These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Rydberg States of rb and cs Atoms on Helium Nanodroplets: a Rydberg-Ritz Analysis  

NASA Astrophysics Data System (ADS)

Rydberg series of Rb and Cs atoms on the surface of helium nanodroplets (He_{N}) have been studied by resonance enhanced multi-photon ionization spectroscopy and laser induced fluorescence spectroscopy. The recorded excitation spectra are analyzed by using a Rydberg-Ritz approach. The dependence of the quantum defects on the principal quantum number within a Rydberg series gives insight into the interaction between the alkali atom's valence electron and the superfluid helium droplet. For higher excited states a screening of the valence electron from the alkali atom core by the helium droplet is observed. For lower states the strength of the screening effect decreases and the quantum defects are found to lie closer to free atom values. In addition, the large spin-orbit (SO) constant of the Cs-He_{N} nP(^{2}?) states allows a detailed study of the influence of the helium droplet on the SO splitting as function of the principal quantum number. Within the pseudo-diatomic picture the alkali-He_{N} system represents a diatomic molecule. The coupling of the Cs valence electrons spin and the orbital angular momentum with the intermolecular axis, which is defined by the connection between the droplet center and the alkali nucleus, depends on the strength of the atomic SO interaction. While the splitting of the 6^{2}P_{1/2}(^{2}?_{1/2}) and 6^{2}P_{3/2}(^{2}?_{3/2}) components has an atom-like character (Hund's case (c) coupling), the SO splitting of higher n states is lower than the atomic value (Hund's case (a) coupling). C. Callegari and W. E. Ernst, Helium Droplets as Nanocryostats for Molecular Spectroscopy - from the Vacuum Ultraviolet to the Microwave Regime, in: Handbook of High-Resolution Spectroscopy, eds. M. Quack and F. Merkt, John Wiley & Sons, Chichester, (2011) F. Lackner, G. Krois, M. Theisen, M. Koch, and W.E. Ernst, Phys. Chem. Chem. Phys., 13, 18781-18788 (2011) F. Lackner, G. Krois, and W.E. Ernst, J. Phys. Chem. Lett., 3, 1404-1408 (2012)

Lackner, Florian; Krois, Gunter; Ernst, Wolfgang E.

2013-06-01

2

Rydberg and autoionizing triplet states in Helium up to the N = 5 threshold  

SciTech Connect

Energy levels of highly excited bound Rydberg states, the position and widths of autoionizing states, and oscillator strengths are calculated for He {sup 3}S, {sup 3}P{sup e}, {sup 3}P{sup o}, {sup 3}D{sup e} and {sup 3}D{sup o} symmetries up to the N = 5 He{sup +} excitation threshold. The calculations are performed with the K-matrix B-spline method with maximum orbital angular momentum l{sub max} = 8. Reliable doubly excited-state parameters up to the n = 20 multiplet below each ionization threshold are presented. One thousand and six hundred newly identified bound and metastable states, seven times those available in literature, fill many gaps, reveal a dozen intruder states, and allow new speculations on propensity rules and radiative decays of triplet Rydberg states.

Argenti, L. [DICASM, Universita di Bologna, via Saragozza 8, I-40136 Bologna (Italy)], E-mail: luca.argenti@gmail.com

2008-11-15

3

Rubidium Atoms on Helium Droplets: Analysis of AN Exotic Rydberg Complex  

NASA Astrophysics Data System (ADS)

Rubidium atoms on the surface of superfluid helium droplets have been excited into Rydberg states. The excitation spectrum of the Rb-He_N system has been recorded from the 5^2D state manifold up to the ionization threshold by resonant three-photon-ionization time-of-flight spectroscopy. The observation of droplet size dependent shifts of excited states with respect to bare atom states is explained by a decreased quantum defect and a lowered ionization threshold. Within the scope of a Rydberg model we demonstrate that quantum defects and ionization thresholds are constant for each specific Rydberg series, which confirms the Rydberg character of excited Rubidium states on helium droplets. A set of six Rydberg series could be identified. Individual Rydberg states are observed with effective principle quantum numbers up to n* ? 19 and l ? 3, for which the expectation value of the electron orbital radius is about ten times larger than the droplet radius. M. Theisen, F. Lackner, G. Krois, and W.E. Ernst, J. Phys. Chem. Lett., 2, 2778-2782 (2011) F. Lackner, G. Krois, M. Theisen, M. Koch, and W.E. Ernst, Phys. Chem. Chem. Phys., 13, 18781-18788 (2011) J.E. Murphy, J.M. Berg, A.J. Merer, N.A. Harris, and R.W. Field, Phys. Rev. Lett. 65, 1861 (1990)

Lackner, Florian; Krois, Günter; Koch, Markus; Ernst, Wolfgang E.

2012-06-01

4

Rydberg state creation by tunnel ionization  

NASA Astrophysics Data System (ADS)

It is well known from numerical and experimental results that the fraction of Rydberg states (excited neutral atoms) created by tunnel ionization declines dramatically with increasing ellipticity of laser light, in a way that is similar to high harmonic generation (HHG). We present a method to analyze this dependence on ellipticity, deriving a probability distribution of Rydberg states that agrees closely with experimental (Nubbemeyer et al 2008 Phys. Rev. Lett. 101 233001) and numerical results. We show using analysis and numerics that most Rydberg electrons are ionized before the peak of the electric field and therefore do not come back to the parent ion. Our work shows, for the first time, the similarities and differences in the process that distinguishes formation of Rydberg electrons from electrons involved in HHG: ionization occurs in a different part of the laser cycle, but the post-ionization dynamics are very similar in both cases, explaining why the same dependence on ellipticity is observed.

Landsman, A. S.; Pfeiffer, A. N.; Hofmann, C.; Smolarski, M.; Cirelli, C.; Keller, U.

2013-01-01

5

Insight into the Rydberg states of CH  

NASA Astrophysics Data System (ADS)

Ab initio electronic structure calculations of a relatively large number of Rydberg states of the CH radical were carried out employing the multireference single and double excitation configuration interaction (MRD-CI) method. A Gaussian basis set of cc-pV5Z quality augmented with 12 diffuse functions was used together with an extensive treatment of electron correlation. The main focus of this contribution is to investigate the 3d Rydberg complex assigned by Watson [Astrophys. J. 555, 472 (2001)] to three unidentified interstellar bands. The authors' calculations reproduce quite well the absolute excitation energies of the three components of the 3d complex, i.e., ?+2(3d?), ?2(3d?), and ?2(3d?), but not the energy ordering inferred from a rotational assignment of the 3d?X?2 laboratory spectrum. The computation of the 4d complex is reported for the first time along with a number of other higher lying Rydberg species with an X?+1 core. The lowest Rydberg states belonging to series converging to the a?3 and A?1 excited states of CH+ are also calculated.

Vázquez, G. J.; Amero, J. M.; Liebermann, H. P.; Buenker, R. J.; Lefebvre-Brion, H.

2007-04-01

6

Excitation of helium Rydberg states and doubly excited resonances in strong extreme ultraviolet fields: Full-dimensional quantum dynamics using exponentially tempered Gaussian basis sets  

SciTech Connect

Recently optimized exponentially tempered Gaussian basis sets [P. R. Kapralova-Zdanska and J. Smydke, J. Chem. Phys. 138, 024105 (2013)] are employed in quantitative simulations of helium absorption cross-sections and two-photon excitation yields of doubly excited resonances. Linearly polarized half-infinite and Gaussian laser pulses at wavelengths 38–58 nm and large intensities up to 100 TW/cm{sup 2} are considered. The emphasis is laid on convergence of the results with respect to the quality of the Gaussian basis sets (typically limited by a number of partial waves, density, and spatial extent of the basis functions) as well as to the quality of the basis set of field-free states (typically limited by the maximum rotational quantum number and maximum excitation of the lower electron). Particular attention is paid to stability of the results with respect to varying complex scaling parameter. Moreover, the study of the dynamics is preceded by a thorough check of helium energies and oscillator strengths as they are obtained with the exponentially tempered Gaussian basis sets, being also compared with yet unpublished emission wavelengths measured in electric discharge experiments.

Kaprálová-Ž?ánská, Petra Ruth; Šmydke, Jan [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8 (Czech Republic) [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8 (Czech Republic); Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Civiš, Svatopluk [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8 (Czech Republic)] [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8 (Czech Republic)

2013-09-14

7

Chirped pulse excitation of two-atom Rydberg states  

E-print Network

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

Kuznetsova, Elena

2015-01-01

8

Atomic Fock State Preparation Using Rydberg Blockade  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

9

Rydberg States of Atoms and Molecules  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

10

Cold Rydberg atoms in circular states  

NASA Astrophysics Data System (ADS)

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

Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

2012-06-01

11

Lifetimes of Rydberg states of Eu atoms  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

12

Rydberg Spectroscopy of Zeeman-Decelerated Beams of Metastable Helium Molecules  

NASA Astrophysics Data System (ADS)

Having three and four electrons, respectively, He_2^+ and He_2 represent systems for which highly accurate ab-initio calculations might become feasible in the near future. With the goal of performing accurate measurements of the rovibrational energy-level structure of He_2^+ by Rydberg spectroscopy of He_2 and multichannel quantum-defect theory extrapolation techniques, we have produced samples of helium molecules in the a ^3?u^+ state in supersonic beams with velocities tunable down to 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. The molecules are formed at an initial velocity of 500 m/s by striking a discharge in the pulsed expansion of helium gas from a reservoir kept at a cryogenic temperature of 10 K. Using rotationally-resolved PFI-ZEKE (pulsed-field-ionization zero-kinetic-energy) photoelectron spectroscopy, we have probed the rotational-state distribution of the molecules produced in the discharge and found vibrational levels up to ?" = 2 and rotational levels up to N"=21 to be populated. The molecular beam is coupled to a multistage Zeeman decelerator that employs pulsed inhomogeneous magnetic fields to further reduce the beam velocity. By measuring the quantum-state distribution of the decelerated sample using photoelectron and photoionization spectroscopy we observed no rotational or vibrational state-selectivity of the deceleration process, but found that one of the three spin-rotation components of the He_2 a ^3?u^+ rotational levels is eliminated. W.-C. Tung, M. Pavanello, L. Adamowicz, J. Chem. Phys. 136, 104309 (2012). D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys. 140, 064304 (2014). M. Motsch, P. Jansen, J. A. Agner, H. Schmutz, and F. Merkt, arXiv:1401.7774. N. Vanhaecke, U. Meier, M. Andrist, B. H. Meier, and F. Merkt, Phys. Rev. A 75, 031402(R) (2007).

Jansen, Paul; Motsch, Michael; Sprecher, Daniel; Merkt, Frederic

2014-06-01

13

Applications of molecular Rydberg states in chemical dynamics and spectroscopy  

NASA Astrophysics Data System (ADS)

Molecules in high Rydberg states, in which one electron has been excited into a hydrogenic orbital of large mean radius, have many unusual properties compared to ground state molecules. These properties, which are reviewed in this article, make them suitable for a diverse and growing number of applications in chemical dynamics. The most recent methods for studying molecular Rydberg states using high-resolution spectroscopy and theory, including effects of electric fields, are described here. An important feature is the high susceptibility of Rydberg states to external field perturbation which not only has a profound effect on the observable energy levels, spectroscopic intensities and lifetimes, but is also useful for state-selective detection through field ionization. The large dipole moment that can be created in a field is also useful for controlling the motion of molecules in Rydberg states. The applications reviewed here include: ZEKE (zero kinetic energy), MATI (mass-analyzed threshold ionization) and PIRI (photo-induced Rydberg ionization) spectroscopy; pulsed-field recombination of ions and electrons; the state selection and reaction of molecular ions; collisions of Rydberg states with neutrals, ions and metallic surfaces; Rydberg tagging and imaging of products of photodissociation; and the control of translational motion and orientation via the use of inhomogeneous fields.

Softley, T. P.

14

Low Energy Rydberg States in Dipositronium  

NASA Astrophysics Data System (ADS)

Previously the possible resonances in positronium hydride, PsH, [1] were studied, assuming a positronium ion, Ps^-, interacting with a proton, H^+, as the prime configuration. This study will look at the first resonances of dipositonium, Ps2, in a similar manner. In this situation a variational method is used to determine the radial function of the bound state. First, the model system consisting of Ps^- and a positron, e^+is investigated by including electron exchange but no positron exchange. Then the antisymmetrization of the two positrons is considered giving rise to a non-local potential. The full symmetrization of a system such as Ps2 involves not only exchanging electrons and exchanging positrons, but also the charge conjugation of the two interacting ions in our model. Thus, in this second approach we construct a wave function that includes representations of both the Ps^- + e^+ and Ps^+ + e^- channels to provide a complete description of this resonant system. From the calculations, the lowest energy singlet Rydberg resonant states are determined. A comparison will be made with results using group-theory analysis [2]. [1] J. Di Rienzi, R. J. Drachman, Phys. Rev. A 76, 032705 (2007). [2] J. Usukura and Y. Suzuki, Phys. Rev. A 66, 010502(R) (2002); C. G. Bao and T. Y. Shu, Phys. Rev. A 67, 042505 (2003).

Dirienzi, Joseph; Drachman, Richard

2009-05-01

15

Xenon low-n Rydberg states in supercritical argon near the critical point  

E-print Network

Xenon low-n Rydberg states in supercritical argon near the critical point Luxi Li a,b , Xianbo Shi simulation of the 6s and 6s Rydberg states (including the blue satellite bands) of xenon doped into argon

Findley, Gary L.

16

Coherent excitation of a single atom to a Rydberg state  

SciTech Connect

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

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

2010-07-15

17

Efficient excitation of Rydberg states in ultracold lithium-7 atoms  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

18

Simultaneous position and state measurement of Rydberg atoms  

E-print Network

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

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

2007-05-22

19

Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide  

E-print Network

The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity of a solid-state co-planar waveguide is reported. Rydberg-Rydberg transitions, at frequencies between 25 GHz and 38 GHz, have been studied for states with principal quantum numbers in the range 30 - 35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used to reduce effects of blackbody radiation. Inhomogeneous, stray electric fields emanating from the surface of the waveguide have been characterized in frequency- and time-resolved measurements and coherence times of the Rydberg atoms on the order of 250 ns have been determined.

Hogan, S D; Merkt, F; Thiele, T; Filipp, S; Wallraff, A

2011-01-01

20

Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide  

E-print Network

The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity of a solid-state co-planar waveguide is reported. Rydberg-Rydberg transitions, at frequencies between 25 GHz and 38 GHz, have been studied for states with principal quantum numbers in the range 30 - 35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used to reduce effects of blackbody radiation. Inhomogeneous, stray electric fields emanating from the surface of the waveguide have been characterized in frequency- and time-resolved measurements and coherence times of the Rydberg atoms on the order of 250 ns have been determined.

S. D. Hogan; J. A. Agner; F. Merkt; T. Thiele; S. Filipp; A. Wallraff

2011-10-06

21

Deexcitation of high-Rydberg-state atoms with a chirped train of half-cycle pulses  

Microsoft Academic Search

Encouraged by the experiments on production of antihydrogen atoms in high Rydberg states we have calculated the effect of deexcitation towards lower states by a chirped train of identical unidirectional half-cycle pulses. The calculations exploit both the one-dimensional and impulse approximations providing convenient analytical formulas for the Rydberg-to-Rydberg transition amplitudes. The calculated deexcitation is shown in terms of the mean

T. Kopyciuk; R. Parzynski

2007-01-01

22

Probing dissociative electron attachment through formation of heavy-Rydberg ion pair states in Rydberg atom collisions  

NASA Astrophysics Data System (ADS)

A new approach to investigating the properties, i.e., lifetimes and decay energetics, of short-lived intermediates formed during dissociative electron attachment reactions is described that is based on measurements of the velocity and angular distributions of heavy-Rydberg ion pair states formed through electron transfer in collisions with Rydberg atoms. The experimental results are analyzed with the aid of a Monte Carlo collisions code and show that while electron capture by CF3I and CH2Br2 leads to creation of very-short-lived intermediates capture by CCl4 results in formation of much longer lived intermediates.

Buathong, S.; Kelley, M.; Wang, C. H.; Dunning, F. B.

2015-01-01

23

Pulsed-field ionization spectroscopy of high Rydberg states ,,n=50200... -benzene...chromium  

E-print Network

Pulsed-field ionization spectroscopy of high Rydberg states ,,n=50­200... of bis,, 6 -benzene...chromium The ionization behavior of the high Rydberg states of bis 6 -benzene chromium in the presence of ac and/or dc chromium, the accurate ionization potential is deduced to give IP=5.4665±0.0003 eV. Optimization

Kim, Sang Kyu

24

Diamagnetic behaviour of xenon Rydberg states studied by the R.F. optogalvanic method  

E-print Network

249 Diamagnetic behaviour of xenon Rydberg states studied by the R.F. optogalvanic method J. P behaviour of xenon nf Rydberg states is studied using single-mode dye laser excita- tion and an R xenon can offer interesting opportunities for studies of this type. We want furthermore to emphasize

Paris-Sud XI, Université de

25

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

E-print Network

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

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

2007-11-02

26

From the Pendulum to Rydberg Accelerator and Planetary Dynamics: Autoresonant Formation and Control of Nonlinear States  

E-print Network

From the Pendulum to Rydberg Accelerator and Planetary Dynamics: Autoresonant Formation and Control of a pendulum (Sec.II), manipulation of a classical state of a Rydberg atom in 3D [8] (Sec.IV), and a related DRIVEN PENDULUM We proceed from the problem of excitation of a pendulum to large energies

Friedland, Lazar

27

Infrared vibrational spectroscopy of cis-dichloroethene in Rydberg states  

NASA Astrophysics Data System (ADS)

We have measured the infrared (IR) vibrational spectrum for cis-dichloroethene (cis-ClCH ?CHCl) in excited Rydberg states with the effective principal quantum numbers n*=9, 13, 17, 21, 28, and 55 using the vacuum ultraviolet-IR-photoinduced Rydberg ionization (VUV-IR-PIRI) scheme. Although the IR frequencies observed for the vibrational bands ?11* (asymmetric C-H stretch) and ?12* (symmetric C-H stretch) are essentially unchanged for different n* states, suggesting that the IR absorption predominantly involves the ion core and that the Rydberg electron behaves as a spectator; the intensity ratio for the ?11* and ?12* bands [R(?11*/?12*)] is found to decrease smoothly as n* is increased. This trend is consistent with the results of a model ab initio quantum calculation of R(?11*/?12*) for excited cis-ClCH ?CHCl in n*=3-18 states and the MP2/6-311++G(2df,p) calculations of R(?11/?12) and R(?11+/?12+), where R(?11/?12)[R(?11+/?12+)] represents the intensity ratio of the ?11(?11+) asymmetric C-H stretching to the ?12(?12+) symmetric C-H stretching vibrational bands for cis-ClCH ?CHCl (cis-ClCH ?CHCl+). We have also measured the IR-VUV-photoion (IR-VUV-PI) and IR-VUV-pulsed field ionization-photoelectron depletion (IR-VUV-PFI-PED) spectra for cis-ClCH ?CHCl. These spectra are consistent with ab initio calculations, indicating that the IR absorption cross section for the ?12 band is negligibly small compared to that for the ?11 band. While the VUV-IR-PIRI measurements have allowed the determination of ?11+=3067±2cm-1, ?12+=3090±2cm-1, and R(?11+/?12+)?1.3 for cis-ClCH ?CHCl+, the IR-VUV-PI and IR-VUV-PFI-PED measurements have provided the value ?11=3088.5±0.2cm-1 for cis-ClCH ?CHCl.

Wang, P.; Woo, H. K.; Lau, K.-C.; Xing, X.; Ng, C. Y.; Zyubin, A. S.; Mebel, A. M.

2006-02-01

28

Quadratic Zeeman effect in Rydberg states of NO  

Microsoft Academic Search

We analyse a resonant-enhanced multiphoton ionization (REMPI) spectrum of the high n (35-50) members of the Rydberg series of NO molecules recorded in a 1 T external magnetic field. In this range the quadratic Zeeman interaction takes over the Coulomb interaction and gradually scrambles the Coulomb structure of the Rydberg series. A perturbative quantum treatment of the diamagnetic interaction, giving

M. Raoult; S. Guizard; D. Gauyacq; A. Matzkin

2005-01-01

29

Charge transport, configuration interaction and Rydberg states under density functional theory  

E-print Network

Density functional theory (DFT) is a computationally efficient formalism for studying electronic structure and dynamics. In this work, we develop DFT-based excited-state methods to study electron transport, Rydberg excited ...

Cheng, Chiao-Lun

2008-01-01

30

A study on a new 2? Rydberg state of SF by resonance-enhanced multiphoton ionization spectroscopy  

NASA Astrophysics Data System (ADS)

The (2 + 1) resonance-enhanced multiphoton ionization (REMPI) spectra of SF radicals have been recorded in the single-photon wavelength region of 271-286 nm for the first time. Four regular vibrational bands were observed and assigned as the transition by two-photon from the ground state to a 2? Rydberg state. The 2? Rydberg state arises from one-electron excitation from the 3? orbital of SF ground state to a 4p? Rydberg orbital, which converging to the first excited ionic state ( 1?). The term value Te, spin-orbit coupling constant A, vibrational frequency and rotational constants for the 2? Rydberg state are determined.

Wang, Tingting; Zheng, Xianfeng; Li, ChunYan; Chen, Yang

2006-07-01

31

Sub-Poissonian statistics of Rydberg-interacting dark-state polaritons.  

PubMed

We observe individual dark-state polaritons as they propagate through an ultracold atomic gas involving Rydberg states coupled via an electromagnetically induced transparency resonance. Strong long-range interactions between Rydberg excitations give rise to a blockade between polaritons, resulting in large optical nonlinearities and modified polariton number statistics. By combining optical imaging and high-fidelity detection of the Rydberg polaritons we investigate both aspects of this coupled atom-light system. We map out the full nonlinear optical response as a function of atomic density and follow the temporal evolution of polaritons through the atomic cloud. In the blockade regime, the statistical fluctuations of the polariton number drop well below the quantum noise limit. The low level of fluctuations indicates that photon correlations modified by the strong interactions have a significant backaction on the Rydberg atom statistics. PMID:25167407

Hofmann, C S; Günter, G; Schempp, H; Robert-de-Saint-Vincent, M; Gärttner, M; Evers, J; Whitlock, S; Weidemüller, M

2013-05-17

32

Need for high resolution in VUV Rydberg state spectroscopy  

NASA Technical Reports Server (NTRS)

The paper emphasizes the necessity of high energy resolution (resolving powers greater than 100,000) in VUV spectroscopic determinations of atomic and molecular Rydberg electronic structures. Attention is given to spectral observations of Rydberg levels in Ge I near the 4p 2P(0)1/2 limit, in Sr I near the 4d 2D3/2 limit, and in diatomic hydrogen halides (especially H I) below the X2Pi3/2 limit.

Ginter, M. L.; Ginter, D. S.; Brown, C. M.

1980-01-01

33

Predissociation of high-lying Rydberg states of molecular iodine via ion-pair states  

SciTech Connect

Velocity map imaging of the photofragments arising from two-photon photoexcitation of molecular iodine in the energy range 73?500–74?500 cm{sup ?1} covering the bands of high-lying gerade Rydberg states [{sup 2}?{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}?{sub 1/2}]{sub c}6d;2{sub g} has been applied. The ion signal was dominated by the atomic fragment ion I{sup +}. Up to 5 dissociation channels yielding I{sup +} ions with different kinetic energies were observed when the I{sub 2} molecule was excited within discrete peaks of Rydberg states and their satellites in this region. One of these channels gives rise to images of I{sup +} and I{sup ?} ions with equal kinetic energy indicating predissociation of I{sub 2} via ion-pair states. The contribution of this channel was up to about 50% of the total I{sup +} signal. The four other channels correspond to predissociation via lower lying Rydberg states giving rise to excited iodine atoms providing I{sup +} ions by subsequent one-photon ionization by the same laser pulse. The ratio of these channels varied from peak to peak in the spectrum but their total ionic signal was always much higher than the signal of (2 + 1) resonance enhanced multi-photon ionization of I{sub 2}, which was previously considered to be the origin of ionic signal in this spectral range. The first-tier E0{sub g}{sup +} and D{sup ?}2{sub g} ion-pair states are concluded to be responsible for predissociation of Rydberg states [{sup 2}?{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}?{sub 1/2}]{sub c}6d;2{sub g}, respectively. Further predissociation of these ion-pair states via lower lying Rydberg states gives rise to excited I(5s{sup 2}5p{sup 4}6s{sup 1}) atoms responsible for major part of ion signal. The isotropic angular distribution of the photofragment recoil directions observed for all channels indicates that the studied Rydberg states are long-lived compared with the rotational period of the I{sub 2} molecule.

Bogomolov, Alexandr S. [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation)] [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation); Grüner, Barbara; Mudrich, Marcel [Physikalisches Institut, Universität Freiburg, D-79104 Freiburg (Germany)] [Physikalisches Institut, Universität Freiburg, D-79104 Freiburg (Germany); Kochubei, Sergei A. [Institute of Semiconductor Physics, ac. Lavrent'yev ave., 13, Novosibirsk 630090 (Russian Federation)] [Institute of Semiconductor Physics, ac. Lavrent'yev ave., 13, Novosibirsk 630090 (Russian Federation); Baklanov, Alexey V. [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation) [Institute of Chemical Kinetics and Combustion, Institutskaya Str. 3, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090 (Russian Federation)

2014-03-28

34

Two-color photoexcitation of Rydberg states via an electric quadrupole transition  

SciTech Connect

We report the observation of an electric quadrupole transition between the 4s{sup '}[1/2]{sub 0}{sup o} and 3d[3/2]{sub 2}{sup o} states in the spectrum of argon and use it in the first step of a scheme to excite Rydberg states. The initial identification of the transition is based on one-color, two-photon photoionization. A different experiment utilizing two-color, two-photon photoexcitation to Rydberg states confirms the identification. Despite the unavoidable background of one-color, two-photon photoionization, the latter experimental technique makes possible two-photon spectroscopy of Rydberg states using a resonant intermediate state populated by an electric quadrupole transition.

Li Leping; Gu Quanli; Knee, J. L. [Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459 (United States); Wright, J. D.; DiSciacca, J. M.; Morgan, T. J. [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States)

2008-03-15

35

Single Photon Transistor Mediated by Inter-State Rydberg Interaction  

E-print Network

We report on the realization of an all-optical transistor by mapping gate and source photons into strongly interacting Rydberg excitations with different principal quantum numbers in an ultracold atomic ensemble. We obtain a record switch contrast of 40 % for a coherent gate input with mean photon number one and demonstrate attenuation of source transmission by over 10 photons with a single gate photon. We use our optical transistor to demonstrate the nondestructive detection of a single Rydberg atom with a fidelity of 0.72(4).

Hannes Gorniaczyk; Christoph Tresp; Johannes Schmidt; Helmut Fedder; Sebastian Hofferberth

2014-04-24

36

LETTER TO THE EDITOR: Energies and dipole moments of long-range molecular Rydberg states  

NASA Astrophysics Data System (ADS)

Adiabatic wavefunctions and dipole moments of Rydberg states perturbed by a neutral atom have been investigated. Wavefunctions are equal to sums of products of Coulomb wavefunctions and differ very substantially from any single Coulomb wavefunction. Using the Kirchhoff-integral method (Fabrikant I I 1993 J. Phys. B: At. Mol. Opt. Phys. 26 2533) we calculate the potential curves of two adiabatic Rydberg states for the Rb*(n?30) + Rb(5s) system: one dominated by the 3S symmetry near the ground-state Rb atom, and the other dominated by the 3P symmetry.

Chibisov, M. I.; Khuskivadze, A. A.; Fabrikant, I. I.

2002-05-01

37

Collisional and electric-field ionization of laser-prepared Rydberg states in an ion trap mass spectrometer  

SciTech Connect

Rydberg states of rubidium are selectively generated by one and two photon laser excitation in a quadrupole ion trap mass spectrometer. Collisional and electric-field ionization is investigated in trapping device. CCl{sub 4} is studied as a target for ionization of Rydberg states through electron attachment.

Ramsey, J.M.; Whitten, W.B.; Goeringer, D.E.; Buckley, B.T.

1990-01-01

38

State selective extreme ultraviolet (EUV) photoemission cross sections for excitation and ionization-excitation of helium in fast electron and positive ion collisions: He{sup {lg_bullet}} (1snp) {sup 1}P{sup {lg_bullet}} (n=2 to 10) and He{sup +} (np) (n=2 to 10) Rydberg states  

SciTech Connect

We have analyzed high resolution (EUV) spectra of HeI and HeII originating from e{sup -}, H{sup +}, H{sub 2}{sup +} and H{sub 3}{sup +} bombardment of He gas. From these data excitation and ionization-excitation cross sections have been obtained by the HeI (1snp){sup 1}P{sup o} {yields} (1s2){sup 1}S + h{nu} and HeII (np){sup 2}P{sup o}-(1s){sup 2}S + h{nu} Rydberg series with main quantum numbers from n=2 to 10, respectively. The determination of the individual line intensities has been accomplished using the IRAF one dimensional spectroscopy package installed on the Physics Department`s HP9000 system. The cross sections for n{>=}4 presented here are reported for the first time. The up manifolds have been studied as a function of the projectile charge and velocity and number of scattering centers. Theoretically we have parametrized the cross sections in terms of first order, second order and interference contributions. We have also tested sum rules, by integrating over all np states. The dynamical Stark mixing among HeII ns and np states has also been investigated. A detailed discussion of the intensity distribution at high np states is presented for different means of excitation.

Rodrigue, M.; Colegrove, T.; Bailey, M. [Univ. of Nevada, Reno, NV (United States)] [and others

1993-05-01

39

Dynamical stabilization of the initial state in a periodically kicked one-dimensional Rydberg atom  

Microsoft Academic Search

We investigate the dynamical stabilization of the initial state of a one-dimensional Rydberg atom subjected to a periodic train of half-cycle pulses. A survival probability of the initial state as a function of pulse repetition frequency is presented for different values of momentum transferred to the electron. This survival probability exhibits a broad maximum at train repetition frequencies close to

T. Kopyciuk; R. Parzynski

2009-01-01

40

Dynamical stabilization of the initial state in a periodically kicked three-dimensional Rydberg atom  

Microsoft Academic Search

We present the dynamical stabilization of the initial state of a three-dimensional Rydberg atom subjected to a periodic train of half-cycle pulses. It is shown as an existence of a broad maximum of the survival probability at train repetition frequencies close to the classical orbital frequency. Population of the initial state for train repetition frequencies from this plateau is almost

T Kopyciuk

2012-01-01

41

The spectroscopy of bound and predissociating Rydberg states of NO in external electric fields  

E-print Network

of NO below the v+=0 ionisation limit, with principal quantum numbers n - 25 - 30. The Stark states are applied to the bound Rydberg states of NO, and the ionisation time profiles are obtained. The development of the experimental chamber and investigation into sources of electrical noise required to achieve this is discussed

Jones, Peter JS

42

Coherent population transfer and quantum entanglement generation involving a Rydberg state by stimulated Raman adiabatic passage  

SciTech Connect

We study a dilute sample of cold atoms to achieve efficient population transfer from a ground state to a Rydberg state. This sample is approximately divided into many independent microspheres containing only two atoms. Each pair of atoms in a microsphere may become quantum correlated via the dipole-dipole interaction characterized by a van der Waals potential. Our numerical results show that, by modulating detunings of a pump pulse and a Stokes pulse applied in the counterintuitive order, we can drive the dilute sample either into the blockade regime or into the antiblockade regime. In the blockade regime, only one atom is allowed to be coherently transferred into the Rydberg state in a microsphere, which then results in a maximal entangled state. In the antiblockade regime, however, both atoms in a microsphere can be efficiently excited into the Rydberg state, which is not accompanied by quantum entanglement. A second maximal entangled state may also be generated if we work between the blockade regime and the antiblockade regime. Note that the existence of a quasidark state is essential for exciting both atoms in a microsphere into the Rydberg state when the van der Waals potential is nonzero.

Yan Dong [College of Physics, Jilin University, Changchun 130012 (China); School of Science, Changchun University, Changchun 130022 (China); Cui Cuili; Zhang Mei; Wu Jinhui [College of Physics, Jilin University, Changchun 130012 (China)

2011-10-15

43

Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions  

SciTech Connect

Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a starlike geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S{sub 1/2}{yields}5P{sub 3/2}{yields}6S{sub 1/2}{yields}nP in Rb atoms have shown that, compared to the one- and two-photon laser excitation, this approach provides much narrower linewidth and longer coherence time for both cold atom samples and hot vapors, if the intermediate one-photon resonances of the three-photon transition are detuned by more than respective single-photon Doppler widths. This method can be used to improve fidelity of Rydberg quantum gates and precision of spectroscopic measurements in Rydberg atoms.

Ryabtsev, I. I.; Beterov, I. I.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A. [A. V. Rzhanov Institute of Semiconductor Physics SB RAS, Prospekt Lavrentyeva 13, 630090 Novosibirsk (Russian Federation)

2011-11-15

44

Observation of g/u-symmetry mixing in the high-n Rydberg states of HD  

SciTech Connect

The structure and dynamics of high-n Rydberg states belonging to series converging to the (v{sup +} = 0, N{sup +} = 0–2) levels of the X{sup +2}?{sub g}{sup +} electronic ground state of HD{sup +} were studied by high-resolution spectroscopy from the GK{sup 1}?{sub g}{sup +} (v= 1, N = 1) state under field-free conditions. Three effects of g/u-symmetry breaking were detected: (i) Single-photon transitions from the GK?(v = 1, N = 1) state of gerade symmetry to the 30d2{sub 1} and 31g2{sub 2} Rydberg states of gerade symmetry were observed after careful compensation of the stray electric fields. (ii) The singlet 61p1{sub 2} Rydberg state of ungerade symmetry was found to autoionize to the N{sup +} = 0,?? = 2 ionization continuum of gerade symmetry with a lifetime of 77(10)?ns. (iii) Shifts of up to 20?MHz induced by g/u-symmetry mixing were measured for members of the np1{sub 1} Rydberg series which lie close to nd2{sub 1} Rydberg states. These observations were analyzed in the framework of multichannel quantum-defect theory. From the observed level shifts, the off-diagonal eigenquantum-defect element ?{sub pd} of singlet-? symmetry was determined to be 0.0023(3) and the corresponding autoionization dynamics could be characterized. The ionization energy of the GK?(v = 1, N = 1) state of HD was determined to be 12?710.544?23(10)?cm{sup ?1}.

Sprecher, Daniel; Merkt, Frédéric, E-mail: frederic.merkt@phys.chem.ethz.ch [Laboratorium für Physikalische Chemie, ETH-Zürich, 8093 Zürich (Switzerland)] [Laboratorium für Physikalische Chemie, ETH-Zürich, 8093 Zürich (Switzerland)

2014-03-28

45

Preparation and characterization of long-lived molecular Rydberg states: Application to HD  

E-print Network

. INTRODUCTION The recent discovery of unexpectedly long-lived high Rydberg states in atoms and molecules that the method of H-atom photofragment translational spectroscopy pioneered by Ash- fold, Welge, and co-workers19 the hydrogen atom. The success of this method resides in its ability to probe the H-atom product by exciting

Zare, Richard N.

46

Quadratic Zeeman effect and l-mixing in high Rydberg states of Sr  

Microsoft Academic Search

By taking advantage of the n4 scaling factor, the quadratic Zeeman effect was measured for low magnetic fields in Rydberg states with principal quantum numbers n>100. The observed l-mixing is found to be in agreement with theoretical predictions.

R. Beigang; W. Makat; E. Matthias; A. Timmermann; P. J. West

1984-01-01

47

An investigation of electronic states of some molecules and molecular cations using mass analyzed threshold ionization and photoinduced Rydberg ionization spectroscopy  

Microsoft Academic Search

Mass analyzed threshold ionization (MATI) experiments have enabled mapping of the n-dependent Rydberg state survival probability for a series of molecules. Utilizing vacuum and extreme ultraviolet (VUV\\/XUV) photons, one photon Rydberg manifold spectra of argon, hydrogen chloride, nitrogen, benzene, and oxygen were produced, and the prospects of photoinduced Rydberg ionization (PIRI) experiments examined. It was found that the widths of

Jason David Hofstein

1999-01-01

48

Photofragmentation, state interaction, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization of HI  

SciTech Connect

Mass resolved resonance enhanced multiphoton ionization data for hydrogen iodide (HI), for two-photon resonance excitation to Rydberg and ion-pair states in the 69?600–72?400 cm{sup ?1} region were recorded and analyzed. Spectral perturbations due to homogeneous and heterogeneous interactions between Rydberg and ion-pair states, showing as deformations in line-positions, line-intensities, and line-widths, were focused on. Parameters relevant to photodissociation processes, state interaction strengths and spectroscopic parameters for deperturbed states were derived. Overall interaction and dynamical schemes to describe the observations are proposed.

Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst, E-mail: agust@hi.is [Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík (Iceland)

2014-06-28

49

Collisional destruction of circular Rydberg states by atoms with small electron affinities  

NASA Astrophysics Data System (ADS)

The results of theoretical studies of interaction between neutral targets with small electron affinities and Rydberg atoms in circular states are reported. The cross sections of collisional destruction of such states due to the resonant quenching mechanism are calculated on the basis of the semiclassical theory of nonadiabatic transitions between the ionic and Rydberg covalent terms of a quasimolecule combined with recently developed technique for exact evaluation of matrix elements. We obtain the basic formula for the square of the coupling parameter involving Rydberg nlm-state with the given values of the principal, orbital, and magnetic quantum numbers. It is employed for the derivation of explicit expressions for transitions from circular states applicable in cases of s- and p-states of negative ion temporarily formed during a collision of atoms. Numerical calculations are carried out for thermal collisions of Li? and Na? atoms with Ca(4s2) and Sr(5s2). We explore n-, l-, m-, and velocity-dependences of the cross sections and analyze orientation effects in such collisions. Cross sections of resonant quenching for circular states (l = | m | = n - 1) are shown to be much smaller than those for states with small l values and typically two times lower than for nearly-circular states (l = n - 1) averaged over m.

Mironchuk, Elena S.; Narits, Alexander A.; Lebedev, Vladimir S.

2014-12-01

50

Quadratic Zeeman effect in hydrogen Rydberg states: Rigorous bound-state error estimates in the weak-field regime  

SciTech Connect

Applying a method based on some results due to Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], we show that series of Rydberg eigenvalues and Rydberg eigenfunctions of hydrogen in a uniform magnetic field can be calculated with a rigorous error estimate. The efficiency of the method decreases as the eigenvalue density increases and as [gamma][ital n][sup 3][r arrow]1, where [gamma] is the magnetic-field strength in units of 2.35[times]10[sup 9] G and [ital n] is the principal quantum number of the unperturbed hydrogenic manifold from which the diamagnetic Rydberg states evolve. Fixing [gamma] at the laboratory value 2[times]10[sup [minus]5] and confining our calculations to the region [gamma][ital n][sup 3][lt]1 (weak-field regime), we obtain extremely accurate results up to states corresponding to the [ital n]=32 manifold.

Falsaperla, P.; Fonte, G. (Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania (Italy) Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Corso Italia 57, I-95129 Catania (Italy))

1993-05-01

51

Equation of state of metallic helium  

SciTech Connect

The effective ion-ion interaction, free energy, pressure, and electric resistance of metallic liquid helium have been calculated in wide density and temperature ranges using perturbation theory in the electron-ion interaction potential. In the case of conduction electrons, the exchange interaction has been taken into account in the random-phase approximation and correlations have been taken into account in the local-field approximation. The solid-sphere model has been used for the nuclear subsystem. The diameter of these spheres is the only parameter of this theory. The diameter and density of the system at which the transition of helium from the singly ionized to doubly ionized state occurs have been estimated by analyzing the pair effective interaction between helium atoms. The case of doubly ionized helium atoms has been considered. Terms up to the third order of perturbation theory have been taken into account in the numerical calculations. The contribution of the third-order term is significant in all cases. The electric resistance and its temperature dependence for metallic helium are characteristic of simple divalent metals in the liquid state. The thermodynamic parameters-temperature and pressure densities-are within the ranges characteristic of the central regions of giant planets. This makes it possible to assume the existence of helium in the metallic state within the solar system.

Shvets, V. T., E-mail: tarval@breezein.net [Odessa State Academy of Refrigeration (Ukraine)

2013-01-15

52

Chirped-pulse millimeter-wave spectroscopy: Spectrum, dynamics, and manipulation of Rydberg–Rydberg transitions  

E-print Network

We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg–Rydberg transitions is that they have enormous electric dipole transition ...

Colombo, Anthony P.

2013-01-01

53

Ion rotational distributions following vibrational autoionization of the Rydberg states of water  

NASA Astrophysics Data System (ADS)

Double-resonance laser excitation and high-resolution energy dispersive photoelectron spectroscopy were used to determine the ionic rotational-state distributions following vibrational autoionization of Rydberg states of water having principal quantum number n=8-10 and converging to the X˜ 2B1 (1,0,0) state of H2O+. Where possible, these states were identified by comparison with results of a calculation based on multichannel quantum defect theory. Symmetry and angular momentum constraints link the observed ionic rotational states to particular values of the orbital angular momentum of the Rydberg electron, l, and to the partial-wave composition of the ejected electron. In particular, this connection allows an unambiguous determination of the even or odd character of the partial waves and provides a test of the predicted character of the autoionizing resonances. The effects of l mixing induced by the nonspherical nature of the ionic field are plainly evident in the ion distributions. The present results also allow a tentative assignment of some resonances to the previously unidentified np Rydberg states.

Glab, W. L.; Pratt, S. T.

2004-05-01

54

Silicon as a model ion trap: Time domain measurements of donor Rydberg states  

PubMed Central

One of the great successes of quantum physics is the description of the long-lived Rydberg states of atoms and ions. The Bohr model is equally applicable to donor impurity atoms in semiconductor physics, where the conduction band corresponds to the vacuum, and the loosely bound electron orbiting a singly charged core has a hydrogen-like spectrum according to the usual Bohr–Sommerfeld formula, shifted to the far-infrared because of the small effective mass and high dielectric constant. Manipulation of Rydberg states in free atoms and ions by single and multiphoton processes has been tremendously productive since the development of pulsed visible laser spectroscopy. The analogous manipulations have not been conducted for donor impurities in silicon. Here, we use the FELIX pulsed free electron laser to perform time-domain measurements of the Rydberg state dynamics in phosphorus- and arsenic-doped silicon and we have obtained lifetimes consistent with frequency domain linewidths for isotopically purified silicon. This implies that the dominant decoherence mechanism for excited Rydberg states is lifetime broadening, just as for atoms in ion traps. The experiments are important because they represent a step toward coherent control and manipulation of atomic-like quantum levels in the most common semiconductor and complement magnetic resonance experiments in the literature, which show extraordinarily long spin lattice relaxation times—key to many well known schemes for quantum computing qubits—for the same impurities. Our results, taken together with the magnetic resonance data and progress in precise placement of single impurities, suggest that doped silicon, the basis for modern microelectronics, is also a model ion trap.

Vinh, N. Q.; Greenland, P. T.; Litvinenko, K.; Redlich, B.; van der Meer, A. F. G.; Lynch, S. A.; Warner, M.; Stoneham, A. M.; Aeppli, G.; Paul, D. J.; Pidgeon, C. R.; Murdin, B. N.

2008-01-01

55

Zeeman Effect of J=2 States of Sr: g-Factor Variation for Interacting Rydberg Series  

Microsoft Academic Search

Measurements of the g factor for a series of bound, 5snd J=2 states in Sr, in the region of an avoided crossing between 1D2 and 3D2 Rydberg series, show a variation which is in agreement with the prediction of multichannel quantum-defect theory. The g factor was measured by multiphonon ionization spectroscopy. The dependence of ionization signal on laser polarization was

J. J. Wynne; J. A. Armstrong; P. Esherick

1977-01-01

56

Rydberg series of 1?u+ and 1?u states of the Li2 molecule studied by the promotion model  

NASA Astrophysics Data System (ADS)

We studied the Rydberg series for the 12 1?u+, 7 1?u, and 1 1?u states. This set consists of the seventeen states derivable from the Li(2s) + Li(nl) (n = 2, 3, 4, 5) configuration, one 1?u+ state and one 1?u state derivable from Li(2s) + Li(6p) and Li(2s) + Li(6d), respectively, plus one ionic state. We used the multireference configuration interaction method, combined with the Stuttgart/Köln group’s effective core potential/core polarization potential method, to calculate their potential energy curves (PECs). Four Rydberg series, ?uns (n = 3, 4, 5, 6), ?unp (n = 2, 3, 4, 5), ?und (n = 3, 4, 5, 6), and ?unf (n = 4, 5), are identified near the potential energy minima (referred to as the ‘Rydberg region’). The promotion model is used to examine the behaviour of PECs and quantum defect curves (QDCs) by constructing diabatic PECs and QDCs. Besides QDCs, effective n and promotion curves are also used to directly examine the promotion. This reveals that the promotion model can be successfully applied to the singlet ungerade states of Li2, indicating that the Rydberg region has the same characteristics as the united atom (UA) limit. Thus, the Rydberg region in Li2 is much closer to the UA limit than the separated atoms (SA) limit. Correlation diagrams based on the promotion model show a big difference in the number of avoided crossings for the 1?u+ and 1?u states. The larger number of avoided crossings for 1?u+ states produces features in the PECs of the 1?u+ states such as shoulders, flattening, and grouping. The promotion model not only helps to identify Rydberg series, but also to explain all the major and minor aspects and subtle phenomena observed in the PECs and spectroscopic constants of the singlet ungerade Rydberg states of Li2.

Kim, Hyun-Jin; Lee, Chun-Woo

2015-01-01

57

Dissociative electron attachment to vibrationally excited H2 molecules involving the ?g+ resonant Rydberg electronic state  

NASA Astrophysics Data System (ADS)

Dissociative electron attachment cross sections (DEA) on vibrationally excited H2 molecule taking place via the 2?g+ Rydberg-excited resonant state are studied using the local complex potential (LCP) model for resonant collisions. The cross sections are calculated for all initial vibrational levels (vi = 0-14) of the neutral molecule. In contrast to the previously noted dramatic increase in the DEA cross sections with increasing vi, when the process proceeds via the X 2?u+ shape resonance of H2, for the 2?g+ Rydberg resonance the cross sections increase only gradually up to vi = 3 and then decrease. Moreover, the cross sections for vi ? 6 exhibit pronounced oscillatory structures. A discussion of the origin of the observed behavior of calculated cross sections is given. The DEA rate coefficients for all vi levels are also calculated in the 0.5-1000 eV temperature range.

Celiberto, R.; Janev, R. K.; Wadehra, J. M.; Tennyson, J.

2012-04-01

58

Rydberg and valence excited states of dibromomethane in 35,000-95,000 cm-1 region studied using synchrotron radiation  

NASA Astrophysics Data System (ADS)

The UV-VUV photoabsorption spectrum of dibromomethane (CH2Br2) in the energy region 4.3-11.8 eV (35,000-95,000 cm-1) is investigated using synchrotron radiation. Rydberg series converging to the first four ionization limits at 10.52, 10.74, 11.21 and 11.30 eV corresponding to excitations from the 3b1, 2b2, 1a2, and 4a1 orbitals of CH2Br2 are identified and analyzed. Quantum defect values are observed to be consistent with excitation from the bromine lone pair orbitals. Assignments of the ns Rydberg series are revised and the np and nd Rydberg series are assigned for the first time. Observed vibrational features accompanying the 5p and 4d Rydberg states are assigned exclusively to the totally symmetric (a1) -CBr symmetric stretching mode (?3) in contrast to the earlier assignment to ?3 and -CH2 bending (?2) modes. The Rydberg and valence transitions observed in the present experiment are found to be in good agreement with the vertical excited states calculated using the TDDFT method. The calculations are further used to infer the valence transitions responsible for the broad intensity pedestals underlying the Rydberg transitions. The assignments are confirmed using isotopic substitution studies on CD2Br2 whose UV-VUV photoabsorption spectrum is reported here for the first time. This work presents a consolidated analysis of the UV-VUV photoabsorption spectrum of dibromomethane.

Mandal, Anuvab; Singh, Param Jeet; Shastri, Aparna; Kumar, Vijay; Sekhar, B. N. Raja; Jagatap, B. N.

2014-09-01

59

High-field-seeking Rydberg atoms orbiting a charged wire  

NASA Astrophysics Data System (ADS)

Pulsed supersonic beams of helium atoms in the high-field-seeking 52p Rydberg state have been guided while following helical trajectories in the electrostatic field of a charged wire suspended along the axis of a grounded cylindrical metallic tube. The operation of this electrostatic wire guide for samples in high-field-seeking Rydberg-Stark states has been investigated with dc and pulsed electric potentials applied to the wire while the guided atoms were detected by pulsed electric-field ionization. The acceptance of the guide has been determined through numerical particle trajectory simulations.

Ko, H.; Hogan, S. D.

2014-05-01

60

Rydberg States of ThIII and UV W. R. Johnson  

E-print Network

to the (J0M0) ground-state to give a coupled two-electron state (FMF ). We use the notation of hyperfine. The first-order energy is E (1) F = (J0M0, kmk)FMF |U| (J0M0, kmk)FMF (8) = J0M0, kmk|FMF J0M0, kmk|FMF Ã? LM to the correction to the energy of the Rydberg state from the core polarizability. We have E (2) pol = - J0M0, kmk|FMF

Johnson, Walter R.

61

Electronic Spectroscopy and Ultrafast Energy Relaxation Pathways in the lowest Rydberg States of Trimethylamine  

PubMed Central

Resonance-enhanced multiphoton ionization photoelectron spectroscopy has been applied to study the electronic spectroscopy and relaxation pathways amongst the 3p and 3s Rydberg states of trimethylamine. The experiments used femtosecond and picosecond duration laser pulses at wavelengths of 416 nm, 266 nm, and 208 nm, and employed two-photon and three-photon ionization schemes. The binding energy of the 3s Rydberg state was found to be 3.087 ± 0.005 eV. The degenerate 3px,y states have binding energies of 2.251 ± 0.005 eV, and 3pz is at 2.204 ± 0.005 eV. Using picosecond and femtosecond time-resolved experiments we spectrally and temporally resolved an intricate sequence of energy relaxation pathways leading from the 3p states to the 3s state. With excitation at 5.96 eV, trimethylamine is found to decay from the 3pz state to 3px,y in 539 fs. The decay to 3s from all the 3p states takes place with a 2.9 ps time constant. On these time scales, trimethylamine does not fragment at the given internal energies, which range from 0.42 to 1.54 eV depending on the excitation wavelength and the electronic state. PMID:18834091

Cardoza, Job D.; Rudakov, Fedor M.; Weber, Peter M.

2009-01-01

62

Extensive Electron-Nuclear Angular Momentum Exchange in Vibrational Autoionization of np and nf Rydberg States of NO  

Microsoft Academic Search

Vibrational autoionization of individual rotational levels of np ( nu = 1) and nf ( nu = 1) Rydberg states of nitric oxide (NO) with 11<=n<=15 have been studied employing two-color double-resonance excitation via the NO A 2Sigma+ ( nui = 1) state. The rotational state distributions of the resulting NO+ X 1Sigma+ ( nu+ = 0) ion have been

Hongkun Park; David J. Leahy; Richard N. Zare

1996-01-01

63

Adiabatic energy levels and electric dipole moments of Rydberg states of Rb2 and Cs2 dimers  

NASA Astrophysics Data System (ADS)

We calculate potential energy curves for heavy alkali-metal dimers, Rb2 and Cs2 in which one of the atoms is in a highly excited Rydberg states. The method combines numerical integration of coupled equations, describing interaction of electron with the ground-state atom in the field of the Coulomb core of the Rydberg atom, with subsequent matching of the obtained wave function with the Coulomb Green's function in the form of the Kirchhoff integral. The spin-orbit interaction for the Rydberg electron is also included. The results show the existence of several groups of states. Most interesting of them are dominated either by the 3S symmetry near the ground-state atom or by the 3PJ symmetry, J=0,1,2. All states, except the 3P1 state, exhibit oscillatory dependence of energy on the internuclear distance that can support long-range molecular Rydberg states [e.g., ``trilobite states'' for the 3S symmetry, Greene et al., Phys. Rev. Lett. 85, 2458 (2000)]. These states possess large diagonal and transition dipole moments which are expressed analytically in terms of the Coulomb wave functions and calculated in a broad range of internuclear separations.

Khuskivadze, A. A.; Chibisov, M. I.; Fabrikant, I. I.

2002-10-01

64

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

NASA Astrophysics Data System (ADS)

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

Pfau, Tilman

2012-06-01

65

Neutral atoms are entangled in hyperfine states via Rydberg blockade  

SciTech Connect

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

Miller, Johanna

2010-02-15

66

Rydberg gas theory of a glow discharge plasma: III. Formation, occupied state distributions, free energy, and kinetic control.  

PubMed

It has been suggested that Rydberg gas atoms are involved in conducting electricity through a steady state flowing afterglow (FAG) discharge plasma (R. S. Mason, D. J. Mitchell and P. M. Dickinson, Phys. Chem. Chem. Phys., 2010, DOI: ). From known properties of Rydberg atoms, a statistical model is developed here to find the distribution of levels (principal quantum number n) occupied in such a hypothetical Rydberg gas. It behaves non-ideally at positive column plasma densities, predicting 30 < n < 150, peaking at n approximately = 85. These values depend on assumptions concerning the power of n dependency of 'pressure ionization' and the free charge density. The occupied states are very long-lived and almost completely separated from the low n states by the low probability of intermediate levels. The effects of Rydberg gas (N(R)) and free charge densities are examined. The gas can exist in a deep free energy well (> 120 kJ mol(-1) below ionisation level when 10(10) < or = N(R) < or = 10(11) atoms cm(-3)) but this is approximately 11 kJ mol(-1) higher than that of the equivalent free ion-electron gas; therefore if it exists in preference to the classical form of the plasma, it is controlled by kinetic factors. A mechanism is suggested by which this could occur. Thus, whilst ionization by high energy electron impact occurs at the Cathode Fall-Negative Glow (NG) boundary as usual, excitation of Rydberg atoms becomes more probable, by electrons slowed by collision and deceleration at the opposite NG-Positive Column (PC) plasma boundary. The atoms become stabilized after passing into the PC, by collisionally induced (nlm) mixing of states and the removal of free charge by charge transfer (and hence the passage of electric current through the Rydberg gas). The coupling of Rydberg states with the ionization continuum is poor; therefore, if the rate of their charge transfer is greater than that of their ionization, the Rydberg gas will remain relatively charge free and hence stable when it is conducting a current. When applied to the FAG plasma, the model provides a self-consistent interpretive framework for all its electrical, mass spectrometric and chemical behaviour. The effect on the optical spectroscopy of these plasmas is considered briefly. PMID:20358067

Mason, Rod S; Douglas, Peter

2010-04-21

67

Efficient Production of Rydberg Positronium  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally the production of Rydberg positronium (Ps) atoms in a two-step process, comprising incoherent laser excitation, first to the 2P3 state and then to states with principal quantum numbers ranging from 10 to 25. We find that excitation of 2P3 atoms to Rydberg levels occurs very efficiently (˜90%) and that the ˜25% overall efficiency of the production of Rydberg atoms is determined almost entirely by the spectral overlap of the primary excitation laser and the Doppler broadened width of the 1S3-2P3 transition. The observed efficiency of Rydberg Ps production can be explained if stimulated emission back to the 2P states is suppressed, for example, by intermixing of the Rydberg state Stark sublevels. The efficient production of long-lived Rydberg Ps in a high magnetic field may make it possible to perform direct measurements of the gravitational free fall of Ps.

Cassidy, D. B.; Hisakado, T. H.; Tom, H. W. K.; Mills, A. P., Jr.

2012-01-01

68

Photoinduced Rydberg ionization spectroscopy of the B˜ state of benzonitrile cation  

NASA Astrophysics Data System (ADS)

Photoinduced Rydberg ionization (PIRI) spectra of the second excited electronic state of benzonitrile cation were recorded via the origin and 6a1 and 6b1 vibrational levels of the cation ground electronic state. This B˜?X˜ transition was verified to be a forbidden B22?B12 transition with an origin at 17225cm-1 above the ground ionic state. By the use of vibronic coupling calculations, as well as symmetry analysis and comparison of the PIRI spectra via different ground vibrational levels, a nearly complete assignment of the vibrational structure was made, and the vibrational frequencies of the B˜B22 state of benzonitrile cation were obtained based on the assignments. Comparisons of the experimental spectra with simulations from the vibronic structure calculations are also used to validate the theoretical procedures used in the simulations.

Xu, Haifeng; Johnson, Philip M.; Sears, Trevor J.

2006-10-01

69

Three-Body Bound States in Dipole-Dipole Interacting Rydberg Atoms  

NASA Astrophysics Data System (ADS)

We show that the dipole-dipole interaction between three identical Rydberg atoms can give rise to bound trimer states. The microscopic origin of these states is fundamentally different from Efimov physics. Two stable trimer configurations exist where the atoms form the vertices of an equilateral triangle in a plane perpendicular to a static electric field. The triangle edge length typically exceeds R?2?m, and each configuration is twofold degenerate due to Kramers degeneracy. The depth of the potential wells and the triangle edge length can be controlled by external parameters. We establish the Borromean nature of the trimer states, analyze the quantum dynamics in the potential wells, and describe methods for their production and detection.

Kiffner, Martin; Li, Wenhui; Jaksch, Dieter

2013-12-01

70

Quadratic Zeeman effect in hydrogen Rydberg states: Rigorous error estimates for energy eigenvalues, energy eigenfunctions, and oscillator strengths  

Microsoft Academic Search

A variational method, based on some results due to T. Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], and previously discussed is here applied to the hydrogen atom in uniform magnetic fields of tesla in order to calculate, with a rigorous error estimate, energy eigenvalues, energy eigenfunctions, and oscillator strengths relative to Rydberg states up to just below the field-free

P. Falsaperla; G. Fonte

1994-01-01

71

Self-interaction corrected density functional calculations of Rydberg states of molecular clusters: N,N-dimethylisopropylamine  

NASA Astrophysics Data System (ADS)

Theoretical calculations of Rydberg excited states of molecular clusters consisting of N,N-dimethylisopropylamine molecules using a Perdew-Zunger self-interaction corrected energy functional are presented and compared with results of resonant multiphoton ionization measurements. The binding energy of the Rydberg electron in the monomer is calculated to be 2.79 eV and 2.27 eV in the 3s and 3p state, respectively, which compares well with measured values of 2.88 eV and 2.21 eV. Three different stable configurations of the dimer in the ground state were found using an energy functional that includes van der Waals interaction. The lowest ground state energy conformation has the two N-atoms widely separated, by 6.2 Å, while the Rydberg state energy is lowest for a configuration where the N-atoms of the two molecules come close together, separated by 3.7 Å. This conformational change is found to lower the Rydberg electron binding energy by 0.2 eV. The self-interaction corrected functional gives a highly localized hole on one of the two molecules, unlike results obtained using the PBE functional or the hybrid B3LYP functional which give a delocalized hole. For the trimer, the self-interaction corrected calculation gives a Rydberg electron binding energy lowered further by 0.13 eV as compared with the dimer. The calculated results compare well with trends observed in experimental measurements. The reduction of the Rydberg electron binding energy with cluster size can be ascribed to an effective delocalization of the positive charge of the hole by the induced and permanent dipole moments of the neighboring molecules. A further decrease observed to occur on a time scale of tens of ps can be ascribed to a structural rearrangement of the clusters in the Rydberg state where molecules rotate to orient their dipoles in response to the formation of the localized hole.

Gudmundsdóttir, Hildur; Zhang, Yao; Weber, Peter M.; Jónsson, Hannes

2014-12-01

72

Photoinduced Rydberg ionization spectroscopy  

NASA Astrophysics Data System (ADS)

A new method for the high-resolution electronic spectroscopy of cations with mass resolution. Optical transitions from Rydberg states converging on the ground state of the cation to states with electronically excited cores are detected by their rapid autoionization. The spectrum of these transitions provide ionic information because the photoabsorption cross-section of a molecule in a high-n Rydberg state closely mirrors the spectrum of the ion core. The technique presented here, called photoinduced Rydberg ionization (PIRI) spectroscopy, is applied in this case to record the B˜ 2E2g?X˜ 2E1g transition of the benzene cation via the vibrational origin of the X˜ 2E1g ionic state.

Taylor, David P.; Goode, Jon G.; LeClaire, Jeffrey E.; Johnson, Philip M.

1995-10-01

73

Precision calculation of low-energy electron-impact excitation cross sections of helium among the ground and excited states  

NASA Astrophysics Data System (ADS)

Low-energy electron-impact cross sections of helium among the ground and some low excited states are calculated using the R -matrix method. The convergences of the cross sections are checked systematically by using five sets of high-quality target states; i.e., including 5, 11, 19, 29, and 39 physical target states, respectively. Our calculated cross sections are in excellent agreement with the benchmark high-resolution experimental data. Compared with the recommended theoretical data, there is a deviation of about 6%, which suggests the recommended data may need a revision. Based on our calculation results, the influence of the Rydberg target states on the collision cross sections of the excited states is found to be similar to the case of the ground state; i.e., the amplitude of resonance structures will decrease with respect to the principal quantum number n of Rydberg target states. This result should be very useful for providing the cross-section data in the whole energy regions with high quality, which would be of great importance in related scientific fields.

Zeng, De-Ling; Gao, Xiang; Han, Xiao-Ying; Li, Jia-Ming

2015-02-01

74

Efficient Production of Rydberg Positronium  

NASA Astrophysics Data System (ADS)

We demonstrated the efficient production of Rydberg Positronium atoms using a two-step incoherent laser excitation process. The two step process occurs first to the 23P state and then to the quantum numbers ranging from 10 to 25. We found a 90% efficiency going from the 23P state to the Rydberg levels and an overall conversion efficiency of 25% of the production of Rydberg atoms. This high efficiency is due to the overlap of the laser bandwidth with the Doppler broadened width of the 1s-2p transition and the suppression of the stimulated emission back to the 2P states, due to the intermixing of the Rydberg state Stark sublevels. By demonstrating the production of long lived Rydberg Ps atoms in a high magnetic field may make it possible to perform gravitational measurements of free falling positronium atoms.

Hisakado, Tomu; Cassidy, David; Tom, Harry; Mills, Allen

2012-06-01

75

Few-body bound states of dipole-dipole-interacting Rydberg atoms  

NASA Astrophysics Data System (ADS)

We show that the resonant dipole-dipole interaction can give rise to bound states between two and three Rydberg atoms with nonoverlapping electron clouds. The dimer and trimer states arise from avoided level crossings between states converging to different fine-structure manifolds in the limit of separated atoms. We analyze the angular dependence of the potential wells, characterize the quantum dynamics in these potentials, and discuss methods for their production and detection. Typical distances between the atoms are of the order of several micrometers which can be resolved in state-of-the-art experiments. The potential depths and typical oscillation frequencies are about one order of magnitude larger as compared to the dimer and trimer states investigated by M. Kiffner et al. [Phys. Rev. A 86, 031401(R) (2012), 10.1103/PhysRevA.86.031401] and M. Kiffner, W. Li, and D. Jaksch [Phys. Rev. Lett. 111, 233003 (2013), 10.1103/PhysRevLett.111.233003], respectively. We find that the dimer and trimer molecules can be aligned with respect to the axis of a weak electric field.

Kiffner, Martin; Huo, Mingxia; Li, Wenhui; Jaksch, Dieter

2014-05-01

76

Experimental study on the possibility of formation of a condensate of excited states in a substance (Rydberg matter)  

Microsoft Academic Search

The results of experimental study of a condensate of cesium excited states (Rydberg matter) are presented. The possibility\\u000a of condensate formation was predicted theoretically first by Prof. .A. Manykin and coauthors from the Russian Research Center\\u000a Kurchatov Institute and experimentally observed by L. Holmlid and coauthors from the Chalmers University, Sweden. In a thermionic\\u000a energy converter with interelectrode medium, where,

V. I. Yarygin; V. N. Sidel’nikov; I. I. Kasikov; V. S. Mironov; S. M. Tulin

2003-01-01

77

Extensive electron-nuclear angular momentum exchange in vibrational autoionization of {ital np} and {ital nf} Rydberg states of NO  

Microsoft Academic Search

Vibrational autoionization of individual rotational levels of {ital np} (ν=1) and {ital nf} (ν=1) Rydberg states of nitric oxide (NO) with 11â¤{ital n}â¤15 have been studied employing two-color double-resonance excitation via the NO {ital A}²Σ{sup +} (ν{sub {ital i}}=1) state. The rotational state distributions of the resulting NO{sup +} {ital X}¹Σ{sup +} (ν{sup +}=0) ion have been determined by time-of-flight

Hongkun Park; David Leahy; Richard Zare

1996-01-01

78

Helium-helium clustering states in 12Be  

NASA Astrophysics Data System (ADS)

An inelastic excitation experiment was performed with a 12Be beam at 29 MeV/u on a carbon target. New resonances close to the respective cluster separation thresholds were observed in 12Be for the 4He+8He and 6He + 6He decay channels, confirming the previously proposed molecular rotational bands. Using the model-independent angular correlation analysis, a 0+ spin parity is assigned to the remarkably large peak at 10.3 MeV in the 4He + 8He channel. A distorted wave Born approximation (DWBA) calculation was compared to the experimental differential cross section of this state, resulting in a largely enhanced monopole transition matrix element of 7.0 ±1.0 fm2 , in good agreement with the generalized two-center cluster model (GTCM) prediction assuming a preformed ? -4 n -? configuration. Together with the previously reported large cluster spectroscopic factor, the strong clustering in 12Be is well demonstrated. The detection focused on the most forward angles, by using a zero-deg telescope, is essential in the present measurement.

Yang, Z. H.; Ye, Y. L.; Li, Z. H.; Lou, J. L.; Wang, J. S.; Jiang, D. X.; Ge, Y. C.; Li, Q. T.; Hua, H.; Li, X. Q.; Xu, F. R.; Pei, J. C.; Qiao, R.; You, H. B.; Wang, H.; Tian, Z. Y.; Li, K. A.; Sun, Y. L.; Liu, H. N.; Chen, J.; Wu, J.; Li, J.; Jiang, W.; Wen, C.; Yang, B.; Liu, Y.; Yang, Y. Y.; Ma, P.; Ma, J. B.; Jin, S. L.; Han, J. L.; Lee, J.

2015-02-01

79

Quadratic Zeeman effect in hydrogen Rydberg states: Rigorous bound-state error estimates in the weak-field regime  

Microsoft Academic Search

Applying a method based on some results due to Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], we show that series of Rydberg eigenvalues and Rydberg eigenfunctions of hydrogen in a uniform magnetic field can be calculated with a rigorous error estimate. The efficiency of the method decreases as the eigenvalue density increases and as gamman3-->1, where gamma is the

P. Falsaperla; G. Fonte

1993-01-01

80

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

NASA Technical Reports Server (NTRS)

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

Drachman, Richard J.

2006-01-01

81

Ab initio potential energy curves of the valence, Rydberg, and ion-pair states of iodine monochloride, ICl  

SciTech Connect

We present for the first time a coherent ab initio study of 39 states of valence, Rydberg, and ion-pair character of the diatomic interhalogen ICl species through large scale multireference variational methods including spin-orbit effects coupled with quantitative basis sets. Various avoided crossings are responsible for a non-adiabatic behaviour creating a wonderful vista for its theoretical description. Our molecular constants are compared with all available experimental data with the aim to assist experimentalists especially in the high energy regime of up to ?95?000 cm{sup ?1}.

Kalemos, Apostolos, E-mail: kalemos@chem.uoa.gr [Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens 15771 (Greece); Prosmiti, Rita [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, (IFF-CSIC), Serrano 123, 28006 Madrid (Spain)

2014-09-14

82

The influence of autoionizing Rydberg states on the H2+ X 2?g+ v+ = 0, 1, 2 state rotationally resolved photoelectron angular distributions and branching ratios  

NASA Astrophysics Data System (ADS)

The effect of vibrational autoionization on the H2+ X 2?g+ v+ = 0, 1, 2, N+ state rotationally resolved photoelectron angular distributions and branching ratios has been investigated with a velocity map imaging spectrometer and synchrotron radiation. Measurements have been made in the energy regions close to the v+ = 0, 1 or 2 ionization thresholds where the photoabsorption spectrum is dominated by structure due to autoionizing Rydberg states. The photoelectron anisotropy parameter associated with the X 1?g+ v? = 0, N? = 1 ? X 2?g+ v+ = 0, 1 or 2, N+ = 1 transition has a high value, characteristic of emission predominantly along the polarization axis of the incident radiation, when ionization occurs directly but in the vicinity of an autoionizing Rydberg state a more isotropic angular distribution is observed. For the v+ = 1 level, the present experimental data are compared with existing theoretical predictions in the energy range encompassing the R(1) 8p? v? = 2 and the Q(1) 8p? v? = 2 states. Qualitative agreement has been obtained between the measured and the predicted rotationally resolved photoelectron anisotropy parameters. The experimental values of the rotationally unresolved S-branch photoelectron anisotropy parameter are found to lie considerably higher than that (0.2, independent of excitation energy) predicted under the assumption of p-wave emission, and, moreover, exhibit deviations which appear to correlate with autoionizing Rydberg states. These observations suggest that a proper description of the photoionization dynamics requires the inclusion of partial waves higher than l = 1. In the neighbourhood of an autoionizing resonance, the variations occurring in the rotationally resolved branching ratios depend upon the rotational level of the Rydberg state.

Holland, D. M. P.; Shaw, D. A.

2014-09-01

83

The electronic structure of molecular oxygen and the rotational structure of the d(1)Pi(g) Rydberg state  

NASA Astrophysics Data System (ADS)

As a major constituent of the terrestrial atmosphere, the O2 molecule plays an important role both in the attenuation of solar radiation and in the spectrum of the airglow and aurora. Photo absorption by O 2 to its complex excited state structure leads to predissociation and involves a host of other kinetic and radiative processes. Part of the work presented in the thesis constitutes a complete and critical review of what is presently known about the electronic structure of O2 in four broad areas: (1)the detailed electronic structure of the first six bound states of O2 (the 0 to ~ 5 eV region), (2)the electronic structures around the B S -u3 state ( ~ 5.5 to 7 eV above the X S - g 3 ), (3)the Rydberg and valence states of both u and g symmetry in the energy region between the dissociation limit of the B S - u3 state and the ionization limit of O2 ( ~ 7 to ~ 12 eV), and (4)a detailed characterization of the d Pg1 Rydberg state and its interaction with several valence states based on analysis of new, laser-based spectroscopic data. Item (1) involves a reevaluation of the results of a number of recent spectroscopic studies and the calculation of the associated potential energy curves by use of the RKR method. Item (2) involves the compilation and presentation of semi-empirical and theoretical potential energy curves based on recent observations and calculations of states near the B S - u3 state. Item (3) involves a comprehensive review of the most recent experimental spectral observations of transitions to Rydberg states of u and g symmetry as well as collection and/or construction of semi-empirical and theoretical potential energy curves. Item (4) was motivated by problems encountered with experimental data during work on item (3) which prompted the present detailed rotational analysis of new high resolution spectra of the d Pg1 - a Dg1 and d Pg1 - b S +g1 transitions. Finally, the potential energy curves for all known electronic states of O2 (both experimental and theoretical) have been collected and summarized.

Morrill, Jeff Stanley

1999-09-01

84

Engineering Very-High-n Polarized Rydberg States Using Tailored Half-Cycle-Pulse Sequences  

Microsoft Academic Search

We show that strongly polarized very-high-n (ñ600) potassium Rydberg atoms can be produced by manipulating lower-n (ñ350) polarized atoms using a tailored sequence of ultrashort half-cycle pulses (HCPs). The protocol for this involves first a weak HCP that generates transient phase-space localization whereupon a second large HCP of opposite polarity excites the electron to a broad distribution of highly elongated

W. Zhao; J. J. Mestayer; J. C. Lancaster; F. B. Dunning; Carlos O Reinhold; S. Yoshida; J. Burgdörfer

2005-01-01

85

Response of highly polarized Rydberg states to trains of half-cycle pulses  

Microsoft Academic Search

The response of very-high- n strongly polarized potassium Rydberg atoms to a sequence of impulsive perturbations provided by a train of short unidirectional electric pulses is investigated. Each pulse, termed a half-cycle pulse (HCP), has a duration Tp≪Tn , where Tn is the classical electron orbital period. Pronounced differences in the survival probability are observed when the sequence of HCPs

C. O. Reinhold; W. Zhao; J. C. Lancaster; F. B. Dunning; E. Persson; D. G. Arbó; S. Yoshida; J. Burgdoerfer

2004-01-01

86

Photoinduced Rydberg ionization spectroscopy of phenol: The structure and assignment of the B˜-state of the cation  

NASA Astrophysics Data System (ADS)

The newly developed technique of photoinduced Rydberg ionization (PIRI) spectroscopy has been successfully applied to study the B˜?X˜ transition in the phenol and phenol-d6 cations. Vibrationally resolved spectra have been obtained for the B˜ state in phenol ion via the origin and the ?6, and ?12 vibrations of the ground ionic state. Similarly, vibrationally resolved spectra for the B˜ state in phenol-d6 ion have been obtained via the origin and ?6 vibration. Calculations to date have suggested the character of the half-filled orbital is ? type, and experimental evidence for the B˜-state assignment so far has been inconclusive. In contrast to previous featureless photoelectron spectra, the main feature in all of the spectra presented here is the presence of several long, low frequency Frank-Condon progressions, suggestive of a large geometry change in the transition. Configuration interaction singles 6-31G* calculations, allowing full geometry optimization, show that the first excited ? state has the OH group rotated 90° from the planar ground state. Therefore, the symmetry for the B˜ state in phenol cation is assigned to be 2p? instead of ?, corresponding to that of benzene and several other monosubstituted benzenes. Further support for this assignment is found in a calculation of the normal mode vibrations, based on the geometry optimized for the excited ? state. These show three low frequency normal modes having a large amount of OH torsion, one of which has a ring motion identical to one of the two normal modes that induces the B˜?X˜ transition in the benzene cation. This calculated normal mode is, therefore, assigned to the most intense and most extensive progression observed in the photoinduced Rydberg ionization spectra.

LeClaire, J. E.; Anand, R.; Johnson, P. M.

1997-05-01

87

An investigation of electronic states of some molecules and molecular cations using mass analyzed threshold ionization and photoinduced Rydberg ionization spectroscopy  

NASA Astrophysics Data System (ADS)

Mass analyzed threshold ionization (MATI) experiments have enabled mapping of the n-dependent Rydberg state survival probability for a series of molecules. Utilizing vacuum and extreme ultraviolet (VUV/XUV) photons, one photon Rydberg manifold spectra of argon, hydrogen chloride, nitrogen, benzene, and oxygen were produced, and the prospects of photoinduced Rydberg ionization (PIRI) experiments examined. It was found that the widths of Rydberg manifolds for the molecules studied are quite different. Hydrogen chloride and nitrogen have the narrowest manifold width, followed by benzene, and then oxygen. These varying widths are most strongly correlated with the angular momentum (i.e., quantum defect) of the initially prepared Rydberg orbital. PIRI experiments required the use of a static cell, rather than a molecular jet assembly, for the more efficient production of higher amounts of VUV/XUV radiation, and hence more Rydberg signal needed to observe PIRI. Armed with the ability to produce tunable VUV/XUV radiation, and to determine the feasibility of a PIRI experiment, the MATI and fragment PIRI spectra of trans-1,3-butadiene (BD) were recorded. The MATI spectrum is vibrationally resolved and was analyzed with the help of ab initio calculations and other published results. The fragment PIRI spectrum of the A<==X transition of BD+ is not vibrationally resolved, but information regarding the wavelength dependence of fragmentation pathways has been gathered and interpreted. It was found that at low photodissociation photon energies, production of C3H3+ dominates, but at higher photon energies, C2H4 + is also produced. The production of each fragment showed a definite PIRI wavelength dependence.

Hofstein, Jason David

1999-11-01

88

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

ERIC Educational Resources Information Center

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

Harbola, Varun

2011-01-01

89

Ground State Hyperfine Structure of Muonic Helium Atom  

E-print Network

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

A. A. Krutov; A. P. Martynenko

2008-07-21

90

The Long-Range Model of High-L Rydberg Fine Structure: A Critical Comparison with Experimental Data  

Microsoft Academic Search

A simple view of the fine structure of non-penetrating Rydberg levels, suggested over 70 years ago [1], was refined to treat the fine structure of helium, lithium [2], and other atoms with S-state ion cores [3]. In this view the ion polarizabilities determine the fine structure pattern. Current experimental techniques provide access to highly excited high-L states in He [4],

Erica L. Snow; Laura E. Wright; Stephen R. Lundeen

2006-01-01

91

Quadratic Zeeman effect in hydrogen Rydberg states: Rigorous error estimates for energy eigenvalues, energy eigenfunctions, and oscillator strengths  

SciTech Connect

A variational method, based on some results due to T. Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], and previously discussed is here applied to the hydrogen atom in uniform magnetic fields of tesla in order to calculate, with a rigorous error estimate, energy eigenvalues, energy eigenfunctions, and oscillator strengths relative to Rydberg states up to just below the field-free ionization threshold. Making use of a basis (parabolic Sturmian basis) with a size varying from 990 up to 5050, we obtain, over the energy range of [minus]190 to [minus]24 cm[sup [minus]1], all of the eigenvalues and a good part of the oscillator strengths with a remarkable accuracy. This, however, decreases with increasing excitation energy and, thus, above [similar to][minus]24 cm[sup [minus]1], we obtain results of good accuracy only for eigenvalues ranging up to [similar to][minus]12 cm[sup [minus]1].

Falsaperla, P.; Fonte, G. (Dipartimento di Fisica,Universita di Catania, Corso Italia 57, I-95129 Catania (Italy) Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Corso Italia 57, I-95129 Catania (Italy))

1994-10-01

92

Rydberg state population due to multicapture processes in Kr[sup q+] (q=17-18) on Kr collisions  

SciTech Connect

Initial population distributions in principal quantum numbers n of excited states were obtained in multicapture processes for Kr[sup q+] (q=17-18) on Kr collisions at low energy ([approx]5 keV/u). Radiative decay curves of Rydberg transitions of the projectivle ions have been measured by shifting the target gas jet along the projectile beam, i.e. perpendicularly to the observation axis. As a result for Kr[sup 18+] projectiles, we have found that an Kr[sup 16+] constant initial population from n=14 to n=19 allows the observed Kr XVII 14--15 radiative decay curve to reproduce relatively well. In addition to this, coincidence time of flight spectroscopy between recoil ion photons and recoil ions have been performed in order to determine the decay curves of recoil ion transitions. We found an initial population distribution centered around n=20 for the 7i--8k transition of Kr VII recoil ion.

Martin, S.; Denis, A.; Delon, A.; Desesquelles, J. (LASIM Universite Lyon 1, Campus de la Doua, F-69622 Villeurbanne Cedex (France)); Ouerdane, Y. (TSI Universite de Saint-Etienne, 23 rue du Dr Paul Michelon, F-4202, Saint-Etienne (France))

1993-06-05

93

Measurement of absolute transition frequencies of {sup 87}Rb to nS and nD Rydberg states by means of electromagnetically induced transparency  

SciTech Connect

We report the measurement of absolute excitation frequencies of {sup 87}Rb to nS and nD Rydberg states. The Rydberg transition frequencies are obtained by observing electromagnetically induced transparency on a rubidium vapor cell. The accuracy of the measurement of each state is < or approx. 1 MHz, which is achieved by frequency stabilizing the two diode lasers employed for the spectroscopy to a frequency comb and a frequency comb calibrated wavelength meter, respectively. Based on the spectroscopic data we determine the quantum defects of {sup 87}Rb, and compare it with previous measurements on {sup 85}Rb. We determine the ionization frequency from the 5S{sub 1/2}(F=1) ground state of {sup 87}Rb to 1010.029 164 6(3)THz, providing the binding energy of the ground state with an accuracy improved by two orders of magnitude.

Mack, Markus; Karlewski, Florian; Hattermann, Helge; Hoeckh, Simone; Jessen, Florian; Cano, Daniel; Fortagh, Jozsef [CQ Center for Collective Quantum Phenomena and their Applications, Physikalisches Institut, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-15

94

Mass transfer of helium, neon, argon, and xenon through a steady-state upper mantle  

Microsoft Academic Search

We have examined the steady-state upper mantle model for helium, neon, argon, and xenon following the mass transfer approach presented by Kellogg and Wasserburg (1990) for helium and Porcelli and Wasserburg (1995a) for xenon. The model explains the available observational data of mantle helium, neon, argon, and xenon isotope compositions and provides specific predictions regarding the rare gas isotopic compositions

D. Porcelli; G. J. Wasserburg

1995-01-01

95

Atomic orientation following predissociation of the C {sup 3}{Pi}{sub g} Rydberg state of molecular oxygen  

SciTech Connect

(2 + 1) resonance enhanced multiphoton ionization in combination with time-of-flight mass spectroscopy (TOF-MS) has been used to detect both the O({sup 3}P) and O({sup 1}D) fragments produced as a result of predissociation of the C {sup 3}{Pi}{sub g} (v= 0) and (v= 1) Rydberg states of O{sub 2}, accessed via two-photon absorption from the ground X {sup 3}{Sigma}{sub g}{sup -} state. In particular, TOF profiles have been recorded at various fixed two-photon absorption wavelengths within the two bands, with circular polarized probe laser light used to probe the angular momentum orientation of these photofragments. All photofragments are found to display coherent orientation resulting from interference between two possible two-photon absorption pathways. The measured orientation is affected by rotational depolarization due to the long lifetime of the excited C state; once this effect is accounted for the orientation is found to be nearly constant over all dissociation wavelengths. The origin of the coherent orientation is attributed to two-photon absorption to different spin-orbit components of the C state.

Gilchrist, A. J.; Ritchie, G. A. D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom)

2013-06-07

96

BF3 valence and Rydberg states as probed by electron energy loss spectroscopy and ab initio calculations.  

PubMed

In this contribution we probe BF3 low-lying excited singlet states measured at 100 eV, 2.8° scattering angle and triplet states at 40 eV, 40° scattering angle, while sweeping the energy loss over the range 10.0-20.0 eV. The electronic state spectroscopy has been investigated and the assignments supported by quantum chemical calculations. This provides the first comprehensive investigation of all singlet and triplet excited electronic states of boron trifluoride up to the first ionization potential. A generalized oscillator strength analysis is employed to derive oscillator strength f0 value and integral cross sections (ICSs) from the corresponding differential cross sections (DCSs). The f0 value is compared with the optical oscillator strength (OOS) from photoabsorption, and the unscaled Born ICSs are then compared with relevant energy and binary-encounter and f-scaled Born cross section (BEf-scaling) results determined as a part of this investigation. The lowest n members of the Rydberg series have been assigned as converging to the lowest ionization energy limits of boron trifluoride and classified according to the magnitude of the quantum defects (?). PMID:25338148

Duflot, D; Hoshino, M; Limão-Vieira, P; Suga, A; Kato, H; Tanaka, H

2014-11-20

97

A New Wide Range Equation of State for Helium-4  

E-print Network

.1 Properties of helium ......................................................................................... 1 1.2 Supply and uses of helium ............................................................................... 5 1.2.1 Helium in cryogenics... glass assures that no bubbles remain trapped in the fiber that might affect normal performance of the glass. The low boiling point of helium is important for purging, pressurizing and for cryogenic applications. This latter use represents the largest...

Ortiz Vega, Diego O

2013-08-01

98

Quantum Incompressibility of a Freely Falling Hydrogen Atom in a Circular Rydberg State, and a Gravitationally-Induced Charge Separation Effect in Superconducting Systems  

Microsoft Academic Search

Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous, and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like

R. Y. Chiao; S. J. Minter; K. Wegter-McNelly; L. A. Martinez

2010-01-01

99

Rydberg excitation assisted light shift blockade in Rb atoms for realizing a collective state quantum bit and quantum memory  

NASA Astrophysics Data System (ADS)

Previously, we had proposed the technique of light shift imbalance induced blockade which leads to a condition where a collection of non-interacting atoms under laser excitation remains combined to a superposition of the ground and the fist excited states, thus realizing a collective state quantum bit which in turn can be used to realize a quantum computer. In this paper, we show first that the light shift imbalance by itself is actually not enough to produce such a blockade, and explain the reason by the limitation of our previous analysis had reached this constraint. We then show that by introducing Rydberg interaction, it is possible to achieve such a blockade for a wide range of parameters. Analytic arguments used to establish these results are confirmed by numerical simulations. The fidelity of coupled quantum gates based on such collective state qubits is highly insensitive to the exact number of atoms in the ensemble. As such, this approach may prove be viable for scalable quantum computing based on neutral atoms.

Tu, Yanfei; Kim, May E.; Shahriar, Selim M.

2014-10-01

100

Determination of the binding energies of the np Rydberg states of H{sub 2}, HD, and D{sub 2} from high-resolution spectroscopic data by multichannel quantum-defect theory  

SciTech Connect

Multichannel quantum-defect theory (MQDT) is used to calculate the electron binding energies of np Rydberg states of H{sub 2}, HD, and D{sub 2} around n = 60 at an accuracy of better than 0.5?MHz. The theory includes the effects of rovibronic channel interactions and the hyperfine structure, and has been extended to the calculation of the asymmetric hyperfine structure of Rydberg states of a heteronuclear diatomic molecule (HD). Starting values for the eigenquantum-defect parameters of MQDT were extracted from ab initio potential-energy functions for the low-lying p Rydberg states of molecular hydrogen and subsequently refined in a global weighted fit to available experimental data on the singlet and triplet Rydberg states of H{sub 2} and D{sub 2}. The electron binding energies of high-np Rydberg states derived in this work represent important quantities for future determinations of the adiabatic ionization energies of H{sub 2}, HD, and D{sub 2} at sub-MHz accuracy.

Sprecher, Daniel; Merkt, Frédéric, E-mail: frederic.merkt@phys.chem.ethz.ch [Laboratorium für Physikalische Chemie, ETH-Zürich, 8093 Zürich (Switzerland)] [Laboratorium für Physikalische Chemie, ETH-Zürich, 8093 Zürich (Switzerland); Jungen, Christian [Laboratoire Aimé Cotton du CNRS, Université de Paris-Sud, 91405 Orsay (France)] [Laboratoire Aimé Cotton du CNRS, Université de Paris-Sud, 91405 Orsay (France)

2014-03-14

101

Millimeter-wave spectroscopy and multichannel quantum-defect-theory analysis of high Rydberg states of xenon: The hyperfine structure of {sup 129}Xe{sup +} and {sup 131}Xe{sup +}  

SciTech Connect

Millimeter-wave transitions between high-n Rydberg states of several isotopes of xenon have been recorded at sub-megahertz resolution. The fine and, for {sup 129}Xe and {sup 131}Xe, hyperfine structures of s, p, d, and f Rydberg states with principal quantum number in the range 52{<=}n{<=}64 have been determined from combination differences and analyzed using multichannel quantum defect theory. Improved eigenquantum defects and channel interaction parameters for the odd- and even-parity Rydberg states of xenon and the hyperfine structure of the {sup 2}P{sub 3/2} ground state of {sup 129}Xe{sup +} and {sup 131}Xe{sup +} have been obtained. Nearly degenerate p and d fine or hyperfine levels are very easily mixed by even weak stray electric fields.

Schaefer, Martin; Raunhardt, Matthias; Merkt, Frederic [Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich (Switzerland)

2010-03-15

102

Hybridization of Rydberg electron orbitals by molecule formation  

E-print Network

The formation of ultralong-range Rydberg molecules is a result of the attractive interaction between Rydberg electron and polarizable ground state atom in an ultracold gas. In the nondegenerate case the backaction of the polarizable atom on the electronic orbital is minimal. Here we demonstrate, how controlled degeneracy of the respective electronic orbitals maximizes this backaction and leads to stronger binding energies and lower symmetry of the bound dimers. Consequently, the Rydberg orbitals hybridize due to the molecular bond.

Gaj, A; Ilzhöfer, P; Löw, R; Hofferberth, S; Pfau, T

2015-01-01

103

Rydberg Atoms Ionisation by Microwave Field and Electromagnetic Pulses  

E-print Network

A simple theory of the Rydberg atoms ionisation by electromagnetic pulses and microwave field is presented. The analysis is based on the scale transformation which reduces the number of parameters and reveals the functional dependencies of the processes. It is shown that the observed ionisation of Rydberg atoms by subpicosecond electromagnetic pulses scale classically. The threshold electric field required to ionise a Rydberg state may be simply evaluated in the photonic basis approach for the quantum dynamics or from the multiphoton ionisation theory.

B. Kaulakys; G. Vilutis

1995-04-10

104

Probing the photoinduced Rydberg ionization process  

NASA Astrophysics Data System (ADS)

The photophysical processes behind the new technique of photoinduced Rydberg ionization (P1RI) spectroscopy have been investigated for benzene. The major limitation to the signal-to-noise attainable using this method has been found to be caused by spontaneous autoionization of the prepared Rydbergs. In addition, some evidence has been found to suggest that the autoionizing transitions, which form the basis of the PIRI technique, only take place when the Rydberg electron is of lower n (and therefore I) than the typical n = 100-200 employed in pulsed field ionization experiments. A new method of recording photoinduced ion core transitions, employing multiphoton photodissociation of the Rydberg core, is also reported. The lighter masses of the fragment ions enable them to be separated from the background of parent ions created by spontaneous autoionization. This method allows the core excitation transition to originate from a vibrationally excited state which previously had produced a prohibitively large background as a result of vibrational autoionization.

Goode, J. G.; Leclaire, I. E.; Johnson, P. M.

1996-12-01

105

Quantum Incompressibility of a Freely Falling Hydrogen Atom in a Circular Rydberg State, and a Gravitationally-Induced Charge Separation Effect in Superconducting Systems  

Microsoft Academic Search

Freely falling point-like objects converge toward the center of the Earth.\\u000aHence the gravitational field of the Earth is inhomogeneous, and possesses a\\u000atidal component. The free fall of an extended quantum mechanical object such as\\u000aa hydrogen atom prepared in a high principal-quantum-number state, i.e. a\\u000acircular Rydberg atom, is predicted to fall more slowly than a classical\\u000apoint-like

R. Y. Chiao; S. J. Minter; K. Wegter-McNelly; L. A. Martinez

2010-01-01

106

One-Dimensional Rydberg Gas in a Magnetoelectric Trap  

SciTech Connect

We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the required linear density of Rydberg atoms.

Mayle, Michael [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany); Hezel, Bernd [Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany); Lesanovsky, Igor [Institut fuer Theoretische Physik, Universitaet Innsbruck, A-6020 Innsbruck (Austria); Schmelcher, Peter [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany); Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany)

2007-09-14

107

LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon  

E-print Network

LBNL-42730 1 Collisional Perturbation of States in Atomic Ytterbium by Helium and Neon D in atomic ytterbium by helium and neon buffer gases are reported. We find upper limits for the quenching and neon. PACS numbers: 34, 11.30.Er, 42.62.Fi (Submitted to Phys. Rev. A) 1. INTRODUCTION The 6s2 1 S0 6s

Pines, Alexander

108

First Application of Engineered Very-High-n Polarized Rydberg States  

Microsoft Academic Search

Direct excitation of very-high-n quasi-one-dimensional (quasi-1D) Stark states in a weak dc field is problematic because stray fields and effective laser linewidths lead to creation of a range of states with no preferred orientation. We show, however, that very-high-n (n ˜ 600) quasi-1D atoms can be engineered from lower-n quasi-1D atoms using a tailored sequence of half cycle pulses (HCPs).

Jeff Mestayer; Wei Zhao; Jim Lancaster; Barry Dunning; Carlos Reinhold; Shuhei Yoshida; Joachim Burgdorfer

2006-01-01

109

Giant cross section for molecular ion formation in ultracold Rydberg gases  

E-print Network

We have studied the associative ionization of a Rydberg atom and a ground state atom in an ultracold Rydberg gas. The measured scattering cross section is three orders of magnitude larger than the geometrical size of the produced molecule. This giant enhancement of the reaction kinetics is due to an efficient directed mass transport which is mediated by the Rydberg electron. We also find that the total inelastic scattering cross section is given by the geometrical size of the Rydberg electron's wavefunction.

Niederprüm, Thomas; Manthey, Torsten; Weber, Tobias M; Ott, Herwig

2015-01-01

110

Electron excitation energy transfer from highly excited Cs atoms forming high Rydberg state atoms and molecules  

Microsoft Academic Search

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

Joergen Lundin; Leif Holmlid

1991-01-01

111

Optical-optical double resonance photoionization spectroscopy of nf Rydberg states of nitric oxide  

E-print Network

calculated, and the results agree closely with experiment. These results combined with circular dichroism, California 94305 Received 21 June 2004; accepted 25 August 2004 The spectra of vibrationally excited nf electronic state with a vibrational quantum number and a rotational quantum number Nc . The total angular

Zare, Richard N.

112

Trapping Rydberg Atoms in an Optical Lattice  

NASA Astrophysics Data System (ADS)

Optical lattice traps for Rydberg atoms are of interest in advanced science and in practical applications. After a brief discussion of these areas of interest, I will review some basics of optical Rydberg-atom trapping. The trapping potential experienced by a Rydberg atom in an optical lattice is given by the spatial average of the free-electron ponderomotive energy weighted by the Rydberg electron's probability distribution. I will then present experimental results on the trapping of ^85Rb Rydberg atoms in a one-dimensional ponderomotive optical lattice (wavelength 1064 nm). The principal methods employed to study the lattice performance are microwave spectroscopy, which is used to measure the lattice's trapping efficiency, and photo-ionization, which is used to measure the dwell time of the atoms in the lattice. I have achieved a 90% trapping efficiency for ^85Rb 50S atoms by inverting the lattice immediately after laser excitation of ground-state atoms into Rydberg states. I have characterized the dwell time of the atoms in the lattice using photo-ionization of 50D5/2 atoms. In continued work, I have explored the dependence of the Rydberg-atom trapping potential on the angular portion of the atomic wavefunction. Distinct angular states exhibit different trapping behavior in the optical lattice, depending on how their wavefunctions are oriented relative to the lattice planes. Specifically, I have measured the lattice potential depth of sublevels of ^85Rb nD atoms (50<=n<=65) in a one-dimensional optical lattice with a transverse DC electric field. The trapping behavior varies substantially for the various angular sublevels, in agreement with theory. The talk will conclude with an outlook into planned experiments.

Anderson, Sarah E.

2012-06-01

113

Electromagnetically induced transparency and fluorescence in blockaded Rydberg atomic system  

SciTech Connect

We investigate the interaction between dark states and Rydberg excitation blockade by using electromagnetically induced transparency (EIT), fluorescence, and four-wave mixing (FWM) signals both theoretically and experimentally. By scanning the frequency detunings of the probe and dressing fields, respectively, we first observe these signals (three coexisting EIT windows, two fluorescence signals, and two FWM signals) under Rydberg excitation blockade. Next, frequency detuning dependences of these signals are obtained, in which the modulated results are well explained by introducing the dressing effects (leading to the dark states) with the corrected factor of the Rydberg excitation blockade. In addition, the variations by changing the principal quantum number n of Rydberg state shown some interesting phenomena resulting from Rydberg blockade are observed. The unique nature of such blockaded signals can have potential application in the demonstration of quantum computing.

Li, Cheng; Zheng, Huaibin; Zhang, Zhaoyang; Yao, Xin; Zhang, Yunzhe; Zhang, Yiqi; Zhang, Yanpeng [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049 (China)] [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, Xi'an Jiaotong University, Xi'an 710049 (China)

2013-10-28

114

Very high Rydberg states /n equals 600/ of carbon in the interstellar gas  

NASA Astrophysics Data System (ADS)

The likelihood and significance of VLF radio recombination lines of carbon in the interstellar medium are assessed by means of calculations for the very high electronic states populations associated with neutral carbon atoms at less than 100 K. It is demonstrated that the carbon n-alpha transitions coincident with absorption features toward Cas A, near 26 MHz, will be in absorption and have a strength and line width compatible with that observed for physical conditions indicated for the bulk of the observed gas toward Cas A. The calculations also suggest that the radio recombination lines may be widely observable under diffuse cloud conditions in the interstellar gas, possessing useful diagnostics. Radio recombination lines at 630-640-alpha involve electrons excited to principal quantum numbers much higher than previously encountered in addition to unprecedentedly low VLF emission frequencies.

Walmsley, C. M.; Watson, W. D.

1982-04-01

115

Simulations of the effect of final state interactions on the scattering reponses of helium droplets  

E-print Network

SIMULATIONS OF THE EFFECT OF FINAL STATE INTERACTIONS ON THE SCATTERING RESPONSES OF HELIUM DROPLETS A Thesis by JIAN YANG Submitted to the Office of Graduate Studies of Texas AgrM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1996 Major Subject: Physics SIMULATIONS OF THE EFFECT OF FINAL STATE INTERACTIONS ON THE SCATTERING RESPONSES OF HELIUM DROPLETS A Thesis by JIAN YANG Submitted to Texas AihM University in partial fulfillment...

Yang, Jian

1996-01-01

116

Progress towards deterministic generation of entangled W-states of neutral atoms using Rydberg blockade  

NASA Astrophysics Data System (ADS)

Every day, millions of cubic feet of natural gas is transported through interstate pipelines and consumed by customers all over the United States of America. Gas distributors, responsible for sending natural gas to individual customers, are eager for an estimate of how much natural gas will be used in the near future. GasHour(TM) software, a reliable forecasting tool from the Marquette University GasDay(TM) lab, has been providing highly accurate hourly forecasts over the past few years. Our goal is to improve current GasHour forecasts, and my thesis presents an approach to achieve that using a blending technique. This thesis includes detailed explanations of the multi-horizon forecasting technique employed by GasHour models. Several graphs are displayed to reveal the structure of hourly forecasts from GasHour. We present SMHF (Smoothing Multi-horizon Forecasts), a step-by-step method showing how a polynomial smoothing technique is applied to current GasHour predications. A slightly different approach of smoothing has also been introduced. We compare RMSEs of both GasHour forecasts and smoothed ones. Different comparisons resulting from different situations have been demonstrated as well. Several conclusions have been reached. Based on the results, blending techniques can improve current GasHour forecasts. We look forward to applying this blending technique to other fields of forecasting.

Gill, Alexander T.

117

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

E-print Network

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

Yavuz, Deniz

118

Transfer of a weakly bound electron in collisions of Rydberg atoms with neutral particles. II. Ion-pair formation and resonant quenching of the Rb(nl) and Ne(nl) States by Ca, Sr, and Ba atoms  

SciTech Connect

Electron-transfer processes are studied in thermal collisions of Rydberg atoms with alkaline-earth Ca(4s{sup 2}), Sr(5s{sup 2}), and Ba(6s{sup 2}) atoms capable of forming negative ions with a weakly bound outermost p-electron. We consider the ion-pair formation and resonant quenching of highly excited atomic states caused by transitions between Rydberg covalent and ionic terms of a quasi-molecule produced in collisions of particles. The contributions of these reaction channels to the total depopulation cross section of Rydberg states of Rb(nl) and Ne(nl) atoms as functions of the principal quantum number n are compared for selectively excited nl-levels with l Much-Less-Than n and for states with large orbital quantum numbers l = n - 1, n - 2. It is shown that the contribution from resonant quenching dominates at small values of n, and the ion-pair formation process begins to dominate with increasing n. The values and positions of the maxima of cross sections for both processes strongly depend on the electron affinity of an alkaline-earth atom and on the orbital angular momentum l of a highly excited atom. It is shown that in the case of Rydberg atoms in states with large l {approx} n - 1, the rate constants of ion-pair formation and collisional quenching are considerably lower than those for nl-levels with l Much-Less-Than n.

Narits, A. A. [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation)] [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation); Mironchuk, E. S. [Moscow Institute of Physics and Technology (State University) (Russian Federation)] [Moscow Institute of Physics and Technology (State University) (Russian Federation); Lebedev, V. S., E-mail: vlebedev@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physics Institute (Russian Federation)

2013-10-15

119

S-states of helium-like ions  

NASA Astrophysics Data System (ADS)

A simple Mathematica (version 7) code for computing S-state energies and wave functions of two-electron (helium-like) ions is presented. The elegant technique derived from the classical papers of Pekeris is applied. The basis functions are composed of the Laguerre functions. The method is based on the perimetric coordinates and specific properties of the Laguerre polynomials. Direct solution of the generalized eigenvalues and eigenvectors problem is used, distinct from the Pekeris works. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of the results and computation times depend on the basis size. The ground state and the lowest triplet state energies can be computed with a precision of 12 and 14 significant figures, respectively. The accuracy of the higher excited states calculations is slightly worse. The resultant wave functions have a simple analytical form, that enables calculation of expectation values for arbitrary physical operators without any difficulties. Only three natural parameters are required in the input. The new version of Mathematica code takes into account the fact that the negative hydrogen ion has only one bound state. New version program summaryProgram title: TwoElAtomSL(SH) Catalogue identifier: AEHY_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHY_v2_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.: 27 998 No. of bytes in distributed program, including test data, etc.: 286 543 Distribution format: tar.gz Programming language: Mathematica 7.0 and 8.0 Computer: Any PC with a Mathematica installation 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 Catalogue identifier of previous version: AEHY_v1_0 Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 1790 Does the new version supersede the previous version?: Yes 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 set of basis functions which are composed of the exponentials combined with the Laguerre polynomials in the perimetric coordinates. Using specific properties of the Laguerre polynomials, solution of the two-electron Schrödinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Reasons for new version: The need to take into account the fact that the negative hydrogen ion ( Z=1) has only one bound (ground) state. Summary of revisions: Minor amendments were made in Cell 2 and Cell 5 of both TwoElAtomSH and TwoElAtomSL programs. Restrictions: Firstly, the too large length of expansion (basis size) takes too much computation time and operative memory giving no perceptible improvement in accuracy. Secondly, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).

Liverts, Evgeny Z.; Barnea, Nir

2012-03-01

120

Spin squeezing in a Rydberg lattice clock.  

PubMed

We theoretically demonstrate a viable approach to spin squeezing in optical lattice clocks via optical dressing of one clock state to a highly excited Rydberg state, generating switchable atomic interactions. For realistic experimental parameters, these interactions are shown to generate over 10 dB of squeezing in large ensembles within a few microseconds and without degrading the subsequent clock interrogation. PMID:24679291

Gil, L I R; Mukherjee, R; Bridge, E M; Jones, M P A; Pohl, T

2014-03-14

121

S-states of helium-like ions  

NASA Astrophysics Data System (ADS)

A simple Mathematica (version 7) code for computing S-state energies and wave functions of two-electron (helium-like) ions is presented. The elegant technique derived from the classical papers of Pekeris (1958, 1959, 1962, 1965, 1971) [1-3] is applied. The basis functions are composed of the Laguerre functions. The method is based on the perimetric coordinates and specific properties of the Laguerre polynomials. Direct solution of the generalized eigenvalues and eigenvectors problem is used, distinct from the Pekeris works. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of the results and computation times depend on the basis size. The ground state and the lowest triplet state energies can be computed with a precision of 12 and 14 significant figures, respectively. The accuracy of the higher excited states calculations is slightly worse. The resultant wave functions have a simple analytical form, that enables calculation of expectation values for arbitrary physical operators without any difficulties. Only three natural parameters are required in the input. The above Mathematica code is simpler than the earlier version (Liverts and Barnea, 2010 [4]). At the same time, it is faster and more accurate. Program summaryProgram title: TwoElAtomSL(SH) Catalogue identifier: AEHY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHY_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.: 11 434 No. of bytes in distributed program, including test data, etc.: 540 063 Distribution format: tar.gz Programming language: Mathematica 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 another physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple set of basis functions which are composed of the exponentials combined with the Laguerre polynomials in the perimetric coordinates. Using specific properties of the Laguerre polynomials, solution of the two-electron Schrödinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Restrictions: First, the too large length of expansion (basis size) takes the too large computation time and operative memory giving no perceptible improvement in accuracy. Second, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).

Liverts, Evgeny Z.; Barnea, Nir

2011-09-01

122

Ultralong-range polyatomic Rydberg molecules formed by a polar perturber  

E-print Network

The internal electric field of a Rydberg atom electron can bind a polar molecule to form a giant ultralong-range stable polyatomic molecule. Such molecules not only share their properties with Rydberg atoms, they possess huge permanent electric dipole moments and in addition allow for coherent control of the polar molecule orientation. In this work, we include additional Rydberg manifolds which couple to the nearly degenerate set of Rydberg states employed in [S. T. Rittenhouse and H. R. Sadeghpour, Phys. Rev. Lett. 104, 243002 (2010)]. The coupling of a set of $(n+3)s$ Rydberg states with the $n(l>2)$ nearly degenerate Rydberg manifolds in alkali metal atoms leads to pronounced avoided crossings in the Born-Oppenheimer potentials. Ultimately, these avoided crossings enable the formation of the giant polyatomic Rydberg molecules with standard two-photon laser photoassociation techniques.

Rittenhouse, Seth T; Schmelcher, P; Sadeghpour, H R

2011-01-01

123

Ultralong-range polyatomic Rydberg molecules formed by a polar perturber  

NASA Astrophysics Data System (ADS)

The internal electric field of a Rydberg atom electron can bind a polar molecule to form a giant ultralong-range stable polyatomic molecule. Such molecules not only share their properties with Rydberg atoms (such as long lifetimes and large sizes) but they also possess huge permanent electric dipole moments and in addition allow for coherent control of the polar molecule orientation. In this work, we include additional Rydberg manifolds which couple to the nearly degenerate set of Rydberg states employed in the previous work (S T Rittenhouse and H R Sadeghpour 2010 Phys. Rev. Lett. 104 243002). The coupling of a set of (n + 3)s Rydberg states with the n(l > 2) nearly degenerate Rydberg manifolds in alkali metal atoms leads to pronounced avoided crossings in the Born-Oppenheimer potentials. Ultimately, these avoided crossings enable the formation of the giant polyatomic Rydberg molecules with standard two-photon laser photoassociation techniques.

Rittenhouse, Seth T.; Mayle, M.; Schmelcher, P.; Sadeghpour, H. R.

2011-09-01

124

Filtering single atoms from Rydberg blockaded mesoscopic ensembles  

E-print Network

We propose an efficient method to filter out single atoms from trapped ensembles with unknown number of atoms. The method employs stimulated adiabatic passage to reversibly transfer a single atom to the Rydberg state which blocks subsequent Rydberg excitation of all the other atoms within the ensemble. This triggers the excitation of Rydberg blockaded atoms to short lived intermediate states and their subsequent decay to untrapped states. Using an auxiliary microwave field to carefully engineer the dissipation, we obtain a nearly deterministic single-atom source. Our method is applicable to small atomic ensembles in individual microtraps and in lattice arrays.

Petrosyan, David; Mølmer, Klaus

2015-01-01

125

Filtering single atoms from Rydberg blockaded mesoscopic ensembles  

E-print Network

We propose an efficient method to filter out single atoms from trapped ensembles with unknown number of atoms. The method employs stimulated adiabatic passage to reversibly transfer a single atom to the Rydberg state which blocks subsequent Rydberg excitation of all the other atoms within the ensemble. This triggers the excitation of Rydberg blockaded atoms to short lived intermediate states and their subsequent decay to untrapped states. Using an auxiliary microwave field to carefully engineer the dissipation, we obtain a nearly deterministic single-atom source. Our method is applicable to small atomic ensembles in individual microtraps and in lattice arrays.

David Petrosyan; D. D. Bhaktavatsala Rao; Klaus Mølmer

2015-01-21

126

Testing time-dependent density functional theory with depopulated molecular orbitals for predicting electronic excitation energies of valence, Rydberg, and charge-transfer states and potential energies near a conical intersection  

SciTech Connect

Kohn-Sham (KS) time-dependent density functional theory (TDDFT) with most exchange-correlation functionals is well known to systematically underestimate the excitation energies of Rydberg and charge-transfer excited states of atomic and molecular systems. To improve the description of Rydberg states within the KS TDDFT framework, Gaiduk et al. [Phys. Rev. Lett. 108, 253005 (2012)] proposed a scheme that may be called HOMO depopulation. In this study, we tested this scheme on an extensive dataset of valence and Rydberg excitation energies of various atoms, ions, and molecules. It is also tested on a charge-transfer excitation of NH{sub 3}-F{sub 2} and on the potential energy curves of NH{sub 3} near a conical intersection. We found that the method can indeed significantly improve the accuracy of predicted Rydberg excitation energies while preserving reasonable accuracy for valence excitation energies. However, it does not appear to improve the description of charge-transfer excitations that are severely underestimated by standard KS TDDFT with conventional exchange-correlation functionals, nor does it perform appreciably better than standard TDDFT for the calculation of potential energy surfaces.

Li, Shaohong L.; Truhlar, Donald G., E-mail: truhlar@umn.edu [Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2014-09-14

127

Wave packet dynamics in triplet states of Na2 attached to helium nanodroplets.  

PubMed

The dynamics of vibrational wave packets excited in Na2 dimers in the triplet ground and excited states is investigated by means of helium nanodroplet isolation (HENDI) combined with femtosecond pump-probe spectroscopy. Different pathways in the employed resonant multiphoton ionization scheme are identified. Within the precision of the method, the wave packet dynamics appears to be unperturbed by the helium droplet environment. PMID:17461563

Claas, Patrick; Droppelmann, Georg; Schulz, Claus Peter; Mudrich, Marcel; Stienkemeier, Frank

2007-08-01

128

OPTICAL PUMPING OF HELIUM IN THE ³S⁠METASTABLE STATE  

Microsoft Academic Search

The alignment of He⁴ atoms in the (n = 2, metastable) ³Si\\/; sub 1\\/ state is described. Metastable atoms are produced by a r-f discharge in a ; glass tube containing a few nim of pure helium, and the one micron pumping light ; (2³P-2 ³S) is provided by a helium lamp. A resonance signal is ; obtained froni radio

F. D. Colegrove; P. A. Franken

1960-01-01

129

Experimental studies of double-well potential energy curves theoretically implied as the representation of the lowest molecular Rydberg states of CdRG (RG = Ne,Ar,Kr) diatomic clusters  

Microsoft Academic Search

The lowest Rydberg state El (3E+) of the CdNe CdAr and CdKr van der Waals complex has been investigated by an optical-optical double resonans (OODR). Two electronic states: AO+(53P1) and B1 (53P1) have been used as intermediates for probing the final E1(63S1) state. We have measured the bound-bound laser excitation spectra of the E12 AO+ transition which correspond to the

M. A. Czajkowski; J. Koperski

2005-01-01

130

Exciton dynamics in emergent Rydberg lattices  

NASA Astrophysics Data System (ADS)

The dynamics of excitons in a one-dimensional ensemble with partial spatial order are studied. During optical excitation, cold Rydberg atoms spontaneously organize into regular spatial arrangements due to their mutual interactions. This emergent lattice is used as the starting point to study resonant energy transfer triggered by driving a nS to n'P transition using a microwave field. The dynamics are probed by detecting the survival probability of atoms in the nS Rydberg state. Experimental data qualitatively agree with our theoretical predictions including the mapping onto the XXZ spin model in the strong-driving limit. Our results suggest that emergent Rydberg lattices provide an ideal platform to study coherent energy transfer in structured media without the need for externally imposed potentials.

Bettelli, S.; Maxwell, D.; Fernholz, T.; Adams, C. S.; Lesanovsky, I.; Ates, C.

2013-10-01

131

Strong-Field Excitation of Helium: Bound State Distribution and Spin Effects  

NASA Astrophysics Data System (ADS)

Using field ionization combined with the direct detection of excited neutral atoms we measured the distribution of principal quantum number n of excited He Rydberg states after strong-field excitation at laser intensities well in the tunneling regime. Our results confirm theoretical predictions from semiclassical and quantum mechanical calculations and simultaneously underpin the validity of the semiclassical frustrated tunneling ionization model. Moreover, since our experimental detection scheme is spin sensitive in the case of He atoms, we show that strong-field excitation leads to strong population of triplet states. The origin of it lies in the fact that high angular momentum states are accessible in strong-field excitation. Thus, singlet-triplet transitions become possible due to the increased importance of spin-orbit interaction rather than due to direct laser induced spin-flip processes.

Zimmermann, H.; Buller, J.; Eilzer, S.; Eichmann, U.

2015-03-01

132

From molecular spectra to a density shift in dense Rydberg gases  

NASA Astrophysics Data System (ADS)

In Rydberg atoms, at least one electron is excited to a state with a high principal quantum number. In an ultracold environment, this low-energy electron can scatter off a ground state atom allowing for the formation of a Rydberg molecule consisting of one Rydberg atom and several ground state atoms. Here we investigate those Rydberg molecules created by photoassociation for the spherically symmetric S-states. A step by step increase of the principal quantum number up to n=111 enables us to go beyond the previously observed dimer and trimer states up to a molecule, where four ground state atoms are bound by one Rydberg atom. The increase of bound atoms and the decreasing binding potential per atom with principal quantum number results finally in an overlap of spectral lines. The associated density-dependent line broadening sets a fundamental limit, for example, for the optical thickness per blockade volume in Rydberg quantum optics experiments.

Gaj, A.; Krupp, A. T.; Balewski, J. B.; Löw, R.; Hofferberth, S.; Pfau, T.

2014-08-01

133

The polaron state of surface electrons on helium covering a structured substrate  

NASA Astrophysics Data System (ADS)

In the temperature range 1.5-2.7 K the conductivity of surface electrons over a liquid helium film that covers a structured silicon substrate containing a regular system of micropores is investigated experimentally. It is found that in the range T ? 2.5 K the conductivity drops sharply, which can be explained by the formation of the autolocalized polaron state of an electron over the helium film. The hypothesis that the polaron state of a surface electron appears in a dense helium vapor was examined by calculating the free energy of the polaron with a minimum showing up when the temperature rises up to a certain critical value, and the dependence of the pressing field is in a qualitative agreement with experimental data on the temperature of the sharp drop in the conductivity. The calculation predicts a dependence of the critical temperature on parameters of the potential acting in a plane of the helium surface and associated with distortion of the helium surface due to the structure of the substrate, which favors the appearance of the localized charge over the helium film.

Smorodin, A. V.; Nikolaenko, V. A.; Sokolov, S. S.

2013-10-01

134

The quadratic Zeeman effect in hydrogen Rydberg series  

Microsoft Academic Search

The authors present the oscillator strengths for dipole transitions to high Rydberg states for hydrogen in a magnetic field of 47 kG. The complex spectra can be largely understood in terms of independent, weakly interacting series.

C. W. Clark; K. T. Taylor

1980-01-01

135

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

Microsoft Academic Search

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

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

2002-01-01

136

Cavity quantum electrodynamics with a Rydberg-blocked atomic ensemble  

SciTech Connect

The realization of a Jaynes-Cummings model in the optical domain is proposed for an atomic ensemble. The scheme exploits the collective coupling of the atoms to a quantized cavity mode and the nonlinearity introduced by coupling to high-lying Rydberg states. A two-photon transition resonantly couples the single-atom ground state |g> to a Rydberg state |e> via a nonresonant intermediate state |i>, but due to the interaction between Rydberg atoms only a single atom can be resonantly excited in the ensemble. This restricts the state space of the ensemble to the collective ground state |G> and the collectively excited state |E> with a single Rydberg excitation distributed evenly on all atoms. The collectively enhanced coupling of all atoms to the cavity field with coherent coupling strengths which are much larger than the decay rates in the system leads to the strong coupling regime of the resulting effective Jaynes-Cummings model. We use numerical simulations to show that the cavity transmission can be used to reveal detailed properties of the Jaynes-Cummings ladder of excited states and that the atomic nonlinearity gives rise to highly nontrivial photon emission from the cavity. Finally, we suggest that the absence of interactions between remote Rydberg atoms may, due to a combinatorial effect, induce a cavity-assisted excitation blockade whose range is larger than the typical Rydberg dipole-dipole interaction length.

Guerlin, Christine [Institute for Quantum Electronics, ETH Zuerich, CH-8093 Zuerich (Switzerland); Thales Research and Technology, Campus Polytechnique, 1 avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Brion, Etienne [Laboratoire Aime Cotton, CNRS, Campus d'Orsay, F-91405, Orsay (France); Esslinger, Tilman [Institute for Quantum Electronics, ETH Zuerich, CH-8093 Zuerich (Switzerland); Moelmer, Klaus [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, University of Aarhus, DK-8000 (Denmark)

2010-11-15

137

Spontaneous avalanche ionization of a strongly blockaded Rydberg gas.  

PubMed

We report the sudden and spontaneous evolution of an initially correlated gas of repulsively interacting Rydberg atoms to an ultracold plasma. Under continuous laser coupling we create a Rydberg ensemble in the strong blockade regime, which at longer times undergoes an ionization avalanche. By combining optical imaging and ion detection, we access the full information on the dynamical evolution of the system, including the rapid increase in the number of ions and a sudden depletion of the Rydberg and ground state densities. Rydberg-Rydberg interactions are observed to strongly affect the dynamics of plasma formation. Using a coupled rate-equation model to describe our data, we extract the average energy of electrons trapped in the plasma, and an effective cross section for ionizing collisions between Rydberg atoms and atoms in low-lying states. Our results suggest that the initial correlations of the Rydberg ensemble should persist through the avalanche. This would provide the means to overcome disorder-induced heating, and offer a route to enter new strongly coupled regimes. PMID:25166173

Robert-de-Saint-Vincent, M; Hofmann, C S; Schempp, H; Günter, G; Whitlock, S; Weidemüller, M

2013-01-25

138

Dislocation-mediated melting of one-dimensional Rydberg crystals  

SciTech Connect

We consider cold Rydberg atoms in a one-dimensional optical lattice in the Mott regime with a single atom per site at zero temperature. An external laser drive with Rabi frequency {Omega} and laser detuning {Delta} creates Rydberg excitations whose dynamics is governed by an effective spin-chain model with (quasi) long-range interactions. This system possesses intrinsically a large degree of frustration resulting in a ground-state phase diagram in the ({Delta},{Omega}) plane with a rich topology. As a function of {Delta}, the Rydberg blockade effect gives rise to a series of crystalline phases commensurate with the optical lattice that form a so-called devil's staircase. The Rabi frequency {Omega}, on the other hand, creates quantum fluctuations that eventually lead to a quantum melting of the crystalline states. Upon increasing {Omega}, we find that generically a commensurate-incommensurate transition to a floating Rydberg crystal that supports gapless phonon excitations occurs first. For even larger {Omega}, dislocations within the floating Rydberg crystal start to proliferate and a second, Kosterlitz-Thouless-Nelson-Halperin-Young dislocation-mediated melting transition finally destroys the crystalline arrangement of Rydberg excitations. This latter melting transition is generic for one-dimensional Rydberg crystals and persists even in the absence of an optical lattice. The floating phase and the concomitant transitions can, in principle, be detected by Bragg scattering of light.

Sela, Eran; Garst, Markus [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Str. 77, DE-50937 Koeln (Germany); Punk, Matthias [Physik Department, Technische Universitaet Muenchen, James-Franck-Strasse, DE-85748 Garching (Germany); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

2011-08-15

139

Rydberg Spectroscopy in an Optical Lattice: Blackbody Thermometry for Atomic Clocks  

SciTech Connect

We show that optical spectroscopy of Rydberg states can provide accurate in situ thermometry at room temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25-30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the strontium clock transition. We demonstrate that magic-wavelength lattices exist for both strontium and ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with 10{sup -16} accuracy provide 10 mK resolution and yield a blackbody uncertainty for the clock transition of 10{sup -18}.

Ovsiannikov, Vitali D. [Physics Department, Voronezh State University, Universitetskaya pl. 1, 394006, Voronezh (Russian Federation); Physics Department, University of Nevada, Reno, Nevada, 89557 (United States); Derevianko, Andrei [Physics Department, University of Nevada, Reno, Nevada, 89557 (United States); Gibble, Kurt [Pennsylvania State University, University Park, Pennsylvania, 16802 (United States)

2011-08-26

140

Rydberg Spectroscopy in an Optical Lattice: Blackbody Thermometry for Atomic Clocks  

E-print Network

We show that optical spectroscopy of Rydberg states can provide accurate {\\em in situ} thermometry at room-temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25 to 30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the Strontium clock transition. We demonstrate that magic wavelength lattices exist for both Strontium and Ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with $10^{-16}$ accuracy provide $10 \\, \\mathrm{mK}$ resolution and yield a blackbody uncertainty for the clock transition of $10^{-18}$.

Vitali D. Ovsiannikov; Andrei Derevianko; Kurt Gibble

2011-07-15

141

Rydberg spectroscopy in an optical lattice: blackbody thermometry for atomic clocks.  

PubMed

We show that optical spectroscopy of Rydberg states can provide accurate in situ thermometry at room temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25-30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the strontium clock transition. We demonstrate that magic-wavelength lattices exist for both strontium and ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with 10(-16) accuracy provide 10 mK resolution and yield a blackbody uncertainty for the clock transition of 10(-18). PMID:21929236

Ovsiannikov, Vitali D; Derevianko, Andrei; Gibble, Kurt

2011-08-26

142

Ultrafast structural dynamics and isomerization in Rydberg-exited Quadricyclane  

SciTech Connect

The quadricyclane - norbornadiene system is an important model for the isomerization dynamics between highly strained molecules. In a breakthrough observation for a polyatomic molecular system of that complexity, we follow the photoionization from Rydberg states in the time-domain to derive a measure for the time-dependent structural dynamics and the time-evolving structural dispersion even while the molecule is crossing electronic surfaces. The photoexcitation to the 3s and 3p Rydberg states deposits significant amounts of energy into vibrational motions. We observe the formation and evolution of the vibrational wavepacket on the Rydberg surface and the internal conversion from the 3p Rydberg states to the 3s state. In that state, quadricyclane isomerizes to norbornadiene with a time constant of {tau}{sub 2} = 136(45) fs. The lifetime of the 3p Rydberg state in quadricyclane is {tau}{sub 1} = 320(31) and the lifetime of the 3s Rydberg state in norbornadiene is {tau}{sub 3} = 394(32).

Rudakov, Fedor M [ORNL

2012-01-01

143

Tune-out wavelengths and landscape-modulated polarizabilities of alkali-metal Rydberg atoms in infrared optical lattices  

NASA Astrophysics Data System (ADS)

Intensity-modulated optical lattice potentials can change sign for an alkali-metal Rydberg atom, and the atoms are not always attracted to intensity minima in optical lattices with wavelengths near the CO2 laser band. Here we demonstrate that such IR lattices can be tuned so that the trapping potential experienced by the Rydberg atom can be made to vanish for atoms in “targeted” Rydberg states. Such state-selective trapping of Rydberg atoms can be useful in controlled cold Rydberg collisions, cooling Rydberg states, and species-selective trapping and transport of Rydberg atoms in optical lattices. We tabulate wavelengths at which the trapping potential vanishes for the ns, np, and nd Rydberg states of Na and Rb atoms and discuss advantages of using such optical lattices for state-selective trapping of Rydberg atoms. We also develop exact analytical expressions for the lattice-induced polarizability for the mz=0 Rydberg states and derive an accurate formula predicting tune-out wavelengths at which the optical trapping potential becomes invisible to Rydberg atoms in targeted l=0 states.

Topcu, Turker; Derevianko, Andrei

2013-11-01

144

Production of very-high-n strontium Rydberg atoms  

NASA Astrophysics Data System (ADS)

The production of very-high-n (n˜300-500) strontium Rydberg atoms is explored using a crossed-laser-atom-beam geometry. n1S0 and n1D2 states are created by two-photon excitation via the 5s5p 1P1 intermediate state using radiation with wavelengths of ˜461 and ˜413 nm. Rydberg atom densities as high as ˜3×105 cm-3 have been achieved, sufficient that Rydberg-Rydberg interactions can become important. The isotope shifts in the Rydberg series limits are determined by tuning the 461-nm light to preferentially excite the different strontium isotopes. Photoexcitation in the presence of an applied electric field is examined. The initially quadratic Stark shift of the n1P1 and n1D2 states becomes near-linear at higher fields and the possible use of n1D2 states to create strongly polarized, quasi-one-dimensional electronic states in strontium is discussed. The data are analyzed with the aid of a two-active-electron (TAE) approximation. The two-electron Hamiltonian, within which the Sr2+ core is represented by a semi-empirical potential, is numerically diagonalized allowing the calculation of the energies of high-n Rydberg states and their photoexcitation probabilities.

Ye, S.; Zhang, X.; Killian, T. C.; Dunning, F. B.; Hiller, M.; Yoshida, S.; Nagele, S.; Burgdörfer, J.

2013-10-01

145

Standoff detection of large organic molecules using Rydberg fingerprint spectroscopy and microwave Rayleigh scattering  

SciTech Connect

We present a technique for nonintrusive and standoff detection of large organic molecules using coherent microwave Rayleigh scattering from plasma produced by structure sensitive photoionization through Rydberg states. We test the method on 1,4-diazobicyclooctane. Transitions between the 3s Rydberg state and higher lying Rydberg states are probed using two-color photoionization with 266?nm photons and photons in the range of 460-2400 nm. Photoionization is detected using microwave radiation, which is scattered by the unbounded electrons. Highly resolved Rydberg spectra are acquired in vacuum and in air.

Rudakov, Fedor M [ORNL; Zhang, Zhili [ORNL

2012-01-01

146

Tailoring Rydberg Wavepackets  

Microsoft Academic Search

Advances in experimental technique now allow study of the behavior of Rydberg atoms subject to one, or more, pulsed unidirectional electric fields, termed half-cycle pulses (HCPs), whose duration is much less than the classical electron orbital period. In this limit, each HCP simply delivers an impulsive momentum transfer or ``kick\\

F. Barry Dunning

2005-01-01

147

The equation of state, electronic thermal conductivity, and opacity of hot dense deuterium-helium plasmas  

NASA Astrophysics Data System (ADS)

Thermophysical properties of dense deuterium-helium plasmas along the 160 g/cm3 isochore with temperatures up to 800 electron-volt are reported. From Kubo-Greenwood formula, the electronic thermal conductivity and Rosseland mean opacity are determined by means of quantum molecular dynamics (QMD) simulations. Equation of states is obtained by QMD and orbital free molecular dynamics. The electronic heat conductance is compared with several models currently used in inertial confinement fusion designs. Our results indicate that only in the weak coupling regime, the opacity is sensitive to the concentration of helium.

Wang, Cong; He, Xian-Tu; Zhang, Ping

2012-04-01

148

Excitation of autoionizing states of helium-like ions by scattering of high-energy particles  

SciTech Connect

The cross sections for two-electron excitations of helium-like atomic systems into the autoionizing 2s{sup 2} ({sup 1}S)- and 2p{sup 2} ({sup 1}S)-states by collisions with high-energy electrons and photons are deduced. The evaluations are performed to the leading order of non-relativistic perturbation theory. The analytical formulas for cross sections are obtained in the form of universal scalings. A comparison of our theoretical predictions with available theoretical and experimental results for the helium atom is made.

Mikhailov, A. I.; Mikhailov, I. A.; Nefiodov, A. V., E-mail: anef@thd.pnpi.spb.ru [B. P. Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Plunien, G. [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)] [Technische Universitaet Dresden, Institut fuer Theoretische Physik (Germany)

2013-03-15

149

Coherent Rydberg Excitation in Thermal Microcells  

NASA Astrophysics Data System (ADS)

In order to create quantum devices based on the Rydberg blockade mechanism, it is necessary to have a confinement of the excitation volume to less than the blockade radius in a frozen gas of atoms; i.e. the excitation times need to be shorter than the timescales of the respective dephasing mechanisms. While ultracold gases seem to be the obvious choice, our approach utilizes thermal atomic vapor in small glass cells [1] which offer multiple advantages like good optical access and scalability. Such a system can be realized by confining the atoms to geometries in the micron regime. Decoherence effects like resonant interactions of the Rydberg atoms with polaritonic excitations in the glass have been studied and can be minimized by the appropriate choice of Rydberg states [2]. Using a bandwidth-limited pulsed laser system for the Rydberg excitation we observe coherent Rabi oscillations on the nanosecond timescale. In collaboration with Renate Daschner, Harald Kuebler, Bernhard Huber, Thomas Baluktsian, Andreas Koelle, James Shaffer, and Tilman Pfau. [4pt] [1] Baluktsian, T., et. al. Opt. Lett. 35, 1950 (2010) [0pt] [2] Kübler, H., et. al. Nature Photon. 4, 112-116 (2010)

Loew, Robert

2011-06-01

150

Photoionization of Alkali-Doped Helium Nanodroplets  

NASA Astrophysics Data System (ADS)

Superfluid helium droplets (He_N) provide a cold, weakly-interacting environment for the investigation of weakly bound molecules. Whereas the host-dopant interaction is weak for neutral molecules, ion impurities may be surrounded by frozen shells of polarized helium atoms. An extreme example of the different behavior is given by alkali metal impurities that stay at the surface of the droplet as neutrals but immerse into the droplet as cations releasing a considerable amount of binding energy. We report measurements of the photoionization efficiency for the rubidium-He_N and cesium-He_N systems and find that the ionization threshold is lowered compared with the free atoms and is in good agreement with Rydberg state spectroscopy of these systems. The corresponding energy shift increases when going from heavy to light alkali metals and from small to large helium droplets. Both effects can be explained by the difference in polarization energies associated with submerged alkali metal cations. The findings agree qualitatively well with recent calculations of helium snowball formation around alkali metal cations. M. Theisen, F. Lackner, G. Krois, and W. E. Ernst, J. Phys. Chem. Lett. 2, 2778 (2011). F. Lackner, G. Krois, M. Theisen, M. Koch, and W. E. Ernst, Phys. Chem. Chem. Phys. 13, 18781 (2011). D. E. Galli, D. M. Ceperley, and L. Reatto, J. Phys. Chem. A 115, 7300 (2011).

Theisen, Moritz; Lackner, Florian; Krois, Günter; Koch, Markus; Ernst, Wolfgang E.

2012-06-01

151

Rydberg atoms in hollow-core photonic crystal fibres  

PubMed Central

The exceptionally large polarizability of highly excited Rydberg atoms—six orders of magnitude higher than ground-state atoms—makes them of great interest in fields such as quantum optics, quantum computing, quantum simulation and metrology. However, if they are to be used routinely in applications, a major requirement is their integration into technically feasible, miniaturized devices. Here we show that a Rydberg medium based on room temperature caesium vapour can be confined in broadband-guiding kagome-style hollow-core photonic crystal fibres. Three-photon spectroscopy performed on a caesium-filled fibre detects Rydberg states up to a principal quantum number of n=40. Besides small energy-level shifts we observe narrow lines confirming the coherence of the Rydberg excitation. Using different Rydberg states and core diameters we study the influence of confinement within the fibre core after different exposure times. Understanding these effects is essential for the successful future development of novel applications based on integrated room temperature Rydberg systems. PMID:24942281

Epple, G.; Kleinbach, K. S.; Euser, T. G.; Joly, N. Y.; Pfau, T.; Russell, P. St. J.; Löw, R.

2014-01-01

152

LETTER TO THE EDITOR: Designing Rydberg wavepackets using trains of half-cycle pulses  

Microsoft Academic Search

A technique for generating Rydberg wavepackets in preferred target states is demonstrated that exploits the mixed phase space structure of the periodically `kicked' Rydberg atom. Experimental data and classical simulations for very-high-n Rydberg atoms are presented that show that application of a train of equispaced, unidirectional half-cycle pulses can lead to localization of the final wavepacket in classical stable islands.

C. O. Reinhold; S. Yoshida; J. Burgdörfer; B. E. Tannian; C. L. Stokely; F. B. Dunning

2001-01-01

153

Systematic errors in angular correlation measurements of the 3 1P state of helium  

Microsoft Academic Search

A Monte Carlo study is made of the effect of several experimental variables on the results of angular correlation experiments. The simulation examines the intensity of the 53.7 nm radiation resulting from the decay of the electron impact excited 3 1P helium state to the 1 1S state at an impact energy of 30 eV. Crossed electron and atomic beams

Ian Humphrey

2002-01-01

154

Equation of State Calculations of Hydrogen-Helium Mixtures in Solar and Extrasolar Giant Planets Burkhard Militzer1  

E-print Network

Equation of State Calculations of Hydrogen-Helium Mixtures in Solar and Extrasolar Giant Planets for hydrogen-helium mixtures at conditions of giant planet interiors of 0.2-2.3 g cm-3 and 1000-80000 K. INTRODUCTION The Kepler mission has provided us with over 2000 exo- planet candidates 1 that vary widely

Militzer, Burkhard

155

Classical Rydberg electron interactions with half-cycle pulses  

NASA Astrophysics Data System (ADS)

We report on classical interactions between sub- picosecond half-cycle pulse (HCP) fields and Rydberg states in atoms. Two experiments are reported. The first uses a HCP pair to create a unique field whose polarization executes a circular rotation for only 1/4 of a field cycle. This field contrasts sharply to more conventional circularly polarized fields that continually circulate about their propagation axis. The ionization response of Sodium Rydberg states due to this field is studied in regimes where the 1/4-cycle field behaves like a rapid, impulsive field or as a slowly varying ramped field, depending on the initial Rydberg state excited. In a surprising result, the ionization response due to the impulsive field shows a remarkable independence of the rapidly varying polarization of the field, in contrast to that from more conventional, circularly polarized fields. The second experiment presented uses a single HCP field to radiatively assist in ion-electron recombination in Calcium. A continuum state is induced in Rydberg atoms using a strong static field, and as much as 10%-15% of the continuum population is recombined. The continuum state exhibits a wildly dynamic behavior over many tens of picoseconds after excitation, depending on the initial Rydberg state and static field strength. There is strong dependence on the orientation of the HCP relative to the static field. Throughout this work, a classical mechanics based numerical analysis has provided valuable insight into the heart of both experiments. Prospects for future work are discussed.

Bensky, Thomas Joseph

156

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

SciTech Connect

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

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

2014-01-14

157

Spectroscopic Observation of Resonant Electric Dipole-Dipole Interactions between Cold Rydberg Atoms  

E-print Network

Atoms K. Afrousheh, P. Bohlouli-Zanjani, D. Vagale, A. Mugford, M. Fedorov, and J. D. D. Martin between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled 85Rb atoms pulse transferred a fraction of these Rydberg atoms to the 46p3=2 state. A second microwave pulse

Le Roy, Robert J.

158

HIGH RESOLUTION MICROWAVE SPECTROSCOPY OF ULTRA COLD RYDBERG ATOMS AS A PROBE OF  

E-print Network

of external electric and magnetic fields. Laser cooling and trapping techniques in a magneto-optical trap (MOTHIGH RESOLUTION MICROWAVE SPECTROSCOPY OF ULTRA COLD RYDBERG ATOMS AS A PROBE OF ELECTRIC, the Rydberg states are very sensitive to external electric field and can be ionized in rather weak fields

Le Roy, Robert J.

159

Two-Atom Rydberg Blockade using Direct 6S to nP Excitation  

E-print Network

We explore a single-photon approach to Rydberg state excitation and Rydberg blockade. Using detailed theoretical models, we show the feasibility of direct excitation, predict the effect of background electric fields, and calculate the required interatomic distance to observe Rydberg blockade. We then measure and control the electric field environment to enable coherent control of Rydberg states. With this coherent control, we demonstrate Rydberg blockade of two atoms separated by 6.6(3) {\\mu}m. When compared with the more common two-photon excitation method, this single-photon approach is advantageous because it eliminates channels for decoherence through photon scattering and AC Stark shifts from the intermediate state while moderately increasing Doppler sensitivity.

A. M. Hankin; Y. -Y. Jau; L. P. Parazzoli; C. W. Chou; D. J. Armstrong; A. J. Landahl; G. W. Biedermann

2014-04-21

160

Ionization states of helium in He-3-rich solar energetic particle events  

NASA Technical Reports Server (NTRS)

Results of a systematic study of the ionic charge state of helium in the energy range 0.6-1.0 MeV/nucleon for He-3-rich solar energetic particle events during the time period August 1978 to October 1979 are reported. The data have been obtained with the Max-Planck-Institut/University of Maryland experiment on ISEE-3. Whereas for solar energetic particle events with no enrichment of He-3 relative to He-4 surprisingly large abundances of singly ionized helium have been reported recently, He-3-rich solar energetic particle events do not show significant abundances of He-3(+). This result is consistent with current theories explaining large compositional anomalies by mass per charge dependent selective heating of the minor ion species.

Klecker, B.; Hovestadt, D.; Moebius, E.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.

1983-01-01

161

An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems  

NASA Astrophysics Data System (ADS)

Recent developments in the study of ultracold Rydberg gases demand an advanced level of experimental sophistication, in which high atomic and optical densities must be combined with excellent control of external fields and sensitive Rydberg atom detection. We describe a tailored experimental system used to produce and study Rydberg-interacting atoms excited from dense ultracold atomic gases. The experiment has been optimized for fast duty cycles using a high flux cold atom source and a three beam optical dipole trap. The latter enables tuning of the atomic density and temperature over several orders of magnitude, all the way to the Bose-Einstein condensation transition. An electrode structure surrounding the atoms allows for precise control over electric fields and single-particle sensitive field ionization detection of Rydberg atoms. We review two experiments which highlight the influence of strong Rydberg-Rydberg interactions on different many-body systems. First, the Rydberg blockade effect is used to pre-structure an atomic gas prior to its spontaneous evolution into an ultracold plasma. Second, hybrid states of photons and atoms called dark-state polaritons are studied. By looking at the statistical distribution of Rydberg excited atoms we reveal correlations between dark-state polaritons. These experiments will ultimately provide a deeper understanding of many-body phenomena in strongly-interacting regimes, including the study of strongly-coupled plasmas and interfaces between atoms and light at the quantum level.

Hofmann, C. S.; Günter, G.; Schempp, H.; Müller, N. L. M.; Faber, A.; Busche, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.

2014-10-01

162

Importance of considering helium excited states in He+ scattering by an aluminum surface  

NASA Astrophysics Data System (ADS)

The He+/Al system is a very interesting projectile-surface combination which was thought initially as an example of a pure Auger neutralization mechanism. Then, because of the measured reionization explained by the antibonding interaction of the projectile state with the core target states, the resonant charge exchange with the band states was considered as another important contribution to the neutralization. Nevertheless, by only considering the neutralization to the ground state of helium, the measured ion survival probability is still overestimated. On the other hand, measurements of electron emission from an Al surface bombarded by He positive ions suggested the possibility of occupied excited states of helium due to the ion-surface collision. In this work, we also include the excited states of He within the time-dependent scattering process in which both neutralization mechanisms, resonant and Auger, are simultaneously contemplated. Our starting point is a multiorbital Anderson Hamiltonian projected over the selected space of ground and excited atomic configurations. An extra term related to the Auger mechanism is added to this Hamiltonian. A difference with previous works is that this approach includes the electron spin and, therefore, the spin fluctuation statistics in the charge-exchange process is correctly taken into account. We find a notable improvement in the agreement with the experiments and also that the interference between both mechanisms is not dramatic.

Iglesias-García, A.; García, Evelina A.; Goldberg, E. C.

2014-11-01

163

Carbon Synthesis in Steady-state Hydrogen and Helium Burning on Accreting Neutron Stars  

NASA Astrophysics Data System (ADS)

Superbursts from accreting neutron stars probe nuclear reactions at extreme densities (? ? 109 g cm-3) and temperatures (T > 109 K). These bursts (~1000 times more energetic than type I X-ray bursts) are most likely triggered by unstable ignition of carbon in a sea of heavy nuclei made during the rapid proton capture process (rp-process) of regular type I X-ray bursts (where the accumulated hydrogen and helium are burned). An open question is the origin of sufficient amounts of carbon, which is largely destroyed during the rp-process in X-ray bursts. We explore carbon production in steady-state burning via the rp-process, which might occur together with unstable burning in systems showing superbursts. We find that for a wide range of accretion rates and accreted helium mass fractions large amounts of carbon are produced, even for systems that accrete solar composition. This makes stable hydrogen and helium burning a viable source of carbon to trigger superbursts. We also investigate the sensitivity of the results to nuclear reactions. We find that the 14O(?, p)17F reaction rate introduces by far the largest uncertainties in the 12C yield.

Stevens, Jeremy; Brown, Edward F.; Cumming, Andrew; Cyburt, Richard; Schatz, Hendrik

2014-08-01

164

Optical imaging of Rydberg atoms  

E-print Network

We present an experiment exploring electromagnetically induced transparency (EIT) in Rydberg atoms in order to observe optical nonlinearities at the single photon level. ??Rb atoms are trapped and cooled using a magneto-optical ...

Mazurenko, Anton

2012-01-01

165

An echo experiment in a strongly interacting Rydberg gas  

E-print Network

When ground state atoms are excited to a Rydberg state, van der Waals interactions among them can lead to a strong suppression of the excitation. Despite the strong interactions the evolution can still be reversed by a simple phase shift in the excitation laser field. We experimentally prove the coherence of the excitation in the strong blockade regime by applying an `optical rotary echo' technique to a sample of magnetically trapped ultracold atoms, analogous to a method known from nuclear magnetic resonance. We additionally measured the dephasing time due to the interaction between the Rydberg atoms.

Ulrich Raitzsch; Vera Bendkowsky; Rolf Heidemann; Björn Butscher; Robert Löw; Tilman Pfau

2007-10-22

166

Photoionisation of a helium atom involving autoionisation states coupled by a circularly polarised laser field  

SciTech Connect

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

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

2005-01-31

167

Learning Approach on the Ground State Energy Calculation of Helium Atom  

SciTech Connect

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

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

2010-07-28

168

Excitation of the n=2 states of helium by positron impact  

SciTech Connect

A high-resolution (DELTAEapprox55 meV) trap-based positron beam has been used to measure absolute scattering cross sections for the excitation of the resolved 2 {sup 1}S,P states of helium at energies between threshold and 38 eV. The experimental integral cross sections, which have typical uncertainties of 10% or less, are compared with several theoretical calculations, and the agreement is generally very favorable. In particular, a new convergent close-coupling approach shows excellent agreement with the experimental data.

Caradonna, Peter; Sullivan, James P.; Jones, Adric; Makochekanwa, Casten; Slaughter, Daniel; Mueller, Dennis W.; Buckman, Stephen J. [ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University Canberra, Australian Capital Territory 0200 (Australia)

2009-12-15

169

Photon-Photon Interactions via Rydberg Blockade  

E-print Network

We develop the theory of light propagation under the conditions of electromagnetically induced transparency (EIT) in systems involving strongly interacting Rydberg states. Taking into account the quantum nature and the spatial propagation of light, we analyze interactions involving few-photon pulses. We demonstrate that this system can be used for the generation of nonclassical states of light including trains of single photons with an avoided volume between them, for implementing photon-photon quantum gates, as well as for studying many-body phenomena with strongly correlated photons.

Alexey V. Gorshkov; Johannes Otterbach; Michael Fleischhauer; Thomas Pohl; Mikhail D. Lukin

2011-03-18

170

Jaynes-Cummings dynamics in mesoscopic ensembles of Rydberg-blockaded atoms  

NASA Astrophysics Data System (ADS)

We show that Jaynes-Cummings dynamics can be observed in mesoscopic atomic ensembles interacting with a classical electromagnetic field in the regime of a Rydberg blockade where the time dynamics of the average number of Rydberg excitations in mesoscopic ensembles displays collapses and revivals typical of this model. As the frequency of Rabi oscillations between collective states of Rydberg-blockaded ensembles depends on the number of interacting atoms, for randomly loaded optical dipole traps, we predict collapses and revivals of Rabi oscillations. We have studied the effects of finite interaction strengths and a finite laser linewidth on the visibility of the revivals. We have shown that observation of collapses and revivals of Rabi oscillations can be used as a signature of the Rydberg blockade without the need to measure the exact number of Rydberg atoms.

Beterov, I. I.; Andrijauskas, T.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A.; Ryabtsev, I. I.; Bergamini, S.

2014-10-01

171

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass  

E-print Network

Metastable pionic helium ($\\pi{\\rm He}^+$) is a three-body atom composed of a helium nucleus, an electron occupying the $1s$ ground state, and a negatively charged pion $\\pi^-$ in a Rydberg state with principal- and orbital angular momentum quantum numbers of $n\\sim \\ell+1\\sim 16$. We calculate the spin-independent energies of the $\\pi{\\rm ^3He}^+$ and $\\pi{\\rm ^4He}^+$ isotopes in the region $n=15$--19. These include relativistic and quantum electrodynamics corrections of orders $R_{\\infty}\\alpha^2$ and $R_{\\infty}\\alpha^3$ in atomic units, where $R_{\\infty}$ and $\\alpha$ denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the $\\pi^-$, and the radiative and Auger decay rates of the states are also calculated. Some states $(n,\\ell)=(16,15)$ and $(17,16)$ retain nanosecond-scale lifetimes against $\\pi^-$ absorption into the helium nucleus. We propose to use laser pulses to induce $\\pi^-$ transitions from these metastable states, to states with large ($\\sim 10^{11}$ s$^{-1}$) Auger rates. The $\\pi{\\rm He}^{2+}$ ion that remains after Auger emission of the $1s$ electron undergoes Stark mixing with the $s$, $p$, and $d$ states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the $\\pi^-$. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge....(continued)

Masaki Hori; Anna Sótér; Vladimir I. Korobov

2014-04-30

172

Simulations of the dissociation of small helium clusters with ab initio molecular dynamics in electronically excited states  

NASA Astrophysics Data System (ADS)

The dynamics resulting from electronic excitations of helium clusters were explored using ab initio molecular dynamics. The simulations were performed with configuration interaction singles and adiabatic classical dynamics coupled to a state-following algorithm. 100 different configurations of He7 were excited into the 2s and 2p manifold for a total of 2800 trajectories. While the most common outcome (90%) was complete fragmentation to 6 ground state atoms and 1 excited state atom, 3% of trajectories yielded bound, He2^*, and <0.5% yielded an excited helium trimer. The nature of the dynamics, kinetic energy release, and connections to experiments are discussed.

Closser, Kristina D.; Gessner, Oliver; Head-Gordon, Martin

2014-04-01

173

Simulations of the dissociation of small helium clusters with ab initio molecular dynamics in electronically excited states  

SciTech Connect

The dynamics resulting from electronic excitations of helium clusters were explored using ab initio molecular dynamics. The simulations were performed with configuration interaction singles and adiabatic classical dynamics coupled to a state-following algorithm. 100 different configurations of He{sub 7} were excited into the 2s and 2p manifold for a total of 2800 trajectories. While the most common outcome (90%) was complete fragmentation to 6 ground state atoms and 1 excited state atom, 3% of trajectories yielded bound, He {sub 2}{sup *}, and <0.5% yielded an excited helium trimer. The nature of the dynamics, kinetic energy release, and connections to experiments are discussed.

Closser, Kristina D.; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Department of Chemistry, University of California Berkeley, Berkeley, California 94720 (United States) [Department of Chemistry, University of California Berkeley, Berkeley, California 94720 (United States); Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Gessner, Oliver [Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2014-04-07

174

Measurement of Holmium Rydberg series through MOT depletion spectroscopy  

E-print Network

We report measurements of the absolute excitation frequencies of $^{165}$Ho $4f^{11}6sns$ and $4f^{11}6snd$ odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range $n=40-101$ yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the $ns$ series around $n=51$ due to an unidentified interloper at 48515.47(4) cm$^{-1}$. From the series convergence, we determine the first ionization potential $E_\\mathrm{IP}=48565.939(4)$ cm$^{-1}$, which is three orders of magnitude more accurate than previous work. This work represents the first time such spectroscopy has been done in Holmium and is an important step towards using Ho atoms for collective encoding of a quantum register.

J. Hostetter; J. D. Pritchard; J. E. Lawler; M. Saffman

2014-12-03

175

Measurement of Holmium Rydberg series through MOT depletion spectroscopy  

E-print Network

We report measurements of the absolute excitation frequencies of $^{165}$Ho $4f^{11}6sns$ and $4f^{11}6snd$ odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range $n=40-101$ yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the $ns$ series around $n=51$ due to an unidentified interloper at 48515.47(4) cm$^{-1}$. From the series convergence, we determine the first ionization potential $E_\\mathrm{IP}=48565.939(4)$ cm$^{-1}$, which is three orders of magnitude more accurate than previous work. This work represents the first time such spectroscopy has been done in Holmium and is an important step towards using Ho atoms for collective encoding of a quantum register.

Hostetter, J; Lawler, J E; Saffman, M

2014-01-01

176

Strongly Coupled Plasmas via Rydberg Blockade of Cold Atoms  

NASA Astrophysics Data System (ADS)

We propose and analyze a new scheme to produce ultracold neutral plasmas deep in the strongly coupled regime. The method exploits the interaction blockade between cold atoms excited to high-lying Rydberg states and therefore does not require substantial extensions of current ultracold plasma experiments. Extensive simulations reveal a universal behavior of the resulting Coulomb coupling parameter, providing a direct connection between the physics of strongly correlated Rydberg gases and ultracold plasmas. The approach is shown to reduce currently accessible temperatures by more than an order of magnitude, which opens up a new regime for ultracold plasma research and cold ion-beam applications with readily available experimental techniques.

Bannasch, G.; Killian, T. C.; Pohl, T.

2013-06-01

177

Strongly coupled plasmas via Rydberg blockade of cold atoms.  

PubMed

We propose and analyze a new scheme to produce ultracold neutral plasmas deep in the strongly coupled regime. The method exploits the interaction blockade between cold atoms excited to high-lying Rydberg states and therefore does not require substantial extensions of current ultracold plasma experiments. Extensive simulations reveal a universal behavior of the resulting Coulomb coupling parameter, providing a direct connection between the physics of strongly correlated Rydberg gases and ultracold plasmas. The approach is shown to reduce currently accessible temperatures by more than an order of magnitude, which opens up a new regime for ultracold plasma research and cold ion-beam applications with readily available experimental techniques. PMID:23829735

Bannasch, G; Killian, T C; Pohl, T

2013-06-21

178

Quantum Spin Ice and dimer models with Rydberg atoms  

E-print Network

Quantum spin ice represents a paradigmatic example on how the physics of frustrated magnets is related to gauge theories. In the present work we address the problem of approximately realizing quantum spin ice in two dimensions with cold atoms in optical lattices. The relevant interactions are obtained by weakly admixing van der Waals interactions between laser admixed Rydberg states to the atomic ground state atoms, exploiting the strong angular dependence of interactions between Rydberg p-states together with the possibility of designing step-like potentials. This allows us to implement Abelian gauge theories in a series of geometries, which could be demonstrated within state of the art atomic Rydberg experiments. We numerically analyze the family of resulting microscopic Hamiltonians and find that they exhibit both classical and quantum order by disorder, the latter yielding a quantum plaquette valence bond solid. We also present strategies to implement Abelian gauge theories using both s- and p-Rydberg states in exotic geometries, e.g. on a 4-8 lattice.

Alexander W. Glaetzle; Marcello Dalmonte; Rejish Nath; Ioannis Rousochatzakis; Roderich Moessner; Peter Zoller

2014-04-21

179

Binding potentials and interaction gates between microwave-dressed Rydberg atoms  

E-print Network

We demonstrate finite range binding potentials between pairs of Rydberg atoms interacting with each other via attractive and repulsive van der Waals potentials and driven by a microwave field. We show that, using destructive quantum interference to cancel single-atom Rydberg excitation, the Rydberg-dimer states can be selectively and coherently populated from the two-atom ground state. This can be used to realize a two-qubit interaction gate which is not susceptible to mechanical forces between the atoms and is therefore immune to motional decoherence.

David Petrosyan; Klaus Mølmer

2014-09-22

180

Ab initio Equation of State data for hydrogen, helium, and water and the internal structure of Jupiter  

E-print Network

The equation of state of hydrogen, helium, and water effects interior structure models of giant planets significantly. We present a new equation of state data table, LM-REOS, generated by large scale quantum molecular dynamics simulations for hydrogen, helium, and water in the warm dense matter regime, i.e.for megabar pressures and temperatures of several thousand Kelvin, and by advanced chemical methods in the complementary regions. The influence of LM-REOS on the structure of Jupiter is investigated and compared with state-of-the-art results within a standard three-layer model consistent with astrophysical observations of Jupiter. Our new Jupiter models predict an important impact of mixing effects of helium in hydrogen with respect to an altered compressibility and immiscibility.

N. Nettelmann; B. Holst; A. Kietzmann; M. French; R. Redmer; D. Blaschke

2008-06-06

181

Quantum Simulation of Helium Hydride in a Solid-State Spin Register  

E-print Network

\\emph{Ab initio} computation of molecular properties is one of the most promising applications of quantum computing. While this problem is widely believed to be intractable for classical computers, efficient quantum algorithms exist which have the potential to vastly accelerate research throughput in fields ranging from material science to drug discovery. Using a solid-state quantum register realized in a nitrogen-vacancy (NV) defect in diamond, we compute the bond dissociation curve of the minimal basis helium hydride cation, HeH$^+$. Moreover, we report an energy uncertainty (given our model basis) of the order of $10^{-14}$ Hartree, which is ten orders of magnitude below desired chemical precision. As NV centers in diamond provide a robust and straightforward platform for quantum information processing, our work provides several important steps towards a fully scalable solid state implementation of a quantum chemistry simulator.

Ya Wang; Florian Dolde; Jacob Biamonte; Ryan Babbush; Ville Bergholm; Sen Yang; Ingmar Jakobi; Philipp Neumann; Alán Aspuru-Guzik; James D. Whitfield; Jörg Wrachtrup

2014-05-12

182

Divalent Rydberg atoms in optical lattices: Intensity landscape and magic trapping  

NASA Astrophysics Data System (ADS)

We develop a theoretical understanding of the trapping of divalent Rydberg atoms in optical lattices. Because the size of the Rydberg electron cloud can be comparable to the scale of spatial variations of laser intensity, we pay special attention to averaging optical fields over the atomic wave functions. The optical potential is proportional to the ac Stark polarizability. We find that in the independent-particle approximation for the valence electrons, this polarizability breaks into two contributions: the singly ionized core polarizability and the contribution from the Rydberg electron. Unlike the usually employed free-electron polarizability, the Rydberg contribution depends both on the laser intensity profile and on the rotational symmetry of the total electronic wave function. We focus on the J =0 Rydberg states of Sr and evaluate the dynamic polarizabilities of the 5sns(1S0) and 5snp(3P0) Rydberg states. We specifically chose the Sr atom for its optical-lattice clock applications. We find that there are several magic wavelengths in the infrared region of the spectrum at which the differential Stark shift between the clock states [5s2(1S0) and 5s5p(3P0)] and the J =0 Rydberg states [5sns(1S0) and 5snp(3P0)] vanishes. We tabulate these wavelengths as a function of the principal quantum number n of the Rydberg electron. We find that because the contribution to the total polarizability from the Rydberg electron vanishes at short wavelengths, magic wavelengths below ˜1000 nm are "universal" as they do not depend on the principal quantum number n.

Topcu, Turker; Derevianko, Andrei

2014-02-01

183

Collision theory of Rydberg atoms with neutral and charged particles  

Microsoft Academic Search

Modern collision theory of Rydberg atoms with neutral and charged particles is presented. Recent results on the excitation, ionization, quenching and broadening of highly excited atomic states are reported. We consider in detail a number of approaches: various versions of perturbation theory, classical and semiclassical methods, Fermi pseudopotential model, impulse approximation and quasimolecular approach. Analytical and numerical methods developed within

I. L Beigman; V. S Lebedev

1995-01-01

184

Coherent ultrafast photoelectron spectroscopy in Br2: an alternative method for measuring Delta v not equal 0 transitions in Rydberg-to-Rydberg excitations.  

PubMed

A two-state vibrational wave packet is prepared in a low-lying 4d[12](1 or 2) Rydberg state of jet cooled Br(2) (4d, v(')=3 and v(')=4) by two-photon excitation with 266.5 nm pulses from an ultrafast laser. The wave packet is detected by autoionization following excitation with time-delayed 800 nm pulses to the n=8 (v(+)=4) and n=9 (v(+)=3) Rydberg states in the (2)Pi(12) angular momentum core state. Autoionization of each state occurs to the (2)Pi(32) state of the ion through spin-orbit ionization. Photoelectron spectroscopy is used to differentiate between the n=8 and n=9 ejected photoelectrons. Detection of the wave packet recurrences via the n=8 and n=9 Rydberg states reveals a pi phase-shift difference of the recurrences between the two final states. In each case, Delta v not equal 0 transitions are observed since wave packet recurrences are detected. By fitting the observed phase change of the recurrences with a simple model for the overlap amplitudes and assumptions about the potentials, we estimate, within the context of the model, that approximately 0.6% of the transitions may be attributed to Delta v= +/- 1 transitions between the initial Rydberg superposition state and the final Rydberg detection state. PMID:16689571

Stavros, Vasilios G; Lau, Lana; Strasser, Daniel; Leone, Stephen R

2006-05-01

185

Correlations of Rydberg excitations in an ultracold gas after an echo sequence  

SciTech Connect

We show that Rydberg states in an ultracold gas can be excited with strongly preferred nearest-neighbor distance if densities are well below saturation. The scheme makes use of an echo sequence in which the first half of a laser pulse excites Rydberg states while the second half returns atoms to the ground state, as in the experiment of Raitzsch et al. [Phys. Rev. Lett. 100, 013002 (2008)]. Near the end of the echo sequence, almost any remaining Rydberg atom is separated from its next-neighbor Rydberg atom by a distance slightly larger than the instantaneous blockade radius halfway through the pulse. These correlations lead to large deviations of the atom-counting statistics from a Poissonian distribution. Our results are based on the exact quantum evolution of samples with small numbers of atoms. Finally, we demonstrate the utility of the {omega} expansion for the approximate description of correlation dynamics through an echo sequence.

Wuester, S.; Stanojevic, J.; Ates, C.; Pohl, T.; Rost, J. M. [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Deuar, P. [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02-668 Warsaw (Poland); Corney, J. F. [ARC Centre of Excellence for Quantum-Atom Optics, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072 (Australia)

2010-02-15

186

Double Excitations of Helium  

NASA Astrophysics Data System (ADS)

The double excitations of helium offer an ideal case for investigating electron dynamics in a three-body system. Our study of the He ^1P^o double excitations comprises measurements of the partial photoionization cross sections ?n (He^+) and the partial photoelectron angular distribution parameters ?n for the series N(K,T)^Ai up to the N=5 threshold. The experiment was performed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 × 10^12 photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K=N-2 are clearly delineated in both ?n and ?_n. The ?n show all minor series with N=K-4 very clearly, in contrast to measurements of the total absorption cross section, as well as very weak members with A=-1. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N=5 and N=6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He^+(n), whereas the peak-to-valley variation in the ?n within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the ?n and ?n of the photoelectron satellites are virtually identical provided the final ionic state He^+(n), n >= 2, is reached via an excited series N with ?=1, or ?=2, where ?=N-n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (N-K), A, and T. We tentatively propose an extension of these systematics for higher series N >= 5, although further theoretical work toward understanding these features of the doubly excited states will be needed. The experiment was performed in close collaboration with C.D. Caldwell, M.O. Krause, S.P. Frigo, and S.B. Whitfield. Valuable theoretical contributions were made by J.-Z. Tang and I. Shimamura. Part of the work appeared in Phys. Rev. Lett. 75, 1479 (1995). This work is supported by the National Science Foundation under grants PHY-9207634 and PHY-9507573.

Menzel, Alexander

1996-05-01

187

Variational calculation for the doubly excited state (2p{sup 2}){sup 3}P{sup e} of helium  

SciTech Connect

Highly precise variational calculations of nonrelativistic energies of the (2p{sup 2}){sup 3}P{sup e} state of the helium atom are presented. We get an upper bound energy E=-0.7105 001 556 5678 a.u., the lowest yet obtained.

Mukherjee, Tapan K.; Mukherjee, Prasanta K. [Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)

2004-06-01

188

Molecular Rydberg transitions. XVI. MCD of CH/sub 3/Br  

SciTech Connect

Magnetic circular dichroism, first derivative (of absorption), and absorption spectra of methyl bromide are presented for the first s--Rydberg transition region, 55 000--61 000 cm/sup -1/. A straightforward analysis in terms of the ratios (MCD/derivative) of the signal amplitudes yields a unique identification of the first s--Rydberg states, /sup 3/E/sub(/sub 1/) and /sup 1/E/sub(/sub 1/). These identifications, in conjunction with oscillator strength ratios and an intermediate coupling model, lead to an assignment of the remaining first s--Rydberg states /sup 3/E/sub(/sub 2/) and /sup 3/E/sub() 0plus-or-minus/. All of these assignments are corroborative of ones based on vibrational analyses and extrapolations (S. Felps, P. Hochmann, P. Brint, and S. P. McGlynn, J. Mol. Spectrosc. 59, 355 (1976)). The power of MCD techniques in VUV Rydberg analyses is strikingly demonstrated.

McGlynn, S.P.; Scott, J.D.; Felps, W.S.; Findley, G.L.

1980-01-01

189

Direct observation of Rydberg-Rydberg transitions via CPmmW spectroscopy  

E-print Network

Rydberg-Rydberg transitions of BaF molecules have been directly observed in our lab. The key to the experimental success is our ability to combine two powerful and new technologies, Chirped-Pulse millimeter-Wave spectroscopy ...

Zhou, Yan, Ph. D. Massachusetts Institute of Technology

2014-01-01

190

Collisional dissociative recombination in helium-hydrogen afterglow plasmas  

NASA Astrophysics Data System (ADS)

The puzzling dependence of electron-ion recombination in helium-hydrogen afterglows on neutralfootnotetextGlos'ik et al., Phys. Rev.A 79, 052707 (2009) and electronfootnotetextGougousi et al., Int. J. Mass Spec. Ion Proc. 149-150, 131 (1995) densities is shown to be compatible with the ``Collisional Dissociative Recombination'' mechanism, originally proposed by Collins,footnotetextCollins, Phys. Rev.A 140, 1850 (1965) in which three-body capture of electrons into molecular high Rydberg states of H3^+ leads to predissociation of the molecular core. While both electrons and neutrals play a role in the three-body capture, their effects on recombination do not add in a simple manner, which makes it difficult to distinguish three-body and binary dissociative recombination. Collision-induced angular momentum mixing (l-mixing), invoked in earlier models, also occurs but does not provide the rate-limiting step that controls the overall recombination rate.

Johnsen, Rainer

2012-10-01

191

Dipole-quadrupole interference spectroscopy: Observation of an autoionizing He 1D Rydberg series  

NASA Astrophysics Data System (ADS)

We have used dipole-quadrupole interference spectroscopy to observe an optically forbidden quadrupole Rydberg series of helium autoionizing levels. The technique measures the forward-backward asymmetry of photoelectron angular distributions produced in the vacuum ultraviolet photoionization of helium. The resonant behavior of this asymmetry in the region of a quadrupole autoionizing level enables the determination of the position, width, and Fano line-profile parameter q of the level. We have obtained these quantities for the He 2(1,0)n+1D Rydberg series for n=2-7. We find that for n?3 all three quantities have the expected n scaling, with a quantum defect of 0.31. For n?3 the average q parameter lies close to zero, whereas for n=2 it is negative.

Krässig, B.; Kanter, E. P.; Southworth, S. H.; Young, L.; Wehlitz, R.; deHarak, B. A.; Martin, N. L. S.

2012-11-01

192

Rotational hybridization, and control of alignment and orientation in triatomic ultralong-range Rydberg molecules  

NASA Astrophysics Data System (ADS)

We explore the electronic structure and rovibrational properties of an ultralong-range triatomic Rydberg molecule formed by a Rydberg atom and a ground state heteronuclear diatomic molecule. We focus here on the interaction of a Rb(n,l?slant 3) Rydberg atom with a KRb(N = 0) diatomic polar molecule. There is significant electronic hybridization with the Rb(n = 24, l?slant 3) degenerate manifold. The polar diatomic molecule is allowed to rotate in the electric fields generated by the Rydberg electron and core as well as an external field. We investigate the metamorphosis of the Born-Oppenheimer potential curves, essential for the binding of the molecule, with varying electric field and analyze the resulting properties such as the vibrational structure and the alignment and orientation of the polar diatomic molecule.

González-Férez, Rosario; Sadeghpour, H. R.; Schmelcher, Peter

2015-01-01

193

Adiabatic quantum computation with Rydberg-dressed atoms  

E-print Network

We study an architecture for implementing adiabatic quantum computation with trapped neutral atoms. Ground state atoms are dressed by laser fields in a manner conditional on the Rydberg blockade mechanism, thereby providing the requisite entangling interactions. As a benchmark we study the performance of a Quadratic Unconstrained Binary Optimization (QUBO) problem whose solution is found in the ground state spin configuration of an Ising-like model. We model a realistic architecture, including details of the atomic implementation, with qubits encoded into the clock states of 133Cs, effective B-fields implemented through stimulated Raman transitions, and atom-atom coupling achieved by excitation to the 100P3/2 Rydberg level. Including the fundamental effects of photon scattering, we find the fidelity of two-qubit implementation to be on the order of 0.99, with higher fidelities possible with improved laser sources.

Tyler Keating; Krittika Goyal; Yuan-Yu Jau; Grant W. Biedermann; Andrew Landahl; Ivan H. Deutsch

2013-08-15

194

Femtosecond time-resolved XUV + UV photoelectron imaging of pure helium nanodroplets.  

PubMed

Liquid helium nanodroplets, consisting of on average 2 × 10(6) atoms, are examined using femtosecond time-resolved photoelectron imaging. The droplets are excited by an extreme ultraviolet light pulse centered at 23.7 eV photon energy, leading to states within a band that is associated with the 1s3p and 1s4p Rydberg levels of free helium atoms. The initially excited states and subsequent relaxation dynamics are probed by photoionizing transient species with a 3.2 eV pulse and using velocity map imaging to measure time-dependent photoelectron kinetic energy distributions. Significant differences are seen compared to previous studies with a lower energy (1.6 eV) probe pulse. Three distinct time-dependent signals are analyzed by global fitting. A broad intense signal, centered at an electron kinetic energy (eKE) of 2.3 eV, grows in faster than the experimental time resolution and decays in ~100 fs. This feature is attributed to the initially excited droplet state. A second broad transient feature, with eKE ranging from 0.5 to 4 eV, appears at a rate similar to the decay of the initially excited state and is attributed to rapid atomic reconfiguration resulting in Franck-Condon overlap with a broader range of cation geometries, possibly involving formation of a Rydberg-excited (He(n))* core within the droplet. An additional relaxation pathway leads to another short-lived feature with vertical binding energies ?2.4 eV, which is identified as a transient population within the lower-lying 1s2p Rydberg band. Ionization at 3.2 eV shows an enhanced contribution from electronically excited droplet states compared to ejected Rydberg atoms, which dominate at 1.6 eV. This is possibly the result of increased photoelectron generation from the bulk of the droplet by the more energetic probe photons. PMID:25381513

Ziemkiewicz, Michael P; Bacellar, Camila; Siefermann, Katrin R; Leone, Stephen R; Neumark, Daniel M; Gessner, Oliver

2014-11-01

195

Femtosecond time-resolved XUV + UV photoelectron imaging of pure helium nanodroplets  

SciTech Connect

Liquid helium nanodroplets, consisting of on average 2 × 10{sup 6} atoms, are examined using femtosecond time-resolved photoelectron imaging. The droplets are excited by an extreme ultraviolet light pulse centered at 23.7 eV photon energy, leading to states within a band that is associated with the 1s3p and 1s4p Rydberg levels of free helium atoms. The initially excited states and subsequent relaxation dynamics are probed by photoionizing transient species with a 3.2 eV pulse and using velocity map imaging to measure time-dependent photoelectron kinetic energy distributions. Significant differences are seen compared to previous studies with a lower energy (1.6 eV) probe pulse. Three distinct time-dependent signals are analyzed by global fitting. A broad intense signal, centered at an electron kinetic energy (eKE) of 2.3 eV, grows in faster than the experimental time resolution and decays in ?100 fs. This feature is attributed to the initially excited droplet state. A second broad transient feature, with eKE ranging from 0.5 to 4 eV, appears at a rate similar to the decay of the initially excited state and is attributed to rapid atomic reconfiguration resulting in Franck-Condon overlap with a broader range of cation geometries, possibly involving formation of a Rydberg-excited (He{sub n})* core within the droplet. An additional relaxation pathway leads to another short-lived feature with vertical binding energies ?2.4 eV, which is identified as a transient population within the lower-lying 1s2p Rydberg band. Ionization at 3.2 eV shows an enhanced contribution from electronically excited droplet states compared to ejected Rydberg atoms, which dominate at 1.6 eV. This is possibly the result of increased photoelectron generation from the bulk of the droplet by the more energetic probe photons.

Ziemkiewicz, Michael P.; Bacellar, Camila; Siefermann, Katrin R.; Neumark, Daniel M. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Leone, Stephen R. [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Gessner, Oliver [Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2014-11-07

196

Relaxation rates of the monopole, magnetic dipole, and electric quadrupole moments of the 3 sup 1 P state of helium  

Microsoft Academic Search

The relaxation rates of the monopole, magnetic dipole, and electric quadrupole moments have been determined for the 3¹{ital P} state of helium excited by electron impact, The data are determined from atomic lifetimes using linear and circular polarization analyzed radiation with the electron-photon delayed coincidence technique. This has permitted the direct observation of the time dependence of all the off-diagonal

J. F. Williams; A. G. Mikosza; J. B. Wang; A. B. Wedding

1992-01-01

197

Relaxation rates of the monopole, magnetic dipole, and electric quadrupole moments of the 31P state of helium  

Microsoft Academic Search

The relaxation rates of the monopole, magnetic dipole, and electric quadrupole moments have been determined for the 31P state of helium excited by electron impact, The data are determined from atomic lifetimes using linear and circular polarization analyzed radiation with the electron-photon delayed coincidence technique. This has permitted the direct observation of the time dependence of all the off-diagonal elements

J. F. Williams; A. G. Mikosza; J. B. Wang; A. B. Wedding

1992-01-01

198

Tuning ultracold chemical reactions via Rydberg-dressed interactions.  

PubMed

We show that ultracold chemical reactions with an activation barrier can be tuned using Rydberg-dressed interactions. Scattering in the ultracold regime is sensitive to long-range interactions, especially when weakly bound (or quasibound) states exist near the collision threshold. We investigate how, by Rydberg dressing a reactant, one enhances its polarizability and modifies the long-range van der Waals collision complex, which can alter chemical reaction rates by shifting the position of near-threshold bound states. We carry out a full quantum mechanical scattering calculation for the benchmark system H(2)+D, and show that resonances can be moved substantially and that rate coefficients at cold and ultracold temperatures can be increased by several orders of magnitude. PMID:25062202

Wang, Jia; Byrd, Jason N; Simbotin, Ion; Côté, R

2014-07-11

199

Robust quantum logic in neutral atoms via adiabatic Rydberg dressing  

E-print Network

We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a $\\sigma_+/\\sigma_-$ orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of $^{133}$Cs, we predict that our protocol could produce a CZ gate in $<10$ $\\mu$s with error probability on the order of $10^{-3}$.

Tyler Keating; Robert L. Cook; Aaron Hankin; Yuan-Yu Jau; Grant W. Biedermann; Ivan H. Deutsch

2015-02-23

200

Robust quantum logic in neutral atoms via adiabatic Rydberg dressing  

NASA Astrophysics Data System (ADS)

We study a scheme for implementing a controlled-Z (cz) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a ?+/?- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a cz gate in <10 ? s with error probability on the order of 10-3.

Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan-Yu; Biedermann, Grant W.; Deutsch, Ivan H.

2015-01-01

201

Entropy and complexity analysis of hydrogenic Rydberg atoms  

SciTech Connect

The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Cramer-Rao, Fisher-Shannon, and Lopez Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associated generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l= 0), circular (l=n- 1), and quasicircular (l=n- 2) states is explicitly done.

Lopez-Rosa, S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla (Spain); Toranzo, I. V.; Dehesa, J. S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada (Spain); Sanchez-Moreno, P. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain) [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Matematica Aplicada, Universidad de Granada, 18071-Granada (Spain)

2013-05-15

202

Tuning Ultracold Chemical Reactions via Rydberg-Dressed Interactions  

NASA Astrophysics Data System (ADS)

We show that ultracold chemical reactions with an activation barrier can be tuned using Rydberg-dressed interactions. Scattering in the ultracold regime is sensitive to long-range interactions, especially when weakly bound (or quasibound) states exist near the collision threshold. We investigate how, by Rydberg dressing a reactant, one enhances its polarizability and modifies the long-range van der Waals collision complex, which can alter chemical reaction rates by shifting the position of near-threshold bound states. We carry out a full quantum mechanical scattering calculation for the benchmark system H2+D, and show that resonances can be moved substantially and that rate coefficients at cold and ultracold temperatures can be increased by several orders of magnitude.

Wang, Jia; Byrd, Jason N.; Simbotin, Ion; Côté, R.

2014-07-01

203

Controlling ultracold chemical reactions via Rydberg-dressed interactions  

E-print Network

We show that ultracold chemical reactions can be manipulated and controlled by using Rydberg-dressed interactions. Scattering in the ultracold regime is sensitive to long-range interactions, especially when weakly bound (or quasi-bound) states exist near the collision threshold. We investigate how, by Rydberg-dressing a reactant, one enhances its polarizability and modifies the long-range van der Waals collision complex, which can alter chemical reaction rates by shifting the position of near threshold bound states. We carry out a full quantum mechanical scattering calculation for the benchmark system H$_2$+D, and show that resonances can be moved substantially and that rate coefficients at cold and ultracold temperatures can be increased by several orders of magnitude.

Jia Wang; Jason N. Byrd; Ion Simbotin; R. Côté

2014-03-24

204

Patterned Rydberg excitation and ionisation with a spatial light modulator  

E-print Network

We demonstrate the ability to excite atoms at well-defined, programmable locations in a magneto-optical trap, either to the continuum (ionisation), or to a Rydberg state. To this end, excitation laser light is shaped into arbitrary intensity patterns with a spatial light modulator. These optical patterns are sensitive to aberrations of the phase of the light field, occuring while traversing the optical beamline. These aberrations are characterised and corrected without observing the actual light field in the vacuum chamber.

R. M. W. van Bijnen; C. Ravensbergen; D. J. Bakker; G. J. Dijk; S. J. J. M. F. Kokkelmans; E. J. D. Vredenbregt

2014-07-25

205

Rydberg atom-Ion Collisions: Quantum Theory of Intrashell Transitions  

Microsoft Academic Search

Intrashell transitions in Rydberg atom induced by distant collision with charge particle are considered as a quantum close coupling problem with {ital n}² channels included. The {ital closed}-{ital form} {ital exact} {ital solution} for the initial {ital ns} state of H atom is obtained based on efficient use of the Fock{close_quote}s O(4) symmetry group. The results are applicable to the

A. K. Kazansky; V. N. Ostrovsky

1996-01-01

206

Calculation of Rydberg energy levels for the francium atom  

NASA Astrophysics Data System (ADS)

Based on the weakest bound electron potential model theory, the Rydberg energy levels and quantum defects of the np2Po1/2 (n = 7-50) and np2Po3/2 (n = 7-50) spectrum series for the francium atom are calculated. The calculated results are in excellent agreement with the 48 measured levels, and 40 energy levels for highly excited states are predicted.

Huang, Shi-Zhong; Chu, Jin-Min

2010-06-01

207

Calculation of Rydberg energy levels for the francium atom  

Microsoft Academic Search

Based on the weakest bound electron potential model theory, the Rydberg energy levels and quantum defects of the np2Po1\\/2 (n = 7-50) and np2Po3\\/2 (n = 7-50) spectrum series for the francium atom are calculated. The calculated results are in excellent agreement with the 48 measured levels, and 40 energy levels for highly excited states are predicted.

Shi-Zhong Huang; Jin-Min Chu

2010-01-01

208

Patterned Rydberg excitation and ionization with a spatial light modulator  

NASA Astrophysics Data System (ADS)

We demonstrate the ability to excite atoms at well-defined, programmable locations in a magneto-optical trap, either to the continuum (ionization), or to a Rydberg state. To this end, excitation laser light is shaped into arbitrary intensity patterns with a spatial light modulator. These optical patterns are sensitive to aberrations of the phase of the light field, occurring while traversing the optical beamline. These aberrations are characterized and corrected without observing the actual light field in the vacuum chamber.

van Bijnen, R. M. W.; Ravensbergen, C.; Bakker, D. J.; Dijk, G. J.; Kokkelmans, S. J. J. M. F.; Vredenbregt, E. J. D.

2015-02-01

209

Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass  

NASA Astrophysics Data System (ADS)

Metastable pionic helium (?He+) is a three-body atom composed of a helium nucleus, an electron occupying the 1s ground state, and a negatively charged pion ?- in a Rydberg state with principal and orbital angular momentum quantum numbers of n ˜?+1˜16. We calculate the spin-independent energies of the ?3He+ and ?4He+ isotopes in the region n =15-19. These include relativistic and quantum electrodynamics corrections of orders R??2 and R??3 in atomic units, where R? and ? denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the ?- and the radiative and Auger decay rates of the states are also calculated. Some states (n,?)=(16,15) and (17,16) retain nanosecond-scale lifetimes against ?- absorption into the helium nucleus. We propose the use of laser pulses to induce ?- transitions from these metastable states to states with large (˜1011 s-1) Auger rates. The ?He2+ ion that remains after Auger emission of the 1s electron undergoes Stark mixing with the s, p, and d states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the ? -. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge. A resonance curve is obtained from which the ?He+ transition frequency can in principle be determined with a fractional precision of 10-8-10-6 provided the systematic uncertainties can be controlled. By comparing the measured ?He+ frequencies with the calculated values, the ?- mass may be determined with a similar precision. The ?He+ will be synthesized by allowing a high-intensity (>108 s-1) beam of ?-produced by a cyclotron to come to rest in a helium target. The precise time structure of the ?- beam is used to ensure a sufficient rate of coincidence between the resonant laser pulses and the ?He+ atoms.

Hori, Masaki; Sótér, Anna; Korobov, Vladimir I.

2014-04-01

210

Collective Excitation of Rydberg-Atom Ensembles beyond the Superatom Model  

NASA Astrophysics Data System (ADS)

In an ensemble of laser-driven atoms involving strongly interacting Rydberg states, the steady-state excitation probability is usually substantially suppressed. In contrast, here we identify a regime in which the Rydberg excited fraction is enhanced by the interaction. This effect is associated with the buildup of many-body coherences induced by coherent multiphoton excitations between collective states. The excitation enhancement should be observable under currently existing experimental conditions and may serve as a direct probe for the presence of coherent multiphoton dynamics involving collective quantum states.

Gärttner, Martin; Whitlock, Shannon; Schönleber, David W.; Evers, Jörg

2014-12-01

211

Review of cold Rydberg atoms and their applications  

NASA Astrophysics Data System (ADS)

We present an introductory review of the latest advancements cold Rydberg atom research. First, we briefly summarize the exaggerated properties of Rydberg atoms, and we discuss the new perspectives of Rydberg atom research that has been enabled by laser cooling and trapping technique. We then highlight the latest developments and achievements in the newly emerged research fields for Rydberg molecules and cold neutral plasmas. Various applications of the Rydberg blockade effect for quantum optics and quantum information science are also reviewed.

Lim, Jongseok; Lee, Han-gyeol; Ahn, Jaewook

2013-08-01

212

Doppler-corrected Balmer spectroscopy of Rydberg positronium  

NASA Astrophysics Data System (ADS)

The production of long-lived Rydberg positronium (Ps) and correction for Doppler shifts in the excitation laser frequencies are crucial elements of proposed measurements of the gravitational freefall of antimatter and for precision measurements of the optical spectrum of Ps. Using a two-step optical transition via 2P levels, we have prepared Ps atoms in Rydberg states up to the term limit. The spectra are corrected for the first-order Doppler shift using measured velocities, and the Balmer transitions are resolved for 15?n?31. The excitation signal amplitude begins to decrease for n >50, consistent with the onset of motional electric field ionization in the 3.5-mT magnetic field at the Ps formation target.

Jones, A. C. L.; Hisakado, T. H.; Goldman, H. J.; Tom, H. W. K.; Mills, A. P.; Cassidy, D. B.

2014-07-01

213

Physics of Ultra-cold and Rydberg Plasmas  

SciTech Connect

Here we discuss collective processes and plasma effects that can be found in ultra-cold matter. First, we consider the ultra-cold atomic gas that can be produced in a magneto-optical trap. Due to the existence of long-range repulsive forces, new collective oscillation can take place, resembling sound waves but with a cut-off frequency. We also examine new phenomena in Rydberg plasmas, resulting from laser ionization of the ultra-cold gas. In these very low temperature plasmas a large amount of excited Rydberg states can exist, leading to a new dispersion relation for the electromagnetic waves. Enhanced magnetic field generation will also be considered. Finally, we discuss the collective properties of Bose Einstein condensates, showing a strong analogy with collective plasma processes. Two related examples are given as an illustration: Bogoliubov oscillations in the condensate, and two-stream instabilities of counter-streaming BECs.

Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

2010-06-15

214

Photoionization of helium-like ions accompanied by the excitation of p-wave states of the residual atom  

SciTech Connect

The single-photon ionization of the ground state of a helium-like multicharged ion, which is accompanied by a simultaneous excitation of the residual ion to the np states, is studied using nonrelativistic pertubation theory with respect to the electron-electron interaction. Formulas describing the cross section for the process being studied are obtained. These formulas exhibit a scaling behavior in the target-nucleus charge number Z and in the principal quantum number n. Numerical calculations are performed for nonrelativistic energies including the near-threshold region.

Mikhailov, A. I.; Nefiodov, A. V., E-mail: anef@thd.pnpi.spb.ru [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)

2011-02-15

215

PHYSICAL REVIEW A 86, 053401 (2012) Electric-field sensing near the surface microstructure of an atom chip using cold Rydberg atoms  

E-print Network

of an atom chip using cold Rydberg atoms J. D. Carter, O. Cherry, and J. D. D. Martin Department of Physics fields near the heterogeneous metal-dielectric surface of an atom chip were measured using cold atoms. The atomic sensitivity to electric fields was enhanced by exciting the atoms to Rydberg states that are 108

Le Roy, Robert J.

216

Two body and multibody interaction in a cold Rydberg gas  

NASA Astrophysics Data System (ADS)

Cold Rydberg atoms trapped in a Magneto Optical Trap (MOT) are not isolated and they tend to bond through dipole-dipole and multiple-multiple interactions between Rydberg atoms. The dipole-dipole interaction and van der Waals interaction between two atoms have been intensively studied. However, the fact that the dipole-dipole interaction and van der Waals interaction show the same size of broadening, studied by Raithel's group, and there is transition between two molecular states, studied by Farooqi and Overstreet, can not be explained by the two atom picture. The purpose of this paper is to show the multibody nature of a dense cold Rydberg gas by studying the molecular state microwave spectrum. Specifically, single body, two body and three body interaction regions are separated. Moreover, the multibody energy levels for selected geometries are calculated. In addition, multibody blockade will be discussed. [3pt] [1] A. Reinhard, K. C. Younge, T. Cubel Liebisch, B. Knuffman, P. R. Berman, and G. Raithel, Phys. Rev. Lett. 100, 233201 (2008).[0pt] [2] S.M. Farooqi, D. Tong, S. Krishnan, J. Stanojevic,Y.P. Zhang, J.R. Ensher, A.S. Estrin, C. Boisseau, R. Cote, E.E. Eyler, and P.L. Gould, Phys. Rev. Lett. 91, 183002 (2003).[0pt] [3] K. Richard Overstreet, Arne Schwettmann, Jonathan Tallant, and James P. Shaffer, Phys. Rev. A 76, 011403 (2007).

Han, Jianing; Gallagher, Tom

2009-05-01

217

Dynamics of oxygen Rydberg atom generation following O 1s inner-shell excitation of H{sub 2}O  

SciTech Connect

The emission of low-energy electrons from H{sub 2}O has been investigated at photon excitation energies in the vicinity of the O 1s ionization threshold. Neutral oxygen Rydberg atoms (O*) were found to form, and the correlation between the initial inner-shell excited state of H{sub 2}O and the Rydberg state of O* was determined. The initially excited electron in a Rydberg orbital is shown to remain associated with O* even after the cleavage of two O-H bonds. We also show that the energy discrepancy between two Rydberg states of H{sub 2}O and O* can be explained by the influence of the post-collision interaction, which becomes stronger as the excitation energy approaches the 1s ionization threshold.

Gejo, T., E-mail: gejo@sci.u-hyogo.ac.jp; Ikegami, T.; Honma, K. [University of Hyogo, Koto 3-2-1, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Takahashi, O. [Hiroshima University, 2-2 Kagamiyama 1-chome, Higashihiroshima 739-8512 (Japan); Shigemasa, E. [UVSOR Facility, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan); Hikosaka, Y. [Department of Environmental Science, Niigata University, 8050, Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Tamenori, Y. [JASRI, Koto 1-1-1, Sayo-cho, Hyogo 679-5198 (Japan)

2014-06-07

218

The Role of Helium Metastable States in Radio-Frequency Helium-Oxygen Atmospheric Pressure Plasma Jets: Measurement and Numerical Simulation  

NASA Astrophysics Data System (ADS)

Absolute densities of metastable He atoms were measured line-of sight integrated along the plasma channel of a capacitively-coupled radio-frequency driven atmospheric pressure plasma jet operated in helium oxygen mixtures by tunable diode-laser absorption spectroscopy. Dependencies of the He metastable density with oxygen admixtures up to 1 percent were investigated. Results are compared to a 1-d numerical simulation, which includes a semi-kinetical treatment of the electron dynamics and the complex plasma chemistry (20 species, 184 reactions), and very good agreement is found. The main formation mechanisms for the helium metastables are identified and analyzed, including their pronounced spatio-temporal dynamics. Penning ionization through helium metastables is found to be significant for plasma sustainment, while it is revealed that helium metastables are not an important energy carrying species into the jet effluent and therefore will not play a direct role in remote surface treatments.

Niemi, Kari; Waskoenig, Jochen; Sadeghi, Nader; Gans, Timo; O'Connell, Deborah

2011-11-01

219

Experimental Determination of the Lifetime for the 2p3d(1P0) Helium Doubly Excited State  

NASA Astrophysics Data System (ADS)

Two recent theoretical studies [

C. Liu et al., Phys. Rev. APLRAAN1050-2947 64, 010501 (2001)
;
M. Žitnik et al., ibid. 65, 032520 (2002)
] predict that the fluorescence lifetimes of helium doubly excited states converging to He+ N=2 should be longer than that of the He+ 2p ion state. This effect is caused by the electric field of the outer electron which, through Stark mixing, gives the inner fluorescing electron some series specific, stabilizing 2s character. We have obtained the first experimental evidence that confirms this effect by measuring the lifetime of the 2p3d(1P0) doubly excited state. This was determined to be 190±30 ps compared to 100 ps for the He+ 2p ion state. The measurements were performed using short pulses of synchrotron radiation to form doubly excited states and recording the arrival time of photons from fluorescence.

Lambourne, J. G.; Penent, F.; Lablanquie, P.; Hall, R. I.; Ahmad, M.; Žitnik, M.; Bu?ar, K.; Odling-Smee, M. K.; Harries, J. R.; Hammond, P.; Waterhouse, D. K.; Stranges, S.; Richter, R.; Alagia, M.; Coreno, M.; Ferianis, M.

2003-04-01

220

Two-Stage Melting in Systems of Strongly Interacting Rydberg Atoms  

SciTech Connect

We analyze the ground state properties of a one-dimensional cold atomic system in a lattice, where Rydberg excitations are created by an external laser drive. In the classical limit, the ground state is characterized by a complete devil's staircase for the commensurate solid structures of Rydberg excitations. Using perturbation theory and a mapping onto an effective low-energy Hamiltonian, we find a transition of these commensurate solids into a floating solid with algebraic correlations. For stronger quantum fluctuations the floating solid eventually melts within a second quantum phase transition and the ground state becomes paramagnetic.

Weimer, Hendrik; Buechler, Hans Peter [Institute of Theoretical Physics III, Universitaet Stuttgart, 70550 Stuttgart (Germany)

2010-12-03

221

Angular-momentum couplings in long-range Rb$_2$ Rydberg molecules  

E-print Network

We study angular-momentum couplings in $^{87}$Rb$_2$ Rydberg molecules formed between Rydberg and 5S$_{1/2}$ ground-state atoms. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering of the Rydberg electron with the 5S$_{1/2}$ atom, along with the fine structure coupling of the Rydberg atom and hyperfine structure coupling of the 5S$_{1/2}$ atom. We discuss the effects of these couplings on the adiabatic molecular potentials. We obtain bound-state energies, lifetimes, and electric and magnetic dipole moments for the vibrational ground states of the $^{87}$Rb$(n$D$+5$S$_{1/2})$ molecules in all adiabatic potentials, with fine and hyperfine structure included. We also study the effect of the hyperfine structure on the deep $^3$S-wave- and $^3$P-wave-dominated adiabatic molecular potentials, which support high-$\\ell$ $^{87}$Rb$_2$ Rydberg molecules.

David A. Anderson; Stephanie A. Miller; Georg Raithel

2014-09-08

222

Dipolar Rydberg-atom gas prepared by adiabatic passage through an avoided crossing  

E-print Network

The passage of cold cesium 49S$_{1/2}$ Rydberg atoms through an electric-field-induced multi-level avoided crossing with nearby hydrogen-like Rydberg levels is employed to prepare a cold, dipolar Rydberg atom gas. When the electric field is ramped through the avoided crossing on time scales on the order of 100~ns or slower, the 49S$_{1/2}$ population adiabatically transitions into high-\\emph{l} Rydberg Stark states. The adiabatic state transformation results in a cold gas of Rydberg atoms with large electric dipole moments. After a waiting time of about $1~\\mu$s and at sufficient atom density, the adiabatically transformed highly dipolar atoms become undetectable, enabling us to discern adiabatic from diabatic passage behavior through the avoided crossing. We attribute the state-selectivity to $m$-mixing collisions between the dipolar atoms. The data interpretation is supported by numerical simulations of the passage dynamics and of binary $m$-mixing collisions.

Wang, Limei; Zhang, Linjie; Li, Changyong; Yang, Yonggang; Zhao, Jianming; Raithel, Georg; Jia, Suotang

2015-01-01

223

Simultaneous measurements of super-radiance at multiple wavelengths from helium excited states: (I) Experiment  

E-print Network

In this paper, we report the results of measurements of the intensities and delays of super-radiance decays from excited helium atoms at multiple wavelengths. The experiment was performed using extreme ultraviolet radiation produced by the free electron laser at the SPring-8 Compact SASE Source test accelerator facility as an excitation source. We observed super-radiant transitions on the $1s3p \\to 1s2s$ ($\\lambda=$502 nm), $1s3d \\to 1s2p$ ($\\lambda=$668 nm), and $1s3s \\to 1s2p$ ($\\lambda=$728 nm) transitions. The pulse energy of each transition and its delay time were measured as a function of the target helium gas density. Several interesting features of the data, some of which appear to contradict with the predictions of the simple two-level super-radiance theory, are pointed out.

Nakajima, Kyo; Iwayama, Hiroshi; Kuma, Susumu; Miyamoto, Yuki; Nagasono, Mitsuru; Ohae, Chiaki; Togashi, Tadashi; Yabashi, Makina; Shigemasa, Eiji; Sasao, Noboru

2014-01-01

224

Thermodynamic properties of helium  

SciTech Connect

This volume offers reliable data on the thermodynamic properties of helium over a wide variety of conditions. Spanning temperatures between the lambda line and 1500 K and pressures up to 100 MPa, these data are vital to helium extraction from natural gases and to the design of cryogenic apparatus. The equations of state are considered along with the construction of a single equation of state. 175 references.

Sychev, V.V.; Vasserman, A.A.; Kozlov, A.D.; Spiridonov, G.A.; Tsymarnyi, V.A.

1987-01-01

225

Anisotropic emission of neutral atoms: evidence of an anisotropic Rydberg sheath in nanoplasma  

NASA Astrophysics Data System (ADS)

Intense laser-produced plasma is a complex amalgam of ions, electrons and atoms both in ground and excited states. Little is known about the spatial composition of the excited states that are an integral part of most gaseous or cluster plasma. In cluster-plasma, Rydberg excitations change the charge composition of the ions through charge transfer reactions and shape the angular distributions. Here, we demonstrate a non-invasive technique that reveals the anisotropic Rydberg excited cluster sheath by measuring anisotropy in fast neutral atoms. The sheath is stronger in the direction of light polarization and the enhanced charge transfer by the excited clusters results in larger neutralization.

Rajeev, R.; Madhu Trivikram, T.; Rishad, K. P. M.; Krishnamurthy, M.

2015-02-01

226

Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields  

SciTech Connect

The ionization dynamics of circular Rydberg states in strong circularly polarized infrared (800 nm) laser fields is studied by means of numerical simulations with the time-dependent Schroedinger equation. We find that at certain intensities, related to the radius of the Rydberg states, atomic stabilization sets in, and the ionization probability decreases as the intensity is further increased. Moreover, there is a strong dependence of the ionization probability on the rotational direction of the applied laser field, which can be understood from a simple classical analogy.

Askeland, S.; Soerngaard, S. A.; Nepstad, R.; Foerre, M. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Pilskog, I. [Department of Physics and Technology, University of Bergen, N-5007 Bergen (Norway); Laboratoire de Chimie Physique - Matiere et Rayonnement, Universite Pierre et Marie Curie - CNRS (UMR 7614), F-75231 Paris Cedex 05 (France)

2011-09-15

227

Out-of-equilibrium structures in strongly interacting Rydberg gases with dissipation  

NASA Astrophysics Data System (ADS)

The nonequilibrium dynamics of a gas of cold atoms in which Rydberg states are off-resonantly excited is studied in the presence of noise. The interplay between interaction and off-resonant excitation leads to an initial dynamics where aggregates of excited Rydberg atoms slowly nucleate and grow, eventually reaching long-lived metastable arrangements which then relax further on much longer time scales. This growth dynamics is governed by an effective Master equation which permits a transparent and largely analytical understanding of the underlying physics. By means of extensive numerical simulations we study the many-body dynamics and the correlations of the resulting nonequilibrium states in various dimensions. Our results provide insight into the dynamical richness of strongly interacting Rydberg gases in noisy environments, and highlight the usefulness of these kinds of systems for the exploration of soft-matter-type collective behavior.

Lesanovsky, Igor; Garrahan, Juan P.

2014-07-01

228

Storage and Control of Optical Photons Using Rydberg Polaritons  

NASA Astrophysics Data System (ADS)

We use a microwave field to control the quantum state of optical photons stored in a cold atomic cloud. The photons are stored in highly excited collective states (Rydberg polaritons) enabling both fast qubit rotations and control of photon-photon interactions. Through the collective read-out of these pseudospin rotations it is shown that the microwave field modifies the long-range interactions between polaritons. This technique provides a powerful interface between the microwave and optical domains, with applications in quantum simulations of spin liquids, quantum metrology and quantum networks.

Maxwell, D.; Szwer, D. J.; Paredes-Barato, D.; Busche, H.; Pritchard, J. D.; Gauguet, A.; Weatherill, K. J.; Jones, M. P. A.; Adams, C. S.

2013-03-01

229

Controlling the interactions of a few cold Rb Rydberg atoms by radio-frequency-assisted Förster resonances  

NASA Astrophysics Data System (ADS)

Long-range interactions between cold Rydberg atoms, which are used in many important applications, can be enhanced using Förster resonances between collective many-body states controlled by an external electric field. Here we report on the first experimental observation of highly resolved radio-frequency-assisted Förster resonances in a few cold Rb Rydberg atoms. We also observed radio-frequency-induced Förster resonances which cannot be tuned by a dc electric field. They imply an efficient transition from van der Waals to resonant dipole-dipole interaction due to Floquet sidebands of Rydberg levels appearing in the rf field. This method can be applied to enhance the interactions of almost arbitrary Rydberg atoms with large principal quantum numbers.

Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A.; Beterov, I. I.; Andreeva, C.; Ryabtsev, I. I.

2014-10-01

230

The role of helium metastable states in radio-frequency driven helium-oxygen atmospheric pressure plasma jets: measurement and numerical simulation  

NASA Astrophysics Data System (ADS)

Absolute densities of metastable He(23S1) atoms were measured line-of-sight integrated along the discharge channel of a capacitively coupled radio-frequency driven atmospheric pressure plasma jet operated in technologically relevant helium-oxygen mixtures by tunable diode-laser absorption spectroscopy. The dependences of the He(23S1) density in the homogeneous-glow-like ?-mode plasma with oxygen admixtures up to 1% were investigated. The results are compared with a one-dimensional numerical simulation, which includes a semi-kinetical treatment of the pronounced electron dynamics and the complex plasma chemistry (in total 20 species and 184 reactions). Very good agreement between measurement and simulation is found. The main formation mechanisms for metastable helium atoms are identified and analyzed, including their pronounced spatio-temporal dynamics. Penning ionization through helium metastables is found to be significant for plasma sustainment, while it is revealed that helium metastables are not an important energy carrying species into the jet effluent and therefore will not play a direct role in remote surface treatments.

Niemi, K.; Waskoenig, J.; Sadeghi, N.; Gans, T.; O'Connell, D.

2011-10-01

231

Spectroscopy of triplet states of Rb{sub 2} by femtosecond pump-probe photoionization of doped helium nanodroplets  

SciTech Connect

The dynamics of vibrational wave packets in triplet states of rubidium dimers (Rb{sub 2}) formed on helium nanodroplets are studied using femtosecond pump-probe photoionization spectroscopy. Due to fast desorption of the excited Rb{sub 2} molecules off the droplets and due to their low internal temperature, wave-packet oscillations can be followed up to very long pump-probe delay times > or approx. 1.5 ns. In the first-excited triplet state (1){sup 3}{sigma}{sub g}{sup +}, full and fractional revivals are observed with high contrast. Fourier analysis provides high-resolution vibrational spectra which are in excellent agreement with ab initio calculations.

Mudrich, M.; Heister, Ph.; Hippler, T.; Giese, Ch.; Stienkemeier, F. [Physikalisches Institut, Universitaet Freiburg, 79104 Freiburg (Germany); Dulieu, O. [Laboratoire Aime Cotton, CNRS, Universite Paris-Sud, Batiment 505, 91405 Orsay (France)

2009-10-15

232

Universal time-evolution of a Rydberg lattice gas with perfect blockade  

E-print Network

We investigate the dynamics of a strongly interacting spin system that is motivated by current experimental realizations of strongly interacting Rydberg gases in lattices. In particular we are interested in the temporal evolution of quantities such as the density of Rydberg atoms and density-density correlations when the system is initialized in a fully polarized state without Rydberg excitations. We show that in the thermodynamic limit the expectation values of these observables converge at least logarithmically to universal functions and outline a method to obtain these functions. We prove that a finite one-dimensional system follows this universal behavior up to a given time. The length of this universal time period depends on the actual system size. This shows that already the study of small systems allows to make precise predictions about the thermodynamic limit provided that the observation time is sufficiently short. We discuss this for various observables and for systems with different dimensions, interaction ranges and boundary conditions.

B. Olmos; R. González-Férez; I. Lesanovsky; L. Velázquez

2012-03-02

233

Surface-electrode decelerator and deflector for Rydberg atoms and molecules  

NASA Astrophysics Data System (ADS)

A surface-electrode decelerator and deflector for Rydberg atoms and molecules has been developed with the goal of performing collisional experiments. Translationally cold H2 molecules in a supersonic beam were excited to Rydberg-Stark states of principal quantum number n =31, loaded into electric traps moving at a predetermined speed above the surface of a bent printed circuit board, decelerated, and deflected from the original direction of the supersonic beam by an angle of 10?. The phase-space characteristics of the deflected beam were characterized by measuring the time-of-flight distribution and images of the Rydberg molecules and comparing them to the results of numerical particle-trajectory simulations. More than 1000 H2 molecules were deflected per experimental cycle at a repetition rate of 25 Hz. The phase-space characteristics of the deflector make it attractive to study ion-molecule reactions at low collision energies.

Allmendinger, P.; Deiglmayr, J.; Agner, J. A.; Schmutz, H.; Merkt, F.

2014-10-01

234

l-mixing and nl-changing collisions of Rydberg atoms with rare-gas atoms  

NASA Astrophysics Data System (ADS)

Semiclassical calculations of the quasielastic l-mixing and inelastic n,l-changing processes in thermal collisions of Rydberg sodium atoms with the rare gas atoms as well as Li(nD) and Rb(nS) atoms with Ne are presented in a wide range of the principal quantum numbers. We use the semiclassical normalized perturbation theory (V.S. Lebedev and I.I. Fabrikant, Phys. Rev. A 54), 2888 (1996). for the Rydberg atom collisions with ground-state neutral atoms combined with the modified effective range theory for scattering of slow electrons by the rare gas atoms. We show the importance of the Ramsauer-Townsend effect for inelastic transition with large energy transfer. The polarization interaction between the Rydberg electron and the Ne atom provides the major contribution to the cross sections of both l-mixing and n,l-changing collisions. Its inclusion leads to better agreement with experimental data.

Fabrikant, I. I.; Lebedev, V. S.

1997-04-01

235

Sub-Poissonian Statistics of Jamming Limits in Ultracold Rydberg Gases  

E-print Network

Several recent experiments have established by measuring the Mandel Q parameter that the number of Rydberg excitations in ultracold gases exhibits sub-Poissonian statistics. This effect is attributed to the Rydberg blockade that occurs due to the strong interatomic interactions between highly-excited atoms. Because of this blockade effect, the system can end up in a state in which all particles are either excited or blocked: a jamming limit. We analyze appropriately constructed random-graph models that capture the blockade effect, and derive formulae for the mean and variance of the number of Rydberg excitations in jamming limits. This yields an explicit relationship between the Mandel Q parameter and the blockade effect, and comparison to measurement data shows strong agreement between theory and experiment.

Jaron Sanders; Matthieu Jonckheere; Servaas Kokkelmans

2015-04-10

236

Measurement of holmium Rydberg series through magneto-optical trap depletion spectroscopy  

NASA Astrophysics Data System (ADS)

We report measurements of the absolute excitation frequencies of 165Ho 4 f116 s n s and 4 f116 s n d odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range n =40 -101 yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the n s series around n =51 due to an unidentified interloper at 48515.47(4) cm-1. From the series convergence, we determine the first ionization potential EIP=48565.910 (3 ) cm-1, which is three orders of magnitude more accurate than previous work. This work is an important step towards using Ho atoms for collective encoding of a quantum register.

Hostetter, J.; Pritchard, J. D.; Lawler, J. E.; Saffman, M.

2015-01-01

237

EVOLUTION OF THE RELATIONSHIPS BETWEEN HELIUM ABUNDANCE, MINOR ION CHARGE STATE, AND SOLAR WIND SPEED OVER THE SOLAR CYCLE  

SciTech Connect

The changing relationships between solar wind speed, helium abundance, and minor ion charge state are examined over solar cycle 23. Observations of the abundance of helium relative to hydrogen (A{sub He} {identical_to} 100 Multiplication-Sign n{sub He}/n{sub H}) by the Wind spacecraft are used to examine the dependence of A{sub He} on solar wind speed and solar activity between 1994 and 2010. This work updates an earlier study of A{sub He} from 1994 to 2004 to include the recent extreme solar minimum and broadly confirms our previous result that A{sub He} in slow wind is strongly correlated with sunspot number, reaching its lowest values in each solar minima. During the last minimum, as sunspot numbers reached their lowest levels in recent history, A{sub He} continued to decrease, falling to half the levels observed in slow wind during the previous minimum and, for the first time observed, decreasing even in the fastest solar wind. We have also extended our previous analysis by adding measurements of the mean carbon and oxygen charge states observed with the Advanced Composition Explorer spacecraft since 1998. We find that as solar activity decreased, the mean charge states of oxygen and carbon for solar wind of a given speed also fell, implying that the wind was formed in cooler regions in the corona during the recent solar minimum. The physical processes in the coronal responsible for establishing the mean charge state and speed of the solar wind have evolved with solar activity and time.

Kasper, J. C.; Stevens, M. L.; Korreck, K. E.; Maruca, B. A.; Kiefer, K. K. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Schwadron, N. A. [Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824 (United States); Lepri, S. T. [Department of Atmospheric, Oceanic and Space Studies, University of Michigan, Ann Arbor, MI 48109 (United States)

2012-02-01

238

Coherent manipulation of cold Rydberg atoms near the surface of an atom chip  

NASA Astrophysics Data System (ADS)

Coherent superpositions of the 49s1/2 and 48s1/2 Rydberg states of cold 87Rb atoms were studied near the surface of an atom chip. The superpositions were created and manipulated using microwaves resonant with the two-photon 49s1/2-48s1/2 transition. Coherent behavior was observed using Rabi flopping, Ramsey sequences, spin echo, and spin locking. These results are discussed in the context of Rydberg atoms as electric field noise sensors. We consider the coherence of systems quadratically coupled to noise fields with 1/f? power spectral densities (??1).

Carter, J. D.; Martin, J. D. D.

2013-10-01

239

Lamb shift of electronic states in neutral muonic helium, an electron-muon-nucleus system  

NASA Astrophysics Data System (ADS)

Neutral muonic helium is an exotic atomic system consisting of an electron, a muon, and a nucleus. Being a three-body system, it possesses a clear hierarchy. This allows us to consider it as a hydrogenlike atom with a compound nucleus, which is, in turn, another hydrogenlike system. There are a number of corrections to the Bohr energy levels, all of which can be treated as contributions of generic hydrogenlike theory. While the form of those contributions is the same for all hydrogenlike atoms, their relative numerical importance differs from atom to atom. Here, the leading contribution to the (electronic) Lamb shift in neutral muonic helium is found in a closed analytic form together with the most important corrections. We believe that the Lamb shift in neutral muonic hydrogen is measurable, at least through a measurement of the (electronic) 1 s -2 s transition. We present a theoretical prediction for the 1 s -2 s transitions with an uncertainty of 3 ppm (9 GHz ), as well as for the 2 s -2 p Lamb shift with an uncertainty of 1.3 GHz .

Karshenboim, Savely G.; Ivanov, Vladimir G.; Amusia, Miron

2015-03-01

240

The Long-Range Model of High-L Rydberg Fine Structure: A Critical Comparison with Experimental Data..  

NASA Astrophysics Data System (ADS)

A simple view of the fine structure of non-penetrating Rydberg levels, suggested over 70 years ago [1], was refined to treat the fine structure of helium, lithium [2], and other atoms with S-state ion cores [3]. In this view the ion polarizabilities determine the fine structure pattern. Current experimental techniques provide access to highly excited high-L states in He [4], Li [5], Mg, SiIII [6], and Ba[7], and a test of the long-range model is possible with the availability of independent theoretical calculations. A critical comparison of the data treated with the long-range model will be made to the a-priori calculations of the ionic polarizabilities. [1] Joseph E. Mayer and Maria Goeppert Mayer, Phys. Rev. 43 605 (1933). [2] Richard J. Drachman and A. K. Bhatia, Phys. Rev. A 51 2926 (1995). [3] C. Laughlin, J. Phys. B: At. Mol. Opt. Phys. 28 2787 (1995). [4] G. D. Stevens and S. R. Lundeen, Comments on At. and Mol. Phys., Comments on Mod. Phys. 1,D 207 (2000). [5] C. H. Storry, N. E. Rothery, and E. A. Hessels, Phys. Rev. A 55 128 (1997). [6] R. A. Komara et. al., J. Phys. B: At. Mol. Opt. Phys. 38 S87 (2005). [7] E.L. Snow, et. al. Phys. Rev. A 71, 022510 (2005)

Snow, Erica L.; Wright, Laura E.; Lundeen, Stephen R.

2006-05-01

241

New Measurement of the Rydberg Constant Using Polarization Spectroscopy of H?  

NASA Astrophysics Data System (ADS)

We have determined a new Rydberg value, R?=109 737.314 76(32) cm-1, from an absolute wavelength measurement of the 2S12-3P12 component of the hydrogen Balmer-? line. Polarization spectroscopy of a mild helium-hydrogen discharge with a cw dye laser provided a threefold higher accuracy than the only previous Doppler-free measurement. Another twofold improvement can be obtained by a more precise wavelength measurement of a near-coincident 127I2 reference line.

Goldsmith, J. E. M.; Weber, E. W.; Hänsch, T. W.

1978-11-01

242

Observation of relativistic E x e vibronic coupling in Rb3 and K3 quartet states on helium droplets.  

PubMed

Spectroscopy of alkali-metal complexes on helium droplets (He(N), N=1000-10 000) provides the unique opportunity to observe high-spin species, which exhibit prominent spin-orbit (SO) effects. In this work we present laser-induced-fluorescence and magnetic-circular-dichroism (MCD) spectra of the (2)(4)E(')<--(1)(4)A(2) (') band of Rb(3) and K(3) on He(N). For Rb(3) we find a progression of four SO split bands, weakly perturbed by linear vibronic [Jahn-Teller (JT)] coupling. The K(3) transition was previously observed and interpreted in terms of linear and quadratic JT effects in the (2)(4)E(') state [J. H. Reho et al., J. Chem. Phys. 115, 10265 (2001)]. The structure of the MCD spectrum, however, clearly reveals the importance of SO coupling also for the K(3) transition and suggests a different assignment with weak linear JT and nonsignificant quadratic JT coupling. The observed strong C-type MCD spectra arise from different populations of the ground-state Zeeman sublevels. Thus a quantitative analysis allows a determination of the spin temperature, and since alkali-metal complexes are situated on the surface of the helium droplet this corresponds to a determination of the surface temperature. Our results from the trimer spectra are consistent with the value of approximately 0.4 K, which is found in the interior of a droplet and which we already confirmed for the surface from the spectra of triplet-state alkali-metal dimers in a previous work. PMID:19044963

Auböck, G; Nagl, J; Callegari, C; Ernst, W E

2008-09-21

243

Observation of relativistic E ?e vibronic coupling in Rb3 and K3 quartet states on helium droplets  

NASA Astrophysics Data System (ADS)

Spectroscopy of alkali-metal complexes on helium droplets (HeN, N =1000-10000) provides the unique opportunity to observe high-spin species, which exhibit prominent spin-orbit (SO) effects. In this work we present laser-induced-fluorescence and magnetic-circular-dichroism (MCD) spectra of the (2)E'4?(1)A2'4 band of Rb3 and K3 on HeN. For Rb3 we find a progression of four SO split bands, weakly perturbed by linear vibronic [Jahn-Teller (JT)] coupling. The K3 transition was previously observed and interpreted in terms of linear and quadratic JT effects in the (2)E'4 state [J. H. Reho et al., J. Chem. Phys. 115, 10265 (2001)]. The structure of the MCD spectrum, however, clearly reveals the importance of SO coupling also for the K3 transition and suggests a different assignment with weak linear JT and nonsignificant quadratic JT coupling. The observed strong C-type MCD spectra arise from different populations of the ground-state Zeeman sublevels. Thus a quantitative analysis allows a determination of the spin temperature, and since alkali-metal complexes are situated on the surface of the helium droplet this corresponds to a determination of the surface temperature. Our results from the trimer spectra are consistent with the value of ?0.4K, which is found in the interior of a droplet and which we already confirmed for the surface from the spectra of triplet-state alkali-metal dimers in a previous work.

Auböck, G.; Nagl, J.; Callegari, C.; Ernst, W. E.

2008-09-01

244

The kicked Rydberg atom: Regular and stochastic motion  

SciTech Connect

We have investigated the dynamics of a three-dimensional classical Rydberg atom driven by a sequence of pulses. Both the deterministic system with periodic pulses and the closely related ''noisy'' system with random pulses have been studied in parallel. The Lyapunov exponent is calculated as a function of pulse height and the angular momentum of the initial state. We find differences between noisy and deterministic perturbations to be most pronounced for small pulse heights. Low angular momentum orbits show enhanced diffusion in agreement with recent experimental data for ion-solid interaction. 22 refs., 6 figs.

Burgdoerfer, J.

1988-01-01

245

Landau-Zener Transitions in Frozen Pairs of Rydberg Atoms  

SciTech Connect

We have induced adiabatic transitions in pairs of frozen Rydberg sodium atoms of a supersonic beam. The diatomic ns+ns{yields}np+(n-1)p transition takes place in a time-dependent electric field and originates from the adiabatic change of the internal state of the pair induced by the dipole-dipole interaction. This is experimentally achieved by sweeping an electric field across the energy degeneracy ns ns-np(n-1)p. Our results fully agree with a two-level Landau-Zener model in the diatom system.

Saquet, Nicolas; Cournol, Anne; Beugnon, Jerome; Robert, Jacques; Pillet, Pierre; Vanhaecke, Nicolas [Laboratoire Aime Cotton, CNRS, Batiment 505, Universite Paris-Sud, 91405 Orsay (France)

2010-04-02

246

Effect of dispersion forces on squeezing with Rydberg atoms  

NASA Technical Reports Server (NTRS)

We report exact results concerning the effect of dipole-dipole interaction (dispersion forces) on dynamic and steady-state characteristics of squeezing in the emitted fluorescent field from two identical coherently driven two-level atoms. The atomic system is subjected to three different damping baths in particular the normal vacuum, a broad band thermal field and a broad band squeezed vacuum. The atomic model is the Dicke model, hence possible experiments are most likely to agree with theory when performed on systems of Rydberg atoms making microwave transitions. The presence of dipole-dipole interaction can enhance squeezing for realizable values of the various parameters involved.

Ng, S. K.; Muhamad, M. R.; Wahiddin, M. R. B.

1994-01-01

247

Atom control and gravity measurements using Rydberg positronium  

NASA Astrophysics Data System (ADS)

We consider some of the obstacles that will have to be overcome in order to perform a direct measurement of the gravitational free-fall of positronium atoms. Foremost among these are the production of positronium atoms in a cryogenic environment, efficient excitation of these atoms to suitably long-lived Rydberg states, and their subsequent control via the interaction of their large electric dipole moments with inhomogeneous electric fields. Recent developments in all of these areas can be directly applied to a positronium free-fall gravity measurement, making such an endeavour both timely and feasible.

Cassidy, D. B.; Hogan, S. D.

2014-05-01

248

Abundances, charge states, and energy spectra of helium and heavy ions during solar particle events  

NASA Technical Reports Server (NTRS)

Carbon and oxygen energy spectra observed during several solar events indicate a systematic deviation of these spectra from a simple power law: the spectra bend down below about 100 keV/nuc and the amount of this bending is highly correlated with the size of the flare, as measured by the 'event averaged' flux of 130-220 keV protons. The energy spectra of helium computed for the same time periods do not show a similar feature. A large variability of the alpha/CNO ratio is found from event to event (from 2 to about 20 at 40 keV/nuc), and in all cases examined the carbon and oxygen nuclei are nearly fully stripped. These results are interpreted as evidence for storage of energetic ions in hot coronal regions, followed by strong adiabatic deceleration.

Gloeckler, G.; Sciambi, R.; Fan, C. Y.; Hovestadt, D.

1975-01-01

249

Scaling the neutral-atom Rydberg gate quantum computer by collective encoding in holmium atoms  

E-print Network

Scaling the neutral-atom Rydberg gate quantum computer by collective encoding in holmium atoms M register encoding in the hyperfine ground states of the rare-earth atom holmium. We present a detailed analysis of operation of the 60-qubit register in holmium. Combining a lattice of multiqubit ensembles

Saffman, Mark

250

Inelastic x-ray scattering study of the state-resolved differential cross section of Compton excitations in helium atoms  

SciTech Connect

The state-resolved differential cross sections for both the 1s{sup 2} {sup 1}S{sub 0}{yields}1s2s {sup 1}S{sub 0} monopolar transition and the 1s{sup 2} {sup 1}S{sub 0}{yields}1s2p {sup 1}P{sub 1} dipolar transition of atomic helium had been measured over a large momentum transfer region by high-resolution inelastic x-ray scattering (IXS). The almost-perfect match of the present measurement with the theoretical calculations gives a stringent test of the theoretical method and the calculated wave functions. Our results demonstrate that high-resolution IXS is a powerful tool for studying the excitations in atoms and molecules.

Xie, B. P.; Yang, K.; Zhou, B.; Feng, D. L. [Department of Physics, Surface Physics Laboratory (National Key Laboratory), and Advanced Materials Laboratory, Fudan University, Shanghai 200433 (China); Zhu, L. F.; Wang, E. L. [Hefei National Laboratory for Physical Sciences at Microscale, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hiraoka, N.; Cai, Y. Q. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Yao, Y.; Wu, C. Q. [Department of Physics, Fudan University, Shanghai 200433 (China)

2010-09-15

251

Electron impact double-excitation of helium 2l2l' autoionizing states using the (e, 2e) technique  

NASA Astrophysics Data System (ADS)

Coplanar (e, 2e) triple differential cross sections (TDCS) measurements are reported for the helium autoionizing doubly excited states, (2s2)1 S, (2p2)1D, and (2s2p)1P, for an incident electron energy of 250 eV and a scattering angle of -13°, corresponding to a momentum transfer of 1.06 a.u. The presence of autoionization results in a clearly visible recoil peak in the TDCS structure with a shape that is strongly dependent on the orbital angular momentum L of the resonance. The resonance contributions together with the strong background of direct ionization processes lead to a complicated asymmetric structure of the resonance profile in the TDCS.

Sise, Omer; Dogan, Mevlut; Okur, Ibrahim; Crowe, Albert

2012-11-01

252

Evolution from Rydberg gas to ultracold plasma in a supersonic atomic beam of Xe  

NASA Astrophysics Data System (ADS)

A Rydberg gas of xenon, entrained in a supersonic atomic beam, evolves slowly to form an ultracold plasma. In the early stages of this evolution, when the free-electron density is low, Rydberg atoms undergo long-range \\ell -mixing collisions, yielding states of high orbital angular momentum. The development of high-\\ell states promotes dipole-dipole interactions that help to drive Penning ionization. The electron density increases until it reaches the threshold for avalanche. Ninety ?s after the production of a Rydberg gas with the initial state, {{n}_{0}}{{\\ell }_{0}}=42d, a 432 V cm-1 electrostatic pulse fails to separate charge in the excited volume, an effect which is ascribed to screening by free electrons. Photoexcitation cross sections, observed rates of \\ell -mixing, and a coupled-rate-equation model simulating the onset of the electron-impact avalanche point consistently to an initial Rydberg gas density of 5\\times {{10}^{8}}\\;c{{m}^{-3}}.

Hung, J.; Sadeghi, H.; Schulz-Weiling, M.; Grant, E. R.

2014-08-01

253

Interaction of the NO 3p? (C 2?) Rydberg state with RG (RG = Ne, Kr, and Xe): Potential energy surfaces and spectroscopy  

NASA Astrophysics Data System (ADS)

We present new potential energy surfaces for the interaction of NO(C 2?) with each of Ne, Kr, and Xe. The potential energy surfaces have been calculated using second order Møller-Plesset perturbation theory, exploiting a procedure to converge the reference Hartree-Fock wavefunction for the excited states: the maximum overlap method. The bound rovibrational states obtained from the surfaces are used to simulate the electronic spectra and their appearance is in good agreement with available (2+1) REMPI spectra. We discuss the assignment and appearance of these spectra, comparing to that of NO-Ar.

Ershova, Olga V.; K?os, Jacek; Besley, Nicholas A.; Wright, Timothy G.

2015-01-01

254

High-pressure phase diagram and equation of state of solid helium from single-crystal X-ray diffraction to 23.3 GPa  

NASA Technical Reports Server (NTRS)

Single-crystal X-ray diffraction measurements have been performed on solid He-4 from 15.6 to 23.3 GPa at 300 K with synchrotron radiation. The diffraction patterns demonstrate that the structure of the solid is hexagonal close packed over this pressure-temperature range, contrary to both the interpretation of high-pressure optical studies and to theoretical predictions. The solid is more compressible than is indicated by equations of state calculated with recently determined helium pair potentials. The results suggest that a significant revision of current views of the phase diagram and energetics of dense solid helium is in order.

Mao, H. K.; Hemley, R. J.; Jephcoat, A. P.; Finger, L. W.; Wu, Y.

1988-01-01

255

Spin-dependent localized Hartree-Fock density-functional calculation of singly, doubly, and triply excited and Rydberg states of He- and Li-like ions  

E-print Network

A spin-dependent density-functional approach for the calculation of highly and multiply excited state of atomic system is proposed based on the localized Hartree-Fock density-functional method and Slater’s diagonal sum rule. In this approach...

Chu, Shih-I; Zhou, Zhongyuan

2005-02-28

256

Rotational perturbations in the (2 + 1) REMPI spectrum of the Rydberg state [ 2? 3 2 ] c 5 d;1 g of I 2  

Microsoft Academic Search

Partly rotationally resolved (2 + 1) resonance-enhanced multiphoton ionization contour spectra of the vibrational bands corresponding to the [2?32g]c5d; lg ? ? X transition in iodine, recorted at room temperature, have been analyzed. Irregular band spectral structures could be simulated by assuming rotational line strengths to be dependent on rotational quantum number in the resonantly excited state at the two-photon

Ágúst Kvaran; Gísli Hólmar Jóhannesson; Huasheng Wang

1996-01-01

257

Linear Atom Guides: Guiding Rydberg Atoms and Progress Toward an Atom Laser  

NASA Astrophysics Data System (ADS)

In this thesis, I explore a variety of experiments within linear, two-wire, magnetic atom guides. Experiments include guiding of Rydberg atoms; transferring between states while keeping the atoms contained within the guide; and designing, constructing, and testing a new experimental apparatus. The ultimate goal of the atom guiding experiments is to develop a continuous atom laser. The guiding of 87Rb 59D5/2 Rydberg atoms is demonstrated. The evolution of the atoms is driven by the combined effects of dipole forces acting on the center-of-mass degree of freedom as well as internal-state transitions. Time delayed microwave and state-selective field ionization, along with ion detection, are used to investigate the evolution of the internal-state distribution as well as the Rydberg atom motion while traversing the guide. The observed decay time of the guided-atom signal is about five times that of the initial state. A population transfer between Rydberg states contributes to this lengthened lifetime, and also broadens the observed field ionization spectrum. The population transfer is attributed to thermal transitions and, to a lesser extent, initial state-mixing due to Rydberg-Rydberg collisions. Characteristic signatures in ion time-of-flight signals and spatially resolved images of ion distributions, which result from the coupled internal-state and center-of-mass dynamics, are discussed. Some groups have used a scheme to make BECs where atoms are optically pumped from one reservoir trap to a final state trap, irreversibly transferring those atoms from one trap to the other. In this context, transfer from one guided ground state to another is studied. In our setup, before the atoms enter the guide, they are pumped into the | F = 1, mF = --1> state. Using two repumpers, one tuned to the F = 1 ? F' = 0 transition (R10) and the other tuned to the F = 1 ? F' = 2 transition (R12), the atoms are pumped between these guided states. Magnetic reflections within the guide are also studied. Design and construction of a new linear magnetic atom guide is detailed. This guide beta has many improvements over the original guide alpha: a Zeeman slower, magnetic injection, a physical shutter, and surface adsorption evaporative cooling are some of the main changes. Testing of this new system is underway. It is hoped that the improvements to guide beta will yield an atom density sufficient to reach degeneracy, thereby forming a continuous BEC at the end of the guide. The BEC, which will be continuously replenished by the atoms within the guide, will be outcoupled to form a continuous atom laser.

Traxler, Mallory A.

258

Exotic topological density waves in cold atomic Rydberg fermions  

E-print Network

Versatile controllability of interactions in ultracold atomic and molecular gases has now reached an unprecedented era where quantum correlations and unconventional many-body phases can be studied with no corresponding analogs in solid state systems. Recent experiments in Rydberg atomic gases have achieved exquisite control over non-local interactions, allowing novel quantum phases unreachable with the usual local interactions in atomic systems. Here, we study Rydberg dressed atomic fermions in a three dimensional optical lattice predicting the existence of hitherto unheard-of exotic mixed topological density wave phases. We show that varying spatial range of the non-local interaction leads to a rich phase diagram containing various bond density waves, with unexpected spontaneous time-reversal symmetry breaking. Quasiparticles in these chiral phases experience emergent gauge fields and form three dimensional quantum Hall and Weyl semimetal states. Remarkably, certain density waves even exhibit mixed topologies beyond the existing topological classification. Experimental signatures of density waves and their topological properties are predicted in time-of-flight measurements.

Xiaopeng Li; S. Das Sarma

2015-01-21

259

The Rydberg electronic transitions of the hydrogen molecule  

SciTech Connect

Transition energies and relative line strengths, without Boltzmann weighting, for the electric dipole transitions between Rydberg states n{prime}L{prime} and nL of the hydrogen molecule (one electron in a near-hydrogenic state of high n and L, with n the principal quantum number and L the orbital angular momentum quantum number of the electron) are calculated. Since the H{sup +}{sub 2} core is loosely coupled to the Rydberg electron, numerous lines occur, depending on the vector sum of L and the core rotational angular momentum. For the core vibrational quantum numbers v = 0 to 5 the strongest lines among the P, Q, and R branches for the lowest 12 core rotational levels are given for the particular transition arrays 6h-5g, 8i-6h, 7i-6h, 8k-7i, and 9l-8k, for which transitions occur in the wave number range 350 to 1,400 cm {sup {minus}1}.

Babb, J.F.; Chang, E.S. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States))

1992-01-01

260

Power law decay and phase rigidity for large-amplitude coherent phonons in bismuth at helium temperature: Possible evidence for transient supersolid state  

E-print Network

Intense ultrafast laser excitation can produce transient states of condensed matter that would otherwise be inaccessible. At high excitation level, the interatomic forces can be altered resulting in an unusual lattice dynamics. Here we report the study of coherent lattice dynamics in Bi made for various excitation levels at helium temperature. We demonstrate that under certain conditions the fully symmetric phonons of large amplitude exhibit anomalous decay and phase rigidity, both of which possibly signaling the attainment of transient supersolid state.

Misochko, O V

2011-01-01

261

Power law decay and phase rigidity for large-amplitude coherent phonons in bismuth at helium temperature: Possible evidence for transient supersolid state  

E-print Network

Intense ultrafast laser excitation can produce transient states of condensed matter that would otherwise be inaccessible. At high excitation level, the interatomic forces can be altered resulting in an unusual lattice dynamics. Here we report the study of coherent lattice dynamics in Bi made for various excitation levels at helium temperature. We demonstrate that under certain conditions the fully symmetric phonons of large amplitude exhibit anomalous decay and phase rigidity, both of which possibly signaling the attainment of transient supersolid state.

O. V. Misochko; M. V. Lebedev

2011-03-17

262

Entangling Atomic Spins with a Strong Rydberg-Dressed Interaction  

E-print Network

Controlling quantum entanglement between parts of a many-body system is the key to unlocking the power of quantum information processing for applications such as quantum computation, highprecision sensing, and simulation of many-body physics. Spin degrees of freedom of ultracold neutral atoms in their ground electronic state provide a natural platform given their long coherence times and our ability to control them with magneto-optical fields, but creating strong coherent coupling between spins has been challenging. We demonstrate a Rydberg-dressed ground-state blockade that provides a strong tunable interaction energy (~1 MHz in units of Planck's constant) between spins of individually trapped cesium atoms. With this interaction we directly produce Bell-state entanglement between two atoms with a fidelity >= 81(2)%, excluding atom loss events, and >= 60(3)% when loss is included.

Jau, Y -Y; Keating, Tyler; Deutsch, I H; Biedermann, G W

2015-01-01

263

Entangling Atomic Spins with a Strong Rydberg-Dressed Interaction  

E-print Network

Controlling quantum entanglement between parts of a many-body system is the key to unlocking the power of quantum information processing for applications such as quantum computation, highprecision sensing, and simulation of many-body physics. Spin degrees of freedom of ultracold neutral atoms in their ground electronic state provide a natural platform given their long coherence times and our ability to control them with magneto-optical fields, but creating strong coherent coupling between spins has been challenging. We demonstrate a Rydberg-dressed ground-state blockade that provides a strong tunable interaction energy (~1 MHz in units of Planck's constant) between spins of individually trapped cesium atoms. With this interaction we directly produce Bell-state entanglement between two atoms with a fidelity >= 81(2)%, excluding atom loss events, and >= 60(3)% when loss is included.

Y. -Y. Jau; A. M. Hankin; Tyler Keating; I. H. Deutsch; G. W. Biedermann

2015-01-16

264

Frustrated Quantum Magnetism with Laser-Dressed Rydberg Atoms  

E-print Network

We show how a broad class of lattice spin-1/2 models with angular- and distance-dependent couplings can be realized with cold alkali atoms stored in optical or magnetic trap arrays. The effective spin-1/2 is represented by a pair of atomic ground states, and spin-spin interactions are obtained by admixing van der Waals interactions between fine-structure split Rydberg states with laser light. The strengths of the diagonal spin interactions as well as the "flip-flop", and "flip-flip" and "flop-flop" interactions can be tuned by exploiting quantum interference, thus realizing different spin symmetries. The resulting energy scales of interactions compare well with typical temperatures and decoherence time-scales, making the exploration of exotic forms of quantum magnetism, including emergent gauge theories and compass models, accessible within state-of-the-art experiments.

Alexander W. Glaetzle; Marcello Dalmonte; Rejish Nath; Christian Gross; Immanuel Bloch; Peter Zoller

2014-10-13

265

The fundamental rotational interval of para-H 2+ by MQDT-assisted Rydberg spectroscopy of H2  

NASA Astrophysics Data System (ADS)

Transitions from selected nd Rydberg states of H2 to n'p/f Rydberg series converging on the lowest two (N+ = 0 and 2) rotational levels of the X + 2 ?g + (v+ = 0) ground state of para-H 2+ have been measured in the range 1-7.4 THz using a laser-based, pulsed, narrow-band source of submillimeter-wave radiation. The analysis of the spectra by multichannel quantum-defect theory (MQDT) has allowed a complete interpretation of the fine structures of the Rydberg series and their dependence on the principal quantum number. The extrapolation of the series to their limits with MQDT has enabled the determination of the first rotational interval of para-H 2+ , which is 174.236 71(7) cm-1 (5 223 485.1(2.3) MHz).

Haase, Christa; Beyer, Maximilian; Jungen, Christian; Merkt, Frédéric

2015-02-01

266

Rydberg transition emission after multielectron capture in low-energy collisions of Ar sup 9+ with He, Ne, and Ar  

SciTech Connect

Cross sections for emission of Rydberg transitions in collisions of Ar{sup 9+} ions with He, Ne, and Ar atoms have been measured at an impact energy of 180 keV. Transitions from levels {ital n}=6,...,11 and {ital l}=5,...,9 following multielectron capture and cascading processes have been observed in fast Ar{sup 7+}, Ar{sup 6+}, Ar{sup 5+}, and Ar{sup 4+} ions. Emission of recoil ions, attributed to transitions in HeII, Ne II--IV, and ArII--IV give an additional proof of the capture of several electrons by the projectile. Doubly excited Rydberg states, also observed in ArVIII, are due to a multicapture process. Cross sections for multicapture with stabilization of two electrons in Rydberg states are compared to those determined by coincidence measurements.

Martin, S.; Denis, A.; Desesquelles, J.; Ouerdane, Y. (Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard (Lyon I), Campus de la Doua, 69622 Villeurbanne CEDEX, France (FR))

1990-12-01

267

Time delay anisotropy in photoelectron emission from the isotropic ground state of helium  

E-print Network

Time delays of electrons emitted from an isotropic initial state and leaving behind an isotropic ion are assumed to be angle-independent. Using an interferometric method involving XUV attosecond pulse trains and an IR probe field in combination with a detection scheme, which allows for full 3D momentum resolution, we show that time delays between electrons liberated from the $1s^{2}$ spherically symmetric ground state of He depend on the emission direction of the electrons with respect to the linear polarization axis of the ionizing XUV light. Such time delays can exhibit values as large as 60 attoseconds. With the help of refined theoretical models we can attribute the observed anisotropy to the interplay between different final quantum states, which arise naturally when two photons are involved in the photoionization process. Since most measurement techniques tracing attosecond electron dynamics have involved at least two photons so far, this is a general, significant, and initially unexpected effect that m...

Heuser, Sebastian; Cirelli, Claudio; Sabbar, Mazyar; Boge, Robert; Lucchini, Matteo; Gallmann, Lukas; Ivanov, Igor; Kheifets, Anatoli S; Dahlström, J Marcus; Lindroth, Eva; Argenti, Luca; Martín, Fernando; Keller, Ursula

2015-01-01

268

Evolution of layers and motional states of helium adatoms in the micro-pores of Y zeolites  

NASA Astrophysics Data System (ADS)

Properties of helium adatoms in the 8-13A?diameter pores of Na-Y and Silica-Y zeolites with different Si/Al ratios and cations have been studied by measuring an isosteric heat qst of adsorption and heat capacity C. Step-wise changes of qst at T=0K with increasing the amount n adsorbed give magnitudes of the localization potentials on the pore wall and they show evolution of layers. In the Y zeolites, a first layer is completed at n?38% of the full pore amount. The adatoms on the first layer are gas-like since we observed ?C/?n?R/2 (=4.2J/K/mol) at 38< n?45% and 1?T?5K. At 50?n?65%, they are liquid-like state with a T-linear heat capacity. Fermi degeneracy of the gas- or liquid-like 3He adatoms is possible below a few hundreds mK.

Wada, Nobuo; Kato, Hideyuki

1994-02-01

269

Steady-state heat transfer to boiling liquid helium in simulated coil windings  

SciTech Connect

The present data show that the worst case steady-state stability in the GE/LCT magnet windings is at a horizontal conductor orientation. The heat transfer improves with inclination of the conductor from horizontal. Calculations show that for these small regions normal zones will recover by cold-end conduction from the inclined conductor on either end.

Walstrom, P.L.

1981-01-01

270

Commensurate to incommensurate transitions and frustration in multi-component Rydberg gases  

E-print Network

We study the static behavior of a gas of atoms held in a one-dimensional lattice where two distinct electronically high-lying Rydberg states are simultaneously excited by laser light. We focus on a situation where interactions of van-der-Waals type take place only among atoms that are in the same Rydberg state. We analytically investigate at first the so-called classical limit of vanishing laser driving strength. We show that the system exhibits a surprisingly complex ground state structure with a sequence of commensurate to incommensurate transitions. The incommensurability between the species leads to mutual frustration, a feature which pertains also in the quantum regime. We perform an analytical and numerical investigation of these features and present an approximative description of the system in terms of a Rokhsar-Kivelson Hamiltonian which permits the analytical understanding of the frustration effects even beyond the classical limit.

Levi, Emanuele; Garrahan, Juan P; Lesanovsky, Igor

2015-01-01

271

On the Formation of (Anionic) Excited Helium Dimers in Helium Droplets  

PubMed Central

Metastable atomic and molecular helium anions exhibiting high-spin quartet configurations can be produced in helium droplets via electron impact. Their lifetimes allow detection in mass spectrometric experiments. Formation of atomic helium anions comprises collision-induced excitation of ground state helium and concomitant electron capture. Yet the formation of molecular helium anions in helium droplets has been an unresolved issue. In this work, we explore the interaction of excited helium atoms exhibiting high-spin triplet configurations with ground state helium using the equation-of-motion coupled-cluster method. Transition barriers in the energetically lowest He*–He and He*––He interaction potentials prevent molecule formation at the extremely low temperatures present in helium droplets. In contrast, some excited states allow a barrier-free formation of molecular helium (anions). Moreover, we show that the necessary excitation energies pinpoint (higher) resonances in recently recorded mass spectra and emend the assignment of those resonances that have previously been assigned to electron-impact ionization of ground state helium necessitating subsequent double-electron capture. Embedding molecules or molecular clusters in helium droplets is a predestined experimental technique for the study of phenomena at very low temperatures. Profound knowledge about active processes in the helium environment is required for a proper assessment of experimental data. PMID:24866535

2014-01-01

272

(HELIUM3, 2PROTON) and the Proton-Proton Final State Interaction  

Microsoft Academic Search

The (('3)He,2p) reaction has been studied at an incident energy of 13.0 MeV, on ('64)Ni, ('9)Be, ('27)Al, and ('90)Zr. From coincident two-proton events, data were extracted of: (a) single proton energy distributions, and (b) intensity distributions as a function of proton -proton correlation angle. The Watson approach was initially adopted, in which a complete separability of primary- and final state

Thomas Vincent Congedo

1980-01-01

273

Helium recovery process  

Microsoft Academic Search

In a process for the recovery of helium from natural gas by liquefaction of hydrocarbons and separation of gaseous helium, the gaseous mixture containing helium, carbon dioxide, nitrogen, and methane is cooled to separate a liquid fraction containing dissolved helium and a helium-enriched gaseous fraction. The helium is stripped from the liquid fraction into an overhead gaseous fraction which is

D. B. Crawford; M. Karafian

1967-01-01

274

Mobilities of ground-state and metastable O/+/, O2/+/, O/2+/, and O2/2+/ ions in helium and neon  

NASA Astrophysics Data System (ADS)

The ionic mobilities of O(+), O2(+), O(2+), and O2(2+) in helium and neon have been measured using a selected-ion drift apparatus (SIDA). It is found that the mobilities of both O(+) and O2(+) ions in the metastable states (2D or 4Pi u) are measurably smaller than those of the same ions carried out by using known, state-selective ion-molecule reactions. A similar mobility differentiation of ground-state and metastable ions was not observed for the O(2+) and O2(2+) ions.

Johnsen, R.; Biondi, M. A.; Hayashi, M.

1982-09-01

275

Testing spatial noncommutativity via Rydberg atoms.  

PubMed

The possibility of testing spatial noncommutativity via Rydberg atoms is explored. An atomic di-pole of a cold Rydberg atom is arranged in appropriate electric and magnetic fields, so that the motion of the dipole is constrained to be planar and rotationally symmetric. Spatial noncommutativity leads the canonical angular momentum to possess fractional values. In the limit of vanishing kinetic energy, the dominate value of the lowest canonical angular momentum takes variant Planck's over h/2. Furthermore, in the limit of eliminating the magnetic field, the dominate value of the lowest canonical angular momentum changes from variant Planck's over h/2 to variant Planck's over h/4. This result is a clear signal of spatial noncommutativity. An experimental verification of this prediction is suggested. PMID:15323756

Zhang, Jian-Zu

2004-07-23

276

Effective dynamics of strongly dissipative Rydberg gases  

E-print Network

We investigate the evolution of interacting Rydberg gases in the limit of strong noise and dissipation. Starting from a description in terms of a Markovian quantum master equation we derive effective equations of motion that govern the dynamics on a "coarse-grained" timescale where fast dissipative degrees of freedom have been adiabatically eliminated. Specifically, we consider two scenarios which are of relevance for current theoretical and experimental studies --- Rydberg atoms in a two-level (spin) approximation subject to strong dephasing noise as well as Rydberg atoms under so-called electromagnetically induced transparency (EIT) conditions and fast radiative decay. In the former case we find that the effective dynamics is described by classical rate equations up to second order in an appropriate perturbative expansion. This drastically reduces the computational complexity of numerical simulations in comparison to the full quantum master equation. When accounting for the fourth order correction in this expansion, however, we find that the resulting equation breaks the preservation of positivity and thus cannot be interpreted as a proper classical master rate equation. In the EIT system we find that the expansion up to second order retains information not only on the "classical" observables, but also on some quantum coherences. Nevertheless, this perturbative treatment still achieves a non-trivial reduction of complexity with respect to the original problem.

M Marcuzzi; J Schick; B Olmos; I Lesanovsky

2014-09-29

277

Alignment of the 2p State of 2-Mev Amu Helium-Like Sulfur  

E-print Network

transition pQ 1 tt Sed sincetheinitia s a of14dff 1 1p o po d hence one may expec itransitions, and Based on the ear- 1S?20 'zation at most. a MeV/amu He, Li, and 0 ions, the 26 ALIGNMENT OF THE 2P STATE OF 2-MeV/amu HELIUMLIKE. . . 3097 I04 52 MeV 0...-AS TARGET SPECTRUM l4 l2? KL2/KLO UJ Z.' Z', C3 (0I- Z.' ~ IO~ O 0 0 0 0 0 ~o KLO cP e ~ ~ ~0 0 ~ ooo ~ ~ $ 0V ~ ~ ~ Q oooo +o ~ ~ ~ ~ P ~ ~ ~ p ~ ~ ~ o ~ ~ ~ ~ W%& ~ ~ ~ ~ ~ ~he~ ~ oolo4oo I I i I i I P...

Church, David A.; Kenefick, R. A.; Wang, D. W.; Watson, R. L.

1982-01-01

278

Duality and bistability in an optomechanical cavity coupled to a Rydberg superatom  

NASA Astrophysics Data System (ADS)

We study the steady-state behaviors of a typical optomechanical cavity coupled to cold Rydberg atoms with dipole-dipole interactions. The interacting atoms are described as one superatom of three collective states in a ladder configuration in the limit of a strong dipole blockade and a weak cavity field. We find that this hybrid system exhibits phenomena of conditional duality and nonlinear bistability in terms of mirror displacement, number of cavity photons, and Rydberg population, depending on the detuning of the cavity field, the strength of the optical driving field, and the number of cold atoms. It is of particular interest that the two branches of relevant curves may intersect to yield a nontrivial duality and bistability. Such correlated optical, mechanical, and atomic responses arise from the efficient feedback between atom-light and optomechanical interactions and have realistic applications, e.g., in realizing accurate optomechanical detection or attaining deterministic single photons.

Yan, Dong; Wang, Zhi-Hai; Ren, Chun-Nian; Gao, Hang; Li, Yong; Wu, Jin-Hui

2015-02-01

279

Rydberg gas theory of a glow discharge plasma: II. Electrode kinetics (probe theory) and the thermal rate constant for Symmetrical charge transfer involving Rydberg atoms of Ar.  

PubMed

A steady state chemical kinetic model is developed to describe the conduction of electrical current between two probes, of relatively large surface area, immersed in a fast flowing plasma by the mechanism of charge transfer through a gas of Rydberg atoms. It correctly predicts the shape of current-voltage profiles which are similar to those of Langmuir, or floating double probe measurements. The difference is that the plateau current at the probe reflects the transport limited ion current at the cathodic electrode, even when the probe is being scanned in the anodic region. The sharp gradient leading up to the plateau of the I-V curve is associated with the field dependence of the efficiency of Rydberg atom ionisation, not the electron temperature. This approach gives a good qualitative explanation of experimental behaviour over a wide range of probe bias voltages and includes the occurrence of electron impact ionisation at the anode. It also gives a value for the thermal rate coefficient of symmetrical charge transfer between Rydberg atoms of Ar (8.2 x 10(-7) molecule(-1) cm(3) s(-1), at 313 K; plasma density approximately = 10(10) atoms cm(-3), total pressure = 2.7 mbar). PMID:20358036

Mason, Rod S

2010-04-21

280

Correlated Exciton Transport in Rydberg-Dressed-Atom Spin Chains  

E-print Network

We investigate the transport of excitations through a chain of atoms with non-local dissipation introduced through coupling to additional short-lived states. The system is described by an effective spin-1/2 model where the ratio of the exchange interaction strength to the reservoir coupling strength determines the type of transport, including coherent exciton motion, incoherent hopping and a regime in which an emergent length scale leads to a preferred hopping distance far beyond nearest neighbors. For multiple impurities, the dissipation gives rise to strong nearest-neighbor correlations and entanglement. These results highlight the importance of non-trivial dissipation, correlations and many-body effects in recent experiments on the dipole-mediated transport of Rydberg excitations.

H. Schempp; G. Günter; S. Wüster; M. Weidemüller; S. Whitlock

2015-04-08

281

Correlated Exciton Transport in Rydberg-Dressed-Atom Spin Chains  

E-print Network

We investigate the transport of excitations through a chain of atoms with non-local dissipation introduced through coupling to additional short-lived states. The system is described by an effective spin-1/2 model where the ratio of the exchange interaction strength to the reservoir coupling strength determines the type of transport, including coherent exciton motion, incoherent hopping and a regime in which an emergent length scale leads to a preferred hopping distance far beyond nearest neighbors. For multiple impurities, the dissipation gives rise to strong nearest-neighbor correlations and entanglement. These results highlight the importance of non-trivial dissipation, correlations and many-body effects in recent experiments on the dipole-mediated transport of Rydberg excitations.

Schempp, H; Wüster, S; Weidemüller, M; Whitlock, S

2015-01-01

282

Laser resonance photoionization spectroscopy of Rydberg levels in Fr  

SciTech Connect

We investigated for the first time the high-lying Rydberg levels in the rare radioactive element francium (Fr). The investigations were conducted by the highly sensitive laser resonance atomic photoionization technique with Fr atoms produced at a rate of about 10/sup 3/ atoms/s in a hot cavity. We measured the wave numbers of the 7p/sup 2/P/sub 3/2/..-->..nd/sup 2/D (n = 22--33) and 7p/sup 2/P/sub 3/2/..-->..ns/sup 2/S (n = 23, 25--27,29--31) transitions and found the binding energy of the 7p/sup 2/P/sub 3/2/ state to be T = -18 924.8(3) cm/sup -1/, which made it possible to establish accurately the ionization potential of Fr.

Andreev, S.V.; Letokhov, V.S.; Mishin, V.I.

1987-09-21

283

Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio.  

PubMed

Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium (pHe(+)) is a three-body atom consisting of a normal helium nucleus, an electron in its ground state and an antiproton (p) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n???l?+?1???38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which p(3)He(+) and p(4)He(+) isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-photon transitions of the antiproton of the type (n, l)???(n?-?2, l?-?2) at deep-ultraviolet wavelengths (? = 139.8, 193.0 and 197.0?nm), which partly cancel the Doppler broadening of the laser resonance caused by the thermal motion of the atoms. The resulting narrow spectral lines allowed us to measure three transition frequencies with fractional precisions of 2.3-5 parts in 10(9). By comparing the results with three-body quantum electrodynamics calculations, we derived an antiproton-to-electron mass ratio of 1,836.1526736(23), where the parenthetical error represents one standard deviation. This agrees with the proton-to-electron value known to a similar precision. PMID:21796208

Hori, Masaki; Sótér, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Friedreich, Susanne; Juhász, Bertalan; Pask, Thomas; Widmann, Eberhard; Horváth, Dezso; Venturelli, Luca; Zurlo, Nicola

2011-07-28

284

Tables of thermodynamic properties of helium magnet coolant: 41 Isobars in the range 1--5 atm and 3--5 K calculated from the equations of state of McCarty  

SciTech Connect

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10{sup 8} Pa,'' Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P({rho},T) covering different regions together with rules for making the transition from one region to another.

McAshan, M.S.

1987-06-01

285

Molecular physics. Production of trilobite Rydberg molecule dimers with kilo-Debye permanent electric dipole moments.  

PubMed

Permanent electric dipole moments are important for understanding symmetry breaking in molecular physics, control of chemical reactions, and realization of strongly correlated many-body quantum systems. However, large molecular permanent electric dipole moments are challenging to realize experimentally. We report the observation of ultralong-range Rydberg molecules with bond lengths of ~100 nanometers and kilo-Debye permanent electric dipole moments that form when an ultracold ground-state cesium (Cs) atom becomes bound within the electronic cloud of an extended Cs electronic orbit. The electronic character of this hybrid class of "trilobite" molecules is dominated by degenerate Rydberg manifolds, making them difficult to produce by conventional photoassociation. We used detailed coupled-channel calculations to reproduce their properties quantitatively. Our findings may lead to progress in ultracold chemistry and strongly correlated many-body physics. PMID:25838380

Booth, D; Rittenhouse, S T; Yang, J; Sadeghpour, H R; Shaffer, J P

2015-04-01

286

Scaling the neutral atom Rydberg gate quantum computer by collective encoding in Holmium atoms  

E-print Network

We discuss a method for scaling a neutral atom Rydberg gate quantum processor to a large number of qubits. Limits are derived showing that the number of qubits that can be directly connected by entangling gates with errors at the $10^{-3}$ level using long range Rydberg interactions between sites in an optical lattice, without mechanical motion or swap chains, is about 500 in two dimensions and 7500 in three dimensions. A scaling factor of 60 at a smaller number of sites can be obtained using collective register encoding in the hyperfine ground states of the rare earth atom Holmium. We present a detailed analysis of operation of the 60 qubit register in Holmium. Combining a lattice of multi-qubit ensembles with collective encoding results in a feasible design for a 1000 qubit fully connected quantum processor.

Saffman, M

2008-01-01

287

Scaling the neutral atom Rydberg gate quantum computer by collective encoding in Holmium atoms  

E-print Network

We discuss a method for scaling a neutral atom Rydberg gate quantum processor to a large number of qubits. Limits are derived showing that the number of qubits that can be directly connected by entangling gates with errors at the $10^{-3}$ level using long range Rydberg interactions between sites in an optical lattice, without mechanical motion or swap chains, is about 500 in two dimensions and 7500 in three dimensions. A scaling factor of 60 at a smaller number of sites can be obtained using collective register encoding in the hyperfine ground states of the rare earth atom Holmium. We present a detailed analysis of operation of the 60 qubit register in Holmium. Combining a lattice of multi-qubit ensembles with collective encoding results in a feasible design for a 1000 qubit fully connected quantum processor.

M. Saffman; K. Molmer

2008-05-04

288

Charge state distribution of 86Kr in hydrogen and helium gas charge strippers at 2.7 MeV /nucleon  

NASA Astrophysics Data System (ADS)

The charge state distributions of krypton (86Kr) with an energy of 2.7 MeV /nucleon were measured using hydrogen (H2 ) and helium (He) gas charge strippers. A differential pumping system was constructed to confine H2 and He gases to a thickness sufficient for the charge state distributions to attain equilibrium. The mean charge states of 86Kr in H2 and He gases attained equilibrium at 25.1 and 23.2, respectively, whereas the mean charge state in N2 gas at equilibrium was estimated to be less than 20. The charge distributions are successfully reproduced by the cross sections of ionization and electron capture processes optimized by a fitting procedure.

Kuboki, H.; Okuno, H.; Hasebe, H.; Fukunishi, N.; Ikezawa, E.; Imao, H.; Kamigaito, O.; Kase, M.

2014-12-01

289

Strongly correlated growth of Rydberg aggregates in a vapour cell  

E-print Network

The observation of strongly interacting many-body phenomena in gaseous samples typically requires ultracold atomic gases. Here we show that the very strong interaction potentials between Rydberg atoms enable the observation of many body effects in an atomic vapour, even at room temperature. We excite Rydberg atoms in caesium vapour and observe in real-time excitation dynamics far from resonance consistent with the formation of aggregates composed of several 10,000 Rydberg atoms. The experimental observations show qualitative and quantitative agreement with a microscopic theoretical model. Numerical simulations reveal that the strongly correlated growth of the emerging aggregates is reminiscent of soft-matter type systems.

Urvoy, A; Lesanovsky, I; Booth, D; Shaffer, J P; Pfau, T; Löw, R

2014-01-01

290

Interaction-induced stabilization of circular Rydberg atoms  

SciTech Connect

We discuss a candidate solution for the controlled trapping and manipulation of two individual Rydberg atoms by means of a magnetic Ioffe-Pritchard trap that is superimposed by a constant electric field. In such a trap Rydberg atoms experience a permanent electric dipole moment that can be of the order of several hundred debye. The interplay of electric dipolar repulsion and three-dimensional magnetic confinement leads to a well controllable equilibrium configuration with tunable trap frequency and atomic distance. We thoroughly investigate the trapping potentials and analyze the interaction-induced stabilization of two such trapped Rydberg atoms. Possible limitations and collapse scenarios are discussed.

Hezel, Bernd [Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, DE-69120 Heidelberg (Germany); Mayle, Michael; Schmelcher, Peter [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, DE-22761 Hamburg (Germany)

2011-12-15

291

Quantum repeaters based on Rydberg-blockade-coupled atomic ensembles  

SciTech Connect

We propose a scheme for realizing quantum repeaters with Rydberg-blockade-coupled atomic ensembles, based on a recently proposed collective encoding strategy. Rydberg-blockade-mediated two-qubit gates and efficient cooperative photon emission are employed to create ensemble-photon entanglement. Thanks to deterministic entanglement swapping operations via Rydberg-based two-qubit gates, and to the suppression of multiexcitation errors by the blockade effect, the entanglement distribution rate of the present scheme is higher by orders of magnitude than the rates achieved by other ensemble-based repeaters. We also show how to realize temporal multiplexing with this system, which offers an additional speedup in entanglement distribution.

Han Yang [Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta (Canada); College of Science, National University of Defense Technology, Changsha 410073 (China); He Bing; Heshami, Khabat; Simon, Christoph [Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta (Canada); Li Chengzu [College of Science, National University of Defense Technology, Changsha 410073 (China)

2010-05-15

292

AB INITIO EQUATION OF STATE FOR HYDROGEN-HELIUM MIXTURES WITH RECALIBRATION OF THE GIANT-PLANET MASS-RADIUS RELATION  

SciTech Connect

Using density functional molecular dynamics simulations, we determine the equation of state (EOS) for hydrogen-helium mixtures spanning density-temperature conditions typical of giant-planet interiors, {approx}0.2-9 g cm{sup -3} and 1000-80,000 K for a typical helium mass fraction of 0.245. In addition to computing internal energy and pressure, we determine the entropy using an ab initio thermodynamic integration technique. A comprehensive EOS table with 391 density-temperature points is constructed and the results are presented in the form of a two-dimensional free energy fit for interpolation. Deviations between our ab initio EOS and the semi-analytical EOS model by Saumon and Chabrier are analyzed in detail, and we use the results for initial revision of the inferred thermal state of giant planets with known values for mass and radius. Changes are most pronounced for planets in the Jupiter mass range and below. We present a revision to the mass-radius relationship that makes the hottest exoplanets increase in radius by {approx}0.2 Jupiter radii at fixed entropy and for masses greater than {approx}0.5 Jupiter mass. This change is large enough to have possible implications for some discrepant ''inflated giant exoplanets''.

Militzer, B. [Departments of Earth and Planetary Science and of Astronomy, University of California, Berkeley, CA 94720 (United States); Hubbard, W. B. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2013-09-10

293

Rydberg series of calcium monofluoride : spectrum, structure, and dynamics  

E-print Network

This thesis summarizes progress toward the ultimate goal of building a complete structural and dynamical model for the CaF molecule. The quantum defects of the Rydberg series of the molecule, as well as their dependences ...

Kay, Jeffrey J

2007-01-01

294

A precision millimeter-wave measurement of the Rydberg frequency  

E-print Network

The Rydberg frequency, cR[infinity], sets the frequency scale for the spectrum of hydrogen atoms. From a frequency measurement of one transition in hydrogen, cR[infinity] can be extracted and the frequency of any other ...

De Vries, Joel Christopher, 1971-

2001-01-01

295

Determination of the Rb85 ng -series quantum defect by electric-field-induced resonant energy transfer between cold Rydberg atoms  

NASA Astrophysics Data System (ADS)

Resonant energy transfer between cold Rydberg atoms was used to determine Rydberg atom energy levels, at precisions approaching those obtainable in microwave spectroscopy. Laser cooled Rb85 atoms from a magneto-optical trap were optically excited to 32d5/2 Rydberg states. The two-atom process 32d5/2+32d5/2?34p3/2+30g is resonant at an electric field of approximately 0.3V/cm . This process is driven by the electric dipole-dipole interaction, which is allowed due to the partial f character that the g state acquires in an electric field. The experimentally observed resonant field, together with the Stark map calculation is used to make a determination of the Rb85 ng -series quantum defect ?g(n=30)=0.00405(6) .

Afrousheh, K.; Bohlouli-Zanjani, P.; Petrus, J. A.; Martin, J. D. D.

2006-12-01

296

Computational design of solid-state interfaces using O-lattice theory: An application to mitigating helium-induced damage  

NASA Astrophysics Data System (ADS)

Tailoring interface structure to control interface properties promises to improve performance in a wide range of structural materials. We demonstrate an approach for designing interfaces with pre-specified internal structure and functionality using O-lattice theory. To illustrate our method, we design an interface intended to mitigate helium (He)-induced damage by promoting precipitation of He into continuous linear channels. A similar top-down design process may be used to tailor interfaces for other applications such as improved mechanical properties.

Yuryev, D. V.; Demkowicz, M. J.

2014-12-01

297

Effect of electric fields on the decay branching ratio of {sup 1}P{sup e} doubly excited states in helium measured by time-resolved fluorescence  

SciTech Connect

We have measured the lifetimes of {sup 1}P{sup e} (n=9-12) doubly excited states in static electric fields (1-6 kV/cm) by observing the decay of the fluorescence signal as a function of time. The effects of the field on these helium states below the second ionization threshold are twofold: their excitation becomes possible due to the Stark mixing with the optically allowed {sup 1}P{sup o} series, and their lifetime is strongly modified by the opening of the autoionization channel, not accessible in zero field. Although the electric field represents only a tiny perturbation of the atomic potential, a substantial shortening of the lifetimes below 100 ps is observed. This is the simplest quantum system where the ratio of autoionization to fluorescence decay probability can be effectively controlled by an electric field of moderate strength.

Zitnik, Matjaz; Mihelic, A.; Bucar, K. [Jozef Stefan Institute, P. O. Box 3000, SI-1001 Ljubljana (Slovenia); Penent, F.; Lablanquie, P. [LCP-MR, Universite Pierre et Marie Curie 6 and CNRS (UMR 7614), 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Richter, R. [Sincrotrone Trieste, I-340 12 Trieste (Italy); Alagia, M. [INFM-TASC, Padriciano 99, I-340 12 Trieste (Italy); Stranges, S. [Dipartimento di Chimica, Universita di Roma 'La Sapienza' and INFM Unit, 00185 Rome (Italy)

2006-11-15

298

Double photon excitation of high-Rydberg atoms as a long-lived submillimeter detector  

NASA Technical Reports Server (NTRS)

A method and apparatus for detecting submillimeter or IR radiation is disclosed. A rare gas, such as xenon, is supplied at its ground state via a pressurized cylinder and an adjustable leak valve into a cryogenically cooled detection area. The ground state of xenon is double photon excited to a particularized level of the Rydberg series by a resonance lamp and a laser. The doubly excited gas is then further excited by the radiation to be measured. A field ionization and an ion measurement indicative of the radiation intensity is achieved.

Chutjian, A. N. (inventor)

1986-01-01

299

Atmospheric helium capillary dielectric barrier discharge for soft ionization: determination of atom number densities in the lowest excited and metastable States.  

PubMed

The populations of the lowest excited helium states 2s 3S1, 2s 1S, 2p 3P0 J, and 2p 1P0 created in an atmospheric helium capillary dielectric barrier discharge were determined by means of optical emission spectroscopy. The emitted intensities of 388, 501, 587, and 667 nm lines were measured side-on and end-on with respect to the discharge axis. The comparison of optically thin side-on spectra with end-on spectra, which exhibited the absorption effects in the line kernels, enabled the determination of the average values of the number densities n1 in the considered He states along the plasma length L. The field of the theoretical profiles for a series of the n1L parameters pertinent to the experimental conditions was calculated for each line. By introducing the experimental data into the field of calculated curves, n1L corresponding to the particular state could be obtained. The measurements of the emission profiles were done as a function of the discharge voltage in the range covering homogeneous as well as filamentary DBD operation mode. Due to nonuniformity of the excited atom density distribution along the plasma, the values of n1 could be obtained only in the homogeneous operation mode where the nonuniformity was small. The following maximum values were found for the number densities in the investigated states: n1 av (2s 3S1) = (2.9 ± 1.1) × 1013 cm?3, n1 av (2s 1S) = (1.4 ± 0.5) × 1013 cm?3, n1 av (2p 3P0 J) = (1.1 ± 0.4) × 1013 cm?3, n1 av (2p 1P0) = (4.2 ± 1.6) × 1012 cm?3, and they represent the average populations along the plasma column in the capillary. PMID:24320177

Horvatic, Vlasta; Müller, Saskia; Veza, Damir; Vadla, Cedomil; Franzke, Joachim

2014-01-01

300

The problem of the structure (state of helium) in small He{sub N}-CO clusters  

SciTech Connect

A second-order perturbation theory, developed for calculating the energy levels of the He-CO binary complex, is applied to small He{sub N}-CO clusters with N = 2-4, the helium atoms being considered as a single bound object. The interaction potential between the CO molecule and HeN is represented as a linear expansion in Legendre polynomials, in which the free rotation limit is chosen as the zero approximation and the angular dependence of the interaction is considered as a small perturbation. By fitting calculated rotational transitions to experimental values it was possible to determine the optimal parameters of the potential and to achieve good agreement (to within less than 1%) between calculated and experimental energy levels. As a result, the shape of the angular anisotropy of the interaction potential is obtained for various clusters. It turns out that the minimum of the potential energy is smoothly shifted from an angle between the axes of the CO molecule and the cluster of {theta} = 100{sup o} in He-CO to {theta} = 180{sup o} (the oxygen end) in He{sub 3}-CO and He{sub 4}-CO clusters. Under the assumption that the distribution of helium atoms with respect to the cluster axis is cylindrically symmetric, the structure of the cluster can be represented as a pyramid with the CO molecule at the vertex.

Potapov, A. V., E-mail: potapov@isan.troitsk.ru; Panfilov, V. A.; Surin, L. A.; Dumesh, B. S. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)

2010-11-15

301

Steady state heat transfer experimental studies of LHC superconducting cables operating in cryogenic environment of superfluid helium  

E-print Network

The heat management is a basic and fundamental aspect of the superconducting magnets used in the CERN Large Hadron Collider. Indeed, the coil temperature must be kept below the critical value, despite the heat which can be generated or deposited in the magnet during the normal operations. Therefore, this thesis work aims at determining the heating power which can be extracted from the superconducting cables of the LHC, specially through their electrical insulation which represents the main thermal barrier. An experimental measurement campaign in superfluid helium bath was performed on several samples reproducting the main LHC magnets. The heating power was generated in the sample by Joule heating and the temperature increase was measured by means of Cernox bare chip and thermocouples. An innovative instrumentation technique which also includes the in-situ calibration of the thermocouples was developed. A thorough uncertainty analysis on the overall measurement chain concluded the experimental setup. The prese...

Santandrea, Dario; Tuccillo, Raffaele; Granieri, Pier Paolo.

302

Properties of Th4+ and Th3+ from rf spectroscopy of high-L thorium Rydberg ions  

NASA Astrophysics Data System (ADS)

Several properties of radon-like Th4+ and francium-like Th3+ were determined from measurements of high-L Rydberg fine structure in Th3+ and Th2+ ions. The measurements were carried out using the resonant excitation Stark ionization spectroscopy (RESIS) technique to detect rf transitions between levels in the same n. The measured Rydberg fine structures were then fit to an effective potential model, and the properties of the ions were extracted. Properties of the 1S0 ground state of Th4+ extracted from the measurements of the n=37 Th3+ Rydberg fine structure were the scalar dipole polarizability, alpha D,0=7.702(6)a.u. and the scalar quadrupole polarizability, alphaQ,0=29.1(1.6) a.u. The Th2+ Rydberg fine structure is much more complex since the ground state of Th3+ is a 2 F5/2, and the presence of low-lying excited states cause non-adiabatic effects in the fine structure which are not well described by the effective potential. To extract the properties, non-adiabatic corrections had to be calculated. The properties of Th3+ extracted were the permanent quadrupole moment, Q=0.5931(14)a.u. , the scalar and tensor dipole polarizabilities, alpha D,0=15.224(33)a.u. and alpha D,2=--5.30(11)a.u., the permanent hexadecapole moment, pi=--0.69(28)a.u., and the reduced dipole and octupole matrix elements coupling the ground state to the 6 d 2D3/2 state, ||=1.436(2) a.u. and ||=3.3(1.1) a.u.

Keele, Julie Adel

303

Deep permeable fault-controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States  

USGS Publications Warehouse

This study assesses the relative importance of deeply circulating meteoric water and direct mantle fluid inputs on near-surface 3He/4He anomalies reported at the Coso and Beowawe geothermal fields of the western United States. The depth of meteoric fluid circulation is a critical factor that controls the temperature, extent of fluid-rock isotope exchange, and mixing with deeply sourced fluids containing mantle volatiles. The influence of mantle fluid flux on the reported helium anomalies appears to be negligible in both systems. This study illustrates the importance of deeply penetrating permeable fault zones (10-12 to 10-15 m2) in focusing groundwater and mantle volatiles with high 3He/4He ratios to shallow crustal levels. These continental geothermal systems are driven by free convection.

Banerjee, Amlan; Person, Mark; Hofstra, Albert; Sweetkind, Donald S.; Cohen, Denis; Sabin, Andrew; Unruh, Jeff; Zyvoloski, George; Gable, Carl W.; Crossey, Laura; Karlstrom, Karl

2011-01-01

304

Fine Structure and Ionization Energy of the 1 s 2 s 2 p 4P State of the Helium Negative Ion He-  

NASA Astrophysics Data System (ADS)

The fine structure and ionization energy of the 1 s 2 s 2 p 4P state of the helium negative ion He- are calculated in Hylleraas coordinates, including relativistic and QED corrections up to O (?4m c2) , O ((? /M )?4m c2) , O (?5m c2) , and O ((? /M )?5m c2) . Higher order corrections are estimated for the ionization energy. A comparison is made with other calculations and experiments. We find that the present results for the fine structure splittings agree with experiment very well. However, the calculated ionization energy deviates from the experimental result by about 1 standard deviation. The estimated theoretical uncertainty in the ionization energy is much less than the experimental accuracy.

Wang, Liming; Li, Chun; Yan, Zong-Chao; Drake, G. W. F.

2014-12-01

305

One-dimensional Rydberg gas in a Magneto-Electric Trap  

Microsoft Academic Search

We investigate the possibility to trap and align ultracold Rydberg atoms in the regime where both the (coupled) center of mass and electronic motion of the Rydberg atom are of quantum nature. First we explore the properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap being commonly used in ultracold atomic physics experiments. A computational scheme projecting on a single

Peter Schmelcher

2008-01-01

306

Motion-induced signal revival in pulsed Rydberg four-wave mixing beyond the frozen-gas limit  

NASA Astrophysics Data System (ADS)

We present measurements on pulsed four-wave mixing involving a Rydberg state in an atomic vapor cell. The excitation to the Rydberg state is conducted by a pulsed two-photon excitation on the nanosecond time scale that is combined with a third cw laser in phase-matched geometry yielding light emission on the same time scale. An additional signal peak is observed shortly after the pulse that can be attributed to a revival of constructive interference between different velocity classes of the radiating atomic dipoles. Furthermore we investigate the density dependence of the four-wave mixing signal. From the shape of the respective curve we are able to confirm energy and momentum conservation in the photonic part of the system.

Huber, B.; Kölle, A.; Pfau, T.

2014-11-01

307

Sub-wavelength imaging and field mapping via electromagnetically induced transparency and Autler-Townes splitting in Rydberg atoms  

SciTech Connect

We present a technique for measuring radio-frequency (RF) electric field strengths with sub-wavelength resolution. We use Rydberg states of rubidium atoms to probe the RF field. The RF field causes an energy splitting of the Rydberg states via the Autler-Townes effect, and we detect the splitting via electromagnetically induced transparency (EIT). We use this technique to measure the electric field distribution inside a glass cylinder with applied RF fields at 17.04?GHz and 104.77?GHz. We achieve a spatial resolution of ?100??m, limited by the widths of the laser beams utilized for the EIT spectroscopy. We numerically simulate the fields in the glass cylinder and find good agreement with the measured fields. Our results suggest that this technique could be applied to image fields on a small spatial scale over a large range of frequencies, up into the sub-terahertz regime.

Holloway, Christopher L., E-mail: holloway@boulder.nist.gov; Gordon, Joshua A. [National Institute of Standards and Technology (NIST), Electromagnetics Division, U.S. Department of Commerce, Boulder Laboratories, Boulder, Colorado 80305 (United States); Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2014-06-16

308

Two-stage Rydberg charge exchange in a strong magnetic field  

SciTech Connect

We have performed calculations of two successive charge transfers from Rydberg states in a strong magnetic field. In the first charge transfer, a positron interacts with a highly excited atom to form positronium. In the second stage, the positronium interacts with an antiproton to give antihydrogen. For many parameters, our results are in qualitative agreement with previous calculations with no magnetic field. However, we do find that there are important changes which may affect the usefulness of the method for efficient formation of antihydrogen that can be trapped.

Wall, M. L.; Norton, C. S.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States)

2005-11-15

309

Single-photon nonlinearity with intracavity electromagnetically induced transparency in blockaded Rydberg ensemble  

E-print Network

A scheme is presented to realize strong single-photon nonlinearity with intracavity electromagnetically induced transparency in blockaded Rydberg ensemble. In our scheme, the photons in the cavity are in the form of cavity dark-state polaritons and thus the effect of tuning the control field is equivalent to that of changing the cavity quality factors $Q$. Profiting from this especial feature, the system behaves very strong single-photon nonlinearity, and the nonlinear strength would be three orders of magnitude larger than both the effective cavity decay rate and atomic decay rate. We also show the application of the strong nonlinearity to strong photon blockade effect.

G. W. Lin; J. Yang; X. M. Lin; Y. P. Niu; S. Q. Gong

2014-01-19

310

Influence of a dc offset field on kicked quasi-one-dimensional Rydberg atoms: Stabilization and frustrated field ionization  

Microsoft Academic Search

The influence of a superposed offset field on the response of highly polarized (quasi-1D) very-high-n Rydberg atoms to a periodic train of unidirectional half-cycle pulses (HCPs) is investigated, both experimentally and theoretically. It is observed that the presence of an offset field strongly influences the dynamics. The electronic states become transiently stabilized and trapped near the ionization threshold when the

S. Yoshida; C. O. Reinhold; J. Burgdoerfer; W. Zhao; J. J. Mestayer; J. C. Lancaster; F. B. Dunning

2006-01-01

311

Influence of a dc offset field on kicked quasi-one-dimensional Rydberg atoms: Stabilization and frustrated field ionization  

Microsoft Academic Search

The influence of a superposed offset field on the response of highly polarized (quasi-1D) very-high- n Rydberg atoms to a periodic train of unidirectional half-cycle pulses (HCPs) is investigated, both experimentally and theoretically. It is observed that the presence of an offset field strongly influences the dynamics. The electronic states become transiently stabilized and trapped near the ionization threshold when

S. Yoshida; Carlos O Reinhold; J. Burgdörfer; W. Zhao; J. J. Mestayer; J. C. Lancaster; F. B. Dunning

2006-01-01

312

Quantum Incompressibility of a Falling Rydberg Atom, and a Gravitationally-Induced Charge Separation Effect in Superconducting Systems  

Microsoft Academic Search

Freely falling point-like objects converge toward the center of the Earth. Hence the gravitational field of the Earth is inhomogeneous,\\u000a and possesses a tidal component. The free fall of an extended quantum mechanical object such as a hydrogen atom prepared in\\u000a a high principal-quantum-number state, i.e. a circular Rydberg atom, is predicted to fall more slowly than a classical point-like

R. Y. Chiao; S. J. Minter; K. Wegter-McNelly; L. A. Martinez

313

Dependence on collisional energy of negative ion formation in collisions of He(14 1P) Rydberg atoms with SF6  

Microsoft Academic Search

The formation of negative ions by electron attachment in collisions of He atoms in the well-defined low-Rydberg state (n=14)1P with SF6 is studied as a function of the relative velocity of the reactants in a crossed-beam experiment at thermal energies. The data show that the cross section does not follow the behavior predicted by the free electron model; it presents

A. Pesnelle; M. Perdrix; G. Watel

1992-01-01

314

Experimental investigation of non-hydrogenic orbits in helium recurrence spectra  

SciTech Connect

Refinements in data aquisition have allowed the authors to capture the first recurrence spectra of helium. Using experimental techniques previously described, they have obtained recurrence spectra for scaled energies {epsilon} ={minus}3,{minus}4, and {minus}5 in the principal quantum number region n=20-30 ({epsilon}=EF{sup {minus}1/2}, where E is the binding energy of the Rydberg electron, and F is the strength of the Stark field in a.u.). Calculated recurrence spectra developed using theoretical Stark map data agree reasonably well with the present experimental results. With continued refinements in both theoretical and experimental methods the authors expect to produce clearer correlation between calculated and experimental spectra. For {epsilon} ={minus}5, the primary non-hydrogenic characteristics in the helium scaled action spectra prior to taking the Fourier transform is in the {open_quotes}p-branch{close_quotes} of the Stark manifold. By eliminating selected hydrogenic features from the experimental spectra the authors have identified the scaled action of several helium-specific orbits. Future experimentation will yield precision scaled action maps of helium-specific orbits as a function of scaled energy, providing detailed information on the effects of the core electron on classical Rydberg orbits.

Keeler, M.L.; Cullinan, D.W.; Morgan, T.J.

1996-05-01

315

A portable helium sniffer  

USGS Publications Warehouse

A portable helium sniffer has been developed for field use. The instrument is mounted in a four-wheel-drive pickup truck and can detect 50 parts per billion of helium in soil gas. The usefulness of helium sniffing in soil is being investigated as a prospecting tool in gas, oil, uranium, and geothermal prospecting as well as in earthquake prediction.

Friedman, Irving; Denton, E.H.

1976-01-01

316

Tungsten Helium cooled Target  

E-print Network

Rotating Tungsten Helium cooled Target RoTHeTa Cyril Kharoua Daniela Ene, Ferenc Mezei, Etam Noah 2011 Some history >Granular Tungsten target helium cooled was first proposed by Peter Sievers for a MW a rotating wheel, fitted with tungsten rods and cooled with helium is a viable solution... #12;Page 4Cyril

McDonald, Kirk

317

Helium-Recycling Plant  

NASA Technical Reports Server (NTRS)

Proposed system recovers and stores helium gas for reuse. Maintains helium at 99.99-percent purity, preventing water vapor from atmosphere or lubricating oil from pumps from contaminating gas. System takes in gas at nearly constant low back pressure near atmospheric pressure; introduces little or no back pressure into source of helium. Concept also extended to recycling of other gases.

Cook, Joseph

1996-01-01

318

a New Value for the Rydberg Constant by Precision Measurement of the Hydrogen Balmer-Beta Transition.  

NASA Astrophysics Data System (ADS)

The Rydberg constant {rm R }_infty is determined to a very high accuracy of 3 parts in 10^{10 } by a direct comparison of the four hydrogen and deuterium Balmer-beta transitions with a standard laser from the National Bureau of Standards. This experiment is now the most precise measurement for {rm R}_infty and approaches the limits of accuracy for wavelength or frequency measurements in the visible region. The result is {rm R}_infty = 109 737.315 73 (3) {rm cm}^{-1} with the definition of the meter: c = 299 792 458 m/sec. The experiment also yields the following results: The fine structure splittings 4{rm P}_ {1/2} rightarrow {rm 4P}_{3/2} in H: 1370.9 (3) MHz and in D: 1371.8 (3) MHz. The isotope shifts between H and D in the transitions {rm 2S}_{1/2} rightarrow {rm 4P}_{1/2}: 167 752.4 (3) MHz and {rm 2S}_{1/2 } rightarrow {rm 4P}_{3/2}: 167 753.3 (3) MHz. The experiment utilizes atomic beam laser spectroscopy. A beam of atomic hydrogen (or deuterium) is excited by electron bombardment to the metastable {rm 2S }_{1/2} state and is detected by a secondary electron emission detector. A chopped cw dye laser beam crosses the atomic beam at an angle of 90^circ to eliminate Doppler broadening. The metastables are quenched by laser excitation to {rm 4P}_{1/2} or {rm 4P}_{3/2 } states. The signal is monitored by a lock -in amplifier with the chopper as reference. An iodine (^{127}{ rm I}_2) stabilized helium-neon (He-Ne) laser is the primary standard with an accuracy of 1.6 times 10^{ -10}. Another He-Ne laser is locked to the standard laser with a variable offset frequency controlled by an oscillator. A frequency chain is established by locking together a dye laser, a piezoelectrically controlled measuring etalon and the offset laser. This chain allows the dye laser to scan across the Balmer-beta line in a precisely controllable manner. The lineshape and offset frequency are recorded simultaneously. Possible sources of systematic shifts and errors are carefully investigated. Hydrogen energy levels are calculated according to most recent values of physical constants. {rm R}_infty is obtained by comparing the measured and calculated hydrogen Balmer-beta transition. The result is in good agreement with the two most recent, but less precise experiments.

Zhao, Ping

319

Stabilized double-electron capture in Ne{sup 10+}-He collisions: Velocity dependence of Rydberg-electron {ital n},{ital l} distributions  

SciTech Connect

The distribution over the {ital n} states populated by double-electron capture in Ne{sup 10+}-He collisions has been determined in the energy range of 0.9--9 keV/u by analyzing the radiative decays of projectile Rydberg transitions. It has been found to be in fair agreement with predictions of the autotransfer-to-Rydberg-states model of Roncin {ital et} {ital al}. [J. Phys. B 26, 4181 (1993)]. Double-capture stabilization ratio {ital R}{sub {ital S}}, defined as the ratio of true double capture {sigma}{sub TDC} to the sum of {sigma}{sub TDC} and autoionizing double capture {sigma}{sub ADC}, has been studied at various energies. A slight enhancement of {ital R}{sub {ital S}} (35--50 %) and an increase by a factor of 5 of the cross sections for emission of optical transitions from (3,{ital n}) Rydberg states have been found as the projectile velocity decreases from 0.6 to 0.19 a.u. We propose a tentative explanation following a model of postcollisional satellization of Rydberg electrons.

Martin, S.; Bernard, J.; Chen, L.; Denis, A.; Desesquelles, J. [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite de Lyon 1, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France)] [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite de Lyon 1, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France)

1995-08-01

320

Stark Shifts in the Spectra of Long-Range Rydberg Molecules  

NASA Astrophysics Data System (ADS)

Theoretical studies using a variety of models [Hamilton, Greene,and Sadeghpour, J. Phys. B, (2002), Khuskivadze, Chibisov, and Fabrikant, Phys. Rev. A, (2002)] have predicted the existence of several classes of molecular bound states arising from the interaction between a Rydberg atom and a ground state perturbing atom in an ultracold dilute gas. We present an exploration of the behavior of the spectral structure of these states under the influence of a weak external electric field. This information provides a diagnostic for distinguishing such states from other resonance phenomena in an experimental sample. Additionally, since these states are known to have unusually large dipole moments, characterizing their interaction with electric fields may be of practical interest for proposing future laboratory applications.

Hamilton, Edward L.; Greene, Chris H.

2003-05-01

321

Strongly correlated growth of Rydberg aggregates in a vapor cell  

E-print Network

The observation of strongly interacting many-body phenomena in atomic gases typically requires ultracold samples. Here we show that the strong interaction potentials between Rydberg atoms enable the observation of many-body effects in an atomic vapor, even at room temperature. We excite Rydberg atoms in cesium vapor and observe in real-time an out-of-equilibrium excitation dynamics that is consistent with an aggregation mechanism. The experimental observations show qualitative and quantitative agreement with a microscopic theoretical model. Numerical simulations reveal that the strongly correlated growth of the emerging aggregates is reminiscent of soft-matter type systems.

A. Urvoy; F. Ripka; I. Lesanovsky; D. Booth; J. P. Shaffer; T. Pfau; R. Löw

2015-03-09

322

Helium in the Universe.  

NASA Astrophysics Data System (ADS)

The element helium was discovered on Earth in March 1895, although its existence had been suggested much earlier by J.N. Lockyer after unidentified spectral lines had been observed in a solar eclipse in 1868. Helium plays a major role in astronomy and cosmology. As a radioactive decay product, it helped to establish the great age of the Earth. Nuclear reactions, producing helium from hydrogen, power most stars and nuclear reactions involving helium are important in late stages of stellar evolution. All stars and gas clouds appear to contain substantial amounts of helium and this observation, together with the discovery and properties of the cosmic microwave radiation, is one of the two factors leading to the current popularity of the hot big-bang cosmological theory. Because helium is such a strongly bound nucleus, a single secure identification of a star or a gas cloud devoid of helium would cause great difficulties for the theory.

Tayler, R. J.

1995-02-01

323

Solving the electron and electron-nuclear Schroedinger equations for the excited states of helium atom with the free iterative-complement-interaction method  

SciTech Connect

Very accurate variational calculations with the free iterative-complement-interaction (ICI) method for solving the Schroedinger equation were performed for the 1sNs singlet and triplet excited states of helium atom up to N=24. This is the first extensive applications of the free ICI method to the calculations of excited states to very high levels. We performed the calculations with the fixed-nucleus Hamiltonian and moving-nucleus Hamiltonian. The latter case is the Schroedinger equation for the electron-nuclear Hamiltonian and includes the quantum effect of nuclear motion. This solution corresponds to the nonrelativistic limit and reproduced the experimental values up to five decimal figures. The small differences from the experimental values are not at all the theoretical errors but represent the physical effects that are not included in the present calculations, such as relativistic effect, quantum electrodynamic effect, and even the experimental errors. The present calculations constitute a small step toward the accurately predictive quantum chemistry.

Nakashima, Hiroyuki; Hijikata, Yuh; Nakatsuji, Hiroshi [Quantum Chemistry Research Institute, JST CREST, Kyodai Katsura Venture Plaza 106, Goryo Oohara 1-36, Nishikyo-ku, Kyoto 615-8245 (Japan) and Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

2008-04-21

324

Atomic approaches in metastable antiprotonic helium atoms. Reply to Analysis of the lifetimes and fractions of antiprotons trapped in metastable antiprotonic helium states by I. Shimamhura and M. Kimura  

NASA Astrophysics Data System (ADS)

In the present note the authors clarify the purpose of YO and complement its essential points, thus showing that the criticisms of SK are inappropriate. The paper YO was aimed at discussing some new aspects related to the metastability of hadronic helium atoms which had been discovered when negative kaons, negative pions and antiprotons were stopped in liquid helium. The delayed fraction, time spectrum shape and lifetimes were the observables. Further experimental studies are in progress, and as of today there is no successful explanation for these interesting phenomena. So, YO tried to give brief and rather qualitative estimates for the observations in an intuitive way, considering only the leading terms. The following problems are discussed in as simple a manner as possible, starting from the exotic-atom viewpoints of Condo and Russell: (1) the atomic core polarization effect; (2) the structure and radiative lifetimes; (3) the non-statistical distribution of the angular momentum and an estimate of the delayed fraction; and (4) the isotope effect, though the title represents only (1). To respond to the comments of SK, it is important to consider the correspondence between the atomic approach and the molecular approach for the metastable antiprotonic helium atom of Condo-Russell. We therefore begin this note with a discussion of this aspect.

Yamazaki, Toshimitsu; Ohtsuki, Kazumasa

1994-08-01

325

Ultracold Rydberg atoms in a magneto-electric trap  

Microsoft Academic Search

We investigate the quantum properties of an ultracold Rydberg atom exposed to a magnetic quadrupole field and a homogeneous electric field. The properly transformed Hamiltonian explicitly depends on the conserved total angular momentum and couples the centre of mass and electronic degrees of freedom. The corresponding Schrödinger equation is solved by an adiabatic separation focusing on a fixed n-manifold. The

Ulrich Schmidt; Igor Lesanovsky; Peter Schmelcher

2007-01-01

326

Ab Initio Equations of State for Hydrogen (H-REOS.3) and Helium (He-REOS.3) and their Implications for the Interior of Brown Dwarfs  

NASA Astrophysics Data System (ADS)

We present new equations of state (EOSs) for hydrogen and helium covering a wide range of temperatures from 60 K to 107 K and densities from 10-10 g cm-3 to 103 g cm-3. They include an extended set of ab initio EOS data for the strongly correlated quantum regime with an accurate connection to data derived from other approaches for the neighboring regions. We compare linear mixing isotherms based on our EOS tables with available real mixture data. A first important astrophysical application of this new EOS data is the calculation of interior models for Jupiter and comparison with recent results. Second, mass-radius relations are calculated for Brown Dwarfs (BDs) which we compare with predictions derived from the widely used EOS of Saumon, Chabrier, and van Horn. Furthermore, we calculate interior models for typical BDs with different masses, namely, Corot-3b, Gliese-229b, and Corot-15b, and the giant planet KOI-889b. The predictions for the central pressures and densities differ by up to 10% dependent on the EOS used. Our EOS tables are made available in the supplemental material of this paper.

Becker, Andreas; Lorenzen, Winfried; Fortney, Jonathan J.; Nettelmann, Nadine; Schöttler, Manuel; Redmer, Ronald

2014-12-01

327

Ab initio equations of state for hydrogen (H-REOS.3) and helium (He-REOS.3) and their implications for the interior of Brown Dwarfs  

E-print Network

We present new equations of state (EOS) for hydrogen and helium covering a wide range of temperatures from 60 K to 10$^7$ K and densities from $10^{-10}$ g/cm$^3$ to $10^3$ g/cm$^3$. They include an extended set of ab initio EOS data for the strongly correlated quantum regime with an accurate connection to data derived from other approaches for the neighboring regions. We compare linear-mixing isotherms based on our EOS tables with available real-mixture data. A first important astrophysical application of this new EOS data is the calculation of interior models for Jupiter and the comparison with recent results. Secondly, mass-radius relations are calculated for Brown Dwarfs which we compare with predictions derived from the widely used EOS of Saumon, Chabrier and van Horn. Furthermore, we calculate interior models for typical Brown Dwarfs with different masses, namely Corot-3b, Gliese-229b and Corot-15b, and the Giant Planet KOI-889b. The predictions for the central pressures and densities differ by up to 10...

Becker, Andreas; Fortney, Jonathan J; Nettelmann, Nadine; Schöttler, Manuel; Redmer, Ronald

2014-01-01

328

Reply to 'Comment on 'Doubly excited bound and resonance ({sup 3}P{sup e}) states of helium''  

SciTech Connect

In response to the comment by Kar and Ho [Phys. Rev. A 82, 036501 (2010)], we have clarified the reason for anomaly between our and their results for the resonance states below the N=5 ionization threshold of He{sup +}.

Saha, Jayanta K.; Mukherjee, Tapan K. [Narula Institute of Technology, Agarpara, Kolkata 700 109 (India)

2010-09-15

329

Vacuum ultraviolet-infrared photo-induced Rydberg ionization spectroscopy: C-H stretching frequencies for trans-2-butene and trichloroethene cations  

NASA Astrophysics Data System (ADS)

We have demonstrated the two-color vacuum ultraviolet (VUV)-infrared (IR) photoinduced Rydberg ionization (PIRI) experiment. Trichloroethene (ClCH=CCl2) and trans-2-butene (trans-CH3CH=CHCH3) were prepared in Rydberg states in the range of effective principal quantum number n*?7-93 by VUV excitation prior to IR-induced autoionization. The observed VUV-IR-PIRI spectra are found to be independent of n*, suggesting that the electron Rydberg orbital is conserved, i.e., the Rydberg electron is behaving as a spectator during the excitation process. The observed IR active C-H stretching vibrational frequencies ?12+=3072±5 cm-1 for ClCH=CCl2+ and ?23+=2908±3 cm-1, ?25+=2990±10 cm-1 and ?30+=3022±10 cm-1 for trans-CH3CH=CHCH3+ are compared with predictions based on ab initio quantum-chemical procedures and density functional calculations.

Woo, H. K.; Wang, P.; Lau, K.-C.; Xing, X.; Ng, C. Y.

2004-01-01

330

Quenching of the resonance 5s(3P1) state of krypton atoms in collisions with krypton and helium atoms  

NASA Astrophysics Data System (ADS)

The processes of collision quenching of the resonance 5s[3/2]1o(3P1) state of the krypton atom are studied by the absorption probe method in electron-beam-excited high-pressure He – Kr mixtures with a low content of krypton. The rate constants of plasmochemical reactions Kr* + Kr + He ? Kr*2 + He [(4.21 ± 0.42) × 10-33 cm6 s-1], Kr* + 2He ? HeKr* + He [(4.5 ± 1.2) × 10-36 cm6 s-1] and Kr* + He ? products + He [(2.21 ± 0.22) × 10-15 cm3 s-1] are measured for the first time. The rate constants of similar reactions are refined for krypton in the metastable 5s[3/2]2o (3P2) state.

Zayarnyi, D. A.; L'dov, A. Yu; Kholin, I. V.

2014-11-01

331

A giant electro-optic effect using polarizable dark states  

E-print Network

by another light beam, is the basis of Kerr lens mode-locking4 , and has led to the development of femto in thermal rubidium vapour17 , and subsequently Table 1 The value of the Kerr coefficient, B0, for various Rydberg EIT to measure the d.c. Kerr effect in thermal rubidium vapour. As Rydberg states have

Loss, Daniel

332

Some calculations on the ground and lowest-triplet state of helium in the fixed-nucleus approximation  

SciTech Connect

The series solution method developed by Pekeris [Phys. Rev. 112, 1649 (1958); 115, 1216 (1959)] for the Schroedinger equation for two-electron atoms, as generalized by Frost [ital et] [ital al]. [J. Chem. Phys. 41, 482 (1964)] to handle any three particles with a Coulomb interaction, has been used. The wave function is expanded in triple orthogonal set in three [ital perimetric] coordinates. From the Schroedinger equation an explicit recursion relation for the coefficients in the expansion is obtained, and the vanishing of the determinant of these coefficients provides the condition for the energy eigenvalues and for the eigenvectors. The Schroedinger equation is solved and the matrix elements are produced algebraically by using the computer algebra system MAPLE. The substitutions for a particular atom and diagonalization were performed by a program written in the C language. Since the determinant is sparse, it is possible to go to the order of 1078 as Pekeris did without using excessive memory or computer CPU time. By using a nonlinear variational parameter in the expression used to remove the energy, nonrelativistic energies, within the fixed-nucleus approximation, have been obtained. For the ground-state singlet 1 [sup 1][ital S] state, this is of the accuracy claimed by Frankowski and Pekeris [Phys. Rev. 146, 46 (1966); 150, 366(E) (1966)] using logarithmic terms for [ital Z] from 1 to 10, and for the triplet 2 [sup 3][ital S] state, energies have been obtained to 12 decimal places of accuracy, which, with the exception of [ital Z]=2, are lower than any previously published, for all [ital Z] from 3 to 10.

Cox, H. (Department of Mathematics, University of York, Heslington, York, YO15DD (United Kingdom)); Smith, S.J.; Sutcliffe, B.T. (Department of Chemistry, University of York, Heslington, York, YO15DD (United Kingdom))

1994-06-01

333

Many-body Rabi oscillations of Rydberg excitation in small mesoscopic samples  

E-print Network

We investigate the collective aspects of Rydberg excitation in ultracold mesoscopic systems. Strong interactions between Rydberg atoms influence the excitation process and impose correlations between excited atoms. The manifestations of the collective behavior of Rydberg excitation are the many-body Rabi oscillations, spatial correlations between atoms as well as the fluctuations of the number of excited atoms. We study these phenomena in detail by numerically solving the many-body Schr\\"edinger equation.

J. Stanojevic; R. Côté

2008-01-15

334

Singlet-triplet energy splitting between 1D and 3D (1s2 2s nd), n = 3, 4, 5, and 6, Rydberg states of the beryllium atom (9Be) calculated with all-electron explicitly correlated Gaussian functions  

NASA Astrophysics Data System (ADS)

Accurate variational nonrelativistic quantum-mechanical calculations are performed for the five lowest 1D and four lowest 3D states of the 9Be isotope of the beryllium atom. All-electron explicitly correlated Gaussian (ECG) functions are used in the calculations and their nonlinear parameters are optimized with the aid of the analytical energy gradient determined with respect to these parameters. The effect of the finite nuclear mass is directly included in the Hamiltonian used in the calculations. The singlet-triplet energy gaps between the corresponding 1D and 3D states, are reported.

Sharkey, Keeper L.; Bubin, Sergiy; Adamowicz, Ludwik

2014-11-01

335

PURIFICATION OF HELIUM COOLANT  

Microsoft Academic Search

The literature from 1955 to 1961 on the purification of helium coolant, ; especially on the separatiqn of fission gases, is reviewed. The principle of gas ; purification, the separation of radioactive and nonradioactive gases, and ; purification systems for helium coolant are covered. 184 references. (D.C.W.)

K. Oshima; K. Naito; K. Nishida

1963-01-01

336

Rotational superfluidity in small helium droplets.  

PubMed

The first minimum appearing in molecular rotational constants as a function of helium droplet size has been previously associated with the onset of superfluidity in these finite systems. We investigate this relationship by bosonic density functional theory calculations of classical molecular rotors (OCS, N2O, CO, and HCN) interacting with the surrounding helium. The calculated rotational constants are in fair agreement with the existing experimental data, demonstrating the applicability of the theoretical model. Inspection of the spatial evolution of the global phase and density shows the increase in the rotational constant after the first minimum correlates with continuous coverage of the molecule by helium and the appearance of angular phase coherence rather than completion of the first solvent shell. We assign the observed phenomenon to quantum phase transition between a localized state and one-dimensional superfluid, which represents the onset of rotational superfluidity in small helium droplets. PMID:25099743

Mateo, David; Gonzalez, Frisly; Eloranta, Jussi

2015-03-19

337

Advanced helium magnetometer for space applications  

NASA Technical Reports Server (NTRS)

The goal of this effort was demonstration of the concepts for an advanced helium magnetometer which meets the demands of future NASA earth orbiting, interplanetary, solar, and interstellar missions. The technical effort focused on optical pumping of helium with tunable solid state lasers. We were able to demonstrate the concept of a laser pumped helium magnetometer with improved accuracy, low power, and sensitivity of the order of 1 pT. A number of technical approaches were investigated for building a solid state laser tunable to the helium absorption line at 1083 nm. The laser selected was an Nd-doped LNA crystal pumped by a diode laser. Two laboratory versions of the lanthanum neodymium hexa-aluminate (LNA) laser were fabricated and used to conduct optical pumping experiments in helium and demonstrate laser pumped magnetometer concepts for both the low field vector mode and the scalar mode of operation. A digital resonance spectrometer was designed and built in order to evaluate the helium resonance signals and observe scalar magnetometer operation. The results indicate that the laser pumped sensor in the VHM mode is 45 times more sensitive than a lamp pumped sensor for identical system noise levels. A study was made of typical laser pumped resonance signals in the conventional magnetic resonance mode. The laser pumped sensor was operated as a scalar magnetometer, and it is concluded that magnetometers with 1 pT sensitivity can be achieved with the use of laser pumping and stable laser pump sources.

Slocum, Robert E.

1987-01-01

338

48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.  

Code of Federal Regulations, 2010 CFR

... false Required Sources for Helium and Helium Usage Data. 52.208-8...208-8 Required Sources for Helium and Helium Usage Data. As prescribed...clause: Required Sources for Helium and Helium Usage Data (APR 2002)...

2010-10-01

339

Rydberg Ion Fine Structure Measurements with the RESIS Method  

NASA Astrophysics Data System (ADS)

Measurements of Rydberg fine structure provide precise determinations of positive ion properties such as polarizabilities and permanent moments. The Resonant Excitation Stark Ionization Spectroscopy (RESIS) method, which has provided a range of such measurements in neutral atoms and molecules [1], has recently been extended to study of Rydberg ion fine structure. In principal, the method can be applied to study positive ions of arbitrary charge. The factors limiting signal to noise and frequency resolution in measurements of this type will be discussed, and some possible future applications will be described. [1] S.R. Lundeen in Advances in Atomic, Molecular, and Optical Physics, edited by Chun C. Lin and Paul Berman (Academic Press, 2005), Vol 52, pp. 161-208

Fehrenbach, C. W.; Lundeen, S. R.

2007-06-01

340

Photon blockade induced by atoms with Rydberg coupling  

E-print Network

We study the photon blockade of two-photon scattering in a one-dimensional waveguide, which contains two atoms coupled via the Rydberg interaction. We obtain the analytic scattering solution of photonic wave packets with the Laplace transform method. We examine the photon correlation by addressing the two-photon relative wave function and the second-order correlation function in the single- and two-photon resonance cases. It is found that, under the single-photon resonance condition, photon bunching and antibunching can be observed in the two-photon transmission and reflection, respectively. In particular, the bunching and antibunching effects become stronger with the increasing of the Rydberg coupling strength. In addition, we find a phenomenon of bunching-antibunching transition caused by the two-photon resonance.

Jin-Feng Huang; Jie-Qiao Liao; C. P. Sun

2013-02-24

341

Coherent dynamics of Rydberg atoms in cosmic microwave background radiation  

E-print Network

Rydberg atoms excited by cold blackbody radiation are shown to display long-lived quantum coherences on timescales of tens of picoseconds. By solving non-Markovian equations of motion with no free parameters we obtain the time evolution of the density matrix, and demonstrate that the blackbody-induced temporal coherences manifest as slowly decaying (100 ps) quantum beats in time-resolved fluorescence. An analytic model shows the dependence of the coherent dynamics on the energy splitting between atomic eigenstates, transition dipole moments, and coherence time of the radiation. Experimental detection of the fluorescence signal from a trapped ensemble of $10^8$ Rydberg atom is discussed, but shown to be technically challenging at present, requiring CMB amplification somewhat beyond current practice.

Timur V. Tscherbul; Paul Brumer

2013-12-20

342

Engineering atomic wavepackets in very-high-n Rydberg atoms  

Microsoft Academic Search

The remarkable level of control of atomic wavepackets that can be achieved using very-high-n Rydberg atoms (n >= 350) is demonstrated. This control is accomplished with carefully-tailored sequences of short unidirectional electric-field pulses, termed half-cycle pulses (HCPs), with duration Tp ≪ Tn, where Tn is the classical orbital period. In this limit, each HCP simply delivers an impulsive momentum transfer

Wei Zhao

2007-01-01

343

Proton formation dynamics in the REMPI[2+n] process via the F 1Delta2 and f 3Delta2 Rydberg states of HCl investigated by three-dimensional velocity mapping.  

PubMed

HCl in the bulk gas phase at a pressure of 10(-5) mbar has been excited via selected Q-lines of the two-photon transition band systems F (1)Delta(2)<--X (1)Sigma(+)(1,0) [Q(8)], V (1)Sigma(+)<--X (1)Sigma(+)(14,0) [Q(8), Q(7)] and f (3)Delta(2)<--X (1)Sigma(+)(0,0) [Q(2-6)]. Concerning the V<--X excitation, subsequent photon absorption is known to yield HCl(+), H(n=2)+Cl, H(+)+Cl(-) and H+Cl(4s,4p,3d). Vibrationally excited HCl(+) (v(+) > or = 5) can be photodissociated to H(+)+Cl, and excited atoms can be easily photoionized by absorption of a fourth photon, respectively. Using three-dimensional velocity map imaging, the spatial proton velocity distributions resulting from these processes for these particular transitions were studied for the first time. Kvaran et al. [J. Chem. Phys. 131, 044324 (2009); J. Chem. Phys. 129, 164313 (2008)] recently reported a substantial increase in the formation of chlorine and hydrogen ions in single rovibrational transitions of the F (1)Delta(2) and f (3)Delta(2) band systems using mass resolved resonance enhanced multiphoton ionization spectroscopy and explained this by the vicinity of single rovibrational levels of the V (1)Sigma(+) state for which photorupture is the main feature. Thus, the known dissociation dynamics of the V (1)Sigma(+) state should also leave their fingerprint in the spatial proton velocity distribution emerging from the photodissociation of those states. Accordingly, we found a strong increase in the H(+) ion signal for the Q(5) line of the f (3)Delta(2)<--X (1)Sigma(+)(0,0) transition, the extra signal resulting from dissociation into H(n=2)+Cl((2)P(1/2)) and the ion pair. No increase for the HCl(+)(v(+) > or = 5) photodissociation channel or dissociation into H(n=2)+Cl((2)P(3/2)) has been observed. Furthermore, H(+) distributions from the Q transitions of the f (3)Delta(2)<--X (1)Sigma(+)(0,0) band system were found to show the two features previously ascribed to the "gateway" state [(4)Pi...4s](3)Pi(0), i.e., autoionization into HCl(+)(5 < or = v(+) < or = 8) and nonadiabatic dissociation into H(n=2)+Cl((2)P(3/2)). The F (1)Delta(2)<--X (1)Sigma(+)(1,0) band system only showed significant proton formation for the Q(8) line. The speed distribution is the same as for the Q(8,7) lines of the V (1)Sigma(+)<--X (1)Sigma(+)(14,0) transition while the excitation history is conserved in the angular distribution confirming the resonance interpretation. PMID:20632749

Kauczok, S; Maul, C; Chichinin, A I; Gericke, K-H

2010-07-14

344

Leakage detection method using helium  

Microsoft Academic Search

A means is disclosed for detecting helium which has flowed into a system by substitution for air at a leaking location and mixed with the remaining gases, and after the helium gas permeates a helium permeable membrane as a sample gas so that the air component unnecessary for detection is suppressed, the helium gas enters the space of a mass

H. Ishii; H. Morishita; K. Seki; T. Yamazaki

1983-01-01

345

The local interstellar helium density  

NASA Technical Reports Server (NTRS)

During the Apollo-Soyuz Test Project, an extreme-ultraviolet telescope observed the region of the sky from which the interstellar medium approaches the sun. The instrument had a tin filter whose bandpass included the 584-A line of neutral helium. The observations set an upper bound for the number density of neutral helium in the local interstellar medium of 0.004 + or - 0.0022 per cu cm, which is significantly lower than previously reported. The stated error is dominated by the present uncertainty in the solar 584-A flux, which is taken to be approximately 200 million photons/sq cm per sec at earth's orbit. The result is not consistent with previous resonant-scattering Ly-alpha observations of interstellar hydrogen passing through the solar system, which generally yield a hydrogen number density of about 0.1 per cu cm, unless interstellar helium is locally depleted below its cosmic abundance. The result is consistent with cosmic abundances if the much lower average hydrogen densities inferred from recent column-density measurements to nearby hot stars are in fact representative of the immediate solar neighborhood.

Freeman, J.; Paresce, F.; Bowyer, S.; Lampton, M.; Stern, R.; Margon, B.

1977-01-01

346

Dissipative Preparation of Spatial Order in Rydberg-Dressed Bose-Einstein Condensates  

E-print Network

We propose a technique for engineering momentum-dependent dissipation in Bose-Einstein condensates with non-local interactions. The scheme relies on the use of momentum-dependent dark-states in close analogy to velocity-selective coherent population trapping. During the short-time dissipative dynamics, the system is driven into a particular finite-momentum phonon mode, which in real space corresponds to an ordered structure with non-local density-density correlations. Dissipation-induced ordering can be observed and studied in present-day experiments using cold atoms with dipole-dipole or off-resonant Rydberg interactions. Due to its dissipative nature, the ordering does not require artificial breaking of translational symmetry by an opticallattice or harmonic trap. This opens up a perspective of direct cooling of quantum gases into strongly-interacting phases.

Johannes Otterbach; Mikhail Lemeshko

2014-06-07

347

Quantum incompressibility of a falling Rydberg atom, and a gravitationally-induced charge separation effect in superconducting systems  

Microsoft Academic Search

Freely falling point-like objects converge towards the center of the Earth.\\u000aHence the gravitational field of the Earth is inhomogeneous, and possesses a\\u000atidal component. The free fall of an extended quantum object such as a hydrogen\\u000aatom prepared in a high principal-quantum-number stretch state, i.e., a\\u000acircular Rydberg atom, is predicted to fall more slowly that a classical\\u000apoint-like

Raymond Y. Chiao

2010-01-01

348

Ab Initio Simulations of Dense Helium Plasmas  

SciTech Connect

We study the thermophysical properties of dense helium plasmas by using quantum molecular dynamics and orbital-free molecular dynamics simulations, where densities are considered from 400 to 800 g/cm{sup 3} and temperatures up to 800 eV. Results are presented for the equation of state. From the Kubo-Greenwood formula, we derive the electrical conductivity and electronic thermal conductivity. In particular, with the increase in temperature, we discuss the change in the Lorenz number, which indicates a transition from strong coupling and degenerate state to moderate coupling and partial degeneracy regime for dense helium.

Wang Cong [LCP, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); He Xiantu; Zhang Ping [LCP, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)

2011-04-08

349

Direct evidence of three-body interactions in a cold Rb85 Rydberg gas  

NASA Astrophysics Data System (ADS)

Cold Rydberg atoms trapped in a magneto-optical trap (MOT) are not isolated and they interact through dipole-dipole and multipole-multipole interactions. First-order dipole-dipole interactions and van der Waals interactions between two atoms have been intensively studied. However, the facts that the first-order dipole-dipole interactions and van der Waals interactions show the same size of broadening [A. Reinhard, K. C. Younge, T. C. Liebisch, B. Knuffman, P. R. Berman, and G. Raithel, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.100.233201 100, 233201 (2008)] and there are transitions between two dimer states [S. M. Farooqi, D. Tong, S. Krishnan, J. Stanojevic, Y. P. Zhang, J. R. Ensher, A. S. Estrin, C. Boisseau, R. Cote, E. E. Eyler, and P. L. Gould, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.91.183002 91, 183002 (2003); K. R. Overstreet, Arne Schwettmann, Jonathan Tallant, and James P. Shaffer, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.011403 76, 011403(R) (2007)] cannot be explained by the two-atom picture. The purpose of this article is to show the few-body nature of a dense cold Rydberg gas by studying the molecular-state microwave spectra. Specifically, three-body energy levels have been calculated. Moreover, the transition from three-body energy levels to two-body coupled molecular energy levels and to isolated atomic energy levels as a function of the internuclear spacing is studied. Finally, single-body, two-body, and three-body interaction regions are estimated according to the experimental data. The results reported here provides useful information for plasma formation, further cooling, and superfluid formation.

Han, Jianing

2010-11-01

350

ccsd00002314, Coherence-preserving trap architecture for long-term control of giant Rydberg atoms  

E-print Network

of giant Rydberg atoms P. Hya#12;l, 1 J. Mozley, 1 A. Perrin, 1 J. Tailleur, 1 G. Nogues, 1 M. Brune, 1 J a single Rydberg atom, make it long-lived and preserve an internal coherence over time scales reaching of the atomic energies using an external microwave #12;eld. We thoroughly identify and account for many causes

351

Ion-pair formation in the collision of high Rydberg argon atoms with SF6 and C6F6 and negative ion lifetimes  

Microsoft Academic Search

The ion-pair formation in collision between argon atoms in high Rydberg states (HR) with SF6 and C6F6 has been investigated. The absolute cross sections are inversely proportional to the Ar(HR) velocity and increase monotonically with increasing principal quantum number n. Measurements of the negative ion lifetimes against autodetachment are reported and are ?20 ?sec for SF6? and ?1 and ?20

I. Dimicoli; R. Botter

1981-01-01

352

Core helium flash  

SciTech Connect

The role of convection in the core helium flash is simulated by two-dimensional eddies interacting with the thermonuclear runaway. These eddies are followed by the explicit solution of the 2D conservation laws with a 2D finite difference hydrodynamics code. Thus, no phenomenological theory of convection such as the local mixing length theory is required. The core helium flash is violent, producing a deflagration wave. This differs from the detonation wave (and subsequent disruption of the entire star) produced in previous spherically symmetric violent core helium flashes as the second dimension provides a degree of relief which allows the expansion wave to decouple itself from the burning front. Our results predict that a considerable amount of helium in the core will be burned before the horizontal branch is reached and that some envelope mass loss is likely.

Cole, P.W.; Deupree, R.G.

1980-01-01

353

The Descending Helium Balloon  

ERIC Educational Resources Information Center

I describe a simple and fascinating experiment wherein helium leaks out of a rubber balloon, thereby causing it to descend. An estimate of the volumetric leakage rate is made by measuring its rate of descent.

Helseth, Lars Egil

2014-01-01

354

a Luttinger Liquid Core Inside HELIUM-4 Filled Nanopores  

NASA Astrophysics Data System (ADS)

As helium-4 is cooled below 2.17 K it undergoes a phase transition to a fundamentally quantum mechanical state of matter known as a superfluid which supports flow without viscosity. This type of dissipationless transport can be observed by forcing helium to travel through a narrow constriction that the normal liquid could not penetrate. Recent experiments have highlighted the feasibility of fabricating smooth pores with nanometer radii, that approach the truly one-dimensional limit where it is believed that a system of bosons (like helium-4) may have startlingly different behavior than in three dimensions. The one-dimensional system is predicted to have a linear hydrodynamic description known as Luttinger liquid (LL) theory, where no type of long range order can be sustained. In the limit where the pore radius is small, LL theory would predict that helium inside the channel behaves as a sort of quasi-supersolid with all correlations decaying as power-law functions of distance at zero temperature. We have performed large scale quantum Monte Carlo simulations of helium-4 inside nanopores of varying radii at low temperature with realistic helium.helium and helium-pore interactions. The results indicate that helium inside the nanopore forms concentric cylindrical shells surrounding a core that can be described via LL theory and provides insights into the exciting possibility of the experimental detection of this intriguing low-dimensional state of matter.

Del Maestro, Adrian

2014-10-01

355

Detection of Negative Charge Carriers in Superfluid Helium Droplets: The Metastable Anions He*– and He2*–  

PubMed Central

Helium droplets provide the possibility to study phenomena at the very low temperatures at which quantum mechanical effects are more pronounced and fewer quantum states have significant occupation probabilities. Understanding the migration of either positive or negative charges in liquid helium is essential to comprehend charge-induced processes in molecular systems embedded in helium droplets. Here, we report the resonant formation of excited metastable atomic and molecular helium anions in superfluid helium droplets upon electron impact. Although the molecular anion is heliophobic and migrates toward the surface of the helium droplet, the excited metastable atomic helium anion is bound within the helium droplet and exhibits high mobility. The atomic anion is shown to be responsible for the formation of molecular dopant anions upon charge transfer and thus, we clarify the nature of the previously unidentified fast exotic negative charge carrier found in bulk liquid helium. PMID:25068008

2014-01-01

356

Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field K. Afrousheh, P. Bohlouli-Zanjani, J. D. Carter, A. Mugford, and J. D. D. Martin  

E-print Network

Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field K electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transition 46d5/2 -47d5/2. The presence of a weak magnetic field 0.5 G reduced

Le Roy, Robert J.

357

Hyperfine structure in hydrogen and helium ion  

Microsoft Academic Search

The hyperfine structure (HFS) intervals of the ground state in a number of neutral atoms and singly charged ions can be measured with a high accuracy. However, theory even in the case of the simplest of them (such as hydrogen isotopes and the helium-3 ion) is essentially af- fected by nuclear structure effects which contribute from 30 to 200 ppm

Savely G. Karshenboima; D. I. Mendeleev

358

Experimental study of {mu}-atomic and {mu}-molecular processes in pure helium and deuterium-helium mixtures  

SciTech Connect

We present experimental results of {mu}-atomic and {mu}-molecular processes induced by negative muons in pure helium and helium-deuterium mixtures. The experiment was performed at the Paul Scherrer Institute (Switzerland). We measured relative intensities of muonic x-ray K series transitions in ({mu}{sup 3,4}He){sup *} atoms in pure helium as well as in helium-deuterium mixtures. The d{mu}{sup 3}He radiative decay probabilities for two different helium densities in D{sub 2}+{sup 3}He mixture were also determined. Finally, the q{sub 1s}{sup He} probability for a d{mu} atom formed in an excited state to reach the ground state was measured and compared with theoretical calculations using a simple cascade model.

Bystritsky, V.M.; Boreiko, V.F.; Gerasimov, V.V.; Pavlov, V.N.; Sandukovsky, V.G.; Stolupin, V.A.; Volnykh, V.P. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Czaplinski, W.; Popov, N.P.; Wozniak, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, PL-30059 Cracow (Poland); Filipowicz, M. [AGH University of Science and Technology, Faculty of Fuels and Energy, PL-30059 Cracow (Poland); Huot, O.; Knowles, P.E.; Schaller, L.A.; Schneuwly, H. [Department of Physics, University of Fribourg, CH-1700 Fribourg (Switzerland); Mulhauser, F. [University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2005-03-01

359

Broadband Rydberg Atom-Based Electric-Field Probe for SI-Traceable, Self-Calibrated Measurements  

NASA Astrophysics Data System (ADS)

We discuss a fundamentally new approach for the measurement of electric (E) fields that will lead to the development of a broadband, direct SI-traceable, compact, self-calibrating E-field probe (sensor). This approach is based on the interaction of radio frequency (RF) fields with alkali atoms excited to Rydberg states. The RF field causes an energy splitting of the Rydberg states via the Autler-Townes effect and we detect the splitting via electromagnetically induced transparency (EIT). In effect, alkali atoms placed in a vapor cell act like an RF-to-optical transducer, converting an RF E-field strength measurement to an optical frequency measurement. We demonstrate the broadband nature of this approach by showing that one small vapor cell can be used to measure E-field strengths over a wide range of frequencies: 1 GHz to 500 GHz. The technique is validated by comparing experimental data to both numerical simulations and far-field calculations for various frequencies. We also discuss various applications, including: a direct traceable measurement, the ability to measure both weak and strong field strengths, compact form factors of the probe, and sub-wavelength imaging and field mapping.

Holloway, Christopher L.; Gordon, Joshua A.; Jefferts, Steven; Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg

2014-12-01

360

SCREW COMPRESSOR CHARACTERISTICS FOR HELIUM REFRIGERATION SYSTEMS  

SciTech Connect

The oil injected screw compressors have practically replaced all other types of compressors in modern helium refrigeration systems due to their large displacement capacity, minimal vibration, reliability and capability of handling helium's high heat of compression.At the present state of compressor system designs for helium systems, typically two-thirds of the lost input power is due to the compression system. Therefore it is important to understand the isothermal and volumetric efficiencies of these machines to help properly design these compression systems to match the refrigeration process. This presentation summarizes separate tests that have been conducted on Sullair compressors at the Superconducting Super-Collider Laboratory (SSCL) in 1993, Howden compressors at Jefferson Lab (JLab) in 2006 and Howden compressors at the Spallation Neutron Source (SNS) in 2006. This work is part of an ongoing study at JLab to understand the theoretical basis for these efficiencies and their loss

Ganni, Venkatarao; Knudsen, Peter; Creel, Jonathan; Arenius, Dana; Casagrande, Fabio; Howell, Matt

2008-03-01

361

Improved helium line formation for EHe stars  

E-print Network

Quantitative analyses of extreme helium stars to date face the difficulty that theory fails to reproduce the observed helium lines in their entirety, wings and line cores. Here, we demonstrate how the issues can be resolved using state-of-the-art non-LTE line formation for these chemically peculiar objects. Two unique B-type objects are discussed in detail, the pulsating variable V652 Her and the metal-poor star HD144941. The improved non-LTE computations for helium show that analyses assuming LTE or based on older non-LTE model atoms can predict equivalent widths, for the HeI 10830A transition in particular, in error by up to a factor ~3. Our modelling approach also succeeds in largely resolving the general mismatch for effective temperatures of EHe stars derived from ionization equilibria and from spectral energy distributions.

N. Przybilla; K. Butler; U. Heber; C. S. Jeffery

2005-12-06

362

Full counting statistics of laser excited Rydberg aggregates in a one-dimensional geometry.  

PubMed

We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional atomic gas. We measure asymmetric excitation spectra and increased second and third order statistical moments of the Rydberg number distribution, from which we determine the average aggregate size. Estimating rates for different excitation processes we conclude that the aggregates grow sequentially around an initial grain. Direct comparison with numerical simulations confirms this conclusion and reveals the presence of liquidlike spatial correlations. Our findings demonstrate the importance of dephasing in strongly correlated Rydberg gases and introduce a way to study spatial correlations in interacting many-body quantum systems without imaging. PMID:24483893

Schempp, H; Günter, G; Robert-de-Saint-Vincent, M; Hofmann, C S; Breyel, D; Komnik, A; Schönleber, D W; Gärttner, M; Evers, J; Whitlock, S; Weidemüller, M

2014-01-10

363

Microwave probes Dipole Blockade and van der Waals Forces in a Cold Rydberg Gas  

E-print Network

We show that microwave spectroscopy of a dense Rydberg gas trapped on a superconducting atom chip in the dipole blockade regime reveals directly the dipole-dipole many-body interaction energy spectrum. We use this method to investigate the expansion of the Rydberg cloud under the effect of repulsive van der Waals forces and the breakdown of the frozen gas approximation. This study opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atoms.

Teixeira, R Celistrino; Nguyen, Thanh Long; Cantat-Moltrecht, T; Raimond, Jean-Michel; Haroche, S; Gleyzes, S; Brune, M

2015-01-01

364

Medium and high resolution vacuum UV photoabsorption spectroscopy of methyl iodide (CH 3I) and its deuterated isotopomers CD 3I and CH 2DI. A Rydberg series analysis  

NASA Astrophysics Data System (ADS)

The vacuum UV photoabsorption spectrum of CH 3I has been investigated between 5 eV and 20 eV. Numerous vibronic transitions are observed. In the high 10-20 eV photon energy range weak to very weak diffuse bands are observed and ascribed to electronic transitions from 3a 1, 1e and 2a 1 to Rydberg orbitals. In the 6-10.5 eV photon energy range more than 200 sharp and strong to weak lines have been observed. Several photon energy ranges were explored under high resolution conditions allowing us to observe many series up to high values of the principal quantum number n. They are assigned to vibrationless Rydberg transitions and classified into two groups converging to the two components of the spin-orbit split XE state of CH 3I +. These two groups consist of six different Rydberg series, i.e., nsa 1, npa 1, npe, nda 1, nde and nf. A very close correlation has been established between the term values of the Rydberg states in CH 3I and in Xe for ns, np, nd and nf Rydberg transitions. For the first time, the same measurements have been performed and the interpretation has been proposed for the photoabsorption spectrum of CH 2DI and CD 3I in the 6-10.5 eV photon energy range. For these two species, ionization energies are deduced: for the XE 3/2 and XE 1/2 states of CH 2DI, these are IE ad = 9.544 eV and IE ad = 10.168 eV, respectively, and the corresponding energies are 9.552 eV and 10.173 eV in CD 3I.

Locht, R.; Leyh, B.; Jochims, H. W.; Baumgärtel, H.

2009-11-01

365

Cavitation pressure in liquid helium  

Microsoft Academic Search

Recent experiments have suggested that, at low enough temperature, the homogeneous nucleation of bubbles occurs in liquid helium near the calculated spinodal limit. This was done in pure superfluid helium 4 and in pure normal liquid helium 3. However, in such experiments, where the negative pressure is produced by focusing an acoustic wave in the bulk liquid, the local amplitude

Frederic Caupin; Sebastien Balibar

2001-01-01

366

Helium, its extraction and purification  

Microsoft Academic Search

This is a general discussion of the extraction of helium from natural gas as practiced in the existing helium plants. Several phases of the helium extraction process, such as the refrigeration systems, and methods of carbon dioxide and water removal, are similar to those in natural gas processing. It is concluded that in cryogenic processes solid desiccants are more suited

R. W. Wilson; H. R. Newson

1967-01-01

367

Mantle Helium and Carbon Isotopes in Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon: Evidence for Renewed Volcanic Activity or a Long Term Steady State System?  

USGS Publications Warehouse

Here we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of strong crustal uplift currently occurring at a rate of 4-5 cm/yr (Wicks, et. al., 2001).Helium [RC/RA = 7.44 and 8.61 RA (RC/R A = (3He/4He)sample-. air corrected/(3He/4He)air))] and carbon (??13C = -11.59 to -9.03??? vs PDB) isotope data and CO2/3He (5 and 9 ?? 109) show that bubbling cold springs in the Separation Creek area near South Sister volcano carry a strong mantle signal, indicating the presence of fresh basaltic magma in the volcanic plumbing system. There is no evidence though, to directly relate this signal to the crustal uplift that is currently taking place in the area, which started in 1998. The geothermal system in the area is apparently much longer lived and shows no significant changes in chemistry compared to data from the early 1990s. Hot springs in the area, which are relatively far removed from the volcanic edifice, do not carry a strong mantle signal in helium isotope ratios (2.79 to 5.08 RA), unlike the cold springs, and also do not show any significant changes in helium isotope ratios compared to literature data for the same springs of over two decades ago. The cold springs of the Separation Creek area form a very diffuse but significant low temperature geothermal system, that should, due to its close vicinity to the center of up uplift, be more sensitive to changes in the deeper volcanic plumbing system than the far removed hot springs and therefore require much more study and consideration when dealing with volcano monitoring in the Cascade range or possibly with geothermal exploration in general.

Van Soest, M. C.; Kennedy, B.M.; Evans, William C.; Mariner, R.H.

2002-01-01

368

Electron spectroscopy of doubly-excited helium-like ions  

Microsoft Academic Search

Spectroscopic investigations of electrons coming from doubly-excited states of helium-like C and B ions have been made with zero-degree spectroscopies. These excited states are produced by two-electron capture collisions of bare ions with helium atoms. Electrons from the configurations of 2lnl' are observed in a wide energy range. Total angular momentum distributions in the double-electron transfer collisions are briefly discussed.

S. Ohtani; Y. Kanai; I. Yamada; H. A. Sakaue; Y. Awaya; T. Kambara; T. Nabeshima; N. Nakamura; H. Suzuki; T. Takayanagi; K. Wakiya; A. Danjo; M. Yoshino

1991-01-01

369

Detailed and Simplified Nonequilibrium Helium Ionization in the Solar Atmosphere  

NASA Astrophysics Data System (ADS)

Helium ionization plays an important role in the energy balance of the upper chromosphere and transition region. Helium spectral lines are also often used as diagnostics of these regions. We carry out one-dimensional radiation-hydrodynamics simulations of the solar atmosphere and find that the helium ionization is set mostly by photoionization and direct collisional ionization, counteracted by radiative recombination cascades. By introducing an additional recombination rate mimicking the recombination cascades, we construct a simplified three-level helium model atom consisting of only the ground states. This model atom is suitable for modeling nonequilibrium helium ionization in three-dimensional numerical models. We perform a brief investigation of the formation of the He I 10830 and He II 304 spectral lines. Both lines show nonequilibrium features that are not recovered with statistical equilibrium models, and caution should therefore be exercised when such models are used as a basis for interpretating observations.

Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit

2014-03-01

370

Helium Neon Laser  

NSDL National Science Digital Library

This resource, part of the Spectroscopy Lab Suite, illustrates the physics of a Helium-Neon Laser. Students can create energy levels for both the He and Ne atoms. The basic processes for light emission, including collisions and level transitions, are shown. The atomic energy levels and the pumping energy can be adjusted to achieve an output spectrum similar to the measured physical spectrum.

Zollman, Dean

371

Trap assisted creation of giant molecules and Rydberg-mediated coherent charge transfer in a Penning trap  

E-print Network

We study two ions confined in a Penning trap. We show that electronically highly excited states exist in which an electron is delocalized among the two ions forming a giant molecule of several micrometer size. At energies close to the top of the Coulomb barrier these molecular states can be regarded as superpositions of Rydberg states of individual ions. We illuminate the possibility to observe coherent charge transfer between the ions. Beyond a critical principal quantum number the electron can coherently tunnel through the Coulomb barrier to an adjacent doubly charged ion. The tunneling occurs on timescales on which the dynamics of the nuclei can be considered frozen and radiative decay can be neglected.

I. Lesanovsky; M. Mueller; P. Zoller

2008-09-18

372

The cryogenic helium cooling system for the Tokamak physics experiment  

SciTech Connect

The Tokamak Physics Experiment (TPX) will use supercritical helium to cool all the magnets and supply helium to the Vacuum cryopumping subsystem. The heat loads will come from the standard steady state conduction and thermal radiation sources and from the pulsed loads of the nuclear and eddy currents caused by the Central Solenoid Coils and the plasma positioning coils. The operations of the TPX will begin with pulses of up to 1000 seconds in duration every 75 minutes. The helium system utilizes a pulse load leveling scheme to buffer out the effects of the pulse load and maintain a constant cryogenic plant operation. The pulse load leveling scheme utilizes the thermal mass of liquid and gaseous helium stored in a remote dewar to absorb the pulses of the tokamak loads. The mass of the stored helium will buffer out the temperature pulses allowing 5 K helium to be delivered to the magnets throughout the length of the pulse. The temperature of the dewar will remain below 5 K with all the energy of the pulse absorbed. This paper will present the details of the heat load sources, of the pulse load leveling scheme operations, a partial helium schematic, dewar temperature as a function of time, the heat load sources as a function of time and the helium temperature as a function of length along the various components that will be cooled.

Felker, B.; Slack, D.S.; Wendland, C.R.

1995-09-29

373

Absolute high-resolution Se+ photoionization cross-section measurements with Rydberg-series analysis  

NASA Astrophysics Data System (ADS)

Absolute single photoionization cross-section measurements for Se+ ions were performed at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory using the photo-ion merged-beams technique. Measurements were made at a photon energy resolution of 5.5 meV from 17.75 to 21.85 eV spanning the 4s24p3 4S3/2o ground-state ionization threshold and the 2P3/2o,2P1/2o,2D5/2o, and2D3/2o metastable state thresholds. Extensive analysis of the complex resonant structure in this region identified numerous Rydberg series of resonances and obtained the Se2+ 4s24p23P2 and 4s24p21S0 state energies. In addition, particular attention was given to removing significant effects in the measurements due to a small percentage of higher-order undulator radiation.

Esteves, D. A.; Bilodeau, R. C.; Sterling, N. C.; Phaneuf, R. A.; Kilcoyne, A. L. D.; Red, E. C.; Aguilar, A.

2011-07-01

374

Rydberg assisted light shift imbalance induced blockade in an atomic ensemble  

NASA Astrophysics Data System (ADS)

Previously, we had proposed the technique of light shift imbalance induced blockade which leads to a condition where a collection of non-interacting atoms under laser excitation remains combined to a superposition of the ground and the first excited states, thus realizing a collective state quantum bit which in turn can be used to realize a quantum computer. In this paper, we show first that the light shift imbalance by itself is actually not enough to produce such a blockade, and explain the reason why the limitation of our previous analysis had reached this constraint. We then show that by introducing Rydberg interaction, it is possible to achieve such a blockade for a wide range of parameters. Analytic arguments used to establish these results are confirmed by numerical simulations. The fidelity of coupled quantum gates based on such collective state qubits is highly insensitive to the exact number of atoms in the ensemble. As such, this approach may prove to be viable for scalable quantum computing based on neutral atoms.

Tu, Yanfei; Kim, May E.; Shahriar, Selim M.

2015-03-01

375

Rydberg-Atom Quantum Simulation and Chern Number Characterization of a Topological Mott Insulator  

NASA Astrophysics Data System (ADS)

In this talk we consider a system of spinless fermions with nearest and next-to-nearest neighbor repulsive Hubbard interactions on a honeycomb lattice within the mean-field treatment, and propose and analyze a realistic scheme for analog quantum simulation of this model with cold atoms in a two-dimensional hexagonal optical lattice. Besides a semi-metallic and a charge-density-wave ordered phase, the system exhibits a quantum anomalous Hall phase, which is generated dynamically, i.e. purely as a result of the repulsive fermionic interactions and in the absence of any external gauge fields. We establish the topological nature of this dynamically created Mott insulating phase by the numerical calculation of a Chern number, and study the possibility of coexistence of this phase with the other phases characterized by local order parameters. Based on the knowledge of the mean-field phase diagram, we then discuss in detail how the interacting Hamiltonian can be engineered effective ly by state-of-the-art experimental techniques for laser-dressing of cold fermionic ground-state atoms with electronically excited Rydberg states that exhibit strong dipolar interactions.[4pt] [1] A. Dauphin, M. Mueller, and M. A. Martin-Delgado, arXiv:1207.6373. Submitted to PRA and accepted on Sep 26, 2012.

Dauphin, Alexandre; Mueller, Markus; Martin-Delgado, Miguel-Angel

2013-03-01

376

Rydberg-atom quantum simulation and Chern-number characterization of a topological Mott insulator  

NASA Astrophysics Data System (ADS)

In this work we consider a system of spinless fermions with nearest and next-to-nearest neighbor repulsive Hubbard interactions on a honeycomb lattice, and propose and analyze a realistic scheme for analog quantum simulation of this model with cold atoms in a two-dimensional hexagonal optical lattice. To this end, we first derive the zero-temperature phase diagram of the interacting model within a mean-field theory treatment. We show that besides a semimetallic and a charge-density-wave ordered phase, the system exhibits a quantum anomalous Hall phase, which is generated dynamically, i.e., purely as a result of the repulsive fermionic interactions and in the absence of any external gauge fields. We establish the topological nature of this dynamically created Mott-insulating phase by the numerical calculation of a Chern number, and we study the possibility of coexistence of this phase with any of the other phases characterized by local order parameters. Based on the knowledge of the mean-field phase diagram, we then discuss in detail how the interacting Hamiltonian can be engineered effectively by state-of-the-art experimental techniques for laser dressing of cold fermionic ground-state atoms with electronically excited Rydberg states that exhibit strong dipolar interactions.

Dauphin, A.; Müller, M.; Martin-Delgado, M. A.

2012-11-01

377

Quantized Redshifts of Galaxies: Stimulated Raman Scattering in Cold Intergalactic Rydberg Matter  

Microsoft Academic Search

That the redshifts for galaxies in the local supercluster are quantizedwas recently confirmedby Guthrie and Napier(A&Amp;Amp;A310 (1996) 353). These redshifts are here proposed to be due to stimulatedStokes Raman processes in intergalactic matter in the form of Rydberg Matter (RM). Rydberg Matteris an electronically excited material, as demonstrated by its use as laser medium in a thermally excitedultra-broadband tunable IR

Leif Holmlid

2004-01-01

378

Rydberg-electron decoherence in experimentally obtained recurrence spectra  

SciTech Connect

Using scaled-energy spectroscopy techniques (recurrence spectroscopy) we investigate the influence of collisionally induced decoherence on semiclassical orbits in the Stark-Rydberg system. This experimental investigation represents the first application of recurrence spectroscopy to an atomic system perturbed by collisions with external gas partners. We present high-resolution recurrence spectra of potassium, revealing core-scattered combination orbits, and with minor modifications to the data acquisition process, recurrence spectra were also obtained with the system perturbed by 10 torr of krypton gas. A simple decoherence model is applied to semiclassical theory to explain the loss of recurrence strength at high actions. In several cases we also observe the loss of coherent interference between orbits. The loss of coherent destructive interference causes an increase in the recurrence strength of several core-scattered combination orbits.

Keeler, M. L.; Setzer, W.; Martin, W. W. [Physics Department, University of Minnesota-Morris, Morris, Minnesota 56267 (United States)

2010-11-15

379

Quantum simulation of energy transport with embedded Rydberg aggregates  

E-print Network

We show that an array of ultracold Rydberg atoms embedded in a laser driven background gas can serve as an aggregate for simulating exciton dynamics and energy transport with a controlled environment. Spatial disorder and decoherence introduced by the interaction with the background gas atoms can be controlled by the laser parameters. This allows for an almost ideal realization of a Haken-Reineker-Strobl type model for energy transport. Physics can be monitored using the same mechanism that provides control over the environment. The degree of decoherence is traced back to information gained on the excitation location through the monitoring, turning the setup into an experimentally accessible model system for studying the effects of quantum measurements on the dynamics of a many-body quantum system.

Schönleber, D W; Genkin, M; Whitlock, S; Wüster, S

2015-01-01

380

Mantle helium and carbon isotopes in Separation Creek Geothermal Springs, Three Sisters area, Central Oregon: Evidence for renewed volcanic activity or a long term steady state system?  

SciTech Connect

Cold bubbling springs in the Separation Creek area, the locus of current uplift at South Sister volcano show strong mantle signatures in helium and carbon isotopes and CO{sub 2}/{sup 3}He. This suggests the presence of fresh basaltic magma in the volcanic plumbing system. Currently there is no evidence to link this system directly to the uplift, which started in 1998. To the contrary, all geochemical evidence suggests that there is a long-lived geothermal system in the Separation Creek area, which has not significantly changed since the early 1990s. There was no archived helium and carbon data, so a definite conclusion regarding the strong mantle signature observed in these tracers cannot yet be drawn. There is a distinct discrepancy between the yearly magma supply required to explain the current uplift (0.006 km{sup 3}/yr) and that required to explain the discharge of CO{sub 2} from the system (0.0005 km{sup 3}/yr). This discrepancy may imply that the chemical signal associated with the increase in magma supply has not reached the surface yet. With respect to this the small changes observed at upper Mesa Creek require further attention, due to the recent volcanic vent in that area it may be the location were the chemical signal related to the uplift can most quickly reach the surface. Occurrence of such strong mantle signals in cold/diffuse geothermal systems suggests that these systems should not be ignored during volcano monitoring or geothermal evaluation studies. Although the surface-expression of these springs in terms of heat is minimal, the chemistry carries important information concerning the size and nature of the underlying high-temperature system and any changes taking place in it.

van Soest, M.C.; Kennedy, B.M.; Evans, W.C.; Mariner, R.H.

2002-04-30

381

Advanced fuels modeling: Evaluating the steady-state performance of carbide fuel in helium-cooled reactors using FRAPCON 3.4  

NASA Astrophysics Data System (ADS)

Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism. One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are an increased corrosion resistance, high mechanical strength, and irradiation stability. However, with increased temperatures, SiC exhibits an extremely brittle nature. The brittle behavior of SiC is not fully understood and thus it is unknown how SiC would respond to the added stress of a swelling UC fuel. To better understand the interaction between these advanced materials, each has been implemented into FRAPCON, the preferred fuel performance code of the Nuclear Regulatory Commission (NRC); additionally, the material properties for a helium coolant have been incorporated. The implementation of UC within FRAPCON required the development of material models that described not only the thermophysical properties of UC, such as thermal conductivity and thermal expansion, but also models for the swelling, densification, and fission gas release associated with the fuel's irradiation behavior. This research is intended to supplement ongoing analysis of the performance and behavior of uranium carbide and silicon carbide in a helium-cooled reactor.

Hallman, Luther, Jr.

382

Explicitly correlated Gaussian calculations of the {sup 2}P{sup o} Rydberg spectrum of the lithium atom  

SciTech Connect

Accurate quantum-mechanical nonrelativistic variational calculations are performed for the nine lowest members of the {sup 2}P{sup o} Rydberg series (1s{sup 2}np{sup 1}, n= 2, ..., 10) of the lithium atom. The effect of the finite nuclear mass is included in the calculations allowing for determining the isotopic shifts of the energy levels. The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. The exponential parameters of the Gaussians are variationally optimized with the aid of the analytical energy gradient determined with respect to those parameters. The calculated state energies are compared with the available experimental data.

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

2012-04-07

383

ANGULAR MOMENTUM CHANGING TRANSITIONS IN PROTON-RYDBERG HYDROGEN ATOM COLLISIONS  

SciTech Connect

Collisions between electrically charged particles and neutral atoms are central for understanding the dynamics of neutral gases and plasmas in a variety of physical situations of terrestrial and astronomical interest. Specifically, redistribution of angular momentum states within the degenerate shell of highly excited Rydberg atoms occurs efficiently in distant collisions with ions. This process is crucial in establishing the validity of the local thermal equilibrium assumption and may also play a role in determining a precise ionization fraction in primordial recombination. We provide an accurate expression for the non-perturbative rate coefficient of collisions between protons and H(nl) ending in a final state H(nl'), with n being the principal quantum number and l, l' the initial and final angular momentum quantum numbers, respectively. The validity of this result is confirmed by results of classical trajectory Monte Carlo simulations. Previous results, obtained by Pengelly and Seaton only for dipole-allowed transitions l {yields} l {+-} 1, overestimate the l-changing collisional rate coefficients approximately by a factor of six, and the physical origin of this overestimation is discussed.

Vrinceanu, D. [Department of Physics, Texas Southern University, Houston, TX 77004 (United States); Onofrio, R. [Dipartimento di Fisica e Astronomia 'Galileo Galilei', Universita di Padova, 35131 Padova (Italy); Sadeghpour, H. R., E-mail: daniel.vrinceanu@gmail.com, E-mail: onofrior@gmail.com, E-mail: hrsadeghpour@gmail.com [ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2012-03-01

384

The Zel'dovich effect and evolution of atomic Rydberg spectra along the Periodic Table  

E-print Network

In 1959 Ya. B. Zel'dovich predicted that the bound-state spectrum of the non-relativistic Coulomb problem distorted at small distances by a short-range potential undergoes a peculiar reconstruction whenever this potential alone supports a low-energy scattering resonance. However documented experimental evidence of this effect has been lacking. Previous theoretical studies of this phenomenon were confined to the regime where the range of the short-ranged potential is much smaller than Bohr's radius of the Coulomb field. We go beyond this limitation by restricting ourselves to highly-excited s states. This allows us to demonstrate that along the Periodic Table of elements the Zel'dovich effect manifests itself as systematic periodic variation of the Rydberg spectra with a period proportional to the cubic root of the atomic number. This dependence, which is supported by analysis of experimental and numerical data, has its origin in the binding properties of the ionic core of the atom.

Eugene B. Kolomeisky; Michael Timmins

2005-04-21

385

Applications of Groundwater Helium  

USGS Publications Warehouse

Helium abundance and isotope variations have widespread application in groundwater-related studies. This stems from the inert nature of this noble gas and the fact that its two isotopes ? helium-3 and helium-4 ? have distinct origins and vary widely in different terrestrial reservoirs. These attributes allow He concentrations and 3He/4He isotope ratios to be used to recognize and quantify the influence of a number of potential contributors to the total He budget of a groundwater sample. These are atmospheric components, such as air-equilibrated and air-entrained He, as well as terrigenic components, including in situ (aquifer) He, deep crustal and/or mantle He and tritiogenic 3He. Each of these components can be exploited to reveal information on a number of topics, from groundwater chronology, through degassing of the Earth?s crust to the role of faults in the transfer of mantle-derived volatiles to the surface. In this review, we present a guide to how groundwater He is collected from aquifer systems and quantitatively measured in the laboratory. We then illustrate the approach of resolving the measured He characteristics into its component structures using assumptions of endmember compositions. This is followed by a discussion of the application of groundwater He to the types of topics mentioned above using case studies from aquifers in California and Australia. Finally, we present possible future research directions involving dissolved He in groundwater.

Kulongoski, Justin T.; Hilton, David R.

2011-01-01

386

Precision spectroscopy of Kaonic helium-3 and helium-4 3d{yields}2p X-rays  

SciTech Connect

Recently, the shift of the kaonic helium-4 2p state was precisely determined by the E570 and SIDDHARTA experiments. Prior to the experiment by E570, the average of three earlier experimental results showed -43{+-}8 eV,while most of the theoretical calculations give {approx}0 eV. This five-sigma discrepancy between theory and experiment was known as the 'kaonic helium puzzle'. A recent theoretical model showed a possible resonance-like shift of maximum 10 eV for a certain value of a deep antikaon-nucleon interaction potential, which is different in helium 3 and helium 4.The E570 experiment determined the shift of the kaonic helium-4 2p state as +2{+-}2 (stat){+-}2 (sys) eV in 2007. The SIDDHARTA experiment determined the shift as 0{+-}6(stat){+-}2(sys) eV in 2009. The results of these experiments resolved the long-standing puzzle. A new experiment of the kaonic helium-3 X-ray measurement is being prepared by the J-PARC E17 collaborators, and the kaonic helium-3 X-ray data taken very recently by the SIDDHARTA experiment are on the way to be analyzed. The results of the E570, E17 and SIDDHARTA experiments examine the strong interaction for light nuclei with different isospin, and test furthermore recent theoretical predictions.

Ishiwatari, T.; Cargnelli, M.; Marton, J.; Widmann, E.; Wuenschek, B.; Zmeskal, J. [Stefan-Meyer-Institut fuer subatomare Physik, Vienna (Austria); Bazzi, M.; Corradi, G.; Curceanu, C.; D'Uffizi, A.; Guaraldo, C.; Levi Sandri, P.; Lucherini, V.; Okada, S.; Pietreanu, D.; Rizzo, A.; Romero Vidal, A.; Scordo, A.; Vazquez Doce, O. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); Bhang, H. [Department of Physics, Seoul National University, Seoul (Korea, Republic of)

2010-08-05

387

Signature of helium segregation in hydrogen-helium mixtures  

NASA Astrophysics Data System (ADS)

The conductivity and reflectivity of mixtures of hydrogen and helium under high pressure are calculated using first-principles molecular dynamics and the Kubo-Greenwood formula. Hydrogen-helium mixtures have been predicted to undergo demixing below a certain critical temperature. The impact of phase segregation of helium on the optical properties of the mixtures is explored. The change in reflectivity upon demixing is found to vary with frequency with larger variation at higher frequency.

Hamel, Sebastien; Morales, Miguel A.; Schwegler, Eric

2011-10-01

388

Oxidation characteristics of the electron beam surface-treated Alloy 617 in high temperature helium environments  

NASA Astrophysics Data System (ADS)

The oxidation characteristics of the electron beam surface-treated Alloy 617, which has an Al-rich surface layer, were evaluated in high temperature helium environments. Isothermal oxidation tests were performed in helium (99.999% purity) and VHTR-helium (helium of prototypical VHTR chemistry containing impurities like CO, CO2, CH4, and H2) environments at 900 °C for up to 1000 h. The surface-treated Alloy 617 showed an initial transient oxidation stage followed by the steady-state oxidation in all test environments. In addition, the steady-state oxidation kinetics of the surface-treated Alloy 617 was 2-order of magnitude lower than that of the as-received Alloy 617 in both helium environments as well as in air. The improvement in oxidation resistance was primarily due to the formation of the protective Al2O3 layer on the surface. The weight gain was larger in the order of air, helium, and VHTR-helium, while the parabolic rate constants (kp) at steady-state were similar for all test environments. In both helium environments, the oxide structure consisted of the outer transition Al2O3 with a small amount of Cr2O3 and inner columnar structured Al2O3 without an internal oxide. In the VHTR-helium environment, where the impurities were added to helium, the initial transient oxidation increased but the steady state kinetics was not affected.

Lee, Ho Jung; Sah, Injin; Kim, Donghoon; Kim, Hyunmyung; Jang, Changheui

2015-01-01

389

Nuclear condensate and helium white dwarfs  

E-print Network

We consider a high density region of the helium phase diagram, where the nuclei form a Bose-Einstein condensate rather than a classical plasma or a crystal. Helium in this phase may be present in helium-core white dwarfs. We show that in this regime there is a new gapless quasiparticle not previously noticed, arising when the constraints imposed by gauge symmetry are taken into account. The contribution of this quasiparticle to the specific heat of a white dwarf core turns out to be comparable in a range of temperatures to the contribution from the particle-hole excitations of the degenerate electrons. The specific heat in the condensed phase is two orders of magnitude smaller than in the uncondensed plasma phase, which is the ground state at higher temperatures, and four orders of magnitude smaller than the specific heat that an ion lattice would provide, if formed. Since the specific heat of the core is an important input for setting the rate of cooling of a white dwarf star, it may turn out that such a change in the thermal properties of the cores of helium white dwarfs has observable implications.

Paulo F. Bedaque; Evan Berkowitz; Aleksey Cherman

2011-11-05

390

How does helium get into buckminsterfullerene?  

Microsoft Academic Search

Reaction mechanisms for helium incorporation into Cââ have been examined by semiempirical (MNDO), ab initio (HF\\/3-21G), and density functional (BLYP\\/3-21G, BP86\\/3-21G) calculations. Effective activation barriers for the penetration through an intact cage and for the insertion through the two possible one-bond windows and six different two-bond windows are reported both in the lowest singlet triplet state. The computed barriers are

Serguei Patchkovskii; Walter Thiel

1996-01-01

391

Helium jet dispersion to atmosphere  

NASA Technical Reports Server (NTRS)

On the event of loss of vacuum guard of superinsulated helium dewar, high rate of heat transfer into the tank occurs. The rapid boiling of liquid helium causes the burst disk to rupture at four atmospheres and consequently the helium passes to the atmosphere through vent lines. The gaseous helium forms a vertical buoyant jet as it exits the vent line into a stagnant environment. Characterization of the gaseous jet is achieved by detailed analysis of the axial and radial dependence of the flow parameters.

Khan, Hasna J.

1986-01-01

392

Helium cryopumping for fusion applications  

SciTech Connect

Large quantities of helium and hydrogen isotopes will be exhausted continuously from fusion power reactors. This paper summarizes two development programs undertaken to address vacuum pumping for this application: (i) A continuous duty cryopump for pumping helium and/or hydrogen species using charcoal sorbent and (ii) a cryopump configuration with an alternative shielding arrangement using charcoal sorbent or argon spray. A test program evaluated automatic pumping of helium, helium pumping by charcoal cryosorption and with argon spray, and cryosorption of helium/hydrogen mixtures. The continuous duty cryopump pumped helium continuously and conveniently. Helium pumping speed was 7.7 l/s/cm/sup 2/ of charcoal, compared to 5.8 l/s/cm/sup 2/ for the alternative pump. Helium speed using argon spray was 18% of that obtained by charcoal cryosorption in the same (W-panel) pump. During continuous duty cryopump mixture tests with helium and hydrogen copumped on charcoal, gas was released sporadically. Testing was insufficient to explain this unacceptable event.

Sedgley, D.W.; Batzer, T.H.; Call, W.R.

1988-05-01

393

Spectroscopy of barium atoms in liquid and solid helium matrices  

SciTech Connect

We present an exhaustive overview of optical absorption and laser-induced fluorescence lines of Ba atoms in liquid and solid helium matrices in visible and near-infrared spectral ranges. Due to the increased density of isolated atoms, we have found a large number of spectral lines that were not observed in condensed helium matrices before. We have also measured the lifetimes of metastable states. The lowest {sup 3}D{sub 1} metastable state has lifetime of 2.6 s and can be used as an intermediate state in two-step excitations of high-lying states. Various matrix-induced radiationless population transfer channels have been identified.

Lebedev, V.; Moroshkin, P.; Weis, A. [Departement de Physique, Universite de Fribourg, Chemin du Musee 3, CH-1700 Fribourg (Switzerland)

2011-08-15

394

Free-energy model for fluid helium at high density  

E-print Network

We present a semi-analytical free-energy model aimed at characterizing the thermodynamic properties of dense fluid helium, from the low-density atomic phase to the high-density fully ionized regime. The model is based on a free-energy minimization method and includes various different contributions representative of the correlations between atomic and ionic species and electrons. This model allows the computation of the thermodynamic properties of dense helium over an extended range of density and temperature and leads to the computation of the phase diagram of dense fluid helium, with its various temperature and pressure ionization contours. One of the predictions of the model is that pressure ionization occurs abruptly at $\\rho \\simgr 10$ g cm$^{-3}$, {\\it i.e.} $P\\simgr 20$ Mbar, from atomic helium He to fully ionized helium He$^{2+}$, or at least to a strongly ionized state, without He$^{+}$ stage, except at high enough temperature for temperature ionization to become dominant. These predictions and this phase diagram provide a guide for future dynamical experiments or numerical first-principle calculations aimed at studying the properties of helium at very high density, in particular its metallization. Indeed, the characterization of the helium phase diagram bears important consequences for the thermodynamic, magnetic and transport properties of cool and dense astrophysical objects, among which the solar and the numerous recently discovered extrasolar giant planets.

Christophe Winisdoerffer; Gilles Chabrier

2004-12-06

395

Radiative lifetimes along even-parity J = 1, 2 Rydberg series of neutral tin  

NASA Astrophysics Data System (ADS)

Using the time-resolved laser-induced fluorescence (LIF) technique in a tin atomic beam, 40 natural radiative lifetimes have been measured for the even-parity J = 1~5 pnp (n = 10-13, 15-19) and J = 2~5 pnp (n = 10-13, 15-19, 27, 31, 32), 5 pnf (n = 4, 5, 9-19, 22, 23) levels along the Rydberg series and for all the 5p8p perturbing levels of neutral tin with energies in the range 52263.8 to 59099.9 cm-1. A two-step laser excitation scheme was used in the experiment. A multiconfigurational relativistic Hartree-Fock (HFR) calculation taking core-polarization effects into account has also been performed for the even-parity states for testing the ability of this approach to correctly predict the radiative properties of tin atom. Through an analysis of the energy levels structure by the multichannel quantum defect theory (MQDT), the channel admixture coefficients have been obtained and used to fit the theoretical lifetimes to the experimental ones in order to predict new values for the levels not measured. A generally good overall agreement between experimental and theoretical MQDT and HFR lifetimes has been achieved except for a few levels.

Zhang, W.; You, S.; Sun, C.; Zhang, Y.; Xu, J.; Ma, Z.; Feng, Y.; Liu, H.; Quinet, P.; Biémont, É.; Dai, Z.

2009-10-01

396

Threshold effects in strong-field ionization: Energy shifts and Rydberg structures  

NASA Astrophysics Data System (ADS)

The behavior of strong-field ionization rates of neutral atoms in the vicinity of multiphoton ionization thresholds is analyzed using formal collision theory. Our approach, which accounts nonperturbatively for effects of an intense laser field, shows that the ionization rates have a nearly constant behavior below and above each multiphoton threshold and that between such thresholds there are an apparently finite number of rapid oscillations due to resonances with laser-field-modified Rydberg states. This pattern is typical for any atomic target, as we illustrate specifically for hydrogen and neon atoms. The flat behavior of the ionization yield near multiphoton thresholds gives the appearance of an energy shift of the ionization thresholds, which have been postulated in a number of recent studies concerning diverse aspects of above-threshold ionization and high-harmonic generation of atoms. The flat behaviors of the rates near threshold exhibit only a rather weak dependence on the laser-field intensity. Other aspects of the near-threshold behavior of ionization rates and their dependence on the laser-field parameters are also discussed.

Krajewska, K.; Fabrikant, I. I.; Starace, A. F.

2012-11-01

397

Resonant collisions of Na Rydberg atoms in electric and magnetic fields  

SciTech Connect

We have observed 10-MHz-wide energy-transfer resonances between colliding Na Rydberg atoms. The narrow linewidth allows us to apply a modest 5--40-G static magnetic field in addition to a static tuning electric field and resolve new resonances arising from magnetic-field-induced splitting of the Stark energy levels. When [ital B] is parallel to [ital E], the nine resolved resonances observed with only an [ital E] field are further split into 144 possible resonances. However, only the 21 resonances corresponding to collisions in which the spins are unchanged are observable. When [ital B] is perpendicular to [ital E], the spectrum of collisional resonances is similar to that of the vertical field case, except that the final spin states cannot be determined. With both parallel and perpendicular fields present, linear and quadratic terms of the [ital B] field interaction create more complicated spectra than with either case alone. The experimental spectra agree quantitatively with the spectra calculated using a simple Zeeman model of the energy levels.

Renn, M.J.; Sun, Q.S.; Gallagher, T.F. (Department of Physics, University of Virginia, Charlottesville, Virginia 22901 (United States))

1994-11-01

398

Commissioning a Helium II Test Facility at SLAC  

SciTech Connect

Liquid helium is the only fluid that exhibits the unique properties characteristic of a superfluid when cooled to temperatures near absolute zero. This superfluid helium state is commonly referred to as He II. Among the many odd properties are a vanishingly small viscosity and a high effective thermal conductivity. A He II test facility will provide researchers in the Experimental Facilities Department at SLAC with the opportunity to do research in the superfluid range with relative ease. The nature of this project is to test the functionality of the existing helium components in the cryogenics lab and recommend improvements. The basic experimental setup consisted of a helium dewar, a vacuum pump system, and a network of sensors. After adding liquid helium into the dewar and turning on the vacuum pump, we observed that the pump was able to reduce the pressure down comfortably into the superfluid state. Furthermore, by adding heat to the fluid in set increments we learned what amount of heat could be added while still keeping the helium in the superfluid range. Our final test was to see if we had the ability to change the pressure via the MKS exhaust valve controller. The controller failed miserably and was found to be inadequate for the type of experiments to be done. Among the other recommended improvements were: adding isolation valves to the vacuum pump line, erecting a supply line for clean helium gas, incorporating a relief valve in the helium recovery line, and documenting the existing vent and vacuum lines. Once these improvements are made, the He II test facility should be up and running, allowing researchers to dive as deep as they please into the superfluid state.

Katz, A.

2004-09-03

399

Heavy Rydberg Photo-dissociation Cross-section Calculations and Experimental Progress Towards Cold Collisions in Lithium  

E-print Network

This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I: One outgoing channel of interest from cold collisions is the production of ion pairs. We describe an effective method for calculating bound-to-continuum cross-sections for charged binary systems by examining transitions to states above the binding energy that become bound when the system is placed within an infinite spherical well. This approach is verified for ionization of a hydrogen atom, and is then applied to the heavy Rydberg system Li+...I-. Part II: A wavemeter previously built in the lab is redesigned for increased reliability and ease of use by replacing the optical hardware with a rocker system, which can be aligned in mere minutes rather than half a day as was previously the case. The new wavemeter has been tested through saturated absorption spectroscopy of lithium.

Ugray, Lisa Madeleine

2013-01-01

400

Heavy rydberg photo-dissociation cross-section calculations and experimental progress towards cold collisions in lithium  

NASA Astrophysics Data System (ADS)

This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I One outgoing channel of interest from cold collisions is the production of ion pairs. We describe an effective method for calculating bound-to-continuum cross-sections for charged binary systems by examining transitions to states above the binding energy that become bound when the system is placed within an infinite spherical well. This approach is verified for ionization of a hydrogen atom, and is then applied to the heavy Rydberg system Li+...I-. Part II A wavemeter previously built in the lab is redesigned for increased reliability and ease of use by replacing the optical hardware with a rocker system, which can be aligned in mere minutes rather than half a day as was previously the case. The new wavemeter has been tested through saturated absorption spectroscopy of lithium.

Ugray, Lisa Madeleine

401

Rydberg levels and ionization potential of francium measured by laser-resonance ionization in a hot cavity  

SciTech Connect

A highly sensitive method of detecting atoms in samples has been used for spectral investigations of the rare radioactive element Fr. The method is based on laser-resonance photoionization of Fr atoms in a hot quasi-enclosed cavity. The investigations have been carried out with samples in which short-lived radioactive /sup 221/Fr atoms formed at a rate of approximately 10/sup 3/ atoms/sec. The data obtained, to our knowledge for the first time, on the energies of the high-lying Rydberg levels of the /sup 2/S/sub 1/2/ and /sup 2/D series have made it possible to determine the electron binding energy of the 7p /sup 2/P/sub 3/2/ state and to establish the ionization potential of Fr accurately.

Andreev, S.V.; Mishin, V.I.; Letokhov, V.S.

1988-10-01

402

Ionization and dissociation equilibrium in strongly-magnetized helium atmosphere  

E-print Network

Recent observations and theoretical investigations of neutron stars indicate that their atmospheres consist not of hydrogen or iron but possibly other elements such as helium. We calculate the ionization and dissociation equilibrium of helium in the conditions found in the atmospheres of magnetized neutron stars. For the first time this investigation includes the internal degrees of freedom of the helium molecule. We found that at the temperatures and densities of neutron star atmospheres the rotovibrational excitations of helium molecules are populated. Including these excitations increases the expected abundance of molecules by up to two orders of magnitude relative to calculations that ignore the internal states of the molecule; therefore, if the atmospheres of neutron stars indeed consist of helium, helium molecules and possibly polymers will make the bulk of the atmosphere and leave signatures on the observed spectra from neutron stars. We applied our calculation to nearby radio-quiet neutron stars with B_{dipole}~10^{13}-10^{14} G. If helium comprises their atmospheres, our study indicates that isolated neutron stars with T_{BB}~10^6 K such as RXJ0720.4-3125 and RXJ1605.3+3249 will have He^+ ions predominantly, while isolated neutron stars with lower temperature (T_{BB}~5x10^5 K) such as RXJ1856.5-3754 and RXJ0420.0-5022 will have some fraction of helium molecules. If helium molecules are abundant, their spectroscopic signatures may be detected in the optical, UV and X-ray band. (Abridged)

Kaya Mori; Jeremy S. Heyl

2007-02-23

403

PHYSICAL REVIEW A 81, 063411 (2010) Spatially resolved excitation of Rydberg atoms and surface effects on an atom chip  

E-print Network

PHYSICAL REVIEW A 81, 063411 (2010) Spatially resolved excitation of Rydberg atoms and surface effects on an atom chip Atreju Tauschinsky,* Rutger M. T. Thijssen, S. Whitlock, H. B. van Linden van den spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced

Amsterdam, Universiteit van

404

1426 J. Opt. Soc. Am. B/Vol. 4, No. 9/September 1987 Bell's inequalities for Rydberg atoms  

E-print Network

1426 J. Opt. Soc. Am. B/Vol. 4, No. 9/September 1987 Bell's inequalities for Rydberg atoms Brian J February 13, 1987; accepted May 7, 1987 The analogy between two-level atoms and spins is used to show that Rydberg atoms provide a new medium through whichBell's inequalities may be studied. The low

Stroud Jr., Carlos R.

405

Fine structure of the H2 5g4f inter-Rydberg transition revealed by difference frequency laser spectroscopy  

E-print Network

Fine structure of the H2 5g­4f inter-Rydberg transition revealed by difference frequency laser of the 5g­4f inter-Rydberg band of H2 has been recorded with a difference frequency laser system composed of absorption lines, some transitions from high vibrational levels of the 5g triplet manifold to 4

Oka, Takeshi

406

Quantized Redshifts of Galaxies: Stimulated Raman Scattering in Cold Intergalactic Rydberg Matter  

NASA Astrophysics Data System (ADS)

That the redshifts for galaxies in the local supercluster are quantizedwas recently confirmedby Guthrie and Napier(A&A310 (1996) 353). These redshifts are here proposed to be due to stimulatedStokes Raman processes in intergalactic matter in the form of Rydberg Matter (RM). Rydberg Matteris an electronically excited material, as demonstrated by its use as laser medium in a thermally excitedultra-broadband tunable IR laser (Chem. Phys. Lett. 376 (2003) 812). Its existence in interstellar andintergalactic space is demonstrated by several observational results, notably the unidentified IR bands,that agree well with the emission from Rydberg Matter. A stimulated Raman process will allow theH I 21 cm radiation to proceed without deflection, in agreement with observation. Such redshiftswill be additive during the passage through space. The process in Rydberg Matter here proposed togive rise to the Stokes Raman process is excitation of electronic translational modes in the planarclusters forming the matter. The specific cluster sizes found in laboratory experiments give rise toa few differently sized redshift quanta, which is in good agreement with the observed quanta. Anexcitation level (principal quantum number) of Rydberg Matter in intergalactic space between 175and 200 gives the correct size of the redshift quanta.

Holmlid, Leif

2004-05-01

407

Helium dilution refrigeration system  

DOEpatents

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

Roach, P.R.; Gray, K.E.

1988-09-13

408

Phase separation in hydrogen–helium mixtures at Mbar pressures  

PubMed Central

The properties of hydrogen–helium mixtures at Mbar pressures and intermediate temperatures (4000 to 10000 K) are calculated with first-principles molecular dynamics simulations. We determine the equation of state as a function of density, temperature, and composition and, using thermodynamic integration, we estimate the Gibbs free energy of mixing, thereby determining the temperature, at a given pressure, when helium becomes insoluble in dense metallic hydrogen. These results are directly relevant to models of the interior structure and evolution of Jovian planets. We find that the temperatures for the demixing of helium and hydrogen are sufficiently high to cross the planetary adiabat of Saturn at pressures ?5 Mbar; helium is partially miscible throughout a significant portion of the interior of Saturn, and to a lesser extent in Jupiter. PMID:19171896

Morales, Miguel A.; Schwegler, Eric; Ceperley, David; Pierleoni, Carlo; Hamel, Sebastien; Caspersen, Kyle

2009-01-01

409

Interstellar helium in the heliosphere  

NASA Astrophysics Data System (ADS)

Several years of neutral measurements by NASA/IBEX-Lo have yielded detailed observations of direct interstellar neutral helium (primary particles). Prior to IBEX, interstellar helium had been observed through UV backscattering, pickup ions, and directly by Ulysses-GAS. The IBEX measurements now also provide strong indications for the presence of secondary neutral helium that is thought to originate in the outer heliosheath from charge exchange. In order to model both primary and secondary particle populations and characterize them throughout the heliosphere, a detailed calculation method based on Keplerian orbits is used, and some sample results are presented. The helium velocity distribution functions throughout the heliosphere are characterized. In the inner heliosphere they exhibit an intricate structure, in particular downwind of the Sun where the helium focusing cone resides as well.

Müller, Hans-Reinhard; Bzowski, Maciej; Möbius, Eberhard; Zank, Gary P.

2013-06-01

410

Implementation of an experimentally feasible controlled-phase gate on two blockaded Rydberg atoms  

NASA Astrophysics Data System (ADS)

We investigate the implementation of a controlled-Z gate on a pair of Rydberg atoms in spatially separated dipole traps where the joint excitation of both atoms into the Rydberg level is strongly suppressed (the Rydberg blockade). We follow the adiabatic gate scheme of Jaksch et al. [D. Jaksch, J. I. Cirac, P. Zoller, S. L. Rolston, R. Côté, and M. D. Lukin, Phys. Rev. Lett. 85, 2208 (2000), 10.1103/PhysRevLett.85.2208], where the pair of atoms is coherently excited using lasers, and apply it to the experimental setup outlined by Gaëtan et al. [A. Gaëtan, Y. Miroshnychenko, T. Wilk, A. Chotia, M. Viteau, D. Comparat, P. Pillet, A. Browaeys, and P. Grangier, Nat. Phys. 5, 115 (2009), 10.1038/nphys1183]. We apply optimization to the experimental parameters to improve gate fidelity and consider the impact of several experimental constraints on the gate success.

Müller, Matthias M.; Murphy, Michael; Montangero, Simone; Calarco, Tommaso; Grangier, Philippe; Browaeys, Antoine

2014-03-01

411

Probing excited states of NO involved in multistate interactions using the optical-optical double resonance-multiphoton ionization technique  

SciTech Connect

Many new transitions from the (3ssigma) A/sup 2/..sigma../sup +/ state to higher Rydberg and valence states in /sup 14/N/sup 16/O have been observed by the technique of optical-optical double resonance-multiphoton ionization. Upper states include members from the np, nd, nf Rydberg states (n = 3 to 6) and several vibrational levels of the B/sup 2/PI and L/sup 2/PI valence states. The spectral simplification aspect of the double resonance technique allows for the observation of these spectra without appreciable band overlap. Analysis of our data leads to the identification of several previously unobserved mixed Rydberg-valence vibrational levels. Discussions of the Rydberg-valence interactions in the 68,600-71,200-cm/sup -1/ energy region of /sup 14/N/sup 16/O are presented in light of these results. 31 references, 12 figures, 15 tables.

Cheung, W.Y.; Chupka, W.A.; Colson, S.D.; Gauyacq, D.; Avouris, P.; Wynne, J.J.

1986-03-13

412

Theoretical investigation of intersystem crossing between the ã¹A? and X³B? states of CH? induced by collisions with helium.  

PubMed

Collisional energy transfer between the ground (X³B?) and first excited (ã¹A?) states of CH2 is facilitated by strong mixing of the rare pairs of accidentally degenerate rotational levels in the ground vibrational manifold of the [Formula: see text] state and the (020) and (030) excited bending vibrational manifolds of the X state. The simplest model for this process involves coherent mixing of the scattering T-matrix elements associated with collisional transitions within the unmixed ã and X states. From previous calculations in our group, we have determined cross sections and room-temperature rate constants for intersystem crossing of CH2 by collision with He. These are used in simulations of the time dependence of the energy flow, both within and between the X and ã vibronic manifolds. Relaxation proceeds through three steps: (a) rapid equilibration of the two mixed-pair levels, (b) fast relaxation within the ã state, and (c) slower relaxation among the levels of the X state. Collisional transfer between the fine-structure levels of the triplet (X) state is very slow. PMID:25134576

Ma, Lifang; Alexander, Millard H; Dagdigian, Paul J

2014-08-14

413

Survival of Rydberg atoms in intense laser fields and the role of nondipole effects  

NASA Astrophysics Data System (ADS)

We consider the interaction of Rydberg atoms with strong infrared laser pulses using an approach based on the Magnus expansion of the time evolution operator. First-order corrections beyond the electric dipole approximation are also included in the theory. We illustrate the dynamics of the interaction at the parameters of the experiment [Eichmann et al., Phys. Rev. Lett. 110, 203002 (2013), 10.1103/PhysRevLett.110.203002]. It emerges that the depletion of Rydberg atoms in this regime comes predominantly from the nondipole effects.

Klaiber, Michael; Dimitrovski, Darko

2015-02-01

414

Coherent Excitation Transfer in a Spin Chain of Three Rydberg Atoms  

NASA Astrophysics Data System (ADS)

We study coherent excitation hopping in a spin chain realized using highly excited individually addressable Rydberg atoms. The dynamics are fully described in terms of an X Y spin Hamiltonian with a long range resonant dipole-dipole coupling that scales as the inverse third power of the lattice spacing, C3/R3 . The experimental data demonstrate the importance of next neighbor interactions which are manifest as revivals in the excitation dynamics. The results suggest that arrays of Rydberg atoms are ideally suited to large scale, high-fidelity quantum simulation of spin dynamics.

Barredo, Daniel; Labuhn, Henning; Ravets, Sylvain; Lahaye, Thierry; Browaeys, Antoine; Adams, Charles S.

2015-03-01

415

Tables of thermodynamic properties of helium magnet coolant  

SciTech Connect

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10{sup 8} Pa'', Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres'', Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

416

Tables of thermodynamic properties of helium magnet coolant. Revision A  

SciTech Connect

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: ``Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10{sup 8} Pa``, Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: ``Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres``, Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

417

Tables of thermodynamic properties of helium magnet coolant, revision A  

NASA Astrophysics Data System (ADS)

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: 'Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10(exp 8) Pa', Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923-1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: 'Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres', Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it.

McAshan, M.

1992-07-01

418

Three-body recombination in cold helium-helium-alkali-metal-atom collisions  

SciTech Connect

Three-body recombination in helium-helium-alkali-metal collisions at cold temperatures is studied using the adiabatic hyperspherical representation. The rates for the three-body recombination processes {sup 4}He+{sup 4}He+X->{sup 4}He+{sup 4}HeX and {sup 4}He+{sup 4}He+X->{sup 4}He{sub 2}+X, with X={sup 7}Li, {sup 23}Na, {sup 39}K, {sup 85}Rb, and {sup 133}Cs, are calculated at nonzero collision energies by including not only zero total angular momentum, J=0, states but also J>0 states. The three-body recombination rates show a relatively weak dependence on the alkali-metal species, differing from each other only by about one order of magnitude, except for the {sup 4}He-{sup 4}He-{sup 23}Na system.

Suno, Hiroya; Esry, B. D. [The Earth Simulator Center, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama 236-0001 (Japan); Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2009-12-15

419

An atomistic assessment of helium behavior in iron  

NASA Astrophysics Data System (ADS)

High helium generation rates in irradiated materials leads to the formation of small He-vacancy clusters that can evolve into larger bubbles and voids. An equation of state that accurately reproduces their pressure-volume relationship is necessary to understand and predict the behaviour of these He-vacancy defects. Previous research has employed equations of state of varying complexity, including the ideal gas, van der Waals, and hard sphere models. We recently used ab initio calculations to determine the energetics of helium-vacancy clusters and applied the results to develop a new three-body interatomic potential that describes the behaviour of helium in iron. This potential was employed in molecular dynamics simulations to determine the conditions for mechanical equilibrium between small helium-stabilized bubbles and an iron matrix, and to systematically map the pressure-volume relationship for the bubbles at a range of temperatures. These atomistic results are compared to an existing equation of state and a modification is proposed for bubbles with high helium densities.

Stoller, R. E.; Osetsky, Yu. N.

2014-12-01

420

Hydrogen Production Using the Modular Helium Reactor  

SciTech Connect

The high-temperature characteristics of the Modular Helium Reactor (MHR) make it a strong candidate for the production of hydrogen using either thermochemical or high-temperature electrolysis (HTE) processes. Using heat from the MHR to drive a Sulfur-Iodine (S-I) thermochemical hydrogen process has been the subject of a DOE sponsored Nuclear Engineering Research Initiative (NERI) project lead by General Atomics, with participation from the Idaho National Engineering and Environmental Laboratory (INEEL) and Texas A&M University. While the focus of much of the initial work was on the S-I thermochemical production of hydrogen, recent activities have also included development of a preconceptual design for an integral HTE hydrogen production plant driven by the process heat and electricity produced by a 600 MWt MHR. This paper describes RELAP5-3D analyses performed to evaluate alternative primary system cooling configurations for the MHR to minimize peak reactor vessel and core temperatures while achieving core helium outlet temperatures in the range of 900 oC to 1000 oC, needed for the efficient production of hydrogen using either the S-I thermochemical or HTE process. The cooling schemes investigated are intended to ensure peak fuel temperatures do not exceed specified limits under normal or transient upset conditions, and that reactor vessel temperatures do not exceed ASME code limits for steady-state or transient conditions using standard LWR vessel materials. Preconceptual designs for both an S-I thermochemical and HTE hydrogen production plant driven by a 600 MWt MHR at helium outlet temperatures in the range of 900 oC to 1000 oC are described and compared. An initial SAPHIRE model to evaluate the reliability, maintainablility, and availability of the S-I hydrogen production plant is also discussed, and plans for future assessments of conceptual designs for both a S-I thermochemical and HTE hydrogen production plant coupled to a 600 MWt modular helium reactor are described.

E. A. Harvego; S. M. Reza; M. Richards; A. Shenoy

2005-05-01

421

Ab Initio simulations of dense helium plasmas.  

PubMed

We study the thermophysical properties of dense helium plasmas by using quantum molecular dynamics and orbital-free molecular dynamics simulations, where densities are considered from 400 to 800??g/cm3 and temperatures up to 800 eV. Results are presented for the equation of state. From the Kubo-Greenwood formula, we derive the electrical conductivity and electronic thermal conductivity. In particular, with the increase in temperature, we discuss the change in the Lorenz number, which indicates a transition from strong coupling and degenerate state to moderate coupling and partial degeneracy regime for dense helium. PMID:21561197

Wang, Cong; He, Xian-Tu; Zhang, Ping

2011-04-01

422

Improved Helium-Barrier Bag  

NASA Technical Reports Server (NTRS)

Specially designed bag maintains helium atmosphere around large, low-temperature duct. Easy to install, durable, and reusable. Intended to prevent cryopumping occurring if air or nitrogen allowed to make contact with cold surface of duct.

Viger, Brent J.; Logan, Robert F.; Fink, Jeffrey E.

1992-01-01

423

Superfluid phases of helium-3  

Microsoft Academic Search

A comprehensive treatment of the theory of superfluid helium-3 is presented in this book. This treatment also illustrates many of the principal themes of theoretical condensed matter physics over the past two decades. The generalized BCS (Barden-Cooper-Schrieffer) pairing theory and the experimental properties of superfluid helium-3 are treated in detail. Extensive treatment of broken symmetries and their relation to macroscopic

Dieter Vollhardt; P. Wolfle; Robert B. Hallock

1991-01-01

424

Radiation source for helium magnetometers  

NASA Technical Reports Server (NTRS)

A radiation source (12) for optical magnetometers (10) which use helium isotopes as the resonance element (30) includes an electronically pumped semiconductor laser (12) which produces a single narrow line of radiation which is frequency stabilized to the center frequency of the helium resonance line to be optically pumped. The frequency stabilization is accomplished using electronic feedback (34, 40, 42, 44) to control a current sources (20) thus eliminating the need for mechanical frequency tuning.

Slocum, Robert E. (Inventor)

1991-01-01

425

PHYSICAL REVIEW A 86, 032506 (2012) Ab initio study of high-lying doubly excited states of helium in static electric fields: Complex-scaling  

E-print Network

in static electric fields: Complex-scaling generalized pseudospectral method in hyperspherical coordinates­11] interest in the study of the effect of static electric fields on low-lying (n 8) doubly excited states in the presence of a strong dc electric field. The GPS method allows nonuniform and optimal spatial discretization

Chu, Shih-I

426

New Opacities for Dense Helium and the Composition of Helium Rich, Very Cool White Dwarf Atmospheres  

NASA Astrophysics Data System (ADS)

Very cool white dwarfs (T eff ? 4000K) are among the oldest stars in the Milky Way. They are of great interest as chronometers for understanding the history of star formation in our Galaxy. To realize the full potential of white dwarf cosmochronology, we need to understand better the physical processes that take place in the surface layers of cool white dwarfs. Strong surface gravity results in a compositionally stratified structure for those stars, with light elements "floating" to the surface. Accretion from the ISM over Gyrs should result in pure H atmosphere for all of them today, regardless of their initial composition. However, observations indicate that many very cool white dwarfs possess helium-rich atmospheres. Envelope models provide a possible explanation for this phenomenon, where He is transported to the atmosphere from the envelope by a convective zone which, for cool white dwarfs of T eff ? 5000K, can extend from the surface down to the helium layer. However, an analysis based on current atmospheric models gives a He abundance that is much higher than can be explained by the convective mixing model. We think that one of the main reason for this discrepancy is an inadequate description of the opacity used in current atmosphere models. The very cool helium-rich atmospheres, with densities up to 2 \\ g/cm3, are fluid, not gaseous. The description of the opacity must be revised for this high density regime. Using quantum molecular dynamics simulations we calculated new opacities for dense helium that are much larger than previously thought. As a result, a much lower helium abundance is found in the coolest white dwarfs, which is in much better agreement with the predictions of the convective mixing model. This research was supported by the United States Department of Energy under contract W-7405-ENG-36.

Kowalski, P. M.; Mazevet, S.; Saumon, D.

2004-12-01

427

SPIN POLARIZED HELIUM3, A PLAYGROUND IN MANY DOMAINS OF PHYSICS  

Microsoft Academic Search

This article gives a survey of the different methods which can be used to polarize the nuclear spin of helium-3. These techniques are particularly discussed in relation to the production of polarized helium-3 targets for nuclear physics experiments, such as electron or proton scattering and neutron spin filters. Some emphasis is given to the development of new powerful solid state

M. LEDUC

1990-01-01

428

Laser ionization and spectroscopy of Cu in superfluid helium nanodroplets  

PubMed Central

Mass and optical spectroscopic methods are used for the analysis of copper (Cu) atoms and clusters doped to helium nanodroplets (HeN). A two-color resonant two-photon ionization scheme is applied to study the Cu 2P1/2,3/2??2S1/2 ground state transition. The absorption is strongly broadened for Cu atoms submerged inside helium nanodroplets and a comparison with computed literature values is provided. An observed ejection of the dopant from the droplet is triggered upon excitation, populating energetically lower states. The formation of Cun clusters up to Cu7 inside helium nanodroplets was observed by means of electron impact ionization mass spectroscopy.

Lindebner, Friedrich; Kautsch, Andreas; Koch, Markus; Ernst, Wolfgang E.

2014-01-01

429

Steering Rydberg wave packets using a chirped train of half-cycle pulses  

Microsoft Academic Search

We present protocols for steering a Rydberg wave packet towards a preferred region in phase space using a train of half-cycle pulses. Developing such protocols is aided by classical phase space portraits. The classical phase space changes its structure as the frequency and the strength of a train of pulses are modulated. The quantum wave packet can be made to

S. Yoshida; C. O. Reinhold; E. Persson; J. Burgdörfer; F. B. Dunning

2005-01-01

430

RYDBERG ATOMS, VARIABLE STARS, KEPLER'S THIRD LAW AND E=hv  

Microsoft Academic Search

Observed radii and oscillation periods of pulsating stars representing several distinct classes or variable stars are shown to obey approximate physical laws that are self-similar analogues to those that are known to correlate the radii and oscillation periods of Rydberg atoms. Magnitudes of the relevant atomic scale parameters and their stellar scale counterparts are quantitatively related by a previously identified

ROBERT L. OLDERSHAW

1988-01-01

431

Phonon transmission at a liquid helium-solid interface: the influence of surface roughness and finite lifetimes of the He states  

SciTech Connect

In a one-dimensional quantum mechanical model the phonon transmission between a solid and liquid He is calculated. It is shown how surface roughness changes the binding forces between the He atoms and the solid and therefore can lead to an increased transmission of low-energy phonons. In addition it turns out that the finite lifetimes of the He states also enhance the transmission probability.

Haug, R.; Sigmund, E.; Weiss, K.

1987-04-01

432

Simulation program for central helium liquefier  

SciTech Connect

The computer program described here analyzes the performance of Fermilab Central Helium Liquefier (CHL) and predicts the values of the plant thermodynamic variables at all process points in the plant. To simulate CHL, this program is modified from the prototype program which was developed by Hitachi Ltd. a couple of years ago. This program takes care of only the steady state simulation and takes account of the change of the turbine efficiency, the pressure drops and the UA values of the heat exchangers. How to use the program is shown.

Kawamura, S.

1984-02-20

433

Polarized Helium to Image the Lung  

NASA Astrophysics Data System (ADS)

The main findings of the european PHIL project (Polarised Helium to Image the Lung) are reported. State of the art optical pumping techniques for polarising 3He gas are described. MRI methodological improvements allow dynamical ventilation images with a good resolution, ultimately limited by gas diffusion. Diffusion imaging appears as a robust method of lung diagnosis. A discussion of the potential advantage of low field MRI is presented. Selected PHIL results for emphysema are given, with the perspectives that this joint work opens up for the future of respiratory medicine.

Leduc, Michèle; Nacher, Pierre Jean

2005-05-01

434

Stability of the Helium-Antiproton System  

NASA Technical Reports Server (NTRS)

In the course of their Born-Oppenheimer calculations of this system Todd and Armour noted that the lowest-lying state closely resembles the hydrogen negative ion, since the antiproton lies very close to the helium nucleus and shields one unit of nuclear charge. In the present paper this observation will be taken seriously to produce a variationally correct estimate of the total energy of this system, along with a similar estimate of the energy of the once-ionized system. The nonadiabatic effect of exactly treating the reduced masses improves the results.

Drachman, Richard J.

2006-01-01

435

The interaction of 193?nm excimer laser radiation with single-crystal zinc oxide: Generation of long lived highly excited particles with evidence of Zn Rydberg formation  

SciTech Connect

In past studies, we have observed copious emissions of ionic and atomic Zn from single-crystal ZnO accompanying irradiation of single-crystal ZnO with 193-nm excimer laser irradiation at fluences below the onset of optical breakdown. The Zn{sup +} and ground state Zn° are studied using time-of-flight techniques and are mass selected using a quadrupole mass spectrometer. Simultaneously, we have observed emitted particles that are detectable with a Channeltron electron multiplier but cannot be mass selected. It is a reasonable hypothesis that these particles correspond to a neutral atom or molecule in highly excited long lived states. We provide strong evidence that they correspond to high lying Rydberg states of atomic Zn. We propose a production mechanism involving laser excitation via a two photon resonance excitation of Zn°.

Khan, Enamul H.; Langford, S. C.; Dickinson, J. T., E-mail: jtd@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States); Boatner, L. A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2014-08-28

436

Helium Diffusion in Olivine  

NASA Astrophysics Data System (ADS)

Diffusion of helium has been characterized in natural Fe-bearing olivine (~Fo90) and synthetic forsterite. Polished, oriented slabs of olivine were implanted with 3He, at 100 keV at a dose of 5x1015/cm2 or at 3.0 MeV at a dose of 1x1016/cm2. A set of experiments on the implanted olivine were run in 1-atm furnaces. In addition to the one-atm experiments, experiments on implanted samples were also run at higher pressures (2.6 and 2.7 GPa) to assess the potential effects of pressure on He diffusion and the applicability of the measured diffusivities in describing He transport in the mantle. The high-pressure experiments were conducted in a piston-cylinder apparatus using an "ultra-soft" pressure cell, with the diffusion sample directly surrounded by AgCl. 3He distributions following experiments were measured with Nuclear Reaction Analysis using the reaction 3He(d,p)4He. This direct profiling method permits us to evaluate anisotropy of diffusion, which cannot be easily assessed using bulk-release methods. For diffusion in forsterite parallel to c we obtain the following Arrhenius relation over the temperatures 250-950°C: D = 3.91x10-6exp(-159 ± 4 kJ mol-1/RT) m2/sec. The data define a single Arrhenius line spanning more than 7 orders of magnitude in D and 700°C in temperature. Diffusion parallel to a appears slightly slower, yielding an activation energy for diffusion of 135 kJ/mol and a pre-exponential factor of 3.73x10-8 m2/sec. Diffusion parallel to b is slower than diffusion parallel to a (by about two-thirds of a log unit); for this orientation an activation energy of 138 kJ/mol and a pre-exponential factor of 1.34x10-8 m2/sec are obtained. This anisotropy is broadly consistent with observations for diffusion of Ni and Fe-Mg in olivine. Diffusion in Fe-bearing olivine (transport parallel to b) agrees within uncertainty with findings for He diffusion in forsterite. The higher-pressure experiments yield diffusivities in agreement with those from the 1-atm experiments, indicating that the results reported here can be reasonably applied to modeling He transport in the upper mantle. The insensitivity of He diffusion to pressure over the investigated range of conditions suggests that compression of the mineral lattice is not sufficient to significantly influence migration of the relatively small helium atoms, which likely diffuse via crystal interstices. The He diffusivities in this work are generally consistent with results from the study of Futagami et al. (1993), who measured He diffusion in natural olivine by outgassing 4He implanted samples, and with the diffusivities measured by bulk-release of 4He and 3He by Shuster et al. (2003), but are about 2 orders of magnitude slower than the recent findings of Tolstikhin et al. (2010) and Blard et al. (2008) . An up-temperature extrapolation of our data also show reasonable agreement with the higher-temperature measurements of Hart (1984). Blard et al. (2008) GCA 72, 3788-3803; Futagami et al. (1993) GCA 57, 3177-3194; Hart (1984) EPSL 70, 297-302; Shuster et al.( 2003) EPSL 217, 19-32; Tolstikhin et al. (2010) GCA 74, 1436-1447

Cherniak, D. J.; Watson, E. B.

2011-12-01

437

Quenching of krypton atoms in the metastable 5s ({sup 3}P{sub 2}) state in collisions with krypton and helium atoms  

SciTech Connect

We have used the absorption probe method to study the processes of collisional quenching of the metastable 5s [3/2]{sup o}{sub 2}({sup 3}P{sub 2}) state of the krypton atom in electron-beam-excited high-pressure He – Kr mixtures with a low content of krypton. The rate constants of plasma-chemical reactions Kr* + Kr + He ? Kr*{sub 2}+He [(2.88 ± 0.29) × 10{sup -33} cm{sup 6} s{sup -1}], Kr* + 2He ? HeKr* + He [(4.6 ± 1.3) × 10{sup -36} cm{sup 6} s{sup -1}] and Kr* + He ? products + He [(1.51 ± 0.15) × 10{sup -15} cm{sup 3} s{sup -1}] are measured for the first time. The rate constants of similar reactions in the Ar – Kr mixture are refined. (active media)

Zayarnyi, D A; L'dov, A Yu; Kholin, I V [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2013-08-31

438

Continuum effects in electron-helium total cross sections  

Microsoft Academic Search

It is shown that total cross sections for the excitation of target states with large spectroscopic factors may be calculated accurately by representing the states by their leading independent-particle configurations. With this approximation coupled-channels calculations agree only qualitatively with experimental total cross sections for the first five states of helium. R-matrix calculations using configuration interaction show better qualitative agreement. The

I. E. McCarthy; K. Ratnavelu; A. M. Weigold

1988-01-01

439

Investigation of particle diffusion and suprathermal electrons in a magnetized helium plasma column  

SciTech Connect

Studying radiative properties of magnetized helium plasma via high-resolution spectroscopy identified close correlations between the particle diffusion and suprathermal electrons for different modes of operation of the MISTRAL installation. The standard diagnostic emission lines in neutral helium (1s3d {sup 3}D-1s2p {sup 3}P, 1s3s {sup 3}S-1s2p {sup 3}P, 1s3d {sup 1}D-1s2p {sup 1}P, and 1s3s {sup 1}S-1s2p {sup 1}P) show anomalous ratios that are related to enhanced particle diffusion and suprathermal electron generation. The supplementary investigation of singlet/triplet Rydberg series (transitions 1snd {sup 3}D-1s2p {sup 3}P and 1s5p {sup 1}P-1s2s {sup 1}S) as well as ionic lines (HeII, transitions n?=?3–4 at 469?nm and n?=?4–6 at 656?nm) allowed quantitative characterization. Simulations carried out with the atomic physics code SOPHIA demonstrate that simultaneous implementation of diffusion processes and suprathermal electrons matches all experimental findings. Single consideration, however, of either diffusion or hot electrons is in contradiction to the proposed extended set of HeI and HeII emission lines. The high precision achieved with the LSJ-split level structure of SOPHIA coupled to Langmuir probe measurements allowed to conclude to a Bohm type diffusion in MISTRAL.

Lefevre, T.; Escarguel, A.; Stamm, R.; Godbert-Mouret, L. [Aix-Marseille Université, CNRS, PIIM UMR 7345, F13397 CEDEX 20, Marseille (France)] [Aix-Marseille Université, CNRS, PIIM UMR 7345, F13397 CEDEX 20, Marseille (France); Rosmej, F. B. [Sorbonne Universités, Pierre et Marie Curie, UMR 7605, LULI, case 128, 4 place Jussieu, F-75252 Paris Cedex 05 (France) [Sorbonne Universités, Pierre et Marie Curie, UMR 7605, LULI, case 128, 4 place Jussieu, F-75252 Paris Cedex 05 (France); LULI, Ecole Polytechnique, CNRS, CEA, Physique Atomique dans les Plasmas Denses PAPD, Route de Saclay, F-91128 Palaiseau (France)

2014-02-15

440

A quantum defect model for the s, p, d, and f Rydberg series of CaF  

E-print Network

We present an improved quantum defect theory model for the “s,” “p,” “d,” and “f” Rydberg series of CaF. The model, which is the result of an exhaustive fit of high-resolution spectroscopic data, parameterizes the electronic ...

Kay, Jeffrey J.

441

Absolute high-resolution Se{sup +} photoionization cross-section measurements with Rydberg-series analysis  

SciTech Connect

Absolute single photoionization cross-section measurements for Se{sup +} ions were performed at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory using the photo-ion merged-beams technique. Measurements were made at a photon energy resolution of 5.5 meV from 17.75 to 21.85 eV spanning the 4s{sup 2}4p{sup 3} {sup 4}S{sub 3/2}{sup o} ground-state ionization threshold and the {sup 2}P{sub 3/2}{sup o},{sup 2}P{sub 1/2}{sup o},{sup 2}D{sub 5/2}{sup o}, and{sup 2}D{sub 3/2}{sup o} metastable state thresholds. Extensive analysis of the complex resonant structure in this region identified numerous Rydberg series of resonances and obtained the Se{sup 2+} 4s{sup 2}4p{sup 23}P{sub 2} and 4s{sup 2}4p{sup 21}S{sub 0} state energies. In addition, particular attention was given to removing significant effects in the measurements due to a small percentage of higher-order undulator radiation.

Esteves, D. A. [University of Nevada, Reno, Department of Physics, MS 0220, Reno, Nevada 89557 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Bilodeau, R. C. [Western Michigan University, MS 5252, 1903 W. Michigan Ave, Kalamazoo, Michigan 49008 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Sterling, N. C. [Department of Physics and Astronomy, Michigan State University, 3248, Biomedical Physical Sciences, East Lansing, Michigan 48824-2320 (United States); Phaneuf, R. A. [University of Nevada, Reno, Department of Physics, MS 0220, Reno, Nevada 89557 (United States); Kilcoyne, A. L. D.; Red, E. C.; Aguilar, A. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2011-07-15

442

COSMIC-RAY HELIUM HARDENING  

SciTech Connect

Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

Ohira, Yutaka; Ioka, Kunihito, E-mail: ohira@post.kek.jp [Theory Center, Institute of Particle and Nuclear Studies, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan)

2011-03-01

443

The rotational structure of methanol and its excitation by helium  

Microsoft Academic Search

We have extended and improved previous calculations of cross-sections for the rotational excitation by helium of A- and E-type methanol in their torsional ground states. We increased the maximum value of the rotational quantum number, j, of the methanol molecule from j = 9, used in the previous calculations, to j = 15, thereby ensuring the completeness of the rotational

Djamal Rabli; D. R. Flower

2010-01-01

444

Equilibrium and stability of charged and uncharged helium film surfaces  

Microsoft Academic Search

We have studied the equilibrium shape and stability of charged and uncharged surfaces on thin films of liquid helium. We assume that the average distance between electrodes is much greater than the film thickness. We used a variational method to obtain the necessary and sufficient conditions for the equilibrium and stability of the equilibrium state of a charged surface. The

Zhakin

1985-01-01

445

Quantum mechanicallycomplete measurements in electron impact excitation of helium  

E-print Network

, experimentally the goal has only been CP500, The Physics of Electronic and Atomic Collisions, edited by Y://proceedings.aip.org/proceedings/cpcr.jsp #12;attained for the 21 ? and 3! P states of helium. Reviews have been given by, for example, Andersen emitted after the excitation process. Earlier studies of the 3*D excitation process made observations

446

Molecular Iodine Fluorescence Using a Green Helium-Neon Laser  

ERIC Educational Resources Information Center

Excitation of molecular iodine vapor with a green (543.4 nm) helium-neon laser produces a fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application of standard evaluation techniques to the spectrum yields ground electronic-state molecular parameters in good agreement with literature…

Williamson, J. Charles

2011-01-01

447

The Helium Atom and Isoelectronic Ions in Two Dimensions  

ERIC Educational Resources Information Center

The energy levels of the helium atom and isoelectronic ions in two dimensions are considered. The difficulties encountered in the analytical evaluation of the perturbative and variational expressions for the ground state, promote an interesting factorization of the inter-electronic interaction, leading to simple expressions for the energy. This…

Patil, S. H.

2008-01-01

448

ALIGNMENT OF METASTABLE HELIUM ATOMS BY UNPOLARIZED RESONANCE RADIATION  

Microsoft Academic Search

Experiments in which helium atoms in the ³S⁠metastable ; state were aligned by the action of unpolarized optical resonance radiation are ; reported. The alignment was detected by resonance methods; the observed line ; widths are of the order of a milligauss with a raw signal-to-noise ratio of ; approximates 1OO: 1. The simplest experimental arrangement is described and

P. A. Franken; F. D. Colegrove

1958-01-01

449

Measurement of the Cascade Transition via the First Excited State of O16 in the C12(?,?)O16 Reaction, and Its S Factor in Stellar Helium Burning  

NASA Astrophysics Data System (ADS)

Radiative ?-particle capture into the first excited, J?=0+ state of O16 at 6.049 MeV excitation energy has rarely been discussed as contributing to the C12(?,?)O16 reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in C12(?,?)O16 for center-of-mass energies of E=2.22MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S6.0(300)=25-15+16keVb] showing that this transition is likely the most important cascade contribution for C12(?,?)O16.

Matei, C.; Buchmann, L.; Hannes, W. R.; Hutcheon, D. A.; Ruiz, C.; Brune, C. R.; Caggiano, J.; Chen, A. A.; D'Auria, J.; Laird, A.; Lamey, M.; Li, Zh.; Liu, Wp.; Olin, A.; Ottewell, D.; Pearson, J.; Ruprecht, G.; Trinczek, M.; Vockenhuber, C.; Wrede, C.

2006-12-01

450

Non-sticking of helium buffer gas to hydrocarbons  

NASA Astrophysics Data System (ADS)

Lifetimes of complexes formed during helium-hydrocarbon collisions at low temperature are estimated for symmetric-top hydrocarbons. The lifetimes are obtained using a density-of-states approach. In general the lifetimes are less than 10-100 ns and are found to decrease with increasing hydrocarbon size. This suggests that clustering will not limit precision spectroscopy in helium-buffer-gas experiments. Lifetimes are computed for noble-gas benzene collisions and are found to be in reasonable agreement with lifetimes obtained from classical trajectories as reported by J. Cui et al. [J. Chem. Phys. 141, 164315 (2014), 10.1063/1.4898796].

Croft, James F. E.; Bohn, John L.

2015-03-01

451

Free-energy model for fluid helium at high density  

E-print Network

We present a semi-analytical free-energy model aimed at characterizing the thermodynamic properties of dense fluid helium, from the low-density atomic phase to the high-density fully ionized regime. The model is based on a free-energy minimization method and includes various different contributions representative of the correlations between atomic and ionic species and electrons. This model allows the computation of the thermodynamic properties of dense helium over an extended range of density and temperature and leads to the computation of the phase diagram of dense fluid helium, with its various temperature and pressure ionization contours. One of the predictions of the model is that pressure ionization occurs abruptly at $\\rho \\simgr 10$ g cm$^{-3}$, {\\it i.e.} $P\\simgr 20$ Mbar, from atomic helium He to fully ionized helium He$^{2+}$, or at least to a strongly ionized state, without He$^{+}$ stage, except at high enough temperature for temperature ionization to become dominant. These predictions and this ...

Winisdoerffer, C; Winisdoerffer, Christophe; Chabrier, Gilles

2004-01-01

452

Coexistence of superfluid and solid helium in aerogel  

NASA Astrophysics Data System (ADS)

The results of recent neutron scattering studies of solid helium in silica aerogel are discussed. Previously I.V. Kalinin et al., Pis’ma Zh. Éksp. Teor. Fiz. 87 (1), 743 (2008) [JETP Lett. 87 (1), 645 (2008)], we detected the existence of a superfluid phase in solid helium at a temperature below 0.6 K and a pressure of 51 bar, although, according to the phase diagram, helium should be in the solid state under these conditions. This work is a continuation of the above studies whose main goal was to examine the detected phenomenon and to establish basic parameters of the existence of a superfluid phase. We have determined the temperature of the superfluid transition from solid to superfluid helium, T C = 1.3 K, by analyzing experimental data. The superfluid phase excitation parameters (lifetime, intensity, and energy) have a temperature dependence similar to that of bulk helium. The superfluid phase coexists with the solid phase in the entire measured temperature range from T = 0.05 K to T C and is a nonequilibrium one and disappears at T C.

Kalinin, I. V.; Kats, E. I.; Koza, M.; Lauter, V. V.; Lauter, H.; Puchkov, A. V.

2010-08-01

453

Coexistence of superfluid and solid helium in aerogel  

SciTech Connect

The results of recent neutron scattering studies of solid helium in silica aerogel are discussed. Previously I.V. Kalinin et al., Pis'ma Zh. Eksp. Teor. Fiz. 87 (1), 743 (2008) [JETP Lett. 87 (1), 645 (2008)], we detected the existence of a superfluid phase in solid helium at a temperature below 0.6 K and a pressure of 51 bar, although, according to the phase diagram, helium should be in the solid state under these conditions. This work is a continuation of the above studies whose main goal was to examine the detected phenomenon and to establish basic parameters of the existence of a superfluid phase. We have determined the temperature of the superfluid transition from solid to superfluid helium, T{sub C} = 1.3 K, by analyzing experimental data. The superfluid phase excitation parameters (lifetime, intensity, and energy) have a temperature dependence similar to that of bulk helium. The superfluid phase coexists with the solid phase in the entire measured temperature range from T = 0.05 K to T{sub C} and is a nonequilibrium one and disappears at T{sub C}.

Kalinin, I. V. [Institute for Physics and Power Engineering (Russian Federation); Kats, E. I.; Koza, M. [Institut Laue-Langevin (France); Lauter, V. V. [Oak Ridge National Laboratory (United States); Lauter, H. [Institut Laue-Langevin (France); Puchkov, A. V., E-mail: puchkov@ippe.r [Institute for Physics and Power Engineering (Russian Federation)

2010-08-15

454

Stabilization of Multi-electron Bubbles in Superfluid Helium  

NASA Astrophysics Data System (ADS)

Multielectron bubbles (MEBs) in liquid helium were first observed in the late 1970s, but their properties have never been explored experimentally due to their short lifetimes and the difficulty to localize them. We report the observation of long- lived MEBs in a novel cell filled with superfluid helium at static negative pressures. MEBs were extracted from the electron filled vapor sheath of a heated filament loop embedded in the superfluid helium and observed by high-speed photography. MEBs are 2D electron gases on the 3D surface of hollow helium bubbles. Diameters can range from nanometers to millimeters, depending on the number of enclosed electrons. Electrons move in angular momentum states; deformations of the surface are called spherical ripplons. The attractive electron-ripplon interaction leads to an unusual form of superconductivity. If they can be compressed, Wigner crystallization and quantum melting can be observed, as well as a new phase for localization called the ripplo- polaron lattice. MEBs are unstable to tunneling discharge when pressed against a surface. Just as Bose gases are captured in a trap for study, MEBs must also be localized away from walls. We shall discuss methods of capturing them in an electromagnetic trap embedded in the liquid helium.

Silvera, Isaac F.; Fang, Jieping; Tempere, Jacques

2014-12-01

455

Photochemistry of 3-hydroxyflavone inside superfluid helium nanodroplets  

SciTech Connect

3-hydroxyflavone is a prototype system for excited state intramolecular proton transfer which is one step of a closed loop photocycle. It was intensively studied for the bare molecule and for the influence of solvents. In the present paper this photocycle is investigated for 3-hydroxyflavone and some hydrated complexes when doped into superfluid helium droplets by the combined measurement of fluorescence excitation spectra and dispersed emission spectra. Significant discrepancies in the proton transfer behavior to gas phase experiments provide evidence for the presence of different complex configurations of the hydrated complexes in helium droplets. Moreover, for bare 3-hydroxyflavone and its hydrated complexes the proton transfer appears to be promoted by the helium environment.

Lehnig, R.; Pentlehner, D.; Vdovin, A.; Dick, B.; Slenczka, A. [Institut fuer Physikalische und Theoretische Chemie Universitaet Regensburg, Regensburg 93040 (Germany)

2009-11-21

456</