specifically radicals and excited species streaming from the plasma discharge. Such a method could be the only possibility of proving that the CH4 + N reaction occurs between CH4 and N reactants in their ground states without any additional energy to initiate the chemical process. The appearance of the CH3 reaction product, just by inducing the mobility of N atoms between 3 and 11 K, translates that a hydrogen abstraction reaction from methane, under non-energetic conditions, will start occurring at very low temperature. The formation of methyl radical, under these experimental conditions, is due to recombination processes N(4S)-N(4S) of ground-state nitrogen atoms without any contribution of cosmic ray particles or high-energy photons.
Atom interferometery on ground and in space
NASA Astrophysics Data System (ADS)
Rasel, Ernst M.; Quantus Collaboration
2014-05-01
We give a brief survey on our latest activities in atom interferometry. This included the first quantum test of the principle of equivalence with two different species, namely potassium and rubidium. We have also shown that interferometers equipped with atom-chip based sources allow to realise compact quantum gravimeters for ground based measurements. These devices allow to achieve a high flux of ultra-cold atoms, extremely low expansion rates of these wave packets and make it possible to realise new interferometers. Last but not least, in 2014, we currently work on testing these devices in the catapult and on a sounding rocket mission to extend atom interferometry to unprecedented time scales. This project is supported by the German Space Agency Deutsches Zentrum für Luft- und Raumfahrt (DLR) with funds provided by the Federal Ministry of Economics and Technology (BMWI) under grant number DLR 50 WM 0346. We thank the German Research Foundation for funding the Cluster of Excellence QUEST Centre for Quantum Engineering and Space-Time Research.
NASA Astrophysics Data System (ADS)
Carbone, Emile; van Dijk, Jan; Kroesen, Gerrit
2015-04-01
In this paper, laser collisional induced fluorescence (LCIF) is used to probe resonant excitation transfers in an argon/hydrogen plasma resulting from heavy particle collisions. Different radiative transitions between the 1s and 2p states (in Paschen's notation) of argon are optically pumped by a nanosecond laser pulse. The spontaneous fluorescence and collisional responses of the argon and hydrogen systems are monitored by optical emission spectroscopy. A surfatron plasma source is used to generate an argon plasma with a few per cent hydrogen addition at pressures between 0.65 and 20 mbar. The electron density is measured independently by means of Thomson scattering. The overall response of the plasma due to optical pumping of argon is briefly discussed and an overview of the known heteronuclear excitation transfers in an argon/hydrogen plasma is given. The propagation of the shortcut in the Ar(1s) to H(n = 2) excitation transfer due to the optical pumping of the Ar(1s) states is seen in the atomic hydrogen LCIF responses. For the first time, we give direct experimental evidence of the existence of an efficient excitation transfer: Additionally, measurements are performed in order to estimate the resonant energy transfer between the resonant argon 1s states and hydrogen atoms: for which no previously measured cross sections could be found in the literature. These are extra quenching channels of argon 1s and 2p states that should be included in collisional-radiative modeling of argon-hydrogen discharges. The high repetition rate of the dye laser allows us to obtain a high sensitivity in the measurements. LCIF is shown to be a powerful tool for unraveling electron and also heavy particle excitation channels in situ in the plasma phase. The technique was previously developed for measuring electron or species densities locally in the plasma, but we show that it can be advantageously used to probe collisional transfers between very short-lived species which exist simultaneously only in the plasma phase.
Magnetic Field Measurement with Ground State Alignment
NASA Astrophysics Data System (ADS)
Yan, Huirong; Lazarian, A.
Observational studies of magnetic fields are crucial. We introduce a process "ground state alignment" as a new way to determine the magnetic field direction in diffuse medium. The alignment is due to anisotropic radiation impinging on the atom/ion. The consequence of the process is the polarization of spectral lines resulting from scattering and absorption from aligned atomic/ionic species with fine or hyperfine structure. The magnetic field induces precession and realign the atom/ion and therefore the polarization of the emitted or absorbed radiation reflects the direction of the magnetic field. The atoms get aligned at their low levels and, as the life-time of the atoms/ions we deal with is long, the alignment induced by anisotropic radiation is susceptible to extremely weak magnetic fields (1 G ? B ? 10^{-15} G). In fact, the effects of atomic/ionic alignment were studied in the laboratory decades ago, mostly in relation to the maser research. Recently, the atomic effect has been already detected in observations from circumstellar medium and this is a harbinger of future extensive magnetic field studies. A unique feature of the atomic realignment is that they can reveal the 3D orientation of magnetic field. In this chapter, we shall review the basic physical processes involved in atomic realignment. We shall also discuss its applications to interplanetary, circumstellar and interstellar magnetic fields. In addition, our research reveals that the polarization of the radiation arising from the transitions between fine and hyperfine states of the ground level can provide a unique diagnostics of magnetic fields in the Epoch of Reionization.
Ground state of antiferromagnetic ordering in fullerene $C_{60}$ molecule
C. V. Usenko; V. C. Usenko
2001-01-15
Theoretical study of mutual orientation of fullerene $C_{60}$ molecule atom spins is presented in this work. Spin-spin interaction was described by Habbard's model. Existence of antiferromagnetic sturcture of spin sub-system in ground state is found.
Multilevel Atomic Coherent States and Atomic Holomorphic Representation
NASA Technical Reports Server (NTRS)
Cao, Chang-Qi; Haake, Fritz
1996-01-01
The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.
Stability of triplet rubidium ground-state molecules
Verhaar, B J
2014-01-01
Experiments involving ultracold molecules require sufficiently long lifetimes, which can be very short for excited rovibrational states in the molecular potentials. For alkali atoms such as rubidium, molecular, rovibrational ground-states can both be found in the electronic singlet and triplet configurations. The molecular singlet ground state is absolutely stable, however, the triplet ground state can decay to a deeper bound singlet molecule due to a radiative decay mechanism that involves the interatomic spin-orbit interaction. We investigate this mechanism, and find the lifetime of rubidium molecules in the triplet rovibrational ground-state to be about 13 minutes. This is sufficiently long for experimental purposes.
Estimation of beryllium ground state energy by Monte Carlo simulation
NASA Astrophysics Data System (ADS)
Kabir, K. M. Ariful; Halder, Amal
2015-05-01
Quantum Monte Carlo method represent a powerful and broadly applicable computational tool for finding very accurate solution of the stationary Schrödinger equation for atoms, molecules, solids and a variety of model systems. Using variational Monte Carlo method we have calculated the ground state energy of the Beryllium atom. Our calculation are based on using a modified four parameters trial wave function which leads to good result comparing with the few parameters trial wave functions presented before. Based on random Numbers we can generate a large sample of electron locations to estimate the ground state energy of Beryllium. Our calculation gives good estimation for the ground state energy of the Beryllium atom comparing with the corresponding exact data.
Savely G. Karshenboim; Vladimir G. Ivanov
2001-09-27
We consider hyperfine splitting of 1s and, in part, of 2s levels in light hydrogen-like atoms: hydrogen, deuterium, tritium, helium-3 ion, muonium and positronium. We discuss present status of precision theory and experiment for the hfs intervals. We pay a special attention to a specific difference, D_{21} = 8 E_{hfs}(2s) - E_{hfs}(1s), which is known experimentally for hydrogen, deuterium and ^3He^+ ion. The difference is weakly affected by the effects of the nuclear structure and thus may be calculated with a high accuracy. We complete a calculation of the fourth order QED contributions to this difference and present here new results on corrections due to the nuclear effects. Our theoretical predictions appear to be in a fair agreement with available experimental data. Comparison of the experimental data with our examination of D_{21} allows to test the state-dependent sector of theory of the hfs separation of the 1s and 2s levels in the light hydrogen-like atoms up to 10^-8.
Coherent Transfer of Photoassociated Molecules into the Rovibrational Ground State
Aikawa, K.; Hayashi, M.; Oasa, K.; Akamatsu, D.; Kobayashi, J.; Naidon, P.; Kishimoto, T.; Ueda, M.; Inouye, S.
2010-11-12
We report on the direct conversion of laser-cooled {sup 41}K and {sup 87}Rb atoms into ultracold {sup 41}K{sup 87}Rb molecules in the rovibrational ground state via photoassociation followed by stimulated Raman adiabatic passage. High-resolution spectroscopy based on the coherent transfer revealed the hyperfine structure of weakly bound molecules in an unexplored region. Our results show that a rovibrationally pure sample of ultracold ground-state molecules is achieved via the all-optical association of laser-cooled atoms, opening possibilities to coherently manipulate a wide variety of molecules.
March, N H; Nagy, A
2008-11-21
Following some studies of integral(n)(r)inverted DeltaV(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, integral(n)(r) partial differential(V)(r)/partial differential(r)dr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force - partial differential(V)/ partial differential(r) is then related to the derivative of the exchange-correlation potential V(xc)(r) by terms involving only the external potential in addition to n(r). The resulting integral constraint should allow some test of the quality of currently used forms of V(xc)(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell. PMID:19026052
State-selective all-optical detection of Rydberg atoms
NASA Astrophysics Data System (ADS)
Karlewski, Florian; Mack, Markus; Grimmel, Jens; Sándor, Nóra; Fortágh, József
2015-04-01
We present an all-optical protocol for detecting population in a selected Rydberg state of alkali-metal atoms. The detection scheme is based on the interaction of an ensemble of ultracold atoms with two laser pulses: one weak probe pulse which is resonant with the transition between the ground state and the first excited state, and a pulse with high intensity which couples the first excited state to the selected Rydberg state. We show that by monitoring the absorption signal of the probe laser over time, one can deduce the initial population of the Rydberg state. Furthermore, it is shown that—for suitable experimental conditions—the dynamical absorption curve contains information on the initial coherence between the ground state and the selected Rydberg state. We present the results of a proof-of-principle measurement performed on a cold gas of 87Rb atoms. The method is expected to find application in quantum computing protocols based on Rydberg atoms.
State-selective all-optical detection of Rydberg atoms
Karlewski, Florian; Grimmel, Jens; Sándor, Nóra; Fortágh, and József
2015-01-01
We present an all-optical protocol for detecting population in a selected Rydberg state of alkali atoms. The detection scheme is based on the interaction of an ensemble of ultracold atoms with two laser pulses: one weak probe pulse which is resonant with the transition between the ground state and the first excited state, and a pulse with high intensity which couples the first excited state to the selected Rydberg state. We show that by monitoring the absorption signal of the probe laser over time, one can deduce the initial population of the Rydberg state. Furthermore, it is shown that - for suitable experimental conditions - the dynamical absorption curve contains information on the initial coherence between the ground state and the selected Rydberg state. We present the results of a proof-of-principle measurement performed on a cold gas of $^{87}$Rb atoms. The method is expected to find application in quantum computing protocols based on Rydberg atoms.
Atomic spin chains as testing ground for quantum magnetism
NASA Astrophysics Data System (ADS)
Otte, Sander
2015-03-01
The field of quantum magnetism aims to capture the rich emergent physics that arises when multiple spins interact, in terms of elementary models such as the spin 1/2 Heisenberg chain. Experimental platforms to verify these models are rare and generally do not provide the possibility to detect spin correlations locally. In my lab we use low-temperature scanning tunneling microscopy to design and build artificial spin lattices with atomic precision. Inelastic electron tunneling spectroscopy enables us to identify the ground state and probe spin excitations as a function of system size, location inside the lattice and coupling parameter values. Two types of collective excitations that play a role in many dynamic magnetic processes are spin waves (magnons) and spinons. Our experiments enable us to study both types of excitations. First, we have been able to map the standing spin wave modes of a ferromagnetic bit of six atoms, and to determine their role in the collective reversal process of the bit (Spinelli et al., Nature Materials 2014). More recently, we have crafted antiferromagnetic spin 1/2 XXZ chains, which allow us to observe spinon excitations, as well as the stepwise transition to a fully aligned phase beyond the critical magnetic field (Toskovic et al., in preparation). These findings create a promising experimental environment for putting quantum magnetic models to the test. Research funded by NWO and FOM.
PEPS as ground states: Degeneracy and topology
Schuch, Norbert; Cirac, Ignacio; Perez-Garcia, David
2010-10-15
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.
All-Optical Scheme to Produce Quantum Degenerate Dipolar Molecules in the Vibronic Ground State
NASA Astrophysics Data System (ADS)
Mackie, Matt; Debrosse, Catherine
2010-03-01
We consider two-color heteronuclear photoassociation of Bose-condensed atoms into 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. The addition of the excited state creates a second pathway for creating ground state molecules, leading to quantum interference between direct photoassociation and photoassociation via the excited molecular state, as well as a dispersive-like 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 semi-classical size of both molecular states. Despite strong enhancement, coherent conversion to the LiNa vibronic ground state is possible only in a limited regime near the free-bound resonance.
Ground state terahertz quantum cascade lasers
Hu, Qing
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 ...
Femtosecond stimulated emission pumping: Characterization ground state
Neumark, Daniel M.
1 vibrational fre- quency, resonance impulsive stimulated Raman scattering RISRS was used to create ground state motion near the bottom of the well. The Fourier transform of the oscillations observed in the FPE spectraFemtosecond stimulated emission pumping: Characterization of the I2 À ground state Martin T. Zanni
NASA Technical Reports Server (NTRS)
Ketsdever, Andrew D.; Weaver, David P.; Muntz, E. P.
1994-01-01
Because of the continuing commitment to activity in low-Earth orbit (LEO), a facility is under development to produce energetic atmospheric species, particularly atomic oxygen, with energies ranging from 5 to 80 eV. This relatively high flux facility incorporates an ion engine to produce the corresponding specie ion which is charge exchanged to produce a neutral atomic beam. Ion fluxes of around 10(exp 15) sec(exp -1) with energies of 20-70 eV have been achieved. A geometrically augmented inertially tethered charge exchanger (GAITCE) was designed to provide a large column depth of charge exchange gas while reducing the gas load to the low pressure portion of the atomic beam facility. This is accomplished using opposed containment jets which act as collisional barriers to the escape of the dense gas region formed between the jets. Leak rate gains to the pumping system on the order of 10 were achieved for moderate jet mass flows. This system provides an attractive means for the charge exchange of atomic ions with a variety of gases to produce energetic atomic beams.
arXiv:quant-ph/99050166May1999 A simple formula for ground state energy of a two-electron atom
Auzinsh, Marcis
upon the Niels Bohr "old" quantum mechanics idea about electron correlation in a two-electron atom mechanics [1]. Already at the very beginning of "old" quantum theory Niels Bohr made his first attempt for electron correlation. Now let us assume, as it was done by Niels Bohr, that electrons are permanently
Simultaneous position and state measurement of Rydberg atoms
C. S. E. van Ditzhuijzen; A. F. Koenderink; L. D. Noordam; H. B. van Linden van den Heuvell
2007-05-22
We present a technique for state-selective position detection of cold Rydberg atoms. Ground state Rb atoms in a magneto-optical trap are excited to a Rydberg state and are subsequently ionized with a tailored electric field pulse. This pulse selectively ionizes only atoms in e.g. the 54d state and not in the 53d state. The released electrons are detected after a slow flight towards a micro channel plate. From the time of flight of the electrons the position of the atoms is deduced. The state selectivity is about 20:1 when comparing 54d with 53d and the one-dimensional position resolution ranges from 6 to 40 $\\mu$m over a range of 300 $\\mu$m. This state selectivity and position resolution are sufficient to allow for the observation of coherent quantum excitation transport.
Ground state laser cooling using electromagnetically induced transparency
Giovanna Morigi; Juergen Eschner; Christoph H. Keitel
2000-10-10
A laser cooling method for trapped atoms is described which achieves ground state cooling by exploiting quantum interference in a driven Lambda-shaped arrangement of atomic levels. The scheme is technically simpler than existing methods of sideband cooling, yet it can be significantly more efficient, in particular when several motional modes are involved, and it does not impose restrictions on the transition linewidth. We study the full quantum mechanical model of the cooling process for one motional degree of freedom and show that a rate equation provides a good approximation.
Mizel, Ari
2004-07-01
Ground-state quantum computers mimic quantum-mechanical time evolution within the amplitudes of a time-independent quantum state. We explore the principles that constrain this mimicking. A no-cloning argument is found to impose strong restrictions. It is shown, however, that there is flexibility that can be exploited using quantum teleportation methods to improve ground-state quantum computer design.
Coherent excitation of a single atom to a Rydberg state
Miroshnychenko, Y.; Gaeetan, A.; Evellin, C.; Grangier, P.; Wilk, T.; Browaeys, A.; Comparat, D.; Pillet, P.
2010-07-15
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.
Coherent excitation of a single atom to a Rydberg state
Y. Miroshnychenko; A. Gaëtan; C. Evellin; P. Grangier; D. Comparat; P. Pillet; T. Wilk; A. Browaeys
2010-05-12
We present the coherent excitation of a single Rubidium atom to the Rydberg state (58d3/2) using a two-photon transition. The experimental setup is described in detail, as well as 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.
Approaching condensed matter ground states from below
Hübener, Robert
2011-01-01
We present a generic approach to the condensed matter ground state problem which is complementary to variational techniques and works directly in the thermodynamic limit. Relaxing the ground state problem, we obtain semidefinite programs (SDP). These can be solved efficiently, yielding lower bounds to the ground state energy and approximations to the few-particle Green's functions. As the method is applicable for all particle statistics, it represents in particular a novel route for the study of strongly correlated fermionic and frustrated spin systems in D>1 spatial dimensions. It is demonstrated for the XXZ model and the Hubbard model of spinless fermions. The results are compared against exact solutions, Quantum Monte Carlo, and Anderson bounds, showing the competitiveness of the SDP method.
Baryonium, a common ground for atomic and high energy physics
NASA Astrophysics Data System (ADS)
Wycech, S.; Dedonder, J.-P.; Loiseau, B.
2015-08-01
Indications of the existence of quasi-bound states in the system are presented. In their measurements, the BES collaboration has discoverd a broad enhancement close to the threshold in the S wave, isospin 0 state formed in radiative decays of J/ ?. Another enhancement located about 50 MeV below the threshold was found in mesonic decays of J/ ?. In terms of the Paris potential model it was shown that these are likely to represent the same state. Antiprotonic atomic data provide some support for this interpretation and indicate the existence of another fairly narrow quasi-bound state in a P wave.
Ground water contamination in the United States.
Pye, V I; Patrick, R
1983-08-19
Ground water contamination is of increasing concern in the United States because about 50 percent of our drinking water comes from well water. The causes of contamination stem from both point sources and nonpoint sources. Since ground water moves slowly, the contaminant may affect only a small portion of an aquifer for a considerable period of time. Deleterious effects on human health have resulted from pathogenic organisms in ground water and from its toxic chemical composition. It is difficult to estimate the extent of contamination on a national basis as the frequency of instances of contamination is very variable. Remedial actions to clean up aquifers are difficult, expensive, and sometimes not feasible. Many of the laws and regulations that control ground water contamination are designed with other main objectives. PMID:6879171
Sideband Cooling Micromechanical Motion to the Quantum Ground State
J. D. Teufel; T. Donner; Dale Li; J. H. Harlow; M. S. Allman; K. Cicak; A. J. Sirois; J. D. Whittaker; K. W. Lehnert; R. W. Simmonds
2011-03-10
The advent of laser cooling techniques revolutionized the study of many atomic-scale systems. This has fueled progress towards quantum computers by preparing trapped ions in their motional ground state, and generating new states of matter by achieving Bose-Einstein condensation of atomic vapors. Analogous cooling techniques provide a general and flexible method for preparing macroscopic objects in their motional ground state, bringing the powerful technology of micromechanics into the quantum regime. Cavity opto- or electro-mechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime, less than a single quantum of motion, has been elusive because sideband cooling has not sufficiently overwhelmed the coupling of mechanical systems to their hot environments. Here, we demonstrate sideband cooling of the motion of a micromechanical oscillator to the quantum ground state. Entering the quantum regime requires a large electromechanical interaction, which is achieved by embedding a micromechanical membrane into a superconducting microwave resonant circuit. In order to verify the cooling of the membrane motion into the quantum regime, we perform a near quantum-limited measurement of the microwave field, resolving this motion a factor of 5.1 from the Heisenberg limit. Furthermore, our device exhibits strong-coupling allowing coherent exchange of microwave photons and mechanical phonons. Simultaneously achieving strong coupling, ground state preparation and efficient measurement sets the stage for rapid advances in the control and detection of non-classical states of motion, possibly even testing quantum theory itself in the unexplored region of larger size and mass.
Creation of a six-atom 'Schrödinger cat' state.
Leibfried, D; Knill, E; Seidelin, S; Britton, J; Blakestad, R B; Chiaverini, J; Hume, D B; Itano, W M; Jost, J D; Langer, C; Ozeri, R; Reichle, R; Wineland, D J
2005-12-01
Among the classes of highly entangled states of multiple quantum systems, the so-called 'Schrödinger cat' states are particularly useful. Cat states are equal superpositions of two maximally different quantum states. They are a fundamental resource in fault-tolerant quantum computing and quantum communication, where they can enable protocols such as open-destination teleportation and secret sharing. They play a role in fundamental tests of quantum mechanics and enable improved signal-to-noise ratios in interferometry. Cat states are very sensitive to decoherence, and as a result their preparation is challenging and can serve as a demonstration of good quantum control. Here we report the creation of cat states of up to six atomic qubits. Each qubit's state space is defined by two hyperfine ground states of a beryllium ion; the cat state corresponds to an entangled equal superposition of all the atoms in one hyperfine state and all atoms in the other hyperfine state. In our experiments, the cat states are prepared in a three-step process, irrespective of the number of entangled atoms. Together with entangled states of a different class created in Innsbruck, this work represents the current state-of-the-art for large entangled states in any qubit system. PMID:16319885
Radio-frequency dressed state potentials for neutral atoms
S. Hofferberth; I. Lesanovsky; B. Fischer; J. Verdu; J. Schmiedmayer
2006-08-29
Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronically excited states of an atom with light. Here we present an experimental investigation of the remarkable properties of potentials derived from radio-frequency (RF) coupling between electronic ground states. The coupling is magnetic and the vector character allows to design state dependent potential landscapes. On atom chips this enables robust coherent atom manipulation on much smaller spatial scales than possible with static fields alone. We find no additional heating or collisional loss up to densities approaching $10^{15}$ atoms / cm$^3$ compared to static magnetic traps. We demonstrate the creation of Bose-Einstein condensates in RF potentials and investigate the difference in the interference between two independently created and two coherently split condensates in identical traps. All together this makes RF dressing a powerful new tool for micro manipulation of atomic and molecular systems.
Ground state of a dipolar crystal
Gross; Wei
2000-02-01
We provide some of the strongest evidence to date that the ground state structure of an infinite collection of point dipoles with hardcore sphere interactions is body-centered tetragonal. The structure with the next highest binding energy is not face-centered cubic; a particular honeycomb structure has lower energy. PMID:11046504
Quantum State Tomography of Cold Atom Qudits
NASA Astrophysics Data System (ADS)
Sosa Martinez, Hector; Lysne, Nathan; Jessen, Poul; Baldwin, Charles; Kalev, Amir; Deutsch, Ivan
2015-05-01
Accurate and robust control over quantum systems plays a key role in quantum information science. The use of systems with large state spaces (qudits) may prove a useful resource for quantum information tasks if good laboratory tools for qudit manipulation and measurement can be developed. Over the past few years we have developed and experimentally implemented a protocol to perform high-fidelity unitary transformations in the 16 dimensional hyperfine ground manifold of Cesium-133 atoms, driving the system with phase modulated radio-frequency and microwave magnetic fields and using the tools of optimal control to find appropriate control waveforms. We have recently extended our protocol to investigate quantum state tomography based on a combination of unitary transformations and Stern-Gerlach analysis. Experimental results shown that optimal tomography based on mutually-unbiased-bases (MUBs) can be implemented, with reconstruction fidelities on the order of 99% for arbitrarily chosen test states in a 16-dimensional Hilbert space. We are also interested in the characterization of our measurement detector for which we plan to perform POVM tomography. Ultimately, successful implementation of this kind of state tomography may prove very valuable, greatly reducing the required data for more complex procedures such as quantum process tomography.
Simulation of the hydrogen ground state in stochastic electrodynamics
NASA Astrophysics Data System (ADS)
Nieuwenhuizen, Theo M.; Liska, Matthew T. P.
2015-10-01
Stochastic electrodynamics is a classical theory which assumes that the physical vacuum consists of classical stochastic fields with average energy \\frac{1}{2}{{\\hslash }}? in each mode, i.e., the zero-point Planck spectrum. While this classical theory explains many quantum phenomena related to harmonic oscillator problems, hard results on nonlinear systems are still lacking. In this work the hydrogen ground state is studied by numerically solving the Abraham-Lorentz equation in the dipole approximation. First the stochastic Gaussian field is represented by a sum over Gaussian frequency components, next the dynamics is solved numerically using OpenCL. The approach improves on work by Cole and Zou 2003 by treating the full 3d problem and reaching longer simulation times. The results are compared with a conjecture for the ground state phase space density. Though short time results suggest a trend towards confirmation, in all attempted modellings the atom ionises at longer times.
Narrow deeply bound $K^-$ atomic states
E. Friedman; A. Gal
1999-05-30
Using optical potentials fitted to a comprehensive set of strong interaction level shifts and widths in $K^-$ atoms, we predict that the $K^-$ atomic levels which are inaccessible in the atomic cascade process are generally narrow, spanning a range of widths about 50 - 1500 keV over the entire periodic table. The mechanism for this narrowing is different from the mechanism for narrowing of pionic atom levels. Examples of such `deeply bound' $K^-$ atomic states are given, showing that in many cases these states should be reasonably well resolved. Several reactions which could be used to form these `deeply bound' states are mentioned. Narrow deeply bound states are expected also in $\\bar{p}$ atoms.
Ground states of spin-2 condensates in an external magnetic field
Zheng, G.-P.; Tong, Y.-G.; Wang, F.-L.
2010-06-15
The possible ground states of spin-2 Bose-Einstein condensates in an external magnetic field are obtained analytically and classified systematically according to the population of the condensed atoms at the hyperfine sublevels. It is shown that the atoms can populate simultaneously at four hyperfine sublevels in a weak magnetic field with only the linear Zeeman energy, in contrast to that in a stronger magnetic field with the quadratic Zeeman energy, where condensed atoms can at most populate at three hyperfine sublevels in the ground states. Any spin configuration we obtained will give a closed subspace in the order parameter space of the condensates.
Quantum state reconstruction on atom-chips
NASA Astrophysics Data System (ADS)
Lovecchio, C.; Cherukattil, S.; Cilenti, B.; Herrera, I.; Cataliotti, F. S.; Montangero, S.; Calarco, T.; Caruso, F.
2015-09-01
We realize on an atom-chip, a practical, experimentally undemanding, tomographic reconstruction algorithm relying on the time-resolved measurements of the atomic population distribution among atomic internal states. More specifically, we estimate both the state density matrix, as well as the dephasing noise present in our system, by assuming complete knowledge of the Hamiltonian evolution. The proposed scheme is based on routinely performed measurements and established experimental procedures, hence providing a simplified methodology for quantum technological applications.
Weak value amplification of atomic cat states
NASA Astrophysics Data System (ADS)
Huang, Sumei; Agarwal, Girish S.
2015-09-01
We show the utility of the weak value amplification to observe the quantum interference between two close lying atomic coherent states in a post-selected atomic cat state, produced in a system of N identical two-level atoms weakly interacting with a single photon field. Through the observation of the negative parts of the Wigner distribution of the post-selected atomic cat state, we find that the post-selected atomic cat state becomes more nonclassical when the post-selected polarization state of the single photon field tends toward becoming orthogonal to its pre-selected state. We show that the small phase shift in the post-selected atomic cat state can be amplified via measuring the peak shift of its phase distribution when the post-selected state of the single photon field is nearly orthogonal to its pre-selected state. We find that the amplification factor of 15 [5] can be obtained for a sample of 10 [100] atoms. This effectively provides us with a method to discriminate between two close lying states on the Bloch sphere. We discuss possible experimental implementation of the scheme, and conclude with a discussion of the Fisher information.
Weak value amplification of atomic cat states
Sumei Huang; Girish S. Agarwal
2015-09-09
We show the utility of the weak value amplification to observe the quantum interference between two close lying atomic coherent states in a post-selected atomic cat state, produced in a system of $N$ identical two-level atoms weakly interacting with a single photon field. Through the observation of the negative parts of the Wigner distribution of the post-selected atomic cat state, we find that the post-selected atomic cat state becomes more nonclassical when the post-selected polarization state of the single photon field tends toward becoming orthogonal to its pre-selected state. We show that the small phase shift in the post-selected atomic cat state can be amplified via measuring the peak shift of its phase distribution when the post-selected state of the single photon field is nearly orthogonal to its pre-selected state. We find that the amplification factor of 15 [5] can be obtained for a sample of 10 [100] atoms. This effectively provides us with a method to discriminate two close lying states on the Bloch sphere. We discuss possible experimental implementation of the scheme, and conclude with a discussion of the Fisher information.
Ground state searches in fcc intermetallics
Wolverton, C.; de Fontaine, D.; Ceder, G.; Dreysse, H.
1991-12-01
A cluster expansion is used to predict the fcc ground states, i.e., the stable phases at zero Kelvin as a function of composition, for alloy systems. The intermetallic structures are not assumed, but derived regorously by minimizing the configurational energy subject to linear constraints. This ground state search includes pair and multiplet interactions which spatially extend to fourth nearest neighbor. A large number of these concentration-independent interactions are computed by the method of direct configurational averaging using a linearized-muffin-tin orbital Hamiltonian cast into tight binding form (TB-LMTO). The interactions, derived without the use of any adjustable or experimentally obtained parameters, are compared to those calculated via the generalized perturbation method extention of the coherent potential approximation within the context of a KKR Hamiltonian (KKR-CPA-GPM). Agreement with the KKR-CPA-GPM results is quite excellent, as is the comparison of the ground state results with the fcc-based portions of the experimentally-determined phase diagrams under consideration.
Programmable solid state atom sources for nanofabrication.
Han, Han; Imboden, Matthias; Stark, Thomas; del Corro, Pablo G; Pardo, Flavio; Bolle, Cristian A; Lally, Richard W; Bishop, David J
2015-06-28
In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ?1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques. PMID:26030007
NASA Astrophysics Data System (ADS)
Suzuki, Yoshi-ichi; Asai, Shigeko; Kobayashi, Katsushi; Noro, Takeshi; Sasaki, Fukashi; Tatewaki, Hiroshi
1997-04-01
Global potential curves have been obtained for the ground state and low-lying states of the Sc dimer with state averaged complete active space self-consistent field and multireference configuration interaction calculations. The obtained curves are smooth over a wide range of internuclear distances. The calculated spectroscopic constants of the ground state agree well with experiment. The configurations arising from the 4F + 4F atomic limit become predominant in the bonding region for the second and third states.
Condensed ground states of frustrated Bose-Hubbard models
Moeller, G.; Cooper, N. R.
2010-12-15
We study theoretically the ground states of two-dimensional Bose-Hubbard models which are frustrated by gauge fields. Motivated by recent proposals for the implementation of optically induced gauge potentials, we focus on the situation in which the imposed gauge fields give rise to a pattern of staggered fluxes of magnitude {alpha} and alternating in sign along one of the principal axes. For {alpha}=1/2 this model is equivalent to the case of uniform flux per plaquette n{sub {phi}=}1/2, which, in the hard-core limit, realizes the 'fully frustrated' spin-1/2 XY model. We show that the mean-field ground states of this frustrated Bose-Hubbard model typically break translational symmetry. Given the presence of both a non-zero superfluid fraction and translational symmetry breaking, these phases are supersolid. We introduce a general numerical technique to detect broken symmetry condensates in exact diagonalization studies. Using this technique we show that, for all cases studied, the ground state of the Bose-Hubbard model with staggered flux {alpha} is condensed, and we obtain quantitative determinations of the condensate fraction. We discuss the experimental consequences of our results. In particular, we explain the meaning of gauge invariance in ultracold-atom systems subject to optically induced gauge potentials and show how the ability to imprint phase patterns prior to expansion can allow very useful additional information to be extracted from expansion images.
The rotational levels of the ground vibrational state of formaldehyde
NASA Astrophysics Data System (ADS)
Handy, Stuart Carter Nicholas C.; Demaison, Jean
A variational procedure for rovibrational energy levels and wavefunctions of centrally connected tetra-atomic molecules is extended to include high rotational states, and in particular, J 10 levels for the vibrational ground state of formaldehyde. It is very important to do this because it has made possible the calculation of the usual rotational spectroscopic constants which correspond to the forcefield and geometry. A direct comparison with the 'observed' spectroscopic constants is therefore possible. The geometry and forcefield are refined against 65 J = 0 levels of H2CO, 6 J = 0 levels of D2CO, 42 J = 1, 70 J = 2 and 98 J = 3 levels of the ground and fundamentals of H2CO a-n 1d D2CO, using an iterative schem-e1. The mean absolute error of the J = 0 levels is 1.10 cm and that for J = / 0 is 0.005 cm , and the predicted geometry is CH = 1.10064 A, CO = 1.20296 A and HCO = 121.648o. Finally, the rotational constants A, B, and C for the ground state are 281 956, 38846 and 34003 MHz, compared with the observed values 281 971, 38 836, and 34 002 MHz. The centrifugal distortion constants J, JK, K and deltaJ, are 77, 1275, 18 113 and 11 kHz compared with 75, 1291, 19 422 and 10 kHz. These results underline the accuracy of the new quartic forcefield.
Pachucki, Krzysztof
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
Proteome Analysis of Ground State Pluripotency
Taleahmad, Sara; Mirzaei, Mehdi; Parker, Lindsay M.; Hassani, Seyedeh-Nafiseh; Mollamohammadi, Sepideh; Sharifi-Zarchi, Ali; Haynes, Paul A.; Baharvand, Hossein; Salekdeh, Ghasem Hosseini
2015-01-01
The differentiation potential of pluripotent embryonic stem cells (ESCs) can be manipulated via serum and medium conditions for direct cellular development or to maintain a naïve ground state. The self-renewal state of ESCs can thus be induced by adding inhibitors of mitogen activated protein kinase (MAPK) and glycogen synthase kinase-3 (Gsk3), known as 2 inhibitors (2i) treatment. We have used a shotgun proteomics approach to investigate differences in protein expressions between 2i- and serum-grown mESCs. The results indicated that 164 proteins were significantly upregulated and 107 proteins downregulated in 2i-grown cells compared to serum. Protein pathways in 2i-grown cells with the highest enrichment were associated with glycolysis and gluconeogenesis. Protein pathways related to organ development were downregulated in 2i-grown cells. In serum-grown ESCs, protein pathways involved in integrin and focal adhesion, and signaling proteins involved in the actin cytoskeleton regulation were enriched. We observed a number of nuclear proteins which were mostly involved in self-renewal maintenance and were expressed at higher levels in 2i compared to serum - Dnmt1, Map2k1, Parp1, Xpo4, Eif3g, Smarca4/Brg1 and Smarcc1/Baf155. Collectively, the results provided an insight into the key protein pathways used by ESCs in the ground state or metastable conditions through 2i or serum culture medium, respectively. PMID:26671762
Proteome Analysis of Ground State Pluripotency.
Taleahmad, Sara; Mirzaei, Mehdi; Parker, Lindsay M; Hassani, Seyedeh-Nafiseh; Mollamohammadi, Sepideh; Sharifi-Zarchi, Ali; Haynes, Paul A; Baharvand, Hossein; Salekdeh, Ghasem Hosseini
2015-01-01
The differentiation potential of pluripotent embryonic stem cells (ESCs) can be manipulated via serum and medium conditions for direct cellular development or to maintain a naïve ground state. The self-renewal state of ESCs can thus be induced by adding inhibitors of mitogen activated protein kinase (MAPK) and glycogen synthase kinase-3 (Gsk3), known as 2 inhibitors (2i) treatment. We have used a shotgun proteomics approach to investigate differences in protein expressions between 2i- and serum-grown mESCs. The results indicated that 164 proteins were significantly upregulated and 107 proteins downregulated in 2i-grown cells compared to serum. Protein pathways in 2i-grown cells with the highest enrichment were associated with glycolysis and gluconeogenesis. Protein pathways related to organ development were downregulated in 2i-grown cells. In serum-grown ESCs, protein pathways involved in integrin and focal adhesion, and signaling proteins involved in the actin cytoskeleton regulation were enriched. We observed a number of nuclear proteins which were mostly involved in self-renewal maintenance and were expressed at higher levels in 2i compared to serum - Dnmt1, Map2k1, Parp1, Xpo4, Eif3g, Smarca4/Brg1 and Smarcc1/Baf155. Collectively, the results provided an insight into the key protein pathways used by ESCs in the ground state or metastable conditions through 2i or serum culture medium, respectively. PMID:26671762
D. O'Donnell; R. D. Page; C. Scholey; L. Bianco; L. Capponi; R. J. Carroll; I. G. Darby; L. Donosa; M. Drummond; F. Ertugral; P. T. Greenlees; T. Grahn; K. Hauschild; A. Herzan; U. Jakobsson; P. Jones; D. T. Joss; R. Julin; S. Juutinen; S. Ketelhut; M. Labiche; M. Leino; A. Lopez-Martens; K. Mullholland; P. Nieminen; P. Peura; P. Rahkila; S. Rinta-Antila; P. Ruotsalainen; M. Sandzelius; J. Saren; B. Saygi; J. Simpson; J. Sorri; A. Thornthwaite; J. Uusitalo
2012-12-19
The a-decay chains originating from the s1/2 and h11/2 states in 173Au have been investigated following fusion-evaporation reactions. Four generations of a radioactivities have been correlated with 173Aum leading to a measurement of the a decay of 161Tam. It has been found that the known a decay of 161Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt g rays feeding the ground state of 173Au. This prompt radiation was used to aid the study of the a-decay chain originating from the s1/2 state in 173Au. Three generations of a decays have been correlated with this state leading to the observation of a previously unreported activity which is assigned as the decay of 165Reg. This work also reports the excitation energy of an a-decaying isomer in 161Ta and the Q-value of the decay of 161Tag.
Geometric renormalization below the ground state
Paul Smith
2011-12-06
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.
Unusual Classical Ground States of Matter Salvatore Torquato
Torquato, Salvatore
Unusual Classical Ground States of Matter Salvatore Torquato Department of Chemistry, Princeton;Volume Temperature rapid quench glass super- cooled liquid liquid freezing point (Tf) glass transition (Tg) crystal very slow cooling . p. 2/32 #12;Classical Ground States · Classical ground states
New Duality Relations for Classical Ground States S. Torquato
Stillinger, Frank
.50.Ah, 82.35.Jk, 82.70.Dd While classical ground states are readily produced by slowly freezing liquidsNew Duality Relations for Classical Ground States S. Torquato School of Natural Sciences, Institute the classical ground states of short-ranged potentials can be used to draw new conclusions about the nature
Preparation and determination of spin-polarized states in multi-Zeeman-sublevel atoms
Wang, Bo; Han, Yanxu; Xiao, Jintao; Yang, Xudong; Zhang, Chunhong; Wang, Hai; Peng, Kunchi; Xiao, Min
2007-05-15
We demonstrate a simple, all-optical technique to prepare and determine the desired internal quantum states in multi-Zeeman-sublevel atoms. By choosing appropriate coupling and pumping laser beams, atoms can be easily prepared in a desired Zeeman sublevel with high purity or in any chosen ground-state population distributions (spin-polarized quantum-state engineering). The population distributions or state purities of such prepared atomic states can be determined by using a weak, circularly polarized probe beam due to differences in transition strengths among different Zeeman sublevels. This technique will have potential impact on quantum-information processing in multilevel atomic systems.
Ground-state structures of Hafnium clusters
Ng, Wei Chun; Yoon, Tiem Leong; Lim, Thong Leng
2015-04-24
Hafnium (Hf) is a very large tetra-valence d-block element which is able to form relatively long covalent bond. Researchers are interested to search for substitution to silicon in the semi-conductor industry. We attempt to obtain the ground-state structures of small Hf clusters at both empirical and density-functional theory (DFT) levels. For calculations at the empirical level, charge-optimized many-body functional potential (COMB) is used. The lowest-energy structures are obtained via a novel global-minimum search algorithm known as parallel tempering Monte-Carlo Basin-Hopping and Genetic Algorithm (PTMBHGA). The virtue of using COMB potential for Hf cluster calculation lies in the fact that by including the charge optimization at the valence shells, we can encourage the formation of proper bond hybridization, and thus getting the correct bond order. The obtained structures are further optimized using DFT to ensure a close proximity to the ground-state.
Beyond pure state entanglement for atomic ensembles
NASA Astrophysics Data System (ADS)
Stasi?ska, Julia; Paganelli, Simone; Sanpera, Anna
2012-03-01
We analyze multipartite entanglement between atomic ensembles within quantum matter-light interfaces. In our proposal, a polarized light beam crosses sequentially several polarized atomic ensembles impinging on each of them at a given angle ?i. These angles are crucial parameters for shaping the entanglement since they are directly connected to the appropriate combinations of the collective atomic spins that are squeezed. We exploit such a scheme to go beyond the pure state paradigm proposing realistic experimental settings to address multipartite mixed state entanglement in continuous variables.
Sideband cooling of micromechanical motion to the quantum ground state.
Teufel, J D; Donner, T; Li, Dale; Harlow, J W; Allman, M S; Cicak, K; Sirois, A J; Whittaker, J D; Lehnert, K W; Simmonds, R W
2011-07-21
The advent of laser cooling techniques revolutionized the study of many atomic-scale systems, fuelling progress towards quantum computing with trapped ions and generating new states of matter with Bose-Einstein condensates. Analogous cooling techniques can provide a general and flexible method of preparing macroscopic objects in their motional ground state. Cavity optomechanical or electromechanical systems achieve sideband cooling through the strong interaction between light and motion. However, entering the quantum regime--in which a system has less than a single quantum of motion--has been difficult because sideband cooling has not sufficiently overwhelmed the coupling of low-frequency mechanical systems to their hot environments. Here we demonstrate sideband cooling of an approximately 10-MHz micromechanical oscillator to the quantum ground state. This achievement required a large electromechanical interaction, which was obtained by embedding a micromechanical membrane into a superconducting microwave resonant circuit. To verify the cooling of the membrane motion to a phonon occupation of 0.34?±?0.05 phonons, we perform a near-Heisenberg-limited position measurement within (5.1?±?0.4)h/2?, where h is Planck's constant. Furthermore, our device exhibits strong coupling, allowing coherent exchange of microwave photons and mechanical phonons. Simultaneously achieving strong coupling, ground state preparation and efficient measurement sets the stage for rapid advances in the control and detection of non-classical states of motion, possibly even testing quantum theory itself in the unexplored region of larger size and mass. Because mechanical oscillators can couple to light of any frequency, they could also serve as a unique intermediary for transferring quantum information between microwave and optical domains. PMID:21734657
Programmable solid state atom sources for nanofabrication
NASA Astrophysics Data System (ADS)
Han, Han; Imboden, Matthias; Stark, Thomas; Del Corro, Pablo G.; Pardo, Flavio; Bolle, Cristian A.; Lally, Richard W.; Bishop, David J.
2015-06-01
In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ~1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques.In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ~1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques. Electronic supplementary information (ESI) available: A document containing further information about device characterization, summary of the evaporation experiments, technical details and data analysis of the measurement is supplied as ESI. In addition, three video files are included. One illustrates the operation of the source array and the other two are SEM videos of the dynamic process of silver evaporating on the source plate. See DOI: 10.1039/c5nr01331c
NASA Astrophysics Data System (ADS)
Bubin, Sergiy; Adamowicz, Ludwik
2011-12-01
In this article we report accurate nonrelativistic variational calculations of the ground and two excited states of C+ ion. We employ extended and well optimized basis sets of all-electron explicitly correlated Gaussians to represent the wave functions of the states. The optimization of the basis functions is performed with a procedure employing the analytic gradient of the energy with respect to the nonlinear parameters of the Gaussians. The calculations explicitly include the effects due to the finite nuclear mass. The calculated transition energies between the three states are compared to the experimentally derived values. Finally, we present expectation values of some small positive and negative powers of the interparticle distances and contact densities.
Scattering length of the ground-state MgMg collision E. Tiesinga, S. Kotochigova, and P. S. Julienne
Kotochigova, Svetlana
can be magneto- optically trapped. This offers many possible applications of cold Mg atoms for ultra coefficients. At temperatures below 5 mK ground state Mg collisions are in the s-wave scattering regime
Ground state of high-density matter
NASA Technical Reports Server (NTRS)
Copeland, ED; Kolb, Edward W.; Lee, Kimyeong
1988-01-01
It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.
Thermodynamic ground states of platinum metal nitrides
Aberg, D; Sadigh, B; Crowhurst, J; Goncharov, A
2007-10-09
We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.
Creating collective many-body states with highly excited atoms
B. Olmos; R. González-Férez; I. Lesanovsky
2009-11-12
We study the collective excitation of a gas of highly excited atoms confined to a large spacing ring lattice, where the ground and the excited states are coupled resonantly via a laser field. Our attention is focused on the regime where the interaction between the highly excited atoms is very weak in comparison to the Rabi frequency of the laser. We demonstrate that in this case the many-body excitations of the system can be expressed in terms of free spinless fermions. The complex many-particle states arising in this regime are characterized and their properties, e.g. their correlation functions, are studied. In addition we investigate how one can actually experimentally access some of these many-particle states by a temporal variation of the laser parameters.
Creating collective many-body states with highly excited atoms
Olmos, B.; Gonzalez-Ferez, R.; Lesanovsky, I.
2010-02-15
The collective excitation of a gas of highly excited atoms confined to a large spacing ring lattice is studied, where the ground and the excited states are resonantly coupled via a laser field. Attention is focused on the regime where the interaction between the highly excited atoms is very weak in comparison to the Rabi frequency of the laser. In this case, the many-body excitations of the system can be expressed in terms of free spinless fermions. The complex many-particle states arising in this regime are characterized and their properties, for example their correlation functions, are studied. Additional investigation into how some of these many-particle states can actually be experimentally accessed by a temporal variation of the laser parameters is performed.
Color Neutral Ground State of 2SC Quark Matter
D. Blaschke; D. Gómez Dumm; A. G. Grunfeld; N. N. Scoccola
2005-07-25
We construct a new color neutral ground state of two-flavor color superconducting quark matter. It is shown that, in contrast with the conventionally considered ground state with diquark pairing in only one color direction, this new state is stable against arbitrary diquark fluctuations. In addition, the thermodynamical potential is found to be lower for this new state than for the conventional one.
The nature of binding in the ground state of the scandium dimer
NASA Astrophysics Data System (ADS)
Miranda, U.; Kaplan, I. G.
2011-07-01
For the study of the nature of binding in the Sc2 dimer, the ground state, X5? u -, was calculated by the valence multireference configuration interaction method with single and double excitations plus Davidson correction, MRCISD (+Q), at the complete basis set (CBS) limit. The employment of the C2 v symmetry group, allowed us to obtain the Sc atoms in different states at the dissociation limit. From the Mulliken population analysis and comparison with atomic energies follows that in the ground state Sc2 dissociates on one Sc in the ground state and the other in the second excited quartet state, 4F u . The spectroscopic parameters of the ground potential curve, obtained at the valence MRCISD (+Q)/CBS level, are: R e = 5.20 bohr, D e = 50.37 kcal/mol, and ? e = 234.5 cm-1. The obtained value for the harmonic frequency agrees very well with the experimental one, ? e = 239.9 cm-1. The dissociation energy with reference to the dissociation on two Sc in the ground states was estimated as D e = 9.98 kcal/mol. In contrast with many other studied transition-metal dimers, which are attributed to the van der Waals bonded molecules, the Sc2 dimer is stabilized by the covalent bonding on the hybrid atomic orbitals.
Engineering the Ground State of Complex Oxides
NASA Astrophysics Data System (ADS)
Meyers, Derek Joseph
Transition metal oxides featuring strong electron-electron interactions have been at the forefront of condensed matter physics research in the past few decades due to the myriad of novel and exciting phases derived from their competing interactions. Beyond their numerous intriguing properties displayed in the bulk they have also shown to be quite susceptible to externally applied perturbation in various forms. The dominant theme of this work is the exploration of three emerging methods for engineering the ground states of these materials to access both their applicability and their deficiencies. The first of the three methods involves a relatively new set of compounds which adhere to a unique paradigm in chemical doping, a-site ordered perovskites. These compounds are iso-structural, i.e. constant symmetry, despite changing the dopant ions. We find that these materials, featuring Cu at the doped A-site, display the Zhang-Rice state, to varying degrees, found in high temperature superconducting cuprates, with the choice of B-site allowing "self-doping" within the material. Further, we find that within CaCu3Ir 4O12 the Cu gains a localized magnetic moment and leads to the experimentally observed heavy fermion state in the materials, one of only two such non-f-electron heavy fermion materials. Next, epitaxial constraint is used to modify the ground state of the rare-earth nickelates in ultra thin film form. Application of compressive (tensile) strain is found to suppress (maintain) the temperature at which the material goes through a Mott metal-insulator transition. Further, while for EuNiO3 thin films the typical bulk-like magnetic and charge ordering is found to occur, epitaxial strain is found to suppress the charge ordering in NdNiO3 thin films due to pinning to the substrate and the relatively weak tendency to monoclinically distort. Finally, the creation of superlattices of EuNiO3 and LaNiO3 was shown to not only allow the selection of the temperature at which the metal-insulator transition occurs, but through digital control the Ni site symmetry can be artificially broken leading to a previously unseen monoclinic metallic phase. Further, by creating a structure which does or does not match the bulk-like rock salt charge order pattern it was found this transition can be either strongly enhanced or removed entirely.
Creating and probing coherent atomic states
Reinhold, C.O.; Burgdoerfer, J. |; Frey, M.T.; Dunning, F.B.
1997-06-01
The authors present a brief review of recent experimental and theoretical time resolved studies of the evolution of atomic wavepackets. In particular, wavepackets comprising a superposition of very-high-lying Rydberg states which are created either using a short half-cycle pulse (HCP) or by rapid application of a DC field. The properties of the wavepackets are probed using a second HCP that is applied following a variable time delay and ionizes a fraction of the atoms, much like a passing-by ion in atomic collisions.
Fisher-like atomic divergences: Mathematical grounds and physical applications
NASA Astrophysics Data System (ADS)
Martín, A. L.; Angulo, J. C.; Antolín, J.
2013-11-01
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.
Driving to the steady ground-state superposition assisted by spontaneous emission
NASA Astrophysics Data System (ADS)
Chen, Ming-Feng; Shen, Li-Tuo; Chen, Rong-Xin; Yang, Zhen-Biao
2015-09-01
We propose a scheme for preparing a coherent ground-state superposition for an atom through external drivings assisted by spontaneous emission. In the scheme, the dynamics induced by the competition between the spontaneous emission and the external drives contributes to the superposition of the ground states. Compared with schemes based on the stimulated Raman adiabatic passage, such a scheme is more easily implemented because the preparation of special initial states is no longer needed, which simplifies the operation process. Moreover, since spontaneous emission is involved to act as a positive factor, a higher fidelity superposition state is achieved.
Bichromatic State-insensitive Trapping of Caesium Atoms
Metbulut, M M
2015-01-01
State-insensitive dipole trapping of multilevel atoms can be achieved by an appropriate choice of the wavelength of the trapping laser, so that the interaction with the different transitions results in equal AC Stark shifts for the ground and excited states of interest. However this approach is severely limited by the availability of coherent sources at the required wavelength and of appropriate power. This work investigates state-insensitive trapping of caesium atoms for which the required wavelength of 935.6 nm is inconvenient in terms of experimental realization. Bichromatic state-insensitive trapping is proposed to overcome the lack of suitable laser sources. We first consider pairs of laser wavelengths in the ratio 1:2 and 1:3, as obtained via second- and third- harmonic generation. We found that the wavelength combinations 931.8-1863.6 nm and 927.5-2782.5 nm are suitable for state-insensitive trapping of caesium atoms. In addition, we examine bichromatic state-insensitive trapping produced by pairs of l...
B2N2O4: Prediction of a Magnetic Ground State for a Light Main-Group Molecule
Varga, Zoltan; Truhlar, Donald G.
2015-09-08
Cyclobutanetetrone, (CO)4, has a triplet ground state. Here we predict, based on electronic structure calculations, that the B2N2O4 molecule also has a triplet ground state and is therefore paramagnetic; the structure is an analogue of (CO)4 in which the carbon ring is replaced by a (BN)2 ring. Similar to (CO)4, the triplet ground-state structure of B2N2O4 is also thermodynamically unstable. Besides analysis of the molecular orbitals, we found that the partial atomic charges are good indicators for predicting magnetic ground states.
Perspectives for coherent optical formation of strontium molecules in their electronic ground state
Koch, Christiane
Perspectives for coherent optical formation of strontium molecules in their electronic ground state . The present study focuses on strontium and addresses the question of how to produce dimer molecules atomic resonance was observed for calcium 16 , strontium 17,18 , and ytterbium 19 . Near the narrow- line
Weatherall, James Owen; Search, Christopher P.
2010-02-15
Transparent media exhibiting anomalous dispersion have been of considerable interest since Wang, Kuzmich, and Dogariu [Nature 406, 277 (2000)] first observed light propagate with superluminal and negative group velocities without absorption. Here, we propose an atomic model exhibiting these properties, based on a generalization of amplification without inversion in a five-level dressed interacting ground-state system. The system consists of a {Lambda} atom prepared as in standard electromagnetically induced transparency (EIT), with two additional metastable ground states coupled to the {Lambda} atom ground states by two rf-microwave fields. We consider two configurations by which population is incoherently pumped into the ground states of the atom. Under appropriate circumstances, we predict a pair of new gain lines with tunable width, separation, and height. Between these lines, absorption vanishes but dispersion is large and anomalous. The system described here is a significant improvement over other proposals in the anomalous dispersion literature in that it permits additional coherent control over the spectral properties of the anomalous region, including a possible 10{sup 4}-fold increase over the group delay observed by Wang, Kuzmich, and Dogariu.
Colour polymeric paints research under atomic oxygen in flight and ground-based experiments
NASA Astrophysics Data System (ADS)
Chernik, V. N.; Naumov, S. F.; Sokolova, S. P.; Gerasimova, T. I.; Kurilyonok, A. O.; Poruchikova, Ju. V.; Novikova, V. A.
2003-09-01
Three types of colour coatings were tested to atomic oxygen resistance on ground-based and in-flight experiments. The epoxy enamels colouring change and significant mass losses are observed. The effect of atomic oxygen on silicone enamels almost does not change their colouring and mass. Protection of the epoxy enamels by a layer of silicone varnish increases paints resistance.
The ground state construction of bilayer graphene
Alessandro Giuliani; Ian Jauslin
2015-07-31
We consider a model of half-filled bilayer graphene, in which the three dominant Slonczewski-Weiss-McClure hopping parameters are retained, in the presence of short range interactions. Under a smallness assumption on the interaction strength $U$ as well as on the inter-layer hopping $\\epsilon$, we construct the ground state in the thermodynamic limit, and prove its analyticity in $U$, uniformly in $\\epsilon$. The interacting Fermi surface is degenerate, and consists of eight Fermi points, two of which are protected by symmetries, while the locations of the other six are renormalized by the interaction, and the effective dispersion relation at the Fermi points is conical. The construction reveals the presence of different energy regimes, where the effective behavior of correlation functions changes qualitatively. The analysis of the crossover between regimes plays an important role in the proof of analyticity and in the uniform control of the radius of convergence. The proof is based on a rigorous implementation of fermionic renormalization group methods, including determinant estimates for the renormalized expansion.
Cold Rydberg atoms in circular states
NASA Astrophysics Data System (ADS)
Anderson, David; Schwarzkopf, Andrew; Raithel, Georg
2012-06-01
Circular-state Rydberg atoms are interesting in that they exhibit a unique combination of extraordinary properties; long lifetimes (˜n^5), large magnetic moments (l=|m|=n-1) and no first order Stark shift. Circular states have found applications in cavity quantum electrodynamics and precision measurements [1,2], among other studies. In this work we present the production of circular states in an atom trapping apparatus using an adiabatic state-switching method (the crossed-field method [3]). To date, we have observed lifetimes of adiabatically prepared states of several milliseconds. Their relatively large ionization electric fields have been verified by time-of-flight signatures of ion trajectories. We intend to explore the magnetic trapping of circular state Rydberg atoms, as well as their production and interaction properties in ultra-cold and degenerate samples.[4pt] [1] P. Bertet et al., Phys. Rev. Lett., 88, 14 (2002)[0pt] [2] M. Brune et al., Phys. Rev. Lett., 72, 21 (1994)[0pt] [3] D. Delande and J.C. Gay, Europhys. Lett., 5, 303-308 (1988).
XUV frequency comb metrology on the ground state of helium
Kandula, Dominik Z; Pinkert, Tjeerd J; Ubachs, Wim; Eikema, Kjeld S E
2011-01-01
The operation of a frequency comb at extreme ultraviolet (XUV) wavelengths based on pair-wise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency comb laser in the near-infrared range is reported. Following a first account of the experiment [Kandula et al., Phys. Rev. Lett. 105, 063001 (2010)], an extensive review is given of the demonstration that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p 1P_1 states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure yields an estimated timing jitter between the two upconverted comb laser pulses of 50 attoseconds, whch indicates that e...
Dimerized ground state in the one-dimensional spin-1 boson Hubbard model
Apaja, Vesa; Syljuaasen, Olav F.
2006-09-15
We have investigated the one-dimensional spin-1 boson Hubbard model with antiferromagnetic interactions using quantum Monte Carlo methods. We obtain the shapes of the two lowest Mott lobes and show that the ground state within the lowest Mott lobe is dimerized. The results presented here are relevant for optically trapped antiferromagnetic spin-1 bosons. An experimental signature of the dimerized ground state is modulated Bragg peaks in the noise distribution of the atomic cloud obtained after switching off the trap. These Bragg peaks are located at wave vectors corresponding to half-integer multiples of the reciprocal wave vector of the optical lattice.
Dissociative recombination of the ground state of N2(+)
NASA Technical Reports Server (NTRS)
Guberman, Steven L.
1991-01-01
Large-scale calculations of the dissociative recombination cross sections and rates for the v = 0 level of the N2(+) ground state are reported, and the important role played by vibrationally excited Rydberg states lying both below and above the v = 0 level of the ion is demonstrated. The large-scale electronic wave function calculations were done using triple zeta plus polarization nuclear-centered-valence Gaussian basis sets. The electronic widths were obtained using smaller wave functions, and the cross sections were calculated on the basis of the multichannel quantum defect theory. The DR rate is calculated at 1.6 x 10 to the -7th x (Te/300) to the -0.37 cu cm/sec for Te in the range of 100 to 1000 K, and is found to be in excellent agreement with prior microwave afterglow experiments but in disagreement with recent merged beam results. It is inferred that the dominant mechanism for DR imparts sufficient energy to the product atoms to allow for escape from the Martian atmosphere.
A resonant state and the ground state of positronium hydride
NASA Technical Reports Server (NTRS)
Ho, Y. K.
1978-01-01
The lowest-lying resonance occurring in S-wave positronium-hydrogen scattering is reinvestigated, using the complex-rotation method. By employing a generalized Hylleraas-type wave function that includes all six interparticle coordinates, a very accurate value of the resonance position is obtained, along with a good value of the width. The present result for the resonance position (-1.205 plus or minus 0.001 Ry) is lower than the previous result of Drachman and Houston, who omitted the interelectronic coordinate in their trial function. In addition, the lowest ground-state energy of positronium hydride is obtained by using 210 terms in the trial wave function. The effect of the interelectronic coordinate and others on both the resonant energy and the binding energy of PsH is discussed.
2010-01-01
G magnetic field. The nonlinearity of rotation results from long-lived coherence of ground-state Zeeman the Doppler effect broadens the range of the magnetic fields where the effect is visible and reduces the size superpositions of Zeeman sublevels of an atomic ground state. Such superpositions (Zeeman coher- ences) result
Ensemble Theory for Stealthy Hyperuniform Disordered Ground States
S. Torquato; G. Zhang; F. H. Stillinger
2015-06-01
It has been shown numerically that systems of particles interacting with "stealthy" bounded, long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are, counterintuitively, disordered, hyperuniform and highly degenerate. Disordered hyperuniform systems have been receiving recent attention because they are distinguishable exotic states of matter poised between a crystal and liquid with novel properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in $d$-dimensional Euclidean space is highly nontrivial because the dimensionality of the configuration space depends on the number density $\\rho$ and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties that apply to any ground-state ensemble as a function of $\\rho$ in any $d$, and show how disordered degenerate ground states arise as part of the ground-state manifold. We then specialize our results to the canonical ensemble by exploiting an ansatz that stealthy states behave remarkably like "pseudo" equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for the structure and thermodynamic properties of the stealthy disordered ground states and associated excited states are in excellent agreement with computer simulations across the first three space dimensions. The development of this theory provides provide new insights regarding our fundamental understanding of the nature and formation of low-temperature states of amorphous matter. Our work also offers challenges to experimentalists to synthesize stealthy ground states at the molecular level.
Ultracold high-density samples of rovibronic ground-state molecules in an optical lattice
NASA Astrophysics Data System (ADS)
Danzl, Johann Georg
2011-03-01
Ultracold molecules controlled at the level of single quantum states with respect to all internal and external degrees of freedom will enable a series of fundamental studies in physics and chemistry, ranging from novel quantum gas experiments and cold controlled chemistry to quantum information and quantum simulation. Ultracold molecules trapped in an optical lattice at high density and prepared in their lowest internal quantum state are an ideal starting point for these studies. We create ultracold and dense samples of molecules in a single hyperfine sublevel of the rovibronic ground state while each molecule is individually trapped in the motional ground state of an optical lattice well [1,2]. Starting from an atomic Mott-insulator state with optimized double-site occupancy, weakly bound Cs dimer molecules are efficiently formed on a Feshbach resonance and subsequently transferred to the rovibronic ground state by a stimulated 4-photon process with the Stimulated Raman Adiabatic Passage (STIRAP) technique. The molecules are trapped in the lattice with a lifetime of 8 s. We aim at producing Bose-Einstein condensates of ground-state molecules by adiabatically removing the lattice. Our results, when suitably generalized to heteronuclear molecules, present an important step towards the realization of dipolar quantum-gas phases in optical lattices. I will report on recent progress in Innsbruck on the formation of RbCs ground state molecules.
Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications
NASA Astrophysics Data System (ADS)
Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J. Z.; Morse, K. J.; Riemann, H.; Abrosimov, N. V.; Nötzel, N.; Litvinenko, K. L.; Murdin, B. N.; Thewalt, M. L. W.
2015-05-01
The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si.
Nonequilibrium Kinetics of Rydberg Atomic States
Bureyeva, L. A.; Kadomtsev, M. B.; Levashova, M. G.; Lisitsa, V. S.
2008-10-22
Two-dimensional quasi-classical model of the radiative-collisional cascade for hydrogen-like systems is developed. The model establishes the correspondence between the quantum and classical approaches. Our calculations of the two-dimensional populations of highly excited atomic hydrogen states for three-body and photorecombination sources of population allow the data of one-dimensional kinetic models to be refined. The calculated intensities of recombination lines demonstrate the degree of nonequilibrium of the Rydberg state populations under typical astrophysical plasma conditions.
Ground states of stealthy hyperuniform potentials: I. Entropically favored configurations
NASA Astrophysics Data System (ADS)
Zhang, G.; Stillinger, F. H.; Torquato, S.
2015-08-01
Systems of particles interacting with "stealthy" pair potentials have been shown to possess infinitely degenerate disordered hyperuniform classical ground states with novel physical properties. Previous attempts to sample the infinitely degenerate ground states used energy minimization techniques, introducing algorithmic dependence that is artificial in nature. Recently, an ensemble theory of stealthy hyperuniform ground states was formulated to predict the structure and thermodynamics that was shown to be in excellent agreement with corresponding computer simulation results in the canonical ensemble (in the zero-temperature limit). In this paper, we provide details and justifications of the simulation procedure, which involves performing molecular dynamics simulations at sufficiently low temperatures and minimizing the energy of the snapshots for both the high-density disordered regime, where the theory applies, as well as lower densities. We also use numerical simulations to extend our study to the lower-density regime. We report results for the pair correlation functions, structure factors, and Voronoi cell statistics. In the high-density regime, we verify the theoretical ansatz that stealthy disordered ground states behave like "pseudo" disordered equilibrium hard-sphere systems in Fourier space. The pair statistics obey certain exact integral conditions with very high accuracy. These results show that as the density decreases from the high-density limit, the disordered ground states in the canonical ensemble are characterized by an increasing degree of short-range order and eventually the system undergoes a phase transition to crystalline ground states. In the crystalline regime (low densities), there exist aperiodic structures that are part of the ground-state manifold but yet are not entropically favored. We also provide numerical evidence suggesting that different forms of stealthy pair potentials produce the same ground-state ensemble in the zero-temperature limit. Our techniques may be applied to sample the zero-temperature limit of the canonical ensemble of other potentials with highly degenerate ground states.
Ground state and constrained domain walls in Gd /Fe multilayers
NASA Astrophysics Data System (ADS)
Van Aken, Bas B.; Prieto, José L.; Mathur, Neil D.
2005-03-01
The magnetic ground state of antiferromagnetically coupled Gd /Fe multilayers and the evolution of in-plane domain walls is modeled with micromagnetics. The twisted state is characterized by a rapid decrease of the interface angle with increasing magnetic field. We found that for certain ratios MFe:MGd, the twisted state is already present at low fields. However, the magnetic ground state is not only determined by the ratio MFe:MGd but also by the thicknesses of the layers; that is by the total moments of the layer. The dependence of the magnetic ground state is explained by the amount of overlap of the domain walls at the interface. Thicker layers suppress the Fe-aligned and the Gd-aligned state in favor of the twisted state. On the other hand, ultrathin layers exclude the twisted state, since wider domain walls cannot form in these ultrathin layers.
Encoding Universal Computation in the Ground States of Ising Lattices
Gu, Mile
2012-01-01
We characterize the set of ground states that can be synthesized by classical 2-body Ising Hamiltonians. We then construct simple Ising planar blocks that simulates 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 emergence properties in infinite lattices.
Designed Diamond Ground State via Optimized Isotropic Monotonic Pair Potentials
Etienne Marcotte; Frank H. Stillinger; Salvatore Torquato
2012-12-15
We apply inverse statistical-mechanical methods to find a simple family of optimized isotropic, monotonic pair potentials, under certain constraints, whose ground states for a wide range of pressures is the diamond crystal. These constraints include desirable phonon spectra and the widest possible pressure range for stability. We also ascertain the ground-state phase diagram for a specific optimized potential to show that other crystal structures arise for other pressures. Cooling disordered configurations interacting with our optimized potential to absolute zero frequently leads to the desired diamond crystal ground state, revealing that the capture basin for the global energy minimum is large and broad relative to the local energy minima basins.
Preparation and probing of the ground state coherence in Rubidium
Martin Oberst; Frank Vewinger; A. I. Lvovsky
2007-01-31
We demonstrate the preparation and probing of the coherence between the hyperfine ground states |5S_{1/2}, F=1> and |5S_{1/2}, F=2> of the Rubidium 87 isotope. The effect of various coherence control techniques, i.e. fractional Stimulated Raman Adiabatic Passage and Coherent Population Return on the coherence are investigated. These techniques are implemented using nearly degenerate pump and Stokes lasers at 795nm (Rubidium D1 transition) which couple the two hyperfine ground states via the excited state |5P_{1/2}, F=1> through a resonant two-photon process, in which a coherent superposition of the two hyperfine ground states is established. The medium is probed by an additional weak laser, which generates a four-wave mixing signal proportional to the ground state coherence, and allows us to monitor its evolution in time. The experimental data are compared with numerical simulations.
GROUND-WATER POLLUTION PROBLEMS IN THE SOUTHEASTERN UNITED STATES
An evaluation of principal sources of ground-water contamination has been carried out in seven southeastern States--Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, and Virginia. Natural ground-water quality is good to excellent, except for the presence of ...
An ultracold high-density sample of rovibronic ground-state molecules in an optical lattice
NASA Astrophysics Data System (ADS)
Danzl, Johann G.; Mark, Manfred J.; Haller, Elmar; Gustavsson, Mattias; Hart, Russell; Aldegunde, Jesus; Hutson, Jeremy M.; Nägerl, Hanns-Christoph
2010-04-01
Control over all internal and external degrees of freedom of molecules at the level of single quantum states will enable a series of fundamental studies in physics and chemistry. In particular, samples of ground-state molecules at ultralow temperatures and high number densities will facilitate new quantum-gas studies and future applications in quantum information science. However, high phase-space densities for molecular samples are not readily attainable because efficient cooling techniques such as laser cooling are lacking. Here we produce an ultracold and dense sample of molecules in a single hyperfine level of the rovibronic ground state with each molecule individually trapped in the motional ground state of an optical lattice well. Starting from a zero-temperature atomic Mott-insulator state with optimized double-site occupancy, weakly bound dimer molecules are efficiently associated on a Feshbach resonance and subsequently transferred to the rovibronic ground state by a stimulated four-photon process with >50% efficiency. The molecules are trapped in the lattice and have a lifetime of 8s. Our results present a crucial step towards Bose-Einstein condensation of ground-state molecules and, when suitably generalized to polar heteronuclear molecules, the realization of dipolar quantum-gas phases in optical lattices.
Ground state cooling in a bad cavity
Stefano Zippilli; Giovanna Morigi; Wolfgang P. Schleich
2006-03-27
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.
Sarkar, Resham; Fang, Renpeng; Tu, Yanfei; Shahriar, Selim M
2014-01-01
We investigate the behavior of an ensemble of N non-interacting, identical atoms, excited by a laser with a wavelength of $\\lambda$. In general, the i-th atom sees a Rabi frequency $\\Omega_i$, an initial position dependent laser phase $\\phi_i$, and a motion induced Doppler shift of $\\delta_i$. When $\\Omega_i=\\Omega$ and $\\delta_i=\\delta$ for all atoms, the system evolves into a superposition of (N+1) symmetric collective states (SCS), independent of the values of $\\phi_i$. If $\\phi_i=\\phi$ for all atoms, these states simplify to the well-known Dicke collective states. When $\\Omega_i$ or $\\delta_i$ is distinct for each atom, the system evolves into a superposition of SCS as well as asymmetric collective states (ACS). For large N, the number of ACS's $(2^N-N-1)$ is far greater than that of the SCS. We show how to formulate the properties of all the collective states under various non-idealities, and use this formulation to understand the dynamics thereof. For the case where $\\Omega_i=\\Omega$ and $\\delta_i=\\delt...
Handbook for state ground water managers
Not Available
1992-05-01
;Table of Contents: Nonpoint Source Implementation; State Public Water System Supervision; State Underground Water Source Protection (Underground Injection Control); Water Pollution Control -- State and Interstate Program Support (106 Grants); Water Quality Management Planning; Agriculture in Concert with the Environment; Consolidated Pesticide Compliance Monitoring and Program Cooperative Agreements; Pollution Prevention Incentives for States; Hazardous Substance Response Trust Fund; Hazardous Waste Financial Assistance; Underground Storage Tank Program; Leaking Underground Storage Tank Trust Fund; State/EPA Data Management Financial Assistance Program; Environmental Education; and Multi-Media Assistance Agreements for Indian Tribes.
Ground State Properties of the 1/2 Flux Harper Hamiltonian
NASA Astrophysics Data System (ADS)
Kennedy, Colin; Burton, William Cody; Chung, Woo Chang; Ketterle, Wolfgang
2015-05-01
The Harper Hamiltonian describes the motion of charged particles in an applied magnetic field - the spectrum of which exhibits the famed Hofstadter's butterfly. Recent advances in driven optical lattices have made great strides in simulating nontrivial Hamiltonians, such as the Harper model, in the time-averaged sense. We report on the realization of the ground state of bosons in the Harper Hamiltonian for 1/2 flux per plaquette utilizing a tilted two-dimensional lattice with laser assisted tunneling. We detail progress in studying various ground state properties of the 1/2 flux Harper Hamiltonian including ground state degeneracies, gauge-dependent observables, effects of micromotion, adiabatic loading schemes, and emergence and decay of coherence. Additionally, we describe prospects for flux rectification using a period-tripled superlattice and generalizations to three dimensions. MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology.
Exploring chaos in the Dicke model using ground-state fidelity and Loschmidt echo.
Bhattacharya, Utso; Dasgupta, Sayak; Dutta, Amit
2014-08-01
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. PMID:25215812
Separability and ground state factorization in quantum spin systems
Giampaolo, S M; Illuminati, F
2009-01-01
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...
Approximating the ground state of gapped quantum spin systems
Michalakis, Spyridon; Hamza, Eman; Nachtergaele, Bruno; Sims, Robert
2009-01-01
We consider quantum spin systems defined on finite sets V equipped with a metric. In typical examples, V is a large, but finite subset of Z{sup d}. For finite range Hamiltonians with uniformly bounded interaction terms and a unique, gapped ground state, we demonstrate a locality property of the corresponding ground state projector. In such systems, this ground state projector can be approximated by the product of observables with quantifiable supports. In fact, given any subset {chi} {contained_in} V the ground state projector can be approximated by the product of two projections, one supported on {chi} and one supported on {chi}{sup c}, and a bounded observable supported on a boundary region in such a way that as the boundary region increases, the approximation becomes better. Such an approximation was useful in proving an area law in one dimension, and this result corresponds to a multi-dimensional analogue.
Protocol for Atomic Oxygen Testing of Materials in Ground-Based Facilities. No. 2
NASA Technical Reports Server (NTRS)
Minton, Timothy K.
1995-01-01
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.
Chiral Ground States in a Frustrated Holographic Superconductor
Mitsuhiro Nishida
2015-09-01
Frustration is an important phenomenon in condensed matter physics because it can introduce a new order parameter such as chirality. Towards understanding a mechanism of the frustration in strongly correlated systems, we study a holographic superconductor model with three scalar fields and an interband Josephson coupling, which is important for the frustration. We analyze free energy of solutions of the model to determine ground states. We find chiral ground states, which have nonzero chirality.
Existence of Ground States of Nonlocal-Interaction Energies
NASA Astrophysics Data System (ADS)
Simione, Robert; Slep?ev, Dejan; Topaloglu, Ihsan
2015-05-01
We investigate which nonlocal-interaction energies have a ground state (global minimizer). We consider this question over the space of probability measures and establish a sharp condition for the existence of ground states. We show that this condition is closely related to the notion of stability (i.e. -stability) of pairwise interaction potentials. Our approach uses the direct method of the calculus of variations.
Ground state hyperfine structure in muonic lithium ions
A. P. Martynenko; A. A. Ulybin
2015-04-09
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\
Theory of ground state factorization in quantum cooperative systems
Giampaolo, S M; Illuminati, F
2008-01-01
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.
Theory of ground state factorization in quantum cooperative systems.
Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio
2008-05-16
We introduce a general analytic approach to the study of factorization points and factorized ground states in quantum cooperative systems. The method allows us to determine rigorously the existence, location, and exact form of separable ground states in a large variety of, generally nonexactly solvable, spin models belonging to different universality classes. The theory applies to translationally invariant systems, irrespective of spatial dimensionality, and for spin-spin interactions of arbitrary range. PMID:18518481
Possible ground-state octupole deformation in /sup 229/Pa
Ahmad, I.; Gindler, J.E.; Betts, R.R.; Chasman, R.R.; Friedman, A.M.
1982-12-13
Evidence is presented for the occurrence of a (5/2)/sup + -/ parity doublet as the ground state of /sup 229/Pa, in agreement with a previous theoretical prediction. The doublet splitting energy is measured to be 0.22 +- 0.05 keV. The relation of this doublet to ground-state octupole deformation is discussed. .ID LV2109 .PG 1762 1764
Ground states of stealthy hyperuniform potentials: I. Entropically favored configurations
Ge Zhang; Frank H. Stillinger; Salvatore Torquato
2015-08-19
Systems of particles interacting with "stealthy" pair potentials have been shown to possess infinitely degenerate disordered hyperuniform classical ground states with novel physical properties. Previous attempts to sample the infinitely degenerate ground states used energy minimization techniques, introducing algorithmic dependence that is artificial in nature. Recently, an ensemble theory of stealthy hyperuniform ground states was formulated to predict the structure and thermodynamics that was shown to be in excellent agreement with corresponding computer simulation results in the canonical ensemble (in the zero-temperature limit). In this paper, we provide details and justifications of the simulation procedure, which involves performing molecular dynamics simulations at sufficiently low temperatures and minimizing the energy of the snapshots for both the high-density disordered regime, where the theory applies, as well as lower densities. We also use numerical simulations to extend our study to the lower-density regime. We report results for the pair correlation functions, structure factors, and Voronoi cell statistics. In the high-density regime, we verify the theoretical ansatz that stealthy disordered ground states behave like "pseudo" disordered equilibrium hard-sphere systems in Fourier space. These results show that as the density decreases from the high-density limit, the disordered ground states in the canonical ensemble are characterized by an increasing degree of short-range order and eventually the system undergoes a phase transition to crystalline ground states. We also provide numerical evidence suggesting that different forms of stealthy pair potentials produce the same ground-state ensemble in the zero-temperature limit. Our techniques may be applied to sample this limit of the canonical ensemble of other potentials with highly degenerate ground states.
Theory of ground state factorization in quantum cooperative systems
S. M. Giampaolo; G. Adesso; F. Illuminati
2008-04-01
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.
Concentration for unknown atomic entangled states via cavity decay
Cao Zhuoliang; Yang Ming; Zhang Lihua
2006-01-15
We present a physical scheme for entanglement concentration of unknown atomic entangled states via cavity decay. In the scheme, the atomic state is used as a stationary qubit and the photonic state as a flying qubit, and a close maximally entangled state can be obtained from pairs of partially entangled states probabilistically.
Maaloul, L.; Gangwar, R. K.; Stafford, L.
2015-07-15
A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from ?115 to ?300?V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5?±?1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500?nm revealed a constant excitation temperature of 0.33?±?0.04?eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12?cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.
NASA Astrophysics Data System (ADS)
Mackie, Matt; Debrosse, Catherine
2010-04-01
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.
Quantum insulating states of F=2 cold atoms in optical lattices
Fei Zhou; Gordon W. Semenoff
2006-11-09
In this Letter we study various spin correlated insulating states of F=2 cold atoms in optical lattices. We find that the effective spin exchange interaction due to virtual hopping contains an {\\em octopole} coupling between two neighboring lattice sites. Depending on scattering lengths and numbers of particles per site the ground states are either rotationally invariant dimer or trimer Mott insulators or insulating states with various spin orders. Three spin ordered insulating phases are ferromagnetic, cyclic and nematic Mott insulators. We estimate the phase boundaries for states with different numbers of atoms per lattice site.
Toward Triplet Ground State LiNa Molecules
NASA Astrophysics Data System (ADS)
Jamison, Alan; Rvachov, Timur; Jing, Li; Jiang, Yijun; Zwierlein, Martin; Ketterle, Wolfgang
2015-05-01
We present progress toward creation of ultracold ground-state triplet LiNa molecules. This molecule is expected to have a long lifetime in the triplet ground state due to its fermionic nature, large rotational constant, and weak spin-orbit coupling. The triplet state has both electric and magnetic dipole moments, affording unique opportunities in quantum simulation and ultracold chemistry. Our progress includes the first observation of triplet excited states in this molecule, achieved through photoassociation of ultracold mixtures of 6-Li and Na. We compare experimental results to a variety of near-dissociation expansions as well as ab initio potentials.
Creation of Ultracold Sr2 Molecules in the Electronic Ground State
NASA Astrophysics Data System (ADS)
Stellmer, Simon; Pasquiou, Benjamin; Grimm, Rudolf; Schreck, Florian
2012-09-01
We report on the creation of ultracold Sr284 molecules in the electronic ground state. The molecules are formed from atom pairs on sites of an optical lattice using stimulated Raman adiabatic passage (STIRAP). We achieve a transfer efficiency of 30% and obtain 4×104 molecules with full control over the external and internal quantum state. STIRAP is performed near the narrow S01-P13 intercombination transition, using a vibrational level of the 1(0u+) potential as an intermediate state. In preparation of our molecule association scheme, we have determined the binding energies of the last vibrational levels of the 1(0u+), 1(1u) excited-state and the X?g+1 ground-state potentials. Our work overcomes the previous limitation of STIRAP schemes to systems with magnetic Feshbach resonances, thereby establishing a route that is applicable to many systems beyond alkali-metal dimers.
Brunet, François D; Feola, Julie C; Joly, Helen A
2012-03-15
Reaction mixtures, containing Al atoms and methylethyl ether (MEE) or diethyl ether (DEE) in an adamantane matrix, were prepared with the aid of a metal-atom reactor known as a rotating cryostat. The EPR spectra of the resulting products were recorded from 77-260 K, at 10 K intervals. Al atoms were found to insert into methyl-O, ethyl-O, and C-C bonds to form CH(3)AlOCH(2)CH(3), CH(3)OAlCH(2)CH(3), and CH(3)OCH(2)AlCH(3), respectively, in the case of MEE while DEE produced CH(3)CH(2)AlOCH(2)CH(3) and CH(3)AlCH(2)OCH(2)CH(3), respectively. From the intensity of the transition lines attributed to the Al atom C-O insertion products of MEE, insertion into the methyl-O bond is preferred. The Al hyperfine interaction (hfi) extracted from the EPR spectra of the C-O insertion products was greater than that of the C-C insertion products, that is, 5.4% greater for the DEE system and 7% greater for the MEE system. The increase in Al hfi is thought to arise from the increased electron-withdrawing ability of the substituents bonded to Al. Besides HAlOH, resulting from the reaction of Al atoms with adventitious water, novel mixed HAlOH:MEE and HAlOH:DEE complexes were identified with the aid of isotopic studies involving H(2)(17)O and D(2)O. The Al and H hfi of HAlOH were found to decrease upon complex formation. These findings are consistent with the nuclear hfi calculated using a density functional theory (DFT) method with close agreement between theory and experiment occurring at the B3LYP level using a 6-311+G(2df,p) basis set. PMID:22299675
Creating Ground State Molecules with Optical Feshbach Resonances in Tight Traps
Koch, Christiane P.; Masnou-Seeuws, Francoise; Kosloff, Ronnie
2005-05-20
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.
Efficient algorithm for approximating one-dimensional ground states
Aharonov, Dorit; Arad, Itai; Irani, Sandy
2010-07-15
The density-matrix renormalization-group method is very effective at finding ground states of one-dimensional (1D) quantum systems in practice, but it is a heuristic method, and there is no known proof for when it works. In this article we describe an efficient classical algorithm which provably finds a good approximation of the ground state of 1D systems under well-defined conditions. More precisely, our algorithm finds a matrix product state of bond dimension D whose energy approximates the minimal energy such states can achieve. The running time is exponential in D, and so the algorithm can be considered tractable even for D, which is logarithmic in the size of the chain. The result also implies trivially that the ground state of any local commuting Hamiltonian in 1D can be approximated efficiently; we improve this to an exact algorithm.
Ground-state van der Waals forces in planar multilayer magnetodielectrics
Buhmann, Stefan Yoshi; Welsch, Dirk-Gunnar; Kampf, Thomas
2005-09-15
Within the frame of lowest-order perturbation theory, the van der Waals potential of a ground-state atom placed within an arbitrary dispersing and absorbing magnetodielectric multilayer system is given. Examples of an atom situated in front of a magnetodielectric plate or between two such plates are studied in detail. Special emphasis is placed on the competing attractive and repulsive force components associated with the electric and magnetic matter properties, respectively, and conditions for the formation of repulsive potential walls are given. Both numerical and analytical results are presented.
NASA Astrophysics Data System (ADS)
Zhu, Qizhong; Zhang, Qi; Wu, Biao
2015-02-01
The extended Bose-Hubbard model for a double-well potential with pair tunneling is studied through both exact diagonalization and mean field theory (MFT). When pair tunneling is strong enough, the ground state wavefunction predicted by the MFT is complex and doubly degenerate while the quantum ground state wavefunction is always real and unique. The time reversal symmetry is spontaneously broken when the system transfers from the quantum ground state into one of the mean field ground states upon a small perturbation. As the gap between the lowest two levels decreases exponentially with particle number, the required perturbation inducing the spontaneous symmetry breaking (SSB) is infinitesimal for particle number of typical cold atom systems. The quantum ground state is further analyzed with the Penrose-Onsager criterion, and is found to be a fragmented condensate. The state also develops the pair correlation and has non-vanishing pair order parameter instead of the conventional single particle order parameter. When this model is generalized to optical lattice, a pair superfluid can be generated. The mean field ground state can be regarded as effective ground state in this simple model. The detailed computation for this model enables us to offer an in-depth discussion of the relation between SSB and effective ground state, giving a glimpse on how nonlinearity arises in the SSB of a quantum system.
Light pulse analysis with a multi-state atom interferometer
Herrera, I.; Lombardi, P.; Schäfer, F.; Petrovic, J.; Cataliotti, F. S.
2014-12-04
We present a controllable multi-state cold-atom interferometer that is easy-to-use and fully merged on an atom chip. We demonstrate its applications as a sensor of the fields whose interactions with atoms are state-dependent.
NASA Astrophysics Data System (ADS)
Lin, Xiu
2010-05-01
We propose an alternative scheme for generation of atomic Schrödinger cat states in an optical cavity. In the scheme the atoms are always populated in the two ground states and the cavity remains in the vacuum state. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. The scheme may be generalized to the deterministic generation of entangled coherent states for two atomic samples. In contrast with the previously proposed schemes of [Commun. Theor. Phys. 40 (2003) 103 and Chin. Phys. B 18 (2009) 1045], the required interaction time in our scheme is greatly shortened and thus the decoherence can be effectively suppressed.
NASA Astrophysics Data System (ADS)
Peng, Hsuan Tung; Ho, Yew Kam
2015-10-01
We have investigated quantum entanglement for two interacting ultracold bosonic atoms in one-dimensional harmonic traps. The effective potential is modeled by delta interaction. For this two-atom system, we have investigated quantum entanglement properties, such as von Neumann entropy and linear entropy for its ground state and excited states. Using a computational scheme that is different from previously employed, a total of the lowest 16 states are studied. Here we show the dependencies of entanglement properties under various interacting strengths. Comparisons for the ground state entanglement are made with earlier results in the literature. New results for the other 15 excited states are reported here.
Systems of Interest Ground State Determination
Crawford, T. Daniel
3 excited states5 calculations with the aug-cc- pVDZ basis set were carried out with the PSI3 code in the interstellar medium (ISM) allows for a better understanding of what types of chemical reactions are possible medium (ISM) by millimeter wavelength measurements taken in 1974 by the Thaddeus group at the Harvard
NASA Astrophysics Data System (ADS)
Vogell, B.; Kampschulte, T.; Rakher, M. T.; Faber, A.; Treutlein, P.; Hammerer, K.; Zoller, P.
2015-04-01
We propose and investigate a hybrid optomechanical system consisting of a micro-mechanical oscillator coupled to the internal states of a distant ensemble of atoms. The interaction between the systems is mediated by a light field which allows the coupling of the two systems in a modular way over long distances. Coupling to internal degrees of freedom of atoms opens up the possibility to employ high-frequency mechanical resonators in the MHz to GHz regime, such as optomechanical crystal structures, and to benefit from the rich toolbox of quantum control over internal atomic states. Previous schemes involving atomic motional states are rather limited in both of these aspects. We derive a full quantum model for the effective coupling including the main sources of decoherence. As an application we show that sympathetic ground-state cooling and strong coupling between the two systems is possible.
B. Vogell; T. Kampschulte; M. T. Rakher; A. Faber; P. Treutlein; K. Hammerer; P. Zoller
2014-12-16
We propose and investigate a hybrid optomechanical system consisting of a micro-mechanical oscillator coupled to the internal states of a distant ensemble of atoms. The interaction between the systems is mediated by a light field which allows to couple the two systems in a modular way over long distances. Coupling to internal degrees of freedom of atoms opens up the possibility to employ high-frequency mechanical resonators in the MHz to GHz regime, such as optomechanical crystal structures, and to benefit from the rich toolbox of quantum control over internal atomic states. Previous schemes involving atomic motional states are rather limited in both of these aspects. We derive a full quantum model for the effective coupling including the main sources of decoherence. As an application we show that sympathetic ground-state cooling and strong coupling between the two systems is possible.
Exploring the Single Atom Spin State by Electron Spectroscopy
NASA Astrophysics Data System (ADS)
Lin, Yung-Chang; Teng, Po-Yuan; Chiu, Po-Wen; Suenaga, Kazu
2015-11-01
To control the spin state of an individual atom is an ultimate goal for spintronics. A single atom magnet, which may lead to a supercapacity memory device if realized, requires the high-spin state of an isolated individual atom. Here, we demonstrate the realization of well isolated transition metal (TM) atoms fixed at atomic defects sparsely dispersed in graphene. Core-level electron spectroscopy clearly reveals the high-spin state of the individual TM atoms at the divacancy or edge of the graphene layer. We also show for the first time that the spin state of single TM atoms systematically varies with the coordination of neighboring nitrogen or oxygen atoms. These structures can be thus regarded as the smallest components of spintronic devices with controlled magnetic behavior.
Exploring the Single Atom Spin State by Electron Spectroscopy.
Lin, Yung-Chang; Teng, Po-Yuan; Chiu, Po-Wen; Suenaga, Kazu
2015-11-13
To control the spin state of an individual atom is an ultimate goal for spintronics. A single atom magnet, which may lead to a supercapacity memory device if realized, requires the high-spin state of an isolated individual atom. Here, we demonstrate the realization of well isolated transition metal (TM) atoms fixed at atomic defects sparsely dispersed in graphene. Core-level electron spectroscopy clearly reveals the high-spin state of the individual TM atoms at the divacancy or edge of the graphene layer. We also show for the first time that the spin state of single TM atoms systematically varies with the coordination of neighboring nitrogen or oxygen atoms. These structures can be thus regarded as the smallest components of spintronic devices with controlled magnetic behavior. PMID:26613462
Structure of ground and excited states of $^{12}$C
Y. Kanada-En'yo}
2006-05-20
We studied the ground and excited states of $^{12}$C based on variational calculations after spin-parity projection in a framework of antisymmetrized molecular dynamics(AMD). The calculations systematically reproduce various experimental data. It was found that the sub-shell closure and SU(3)-limit $3\\alpha$ cluster components are contained in the ground state, while various $3\\alpha$ cluster structures develop in the excited states. We discussed effects of $\\alpha$ breaking and show the importance of coexistence of the cluster and shell-model-like aspects.
Ensemble Theory for Stealthy Hyperuniform Disordered Ground States
NASA Astrophysics Data System (ADS)
Torquato, S.; Zhang, G.; Stillinger, F. H.
2015-04-01
It has been shown numerically that systems of particles interacting with isotropic "stealthy" bounded long-ranged pair potentials (similar to Friedel oscillations) have classical ground states that are (counterintuitively) disordered, hyperuniform, and highly degenerate. Disordered hyperuniform systems have received attention recently because they are distinguishable exotic states of matter poised between a crystal and liquid that are endowed with novel thermodynamic and physical properties. The task of formulating an ensemble theory that yields analytical predictions for the structural characteristics and other properties of stealthy degenerate ground states in d -dimensional Euclidean space Rd is highly nontrivial because the dimensionality of the configuration space depends on the number density ? and there is a multitude of ways of sampling the ground-state manifold, each with its own probability measure for finding a particular ground-state configuration. The purpose of this paper is to take some initial steps in this direction. Specifically, we derive general exact relations for thermodynamic properties (energy, pressure, and isothermal compressibility) that apply to any ground-state ensemble as a function of ? in any d , and we show how disordered degenerate ground states arise as part of the ground-state manifold. We also derive exact integral conditions that both the pair correlation function g2(r ) and structure factor S (k ) must obey for any d . We then specialize our results to the canonical ensemble (in the zero-temperature limit) by exploiting an ansatz that stealthy states behave remarkably like "pseudo"-equilibrium hard-sphere systems in Fourier space. Our theoretical predictions for g2(r ) and S (k ) are in excellent agreement with computer simulations across the first three space dimensions. These results are used to obtain order metrics, local number variance, and nearest-neighbor functions across dimensions. We also derive accurate analytical formulas for the structure factor and thermal expansion coefficient for the excited states at sufficiently small temperatures for any d . The development of this theory provides new insights regarding our fundamental understanding of the nature and formation of low-temperature states of amorphous matter. Our work also offers challenges to experimentalists to synthesize stealthy ground states at the molecular level.
Photoionization of ground and excited states of Ti I
NASA Astrophysics Data System (ADS)
Nahar, Sultana N.
2015-07-01
Detailed photoionization of ground and many excited states with autoionizing resonances of neutral Ti are presented. Ti I with 22 electrons forms a large number of bound states, the present work finds a total of 908 bound states with n ? 10 and l ? 8 . Photoionization cross sections (?PI) for all these bound states have been obtained. Calculations were carried out in the close-coupling R-matrix method using a wave function expansion that included 36 states of core ion Ti II. It is found that the resonances enhance the low energy region of photoionization of the ground and low lying excited states. The resonant features will increase the opacity, as expected of astrophysical observation, and hence play important role in determination of abundances in the elements in the astronomical objects. The excited states also show prominent structures of Seaton or photo-excitation-of-core resonances.
A single laser system for ground-state cooling of 25Mg+
NASA Astrophysics Data System (ADS)
Hemmerling, B.; Gebert, F.; Wan, Y.; Nigg, D.; Sherstov, I. V.; Schmidt, P. O.
2011-09-01
We present a single solid-state laser system to cool, coherently manipulate and detect 25Mg+ ions. Coherent manipulation is accomplished by coupling two hyperfine ground state levels using a pair of far-detuned Raman laser beams. Resonant light for Doppler cooling and detection is derived from the same laser source by means of an electro-optic modulator, generating a sideband which is resonant with the atomic transition. We demonstrate ground-state cooling of one of the vibrational modes of the ion in the trap using resolved-sideband cooling. The cooling performance is studied and discussed by observing the temporal evolution of Raman-stimulated sideband transitions. The setup is a major simplification over existing state-of-the-art systems, typically involving up to three separate laser sources.
Ground Control to Niels Bohr: Exploring Outer Space with Atomic Physics
Mason A. Porter; Predrag Cvitanovic
2005-05-11
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.
Hyperfine structure of the ground state in singly ionized manganese
NASA Astrophysics Data System (ADS)
Blackwell-Whitehead, R. J.; Toner, A.; Hibbert, A.; Webb, J.; Ivarsson, S.
2005-12-01
We report the first experimental measurements and theoretical calculations for the hyperfine splitting of the 3d5 4s ground state of MnII. The hyperfine structure constants were determined using Fourier transform spectroscopy with a hollow cathode discharge lamp. The uncertainties in the magnetic dipole constants, A, are between 3 × 10-4 and 5 × 10-4cm-1. Extensive configuration interaction calculations of the hyperfine splitting of the a7S3 ground state have been carried out to compare with the experimental measurements. In addition, we give wavelengths for three resonant transitions to the ground state of MnII, accurate to a few parts in 108. These wavelengths are of interest in astrophysical applications such as studies of the time variation of the fine structure constant.
Phase diagram of the ground states of DNA condensates
Hoang, Trinh X; Giacometti, Achille; Podgornik, Rudolf; Banavar, Jayanth R; Maritan, Amos
2015-01-01
Phase diagram of the ground states of DNA in a bad solvent is studied for a semi-flexible polymer model with a generalized local elastic bending potential characterized by a nonlinearity parameter $x$ and effective self-attraction promoting compaction. $x=1$ corresponds to the worm-like chain model. Surprisingly, the phase diagram as well as the transition lines between the ground states are found to be a function of $x$. The model provides a simple explanation for the results of prior experimental and computational studies and makes predictions for the specific geometries of the ground states. The results underscore the impact of the form of the microscopic bending energy at macroscopic observable scales.
Probing Quantum Frustrated Systems via Factorization of the Ground State
NASA Astrophysics Data System (ADS)
Giampaolo, Salvatore M.; Adesso, Gerardo; Illuminati, Fabrizio
2010-05-01
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.
Probing Quantum Frustrated Systems via Factorization of the Ground State
Salvatore M. Giampaolo; Gerardo Adesso; Fabrizio Illuminati
2010-05-20
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.
Probing quantum frustrated systems via factorization of the ground state.
Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio
2010-05-21
The existence of definite orders in frustrated quantum systems is related rigorously to the occurrence of fully factorized ground states below a threshold value of the frustration. Ground-state separability thus provides a natural measure of frustration: strongly frustrated systems are those that cannot accommodate for classical-like solutions. The exact form of the factorized ground states and the critical frustration are determined for various classes of nonexactly solvable spin models with different spatial ranges of the interactions. For weak frustration, the existence of disentangling transitions determines the range of applicability of mean-field descriptions in biological and physical problems such as stochastic gene expression and the stability of long-period modulated structures. PMID:20867055
Ground-State Electromagnetic Moments of Calcium Isotopes
R. F. Garcia Ruiz; M. L. Bissell; K. Blaum; N. Frommgen; M. Hammen; J. D. Holt; M. Kowalska; K. Kreim; J. Menendez; R. Neugart; G. Neyens; W. Nortershauser; F. Nowacki; J. Papuga; A. Poves; A. Schwenk; J. Simonis; D. T. Yordanov
2015-04-17
High-resolution bunched-beam collinear laser spectroscopy was used to measure the optical hyperfine spectra of the $^{43-51}$Ca isotopes. The ground state magnetic moments of $^{49,51}$Ca and quadrupole moments of $^{47,49,51}$Ca were measured for the first time, and the $^{51}$Ca ground state spin $I=3/2$ was determined in a model-independent way. Our results provide a critical test of modern nuclear theories based on shell-model calculations using phenomenological as well as microscopic interactions. The results for the neutron-rich isotopes are in excellent agreement with predictions using interactions derived from chiral effective field theory including three-nucleon forces, while lighter isotopes illustrate the presence of particle-hole excitations of the $^{40}$Ca core in their ground state.
Long-range quantum gate via Rydberg states of atoms in a thermal microwave cavity
L?rinc Sárkány; József Fortágh; David Petrosyan
2015-09-11
We propose an implementation of a universal quantum gate between pairs of spatially separated atoms in a microwave cavity at finite temperature. The gate results from reversible laser excitation of Rydberg states of atoms interacting with each other via exchange of virtual photons through a common cavity mode. Quantum interference of different transition paths between the two-atom ground and double-excited Rydberg states makes both the transition amplitude and resonance largely insensitive to the excitations in the microwave cavity "quantum bus" which can therefore be in any superposition or mixture of photon number states. Our scheme for attaining ultralong-range interactions and entanglement also applies to mesoscopic atomic ensembles in the Rydberg blockade regime and is scalable to many ensembles trapped within a centimeter sized microwave resonator.
Long-range quantum gate via Rydberg states of atoms in a thermal microwave cavity
NASA Astrophysics Data System (ADS)
Sárkány, L?rinc; Fortágh, József; Petrosyan, David
2015-09-01
We propose an implementation of a universal quantum gate between pairs of spatially separated atoms in a microwave cavity at finite temperature. The gate results from reversible laser excitation of Rydberg states of atoms interacting with each other via exchange of virtual photons through a common cavity mode. Quantum interference of different transition paths between the two-atom ground and double-excited Rydberg states makes both the transition amplitude and resonance largely insensitive to the excitations in the microwave cavity quantum bus which can therefore be in any superposition or mixture of photon number states. Our scheme for attaining ultra-long-range interactions and entanglement also applies to mesoscopic atomic ensembles in the Rydberg blockade regime and is scalable to many ensembles trapped within a centimeter-sized microwave resonator.
Resonant two-photon ionization spectroscopy of jet-cooled UN: determination of the ground state.
Matthew, Daniel J; Morse, Michael D
2013-05-14
The optical transitions of supersonically cooled uranium nitride (UN) have been investigated in the range from 19,200 to 23,900 cm(-1) using resonant two-photon ionization spectroscopy. A large number of bands have been observed, of which seven have been rotationally resolved and analyzed. All are found to arise from the same state, which is presumably the ground state of the molecule. From the analysis of the bands, the ground state has ? = 3.5, with a bond length of 1.7650(12) A?. Comparisons to the known isovalent molecules are made, and the variations in ground state configuration are explained in terms of the configurational reordering that occurs with changes in the nuclear and ligand charges. It is concluded that the UN molecule is best considered as a U(3+)N(3-) species in which the closed shell nitride ligand interacts with a U(3+) ion. The ground state of the molecule derives from a U(3+) ion in its 7s(1)5f 2) atomic configuration. PMID:23676040
Resonant two-photon ionization spectroscopy of jet-cooled UN: Determination of the ground state
NASA Astrophysics Data System (ADS)
Matthew, Daniel J.; Morse, Michael D.
2013-05-01
The optical transitions of supersonically cooled uranium nitride (UN) have been investigated in the range from 19 200 to 23 900 cm-1 using resonant two-photon ionization spectroscopy. A large number of bands have been observed, of which seven have been rotationally resolved and analyzed. All are found to arise from the same state, which is presumably the ground state of the molecule. From the analysis of the bands, the ground state has ? = 3.5, with a bond length of 1.7650(12) Å. Comparisons to the known isovalent molecules are made, and the variations in ground state configuration are explained in terms of the configurational reordering that occurs with changes in the nuclear and ligand charges. It is concluded that the UN molecule is best considered as a U3+N3- species in which the closed shell nitride ligand interacts with a U3+ ion. The ground state of the molecule derives from a U3+ ion in its 7s15f 2 atomic configuration.
Ground-state entanglement constrains low-energy excitations
NASA Astrophysics Data System (ADS)
Kim, Isaac H.; Brown, Benjamin J.
2015-09-01
For a general quantum many-body system, we show that its ground-state entanglement imposes a fundamental constraint on the low-energy excitations. For two-dimensional systems, our result implies that any system that supports anyons must have a nonvanishing topological entanglement entropy. We demonstrate the generality of this argument by applying it to three-dimensional quantum many-body systems and showing that there is a pair of ground-state topological invariants that are associated to their physical boundaries. From the pair, one can determine whether the given boundary can or cannot absorb pointlike or linelike excitations.
Ground state entanglement constrains low-energy excitations
Isaac H. Kim; Benjamin J. Brown
2015-09-23
For a general quantum many-body system, we show that its ground-state entanglement imposes a fundamental constraint on the low-energy excitations. For two-dimensional systems, our result implies that any system that supports anyons must have a nonvanishing topological entanglement entropy. We demonstrate the generality of this argument by applying it to three-dimensional quantum many-body systems, and showing that there is a pair of ground state topological invariants that are associated to their physical boundaries. From the pair, one can determine whether the given boundary can or cannot absorb point-like or line-like excitations.
Ground-State Quantum-Electrodynamical Density-Functional Theory
M. Ruggenthaler
2015-09-04
In this work I show that the hybrid ground state of a quantum system, which consists of particles dipole-coupled to photons in a cavity, is uniquely determined by the charge density of the particles and the expectation value of the displacement operators of the cavity modes. This result extends ground-state density-functional theory to include photons and allows to determine all properties of the coupled quantum system by only knowing these two observables. The corresponding Kohn-Sham scheme shows how the photon field can be replaced by a classical electro-magnetic field and a non-linear coupling to the particles.
Ground state hyperfine structure in muonic lithium ions
NASA Astrophysics Data System (ADS)
Martynenko, A. P.; Ulybin, A. A.
2015-10-01
On the basis of perturbation theory in the fine structure constant ? and the mass ratio of the electron and muon, we calculate the one-loop vacuum polarization, electron vertex corrections, nuclear structure and recoil corrections of the hyperfine splitting of the ground state in muonic lithium ions {(? {{e}}{ }36{Li})}+ and {(? {{e}}{ }37{Li})}+. We obtain complete results for small hyperfine splittings of the ground state in {(? {{e}}{ }36{Li})}+ of {{? }}{? }1=21572.16 MHz and {{? }}{? }2=14152.56 MHz and in {(? {{e}}{ }37{Li})}+ {{? }}{? }1=21733.06 MHz and {{? }}{? }2=13994.35 MHz, which can be regarded as a reliable estimates for comparison with future experimental data.
Rydberg States of Atoms and Molecules
NASA Astrophysics Data System (ADS)
Stebbings, R. F.; Dunning, F. B.
2011-03-01
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.
Dimerized ground states in spin-S frustrated systems
C. A. Lamas; J. M. Matera
2015-09-08
We study a family of frustrated anti-ferromagnetic spin-$S$ systems with a fully dimerized ground state. This state can be exactly obtained without the need to include any additional three-body interaction in the model. The simplest members of the family can be used as a building block to generate more complex geometries like spin tubes with a fully dimerized ground state. After present some numerical results about the phase diagram of these systems, we show that the ground state is robust against the inclusion of weak disorder in the couplings as well as several kinds of perturbations, allowing to study some other interesting models as a perturbative expansion of the exact one. A discussion on how to determine the dimerization region in terms of quantum information estimators is also presented. Finally, we explore the relation of these results with a the case of the a 4-leg spin tube which recently was proposed as the model for the description of the compound Cu$_2$Cl$_4$D$_8$C$_4$SO$_2$, delimiting the region of the parameter space where this model presents dimerization in its ground state.
Fock-state view of weak-value measurements and implementation with photons and atomic ensembles
Simon, Christoph; Polzik, Eugene S.
2011-04-15
Weak measurements in combination with postselection can give rise to a striking amplification effect (related to a large ''weak value''). We show that this effect can be understood by viewing the initial state of the pointer as the ground state of a fictional harmonic oscillator. This perspective clarifies the relationship between the weak-value regime and other measurement techniques and inspires a proposal to implement fully quantum weak-value measurements combining photons and atomic ensembles.
The Leading Behaviour of The Ground-State Energy of Heavy Ions According to Brown and Ravenhall
Xiao Liu
2011-06-18
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].
Predictive State Representations for Grounding Human-Robot Communication
Isler, Ibrahim Volkan
to an increasing elderly population which could alleviate the strain on the health care system and improvePredictive 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
Ground State Entanglement in One Dimensional Translationally Invariant Quantum Systems
Irani, Sandy
Ground State Entanglement in One Dimensional Translationally Invariant Quantum Systems Sandy Irani and quantifying entanglement in quantum systems is a central theme in quantum information science. On one hand quantum entanglement is a valuable re- source that enables novel computation and communication
Calculations of the ground state of sup 16 O
Pieper, S.C.
1989-01-01
One of the central problems in nuclear physics is the description of nuclei as systems of nucleons interacting via realistic potentials. There are two main aspects of this problem: specification of the Hamiltonian, and calculation of the ground states of nuclei with the given interaction. Realistic interactions must contain both two- and three-nucleon potentials and these potentials have a complicated non-central operator structure consisting, for example, of spin, isospin and tensor dependences. This structure results in formidable many-body problems in the computation of the ground states of nuclei. At present, reliable solutions of the Faddeev equations for the A = 3 nuclei with such interactions are routine. Recently, Carlson has made an essentially exact GFMC calculation of the He ground state using just a two-nucleon interaction, and there are reliable variational calculations for more complete potential models. Nuclear matter calculations can also be made with reasonable reliability. However, there have been very few calculations of nuclei with A > 5 using realistic interactions, and none with a modern three-nucleon interaction. In the present paper I present a new technique for variational calculations for such nuclei and apply it to the ground state of {sup 16}O. 15 refs., 2 figs., 3 tabs.
Separability and ground state factorization in quantum spin systems
S. M. Giampaolo; G. Adesso; F. Illuminati
2009-06-04
We investigate the existence and the properties of fully separable (fully factorized) ground states in quantum spin systems. Exploiting techniques of quantum information and entanglement theory we extend a recently introduced method and construct a general, self-contained theory of ground state factorization in frustration free quantum spin models defined on lattices in any spatial dimension and for interactions of arbitrary range. We show that, quite generally, non exactly solvable translationally invariant models in presence of an external uniform magnetic field can admit exact, fully factorized ground state solutions. Unentangled ground states occur at finite values of the Hamiltonian parameters satisfying well defined balancing conditions between the applied field and the interaction strengths. These conditions are analytically determined together with the type of magnetic orderings compatible with factorization and the corresponding values of the fundamental observables such as energy and magnetization. The method is applied to a series of examples of increasing complexity, including translationally-invariant models with short, long, and infinite ranges of interaction, as well as systems with spatial anisotropies, in low and higher dimensions. We also illustrate how the general method, besides yielding a large series of novel exact results for complex models in any dimension, recovers, as particular cases, the results previously achieved on simple models in low dimensions exploiting direct methods based on factorized mean-field ansatz.
On the ground state wave function of matrix theory
NASA Astrophysics Data System (ADS)
Lin, Ying-Hsuan; Yin, Xi
2015-11-01
We propose an explicit construction of the leading terms in the asymptotic expansion of the ground state wave function of BFSS SU( N ) matrix quantum mechanics. Our proposal is consistent with the expected factorization property in various limits of the Coulomb branch, and involves a different scaling behavior from previous suggestions. We comment on some possible physical implications.
Selected bibliography of ground-water in the United States
Ward-McLemore, E.
1984-01-01
This bibliography contains 899 records related to the hydrology of the US. Specific topics include, but are not limited to: aquifers; artesian wells; geophysics; ground water; flow models; pollution; tritium; water levels; water policy; and legal aspects. The subject index provides listings of records related to each state. Some of the items (81) are themselves bibliographies.
On the Ground State Wave Function of Matrix Theory
Ying-Hsuan Lin; Xi Yin
2015-08-28
We propose an explicit construction of the leading terms in the asymptotic expansion of the ground state wave function of BFSS SU(N) matrix quantum mechanics. Our proposal is consistent with the expected factorization property in various limits of the Coulomb branch, and involves a different scaling behavior from previous suggestions. We comment on some possible physical implications.
Controlled probabilistic quantum key distribution using a ground state
NASA Astrophysics Data System (ADS)
Liu, Lin-Lin; Hwang, Tzonelih
2015-03-01
In this paper, we propose two controlled probabilistic quantum key distribution protocols with AKLT states. An AKLT state is a gapped ground state with minimum energy, and owing to the properties of this special state, our proposed protocols incorporate not only the measurement uncertainty in quantum phenomena (entanglement swapping with 1/4 probability) but also additional randomness (Bell measurement on two physical particles with 1/3 probability), in comparison with other PQKD schemes. Therefore, our protocols are more suitable for use by two mutually untrusted communicants, with no authenticated intermediate channel, allowing them to obtain an unpredictable, and therefore secure, key.
Lamb Shift of Laser-Dressed Atomic States
U. D. Jentschura; J. Evers; M. Haas; C. H. Keitel
2003-07-07
We discuss radiative corrections to an atomic two-level system subject to an intense driving laser field. It is shown that the Lamb shift of the laser-dressed states, which are the natural state basis of the combined atom-laser system, cannot be explained in terms of the Lamb shift received by the atomic bare states which is usually observed in spectroscopic experiments. In the final part, we propose an experimental scheme to measure these corrections based on the incoherent resonance fluorescence spectrum of the driven atom.
Speed of Markovian relaxation toward the ground state
Vogl, Malte; Schaller, Gernot; Brandes, Tobias
2010-01-15
For sufficiently low reservoir temperatures, it is known that open quantum systems subject to decoherent interactions with the reservoir relax toward their ground state in the weak coupling limit. Within the framework of quantum master equations, this is formalized by the Born-Markov-secular (BMS) approximation, where one obtains the system Gibbs state with the reservoir temperature as a stationary state. When the solution to some problem is encoded in the (isolated) ground state of a system Hamiltonian, decoherence can therefore be exploited for computation. The computational complexity is then given by the scaling of the relaxation time with the system size n. We study the relaxation behavior for local and nonlocal Hamiltonians that are coupled dissipatively with local and nonlocal operators to a bosonic bath in thermal equilibrium. We find that relaxation is generally more efficient when coherences of the density matrix in the system energy eigenbasis are taken into account. In addition, the relaxation speed strongly depends on the matrix elements of the coupling operators between initial state and ground state. We show that Dicke superradiance is a special case of our relaxation models and can thus be understood as a coherence-assisted relaxation speedup.
Speed of Markovian relaxation toward the ground state
NASA Astrophysics Data System (ADS)
Vogl, Malte; Schaller, Gernot; Brandes, Tobias
2010-01-01
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.
NASA Astrophysics Data System (ADS)
Majumder, A.; Dikshit, B.; Bhatia, M. S.; Mago, V. K.
2008-09-01
State resolved atom population of metal vapor having low-lying metastable states departs from equilibrium value. It needs to be experimentally investigated. This paper reports the use of hollow cathode lamp based atomic absorption spectroscopy technique to measure online the state resolved atom density (ground and metastable) of metal vapor in an atomic beam produced by a high power electron gun. In particular, the advantage of availability of multiwavelength emission in hollow cathode lamp is used to determine the atom density in different states. Here, several transitions pertaining to a given state have also been invoked to obtain the mean value of atom density thereby providing an opportunity for in situ averaging. It is observed that at higher source temperatures the atoms from metastable state relax to the ground state. This is ascribed to competing processes of atom-atom and electron-atom collisions. The formation of collision induced virtual source is inferred from measurement of atom density distribution profile along the width of the atomic beam. The total line-of-sight average atom density measured by absorption technique using hollow cathode lamp is compared to that measured by atomic vapor deposition method. The presence of collisions is further supported by determination of beaming exponent by numerically fitting the data.
Majumder, A.; Dikshit, B.; Bhatia, M. S.; Mago, V. K.
2008-09-15
State resolved atom population of metal vapor having low-lying metastable states departs from equilibrium value. It needs to be experimentally investigated. This paper reports the use of hollow cathode lamp based atomic absorption spectroscopy technique to measure online the state resolved atom density (ground and metastable) of metal vapor in an atomic beam produced by a high power electron gun. In particular, the advantage of availability of multiwavelength emission in hollow cathode lamp is used to determine the atom density in different states. Here, several transitions pertaining to a given state have also been invoked to obtain the mean value of atom density thereby providing an opportunity for in situ averaging. It is observed that at higher source temperatures the atoms from metastable state relax to the ground state. This is ascribed to competing processes of atom-atom and electron-atom collisions. The formation of collision induced virtual source is inferred from measurement of atom density distribution profile along the width of the atomic beam. The total line-of-sight average atom density measured by absorption technique using hollow cathode lamp is compared to that measured by atomic vapor deposition method. The presence of collisions is further supported by determination of beaming exponent by numerically fitting the data.
Majumder, A; Dikshit, B; Bhatia, M S; Mago, V K
2008-09-01
State resolved atom population of metal vapor having low-lying metastable states departs from equilibrium value. It needs to be experimentally investigated. This paper reports the use of hollow cathode lamp based atomic absorption spectroscopy technique to measure online the state resolved atom density (ground and metastable) of metal vapor in an atomic beam produced by a high power electron gun. In particular, the advantage of availability of multiwavelength emission in hollow cathode lamp is used to determine the atom density in different states. Here, several transitions pertaining to a given state have also been invoked to obtain the mean value of atom density thereby providing an opportunity for in situ averaging. It is observed that at higher source temperatures the atoms from metastable state relax to the ground state. This is ascribed to competing processes of atom-atom and electron-atom collisions. The formation of collision induced virtual source is inferred from measurement of atom density distribution profile along the width of the atomic beam. The total line-of-sight average atom density measured by absorption technique using hollow cathode lamp is compared to that measured by atomic vapor deposition method. The presence of collisions is further supported by determination of beaming exponent by numerically fitting the data. PMID:19044405
Experimental Investigation of Excited-State Lifetimes in Atomic Ytterbium
Bowers, C.J.; Budker, D.; Commins, E.D.; DeMille, D.; Freedman, S.J.; Nguyen, A.-T.; Shang, S.-Q.; Zolotorev, M.; /SLAC
2011-11-15
Lifetimes of 21 excited states in atomic Yb were measured using time-resolved fluorescence detection following pulsed laser excitation. The lifetime of the 4f{sup 14}5d6s {sup 3}D{sub 1} state, which is of particular importance for a proposed study of parity nonconservation in atoms, was measured to be 380(30) ns.
Aircraft state estimation for a ground directed bombing system
NASA Astrophysics Data System (ADS)
Jauregui, J. A.
1982-12-01
The performance of a modified linear Kalman filter with adaptation is compared with that of a common adaptive alpha-beta filter for state estimation of a pilot controlled, ground directed bombing system. Of particular concern, is the accuracy and response of the alternative filters when the aircraft conducts random maneuvers in the vicinity of the target. The desirability of including deterministic forcing in the filter model is discussed and a technique utilizing an adaptive Kalman identifier to establish the pilot response to ground control heading commands is presented.
Towards ultracold ground-state NaRb molecule
NASA Astrophysics Data System (ADS)
Guo, Mingyang; Zhu, Bing; Li, Xiaoke; Lu, Bo; Wang, Fudong; Ye, Xin; Wang, Dajun
2015-05-01
The ground-state 23Na87Rb molecule is chemically stable and has a permanent electric dipole moment as large as 3.3 Debye. These properties make it a promising candidate for investigating dipolar quantum gases. Recently, we have realized weakly bound 23Na87Rb Feshbach molecules via magneto-association. Here, we will present our results on excited-state molecular spectroscopy investigation starting with these Feshbach molecules. The prospects of transferring 23Na87Rb to the absolute ground state will also be discussed. This work is supported by Hong Kong Research Grants Council (General Research Fund Projects 403111, 404712 and the ANR/RGC Joint Research Scheme ACUHK403/13).
Mazzarella, G.; Toigo, F.; Salasnich, L.; Parola, A.
2011-05-15
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.
Adiabatic Creation of Atomic Squeezing in Dark States vs. Decoherences
Z. R. Gong; Xiaoguang Wang; C. P. Sun
2010-11-12
We study the multipartite correlations of the multi-atom dark states, which are characterized by the atomic squeezing beyond the pairwise entanglement. It is shown that, in the photon storage process with atomic ensemble via electromagnetically induced transparency (EIT) mechanism, the atomic squeezing and the pairwise entanglement can be created by adiabatically manipulating the Rabi frequency of the classical light field on the atomic ensemble. We also consider the sudden death for the atomic squeezing and the pairwise entanglement under various decoherence channels. An optimal time for generating the greatest atomic squeezing and pairwise entanglement is obtained by studying in details the competition between the adiabatic creation of quantum correlation in the atomic ensemble and the decoherence that we describe with three typical decoherence channels.
Quantum state transfer between three ring-connected atoms
Guo Yan-Qing; Deng Yao; Pei Pei; Wang Dian-fu
2015-04-24
A robust quantum state transfer scheme is discussed for three atoms that are trapped by separated cavities linked via optical fibers in ring-connection. It is shown that, under the effective three-atom Ising model, arbitrary quantum state can be transferred from one atom to another deterministically via an auxiliary atom with maximum unit fidelity. The only required operation for this scheme is replicating turning on/off the local laser fields applied to the atoms for two steps with time cost $\\frac{\\sqrt{2}\\pi}{\\Gamma_{0}}$. The scheme is insensitive to cavity leakage and atomic position due to the condition $\\Delta \\approx \\kappa\\gg g$. Another advantage of this scheme is that the cooperative influence of spontaneous emission and operating time error can reduce the time cost for maximum fidelity and thus speed up the implementation of quantum state transfer.
NASA Technical Reports Server (NTRS)
Yuan, J.-M.; Skuse, B. M.; Jaffe, R. L.; Komornicki, A.; Morokuma, K.; George, T. F.
1980-01-01
Semiclassical calculations are carried out for the quenching of excited-state fluorine atom by collinear collisions with hydrogen molecule. The overall quenching probability is the sum of two contributions: the reactive quenching probability associated with the formation of hydrogen fluoride and the nonreactive quenching probability leading to ground-state fluorine atom and hydrogen molecule. The reactive probability is greater in the threshold region of the collision energy, whereas the nonreactive probability dominates for energies above the threshold region.
Periodic striped ground states in Ising models with competing interactions
Alessandro Giuliani; Robert Seiringer
2015-09-09
We consider Ising models in two and three dimensions, with short range ferromagnetic and long range, power-law decaying, antiferromagnetic interactions. We let $J$ be the ratio between the strength of the ferromagnetic to antiferromagnetic interactions. The competition between these two kinds of interactions induces the system to form domains of minus spins in a background of plus spins, or vice versa. If the decay exponent $p$ of the long range interaction is larger than $d+1$, with $d$ the space dimension, this happens for all values of $J$ smaller than a critical value $J_c(p)$, beyond which the ground state is homogeneous. In this paper, we give a characterization of the infinite volume ground states of the system, for $p>2d$ and $J$ in a left neighborhood of $J_c(p)$. In particular, we prove that the quasi-one-dimensional states consisting of infinite stripes ($d=2$) or slabs ($d=3$), all of the same optimal width and orientation, and alternating magnetization, are infinite volume ground states. Our proof is based on localization bounds combined with reflection positivity.
Guidelines for ground motion definition for the eastern United States
Gwaltney, R.C.; Aramayo, G.A.; Williams, R.T.
1985-06-01
Guidelines for the determination of earthquake ground motion definition for the eastern United States are established here. Both far-field and near-field guidelines are given. The guidelines were based on an extensive review of the current procedures for specifying ground motion in the United States. Both empirical and theoretical procedures were used in establishing the guidelines because of the low seismicity in the eastern United States. Only a few large- to great-sized earthquakes (M/sub s/ > 7.5) have occurred in this region, no evidence of tectonic surface ruptures related to historic or Holocene earthquakes has been found, and no currently active plate boundaries of any kind are known in this region. Very little instrumented data have been gathered in the East. Theoretical procedures are proposed so that in regions of almost no data, a reasonable level of seismic ground motion activity can be assumed. The guidelines are to be used to develop the safe shutdown earthquake (SSE). A new procedure for establishing the operating basis earthquake (OBE) is proposed, in particular for the eastern United States. The OBE would be developed using a probabilistic assessment of the geological conditions and the recurrence of seismic events at a site. These guidelines should be useful in development of seismic design requirements for future reactors. 17 refs., figs., tabs.
New Ground-State Measurements of Ethyl Cyanide
NASA Astrophysics Data System (ADS)
Brauer, Carolyn S.; Pearson, John C.; Drouin, Brian J.; Yu, Shanshan
2009-09-01
The spectrum of ethyl cyanide, or propionitrile (CH3CH2CN), 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.
Topological entanglement entropy, ground state degeneracy and holography
NASA Astrophysics Data System (ADS)
Parnachev, Andrei; Poovuttikul, Napat
2015-10-01
Topological entanglement entropy, a measure of the long-ranged entanglement, is related to the degeneracy of the ground state on a higher genus surface. The exact relation depends on the details of the topological theory. We consider a class of holographic models where such relation might be similar to the one exhibited by Chern-Simons theory in a certain large N limit. Both the non-vanishing topological entanglement entropy and the ground state degeneracy in these holographic models are consequences of the topological Gauss-Bonnet term in the dual gravitational description. A soft wall holographic model of confinement is used to generate finite correlation length but keep the disk topology of the entangling surface in the bulk, necessary for nonvanishing topological entanglement entropy.
Topological Entanglement Entropy, Ground State Degeneracy and Holography
Parnachev, Andrei
2015-01-01
Topological entanglement entropy, a measure of the long-ranged entanglement, is related to the degeneracy of the ground state on a higher genus surface. The exact relation depends on the details of the topological theory. We consider a class of holographic models where such relation might be similar to the one exhibited by Chern-Simons theory in a certain large N limit. Both the non-vanishing topological entanglement entropy and the ground state degeneracy in these holographic models are consequences of the topological Gauss-Bonnet term in the dual gravitational description. A soft wall holographic model of confinement is used to generate finite correlation length but keep the disk topology of the entangling surface in the bulk, necessary for nonvanishing topological entanglement entropy.
Topological Entanglement Entropy, Ground State Degeneracy and Holography
Andrei Parnachev; Napat Poovuttikul
2015-09-29
Topological entanglement entropy, a measure of the long-ranged entanglement, is related to the degeneracy of the ground state on a higher genus surface. The exact relation depends on the details of the topological theory. We consider a class of holographic models where such relation might be similar to the one exhibited by Chern-Simons theory in a certain large N limit. Both the non-vanishing topological entanglement entropy and the ground state degeneracy in these holographic models are consequences of the topological Gauss-Bonnet term in the dual gravitational description. A soft wall holographic model of confinement is used to generate finite correlation length but keep the disk topology of the entangling surface in the bulk, necessary for nonvanishing topological entanglement entropy.
The valence-fluctuating ground state of plutonium
Janoschek, Marc; Das, Pinaki; Chakrabarti, Bismayan; Abernathy, Douglas L.; Lumsden, Mark D.; Lawrence, John M.; Thompson, Joe D.; Lander, Gerard H.; Mitchell, Jeremy N.; Richmond, Scott; Ramos, Mike; Trouw, Frans; Zhu, Jian-Xin; Haule, Kristjan; Kotliar, Gabriel; Bauer, Eric D.
2015-01-01
A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials. PMID:26601219
Calculating helium atomic excited states in coordinate space
NASA Astrophysics Data System (ADS)
Hall, Shane; Siegel, P. B.
2015-12-01
Two coupled Schrödinger equations are used to calculate excited states of atomic helium. Using product state functions for the two-electron state, the shooting method is used to numerically determine the energies of the allowed singlet and triplet levels. The calculations agree well with the data, and the coordinate-space basis yields Schrödinger equations for helium that are familiar to students who have used similar methods for the hydrogen atom.
A limit law for the ground state of Hill's equation
NASA Astrophysics Data System (ADS)
McKean, H. P.
1994-03-01
It is proved that the ground state ?( L) of (-1)x the Schrödinger operator with white noise potential, on an interval of length L, subject to Neumann, periodic, or Dirichlet conditions, satisfies the law {lim }limits_{L \\uparrow infty } P[(L/? )? ^{1/2} exp ( - tfrac{8}{3}? ^{3/2} ) > x] = \\{ {begin{array}{*{20}c} {1forx< 0} \\ {e^{ - x} forx ?slant 0} \\ } .
Ground state and supersymmetry of generally covariant systems
Gamboa, J.; Zanelli, J.
1988-12-01
We discuss the extension of Gozzi's approach to supersymmetry, based on the ground state representation (GSR) for quantum mechanical systems. The approach leads directly to the supersymmetric extensions of generally covariant systems, whose Hamiltonian constraints H = 0 are naturally in their GSR form. The method is applied to several cases: relativistic particles interacting with external gauge and gravitational fields, strings, etc. copyright 1988 Academic Press, Inc.
Detecting topological order in a ground state wave function.
Levin, Michael; Wen, Xiao-Gang
2006-03-24
A large class of topological orders can be understood and classified using the string-net condensation picture. These topological orders can be characterized by a set of data (N, di, F(lmn)(ijk), delta(ijk). We describe a way to detect this kind of topological order using only the ground state wave function. The method involves computing a quantity called the "topological entropy" which directly measures the total quantum dimension D= Sum(id2i). PMID:16605803
Detecting Topological Order in a Ground State Wave Function
NASA Astrophysics Data System (ADS)
Levin, Michael; Wen, Xiao-Gang
2006-03-01
A large class of topological orders can be understood and classified using the string-net condensation picture. These topological orders can be characterized by a set of data (N,di,Flmnijk,?ijk). We describe a way to detect this kind of topological order using only the ground state wave function. The method involves computing a quantity called the “topological entropy” which directly measures the total quantum dimension D=?idi2.
Ground state solutions of asymptotically linear fractional Schrödinger equations
NASA Astrophysics Data System (ADS)
Chang, Xiaojun
2013-06-01
This paper is devoted to a time-independent fractional Schrödinger equation of the form (-? )^s u+V(x)u=f(x,u) in {R}N, where N ? 2, s ? (0, 1), (-?)s stands for the fractional Laplacian. We apply the variational methods to obtain the existence of ground state solutions when f(x, u) is asymptotically linear with respect to u at infinity.
Ground-state energy and relativistic corrections for positronium hydride
Bubin, Sergiy; Varga, Kalman
2011-07-15
Variational calculations of the ground state of positronium hydride (HPs) are reported, including various expectation values, electron-positron annihilation rates, and leading relativistic corrections to the total and dissociation energies. The calculations have been performed using a basis set of 4000 thoroughly optimized explicitly correlated Gaussian basis functions. The relative accuracy of the variational energy upper bound is estimated to be of the order of 2x10{sup -10}, which is a significant improvement over previous nonrelativistic results.
Complex spin-exchange cross sections in collisions of rubidium isotopes in the ground state
NASA Astrophysics Data System (ADS)
Kartoshkin, V. A.
2015-10-01
Complex spin-exchange cross sections are calculated on the basis of the data on the singlet ( X 1?+) and triplet ( a 3?+) potentials describing the interaction of isotopes of Rb alkali-metal atoms in the ground state. The cross sections calculated in this study are compared with the cross-section data obtained earlier with the model interaction potentials. The cross-section values allow one to calculate the processes of polarization transfer and the relaxation times, as well as the magnetic resonance frequency shifts caused by the Rb?Rb spin-exchange collisions.
Alternative ground states enable pathway switching in biological electron transfer
Abriata, Luciano A.; Álvarez-Paggi, Damián; Ledesma, Gabriela N.; Blackburn, Ninian J.; Vila, Alejandro J.; Murgida, Daniel H.
2012-01-01
Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant CuA redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or “invisible” electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein–protein interactions and membrane potential may optimize and regulate electron–proton energy transduction. PMID:23054836
Dimerized ground states in spin-S frustrated systems
NASA Astrophysics Data System (ADS)
Lamas, C. A.; Matera, J. M.
2015-09-01
We study a family of frustrated antiferromagnetic spin-S systems with a fully dimerized ground state. Starting from the simplest case of the frustrated zigzag spin ladder, we generalize the family to more complex geometries like tetrahedral ladders and spin tubes. After presenting some numerical results about the phase diagram of these systems, we show that the ground state is robust against the inclusion of weak disorder in the couplings as well as several kinds of perturbations, allowing to study some other interesting models as a perturbative expansion of the exact one. A discussion on how to determine the dimerization region in terms of quantum information estimators is also presented. Finally, we explore the relation of these results with the case of a four-leg spin tube, which recently was proposed as a model for the description of the compound Cu2Cl4D8C4SO2 , delimiting the region of the parameter space where this model presents dimerization in its ground state.
Efficient determination of alloy ground-state structures
NASA Astrophysics Data System (ADS)
Seko, Atsuto; Shitara, Kazuki; Tanaka, Isao
2014-11-01
We propose an efficient approach to accurately finding the ground-state structures in alloys based on the cluster expansion method. In this approach, a small number of candidate ground-state structures are obtained without any information regarding the energy. To generate the candidates, we employ the convex hull constructed from the correlation functions of all possible structures by using an efficient algorithm. This approach is applicable to not only simple lattices, but also complex lattices. First, we evaluate the convex hulls for binary alloys with four types of simple lattice. Then we discuss the structures on the vertices. To examine the accuracy of this approach, we perform a set of density functional theory calculations and the cluster expansion for the Ag-Au alloy and compare the formation energies of the vertex structures with those of all possible structures. As applications, the ground-state structures of the intermetallic compounds CuAu, CuAg, CuPd, AuAg, AuPd, AgPd, MoTa, MoW, and TaW are similarly evaluated. Finally, the energy distribution is obtained for different cation arrangements in the MgAl2O4 spinel, for which long-range interactions are essential for the accurate description of its energetics.
Ground state magnetic response of two coupled dodecahedra.
Konstantinidis, N P
2016-01-13
The antiferromagnetic Heisenberg model on the dodecahedron possesses a number of ground state magnetization discontinuities in a field at the classical and quantum level, even though it lacks magnetic anisotropy. Here the model is considered for two dodecahedra coupled antiferromagnetically along one of their faces, as a first step to determine the magnetic response of collections of fullerene molecules. The magnetic response is determined from the competition among the intra-, interdodecahedral exchange and magnetic field energies. At the classical level the discontinuities of the isolated dodecahedron are renormalized by the interdodecahedral coupling, while new ones show up, with the maximum number of ground state discontinuities being six for a specific range of the coupling. In the full quantum limit where the individual spin magnitude [Formula: see text], there are two ground state discontinuities originating in the single discontinuity of the isolated dodecahedron, and another one due to the intermolecular coupling, generating a total of three discontinuities which come one right after the other. These results show that the magnetic response of more than one dodecahedra interacting together is quite richer than the one of a single dodecahedron. PMID:26643035
NASA Astrophysics Data System (ADS)
Seybold, P. G.; Kier, L. B.; Cheng, C.-K.
1999-12-01
Emissions from the 1S and 1D excited states of atomic oxygen play a prominent role in creating the dramatic light displays (aurora borealis) seen in the skies over polar regions of the Northern Hemisphere. A probabilistic asynchronous cellular automaton model described previously has been applied to the excited-state dynamics of atomic oxygen. The model simulates the time-dependent variations in ground (3P) and excited-state populations that occur under user-defined probabilistic transition rules for both pulse and steady-state conditions. Although each trial simulation is itself an independent "experiment", deterministic values for the excited-state emission lifetimes and quantum yields emerge as limiting cases for large numbers of cells or large numbers of trials. Stochastic variations in the lifetimes and emission yields can be estimated from repeated trials.
Microstructure of as-fabricated UMo/Al(Si) plates prepared with ground and atomized powder
NASA Astrophysics Data System (ADS)
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
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.
Kohn-Sham Theory for Ground-State Ensembles
Ullrich, C. A.; Kohn, W.
2001-08-27
An electron density distribution n(r) which can be represented by that of a single-determinant ground state of noninteracting electrons in an external potential v(r) is called pure-state v -representable (P-VR). Most physical electronic systems are P-VR. Systems which require a weighted sum of several such determinants to represent their density are called ensemble v -representable (E-VR). This paper develops formal Kohn-Sham equations for E-VR physical systems, using the appropriate coupling constant integration. It also derives local density- and generalized gradient approximations, and conditions and corrections specific to ensembles.
NASA Technical Reports Server (NTRS)
Cross, J. B.; Lan, E. H.; Smith, C. A.; Whatley, W. J.; Koontz, S. L.
1990-01-01
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.
NASA Technical Reports Server (NTRS)
Cross, J. B.; Lan, E. H.; Smith, C. A.; Whatley, W. J.
1990-01-01
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.
Dissociation energy of the ground state of NaH
Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen; Chang, Yung-Yung; Tsai, Chin-Chun
2010-07-28
The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9{<=}v{sup ''}{<=}21 and 1{<=}J{sup ''}{<=}14 were assigned to the X {sup 1}{Sigma}{sup +} state of NaH. The highest vibrational level observed was only about 40 cm{sup -1} from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation v{sub D} from the highest four vibrational levels yielded the dissociation energy D{sub e}=15 815{+-}5 cm{sup -1}. Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.
Oh, J H; Lee, K-J; Lee, Hyun-Woo; Shin, M
2014-05-14
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
Coherent Population Trapping Based Collective State Atomic Clock Using Trapped Atoms
NASA Astrophysics Data System (ADS)
Kim, May E.; Fang, Renpeng; Sarkar, Resham; Shahriar, Selim M.
2015-05-01
In most atomic clocks, the signal collection efficiency is limited to only a few percent due to unavoidable geometric constraints, which limits its stability. We describe a coherent population trapping (CPT) based atomic clock that can achieve a much higher collection efficiency, and has reduction in linewidth by factor of ?{ N}, where N is number of atoms. The CPT process pumps atoms into dark state, | - > , which is a superposition of two atomic states. When all atoms are in | - > , the system is in collective state | ED > = | - , - , - , . . . - > . The signal corresponding to measurement of | ED > has resonance that is narrowed by ?{ N} compared to the width in conventional CPT clock. This narrowing results from interference among collective states, and can be interpreted as manifestation of effective increase in clock frequency by ?{ N}. The amplitude of | ED > can be observed via null measurement of bright state | + > . When no fluorescence from | + > is detected, the system is in | ED > . By coherent Raman scattering of anti-Stokes photons in an optically dense cloud of cold atoms, the collection efficiency approaches unity, which improves clock stability significantly, leading to advance in precision time keeping.
$K^-$ and $\\bar p$ deeply bound atomic states
E. Friedman; A. Gal
1999-07-14
The strongly absorptive optical potentials $V_{{\\rm opt}}$ which have been deduced from the strong-interaction level shifts and widths in X-ray spectra of $K^-$ and $\\bar p$ atoms produce effective repulsion leading to substantial suppression of the {\\it atomic} wave functions within the nucleus. The width of atomic levels then saturates as function of the strength of Im $V_{{\\rm opt}}$. We find that `deeply bound' atomic states, which are inaccessible in the atomic cascade process, are generally narrow, due to this mechanism, over the entire periodic table %reaching values of $\\Gamma_{K^-} \\sim 1.7$ MeV and %$\\Gamma_{\\bar p} \\sim 1.9$ MeV for the $1s$ state in Pb, and should be reasonably well resolved. These predictions are insensitive to $V_{{\\rm opt}}$, provided it was fitted to the observed X-ray spectra. In contrast, the {\\it nuclear} states bound by $V_{{\\rm opt}}$ are very broad and their spectrum depends sensitively on details of $V_{{\\rm opt}}$. We discuss production reactions for $K^-$ atomic states using slow $K^-$ mesons from the decay of the $\\phi$(1020) vector meson, and the ($\\bar p, p$) reaction for $\\bar p$ atomic states. Rough cross-section estimates are given.
Ground state cooling of nanomechanical resonator via linear coupling in a superconducting circuit
NASA Astrophysics Data System (ADS)
Tian, Lin
2009-03-01
In recent experiments, it has been demonstrated that radiation pressure-like coupling between a nanomechanical resonator and a superconducting resonator can be explored for the cooling of the nanomechanical mode. In this work, We present a ground state cooling scheme for a nanomechanical resonator linearly coupled with a superconducting LC oscillator. The linear coupling, when periodically modulated at red detuning, up-converts the low-frequency nanomechanical mode to the high- frequency LC oscillator mode and generates backaction force that can cool the nanomechanical mode to its ground state in the resolved-sideband regime. Compared with schemes using radiation pressure-like coupling, the LC oscillator mode doesn't need to be driven to high photon occupation number in our scheme. We calculate the cooling rate and the stationary occupation number of the nanomechanical mode and show that ground state can be reached with practical device parameters. A detailed study of our model shows that the quantum backaction noise that limits the cooling process is due to the counter rotating terms in the linear coupling. The scheme can be compared with laser cooling for the atomic systems as well.
Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications.
Saeedi, K; Szech, M; Dluhy, P; Salvail, J Z; Morse, K J; Riemann, H; Abrosimov, N V; Nötzel, N; Litvinenko, K L; Murdin, B N; Thewalt, M L W
2015-01-01
The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched (28)Si. PMID:25990870
Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications
Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J.Z.; Morse, K.J.; Riemann, H.; Abrosimov, N.V.; Nötzel, N.; Litvinenko, K.L.; Murdin, B.N.; Thewalt, M.L.W.
2015-01-01
The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si. PMID:25990870
Earthquake Ground Motion Simulations in the Central United States
NASA Astrophysics Data System (ADS)
Ramirez Guzman, L.; Boyd, O. S.; Hartzell, S.; Williams, R. A.
2010-12-01
The Central United States (CUS) includes two of the major seismic zones east of the Rockies: the New Madrid and Wabash Valley Seismic Zones. The winter 1811-1812 New Madrid Seismic Zone (NMSZ) events were the largest intraplate sequence ever recorded in the United States. Together with their aftershocks, these earthquakes produced large areas of liquefaction, new lakes, and landslides in the region. Seismicity in the early 1800’s was dominated by the NMSZ activity, although three low magnitude 5 earthquakes occurred in the last 40 years in the Wabash Valley Seismic Zone (WVSZ). The population and infrastructure of the CUS have drastically changed from that of the early nineteenth century, and a large earthquake would now cause significant casualties and economic losses within the country’s heartland. In this study we present three sets of numerical simulations depicting earthquakes in the region. These hypothetical ruptures are located on the Reelfoot fault and the southern axial arm of the NMSZ and in the WVSZ. Our broad-band synthetic ground motions are calculated following the Liu et al. (2006) hybrid method. Using a finite element solver we calculate low frequency ground motion (< 1 Hz) which accounts for the heterogeneity and low velocity soils of the region by using a recently developed seismic velocity model (CUSVM1) and a minimum shear wave velocity of 300 m/s. The broad-band ground motions are then generated by combining high frequency synthetics computed in a 1D velocity model with the low frequency motions at a crossover frequency of 1 Hz. We primarily discuss the basin effects produced by the Mississippi embayment and investigate the effects of hypocentral location and slip distribution on ground motions in densely populated areas within the CUS.
Equatorial ground ice on Mars: Steady-state stability
NASA Technical Reports Server (NTRS)
Mellon, Michael T.; Jakosky, Bruce M.; Postawko, Susan E.
1993-01-01
Current Martian equatorial surface temperatures are too warm for water ice to exist at the surface for any appreciable length of time before subliming into the atmosphere. Subsurface temperatures are generally warmer still and, despite the presence of a diffusive barrier of porous regolith material, it has been shown by Smoluchowski, Clifford and Hillel, and Fanale et al. that buried ground ice will also sublime and be lost to the atmosphere in a relatively short time. We investigate the behavior of this subliming subsurface ice and show that it is possible for ice to maintain at a steady-state depth, where sublimation and diffusive loss to the atmosphere is balanced by resupply from beneath by diffusion and recondensation of either a deeper buried ice deposits or ground water. We examine the behavior of equatorial ground ice with a numercial time-marching molecular diffusion model. In our model we allow for diffusion of water vapor through a porous regolith, variations in diffusivity and porosity with ice content, and recondensation of sublimed water vapor. A regolith containing considerable amounts of ice can still be very porous, allowing water vapor to diffuse up from deeper within the ice layer where temperatures are warmer due to the geothermal gradient. This vapor can then recondense nearer to the surface where ice had previously sublimed and been lost to the atmosphere. As a result we find that ice deposits migrate to find a steady-state depth, which represents a balance between diffusive loss to the atmosphere through the overlying porous regolith and diffusive resupply through a porous icy regolith below. This depth depends primarily on the long-term mean surface temperature and the nature of the geothermal gradient, and is independent of the ice-free porosity and the regolith diffusivity. Only the rate of loss of ground ice depends on diffusive properties.
Low Frequency Gravitational Wave Detection With Ground Based Atom Interferometer Arrays
Chaibi, W; Canuel, B; Bertoldi, A; Landragin, A; Bouyer, P
2016-01-01
We propose a new detection strategy for gravitational waves (GWs) below few Hertz based on a correlated array of atom interferometers (AIs). Our proposal allows to reduce the Newtonian Noise (NN) which limits all ground based GW detectors below few Hertz, including previous atom interferometry-based concepts. Using an array of long baseline AI gradiometers yields several estimations of the NN, whose effect can thus be reduced via statistical averaging. Considering the km baseline of current optical detectors, a NN rejection of factor 2 could be achieved, and tested with existing AI array geometries. Exploiting the correlation properties of the gravity acceleration noise, we show that a 10-fold or more NN rejection is possible with a dedicated configuration. Considering a conservative NN model and the current developments in cold atom technology, we show that strain sensitivities below $1\\times 10^{-19}/ \\sqrt{\\text{Hz}}$ in the $ 0.3-3 \\ \\text{Hz}$ frequency band can be within reach, with a peak sensitivity o...
Absence of Energy Level Crossing for the Ground State Energy of the Rabi Model
Masao Hirokawa; Fumio Hiroshima
2012-07-17
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
Quantum Light Storage in Solid State Atomic Ensembles
Hugues de Riedmatten; Mikael Afzelius
2015-02-01
In this chapter, we will describe the storage and retrieval of quantum light (heralded single photons and entangled photons) in atomic ensembles in a solid state environment. We will consider ensembles of rare-earth ions embedded in dielectric crystals. We will describe the methods used to create quantum light spectrally compatible with the narrow atomic transitions, as well as possible protocols based on dipole rephasing that can be used to reversibly map the quantum light onto collective atomic excitations. We will review the experimental state of the art and describe in more detail quantum light storage experiments in neodymium and praseodymium doped crystals.
Adiabatic control of atomic dressed states for transport and sensing
NASA Astrophysics Data System (ADS)
Cooper, N. R.; Rey, A. M.
2015-08-01
We describe forms of adiabatic transport that arise for dressed-state atoms in optical lattices. Focusing on the limit of weak tunnel-coupling between nearest-neighbor lattice sites, we explain how adiabatic variation of optical dressing allows control of atomic motion between lattice sites: allowing adiabatic particle transport in a direction that depends on the internal state, and force measurements via spectroscopic preparation and readout. For uniformly filled bands these systems display topologically quantized particle transport. An implementation of the dressing scheme using optical transitions in alkaline-earth atoms is discussed as well as its favorable features for precise force sensing.
Adiabatic Control of Atomic Dressed States for Transport and Sensing
Cooper, N. R.; Rey, A. M.
2015-08-12
only spectroscopic control. The local description also allows one to under- stand in simple terms the role of inter-atomic interac- tions. We discuss an implementation using the long-lived clock states in alkaline earth atoms (AEA)[15–17]. We consider a... , 21]. Our dressed state approach allows measurements of ?V/h using the same spectroscopic methods as those developed in atomic clocks and it is not limited to quantum degenerate con- ditions. In fact it can be implemented in current AEA optical lattice...
NASA Technical Reports Server (NTRS)
deGroh, Kim K.; Banks, Bruce A.; Ma, David
2004-01-01
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.
Estimating the ground-state probability of a quantum simulation with product-state measurements
NASA Astrophysics Data System (ADS)
Yoshimura, Bryce; Freericks, James
2015-10-01
.One of the goals in quantum simulation is to adiabatically generate the ground state of a complicated Hamiltonian by starting with the ground state of a simple Hamiltonian and slowly evolving the system to the complicated one. If the evolution is adiabatic and the initial and final ground states are connected due to having the same symmetry, then the simulation will be successful. But in most experiments, adiabatic simulation is not possible because it would take too long, and the system has some level of diabatic excitation. In this work, we quantify the extent of the diabatic excitation even if we do not know a priori what the complicated ground state is. Since many quantum simulator platforms, like trapped ions, can measure the probabilities to be in a product state, we describe techniques that can employ these simple measurements to estimate the probability of being in the ground state of the system after the diabatic evolution. These techniques do not require one to know any properties about the Hamiltonian itself, nor to calculate its eigenstate properties. All the information is derived by analyzing the product-state measurements as functions of time.
Photoionization of Fe7+ from the ground and metastable states
NASA Astrophysics Data System (ADS)
Tayal, S. S.; Zatsarinny, O.
2015-01-01
The B -spline Breit-Pauli R -matrix method is used to investigate the photoionization of Fe7 + from the ground and metastable states in the energy region from ionization thresholds to 172 eV. The present calculations were designed to resolve the large discrepancies between recent measurements and available theoretical results. The multiconfiguration Hartree-Fock method in connection with B -spline expansions is employed for an accurate representation of the initial- and final-state wave functions. The close-coupling expansion includes 99 fine-structure levels of the residual Fe8 + ion in the energy region up to 3 s23 p54 s states. It includes levels of the 3 s23 p6,3 s23 p53 d ,3 s23 p54 s , and 3 s 3 p63 d configurations and some levels of the 3 s23 p43 d2 configuration which lie in the energy region under investigation. The present photoionization cross sections in the length and velocity formulations exhibit excellent agreement. The present photoionization cross sections agree well with the Breit-Pauli R -matrix calculation by Sossah et al. and the TOPbase data in the magnitude of the background nonresonant cross sections but show somewhat richer resonance structures, which qualitatively agree with the measurements. The calculated cross sections, however, are several times lower than the measured cross sections, depending upon the photon energy. The cross sections for photoionization of metastable states were found to have approximately the same magnitude as the cross sections for photoionization of the ground state, thereby the presence of metastable states in the ion beam may not be the reason for the enhancement of the measured cross sections.
Ground-state Electronic Structure of Actinide Monocarbides and Mononitrides
Petit, Leon; Svane, Axel; Szotek, Zdzislawa; Temmerman, Walter M; Stocks, George Malcolm
2009-01-01
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.
Manipulation of Non-classical Atomic Spin States
Tetsushi Takano; Shin-Ichi-Ro Tanaka; Ryo Namiki; Yoshiro Takahashi
2009-09-13
We report successful manipulation of non-classical atomic spin states. We generate squeezed spin states by a spin quantum nondemolition measurement, and apply an off-resonant circularly-polarized light pulse to the atoms. By changing the pulse duration, we have clearly observed a rotation of anisotropic quantum noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum noise distribution is always isotropic. This is an important step for quantum state tomography, quantum swapping, and precision spectroscopic measurement.
Ground-Laboratory to In-Space Effective Atomic-Oxygen Fluence Determined for DC 93-500 Silicone
NASA Technical Reports Server (NTRS)
deGroh, Kim K.; Banks, Bruce A.; Ma, David
2005-01-01
Surfaces on the leading edge of spacecraft in low Earth orbit (e.g., surface facing the velocity direction), such as on the International Space Station, are subject to atomic oxygen attack, and certain materials are susceptible to erosion. Therefore, ground-based laboratory testing of the atomic oxygen durability of spacecraft materials is necessary for durability assessment when flight data are not available. For accurate space simulation, the facility is commonly calibrated on the basis of the mass loss of Kapton (DuPont, Wilmington, DE) as a control sample for effective fluence determination. This is because Kapton has a well-characterized atomic oxygen erosion yield (E(sub y), in cubic centimeters per atom) in the low Earth orbit (LEO) environment. Silicones, a family of commonly used spacecraft materials, do not chemically erode away with atomic oxygen attack like other organic materials that have volatile oxidation products. Instead, silicones react with atomic oxygen and form an oxidized hardened silicate surface layer. Often the loss of methyl groups causes shrinkage of the surface skin and "mud-tile" crazing degradation. But silicones often do not lose mass, and some silicones actually gain mass during atomic oxygen exposure. Therefore, the effective atomic oxygen fluence for silicones in a ground-test facility should not be determined on the basis of traditional mass-loss measurements, as it is with polymers that erode. Another method for determining effective fluence needs to be employed for silicones. A new technique has been developed at the NASA Glenn Research Center for determining the effective atomic oxygen fluence for silicones in ground-test facilities. This technique determines the equivalent amount of atomic oxygen oxidation on the basis of changes in the surface-oxide hardness. The specific approach developed was to compare changes in the surface hardness of ground-laboratory-exposed DC93-500 silicone with DC93-500 exposed to LEO atomic oxygen as part of a shuttle flight experiment. The on-the-ground to in-space effective atomic oxygen fluence was determined on the basis of the Kapton effective fluence in the ground-laboratory facility that produced the same hardness for the fluence in space.
Detecting Topological Order in a Ground State Wave Function
Levin, Michael; Wen Xiaogang
2006-03-24
A large class of topological orders can be understood and classified using the string-net condensation picture. These topological orders can be characterized by a set of data (N,d{sub i},F{sub lmn}{sup ijk},{delta}{sub ijk}). We describe a way to detect this kind of topological order using only the ground state wave function. The method involves computing a quantity called the 'topological entropy' which directly measures the total quantum dimension D=id{sub i}{sup 2}.
Monogamy and ground-state entanglement in highly connected systems
Ferraro, Alessandro; Garcia-Saez, Artur; Acin, Antonio
2007-11-15
We consider the ground-state entanglement in highly connected many-body systems consisting of harmonic oscillators and spin-1/2 systems. Varying their degree of connectivity, we investigate the interplay between the enhancement of entanglement, due to connections, and its frustration, due to monogamy constraints. Remarkably, we see that in many situations the degree of entanglement in a highly connected system is essentially of the same order as in a low connected one. We also identify instances in which the entanglement decreases as the degree of connectivity increases.
Ground-state electric quadrupole moment of 31Al
D. Nagae; H. Ueno; D. Kameda; M. Takemura; K. Asahi; K. Takase; A. Yoshimi; T. Sugimoto; K. Shimada; T. Nagatomo; M. Uchida; T. Arai; T. Inoue; S. Kagami; N. Hatakeyama; H. Kawamura; K. Narita; J. Murata
2008-10-16
Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms) has been measured by means of the beta-NMR spectroscopy using a spin-polarized 31Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell model calculations within the sd valence space. Previous result on the magnetic moment also supports the validity of the sd model in this isotope, and thus it is concluded that 31Al is located outside of the island of inversion.
Ground state of the one dimensional Gross-Pitaevskii equation with a Morse potential
Sukla Pal; Jayanta K. Bhattacharjee
2013-09-21
We have studied the ground state of the Gross-Pitaevskii equation (nonlinear Schrodinger equation) for a Morse potential via a variational approach. It is seen that the ground state ceases to be bound when the coupling constant of the nonlinear term reaches a critical value. The disappearence of the ground state resembles a saddle node bifurcation.
UV Resonance Raman Ground and Excited State Studies of Amide and Peptide Isomerization Dynamics
Asher, Sanford A.
UV Resonance Raman Ground and Excited State Studies of Amide and Peptide Isomerization Dynamics the first measurements of the activation barrier for ground state trans-cis isomerization of secondary determined from the temperature dependence of the ground state isomerization rates, which were measured
Calculation of hyperfine coupling constants of the CN and CP ground state radicals
Simons, Jack
Calculation of hyperfine coupling constants of the CN and CP ground state radicals Berta Fern investigation, we have determined accurately the hyperfme coupling constants of the ground states of CN and CP a detailed and thorough study of the hyperfine coupling constants of the X `X+ ground states of CN and CP
Single-Atom Gating of Quantum State Superpositions
Moon, Christopher
2010-04-28
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.
Face-dependent Auger neutralization and ground-state energy shift for He in front of Al surfaces
Wethekam, S.; Winter, H.; Valdes, Diego; Monreal, R. C.
2008-08-15
He atoms and ions with keV energies are scattered under grazing angles of incidence from Al(111), Al(100), and Al(110) surfaces. Fractions of surviving ions and normal energy gains of He{sup +} ions prior to neutralization, derived from shifts of angular distributions for incident atoms and ions, are compared to results from three-dimensional Monte Carlo simulations based on theoretically calculated Auger neutralization rates and He ground-state energy shifts. From the good agreement of experimental data with simulations, we conclude a detailed microscopic understanding for a model system of ion-surface interactions. Our work provides further evidence for the recently reported surface Miller index dependence for the neutralization of He{sup +} ions at metal surfaces. The study is extended to the face dependence of the He ground-state energy shift.
Ground state of finite nuclei evaluated from realistic interactions
Kh. Gad; H. Müther
2002-05-08
Ground state properties of finite nuclei ($^{16}$O and $^{40}$Ca) are evaluated from realistic nucleon-nucleon interactions. The calculations are based on the Brueckner-Hartree-Fock approximation. Special attention is paid to the role of the energy spectrum for the particle states, in particular for those close to the Fermi energy. Additional binding energy is obtained from the inclusion of the hole-hole scattering term within the framework of the Green function approach. Results for the energy distribution of the single-particle strength and the sensitivity to the nucleon-nucleon interaction are investigated. For that purpose three modern nucleon-nucleon interactions are employed: the Argonne V18, the charge dependent Bonn potential and a realistic nucleon-nucleon interaction which is based on chiral perturbation theory and which has recently been fitted by the Idaho group.
Ground states of partially connected binary neural networks
NASA Technical Reports Server (NTRS)
Baram, Yoram
1990-01-01
Neural networks defined by outer products of vectors over (-1, 0, 1) are considered. Patterns over (-1, 0, 1) define by their outer products partially connected neural networks consisting of internally strongly connected, externally weakly connected subnetworks. Subpatterns over (-1, 1) define subnetworks, and their combinations that agree in the common bits define permissible words. It is shown that the permissible words are locally stable states of the network, provided that each of the subnetworks stores mutually orthogonal subwords, or, at most, two subwords. It is also shown that when each of the subnetworks stores two mutually orthogonal binary subwords at most, the permissible words, defined as the combinations of the subwords (one corresponding to each subnetwork), that agree in their common bits are the unique ground states of the associated energy function.
Search for the ground state of {sup 11}N
Azhari, A.; Baumann, T.; Brown, J.A.
1995-04-01
The ground state of proton-unbound {sup 11}N is thought to consist of a broad s-wave state, but this has not been experimentally verified. Due to recent interest in this system, the authors have studied {sup 11}N using the neutron-stripping reaction {sup 9}Be({sup 12}N,{sup 11}N) at E({sup 12}N)= 40 MeV/A. The radioactive {sup 12}N beam was produced by projectile fragmentation of 80 MeV/A {sup 16}O using the NSCL A1200 fragment separator. Coincident proton and {sup 10}C particles from the inflight decay of {sup 11}N were detected and the decay energy of the composite system was determined from the measured energies and angles. Results from this study and model calculations will be present.
Cloning and variation of ground state intestinal stem cells.
Wang, Xia; Yamamoto, Yusuke; Wilson, Lane H; Zhang, Ting; Howitt, Brooke E; Farrow, Melissa A; Kern, Florian; Ning, Gang; Hong, Yue; Khor, Chiea Chuen; Chevalier, Benoit; Bertrand, Denis; Wu, Lingyan; Nagarajan, Niranjan; Sylvester, Francisco A; Hyams, Jeffrey S; Devers, Thomas; Bronson, Roderick; Lacy, D Borden; Ho, Khek Yu; Crum, Christopher P; McKeon, Frank; Xian, Wa
2015-06-11
Stem cells of the gastrointestinal tract, pancreas, liver and other columnar epithelia collectively resist cloning in their elemental states. Here we demonstrate the cloning and propagation of highly clonogenic, 'ground state' stem cells of the human intestine and colon. We show that derived stem-cell pedigrees sustain limited copy number and sequence variation despite extensive serial passaging and display exquisitely precise, cell-autonomous commitment to epithelial differentiation consistent with their origins along the intestinal tract. This developmentally patterned and epigenetically maintained commitment of stem cells is likely to enforce the functional specificity of the adult intestinal tract. Using clonally derived colonic epithelia, we show that toxins A or B of the enteric pathogen Clostridium difficile recapitulate the salient features of pseudomembranous colitis. The stability of the epigenetic commitment programs of these stem cells, coupled with their unlimited replicative expansion and maintained clonogenicity, suggests certain advantages for their use in disease modelling and regenerative medicine. PMID:26040716
Hexagonal-close-packed lattice: Ground state and phase transition.
Hoang, Danh-Tai; Diep, H T
2012-04-01
We study the ground state (GS) and the phase transition in a hexagonal-close-packed lattice with both XY and Ising models by using extensive Monte Carlo simulation. We suppose the in-plane interaction J1 and interplane interaction J2, both antiferromagnetic. The system is frustrated with two kinds of GS configuration below and above a critical value of ?=J1/J2 (?c). For the Ising case, one has ?c=0.5 which separates in-plane ferromagnetic and antiferromagnetic states, while for the XY case ?c=1/3 separates the collinear and noncollinear spin configurations. The phase transition is shown to be of first (second) order for ?>(<)?c. The phase diagram in the space (?,T) is shown for both cases. PMID:22680420
Approximating Ground and Excited State Energies on a Quantum Computer
Stuart Hadfield; Anargyros Papageorgiou
2015-08-06
Approximating ground and a fixed number of excited state energies, or equivalently low order Hamiltonian eigenvalues, is an important but computationally hard problem. Typically, the cost of classical deterministic algorithms grows exponentially with the number of degrees of freedom. Under general conditions, and using a perturbation approach, we provide a quantum algorithm that produces estimates of a constant number $j$ of different low order eigenvalues. The algorithm relies on a set of trial eigenvectors, whose construction depends on the particular Hamiltonian properties. We illustrate our results by considering a special case of the time-independent Schr\\"odinger equation with $d$ degrees of freedom. Our algorithm computes estimates of a constant number $j$ of different low order eigenvalues with error $O(\\epsilon)$ and success probability at least $\\frac34$, with cost polynomial in $\\frac{1}{\\epsilon}$ and $d$. This extends our earlier results on algorithms for estimating the ground state energy. The technique we present is sufficiently general to apply to problems beyond the application studied in this paper.
Magnetic ground state of semiconducting transition metal trichalcogenide monolayers
Sivadas, Mr. Nikhil; Daniels, Matthew W.; Swendsen, Robert H.; Okamoto, Satoshi; Xiao, Di
2015-01-01
Layered transition-metal trichalcogenides with the chemical formula ABX3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides.We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperature of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic N eel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. Our study suggests that ABX3 can be a promising platform to explore two-dimensional magnetic phenomena.
The ground state rotational spectrum of SO 2F 2
NASA Astrophysics Data System (ADS)
Rotger, M.; Boudon, V.; Loëte, M.; Margulès, L.; Demaison, J.; Mäder, H.; Winnewisser, G.; Müller, H. S. P.
2003-12-01
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.
T. Werlang; R. Guzman; F. O. Prado; C. J. Villas-Boas
2008-06-17
We present a way to engineer an effective anti-Jaynes-Cumming and a Jaynes-Cumming interaction between an atomic system and a single cavity mode and show how to employ it in reservoir engineering processes. To construct the effective Hamiltonian, we analyse considered the interaction of an atomic system in a \\{Lambda} configuration, driven by classical fields, with a single cavity mode. With this interaction, we firstly show how to generate a decoherence-free displaced squeezed state for the cavity field. In our scheme, an atomic beam works as a reservoir for the radiation field trapped inside the cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401 (2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in high-Q resonators. In our scheme, all the atoms have to be prepared in the ground state and, as in the cited article, neither atomic detection nor precise interaction times between the atoms and the cavity mode are required. From this same interaction, we can also generate an ideal squeezed reservoir for atomic systems. For this purpose we have to assume, besides the engineered atom-field interaction, a strong decay of the cavity field (i.e., the cavity decay must be much stronger than the effective atom-field coupling). With this scheme, some interesting effects in the dynamics of an atom in a squeezed reservoir could be tested.
Transmission-line decelerators for atoms in high Rydberg states
NASA Astrophysics Data System (ADS)
Lancuba, P.; Hogan, S. D.
2014-11-01
Beams of helium atoms in Rydberg states with principal quantum number n =52 , and traveling with an initial speed of 1950 m/s, have been accelerated, decelerated, and guided while confined in moving electric traps generated above a curved, surface-based electrical transmission line with a segmented center conductor. Experiments have been performed with atoms guided at constant speed, and with accelerations exceeding 107 m /s 2. In each case, the manipulated atoms were detected by spatially resolved, pulsed electric field ionization. The effects of tangential and centripetal accelerations on the effective trapping potentials experienced by the atoms in the decelerator have been studied, with the resulting observations highlighting contributions from the density of excited Rydberg atoms to the acceleration, deceleration, and guiding efficiencies in the experiments.
Transition properties of low-lying states in atomic indium
Sahoo, B. K.; Das, B. P.
2011-07-15
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.
Characterization of a state-insensitive dipole trap for cesium atoms
Phoonthong, P.; Douglas, P.; Wickenbrock, A.; Renzoni, F.
2010-07-15
In this work we characterize a state-insensitive dipole trap for cold cesium atoms, as realized by tightly focusing a single running laser beam at the magic wavelength. The use of trapping light at the magic wavelength of 935.6 nm resulted in the same ac Stark shift for the {sup 6}S{sub 1/2} ground state and the {sup 6}P{sub 3/2} excited state. A complete characterization of the trap is given, which includes the dependence of the lifetime on the trap depth, an analysis of the important role played by a depumper beam, and a comparison with dipole trapping at different (nonmagic) wavelengths. In particular, we measured the differential light shift of the relevant optical transition as a function of the trapping light wavelength, and showed that it becomes zero at the magic wavelength. Our results are compared to previous realizations of state-insensitive dipole traps for cesium atoms. We also discuss the possible role of the state-insensitive trap, its limitations, and possible developments for the study of ground-state quantum coherence phenomena and related applications.
All-electric control of single atom spin states
NASA Astrophysics Data System (ADS)
Otte, Sander
2011-03-01
The quantum state of a single spin is a great candidate for forming a qubit. Spin systems in various forms are considered for the task, ranging from electrons trapped in artificial quantum dots to magnetic dopants in semiconductors and diamond. In this talk I will review recent progress towards controlling the spins of individual atoms on a surface through local access with an STM probe tip: an intriguing approach in view of the possibility to rearrange the atoms at will so as to build multi-atom structures. Magnetic d-metal atoms, separated from a metal substrate by a thin decoupling layer, are studied through inelastic electron tunneling spectroscopy (IETS): a tool by which transition energies of the spin state can be accurately followed. By addressing the atoms with a spin-filtered probe tip, controlled excitations or de-excitations can be made, effectively pumping the spin into a magnetization direction of choice. In a more recent experiment, spin pumping is performed in short pulses, opening up ways to control atomic spins in the time domain. I will discuss avenues to further develop this technique, eventually leading to coherent control of an atomic spin qubit.
Symmetry adapted coherent states for three-level atoms interacting with one-mode radiation
NASA Astrophysics Data System (ADS)
López-Peña, R.; Cordero, S.; Nahmad-Achar, E.; Castaños, O.
2015-06-01
We introduce a combination of coherent states as variational test functions for the atomic and radiation sectors to describe a system of Na three-level atoms interacting with a one-mode quantised electromagnetic field, with and without the rotating wave approximation, which preserves the symmetry presented by the Hamiltonian. These provide us with the possibility of finding analytical solutions for the ground and first excited states. We study the properties of these solutions for the V-configuration in the double resonance condition, and calculate the expectation values of the number of photons, the atomic populations, the total number of excitations, and their corresponding fluctuations. We also calculate the photon number distribution and the linear entropy of the reduced density matrix to estimate the entanglement between matter and radiation. For the first time, we exhibit analytical expressions for all of these quantities, as well as an analytical description for the phase diagram in parameter space, which distinguishes the normal and collective regions, and which gives us all the quantum phase transitions of the ground state from one region to the other as we vary the interaction parameters (the matter-field coupling constants) of the model, in functional form.
Symmetry Adapted Coherent States for Three-Level Atoms Interacting with One-Mode Radiation
R. López-Peña; S. Cordero; E. Nahmad-Achar; O. Castaños
2015-10-21
We introduce a combination of coherent states as variational test functions for the atomic and radiation sectors to describe a system of Na three- level atoms interacting with a one-mode quantised electromagnetic field, with and without the rotating wave approximation, which preserves the symmetry presented by the Hamiltonian. These provide us with the possibility of finding analytical solutions for the ground and first excited states. We study the properties of these solutions for the V-configuration in the double resonance condition, and calculate the expectation values of the number of photons, the atomic populations, the total number of excitations, and their corresponding fluctuations. We also calculate the photon number distribution and the linear entropy of the reduced density matrix to estimate the entanglement between matter and radiation. For the first time, we exhibit analytical expressions for all of these quantities, as well as an analytical description for the phase diagram in parameter space, which distinguishes the normal and collective regions, and which gives us all the quantum phase transitions of the ground state from one region to the other as we vary the interaction parameters (the matter-field coupling constants) of the model, in functional form.
Steady state quantum discord for circularly accelerated atoms
NASA Astrophysics Data System (ADS)
Hu, Jiawei; Yu, Hongwei
2015-12-01
We study, in the framework of open quantum systems, the dynamics of quantum entanglement and quantum discord of two mutually independent circularly accelerated two-level atoms in interaction with a bath of fluctuating massless scalar fields in the Minkowski vacuum. We assume that the two atoms rotate synchronically with their separation perpendicular to the rotating plane. The time evolution of the quantum entanglement and quantum discord of the two-atom system is investigated. For a maximally entangled initial state, the entanglement measured by concurrence diminishes to zero within a finite time, while the quantum discord can either decrease monotonically to an asymptotic value or diminish to zero at first and then followed by a revival depending on whether the initial state is antisymmetric or symmetric. When both of the two atoms are initially excited, the generation of quantum entanglement shows a delayed feature, while quantum discord is created immediately. Remarkably, the quantum discord for such a circularly accelerated two-atom system takes a nonvanishing value in the steady state, and this is distinct from what happens in both the linear acceleration case and the case of static atoms immersed in a thermal bath.
NASA Astrophysics Data System (ADS)
Sarkar, Resham; Fang, Renpeng; Kim, May; Shahriar, Selim
2015-05-01
An ensemble of N independent, noninteracting 2-level atoms with states | 1 > and | 2 > , interacting with a laser, can be represented as a Coherent State of spin, depicting a superposition of N+1 symmetric collective states. This model is also valid for 3-level atoms where the ground states | 1 > and | 2 > are mutually coupled via off-resonant Raman interaction through an intermediate excited state | 3 > , upon adiabatic elimination thereof. We recently proposed a Collective State Atomic Interferometer (COSAIN) that splits, redirects and recombines such an ensemble to yield a signal that is a measurement of the ensemble state where all the atoms are simultaneously in state | 1 > . The width of the COSAIN signal fringe scales as 1 /?{ N} . This narrowing occurs due to the simultaneous interference of the N+1 arms of the COSAIN. A similar narrowing is also predicted for a Collective State Atomic Clock (COSAC) proposed by us. We will describe the effect of one-axis twist and two-axes twist spin squeezing on the behavior of the COSAIN and the COSAC in order to approach Heisenberg limited sensitivity. We will also discuss the prospect of implementing spin squeezed versions of these devices via the use of Rydberg assisted interaction among the atoms.
Ground-state phase diagram of the quantum Rabi model
NASA Astrophysics Data System (ADS)
Ying, Zu-Jian; Liu, Maoxin; Luo, Hong-Gang; Lin, Hai-Qing; You, J. Q.
2015-11-01
The Rabi model plays a fundamental role in understanding light-matter interaction. It reduces to the Jaynes-Cummings model via the rotating-wave approximation, which is applicable only to the cases of near resonance and weak coupling. However, recent experimental breakthroughs in upgrading light-matter coupling order require understanding the physics of the full quantum Rabi model (QRM). Despite the fact that its integrability and energy spectra have been exactly obtained, the challenge to formulate an exact wave function in a general case still hinders physical exploration of the QRM. Here we unveil a ground-state phase diagram of the QRM, consisting of a quadpolaron and a bipolaron as well as their changeover in the weak-, strong-, and intermediate-coupling regimes, respectively. An unexpected overweighted antipolaron is revealed in the quadpolaron state, and a hidden scaling behavior relevant to symmetry breaking is found in the bipolaron state. An experimentally accessible parameter is proposed to test these states, which might provide novel insights into the nature of the light-matter interaction for all regimes of the coupling strengths.
Ground-State Proton Transfer Kinetics in Green Fluorescent Protein
2015-01-01
Proton transfer plays an important role in the optical properties of green fluorescent protein (GFP). While much is known about excited-state proton transfer reactions (ESPT) in GFP occurring on ultrafast time scales, comparatively little is understood about the factors governing the rates and pathways of ground-state proton transfer. We have utilized a specific isotopic labeling strategy in combination with one-dimensional 13C nuclear magnetic resonance (NMR) spectroscopy to install and monitor a 13C directly adjacent to the GFP chromophore ionization site. The chemical shift of this probe is highly sensitive to the protonation state of the chromophore, and the resulting spectra reflect the thermodynamics and kinetics of the proton transfer in the NMR line shapes. This information is complemented by time-resolved NMR, fluorescence correlation spectroscopy, and steady-state absorbance and fluorescence measurements to provide a picture of chromophore ionization reactions spanning a wide time domain. Our findings indicate that proton transfer in GFP is described well by a two-site model in which the chromophore is energetically coupled to a secondary site, likely the terminal proton acceptor of ESPT, Glu222. Additionally, experiments on a selection of GFP circular permutants suggest an important role played by the structural dynamics of the seventh ?-strand in gating proton transfer from bulk solution to the buried chromophore. PMID:25184668
Microwave-dressed state-selective potentials for atom interferometry
NASA Astrophysics Data System (ADS)
Guarrera, V.; Szmuk, R.; Reichel, J.; Rosenbusch, P.
2015-08-01
We propose a novel and robust technique to realize a beam splitter for trapped Bose-Einstein condensates (BECs). The scheme relies on the possibility of producing different potentials simultaneously for two internal atomic states. The atoms are coherently transferred, via a Rabi coupling between the two long-lived internal states, from a single well potential to a double-well. We present numerical simulations supporting our proposal and confirming excellent efficiency and fidelity of the transfer process with realistic numbers for a BEC of 87Rb. We discuss the experimental implementation by suggesting state-selective microwave (MW) potentials as an ideal tool to be exploited for magnetically trapped atoms. The working principles of this technique are tested on our atom chip device which features an integrated coplanar MW guide. In particular, the first realization of a double-well potential by using a MW dressing field is reported. Experimental results are presented together with numerical simulations, showing good agreement. Simultaneous and independent control on the external potentials is also demonstrated in the two Rubidium clock states. The transfer between the two states, featuring respectively a single and a double-well, is characterized and it is used to measure the energy spectrum of the atoms in the double-well. Our results show that the spatial overlap between the two states is crucial to ensure the functioning of the beamsplitter. Even though this condition could not be achieved in our current setup, the proposed technique can be realized with current state-of-the-art devices being particularly well suited for atom chip experiments. We anticipate applications in quantum enhanced interferometry.
NASA Technical Reports Server (NTRS)
Stambler, Arielle H.; Inoshita, Karen E.; Roberts, Lily M.; Barbagallo, Claire E.; deGroh, Kim K.; Banks, Bruce A.
2011-01-01
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.
Thermodynamic ground state of MgB{sub 6} predicted from first principles structure search methods
Wang, Hui; Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 ; LeBlanc, K. A.; Gao, Bo; Yao, Yansun; Canadian Light Source, Saskatoon, Saskatchewan S7N 0X4
2014-01-28
Crystalline structures of magnesium hexaboride, MgB{sub 6}, were investigated using unbiased structure searching methods combined with first principles density functional calculations. An orthorhombic Cmcm structure was predicted as the thermodynamic ground state of MgB{sub 6}. The energy of the Cmcm structure is significantly lower than the theoretical MgB{sub 6} models previously considered based on a primitive cubic arrangement of boron octahedra. The Cmcm structure is stable against the decomposition to elemental magnesium and boron solids at atmospheric pressure and high pressures up to 18.3 GPa. A unique feature of the predicted Cmcm structure is that the boron atoms are clustered into two forms: localized B{sub 6} octahedra and extended B{sub ?} ribbons. Within the boron ribbons, the electrons are delocalized and this leads to a metallic ground state with vanished electric dipoles. The present prediction is in contrast to the previous proposal that the crystalline MgB{sub 6} maintains a semiconducting state with permanent dipole moments. MgB{sub 6} is estimated to have much weaker electron-phonon coupling compared with that of MgB{sub 2}, and therefore it is not expected to be able to sustain superconductivity at high temperatures.
From ground-state densities to entangled wave functions: an exploration for the Hubbard model
NASA Astrophysics Data System (ADS)
Capelle, Klaus
2015-03-01
The fundamental Hohenberg-Kohn theorem of density-functional theory (DFT) guarantees that, in principle, all information about a many-body system is contained in it ground-state density. Most effort in DFT is thus directed at finding ways to reliably calculate this density and to extract useful information from it. Quantum-information theory (QIT), on the other hand, is little concerned with ground-state densities, focusing instead on wave functions and density matrices, with a view on exploiting entangled states in information processing. In spite of these different philosophies, many connections exist between both approaches. In this talk, I review of how some of these connections have been discovered and quantified in the context of the Hubbard model: (i) DFT calculations for a model Hamiltonian serve to relate the entanglement entropy to phase transitions; (ii) a local-density-type approximation can be used to calculate the entanglement entropy of spatially inhomogeneous systems, such as cold atoms in optical traps and large superlattices, where traditional numerical methods encounter difficulties; (iii) a combination of DFT with Bethe-Ansatz techniques allows one to calculate the values of system-specific parameters in expressions for the block-block entanglement that remain undetermined in scaling approaches; (iv) the construction of suitable metrics shines light on how the Hohenberg-Kohn theorem relates densities and wave functions for different systems.
Correlated eikonal initial state in ion-atom collisions
Ciappina, M.F.; Otranto, S.; Garibotti, C.R.
2002-11-01
An approximation is developed to deal with the ionization of atoms by bare charged ions. In this method the transition amplitude describing the three-body final state is evaluated using a continuum correlated wave and that for the initial state by an analytical continuation of the {phi}{sub 2} model to complex momenta. This procedure introduces in the atomic bound state a kinematical correlation with the projectile motion. Doubly differential cross sections (DDCS's) are computed for collisions of H{sup +} and F{sup 9+} ions with He atoms. Results for the DDCS's in the forward direction are compared with experimental data and other theoretical models. We find an enhancement of the distribution for low energy electrons and that the asymmetry of the electron capture to the continuum (ECC) peak is correctly described.
Laser cooling of a nanomechanical oscillator into its quantum ground state.
Chan, Jasper; Alegre, T P Mayer; Safavi-Naeini, Amir H; Hill, Jeff T; Krause, Alex; Gröblacher, Simon; Aspelmeyer, Markus; Painter, Oskar
2011-10-01
The simple mechanical oscillator, canonically consisting of a coupled mass-spring system, is used in a wide variety of sensitive measurements, including the detection of weak forces and small masses. On the one hand, a classical oscillator has a well-defined amplitude of motion; a quantum oscillator, on the other hand, has a lowest-energy state, or ground state, with a finite-amplitude uncertainty corresponding to zero-point motion. On the macroscopic scale of our everyday experience, owing to interactions with its highly fluctuating thermal environment a mechanical oscillator is filled with many energy quanta and its quantum nature is all but hidden. Recently, in experiments performed at temperatures of a few hundredths of a kelvin, engineered nanomechanical resonators coupled to electrical circuits have been measured to be oscillating in their quantum ground state. These experiments, in addition to providing a glimpse into the underlying quantum behaviour of mesoscopic systems consisting of billions of atoms, represent the initial steps towards the use of mechanical devices as tools for quantum metrology or as a means of coupling hybrid quantum systems. Here we report the development of a coupled, nanoscale optical and mechanical resonator formed in a silicon microchip, in which radiation pressure from a laser is used to cool the mechanical motion down to its quantum ground state (reaching an average phonon occupancy number of 0.85 ± 0.08). This cooling is realized at an environmental temperature of 20?K, roughly one thousand times larger than in previous experiments and paves the way for optical control of mesoscale mechanical oscillators in the quantum regime. PMID:21979049
Stability of quantum-dot excited-state laser emission under simultaneous ground-state perturbation
Kaptan, Y. Herzog, B.; Schöps, O.; Kolarczik, M.; Woggon, U.; Owschimikow, N.; Röhm, A.; Lingnau, B.; Lüdge, K.; Schmeckebier, H.; Arsenijevi?, D.; Bimberg, D.; Mikhelashvili, V.; Eisenstein, G.
2014-11-10
The impact of ground state amplification on the laser emission of In(Ga)As quantum dot excited state lasers is studied in time-resolved experiments. We find that a depopulation of the quantum dot ground state is followed by a drop in excited state lasing intensity. The magnitude of the drop is strongly dependent on the wavelength of the depletion pulse and the applied injection current. Numerical simulations based on laser rate equations reproduce the experimental results and explain the wavelength dependence by the different dynamics in lasing and non-lasing sub-ensembles within the inhomogeneously broadened quantum dots. At high injection levels, the observed response even upon perturbation of the lasing sub-ensemble is small and followed by a fast recovery, thus supporting the capacity of fast modulation in dual-state devices.
Quantum interference effects on ground-state optomechanical cooling
NASA Astrophysics Data System (ADS)
Gu, Wen-ju; Li, Gao-xiang
2013-02-01
We propose a fast ground-state optomechanical cooling scheme through the use of a two-mode optical cavity with a quarter-wave plate inside. Two cavity modes are orthogonally polarized; one cavity mode dissipates to the external environment at a fast rate while the other dissipates at a slow rate. The quarter-wave plate provides linear mixing interaction between these two cavity modes. The cooling process is dominated by scattering process via the fast-decay channel, which is significantly enhanced as compared with that obtained in the resolved-sideband optomechanical cooling scheme. Meanwhile, the heating process is significantly suppressed by exploiting the destructive quantum interference between the two cavity modes with the help of the quarter-wave plate.
A new phenomenological formula for ground state binding energies
G. Gangopadhyay
2010-07-09
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.
Direct Spectroscopic Detection and EPR Investigation of a Ground State Triplet Phenyl Oxenium Ion.
Li, Ming-De; Albright, Toshia R; Hanway, Patrick J; Liu, Mingyue; Lan, Xin; Li, Songbo; Peterson, Julie; Winter, Arthur H; Phillips, David Lee
2015-08-19
Oxenium ions are important reactive intermediates in synthetic chemistry and enzymology, but little is known of the reactivity, lifetimes, spectroscopic signatures, and electronic configurations of these unstable species. Recent advances have allowed these short-lived ions to be directly detected in solution from laser flash photolysis of suitable photochemical precursors, but all of the studies to date have focused on aryloxenium ions having closed-shell singlet ground state configurations. To study alternative spin configurations, we synthesized a photoprecursor to the m-dimethylamino phenyloxenium ion, which is predicted by both density functional theory and MRMP2 computations to have a triplet ground state electronic configuration. A combination of femtosecond and nanosecond transient absorption spectroscopy, nanosecond time-resolved Resonance Raman spectroscopy (ns-TR(3)), cryogenic matrix EPR spectroscopy, computational analysis, and photoproduct studies allowed us to trace essentially the complete arc of the photophysics and photochemistry of this photoprecursor and permitted a first look at a triplet oxenium ion. Ultraviolet photoexcitation of this precursor populates higher singlet excited states, which after internal conversion to S1 over 800 fs are followed by bond heterolysis in ?1 ps, generating a hot closed-shell singlet oxenium ion that undergoes vibrational cooling in ?50 ps followed by intersystem crossing in ?300 ps to generate the triplet ground state oxenium ion. In contrast to the rapid trapping of singlet phenyloxenium ions by nucleophiles seen in prior studies, the triplet oxenium ion reacts via sequential H atom abstractions on the microsecond time domain to ultimately yield the reduced m-dimethylaminophenol as the only detectable stable photoproduct. Band assignments were made by comparisons to computed spectra of candidate intermediates and comparisons to related known species. The triplet oxenium ion was also detected in the ns-TR(3) experiments, permitting a more clear assignment and identifying the triplet state as the ?,?* triplet configuration. The triplet ground state of this ion was further supported by photolysis of the photoprecursor in an ethanol glass at ?4 K and observing a triplet species by cryogenic EPR spectroscopy. PMID:26198984
Xia, Shu-Hua; Xie, Bin-Bin; Fang, Qiu; Cui, Ganglong; Thiel, Walter
2015-04-21
Excited-state intramolecular proton transfer (ESIPT) between two highly electronegative atoms, for example, oxygen and nitrogen, has been intensely studied experimentally and computationally, whereas there has been much less theoretical work on ESIPT to other atoms such as carbon. We have employed CASSCF, MS-CASPT2, RI-ADC(2), OM2/MRCI, DFT, and TDDFT methods to study the mechanistic photochemistry of 2-phenylphenol, for which such an ESIPT has been observed experimentally. According to static electronic structure calculations, irradiation of 2-phenylphenol populates the bright S1 state, which has a rather flat potential in the Franck-Condon region (with a shallow enol minimum at the CASSCF level) and may undergo an essentially barrierless ESIPT to the more stable S1 keto species. There are two S1/S0 conical intersections that mediate relaxation to the ground state, one in the enol region and one in the keto region, with the latter one substantially lower in energy. After S1 ? S0 internal conversion, the transient keto species can return back to the S0 enol structure via reverse ground-state hydrogen transfer in a facile tautomerization. This mechanistic scenario is verified by OM2/MRCI-based fewest-switches surface-hopping simulations that provide detailed dynamic information. In these trajectories, ESIPT is complete within 118 fs; the corresponding S1 excited-state lifetime is computed to be 373 fs in vacuum. Most of the trajectories decay to the ground state via the S1/S0 conical intersection in the keto region (67%), and the remaining ones via the enol region (33%). The combination of static electronic structure computations and nonadiabatic dynamics simulations is expected to be generally useful for understanding the mechanistic photophysics and photochemistry of molecules with intramolecular hydrogen bonds. PMID:25711992
Cooling atom-cavity systems into entangled states
Busch, J.; De, S.; Spiller, T. P.; Beige, A.; Ivanov, S. S.; Torosov, B. T.
2011-08-15
Generating entanglement by simply cooling a system into a stationary state which is highly entangled has many advantages. Schemes based on this idea are robust against parameter fluctuations, tolerate relatively large spontaneous decay rates, and achieve high fidelities independent of their initial state. A possible implementation of this idea in atom-cavity systems has recently been proposed by Kastoryano et al., [Kastoryano et al., Phys. Rev. Lett. 106, 090502 (2011).]. Here we propose an improved entanglement cooling scheme for two atoms inside an optical cavity which achieves higher fidelities for comparable single-atom cooperativity parameters C. For example, we predict fidelities above 90% even for C as low as 20 without having to detect photons.
Area law in one dimension: Degenerate ground states and Renyi entanglement entropy
Yichen Huang
2015-01-07
An area law is proved for the Renyi entanglement entropy of possibly degenerate ground states in one-dimensional gapped quantum systems. Suppose in a chain of $n$ spins the ground states of a local Hamiltonian with energy gap $\\epsilon$ are constant-fold degenerate. Then, the Renyi entanglement entropy $R_\\alpha(0<\\alpha<1)$ of any ground state across any cut is upper bounded by $\\tilde O(\\alpha^{-3}/\\epsilon)$, and any ground state can be well approximated by a matrix product state of subpolynomial bond dimension $2^{\\tilde O(\\epsilon^{-1/4}\\log^{3/4}n)}$.
Problems with interpretation of $^{10}$He ground state
L. V. Grigorenko; M. V. Zhukov
2008-02-05
The continuum of $^{10}$He nucleus is studied theoretically in a three-body $^{8}$He+$n$+$n$ model basing on the recent information concerning $^9$He spectrum [Golovkov, \\textit{et al.}, Phys. Rev. C \\textbf{76}, 021605(R) (2007)]. The $^{10}$He ground state (g.s.) candidate with structure $[p_{1/2}]^2$ for new g.s. energy of $^9$He is predicted to be at about $2.0-2.3$ MeV. The peak in the cross section associated with this state may be shifted to a lower energy (e.g. $\\sim 1.2$ MeV) when $^{10}$He is populated in reactions with $^{11}$Li due to peculiar reaction mechanism. Formation of the low-energy ($EHe in the case of considerable attraction (e.g. $aHe channel, which properties are still quite uncertain. This result either questions the existing experimental low-energy spectrum of $^{10}$He or place a limit on the scattering length in $^9$He channel, which contradicts existing data.
Correction method for obtaining the variationally best ground-state pair density
Higuchi, Masahiko; Higuchi, Katsuhiko
2011-10-15
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.
Nonlinear ground-state pump-probe spectroscopy in an ultracold rubidium system
NASA Astrophysics Data System (ADS)
Mills, Arthur K.; Elliott, D. S.
2012-12-01
We present results of our experimental investigations of nonlinear ground-state pump-probe spectroscopy in ultracold 85Rb collected in a magneto-optical trap. These measurements represent an extension of a similar pump-probe spectroscopy in a two-level atomic system when strongly driven by a near-resonant pump beam. In the present three-level system, coherence-induced gain at the probe laser frequency can be observed at specific frequencies within the spectrum. The absorption or gain spectra that we observe resemble those of the two-level gain spectra, but different interference processes lead to features that are not present in the two-level case. We describe our measurements of this interaction in this work.
Mott-Insulator States of Ultracold Atoms in Optical Resonators
Larson, Jonas; Damski, Bogdan; Morigi, Giovanna; Lewenstein, Maciej
2008-02-08
We study the low temperature physics of an ultracold atomic gas in the potential formed inside a pumped optical resonator. Here, the height of the cavity potential, and hence the quantum state of the gas, depends not only on the pump parameters, but also on the atomic density through a dynamical ac-Stark shift of the cavity resonance. We derive the Bose-Hubbard model in one dimension and use the strong coupling expansion to determine the parameter regime in which the system is in the Mott-insulator state. We predict the existence of overlapping, competing Mott-insulator states, and bistable behavior in the vicinity of the shifted cavity resonance, controlled by the pump parameters. Outside these parameter regions, the state of the system is in most cases superfluid.
Mott insulator states of ultracold atoms in optical resonators
Jonas Larson; Bogdan Damski; Giovanna Morigi; Maciej Lewenstein
2007-12-18
We study the low temperature physics of an ultracold atomic gas in the potential formed inside a pumped optical resonator. Here, the height of the cavity potential, and hence the quantum state of the gas, depends not only on the pump parameters, but also on the atomic density through a dynamical a.c.-Stark shift of the cavity resonance. We derive the Bose-Hubbard model in one dimension, and use the strong coupling expansion to determine the parameter regime in which the system is in the Mott-insulator state. We predict the existence of overlapping, competing Mott states, and bistable behavior in the vicinity of the shifted cavity resonance, controlled by the pump parameters. Outside these parameter regions, the state of the system is in most cases superfluid.
Combined Film Catalog, 1972, United States Atomic Energy Commission.
ERIC Educational Resources Information Center
Atomic Energy Commission, Washington, DC.
A comprehensive listing of all current United States Atomic Energy Commission (USAEC) films, this catalog describes 232 films in two major film collections. Part One: Education-Information contains 17 subject categories and two series and describes 134 films with indicated understanding levels on each film for use by schools. The categories…
Ground-based optical atomic clocks as a tool to monitor vertical surface motion
NASA Astrophysics Data System (ADS)
Bondarescu, Ruxandra; Schärer, Andreas; Lundgren, Andrew; Hetényi, György; Houlié, Nicolas; Jetzer, Philippe; Bondarescu, Mihai
2015-09-01
According to general relativity, a clock experiencing a shift in the gravitational potential ?U will measure a frequency change given by ?f/f ? ?U/c2. The best clocks are optical clocks. After about 7 hr of integration they reach stabilities of ?f/f ˜ 10-18 and can be used to detect changes in the gravitational potential that correspond to vertical displacements of the centimetre level. At this level of performance, ground-based atomic clock networks emerge as a tool that is complementary to existing technology for monitoring a wide range of geophysical processes by directly measuring changes in the gravitational potential. Vertical changes of the clock's position due to magmatic, post-seismic or tidal deformations can result in measurable variations in the clock tick rate. We illustrate the geopotential change arising due to an inflating magma chamber using the Mogi model and apply it to the Etna volcano. Its effect on an observer on the Earth's surface can be divided into two different terms: one purely due to uplift (free-air gradient) and one due to the redistribution of matter. Thus, with the centimetre-level precision of current clocks it is already possible to monitor volcanoes. The matter redistribution term is estimated to be 3 orders of magnitude smaller than the uplift term. Additionally, clocks can be compared over distances of thousands of kilometres over short periods of time, which improves our ability to monitor periodic effects with long wavelength like the solid Earth tide.
Theoretical studies of the first-row transition metals: Ground state and thermal properties
NASA Astrophysics Data System (ADS)
Prevost, Jean-Paul L.
Theoretical studies of the ground state properties of the first-row transition metals (Sc to Zn) are conducted using the Stuttgart TB-LMTO ESC program. The standard deviation of the calculation precision errors (CPE's) and the magnitude of the systematic calculation errors (SCE's) in the output of the TB-LMTO ESC program are estimated. The ground state lattice parameters, local atomic magnetic moment magnitudes and bulk moduli of the first-row transition metals are calculated. Lattice parameters are found to be within 5% to 10% of experimental values, and magnetic moment magnitudes are found to be within 10% to 20% of experimental values. Bulk moduli are found to be within 60% of experimental values. Lattice parameter and magnetic moment magnitude calculations are most accurate when the non-local exchange-correlation functional of Hu and Langreth is used. Bulk modulus calculations are most accurate when conducted using the exchange-correlation functional of Perdew and Yue. The TB-LMTO ESC program is also used to study the volume-controlled low-moment to high-moment (LM-HM) transition of the first-row transition metals (Sc to Ni) when they are constrained to take the FCC crystal structure. A LM-HM transition is predicted to occur in all FCC first-row transition metals if their lattice parameter is sufficiently increased. FCC Fe is found to occupy a unique position in the first-row transition metal series, as its LM-HM transition occurs when its lattice parameter is less than 2.5% larger than its ground state value. The LM-HM transition of the other FCC first-row transition metals occur when their lattice parameters are much larger or much smaller than their ground state values. It is argued that when the lattice parameters of the FCC first-row transition metals are too small, the energy bands of their valence electrons are too wide to allow magnetic moments to form within these metals. A method is proposed for calculating the Helmholtz' free energy of non-magnetic, bulk, crystalline solids consisting of a single chemical species. The method assumes only that an inter-atomic interaction potential can be derived from the minimum total energy versus lattice parameter curve of a solid using results published by Chen, Chen and Wei, and that this potential can accurately reproduce the energy increase that occurs when the atomic nuclei of the solid move away from their equilibrium positions as they undergo small amplitude thermal oscillations. The method is entirely theoretical as the minimum total energy versus lattice parameter curve of a solid can be calculated entirely from first principles using an ESC program. Within the method, the atomic nuclei of a solid are treated in a quasi-harmonic approximation, either as independent harmonic oscillators, or as coupled harmonic oscillators. The thermal expansion of metallic Cu is studied using the proposed method for calculating the Helmholtz' free energy of solids in conjunction with the TB-LMTO ESC program. The lattice parameter versus temperature curve of metallic Cu can be accurately calculated using the method, but its accuracy is sensitive to the functional form of the calculated minimum total energy versus lattice parameter curve of FCC Cu and to the range of the inter-atomic interaction potential. The results of these calculations suggest that the range of the inter-atomic interaction potential extends only to first nearest neighbour atomic nuclei in the metallic Cu solid. These results also suggest that the curvature of the minimum total energy versus lattice parameter curve of FCC Cu is most accurate when the curve is calculated using the exchange-correlation functional of Perdew and Yue even though the ground state lattice parameter of metallic Cu is most accurately predicted using the exchange-correlation functional of Hu and Langreth. However, it may be that imposing a short range to the inter-atomic interaction potential and that using the minimum total energy versus lattice parameter curve obtained with the exchange-correlation functional of Perdew and Yue simply bet
Probing ground and low-lying excited states for HIO{sub 2} isomers
Souza, Gabriel L. C. de; Brown, Alex
2014-12-21
We present a computational study on HIO{sub 2} molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10{sup ?3})
Electro-optic control of atom-light interactions using Rydberg dark-state polaritons
M. G. Bason; A. K. Mohapatra; K. J. Weatherill; C. S. Adams
2007-09-10
We demonstrate a multiphoton Rydberg dark resonance where a Lambda-system is coupled to a Rydberg state. This N-type level scheme combines the ability to slow and store light pulses associated with long lived ground state superpositions, with the strongly interacting character of Rydberg states. For the nd_{5/2} Rydberg state in 87Rb (with n=26 or 44) and a beam size of 1 mm we observe a resonance linewidth of less than 100 kHz in a room temperature atomic ensemble limited by transit-time broadening. The resonance is switchable with an electric field of order 1 V/cm. We show that, even when photons with different wavevectors are involved, the resonance can be Doppler-free. Applications in electro-optic switching and photonic phase gates are discussed.
Robustness of fractional quantum Hall states with dipolar atoms in artificial gauge fields
Grass, T.; Baranov, M. A.; Lewenstein, M.
2011-10-15
The robustness of fractional quantum Hall states is measured as the energy gap separating the Laughlin ground state from excitations. Using thermodynamic approximations for the correlation functions of the Laughlin state and the quasihole state, we evaluate the gap in a two-dimensional system of dipolar atoms exposed to an artificial gauge field. For Abelian fields, our results agree well with the results of exact diagonalization for small systems but indicate that the large value of the gap predicted [Phys. Rev. Lett. 94, 070404 (2005)] was overestimated. However, we are able to show that the small gap found in the Abelian scenario dramatically increases if we turn to non-Abelian fields squeezing the Landau levels.
Existence and concentration of ground states for Schrödinger-Poisson equations with critical growth
NASA Astrophysics Data System (ADS)
He, Xiaoming; Zou, Wenming
2012-02-01
In this paper, we study the existence and concentration behavior of ground state solutions for a class of Schrödinger-Poisson equation with a parameter ? > 0. Under some suitable conditions on the nonlinearity f and the potential V, we prove that for ? small, the equation has a ground state solution concentrating around global minimum of the potential V in the semi-classical limit. Also, the exponential decay of the ground state solutions is studied.
Perry, Rebecca W; Holmes-Cerfon, Miranda C; Brenner, Michael P; Manoharan, Vinothan N
2015-06-01
We study experimentally what is arguably the simplest yet nontrivial colloidal system: two-dimensional clusters of six spherical particles bound by depletion interactions. These clusters have multiple, degenerate ground states whose equilibrium distribution is determined by entropic factors, principally the symmetry. We observe the equilibrium rearrangements between ground states as well as all of the low-lying excited states. In contrast to the ground states, the excited states have soft modes and low symmetry, and their occupation probabilities depend on the size of the configuration space reached through internal degrees of freedom, as well as a single "sticky parameter" encapsulating the depth and curvature of the potential. Using a geometrical model that accounts for the entropy of the soft modes and the diffusion rates along them, we accurately reproduce the measured rearrangement rates. The success of this model, which requires no fitting parameters or measurements of the potential, shows that the free-energy landscape of colloidal systems and the dynamics it governs can be understood geometrically. PMID:26196649
NASA Astrophysics Data System (ADS)
Perry, Rebecca W.; Holmes-Cerfon, Miranda C.; Brenner, Michael P.; Manoharan, Vinothan N.
2015-06-01
We study experimentally what is arguably the simplest yet nontrivial colloidal system: two-dimensional clusters of six spherical particles bound by depletion interactions. These clusters have multiple, degenerate ground states whose equilibrium distribution is determined by entropic factors, principally the symmetry. We observe the equilibrium rearrangements between ground states as well as all of the low-lying excited states. In contrast to the ground states, the excited states have soft modes and low symmetry, and their occupation probabilities depend on the size of the configuration space reached through internal degrees of freedom, as well as a single "sticky parameter" encapsulating the depth and curvature of the potential. Using a geometrical model that accounts for the entropy of the soft modes and the diffusion rates along them, we accurately reproduce the measured rearrangement rates. The success of this model, which requires no fitting parameters or measurements of the potential, shows that the free-energy landscape of colloidal systems and the dynamics it governs can be understood geometrically.
Sideband Cooling while Preserving Coherences in the Nuclear Spin State in Group-II-like Atoms
Reichenbach, Iris; Deutsch, Ivan H.
2007-09-21
We propose a method for laser cooling group-II-like atoms without changing the quantum state of their nuclear spins, thus preserving coherences that are usually destroyed by optical pumping in the cooling process. As group-II-like atoms have a {sup 1}S{sub 0} closed-shell ground state, nuclear spin and electronic angular momentum are decoupled, allowing for their independent manipulation. The hyperfine interaction that couples these degrees of freedom in excited states can be suppressed through the application of external magnetic fields. Our protocol employs resolved-sideband cooling on the forbidden clock transition, {sup 1}S{sub 0}{yields}{sup 3}P{sub 0}, with quenching via coupling to the rapidly decaying {sup 1}P{sub 1} state, deep in the Paschen-Back regime. This makes it possible to laser cool neutral atomic qubits without destroying the quantum information stored in their nuclear spins, as shown in two examples, {sup 171}Yb and {sup 87}Sr.
Intensity and amplitude correlations in the fluorescence from atoms with interacting Rydberg states
Qing Xu; Klaus Mølmer
2015-08-04
We explore the fluorescence signals from a pair of atoms driven towards Rydberg states on a three-level ladder transition. The dipole--dipole interactions between Rydberg excited atoms significantly distort the dark state and electromagnetically induced transparency behavior observed with independent atoms and, thus, their steady state light emission. We calculate and analyze the temporal correlations between intensities and amplitudes of the signals emitted by the atoms and explain their origin in the atomic Rydberg state interactions.
Quantum teleportation of an arbitrary superposition of atomic Dicke states
Di, TG; Muthukrishnan, A.; Scully, Marlan O.; Zubairy, M. Suhail
2005-01-01
entangle- ment among distant atoms f10,11g. In an application of this idea, Bose et al. f4g show how to teleport an atomic state from one cavity to another by conditional detection of a pho- ton from both cavities. The main advantage of their scheme..., J. L. Sorensen, S. L. Brounstein, C. A. Fuchs, H. J. Kimble, and E. S. Polzik, Science 282, 706 s1998d. f4g S. Bose, P. L. Knight, M. B. Plenio, and V. Vedral, Phys. Rev. Lett. 83, 5158 s1999d. f5g L. Davidovich, N. Zagury, M. Brune, J. M...
NASA Astrophysics Data System (ADS)
Zeng, Hui; Zhao, Jun
2012-07-01
In this paper, the energy, equilibrium geometry, and harmonic frequency of the ground electronic state of PO2 are computed using the B3LYP, B3P86, CCSD(T), and QCISD(T) methods in conjunction with the 6-311++G(3df, 3pd) and cc-pVTZ basis sets. A comparison between the computational results and the experimental values indicates that the B3P86/6-311++G(3df, 3pd) method can give better energy calculation results for the PO2 molecule. It is shown that the ground state of the PO2 molecule has C2? symmetry and its ground electronic state is X2A1. The equilibrium parameters of the structure are RP-O = 0.1465 nm, ?OPO = 134.96°, and the dissociation energy is Ed = 19.218 eV. The bent vibrational frequency ?1 = 386 cm-1, symmetric stretching frequency ?2 = 1095 cm-1, and asymmetric stretching frequency ?3 = 1333 cm-1 are obtained. On the basis of atomic and molecular reaction statics, a reasonable dissociation limit for the ground state of the PO2 molecule is determined. Then the analytic potential energy function of the PO2 molecule is derived using many-body expansion theory. The potential curves correctly reproduce the configurations and the dissociation energy for the PO2 molecule.
Table of experimental nuclear ground state charge radii: An update
Angeli, I.; Marinova, K.P.
2013-01-15
The present table contains experimental root-mean-square (rms) nuclear charge radii R obtained by combined analysis of two types of experimental data: (i) radii changes determined from optical and, to a lesser extent, K{sub ?} 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)
Arsenic in Ground-Water Resources of the United States
Welch, Alan H.; Watkins, Sharon A.; Helsel, Dennis R.; Focazio, Michael J.
2000-01-01
Arsenic is a naturally occurring element in rocks, soils, and the waters in contact with them. Recognized as a toxic element for centuries, arsenic today also is a human health concern because it can contribute to skin, bladder, and other cancers (National Research Council, 1999). Recently, the National Research Council (1999) recommended lowering the current maximum contaminant level (MCL) allowed for arsenic in drinking water of 50 ?g/L (micrograms per liter), citing risks for developing bladder and other cancers. The U.S. Environmental Protection Agency (USEPA) will propose a new, and likely lower, arsenic MCL during 2000 (U.S. Environmental Protection Agency, 2000). This fact sheet provides information on where and to what extent natural concentrations of arsenic in ground water exceed possible new standards. The U.S. Geological Survey (USGS) has collected and analyzed arsenic in potable (drinkable) water from 18,850 wells in 595 counties across the United States during the past two decades. These wells are used for irrigation, industrial purposes, and research, as well as for public and private water supply. Arsenic concentrations in samples from these wells are similar to those found in nearby public supplies (see Focazio and others, 1999). The large number of samples, broad geographic coverage, and consistency of methods produce a more accurate and detailed picture of arsenic concentrations than provided by any previous studies.
Kuang Leman; Zhou Lan
2003-10-01
In this paper, we present a method to generate continuous-variable-type entangled states between photons and atoms in atomic Bose-Einstein condensate (BEC). The proposed method involves an atomic BEC with three internal states, a weak quantized probe laser, and a strong classical coupling laser, which form a three-level {lambda}-shaped BEC system. We consider a situation where the BEC is in electromagnetically induced transparency with the coupling laser being much stronger than the probe laser. In this case, the upper and intermediate levels are unpopulated, so that their adiabatic elimination enables an effective two-mode model involving only the atomic field at the lowest internal level and the quantized probe laser field. Atom-photon quantum entanglement is created through laser-atom and interatomic interactions, and two-photon detuning. We show how to generate atom-photon entangled coherent states and entangled states between photon (atom) coherent states and atom-(photon-) macroscopic quantum superposition (MQS) states, and between photon-MQS and atom-MQS states.
Ground State Valency and Spin Configuration of the Ni Ions in Nickelates
Petit, Leon; Egami, Takeshi; Stocks, George Malcolm; Temmerman, Walter M; Szotek, Zdzislawa
2006-01-01
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.
Antiferromagnetic Order as the Competing Ground State in electron-doped high-Tc superconductors
NASA Astrophysics Data System (ADS)
Dai, Pengcheng
2004-03-01
Superconductivity in the high-transition-temperature (high-T_c) copper oxides competes with other possible ground states. The physical explanation for superconductivity can be constrained by determining the nature of the closest competing ground state, and establishing if that state is universal among all high-Tc materials. Antiferromagnetism has been theoretically predicted to be the competing ground state. A competing ground state is revealed when superconductivity is destroyed by the application of a magnetic field, and antiferromagnetism has been observed in hole-doped materials under the influence of modest fields. Here we report the results of transport and neutron-scattering experiments on several electron-doped high-Tc superconductors. The applied field reveals a static, commensurate, anomalously conducting long-range order antiferromagnetic state. This and previous experiments on the hole-doped materials therefore establishes antiferromagnetic order as the competing ground state in high-Tc copper oxides materials, irrespective of electron or hole-doping.
Atomic homodyne detection of continuous-variable entangled twin-atom states.
Gross, C; Strobel, H; Nicklas, E; Zibold, T; Bar-Gill, N; Kurizki, G; Oberthaler, M K
2011-12-01
Historically, the completeness of quantum theory has been questioned using the concept of bipartite continuous-variable entanglement. The non-classical correlations (entanglement) between the two subsystems imply that the observables of one subsystem are determined by the measurement choice on the other, regardless of the distance between the subsystems. Nowadays, continuous-variable entanglement is regarded as an essential resource, allowing for quantum enhanced measurement resolution, the realization of quantum teleportation and quantum memories, or the demonstration of the Einstein-Podolsky-Rosen paradox. These applications rely on techniques to manipulate and detect coherences of quantum fields, the quadratures. Whereas in optics coherent homodyne detection of quadratures is a standard technique, for massive particles a corresponding method was missing. Here we report the realization of an atomic analogue to homodyne detection for the measurement of matter-wave quadratures. The application of this technique to a quantum state produced by spin-changing collisions in a Bose-Einstein condensate reveals continuous-variable entanglement, as well as the twin-atom character of the state. Our results provide a rare example of continuous-variable entanglement of massive particles. The direct detection of atomic quadratures has applications not only in experimental quantum atom optics, but also for the measurement of fields in many-body systems of massive particles. PMID:22139418
Ground Water Quality Protection. State and Local Strategies.
ERIC Educational Resources Information Center
National Academy of Sciences - National Research Council, Washington, DC. Commission on Physical Sciences, Mathematics, and Resources.
Using regional case studies, this document examines representative programs for dealing with ground water contamination. Section one describes the ground water protection strategy of the U.S. Environmental Protection Agency (EPA); (2) discusses the limited data available for determining the extent of contamination; (3) provides a listing of the…
A ground state depleted laser in neodymium doped yttrium orthosilicate
Beach, R.; Albrecht, G.; Solarz, R.; Krupke, W.; Comaskey, B.; Mitchell, S.; Brandle, C.; Berkstresser, G.
1990-01-16
A ground state depleted (GSD){sup 1,2} laser has been demonstrated in the form of a Q-switched oscillator operating at 912 nm. Using Nd{sup 3+} as the active ion and Y{sub 2}SiO{sub 5} as the host material, the laser transition is from the lowest lying stark level of the Nd{sup 3t}F{sub 3/2} level to a stark level 355 cm{sup {minus}1} above the lowest lying one in the {sup 4}I{sub 9/2} manifold. The necessity of depleting the ground {sup 4}I{sub 9/2} manifold is evident for this level scheme as transparency requires a 10% inversion. To achieve the high excitation levels required for the efficient operation of this laser, bleach wave pumping using an alexandrite laser at 745 nm has been employed. The existence of a large absorption feature at 810 nm also allows for the possibility of AlGaAs laser diode pumping. Using KNbO{sub 3}, noncritical phase matching is possible at 140{degree}C using d{sub 32} and has been demonstrated. The results of Q-switched laser performance and harmonic generation in KNbO{sub 3} will be presented. Orthosilicate can be grown in large boules of excellent optical quality using a Czochralski technique. Because of the relatively small 912 nm emission cross section of 2-3 {times} 10{sup {minus}20} cm{sup 2} (orientation dependent) fluences of 10-20 J/cm{sup 2} must be circulated in the laser cavity for the efficient extraction of stored energy. This necessitates very aggressive laser damage thresholds. Results from the Reptile laser damage facility at Lawrence Livermore National Laboratory (LLNL) will be presented showing Y{sub 2}SiO{sub 5} bulk and AR sol-gel coated surface damage thresholds of greater than 40 J/cm{sup 2} for 10 nsec, 10 Hz, 1.06 {mu} pulses. 16 refs., 18 figs., 6 tabs.
Pair supersolid with atom-pair hopping on the state-dependent triangular lattice
NASA Astrophysics Data System (ADS)
Zhang, Wanzhou; Yin, Ruoxi; Wang, Yancheng
2013-11-01
We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of large-scale quantum Monte Carlo simulations, the ground-state phase diagram is studied. We find a first-order transition between the atomic superfluid phase and the pair superfluid phase when the ratio of the atomic hopping and the atom-pair hopping is adapted. The first-order transition remains unchanged under various conditions. We then focus on the interplay among the atom-pair hopping, the on-site repulsion, and the nearest-neighbor repulsion. With on-site repulsion present, we observe first-order transitions between the Mott insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1, and 4/3 filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasihardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. Without on-site repulsion, the transitions between the pair supersolid and the atom superfluid or pair superfluid are first order, except for the particle-hole symmetric point. With weak on-site repulsion and atom hopping turning on, the transition between the pair supersolid and pair superfluid phase becomes continuous. The transition between solid and pair supersolid is three-dimensional XY university, with dynamical exponent z=1 and correlation exponent ?=0.67155. The thermal melting of pair supersolid belongs to the two-dimensional Ising university. We check both energetic and mechanical balance of pair supersolid phase. Lowering the three-body constraint, no pair supersolid is found due to the absence of degeneracy of pair solids in classical limits. We describe the experimental realization of pair tunneling on state dependent lattice.
XUV frequency-comb metrology on the ground state of helium
Kandula, Dominik Z.; Gohle, Christoph; Pinkert, Tjeerd J.; Ubachs, Wim; Eikema, Kjeld S. E.
2011-12-15
The operation of a frequency comb at extreme ultraviolet (xuv) wavelengths based on pairwise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency-comb laser in the near-infrared range is reported. It is experimentally demonstrated that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p {sup 1} P{sub 1} states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited-state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium atom as a precision phase ruler, yields an estimated timing jitter between the two upconverted-comb laser pulses of 50 attoseconds, which is equivalent to a phase jitter of 0.38 (6) cycles in the xuv at 51 nm. This sets a quantitative figure of merit for the operation of the xuv comb and indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5 740 806 993 (10) and 5 814 248 672 (6) MHz for excitation of the 1s4p and 1s5p {sup 1} P{sub 1} states, respectively. This constitutes an important frequency measurement in the xuv, attaining high accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold-improved {sup 4}He ionization energy of 5 945 204 212 (6) MHz is derived. Also, a new value for the {sup 4}He ground-state Lamb shift is found of 41 247 (6) MHz. This experimental value is in agreement with recent theoretical calculations up to order m{alpha}{sup 6} and m{sup 2}/M{alpha}{sup 5}, but with a six-times-higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.
NASA Astrophysics Data System (ADS)
Choi, Jungu; Toh, George; Elliott, Daniel; Elliott's Lab Team
2015-05-01
We discuss initial work towards a measurement of the anapole moment of 133 Cesium from a parity nonconserving (PNC) interaction between the hyperfine ground states. The result of the previous measurement of this anapole moment by the Boulder group, carried out on the 6S/2 --> 7S/2 transition, was much larger than expected, and is at odds with various measurements of scattering cross sections. In an effort to address this deviation, we propose to observe the PNC effect on the hyperfine ground state 6S/2 F = 3 --> 6S/ 2 F = 4 transition by exciting the microwave and two-photon Raman transitions, and observing the interference between these interactions. The benefits of this proposed measurement include the well-known microwave transition frequency (atomic clock frequency), far less sensitivity to the stray field effects, and a high excitation rate by the Raman transition.
Sturmian expansions for two-electron atomic systems: Singly and doubly excited states
Frapiccini, A. L.; Randazzo, J. M.; Colavecchia, F. D.; Gasaneo, G.
2010-10-15
We present a configuration interaction (CI) method based on the Sturmian expansion for bound states of a two-electron atomic system. These Sturmian functions are solutions of one-electron quantum mechanical problems, where the eigenvalue is the magnitude of a short-range potential. Also, they fulfill the long-range boundary conditions of Coulomb potentials. We choose to expand the Sturmians of the CI basis using L{sup 2} Laguerre-type functions. We compute ground and single-excited states energies for He and H{sup -}. Moreover, we are able to obtain energies and widths of double excited states of He, using a Sturmian basis with outgoing boundary conditions. In all cases, our ansatz outperforms other CI calculations, for similar basis size.
Fault-tolerant Implementations of the Atomic-state Communication Model in Weaker Networks ?
Johnen, Colette
Fault-tolerant Implementations of the Atomic-state Communication Model in Weaker Networks ? Colette that are either regular, atomic, or safe we arrive at six dierent network models that use locally shared registers. For example, the atomic-state model has atomic registers located at the nodes of the network. The other models
Steady-state superradiance with alkaline-earth-metal atoms
Meiser, D.; Holland, M. J.
2010-03-15
Alkaline-earth-metal-like atoms with ultranarrow transitions open the door to a new regime of cavity quantum electrodynamics. That regime is characterized by a critical photon number that is many orders of magnitude smaller than what can be achieved in conventional systems. We show that it is possible to achieve superradiance in steady state with such systems. We discuss the basic underlying mechanisms as well as the key experimental requirements.
Kobe, Sigismund
Finding Ground States of Sherrington-Kirkpatrick Spin Glasses with Hierarchical BOA and Genetic- erarchical Bayesian optimization algorithm (hBOA) to reli- ably identify ground states of SK instances. Performance of hBOA is compared to that of the genetic algorithm with two common crossover operators
Chowdhury, Arindam
Ground and Excited State Intramolecular Proton Transfer in Salicylic Acid: an Ab Initio Electronic, India ReceiVed: April 12, 1999 Energetics of the ground and excited state intramolecular proton transfer at the restricted Hartree-Fock (RHF) and configuration interaction-single excitation (CIS) levels and also using
Some Correlation Functions in Matrix Product Ground States of One-Dimensional Two-State Chains
NASA Astrophysics Data System (ADS)
Shariati, Ahmad; Aghamohammadi, Amir; Fatollahi, Amir H.; Khorrami, Mohammad
2014-04-01
Consider one-dimensional chains with nearest neighbour interactions, for which to each site correspond two independent states (say up and down), and the ground state is a matrix product state. It has been shown [23] that for such systems, the ground states are linear combinations of specific vectors which are essentially direct products of specific numbers of ups and downs, symmetrized in a generalized manner. By a generalized manner, it is meant that the coefficient corresponding to the interchange of states of two sites, in not necessarily plus one or minus one, but a phase which depends on the Hamiltonian and the position of the two sites. Such vectors are characterized by a phase ?, the N-th power of which is one (where N is the number of sites), and an integer. Corresponding to ?, there is another integer M which is the smallest positive integer that ?M is one. Two classes of correlation functions for such systems (basically correlation functions for such vectors) are calculated. The first class consists of correlation functions of tensor products of one-site diagonal observables; the second class consists of correlation functions of tensor products of less than M one-site observables (but not necessarily diagonal).
Observation of Floquet States in a Strongly Driven Artificial Atom
NASA Astrophysics Data System (ADS)
Deng, Chunqing; Orgiazzi, Jean-Luc; Shen, Feiruo; Ashhab, Sahel; Lupascu, Adrian
2015-09-01
We present experiments on the driven dynamics of a two-level superconducting artificial atom. The driving strength reaches 4.78 GHz, significantly exceeding the transition frequency of 2.288 GHz. The observed dynamics is described in terms of quasienergies and quasienergy states, in agreement with Floquet theory. In addition, we observe the role of pulse shaping in the dynamics, as determined by nonadiabatic transitions between Floquet states, and we implement subnanosecond single-qubit operations. These results pave the way to quantum control using strong driving with applications in quantum technologies.
Ionization potential for excited S states of the lithium atom
Puchalski, M.; KePdziera, D.; Pachucki, K.
2010-12-15
Nonrelativistic, relativistic, quantum electrodynamic, and finite nuclear mass corrections to the energy levels are obtained for the nS{sub 1/2},n=3,...,9 states of the lithium atom. Computational approach is based on the explicitly correlated Hylleraas functions with the analytic integration and recursion relations. Theoretical predictions for the ionization potential of nS{sub 1/2} states and transition energies nS{sub 1/2{yields}}2S{sub 1/2} are compared to known experimental values for {sup 6,7}Li isotopes.
Observation of Floquet states in a strongly driven artificial atom
Deng, Chunqing; Shen, Feiruo; Ashhab, Sahel; Lupascu, Adrian
2015-01-01
We present experiments on the driven dynamics of a two-level superconducting artificial atom. The driving strength reaches 4.78 GHz, significantly exceeding the transition frequency of 2.288 GHz. The observed dynamics is described in terms of quasienergies and quasienergy states, in agreement with Floquet theory. In addition, we observe the role of pulse shaping in the dynamics, as determined by non-adiabatic transitions between Floquet states, and we implement subnanosecond single-qubit operations. These results pave the way to quantum control using strong driving with applications in quantum technologies.
Dark state cooling of atoms by superfluid immersion
A. Griessner; A. J. Daley; S. R. Clark; D. Jaksch; P. Zoller
2006-07-10
We propose and analyse a scheme to cool atoms in an optical lattice to ultra-low temperatures within a Bloch band, and away from commensurate filling. The protocol is inspired by ideas from dark state laser cooling, but replaces electronic states with motional levels, and spontaneous emission of photons by emission of phonons into a Bose-Einstein condensate, in which the lattice is immersed. In our model, achievable temperatures correspond to a small fraction of the Bloch band width, and are much lower than the reservoir temperature.
Observation of Floquet States in a Strongly Driven Artificial Atom.
Deng, Chunqing; Orgiazzi, Jean-Luc; Shen, Feiruo; Ashhab, Sahel; Lupascu, Adrian
2015-09-25
We present experiments on the driven dynamics of a two-level superconducting artificial atom. The driving strength reaches 4.78 GHz, significantly exceeding the transition frequency of 2.288 GHz. The observed dynamics is described in terms of quasienergies and quasienergy states, in agreement with Floquet theory. In addition, we observe the role of pulse shaping in the dynamics, as determined by nonadiabatic transitions between Floquet states, and we implement subnanosecond single-qubit operations. These results pave the way to quantum control using strong driving with applications in quantum technologies. PMID:26451555
Inelastic processes in atomic collisions involving ground state and laser-prepared atoms
NASA Astrophysics Data System (ADS)
Planje, Willem Gilles
1999-11-01
In dit proefschrift worden experimenten beschreven waarbij ionen of atomen met een bepaalde snelheid op een ensemble van doelwitatomen worden gericht. Wanneer twee deeltjes elkaar voldoende genaderd hebben, vindt er wissel- werking plaats waarbij allerlei processen kunnen optreden. Deze processen resulteren in specieke eindproducten. Kennis over de interactie tussen twee botsingspartners wordt verkregen door te bekijken welke eindproducten ontstaan, en in welke mate. Een belangrijke grootheid die van invloed is op mogelijke processen is de onderlinge snelheid van de twee kernen, oftewel de botsingssnelheid. Wanneer de botsingssnelheid voldoende klein is dan kunnen de verschillende reactiemechanismen zowel kwalitatief als kwanti- tatief vaak goed voorspeld worden door het systeem te beschouwen als een kort-stondig molecuul, opgebouwd uit de twee botsende deeltjes. De ver- schillende processen die kunnen optreden worden gekwaliceerd afhankelijk van de vorming van bepaalde eindproducten. Ruwweg de volgende indeling kan gemaakt worden: 1. de interne structuur van de eindproducten zijn identiek aan die van de beginproducten. We spreken dan van een elastische botsing. 2. e en van de deeltjes of beiden worden in een aangeslagen toestand ge- bracht (of ge¨oniseerd). Dit zijn processen waarbij de herschikte elek- tronen zich bij de oorspronkelijke kern bevinden. We spreken dan van excitatie of ionisatie. 3. e en of meerdere elektronen bevinden zich bij de andere kern na de botsing (eventueel in aangeslagen toestand). We spreken dan van elek- tronenoverdracht. In het eerste deel van deze dissertatie worden botsingsexperimenten tussen heliumionen en natriumatomen beschreven waarbij het proces van elek- tronenoverdracht wordt onderzocht. Bij dit mechanisme is het buitenste 117?Samenvatting natriumelektron betrokken. Deze kan relatief gemakkelijk `overspringen' naar het heliumion wanneer deze zich dicht in de buurt van het natrium- atoom bevindt. Het elektron kan hierbij een bepaalde (aangeslagen) toe- stand bezetten. Wij meten de bezetting van de heliumtoestanden die onder uitzending van XUV licht ( ? 58 nm) vervallen naar de heliumgrondtoe- stand. Door de lichtintensiteit te meten onderzoeken we de mate van elek- tronenoverdracht naar een selecte groep van singlet helium`eind'toestanden, namelijk He(1s2p), He(1s3s), He(1s3p) en He(1s3d). In een reactie- vergelijking ziet het mechanisme er als volgt uit: He + (1s) + ( Na(3s) Na(3p) e- -! He + Na + -! He(1s 2 ) +h(58 nm) + Na + Het experiment kent een extra dimensie door het feit dat het, in beginsel bol- symmetrische, natriumatoom een bepaalde ruimtelijk uitlijning kan worden meegegeven. Met behulp van laserlicht van een specieke frequentie en po- larisatie, wordt het buitenste natriumelektron in een aangeslagen p toestand gebracht. Het aanslaan naar deze toestand heeft als gevolg dat het valentie- elektron zich op grotere afstand van zijn kern bevindt dan voorheen. Daar- naast kan, afhankelijk van de gebruikte laserpolarisatie, het buitenste elek- tron zich nu rond de natriumkern bewegen volgens een bepaalde anisotrope verdeling, de bolsymmetrie is doorbroken. De eecten van de excitatie en ruimtelijk verdeling van dit natriumelektron op het proces van elektronen- overdracht zijn onderzocht voor botsingsenergie¨en vari¨erend van 0.5 keV tot 6.0 keV. De metingen laten zien dat het eect van laserexcitatie een bezettingstoe- name van de beschouwde singlet heliumtoestanden betekent, ongeacht de uitlijning van het natrium 3p elektron. Dit is simpelweg te begrijpen uit het feit dat het 3p natrium elektron minder sterk gebonden is en elektro- nenoverdracht makkelijker gaat. Daarnaast is de uitlijning van het aanges- lagen elektron van invloed op de elektronenoverdracht. De resultaten zijn vergeleken met berekeningen van S.E. Nielsen en T.H. Rod [13], die de elek- tronoverdracht beschrijven in een model waarbij het betrokken elektron zich beweegt in bepaalde eectieve potentiaalvelden. De goede overeenkomsten van onze metingen met de berekeningen rechtvaardigen de theoretische be- naderin
J. C. Berengut; V. A. Dzuba; V. V. Flambaum; S. G. Porsev
2009-04-16
The 7.6 eV electromagnetic transition between the nearly degenerate ground state and first excited state in the Th-229 nucleus may be very sensitive to potential changes in the fine-structure constant, $\\alpha = e^2/\\hbar c$. However, the sensitivity is not known, and nuclear calculations are currently unable to determine it. We propose measurements of the differences of atomic transition frequencies between thorium atoms (or ions) with the nucleus in the ground state and in the first excited (isomeric) state. This will enable extraction of the change in nuclear charge radius and electric quadrupole moment between the isomers, and hence the $\\alpha$-dependence of the isomeric transition frequency with reasonable accuracy.
Ground-state phases of a rung-alternated spin-1/2 Heisenberg ladder
NASA Astrophysics Data System (ADS)
Amiri, F.; Sun, G.; Mikeska, H.-J.; Vekua, T.
2015-11-01
The ground-state phase diagram of a Heisenberg spin-1/2 system on a two-leg ladder with rung alternation is studied by combining analytical approaches with numerical simulations. For the case of ferromagnetic leg exchanges a unique ferrimagnetic ground state emerges, whereas for the case of antiferromagnetic leg exchanges several different ground states are stabilized depending on the ratio between exchanges along legs and rungs. For the more general case of a honeycomb-ladder model for the case of ferromagnetic leg exchanges besides the usual rung-singlet and saturated ferromagnetic states we obtain a ferrimagnetic Luttinger liquid phase with both linear and quadratic low-energy dispersions and ground-state magnetization continuously changing with system parameters. For the case of antiferromagnetic exchanges along legs, different dimerized states including states with additional topological order are suggested to be realized.
Ground-State Cooling of a Trapped Ion Using Long-Wavelength Radiation
NASA Astrophysics Data System (ADS)
Weidt, S.; Randall, J.; Webster, S. C.; Standing, E. D.; Rodriguez, A.; Webb, A. E.; Lekitsch, B.; Hensinger, W. K.
2015-07-01
We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of n ¯=0.13 (4 ) after sideband cooling, corresponding to a ground-state occupation probability of 88(7)%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the |n =0 ? and |n =1 ? Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system.
Ground-State Cooling of a Trapped Ion Using Long-Wavelength Radiation.
Weidt, S; Randall, J; Webster, S C; Standing, E D; Rodriguez, A; Webb, A E; Lekitsch, B; Hensinger, W K
2015-07-01
We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of n[over ¯]=0.13(4) after sideband cooling, corresponding to a ground-state occupation probability of 88(7)%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the |n=0? and |n=1? Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system. PMID:26182094
Ground-state cooling of a trapped ion using long-wavelength radiation
S. Weidt; J. Randall; S. C. Webster; E. D. Standing; A. Rodriguez; A. E. Webb; B. Lekitsch; W. K. Hensinger
2015-06-04
We demonstrate ground-state cooling of a trapped ion using radio-frequency (RF) radiation. This is a powerful tool for the implementation of quantum operations, where RF or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of $\\overline{n} = 0.13(4)$ after sideband cooling, corresponding to a ground-state occupation probability of 88(7)\\%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the n=0 and n=1 Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost two orders of magnitude compared to our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system.
No-go theorem for ground state cooling given initial system-thermal bath factorization
Wu, Lian-Ao; Segal, Dvira; Brumer, Paul
2013-01-01
Ground-state cooling and pure state preparation of a small object that is embedded in a thermal environment is an important challenge and a highly desirable quantum technology. This paper proves, with two different methods, that a fundamental constraint on the cooling dynamic implies that it is impossible to cool, via a unitary system-bath quantum evolution, a system that is embedded in a thermal environment down to its ground state, if the initial state is a factorized product of system and bath states. The latter is a crucial but artificial assumption included in numerous tools that treat system-bath dynamics, such as master equation approaches and Kraus operator based methods. Adopting these approaches to address ground state and even approximate ground state cooling dynamics should therefore be done with caution, considering the fundamental theorem exposed in this work. PMID:23661066
Multiphoton lasing in atomic potassium: Steady-state and dynamic behavior
Font, J. L.; Fernandez-Soler, J. J.; Vilaseca, R.; Gauthier, Daniel J.
2005-12-15
We show theoretically that it is possible to generate laser light based on two-photon and other high-order multiphoton processes when an atomic beam of optically driven potassium atoms crosses a high-finesse optical cavity. We use a rigorous model that takes into account all the atomic substates involved in the optical interactions and is valid for any drive and lasing field intensities. The polarizations of the drive and lasing fields are assumed to be fixed. Stable and unstable laser emission branches are obtained, which are represented as a function of cavity detuning and are analyzed in terms of the fundamental quantum processes yielding them. Closed-curve laser-emission profiles are obtained for multiphoton lasing based on processes involving more than one lasing photon. Two-photon laser emission branches show relatively long segments of stationary emission, combined in general with some segments of nonstationary emission, or with segments of mixture with three-photon emission processes. Rayleigh and hyper-Rayleigh processes can become simultaneously resonant, entailing in such case a large and fast transfer of population from the atomic initial ground sublevel to other ground sublevels with different z components of the total angular momentum. They could be useful in generating multiphoton correlated field states. In all cases the largest laser emission intensities are obtained from the highest-order processes, rather than the lowest. These results open the way to the understanding of experiments performed in the past years and suggest possibilities for more efficient and varied types of multiphoton laser operation.
Quantum states of hydrogen atom on Pd(1 1 0) surface
NASA Astrophysics Data System (ADS)
Padama, Allan Abraham B.; Nakanishi, Hiroshi; Kasai, Hideaki
2015-12-01
The quantum states of adsorbed hydrogen atom on Pd(1 1 0) surface are investigated in this work. From the calculated potential energy surface (PES) of hydrogen atom on Pd(1 1 0), the wave functions and eigenenergies in the ground and few excited states of protium (H) and deuterium (D) are calculated. Localized wave functions of hydrogen atom exist on pseudo-threefold and long bridge sites of Pd(1 1 0). The short bridge site is a local minimum from the result of PES, however, quantum behavior of hydrogen revealed that its vibration would allow it to hop to other pseudo-threefold site (that crosses the short bridge site) than to stay on the short bridge site. Exchange of ordering of the wave functions between H and D is attributed to the difference in their masses. The calculated eigenenergies are found to be in fair agreement with experimental data based from the identified vibrations of hydrogen with component perpendicular to the surface. The activation barriers measured from the eigenenergies are in better agreement with experimental findings in comparison to the data gathered from PES.
High contrast resonances of the coherent population trapping on sublevels of the ground atomic term
Sahin, Ersoy; Birlikseven, Cengiz; Özen, Gönül; Izmailov, Azad Ch
2012-01-01
We have detected and analyzed narrow, high contrast coherent population trapping resonances, which appear in transmission of the probe monochromatic light beam under action of the counterpropagating two-frequency laser radiation, on example of the nonclosed three level {\\Lambda}-system formed by spectral components of the Doppler broadened D2 line of cesium atoms (in the cell with the rarefied Cs vapor). These nontrivial resonances are determined directly by the trapped atomic population on the definite lower level of the {\\Lambda}-system and may be used in atomic frequency standards, sensitive magnetometers and in ultrahigh resolution laser spectroscopy of atoms and molecules.
Striped Ferronematic ground states in a spin-orbit coupled spin-1 Bose gas
NASA Astrophysics Data System (ADS)
Natu, Stefan; Li, Xiaopeng; Cole, William
2015-03-01
Motivated by recent experiments on spin-orbit coupled quantum gases, and the recent cooling to degeneracy of large spin atoms, we explore the ground state phase diagram of a spin-orbit coupled spin-1 Bose gas. A key new feature of large spin systems is the appearance of liquid crystalline order such as nematic or more exotic platonic solid order, which has no analog in solid state. Here we explore the interplay between spin order, translational symmetry breaking induced by spin-orbit coupling and these liquid crystalline order parameters in the experimentally relevant spin-1 system, finding a rich phase diagram. For repulsive spin-dependent interaction, we find a transition from a uniaxial ferronematic phase with XY spiral spin order but uniform total density to a biaxial ferronematic phase with stripes in the total density. As a function of the quadratic Zeeman shift (q), for attractive spin dependent interactions, we find a transition from a ferromagnetic stripe phase which breaks translational symmetry in real space to a uniform ferromagnet for q>0 and a uniform nematic phase for q<0. We discuss the implications of our predictions to ongoing experiments on spin-orbit coupled large spin quantum gases.
NASA Astrophysics Data System (ADS)
Pink, R. H.; Dubey, Archan; Badu, S. R.; Scheicher, R. H.; Chow, Lee; Das, T. P.
2011-03-01
As part of a test of the accuracy of the variational methods (VHFMBPT) and (VDFT) for energy and wave-function dependent properties in molecular and solid state systems, the nuclear quadrupole interactions in the ground state of boron and aluminum atoms are being studied by these methods. Results for the electric field gradients will be presented for these atoms and compared with experiment , and with results , of the highly accurate LCMBPT procedure for the atoms. Conclusions about the factors governing the accuracies of the variational methods will be presented. J.S.M. Harvey, L. Evans, and H. Lew, Can. J. Phys. 50, 1719 (1972)
A new quantum gas apparatus for ultracold mixtures of K and Cs and KCs ground-state molecules
Gröbner, Michael; Meinert, Florian; Lauber, Katharina; Kirilov, Emil; Nägerl, Hanns-Christoph
2015-01-01
We present a new quantum gas apparatus for ultracold mixtures of K and Cs atoms and ultracold samples of KCs ground-state molecules. We demonstrate the apparatus' capabilities by producing Bose-Einstein condensates (BEC) of 39K and 133Cs in a manner that will eventually allow sequential condensation within one experimental cycle, precise sample overlap, and magnetic association of atoms into KCs molecules. The condensates are created independently without relying on sympathetic cooling. Our approach is universal and applicable to other species combinations when the two species show dramatically different behavior in terms of loss mechanisms and post laser cooling temperatures, i.e. species combinations that make parallel generation of quantum degenerate samples challenging. We give an outlook over the next experiments involving e.g. sample mixing, molecule formation, and transport into a science chamber for high-resolution spatial imaging of novel quantum-many body phases based on K-Cs.
Cross, J.B. ); Koontz, S.L. . Lyndon B. Johnson Space Center); Lan, E.H. )
1991-01-01
The effects of atomic oxygen on boron nitride, silicon nitride, solar cell interconnects used on the Intelsat 6 satellite, organic polymers, and MoS{sub 2} and WS{sub 2} dry lubricant have been studied in low Earth orbit (LEO) flight experiments and in our ground-based simulation facility at Los Alamos National Laboratory. Both the in-flight and ground-based experiments employed in situ electrical resistance measurements to detect penetration of atomic oxygen through materials and ESCA analysis to measure chemical composition changes. In the presence of atomic oxygen, silver oxidizes to form silver oxide, which has a much higher electrical resistance than pure silver. Permeation of atomic oxygen through BN overcoated on thin silver was observed. No permeation of atomic oxygen through Si{sub 3}N{sub 4} was observed. Test results on the Intelsat 6 satellite interconnects used on its photovoltaic array indicate that more than 60--80% of the original thickness of silver should remain after completion of the proposed Space Shuttle rescue/reboost mission. Gas phase reaction products produced by the interaction of high kinetic energy atomic oxygen (AO) with Kapton were found to be H{sub 2}, H{sub 2}O, CO, and CO{sub 2} with NO being a possible secondary product. Hydrogen abstraction at high AO kinetic energy is postulated to be the key reaction controlling the erosion rate of Kapton. An Arrhenius-like expression having an activation barrier of 0.4 eV can be fit to the data, which suggests that the rate limiting step in the AO/Kapton reaction mechanism can be overcome by translational energy. Oxidation of MoS{sub 2} and WS{sub 2} dry lubricants in both ground-based and orbital exposures indicated the formation of MoO{sub 3} and WO{sub 3} respectively. A protective oxide layer is formed {approx}30 monolayers thick which has a high initial friction coefficient until the layer is worn off.
Quantum Monte Carlo study of the ground state and low-lying excited states of the scandium dimer
NASA Astrophysics Data System (ADS)
Matxain, Jon M.; Rezabal, Elixabete; Lopez, Xabier; Ugalde, Jesus M.; Gagliardi, Laura
2008-05-01
A large set of electronic states of scandium dimer has been calculated using high-level theoretical methods such as quantum diffusion Monte Carlo (DMC), complete active space perturbation theory as implemented in GAMESS-US, coupled-cluster singles, doubles, and triples, and density functional theory (DFT). The ?u3 and ?u5 states are calculated to be close in energy in all cases, but whereas DFT predicts the ?u5 state to be the ground state by 0.08eV, DMC and CASPT2 calculations predict the ?u3 to be more stable by 0.17 and 0.16eV, respectively. The experimental data available are in agreement with the calculated frequencies and dissociation energies of both states, and therefore we conclude that the correct ground state of scandium dimer is the ?u3 state, which breaks with the assumption of a ?u5 ground state for scandium dimer, believed throughout the past decades.
Bes, D. R.; Civitarese, O.
2010-01-15
Theoretical matrix elements, for the ground-state to ground-state two-neutrino double-{beta}-decay mode (2{nu}{beta}{sup -}{beta}{sup -}gs->gs) of {sup 128,130}Te isotopes, are calculated within a formalism that describes interactions between neutrons in a superfluid phase and protons in a normal phase. The elementary degrees of freedom of the model are proton-pair modes and pairs of protons and quasineutrons. The calculation is basically a parameter-free one, because all relevant parameters are fixed from the phenomenology. A comparison with the available experimental data is presented.
A new window on Strange Quark Matter as the ground state of strongly interacting matter
Vikram Soni; Dipankar Bhattacharya
2003-09-08
If strange quark matter is the true ground state of matter, it must have lower energy than nuclear matter. Simultaneously, two-flavour quark matter must have higher energy than nuclear matter, for otherwise the latter would convert to the former. We show, using an effective chiral lagrangian, that the existence of a new lower energy ground state for two-flavour quark matter, the pion condensate, shrinks the window for strange quark matter to be the ground state of matter and sets new limits on the current strange quark mass.
Bulk-edge correspondence of entanglement spectrum in two-dimensional spin ground states
NASA Astrophysics Data System (ADS)
Santos, Raul A.
2013-01-01
General local spin S ground states, described by a valence bond solid (VBS) on a two-dimensional lattice are studied. The norm of these ground states is mapped to a classical O(3) model on the same lattice. Using this quantum-to-classical mapping, we obtain the partial density matrix ?A associated with a subsystem A of the original ground state. We show that the entanglement spectrum of ?A in a translation invariant lattice is related with the spectrum of a quantum XXX Heisenberg model and all its conserved charges on the boundary of the region A.
Characterization of ground state entanglement by single-qubit operations and excitation energies
Giampaolo, S M; Illuminati, F; Verrucchi, P; Giampaolo, Salvatore M.; Illuminati, Fabrizio; Siena, Silvio De; Verrucchi, Paola
2006-01-01
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.
Ground state properties of superheavy nuclei with Z=117 and Z=119
Ren Zhongzhou; Chen Dinghan; Xu Chang
2006-11-02
We review the current studies on the ground-state properties of superheavy nuclei. It is shown that there is shape coexistence for the ground state of many superheavy nuclei from different models and many superheavy nuclei are deformed. This can lead to the existence of isomers in superheavy region and it plays an important role for the stability of superheavy nuclei. Some new results on Z=117 and Z=119 isotopes are presented. The agreement between theoretical results and experimental data clearly demonstrates the validity of theoretical models for the ground-state properties of superheavy nuclei.
Ground-state energies of the nonlinear sigma model and the Heisenberg spin chains
NASA Technical Reports Server (NTRS)
Zhang, Shoucheng; Schulz, H. J.; Ziman, Timothy
1989-01-01
A theorem on the O(3) nonlinear sigma model with the topological theta term is proved, which states that the ground-state energy at theta = pi is always higher than the ground-state energy at theta = 0, for the same value of the coupling constant g. Provided that the nonlinear sigma model gives the correct description for the Heisenberg spin chains in the large-s limit, this theorem makes a definite prediction relating the ground-state energies of the half-integer and the integer spin chains. The ground-state energies obtained from the exact Bethe ansatz solution for the spin-1/2 chain and the numerical diagonalization on the spin-1, spin-3/2, and spin-2 chains support this prediction.
Brashears, M.L., Jr.
1950-01-01
The United States Geological Survey in cooperation with the Massachusetts Department of Public Works in 1938 began an investigation of the ground-water conditions in Massachusetts. This work is part of a larger cooperative program that includes surface-water investigations, geologic studies, and topographic mapping. The purpose of the ground-water studies is to obtain detailed information concerning the occurrence and availability of ground water throughout the State. The information is used by the Highway Division of the Department of Public Works in connection with design, construction, and maintenance of highways. These studies also provided a basis for the more effective utilization of the ground-water resources of the State. They indicate where additional developments can be made safely or where present use may be excessive. Reports covering the ground-water studies are listed in the appendix.
NASA Astrophysics Data System (ADS)
Prakash, Abhishodh; Wei, Tzu-Chieh
2015-08-01
The program of classifying symmetry-protected topological (SPT) phases in one dimension has been recently completed and has opened the doors to studying closely the properties of systems belonging to these phases. It was recently found that being able to constrain the form of ground states of SPT order based on symmetry properties also makes it possible to explore novel resource states for processing of quantum information. In this paper, we generalize the consideration of Else et al. [Phys. Rev. Lett. 108, 240505 (2012)], 10.1103/PhysRevLett.108.240505, where it was shown that the ground-state form of spin-1 chains protected by Z2×Z2 symmetry supports perfect operation of the identity gate, important also for long-distance transmission of quantum information. We develop a formalism to constrain the ground-state form of SPT phases protected by any arbitrary finite symmetry group and use it to examine examples of ground states of SPT phases protected by various finite groups for similar gate protections. We construct a particular Hamiltonian invariant under A4 symmetry transformation, which is one of the groups that allows protected identity operation, and examine its ground states. We find that there is an extended region where the ground state is the AKLT state, which not only supports the identity gate but also arbitrary single-qubit gates.
NASA Astrophysics Data System (ADS)
Petrosyan, David; Mølmer, Klaus
2013-03-01
We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg excitation of precisely one atom within the atomic ensemble. The quantum Zeno effect offers a lucid interpretation of this result: the Rydberg blocked atoms repetitively scattering photons effectively monitor a randomly excited atom, which therefore remains in the Rydberg state. This system can be used for deterministic creation and, possibly, extraction of Rydberg atoms or ions one at a time. The sympathetic monitoring via decay of ancilla particles may find wider applications for state preparation and probing of interactions in dissipative many-body systems.
Switching between ground and excited states by optical feedback in a quantum dot laser diode
Virte, Martin; Breuer, Stefan; Sciamanna, Marc; Panajotov, Krassimir
2014-09-22
We demonstrate switching between ground state and excited state emission in a quantum-dot laser subject to optical feedback. Even though the solitary laser emits only from the excited state, we can trigger the emission of the ground state by optical feedback. We observe recurrent but incomplete switching between the two emission states by variation of the external cavity length in the sub-micrometer scale. We obtain a good qualitative agreement of experimental results with simulation results obtained by a rate equation that accounts for the variations of the feedback phase.
Optical pumping of metastable NH radicals into the paramagnetic ground state
Meerakker, Sebastiaan Y.T. van de; Mosk, Allard P.; Jongma, Rienk T.; Sartakov, Boris G.; Meijer, Gerard
2003-09-01
We here report on the optical pumping of both {sup 14}NH and {sup 15}NH radicals from the metastable a {sup 1}{delta} state into the X {sup 3}{sigma}{sup -} ground state in a molecular beam experiment. By inducing the hitherto unobserved spin-forbidden A {sup 3}{pi} <- a {sup 1}{delta} transition, followed by spontaneous emission to the X {sup 3}{sigma}{sup -} state, a unidirectional pathway for population transfer from the metastable state into the electronic ground state is obtained. The optical pumping scheme demonstrated here opens up the possibility to accumulate NH radicals in a magnetic or optical trap.
Ground states of stealthy hyperuniform potentials. II. Stacked-slider phases
NASA Astrophysics Data System (ADS)
Zhang, G.; Stillinger, F. H.; Torquato, S.
2015-08-01
Stealthy potentials, a family of long-range isotropic pair potentials, produce infinitely degenerate disordered ground states at high densities and crystalline ground states at low densities in d -dimensional Euclidean space Rd. In the previous paper in this series, we numerically studied the entropically favored ground states in the canonical ensemble in the zero-temperature limit across the first three Euclidean space dimensions. In this paper, we investigate using both numerical and theoretical techniques metastable stacked-slider phases, which are part of the ground-state manifold of stealthy potentials at densities in which crystal ground states are favored entropically. Our numerical results enable us to devise analytical models of this phase in two, three, and higher dimensions. Utilizing this model, we estimated the size of the feasible region in configuration space of the stacked-slider phase, finding it to be smaller than that of crystal structures in the infinite-system-size limit, which is consistent with our recent previous work. In two dimensions, we also determine exact expressions for the pair correlation function and structure factor of the analytical model of stacked-slider phases and analyze the connectedness of the ground-state manifold of stealthy potentials in this density regime. We demonstrate that stacked-slider phases are distinguishable states of matter; they are nonperiodic, statistically anisotropic structures that possess long-range orientational order but have zero shear modulus. We outline some possible future avenues of research to elucidate our understanding of this unusual phase of matter.
NASA Astrophysics Data System (ADS)
B?aziak, Kacper; Panek, Jaros?aw J.; Jezierska, Aneta
2015-07-01
Quinoline derivatives are interesting objects to study internal reorganizations due to the observed excited-state-induced intramolecular proton transfer (ESIPT). Here, we report on computations for selected 12 quinoline derivatives possessing three kinds of intramolecular hydrogen bonds. Density functional theory was employed for the current investigations. The metric and electronic structure simulations were performed for the ground state and first excited singlet and triplet states. The computed potential energy profiles do not show a spontaneous proton transfer in the ground state, whereas excited states exhibit this phenomenon. Atoms in Molecules (AIM) theory was applied to study the nature of hydrogen bonding, whereas Harmonic Oscillator Model of aromaticity index (HOMA) provided data of aromaticity evolution as a derivative of the bridge proton position. The AIM-based topological analysis confirmed the presence of the intramolecular hydrogen bonding. In addition, using the theory, we were able to provide a quantitative illustration of bonding transformation: from covalent to the hydrogen. On the basis of HOMA analysis, we showed that the aromaticity of both rings is dependent on the location of the bridge proton. Further, the computed results were compared with experimental data available. Finally, ESIPT occurrence was compared for the three investigated kinds of hydrogen bridges, and competition between two bridges in one molecule was studied.
Hyperfine structure of the metastable 3 P2 state of alkaline earth atoms as an accurate
Johnson, Walter R.
Hyperfine structure of the metastable 3 P2 state of alkaline earth atoms as an accurate probe and electric hexadecapole moments. Here, using relativistic many-body methods of atomic structure the hyperfine structure of long-lived 3 P2 states of cold divalent atoms may facilitate extracting the so far
NASA Astrophysics Data System (ADS)
Blum, Volker
2006-03-01
First-principles quantum-mechanical (QM) calculations allow to evaluate many interesting properties of a given nano-scale configuration of atoms with high accuracy. However, predicting stable structures or finite-T thermodynamic configurational averages with QM accuracy remains a challenge: even for a binary solid with N atoms per unit cell, 2^N distinct configurations must be evaluated. Such large numbers of calculations can be made affordable by mapping the QM Hamiltonian onto a computationally simpler ``coarse-grained'' Hamiltonian. The ability to predict ground state structures then depends on the shape of the coarse-grained Hamiltonian, but this shape is not a priori clear. For instance, a few simple assumed generic interactions will allow only a few simple ground states, but any more complex structures will be missed. For the generalized Ising model for binary alloys (cluster expansion), I show how a genetic algorithm^1,2 can identify the leading interactions which characterize a given system. I illustrate the method for the bcc binary alloys of Nb, Ta, Mo, W. A rich spectrum of ground state structures is found, including both well-known and unsuspected complex structures, far beyond what is envisioned from ``usual-suspect'' structure listings or from simple generic interactions. At the same time, order-disorder temperatures are significantly lower than those from simple intuition-based interactions, in agreement with experimental observations for these systems. This work was done at the National Renewable Energy Laboratory, supported by DOE-SC-BES, in collaboration with A. Zunger and G. Hart. ^1G. Hart, V. Blum, M. Walorski and A. Zunger, Nature Materials 4, 391 (2005); ^2V. Blum, G. Hart, M. Walorski and A. Zunger, Phys. Rev. B 72, 165113 (2005).
Features of simultaneous ground- and excited-state lasing in quantum dot lasers
Zhukov, A. E. Maximov, M. V.; Shernyakov, Yu. M.; Livshits, D. A.; Savelyev, A. V.; Zubov, F. I.; Klimenko, V. V.
2012-02-15
The lasing spectra and light-current (L-I) characteristics of an InAs/InGaAs quantum dot laser emitting in the simultaneous lasing mode at the ground- and excited-state optical transitions are studied. Lasing and spontaneous emission spectra are compared. It is shown that ground-state quenching of lasing is observed even in the absence of active region self-heating or an increase in homogeneous broadening with growth in the current density. It is found that the intensities of both lasing and spontaneous emission at the ground-state transition begin to decrease at a pump intensity that significantly exceeds the two-level lasing threshold. It is also found that different groups of quantum dots are involved in ground- and excited-state lasing.
Note on ultraviolet renormalization and ground state energy of the Nelson model
Fumio Hiroshima
2015-07-19
Ultraviolet (UV) renormalization of the Nelson model in quantum field theory is considered. A relationship between a ultraviolet renormalization term and the ground state energy of the Hamiltonian with total momentum zero is studied by functional integrations.
Yang, Juan
2007-09-17
The vibrational potential energy surfaces in electronic ground and excited states of several ring molecules were investigated using several different spectroscopic methods, including far-infrared (IR), Raman, ultraviolet ...
Precision study of ground state capture in the 14N(p,gamma)15O reaction
M. Marta; A. Formicola; Gy. Gyurky; D. Bemmerer; C. Broggini; A. Caciolli; P. Corvisiero; H. Costantini; Z. Elekes; Zs. Fulop; G. Gervino; A. Guglielmetti; C. Gustavino; G. Imbriani; M. Junker; R. Kunz; A. Lemut; B. Limata; C. Mazzocchi; R. Menegazzo; P. Prati; V. Roca; C. Rolfs; M. Romano; C. Rossi Alvarez; E. Somorjai; O. Straniero; F. Strieder; F. Terrasi; H. P. Trautvetter; A. Vomiero
2008-07-30
The rate of the hydrogen-burning carbon-nitrogen-oxygen (CNO) cycle is controlled by the slowest process, 14N(p,gamma)15O, which proceeds by capture to the ground and several excited states in 15O. Previous extrapolations for the ground state contribution disagreed by a factor 2, corresponding to 15% uncertainty in the total astrophysical S-factor. At the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator placed deep underground in the Gran Sasso facility in Italy, a new experiment on ground state capture has been carried out at 317.8, 334.4, and 353.3 keV center-of-mass energy. Systematic corrections have been reduced considerably with respect to previous studies by using a Clover detector and by adopting a relative analysis. The previous discrepancy has been resolved, and ground state capture no longer dominates the uncertainty of the total S-factor.
Trajectory approach to the Schrödinger-Langevin equation with linear dissipation for ground states
NASA Astrophysics Data System (ADS)
Chou, Chia-Chun
2015-11-01
The Schrödinger-Langevin equation with linear dissipation is integrated by propagating an ensemble of Bohmian trajectories for the ground state of quantum systems. Substituting the wave function expressed in terms of the complex action into the Schrödinger-Langevin equation yields the complex quantum Hamilton-Jacobi equation with linear dissipation. We transform this equation into the arbitrary Lagrangian-Eulerian version with the grid velocity matching the flow velocity of the probability fluid. The resulting equation is simultaneously integrated with the trajectory guidance equation. Then, the computational method is applied to the harmonic oscillator, the double well potential, and the ground vibrational state of methyl iodide. The excellent agreement between the computational and the exact results for the ground state energies and wave functions shows that this study provides a synthetic trajectory approach to the ground state of quantum systems.
Ground-state information geometry and quantum criticality in an inhomogeneous spin model
NASA Astrophysics Data System (ADS)
Ma, Yu-Quan
2015-09-01
We investigate the ground-state Riemannian metric and the cyclic quantum distance of an inhomogeneous quantum spin-1/2 chain in a transverse field. This model can be diagonalized by using a general canonical transformation to the fermionic Hamiltonian mapped from the spin system. The ground-state Riemannian metric is derived exactly on a parameter manifold ring S1, which is introduced by performing a gauge transformation to the spin Hamiltonian through a twist operator. The cyclic ground-state quantum distance and the second derivative of the ground-state energy are studied in different exchange coupling parameter regions. Particularly, we show that, in the case of exchange coupling parameter Ja = Jb, the quantum ferromagnetic phase can be characterized by an invariant quantum distance and this distance will decay to zero rapidly in the paramagnetic phase. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404023 and 11347131).
Observation of a kilogram-scale oscillator near its quantum ground state
Bayer, K.
We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale system—an interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave ...
Chun-Ling Leng; Qi Guo; Xin Ji; Shou Zhang
2014-12-11
We propose a scheme for generating a genuine $\\chi$-type four-particle entangled state of superconducting artificial atoms with broken symmetry by using one-dimensional transmission line resonator as a data bus. The $\\Delta$-type three-level artificial atom we use in the scheme is different from natural atom and has cyclic transitions. After suitable interaction time and simple operations, the desired entangled state can be obtained. Since artificial atomic excited states and photonic states are adiabatically eliminated, our scheme is robust against the spontaneous emissions of artificial atoms and the decays of transmission line resonator.
Ground-state properties and superfluidity of two- and quasi-two-dimensional solid 4He.
Cazorla, C; Astrakharchik, G E; Casulleras, J; Boronat, J
2010-04-28
In a recent study we have reported a new type of trial wavefunction symmetric under the exchange of particles, which is able to describe a supersolid phase. In this work, we use the diffusion Monte Carlo method and this model wavefunction to study the properties of solid (4)He in two- and quasi-two-dimensional geometries. In the purely two-dimensional (2D) case, we obtain results for the total ground-state energy and freezing and melting densities which are in good agreement with previous exact Monte Carlo calculations performed with a slightly different interatomic potential model. We calculate the value of the zero-temperature superfluid fraction ?(s)/? of 2D solid (4)He and find that it is negligible in all the considered cases, similarly to what is obtained in the perfect (free of defects) three-dimensional crystal using the same computational approach. Interestingly, by allowing the atoms to move locally in the direction perpendicular to the plane where they are confined to zero-point oscillations (quasi-2D crystal), we observe the emergence of a finite superfluid density that coexists with the periodicity of the system. PMID:21386422
Ground and Excited States of an Anisotropically Confined Condensed Bose Gas
NASA Astrophysics Data System (ADS)
Schneider, Barry I.; Feder, David L.; Clark, Charles W.
1998-03-01
The ground and excited states of a weakly interacting and dilute Bose gas confined in a completely anisotropic harmonic oscillator potential are determined self-consistently for both zero and finite temperatures. The numerical calculations employ an efficient procedure based on the discrete variable representation (DVR).(J.C. Light, I.P. Hamilton, and J.V. Lill, J. Chem. Phys. 82), 1400 (1985). Standard iterative techniques applied to the solution of the non-linear differential equation for the condensate are usually non-convergent, particularly for large number of atoms. This limitation is overcome using the method of the direct inversion in the iterated subspace.(P. Pulay, Chem. Phys. Lett. 73), 393 (1980), J. Comp. Chem. 3, 556 (1982). The sparse structure of the DVR representation also enables the efficient application of iterative techniques, such as the Davidson and/or Lanczos methods, to extract the relevant eigenvalues. The results are compared with recent experimental data obtained for Bose-condensed alkali metal vapors confined in magnetic traps.
Singlet Ground State of the Quantum Antiferromagnet Ba3CuSb2O9 J. A. Quilliam,1
Paris-Sud 11, Université de
that there is a total absence of spin freezing in the ground state. Sb NMR measurements allow us to track the intrinsicSinglet Ground State of the Quantum Antiferromagnet Ba3CuSb2O9 J. A. Quilliam,1 F. Bert,1 E are ex- pected to have QSL ground states and apparent JT insta- bilities make it even more surprising
Infrared diode laser spectroscopy of the electronic ground state of SnD
NASA Astrophysics Data System (ADS)
Simon, U.; Petri, M.; Zimmermann, W.; Huhn, G.; Urban, W.
We report the first direct observation of the vibration-rotation spectrum of the tin deuteride radical in its electronic ground state 2? by infrared diode laser spectroscopy. The SnD radicals were produced using tetramethylstannane (Sn(CH3)4) and deuterium in a DC helium glow discharge. The isotopic structure, the lambda-type doubling and the hyperfine splitting due to the tin nucleus could be resolved. A set of molecular parameters for the ground state is given.
On crystal ground state in the Schrödinger-Poisson model: point ions
A. I. Komech
2015-11-29
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.
Slow ground state molecules from matrix isolation sublimation
NASA Astrophysics Data System (ADS)
Oliveira, A. N.; Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L.
2014-12-01
We describe the generation and properties of a cryogenic beam of 7Li2 dimers from sublimation of a neon matrix where lithium atoms have been implanted via laser ablation of solid precursors of metallic lithium or lithium hydride (LiH). Different sublimation regimes lead to pulsed molecular beams with different temperatures, densities and forward velocities. With laser absorption spectroscopy these parameters were measured using the molecular 7Li2 (R) transitions A1? u+(v\\prime =4,J\\prime =J\\prime\\prime +1) ?ftarrow X 1? g+(v\\prime\\prime =0,J\\prime\\prime =0,1,3). In a typical regime, sublimating a matrix at 16 K, translational temperatures of 6-8 K with a drift velocity of 130 m s-1 in a free expanding pulsed beam with molecular density of 109 cm-3, averaged along the laser axis, were observed. Rotational temperatures around 5-7 K were obtained. In recent experiments we were able to monitor the atomic Li signal—in the D2 line—concomitantly with the molecular signal in order to compare them as a function of the number of ablation pulses. Based on the data and a simple model, we discuss the possibility that a fraction of these molecules are being formed in the matrix, by mating atoms from different ablation pulses, which would open up the way to formation of other more interesting and difficult molecules to be studied at low temperatures. Such a source of cryogenic molecules have possible applications encompassing fundamental physics tests, quantum information studies, cold collisions, chemistry, and trapping.
NASA Astrophysics Data System (ADS)
Marcotte, Étienne; DiStasio, Robert A., Jr.; Stillinger, Frank H.; Torquato, Salvatore
2013-11-01
In the first paper of this series [DiStasio, Jr., Marcotte, Car, Stillinger, and Torquato, Phys. Rev. B10.1103/PhysRevB.88.134104 88, 134104 (2013)], we applied inverse statistical-mechanical techniques to study the extent to which targeted spin configurations on the square lattice can be ground states of finite-ranged radial spin-spin interactions. In this sequel, we enumerate all of the spin configurations within a unit cell on the one-dimensional integer lattice and the two-dimensional square lattice up to some modest size under periodic boundary conditions. We then classify these spin configurations into those that can or cannot be unique classical ground states of the aforementioned radial pair spin interactions and found the relative occurrences of these ground-state solution classes for different system sizes. As a result, we also determined the minimal radial extent of the spin-spin interaction potentials required to stabilize those configurations whose ground states are either unique or degenerate (i.e., those sharing the same radial spin-spin correlation function). This enumeration study has established that unique ground states are not limited to simple target configurations. However, we also found that many simple target spin configurations cannot be unique ground states.
A high flux pulsed source of energetic atomic oxygen. [for spacecraft materials ground testing
NASA Technical Reports Server (NTRS)
Krech, Robert H.; Caledonia, George E.
1986-01-01
The design and demonstration of a pulsed high flux source of nearly monoenergetic atomic oxygen are reported. In the present test setup, molecular oxygen under several atmospheres of pressure is introduced into an evacuated supersonic expansion nozzle through a pulsed molecular beam valve. A 10J CO2 TEA laser is focused to intensities greater than 10 to the 9th W/sq cm in the nozzle throat, generating a laser-induced breakdown with a resulting 20,000-K plasma. Plasma expansion is confined by the nozzle geometry to promote rapid electron-ion recombination. Average O-atom beam velocities from 5-13 km/s at fluxes up to 10 to the 18th atoms/pulse are measured, and a similar surface oxygen enrichment in polyethylene samples to that obtained on the STS-8 mission is found.
Delin, Geoffrey N.; Risser, Dennis W.
2007-01-01
Increased demands on water resources by a growing population and recent droughts have raised awareness about the adequacy of ground-water resources in humid areas of the United States. The spatial and temporal variability of ground-water recharge are key factors that need to be quantified to determine the sustainability of ground-water resources. Ground-water recharge is defined herein as the entry into the saturated zone of water made available at the water-table surface, together with the associated flow away from the water table within the saturated zone (Freeze and Cherry, 1979). In response to the need for better estimates of ground-water recharge, the Ground-Water Resources Program (GWRP) of the U.S. Geological Survey (USGS) began an initiative in 2003 to estimate ground-water recharge rates in the relatively humid areas of the United States.
Young, C.E.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.
1983-01-01
Velocity distributions and relative populations in the fine-structure levels of the a/sup 5/D/sub J/ ground state of Fe atoms, produced by sputtering with 3 keV argon ions, have been investigated by Doppler shifted laser induced fluorescence. The laser system employs a single-mode, scanning ring dye laser, amplified by a sequence of three excimer-pumped flowing-dye cells. Frequency doubling in a KD*P crystal was used to produce high energy (> .5 mJ) pulses of narrowband tunable UV output near 300 nm. Laser power influence on effective velocity bandwidth was investigated. Favorable light-collection geometry minimized distortion of the velocity spectra from apparatus-averaging effects. In impurity flux diagnostic applications in fusion devices, substantial spatial averaging may occur. In the latter case, the narrow velocity bandwidth (70 m/s, transform limit) of the present laser system is particularly useful.
NASA Astrophysics Data System (ADS)
Suo, Bingbing; Yu, Yan-Mei; Han, Huixian
2015-03-01
We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for ? = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of ? = 1/2, which is highly mixed with 4?- and 2? states in ? - S notation. The two low-lying states 5/2 and 7/2 are nearly degenerate with the ground state and locate only 234 and 260 cm-1 above, respectively. The equilibrium bond length 1.712 Å and the harmonic vibrational frequency 903 cm-1 of the 5/2 state are close to the experimental measurement of 1.724 Å and 909 cm-1, which suggests that the 5/2 state should be the low-lying state that contributes to the experimental spectra. Moreover, the electronic states that give rise to the observed transition bands are assigned for ? = 5/2 and 7/2 in terms of the obtained excited energies and oscillator strengths.
Suo, Bingbing; Yu, Yan-Mei; Han, Huixian
2015-03-07
We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for ? = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of ? = 1/2, which is highly mixed with {sup 4}?{sup ?} and {sup 2}? states in ? ? S notation. The two low-lying states 5/2 and 7/2 are nearly degenerate with the ground state and locate only 234 and 260 cm{sup ?1} above, respectively. The equilibrium bond length 1.712 Å and the harmonic vibrational frequency 903 cm{sup ?1} of the 5/2 state are close to the experimental measurement of 1.724 Å and 909 cm{sup ?1}, which suggests that the 5/2 state should be the low-lying state that contributes to the experimental spectra. Moreover, the electronic states that give rise to the observed transition bands are assigned for ? = 5/2 and 7/2 in terms of the obtained excited energies and oscillator strengths.
Long Distance, Unconditional Teleportation of Atomic States Via Complete Bell State Measurements
S. Lloyd; M. S. Shahriar; P. R. Hemmer
2001-01-30
This paper proposes a scheme for creating and storing quantum entanglement over long distances. Optical cavities that store this long-distance entanglement in atoms could then function as nodes of a quantum network, in which quantum information is teleported from cavity to cavity. The teleportation can be carried out unconditionally via measurements of all four Bell states, using a method of sequential elimination.
Sonam Mahajan; Neha Aggarwal; Aranya B Bhattacherjee; ManMohan
2013-02-02
We present a detailed study to show the possibility of approaching the quantum ground-state of a hybrid optomechanical quantum device formed by a Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity with an oscillatory end mirror. Cooling is achieved using two experimentally realizable schemes: back-action cooling and cold damping quantum feedback cooling. In both the schemes, we found that increasing the two body atom-atom interaction brings the mechanical oscillator to its quantum ground state. It has been observed that back-action cooling is more effective in the good cavity limit while the cold damping cooling scheme is more relevant in the bad cavity limit. It is also shown that in the cold damping scheme, the device is more efficient in the presence of BEC than in the absence of BEC.
NASA Astrophysics Data System (ADS)
Mahajan, Sonam; Aggarwal, Neha; Bhattacherjee, Aranya B.; ManMohan
2013-04-01
We present a detailed study to show the possibility of approaching the quantum ground state of a hybrid optomechanical quantum device formed by a Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity with an oscillatory end mirror. Cooling is achieved using two experimentally realizable schemes: back-action cooling and cold damping quantum feedback cooling. In both the schemes, we found that increasing the two-body atom-atom interaction brings the mechanical oscillator to its quantum ground state. It has been observed that back-action cooling is more effective in the good cavity limit, while the cold damping cooling scheme is more relevant in the bad cavity limit. It is also shown that in the cold damping scheme, the device is more efficient in the presence of a BEC than in the absence of a BEC.
NASA Astrophysics Data System (ADS)
Luo, Ming-Xing; Deng, Yun; Li, Hui-Ran; Wang, Xiaojun
2015-10-01
Multipartite entangled state plays a crucial role in quantum applications. We propose theoretical schemes to generate entanglements among several trapped atoms with the help of quantum dots in single-side optical microcavities. In the first scheme, a basic architecture will be built to produce arbitrary N-atom GHZ state by using only one auxiliary photon. Moreover, using a photon state with multiple modes, we can realize 2^n-atom W state. All these schemes are insensitive to the variation of the atom-photon coupling rates and are also right for remotely trapped atoms by using the photonic transmissions, local quantum operations, and classical channel. Simulations show that our schemes are faithful and available with present physical techniques.
Suo, Bingbing; Han, Huixian
2014-01-01
We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest states for four spin-orbit components 1/2, 3/2, 5/2, and 7/2 are calculated intensively to clarify the ground state of IrO. Our calculation suggests that the ground state is of 1/2 spin-orbit component, which is highly mixed with $^4\\Sigma^-$ and $^2\\Pi$ states in $\\Lambda-S$ notation. The two low-lying states of the 5/2 and 7/2 spin-orbit components are nearly degenerate with the ground state and locate only 234 and 260 cm$^{-1}$ above, respectively. The equilibrium bond length 1.712 \\AA \\ and harmonic vibrational frequency 903 cm$^{-1}$ of the 5/2 spin-orbit component are close to the experimental measurement of 1.724 \\AA \\ and 909 cm$^{-1}$, which suggests the 5/2 state should be the low-lying state contributed to spectra in experimental study. Moreover, the electronic states that give rise to the observed trans...
Exact ground states of a staggered supersymmetric model for lattice fermions
Huijse, L.; Moran, N.; Vala, J.; Schoutens, K.
2011-09-15
We study a supersymmetric model for strongly interacting lattice fermions in the presence of a staggering parameter. The staggering is introduced as a tunable parameter in the manifestly supersymmetric Hamiltonian. We obtain analytic expressions for the ground states in the limit of small and large staggering for the model on the class of doubly decorated lattices. On this type of lattice there are two ground states, each with a different density. In one limit we find these ground states to be a simple Wigner crystal and a valence bond solid state. In the other limit we find two types of quantum liquids. As a special case, we investigate the quantum liquid state on the one dimensional chain in detail. It is characterized by a massless kink that separates two types of order.
Spin-split antibonding molecular ground state in manganese-doped quantum dot molecules
NASA Astrophysics Data System (ADS)
Qu, Fanyao; Villegas-Lelovsky, L.; Morais, P. C.
2015-09-01
Tunnel coupling between two dots in manganese-doped InAs/GaAs quantum dot molecules (QDMs), valence band mixing, and p -d exchange interaction between holes and localized d electrons give rise to a tunability of charge, spin, and molecular orbitals. The interplay among them determines the nature of the molecular ground state. Remarkably, unlike usual diatomic molecules in which the bonding (BD) state is always the ground state, we found that the molecular ground state in Mn-doped QDMs is of antibonding (AB) character. Furthermore, it is a spin-split state and can be switched into the spin-split BD type. We also demonstrate that this unusual behavior can be tuned by the lateral confinement strength of the QDMs, the concentration, and the distribution of manganese as well as the electric field applied along the direction of the QDM axis.
The ground electronic state of KCs studied by Fourier transform spectroscopy.
Ferber, R; Klincare, I; Nikolayeva, O; Tamanis, M; Knöckel, H; Tiemann, E; Pashov, A
2008-06-28
We present here the first analysis of laser induced fluorescence (LIF) of the KCs molecule obtaining highly accurate data and perform a direct potential construction for the X (1)Sigma(+) ground state in a wide range of internuclear distances. KCs molecules were produced by heating a mixture of K and Cs metals in a heat pipe at a temperature of about 270 degrees C. KCs fluorescence was induced by different laser sources: the 454.5, 457.9, 465.8, and 472.7 nm lines of an Ar(+) laser, a dye laser with Rhodamine 6G dye (excitation at around 16 870 cm(-1)), and 850 and 980 nm diode lasers (11 500-11 900 and 10 200-10 450 cm(-1) tuning ranges, respectively). The LIF to the ground state was recorded by a Bruker IFS-125HR Fourier transform spectrometer with a spectral resolution of 0.03 cm(-1). Particularly, by applying the 850 nm laser diode we were able to observe LIF progressions to very high vibrational levels of the ground state close to the dissociation limit. The present data field contains 7226 term values for the ground state X (1)Sigma(+) and covers a range from v(")=0 to 97 with J(") varying from 12 to 209. More than 10 000 fluorescence lines were used to fit the ground state potential energy curve via the inverted perturbation approach procedure. The present empirical potential extends up to approximately 12.6 A and covers more than 99% of the potential well depth, it describes most of the spectral lines with an accuracy of about 0.003 cm(-1) and yields a dissociation energy of 4069.3+/-1.5 cm(-1) for the ground state X (1)Sigma(+). First observations of the triplet ground state a (3)Sigma(+) of KCs are presented, and preliminary values of few main molecular constants could be derived. PMID:18601341
NASA Technical Reports Server (NTRS)
Bouquet, Frank L.; Maag, Carl R.
1986-01-01
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.
NASA Technical Reports Server (NTRS)
Banks, Bruce A.; Dill, Grace C.; Loftus, Ryan J.; deGroh, Kim K.; Miller, Sharon K.
2013-01-01
The atomic oxygen erosion yields of 26 materials (all polymers except for pyrolytic graphite) were measured in two directed hyperthermal radio frequency (RF) plasma ashers operating at 30 or 35 kHz with air. The hyperthermal asher results were compared with thermal energy asher results and low Earth orbital (LEO) results from the Materials International Space Station Experiment 2 and 7 (MISSE 2 and 7) flight experiments. The hyperthermal testing was conducted to a significant portion of the atomic oxygen fluence similar polymers were exposed to during the MISSE 2 and 7 missions. Comparison of the hyperthermal asher prediction of LEO erosion yields with thermal energy asher erosion yields indicates that except for the fluorocarbon polymers of PTFE and FEP, the hyperthermal energy ashers are a much more reliable predictor of LEO erosion yield than thermal energy asher testing, by a factor of four.
Using soil stress state transducers in freezing ground
Technology Transfer Automated Retrieval System (TEKTRAN)
Three instrumented test sections of sand, silt and clay, were constructed to monitor the impact of frost layers on vehicle-induced stresses and to assess the performance of the sensors used to measure such stresses. One of the instruments used to measure in-situ stress is the soil Stress State Tran...
Periodic ground state for the charged massive Schwinger model
Nagy, S.; Sailer, K.; Polonyi, J.
2004-11-15
It is shown that the charged massive Schwinger model supports a periodic vacuum structure for arbitrary charge density, similar to the common crystalline layout known in solid state physics. The dynamical origin of the inhomogeneity is identified in the framework of the bosonized model and in terms of the original fermionic variables.
ERIC Educational Resources Information Center
Bandyopadhyay, Subhajit; Roy, Saswata
2014-01-01
This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…
Short-range correlations in the magnetic ground state of Na4 Ir3 O8
NASA Astrophysics Data System (ADS)
Dally, Rebecca; Hogan, Tom; Amato, Alex; Luetkens, Hubertus; Baines, Chris; Rodriguez-Rivera, Jose; Graf, Michael; Wilson, Stephen
2015-03-01
The magnetic ground state of the candidate three-dimensional quantum spin liquid Na4 Ir3O8 has been studied through bulk magnetization, muon spin relaxation and neutron scattering measurements. Na4 Ir3O8 possesses a unique hyper-Kagome lattice of Ir moments that is potentially accompanied by a novel realization of Heisenberg-Kitaev exchange. This fact combined with the absence of previously reported magnetic ordering has led to its candidacy as a three-dimensional quantum spin liquid. Our combined experimental data show that a short-range, frozen, ground state comprised of quasi-static moments develops in this material below a characteristic temperature TF = 6 K , persisting down until at least 20 mK. The expected dynamical ground state of a quantum spin liquid was not observed but rather an inhomogeneous quasi-static spin state that survives with persistent long timescale fluctuations.
Exact many-electron ground states on the diamond Hubbard chain
NASA Astrophysics Data System (ADS)
Gulacsi, Zsolt; Kampf, Arno; Vollhardt, Dieter
2008-03-01
Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnetism, correlation induced metallic, half-metallic, or insulating behavior [1]. The properties of these ground states can be tuned by changing the magnetic flux, local potentials, or electron density.The results show that the studied simple one-dimensional structure displays remarkably complex physical properties. The virtue of tuning different ground states through external parameters points to new possibilities for the design of electronic devices which can switch between insulating or conducting and nonmagnetic or (fully or partially spin polarized) ferromagnetic states, open new routes for the design of spin-valve devices and gate induced ferromagnetism. [1] Z. Gulacsi, A. Kampf, D. Vollhardt, Phys. Rev. Lett. 99, 026404(2007).
Multidimensional hydrogen tunneling dynamics in the ground vibrational state of the ammonia dimer
Elrod, Matthew J.
Multidimensional hydrogen tunneling dynamics in the ground vibrational state of the ammonia dimer new far-infrared absorption lines and 12 new microwave absorption lines of the ammonia dimer. Our data. The vibration-rotation-tunneling (VRT) states of the ammonia dimer connected by electric- dipole
GROUND WATER CONTAMINANTS AND THEIR SOURCES - A REVIEW OF STATE REPORTS
Pursuant to section 305(B) of the Clean Water Act of 1987, each state submits biennially a water quality report to the U.S. Environmental Protection Agency (EPA). his paper contains a review of 42 such reports in relation to public ground water supplies. ineteen states provided m...
Influence of periodically modulated cavity field on the generation of atomic-squeezed states
Neha Aggarwal; Aranya B Bhattacherjee; Arup Banerjee; Man Mohan
2015-04-07
We investigate the influence of periodically time-modulated cavity frequency on the generation of atomic squeezed states for a collection of N two-level atoms confined in a non-stationary cavity with a moving mirror. We show that the two-photon character of the field generated from the vacuum state of field plays a significant role in producing the atomic or spin squeezed states. We further show that the maximum amount of persistent atomic squeezing is obtained for the initial cavity field prepared in the vacuum state.
On the ground state electronic structure of uranium dioxide
NASA Astrophysics Data System (ADS)
Krack, Matthias
2015-09-01
Fully unconstrained cell optimizations of uranium dioxide (UO2) bulk model systems using the Gaussian plane waves method are presented. Different effective {U}{eff} values are employed for various initial uranium 5f orbital occupation patterns in the framework of a spin polarized DFT+U approach based on the generalized gradient approximation proposed by Perdew, Burke, and Ernzerhof. The detected low-lying states are presented and their properties are analyzed. A new lowest energy state has been detected with a mixed 5f orbital occupation pattern different from the proposed ones so far which shows also favorable properties. The presented results are relevant for future investigations using DFT+U or hybrid functional methods for the study of actinide systems like UO2, especially defective ones.
Precision Measurement of the 87-Rb Tune-Out Wavelength in the Hyperfine Ground State F=1 at 790 nm
Schmidt, Felix; Hohmann, Michael; Lausch, Tobias; Kindermann, Farina; Widera, Artur
2015-01-01
We report on a precision measurement of the $D$ line tune-out wavelength of $^{87}$Rubidium in the hyperfine ground state $|F=1, m_F=0,\\pm1 \\rangle$ manifold at 790 nm, where the scalar ac Stark shifts of the $D_1$ and the $D_2$ lines cancel. This wavelength is sensitive to usually neglected contributions from vector and tensor ac Stark shifts, transitions to higher principle quantum numbers, and core electrons. The ac Stark shift is probed by Kapitza-Dirac scattering of a Rubidium Bose-Einstein condensate in a one-dimensional optical lattice in free space and controlled magnetic environment. The tune-out wavelength of the magnetically insensitive $m_F=0$ state was determined to 790.01858(23) nm with sub pm accuracy. An in situ absolute polarization, and magnetic background field measurement is performed by employing the ac vector Stark shift for the $m_F=\\pm 1$ states. Comparing our findings to theory, we get quantitative insight into atomic physics beyond commonly used two-level atom approximations or the n...
The two-electron atomic systems. S-states
NASA Astrophysics Data System (ADS)
Liverts, Evgeny Z.; Barnea, Nir
2010-01-01
A simple Mathematica program for computing the S-state energies and wave functions of two-electron (helium-like) atoms (ions) is presented. The well-known method of projecting the Schrödinger equation onto the finite subspace of basis functions was applied. The basis functions are composed of the exponentials combined with integer powers of the simplest perimetric coordinates. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of results and computation time depend on the basis size. The precise energy values of 7-8 significant figures along with the corresponding wave functions can be computed on a single processor within a few minutes. The resultant wave functions have a simple analytical form consisting of elementary functions, that enables one to calculate the expectation values of arbitrary physical operators without any difficulties. Program summaryProgram title: TwoElAtom-S Catalogue identifier: AEFK_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFK_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10 185 No. of bytes in distributed program, including test data, etc.: 495 164 Distribution format: tar.gz Programming language: Mathematica 6.0; 7.0 Computer: Any PC Operating system: Any which supports Mathematica; tested under Microsoft Windows XP and Linux SUSE 11.0 RAM:?10 bytes Classification: 2.1, 2.2, 2.7, 2.9 Nature of problem: The Schrödinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or other physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple basis set in three perimetric coordinates. Method of projecting the two-electron Schrödinger equation (for atoms/ions) onto a subspace of the basis functions enables one to obtain the set of homogeneous linear equations F.C=0 for the coefficients C of the above expansion. The roots of equation det(F)=0 yield the bound energies. Restrictions: First, the too large length of expansion (basis size) takes the too large computation time giving no perceptible improvement in accuracy. Second, the order of polynomial ? (input parameter) in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Additional comments: The CPC Program Library includes "A program to calculate the eigenfunctions of the random phase approximation for two electron systems" (AAJD). It should be emphasized that this fortran code realizes a very rough approximation describing only the averaged electron density of the two electron systems. It does not characterize the properties of the individual electrons and has a number of input parameters including the Roothaan orbitals. Running time: ˜10 minutes (depends on basis size and computer speed)
U. Vogl; M. Weitz
2007-04-17
We have recorded fluorescence spectra of the atomic rubidium D-lines in the presence of several hundreds of bars buffer gas pressure. With additional saturation broadening a spectral linewidth comparable to the thermal energy of the atoms in the heated gas cell is achieved. An intensity-dependent blue asymmetry of the spectra is observed, which becomes increasingly pronounced when extrapolating to infinitely high light intensity. We interpret our results as evidence for the dressed (coupled atom-light) states to approach thermal equilibrium.
NASA Astrophysics Data System (ADS)
Pino, H.; Alba, E.; Taron, J.; Garcia-Ripoll, J. J.; Barberán, N.
2013-05-01
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.
Core-level spectroscopy to probe the oxidation state of single europium atoms.
Tizei, Luiz H G; Nakanishi, Ryo; Kitaura, Ryo; Shinohara, Hisanori; Suenaga, Kazu
2015-05-15
The valence of individual europium atoms confined in carbon nanotubes is successfully measured by using core-level electron energy loss spectroscopy. Changes in the oxidation state at the atomic scale have been observed in Eu atomic chains exposed to oxygen. A transitory behavior has been identified where multiple atoms show a signal consistent with a sum of Eu^{2+} and Eu^{3+}. This indicates that single atoms change their valence state multiple times during the reaction, suggesting that oxidation in confined spaces and with extra energy input (from the electron beam) might not be a simple one step electron transfer event. PMID:26024198
Atomic solid state energy scale: Universality and periodic trends in oxidation state
NASA Astrophysics Data System (ADS)
Pelatt, Brian D.; Kokenyesi, Robert S.; Ravichandran, Ram; Pereira, Clifford B.; Wager, John F.; Keszler, Douglas A.
2015-11-01
The atomic solid state energy (SSE) scale originates from a plot of the electron affinity (EA) and ionization potential (IP) versus band gap (EG). SSE is estimated for a given atom by assessing an average EA (for a cation) or an average IP (for an anion) for binary inorganic compounds having that specific atom as a constituent. Physically, SSE is an experimentally-derived average frontier orbital energy referenced to the vacuum level. In its original formulation, 69 binary closed-shell inorganic semiconductors and insulators were employed as a database, providing SSE estimates for 40 elements. In this contribution, EA and IP versus EG are plotted for an additional 92 compounds, thus yielding SSE estimates for a total of 64 elements from the s-, p-, d-, and f-blocks of the periodic table. Additionally, SSE is refined to account for its dependence on oxidation state. Although most cations within the SSE database are found to occur in a single oxidation state, data are available for nine d-block transition metals and one p-block main group metal in more than one oxidation state. SSE is deeper in energy for a higher cation oxidation state. Two p-block main group non-metals within the SSE database are found to exist in both positive and negative oxidation states so that they can function as a cation or anion. SSEs for most cations are positioned above -4.5 eV with respect to the vacuum level, and SSEs for all anions are positioned below. Hence, the energy -4.5 eV, equal to the hydrogen donor/acceptor ionization energy ?(+/-) or equivalently the standard hydrogen electrode energy, is considered to be an absolute energy reference for chemical bonding in the solid state.
W. M. Seif; M. M. Botros; A. I. Refaie
2015-07-23
The ground-state spin and parity of a formed daughter in the radioactive Alpha-emitter is expected to influence the preformation probability of the Alpha and daughter clusters inside it. We investigate the Alpha and daughter preformation probability inside odd-A and doubly-odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground-state to ground-state unfavored decays. This is to extract precise information about the effect of the difference in the ground states spin-parity of the involved nuclei far away any influences from the excitation energy if the decays are coming from isomeric states. The calculations are done for 161 Alpha-emitters, with Z=65-112 and N=84-173, in the framework of the extended cluster model, with WKB penetrability and assault frequency. We used a Hamiltonian energy density scheme based on Skyrme-SLy4 interaction to compute the interaction potential. The Alpha plus cluster preformation probability is extracted from the calculated decay width and the experimental half-life time. We discussed in detailed steps the effect of angular momentum of the emitted Alpha-particle on the various physical quantities involved in the unfavored decay process and how it is finally increases the half-life time. We found that if the ground states spin and/or parity of parent and daughter nuclei are different, then the preformation probability of the Alpha-cluster inside parent is less than it would be if they have similar spin-parity. We modified the formula that gives the Alpha preformation probability in terms of the numbers of protons and neutrons outside the shell closures of parent, to account for this hindrance in the preformation probability for the unfavored decays between ground states.
NASA Astrophysics Data System (ADS)
Seif, W. M.; Botros, M. M.; Refaie, A. I.
2015-10-01
The ground state spin and parity of a daughter formed in a radioactive ? emitter are expected to influence the preformation probability of the ? and daughter clusters inside it. We investigate the ? and daughter preformation probability inside odd-A and doubly odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground state to ground state unfavored decays. This is to extract precise information about the effect of the difference in the spin-parity of the ground states of the involved nuclei far away from any influence from the excitation energy, if the decays are coming from isomeric states. The calculations are done for 161 ? emitters, with 65 ?Z ?112 and 84 ?N ?173 , in the framework of the extended cluster model, with the Wentzel-Kramers-Brillouin penetrability and assault frequency. We used a Hamiltonian energy density scheme based on the Skyrme SLy4 interaction to compute the interaction potential. The ? -plus-cluster preformation probability is extracted from the calculated decay width and the experimental half-life time. We discussed in detailed steps the effect of the angular momentum of the emitted ? particle on the various physical quantities involved in the unfavored decay process and how it finally increases the half-life time. We found that if the ground state spin and/or parity of parent and daughter nuclei are different, then the preformation probability of the ? cluster inside the parent is less than it would be if they had similar spin-parity. We modified the formula that gives the ? preformation probability in terms of the numbers of protons and neutrons outside the shell closures of the parent, to account for this hindrance in the preformation probability for the unfavored decays between ground states.
Ground states of stealthy hyperuniform potentials. II. Stacked-slider phases
Ge Zhang; Frank H. Stillinger; Salvatore Torquato
2015-08-19
Stealthy potentials, a family of long-range isotropic pair potentials, produce infinitely degenerate disordered ground states at high densities and crystalline ground states at low densities in d-dimensional Euclidean space R^d. In the previous paper in this series, we numerically studied the entropically favored ground states in the canonical ensemble in the zero-temperature limit across the first three Euclidean space dimensions. In this paper, we investigate using both numerical and theoretical techniques metastable stacked-slider phases, which are part of the ground-state manifold of stealthy potentials at densities in which crystal ground states are favored entropically. Our numerical results enable us to devise analytical models of this phase in two, three, and higher dimensions. Utilizing this model, we estimated the size of the feasible region in configuration space of the stacked-slider phase, finding it to be smaller than that of crystal structures in the infinite-system-size limit, which is consistent with our recent previous work. In two dimensions, we also determine exact expressions for the pair correlation function and structure factor of the analytical model of stacked-slider phases and analyze the connectedness of the ground-state manifold of stealthy potentials in this density regime. We demonstrate that stacked-slider phases are distinguishable states of matter; they are nonperiodic, statistically anisotropic structures that possess long-range orientational order but have zero shear modulus. We outline some possible future avenues of research to elucidate our understanding of this unusual phase of matter.
Inversion symmetry breaking of atomic bound states in strong and short laser fields
Stooß, Veit; Ott, Christian; Blättermann, Alexander; Ding, Thomas; Pfeifer, Thomas
2015-01-01
In any atomic species, the spherically symmetric potential originating from the charged nucleus results in fundamental symmetry properties governing the structure of atomic states and transition rules between them. If atoms are exposed to external electric fields, these properties are modified giving rise to energy shifts such as the AC Stark-effect in varying fields and, contrary to this in a constant (DC) electric field for high enough field strengths, the breaking of the atomic symmetry which causes fundamental changes in the atom's properties. This has already been observed for atomic Rydberg states with high principal quantum numbers. Here, we report on the observation of symmetry breaking effects in Helium atoms for states with principal quantum number n=2 utilizing strong visible laser fields. These findings were enabled by temporally resolving the dynamics better than the sub-optical cycle of the applied laser field, utilizing the method of attosecond transient absorption spectroscopy (ATAS). We ident...
NASA Astrophysics Data System (ADS)
Korolkov, M. V.; Manz, J.; Paramonov, G. K.
1997-05-01
An overview of the current state of the art in the laser control of molecular dynamics is presented with a special emphasis on the ultrafast vibrationally state-selective processes controlled by short and shaped infrared laser pulses. Ultrafast state-selective vibrational dynamics and dissociation of isolated diatomic molecules in the electronic ground state under the control of intense and shaped infrared laser pulses of picosecond and femtosecond duration is investigated within the Schrödinger wavefunction formalism. The laser driven dissipative dynamics is investigated within the reduced density matrix formalism beyond and within a Markov-type approximation for the ultrafast state-selective excitation of diatomic molecules, which are coupled to an unobserved quasi-resonant thermal environment. Quantum dynamics in a classical electric field is simulated for a one-dimensional Morse oscillator, representing the local OH bond of the H 2O and HOD molecules in the electronic ground state. Flexible tools of optimal laser control are developed and demonstrated on a picosecond timescale, which enable to localize the population with a very high probability at any prescribed vibrational level of OH, including those close to the dissociation threshold, without substantial dissociation. Comparative analysis of the Markovian and non-Markovian dissipative quantum dynamics reveals that the Markov approximation results in a pronounced decrease of a predicted probability for ultrafast selective preparation of very high vibrational bound states. The laser-controlled dissociation from selectively prepared high vibrational bound states is investigated for a wide range of the laser carrier frequencies, revealing the role of the phase of the dissociating laser pulse. In the limiting case of small laser frequencies, for half-cycle pulses, a spatial squeezing of highly excited molecules is discovered. It is demonstrated that the optimally controlled dissociation may be very efficient, and the dissociation probability may approach the maximal value. Quantum dynamics of vibrationally state-selective association of a diatomic molecule in the electronic ground state controlled by shaped sub-picosecond infrared laser pulse is investigated by means of representative wavepackets. It is shown, in particular, that a colliding pair of O and H atoms can be transferred selectively into a prespecified vibrational bound state of OH(?). Optimal design of the laser field controlling this process results in a high association probability with a very high vibrational state-selectivity.
Surface modification using low energy ground state ion beams
NASA Technical Reports Server (NTRS)
Chutjian, Ara (inventor); Hecht, Michael H. (inventor); Orient, Otto J. (inventor)
1990-01-01
A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.
Ground states of simple bodies that may undergo brittle fractures
NASA Astrophysics Data System (ADS)
Giaquinta, Mariano; Mariano, Paolo Maria; Modica, Giuseppe; Mucci, Domenico
2010-08-01
Equilibrium states of elastic-brittle solids that may suffer nucleation of cracks in finite deformation setting are analyzed. Crack patterns are described in terms of appropriate Radon measures, namely curvature varifolds with boundary. A new form of the energy is presented: it includes terms associated with the curvature of margins and tips of possible cracks. Existence of minima of the energy is established in classes of pairs of deformation and families of varifolds. Configurational balances in weak form are determined with reference to generic curvature varifolds with boundary. They include non-standard terms associated with the curvatures involved in the energy. Pointwise balances of configurational actions are also evaluated in a special case: new pointwise balances at the tips and along the margins of the crack pattern emerge.
Arsenic in ground water of the United States: occurrence and geochemistry
Welch, Alan H.; Westjohn, D.B.; Helsel, Dennis R.; Wanty, Richard B.
2000-01-01
Concentrations of naturally occurring arsenic in ground water vary regionally due to a combination of climate and geology. Although slightly less than half of 30,000 arsenic analyses of ground water in the United States were ? 1 µg/L, about 10% exceeded 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.
Basari?, Nikola; Došli?, Na?a; Ivkovi?, Jakov; Wang, Yu-Hsuan; Mališ, Momir; Wan, Peter
2012-08-20
Irradiation of 2-phenyl-1-naphthol (6) in CH(3) CN/D(2) O (3:1) leads to very efficient incorporation of deuterium at the ortho-positions of the adjacent phenyl ring (overall ?=0.73±0.07), along with minor incorporation at the naphthalene positions 5 and 8. These finding are explained by excited state intramolecular proton transfer (ESIPT) from the phenolic OH group to the corresponding carbon atoms, the main pathway giving rise to quinone methide (QM) 7, which has been characterized by LFP (??20?ns; 460?nm). The ESIPT reaction paths have been explored with the second order approximate coupled cluster (CC2) method. In nonprotic solvents the ESIPT from the naphthol O-H to the ortho-position of the phenyl ring proceeds in a barrierless manner along the (1) L(a) energy surface via a conical intersection with the S(0) state, delivering 7. In aqueous solvent, clusters with H(2) O are formed wherein proton transfer (PT) to solvent and a H(2) O-mediated relay mechanism gives rise to naphtholates and QMs. The results are compared with 2-phenylphenol (3) that also undergoes barrierless ESIPT giving a QM via a conical intersection. However, due to an unfavorable conformation in the ground state, the quantum efficiency for ESIPT of 3 is significantly lower (? for D-exchange=0.041). These results show that ESIPT from phenol to carbon need not be an intrinsically inefficient process. PMID:22782655
Broken vertex symmetry and finite zero-point entropy in the artificial square ice ground state
NASA Astrophysics Data System (ADS)
Gliga, Sebastian; Kákay, Attila; Heyderman, Laura J.; Hertel, Riccardo; Heinonen, Olle G.
2015-08-01
We study degeneracy and entropy in the ground state of artificial square ice. In theoretical models, individual nanomagnets are typically treated as single spins with only two degrees of freedom, leading to a twofold degenerate ground state with intensive entropy and thus no zero-point entropy. Here, we show that the internal degrees of freedom of the nanostructures can result, through edge bending of the magnetization and breaking of local magnetic symmetry at the vertices, in a transition to a highly degenerate ground state with finite zero-point entropy, similar to that of the pyrochlore spin ices. We find that these additional degrees of freedom have observable consequences in the resonant spectrum of the lattice, and predict the occurrence of edge "melting" above a critical temperature at which the magnetic symmetry is restored.
Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet
NASA Astrophysics Data System (ADS)
Fu, Mingxuan; Imai, Takashi; Han, Tian-Heng; Lee, Young S.
2015-11-01
The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility ?kagome, deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of ?kagome that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.
Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet.
Fu, Mingxuan; Imai, Takashi; Han, Tian-Heng; Lee, Young S
2015-11-01
The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility ?(kagome), deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of ?(kagome) that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap. PMID:26542565
Solving condensed-matter ground-state problems by semidefinite relaxations
Thomas Barthel; Robert Hübener
2012-08-07
We present a new generic approach to the condensed-matter ground-state problem which is complementary to variational techniques and works directly in the thermodynamic limit. Relaxing the ground-state problem, we obtain semidefinite programs (SDP). These can be solved efficiently, yielding strict lower bounds to the ground-state energy and approximations to the few-particle Green's functions. As the method is applicable for all particle statistics, it represents in particular a novel route for the study of strongly correlated fermionic and frustrated spin systems in D>1 spatial dimensions. It is demonstrated for the XXZ model and the Hubbard model of spinless fermions. The results are compared against exact solutions, quantum Monte Carlo, and Anderson bounds, showing the competitiveness of the SDP method.
Solving condensed-matter ground-state problems by semidefinite relaxations.
Barthel, Thomas; Hübener, Robert
2012-05-18
We present a generic approach to the condensed-matter ground-state problem which is complementary to variational techniques and works directly in the thermodynamic limit. Relaxing the ground-state problem, we obtain semidefinite programs (SDP). These can be solved efficiently, yielding strict lower bounds to the ground-state energy and approximations to the few-particle Green's functions. As the method is applicable for all particle statistics, it represents, in particular, a novel route for the study of strongly correlated fermionic and frustrated spin systems in D>1 spatial dimensions. It is demonstrated for the XXZ model and the Hubbard model of spinless fermions. The results are compared against exact solutions, quantum Monte Carlo calculations, and Anderson bounds, showing the competitiveness of the SDP method. PMID:23003130
Observation of the Ground State Bands in 109Pd and 111Pd
NASA Astrophysics Data System (ADS)
Stefanova, E. A.; Lalkovski, S.; Korichi, A.; Kutsarova, T.; Lopez-Martens, A.; Xu, F. R.; Liu, H. L.; Kisyov, S.; Minkova, A.; Bazzaco, D.; Bergström, M.; Görgen, A.; Hannachi, F.; Herskind, B.; Hübel, H.; Jansen, A.; Khoo, T. L.; Podolyák, Zs; Schönwasser, G.
2014-09-01
The neutron-rich nuclei 109 Pd and 111Pd were produced as fission fragments following the 30Si + 168Er reaction at a beam energy of 142 MeV. Using the identification based on the coincidences with the complementary fission fragments, the ground state bands in 109Pd and 111Pd were found. They are the only positive-parity bands observed so far in 109Pd and 111 Pd. A band, built on top of the 5/2+ ground state exhibiting ?I = 1 energy-level staggering was observed in each of these nuclei. Both nuclei of interest, 109Pd and 111 Pd, are suggested to lie in the transitional region of Pd isotopes of maximum ?-softness. The ground states of both nuclei are predicted by TRS calculations to be extremely ?-soft with shallow triaxial minima. The first crossing in the new bands is proposed to be due to an alignment of h211/2 neutrons.
Nonadiabatic loading of a Bose-Einstein condensate into the ground state of an optical lattice
NASA Astrophysics Data System (ADS)
Mellish, A. S.; Duffy, G.; McKenzie, C.; Geursen, R.; Wilson, A. C.
2003-11-01
We present a scheme for rapidly loading a Bose-Einstein condensate into a single Bloch state of a weak optical lattice at a quasimomentum of q=?k. Rabi cycling of the Bose-Einstein condensate between momentum states is modified by a phase shift applied to the lattice. By appropriately choosing the magnitude and timing of the phase shift, we demonstrate nearly perfect loading of the lattice ground state, the signature of which is an abrupt halt to the Rabi cycling.
Spin-glass insulating ground state in Y2Os2O7
NASA Astrophysics Data System (ADS)
Zhao, Zhiying; Calder, Stuart; McGuire, Michael; Sales, Brian; Zhou, Haidong; Yan, Jiaqiang
2015-03-01
4 d/5 d transition-metal oxides can display many exotic physical properties due to the interplay between spin-orbit coupling (SOC), Coulomb interaction, crystal field effect, Hund's coupling, and lattice distortion. The magnetic ground state of systems with d4 electronic configuration is under hot debate since the consensus between experiments and theories has not been achieved. A non-magnetic ground state is expected under the Jeff scenario in the presence of SOC. However, various ground states are observed in some d4 systems (such as Ir5+, Os4+, and Ru4+) . In this talk, I will present our study on Y2Os2O7 with nonmagnetic Y3+ at A site which allows us to study the magnetism of Os4+ (d4) sublattice. Polycrystalline Y2Os2O7 was synthesized by solid state reaction and was studied by measuring electrical resistivity, magnetic susceptibility, specific heat, and neutron powder diffraction. A spin-glass insulating ground state is observed in contrast to the long-range magnetic ordered state in Y2Ru2O7.
NASA Technical Reports Server (NTRS)
Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon; DiFilippo, Frank J.
1996-01-01
The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.
Preparing ground states of quantum many-body systems on a quantum computer
NASA Astrophysics Data System (ADS)
Poulin, David
2009-03-01
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.
Nuclear ground-state shapes for nuclei with 16 < A < 280
Moeller, P.; Nix, J.R.
1981-01-01
A new macroscopic-microscopic model based on a Yukawa-plus-exponential macroscopic model and a folded-Yukawa microscopic model with new terms included to account for previously neglected physical effects was used to calculate the nuclear ground-state mass and shape for over 4000 nuclei. The potential energy is plotted versus shape coordinate epsilon/sub 2/ for Na and Sr isotopes (the plot is relative to the spherical macroscopic Yukawa-plus-exponential energy). The effect of a variation of the mass-asymmetry coordinate epsilon/sub 3/ on the ground-state energy is shown for a few heavy nuclei. 3 figures. (RWR)
Ground State of Magnetic Dipoles on a Two-Dimensional Lattice: Structural Phases in Complex Plasmas
Feldmann, J. D.; Kalman, G. J.; Hartmann, P.; Rosenberg, M.
2008-02-29
We study analytically and by molecular dynamics simulations the ground state configuration of a system of magnetic dipoles fixed on a two-dimensional lattice. We find different phases, in close agreement with previous results. Building on this result and on the minimum energy requirement we determine the equilibrium lattice configuration, the magnetic order (ferromagnetic versus antiferromagnetic), and the magnetic polarization direction of a system of charged mesoscopic particles with magnetic dipole moments, in the domain where the strong electrostatic coupling leads to a crystalline ground state. Orders of magnitudes of the parameters of the system relevant to possible future dusty plasma experiments are discussed.
NASA Astrophysics Data System (ADS)
Nieuwenhuizen, Theodorus M.; Liska, Matthew T. P.
2015-10-01
In a recent paper the authors studied numerically the hydrogen ground state in stochastic electrodynamics (SED) within the the non-relativistic approximation. In quantum theory the leading non-relativistic corrections to the ground state energy dominate the Lamb shift related to the photon cloud that should cause the quantum-like behaviour of SED. The present work takes these corrections into account in the numerical modelling. It is found that they have little effect; the self-ionisation that occurs without them remains present. It is speculated that the point-charge approximation for the electron is the cause of the failure.
The permanent dipole moment of LiCs in the ground state
Deiglmayr, J; Repp, M; Dulieu, O; Wester, R; Weidemüller, M
2010-01-01
Recently we demonstrated the formation of ultracold polar LiCs molecules in deeply bound levels of the X1S+ ground state, including the rovibrational ground state [J. Deiglmayr et al., Phys. Rev. Lett. 101, 133004 (2008)]. Here we report on the first experimental determination of the permanent electric dipole moment of deeply bound LiCs molecules. For X1S+,v"=2 and v"=3 we measure values of mu=5.5(2) Debye and 5.3(2) Debye respectively.
Gravitational potential of ground state for three-dimensional spiral galaxies
NASA Astrophysics Data System (ADS)
Tong, Y.; Wu, S.; Peng, Q.
1983-11-01
Density wave theory is used to determine the perturbed gravitational potential of three-dimensional spiral galaxies. The integral form of the gravitational potential for the ground state is derived using the Hankel transformation. A formula for the surface density is obtained by taking Toomre's galaxy rotation model and its corresponding form for projecting surface density modified for the galactic thickness. An analytic solution for the gravitational potential of the ground state for three-dimensional spiral galaxies is deduced and applied to calculate the potential at r = 10 kpc for the Galaxy. The result agrees well with observational data.
Infrared diode laser spectroscopy of the ground state of GeH (X 2?)
NASA Astrophysics Data System (ADS)
Petri, M.; Simon, U.; Zimmermann, W.; Urban, W.; Towle, J. P.; Brown, J. M.
Transitions in the fundamental band of the ground state X 2?1/2 of the GeH radical are detected by tunable diode laser spectroscopy. Signals are observed for all five naturally occurring isotopes of germanium. A preliminary fit of the vibrational-rotational constants for the ground state is given, in which the vibrational corrections ?A, ?? and ?p+2q to the fine structure constant A, the spin rotation constant ? and the lambda doubling constant p + 2q are determined from our data.
Ground-state structure and dynamics in a toy model for granular compaction
NASA Astrophysics Data System (ADS)
Luck, J. M.
2006-04-01
We report on a toy model for the glassy compaction dynamics of granular systems, introduced and investigated in collaboration with Anita Mehta and Peter Stadler. A stochastic dynamics is defined on a column of grains. Grains are anisotropic and possess a discrete orientational degree of freedom. Gravity induces long-range directional interactions down the column. The key control parameter of the model, ?, is a representation of granular shape. Rational and irrational values of ? correspond to very different kinds of behavior, both in statics (structure of ground states) and in low-temperature dynamics (retrieval of ground states).
Model valence-fluctuation systems: variational ground states and magnetic responses
Brandow, B.H.
1980-04-01
Variational ground-state wavefunctions are presented and optimized for two model valence-fluctuation systems, based on Anderson lattice Hamiltonians in the U ..-->.. infinity limit. Although these wavefunctions are approximate, they are treated in an essentially exact manner. The )f/sup 0/, f/sup 1/; n = 1) system has an intuitively reasonable ground-state susceptibility, while the )f/sup 1/, f/sup 2/; n = 2) system is found to exhibit an insulating gap. Due to their different crystal symmetries, this gap should be realized in SmB/sub 6/ but not in SmS.
Ground-state properties of third-row elements with nonlocal density functionals
Bagno, P.; Jepsen, O.; Gunnarsson, O.
1989-07-15
The cohesive energy, the lattice parameter, and the bulk modulus of third-row elements are calculated using the Langreth-Mehl-Hu (LMH), the Perdew-Wang (PW), and the gradient expansion functionals. The PW functional is found to give somewhat better results than the LMH functional and both are found to typically remove half the errors in the local-spin-density (LSD) approximation, while the gradient expansion gives worse results than the local-density approximation. For Fe both the LMH and PW functionals correctly predict a ferromagnetic bcc ground state, while the LSD approximation and the gradient expansion predict a nonmagnetic fcc ground state.
NASA Astrophysics Data System (ADS)
Wu, Y.; Stancil, P. C.; Schultz, D. R.; Hui, Y.; Liebermann, H. P.; Buenker, R. J.
2012-12-01
The charge exchange process has been found to play a dominant role in the production of x-rays and/or extreme ultraviolet photons emitted from cometary and planetary atmospheres and from the heliosphere. Charge exchange cross sections, especially state-selective cross sections, are necessary parameters in simulations of this x-ray emission. In this study, charge exchange, or single-electron capture, due to collisions of ground state O6 +(1s2?1S) with atomic hydrogen has been investigated theoretically using the quantum-mechanical molecular-orbital close-coupling method (QMOCC). The multi-reference single- and double-excitation configuration interaction approach has been applied to compute the adiabatic potentials and nonadiabatic couplings, and the atomic basis sets used have been optimized with a method proposed previously to obtain accurate descriptions of the high-lying Rydberg states of highly charged ions. Total and final-state-selective cross sections are calculated for energies between 0.1 eV/u and 10 keV/u. The QMOCC results are compared to available experimental and theoretical data as well as to new atomic-orbital close-coupling (AOCC) and classical trajectory Monte Carlo (CTMC) calculations. A recommended set of cross sections, based on the QMOCC, AOCC and CTMC calculations, and existing data, are deduced which should aid in x-ray emission modelling studies.
Summary of informal workshop on state of ion beam facilities for atomic physics research
Jones, K.W.; Cocke, C.L.; Datz, S.; Kostroun, V.
1984-11-13
The present state of ion beam facilities for atomic physics research in the United States is assessed by means of a questionnaire and informal workshop. Recommendations for future facilities are given. 3 refs.
Estimation of ground and excited state dipole moments of Oil Red O by solvatochromic shift methods
NASA Astrophysics Data System (ADS)
S?d?r, ?sa; Gülseven S?d?r, Yadigar
2015-01-01
Absorption and fluorescence spectra of Oil Red O (abbreviated as ORO) are recorded in various solvents with different polarity in the range of 250-900 nm, at room temperature. The solvatochromic shift methods have been used to determine the ground state (?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.
Quantum Monte Carlo study of the ground state and low-lying excited states of the scandium dimer.
Matxain, Jon M; Rezabal, Elixabete; Lopez, Xabier; Ugalde, Jesus M; Gagliardi, Laura
2008-05-21
A large set of electronic states of scandium dimer has been calculated using high-level theoretical methods such as quantum diffusion Monte Carlo (DMC), complete active space perturbation theory as implemented in GAMESS-US, coupled-cluster singles, doubles, and triples, and density functional theory (DFT). The 3 Sigma u and 5 Sigma u states are calculated to be close in energy in all cases, but whereas DFT predicts the 5 Sigma u state to be the ground state by 0.08 eV, DMC and CASPT2 calculations predict the 3 Sigma u to be more stable by 0.17 and 0.16 eV, respectively. The experimental data available are in agreement with the calculated frequencies and dissociation energies of both states, and therefore we conclude that the correct ground state of scandium dimer is the 3 Sigma u state, which breaks with the assumption of a 5 Sigma u ground state for scandium dimer, believed throughout the past decades. PMID:18500873
Bao, Weizhu; Chern, I-Liang; Department of Mathematics, National Taiwan University, Taipei 10617, Taiwan ; Zhang, Yanzhi
2013-11-15
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.
Seif, W M; Refaie, A I
2015-01-01
The ground-state spin and parity of a formed daughter in the radioactive Alpha-emitter is expected to influence the preformation probability of the Alpha and daughter clusters inside it. We investigate the Alpha and daughter preformation probability inside odd-A and doubly-odd radioactive nuclei when the daughter and parent are of different spin and/or parity. We consider only the ground-state to ground-state unfavored decays. This is to extract precise information about the effect of the difference in the ground states spin-parity of the involved nuclei far away any influences from the excitation energy if the decays are coming from isomeric states. The calculations are done for 161 Alpha-emitters, with Z=65-112 and N=84-173, in the framework of the extended cluster model, with WKB penetrability and assault frequency. We used a Hamiltonian energy density scheme based on Skyrme-SLy4 interaction to compute the interaction potential. The Alpha plus cluster preformation probability is extracted from the calculat...
A projection gradient method for computing ground state of spin-2 Bose–Einstein condensates
Wang, Hanquan
2014-10-01
In this paper, a projection gradient method is presented for computing ground state of spin-2 Bose–Einstein condensates (BEC). We first propose the general projection gradient method for solving energy functional minimization problem under multiple constraints, in which the energy functional takes real functions as independent variables. We next extend the method to solve a similar problem, where the energy functional now takes complex functions as independent variables. We finally employ the method into finding the ground state of spin-2 BEC. The key of our method is: by constructing continuous gradient flows (CGFs), the ground state of spin-2 BEC can be computed as the steady state solution of such CGFs. We discretized the CGFs by a conservative finite difference method along with a proper way to deal with the nonlinear terms. We show that the numerical discretization is normalization and magnetization conservative and energy diminishing. Numerical results of the ground state and their energy of spin-2 BEC are reported to demonstrate the effectiveness of the numerical method.
Calculated ground state potential surface and excitation energies for the copper trimer
NASA Technical Reports Server (NTRS)
Walch, S. P.; Laskowski, B. C.
1986-01-01
In the context of their relevance to catalysis and to materials science problems, transition metals and transition metal (TM) compounds are currently of considerable interest, and studies have been conducted of the copper trimer, Cu3. The present investigation is concerned with a study of the ground state surface and several groups of excited states in order to improve the understanding of the spectroscopy of Cu3. Differences of the current study from previous investigations are related to an employment of larger basis sets and a more extensive electron correlation. This was done with the objective to obtain a more accurate definition of the ground state surface. Features of the bonding in the copper dimer are considered to obtain a basis for an understanding of the copper trimer. Attention is given to calculational details, the ground state surface, and calculated vertical excitation energies. The results of SCF/SDCI calculations are reported for portions of the ground surface, for two groups of excited states, and for the ionization potential of Cu3.
Unitary photoassociation: One-step production of ground-state bound molecules
Kallush, S.; Kosloff, R.
2008-02-15
Bound-state molecules can be photoassociated directly from ultracold free-atom pairs by excitation to a purely repulsive electronic state. The process is explained on the basis of quantum unitarity: the initially free-scattering state is transformed by an impulsive light pulse to a deformed superposition which contains bound-state components. For pulse durations which are short compared to the ultracold dynamics, the maximal rate of photoassociation was found to be determined by the initial stationary distribution of scattering states of the atom pairs. The process was simulated for an ultracold gas of {sup 87}Rb with a temperature of T=44 {mu}K and a density of {approx_equal}10{sup 11} cm{sup -3}. Transform-limited pulses maximize the photoassociation, yielding {approx}1 bound molecule per pulse. Coherent control calculated by a local control scheme can increase the photoassociation yield by two orders of magnitude.
Dynamic polarizabilities and related properties of clock states of the ytterbium atom
NASA Astrophysics Data System (ADS)
Dzuba, V. A.; Derevianko, A.
2010-04-01
We carry out relativistic many-body calculations of the static and dynamic dipole polarizabilities of the ground 6s2 1S0 and the first excited 6s6p 3Po0 states of Yb. With these polarizabilities, we compute several properties of Yb relevant to optical lattice clocks operating on the 6s2 1S0-6s6p 3Po0 transition. We determine (i) the first four magic wavelengths of the laser field for which the frequency of the clock transition is insensitive to the laser intensity. While the first magic wavelength is known, we predict the second, the third and the fourth magic wavelengths to be 551 nm, 465 nm and 413 nm. (ii) We re-evaluate the effect of black-body radiation on the frequency of the clock transition, the resulting clock shift at T = 300 K being -1.41(17) Hz. (iii) We compute long-range interatomic van der Waals coefficients (in a.u.) C6(6s2 1S0 + 6s2 1S0) = 1909(160), C6(6s2 1S0 + 6s6p 3P0) = 2709(338) and C6(6s6p 3P0 + 6s6p 3P0) = 3886(360). Finally, we determine the atom-wall interaction coefficients (in a.u.), C3(6s2 1S0) = 3.34 and C3(6s6p 3P0) = 3.68. We also address and resolve a disagreement between previous calculations of the static polarizability of the ground state.
Rayleigh approximation to ground state of the Bose and Coulomb glasses
Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.
2015-01-01
Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Our findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties. PMID:25592417
Rayleigh approximation to ground state of the Bose and Coulomb glasses
Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.
2015-01-16
Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Our findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties.
Bibliography on ground water in glacial-aquifer systems in the Northeastern United States
Wiltshire, Denise A.; Lyford, Forest P.; Cohen, A.J.
1986-01-01
The U.S. Geological Survey established the Regional Aquifer-System Analysis (RASA) program to evaluate major interconnected aquifers or groups of aquifers that share similar characteristics within a region. One of the objectives of the Northeastern Glacial RASA is to provide information on the occurrence and quality of ground water in glacial deposits in ten States: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, Ohio, Pennsylvania, and New Jersey. To help meet the objectives of the RASA program, an automated bibliographic data base was developed. The data base contains references to ground-water resources of glacial-aquifer systems in the ten States listed above. This bibliography contains more than 700 ground-water related references that date from 1839 through 1984. The bibliography lists books, journal articles, conference proceedings, government and other technical reports, theses, and maps. Unpublished manuscripts, publications in press, newspaper articles, and book reviews are omitted from the bibliography.
Rayleigh approximation to ground state of the Bose and Coulomb glasses
Ryan, S. D.; Mityushev, V.; Vinokur, V. M.; Berlyand, L.
2015-01-16
Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature and properties of which are still far from being thoroughly understood. We report an analytical approach based on the method of functional equations that allows us to construct the Rayleigh approximation to the ground state of a two-dimensional (2D) random Coulomb system with logarithmic interactions. We realize a model for 2D Coulomb glass as a cylindrical type II superconductor containing randomly located columnar defects (CD) which trap superconducting vortices induced by applied magnetic field. Ourmore »findings break ground for analytical studies of glassy systems, marking an important step towards understanding their properties.« less
Resetting Transcription Factor Control Circuitry toward Ground-State Pluripotency in Human
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
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
Pregalactic Black Hole Formation with an Atomic Hydrogen Equation of State
Marco Spaans; Joseph Silk
2006-08-16
The polytropic equation of state of an atomic hydrogen gas is examined for primordial halos with baryonic masses of M_h~10^7-10^9 Mo. For roughly isothermal collapse around 10^4 K, we find that line trapping of Lyman alpha (HI and HeII) photons causes the polytropic exponent to stiffen to values significantly above unity. Under the assumptions of zero H2 abundance and very modest pollution by metals (<10^-4 Solar), fragmentation is likely to be inhibited for such an equation of state. We argue on purely thermodynamic grounds that a single black hole of ~0.02-0.003M_h can form at the center of a halo for z=10-20 when the free-fall time is less than the time needed for a resonantly scattered Lyman alpha photon to escape from the halo. The absence of H2 follows naturally from the high, 10^4 K, temperatures that are attained when Lyman alpha photons are trapped in the dense and massive halos that we consider. An H2 dissociating UV background is needed if positive feedback effects on H2 formation from X-rays occur. The black hole to baryon mass fraction is suggestively close to what is required for these intermediate mass black holes, of mass M_BH~10^4-10^6 Mo, to act as seeds for forming the supermassive black holes of mass ~0.001M_spheroid found in galaxies today.
The laboratory millimeter-wave spectrum of methyl formate in its ground torsional E state
NASA Technical Reports Server (NTRS)
Plummer, G. M.; Herbst, E.; De Lucia, F. C.; Blake, G. A.
1986-01-01
Over 250 rotational transitions of the internal rotor methyl formate (HCOOCH3) in its ground v(t) = 0 degenerate (E) torsional substate have been measured in the millimeter-wave spectral region. These data and a number of E-state lines identified by several other workers have been analyzed using an extension of the classical principal-axis method in the high barrier limit. The resulting rotational constants allow accurate prediction of the v(t) = 0 E substate methyl formate spectrum below 300 GHz between states with angular momentum J not greater than 30 and rotational energy of not more than 350/cm. The calculated transition frequencies for the E state, when combined with the results of the previous analysis of the ground-symmetric, nondegenerate state, account for over 200 of the emission lines observed toward Orion in a recent survey of the 215-265 GHz band.
Optomechanical sideband cooling of a micromechanical oscillator close to the quantum ground state
Remi Riviere; Samuel Deleglise; Stefan Weis; Emanuel Gavartin; Olivier Arcizet; Albert Schliesser; Tobias J. Kippenberg
2010-11-01
Cooling a mesoscopic mechanical oscillator to its quantum ground state is elementary for the preparation and control of low entropy quantum states of large scale objects. Here, we pre-cool a 70-MHz micromechanical silica oscillator to an occupancy below 200 quanta by thermalizing it with a 600-mK cold 3He gas. Two-level system induced damping via structural defect states is shown to be strongly reduced, and simultaneously serves as novel thermometry method to independently quantify excess heating due to the cooling laser. We demonstrate that dynamical backaction sideband cooling can reduce the average occupancy to 9+-1 quanta, implying that the mechanical oscillator can be found (10+- 1)% of the time in its quantum ground state.
Ground states of the Wick-Cutkosky model using light-front dynamics
Jason R. Cooke; Gerald A. Miller
2000-03-17
We consider the ground state in a model with scalar nucleons and a meson using the formalism of light-front dynamics. Light-front potentials for two-nucleon bound states are calculated using two approaches. First, light-front time-ordered perturbation theory is used to calculate one- and two-meson-exchange potentials. These potentials give results that agree well with the ladder and ladder plus crossed box Bethe-Salpeter spectra. Secondly, approximations that incorporate non-perturbative physics are used to calculate alternative one-meson-exchange potentials. These non-perturbative potentials give better agreement with the spectra of the full non-perturbative ground-state calculation than the perturbative potentials. For lightly-bound states, all of the approaches appear to agree with each other.
NASA Astrophysics Data System (ADS)
Schwartz, Sylvain; Dupont-Nivet, Matthieu; Westbrook, Chris
2015-05-01
Microwave-stimulated Raman adiabatic passage (STIRAP) between internal states of a Bose-Einstein condensate (BEC) magnetically trapped in the vicinity of an atom chip is demonstrated by coherently transferring about 90 percent of a 7.000-atom BEC initially in the (F = 2, mF = 2) hyperfine level of the 5 2S1 / 2 ground state of 87Rb into (F = 2, mF = 1), using (F = 1, mF = 1) as an intermediate (unpopulated) level. The STIRAP protocol used in this experiment is robust to external perturbations as it is an adiabatic transfer, and power efficient as it involves only resonant (or quasi-resonant) processes. Taking into account the effect of losses and collisions in a Bloch equations model, we show that the maximum transfer efficiency is obtained for significantly non-zero values of the one- and two-photon detunings, which is confirmed quantitatively by our experimental measurements (and is shown to come mostly from inelastic collisions within (F = 2, mF = 1)). This work shows that microwave STIRAP between hyperfine ground states of magnetically trapped atoms is feasible, paving the way for STIRAP-based quantum information or metrology experiments integrated on a chip.
NASA Astrophysics Data System (ADS)
Yoshida, Yasuo; Schroeder, Silke; Ferriani, Paolo; Serrate, David; von Bergmann, Kirsten; Kubetzka, Andre; Heinze, Stefan; Wiesendanger, Roland
2012-02-01
The magnetic properties of transition-metal nanostructures are commonly explained based on the interplay of Heisenberg exchange, Dzyaloshinskii-Moriya (DM) interaction and magnetocrystalline anisotropy while higher order terms such as the biquadratic exchange and the four-spin interaction are typically neglected due to their small strength. Here, we demonstrate that higher-order terms can play a crucial role for the magnetic ground state and report as an example a transverse conical spin-spiral state in an ultra-thin film composed of two atomic layers of Mn on W(110). This spin structure is characterized by magnetic moments rotating on a cone that is perpendicular to the [001] propagation direction of the spin-spiral with a periodicity of 2.4 nm. The cones of nearest-neighbor Mn atoms point into opposite directions which results in nearly antiferromagnetic alignment. This intriguing spin structure has been resolved on the atomic-scale using spin-polarized scanning tunneling microscopy and confirmed to be the ground state by first-principles calculations based on DFT. Our calculations also reveal that the canting of the spins is induced by higher-order exchange interactions while the spiraling along the [001]-direction is due to frustrated Heisenberg exchange and DM interaction.
Prevalence and Characterization of Salmonellae in Commercial Ground Beef in the United States
Technology Transfer Automated Retrieval System (TEKTRAN)
Commercially produced ground beef samples (n = 4,136) were collected from seven regions of the United States over a 24 month period (July 2005 to June 2007) and analyzed for the presence of Salmonella using methods to examine enumerable levels and total prevalence. All Salmonella isolated were sero...
Searching for Ground States of Ising Spin Glasses with Hierarchical BOA and Cluster
Hartmann, Alexander K.
1 Searching for Ground States of Ising Spin Glasses with Hierarchical BOA and Cluster Exact@physik.uniÂgoettingen.de Summary. This chapter applies the hierarchical Bayesian optimization algorithm (hBOA) to the problem. The performance of hBOA is comÂ pared to that of the simple genetic algorithm (GA) and the univariate marginal
First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo
Anderson, James B.
First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo Arne Lu. The dissociation energies De have been calculated with accuracies of 0.5 kcal mol 1 or better. For all hydrides, the dissociation energies are consistent with experimental values. The fixed-node quantum Monte Carlo method can
Ground State D, Dissociation Energy from the Near-dissociation Behaviorof Rotational Level Spacings1
Le Roy, Robert J.
Ground 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 lying near dissociation is derived and tested. It is based on expressions relating the characteristic
Scaling of the giant dipole resonance widths in hot rotating nuclei from the ground state values
Bhattacharya, Srijit; Pandit, Deepak; Mukhopadhyay, S.; Pal, Surajit; Banerjee, S. R.
2008-12-15
The systematics of the giant dipole resonance (GDR) widths in hot and rotating nuclei are studied in terms of temperature T, angular momentum J, and mass A. The different experimental data in the temperature range of 1-2 MeV have been compared with the thermal shape fluctuation model (TSFM) in the liquid drop formalism using a modified approach to estimate the average values of T, J, and A in the decay of the compound nucleus. The values of the ground state GDR widths have been extracted from the TSFM parametrization in the liquid drop limit for the corrected T, J, and A for a given system and compared with the corresponding available systematics of the experimentally measured ground state GDR widths for a range of nuclei from A=45 to 194. Amazingly, the nature of the theoretically extracted ground state GDR widths matches remarkably well, though 1.5 times smaller, with the experimentally measured ground state GDR widths consistently over a wide range of nuclei.
Ground states of 2d J Ising spin glasses via stationary FokkerPlanck sampling
Peinke, Joachim
optimization, called stationary FokkerPlanck (SFP) sampling [11, 12]. The basic idea is to perform a Langevin for the probability density of the variables of the cost function. Related to this, SFP sampling aims to estimate of a stationary probability density by the SFP algorithm was illustrated #12; Ground states of 2d ±J Ising spin
Ground-state properties of microcavity polariton condensates at arbitrary excitation density
Kamide, Kenji; Ogawa, Tetsuo
2011-04-15
The ground state of microcavity polariton Bose-Einstein condensates (BEC's) is determined as a function of experimentally tunable parameters (the excitation density and the detuning of cavity photons), and also a material parameter (the ultraviolet cutoff). To obtain the ground state at an arbitrary excitation density, an interpolation method for the BEC-BCS crossover of excitonic insulators is extended to microcavity polariton systems in two or three dimensions. The ground state of the condensate changes from excitonic to photonic with an increase in the excitation density. This change is accompanied by several interesting features: (i) A laserlike input (excitation density) and output (photon density) relation with a sharp onset for largely detuned systems, which changes to that with a smooth onset for slightly detuned systems. (ii) The origin of the binding force of electron-hole pairs changes from Coulomb attraction to photon-mediated interactions, resulting in the formation of strongly bound pairs with a small radius, such as Frenkel excitons, in the photonic regime. The change in the ground state can be a crossover or a first-order transition, depending on the above-mentioned parameters, and is studied by plotting phase diagrams.
A polynomial time algorithm for the ground state of one-dimensional gapped local Hamiltonians
NASA Astrophysics Data System (ADS)
Landau, Zeph; Vazirani, Umesh; Vidick, Thomas
2015-07-01
The density matrix renormalization group method has been extensively used to study the ground state of 1D many-body systems since its introduction two decades ago. In spite of its wide use, this heuristic method is known to fail in certain cases and no certifiably correct implementation is known, leaving researchers faced with an ever-growing toolbox of heuristics, none of which is guaranteed to succeed. Here we develop a polynomial time algorithm that provably finds the ground state of any 1D quantum system described by a gapped local Hamiltonian with constant ground-state energy. The algorithm is based on a framework that combines recently discovered structural features of gapped 1D systems with an efficient construction of a class of operators called approximate ground-state projections (AGSPs). The combination of these tools yields a method that is guaranteed to succeed in all 1D gapped systems. An AGSP-centric approach may help guide the search for algorithms for more general quantum systems, including for the central challenge of 2D systems, where even heuristic methods have had more limited success.
Ground State of the Massless Nelson Model in a non-Fock Representation
/2 ^ Dom( -1/2 m ) and a(k) , a(k) are the distribution kernels of the creation and annihilation operators is a quantum mechanical model which describes an interaction between some quantum mechanical particles on Fb(L2 (R3 )) (Dom(A) means the domain of operator A). The problem on the ground state of HV m can
could represent a conserved ground state of ab-tubulin. Together, these observations add further
Dworkin, Ian
could represent a conserved ground state of ab- tubulin. Together, these observations add further conformations (17). The regions of curved ab-tubulin that engage TOG1 move relative to each other in the transi- tion to the straight conformation (Fig. 4A). Thus, TOG1:ab-tubulin interactions might be sensitive
Anharmonic Ground state selection in the pyrochlore antiferromagnet and C. L. Henley
Henley, Christopher L.
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
Ground state properties of a fully frustrated quantum spin system Elliott H. Lieb and Peter Schupp
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
Ground States of the Classical Antiferromagnet on the Pyrochlore Lattice Matthew F. Lapa1,2
Henley, Christopher L.
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
Theoretical Study on the Reaction of Ground State Cyano Radical with Propylene in Titan's Atmosphere
Kaiser, Ralf I.
Theoretical Study on the Reaction of Ground State Cyano Radical with Propylene in Titan in cold molecular clouds and in the atmosphere of Saturn's satellite Titan. I. Introduction For the last two decades, the atmospheric composition and chemical processing of Saturn's largest satellite, Titan
N'eel Order in the Ground State of Spin1/2 Heisenberg
N'eel Order in the Ground State of SpinÂ1/2 Heisenberg Antiferromagnetic Multilayer Systems J.O. Box 66318 05389Â970 S~ao Paulo Brazil July, 1996 Abstract We show existence of N'eel order by CAPES. y Supported by FAPESP. z Partially supported by CNPq. 1 #12; 1 Introduction The existence of N'eel