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Sample records for helium rydberg states

  1. STIRAP on helium: Excitation to Rydberg states

    NASA Astrophysics Data System (ADS)

    Yuan, Deqian

    Research in optically induced transitions between dierent atomic levels has a long history. For transitions between states driven by a coherent optical eld, the theoretical eciency could be ideally high as 100% but there could be many factors preventing this. In the three state helium atom excitation process, i.e. 23S→33P→nL , the stimulated emission from intermediate state makes it hard to achieve ecient population transfer to the nal state through an intuitive excitation order. One technique to achieve a higher eciency is Stimulated Raman Adiabatic Passage (STIRAP) which is being studied and under research in our lab. Unlike traditional three level excitation processes, STIRAP actually uses a counter intuitive pulsed laser beams timing arrangement. The excitation objects are metastable helium atoms traveling in a vacuum system with a longitudinal velocity of ~ 1070 m/s. We are using a 389 nm UV laser to connect the 23S and the 33P state and a frequency tunable ~790 nm IR laser to connect the 33P state and the dierent Rydberg states. A third 1083 nm wavelength laser beam drives the 23S → 23P transition to transversely separate the residual metastable atoms and the Rydberg atoms for eciency measurements. The data is taken by a stainless steel detector in the vacuum system. As the Rydberg atoms will get ionized by blackbody radiation under room temperature, we can utilize this for their detection. An ion detector sitting on the eld plate is capable to collect the ion signals of the Rydberg atoms for detection. So far the whole system has not been ready for data collection and measurement, so here we are using data and results from previous theses for discussions. The highest transition frequency that has ever been achieved in our lab is around 70% after corrections.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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}Π) 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}Π_{1/2}) and 6^{2}P_{3/2}(^{2}Π_{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)

  3. Effects of transverse photon exchange in helium Rydberg states - Corrections beyond the Coulomb-Breit interaction

    NASA Technical Reports Server (NTRS)

    Au, C. K.

    1989-01-01

    The Breit correction only accounts for part of the transverse photon exchange correction in the calculation of the energy levels in helium Rydberg states. The remaining leading corrections are identified and each is expressed in an effective potential form. The relevance to the Casimir correction potential in various limits is also discussed.

  4. Orientation effects in thermal collisions between ''circular''--Rydberg-state atoms and ground-state helium

    SciTech Connect

    de Prunele, E.

    1985-06-01

    A general formulation for thermal collisions between a Rydberg-state atom and a ground-state rare-gas atom is developed within the framework of the impulse approximation. This formulation allows calculation of cross sections for state-to-state transitions for an arbitrary initial orientation between the Rydberg-state atom and the relative velocity of the two partners of the collision. It also allows a direct computation of these cross sections averaged over all orientations, a situation corresponding to a cell experiment. In this formulation, the differential cross sections with respect to the modulus of the momentum transfer are obtained analytically in terms of rotation matrix elements. Numerical applications are made for the case of a sodium atom in a ''circular'' Rydberg state (Vertical Barn,l,m>, with l = m = n-1) colliding with helium. The collisional processes are found to be highly anisotropic. In particular, a selection rule may appear, or disappear, depending upon the initial orientation. The extension to the case where an external electric field is present is also discussed, with special emphasis on symmetry properties.

  5. Rydberg states of helium in electric and magnetic fields of arbitrary relative orientation

    NASA Astrophysics Data System (ADS)

    Tkáč, Ondřej; Žeško, Matija; Agner, Josef A.; Schmutz, Hansjürg; Merkt, Frédéric

    2016-05-01

    A spectroscopic study of Rydberg states of helium (n = 30 and 45) in magnetic, electric and combined magnetic and electric fields with arbitrary relative orientations of the field vectors is presented. The emphasis is on two special cases where (i) the diamagnetic term is negligible and both paramagnetic Zeeman and Stark effects are linear (n = 30, B ≤ 120 mT and F = 0–78 V cm‑1), and (ii) the diamagnetic term is dominant and the Stark effect is linear (n = 45, B = 277 mT and F = 0–8 V cm‑1). Both cases correspond to regimes where the interactions induced by the electric and magnetic fields are much weaker than the Coulomb interaction, but much stronger than the spin–orbit interaction. The experimental spectra are compared to spectra calculated by determining the eigenvalues of the Hamiltonian matrix describing helium Rydberg states in the external fields. The spectra and the calculated energy-level diagrams in external fields reveal avoided crossings between levels of different m l values and pronounced m l -mixing effects at all angles between the electric- and magnetic-field vectors other than 0. These observations are discussed in the context of the development of a method to generate dense samples of cold atoms and molecules in a magnetic trap following Rydberg–Stark deceleration.

  6. Blackbody-induced decay, excitation and ionization rates for Rydberg states in hydrogen and helium atoms

    NASA Astrophysics Data System (ADS)

    Glukhov, I. L.; Nekipelov, E. A.; Ovsiannikov, V. D.

    2010-06-01

    New features of the blackbody-induced radiation processes on Rydberg atoms were discovered on the basis of numerical data for the blackbody-induced decay Pdnl(T), excitation Penl(T) and ionization Pionnl(T) rates of nS, nP and nD Rydberg states calculated together with the spontaneous decay rates Pspnl in neutral hydrogen, and singlet and triplet helium atoms for some values of the principal quantum number n from 10 to 500 at temperatures from T = 100 K to 2000 K. The fractional rates Rd(e, ion)nl(T) = Pnld(e, ion)(T)/Pspnl equal to the ratio of the induced decay (excitation, ionization) rates to the rate of spontaneous decay were determined as functions of T and n in every series of states with a given angular momentum l = 0, 1, 2. The calculated data reveal an essential difference between the asymptotic dependence of the ionization rate Pionnl(T) and the rates of decay and excitation Pd(e)nl(T)~T/n2. The departures appear in each Rydberg series for n > 100 and introduce appreciable corrections to the formula of Cooke and Gallagher. Two different approximation formulae are proposed on the basis of the numerical data, one for Rd(e)nl(T) and another one for Rionnl(T), which reproduce the calculated values in wide ranges of principal quantum number from n = 10 to 1000 and temperatures between T = 100 K and T = 2000 K with an accuracy of 2% or better. Modified Fues' model potential approach was used for calculating matrix elements of bound-bound and bound-free radiation transitions in helium.

  7. Influence of an external electric field on thermal collisions between ''circular'' Rydberg-state atoms and ground-state helium

    SciTech Connect

    de Prunele, E.

    1986-05-01

    The influence of an external electric field on thermal collisions between a sodium atom excited in a ''circular'' Rydberg state (n = l+1 = m+1 = 20) and a ground-state helium atom is studied numerically within the framework of the impulse approximation. The effect of the field is determined by using parabolic wave functions for the initial and final hydrogenic atomic states. The removal of degeneracy induced by the field appears to have no significant effect for fields in the range of 0-400 V/cm. However, the state-to-state transition cross sections are strongly dependent on the initial orientation as found in previous calculations without electric field.

  8. Ultrafast probing of ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets

    SciTech Connect

    Buenermann, Oliver; Kornilov, Oleg; Neumark, Daniel M.; Haxton, Daniel J.; Gessner, Oliver; Leone, Stephen R.

    2012-12-07

    The ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets are studied with time-resolved extreme ultraviolet ion imaging spectroscopy. At excitation energies of 23.6 {+-} 0.2 eV, Rydberg atoms in n= 3 and n= 4 states are ejected on different time scales and with significantly different kinetic energy distributions. Specifically, n= 3 Rydberg atoms are ejected with kinetic energies as high as 0.85 eV, but their appearance is delayed by approximately 200 fs. In contrast, n= 4 Rydberg atoms appear within the time resolution of the experiment with considerably lower kinetic energies. Major features in the Rydberg atom kinetic energy distributions for both principal quantum numbers can be described within a simple elastic scattering model of localized perturbed atomic Rydberg atoms that are expelled from the droplet due to their repulsive interaction with the surrounding helium bath. Time-dependent kinetic energy distributions of He{sub 2}{sup +} and He{sub 3}{sup +} ions are presented that support the formation of molecular ions in an indirect droplet ionization process and the ejection of neutral Rydberg dimers on a similar time scale as the n= 3 Rydberg atoms.

  9. Molecular Rydberg states. Low-energy Rydberg states of azulene

    SciTech Connect

    Lewis, J.W.; Nauman, R.V.; Bouler, D.B. Jr.; McGlynn, S.P.

    1983-09-15

    Electronic spectra of azulenes are discussed. The low-energy Rydberg states are emphasized. The 3d-Rydberg states lie at 45,000 to 50,000 cm/sup -1/. They are partially quenched by chemical substituents and totally quenched in condensed media. The 3p-Rydberg states lie at approx. 40,000 cm/sup -1/ in azulene and are largely quenched in all derivatives. The quenching of the 3p Rydbergs of azulene in condensed media is responsible for much of the alterations that occur in the S/sub 4/ reverse arrow S/sub 0/ absorption region of azulene upon going from gaseous to condensed phases. The 3s-Rydberg states should lie in the S/sub 2/, S/sub 3/, low-energy S/sub 4/ reverse arrow S/sub 0/ absorption region. Investigations of this region demonstrate two phase-dependent behavioral peculiarities. However, neither of these provides acceptable proof of the presence of a low-energy 3s Rydberg.

  10. Dipolar Dephasing of Rydberg D -State Polaritons

    NASA Astrophysics Data System (ADS)

    Tresp, C.; Bienias, P.; Weber, S.; Gorniaczyk, H.; Mirgorodskiy, I.; Büchler, H. P.; Hofferberth, S.

    2015-08-01

    We experimentally study the effects of the anisotropic Rydberg interaction on D -state Rydberg polaritons slowly propagating through a cold atomic sample. We observe the interaction-induced dephasing of Rydberg polaritons at very low photon input rates into the medium. We develop a model combining the propagation of the two-photon wave function through our system with nonperturbative calculations of the anisotropic Rydberg interaction to show that the observed effect can be attributed to pairwise interaction of individual Rydberg polaritons at distances larger than the Rydberg blockade.

  11. Trojan wavepackets in helium - by core-Rydberg interaction

    SciTech Connect

    Kalinski, M.; Eberly, J.H.

    1996-05-01

    The authors exhibit the existence of core-induced shape invariant wave packets in helium analogous to the Trojan wave packets predicted for hydrogen. They show that the core dipole moment oscillating with the Rabi frequency in the presence of a laser field will cause both radical and angular confinement of an outer Rydberg electron moving around a nearly circular orbit if the parameters of the orbit are properly chosen. They find the relation between the Rabi frequency of the core electron oscillations, laser field strength and the parameters of the Rydberg orbit of the outer electron.

  12. Single-color two-photon spectroscopy of Rydberg states in electric fields

    NASA Astrophysics Data System (ADS)

    Wall, T. E.; Cassidy, D. B.; Hogan, S. D.

    2014-11-01

    Rydberg states of atomic helium with principal quantum numbers ranging from n =20 to n =100 have been prepared by non-resonance-enhanced single-color two-photon excitation from the metastable 2 3S1 state. Photoexcitation was carried out using linearly and circularly polarized pulsed laser radiation. In the case of excitation with circularly polarized radiation, Rydberg states with azimuthal quantum number | mℓ|=2 were prepared in zero electric field and in homogeneous electric fields oriented parallel to the propagation axis of the laser radiation. In sufficiently strong electric fields, individual Rydberg-Stark states were resolved spectroscopically, highlighting the suitability of non-resonance-enhanced multiphoton excitation schemes for the preparation of long-lived high-| mℓ| hydrogenic Rydberg states for deceleration and trapping experiments. Applications of similar schemes for Doppler-free excitation of positronium atoms to Rydberg states are also discussed.

  13. Photoelectron angular distributions in infrared one-photon and two-photon ionization of FEL-pumped Rydberg states of helium

    NASA Astrophysics Data System (ADS)

    Mondal, S.; Fukuzawa, H.; Motomura, K.; Tachibana, T.; Nagaya, K.; Sakai, T.; Matsunami, K.; Yase, S.; Yao, M.; Wada, S.; Hayashita, H.; Saito, N.; Callegari, C.; Prince, K. C.; O'Keeffe, P.; Bolognesi, P.; Avaldi, L.; Miron, C.; Nagasono, M.; Togashi, T.; Yabashi, M.; Ishikawa, K. L.; Sazhina, I. P.; Kazansky, A. K.; Kabachnik, N. M.; Ueda, K.

    2013-10-01

    The photoelectron angular distributions (PADs) have been investigated for infrared (IR) ionization of He atoms excited to Rydberg states by extreme ultraviolet free-electron laser pulses. The experiment was carried out with two pulses which do not overlap in time. Depending on the intensity of the IR pulses, one IR photon ionization or additionally two-photon above-threshold ionization is observed. For low IR intensity, the PAD is well described by a contribution of s and d partial waves in accordance with early experiments. At high IR intensity, the PAD for two IR photon ionization clearly shows the contribution of higher partial waves. The experimental data are compared with the results of theoretical calculations based on solving the time-dependent Schrödinger equation.

  14. Efficient excitation of atomic Rydberg states

    NASA Astrophysics Data System (ADS)

    Corless, John Douglas

    1997-10-01

    We have investigated the optical excitation of atomic Rydberg states with emphasis on efficiency and selectivity. We consider both direct excitation from the ground to the Rydberg state as well as excitation via an intermediate resonance. In the direct excitation case, we find that a major limitation to the selectivity of the process is the optical mixing of the nearly degenerate Rydberg states with the same principal quantum number, but differing angular momentum quantum numbers. The interaction between these states is characterized by Rabi frequencies that exceed the optical frequency even for very modest optical field strengths. This interaction gives rise to angular distributions peaked orthogonal to the laser polarization direction, emission of high harmonics of the laser field, as well as laser induced stabilization. We derive analytic results for this interaction as well as develop a model based on Landau-Zener level-crossing theory. Experimentally, we observe this strong interaction between Rydberg states by examining three-photon ionization in atomic potassium when a picosecond dye laser is tuned through two-photon resonance with the Rydberg series. The ionization signal becomes suppressed when the optical mixing of the Rydberg states becomes large. The details of this suppression depend on the peak intensity of the laser field. We then consider doubly-resonant excitation of Rydberg states and investigate the dependence of the transfer efficiency on the time delay between the two resonant laser pulses. We find that even in the presence of Doppler broadening, transverse spatial variation of the laser beam, and laser amplitude fluctuations that the transfer efficiency from the ground state to the Rydberg state is maximized when the laser pulses are applied in the counterintuitive order. We investigate these predictions experimentally in a three-level cascade system in atomic sodium vapor and verify that the population transfer efficiency is maximized in the counterintuitive regime. We further find that in the presence of laser amplitude fluctuations, the population transfer signal fluctuates less when the pulses are applied in the counterintuitive order.

  15. Transmission-line decelerators for atoms in high Rydberg states

    NASA Astrophysics Data System (ADS)

    Lancuba, P.; Hogan, S. D.

    2014-11-01

    Beams of helium atoms in Rydberg states with principal quantum number n =52 , and traveling with an initial speed of 1950 m/s, have been accelerated, decelerated, and guided while confined in moving electric traps generated above a curved, surface-based electrical transmission line with a segmented center conductor. Experiments have been performed with atoms guided at constant speed, and with accelerations exceeding 107 m /s 2. In each case, the manipulated atoms were detected by spatially resolved, pulsed electric field ionization. The effects of tangential and centripetal accelerations on the effective trapping potentials experienced by the atoms in the decelerator have been studied, with the resulting observations highlighting contributions from the density of excited Rydberg atoms to the acceleration, deceleration, and guiding efficiencies in the experiments.

  16. Rydberg states via CPmmW spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Grimes, David; Field, Robert

    2014-05-01

    Rydberg-Rydberg transitions of Ca atoms are directly observed by chirped-pulse millimeter-wave spectroscopy, which is a form of broadband, high-resolution, free induction decay (FID) spectroscopy with accurate relative intensities. At moderate to high number densities (~106 cm-3), interactions between many Rydberg atoms are mediated by an AC electric field, absorbing and radiating cooperatively. A semiclassical model describes several significant time-domain and frequency-domain cooperative effects in two-level systems and Λ-type three-level systems. Experimental evidence that supports this model will be discussed. A new experiment, employing the buffer gas cooling technique has been constructed and I expect to present preliminary results. In partically, the >100-fold increase in number density will permit study of ``pure electronic'' spectra of Rydberg molecules, such as BaF. We expect to produce 108 state selected core-nonpenetrating Rydberg molecules in a single pulse of a laser-laser-mm-wave excitation sequence.

  17. Photodissociation Dynamics of Diacetylene Rydberg States.

    PubMed

    Wang, Hongzhen; Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun; Yang, Xueming

    2015-11-19

    The state-selective photodissociation of diacetylene (C4H2) was studied in the wavelength range of 127.5-164.4 nm by high-resolution Rydberg H atom time-of-flight spectroscopy measurements. In the wavelength region, two Rydberg series nR and nR' were state-selectively excited using tunable vacuum-ultraviolet laser radiation. In all photolysis wavelengths, two decay channels with different dissociation dynamics were observed. In one channel, the characteristic and isotropic translational energy distributions with a peak around 1800 cm(-1) can be found, suggesting statistical dissociation through internal conversion (IC) from the Rydberg state to the ground state and then dissociation on the ground-state surface. In contrast to this, in the second channel, nonstatistical and anisotropic translational energy distributions were observed, possibly through IC to the excited repulsive state. The vibrational progressions of C4H (A(2)Π) products have also been observed and assigned to the CCC bend and C≡C stretch progressions in the second channel at 3R Rydberg states. PMID:26492566

  18. Many-body calculation of helium D-1-D-3 term intervals for 1snd (n=12 similar to 20) high Rydberg states

    NASA Astrophysics Data System (ADS)

    He, Liming; Cao, Wei

    2006-12-01

    With many-body perturbation theory, D-1-D-3 term intervals of helium 1snd (n = 12 similar to 20) configurations are calculated. Based on two different models, Rayleigh-Schrodinger perturbation expansion terms consisting of bound states only, and those of continua are evaluated, respectively. As for bound states, zeroth-order wave functions are strictly generated from self-iteration solutions of the Hartree equation and residues of infinite expansion series are dealt with by the integral processing method, while a simplified hydrogen potential is adopted to get the continua. Using Rayleigh-Schrodinger expansions, we evaluate exchange energy up to third-order terms. It is found that level splittings are mainly attributed to summations over bound states. The fine-structure level splittings yielded here are found to agree quite well with experimental results.

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

    PubMed

    Kaprálová-Ždánská, Petra Ruth; Šmydke, Jan; Civiš, Svatopluk

    2013-09-14

    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(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. PMID:24050351

  20. 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

    Kaprlov-?nsk, Petra Ruth; mydke, Jan; Department of Radiation and Chemical Physics, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 ; Civi, Svatopluk

    2013-09-14

    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 3858 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.

  1. Logic gates using high Rydberg states

    PubMed Central

    Remacle, F.; Schlag, E. W.; Selzle, H.; Kompa, K. L.; Even, U.; Levine, R. D.

    2001-01-01

    Connected logic gates can be operated on the levels of one molecule by making use of the special properties of high Rydberg states. Explicit experimental results for the NO molecule are provided as an example. A number of other options, including that of several gates concatenated so as to operate as a full adder, are discussed. Specific properties of high Rydberg states that are used are: their autoionization is delayed so that they can be distinguished from direct multiphoton ionization, during their long life such states also can decay by energy transfer to the molecular core in a way that can be controlled by the judicious application of very weak external electrical fields, and the Rydberg states can be detected by the application of an ionizing electrical field. The combination of two (or three) color photons with and without external weak fields allows the construction of quite elaborate logic circuit diagrams and shows that taking advantage of the different intramolecular dynamics of levels that differ by their excitation enables the compounding of logic operations on one molecular frame. PMID:11248016

  2. Logic gates using high Rydberg states.

    PubMed

    Remacle, F; Schlag, E W; Selzle, H; Kompa, K L; Even, U; Levine, R D

    2001-03-13

    Connected logic gates can be operated on the levels of one molecule by making use of the special properties of high Rydberg states. Explicit experimental results for the NO molecule are provided as an example. A number of other options, including that of several gates concatenated so as to operate as a full adder, are discussed. Specific properties of high Rydberg states that are used are: their autoionization is delayed so that they can be distinguished from direct multiphoton ionization, during their long life such states also can decay by energy transfer to the molecular core in a way that can be controlled by the judicious application of very weak external electrical fields, and the Rydberg states can be detected by the application of an ionizing electrical field. The combination of two (or three) color photons with and without external weak fields allows the construction of quite elaborate logic circuit diagrams and shows that taking advantage of the different intramolecular dynamics of levels that differ by their excitation enables the compounding of logic operations on one molecular frame. PMID:11248016

  3. Observation of New Rydberg Series and Resonances in Doubly Excited Helium at Ultrahigh Resolution

    SciTech Connect

    Schulz, K.; Kaindl, G.; Domke, M.; Bozek, J.D.; Heimann, P.A.; Schlachter, A.S.; Rost, J.M.

    1996-10-01

    We report on a striking improvement in spectral resolution in the soft x-ray range to 1.0meV at 64.1eV, measured via the {mu}eV-wide 2,{minus}1{sub 3} double-excitation resonance of helium. This ultrahigh resolution combined with the high photon flux at undulator beam line 9.0.1 of the Advanced Light Source have allowed observation of new Rydberg series and resonances below the {ital N}=3 threshold of doubly excited He. The obtained resonance parameters (energies, lifetime widths, and Fano-{ital q} parameters) are in excellent agreement with the results of state-of-the-art calculations. {copyright} {ital 1996 The American Physical Society.}

  4. Supersymmetry and radial squeezed states for Rydberg wave packets

    NASA Technical Reports Server (NTRS)

    Bluhm, Robert; Kostelecky, V. Alan

    1994-01-01

    Atomic supersymmetry provides an analytical effective-potential model useful for describing certain aspects of Rydberg atoms. Experiments have recently demonstrated the existence of Rydberg wave packets localized in the radial coordinated with p-state angular distribution. This paper shows how atomic supersymmetry can be used to treat radial Rydberg wave packets via a particular analytical type of squeezed state, called a radial squeezed state.

  5. Rydberg States of Atoms and Molecules

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  6. Nonequilibrium Kinetics of Rydberg Atomic States

    SciTech Connect

    Bureyeva, L. A.; Kadomtsev, M. B.; Levashova, M. G.; Lisitsa, V. S.

    2008-10-22

    Two-dimensional quasi-classical model of the radiative-collisional cascade for hydrogen-like systems is developed. The model establishes the correspondence between the quantum and classical approaches. Our calculations of the two-dimensional populations of highly excited atomic hydrogen states for three-body and photorecombination sources of population allow the data of one-dimensional kinetic models to be refined. The calculated intensities of recombination lines demonstrate the degree of nonequilibrium of the Rydberg state populations under typical astrophysical plasma conditions.

  7. Atomic Fock state preparation using Rydberg blockade.

    PubMed

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

    2014-01-31

    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 π 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. PMID:24580449

  8. Laser excitation of localized wave packets of Rydberg states

    NASA Astrophysics Data System (ADS)

    Teper, N. I.; Derbov, V. L.

    2007-06-01

    Nonperturbative numerical modeling of the excitation of the hydrogen atom from the ground state into Rydberg states by means of CW or pulsed laser radiation with linear or circular polarization is presented. Temporal population dynamics of Rydberg states is calculated. The results should be considered as preliminary, since the transitions to continuum and the relaxation processes have not been taken into account.

  9. Cold Rydberg atoms in circular states

    NASA Astrophysics Data System (ADS)

    Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

    2012-06-01

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

  10. Analysis of a controlled phase gate using circular Rydberg states

    NASA Astrophysics Data System (ADS)

    Xia, T.; Zhang, X. L.; Saffman, M.

    2013-12-01

    We propose and analyze the implementation of a two-qubit quantum gate using circular Rydberg states with maximum orbital angular momentum. The intrinsic quantum gate error is limited by the finite Rydberg lifetime and finite Rydberg blockade shift. Circular states have much longer radiative lifetimes than low orbital angular momentum states and are therefore candidates for high-fidelity gate operations. We analyze the dipole-dipole interaction of two circular state Rydberg atoms and present numerical simulations of quantum process tomography to find the intrinsic fidelity of a Rydberg blockade-controlled phase gate. Our analysis shows that the intrinsic gate error can be less than 9×10-6 for circular Cs atoms in a cryogenic environment.

  11. Rydberg states and quantum defects of the NO molecule

    NASA Astrophysics Data System (ADS)

    Kaufmann, Karl; Nager, Christoph; Jungen, Martin

    1985-05-01

    Using a new gaussian for Rydberg orbitals we have calculated orbital energies and oscillator strengths for the Rydberg states of NO up to n* = 5. For comparison with the approach by quantum-defect theory we have evaluated the partial wave decomposition of the wavefunctions ( U matrix) and the quantum defects at threshold.

  12. Rydberg Spectroscopy of Zeeman-Decelerated Beams of Metastable Helium Molecules

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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 ^3Σu^+ 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 ν" = 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 ^3Σu^+ 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).

  13. Squeezing a helium nanodroplet with a Rydberg electron.

    PubMed

    Ancilotto, F; Pi, M; Mayol, R; Barranco, M; Lehmann, K K

    2007-12-13

    We have investigated, by means of density functional theory, the structure of a "scolium", that is, an electron circulating around a positively charged 4He nanodroplet, temporarily prevented from neutralization by the helium-electron repulsion. The positive ion core resides in the center of the nanodroplet where, as a consequence of electrostriction, a strong increase in the helium density with respect to its bulk value occurs. The electron enveloping the 4He cluster exerts an additional electrostatic pressure which further increases the local 4He density around the ion core. We argue that under such pressure, sufficiently small 4He nanodroplets may turn solid. The stability of a scolium with respect to electron-ion recombination is investigated. PMID:17983211

  14. Microwave spectroscopy of Al I Rydberg states: F terms

    NASA Astrophysics Data System (ADS)

    Dyubko, S. F.; Efremov, V. A.; Gerasimov, V. G.; MacAdam, K. B.

    2003-09-01

    Energy level separations in high-lying Rydberg states of neutral aluminium have been measured by a two-photon millimetre-wave resonance method to obtain n 2F-(n + 1) 2F intervals for n = 29-37 with an accuracy ±1 MHz. An Al atomic beam was excited stepwise by pulsed lasers, and the Rydberg atoms were detected by state-selective field ionization. From these data and previous optical data for the 3s2nell configuration of Al I new Ritz-expansion coefficients, which express the weakly n-dependent quantum defects for the nF Rydberg series, have been obtained. A previous laser-spectroscopic study of 2F Rydberg levels in Al I is shown to be in error, and quantum defects based on the classical spectroscopic work of Eriksson and Isberg are confirmed. The nF series is completely regular and shows no sign of perturbations by other electronic configurations.

  15. Spectroscopy of Rydberg States in Laser-Cooled Rubidium Clouds

    NASA Astrophysics Data System (ADS)

    Raithel, Georg

    2000-06-01

    We investigate Rydberg gases excited in a magneto-optic trap of ^87Rb atoms using a two-step optical excitation scheme. The upper excitation step is provided by a tunable, pulsed dye laser with a wavelength of λ ≈ 480nm, which excites ns- and nd- Rydberg states from the intermediate 5P_3/2 level. Trap-loss spectra will be discussed, in which the trap loss induced by the Rydberg excitation is measured vs. the center frequency of the pulsed laser. Both above and below the ionization threshold, over a wide range of the laser pulse energy the trap loss exceeds 50%. We also measure the electron current emitted by the Rydberg gas as a function of time using a microchannelplate detector located near the atomic cloud. Usually, the electron signals extend over a few 100μs after the Rydberg excitation. However, when the pulsed laser excites a discrete ns or nd level, the electron signal can display tails extending over as much as 50ms, largely independent of the value of the principal quantum number n. This time scale is a factor of 100 to 1000 longer than the lifetime of the originally excited Rydberg levels. A model that explains these observations will be presented. Future developments will be discussed.

  16. Revealing photofragmentation dynamics through interactions between Rydberg states: REMPI of HI as a case study.

    PubMed

    Hrmarsson, Helgi Rafn; Kvaran, gst

    2015-12-01

    High energy regions of molecular electronic states are largely characterized by the nature and involvement of Rydberg states. Whereas there are a number of observed dynamical processes that are due to interactions between Rydberg and valence states, reports on the corresponding effect of Rydberg-Rydberg state interaction in the literature are scarce. Here we report a detailed characterization of the effects of interactions between two Rydberg states on photofragmentation processes, for a hydrogen halide molecule. Perturbation effects, showing as rotational line shifts, intensity alterations and line-broadenings in REMPI spectra of HI, for two-photon resonance excitations to the j(3)?(-)(0(+); v' = 0) and k(3)?1(v' = 2) Rydberg states, are analyzed. The data reveal pathways of further photofragmentation processes involving photodissociation, autoionization and photoionization affected by the Rydberg-Rydberg state interactions as well as the involvement of other states, close in energy. Detailed mechanisms of the involved processes are proposed. PMID:26593395

  17. Plasma screening within Rydberg atoms in circular states

    NASA Astrophysics Data System (ADS)

    Flannery, M. R.; Oks, E.

    2008-04-01

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

  18. Autoionizing Rydberg states of NO in strong electric fields

    NASA Astrophysics Data System (ADS)

    Warntjes, J. B. M.; Robicheaux, F.; Bakker, J. M.; Noordam, L. D.

    1999-08-01

    We report on an investigation on autoionization of Rydberg electrons of the nitric oxide molecule in strong, static electric fields. The excitation was done via various rotational states of the A 2Σ+ intermediate state (v'=0) and with polarization parallel or perpendicular to the electric field. The splitting of the autoionizing Rydberg states into overlapping Stark manifolds is resolved for excitation above the saddlepoint created by the field. We observe that the competing decay between photoionization and predissociation can lead to an incorrect interpretation of threshold energy. The photoionization spectrum of NO Rydberg series attached to various rotational thresholds is very similar owing to weak rotational coupling. The experimental results are accurately simulated by quantum calculations based on multichannel quantum defect theory (MQDT). A more intuitive formulation of the average behavior of the photoionization cross section is developed that accounts for the suppression of ionization near the threshold due to competing predissociating channels.

  19. Coherent excitation of a single atom to a Rydberg state

    SciTech Connect

    Miroshnychenko, Y.; Gaeetan, A.; Evellin, C.; Grangier, P.; Wilk, T.; Browaeys, A.; Comparat, D.; Pillet, P.

    2010-07-15

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

  20. Photoionization dynamics of the C2+ ion in Rydberg states

    NASA Astrophysics Data System (ADS)

    Stancalie, Viorica

    2014-11-01

    The goal of this work is to examine in detail the ionization dynamics of Be-like C ion in Rydberg states. An initial calculation has been done to output the lifetime due to spontaneous decay for unperturbed 1s22sns (1Se) Rydberg states using the multi-configuration Dirac-Fock (MCDF) method with configuration interaction option implemented in the general-purpose relativistic atomic structure package (GRASP). Both the C2+ ground state and the C3+ target state energies have been carefully calculated. We report results from a detailed and systematic study of the behaviour of complex photoionization amplitudes, the lifetime due to spontaneous decay for unperturbed 1s22sns (1Se) Rydberg states, the `resonant' phase shift and the rapidly increasing of this shift from well below to well above the resonance position. The sum-over-state method is used to calculate the static dipole polarizability, while the frequency-dependent polarizability values of C2+ ion in these Rydberg states are obtained from two-state model calculation results. Contribution to the Topical Issue "Elementary Processes with Atoms and Molecules in Isolated and Aggregated States", edited by Friedrich Aumayr, Bratislav Marinkovic, Stefan Matejcik, John Tanis and Kurt H. Becker.

  1. Enhanced electron attachment to Rydberg states in molecular hydrogen volume discharges

    NASA Astrophysics Data System (ADS)

    Pinnaduwage, L. A.; Ding, W. X.; McCorkle, D. L.; Lin, S. H.; Mebel, A. M.; Garscadden, A.

    1999-05-01

    We review recent studies on negative ion formation and studies in other areas that are relevant to the role of high-Rydberg states of H2 and H3 in hydrogen negative ion sources. Possible mechanisms for the formation of these excited states are discussed, including the formation of long-lived superexcited (core-excited) Rydberg states. Experimental evidence for negative ion formation via electron attachment to core-excited Rydberg states in a glow discharge apparatus is presented. An expression for the dissociative electron attachment rate constant for Rydberg molecules is derived based on electron capture by a Rydberg molecule due to polarization interaction.

  2. Spectroscopy and dynamics of vibrationally autoionizing nitric oxide Rydberg states

    NASA Astrophysics Data System (ADS)

    Konen, Ian Michael

    Vibrationally autoionizing Rydberg states of nitric oxide are studied to learn about the dynamics of this nonadiabatic (Born-Oppenheimer violating) process. Most of chemical physics is described in terms of the Born-Oppenheimer approximation, in which the nuclei are assumed to be moving too slowly to interact with the motion of the electrons. This thesis presents the study of a specific case where this approximation breaks down. A new theoretical development based on multichannel quantum defect theory (MQDT) is derived, demonstrating the energy dependence of photoelectron dynamics through a weakly autoionizing Rydberg state. This model of resonance mediated photoionization is compared to a first order perturbation theory model of bound-continuum mixing. The two models are shown to predict equivalent results for angular distribution measurements from optically prepared, weakly autoionizing Rydberg states with minimal contribution from direct photoionization. Spectra are reported for Rydberg states converging to the NO+ X (v+ = 1) with total angular momentum, N, from 19--27, and principal quantum number, n, from 11--18. The spectra were recorded by measuring ion current produced by vibrational autoionization of the prepared states. Spectral features were identified by a combination of techniques, including simulations and circular dichroism. Resonant energies were fit to an MQDT expression using a nonlinear least-squares algorithm to extract phase shift parameters of closed-channel K matrix for s, p, and d channels. Eigen defects deduced from this fit are reported for the (v = 1) musd1sigma, mu sd2sigma, mud pi, muddelta, mu psigma, and mup pi channels. Time-of-flight photoelectron spectra and photoelectron angular distributions are reported for seven Rydberg states in the NO (v = 1) s--d complex. A previously reported analysis of the 14 s(v = 1, R = 20) Rydberg state is corrected, and the conclusions from that report are re-evaluated. Significant lambda mixing resulting from vibrational autoionization is confirmed, indicating significant contribution from long-range coupling between the bound states and the continuum.

  3. Selective Population of Molecular Core Nonpenetrating Rydberg States

    NASA Astrophysics Data System (ADS)

    Grimes, David; Zhou, Yan; Barnum, Timothy J.; Klein, Ethan; Field, Robert W.

    2014-06-01

    Core nonpenetrating Rydberg states of molecules are a neglected state of matter. They could have a variety of uses, notably state-selective production of molecular ions. Due to the l(l+1)/r2 centrifugal barrier that prevents the Rydberg electron in high-l states from penetrating inside of the ion core, the electron is essentially uncoupled from the ion core, and the system becomes atom-like with long lifetimes, an "almost good" l quantum number, and electronic transitions that follow ΔJ+=0 and Δv+=0 propensity rules. However, in most molecules access to these states, via a sequence of Δl=+1 transitions from low-n*, low-l states, is blocked by the necessity to traverse the "zone of death," in which nonradiative decay mechanisms are prohibitively fast. We exploit Chirped Pulse millimeter-Wave (CPmmW) spectroscopy to efficiently excite Ca atoms and BaF molecules to core nonpenetrating states in the absence of nonradiative decay mechanisms. A universal method for preparing core nonpenetrating Rydberg states of molecules, which combines CPmmW spectroscopy with STImulated Raman Adiabatic Passage (STIRAP), will be discussed.

  4. Collision-based spectroscopy of Xe VIII Rydberg states

    NASA Astrophysics Data System (ADS)

    Wang, M.; Arnesen, A.; Hallin, R.; Heijkenskjöld, F.; Langereis, A.; Larsson, M. O.; Nordling, C.; Wännström, A.

    1996-08-01

    The photon emission from 10q keV Xeq++T (q=7, 8; T=He, Ar, Na) collisions has been recorded in the 35-800-nm wavelength region. Especially in the T=Na spectra we observed many unreported lines, of which 68 were ascribed to Xe VIII transitions involving Rydberg states. As a result of this, we established 32 new energy levels and revised the energies of 6 previously reported levels. The Xe VIII ionization energy 854 755+/-33 cm-1 was determined with improved accuracy. Furthermore, we derived Ritz formula coefficients for the observed Rydberg series and the core dipole and quadrupole polarizabilities. The analysis was supported by Hartree-Fock calculations.

  5. Sensitive polarization dependence for helium Rydberg atoms driven by strong microwave fields

    SciTech Connect

    Zelazny, S.A.; Bellermann, M.R.W.; Smith, L.L.; Koch, P.M.

    1996-05-01

    The authors prepare n{sup 3}S He Rydberg atoms with selected values n {ge} 25 in a fast beam using CO{sub 2} lasers and double-resonance excitation. They then fly through a TE{sub 121} mode cavity, exposing them to a half-sine pulse (about 350 field osc.) of 9.904 GHz electric field whose polarization can be varied; linear (LP), elliptical (EP), and circular (CP). Making EP close to LP can lead to substantial changes in microwave-power-dependent transitions to nearby bound states. In at least one case, a sharp dip in the LP signal is transformed by EP into a pattern reminiscent of Stueckelberg oscillations, previously observed with LP at higher frequencies. Calculations suggest that pulse-shape-induced dynamics at Floquet avoided-crossing(s) explain the LP behavior. Changing the field to EP clearly must modify this behavior. The authors will discuss this kind of data as well as the polarization dependence of microwave ionization of n{sup 3}S He Rydberg atoms.

  6. Neutral Rydberg-state excitation of atoms and diatomic molecules in strong laser fields

    NASA Astrophysics Data System (ADS)

    Lv, Hang; Zhang, Junfeng; Zuo, Wanlong; Jin, Mingxing; Xu, Haifeng; Ding, Dajun

    2014-04-01

    Using pulsed-field ionization technique combining with time-of-flight mass spectrometer, we have observed neutral Rydberg-state excitation of Ar atom and NO molecule when irradiated by a 90-fs 800-nm laser with intensity range of 1.5×1014 ~ 3.0×1015 Wcm-2. The dependence of the Rydberg-state excitation on the polarization and intensity of the laser field has been investigated. The results show that Rydberg-state excitation is suppressed by the circular polarized laser and the yield of Rydberg-state exhibits a plateau structure as the laser intensity is increased.

  7. On the dynamics of high Rydberg states of large molecules

    NASA Astrophysics Data System (ADS)

    Jortner, Joshua; Bixon, M.

    1995-04-01

    In this paper we explore the level structure, the optical excitation modes and the dynamics of a mixed Stark manifold of very high Rydberg states (with principal quantum numbers n=80-250) of large molecules, e.g., 1,4 diaza bicyclo [2,2,2] octane (DABCO) and bis (benzene) chromium (BBC) [U. Even, R. D. Levine, and R. Bersohn, J. Phys. Chem. 98, 3472 (1994)] and of autoionizing Rydbergs of atoms [F. Merkt, J. Chem. Phys. 100, 2623 (1994)], interrogated by time-resolved zero-electron kinetic energy (ZEKE) spectroscopy. We pursue the formal analogy between the level structure, accessibility and decay of very high Rydbergs in an external weak (F≂0.1-1 V cm-1) electric field and intramolecular (interstate and intrastate) relaxation in a bound molecular level structure. The onset n=nM of the strong mixing (in an external field F and in the field exerted by static ions) of a doorway state, which is characterized by a low azimuthal quantum number l, a finite quantum defect δ, and a total nonradiative width Γs≂Γ0/n3, with the inactive high l manifold is specified by nM≂80.6δ1/5(F/V cm-1)-1/5. At n≥nM the level structure and dynamics are characterized by the product γρ, where ρ is the density of states and γ=ΓsD(n) is the average decay width of the eigenstates, with the dilution factor D(n)≊n-2 for (lml) mixing and D(n)≂n-1 for (l) mixing, whereupon γρ=(Γ0/4δR)(nM/n)5, being independent of D(n). The sparse level structure is realized for γρ≪1, while the dense level structure prevails for γρ≳1, resulting in two limiting situations; (a) a dense limit for n≥nM and a sparse limit for n≫nM, and (b) a sparse limit for all n≥nM. The experimental information currently available on the decay dynamics of molecular (DABCO and BBC) and atomic (Ar) Rydbergs for n≥nM corresponds to case (b). The time-resolved dynamics was characterized in terms of the excited state total population probability P(t) and the population probability I(t) of the doorway state. P(t), which is interrogated by time-resolved ZEKE spectroscopy, will exhibit for both the sparse and dense level structures and for all excitation conditions a superposition of exponential temporal decay terms with an average lifetime of ˜ℏ/γ. I(t) can be used to interrogate coherence effects, which in case (b) are manifested in quantum beats, while case (a) corresponds to a giant resonance with a molecular time characterized by the reciprocal energetic spread of the Stark manifold. The experimental data for the onset of strong mixing and for the diluted lifetimes [ℏ/ΓsD(n) with D(n)˜n-1] of the high Rydbergs (n˜100-200) of BBC and of DABCO are in accord with the predictions of the theory for the limit of strong (l) mixing. While strong mixing is realized for F¯=Fn5/3.4×109δ≳1, we expect that for the weak mixing regime (F¯<1) the dynamics of ultrahigh Rydbergs will be characterized by two distinct (˜ns and ˜μs) time scales. Finally, we emphasize the universality of the model, which provides a unified description of the level structure and dynamics of high Rydbergs of molecules and of autoionizing atoms.

  8. Transfer of entangled state, entanglement swapping and quantum information processing via the Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Deng, Li; Chen, Ai-Xi; Zhang, Jian-Song

    2011-11-01

    We provide a scheme with which the transfer of the entangled state and the entanglement swapping can be realized in a system of neutral atoms via the Rydberg blockade. Our idea can be extended to teleport an unknown atomic state. According to the latest theoretical research of the Rydberg excitation and experimental reports of the Rydberg blockade effect in quantum information processing, we discuss the experimental feasibility of our scheme.

  9. Excitation of Ultracold Molecules to ``TRILOBITE-LIKE" Long-Range Molecular Rydberg States

    NASA Astrophysics Data System (ADS)

    Bellos, M. A.; Carollo, R.; Banerjee, J.; Eyler, E. E.; Gould, P. L.; Stwalley, W. C.

    2013-06-01

    A class of long-range Rydberg molecules, sometimes called ``trilobite states", occurs when a ground-state atom is embedded in the electronic cloud of a Rydberg atom. The bond between the Rydberg atom and the ground-state atom originates from the low-energy scattering of the Rydberg electron from the ground-state atom. We produce trilobite-like states of ultracold Rb_2 at low principal quantum numbers and at internuclear separations less than 40 bohr. We populate these states through single-photon ultraviolet transitions starting from molecules in high-lying vibrational levels of the lowest triplet state. This demonstrates that long-range Rydberg molecules can also be excited through bound-bound transitions, in addition to previous studies that used free-bound transitions. We also discuss the advantages of a bound-bound pathway. C. H. Greene, A. S. Dickinson, and H. R. Sadeghpour, Phys. Rev. Lett. 85, 2458 (2000).

  10. Selective Production of Rydberg-Stark States of Positronium

    NASA Astrophysics Data System (ADS)

    Wall, T. E.; Alonso, A. M.; Cooper, B. S.; Deller, A.; Hogan, S. D.; Cassidy, D. B.

    2015-05-01

    Rydberg positronium (Ps) atoms have been prepared in selected Stark states via two-step (1 s →2 p →n d /ns ) optical excitation. Two methods have been used to achieve Stark-state selection: a field ionization filter that transmits the outermost states with positive Stark shifts, and state-selected photoexcitation in a strong electric field. The former is demonstrated for n =17 and 18 while the latter is performed for n =11 in a homogeneous electric field of 1.9 kV /cm . The observed spectral intensities and their dependence on the polarization of the laser radiation are in agreement with calculations that include the perturbations of the intermediate n =2 manifold. Our results pave the way for the generation of Rydberg Ps atoms with large electric dipole moments that are required for the realization of schemes to control their motion using inhomogeneous electric fields, an essential feature of some proposed Ps free-fall measurements requiring focused beams of long-lived atoms.

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

    SciTech Connect

    Kopyciuk, T.; Parzynski, R.

    2007-05-15

    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 value of localization of the Rydberg wave packet in the coordinate space, the Rydberg-state population distribution, the Husimi phase-space distribution function, and the probability density distribution, each of these measures vs the length of the applied train of half-cycle pulses. The results for chirped trains are compared with those for periodic trains and examples of higher deexcitation efficiency of the chirped trains are given.

  12. High Rydberg states of DABCO: Spectroscopy, ionization potential, and comparison with mass analyzed threshold ionization

    NASA Astrophysics Data System (ADS)

    Boogaarts, Maarten G. H.; Holleman, Iwan; Jongma, Rienk T.; Parker, David H.; Meijer, Gerard; Even, Uzi

    1996-03-01

    Doubly-resonant excitation/vibrational autoionization is used to accurately determine the ionization potential (IP) of the highly symmetric caged amine 1,4 diazabicyclo[2,2,2]octane (DABCO). The IP of DABCO excited with one quantum of the ν24(e') vibration lies at (59 048.62±0.03) cm-1, based on fitting 56 components of the npxy Rydberg series (δ=0.406±0.002) to the Rydberg formula. Rydberg state transition energies and linewidths are determined using standard calibration and linefitting techniques. The IP determined from Rydberg state extrapolation is compared with that determined by mass analyzed threshold ionization (MATI). Effects of static electric fields on MATI signals measured for the high Rydberg states are discussed.

  13. Lensing effect of electromagnetically induced transparency involving a Rydberg state

    NASA Astrophysics Data System (ADS)

    Han, Jingshan; Vogt, Thibault; Manjappa, Manukumara; Guo, Ruixiang; Kiffner, Martin; Li, Wenhui

    2015-12-01

    We study the lensing effect experienced by a weak probe field under conditions of electromagnetically induced transparency (EIT) involving a Rydberg state. A Gaussian coupling beam tightly focused on a laser-cooled atomic cloud produces an inhomogeneity in the coupling Rabi frequency along the transverse direction and makes the EIT area acting like a gradient-index medium. We image the probe beam at the position where it exits the atomic cloud and observe that a red-detuned probe light is strongly focused with a greatly enhanced intensity whereas a blue-detuned one is defocused with a reduced intensity. Our experimental results agree very well with the numerical solutions of Maxwell-Bloch equations.

  14. Measurement of the electronic momentum distributions of Rydberg Stark states

    SciTech Connect

    Murray-Krezan, J.; Jones, R. R.

    2007-06-15

    Approximate momentum distributions of Rydberg electrons in static electric fields have been obtained using an improved impulsive momentum retrieval (IMR) technique. An imaging detector enables the measurement of half-cycle pulse (HCP) ionization probability across the spatial profile of a focused half-cycle pulse beam. By modulating the HCP amplitude we directly measure the derivative of the ionization vs HCP impulse curve, enabling the recovery of momentum distributions with better resolution than previously demonstrated with IMR. For example, for Stark states with small dipole moments, we observe predicted fine-structure in the projection of the momentum distribution along the Stark field axis. We use a semiclassical model to simulate the effect that the nonzero HCP duration has on our measurements. Good agreement between simulated and measured momentum distributions is obtained.

  15. Some new approaches to modeling wave packets of Rydberg states

    NASA Astrophysics Data System (ADS)

    Derbov, Vladimir L.; Bychenkov, Aleksey I.; Teper, Natalja I.; Serov, Vladislav V.

    2004-07-01

    We propose an approximate method for modeling the so-called Trojan wave packets of Rydberg states in a hydrogen-like atom subjected to a circularly polarized microwave field and a constant magnetic field. The method implies the reduction of the Schrodinger wave equation to a set of ordinary nonlinear differential equations for the parameters of the wave packet. Earlier we applied this method to solve the Schrodinger-like parabolic equation in nonlinear optics to describe misaligned beams in waveguide systems. The optimal values of the wave packet initial parameters are obtained. The numerical solution of the obtained differential equations show, that for these parameters the Trojan wave packet moves along a circle orbit.

  16. Generation of singlet states with Rydberg blockade mechanism and driven by adiabatic passage

    NASA Astrophysics Data System (ADS)

    Yang, Rong-Can; Lin, Xiu; Ye, Li-Xiang; Chen, Xiang; He, Juan; Liu, Hong-Yu

    2016-02-01

    A single state is a special state that entangles multi-state quantum systems and plays a significant role in the field of quantum computation. In this paper, we propose a scheme to realize the generation of single states for Rydberg atoms, where one Rydberg atom is trapped in an optical potential and the others are trapped in an adjacent optical potential. Moreover, combining Rydberg blockade and adiabatic-passage technologies, an N-atom singlet state can be generated with the interaction of an N-dimensional Rydberg atom and an (N-1)-atom singlet state. Compared to previous schemes, the advantage of our proposal is that an N-particle N-level singlet state with N?3 may be realized more simply.

  17. Non-classical Rydberg states for metrology experiments

    NASA Astrophysics Data System (ADS)

    Dietsche, Eva-Katharina; Facon, Adrien; Grosso, Dorian; Signoles, Adrien; Dotsenko, Igor; Haroche, Serge; Raimond, Jean-Michel; Brune, Michel; Gleyzes, Sebastien

    2015-05-01

    The Stark level structure of a Rydberg atom offers a large Hilbert space in which we can implement novel complex quantum dynamics. Coupled to a well polarized radio-frequency field, the atom behaves like a large angular momentum. We have recently demonstrated that we can use Quantum Zeno dynamics to prepare the atom in a quantum superposition of coherent spin states. The atom, initially in the circular state, is driven by the radio-frequency field while a microwave field selectively addresses a given Stark sub-level. The coupling to the microwave field leads to a restricted evolution in the Hilbert space, in which the atom periodically evolves in a quantum superposition of two spins pointing in different classical directions. Those states show a Wigner function with fast oscillating interference fringes, which are very sensitive to slight changes of the atomic frequency induced by either the Stark or the Zeeman effect. We explore how such Schrodinger cat states can be used to perform metrology experiments that measure small variations of electric or magnetic fields with a sensitivity beyond the standard quantum limit.

  18. Two-Photon Excited State Dynamics of Dark Valence, Rydberg, and Superexcited States in 1,3-Butadiene.

    PubMed

    Schalk, Oliver; Boguslavskiy, Andrey E; Stolow, Albert

    2014-02-01

    Two-photon absorption in systems with parity permits access to states that cannot be prepared by one-photon absorption. Here we present the first time-resolved photoelectron spectroscopy study using this technique, applied to 1,3-butadiene, in which we investigated the dynamics of its dark valence, Rydberg, and superexcited states. The dark valence state dynamics are accessed via the Rydberg manifold, excited by two photons of 400 nm. We find that the 'dark' 2(1)Ag state populated in this manner has a much longer lifetime than when accesses via the 1(1)Bu 'bright' valence state when populated by one photon of 200 nm. In addition, we compared the dynamics of the 3sπ- and 3dπ-Rydberg states. These Rydberg states relax to the valence manifold on a subpicosecond time scale, with the 3sπ-Rydberg state decay rate being larger due to a stronger valence-Rydberg mixing. Finally, we investigated superexcited valence states that fragment or autoionize within 200 fs, likely without involving Rydberg states. PMID:26276609

  19. Need for high resolution in VUV Rydberg state spectroscopy

    NASA Astrophysics Data System (ADS)

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

    1980-12-01

    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.

  20. Self-interaction corrected density functional calculations of molecular Rydberg states

    SciTech Connect

    Gudmundsdóttir, Hildur; Zhang, Yao; Weber, Peter M.; Jónsson, Hannes; Faculty of Physical Sciences, VR-III, University of Iceland, 107 Reykjavík

    2013-11-21

    A method is presented for calculating the wave function and energy of Rydberg excited states of molecules. A good estimate of the Rydberg state orbital is obtained using ground state density functional theory including Perdew-Zunger self-interaction correction and an optimized effective potential. The total energy of the excited molecule is obtained using the Delta Self-Consistent Field method where an electron is removed from the highest occupied orbital and placed in the Rydberg orbital. Results are presented for the first few Rydberg states of NH{sub 3}, H{sub 2}O, H{sub 2}CO, C{sub 2}H{sub 4}, and N(CH{sub 3}){sub 3}. The mean absolute error in the energy of the 33 molecular Rydberg states presented here is 0.18 eV. The orbitals are represented on a real space grid, avoiding the dependence on diffuse atomic basis sets. As in standard density functional theory calculations, the computational effort scales as NM{sup 2} where N is the number of orbitals and M is the number of grid points included in the calculation. Due to the slow scaling of the computational effort with system size and the high level of parallelism in the real space grid approach, the method presented here makes it possible to estimate Rydberg electron binding energy in large molecules.

  1. Self-interaction corrected density functional calculations of molecular Rydberg states.

    PubMed

    Gudmundsdttir, Hildur; Zhang, Yao; Weber, Peter M; Jnsson, Hannes

    2013-11-21

    A method is presented for calculating the wave function and energy of Rydberg excited states of molecules. A good estimate of the Rydberg state orbital is obtained using ground state density functional theory including Perdew-Zunger self-interaction correction and an optimized effective potential. The total energy of the excited molecule is obtained using the Delta Self-Consistent Field method where an electron is removed from the highest occupied orbital and placed in the Rydberg orbital. Results are presented for the first few Rydberg states of NH3, H2O, H2CO, C2H4, and N(CH3)3. The mean absolute error in the energy of the 33 molecular Rydberg states presented here is 0.18 eV. The orbitals are represented on a real space grid, avoiding the dependence on diffuse atomic basis sets. As in standard density functional theory calculations, the computational effort scales as NM(2) where N is the number of orbitals and M is the number of grid points included in the calculation. Due to the slow scaling of the computational effort with system size and the high level of parallelism in the real space grid approach, the method presented here makes it possible to estimate Rydberg electron binding energy in large molecules. PMID:24320311

  2. Collective state synthesis in an optical cavity using Rydberg atom dipole blockade

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Sheng, Jiteng; Sedlacek, Jonathon A.; Fan, Haoquan; Shaffer, James P.

    2016-03-01

    We investigate the coherent manipulation of interacting Rydberg atoms placed inside a high-finesse optical cavity for the deterministic preparation of strongly coupled light-matter systems. We consider a four-level diamond scheme with one common Rydberg level for N interacting atoms. One side of the diamond is used to excite the atoms into a collective ‘superatom’ Rydberg state using either π-pulses or stimulated Raman adiabatic passage (STIRAP) pulses. The upper transition on the other side of the diamond is used to transfer the collective state to one that is coupled to a field mode of an optical cavity. Due to the strong interaction between the atoms in the Rydberg level, the Rydberg blockade mechanism plays a key role in the deterministic quantum state synthesis of the atoms in the cavity. We use numerical simulation to show that non-classical states of light can be generated and that the state that is coupled to the cavity field is a collective one. We also investigate how different decay mechanisms affect this interacting many-body system. We also analyze our system in the case of two Rydberg excitations within the blockade volume. The simulations are carried out with parameters corresponding to realizable high-finesse optical cavities and alkali atoms like rubidium.

  3. A critical re-assignment of the Rydberg states of iodomethane based on new polarization data

    NASA Astrophysics Data System (ADS)

    Donovan, Robert J.; Hennessy, John T.; Lawley, Kenneth P.; Ridley, Trevor

    2013-04-01

    2- and 3-photon excitation of components of the lower Rydberg states of iodomethane (CH3I) using linearly and circularly polarized light, followed by ionization with one more photon, is used to determine their molecular term symbol, Ω, values as well as quantum defects. These Ω values, together with a detailed theoretical analysis, require a re-assignment of the 7s and 8s states to various components of the 5d and 6d states, but there is evidence of (n+2)s/nd hybridization in the pairs of Ω = 1 states. Predissociation sets in for all Rydberg states beyond 6d based on the ground (2Π3/2) state of the core, but sharp autoionizing resonances based on the 2Π1/2 core state are assigned to the 9s, 7d, and 5f states. The dominant effect of the singlet/triplet character of the Rydberg states on their accessibility from the ground state, seen in bromomethane and chloromethane, is again apparent and a concordant interpretation of the Rydberg spectra of CH3I can now be presented. Evidence for coupling of some Ω = 1 and Ω = 0+ Rydberg states with a repulsive valence state and an ion-pair state, respectively, is also put forward.

  4. Engineering Atomic Rydberg States with Pulsed Electric Fields

    SciTech Connect

    Dunning, F. B.; Mestayer, J. J.; Reinhold, Carlos O; Yoshida, S.; Burgdorfer, J.

    2009-01-01

    Atoms in high-lying Rydberg states with large values of the principal quantum number n, n {ge} 300, form a valuable laboratory in which to explore the control and manipulation of quantum states of mesoscopic size using carefully tailored sequences of short electric field pulses whose characteristic times (duration and/or rise/fall times) are less than the classical electron orbital period. Atoms react to such pulse sequences very differently than to short laser or microwave pulses providing the foundation for a number of new approaches to engineering atomic wavefunctions. The remarkable level of control that can be achieved is illustrated with reference to the generation of localized wavepackets in Bohr-like near-circular orbits, and the production of non-dispersive wavepackets under periodic driving and their transport to targeted regions of phase space. The testing of these control schemes, together with their reversibility, through the creation of electric dipole echoes in Stark wavepackets, is also described. New protocols continue to be developed that will allow even tighter control with the promise of new insights into quantum-classical correspondence, information storage in mesoscopic systems, physics in the ultra-fast ultra-intense regime and nonlinear dynamics in driven systems.

  5. TOPICAL REVIEW: Engineering atomic Rydberg states with pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Dunning, F. B.; Mestayer, J. J.; Reinhold, C. O.; Yoshida, S.; Burgdörfer, J.

    2009-01-01

    Atoms in high-lying Rydberg states with large values of the principal quantum number n, n >= 300, form a valuable laboratory in which to explore the control and manipulation of quantum states of mesoscopic size using carefully tailored sequences of short electric field pulses whose characteristic times (duration and/or rise/fall times) are less than the classical electron orbital period. Atoms react to such pulse sequences very differently than to short laser or microwave pulses providing the foundation for a number of new approaches to engineering atomic wavefunctions. The remarkable level of control that can be achieved is illustrated with reference to the generation of localized wavepackets in Bohr-like near-circular orbits, and the production of non-dispersive wavepackets under periodic driving and their transport to targeted regions of phase space. The testing of these control schemes, together with their reversibility, through the creation of electric dipole echoes in Stark wavepackets, is also described. New protocols continue to be developed that will allow even tighter control with the promise of new insights into quantum-classical correspondence, information storage in mesoscopic systems, physics in the ultra-fast ultra-intense regime and nonlinear dynamics in driven systems.

  6. Rydberg-like electronic states above metallic and dielectric nanotubes

    NASA Astrophysics Data System (ADS)

    Granger, Brian E.

    2003-05-01

    Quantized electronic states have been observed above the surface of planar (Höfer, et al.), Science 227, 1480 (1997). and spherical conductors (V. Kasperovich, K. Wong, G. Tikhonov and V. V. Kresin, Phys. Rev. Lett. 85), 2729 (2000).. These states are formed in the attractive ``image'' potential that occurs when the electron sees its image charge reflected in the surface of the conductor. Unfortunately, the lifetimes of these states are typically short (a few ps) as the electrons decay quickly into the bulk of the conductor. In this talk, I will discuss our recent theoretical prediction (B. E. Granger, P. Kral, H. R. Sadeghpour, and M. Shapiro, Phys. Rev. Lett 89), 135506 (2002)., that long-lived, Rydberg-like electronic states can be formed around cylindrically shaped metallic nanotubes, such as carbon nanotubes (J. W. Wildöer, et al.), Nature 391, 59 (1998).(T. W. Odom, J. Huang, P. Kim and C. M. Lieber, Nature 391), 62 (1998).. The effective interaction potential between a slow moving electron and a conducting (or dielectric) nanotube consists of two parts: an attractive part due to the interaction of the electron with its image charge, and a repulsive part due to the electron's angular momentum about the nanotube axis. The combination of these two effects yields effective potential curves having long range (10-50 nm) wells that support bound image potential states in the 1-10 meV range. A central idea in this work is that the angular momentum of an electron near a nanotube can be used to isolate the electron from the surface of the nanotube and supress the rapid decay of the electron into the bulk of the nanotube. The lifetime is then limited by the much slower processes of radiative decay and the coupling of the electron to the collective modes of the nanotube (phonons and plasmons). These decay mechanisms will be discussed along with possible methods for forming and observing these states in experiments.

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

    SciTech Connect

    Bogomolov, Alexandr S.; Grüner, Barbara; Mudrich, Marcel; Kochubei, Sergei A.; Baklanov, Alexey V.; Novosibirsk State University, Pirogova Str. 2, Novosibirsk 630090

    2014-03-28

    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}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{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}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{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.

  8. Magnetic stabilization of a Rydberg quasimolecule in circular states

    NASA Astrophysics Data System (ADS)

    Flannery, M. R.; Oks, E.

    2006-01-01

    An exact analytical classical solution for the electronic terms of circular Rydberg states (CRS) in the presence of a magnetic field B is obtained for two-Coulomb-center systems. The classical electronic terms are shown to be significantly affected by the magnetic field. In particular, a sufficiently strong magnetic field is shown to cause the appearance of CRS above the ionization threshold. These CRS are the classical molecular counterparts of the quantal atomic quasi-Landau levels (resonances). Study of the stability of the nuclear motion in this system reveals that the system in CRS is, in the absence of the magnetic field, not really a molecule, but only a quasimolecule with antibonding molecular orbitals. We also find that the magnetic field creates a deep minimum in one of the branches of the effective potential of the relative motion of the nuclei, and thereby stabilizes the nuclear motion. We have therefore shown that a magnetic field can transform the quasimolecule into a real, classically described molecule where one of the molecular orbitals becomes bonding. This result reveals a phenomenon—the magnetically controlled stabilization of the quasimolecules in CRS—which is appropriate for future experimental studies.

  9. Magnetic stabilization of a Rydberg quasimolecule in circular states

    SciTech Connect

    Flannery, M. R.; Oks, E.

    2006-01-15

    An exact analytical classical solution for the electronic terms of circular Rydberg states (CRS) in the presence of a magnetic field B is obtained for two-Coulomb-center systems. The classical electronic terms are shown to be significantly affected by the magnetic field. In particular, a sufficiently strong magnetic field is shown to cause the appearance of CRS above the ionization threshold. These CRS are the classical molecular counterparts of the quantal atomic quasi-Landau levels (resonances). Study of the stability of the nuclear motion in this system reveals that the system in CRS is, in the absence of the magnetic field, not really a molecule, but only a quasimolecule with antibonding molecular orbitals. We also find that the magnetic field creates a deep minimum in one of the branches of the effective potential of the relative motion of the nuclei, and thereby stabilizes the nuclear motion. We have therefore shown that a magnetic field can transform the quasimolecule into a real, classically described molecule where one of the molecular orbitals becomes bonding. This result reveals a phenomenon--the magnetically controlled stabilization of the quasimolecules in CRS--which is appropriate for future experimental studies.

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

    NASA Astrophysics Data System (ADS)

    Sprecher, Daniel; Merkt, Frédéric

    2014-03-01

    The structure and dynamics of high-n Rydberg states belonging to series converging to the (v+ = 0, N+ = 0-2) levels of the X^+ ^2Σ _g^+ electronic ground state of HD+ were studied by high-resolution spectroscopy from the GK ^1Σ _g^+ (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 30d21 and 31g22 Rydberg states of gerade symmetry were observed after careful compensation of the stray electric fields. (ii) The singlet 61p12 Rydberg state of ungerade symmetry was found to autoionize to the N+ = 0, ℓ = 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 np11 Rydberg series which lie close to nd21 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 μ _pd of singlet-π 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-1.

  11. Generation of tunable coherent far-infrared radiation using atomic Rydberg states

    SciTech Connect

    Bookless, W.

    1980-12-01

    A source of tunable far-infrared radiation has been constructed. The system has been operated at 91.6 cm/sup -1/ with a demonstrated tunability of .63 cm/sup -1/. The system is based on a Rydberg state transition in optically pumped potassium vapor. The transition energy is tuned by the application of an electric field to the excited vapor. The transition wavelength and the shifted wavelength were detected and measured by the use of a Michelson interferometer and a liquid helium cooled Ga:Ge bolometer and the data was reduced using Fast Fourier transform techniques. Extensive spectroscopy was done on the potassium vapor to elucidate the depopulation paths and rates of the excited levels. Both theoretical and experimental results are presented to support the conclusions of the research effort. Additionally, possible alternative approaches to the population of the excited state are explored and recommendations are made for the future development of this source as well as the potential uses of it in molecular spectroscopy.

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

    PubMed

    Zhao, Runchuan; Konen, Ian M; Zare, Richard N

    2004-11-22

    The spectra of vibrationally excited nf Rydberg states of nitric oxide were recorded by monitoring the photoion current produced using two-photon double resonance excitation via the NO A (2)Sigma(+) state followed by photoexcitation of the Rydberg state that undergoes autoionization. The optical transition intensities from NO A state to nf Rydberg states were calculated, and the results agree closely with experiment. These results combined with circular dichroism measurements allow us to assign rotational quantum numbers to the nf Rydberg states even in a spectrum of relatively low resolution. We report the positions of these nf (upsilon,N,N(c)) Rydberg levels converging to the NO X (1)Sigma(+) upsilon(+) = 1 and 2 ionization limits where N is the total angular momentum excluding electron and nuclear spin and N(c) represents the rotational quantum number of the ion core. Our two-color optical-optical double resonance measurements cover the range of N from 15 to 28, N(c) from 14 to 29, and the principal quantum number n from 9 to 21. The electrostatic interaction between the Rydberg electron and the ion core is used to account for the rotational fine structure and a corresponding model is used to fit the energy levels to obtain the quadrupole moment and polarizability of the NO(+) core. Comparison with a multichannel quantum defect theory fit to the same data confirms that the model we use for the electrostatic interaction between the nf Rydberg electron and the ion core of NO well describes the rotational fine structure. PMID:15549868

  13. Millimeter Wave Spectroscopy of Rydberg States of Molecules in the Region of 260-295 GHz

    NASA Astrophysics Data System (ADS)

    Grimes, David; Zhou, Yan; Barnum, Timothy J.; Field, Robert W.

    2015-06-01

    Free induction decay detected chirped pulse millimeter wave spectroscopy of Rydberg-Rydberg transitions in atoms and molecules is a powerful and flexible method for characterizing the electronic structure of Rydberg states and determining the structure and dynamics of the ion-core. Complicating the use of this technique are the difficulties in reliably and repeatedly accessing not just the most information rich core-nonpenetrating states, but also the low-ℓ core-penetrating Rydberg states in the area of principal quantum number n* >35. Small transition moments and narrow linewidths for transitions between valence electronic states and high Rydberg states are the primary limiting factor. We demonstrate a simple method to avoid the problem entirely by using chirped pulse technology operating in the frequency range of 260-295 GHz, which allows us to sample a lower range of n* values than before with comparable frequency resolution and accuracy as our previous W-band experiments. Further improvements to our experiment in order to accurately capture details of Stark demolition, a technique that provides rapid differentiation between core-penetrating and core-nonpenetrating states, will also be discussed.

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

    SciTech Connect

    Li Leping; Gu Quanli; Knee, J. L.; Wright, J. D.; DiSciacca, J. M.; Morgan, T. J.

    2008-03-15

    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.

  15. UV + V UV double-resonance studies of autoionizing Rydberg states of the hydroxyl radical

    NASA Astrophysics Data System (ADS)

    Green, Amy M.; Liu, Fang; Lester, Marsha I.

    2016-05-01

    The hydroxyl radical (OH) is a key oxidant in atmospheric and combustion chemistry. Recently, a sensitive and state-selective ionization method has been developed for detection of the OH radical that utilizes UV excitation on the A2Σ+-X2Π transition followed by fixed 118 nm vacuum ultraviolet (VUV) radiation to access autoionizing Rydberg states [J. M. Beames et al., J. Chem. Phys. 134, 241102 (2011)]. The present study uses tunable VUV radiation generated by four-wave mixing to examine the origin of the enhanced ionization efficiency observed for OH radicals prepared in specific A2Σ+ intermediate levels. The enhancement is shown to arise from resonant excitation to distinct rotational and fine structure levels of two newly identified 2Π Rydberg states with an A3Π cationic core and a 3d electron followed by ionization. Spectroscopic constants are derived and effects due to uncoupling of the Rydberg electron are revealed for the OH 2Π Rydberg states. The linewidths indicate a Rydberg state lifetime due to autoionization on the order of a picosecond.

  16. UV + V UV double-resonance studies of autoionizing Rydberg states of the hydroxyl radical.

    PubMed

    Green, Amy M; Liu, Fang; Lester, Marsha I

    2016-05-14

    The hydroxyl radical (OH) is a key oxidant in atmospheric and combustion chemistry. Recently, a sensitive and state-selective ionization method has been developed for detection of the OH radical that utilizes UV excitation on the A(2)Σ(+)-X(2)Π transition followed by fixed 118 nm vacuum ultraviolet (VUV) radiation to access autoionizing Rydberg states [J. M. Beames et al., J. Chem. Phys. 134, 241102 (2011)]. The present study uses tunable VUV radiation generated by four-wave mixing to examine the origin of the enhanced ionization efficiency observed for OH radicals prepared in specific A(2)Σ(+) intermediate levels. The enhancement is shown to arise from resonant excitation to distinct rotational and fine structure levels of two newly identified (2)Π Rydberg states with an A(3)Π cationic core and a 3d electron followed by ionization. Spectroscopic constants are derived and effects due to uncoupling of the Rydberg electron are revealed for the OH (2)Π Rydberg states. The linewidths indicate a Rydberg state lifetime due to autoionization on the order of a picosecond. PMID:27179488

  17. Interacting Rydberg atoms in an optical cavity to synthesize coherent collective states using dipole blockade

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Sheng, Jiteng; Sedlacek, Jonathon; Ewel, Charlie; Fan, Haoquan; Shaffer, James

    2015-05-01

    We investigate the coherent manipulation of interacting Rydberg atoms placed inside a high-finesse optical cavity for the preparation of strongly coupled light-matter systems. We consider a four-level diamond scheme with one common Rydberg level. One side of the diamond is used to collectively excite the atoms to the Rydberg level using a pair of pulses. The other side of the diamond is used to produce a collective state that is close to resonance with a field mode of a high-finesse optical cavity. The interaction between Rydberg atoms creates a blockade which is useful for synthesizing the coherent collective state. We use numerical simulation to generate non-classical states of light and also investigate different decay mechanisms affecting this system. We also analyze our system in the case of two Rydberg excitations within the blockade volume. In this case, we show that more elaborate few excitation quantum states can be prepared in the cavity to observe interesting dynamics and analyze the correlation of the two-photon emission. This work is supported by the DARPA Quasar program by a grant through ARO, AFOSR and NSF.

  18. High-resolution spectroscopy of Rydberg states in an ultracold cesium gas

    NASA Astrophysics Data System (ADS)

    Saßmannshausen, H.; Merkt, F.; Deiglmayr, J.

    2013-03-01

    Transitions between high Rydberg states of 133Cs atoms have been studied by high-resolution millimeter-wave spectroscopy of an ultracold sample. The spectroscopic measurements were performed after releasing the atoms from a magneto-optical trap. Switching off all trapping fields and compensating the stray electric and magnetic fields to below 1 mV/cm and 2 mG, respectively, prior to the spectroscopic measurement enabled the recording of millimeter-wave spectra of Rydberg states with principal quantum number beyond n=100 under conditions where the inhomogeneous broadening by stray fields is minimal and no dephasing of the Rydberg-atom sample can be detected over measurement times up to 60 μs. The Fourier-transform-limited line widths of better than 20 kHz enabled the observation of the hyperfine structure of nS and nP Rydberg states of Cs beyond n=90. The analysis of the line shapes of transitions to Rydberg states with n≈230 indicated that field inhomogeneities across the atomic sample represent the dominant cause of spectral broadening at high n values. The analysis also revealed that the initial polarization of the atomic sample (F=4, MF=4) is preserved for several tens of microseconds, the depolarization being caused by slow precession along the magnetic stray fields.

  19. Vibrational Autoionization and Predissociation in High Rydberg States of Nitric Oxide

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.

    1998-05-01

    New results on the competition between autoionization and predissociation in the high Rydberg states of NO are presented. These results provide insight into the earlier work of H. Park et al. [Phys. Rev. Lett. 76, 1591 (1996)] that show evidence for substantial mixing between Rydberg series and ionization continua with even and odd orbital angular momenta. New data based on fluorescence-dip spectroscopy, detection of neutral predissociation products, and photoelectron spectroscopy suggest that the A' ^2Σ ^+ and I ^2Σ ^+ dissociative valence states play an important role in this mixing. As an example, the ionization and dissociation efficiencies of the nf levels are found to depend strongly on whether the total angular momentum minus spin, N, is even or odd, indicating predissociation via a ^2Σ ^+ state. Zeeman splittings observed in a magnetic bottle electron spectrometer also result in an improvement in the assignment of these high Rydberg states.

  20. Vibrational autoionization and predissociation in high Rydberg states of nitric oxide

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.

    1998-05-01

    New results on the competition between autoionization and predissociation in the high Rydberg states of nitric oxide are presented. These results provide insight into the earlier work of Park et al. [Phys. Rev. Lett. 76, 1591 (1996)] that shows evidence for substantial mixing between Rydberg series and ionization continua with even and odd orbital angular momenta (l). New data based on fluorescence-dip spectroscopy, detection of neutral predissociation products, and photoelectron spectroscopy suggest that the A' 2Σ+ and I 2Σ+ dissociative valence states play an important role in this l mixing. Zeeman splittings observed in a magnetic bottle electron spectrometer also result in an improvement in the assignment of these high Rydberg states.

  1. Circular Rydberg states of atomic hydrogen in an arbitrary magnetic field

    NASA Astrophysics Data System (ADS)

    Zhao, L. B.; Saha, B. C.; Du, M. L.

    2011-05-01

    A theoretical method using a B-spline basis set has been proposed to evaluate circular Rydberg states of atomic hydrogen in a strong magnetic field. The combination of this method and a recently reported finite-basis-set technique can provide a practicable scheme to implement high accuracy computations of circular Rydberg states of atomic hydrogen in an arbitrary magnetic field. Energy levels of hydrogen are presented for circular Rydberg states with azimuthal quantum numbers |m | = 10 - 70 as a function of magnetic field strengths ranging from zero to 2.35 × 109 T. Comparison with available theoretical data shows excellent agreement. The variation of spatial distributions of electron probability densities with magnetic field strengths is discussed and competition between Coulomb and magnetic interactions is illustrated. Supported by NSF-CREST project (grant #0630370).

  2. Long-range quantum gate via Rydberg states of atoms in a thermal microwave cavity

    NASA Astrophysics Data System (ADS)

    Sárkány, Lőrinc; Fortágh, József; Petrosyan, David

    2015-09-01

    We propose an implementation of a universal quantum gate between pairs of spatially separated atoms in a microwave cavity at finite temperature. The gate results from reversible laser excitation of Rydberg states of atoms interacting with each other via exchange of virtual photons through a common cavity mode. Quantum interference of different transition paths between the two-atom ground and double-excited Rydberg states makes both the transition amplitude and resonance largely insensitive to the excitations in the microwave cavity quantum bus which can therefore be in any superposition or mixture of photon number states. Our scheme for attaining ultra-long-range interactions and entanglement also applies to mesoscopic atomic ensembles in the Rydberg blockade regime and is scalable to many ensembles trapped within a centimeter-sized microwave resonator.

  3. Reduction of the dc-electric-field sensitivity of circular Rydberg states using nonresonant dressing fields

    NASA Astrophysics Data System (ADS)

    Ni, Y.; Xu, P.; Martin, J. D. D.

    2015-12-01

    Nonresonant dressing fields can make the transition frequency between two circular Rydberg states insensitive to second-order variations in the dc electric field. Perturbation theory can be used to establish the required dressing field amplitude and frequency. The same perturbative approach may be used to understand removal of the first-order dependence of the transition frequency on electric field about a bias dc electric field [Hyafil et al., Phys. Rev. Lett. 93, 103001 (2004), 10.1103/PhysRevLett.93.103001]. The directional alignment of the dressing and dc fields is critical in determining the electric field sensitivity of the dressed transition frequencies. This sensitivity is significantly larger for circular Rydberg states compared to low-angular momentum Rydberg states of Rb.

  4. Van der Waals interactions among alkali Rydberg atoms with excitonic states

    NASA Astrophysics Data System (ADS)

    Zoubi, Hashem

    2015-09-01

    We investigate the influence of the appearance of excitonic states on van der Waals interactions among two Rydberg atoms. The atoms are assumed to be in different Rydberg states, e.g., in the | {ns}> and | {np}> states. The resonant dipole-dipole interactions yield symmetric and antisymmetric excitons, with energy splitting that give rise to new resonances as the atoms approach each other. Only away from these resonances can the van der Waals coefficients, C6sp, be defined. We calculate the C6 coefficients for alkali atoms and present the results for lithium by applying perturbation theory. At short interatomic distances of several μ {{m}}, we show that the widely used simple model of two-level systems for excitons in Rydberg atoms breaks down, and the correct representation implies multi-level atoms. Even though, at larger distances one can keep the two-level systems but in including van der Waals interactions among the atoms .

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

    SciTech Connect

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

    1990-01-01

    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.

  6. Photoexcitation of n 305 Rydberg States in the Presence of an rf Drive Field

    SciTech Connect

    Yoshida, S; Reinhold, Carlos O; Burgdorfer, J.; Ye, S; Dunning, F. B.

    2012-01-01

    The response of highly excited potassium Rydberg states with n 305 to a sinusoidal electric drive field in the radio frequency (100 300 MHz) regime is examined by photoexcitation from the 4s ground state using a uv probe beam. The drive field couples many Rydberg levels simultaneously and results in a coherent response that leads to a variety of multiphoton processes. The excitation spectra are analyzed within the framework of Floquet theory and reveal signatures of quantum optical phenomena such as electromagnetically induced transparency and Autler-Townes splitting seen with few-level systems.

  7. Circular Rydberg States of Atomic Hydrogen in an Arbitrary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Zhao, Li-Bo; B. C., Saha; Du, Meng-Li

    2011-09-01

    We report a theoretical scheme using a B-spline basis set to improve the poor computational accuracy of circular Rydberg states of hydrogen atoms in the intermediate magnetic field. This scheme can produce high accuracy energy levels and valid for an arbitrary magnetic field. Energy levels of hydrogen are presented for circular Rydberg states with azimuthal quantum numbers |m| = 10-70 as a function of magnetic field strengths ranging from zero to 2.35 × 109 T. The variation of spatial distributions of electron probability densities with magnetic field strengths is discussed and competition between Coulomb and magnetic interactions is illustrated.

  8. Photodissociation Efficiency Spectroscopy Study of the Rydberg Excited Ion-Pair States of Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Feng, Qiang; Xu, Yun-Feng; Sun, Jin-Da; Tian, Shan-Xi; Shan, Xiao-Bin; Liu, Fu-Yi; Sheng, Liu-Si

    2009-10-01

    Photodissociation efficiency spectrum of anionic oxygen atom produced via ion-pair dissociations of carbon dioxide is recorded by means of the synchrotron radiation excitation (XUV photon energy 17.40-20.00 eV). The present spectrum is assigned as the Rydberg-like excited ion-pair states, i.e., Tanaka-Ogawa and Henning series, tilde C2Σg+ (CO+2) vibrational ground-state and excitation series. Three Rydberg series, npσu, npπu, and nfu, converging to tilde C2Σg+ (0, 0, 0), show the higher cross sections.

  9. GHz Rabi Flopping to Rydberg States in Hot Atomic Vapor Cells

    SciTech Connect

    Huber, B.; Baluktsian, T.; Schlagmueller, M.; Koelle, A.; Kuebler, H.; Loew, R.; Pfau, T.

    2011-12-09

    We report on the observation of Rabi oscillations to a Rydberg state on a time scale below 1 ns in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of {approx}4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor, thus suggesting small vapor cells as a platform for room-temperature quantum devices. Furthermore, the result implies that previous coherent dynamics in single-atom Rydberg gates can be accelerated by 3 orders of magnitude.

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

    SciTech Connect

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

    2011-11-15

    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.

  11. Formation of the Circular Rydberg States in Ion-Solid Collisions

    NASA Astrophysics Data System (ADS)

    Nandi, T.

    2008-01-01

    We observed the circular Rydberg states populating H-like Fe ions during fast ion-solid collisions. Time-resolved X-ray spectra obtained with 164 MeV 5626Fe ions colliding with a carbon foil do not show any lines due to H-like Fe ions at small delay times until 600 ps. However, Lyα and Lyβ transitions appear after a while and attain maximum intensity at a delay of 920 ± 5 ps. Such a delay is attributed to successive cascading from the circular Rydberg levels, which has important implications for understanding the origin of radio recombination lines from interstellar space.

  12. Spin-charge separation of dark-state polaritons in a Rydberg medium

    NASA Astrophysics Data System (ADS)

    Shi, Xiao-Feng; Svetlichnyy, P.; Kennedy, T. A. B.

    2016-04-01

    The propagation of light fields through a quasi one-dimensional cold atomic gas, exciting atomic Rydberg levels of large principal quantum number under conditions of electromagnetically induced transparency, can lead to a stable two-mode Luttinger liquid system. Atomic van der Waals interactions induce a coupling of bosonic field modes that display both photonic and atomic character, the Rydberg dark-state polaritons (RDPs). It is shown that by tunable control of the van der Waals coupling, the RDP may decouple into independent ‘spin’ and ‘charge’ fields which propagate at different speeds, analogous to spin-charge separation of electrons in a one-dimensional metal.

  13. Vibrational modes in excited Rydberg states of acetone: A computational study

    NASA Astrophysics Data System (ADS)

    Shastri, Aparna; Singh, Param Jeet

    2016-04-01

    Computational studies of electronically excited states of the acetone molecule [(CH3)2CO] and its fully deuterated isotopologue [(CD3)2CO] are performed using the time dependent density functional (TDDFT) methodology. In addition to vertical excitation energies for singlet and triplet states, equilibrium geometries and vibrational frequencies of the n=3 Rydberg states (3s, 3p and 3d) are obtained. This is the first report of geometry optimization and frequency calculations for the 3px, 3pz, 3dyz, 3dxy, 3dxz, 3dx2-y2 and 3dz2 Rydberg states. Results of the geometry optimization indicate that the molecule retains approximate C2V geometry in most of these excited Rydberg states, with the most significant structural change seen in the CCO bond angle which is found to be reduced from the ground state value. Detailed comparison of the computationally predicted vibrational wavenumbers with experimental studies helps to confirm several of the earlier vibronic assignments while leading to revised/new assignments for some of the bands. The important role of hot bands in analysis of the room temperature photoabsorption spectra of acetone is corroborated by this study. While the vibrational frequencies in excited Rydberg states are overall found to be close to those of the ionic ground state, geometry optimization and vibrational frequency computation for each excited state proves to be very useful to arrive at a consistent set of vibronic assignments. Isotopic substitution helps in consolidating and confirming assignments. An offshoot of this study is the interpretation of the band at ~8.47 eV as the π-3s Rydberg transition converging to the second ionization potential.

  14. State transfer of nS ultracold Rydberg atoms in external electric fields

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Zhang, Hao; Wang, Limei; Bao, Shanxia; Zhang, Linjie; Li, Changyong; Zhao, Jianming; Jia, Suotang

    2014-09-01

    The state transfer from cesium nS (n = 45-53) states to Stark (product) states induced by a weak electric field (WEF) pulse was investigated using the state-selective field ionization method in a standard magneto-optic trap (MOT). The WEF pulse shifts the nS Rydberg states that anticross with the (n - 4) hydrogen-like manifolds, causing state transitions from the initial excited nS state to the Stark states. The mechanism of transfer was investigated by changing the rising and falling time of the WEF pulse and the switching off time of the external field pulse had an important role during the evolution process of product states. The population of the product states is also measured as a function of the principal quantum number and Rydberg densities.

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

    SciTech Connect

    Sprecher, Daniel; Merkt, Frédéric

    2014-03-28

    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}Σ{sub g}{sup +} electronic ground state of HD{sup +} were studied by high-resolution spectroscopy from the GK{sup 1}Σ{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, ℓ = 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 μ{sub pd} of singlet-π 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}.

  16. Solvent interaction with the (2p3s) Rydberg state of hexamethylenetetramine: Energetics and relaxation dynamics

    NASA Astrophysics Data System (ADS)

    Shang, Q. Y.; Dion, C.; Bernstein, E. R.

    1994-07-01

    The (1+1) mass resolved excitation spectra are reported for the (2p3s)←(2p)2 Rydberg transition of the tricyclic, high symmetry molecule hexamethylenetetramine [HMT (C6H12N4)] and its van der Waals clusters. The solvent molecules employed include both nonpolar (Ar, CH4) and polar (NH3, CH3OCH3) species. HMT and its clusters are generated and cooled in a supersonic expansion. The observed electronic transition is assigned as T2←A1 within the Td print group. A transition blue shift of 52 cm-1 for each Ar atom and 65 cm-1 for each methane molecule in the HMT van der Waals cluster is characterized. These shifts are caused by an excited state repulsive interaction between the excited Rydberg electron and the closed shell solvent which reduces the attractive dispersion interaction between the HMT and nonpolar solvent species in the van der Waals cluster. A transition red shift of more than 600 cm-1 for NH3 and CH3OCH3 solvent/HMT clusters is observed; this large increase in interaction energy for the excited Rydberg state of HMT with respect to the ground state of HMT is associated with the delocalization of the excited electron into available (virtual) Rydberg orbitals of the solvent molecules. The interaction is characterized as an electron transfer interaction. These results and assignments are consistent with previously reported ones for DABCO/solvent clusters. Relaxation dynamics of excited HMT and its clusters are investigated via a pump/probe (ionization) technique. Relaxation of the clusters is dominated by an intersystem crossing mechanism resulting in an excited state singlet lifetime of ˜5 ns compared to a bare molecule HMT excited state lifetime of ˜1.0 μs. A triplet state of HMT lies 255 cm-1 below the first excited singlet Rydberg state as determined by two-color threshold ionization studies.

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

    SciTech Connect

    Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst

    2014-06-28

    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.

  18. New Rydberg states of gas-phase aluminum halides observed by resonance-enhanced multiphoton ionization spectroscopy

    SciTech Connect

    Hudgens, J.W.; Dearden, D.V.; Johnson, R.D. III

    1993-12-31

    The authors report detection and characterization of AlF and AlCl using 1+2, 2=1, 2+2, 3+1, and 3+2 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. REMPI Spectra of AlF reveal 13 new Rydberg states that lie between 70,000 and 77,000 cm{sup {minus}1}. These new states, in combination with previously known states, form six Rydberg series. Least-squares fitting of the Rydberg series to the Rydberg equation yields the precise adiabatic ionization potential, IP{sub a}(AlF) = 9.729 {+-} 0.001 eV. Vibrational intervals of the new Rydberg states are about 25% greater than those of AlF (X {sup 1}{Sigma}{sup +}), with most lying between 930-980 cm{sup {minus}1}. REMPI spectra of AlCl reveal new Rydberg states that lie between 54000 and 60000 cm{sup {minus}1}. Vibrational intervals of these new Rydberg states are about 25% greater than those of AlCl (X {sup 1}{Sigma}{sup +}), with most lying between 570-600 cm{sup {minus}1}.

  19. Comparative study on atomic and molecular Rydberg-state excitation in strong infrared laser fields

    NASA Astrophysics Data System (ADS)

    Lv, Hang; Zuo, Wanlong; Zhao, Lei; Xu, Haifeng; Jin, Mingxing; Ding, Dajun; Hu, Shilin; Chen, Jing

    2016-03-01

    Rydberg-state excitation of atoms in strong infrared laser fields provides a new complementary aspect of the perspective of atom-strong field interactions. In this article, we perform an experimental and theoretical study on the corresponding process of diatomic molecules, N2 and O2. We show that neutral molecules can also survive strong 800-nm laser fields in high Rydberg states, while their behavior is remarkably different in comparison with their companion atoms, Ar and Xe. The Rydberg excitation of N2 generally behaves similarly to Ar, while that of O2 is more significantly suppressed than the ionization compared to Xe in a high intensity region, which can be understood in the frame of a semiclassical picture, together with their different structures of molecular orbitals. However, distinct quantum features in the Rydberg excitation processes that are apparently beyond the semiclassical picture have been identified, i.e., the less suppressed probability of O2 at low intensity and the oscillation behavior of the ratio between N2 and Ar, indicating that our understanding of the relevant physics is still far from complete.

  20. Involvement of a low-lying Rydberg state in the ultrafast relaxation dynamics of ethylene.

    PubMed

    Champenois, Elio G; Shivaram, Niranjan H; Wright, Travis W; Yang, Chan-Shan; Belkacem, Ali; Cryan, James P

    2016-01-01

    We present a measurement of the time-resolved photoelectron kinetic energy spectrum of ethylene using 156 nm and 260 nm laser pulses. The 156 nm pulse first excites ethylene to the (1)B1u (??(?)) electronic state where 260 nm light photoionizes the system to probe the relaxation dynamics with sub-30 fs resolution. Recent ab initio calculations by Mori et al. [J. Phys. Chem. A 116, 2808-2818 (2012)] have predicted an ultrafast population transfer from the initially excited state to a low-lying Rydberg state during the relaxation of photoexcited ethylene. The measured photoelectron kinetic energy spectrum reveals wave packet motion on the valence state and shows indications that the low-lying ?3s Rydberg state is indeed transiently populated via internal conversion following excitation to the ??(?) state, supporting the theoretical predictions. PMID:26747802

  1. Experimental efforts at NIST towards one-electron ions in circular Rydberg states

    NASA Astrophysics Data System (ADS)

    Tan, Joseph N.; Brewer, Samuel M.; Guise, Nicholas D.

    2011-06-01

    Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

  2. Involvement of a low-lying Rydberg state in the ultrafast relaxation dynamics of ethylene

    NASA Astrophysics Data System (ADS)

    Champenois, Elio G.; Shivaram, Niranjan H.; Wright, Travis W.; Yang, Chan-Shan; Belkacem, Ali; Cryan, James P.

    2016-01-01

    We present a measurement of the time-resolved photoelectron kinetic energy spectrum of ethylene using 156 nm and 260 nm laser pulses. The 156 nm pulse first excites ethylene to the 1B1u (ππ∗) electronic state where 260 nm light photoionizes the system to probe the relaxation dynamics with sub-30 fs resolution. Recent ab initio calculations by Mori et al. [J. Phys. Chem. A 116, 2808-2818 (2012)] have predicted an ultrafast population transfer from the initially excited state to a low-lying Rydberg state during the relaxation of photoexcited ethylene. The measured photoelectron kinetic energy spectrum reveals wave packet motion on the valence state and shows indications that the low-lying π3s Rydberg state is indeed transiently populated via internal conversion following excitation to the ππ∗ state, supporting the theoretical predictions.

  3. Quantum dynamics of a circular Rydberg state in a microwave field

    SciTech Connect

    Buchleitner, A.; Delande, D. )

    1993-11-29

    We present the first complete quantum treatment of the ionization of a circular Rydberg state by a linearily polarized microwave field. Experimentally accessible ionization threshold fields as well as the dynamics of the resonance eigenfunctions are investigated, together with a comparison to the behavior of a quasi-one-dimensional state subject to a microwave, and of a circular state in an intense, high frequency laser field.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  5. Equation of state of metallic helium

    SciTech Connect

    Shvets, V. T.

    2013-01-15

    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.

  6. Fundamental constants and tests of theory in Rydberg states of one-electron ions

    NASA Astrophysics Data System (ADS)

    Jentschura, Ulrich D.; Mohr, Peter J.; Tan, Joseph N.

    2010-04-01

    The nature of the theory of circular Rydberg states of hydrogen-like ions allows highly accurate predictions to be made for energy levels. In particular, uncertainties arising from the problematic nuclear size correction which beset low angular-momentum states are negligibly small for the high angular-momentum states. The largest remaining source of uncertainty can be addressed with the help of quantum electrodynamics calculations, including a new nonperturbative result reported here. More stringent tests of theory and an improved determination of the Rydberg constant may be possible if predictions can be compared with precision frequency measurements in this regime. The diversity of information can be increased by utilizing a variety of combinations of ions and Ryberg states to determine fundamental constants and test theory.

  7. Femtosecond multiphoton ionization of free and aggregated NaI via Rydberg states

    NASA Astrophysics Data System (ADS)

    Stibbe, Darian T.; Charron, Eric; Suzor-Weiner, Annick

    2001-12-01

    Using a wave packet simulation on simplified potential curves, we investigate the vibrational dynamics of NaI in its first excited electronic state, both isolated and aggregated with a molecule of acetonitrile. The probe signal is obtained by resonant multiphoton ionization (REMPI) of the diatomic chromophore NaI via Rydberg states. The addition of acetonitrile is found to change greatly the ionization signal, suggesting strong modification of the reaction dynamics.

  8. Resonances in the population of circular Rydberg states formed in beam-foil excitation

    NASA Astrophysics Data System (ADS)

    Mishra, Adya P.; Nandi, T.; Jagatap, B. N.

    2013-05-01

    By directing fast moving 164 MeV F2656e ion beam on 90 μg/cm2 thick carbon foil we have studied the unresolved decay of short-lived 2p (τ2p≈3.3 fs) and long-lived 2s (τ2s≈350.6 ps) states of H-like Fe in the time range 1.6×104-9.2×105τ2p, where, τ2p and τ2s are, respectively, radiative lifetimes of the 2p and 2s levels. At such large times four resonances have been observed as the humps riding on the decay curve of the beam-foil-excited 2s state. This unusual behavior is explained as consequence of the sequential cascading of circular Rydberg states (l=n-1) to 2p state, which modifies the time dependent photon intensity, I(t), of the 2p→1s transition from an exponential to hump-like structures for t»τ2p. From the detailed study of the cascading process the relative population of circular Rydberg states is determined. It is observed that certain circular Rydberg states are unexpectedly and profusely populated when fast H-like Fe ions emerge from the back surface of a thin solid foil.

  9. Effective Ion-In Potentials for Non-Penetrating Rydberg States of Polar Molecules

    NASA Astrophysics Data System (ADS)

    Coy, Stephen; Grimes, David; Zhou, Yan; Field, Robert W.; Wong, Bryan M.

    2015-06-01

    Rydberg states of atoms or molecules for which the inner turning point of the Rydberg electron on the radial plus centrifugal potential lies outside the bulk of the ion core electron density are known as core-non-penetrating states. Interpretation of Rydberg spectroscopic data for polar molecules makes use of effective potentials that include ionic bonding and polarizability in order to represent electric properties of the ion core. We examine the accuracy and convergence properties of single-center polarization potentials and show that the center of charge representation, for which the core dipole moment is zero so that first-order l-mixing can be neglected, is excluded by the convergence sphere for use with l-states that can be treated by an expansion about the center or mass, the center of dipole or a newly-defined center of polarizability. The potential expansion converges only outside a sphere enclosing the charge distribution, and the sphere is much larger when the center of charge is used. For higher l-states of the rotating molecule (turning points defined in center of mass), the sphere required for convergence is much smaller for an origin within the charge distribution, so that lower l states are modeled correctly.

  10. Spectroscopy of acetylene Rydberg states studied by VUV absorption and (3+1)-Resonantly Enhanced Multiphoton Ionisation

    NASA Astrophysics Data System (ADS)

    Boyé, Séverine; Campos, Andrea; Fillion, Jean-Hugues; Douin, Stéphane; Shafizadeh, Niloufar; Gauyacq, Dolores

    2004-03-01

    The ungerade ns+ nd Rydberg states of C 2H 2 converging to the ground state of the C 2H 2+ cation have been investigated in the energy range 74 000- 88 000 cm-1 by (3+1)-multiphoton ionisation (REMPI) and by VUV absorption spectroscopy at the Super-ACO synchrotron radiation facility. Both methods have allowed the selective analysis of the Rydberg transitions with rotational resolution. Mulliken's semi-united atom model, in which predissociation has been taken into account, was used to understand the relative three-photon intensities among the different electronic transitions within the same Rydberg supercomplex. Lifetimes have been evaluated and illustrate very different behaviours towards predissociation for the observed Rydberg states. To cite this article: S. Boyé et al., C. R. Physique 5 (2004).

  11. Long-lived Electronic Coherence of Rydberg States in the Strong-Field Ionization of a Polyatomic Molecule

    NASA Astrophysics Data System (ADS)

    Konar, Arkaprabha; Shu, Yinan; Levine, Benjamin; Lozovoy, Vadim; Dantus, Marcos

    2015-05-01

    Here, we report on quantum coherent control of a large (>20 atoms) polyatomic molecule. In particular, we explore the time resolved dynamics of dicyclopentadiene when excited by a pair of phase-locked intense 800nm femtosecond pulses by monitoring changes in ion yield of the parent and fragments. Long-lived oscillations are observed for ~ 500 fs in the parent ion yield indicating the presence of long lived-electronic states. We take advantage of the long-lived electronic coherence to control the yield of different fragment ions. The presence of Rydberg states is further supported by ab initio calculations at the EOM-CCSD/6-31 +G** level of theory which identified five low-lying electronic states of neutral DCPD in the regions between 6.4 and 7.0 eV in vertical excitation energy. States of both pure Rydberg and mixed π --> π */Rydberg character are observed in this low energy region and are known to originate from ethylene. The multiphoton excitation of two or more Rydberg states, separated by the photon energy is the key to the observed long-lived electronic coherence in DCPD with a quantum beat at the difference frequency. Rydberg states are expected to have very similar potential energy surfaces and the Rydberg electron is relatively uncoupled to the nuclear dynamics, therefore supporting long electronic coherence time.

  12. Tests of Theory in Rydberg States of One-Electron Ions

    NASA Astrophysics Data System (ADS)

    Tan, Joseph N.; Mohr, Peter J.

    Comparison of optical frequency measurements to predictions of quantum electrodynamics (QED) for Rydberg states of one-electron ions can test theory and allow new determinations of constants of nature to be made. Simplifications in the QED theory of high-angular-momentum states reduces the uncertainty in the prediction of transition frequencies to a level where a new value of the Rydberg constant which is independent of the proton radius can be determined. Since the energy-level spacing between neighbouring Rydberg states grows as the square of the nuclear charge number, it is possible to study transitions with optical frequencies that are accessible to femtosecond laser frequency combs. Recently at the US National Institute of Standards and Technology (NIST), highly charged ions (including bare nuclei) created in an Electron Beam Ion Trap (EBIT) were extracted and captured in a novel compact Penning trap. An ongoing experiment aims to produce one-electron ions isolated in an ion trap designed for laser spectroscopy. Tests of theory in a regime free of nuclear effects would be valuable in shedding light on the puzzle surrounding the large discrepancy in the value of the proton radius inferred from the observed Lamb shift in muonic hydrogen as compared to the value deduced from hydrogen and deuterium spectroscopy and electron scattering measurements.

  13. Rydberg, valence, and ion-pair quintet states of O2

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    We report an ab initio study of the quintet states of molecular oxygen. The calculations are carried out employing the multireference single and double excitation configuration interaction package. Potential energy curves of the six quintet valence states dissociating into ground state atoms and of the four quintet states dissociating to ion-pair atoms were computed. A number of bound quintet Rydberg series converging to the a4Πu and b 4 Σg - states of the O 2+ cation have been identified.

  14. Heavy Rydberg behaviour in high vibrational levels of some ion-pair states of the halogens and inter-halogens

    SciTech Connect

    Donovan, Robert J. E-mail: tr01@staffmail.ed.ac.uk; Lawley, Kenneth P. Ridley, Trevor E-mail: tr01@staffmail.ed.ac.uk

    2015-05-28

    We report the identification of heavy Rydberg resonances in the ion-pair spectra of I{sub 2}, Cl{sub 2}, ICl, and IBr. Extensive vibrational progressions are analysed in terms of the energy dependence of the quantum defect δ(E{sub b}) rather than as Dunham expansions. This is shown to define the heavy Rydberg region, providing a more revealing fit to the data with fewer coefficients and leads just as easily to numbering data sets separated by gaps in the observed vibrational progressions. Interaction of heavy Rydberg states with electronic Rydberg states at avoided crossings on the inner wall of the ion-pair potential is shown to produce distinctive changes in the energy dependence of δ(E{sub b}), with weak and strong interactions readily distinguished. Heavy Rydberg behaviour is found to extend well below near-dissociation states, down to vibrational levels ∼18 000-20 000 cm{sup −1} below dissociation. The rapid semi-classical calculation of δ(E{sub b}) for heavy Rydberg states is emphasised and shows their absolute magnitude to be essentially the volume of phase space excluded from the vibrational motion by avoiding core-core penetration of the ions.

  15. Rydberg States of Atoms and Molecules in the Atmospheres of Very Cool Stars with Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Gnedin, Yu. N.; Piotrovich, M. Yu.; Klyucharev, A. N.

    2015-04-01

    We present the results of observations of ultra cool active stars, including new discoveries and determination of spectral types from the SDSS and 2MASS photometric colors. A number of cool dwarfs emit circularly polarized radio waves generated by the electron cyclotron maser instability. Strong infrared absorption is observed in these stars. Model atmosphere calculations indicate that the pure hydrogen composition may be ruled out. The fundamental dipole-dipole interaction between the cold Rydberg atoms is the dominant physical process in these stars. The Rydberg states exhibit unique phenomena, such as the spin polarization patterns and giant electric dipole moments induced by the magnetic field. As a result, highly excited atoms very sensitive to the electric and magnetic fields can be used for the spectroscopic detection and compensation for the effects of these fields.

  16. Experimental confirmation of circular Rydberg states with projectile-like ions

    NASA Astrophysics Data System (ADS)

    Nandi, T.

    2009-06-01

    Using projectile-like ions instead of projectile ions in a beam-foil source, we have reconfirmed the formation of circular Rydberg states. The projectile-like 6028Ni and 6329Cu ions have been produced by a 5626Fe ion beam and 6230Zn ions by a 5828Ni ion beam, at beam energies above the Coulomb barrier, bombarding a thin carbon foil. Time-resolved x-ray transitions of these projectile-like ions attain their maximum intensities at different delays. Such delays are attributed to successive cascading through yrast transitions from the circular Rydberg levels, which find important implications in understanding the origin of radio recombination lines from interstellar space.

  17. Microwave Spectroscopy of High-L, n=10 Rydberg states of Silicon

    NASA Astrophysics Data System (ADS)

    Komara, R. A.; Fehrenbach, C. W.

    2005-05-01

    Using the RESIS/microwave technique [1], we have measured two fine structure intervals between high-L, n=10 Rydberg states of Silicon. A fast Si beam was obtained from an 8 keV Si^+ beam by charge exchange in an n=10 Rb Rydberg target. Individual n=10 Rydberg levels with L=6-9 were selectively detected by upwards excitation to n=31, using a Doppler tuned CO2 laser, followed by Stark ionization of the n=31 level and collection of the resulting ions. This L-selective detection was then used to detect microwave-induced transitions from L=7 to L=8 and from L=8 to =9. The measured intervals give a much improved determination of the dipole polarizability of the ground state of Si^+,^ (3p ^2 P1/2). An unexpected observation is the large ``spin-splitting" between the two levels formed by coupling Jc to L. The observed splittings are more than an order of magnitude larger than expected from magnetic interactions. [1] R.A. Komara, M.A. Gearba, C.W. Fehrenback and S.R. Lundeen, J. Phys. B: At. Mol. Opt. Phys. 38 S87 (2005).

  18. Solvation effects on the molecular 3s Rydberg state: AZAB/CYCLO octanes clustered with argon

    NASA Astrophysics Data System (ADS)

    Shang, Q. Y.; Moreno, P. O.; Li, S.; Bernstein, E. R.

    1993-02-01

    Two color, 1+1, mass resolved excitation spectroscopy (MRES) is used to obtain molecular Rydberg (3s←n) spectra of azabicyclo[2.2.2]octane (ABCO) and diazabicyclo[2.2.2]octane (DABCO) clustered with argon. Nozzle/laser timing delay studies are employed together with time-of-flight mass spectroscopy to identify cluster composition. Population depletion techniques are used to differentiate between clusters with the same mass, but different geometries. A Lennard-Jones 6-12 potential is used to model the intermolecular interactions and predict minimum energy cluster geometries and cluster binding energies. The experimental results are combined with the cluster geometry calculations to assign spectral features to specific cluster geometries. Three different excited state interactions are required to model the experimentally observed line shapes, spectral shifts, and cluster dissociation. The relationship between these model potentials and the cluster binding sites suggests that the form of the cluster intermolecular potential in the Rydberg excited state is dictated by the distance between the argon and chromophore atoms. A comparison of results for ABCO(Ar)1 and DABCO(Ar)1 leads to the conclusion that the nitrogen 3s Rydberg orbital in clusters of DABCO is delocalized.

  19. Observation of the (2 p , nd ) sup 1 P o double-excitation Rydberg series of helium

    SciTech Connect

    Domke, M.; Remmers, G.; Kaindl, G. )

    1992-08-24

    Double-excitation Rydberg resonances of He below the {ital N}=2 threshold of He{sup +} were studied with an energy resolution of {congruent}4 meV by photoionization using synchrotron radiation. All three Rydberg series of {sup 1}{ital P{ital o}} resonances accessible by photoabsorption, including the hitherto missing'' (2{ital p},{ital nd}){sup 1}{ital P{ital o}} series, were resolved. This settles a long-standing discrepancy between experiment and theoretical predictions and establishes a firm basis for testing the accuracy of atomic multiconfiguration calculations.

  20. Theoretical description of electronically excited vinylidene up to 10 eV: First high level ab initio study of singlet valence and Rydberg states

    NASA Astrophysics Data System (ADS)

    Boyé-Péronne, Séverine; Gauyacq, Dolores; Liévin, Jacques

    2014-11-01

    The first quantitative description of the Rydberg and valence singlet electronic states of vinylidene lying in the 0-10 eV region is performed by using large scale ab initio calculations. A deep analysis of Rydberg-valence interactions has been achieved thanks to the comprehensive information contained in the accurate Multi-Reference Configuration Interaction wavefunctions and an original population analysis highlighting the respective role played by orbital and state mixing in such interactions. The present theoretical approach is thus adequate for dealing with larger than diatomic Rydberg systems. The nine lowest singlet valence states have been optimized. Among them, some are involved in strong Rydberg-valence interactions in the region of the Rydberg state equilibrium geometry. The Rydberg states of vinylidene present a great similarity with the acetylene isomer, concerning their quantum defects and Rydberg molecular orbital character. As in acetylene, strong s-d mixing is revealed in the n = 3 s-d supercomplex. Nevertheless, unlike in acetylene, the close-energy of the two vinylidene ionic cores 2A1 and 2B1 results into two overlapped Rydberg series. These Rydberg series exhibit local perturbations when an accidental degeneracy occurs between them and results in avoided crossings. In addition, some Δl = 1 (s-p and p-d) mixings arise for some Rydberg states and are rationalized in term of electrostatic interaction from the electric dipole moment of the ionic core. The strongest dipole moment of the 2B1 cationic state also stabilizes the lowest members of the n = 3 Rydberg series converging to this excited state, as compared to the adjacent series converging toward the 2A1 ionic ground state. The overall energies of vinylidene Rydberg states lie above their acetylene counterpart. Finally, predictions for optical transitions in singlet vinylidene are suggested for further experimental spectroscopic characterization of vinylidene.

  1. Theoretical description of electronically excited vinylidene up to 10 eV: First high level ab initio study of singlet valence and Rydberg states

    SciTech Connect

    Boyé-Péronne, Séverine; Gauyacq, Dolores; Liévin, Jacques

    2014-11-07

    The first quantitative description of the Rydberg and valence singlet electronic states of vinylidene lying in the 0–10 eV region is performed by using large scale ab initio calculations. A deep analysis of Rydberg-valence interactions has been achieved thanks to the comprehensive information contained in the accurate Multi-Reference Configuration Interaction wavefunctions and an original population analysis highlighting the respective role played by orbital and state mixing in such interactions. The present theoretical approach is thus adequate for dealing with larger than diatomic Rydberg systems. The nine lowest singlet valence states have been optimized. Among them, some are involved in strong Rydberg-valence interactions in the region of the Rydberg state equilibrium geometry. The Rydberg states of vinylidene present a great similarity with the acetylene isomer, concerning their quantum defects and Rydberg molecular orbital character. As in acetylene, strong s-d mixing is revealed in the n = 3 s-d supercomplex. Nevertheless, unlike in acetylene, the close-energy of the two vinylidene ionic cores {sup 2}A{sub 1} and {sup 2}B{sub 1} results into two overlapped Rydberg series. These Rydberg series exhibit local perturbations when an accidental degeneracy occurs between them and results in avoided crossings. In addition, some Δl = 1 (s-p and p-d) mixings arise for some Rydberg states and are rationalized in term of electrostatic interaction from the electric dipole moment of the ionic core. The strongest dipole moment of the {sup 2}B{sub 1} cationic state also stabilizes the lowest members of the n = 3 Rydberg series converging to this excited state, as compared to the adjacent series converging toward the {sup 2}A{sub 1} ionic ground state. The overall energies of vinylidene Rydberg states lie above their acetylene counterpart. Finally, predictions for optical transitions in singlet vinylidene are suggested for further experimental spectroscopic characterization of vinylidene.

  2. Theoretical description of electronically excited vinylidene up to 10 eV: first high level ab initio study of singlet valence and Rydberg states.

    PubMed

    Boy-Pronne, Sverine; Gauyacq, Dolores; Livin, Jacques

    2014-11-01

    The first quantitative description of the Rydberg and valence singlet electronic states of vinylidene lying in the 0-10 eV region is performed by using large scale ab initio calculations. A deep analysis of Rydberg-valence interactions has been achieved thanks to the comprehensive information contained in the accurate Multi-Reference Configuration Interaction wavefunctions and an original population analysis highlighting the respective role played by orbital and state mixing in such interactions. The present theoretical approach is thus adequate for dealing with larger than diatomic Rydberg systems. The nine lowest singlet valence states have been optimized. Among them, some are involved in strong Rydberg-valence interactions in the region of the Rydberg state equilibrium geometry. The Rydberg states of vinylidene present a great similarity with the acetylene isomer, concerning their quantum defects and Rydberg molecular orbital character. As in acetylene, strong s-d mixing is revealed in the n = 3 s-d supercomplex. Nevertheless, unlike in acetylene, the close-energy of the two vinylidene ionic cores (2)A1 and (2)B1 results into two overlapped Rydberg series. These Rydberg series exhibit local perturbations when an accidental degeneracy occurs between them and results in avoided crossings. In addition, some ?l = 1 (s-p and p-d) mixings arise for some Rydberg states and are rationalized in term of electrostatic interaction from the electric dipole moment of the ionic core. The strongest dipole moment of the (2)B1 cationic state also stabilizes the lowest members of the n = 3 Rydberg series converging to this excited state, as compared to the adjacent series converging toward the (2)A1 ionic ground state. The overall energies of vinylidene Rydberg states lie above their acetylene counterpart. Finally, predictions for optical transitions in singlet vinylidene are suggested for further experimental spectroscopic characterization of vinylidene. PMID:25381524

  3. 3s Rydberg and cationic States of pyrazine studied by photoelectron spectroscopy.

    PubMed

    Oku, Mizuki; Hou, Yu; Xing, Xi; Reed, Beth; Xu, Hong; Chang, Chao; Ng, Cheuk-Yiu; Nishizawa, Kiyoshi; Ohshimo, Keijiro; Suzuki, Toshinori

    2008-03-20

    We have studied 3s(n-1 and pi-1) Rydberg states and D0(n-1) and D1(pi-1) cationic states of pyrazine [1,4-diazabenzene] by picosecond (2 + 1) resonance-enhanced multiphoton ionization (REMPI), (2 + 1) REMPI photoelectron imaging, He(I) ultraviolet photoelectron spectroscopy (UPS), and vacuum ultraviolet pulsed field ionization photoelectron spectroscopy (VUV-PFI-PE). The new He(I) photoelectron spectrum of pyrazine in a supersonic jet revealed a considerably finer vibrational structure than a previous photoelectron spectrum of pyrazine vapor. We performed Franck-Condon analysis on the observed photoelectron and REMPI spectra in combination with ab initio density functional theory and molecular orbital calculations to determine the equilibrium geometries in the D0 and 3s(n-1) states. The equilibrium geometries were found to differ slightly between the D0 and 3s states, indicating the influence of a Rydberg electron on the molecular structure. The locations of the D1-D0 and 3s(pi-1)-3s(n-1) conical intersections were estimated. From the line width in the D1 <-- S0 spectrum, we estimated the lifetime of D1 to be 12 fs for pyrazine and 15 fs for fully deuterated pyrazine. A similar lifetime was estimated for the 3s(pi-1) state of pyrazine by REMPI spectroscopy. The vibrational feature of D1 observed in the VUV-PFI-PE measurement differed dramatically from that in the UPS spectrum, which suggests that the high-n Rydberg (ZEKE) states converging to the D1 vibronic state are short-lived due to electronic autoionization to the D0 continuum. PMID:18293947

  4. Probing the Dynamics of Rydberg and Valence States of Molecular Nitrogen with Attosecond Transient Absorption Spectroscopy.

    PubMed

    Warrick, Erika R; Cao, Wei; Neumark, Daniel M; Leone, Stephen R

    2016-05-19

    An attosecond pulse is used to create a wavepacket in molecular nitrogen composed of multiple bound and autoionizing electronic states of Rydberg and valence character between 12 and 16.7 eV. A time-delayed, few-femtosecond, near-infrared (NIR) laser pulse is used to couple individual states in the wavepacket to multiple neighboring states, resulting in time-dependent modification of the absorption spectrum and revealing both individual quantum beats of the wavepacket and the energy shifts of the excited states in the presence of the strong NIR field. The broad bandwidth of the attosecond pulse and high energy resolution of the extreme ultraviolet spectrometer allow the simultaneous observation of time-dependent dynamics for many individual vibrational levels in each electronic state. Quantum beating with periods from 1.3 to 12 fs and transient line shape changes are observed among vibrational levels of a progression of electronically autoionizing Rydberg states leading to the excited A (2)Πu N2(+) ion core. Vibrational levels in the valence b (1)Πu state exhibit 50 fs oscillation periods, revealing superpositions between individual vibrational levels within this state. Comparisons are made to previous studies of electronic wavepackets in atoms that highlight similarities to atomic behavior yet illustrate unique contributions of the diatomic molecular structure to the wavepacket, including the influence of different electronic potentials and vibrational-level-specific electronic dynamics. PMID:26862883

  5. Ultrafast dynamics of the ns (n = 3,4) and 3d Rydberg states of O2.

    PubMed

    Peralta Conde, A; Montero, R; Ovejas, V; Fernández-Fernández, M; Castaño, F; Longarte, A

    2013-04-14

    The ultrafast dynamics of the lowest optically accessible Rydberg states of molecular oxygen (O2) has been studied by time resolved transient ionization. The process was triggered by the absorption of two pump photons in the 304 nm-220 nm range which corresponds to an energy range of 8.2 eV-11.3 eV, and probed by ionization with photons at 800 nm. From the analysis of the experimental data different time constants ranging from a few femtoseconds to hundreds of picoseconds were found. The identification of the states responsible for the measured lifetimes revealed important facts about the dynamics of the Rydberg states in this energy range, underlying the importance of the coupling between Rydberg and valence states in the relaxation mechanisms of the molecule. PMID:23435804

  6. Hydrogenic Rydberg States of Molecular van der Waals Complexes: Resolved Rydberg Spectroscopy of DABCO-N2

    NASA Astrophysics Data System (ADS)

    Cockett, Martin C.; Watkins, Mark J.

    2004-01-01

    The complementary threshold ionization techniques of MATI and ZEKE spectroscopy have been used to reveal well-resolved, long-lived (>10 μs) hydrogenic Rydberg series (50≤n≤98) in a van der Waals complex formed between a polyatomic molecule and a diatomic molecule for the first time. The series are observed within 50 cm-1 of the adiabatic ionization threshold as well as two core-excited thresholds corresponding to excitation of up to two quanta in the van der Waals vibra­tional mode.

  7. Time-resolved photoionization spectroscopy of mixed Rydberg-valence states: indole case study.

    PubMed

    Zawadzki, Magdalena M; Thompson, James O F; Burgess, Emma A; Paterson, Martin J; Townsend, Dave

    2015-10-28

    Time-resolved photoelectron imaging was used to study non-adiabatic relaxation dynamics in gas-phase indole following photo-excitation at 267 nm and 258 nm. Our data analysis was supported by various ab initio calculations using both coupled cluster and density functional methods. The highly differential energy- and angle-resolved information provided by our experimental approach provides extremely subtle details of the complex interactions occurring between several low-lying electronically excited states. In particular, new insight into the role and fate of the mixed Rydberg-valence 3s/πσ* state is revealed. This includes population residing on the excited state surface at large N-H separations for a relatively long period of time (∼1 ps) prior to dissociation and/or internal conversion. Our findings may, in part, be rationalized by considering the rapid evolution of this state's electronic character as the N-H stretching coordinate is extended - as extensively demonstrated in the supporting theory. Overall, our findings highlight a number of important general caveats regarding the nature of mixed Rydberg-valence excited states, their spectral signatures and detection sensitivity in photoionization measurements, and the evaluation of their overall importance in mediating electronic relaxation in a wide range of small model-chromophore systems providing bio-molecular analogues - a topic of considerable interest within the chemical dynamics community over the last decade. PMID:26394263

  8. Collision-based spectroscopy of Xe VI Rydberg states

    NASA Astrophysics Data System (ADS)

    Wang, M.; Larsson, M. O.; Arnesen, A.; Hallin, R.; Heijkenskjöld, F.; Nordling, C.; Wännström, A.

    1996-12-01

    The photon emission from 60-keV Xe6+ colliding with Na or Ar was recorded in the 35-800-nm wavelength region. Several of the observed lines were classified as transitions from singly excited states in Xe5+. The dipole polarizability of Xe6+ and the ionization energy of Xe5+ were determined from a fit with the polarization formula to the experimentally determined energy levels of nonpenetrating states. The analysis was assisted by Hartree-Fock calculations. All Xe5+ lines in the range 35-800 nm, reported in this work or previously, are tabulated. .

  9. Neutral atoms are entangled in hyperfine states via Rydberg blockade

    SciTech Connect

    Miller, Johanna

    2010-02-15

    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.

  10. Rydberg states of the hydrogen-antihydrogen quasimolecule

    NASA Astrophysics Data System (ADS)

    Sharipov, V.; Labzowsky, L.; Plunien, G.

    2006-05-01

    A description of the excited lepton states of the hydrogen-antihydrogen quasimolecule is presented. Potential energy curves and the leptonic part of the wave functions corresponding to a variety of such states are calculated within the Born-Oppenheimer approximation employing the Ritz variational principle. Nonadiabatic corrections to the leptonic potentials are also obtained. Basis functions are constructed as products of explicitly correlated Gaussians and spherical harmonics which describe correctly the motion of leptons with arbitrary orbital angular momentum projection onto the molecular (internuclear) axis. The hadronic part of the wave function for each leptonic level of the hydrogen-antihydrogen system is calculated by solving the Schrödinger equation with the obtained leptonic potentials. Corresponding solutions are generated utilizing precise B-spline representations. Employing leptonic and hadronic parts of the wave function the electron-positron and proton-antiproton annihilation rates are computed for a number of quasimolecular states. The decay rates of the hydrogen-antihydrogen system into separate positronium and protonium atoms are also estimated for the quasimolecular levels under consideration.

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

    NASA Astrophysics Data System (ADS)

    Pfau, Tilman

    2012-06-01

    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).

  12. Circular Rydberg States of the Hydrogen Atom in a Magnetic Field

    SciTech Connect

    Germann, T.C.; Herschbach, D.R. ); Dunn, M.; Watson, D.K. )

    1995-01-30

    Dimensional perturbation theory is used to study circular Rydberg states ([vert bar][ital m][vert bar]=[ital n][minus]1[much gt]1) and other large [vert bar][ital m][vert bar] states of the hydrogen atom in a uniform magnetic field. Because of a degeneracy between states of increased angular momentum and states of increased Cartesian dimensionality, the accuracy of the zeroth-order [ital D][r arrow][infinity] limit and a dimensional perturbation expansion improves significantly for states with larger [vert bar][ital m][vert bar]. In contrast to other approaches, this method is applicable to the entire range of magnetic field strengths. Energies and expectation values are presented as functions of the field strength.

  13. Combined theoretical and experimental study of the valence, Rydberg, and ionic states of chlorobenzene

    NASA Astrophysics Data System (ADS)

    Palmer, Michael H.; Ridley, Trevor; Vrønning Hoffmann, Søren; Jones, Nykola C.; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Zhang, Teng; Biczysko, Malgorzata; Baiardi, Alberto; Peterson, Kirk A.

    2016-03-01

    New photoelectron (PE) and ultra violet (UV) and vacuum UV (VUV) spectra have been obtained for chlorobenzene by synchrotron study with higher sensitivity and resolution than previous work and are subjected to detailed analysis. In addition, we report on the mass-resolved (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of a jet-cooled sample. Both the VUV and REMPI spectra have enabled identification of a considerable number of Rydberg states for the first time. The use of ab initio calculations, which include both multi-reference multi-root doubles and singles configuration interaction (MRD-CI) and time dependent density functional theoretical (TDDFT) methods, has led to major advances in interpretation of the vibrational structure of the ionic and electronically excited states. Franck-Condon (FC) analyses of the PE spectra, including both hot and cold bands, indicate much more complex envelopes than previously thought. The sequence of ionic states can be best interpreted by our multi-configuration self-consistent field computations and also by comparison of the calculated vibrational structure of the B and C ionic states with experiment; these conclusions suggest that the leading sequence is the same as that of iodobenzene and bromobenzene, namely: X2B1(3b1-1) < A2A2(1a2-1) < B2B2(6b2-1) < C2B1(2b1-1). The absorption onset near 4.6 eV has been investigated using MRD-CI and TDDFT calculations; the principal component of this band is 1B2 and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. The other low-lying absorption band near 5.8 eV is dominated by a 1A1 state, but an underlying weak 1B1 state (πσ∗) is also found. The strongest band in the VUV spectrum near 6.7 eV is poorly resolved and is analyzed in terms of two ππ∗ states of 1A1 (higher oscillator strength) and 1B2 (lower oscillator strength) symmetries, respectively. The calculated vertical excitation energies of these two states are critically dependent upon the presence of Rydberg functions in the basis set, since both manifolds are strongly perturbed by the Rydberg states in this energy range. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene and bromobenzene.

  14. Combined theoretical and experimental study of the valence, Rydberg, and ionic states of chlorobenzene.

    PubMed

    Palmer, Michael H; Ridley, Trevor; Vrønning Hoffmann, Søren; Jones, Nykola C; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Zhang, Teng; Biczysko, Malgorzata; Baiardi, Alberto; Peterson, Kirk A

    2016-03-28

    New photoelectron (PE) and ultra violet (UV) and vacuum UV (VUV) spectra have been obtained for chlorobenzene by synchrotron study with higher sensitivity and resolution than previous work and are subjected to detailed analysis. In addition, we report on the mass-resolved (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of a jet-cooled sample. Both the VUV and REMPI spectra have enabled identification of a considerable number of Rydberg states for the first time. The use of ab initio calculations, which include both multi-reference multi-root doubles and singles configuration interaction (MRD-CI) and time dependent density functional theoretical (TDDFT) methods, has led to major advances in interpretation of the vibrational structure of the ionic and electronically excited states. Franck-Condon (FC) analyses of the PE spectra, including both hot and cold bands, indicate much more complex envelopes than previously thought. The sequence of ionic states can be best interpreted by our multi-configuration self-consistent field computations and also by comparison of the calculated vibrational structure of the B and C ionic states with experiment; these conclusions suggest that the leading sequence is the same as that of iodobenzene and bromobenzene, namely: X(2)B1(3b1 (-1)) < A(2)A2(1a2 (-1)) < B(2)B2(6b2 (-1)) < C(2)B1(2b1 (-1)). The absorption onset near 4.6 eV has been investigated using MRD-CI and TDDFT calculations; the principal component of this band is (1)B2 and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. The other low-lying absorption band near 5.8 eV is dominated by a (1)A1 state, but an underlying weak (1)B1 state (πσ(∗)) is also found. The strongest band in the VUV spectrum near 6.7 eV is poorly resolved and is analyzed in terms of two ππ(∗) states of (1)A1 (higher oscillator strength) and (1)B2 (lower oscillator strength) symmetries, respectively. The calculated vertical excitation energies of these two states are critically dependent upon the presence of Rydberg functions in the basis set, since both manifolds are strongly perturbed by the Rydberg states in this energy range. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene and bromobenzene. PMID:27036443

  15. Information and entanglement measures applied to the analysis of complexity in doubly excited states of helium

    NASA Astrophysics Data System (ADS)

    Restrepo Cuartas, J. P.; Sanz-Vicario, J. L.

    2015-05-01

    Shannon entropy and Fisher information calculated from one-particle density distributions and von Neumann and linear entropies (the latter two as measures of entanglement) computed from the reduced one-particle density matrix are analyzed for the S e 1 ,3 ,P o 1 ,3 , and D e 1 ,3 Rydberg series of He doubly excited states below the second ionization threshold. In contrast with the Shannon entropy, we find that both the Fisher information and entanglement measures are able to discriminate low-energy resonances pertaining to different (K ,T ) n2A 2 series according to the Herrick-Sinanoğlu-Lin classification. Contrary to bound states, which show a clear and unique asymptotic value for both Fisher information and entanglement measures in their Rydberg series 1 s n ℓ for n →∞ (which implies a loss of spatial entanglement), the variety of behaviors and asymptotic values of entanglement above the noninteracting limit value in the Rydberg series of doubly excited states (K ,T ) n2A 2 indicates a signature of the intrinsic complexity and remnant entanglement in these high-lying resonances even with infinite excitation n2→∞ , for which all known attempts of resonance classifications fail in helium.

  16. Laser-induced optical activity in range of Rydberg autoionizing states of xenon

    NASA Astrophysics Data System (ADS)

    Gryzlova, E. V.; Grum-Grzhimailo, A. N.; Magunov, A. I.; Strakhova, S. I.

    2010-07-01

    Optical activity of xenon atoms in the vacuum UV range induced by circularly polarized laser light is studied theoretically. The optical activity arises in the vicinity of the autoionizing state 5 p 5(2 P 1/2)8 s' left[ {frac{1} {2}} right]_1 as a result of its coupling via the laser field with the discrete state 5 p 5(2 P 3/2)7 p left[ {frac{1} {2}} right]_1 . Polarization variations of the vacuum UV radiation upon its propagation through the atomic medium are calculated, and the possibility of controlling this polarization is discussed. Manifestations of nonresonant coupling of the discrete state with the broad autoionizing state 5 p 5(2 P 1/2)6 d' left[ {frac{1} {2}} right]_1 induced by the overlap of the Rydberg autoionizing series in xenon are studied.

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

    PubMed

    Mason, Rod S; Douglas, Peter

    2010-04-21

    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

  18. Applications of the modified Rydberg-Vinet equation-of-state to the lower mantle and core

    NASA Astrophysics Data System (ADS)

    Fang, Zheng-Hua

    2016-01-01

    A modified Rydberg-Vinet equation-of-state (mRV EOS) with an arbitrary nonzero-pressure reference point, as is derived strictly from the related Rydberg potential, has been applied to the mantle and the core. The tests and comparisons demonstrate that mRV EOS is superior to the reciprocal K-primed equation [see F. D. Stacey and P. M. Davis, Phys. Earth Planet. Inter. 142 (2004) 137] not only because of its higher fitting accuracy but also because it has fewer fitting parameters and is easier to use.

  19. Effect of tunneling on ionization of Rydberg states in intense fields: Hydrogenic atoms

    SciTech Connect

    Cohen, James S.

    2003-09-01

    The ionization probabilities of hydrogenic Rydberg states in intense fields are calculated using a trajectory method, which was previously shown to be accurate for ionization of the ground-state hydrogen atom [J. S. Cohen, Phys. Rev. A 64, 043412 (2001)]. It is found that the ionization probability approaches the classical over-the-barrier probability for sufficiently large n quantum numbers, but that tunneling still significantly decreases the onset field strengths at surprisingly high n. Calculations are done for ns, np{sub 0}, and np{sub {+-}} targets, subjected to sudden and adiabatically ramped pulses in the long-wavelength limit. The dependence on the angular-momentum projection m along the field axis is also examined for circular orbi0008.

  20. Excitation of high orbital angular momentum Rydberg states with Laguerre-Gauss beams

    NASA Astrophysics Data System (ADS)

    Rodrigues, J. D.; Marcassa, L. G.; Mendonça, J. T.

    2016-04-01

    We consider the excitation of Rydberg states through photons carrying an intrinsic orbital angular momentum degree of freedom. Laguerre-Gauss modes, with a helical wave-front structure, correspond to such a set of laser beams, which carry {{\\ell }}0 units of orbital angular momentum in their propagation direction, with ℓ 0 the winding number. We demonstrate that, in a proper geometry setting, this orbital angular momentum can be transferred to the internal degrees of freedom of the atoms, thus violating the standard dipole selection rules. Higher orbital angular momentum states become accessible through a single photon excitation process. We investigate how the spacial structure of the Laguerre-Gauss beam affects the radial coupling strength, assuming the simplest case of hydrogen-like wavefunctions. Finally we discuss a generalization of the angular momentum coupling, in order to include the effects of the fine and hyperfine splitting, in the context of the Wigner-Eckart theorem.

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

    SciTech Connect

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

    2014-12-21

    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.

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

    PubMed

    Gudmundsdttir, Hildur; Zhang, Yao; Weber, Peter M; Jnsson, Hannes

    2014-12-21

    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 , 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 . 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. PMID:25527936

  3. The effect of nonpolar solvents on Rydberg states: van der Waals complexes of azabicyclooctanes

    NASA Astrophysics Data System (ADS)

    Shang, Q. Y.; Moreno, P. O.; Dion, C.; Bernstein, E. R.

    1993-05-01

    The effect of solvation by nonpolar solvents on the (n,3s) Rydberg states of 1,4-diazabicyclo[2.2.2]octane (DABCO) and azabicyclo[2.2.2]octane (ABCO) is investigated through mass resolved excitation spectroscopy of their van der Waals complexes. The solute/solvent clusters formed in a supersonic expansion include DABCO and ABCO with Ar, n-CmH2m+2 (m=1-7), and CF4 and C2F6. The resulting spectra are analyzed with the help of empirical potential energy calculations of the cluster binding energies, minimum energy structures, van der Waals modes, and potential barriers between the various cluster minimum energy structures. Good agreement is found between the calculated and experimental results for DABCO and ABCO clustered with argon and methane. The spectra of clusters with all other hydrocarbons can be ascribed to only one major geometry for each cluster stoichiometry, despite the fact that calculations yield many stable geometries for each cluster. This apparent lack of agreement between calculations and experiments can be rationalized based on cluster binding energy, zero point energy, and the potential energy barriers between the cluster minima. The observed blue shift of the cluster 000 transition energy as a function of the n-alkane chain length can be qualitatively modeled by a Lennard-Jones potential for the solute-solvent interaction for both the ground and excited states. The model reveals a strong repulsive interaction between the Rydberg state electronic distribution and the solvent molecule. This repulsion depends on the distance between the solvent molecule and the solute molecule nitrogen atom.

  4. Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

    NASA Astrophysics Data System (ADS)

    Mihajlov, A. A.; Srećković, V. A.; Ignjatović, Lj. M.; Klyucharev, A. N.; Dimitrijević, M. S.; Sakan, N. M.

    2015-12-01

    In our previous research, it has been demonstrated that inelastic processes in atom Rydberg-atom collisions, such as chemi-ionization and ( n- n') mixing, should be considered together. Here we will review the present state-of-the-art and the actual problems. In this context, we will consider the influence of the ( n- n')-mixing during a symmetric atom Rydberg-atom collision processes on the intensity of chemi-ionization process. It will be taken into account H(1s) + H ∗( n) collisional systems, where the principal quantum number is n>> 1. It will be demonstrated that the inclusion of ( n- n') mixing in the calculation, influences significantly on the values of chemi-ionization rate coefficients, particularly in the lower part of the block of the Rydberg states. Different possible channels of the ( n- n')-mixing influence on chemi-ionization rate coefficients will be demonstrated. The possibility of interpretation of the ( n- n')-mixing influence will be considered on the basis of two existing methods for describing the inelastic processes in symmetrical atom Rydberg-atom collisions.

  5. Blackbody-radiation-induced shifts and the broadening of Rydberg states in the ions of group IIa elements

    NASA Astrophysics Data System (ADS)

    Glukhov, I. L.; Nikitina, E. A.; Ovsiannikov, V. D.

    2016-02-01

    The rates of blackbody-radiation(BBR)-induced transitions from excited nS, nP, nD and nF states into bound states and into continua of the group IIa ions Ca+, Sr+, Ba+ at temperatures from T = 100 K to T = 3000 K are calculated in consecutive comparison of the Fues model potential (FMP) with quantum defect method (QDM). The temperature and binding-energy dependencies are determined and analytical asymptotic approximations are proposed for evaluating numerically the contributions of the bound states and continua to the Rydberg-level widths and positions. The general properties of n-dependence at the threshold and regularities of above-threshold ionization cross sections for states with high principal quantum numbers n are used for determining the rates of BBR-induced ionization. Relations are determined between deviations from general regularities for the sum rules of oscillator- strengths and specific non-local dependence of the FMP on optical-electron angular momentum. The QDM appears preferable in comparison with the FMP approach for calculating the amplitudes of radiation transitions from Rydberg states, and specifically sums of matrix-element-dependent terms over very large (in particular, infinite) numbers of discrete states. The fractional (related to natural decay) rates of BBR-induced decay into lower bound states, excitation into upper bound states and ionization transitions into the continuum are presented asymptotically with parameters tabulated for the S, P, D and F Rydberg states.

  6. Fractional Quantum Hall Effect of lossy Rydberg Dark-State Polaritons

    NASA Astrophysics Data System (ADS)

    Grusdt, Fabian; Fleischhauer, Michael; Höning, Michael; Otterbach, Johannes

    2012-06-01

    Dark-state-polaritons (DSP) are bosonic quasiparticles arising in the interaction of light with 3-level atoms under conditions of electromagnetically induced transparency (EIT). When exposed to a strong artificial magnetic field, they can enter the lowest Landau level regime. With additional long range interactions, as realized e.g. when the 3-level atom contains a Rydberg-excited state, DSPs are natural candidates for a realization of the bosonic fractional quantum Hall effect. Besides their high controllability, they offer the possibility to examine open quantum Hall systems. We show how highly-correlated quantum Hall states of DSPs can be prepared, making use of nonlinear polariton losses. The possibility of realizing these states as stationary states of open systems is investigated. We propose a realistic quantum-optical setup, and show that different fractional quantum Hall states can be prepared, manipulated and observed. Numerical and analytical results for the excitation gaps of the ν=1/2p Laughlin states are presented.

  7. Rydberg, Valence and Ion-Pair Quintet States of O_2

    NASA Astrophysics Data System (ADS)

    Vazquez, Gabriel J.; Liebermann, Hans P.; Lefebvre-Brion, H.

    2015-06-01

    We carried out a relatively comprehensive ab--initio study of the electronic structure of O_2 and O_2^+. We employed the MRD--CI package together with the cc--pV4Z basis set augmented with seven diffuse functions of s, p and d character on each atom. In this contribution we focus on the quintet states. Potential energy curves of about 50 quintet states were computed. The spectroscopic constants of the six valence quintet states (^5σ^+_g, ^5σ^-_g, ^5σ^-_u, ^5Π_u, ^5Π_g, ^5Δ_g) dissociating to the first dissociation limit O(^3P)+O(^3P) are reported. The four ion--pair quintet states (^5σ^-_g, ^5σ^-_u, ^5Π_g, ^5Π_u) dissociating into O^+(^4S)+O^-(^2P) at 17.28 eV were also computed and their spectroscopic constants will be presented. A number of bound quintet Rydberg states belonging to series converging to the a^4Π_u, b^4σ^-_g, f^4Π_g and ^6σ^+_u states of the O_2^+ cation were identified and attributed. Long--range interactions involving the ion--pair states as they slowly approach their dissociation limit will be shown.

  8. Multireference configuration interaction studies on higher valence and Rydberg states of OClO, ionization potentials, and electron detachment energies

    NASA Astrophysics Data System (ADS)

    Grein, Friedrich

    2011-07-01

    MRCI results are reported for the vertical excitation energies (VEE) and oscillator strengths f of doublet states of OClO up to 11 eV, including 3b1 ? 4s, 4p, 3d, 5s, 5p, 4d, and most 1a2, 8a1, 5b2 ? 4s and 4p Rydberg states. The lowest Rydberg states 3b1 ? 4s and 3b1 ? 4px have mixed valence-Rydberg character. The observed spectral bands were reassigned to include valence states which have generally higher oscillator strengths. The well-known valence state 12A2 has a VEE of 3.63 eV, and a relatively high f of 0.042. Overall, the calculated oscillator strengths are in good agreement with measured values. The lowest quartet state, 14B2, lies at 6.95 eV. Quartet Rydberg states start with 1a2 ? 4s at 9.28 eV. According to calculated vertical ionization potentials (VIP) of OClO, the second VIP at 12.59 eV is reassigned from 13B1 to 13B2 (ionization from 1a2, rather than 8a1), and the third VIP at 12.63 eV from 11B1 to 13B1 (ionization from 8a1). Vertical electron detachment energies of OClO- have been calculated up to 8.9 eV. There is good agreement with experimental values.

  9. Multireference configuration interaction studies on higher valence and Rydberg states of OClO, ionization potentials, and electron detachment energies.

    PubMed

    Grein, Friedrich

    2011-07-28

    MRCI results are reported for the vertical excitation energies (VEE) and oscillator strengths f of doublet states of OClO up to 11 eV, including 3b(1) ? 4s, 4p, 3d, 5s, 5p, 4d, and most 1a(2), 8a(1), 5b(2) ? 4s and 4p Rydberg states. The lowest Rydberg states 3b(1) ? 4s and 3b(1) ? 4p(x) have mixed valence-Rydberg character. The observed spectral bands were reassigned to include valence states which have generally higher oscillator strengths. The well-known valence state 1(2)A(2) has a VEE of 3.63 eV, and a relatively high f of 0.042. Overall, the calculated oscillator strengths are in good agreement with measured values. The lowest quartet state, 1(4)B(2), lies at 6.95 eV. Quartet Rydberg states start with 1a(2) ? 4s at 9.28 eV. According to calculated vertical ionization potentials (VIP) of OClO, the second VIP at 12.59 eV is reassigned from 1(3)B(1) to 1(3)B(2) (ionization from 1a(2), rather than 8a(1)), and the third VIP at 12.63 eV from 1(1)B(1) to 1(3)B(1) (ionization from 8a(1)). Vertical electron detachment energies of OClO(-) have been calculated up to 8.9 eV. There is good agreement with experimental values. PMID:21806116

  10. Atomic orientation following predissociation of the C 3Πg Rydberg state of molecular oxygen

    NASA Astrophysics Data System (ADS)

    Gilchrist, A. J.; Ritchie, G. A. D.

    2013-06-01

    (2 + 1) resonance enhanced multiphoton ionization in combination with time-of-flight mass spectroscopy (TOF-MS) has been used to detect both the O(3P) and O(1D) fragments produced as a result of predissociation of the C 3Πg (v = 0) and (v = 1) Rydberg states of O2, accessed via two-photon absorption from the ground X ^3Σ -g 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.

  11. Atomic orientation following predissociation of the C 3Πg Rydberg state of molecular oxygen.

    PubMed

    Gilchrist, A J; Ritchie, G A D

    2013-06-01

    (2 + 1) resonance enhanced multiphoton ionization in combination with time-of-flight mass spectroscopy (TOF-MS) has been used to detect both the O((3)P) and O((1)D) fragments produced as a result of predissociation of the C (3)Πg (v = 0) and (v = 1) Rydberg states of O2, accessed via two-photon absorption from the ground X (3)Σg(-) 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. PMID:23758371

  12. Long lifetimes of high molecular Rydberg states in crossed magnetic and electric fields: An experimental and classical computational study

    NASA Astrophysics Data System (ADS)

    Mühlpfordt, Annette; Even, U.; Rabani, Eran; Levine, R. D.

    1995-05-01

    Crossed magnetic and electric fields are observed to extend the lifetime of high molecular Rydberg states of DABCO (1,4-Diazabicyclo[2.2.2]octane) well into the microsecond range. The experimental and computational (using classical mechanics and for a diatomic polar core) results agree both on the magnitude of the effect and on its decrease with increasing electrical field. Theoretical considerations suggest that this time-stretching effect is only present for high Rydberg states and/or for not too weak fields. The computed lifetime increases as the magnetic-field strength is decreased but it requires a finite magnetic field for the onset of the effect. The experimental technique of detection of the surviving Rydberg states via their ionization in a delayed field pulse (known as ZEKE spectroscopy) is most easily implemented for high (say, n>100) but not too high (n<400) Rydberg states. In this regime, the magnetic field required for the additional time stretching is larger than that due to the earth but can be significantly weaker than that required to induce extensive chaotic behavior. The results of the numerically exact classical simulations are interpreted using equations of motion, cast in the form of a mapping, which retain terms up to second order in the fields. (The first-order terms are qualitatively and quantitatively not, by themselves, sufficient.) As is to be expected on physical grounds, the origin of the effect is the slow, periodic modulation of the magnitude of the magnetic quantum number ml of the electron due to terms second order in the magnetic field. Since the angular momentum l of the electron is bounded from below by ml, and since it requires a low l for the electron to couple effectively to the molecular core, the presence of the magnetic field provides for an elongation of the time scale which is over and above that made possible due to the periodic motion of l due to the dc electric field.

  13. Velocity-selective electromagnetically-induced-transparency measurements of potassium Rydberg states

    NASA Astrophysics Data System (ADS)

    Xu, Wenchao; DeMarco, Brian

    2016-01-01

    We demonstrate a velocity selection scheme that mitigates suppression of electromagnetically induced transparency (EIT) by Doppler shifts for coupling wavelengths larger than the probe wavelength. An optical pumping beam counterpropagating with the EIT probe beam transfers atoms between hyperfine states in a velocity-selective fashion. Measurement of the transmitted probe beam synchronous with chopping of the optical pumping beam enables a Doppler-free EIT signal to be detected. Transition frequencies between 5 P1 /2 and n S1 /2 states for n =26 , 27, and 28 in 39K are obtained via EIT spectroscopy in a heated vapor cell with a probe beam stabilized to the 4 S1 /2→5 P1 /2 transition. Using previous high-resolution measurements of the 4 S1 /2→n S1 /2 transitions, we make a determination of the absolute frequency of the 4 S1 /2→5 P1 /2 transition. Our measurement is shifted by 560 MHz from the currently accepted value with a twofold improvement in uncertainty. These measurements will enable novel experiments with Rydberg-dressed ultracold Fermi gases composed of 40K atoms.

  14. Polarizabilites and Rydberg States in the Presence of a Debye Potential

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Drachman, Richard J.

    2010-01-01

    Polarizabilities and hyperpolarizabilities, alpha(1), beta(1),gamma(1), alpha(2), beta(2),gamma(2), alpha(3), beta(3),gamma(3), delta and epsilon of hydrogenic systems have been calculated by Drachman. We have now calculated these quantities by using pseudostates for the S. P. D and F states. All of them converge very fast as the number of terms in the pseudostates is increased, and are essentially independent of the nonlinear parameters. All the results are in good agreement with the results obtained by Drachman. except for delta, which is of the third-order in perturbation formalism. We have calculated Rydberg states of He for high N and L. The effective potential is -alpha(sub 1)/x(exp 4)+{6 * Beta(sub 1) -alpha(sub 2)/x(exp6), where x is the distance of the outer electron from the nucleus. The exchange and electron-electron correlations are unimportant because the outer electron is far away from the nucleus. This implies that the conventional variational calculations are not necessary. The results agree well with the results of Drachman. We have generalized this approach in the presence of a Debye potential.

  15. Rydberg state, metastable, and electron dynamics in the low-pressure argon afterglow

    NASA Astrophysics Data System (ADS)

    Tsankov, Tsanko V.; Johnsen, Rainer; Czarnetzki, Uwe

    2015-12-01

    In this work a time-dependent collisional-radiative model for recombining plasmas is developed. It tracks the collisional and radiative capture of electrons into highly-excited (Rydberg) states and their consecutive deexcitation through collisions and radiation to the ground or the metastable state. The model allows the calculation of the net recombination rate and the electron energy gain by recombination. It is coupled to the volume-averaged balance equations for the electron density and temperature. The numerical solution of these equations includes a model for the diffusion cooling of the electrons (Celik et al 2012 Phys. Rev. E 85 046407) and a simplified model for the gas cooling. Using as only input the experimentally determined initial values of the electron density and temperature, gas temperature and metastable density, the temporal evolution of all parameters in the afterglow is calculated and compared with measurements. The results reproduce very well the measured quantities (electron density, light emission and metastable density) without the need to invoke adjustable parameters. This gives confidence in the validity of the model that allows it to be used not only to deepen the understanding of afterglow plasmas but also to tailor their properties as required for applications. The analysis of the model results further shows that gas heating and cooling must be explicitly taken into account to reproduce experimental observations. The electron heating by recombination is another process that is important for the good agreement. Both of these effects were largely ignored in previous works on afterglows.

  16. Far infrared stimulated emission from the ns and nf Rydberg states of NO

    SciTech Connect

    Furukawa, Hiroki; Araki, Mitsunori; Umeki, Hiroya; Tsukiyama, Koichi

    2013-06-28

    We report directional far-infrared emission from the {upsilon}= 0 vibrational levels of the 9s{sigma}, 10s{sigma}, 11s{sigma}, 9f, and 10f Rydberg states of NO in the gas phase. The emission around 28 and 19 {mu}m from the 9f state was identified as the downward 9f{yields} 8g and subsequent 8g{yields} 7f cascade transitions, respectively. The emission around 38 and 40 {mu}m from the 10f state was identified as the 10f{yields} 9g and 10f{yields} 9d{sigma}{pi} transition, respectively. Following the excitation of the 9s{sigma}, 10s{sigma}, and 11s{sigma} states, the emission around 40, 60, and 83 {mu}m was assigned as the 9s{sigma}{yields} 8p{sigma}, 10s{sigma}{yields} 9p{sigma}, and 11s{sigma}{yields} 10p{sigma} transitions, respectively. In addition to these emission systems originated from the laser-prepared levels, we found the emission bands from the 8f, 9f, and 10f states which are located energetically above the 9s{sigma}, 10s{sigma}, and 11s{sigma} states, respectively. This observation suggests that the upward 8f Leftwards-Arrow 9s{sigma}, 9f Leftwards-Arrow 10s{sigma}, and 10f Leftwards-Arrow 11s{sigma} optical excitation occurs. Since the energy differences between nf and (n+ 1)s{sigma} states correspond to the wavelength longer than 100 {mu}m, the absorption of blackbody radiation is supposed to be essential for these upward transitions.

  17. Resonance-enhanced multiphoton-ionization photoelectron spectroscopy of even-parity autoionizing Rydberg states of atomic sulphur

    NASA Astrophysics Data System (ADS)

    Woutersen, S.; Milan, J. B.; Buma, W. J.; de Lange, C. A.

    1997-05-01

    Several previously unobserved Rydberg states of the sulphur atom above the lowest ionization threshold are identified and assigned using (2+1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy. All states were accessed by two-photon transitions from either the 3P ground or the 1D excited state, prepared by in situ photodissociation of H2S. The observed states derive from the (2Do)5p and (2Po)4p configurations. For the (2Do)5p 3F and (2Po)4p 3D triplets, extensive photoelectron spectroscopic studies enable a detailed comparison of the autoionization and photoionization rates of these states.

  18. Experiment at NIST to produce one-electron ions in circular Rydberg states

    NASA Astrophysics Data System (ADS)

    Tan, Joseph; Brewer, Samuel; Guise, Nicholas

    2011-05-01

    Highly charged ions, including bare nuclei, produced in the NIST EBIT (electron beam ion trap) are extracted and captured in the simplest Penning trap that can be configured with a single neodymium (NdFeB) magnet. Slowing and capture of bare nuclei is a step towards formation and study of one-electron ions within the well-controlled environment of a Penning or Paul trap. Detailed laser spectroscopy of hydrogen-like ions in circular Rydberg states would potentially provide a test of theory in a regime with completely negligible nuclear- size corrections. Such a test is of particular interest in the wake of the large discrepancy in proton radius determinations that resulted from the muonic hydrogen Lamb-shift measurements. We discuss some experiments with captured ions planned in a more elaborate apparatus configured with a two-neomagnet (NdFeB) Penning trap for better magnetic field homogeneity, an electron gun for in-trap loading of low- Z ions, and optical access for spectroscopy experiments with low-energy, highly-charged ions. N. Guise, S.M. Brewer and J.N. Tan, oral presentation at this meeting

  19. Electromagnetically induced transparency in a Y system with single Rydberg state

    NASA Astrophysics Data System (ADS)

    Tian, Xue-Dong; Liu, Yi-Mou; Yan, Xiao-Bo; Cui, Cui-Li; Zhang, Yan

    2015-06-01

    We study the transmitted intensity and correlation properties of a probe field propagating through a sample of cold interacting 87Rb atoms driven into the Y level configuration with single Rydberg state. We find two electromagnetically induced transparency (EIT) windows in the transmission spectrum. One window is linear since it is immune to the incident probe field. The other window depth is sensitive to the incident probe intensity, exhibiting cooperative nonlinearity. Meanwhile, the linear window is low but the transmissivity at the nonlinear window can reach nearly 100% in case of the weak probe intensity. When two EIT windows overlap, the cooperative optical nonlinearity plays a leading role in the degenerate window. In addition, the probe propagation is affected by its two-photon correlation which is suppressed at the center of nonlinear window and is enhanced near the boundaries of two windows. The two-photon correlation is also sensitive to the probe field, and that means we can attain the strongest photon bunching (anti-bunching) effect by controlling the probe and coupling fields.

  20. Electronic Structure of the X {^1σ^+} Ion Core of CaF Rydberg States

    NASA Astrophysics Data System (ADS)

    Coy, Stephen; Baraban, Joshua H.; Grimes, David; Barnum, Timothy J.; Field, Robert W.; Wong, Bryan M.

    2015-06-01

    We use ab-initio calculations to examine the electronic structure of CaF{^+},making comparison to the available experimental data and effective potential models. An electron-density-difference plot comparing isolated Ca{+2} and F{^-} ions with the CaF{^+} ab-initio density shows s-d mixing at Ca, and maintenance of near spherical symmetry at F. This unexpected result is interpreted in terms of the electronic states of Ca{^+}. Calculation of the effective charge on F spanning the region of the transition from ionic to dissociating Ca{^+} F{^0} locates the transition very near the crossing of the Ca{+2} F{^-} and Ca{^+} F{^0} curves and additionally determines the width of the ionic-bonding transition region. An accurate non-relativistic long or intermediate range effective potential for the CaF Rydberg electron is obtained by choice of origin at the center of polarizability, with inclusion of multipoles through octopole and the use of anisotropic polarizability. The estimates of CaF{^+} polarizability from ab-initio and effective potential models predict high anisotropy, with the parallel dipole polarizability, where the atomic dipoles are mutually enhancing, predicted to be about double the perpendicular polarizability, where the atomic dipoles are mutually antagonistic.

  1. Quantum defect description of H[sub 3] Rydberg state dynamics

    SciTech Connect

    Stephens, J.A.; Greene, C.H. )

    1994-03-14

    We develop a multichannel quantum defect formulation to describe the collision of a Rydberg or continuum electron with a vibrating and rotating polyatomic ion. We formulate a full rovibronic frame transformation which accounts simultaneously for vibrationally and rotationally inelastic collisions (preionization) and [ital l] uncoupling. Interactions among degenerate Rydberg series, arising from Jahn-Teller disortions of molecular geometry, play an important role in the formulation. An application to the 1[ital s][sup 2]3[ital sA][sub 1][sup [prime

  2. Laser diagnostics of the energy spectrum of Rydberg states of the lithium-7 atom

    SciTech Connect

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

    2015-12-15

    The spectra of excited lithium-7 atoms prepared in a magneto-optical trap are studied using a UV laser. The laser diagnostics of the energy of Rydberg atoms is developed based on measurements of the change in resonance fluorescence intensity of ultracold atoms as the exciting UV radiation frequency passes through the Rydberg transition frequency. The energies of various nS configurations are obtained in a broad range of the principal quantum number n from 38 to 165. The values of the quantum defect and ionization energy obtained in experiments and predicted theoretically are discussed.

  3. Rydberg atom spectroscopy enabled by blackbody radiation ionization

    SciTech Connect

    Lu Xiaoxu; Sun Yuan; Metcalf, Harold

    2011-09-15

    We have excited helium atoms from their metastable 2 {sup 3} S state to Rydberg states in the range 13state using light at {lambda}=389 nm and 785-815 nm. Atoms in a thermal beam (100 K) cross partially overlapping laser beams of the appropriate frequencies in the counterintuitive order to exploit the high efficiency of stimulated rapid adiabatic passage. The interaction region is between two plates that can be used for Stark tuning in a few V/cm field or for field ionization. At fields much too low for field ionization, we observe signals attributed to ionization by blackbody radiation. Multiple tests confirm this attribution as the cause of ionization. For example, by heating the plates we observe the expected signal increases. Our experiments reinforce previous work where the interaction between Rydberg atoms and room temperature blackbody radiation is important for experiments.

  4. Extensive double-excitation states in atomic helium

    SciTech Connect

    Domke, M.; Xue, C.; Puschmann, A.; Mandel, T.; Hudson, E.; Shirley, D.A.; Kaindl, G. ); Greene, C.H.; Sadeghpour, H.R. ); Petersen, H. GmbH, D-1000 Berlin 33 )

    1991-03-11

    High-resolution photoionization studies of He have revealed more than 50 states below the {ital N}=2--7 thresholds of He{sup +}, including sixteen ({ital sp},2{ital n}+) and five ({ital sp},2{ital n}{minus}) states in the {ital N}=2 series. With a resolving power of {ital E}/{Delta}{ital E}{congruent}10 000, states as narrow as 0.1 meV could be observed and linewidths were determined with an accuracy up to {plus minus}0.5 meV. Interchannel interferences, evident through effects on positions, shapes, and intensities of Rydberg lines, were interpreted within the framework of the multichannel quantum-defect theory.

  5. Spectroscopic signatures of dressed Rydberg-Rydberg interactions in Sr

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rick; Hazzard, Kaden

    2015-05-01

    Ultracold Rydberg-dressed atoms exhibit strong, long-range interactions that can potentially create exotic phases of matter and entangled states that are useful in quantum computation and metrology. Rydberg-dressed atoms are obtained by off-resonantly admixing a Rydberg state | R > into a long-lived electronic state, often the ground state. As a tool to observe dressed Rydberg interactions, we theoretically consider a spectroscopic method that relies on strontium's unique long-lived (~ 23 μ s) electronic excited state 3P1. Specifically, we consider an effective two level system: the electronic ground state | G > and the Rydberg dressed state | D > = | 3 P1 > + ɛ | R > with ɛ << 1 . Using spin language to describe this two level system, our proposed Ramsey scheme rotates the spins by angle θ, allows the atoms to interact for a time t, and then measures the final spin vector. Our calculation is exact and includes experimental complications, such as dissipation and pulse timing errors. Excitingly, the dependence of the spin vector on time and θ can be used to experimentally measure the strength and power law dependence of the dressed Rydberg atom interaction.

  6. Resonance-enhanced multiphoton-ionization photoelectron spectroscopy of even-parity Rydberg states of atomic sulfur

    NASA Astrophysics Data System (ADS)

    Woutersen, S.; Milan, J. B.; Buma, W. J.; de Lange, C. A.

    1996-12-01

    A (2+1) resonance-enhanced multiphoton-ionization photoelectron spectroscopy study of the sulfur atom was performed in the one-photon energy region between 260 and 240 nm. Some 20 previously unobserved even-parity Rydberg states of the sulfur atom are reported, which were accessed by two-photon transitions from the 3P ground state of the atom, prepared by in situ photodissociation of H2S. The (4So)np 3P series could be followed up to n=25. This series is perturbed around n=7 by an interloping Rydberg state converging to the first excited ionic limit 2Do. A two-channel quantum defect theory analysis was performed in order to estimate the composition of the wave functions of the perturbed series members, which is compared with the ionic state branching ratios obtained from photoelectron spectra. This analysis, moreover, enabled the determination of the ionization energy of the lowest ionic state 4So with an improved accuracy as compared to the previously reported value.

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

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2006-01-01

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

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

    SciTech Connect

    Kalemos, Apostolos; Prosmiti, Rita

    2014-09-14

    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}.

  9. Rotationally resolved spectroscopy and dynamics of the 3p(x) (1)A(2) Rydberg state of formaldehyde.

    PubMed

    Meisinger, M; Schulenburg, A M; Merkt, F; Radi, P P

    2010-12-28

    The rotational structure of the lowest three vibrational levels (0(0), 6(1) and 4(1)) of the 3p(x) (1)A(2) Rydberg state of formaldehyde has been studied by doubly-resonant three-photon ionization spectroscopy. A strong a-type Coriolis interaction between the in-plane rocking (ν(6)) and out-of-plane bending (ν(4)) modes results in the observation of vibronically forbidden transitions to the 6(1) level from the intermediate Ã(1)A(2) (2(1) 4(3)) level. The full widths at half maximum of the rovibronic transitions to the 4(1) state are considerably larger than to the vibrational ground state and the 6(1) level. The band origin (T(0) = 67 728.939(82) cm(-1)), the rigid rotor rotational constants (A = 9.006(19) cm(-1), B = 1.331(20) cm(-1), and C = 1.135(22) cm(-1)), the Coriolis coupling constant (ξ = 8.86(89) cm(-1)) and the deperturbed fundamental wave numbers of both vibrational modes (v[combining tilde](6) = 808.88(25) cm(-1) and v[combining tilde](4) = 984.92(26) cm(-1)) have been determined for the 3p(x) (1)A(2) Rydberg state. Polarization effects originating from the double-resonance technique have been exploited to detect the Coriolis interaction and investigate how it affects the predissociation dynamics. PMID:20733971

  10. Fano resonances observed in helium nanodroplets

    NASA Astrophysics Data System (ADS)

    LaForge, A. C.; Regina, D.; Jabbari, G.; Gokhberg, K.; Kryzhevoi, N. V.; Krishnan, S. R.; Hess, M.; O'Keeffe, P.; Ciavardini, A.; Prince, K. C.; Richter, R.; Stienkemeier, F.; Cederbaum, L. S.; Pfeifer, T.; Moshammer, R.; Mudrich, M.

    2016-05-01

    Doubly excited Rydberg states of helium (He) have been studied in nanodroplets using synchrotron radiation. Although qualitatively similar to their atomic counterparts, the Fano resonances in droplets are broader and exhibit blueshifts which increase for the higher excited states. However, varying the droplet size hardly affects the shapes of the resonances. Furthermore, additional dipole-forbidden resonances appear which are not seen in the He atom. We discuss these features in terms of localized atomic states perturbed by the surrounding He atoms.

  11. Direct Electron Impact Excitation of Rydberg-Valence States of Molecular Nitrogen

    NASA Astrophysics Data System (ADS)

    Malone, C. P.; Johnson, P. V.; Liu, X.; Ajdari, B.; Muleady, S.; Kanik, I.; Khakoo, M. A.

    2012-12-01

    Collisions between electrons and neutral N2 molecules result in emissions that provide an important diagnostic probe for understanding the ionospheric energy balance and the effects of space weather in upper atmospheres. Also, transitions to singlet ungerade states cause N2 to be a strong absorber of solar radiation in the EUV spectral range where many ro-vibrational levels of these Rydberg-valence (RV) states are predissociative. Thus, their respective excitation and emission cross sections are important parameters for understanding the [N]/[N2] ratio in the thermosphere of nitrogen dominated atmospheres. The following work provides improved constraints on absolute and relative excitation cross sections of numerous RV states of N2, enabling more physically accurate atmospheric modeling. Here, we present recent integral cross sections (ICSs) for electron impact excitation of RV states of N2 [6], which were based on the differential cross sections (DCSs) derived from electron energy-loss (EEL) spectra of [5]. This work resulted in electronic excitation cross sections over the following measured vibrational levels: b 1Πu (v‧=0-14), c3 1Πu (v‧=0-3), o3 1Πu (v‧=0-3), b‧ 1Σu+ (v‧=0-10), c‧4 1Σu+ (v‧=0-3), G 3Πu (v‧=0-3), and F 3Πu (v‧=0-3). We further adjusted the cross sections of the RV states by extending the vibronic contributions to unmeasured v‧-levels via the relative excitation probabilities (REPs) as discussed in [6]. This resulted in REP-scaled ICSs over the following vibrational levels for the singlet ungerade states: b(0-19), c3(0-4), o3(0-4), b‧(0-16), and c‧4(0-8). Comparison of the ICSs of [6] with available EEL based measurements, theoretical calculations, and emission based work generally shows good agreement within error estimations, except with the recent reevaluation provided by [1]. Further, we have extended these results, using the recent EEL data of [3], to include the unfolding of better resolved features above ~13.82eV. This effort is to provide improved cross sections for these RV states, in particular for the b‧ 1Σu+ and c‧4 1Σu+ states, with inclusion of more upper vibrational levels. Future optical emission work should include re-measurements of excitation shape functions of the singlet ungerade states utilizing better spectral resolution than past determinations (e.g., [2,4]) to avoid uncertainties associated with unresolved and/or blended spectral features as well as J-dependent predissociation. Further development of theoretical treatments of N2 excitation is also in need. We will also present analysis of our new low-energy, near-threshold excitation cross sections for the valence states of N2, including a 1Πg (v‧) levels. Acknowledgement: This work was performed at CSUF and JPL, Caltech, under contract with NASA. We gratefully acknowledge financial support through NASA's OPR and PATM programs and NSF-PHY-RUI-0096808 & -0965793 and NSF-AGS-0938223. References: [1] Ajello, J. M., M. H. Stevens, I. Stewart, et al. (2007), GRL, 34, L24204 [2] Ajello, J. M., G. K. James, and B. O. Franklin (1989), PRA, 40, 3524-56 [3] Heays, A. N., B. R. Lewis, S. T. Gibson, et al. (2012), PRA, 85, 012705 [4] James, G. K., J. M. Ajello, B. Franklin, and D. E. Shemansky (1990), JPB, 23, 2055-81 [5] Khakoo, M. A., C. P. Malone, P. V. Johnson, et al. (2008), PRA, 77, 012704 [6] Malone, C. P., P. V. Johnson, X. Liu, et al. (2012), PRA, 85, 062704

  12. Field ionization of alkali-metal Rydberg states formed by resonance absorption of sunlight: Application as an ultraviolet radiation detector

    SciTech Connect

    Whitaker, T.; Bekov, G.

    1995-04-01

    In order to assess the long-term threat posed to plant and animal life by ozone depletion and the resulting increase of ultraviolet (UV) radiation, the United States Department of Agriculture has established a UV irradiance monitoring program, with emphasis on the UV-B wavelength region between 290 nm and 320 nanometers. However, there is serious concern over the long-term stability of conventional instruments used to measure the UV-B flux. We have recently demonstrated the feasibility of using resonance ionization to monitor specific wavelengths in the UV-B band. However, instead of using high-intensity lasers to detect a few atoms as is typically done in resonance ionization experiments, the UV-B monitor is based upon using a relatively high pressure (about 10{sup -5} Torr) of vapor-phase cesium, rubidium, and/or potassium to detect photons. Specific Rydberg states formed by resonant absorption of UV-B radiation in these vapors can be identified by their unique voltage threshold for ionization. Our initial work has established that there is a high correlation between the detected Rydberg state and the wavelength of the absorbed light, so that it should be possible to construct a UV-B detector with an internal, absolute wavelength calibration. The initial work will be discussed and the prospect for making a UV-B detector will be examined.

  13. A Definitive Analysis of the Rydberg and Valence Anti-bonding Character of States in the O K-edge of H2O

    SciTech Connect

    Bagus, Paul S.; Woll, Christof; Ilton, Eugene S.

    2006-09-01

    A new method is introduced that provides a definitive analysis of the nature and the extent of the valence anti-bonding and Rydberg character of excited orbitals involved in excitations from core levels to unoccupied bound states. These excitations are observed in X-ray absorption and related spectroscopies. The new method depends on defining pure valence anti-bonding orbitals using, literally, a linear combination of atomic orbitals. Application to the O K-edge excited states of H2O is presented. This analysis is important since Rydberg and valence anti-bonding orbitals will behave differently when a molecule is placed in a condensed environment.

  14. Observation of intracluster Coulombic decay of Rydberg-like states triggered by intense near-infrared pulses

    NASA Astrophysics Data System (ADS)

    Schütte, Bernd; Arbeiter, Mathias; Fennel, Thomas; Jabbari, Ghazal; Gokhberg, Kirill; Kuleff, Alexander I.; Vrakking, Marc J. J.; Rouzée, Arnaud

    2015-05-01

    Interatomic Coulombic decay (ICD) describes a process, where an excited atom relaxes by transferring its energy to an atom in the environment that gets ionized. So far, ICD has been observed following XUV ionization or excitation of clusters. Here we present novel results of an intracluster Coulombic decay mechanism induced by intense NIR pulses and following Rydberg atom formation in the generated nanoplasma. When a highly-excited Rydberg atom relaxes to its ground state by transferring its excess energy to a weakly bound electron in the environment, electrons with kinetic energies close to the atomic ionization potential are emitted. We show evidence for such an intracluster Coulombic decay process that leaves clear signatures in the electron kinetic energy spectra. ICD is time-resolved in a pump-probe experiment, where a weak probe pulse depopulates the excited states, leading to a quenching of the ICD signal. We find a decay time of 87 ps, which is siginificantly longer than for previous ICD observations, where inner-shell holes were created by XUV pulses. Intracluster Coulombic decay is found to be a generic process that takes places in atomic and molecular clusters and at different wavelengths. It may play an important role in biological systems and in astronomical plasmas. Previous affiliation: Max-Born-Institut, Berlin, Germany.

  15. Rydberg series of 1Σu+ and 1Δu states of the Li2 molecule studied by the promotion model

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Lee, Chun-Woo

    2015-01-01

    We studied the Rydberg series for the 12 1Σu+, 7 1Δu, and 1 1Γu states. This set consists of the seventeen states derivable from the Li(2s) + Li(nl) (n = 2, 3, 4, 5) configuration, one 1Σu+ state and one 1Δu 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, σuns (n = 3, 4, 5, 6), σunp (n = 2, 3, 4, 5), δund (n = 3, 4, 5, 6), and δunf (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 1Σu+ and 1Δu states. The larger number of avoided crossings for 1Σu+ states produces features in the PECs of the 1Σu+ 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.

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

    ERIC Educational Resources Information Center

    Harbola, Varun

    2011-01-01

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

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

    ERIC Educational Resources Information Center

    Harbola, Varun

    2011-01-01

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

  18. Tunable cw UV laser with <35 kHz absolute frequency instability for precision spectroscopy of Sr Rydberg states.

    PubMed

    Bridge, Elizabeth M; Keegan, Niamh C; Bounds, Alistair D; Boddy, Danielle; Sadler, Daniel P; Jones, Matthew P A

    2016-02-01

    We present a solid-state laser system that generates over 200 mW of continuous-wave, narrowband light, tunable from 316.3 nm - 317.7 nm and 318.0 nm - 319.3 nm. The laser is based on commercially available fiber amplifiers and optical frequency doubling technology, along with sum frequency generation in a periodically poled stoichiometric lithium tantalate crystal. The laser frequency is stabilized to an atomic-referenced high finesse optical transfer cavity. Using a GPS-referenced optical frequency comb we measure a long term frequency instability of < 35 kHz for timescales between 10-3 s and 103 s. As an application we perform spectroscopy of Sr Rydberg states from n = 37 - 81, demonstrating mode-hop-free scans of 24 GHz. In a cold atomic sample we measure Doppler-limited linewidths of 350 kHz. PMID:26906804

  19. Interaction of Rydberg atoms in circular states with the alkaline-earth Ca(4s{sup 2}) and Sr(5s{sup 2}) atoms

    SciTech Connect

    Mironchuk, E. S.; Narits, A. A.; Lebedev, V. S.

    2015-11-15

    The resonant mechanism of interaction of alkaline-earth atoms having a low electron affinity to Rydberg atoms in circular (l = vertical bar m vertical bar = n–1) and near-circular states has been studied. To describe the dynamics of resonant processes accompanied by nonadiabatic transitions between ionic and Rydberg covalent terms of a quasimolecule, an approach based on the integration of coupled equations for the probability amplitudes has been developed taking into account the possibility of the decay of an anion in the Coulomb field of the positive ionic core of a highly excited atom. The approach involves the specific features of the problem associated with the structure of the wavefunction of a Rydberg electron in states with high orbital angular momenta l ∼ n–1. This approach provides a much more accurate description of the dynamics of electronic transitions at collisions between atoms than that within the modified semiclassical Landau–Zener model. In addition, this approach makes it possible to effectively take into account many channels of the problem. The cross sections for resonant quenching of Rydberg states of the Li(nlm) atom with given principal n, orbital l = n–1, and magnetic m quantum numbers at thermal collisions with the Ca(4s{sup 2}) and Sr(5s{sup 2}) atoms have been calculated. The dependences of the results on n, m, and angle α between the relative velocity of the atoms and the normal to the plane of the orbit of the Rydberg electron have been obtained. The influence of orientational effects on the efficiency of the collisional destruction of circular and near-circular states has been studied. The results indicate a higher stability of such states to their perturbations by neutral particles as compared to usually studied nl states with low values of l (l ≪ n)

  20. Interaction of Rydberg atoms in circular states with the alkaline-earth Ca(4 s 2) and Sr(5 s 2) atoms

    NASA Astrophysics Data System (ADS)

    Mironchuk, E. S.; Narits, A. A.; Lebedev, V. S.

    2015-11-01

    The resonant mechanism of interaction of alkaline-earth atoms having a low electron affinity to Rydberg atoms in circular ( l = | m| = n-1) and near-circular states has been studied. To describe the dynamics of resonant processes accompanied by nonadiabatic transitions between ionic and Rydberg covalent terms of a quasimolecule, an approach based on the integration of coupled equations for the probability amplitudes has been developed taking into account the possibility of the decay of an anion in the Coulomb field of the positive ionic core of a highly excited atom. The approach involves the specific features of the problem associated with the structure of the wavefunction of a Rydberg electron in states with high orbital angular momenta l ~ n-1. This approach provides a much more accurate description of the dynamics of electronic transitions at collisions between atoms than that within the modified semiclassical Landau-Zener model. In addition, this approach makes it possible to effectively take into account many channels of the problem. The cross sections for resonant quenching of Rydberg states of the Li( nlm) atom with given principal n, orbital l = n-1, and magnetic m quantum numbers at thermal collisions with the Ca(4 s 2) and Sr(5 s 2) atoms have been calculated. The dependences of the results on n, m, and angle α between the relative velocity of the atoms and the normal to the plane of the orbit of the Rydberg electron have been obtained. The influence of orientational effects on the efficiency of the collisional destruction of circular and near-circular states has been studied. The results indicate a higher stability of such states to their perturbations by neutral particles as compared to usually studied nl states with low values of l ( l ≪ n).

  1. Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange

    NASA Astrophysics Data System (ADS)

    McConnell, R.; Gabrielse, G.; Kolthammer, W. S.; Richerme, P.; Müllers, A.; Walz, J.; Grzonka, D.; Zielinski, M.; Fitzakerley, D.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; ATRAP Collaboration

    2016-03-01

    Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is expected to be increased by a similar factor.

  2. Identification of transitions into Rydberg states in the X-ray absorption spectra of condensed long-chain alkanes

    NASA Astrophysics Data System (ADS)

    Bagus, P. S.; Weiss, K.; Schertel, A.; Wöll, Ch.; Braun, W.; Hellwig, C.; Jung, C.

    1996-01-01

    A detailed theoretical analysis of the high-resolution X-ray absorption spectra of condensed long-chain alkane molecules (hexatriacontane, C 36H 74 and heptatriacontane, C 37H 76) suggests that the resonance at 287.7 eV, which is the dominating feature in the near-edge X-ray absorption spectra of saturated long-chain hydrocarbons, is due to transitions into Rydberg states. These findings, which are at variance with the previous interpretation, are corroborated by the identification of a previously unresolved resonance at 288.2 eV in the high-resolution X-ray absorption spectra and of the observation of a strong quenching of the X-ray absorption resonances upon physisorption on a Cu(111)-metal surface.

  3. Predissociation and dissociative ionization of Rydberg states of Xe{sub 2} and the photodissociation of Xe{sub 2}{sup +}.

    SciTech Connect

    Shubert, V. A.; Rednic, M.; Pratt, S. T.

    2010-01-01

    The Rydberg states of Xe{sub 2} in the region between 76,,000 and 84,000 cm{sup -1} were studied by using a combination of two-photon excitation and velocity map ion imaging. The electronic states in this region are based on the Xe({sup 1}S{sub 0})+Xe 6p and 5d dissociation limits, and the large number of states leads to numerous curve crossings and distorted potentials. These Rydberg states can decay by predissociation or fluorescence or can be photoionized, dissociatively photoionized, or photodissociated by the absorption of a single additional photon. Furthermore, the molecular ion can be photodissociated as well. While numerous other techniques have been applied to this problem, velocity map ion imaging provides a high resolution approach to determine the operative processes. When combined with existing data obtained by other methods, the present experiments allow a more complete understanding of the assignment and behavior of these states.

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

    SciTech Connect

    Mack, Markus; Karlewski, Florian; Hattermann, Helge; Hoeckh, Simone; Jessen, Florian; Cano, Daniel; Fortagh, Jozsef

    2011-05-15

    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.

  5. Photofragmentations, state interactions, and energetics of Rydberg and ion-pair states: resonance enhanced multiphoton ionization via E and V (B) states of HCl and HBr.

    PubMed

    Long, Jingming; Wang, Huasheng; Kvaran, gst

    2013-01-28

    (2 + n) resonance enhanced multiphoton ionization mass spectra for resonance excitations to diabatic E(1)?(+) (v') Rydberg and V (1)?(+) (v') ion-pair states (adiabatic B(1)?(+)(v') states) of H(i)Cl (i = 35,37) and H(i)Br (i = 79,81) were recorded as a function of excitation wavenumber (two-dimensional REMPI). Simulation analyses of ion signal intensities, deperturbation analysis of line shifts and interpretations of line-widths are used to derive qualitative and quantitative information concerning the energetics of the states, off-resonance interactions between the E states and V states, closest in energy as well as on predissociation channels. Spectroscopic parameters for the E(1)?(+) (v')(v' = 1) for H(35)Cl and v' = 0 for H(79)Br states, interaction strengths for E - V state interactions and parameters relevant to dissociation of the E states are derived. An overall interaction and dynamical scheme, to describe the observations for HBr, is proposed. PMID:23387585

  6. The Observation of Transitions Between Rydberg States of Atomic Chlorine by Laser Magnetic Resonance at 6.7 μm

    NASA Astrophysics Data System (ADS)

    Brown, J. M.; Comben, E. R.; Bohle, W.; Zeitz, D.; Urban, W.

    1987-02-01

    Transitions between Rydberg states of atomic chlorine have been detected between 1477 and 1507 cm-1 by the technique of carbon monoxide laser magnetic resonance (LMR). Transitions have been observed in both emission and absorption. The spectra have been assigned for those transitions involving levels which have been identified previously. However, several more resonances are unassigned, revealing the presence of previously unidentified states of atomic chlorine. Many of the lines show resolved nuclear hyperfine structure.

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

    SciTech Connect

    Gilchrist, A. J.; Ritchie, G. A. D.

    2013-06-07

    (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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  9. Welcome to Rydberg-Land

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Grimes, David; Colombo, Tony; Klein, Ethan; Barnum, Timothy J.; Field, Robert W.

    2014-06-01

    Rydberg-Rydberg electronic transitions provide information about the electronic structure of the ion-core and each of the fundamental mechanisms by which a light electron exchanges energy and angular momentum with heavy nuclei. Normally, Rydberg electronic states have been indirectly observed via a sequence of laser-excitation steps, for which detection of transitions is accomplished by either fluorescence- or ionization-based schemes. Electronic transitions of |? n*|<1 between Rydberg states (n* is the effective principal quantum number) have kilo-Debye electric dipole transition moments when n*>30. Such enormous transition moments render Rydberg-Rydberg electronic transitions directly observable. A chirped millimeter wave pulse can simultaneously polarize a 23 GHz chunk of two-level systems. In our spectra of Ca atoms (104 Rydberg atoms/cm3 in a volume of 100 cm3), the resultant Free Induction Decay (FID) from each of these two level systems is down-converted and heterodyne detected at <500 kHz resolution (at 3:1 S:N in a single chirp). Willis Flygare and Brooks Pate are to be thanked! But there is more, especially for molecules! Recently, the Doyle and DeMille research groups have developed a cryogenic buffer gas cooled ablation source, our version of which produces beams of alkaline earth monohalide molecules that are >100x brighter and 10x slower than those produced by our Smalley type supersonic jet ablation source. Our 20 K Neon buffer gas cooled ablation source, in combination with redesign of the resonance region (300 cm3, mm-wave radiation on-axis with the molecular beam) of our CPmmW spectrometer, has resulted in a 1000x increase in brightness of a BaF molecular beam (108 Rydberg molecules/cm3 in a single quantum state) and a 10x improvement in resolution (50 kHz @ 100 GHz). When buffer gas cooled ablation sources are combined with direct detection of FID, a new domain of high resolution molecular spectroscopy begs for exploration!

  10. All-electron spin-orbit configuration interaction study on the valence and low-lying Rydberg electronic states of GeH

    NASA Astrophysics Data System (ADS)

    Li, Rui; Zhai, Zhen; Zhang, Xiaomei; Jin, Mingxing; Xu, Haifeng; Yan, Bing

    2015-05-01

    Germanium monohydride (GeH), an important radical for the growth of semiconductor germanium film, has received much attention. However, the electronic structure and spectroscopic properties of low-lying excited states of the radical have not been well understood, especially the coupling between different electronic states. In this work, eight Λ-S valence states and four low-lying Λ-S Rydberg states correlated to the four lowest dissociation limits of GeH are investigated by employing the multireference configuration interaction method. With the inclusion of spin-orbit coupling effect, there are 24 Ω states generated from 12 Λ-S states. On the basis of computed potential energy curves of the Λ-S and Ω states, the spectroscopic parameters of bound states are evaluated, which demonstrate that the first Rydberg state 32Σ+ located at 5.12 eV is exactly the B2Σ+ state tentatively assigned by experiment. With the help of the calculated spin-orbit matrix elements, the predissociation mechanism of A2Δ state is investigated, which may interpret the fact that ν‧>2 vibrational levels of A2Δ state are difficult to be detected in experiment. Finally, the transition dipole moments and the radiative lifetimes of several vibrational levels of A2Δ and a4Σ- states are calculated.

  11. Hybrid Quantum Information Processing with Superconducting Circuits and Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Beck, Matthew; Isaacs, Joshua; Booth, Donald; Saffman, Mark; McDermott, Robert

    Hybrid approaches to quantum information processing exploit the strengths of disparate quantum technologies to realize performance that exceeds what can be reached with any single technology on its own. Here we describe steps toward realization of a hybrid superconducting circuit - Rydberg atom quantum architecture that will marry a fast, high-fidelity superconducting quantum processor with a long-lived quantum memory based on trapped Rydberg atoms. The key challenge is development of a high-fidelity microwave photon - Rydberg atom interface. We have designed superconducting thin-film microwave resonators that allow trapping of single Rydberg atoms at a voltage antinode, where coupling to the zero-point fields of the resonator is strongest. We discuss the dependence of resonator quality factor and achievable coupling factor on device geometry. Finally, we present preliminary results of experiments to couple Rydberg atoms and superconducting linear resonators in a custom liquid helium cryostat.

  12. Rydberg state photochemistry of 1,4-diazabicyclo(2. 2. 2)octane excited by 193- and 248-nm lasers

    SciTech Connect

    Lin, C.T.

    1987-05-21

    Linear and nonlinear photochemistries of 1,4-diazabicyclo(2.2.2)octane (DABCO) are investigated at room temperature by using ArF (193 nm) and KrF (248 nm) lasers. With an unfocused beam geometry, DABCO vapor displays a strong fluorescence when excited at 248 nm, but it shows no detectable emission with 193-nm excitation. The linear photochemistry quantum yield for DABCO is determined as phi/sub p/(248nm) approx. 0.1 and phi/sub p/(193 nm) approx. 0.3. The main stable photochemical products are analyzed as C/sub 2/H/sub 4/ and C/sub 2/H/sub 2/ for 248- and 193-nm excitation, respectively. When focused beam excitation is used, both ArF and KrF lasers dissociate DABCO molecules and give three strong radical emissions of CN*(B vector /sup 2/..sigma.. ..-->.. X vector /sup 2/ ..sigma../sup +/), CH*(A vector /sup 2/..delta.. ..-->.. X vector /sup 2/II), and C/sub 2/*(D vector /sup 3/II/sub g/ ..-->.. a vector /sup 3/II/sub u/). The time behavior, the laser power dependence, and the sample pressure dependence of these emissive radicals are examined. The possible mechanisms for the Rydberg state photochemistry of DABCO are discussed.

  13. Phase Modulation in Rydberg Dressed Multi-Wave Mixing processes.

    PubMed

    Zhang, Zhaoyang; Zheng, Huaibin; Yao, Xin; Tian, Yaling; Che, Junling; Wang, Xiuxiu; Zhu, Dayu; Zhang, Yanpeng; Xiao, Min

    2015-01-01

    We study the enhancement and suppression of different multi-waving mixing (MWM) processes in a Rydberg-EIT rubidium vapor system both theoretically and experimentally. The nonlinear dispersion property of hot rubidium atoms is modulated by the Rydberg-Rydberg interaction, which can result in a nonlinear phase shift of the relative phase between dark and bright states. Such Rydberg-induced nonlinear phase shift can be quantitatively estimated by the lineshape asymmetry in the enhancedand suppressed MWM processes, which can also demonstrate the cooperative atom-light interaction caused by Rydberg blockaded regime. Current study on phase shift is applicable to phase-sensitive detection and the study of strong Rydberg-Rydberg interaction. PMID:26053438

  14. Phase Modulation in Rydberg Dressed Multi-Wave Mixing processes

    PubMed Central

    Zhang, Zhaoyang; Zheng, Huaibin; Yao, Xin; Tian, Yaling; Che, Junling; Wang, Xiuxiu; Zhu, Dayu; Zhang, Yanpeng; Xiao, Min

    2015-01-01

    We study the enhancement and suppression of different multi-waving mixing (MWM) processes in a Rydberg-EIT rubidium vapor system both theoretically and experimentally. The nonlinear dispersion property of hot rubidium atoms is modulated by the Rydberg-Rydberg interaction, which can result in a nonlinear phase shift of the relative phase between dark and bright states. Such Rydberg-induced nonlinear phase shift can be quantitatively estimated by the lineshape asymmetry in the enhancedand suppressed MWM processes, which can also demonstrate the cooperative atom-light interaction caused by Rydberg blockaded regime. Current study on phase shift is applicable to phase-sensitive detection and the study of strong Rydberg-Rydberg interaction. PMID:26053438

  15. Evidence of the 2s2p({sup 1}P) doubly excited state in the harmonic generation spectrum of helium

    SciTech Connect

    Ngoko Djiokap, J. M.; Starace, Anthony F.

    2011-07-15

    By solving the two-active-electron time-dependent Schroedinger equation in an intense, ultrashort laser field, we investigate evidence of electron correlations in the high-order harmonic generation spectrum of helium. As the frequency of the driving laser pulse varies from 4.6 to 6.6 eV, the 13th, 11th, and 9th harmonics sequentially become resonant with the transition between the ground state and the isolated 2s2p({sup 1}P) autoionizing state of helium, which dramatically enhances these harmonics and changes their profiles. When each of the 9th and 13th harmonics are in resonance with this autoionizing state, there is also a low-order multiphoton resonance with a Rydberg state, resulting in a particularly large enhancement of these harmonics relative to neighboring harmonics. When the 11th harmonic is in resonance with the 2s2p({sup 1}P) autoionizing state, the 13th harmonic is simultaneously in resonance with numerous higher-energy autoionizing states, resulting in a competition between these two harmonics for intensity. These results demonstrate that even electron correlations occurring over a narrow energy interval can have a significant effect on strong-field processes such as harmonic generation.

  16. Rotationally resolved photoelectron spectra in resonance enhanced multiphoton ionization of HCl via the F 1Δ2 Rydberg state

    NASA Astrophysics Data System (ADS)

    Wang, Kwanghsi; McKoy, V.

    1991-12-01

    Results of studies of rotational ion distributions in the X 2Π3/2 and X 2Π1/2 spin-orbit states of HCl+ resulting from (2+1') resonance enhanced multiphoton ionization (REMPI) via the S(0) branch of the F 1Δ2 Rydberg state are reported and compared with measured threshold-field-ionization zero-kinetic-energy spectra reported recently [K. S. Haber, Y. Jiang, G. Bryant, H. Lefebvre-Brion, and E. R. Grant, Phys. Rev. A (in press)]. These results show comparable intensities for J+=3/2 of the X 2Π3/2 ion and J+=1/2 of the X 2Π1/2 ion. Both transitions require an angular momentum change of ΔN=-1 upon photoionization. To provide further insight into the near-threshold dynamics of this process, we also show rotationally resolved photoelectron angular distributions, alignment of the ion rotational levels, and rotational distributions for the parity components of the ion rotational levels. About 18% population is predicted to occur in the (+) parity component, which would arise from odd partial-wave contributions to the photoelectron matrix element. This behavior is similar to that in (2+1) REMPI via the S(2) branch of the F 1Δ2 state of HBr and was shown to arise from significant l mixing in the electronic continuum due to the nonspherical molecular ion potential. Rotational ion distributions resulting from (2+1) REMPI via the S(10) branch of the F 1Δ2 state are also shown.

  17. Effects of molecular resonances on Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Derevianko, Andrei; Kmr, Pter; Topcu, Turker; Kroeze, Ronen M.; Lukin, Mikhail D.

    2015-12-01

    We study the effect of resonances associated with complex molecular interaction of Rydberg atoms on Rydberg blockade. We show that densely spaced molecular potentials between doubly excited atomic pairs become unavoidably resonant with the optical excitation at short interatomic separations. Such molecular resonances limit the coherent control of individual excitations in Rydberg blockade. As an illustration, we compute the molecular interaction potentials of Rb atoms near the 100 s states asymptote to characterize such detrimental molecular resonances and determine the resonant loss rate to molecules and inhomogeneous light shifts. Techniques to avoid the undesired effect of molecular resonances are discussed.

  18. The multiphoton ionization spectrum of jet-cooled pyrimidine in the 3 p Rydberg and 3B1 ( π∗, n) states

    NASA Astrophysics Data System (ADS)

    Philis, J. G.

    2005-07-01

    Resonance-enhanced multiphoton ionization (REMPI) has been applied to study the n → 3 p Rydberg transition of pyrimidine (jet-cooled sample and mass resolved spectrum). Only the one component, the 3 pz( B2), appears in the (2 + 1) REMPI and the active vibrations are ν6 a = 622, ν1 = 946, and ν9 a = 1116 cm -1. The symmetry of the state was determined by polarization measurements (linear, circular polarization). The first ( π∗, n) 3B1 triplet state appears as a one-photon resonance in the three-photon ionization process.

  19. Observations and analysis with the spline-based Rydberg-Klein-Rees approach for the 3 1 Σg + state of Rb2

    NASA Astrophysics Data System (ADS)

    Yang, Jinxin; Guan, Yafei; Zhao, Wei; Zhou, Zhaoyu; Han, Xiaomin; Ma, Jie; Sovkov, Vladimir B.; Ivanov, Valery S.; Ahmed, Ergin H.; Lyyra, A. Marjatta; Dai, Xingcan

    2016-01-01

    Ro-vibrational term values of the 3 1 Σg + state of 85,85Rb2 and 85,87Rb2 and resolved fluorescence spectra to the A 1 Σu + state are recorded following optical-optical double resonance excitation. The experimental data are heavily perturbed, and as a result, the standard analysis based on Dunham series representation of the energy levels fails. The analysis is done via modeling the adiabatic potential function with the Rydberg-Klein-Rees potential constructed from the generalized smoothing spline interpolation of the vibrational energies Gv and rotational constants Bv.

  20. Quantum-classical lifetimes of Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Junginger, Andrej; Main, Jörg; Wunner, Günter

    2013-04-01

    A remarkable property of Rydberg atoms is the possibility of creating molecules formed by one highly excited atom and another atom in the ground state. The first realization of such a Rydberg molecule has opened an active field of physical investigations, and showed that its basic properties can be described within a simple model regarding the ground state atom as a small perturber that is bound by a low-energy scattering process with the Rydberg electron (Greene et al 2000 Phys. Rev. Lett. 85 2458). Besides the good agreement between theory and the experiment concerning the vibrational states of the molecule, the experimental observations yield the astonishing feature that the lifetime of the molecule is clearly reduced as compared to the bare Rydberg atom (Butscher et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 184004). With focus on this yet unexplained observation, we investigate in this paper the vibrational ground state of the molecule in a quantum-classical framework. We show that the Rydberg wavefunction is continuously detuned by the presence of the moving ground state atom and that the timescale on which the detuning significantly exceeds the natural linewidth is in good agreement with the observed reduced lifetimes of the Rydberg molecule.

  1. Ground state and resonant states of helium in exponential cosine screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Ghoshal, Arijit; Ho, Y. K.

    2009-05-01

    We have investigated the ground state and a resonance state of normal helium atom in exponential cosine screened Coulomb potential (ECSCP) with screening parameterλ: V(r),,,1r,^-λr(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz's variational principle and making use of a highly correlated wave function, we have determined the ground state energies and wave functions of the helium atom for different values of the screening parameterλ. Furthermore, we have shown that the ground state energy of helium for a particular value of λ does converge with increasing number of terms in the wave function. In addition, using the stabilization method, we have investigated the doubly excited 2s^2 ^1S^e resonance state in helium with ECSCP. Resonance energy and width for various λ values are calculated. Our present work will play a useful role in the investigations of atomic structures in quantum plasmas [1]. [1]. P.K. Shukla and B. Eliasson, Phys. Lett. A 372, 2899 (2008).

  2. Stability of Surface State Electrons on Helium Films

    NASA Astrophysics Data System (ADS)

    Leiderer, P.; Scheer, E.; Kono, K.; Lin, J.-J.; Rees, D. G.

    2016-05-01

    Electrons on helium substrates form a model Coulomb system in which the transition from classical electron liquid to Wigner crystal is readily observed. However, attempts to increase the electron density in order to observe the `quantum melting' of the system to a Fermi degenerate gas are hindered by an instability of the helium surface. Here we describe experimental efforts to reach the degenerate regime on thin helium films and microstructured substrates, for which the surface instability is suppressed. We demonstrate that, although the electron densities obtained exceed those for bulk helium substrates, observation of quantum melting remains challenging. We discuss possible solutions to the technical challenges involved.

  3. Polarization control of absorption of virtual dressed states in helium

    NASA Astrophysics Data System (ADS)

    Reduzzi, Maurizio; Hummert, Johan; Dubrouil, Antoine; Calegari, Francesca; Nisoli, Mauro; Frassetto, Fabio; Poletto, Luca; Chen, Shaohao; Wu, Mengxi; Gaarde, Mette B.; Schafer, Kenneth; Sansone, Giuseppe

    2015-09-01

    The extreme ultraviolet absorption spectrum of an atom is strongly modified in the presence of a synchronized intense infrared field. In this work we demonstrate control of the absorption properties of helium atoms dressed by an infrared pulse by changing the relative polarization of the infrared and extreme ultraviolet fields. Light-induced features associated with the dressed 1 s 2 s , 1 s 3 s , and 1 s 3 d states, referred to as 2 s+ , 3 s± , and 3 d± light-induced states, are shown to be strongly modified or even eliminated when the relative polarization is rotated. The experimental results agree well with calculations based on the solution of the time-dependent Schrödinger equation using a restricted excitation model that allows efficient treatment of the three-dimensional problem. We also present an analysis of the light-induced states based on Floquet theory, which allows for a simple explanation of their properties. Our results open a new route to creating controllable superpositions of dipole allowed and nondipole allowed states in atoms and molecules.

  4. 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

    Sprecher, Daniel; Merkt, Frédéric; Jungen, Christian

    2014-03-14

    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.

  5. Multiphoton Microwave Ionization of Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Gurian, Joshua Houston

    This thesis describes a series of multiphoton microwave experiments on Rydberg atoms when the microwave frequency is much greater than the classical Kepler frequency of the excited atoms. A new kHz pulse repetition frequency dye laser system was constructed for Rydberg lithium excitation with a linewidth as narrow as 3 GHz. This new laser system is used for first experiments of multiphoton microwave ionization of Rydberg lithium approaching the photoionization limit using 17 and 36 GHz microwave pulses. A multi-channel quantum defect model is presented that well describes the experimental results, indicating that these results are due to the coherent coupling of many atomic levels both above and below the classical ionization limit. Finally, preliminary results of measuring the final-state distributions of high lying Rydberg states after 17 GHz microwave pulses are presented.

  6. Antiprotonic helium atomcules

    NASA Astrophysics Data System (ADS)

    Sauge, Sébastien

    2012-10-01

    About 3% of antiprotons (bar{p}) stopped in helium are long-lived with microsecond lifetimes, against picoseconds in all other materials. This unusual longevity has been ascribed to the trapping of bar{p} on metastable bound states in bar{p}He+ helium atom-molecules thus named atomcules. Apart from their unique dual structure investigated by laser spectroscopy - a near-circular quasi-classical Rydberg atom with l n - 1 37 or a special diatomic molecule with a negatively charged bar{p} nucleus in high rotational state with J = l - the chemical physics aspects of their interaction with other atoms or molecules constitute an interesting topic for molecular physics. While atomcules may resist to million collisions in helium, molecular contaminants such as H2 are likely to destroy them in a single one, down to very low temperatures. In the Born-Oppenheimer framework, we interpret the molecular interaction obtained by ab initio quantum chemical calculations in terms of classical reactive channels, with activation barriers accounting for the experiments carried out in He and H2. From classical trajectory Monte Carlo simulations, we show that the thermalization stage strongly quenches initial populations, thus reduced to a recovered 3 % trapping fraction. This work illustrates the pertinence of chemical physics concepts to the study of exotic processes involving antimatter. New insights into the physico-chemistry of cold interstellar radicals are anticipated.

  7. Vacuum Ultraviolet Laser Photoion and Pulsed Field Ionization-Photoion Study of Rydberg Series of Chlorine Atoms Prepared in the 2PJ (J = 3/2 and 1/2) Fine-structure States

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Gao, Hong; Zhou, Jingang; Ng, C. Y.

    2015-09-01

    We have measured the high-resolution vacuum ultraviolet (VUV) photoion (VUV-PI) and VUV pulsed-field ionization-photoion (VUV-PFI-PI) spectra of chlorine atoms (Cl) in the VUV energy range 103,580-105,600 cm-1 (12.842-13.093 eV) using a tunable VUV laser as the photoexcitation and photoionization source. Here, Cl atoms are prepared in the Cl(2P3/2) and Cl(2P1/2) fine-structure states by 193.3 nm laser photodissociation of chlorobenzene. The employment of VUV-PFI-PI detection has allowed the identification of Rydberg transitions that are not observed in VUV-PI measurements. More than 180 new Rydberg transition lines with principal quantum number up to n = 61 have been identified and assigned to members of nine Rydberg series originating from the neutral Cl(2P3/2) and Cl(2P1/2) fine-structure states. Two of these Rydberg series are found to converge to the Cl+(3P2), four to the Cl+(3P1), and three to the Cl+(3P0) ionization limits. Based on the convergence limits determined by least-squares fits of the observed Rydberg transitions to the modified Ritz formula, we have obtained a more precise ionization energy (IE) for the formation of the ionic Cl+(3P2) from the ground Cl(2P3/2) state to be 104,591.01 0.13 cm-1. This is consistent with previous IE measurements, but has a smaller uncertainty. The analysis of the quantum defects obtained for the Rydberg transitions reveals that many high-n Rydberg transitions are perturbed.

  8. Excited States of Helium Isotopes 6,7He

    NASA Astrophysics Data System (ADS)

    Chernyshev, B. A.; Gurov, Yu. B.; Korotkova, L. Yu.; Kuznetsov, D. S.; Lapushkin, S. V.; Pritula, R. V.; Tel'Kushev, M. V.; Sandukovskiy, V. G.

    2015-06-01

    The excited states of heavy helium isotopes 6,7He were studied in stopped pion absorption on 10,11B nuclei. In three reaction channels 11B(π-, dt)6He, 10B(π-, pt)6He and 10B(π-, dd)6He the 6He state with Ex = 3.5(3) MeV and C = 3.1(4) MeV has been observed. At high excitations new levels of 6He have been found with Ex = 9.3(2) MeV, C = 1.0(4) MeV, Ex = 22(1) MeV, C = 2.7(1.4) MeV and Ex = 27.0(8) MeV, C = 2.5(1.1) MeV. Excitation spectrum of 7He has been studied in three reaction channels 11B(π-, pt)7He, 11B(π-, dd)7He and 10B(π-, pd)7He. For the first time in one experiment it was observed three low-lying narrow (C<0.5 MeV) states with Ex = 3.1(1), 4.9(2) and 6.7(2) MeV. At high excitations new levels have been found with Ex = 19.8(3) MeV, C = 1.5(3) MeV and Ex = 24.8(4) MeV, C = 4.6(7) MeV.

  9. Antiferromagnetic phase transition in a nonequilibrium lattice of Rydberg atoms

    SciTech Connect

    Lee, Tony E.; Cross, M. C.; Haeffner, H.

    2011-09-15

    We study a driven-dissipative system of atoms in the presence of laser excitation to a Rydberg state and spontaneous emission. The atoms interact via the blockade effect, whereby an atom in the Rydberg state shifts the Rydberg level of neighboring atoms. We use mean-field theory to study how the Rydberg population varies in space. As the laser frequency changes, there is a continuous transition between the uniform and antiferromagnetic phases. The nonequilibrium nature also leads to a novel oscillatory phase and bistability between the uniform and antiferromagnetic phases.

  10. Scattering properties of strongly interacting Rydberg polaritons

    NASA Astrophysics Data System (ADS)

    Choi, Soonwon; Bienias, Przemek; Firstenberg, Ofer; Maghrebi, Mohammad; Lukin, Mikhail; Gorshkov, Alexey; Gullans, Michael; Buchler, Hanspeter

    2014-05-01

    The combination of Electromagnetically Induced Transparency(EIT) and strong Rydberg-Rydberg interaction can lead to a system of interacting polaritons. In this poster, we present a theoretical analysis of two-polariton dynamics in Rydberg EIT medium. We show that the effective polariton-polariton interaction is tunable to both attraction and repulsion and investigate its scattering properties. In the regime of attraction, we identify the formation of multiple two-polariton bound states and compute their dispersions. Finally, we discuss the implications of our results to the ongoing experiments and to the effective many body theory for strongly interacting Rydberg polaritons. We acknowledge support by the Center for Integrated Quantum Science and Technology, the Deutsche Forschungsgemeinschaft, EU Marie Curie ITN COHERENCE, and the National Science Foundation under Grant No. NSF PHY11-25915.

  11. High-Precision Measurement of the Rydberg Constant

    NASA Astrophysics Data System (ADS)

    Moore, Kaitlin; Raithel, Georg

    2013-05-01

    A new spectroscopic method is proposed to couple circular Rydberg states of rubidium using lattice modulation. This excitation strategy could allow for a competitive measurement of the Rydberg constant while relying very little on the accuracy of QED calculations and being insensitive to nuclear charge distribution. The spectroscopic method requires preparing circular-state Rydberg atoms via an RF adiabatic passage method and confining prepared atoms in an optical lattice. Excitation of a two-photon electric quadrupole transition between circular Rydberg states can be accomplished through electro-optic modulation of the lattice at the microwave transition frequency between these states. Detection of the target-state population as a function of the modulation frequency can be accomplished through state-selective electric-field ionization. We discuss frequency shift corrections that will contribute to determining the Rydberg constant from this frequency, along with theoretical and experimental progress. Supported by NSF, NIST.

  12. Probing Atom-Surface Interactions Using Rb Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Sedlacek, Jonathon; Kübler, Harald; Ewel, Charles; Shaffer, James

    2014-05-01

    Alkali Rydberg atoms close to a dielectric surface can resonantly excite surface phonon-polaritons, by decaying into a nearby Rydberg state. In our experiment, rubidium atoms are trapped in a mirror-MOT and are brought close to a dielectric surface in a magnetic trap, where Rydberg excitiation takes place. We are exploring the controlled coupling of Rydberg atoms to surfaces such as quartz, LaF3, and PPLN. Engineered materials such as PPLN allow for control over surface phonon-polariton resonance frequencies and bandwidths, enabling increased coupling strength. Engineering the surface allows for coupling to surface phonon-polaritions at much greater distances.

  13. 532-nm intensity-modulated optical lattice for driving Rydberg-Rydberg transitions

    NASA Astrophysics Data System (ADS)

    Maclennan, Jamie; Moore, Kaitlin; Ramos, Andira; Raithel, Georg

    2015-05-01

    We present progress towards implementing an experiment to make a precision measurement of the Rydberg constant using circular-state Rydberg atoms. An independent measurement of the Rydberg constant will contribute to solving discrepancies in fundamental physics, most notably the ``proton radius puzzle''. The experiment relies on driving a circular to near-circular, n = 51 to 53 Rydberg-Rydberg transition. This transition was chosen because it is insensitive to nuclear charge distribution and first-order Stark and Zeeman effects, yielding less uncertainty in a Rydberg constant measurement. The Rydberg atoms are trapped in a 532-nm optical lattice, which is intensity-modulated so that its temporal harmonics drive the microwave-frequency transitions, so-called ``ponderomotive spectroscopy.'' We have previously demonstrated ponderomotive spectroscopy using 1064-nm light modulated by a fiber-based electro-optic modulator (EOM). Here, the 532-nm light offers the benefit of a ``magic wavelength'' for the transition. Finding a method to prepare a tunable, high-power, intensity-modulated optical lattice at 532 nm presents a substantial challenge. Here, we report on progress in overcoming this challenge as well as on other recent experimental developments.

  14. The structure of the lowest electronic Rydberg state of CdAr complex determined by laser double resonance method in a supersonic jet-expansion beam.

    PubMed

    Koperski, J; Czajkowski, M

    2003-09-01

    The lowest E1(3Sigma(+)) Rydberg state of the CdAr van der Waals (vdW) complex was investigated by means of an optical-optical double resonance (OODR) method of laser spectroscopy in conjunction with a free jet-expansion molecular beam. Two dye lasers were employed for the two-step excitation. The A0(+)(3Pi(+)) and B1(3Sigma(+)) states were used as intermediates in the excitation process from the X0(+)(1Sigma(+)) ground state. Two types of bound-bound excitation spectra of the E1<--A0(+) and E1<--B1 transitions were recorded indicating the existence of two, well defined minima in the E1-state potential energy (PE) curve. First, considerably deep, with the well depth of D(e)'(E1(2))=1309.0 cm(-1) and second, separated by a positive PE barrier, with D(e)'(E1(2))=24.2 cm(-1). Combination of bound-bound and first-time observed bound-free excitation spectra enabled a complete determination of the spectroscopical parameters of the PE curve of the E1-Rydberg state, the height of the PE barrier and its approximate location. In the excitation spectra of the E1<--B1 transition, a nodal structure of the bound-free transitions was observed and elucidated by a projection of the B1-state vibrational wave-functions onto the E1-state potential barrier and/or onto the repulsive part of the E1-state PE curve. The experimental results of our investigation coincides well with recently published results of ab initio calculation of Czuchaj and co-workers [Chem. Phys. 248 (1999) 1; Chem Phys. 263 (2001) 7; Theor. Chem Acc. 105 (2001) 219]. PMID:12963441

  15. New ion-atom collision experiments with aligned and oriented Rydberg atoms

    SciTech Connect

    MacAdam, K.B.

    1994-12-31

    The alignment and orientation of Rydberg target atoms, effected by polarized-laser excitation and the use of external electric and magnetic fields, has recently allowed investigation of new effects in Rydberg-atom collisions at projectile velocities comparable to Rydberg-electron speeds. Results on capture from orbitally aligned Na(nd) targets and circular and elliptical Rydberg states of Li(n=25) will be discussed, and prospects for new alignment studies will be described.

  16. Chirped multiphoton adiabatic passage for a four-level ladder-type Rydberg excitation

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Zhai, Jingjing; Zhang, Lu; Zhang, Weiping

    2015-01-01

    We develop a multiphoton adiabatic passage to realize a highly efficient Rydberg excitation in a four-level ladder-type atomic system. The adiabatic passage is based on the existence of a novel quasidark state in the cascade excitation system where the frequencies of the lasers are appropriately chirped with time. We also investigate the influence of the interatomic Rydberg interaction on the passage and extend its application to the preparation of antiblockade Rydberg atom pairs in the Rydberg blockade regime.

  17. Trapping Rydberg Atoms in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Anderson, Sarah E.

    2012-06-01

    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.

  18. S-states of helium-like ions

    NASA Astrophysics Data System (ADS)

    Liverts, Evgeny Z.; Barnea, Nir

    2012-03-01

    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 Ω in the wave function expansion enables one to calculate the excited nS-states up to n=Ω+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).

  19. Electromagnetically induced transparency and fluorescence in blockaded Rydberg atomic system

    SciTech Connect

    Li, Cheng; Zheng, Huaibin; Zhang, Zhaoyang; Yao, Xin; Zhang, Yunzhe; Zhang, Yiqi; Zhang, Yanpeng

    2013-10-28

    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.

  20. Magnetic trapping of circular Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

    2013-05-01

    Circular Rydberg atoms exhibit a unique combination of properties: long lifetimes ( n5), large magnetic moments and angular momenta (|m | = l =n - 1), and no first order Stark shift. Here, n , l and m are the principal, orbital and magnetic quantum numbers, respectively. Several of these features have made circular Rydberg atoms attractive for a number of applications including photon-atom interaction and Rydberg interaction experiments. We present here the realization of a magnetic trap for circular Rydberg atoms. The Rydberg-atom trap is characterized using state-selective electric-field ionization, direct spatial imaging of the atom distributions and time-of-flight analysis of the ion signal. At room temperature, we observe 70 percent of the trapped atoms remaining after 6ms. We measure an increase of the center-of-mass trap oscillation frequency by the expected factor of √{ | m | }. Simulations of the state-evolution of circular-state atoms in our magnetic trap, held at 300K radiation temperature, are performed and results are in good agreement with the observed phenomena. This work was supported by the AFOSR (FA9550-10-1-0453).

  1. Dynamics and kinetics of molecular high Rydberg states in the presence of an electrical field: An experimental and classical computational study

    NASA Astrophysics Data System (ADS)

    Rabani, Eran; Levine, R. D.; Mühlpfordt, Annette; Even, U.

    1995-01-01

    The effect of an electrical field on the dynamics and decay kinetics of a high Rydberg electron coupled to a core is discussed with special reference to simulations using classical dynamics and to experiment. The emphasis is on the evolution of the system within the range of Rydberg states that can be detected by delayed pulsed ionization spectroscopy (which is n≳90 for both the experiment and the computations). The Hamiltonian used in the computations is that of a diatomic ionic core about which the electron revolves. The primary coupling is due to the anisotropic part of the potential which can induce energy and angular momentum exchange between the orbital motion of the electron and the rotation of the ion. The role of the field is to modulate this coupling due to the oscillation of the orbital angular momentum l of the electron. In the region of interest, this oscillation reduces the frequency with which the electron gets near to the core and thereby slows down the decay caused by the coupling to the core. In the kinetic decay curves this is seen as a stretching of the time axis. For lower Rydberg states, where the oscillation of l is slower, the precession of the orbit, due to the central but not Coulombic part of the potential of the core, prevents the oscillation of l and the decay is not slowed down. Examination of individual trajectories demonstrates that the stretching of the time axis due to the oscillatory motion of the electron angular momentum in the presence of the field is as expected on the basis of theoretical considerations. The relation of this time stretch to the concept of the dilution effect is discussed, with special reference to the coherence width of our laser and to other details of the excitation process. A limit on the principal quantum number below which the time stretch effect will be absent is demonstrated by the computations. The trajectories show both up and down processes in which the electron escapes from the detection window by either a gain or a loss of enough energy. Either process occurs in a diffusive like fashion of many smaller steps, except for a fraction of trajectories where prompt ionization occurs. The results for ensembles of trajectories are examined in terms of the decay kinetics. It is found that after a short induction period, which can be identified with the sampling time of the available phase space, the kinetics of the decay depend only on the initial energy of the electron and on the magnitude of the field, but not on the other details of the excitation process. The computed kinetics of the up and down channels are shown to represent competing decay modes. A possible intramolecular mechanism for long time stability based on the sojourn in intermediate Rydberg states is discussed. The available experimental evidence does not suffice to rule out nor to substantiate this mechanism, and additional tests are proposed. The theoretical expectations are discussed in relation to observed time resolved decay kinetics of high Rydberg states of BBC (bisbenzenechromium) and of DABCO (1,4-diazabicyclo[2.2.2]octane). The experimental setup allows for the imposition of a weak (0.1-1.5 V/cm) electrical field in the excitation region. The role of the amplitude of the time delayed field, used to detect the surviving Rydberg states by ionization, is also examined. The observed decay kinetics are as previously reported for cold aromatic molecules: Most of the decay is on the sub-μs time scale with a minor (˜10%) longer time component. The decay rate of the faster component increases with the magnitude of the field. Many features in such an experiment, including the absolute time scales, are similar to those found in the classical trajectory computations, suggesting that the Hamiltonian used correctly describes the physics of the faster decay kinetics of the high Rydberg states.

  2. Ultracold Long-Range Rydberg Molecules with Complex Multichannel Spectra

    NASA Astrophysics Data System (ADS)

    Eiles, Matthew T.; Greene, Chris H.

    2015-11-01

    A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound "trilobite" molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation.

  3. Ultracold Long-Range Rydberg Molecules with Complex Multichannel Spectra.

    PubMed

    Eiles, Matthew T; Greene, Chris H

    2015-11-01

    A generalized class of ultralong-range Rydberg molecules is predicted which consist of a multichannel Rydberg atom whose outermost electron creates a chemical bond with a distant ground state atom. Such multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number. The resulting occurrence of near degeneracies with states of high orbital angular momentum promotes the admixture of low l into the high l deeply bound "trilobite" molecule states, thereby circumventing the usual difficulty posed by electric dipole selection rules. Such states also can exhibit multiscale binding possibilities that could present novel options for quantum manipulation. PMID:26588378

  4. Production and trapping of cold circular Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Anderson, D. A.; Schwarzkopf, A.; Sapiro, R. E.; Raithel, G.

    2013-09-01

    Cold circular Rydberg atoms are produced and magnetically trapped. The trap is characterized by direct spatial imaging of ion distributions, ion counting, and state-selective field ionization. At room temperature, we observe about 70% of the trapped atoms remaining after 6 ms. We measure a trap oscillation frequency increase of the circular Rydberg atom trap relative to the ground-state atom trap due to the larger magnetic moment of the circular Rydberg atoms. Simulations of the center-of-mass and internal-state evolution of circular states in our magnetic trap are performed and results are in good agreement with experimental observations.

  5. 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

    Li, Shaohong L.; Truhlar, Donald G.

    2014-09-14

    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.

  6. Classical description of charge exchange involving He-like or Li-like ions in Rydberg states in plasmas

    NASA Astrophysics Data System (ADS)

    Kryukov, N.; Oks, E.

    2016-02-01

    A purely classical description of energy terms of one-electron Rydberg quasimolecules (hereafter, RQ1) consisting of one electron and two fully stripped ions of charges Z and Z‧, where Z‧ ≠ Z, had been previously published by one of us. The analysis of the crossings of the energy terms led to a classical description of charge exchange either between a hydrogen-like ion of the nuclear charge Z with a fully stripped ion of the charge Z‧ or between a hydrogen-like ion of the nuclear charge Z‧ with a fully stripped ion of the charge Z. Later applications included, e.g., the influence of electric and magnetic fields, as well as of the screening by plasma electrons. In the present paper we extend the classical description of energy terms to two-electron Rydberg quasimolecules (RQ2), consisting of two electrons and two fully stripped ions of charges Z and Z‧, and to three-electron Rydberg quasimolecules (RQ3), consisting of three electrons and two fully stripped ions of charges Z and Z‧. We show that classical energy terms of RQ2 and RQ3 also exhibit crossings like the energy terms of RQ1. The crossing of terms of RQ2 occurs at a larger internuclear distance compared to the crossing of the corresponding terms of RQ1, so that the cross-section of the charge exchange for RQ2 is larger than the corresponding cross-section for RQ1. The crossing of terms of RQ3 occurs at an even larger internuclear distance compared to the crossing of the corresponding terms of RQ2, so that the cross-section of the charge exchange for RQ3 is even larger than the corresponding cross-section for RQ2. Thus, the classical roots of charge exchange are revealed not only by the example of RQ1 systems, but also by the examples of RQ2 and RQ3 systems. Our results contribute to advance the understanding of the quantum-classical correspondence and can be used in applications where charge exchange plays the key role.

  7. Spin squeezing in a Rydberg lattice clock.

    PubMed

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

    2014-03-14

    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

  8. Direct detection of Rydberg-Rydberg millimeter-wave transitions in a buffer gas cooled molecular beam

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Grimes, David D.; Barnum, Timothy J.; Patterson, David; Coy, Stephen L.; Klein, Ethan; Muenter, John S.; Field, Robert W.

    2015-11-01

    Millimeter-wave transitions between molecular Rydberg states (n ∼ 35) of barium monofluoride are directly detected via Free Induction Decay (FID). Two powerful technologies are used in combination: Chirped-Pulse millimeter-Wave (CPmmW) spectroscopy and a buffer gas cooled molecular beam photoablation source. Hundreds of Rydberg-Rydberg transitions are recorded in 1 h with >10:1 signal:noise ratio and ∼150 kHz resolution. This high resolution, high spectral velocity experiment promises new strategies for rapid measurements of structural and dynamical information, such as the electric structure (multipole moments and polarizabilities) of the molecular ion-core and the strengths and mechanisms of resonances between Rydberg electron and ion-core motions. Direct measurements of Rydberg-Rydberg transitions with kilo-Debye dipole moments support efficient and definitive spectral analysis techniques, such as the Stark demolition and polarization diagnostics, which enable semi-automatic assignments of core-nonpenetrating Rydberg states. In addition, extremely strong radiation-mediated collective effects (superradiance) in a dense Rydberg gas of barium atoms are observed.

  9. Quantum dynamics with strongly interacting Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Zhou, Lu; Zhao, Xingdong; Zhang, Weiping; East China Normal University Collaboration; Henan Normal University Collaboration

    2014-03-01

    Rydberg atoms with high principal quantum number have exaggerated atomic properties, including strong dipole-dipole interactions, long radiative lifetimes and so on. These properties can provide intriguing routes to study attractive quantum many-body dynamics. In this talk, we present three research works with strongly interacting Rydberg atoms. We study quantum non-equilibrium phases of Rydberg atoms in cubic and triangular optical lattices and find exotic quantum phases such as uniform phase, antiferromagnetic phase, and oscillatory phase. In some parameter areas, bi-stability phase can be observable. Except that, in a triangle lattice, we also identify dynamical chaos effect in the strong-interaction limit. Besides, depending on the strong dipole-dipole interactions between Rydberg states, Rydberg blockade effect appears. In a more recent work, we find the effective two-atom-blockade spherical model can reveal anisotropic deformation and shrunken properties when the real number of atoms increases from two to three in few-tom systems. These results will all be discussed in the talk. We acknowledge support from NSFC No. 11104076 and the Specialized Research Fund for the Doctoral Program of Higher Education No.20110076120004.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  11. Strong-field excitation of helium: bound state distribution and spin effects.

    PubMed

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

    2015-03-27

    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. PMID:25860739

  12. Photonic Controlled-Phase Gate Based on Rydberg Interactions

    NASA Astrophysics Data System (ADS)

    Khazali, Mohammadsadegh; Heshami, Khabat; Simon, Christoph

    2015-03-01

    Photons are ideal carriers of information in quantum communication. Since they do not interact, the implementation of deterministic photonic quantum computation depends on the creation of a non-permanent strong interaction between single photons. The implementation of neutral Rydberg atom gates inspired the development of photonic gates, using the coherent reversible mapping of the quantum states of photons onto highly interacting Rydberg atoms. Here we propose an interaction-based two-qubit gate between photons stored in Rydberg levels of an atomic ensemble. We perform a detailed study of errors due to the many-body interaction between Rydberg spin-waves, and we propose a compensation scheme for these errors. Furthermore we completely separate interaction and propagation by eliminating the Rydberg level from the storage process. Our proposed controlled-phase gate can achieve 99% fidelity with current technology.

  13. Filtering single atoms from Rydberg-blockaded mesoscopic ensembles

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    We propose an efficient method to filter out single atoms from trapped ensembles with unknown numbers 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.

  14. Exciton dynamics in emergent Rydberg lattices

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  15. Transition rates for a Rydberg atom surrounded by a plasma

    NASA Astrophysics Data System (ADS)

    Lin, Chengliang; Gocke, Christian; Röpke, Gerd; Reinholz, Heidi

    2016-04-01

    We derive a quantum master equation for an atom coupled to a heat bath represented by a charged particle many-body environment. In the Born-Markov approximation, the influence of the plasma environment on the reduced system is described by the dynamical structure factor. Expressions for the profiles of spectral lines are obtained. Wave packets are introduced as robust states allowing for a quasiclassical description of Rydberg electrons. Transition rates for highly excited Rydberg levels are investigated. A circular-orbit wave-packet approach has been applied in order to describe the localization of electrons within Rydberg states. The calculated transition rates are in a good agreement with experimental data.

  16. Quantum Critical Behavior in Strongly Interacting Rydberg Gases

    SciTech Connect

    Weimer, Hendrik; Buechler, Hans Peter; Loew, Robert; Pfau, Tilman

    2008-12-19

    We study the appearance of correlated many-body phenomena in an ensemble of atoms driven resonantly into a strongly interacting Rydberg state. The ground state of the Hamiltonian describing the driven system exhibits a second order quantum phase transition. We derive the critical theory for the quantum phase transition and show that it describes the properties of the driven Rydberg system in the saturated regime. We find that the suppression of Rydberg excitations known as blockade phenomena exhibits an algebraic scaling law with a universal exponent.

  17. From molecular spectra to a density shift in dense Rydberg gases

    PubMed Central

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

    2014-01-01

    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. PMID:25082599

  18. Exotic Self-trapped States of an Electron in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Elser, Veit

    2015-09-01

    We explore the possibility that the fast and exotic negative ions in superfluid helium are electrons bound to quantized vortex structures, the simplest being a ring. In the states we consider, the electron energy is only slightly below the conduction band minimum of bulk helium. To support our proposal, we present two calculations. In the first, we show that the electron pressure on the vortex core is insufficient to cavitate the helium and form an electron bubble. In the second, we estimate the equilibrium radius of the vortex ring that would bind an electron and find it is much smaller than the electron bubble, about 7 Å. The many exotic ions reported in experiments might be bound states of an electron with more complex vortex structures.

  19. Dislocation-mediated melting of one-dimensional Rydberg crystals

    SciTech Connect

    Sela, Eran; Garst, Markus; Punk, Matthias

    2011-08-15

    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.

  20. Cavity quantum electrodynamics with a Rydberg-blocked atomic ensemble

    SciTech Connect

    Guerlin, Christine; Brion, Etienne; Esslinger, Tilman; Moelmer, Klaus

    2010-11-15

    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.

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

    SciTech Connect

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

    2011-08-26

    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}.

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

    PubMed

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

    2011-08-26

    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

  3. Equation of state and transport properties of warm dense helium via quantum molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Guo; Cheng, Yan; Chen, Qi-Feng; Chen, Xiang-Rong

    2016-05-01

    The equation of state, self-diffusion, and viscosity coefficients of helium have been investigated by quantum molecular dynamics (QMD) simulations in the warm dense matter regime. Our simulations are validated through the comparison with the reliable experimental data. The calculated principal and reshock Hugoniots of liquid helium are in good agreement with the gas-gun data. On this basis, we revisit the issue for helium, i.e., the possibility of the instabilities predicted by chemical models at around 2000 GPa and 10 g/cm3 along the pressure isotherms of 6309, 15 849, and 31 623 K. Our calculations show no indications of instability in this pressure-temperature region, which reconfirm the predictions of previous QMD simulations. The self-diffusion and viscosity coefficients of warm dense helium have been systematically investigated by the QMD simulations. We carefully test the finite-size effects and convergences of statistics, and obtain numerically converged self-diffusion and viscosity coefficients by using the Kubo-Green formulas. The present results have been used to evaluate the existing one component plasma models. Finally, the validation of the Stokes-Einstein relationship for helium in the warm dense regime is discussed.

  4. Production of very-high-n strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

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

    SciTech Connect

    Rudakov, Fedor M; Zhang, Zhili

    2012-01-01

    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.

  6. C-NOT gate based on ultracold Rydberg atom interactions

    NASA Astrophysics Data System (ADS)

    Rashid, Muhammad; Maarten, Hoogerland; Yasir, Jamil

    2013-11-01

    The Rydberg states of neutral atoms are strongly polarisable and possess long lifetimes because of high energies which can lead to strong and long range dipole-dipole interactions. The energy levels corresponding to these states are shifted because of dipole-dipole interactions and can be used to block transitions of more than one excitation in the Rydberg regime. This reputed Rydberg blockade is obtained when the excitation is shifted out of resonance by these interactions. Electromagnetically induced transparency (EIT) is sensitive to a small detuning. At large distances, up to several micrometers, the interactions can interrupt the EIT consequence. Herein we investigate a novel scheme based on EIT and Rydberg blockade and performed a simulation of a controlled-NOT (C-NOT) quantum gate which is critical for quantum computation by using neutral atoms.

  7. Asymptotic methods for Rydberg transitions

    NASA Astrophysics Data System (ADS)

    Dewangan, D. P.

    2012-02-01

    Quantum mechanical expressions of several important physical quantities like the hydrogen dipole matrix elements, line strength and form factors for several excitation processes have long been available in the literature in terms of the terminating hypergeometric functions but calculations from these expressions generally present serious numerical problems for large principal quantum numbers n and n‧. Determination of asymptotic and other appropriate approximations of these quantities for large n and n‧ has for long been posing challenge. We discuss a recent method that transforms the terminating hypergeometric functions into the Jacobi polynomials and exploits the properties of the Jacobi polynomials to provide a solution to the problem of the evaluation of these physical quantities. A noteworthy result of this method is that the exploitation of the recurrence relation of the Jacobi polynomials permits exact numerical calculations for various Rydberg processes for so large n,n‧˜2000 for which computation was usually not possible earlier. Another noteworthy outcome is that the method readily leads to a strikingly accurate expression of a Rydberg matrix element between nearby Rydberg states in terms of the Bessel functions, called an NRS-formula, which also helps to solve, without any recourse to classical and semiclassical arguments, a long standing problem of how to consistently derive the formula of classical mechanics obtained earlier by invoking the correspondence principle. The numerical results from the exact and approximate formulae of various quantum matrix elements presented in the article are so extensive that they reveal how various formulae including those of the correspondence principle convergence to their respective exact quantum expressions. Also, for numerical and analytical study of various matrix elements involving states lying near the continuum threshold, which have posed problems earlier, simpler quantum expressions are presented. The quantum expressions presented in the article provide nearly complete solutions over the hydrogenic bound-state spectrum for the calculation of several physical quantities like the radial dipole matrix element, line strength and form factors for transitions between arbitrary s states and between arbitrary circular states.

  8. EDITORIAL: Special issue on Rydberg physics

    NASA Astrophysics Data System (ADS)

    Côté, Robin; Pattard, Thomas; Weidemüller, Matthias

    2005-01-01

    Atoms and molecules in highly excited electronic states ('Rydberg atoms') have been the object of broad scientific research for almost a century. Despite this long history, the field of research has never lost its buoyancy, and recent years in particular have seen a tremendous revival of interest in the physics of Rydberg atoms and molecules from many different perspectives. Rydberg systems touch a wide range of research areas including, among others, ultralong-range molecules, artificial ('designer') atoms, quantum chaos, quantum information, ultracold Rydberg gases and plasmas, and anti-hydrogen formation. Due to the many fields involved, the physical insight and technical know-how are scattered over different communities. The goal of this special issue is to provide an integral overview of the latest developments in this highly innovative research field and to make the physical knowledge available to a wide audience. Groups from various fields of atomic, molecular and optical physics as well as condensed matter and plasma physics have contributed to this issue, which therefore spans a wide range of areas connected through the common theme: 'Rydberg physics'. This name was given to a four-week International Workshop and Seminar which was held from 19 April to 14 May 2004 at the Max-Planck-Institut für Physik Komplexer Systeme in Dresden, Germany, and organized by the three of us. The workshop and seminar programme was a very successful mixture of topics bringing together colleagues working in different but related areas of research centred about the physics of highly excited Rydberg atoms and molecules. We would like to take this opportunity to express our gratitude to the organization team of the MPI-PKS Dresden, especially the Director, Jan-Michael Rost, and the Visitors' Programme coordinator, Mandy Lochar. The generous support of the Max Planck Society, which made this successful workshop and seminar possible, is also gratefully acknowledged. Inspired by the great response to the 'Rydberg physics' conference we thought that it would be timely and appropriate to recognize the importance of Rydberg physics with a special issue of a scientific journal. The 'unbureaucratic' and highly efficient editorial and publishing team of Journal of Physics B: Atomic, Molecular and Optical Physics (J. Phys. B) allowed this to become a reality; it was a real pleasure for us to serve as guest editors. Unlike a conventional conference proceedings, this special issue has not been restricted to participants of the 'Rydberg physics' conference, and all the original papers contained in it have been peer-reviewed to the usual high standards of J. Phys. B. The variety and integrated discussion on the physics of Rydberg systems during the 'Rydberg physics' conference is reflected in the papers presented here. We have tried to group the papers according to the subject areas which are addressed. The first part of this special issue is devoted to high-resolution spectroscopy revealing deeper insights into the structure of Rydberg atoms and molecules as well as electronic interaction processes. The second part contains experimental and theoretical investigations on the influence of external static and oscillatory fields on Rydberg atoms. The third part takes account of the newly established field of ultracold Rydberg gases and plasmas with special emphasis on the appearance of ultralong-range interactions in these systems. Finally, the issue is concluded by articles on new developments including 'exotic' Rydberg systems. We would like to thank all of the participants of the 'Rydberg physics' workshop and seminar, and, in particular, the contributors to this special collection of papers, for their involvement. We are deeply indebted to the J. Phys. B editorial and publishing team both for making its realization possible in an extremely efficient way, and for the journal's commitment to the physics of Rydberg systems. We are impressed by the continuing progress in this fascinating and rapidly growing field of research and we look forward to many more thrilling and surprising achievements.

  9. Search for Positron Bound States in the Doubly Excited Region of the Helium Atom

    NASA Astrophysics Data System (ADS)

    Boadle, Roisin; Machacek, Joshua; Anderson, Emma; Sullivan, James; Buckman, Stephen

    2012-10-01

    Positron-atom binding has been the subject of many theoretical calculations in recent years. In these systems, a positron becomes temporarily bound to the atom, either through polarisation of the electronic charge cloud or formation of positronium (an e^-e^+ pair) which is weakly bound to the atom. There is now theoretical evidence of numerous positron-atom bound states, including for the helium atom. Ground state helium is incapable of binding a positron; however, recent calculations [1] have indicated that excited metastable states and doubly excited states may do so. These bound states might be expected to manifest themselves as structure in the energy dependence of the cross sections for processes such as total scattering, positronium formation, or ionization. We have carried out an experimental search for these positronic helium states in the doubly-excited region near 58 eV, using our high-resolution, trap-based positron beam. Results from this study will be presented and their ramifications discussed. [4pt] [1] M.J. Bromley and J. Mitroy Private Communication (2012)

  10. Rydberg atoms in hollow-core photonic crystal fibres

    PubMed Central

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

    2014-01-01

    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

  11. The role of Rydberg states in photoionization of NO2 and (NO+, O-) ion pair formation induced by one VUV photon.

    PubMed

    Poullain, S Marggi; Veyrinas, K; Billaud, P; Lebech, M; Picard, Y J; Lucchese, R R; Dowek, D

    2013-07-28

    We report a combined experimental and theoretical study of photoionization (PI) of the NO2 molecule into the NO2(+) (X (1)Σg(+)) ground state and the photodissociation of NO2 into the NO(+)((1)Σ(+)) + O(-)((2)P) ion pair. These processes were induced by 10.9 eV-13 eV synchrotron radiation and the products were detected using electron-ion or O(-)-NO(+) coincident momentum spectroscopy. The results demonstrate the strong influence of [R(∗)(4b2)(-1), nlα(i), v2(')] Rydberg states vibrationally resolved in the v2(') bending modes for both processes. In particular, we emphasize two regions around 11.5 eV and 12.5 eV that were studied in more detail for their relevance to 400 nm multiphoton ionization induced by femtosecond pulses. The photoelectron energy spectra and asymmetry parameters support the existence of two PI mechanisms, as probed with the help of fixed-nuclei frozen-core Hartree-Fock calculations. We found significant deviations from Franck-Condon ionization predictions which may be assigned to vibronic coupling of NO2(∗) states such as that induced by a conical intersection. The limited agreement between theory and experiment, even for the non-resonant processes, indicates the need for calculations that go beyond the approximations used in the current study. Ion pair formation leads to strong vibrational and rotational excitation of the NO(+)((1)Σ(+),v) product, with an ion fragment angular anisotropy depending on both the v2(') bending quantum number of the excited parent molecule and the v vibrational level of the fragment. PMID:23901984

  12. Theoretical research of helium pulsating heat pipe under steady state conditions

    NASA Astrophysics Data System (ADS)

    Xu, D.; Liu, H. M.; Li, L. F.; Huang, R. J.; Wang, W.

    2015-12-01

    As a new-type heat pipe, pulsating heat pipe (PHP) has several outstanding features, such as great heat transport ability, strong adjustability, small size and simple construction. PHP is a complex two-phase flow system associated with many physical subjects and parameters, which utilizes the pressure and temperature changes in volume expansion and contraction during phase changes to excite the pulsation motion of liquid plugs and vapor bubbles in the capillary tube between the evaporator and the condenser. At present time, some experimental investigation of helium PHP have been done. However, theoretical research of helium PHP is rare. In this paper, the physical and mathematical models of operating mechanism for helium PHP under steady state are established based on the conservation of mass, momentum, and energy. Several important parameters are correlated and solved, including the liquid filling ratio, flow velocity, heat power, temperature, etc. Based on the results, the operational driving force and flow resistances of helium PHP are analysed, and the flow and heat transfer is further studied.

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

    SciTech Connect

    Aquino, N.

    2014-01-14

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

  14. Doubly excited states of the hydrogen negative ion and helium atom in astrophysical plasmas

    SciTech Connect

    Jiang Pinghui; Kar, Sabyasachi; Zhou, Y.

    2013-01-15

    The nonthermal effects on the doubly excited resonance states of the hydrogen negative ion and helium atom are investigated in Lorentzian astrophysical plasma environments using highly correlated Hylleraas-type wave functions in the framework of the stabilization method. Resonance parameters (resonance position and width) are reported for the first time as functions of the spectral index and plasma parameter. The screening effects are more pronounced in the stronger screening region.

  15. Anomalous Broadening in Driven Dissipative Rydberg Systems

    NASA Astrophysics Data System (ADS)

    Goldschmidt, E. A.; Boulier, T.; Brown, R. C.; Koller, S. B.; Young, J. T.; Gorshkov, A. V.; Rolston, S. L.; Porto, J. V.

    2016-03-01

    We observe interaction-induced broadening of the two-photon 5 s -18 s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly 2 orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18 s atoms with blackbody induced population in nearby n p states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.

  16. Anomalous Broadening in Driven Dissipative Rydberg Systems.

    PubMed

    Goldschmidt, E A; Boulier, T; Brown, R C; Koller, S B; Young, J T; Gorshkov, A V; Rolston, S L; Porto, J V

    2016-03-18

    We observe interaction-induced broadening of the two-photon 5s-18s transition in ^{87}Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly 2 orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with blackbody induced population in nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms. PMID:27035299

  17. Recurrence Spectroscopy of Autoionizing Rydberg Argon

    NASA Astrophysics Data System (ADS)

    Wright, J. D.; Walker, P. A.; Gurian, J. H.; van Lier-Walqui, M.; Lambert, J. M.; Flores-Rueda, H.; Morgan, T. J.

    2004-05-01

    We have extended scaled energy spectroscopy of meta-stable argon to measure Rydberg states above the first ionization limit. Prior measurements [1] showed a principal Rydberg series converging to the ground state of the Ar+ ion. The spectra also showed strong perturbing resonances of the Rydberg electron orbiting an excited ion core. New experiments show that single uv-photon excitation of the meta-stable state can produce strong transitions to doubly excited states above the first ionization limit. In this auto-ionizing regime the electron escapes leaving behind an excited ion core. The excitation creates an electron-hole pair which interacts with the rest of the atom. This three body system provides an opportunity to test extensions of closed orbit theory [2,3] and experimentally probe the classical dynamics using recurrence spectroscopy. Work supported by National Science Foundation. [1] M.L. Keeler, J.D. Wright, H. Flores-Rueda, and T.J. Morgan, J. Phys. B (to be published) [2] B.E. Granger and C.H. Green, PRA 62, 12511 (2000) [3] W. Huang and T.J. Morgan, PRA 65 033409 (2002)

  18. Observation of luminescence spectra of KrD Rydberg molecule at low (40K) temperature

    SciTech Connect

    Pelmenev, A.A.; Gordon, E.B.; Khmelenko, V.V.; Martynenko, M.V.; Popov, E.A.

    1996-12-31

    The luminescence spectra of KrD Rydberg molecule in the spectral range from 400 nm to 800 nm in the gas phase at low temperatures (40K) were observed for the first time by means of original experimental technique. In this method, two gas jets were intersected over the surface of superfluid helium (temperature 1.5K, pressure of helium vapor 10 torr). Gas mixture of He with frequency electrodeless discharge. The resulting luminescent jet was introduced in a helium cryostat and crossed by a stream of H{sub 2} or D{sub 2} molecules to produce RgH or RgD. First experiments with Kr and D{sub 2} were carried out. A number of bands observed in the luminescence spectra were assigned to KrD extensively studied by Dabrowski et al. The most pronounced bands observed at 515 nm and 773 nm originate from 4d state and correspond to transitions to 5p states. Transitions from the np complexes were also identified but their intensity was much weaker. Near 483 nm there was a rather broad band assigned to transitions from nf complexes. The luminescence spectra of nitrogen molecules and ions, and CN radicals at such low temperatures were also studied and a number of peculiarities in the spectra were observed. These results will be presented as well.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  20. Electrostatic trapping and in situ detection of Rydberg atoms above chip-based transmission lines

    NASA Astrophysics Data System (ADS)

    Lancuba, P.; Hogan, S. D.

    2016-04-01

    Beams of helium atoms in Rydberg-Stark states with principal quantum number n = 48 and electric dipole moments of 4600 D have been decelerated from a mean initial longitudinal speed of 2000 m s-1 to zero velocity in the laboratory-fixed frame-of-reference in the continuously moving electric traps of a transmission-line decelerator. In this process accelerations up to -1.3× {10}7 m s-2 were applied, and changes in kinetic energy of {{Δ }}{E}{kin}=1.3× {10}-20 J ({{Δ }}{E}{kin}/e=83 meV) per atom were achieved. Guided and decelerated atoms, and those confined in stationary electrostatic traps, were detected in situ by pulsed electric field ionisation. The results of numerical calculations of particle trajectories within the decelerator have been used to characterise the observed deceleration efficiencies, and aid in the interpretation of the experimental data.

  1. Bethe logarithm for the 1 1S and 2 1S states of helium

    NASA Astrophysics Data System (ADS)

    Korobov, V. I.; Korobov, S. V.

    1999-05-01

    We present variational calculations of the Bethe logarithm for the 1 1S and 2 1S states of helium. The approach is based on the explicit second-order perturbation formula and closely follows the method of Schwartz. The final values are ln[K0(1 1S)/(1 Ry)]=4.370 157 9(5) and ln[K0(2 1S)/(1 Ry)]=4.366 409 1(7). The latter result reduces the difference between theoretical and experimental values for the ionization potential of the 2 1S state to 0.15 MHz.

  2. Test of the Pluvinage wave function for the helium ground state

    NASA Astrophysics Data System (ADS)

    Jones, S.; Macek, Joseph H.; Madison, D. H.

    2004-07-01

    The accuracy of the Pluvinage wave function for the ground state of helium is investigated by considering a number of different physical processes including double ionization by photoabsorption, Compton scattering, and electron impact. In the high-energy limit of these processes, the accuracy of the initial ground state can be ascertained without reference to the final double-continuum state. In this limit, we find that a Hylleraas description is superior to the Pluvinage one. For intermediate energies, final-state correlation becomes important, so we employ a 3C description of the final state (the 3C wave function is the double-continuum analog of the Pluvinage wave function). In this case, however, better agreement with experiment is obtained with the Pluvinage initial state. A possible explanation for this seemingly paradoxical result is suggested.

  3. Lifetimes of ultra-long-range strontium Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Camargo, F.; Whalen, J. Â. D.; Ding, R.; Sadeghpour, H. R.; Yoshida, S.; Burgdörfer, J.; Dunning, F. B.; Killian, T. C.

    2016-02-01

    The lifetimes of the lower-lying vibrational states of ultra-long-range strontium Rydberg molecules comprising one ground-state 5 s2 1S0 atom and one Rydberg atom in the 5 s 38 s 3S1 state are reported. The molecules are created in an ultracold gas held in an optical dipole trap and their numbers determined using field ionization, the product electrons being detected by a microchannel plate. The measurements show that, in marked contrast to earlier measurements involving rubidium Rydberg molecules, the lifetimes of the low-lying molecular vibrational states are very similar to those of the parent Rydberg atoms. This results because the strong p -wave resonance in low-energy electron-rubidium scattering, which strongly influences the rubidium molecular lifetimes, is not present for strontium. The absence of this resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing of theories of molecular formation and decay.

  4. Absence of Collective Decay in a Cold Rydberg Gas

    NASA Astrophysics Data System (ADS)

    Zhou, Tao; Richards, B. G.; Jones, R. R.

    2015-05-01

    We have studied the decay of Rydberg excitations in a cold Rb gas. A 10 ns, pulsed dye-amplified diode laser drives Rb 5 p atoms at 70 μK in a MOT to ns or np Rydberg states. Excitation of np states is facilitated by Stark mixing in a small static electric field. Time-delayed state-selective field ionization (SSFI) is used to directly monitor the population in the initial and neighboring Rydberg levels. We find that the time-dependence of the Rydberg population is well described by numerical simulations which consider only spontaneous emission and stimulated emission and absorption of black-body radiation. No signature of collective decay phenomena is observed. In contrast, previous studies performed at similar atom density and laser focal volume conditions, but at slightly higher principal quantum number and without state resolved population detection, reported evidence of very rapid Rydberg decay that was attributed to superradiance. This work has been supported by the NSF.

  5. Carbon synthesis in steady-state hydrogen and helium burning on accreting neutron stars

    SciTech Connect

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

    2014-08-20

    Superbursts from accreting neutron stars probe nuclear reactions at extreme densities (ρ ≈ 10{sup 9} g cm{sup –3}) and temperatures (T > 10{sup 9} 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 {sup 14}O(α, p){sup 17}F reaction rate introduces by far the largest uncertainties in the {sup 12}C yield.

  6. Magic-wavelength optical traps for Rydberg atoms

    SciTech Connect

    Zhang, S.; Saffman, M.; Robicheaux, F.

    2011-10-15

    We propose blue-detuned optical traps that are suitable for trapping of both ground-state and Rydberg excited atoms. The addition of a background compensation field or a suitable choice of the trap geometry provides a magic trapping condition for ground-state and Rydberg atoms at the trap center. Deviations from the magic condition at finite temperature are calculated. Designs that achieve less than 200-kHz differential trap shift between Cs ground states and 125s Rydberg states for 10 {mu}K Cs atoms are presented. Consideration of the trapping potential and photoionization rates suggests that these traps will be useful for quantum-information experiments with atomic qubits.

  7. Strong photon blockade with intracavity electromagnetically induced transparency in a blockaded Rydberg ensemble

    NASA Astrophysics Data System (ADS)

    Lin, G. W.; Qi, Y. H.; Lin, X. M.; Niu, Y. P.; Gong, S. Q.

    2015-10-01

    We consider the dynamics of intracavity electromagnetically induced transparency (EIT) in an ensemble of strongly interacting Rydberg atoms. By combining the advantage of variable cavity lifetimes with intracavity EIT and strongly interacting Rydberg dark-state polaritons, we show that such an intracavity EIT system could exhibit a very strong photon blockade effect.

  8. (Electronic structure of helium and hydride complexes)

    SciTech Connect

    1981-01-01

    Research on the electronic structure of weakly bound helium and hydrogen species is described. The work grew from interest in a remarkable experimental observation at Los Alamos which shows that the helium generated from radioactive decay of liquid tritium remains in solution at concentrations which exceed the known solubility by much more than a factor of 100. The understanding of this supersolubility phenomenon is a challenging problem with significant implications for other condensed phase systems. In the hope of discovering the mechanism of the supersolubility, electronic structure calculations were carried out employing several methods to evaluate the binding energies of complexes of the form He(H/sup +/) (H/sub 2/)/sub n/, with n = 2, 3, 4. For comparison, similar calculations were made for the complexes H/sub 2/(H/sup +/) (H/sub 2/)/sub n/. Also, the binding of the negative counter-ion species of the form (H/sup -/) (H/sub 2/)/sub n/ was calculated. Although the calculations show that such complexes have sufficient binding energy to account for the enhanced solubility at the low temperature (20 K) of interest, major questions remain to be clarified. These include the mechanism for formation of the complexes, which may well involve excited, Rydberg-like states in solution. Another quite crucial question is how such weak complexes could persist in solution for months without displacement of the He by solvent molecules. Theoretical calculations focus on three topics: (1) Rydberg states; (2) condensed phase interactions; and (3) estimates of ionic conductivity in tritium solutions, as an aid to the interpretation of experiments now underway at Los Alamos. (WHK)

  9. Rydberg blockade effects at n ˜300 in strontium

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Dunning, F. B.; Yoshida, S.; Burgdörfer, J.

    2015-11-01

    Rydberg blockade at n ˜300 , is examined using strontium n F13 Rydberg atoms excited in an atomic beam in a small volume defined by two tightly focused crossed laser beams. The observation of blockade for such states is challenging due to their extreme sensitivity to stray fields and the many magnetic sublevels associated with F states which results in a high local density of states. Nonetheless, with a careful choice of laser polarization to selectively excite only a limited number of these sublevels, sizable blockade effects are observed on an ˜0.1 mm length scale extending blockade measurements into the near-macroscopic regime and enabling study of the dynamics of strongly coupled many-body high-n Rydberg systems under carefully controlled conditions.

  10. Stationary three-dimensional entanglement via dissipative Rydberg pumping

    NASA Astrophysics Data System (ADS)

    Shao, Xiao-Qiang; You, Jia-Bin; Zheng, Tai-Yu; Oh, C. H.; Zhang, Shou

    2014-05-01

    We extend the recent result of a bipartite Bell singlet [A. W. Carr and M. Saffman, Phys. Rev. Lett. 111, 033607 (2013), 10.1103/PhysRevLett.111.033607] to a stationary three-dimensional entanglement between two-individual neutral Rydberg atoms. This proposal makes full use of the coherent dynamics provided by a Rydberg-mediated interaction and the dissipative factor originating from the spontaneous emission of a Rydberg state. The numerical simulation of the master equation reveals that both the target state negativity N (ρ̂∞) and fidelity F (ρ̂∞) can exceed 99.90%. Furthermore, a steady three-atom singlet state |S3> is also achievable based on the same mechanism.

  11. Simplified scheme for entanglement preparation with Rydberg pumping via dissipation

    NASA Astrophysics Data System (ADS)

    Su, Shi-Lei; Guo, Qi; Wang, Hong-Fu; Zhang, Shou

    2015-08-01

    Inspired by recent work [Carr and Saffman, Phys. Rev. Lett. 111, 033607 (2013), 10.1103/PhysRevLett.111.033607], we propose a simplified scheme to prepare the two-atom maximally entangled states via dissipative Rydberg pumping. Compared with the former scheme, the simplified one involves fewer classical laser fields and Rydberg interactions, and the asymmetric Rydberg interactions are avoided. Master equation simulations demonstrate that the fidelity and the Clauser-Horne-Shimony-Holt correlation of the maximally entangled state could reach up to 0.999 and 2.821, respectively, under certain conditions. Furthermore, we extend the physical thoughts to prepare the three-dimensional entangled state, and the numerical simulations show that, in theory, both the fidelity and the negativity of the desired entanglement could be very close to unity under certain conditions.

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

    SciTech Connect

    Caradonna, Peter; Sullivan, James P.; Jones, Adric; Makochekanwa, Casten; Slaughter, Daniel; Mueller, Dennis W.; Buckman, Stephen J.

    2009-12-15

    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.

  13. Rapid and precise scanning helium ion microscope milling of solid-state nanopores for biomolecule detection

    SciTech Connect

    Yang, Jijin; Ferranti, David C; Stern, Lewis A; Sanford, Colin A; Huang, Jason; Ren, Zheng; Qin, Lu-Chang; Hall, Adam R

    2011-06-10

    We report the formation of solid-state nanopores using a scanning helium ion microscope. The fabrication process offers the advantage of high sample throughput along with fine control over nanopore dimensions, producing single pores with diameters below 4 nm. Electronic noise associated with ion transport through the resultant pores is found to be comparable with levels measured on devices made with the established technique of transmission electron microscope milling. We demonstrate the utility of our nanopores for biomolecular analysis by measuring the passage of double-strand DNA.

  14. Learning Approach on the Ground State Energy Calculation of Helium Atom

    SciTech Connect

    Shah, Syed Naseem Hussain

    2010-07-28

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

  15. Rydberg-blockade effects in Autler-Townes spectra of ultracold strontium

    NASA Astrophysics Data System (ADS)

    DeSalvo, B. J.; Aman, J. A.; Gaul, C.; Pohl, T.; Yoshida, S.; Burgdörfer, J.; Hazzard, K. R. A.; Dunning, F. B.; Killian, T. C.

    2016-02-01

    We present a combined experimental and theoretical study of the effects of Rydberg interactions on Autler-Townes spectra of ultracold gases of atomic strontium. Realizing two-photon Rydberg excitation via a long-lived triplet state allows us to probe the regime where Rydberg state decay presents the dominant decoherence mechanism. The effects of Rydberg interactions are observed in shifts, asymmetries, and broadening of the measured atom-loss spectra. The experiment is analyzed within a one-body density-matrix approach, accounting for interaction-induced level shifts and dephasing through nonlinear terms that approximately incorporate correlations due to the Rydberg blockade. This description yields good agreement with our experimental observations for short excitation times. For longer excitation times, the loss spectrum is altered qualitatively, suggesting additional dephasing mechanisms beyond the standard blockade mechanism based on pure van der Waals interactions.

  16. Phase-Imprinting of Bose-Einstein Condensates with Rydberg Impurities.

    PubMed

    Mukherjee, Rick; Ates, Cenap; Li, Weibin; Wster, Sebastian

    2015-07-24

    We show how the phase profile of Bose-Einstein condensates can be engineered through its interaction with localized Rydberg excitations. The interaction is made controllable and long range by off-resonantly coupling the condensate to another Rydberg state with laser light. Our technique allows the mapping of entanglement generated in systems of few strongly interacting Rydberg atoms onto much larger atom clouds in hybrid setups. As an example we discuss the creation of a spatial mesoscopic superposition state from a bright soliton. Additionally, the phase imprinted onto the condensate using the Rydberg excitations is a diagnostic tool for the latter. For example, a condensate time-of-flight image would permit reconstructing the pattern of an embedded Rydberg crystal. PMID:26252669

  17. Systematics of Rydberg Series of Diatomic Molecules and Correlation Diagrams

    NASA Astrophysics Data System (ADS)

    Lee, Chun-Woo

    2015-06-01

    Rydberg states are studied for H2, Li2, HeH, LiH and BeH using the multi-reference configuration interaction (MRCI) method. The systematics and regularities of the physical properties such as potential energies curves (PECs), quantum defect curves, permanent dipole moment and transition dipole moment curves of the Rydberg series are studied. They are explained using united atom perturbation theory by Bingel and Byers-Brown, Fermi model, Stark theory, and Mulliken's theory. Interesting mirror relationships of the dipole moments are observed between l-mixed Rydberg series, indicating that the members of the l-mixed Rydberg series have dipole moments with opposite directions, which are related to the reversal of the polarity of a dipole moment at the avoided crossing points. The assignment of highly excited states is difficult because of the usual absence of the knowledge on the behaviors of potential energy curves at small internuclear separation whereby the correlation between the united atom limit and separated atoms limit cannot be given. All electron MRCI calculations of PECs are performed to obtain the correlation diagrams between Rydberg orbitals at the united-atom and separated atoms limits.

  18. Interactions of circular Rydberg atoms with charged particles

    SciTech Connect

    Wang, J.

    1994-12-31

    Recent progress in experimental cross-field techniques has made it possible to produce oriented Rydberg atoms of any angular momentum l within a given n manifold. The largest angular momentum state l{sup max}= n - 1 of a given n manifold is of particular interest because of its semiclassical properties for n{much_gt}1. The corresponding classical Kepler orbit is circular with highly localized phase space distribution. The circular Rydberg atoms afford the opportunity to study various interactions in the semiclassical regime. The authors report electron capture from circular Rydberg atoms by protons and positrons at speeds comparable to the electron orbital speed. They find orientation dependent, novel peak structures for both protons and positrons in the angular scattering of the particles. The structures may be understood in terms of quasi Thomas double scattering mechanism for capture. Other related aspects including final state population and orientation indulged scattering asymmetry will also be discussed.

  19. Superposition of Fragment Excitations for Excited States of Large Clusters with Application to Helium Clusters.

    PubMed

    Closser, Kristina D; Ge, Qinghui; Mao, Yuezhi; Shao, Yihan; Head-Gordon, Martin

    2015-12-01

    We develop a local excited-state method, based on the configuration interaction singles (CIS) wave function, for large atomic and molecular clusters. This method exploits the properties of absolutely localized molecular orbitals (ALMOs), which strictly limits the total number of excitations, and results in formal scaling with the third power of the system size for computing the full spectrum of ALMO-CIS excited states. The derivation of the equations and design of the algorithm are discussed in detail, with particular emphasis on the computational scaling. Clusters containing ∼500 atoms were used in evaluating the scaling, which agrees with the theoretical predictions, and the accuracy of the method is evaluated with respect to standard CIS. A pioneering application to the size dependence of the helium cluster spectrum is also presented for clusters of 25-231 atoms, the largest of which results in the computation of 2310 excited states per sampled cluster geometry. PMID:26609558

  20. Slow-light polaritons in Rydberg gases

    NASA Astrophysics Data System (ADS)

    Fleischhauer, Michael

    2012-02-01

    Slow-light polaritons are quasi-particles generated in the interaction of photons with laser-driven atoms with a λ- or ladder-type coupling scheme under conditions of electromagnetically induced transparency (EIT). They are a superposition of electromagnetic and collective spin excitations. If one of the states making up the atomic spin is a high lying Rydberg level, the polaritons are subject to a strong and non-local interaction mediated by a dipole-dipole or van-der Waals coupling between excited Rydberg atoms. I will present and discuss an effective many-body model for these Rydberg polaritons. Depending on the detuning of the control laser the interaction potential between the polaritons can be repulsive or attractive and can have a large imaginary component for distances less than the so-called blockade radius. The non-local effective interaction gives rize to interesting many-body phenomena such as the generation of photons with an avoided volume, visible in stronlgy suppressed two-particle correlations inside the blockade volume. Moreover the long-range, power-law scaling of the interaction can in the repulsive case give rize to the formation of quasi-crystalline structures of photons. In a one dimensional system the low-energy dynamics of the polaritons can be described in terms of a Luttinger liquid. Using DMRG simulations the Luttinger K parameter is calculated and conditions for the formation of a quasi-crystal are derived. When confined to a two-dimensional geometry, e.g. using a resonator with quasi-degenerate transversal mode spectrum, Rydberg polaritons are an interesting candidate to study the bosonic fractional quantum Hall effect. I will argue that the formation of photons with an avoided volume is essential for explaining recent experiments on stationary EIT in Rydberg gases [1,2].[4pt] [1] J.D. Pritchard et al., Phys. Rev. Lett. 105, 193603 (2010). [0pt] [2] D. Petrosyan, J. Otterbach, and M. Fleischhauer, arXiv:1106.1360

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

    SciTech Connect

    Closser, Kristina D.; Head-Gordon, Martin; Ultrafast X-Ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 ; Gessner, Oliver

    2014-04-07

    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.

  2. Deceleration and electrostatic trapping of hydrogen Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Hogan, Stephen

    2009-05-01

    Recent progress in the development of methods by which to decelerate and manipulate the translational motion of Rydberg atoms in the gas phase using static and time-varying inhomogeneous electric fields [1] has led to the experimental realization of Rydberg atom optics elements including a lens [2], a mirror [3] and two- and three-dimensional traps [4,5]. These experiments exploit the very large electric dipole moments associated with Rydberg Stark states, and have demonstrated the possibility to stop a seeded, pulsed, supersonic beam of atomic hydrogen traveling with an initial velocity of 700 ms-1 within 2 mm and only ˜5 μs using electric fields of a few kVcm-1. We have now extended these techniques to manipulate the translational motion of molecular hydrogen, for applications in precision spectroscopy and in studies of molecular collisions at low temperature or with a high degree of control over collision energies. The results of recent experiments in which we have been able to load hydrogen Rydberg molecules into a three-dimensional electrostatic traps will be summarized. These experiments have relied upon the preparation of nonpenetrating (l>=3) Rydberg-Stark states, with principal quantum number in the range n=20-30, using circularly polarized laser radiation. The rate of decay of these states in the trap has been determined providing, for the first time, experimental information on the predissociation of nonpenetrating molecular Rydberg states.[4pt] [1] S. R. Procter et al., Chem. Phys. Lett., 374, 667 (2003).[0pt] [2] E. Vliegen et al., Eur. Phys. J. D, 40, 73 (2006).[0pt] [3] E. Vliegen and F. Merkt, Phys. Rev. Lett., 97, 033002 (2006).[0pt] [4] E. Vliegen et al., Phys. Rev. A, 76, 023405 (2007).[0pt] [5] S. D. Hogan and F. Merkt, Phys. Rev. Lett., 100, 043001 (2008).

  3. Coherent manipulation by adiabatic passage of interacting Rydberg atoms inside a cavity

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Ewel, Charles; Sedlacek, Jonathon; Shaffer, James

    2014-05-01

    We investigate the coherent manipulation of interacting Rydberg atoms placed inside a cavity by using stimulated Raman adiabatic passage (STIRAP). In this approach, we consider a five-level double-ladder scheme with one common Rydberg level for N interacting atoms. One side of the ladder excites the atoms into the Rydberg level using counter-intuitive STIRAP pulses, while the other side of the ladder couples the atom to a cavity field. Due to the strong interaction between the atoms in the Rydberg level, the Rydberg blockade mechanism plays an important role in the manipulation of the atoms. We use numerical simulation to show that how one can generate non-classical states of light with this system. We consider how the decay mechanisms affect this interacting many-body system.

  4. Spatially resolved excitation of Rydberg atoms and surface effects on an atom chip

    SciTech Connect

    Tauschinsky, Atreju; Thijssen, Rutger M. T.; Whitlock, S.; Linden van den Heuvell, H. B. van; Spreeuw, R. J. C.

    2010-06-15

    We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold-coated chip surface. We measure distance-dependent shifts ({approx}10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. The measured field strength and distance dependence is in agreement with a simple model for the electric field produced by a localized patch of Rb adsorbates deposited on the chip surface during experiments. The EIT resonances remain narrow (<4 MHz) and the observed widths are independent of atom-surface distance down to {approx} 20 {mu}m, indicating relatively long lifetime of the Rydberg states. Our results open the way to studies of dipolar physics, collective excitations, quantum metrology, and quantum information processing involving interacting Rydberg excited atoms on atom chips.

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

    PubMed

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

    2015-08-25

    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 10 orders of magnitude below the desired chemical precision. As NV centers in diamond provide a robust and straightforward platform for quantum information processing, our work provides an important step toward a fully scalable solid-state implementation of a quantum chemistry simulator. PMID:25905564

  6. Mesoscopic Rydberg Impurity in an Atomic Quantum Gas

    NASA Astrophysics Data System (ADS)

    Schmidt, Richard; Sadeghpour, H. R.; Demler, E.

    2016-03-01

    Giant impurity excitations are powerful probes for exploring new regimes of far out of equilibrium dynamics in few- and many-body quantum systems, and in situ observations of correlations. Motivated by recent experimental progress in spectroscopic studies of Rydberg excitations in ultracold atoms, we develop a new theoretical approach for describing multiscale dynamics of Rydberg excitations in quantum Bose gases. We find that the crossover from few- to many-body dynamics manifests in a dramatic change in spectral profile from resolved molecular lines to broad Gaussian distributions representing a superpolaronic state in which many atoms bind to the Rydberg impurity. We discuss signatures of this crossover in the temperature and density dependence of the spectra.

  7. Mesoscopic Rydberg Impurity in an Atomic Quantum Gas.

    PubMed

    Schmidt, Richard; Sadeghpour, H R; Demler, E

    2016-03-11

    Giant impurity excitations are powerful probes for exploring new regimes of far out of equilibrium dynamics in few- and many-body quantum systems, and in situ observations of correlations. Motivated by recent experimental progress in spectroscopic studies of Rydberg excitations in ultracold atoms, we develop a new theoretical approach for describing multiscale dynamics of Rydberg excitations in quantum Bose gases. We find that the crossover from few- to many-body dynamics manifests in a dramatic change in spectral profile from resolved molecular lines to broad Gaussian distributions representing a superpolaronic state in which many atoms bind to the Rydberg impurity. We discuss signatures of this crossover in the temperature and density dependence of the spectra. PMID:27015490

  8. Driving Rydberg-Rydberg transitions with an amplitude-modulated optical lattice

    NASA Astrophysics Data System (ADS)

    Moore, Kaitlin; Anderson, Sarah; Raithel, Georg

    2014-05-01

    We demonstrate a novel spectroscopic method that couples Rydberg states using an amplitude-modulated optical lattice. The method is fundamentally different from traditional microwave spectroscopy: it engages the A2-term rather than the Ap -term of the atom-field interaction Hamiltonian. The method allows us to drive microwave transitions between Rydberg states with optical spatial resolution, and it is not subject to the usual electric-dipole selection rules. Both features are attractive for quantum computing and precision metrology, such as measuring an improved value for the dipolar polarizibility of the Rb ionic core. In the experiment, cold Rb Rydberg atoms are first excited and confined in an optical lattice of wavelength 1064 nm. Then, the electric-quadrupole transition 58 S --> 59 S is driven by modulating the intensity of the optical lattice using a tunable electro-optic fiber modulator. Maximum population transfer occurs at a lattice modulation frequency of 38.768610(30) GHz, in close agreement with calculations. We briefly explain the theoretical background of the new spectroscopic method, show experimental results and discuss applications. We acknowledge support from DOE SCGF and NSF.

  9. Orthogonal flexible Rydberg aggregates

    NASA Astrophysics Data System (ADS)

    Leonhardt, K.; Wüster, S.; Rost, J. M.

    2016-02-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali-metal atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable nonadiabatic effects. A joint exciton-motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of nonadiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K. Leonhardt et al., Phys. Rev. Lett. 113, 223001 (2014), 10.1103/PhysRevLett.113.223001]. In this article we discuss the underlying complex dynamics in detail, characterize the switch, and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.

  10. Absence of collective decay in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Zhou, Tao; Richards, B. G.; Jones, R. R.

    2016-03-01

    We have studied the decay of Rydberg excitations in a cold Rb gas. A 10 ns, pulsed-dye-amplified diode laser excites Rb atoms at 70 μ K in a magneto-optical trap to n s or n p Rydberg states with principal quantum numbers 26 ≤n ≤40 . Time-delayed state-selective field ionization is used to directly monitor the population in the initial and neighboring Rydberg levels. The measured time dependence of the Rydberg population is well described by numerical simulations which consider only spontaneous emission and population transfer by blackbody radiation. No evidence for collective decay is found at atom densities up to 3 ×109cm-3 . This result is in contrast to a previous study [Wang et al., Phys. Rev. A 75, 033802 (2007), 10.1103/PhysRevA.75.033802], in which superradiant decay was theoretically predicted and experimentally inferred for atom density and laser focal volume conditions very similar to those considered here. Suppression of collective emission is likely due to variations in transition energies within the atom sample, dominated by inhomogeneities in dipole-dipole exchange interactions for initial s states, or by a combination of dipole-dipole and electric field inhomogeneities for the initial p states.

  11. Measurement of the oscillator strength distribution in helium

    SciTech Connect

    Hussain, Shahid; Saleem, M.; Baig, M. A.

    2007-07-15

    The oscillator strength distribution in the discrete and continuous regions of the spectrum of helium from the 2s {sup 1}S{sub 0} metastable state has been determined using a Nd: yttrium aluminum garnet (YAG) pumped dye laser system in conjunction with a low pressure rf glow discharge. The saturation technique has been employed to determine the photoionization cross section from the 2s {sup 1}S{sub 0} excited state at and above the first ionization threshold. The measured value of the photoionization cross section at the ionization threshold has been used to extract the f values for the 2s {sup 1}S{yields}np {sup 1}P Rydberg series from n=10 to n=52. The f values of the observed Rydberg series decrease smoothly with an increase of the principal quantum number. In the continuum region the oscillator strength densities have been estimated by measuring the photoionization cross sections from the 2s {sup 1}S{sub 0} excited state at five ionizing laser wavelengths above the first ionization threshold. The discrete f values smoothly merge into the continuous oscillator strength densities across the ionization threshold.

  12. Measurement of the oscillator strength distribution in helium

    NASA Astrophysics Data System (ADS)

    Hussain, Shahid; Saleem, M.; Baig, M. A.

    2007-07-01

    The oscillator strength distribution in the discrete and continuous regions of the spectrum of helium from the 2sS01 metastable state has been determined using a Nd: yttrium aluminum garnet (YAG) pumped dye laser system in conjunction with a low pressure rf glow discharge. The saturation technique has been employed to determine the photoionization cross section from the 2sS01 excited state at and above the first ionization threshold. The measured value of the photoionization cross section at the ionization threshold has been used to extract the f values for the 2sS1→npP1 Rydberg series from n=10 to n=52 . The f values of the observed Rydberg series decrease smoothly with an increase of the principal quantum number. In the continuum region the oscillator strength densities have been estimated by measuring the photoionization cross sections from the 2sS01 excited state at five ionizing laser wavelengths above the first ionization threshold. The discrete f values smoothly merge into the continuous oscillator strength densities across the ionization threshold.

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

    SciTech Connect

    Kar, Sabyasachi; Ho, Y. K.

    2010-09-15

    Recently a study [J. K. Saha and T. K. Mukherjee, Phys. Rev. A 80, 022513 (2009)] on the doubly excited {sup 3}P{sup e} states of helium reports some resonance states that are not in conformity with previously published works [Y. K. Ho and A. K. Bhatia, Phys. Rev. A 47, 2628 (1993)]. Owing to discrepancies between the works, we investigate the resonance parameters (positions and widths) of the doubly excited Feshbach resonances of the {sup 3}P{sup e} symmetries associated with N = 3, 4, and 5 He{sup +} thresholds using a different choice of correlated wave functions in the framework of the complex-coordinate rotation method and the stabilization method. Resonance parameters below the N=4 and N=5 He{sup +} thresholds obtained from the present calculations are not consistent with the results and discussions made in the recent work. Here we point out an error in assessment made by Saha and Mukherjee in an earlier work as well as the lack of numerical accuracy of the results for some high-lying doubly excited states reported by Saha and Mukherjee. The bound 2p{sup 2} {sup 3}P{sup e} and 2p3p {sup 3}P{sup e} state energies obtained from this calculation are consistent with the best reported results but not with the reported values of Saha and Mukherjee.

  14. Rotational state-changing cold collisions of hydroxyl ions with helium

    NASA Astrophysics Data System (ADS)

    Hauser, Daniel; Lee, Seunghyun; Carelli, Fabio; Spieler, Steffen; Lakhmanskaya, Olga; Endres, Eric S.; Kumar, Sunil S.; Gianturco, Franco; Wester, Roland

    2015-06-01

    Cold molecules are important for many applications, from fundamental precision measurements, quantum information processing, quantum-controlled chemistry, to understanding the cold interstellar medium. Molecular ions are known to be cooled efficiently in sympathetic collisions with cold atoms or ions. However, little knowledge is available on the elementary cooling steps, because the determination of quantum state-to-state collision rates at low temperature is very challenging for both experiment and theory. Here we present a method to manipulate molecular quantum states by non-resonant photodetachment. Based on this we provide absolute quantum scattering rate coefficients under full quantum state control for the rotationally inelastic collision of hydroxyl anions with helium. Experiment and quantum scattering theory show excellent agreement without adjustable parameters. Very similar rate coefficients are obtained for two different isotopes, which is linked to several quantum scattering resonances appearing at different energies. The presented method is also applicable to polyatomic systems and will help elucidate non-radiative processes in polyaromatic hydrocarbons and protein chromophores.

  15. Rydberg-blockaded medium inside a high-finesse optical cavity

    NASA Astrophysics Data System (ADS)

    Sheng, Jiteng; Kumar, Santosh; Whiteneck, William; Sedlacek, Jonathon; Shaffer, James

    2015-05-01

    We present experimental and theoretical progress on a Rydberg-blockaded atomic ensemble coupled to a high-finesse optical cavity. Theoretically, we analyze the role that the Rydberg blockade mechanism can play in synthesizing collective quantum states and non-classical states of light in this system. We study the correlation of two photon emission in the case of two Rydberg excitations within the cavity. Experimentally, we show that a cold atomic cloud can be transported into a high-finesse optical cavity by using a focus-tunable lens and that a collective state can be created inside the cavity using Rydberg atom blockade. Future work to realize collective quantum states in the atom-cavity experiment and study the interesting dynamics of the correlated photon emission will be presented.

  16. Trap losses induced by near-resonant Rydberg dressing of cold atomic gases

    NASA Astrophysics Data System (ADS)

    Aman, J. A.; DeSalvo, B. J.; Dunning, F. B.; Killian, T. C.; Yoshida, S.; Burgdörfer, J.

    2016-04-01

    The near-resonant dressing of cold strontium gases and Bose-Einstein condensates contained in an optical dipole trap (ODT) with the 5 s 30 s S31 Rydberg state is investigated as a function of the effective two-photon Rabi frequency, detuning, and dressing time. The measurements demonstrate that a rapid decrease in the ground-state atom population in the ODT occurs even for weak dressing and when well detuned from resonance. This decrease is attributed to Rydberg atom excitation, which can lead to direct escape from the trap and to population of very long-lived 5 s 5 p 0, 2 3P metastable states. The effects of interactions between Rydberg atoms, including those populated by blackbody radiation, are analyzed. The work has important implications when considering the use of Rydberg dressing to control the interactions between dressed ground-state atoms.

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

    NASA Astrophysics Data System (ADS)

    Porcelli, D.; Wasserburg, G. J.

    1995-12-01

    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 of the lower mantle, subduction of rare gases, and mantle rare gas concentrations. Rare gases in the upper mantle are derived from mixing of rare gases from the lower mantle, subducted rare gases, and radiogenic nuclides produced in situ. Isotopic shifts in the closed system lower mantle are due to decay of uranium and thorium decay series nuclides, 40K, 129I, and 244Pu over 4.5 Ga, while isotopic shifts in the steady-state upper mantle are due to decay of uranium and thorium series nuclides, and 40K over a timescale of ˜1.4 Ga. The model predicts that the shift in 21Ne/ 22Ne in the upper mantle relative to that in the lower mantle is the same as that for 4He/ 3He between the mantle reservoirs. This is compatible with the available data for MORB and ocean islands. Subduction of atmospheric helium and neon is not significant. All of the 40Ar in the lower mantle has been produced by 40K decay in the lower mantle. In the upper mantle, 40K decay further increases the radiogenic 40Ar from the lower mantle by a factor of ˜3. The calculated minimum lower mantle 40Ar/36Ar ratio is substantially greater than the atmospheric ratio. The inferred rare gas relative abundances of the lower mantle are different from those of the atmosphere and are consistent with possible early solar system reservoirs. Both the calculated 3He/22Ne and 20Ne/36Ar ratios of the lower mantle are within the range for meteorites with 'solar' neon isotope compositions. The 130Xe/36Ar ratio of the lower mantle is greater than that of the atmosphere, and may be possibly as high as the ratio found for meteoritic "planetary" rare gases. The model treats the atmosphere as a separate reservoir with rare gas isotope compositions that are distinct from those in the mantle. If the Earth originally had uniform concentrations of rare gases as represented by those in the lower mantle, then degassing of the upper mantle would have provided only a small proportion of the nonradiogenic rare gases presently in the atmosphere. The remainder may have been derived from late-accreted material with a much higher concentration of rare gases than the lower mantle. However, the amount of radiogenic 129Xe and 136Xe in the atmosphere as well as the lower mantle implies a substantial loss of rare gases. It is most likely that rare gases have been lost during late accretion and/or during; the hypothesized moon-forming impact. The nonradiogenic rare gases in the atmosphere were then supplied by subsequently accreted material with nonradiogenic xenon, possibly in comets. Fractionation of atmospheric xenon isotopes relative to other early solar system components must have occurred either on the late-accreting materials or during subsequent loss from the Earth.

  18. Quantum Interference in Field Ionization of Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Feynman, Rachel; Hollingsworth, Jacob; Vennittilli, Michael; Budner, Tamas; Zmiewski, Ryan; Fahey, Donald P.; Carroll, Thomas J.; Noel, Michael W.

    2015-05-01

    We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of three | mj | sublevels of a Rydberg state. After a delay in which the relative phase of the states evolve, we field ionize the atoms. The process of ionization is complicated by the details of the state structure for a weakly bound electron in Rydberg states. As these states ionize, their ionization pathways overlap, allowing them to interfere. We find that the result of this interference is dependent on the relative phase between the three states, and that the phase evolves in time inversely with the energy separation between the states. This material is based upon work supported by the National Science Foundation under Grant No. 1205897.

  19. Deflection Schemes Using Rydberg Atom Mirror

    NASA Astrophysics Data System (ADS)

    Tudorica, F.; Kritsun, O. A.; Stevens, G. D.; Metcalf, H.

    1998-05-01

    We are investigating two schemes for deflecting Rydberg atoms in our atom mirror experiment. We plan to excite the Li Rydberg states (n=15) by a 3-step process(G.D. Stevens et al.)., Phys. Rev. Lett. 75, 3402 (1995).. The atoms then travel between a pair of plates that create an inhomogeneous elctric field. Li atoms will evolve along one of the levels of the Stark manifold, the energy changing with the position in the field. The velocity component along the field gradient will be changed, resulting in deflection. In our field configuration we can obtain a gradient of 1000 V/cm across 1 mm, corresponding to a change in energy of 23 cm-1. We compare two possible deflection schemes: 1) atoms going across the field gradient with an initial velocity until reversed, and then steered back towards high/low fields (for high/low field seeker states) or 2) atoms going along the field gradient and simply increasing their transverse momentum. For the first case we study the velocity-dependent nature of the deflection, while for the second case we calculate an optimum deflection angle of about 15^circ for our experimental conditions (beam velocity v ~2000 m/s, field variation 0-1000 V/cm, n=15). We have successfully implemented a Pt-Ir hotwire detector for the beam profile.

  20. Dressing effects in the attosecond transient absorption spectra of doubly excited states in helium

    NASA Astrophysics Data System (ADS)

    Argenti, L.; Jimnez-Galn, .; Marante, C.; Ott, C.; Pfeifer, T.; Martn, F.

    2015-06-01

    Strong-field manipulation of autoionizing states is a crucial aspect of electronic quantum control. Recent measurements of the attosecond transient absorption spectrum (ATAS) of helium dressed by a few-cycle visible pulse [C. Ott et al., Nature (London) 516, 374 (2014), 10.1038/nature14026] provide evidence of the inversion of Fano profiles. With the support of accurate ab initio calculations that reproduce the results of the latter experiment, here we investigate the new physics that arise from ATAS when the laser intensity is increased. In particular, we show that (i) previously unnoticed signatures of the dark 2 p21S doubly excited state are observed in the experimental spectrum, (ii) inversion of Fano profiles is predicted to be periodic in the laser intensity, and (iii) the ac Stark shift of the higher terms in the s p2,n + autoionizing series exceeds the ponderomotive energy, which is the result of a genuine two-electron contribution to the polarization of the excited atom.

  1. Universal Nonequilibrium Properties of Dissipative Rydberg Gases

    NASA Astrophysics Data System (ADS)

    Marcuzzi, Matteo; Levi, Emanuele; Diehl, Sebastian; Garrahan, Juan P.; Lesanovsky, Igor

    2014-11-01

    We investigate the out-of-equilibrium behavior of a dissipative gas of Rydberg atoms that features a dynamical transition between two stationary states characterized by different excitation densities. We determine the structure and properties of the phase diagram and identify the universality class of the transition, both for the statics and the dynamics. We show that the proper dynamical order parameter is in fact not the excitation density and find evidence that the dynamical transition is in the "model A " universality class; i.e., it features a nontrivial Z2 symmetry and a dynamics with nonconserved order parameter. This sheds light on some relevant and observable aspects of dynamical transitions in Rydberg gases. In particular it permits a quantitative understanding of a recent experiment [C. Carr, Phys. Rev. Lett. 111, 113901 (2013)] which observed bistable behavior as well as power-law scaling of the relaxation time. The latter emerges not due to critical slowing down in the vicinity of a second order transition, but from the nonequilibrium dynamics near a so-called spinodal line.

  2. Electron capture from circular Rydberg atoms

    SciTech Connect

    Lundsgaard, M.F.V.; Chen, Z.; Lin, C.D. ); Toshima, N. )

    1995-02-01

    Electron capture cross sections from circular Rydberg states as a function of the angle [ital cphi] between the ion velocity and the angular momentum of the circular orbital have been reported recently by Hansen [ital et] [ital al]. [Phys. Rev. Lett. 71, 1522 (1993)]. We show that the observed [ital cphi] dependence can be explained in terms of the propensity rule that governs the dependence of electron capture cross sections on the magnetic quantum numbers of the initial excited states. We also carried out close-coupling calculations to show that electron capture from the circular H(3[ital d],4[ital f],5[ital g]) states by protons at the same scaled velocity has nearly the same [ital cphi] dependence.

  3. Dipole effects in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Han, Jianing

    2009-12-01

    This dissertation is a continuing study of the dipole effects between cold Rydberg atoms in a MOT (Magneto Optical Trap). The dipole-dipole interaction is commonly used to explain the plasma forming process and dipole blockade effects. However, no direct measurements have been made for such interaction. This dissertation is designed to directly measure this interaction and study the effects induced by the dipole interaction. To achieve this, a few experiments were carried out. First, a millimeter wave spectroscopy experiment was performed to determine quantum defects of higher angular momentum f and g states, which then allows us to accurately identify these states. Moreover, the higher angular momentum states play an important role in the plasma forming process. The next experiment examined the oscilloscope trace collected through field ionization pulses on which all our experiments are based, which leads to the conclusion that the side peaks other than the main peak can be due to the field ionization pulse sweeping through the resonances. Based on the knowledge of identifying states obtained from these two experiments, a third experiment was carried out to understand the interactions between cold Rydberg atoms. It was found that the second order dipole-dipole interaction, the van der Waals interaction, commonly exists between the atoms in our atomic sample, and when we excite the atoms from the ns to (n + 1)s states using a narrow band microwave pulse, an asymmetric broadening, which is attributed to the nsns to ns(n + 1) s molecular state transition, was observed. Furthermore, the van der Waals long range molecule is studied, which provides another way to study the two-body to multi-body transition.

  4. Two-body interactions and decay of three-level Rydberg-dressed atoms

    NASA Astrophysics Data System (ADS)

    Helmrich, S.; Arias, A.; Pehoviak, N.; Whitlock, S.

    2016-02-01

    We theoretically analyze the interactions and decay rates for atoms dressed by multiple laser fields to strongly interacting Rydberg states using a quantum master equation approach. In this framework a comparison of two-level and three-level Rydberg-dressing schemes is presented. We identify a resonant enhancement of the three-level dressed interaction strength which originates from cooperative multiphoton couplings as well as small distance dependent decay rates. In this regime the soft-core shape of the potential is independent of the sign of the bare Rydberg–Rydberg interaction, while its sign can be repulsive or attractive depending on the intermediate state detuning. As a consequence, near-resonant Rydberg dressing in three-level atomic systems may enable the realization of laser driven quantum fluids with long-range and anisotropic interactions and with controllable dissipation.

  5. Cooperative excitation and many-body interactions in a cold Rydberg gas.

    PubMed

    Viteau, Matthieu; Huillery, Paul; Bason, Mark G; Malossi, Nicola; Ciampini, Donatella; Morsch, Oliver; Arimondo, Ennio; Comparat, Daniel; Pillet, Pierre

    2012-08-01

    The dipole blockade of Rydberg excitations is a hallmark of the strong interactions between atoms in these high-lying quantum states [M. Saffman, T. G. Walker, and K. Mølmer, Rev. Mod. Phys. 82, 2313 (2010); D. Comparat and P. Pillet, J. Opt. Soc. Am. B 27, A208 (2010)]. One of the consequences of the dipole blockade is the suppression of fluctuations in the counting statistics of Rydberg excitations, of which some evidence has been found in previous experiments. Here we present experimental results on the dynamics and the counting statistics of Rydberg excitations of ultracold rubidium atoms both on and off resonance, which exhibit sub- and super-Poissonian counting statistics, respectively. We compare our results with numerical simulations using a novel theoretical model based on Dicke states of Rydberg atoms including dipole-dipole interactions, finding good agreement between experiment and theory. PMID:23006168

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

    SciTech Connect

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

    1980-01-01

    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.

  7. Quantum interface between Rydberg ensembles and mechanical oscillators in free space

    NASA Astrophysics Data System (ADS)

    Bariani, Francesco; Otterbach, Johannes; Tan, Huatang; Buchmann, L. F.; Meystre, Pierre

    2013-05-01

    We analyze theoretically an electro-mechanical interface between a charged mechanical oscillator and an ensemble of Rydberg atoms. The charged mechanical oscillator acting as an oscillating electric dipole is coupled to the large electric dipole of the Rydberg transition. The Rydberg blockade effect guarantees that only a single collective spin wave is excited in the atomic ensemble. This hybrid system allows for quantum control of the state of one or more mechanical oscillators. The rich atomic Rydberg spectrum and high level of control of atomic transitions allow to build feedback protocols that maximize its fidelity. We also comment on the use of this interface for phononic state tomography. We ackowledge financial support from NSF, ARO and the DARPA QuaSAR and ORCHID programs.

  8. Quantum Magnetism and Topological Ordering via Rydberg Dressing near Förster Resonances.

    PubMed

    van Bijnen, R M W; Pohl, T

    2015-06-19

    We devise a cold-atom approach to realizing a broad range of bilinear quantum magnets. Our scheme is based on off-resonant single-photon excitation of Rydberg P states (Rydberg dressing), whose strong interactions are shown to yield controllable XYZ interactions between effective spins, represented by different atomic ground states. The distinctive features of Förster-resonant Rydberg atom interactions are exploited to enhance the effectiveness of Rydberg dressing and, thereby, yield large spin interactions that greatly exceed the corresponding decoherence rates. We illustrate the concept on a spin-1 chain implemented with cold rubidium atoms, and demonstrate that this permits the dynamical preparation of topological magnetic phases. Generally, the described approach provides a viable route to exploring quantum magnetism with dynamically tunable (an)isotropic interactions as well as variable space and spin dimensions in cold-atom experiments. PMID:26196973

  9. Spin-orbit coupled Bose-Einstein condensates with Rydberg-dressing interaction

    NASA Astrophysics Data System (ADS)

    Lü, Hao; Zhu, Shao-Bing; Qian, Jun; Wang, Yu-Zhu

    2015-09-01

    Interaction between Rydberg atoms can be used to control the properties of interatomic interaction in ultracold gases by weakly dressing the atoms with a Rydberg state. Here we investigate the effect of the Rydberg-dressing interaction on the ground-state properties of a Bose-Einstein condensate imposed by Raman-induced spin-orbit coupling. We find that, in the case of SU(2)-invariant s-wave interactions, the gas is only in the plane-wave phase and the zero-momentum phase is absent. In particular, we also predict an unexpected magnetic stripe phase composed of two plane-wave components with unequal weight when s-wave interactions are non-symmetric, which originates from the Rydberg-dressing interaction. Project supported by the National Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 11104292).

  10. Collisional dissociative recombination in helium-hydrogen afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Johnsen, Rainer

    2012-10-01

    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.

  11. Quantum entanglement of helium-like systems with varying-Z: compact state-of-the-art CI wave functions

    NASA Astrophysics Data System (ADS)

    López-Rosa, S.; Esquivel, R. O.; Plastino, A. R.; Dehesa, J. S.

    2015-09-01

    In this work we have performed state-of-the-art configuration-interaction (CI) calculations to determine the linear and von Neumann entanglement entropies for the helium-like systems with varying nuclear charge Z in the range 1≤slant Z≤slant 10. The focus of the work resides on determining accurate entanglement values for 2-electron systems with the lowest computational cost through compact CI-wave functions. Our entanglement results for the helium atom fully agree with the results obtained with higher quality wave functions of the Kinoshita type (Dehesa [5]). We find that the correlation energy is linearly related to the entanglement measures associated with the linear and von Neumann entropies of the single-particle reduced density matrizes, which sheds new light on the physical implications of entanglement in helium-like systems. Moreover, we report CI-wave-function-based benchmark results for the entanglement values for all members of the helium isoelectronic series with an accuracy similar to that of Kinoshita-type wave functions. Finally, we give parametric expressions of the linear and von Neumann entanglement measures for two-electron systems as Z varies from 1 to 10.

  12. Electron capture from circular Rydberg atoms

    SciTech Connect

    Lundsgaard, M.F.V.; Chen, Z.; Lin, C.D. Jr.

    1994-12-31

    Recent experiments on electron capture from elliptic Rydberg states by Ehrenreich et al. have shown that the total electron capture cross section, {sigma}, depends strongly on the eccentricity, e, of the elliptic state and the orbit direction of the electron. The authors present the results of close-coupling calculations carried out for protons colliding with elliptic H(n=3,4,5) atoms, which show that the dependence of {sigma} on e varies weakly with the principal quantum number n. The dependence of {sigma} on the angle, {phi}, between the beam and the classical plane of the elliptic orbital is also presented. The results are shown to be consistent with the criteria of velocity matching for the electron capture process.

  13. Rydberg Spectroscopy and imaging of single Holmium atoms

    NASA Astrophysics Data System (ADS)

    Hostetter, James; Pritchard, Jonathan; Saffman, Mark

    2015-05-01

    Neutral holmium with its large number of hyperfine ground states provides a promising approach for collective encoding of a multi-qubit register. Collective encoding relies on the use of Rydberg blockade to create a one-to-one correspondence between singly excited states of the atomic ensemble and logical register states. As a step towards collective encoding with Rydberg blockade in holmium we have precisely measured the energy of ns and nd Rydberg states from n = 41-101 using MOT depletion spectroscopy. These measurements have resulted in a precise determination of the first ionization potential as well as the quantum defects of the singlet ns and nd series. The strong 410.5 nm cooling transition with ~ 33 MHz linewidth coupled with the large hyperfine splitting in the electronically excited state are predicted to enable fast, loss-free, and state sensitive measurements which are a prerequisite for collective encoding experiments. We report on progress towards single-atom trapping and state sensitive detection of holmium in a far off-resonant optical dipole trap. Work supported by NSF award PHY-1404357.

  14. Photo-excited states in germanium at liquid-helium temperatures

    SciTech Connect

    Culbertson, J.C.

    1982-12-01

    A wide variety of experimental work dealing with the basic properties of photoexcited states in Ge at liquid helium temperatures is presented. The primary emphasis is on the electron-hole liquid (EHL) and the free exciton (FE). The EHL is composed of two interpenetrating Fermi liquids, one of electrons and one of holes, each with its own Fermi level. The FE dealt with here is a mobile, loosely bound state of an electron and a hole. We report the first absolute measurement of the density dependence of the enhancement factor g/sub eh/(0) for the EHL in Ge. This factor g/sub eh/(0) is a measure of the electron-hole spatial correlation function, and provides a valuable and sensitive test for the predictions of various many-body-theory approximations. An EHL droplet - FE gas system confined to a strain induced potential well was used. The measurement approach relied on only a few simple and verifiable assumptions. A byproduct of this work was the measurement as a function of stress of: the electron and hole Fermi levels E/sub F//sup e/ and E/sub F//sup h/, the EHL density n/sub l/, the condensation energy phi of a FE relative to the EHL, and the binding energy of a FE (E/sub x/) relative to free carriers (FC). The decay of a FE-FC system confined to a strain induced potential well is studied. The first direct measurement of the FE diffusivity D/sub x/ is reported. The evolution in time of spatial profiles of FE luminescence were measured. From these FE density profiles, D/sub x/(4.2K) approx. = to 300 cm/sup 2/ s/sup -1/, the surface recombination velocity S approx. = 3000 cm s/sup -1/, and the FE lifetime tau/sub x/ = 27 ..mu..s with surface effects excluded were determined. (WHK)

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  16. Rydberg excitation of neutral nitric oxide molecules in strong UV and near-IR laser fields

    NASA Astrophysics Data System (ADS)

    Lv, Hang; Zhang, Jun-Feng; Zuo, Wan-Long; Xu, Hai-Feng; Jin, Ming-Xing; Ding, Da-Jun

    2015-06-01

    Rydberg state excitations of neutral nitric oxide molecules are studied in strong ultraviolet (UV) and near-infra-red (IR) laser fields using a linear time-of-flight (TOF) mass spectrometer with the pulsed electronic field ionization method. The yield of Rydberg molecules is measured as a function of laser intensity and ellipticity, and the results in UV laser fields are compared with those in near-IR laser fields. The present study provides the first experimental evidence of neutral Rydberg molecules surviving in a strong laser field. The results indicate that a rescattering-after-tunneling process is the main contribution to the formation of Rydberg molecules in strong near-IR laser fields, while multi-photon excitation may play an important role in the strong UV laser fields. Project supported by the National Basic Research Program of China (Grant No. 2013CB922200) and the National Natural Science Foundation of China (Grant Nos. 11034003 and 11274140).

  17. Projectile charge-state dependence on final-state momentum distributions for single ionization of helium

    SciTech Connect

    Wood, C.J.; Feeler, C.R.; Olson, R.E.

    1997-11-01

    Single-ionization cross sections and final-state momentum distributions have been calculated for the single-ionization collision reactions H{sup +}, {bar p}, He{sup 2+}, C{sup 4+}, and C{sup 6+} + He at 100 keV/u. The classical trajectory Monte Carlo method has been used with a Wigner distribution to improve both the He electron classical radial and momentum distributions. Final-state ionized electron momenta are projected into a collision plane defined by the initial projectile momentum and the final transverse component of the He{sup +} recoil momentum, with the results displayed differentially in various components of electron and recoil momenta. Positively charged projectile impact shows that the soft electrons drift with the recoil ion, while higher-energy electrons move with the projectile and away from the recoiling target. The electron capture to the continuum cusp is present for hard collisions, with asymmetry in both the collision plane and along the longitudinal momenta. Antiproton impact results in soft electrons drifting backward, away from the recoil ion, with the binary-encounter ring clearly observed. {copyright} {ital 1997} {ital The American Physical Society}

  18. Exploiting the coupling between a Rydberg atom and a surface phonon polariton for single-photon subtraction

    NASA Astrophysics Data System (ADS)

    Kübler, H.; Booth, D.; Sedlacek, J.; Zabawa, P.; Shaffer, J. P.

    2013-10-01

    We investigate a hybrid quantum system that consists of a superatom coupled to a surface phonon-polariton. We apply this hybrid quantum system to subtract individual photons from a beam of light. A Rydberg atom blockade is used to attain absorption of a single photon by an atomic microtrap. Surface phonon-polariton coupling to the superatom then triggers the transfer of the excitation to a storage state, a single Rydberg atom. The approach utilizes the interaction between a superatom and a Markovian bath that acts as a controlled decoherence mechanism to irreversibly project the superatom state into a single Rydberg atom state that can be read out.

  19. Analytical solutions for diatomic Rydberg quasimolecules in a laser field

    NASA Astrophysics Data System (ADS)

    Kryukov, Nikolay; Oks, Eugene

    2014-06-01

    In our previous works we studied analytically helical Rydberg states and circular Rydberg states of two-Coulomb-center systems consisting of two nuclei of charges Z and Z', separated by a distance R, and one electron. We obtained energy terms of these Rydberg quasimolecules for a field-free case, as well as under a static electric field or under a static magnetic field. In the present paper we study such systems under a laser field. For the situation where the laser field is linearly-polarized along the internuclear axis, we found an analytical solution for the stable helical motion of the electron valid for wide ranges of the laser field strength and frequency. We also found resonances, corresponding to a laser-induced unstable motion of the electron, that result in the destruction of the helical states. For the situation where such Rydberg quasimolecules are under a circularly-polarized field, polarization plane being perpendicular to the internuclear axis, we found an analytical solution for circular Rydberg states valid for wide ranges of the laser field strength and frequency. We showed that both under the linearly-polarized laser field and under the circularly-polarized laser field, in the electron radiation spectrum in the addition to the primary spectral component at (or near) the unperturbed revolution frequency of the electron, there appear satellites. We found that for the case of the linearly-polarized laser field, the intensities of the satellites are proportional to the squares of the Bessel functions J {/q 2}( s), ( q = 1, 2, 3, ...), where s is proportional to the laser field strength. As for the case of the circularly-polarized field, we demonstrated that there is a red shift of the primary spectral component — the shift linearly proportional to the laser field strength. Under a laser field of a known strength, in the case of the linear polarization the observation of the satellites would be the confirmation of the helical electronic motion in the Rydberg quasimolecule, while in the case of the circular polarization the observation of the red shift of the primary spectral component would be the confirmation of the specific type of the phase modulation of the electronic motion. Conversely, if the laser field strength is unknown, both the relative intensities of the satellites and the red shift of the primary spectral component could be used for measuring the laser field strength.

  20. Infrared detection using Rydberg atoms. Final report, 1 March 1979-30 November 1987

    SciTech Connect

    Kleppner, D.

    1988-04-01

    This is the final report on a program of research on Rydberg atoms and radiation. The goal of the program was to use Rydberg atoms to explore new types of fundamental radiative phenomena. As demonstrated by the research generated by this line of inquiry in laboratories in the U.S. and abroad, the program has been successful. A new area of study called Cavity Quantum Electrodynamics has emerged in the last few years. Research under this grant on inhibited spontaneous emission is often regarded as seminal in that development. The Principal Investigator was awarded the 1986 Davisson-Germer Prize of the American Physical Society for research on Rydberg Atoms in applied fields: research under this grant was central to that achievement. Early work under the grant involved developing techniques for studying radiative transfer of Rydberg atoms on a level-by level basis. During this time the P.I. conceived the idea of of turning off spontaneous emission by Rydberg atoms. A closely related idea - the inhibition of black-body radiative transfer - was demonstrated shortly thereafter. Full demonstration of inhibited spontaneous emission required the development of a technique for transferring atoms to the so-called circular Rydberg states. These are states of the highest-possible angular momentum for a given principal quantum number. The author's method has been adapted in other laboratories, and is now being employed in Rydberg-atom studies and in a new type of measurement of the Rydberg constant. The most-exciting advance under the grant has been the demonstration that spontaneous emission can indeed be switched off.

  1. Electron capture from circular Rydberg atoms

    SciTech Connect

    Hansen, S.B.; Ehrenreich, T.; Horsdal-Pedersen, E. ); MacAdam, K.B. ); Dube, L.J. )

    1993-09-06

    Capture cross sections for circular Rydberg states have been measured as a function of the angle, [ital cphi], between ion velocity and angular momentum of the circular orbital. The system studied is 2.5 keV [sup 23]Na[sup +] on Li(1[ital s][sup 2],[ital nlm]) with [ital n]=25, [ital l]=[ital n][minus]1, and [ital m]=+[ital l], where [ital m] is defined relative to a weak, external magnetic field. A strong dependence on [ital cphi] is found. It is expected that studies such as the present will lead to an improved understanding of the three-body problem in the region of sufficiently large quantum numbers and impact velocities for classical physics to be accurate.

  2. Optical properties of Rydberg excitons and polaritons

    NASA Astrophysics Data System (ADS)

    Zielińska-Raczyńska, Sylwia; Czajkowski, Gerard; Ziemkiewicz, David

    2016-02-01

    We show how to compute the optical functions when Rydberg excitons appear, including the effect of the coherence between the electron-hole pair and the electromagnetic field. We use the real density matrix approach (RDMA), which, combined with the Green's function method, enables one to derive analytical expressions for the optical functions. Choosing the susceptibility, we performed numerical calculations appropriate to a Cu20 crystal, being a semiconductor with an indirect gap. The effect of the coherence is displayed in the line shape. We also examine in detail and explain the dependence of the oscillator strength and the resonance placement on the state number. We report good agreement with recently published experimental data. We also show that the presented method can be applied to semiconductors with a direct gap.

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

    SciTech Connect

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

    2014-11-07

    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.

  4. Entanglement generation between spinor Bose-Einstein condensates using Rydberg excitations

    NASA Astrophysics Data System (ADS)

    Idlas, Sandrine; Domenzain, Luis; Spreeuw, Robert; Byrnes, Tim

    2016-02-01

    We propose an experimental scheme of generating entangled states between two spinor Bose-Einstein condensates (BECs) using Rydberg excitations. Due to the strong interaction between Rydberg atoms, the Rydberg excitation creates an interaction between two closely located BECs. The method is suitable particularly for atom chip and permanent magnetic trap systems, which can create many BECs with an arbitrary two-dimensional geometry. We show two schemes of entangled state generation, based on stimulated Raman adiabatic passage (STIRAP) methods. The first method produces a symmetric state with total Sx spin zero between ground and excited states of the atoms using a single STIRAP pair, while the second produces a NOON state between hyperfine ground states using two STIRAP pairs. We show that despite the additional complexity of the BECs, it is possible to identify the initial and final adiabatic states exactly. We verify our theoretical predictions using numerical simulations on small boson number systems.

  5. Population transfer in the Na s-p Rydberg ladder by a chirped microwave pulse

    SciTech Connect

    Maeda, H.; Gurian, J. H.; Gallagher, T. F.

    2011-12-15

    While quantum defects of nl Rydberg states of Na with l{>=}2 are nearly equal to zero, the quantum defects of ns and np states of Na are quite large due to the finite size of its ionic core. Since the Na ns and np states are energetically isolated from the higher angular momentum states of the same n, we can think of the Na ns and np Rydberg states as a specific example of a simple multilevel ladder system consisting of only alternating s and p angular momentum states. Here we report that population transfer in the Na s-p Rydberg ladder can be effectively achieved using a frequency-chirped microwave pulse, which couples only s and p states under suitable conditions.

  6. Charge transfer in ion collisions with circular Rydberg atoms

    SciTech Connect

    Homan, D.M.; Cavagnero, M.J.; Harmin, D.A. )

    1994-09-01

    Recent experimental measurements of charge transfer in ion collisions with circular-state Rydberg atoms (for which [ital m]=[ital l]=[ital n][minus]1) can be qualitatively reproduced using an elementary atomic model consisting of a classical electron in a circular orbit with an arbitrary axis of rotation defined by experiment. Contributions to capture are further separated into one-swap and three-swap charge transfers, revealing the relative importance of a Thomaslike mechanism for charge transfer at ion velocities of 1.00, 1.65, and 2.00 times the velocity of the target electron. The model is extended to estimate charge-transfer cross sections for ions incident on elliptic-state Rydberg atoms of specific eccentricity.

  7. Entropy and complexity analysis of hydrogenic Rydberg atoms

    NASA Astrophysics Data System (ADS)

    López-Rosa, S.; Toranzo, I. V.; Sánchez-Moreno, P.; Dehesa, J. S.

    2013-05-01

    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 Crámer-Rao, Fisher-Shannon, and López 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.

  8. Entropy and complexity analysis of hydrogenic Rydberg atoms

    SciTech Connect

    Lopez-Rosa, S.; Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla ; Toranzo, I. V.; Dehesa, J. S.; Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada ; Sanchez-Moreno, P.; Departamento de Matematica Aplicada, Universidad de Granada, 18071-Granada

    2013-05-15

    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.

  9. Floquet analysis of inelastic collisions of ions with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Cavagnero, M. J.

    1995-10-01

    The theory of Demkov et al. (Zh. Eksp. Teor. Fiz. 66, 125 (1974) [Sov. Phys. JETP 39, 57 (1974)]) for collisional mixing of degenerate states of a hydrogenlike target is generalized to nonhydrogenic targets parametrized by a set of quantum defects, \\{μl\\}, with l the orbital angular-momentum quantum number of the Rydberg electron. Schrödinger's equation is written in periodic form in the impact-parameter approximation by using the angle of rotation of the internuclear line, as opposed to the time, as the independent variable. Quasiperiodic solutions are constructed by Floquet analysis, as in studies of Rydberg-state mixing by oscillatory fields, leading to an infinite-dimensional eigenvalue equation whose eigenvectors and eigenvalues determine the evolution operator of the collision system. An initial application to ``l-mixing collisions'' of ions with alkali-metal atoms indicates that dipole-forbidden transitions dominate depopulation cross sections at intermediate collision speeds.

  10. Calculation of Rydberg energy levels for the francium atom

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Zhong; Chu, Jin-Min

    2010-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    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.

  12. Quantum computing with cold atoms and Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Saffman, Mark

    2015-05-01

    Optically trapped neutral atoms are one of several leading approaches to scalable quantum information processing. When prepared in electronic ground states in deep optical lattices atomic qubits are weakly interacting with long coherence times. Excitation to Rydberg states turns on strong interactions which enable fast gates and entanglement generation through either coherent evolution or dissipative dynamics. Rydberg interactions can be applied in a variety of ways enabling control of single atom qubits, multi-atom ensemble qubits, and hybrid entanglement between different types of atoms, between atoms and photons, or between atoms and solid state qubits. I will present advances that leverage strong Rydberg interactions for implementation of a small scale quantum computing device. We trap 30 or more atomic qubits in a 2D array of 49 sites. Single qubit gates are performed with fidelities better than 0.999 as characterized by random benchmarking. Two-qubit gates and entanglement are demonstrated between qubit pairs. Experimental gate fidelities are not yet sufficient for reliable error correction and scalable quantum computation. I will describe prospects for reaching the fault tolerance threshold based on new gate protocols with the potential for fast generation of entanglement at fidelities better than 0.9999. Work supported by the NSF, IARPA MQCO program, ARO, and AFOSR.

  13. Angular-momentum couplings in long-range Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Anderson, David; Miller, Stephanie; Raithel, Georg

    2015-05-01

    We present results of a recent theoretical study of angular-momentum couplings in long-range diatomic Rydberg molecules formed between a rubidium Rydberg and 5S1 / 2 ground-state atom. A Fermi model is used that takes into account all angular-momentum couplings comparable to the e- + 5S1 / 2 scattering interaction strength. The model includes S- and P-wave singlet and triplet e- + 5S1 / 2 scattering, the fine-structure of the Rydberg atom as well as the hyperfine-structure of the 5S1 / 2 atom. The effects of these couplings on the adiabatic molecular potentials are discussed. We calculate bound-state energies, lifetimes, and electric and magnetic dipole moments for the 87Rb(nDj + 5S1 / 2) molecules in all potentials. The hyperfine structure gives rise to mixed singlet-triplet potentials in both low- and high- l molecular classes. These spin-mixed potentials are deep enough to sustain bound states, which were recently observed in low- l Cs2 molecules. We also study the effects of the hyperfine structure on the deep 3S and 3P adiabatic molecular potentials in both Rb2 and Cs2 molecules.

  14. Study on Off-Design Steady State Performances of Helium Gas Turbo-compressor for HTGR-GT

    SciTech Connect

    Qisen Ren; Xiaoyong Yang; Zhiyong Huang; Jie Wang

    2006-07-01

    The high temperature gas-cooled reactor (HTGR) coupled with direct gas turbine cycle is a promising concept in the future of nuclear power development. Both helium gas turbine and compressor are key components in the cycle. Under normal conditions, the mode of power adjustment is to control total helium mass in the primary loop using gas storage vessels. Meanwhile, thermal power of reactor core is regulated. This article analyzes off-design performances of helium gas turbine and compressors for high temperature gas-cooled reactor with gas turbine cycle (HTGR-GT) at steady state level of electric power adjustment. Moreover, performances of the cycle were simply discussed. Results show that the expansion ratio of turbine decreases as electric power reduces but the compression ratios of compressors increase, efficiencies of both turbine and compressors decrease to some extent. Thermal power does not vary consistently with electric power, the difference between these two powers increases as electric power reduces. As a result of much thermal energy dissipated in the temperature modulator set at core inlet, thermal efficiency of the cycle has a widely reduction under partial load conditions. (authors)

  15. Antiprotonic helium and CPT invariance

    NASA Astrophysics Data System (ADS)

    Hayano, Ryugo S.; Hori, Masaki; Horváth, Dezso; Widmann, Eberhard

    2007-12-01

    We review recent progress in the laser and microwave spectroscopy of antiprotonic helium atoms (\\barpHe^+ \\equiv \\rme^\\--\\barp - He^{++}) carried out at CERN's Antiproton Decelerator facility (AD). Laser transitions were here induced between Rydberg states (n, ell) and (n ± 1, ell - 1) of \\barpHe^+ (n ~ 40 and ell ≲ n - 1 being the principal and orbital angular momentum quantum numbers of the antiproton orbit). Successive refinements in the experimental techniques improved the fractional precision on the \\barpHe^+ frequencies from 3 parts in 106 to ~1 part in 108. These included a radiofrequency quadrupole decelerator, which reduced the energy of the antiprotons from 5.3 MeV (the energy of the beam emerging from AD) to ~100 keV. This enabled the production of \\barpHe^+ in ultra-low density targets, where collisional effects with other helium atoms are negligible. A continuous wave pulse-amplified dye laser, stabilized against a femtosecond optical frequency comb, was then used to measure the \\barpHe^+ frequencies with ppb-scale precision. This progress in the experimental field was matched by similar advances in computing methods for evaluating the expected transition frequencies in three-body QED calculations. The comparison of experimental (νexp) and theoretical (νth) frequencies for seven transitions in \\barp^4He^+ and five in \\barp^3 He^+ yielded an antiproton-to-electron mass ratio of m_\\bar p/m_{\\rme} = 1836.152\\,674(5) . This agrees with the known proton-to-electron mass ratio at the level of ~2 × 10-9. The experiment also set a limit on any CPT-violating difference between the antiproton and proton charges and masses, (Q_p - |Q_{\\barp}|)/Q_p \\sim (m_p - m_{\\barp})/m_p < 2 \\times 10^{-9} to a 90% confidence level. If on the other hand we assume the validity of the CPT invariance, the m_{\\barp}/m_{\\rme} result can be taken to be equal to mp/me. This can be used as an input to future adjustments of fundamental constants. The hyperfine structure of a state in \\barp^4He^+ has also been measured by microwave spectroscopy to a precision of 3 × 10-5. This corresponds to the accuracy of the most precise three-body QED calculations. Further increases in the experimental precision may soon yield an improvement in the value of the antiproton magnetic moment.

  16. Dielectronic Recombination, Autoionization and Non-Adiabatic Core Polarization of Rydberg Two-Electron Atoms

    NASA Astrophysics Data System (ADS)

    Nunkaew, Jirakan

    In this dissertation, I study the structure and dynamics of Rydberg two-electron atoms. Specifically, I study the core polarization effect of the Rydberg electron on the ground state ion of strontium and the autoionization of barium atoms in an external static field in the low field regime. The autoionization studies show that it is possible to measure the contribution to dielectronic recombination (DR) of energetically unresolved high ℓ states by measuring the recombination rate as a function of electric field. I also present the experimental observation that the ejected electrons from autoionizing states in an electric field have a directional preference that depends on the orientation of the Rydberg Stark state wavefunctions. Finally, I present the spectroscopy of the Stark autoionizing states in the low field regime using a high resolution dye-amplified diode laser.

  17. Wigner crystallization of single photons in cold Rydberg ensembles.

    PubMed

    Otterbach, Johannes; Moos, Matthias; Muth, Dominik; Fleischhauer, Michael

    2013-09-13

    The coupling of weak light fields to Rydberg states of atoms under conditions of electromagnetically induced transparency leads to the formation of Rydberg polaritons which are quasiparticles with tunable effective mass and nonlocal interactions. Confined to one spatial dimension their low energy physics is that of a moving-frame Luttinger liquid which, due to the nonlocal character of the repulsive interaction, can form a Wigner crystal of individual photons. We calculate the Luttinger K parameter using density-matrix renormalization group simulations and find that under typical slow-light conditions kinetic energy contributions are too strong for crystal formation. However, adiabatically increasing the polariton mass by turning a light pulse into stationary spin excitations allows us to generate true crystalline order over a finite length. The dynamics of this process and asymptotic correlations are analyzed in terms of a time-dependent Luttinger theory. PMID:24074081

  18. Observation and characterization of cavity Rydberg polaritons

    NASA Astrophysics Data System (ADS)

    Ningyuan, Jia; Georgakopoulos, Alexandros; Ryou, Albert; Schine, Nathan; Sommer, Ariel; Simon, Jonathan

    2016-04-01

    We experimentally demonstrate the emergence of a robust quasiparticle, the cavity Rydberg polariton, when an optical cavity photon hybridizes with a collective Rydberg excitation of a laser-cooled atomic ensemble. Free-space Rydberg polaritons have recently drawn intense interest as tools for quantum information processing and few-body quantum science. Here, we explore the properties of their cavity counterparts in the single-particle sector, observing an enhanced lifetime and slowed dynamics characteristic of cavity dark polaritons. We measure the range of cavity frequencies over which the polaritons persist, corresponding to the spectral width available for polariton quantum dynamics, and the speed limit for quantum information processing. Further, we observe a cavity-induced suppression of inhomogeneous broadening channels and demonstrate the formation of Rydberg polaritons in a multimode cavity. In conjunction with recent demonstrations of Rydberg-induced cavity nonlinearities, our results point the way towards using cavity Rydberg polaritons as a platform for creating high-fidelity photonic quantum materials and, more broadly, indicate that cavity dark polaritons offer enhanced stability and control uniquely suited to optical quantum information processing applications beyond the Rydberg paradigm.

  19. Two body and multibody interaction in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Han, Jianing; Gallagher, Tom

    2009-05-01

    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).

  20. Phases, collective modes, and nonequilibrium dynamics of dissipative Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Ray, S.; Sinha, S.; Sengupta, K.

    2016-03-01

    We use a density matrix formalism to study the equilibrium phases and nonequilibrium dynamics of a system of dissipative Rydberg atoms in an optical lattice within mean-field theory. We provide equations for the fixed points of the density matrix evolution for atoms with infinite on-site repulsion and analyze these equations to obtain their Mott-insulator-superfluid (MI-SF) phase boundary. A stability analysis around these fixed points provides us with the excitation spectrum of the atoms both in the MI and SF phases. We study the nature of the MI-SF critical point in the presence of finite dissipation of Rydberg excitations, discuss the fate of the superfluid order parameter of the atoms in the presence of such dissipation in the weak-coupling limit using a coherent state representation of the density matrix, and extend our analysis to Rydberg atoms with finite on-site interaction via numerical solution of the density matrix equations. Finally, we vary the boson (atom) hopping parameter J and the dissipation parameter Γ according to a linear ramp protocol. We study the evolution of entropy of the system following such a ramp and show that the deviation of the entropy from its steady-state value for the latter protocol exhibits power-law behavior as a function of the ramp time. We discuss experiments that can test our theory.

  1. Radioprotection in depressed metabolic states: The physiology of helium-cold hypothermia

    NASA Technical Reports Server (NTRS)

    Musacchia, X. J.

    1973-01-01

    The use of hypothermia as a means of radiation protection was studied on a variety of mammals exposed to 80% helium-20% oxygen atmospheres at low ambient temperatures. Results show that the LD for normothermic animals significantly increased compared with hypothermic animals; similar results were obtained for hibernating mammalians. Pre-exposure of animals to cold temperatures increased their ability to withstand radiation levels close to LD sub 50.

  2. Attosecond Two-Photon Interferometry for Doubly Excited States of Helium

    SciTech Connect

    Feist, J.; Nagele, S.; Burgdoerfer, J.; Ticknor, C.; Collins, L. A.; Schneider, B. I.

    2011-08-26

    We show that the correlation dynamics in coherently excited doubly excited resonances of helium can be followed in real time by two-photon interferometry. This approach promises to map the evolution of the two-electron wave packet onto experimentally easily accessible noncoincident single-electron spectra. We analyze the interferometric signal in terms of a semianalytical model which is validated by a numerical solution of the time-dependent two-electron Schroedinger equation in its full dimensionality.

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

    SciTech Connect

    Gejo, T. Ikegami, T.; Honma, K.; Takahashi, O.; Shigemasa, E.; Hikosaka, Y.; Tamenori, Y.

    2014-06-07

    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.

  4. Liquid Helium

    NASA Astrophysics Data System (ADS)

    Atkins, K. R.

    2014-06-01

    Preface; 1. Introduction; 2. Equilibrium properties; 3. Theories; 4. The new thermodynamics; 5. First and second sound; 6. Further aspects of the thermodynamics; 7. Helium films; 8. Helium three; 9. He3-He4 mixtures; References; Index.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    The passage of cold cesium 49S1/2 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 49S1/2 population adiabatically transitions into high-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 μs 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.

  6. Imaging electric fields in the vicinity of cryogenic surfaces using Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Thiele, T.; Deiglmayr, J.; Stammeier, M.; Agner, J.-A.; Schmutz, H.; Merkt, F.; Wallraff, A.

    2015-12-01

    The ability to characterize static and time-dependent electric fields in situ is an important prerequisite for quantum-optics experiments with atoms close to surfaces. Especially in experiments which aim at coupling Rydberg atoms to the near field of superconducting circuits, the identification and subsequent elimination of sources of stray fields are crucial. We present a technique that allows the determination of stray-electric-field distributions [Fxstr(r ⃗) ,Fystr(r ⃗) ,Fzstr(r ⃗) ] at distances of less than 2 mm from (cryogenic) surfaces using coherent Rydberg-Stark spectroscopy in a pulsed supersonic beam of metastable 1 s12 s11S0 helium atoms. We demonstrate the capabilities of this technique by characterizing the electric stray field emanating from a structured superconducting surface. Exploiting coherent population transfer with microwave radiation from a coplanar waveguide, the same technique allows the characterization of the microwave-field distribution above the surface.

  7. Quantum Zeno dynamics of a Rydberg atom

    NASA Astrophysics Data System (ADS)

    Gleyzes, Sebastien; Signoles, Adrien; Facon, Adrien; Grosso, Dorian; Dotsenko, Igor; Haroche, Serge; Raimond, Jean Michel; Brune, Michel

    2014-05-01

    The back-action of a quantum measurement can completely modify the evolution of a quantum system. A famous example is the quantum Zeno effect. However, if the eigenspace corresponding to the result of the measurement is degenerated, the evolution of system is no longer freezed, but the dynamics is confined inside the eigenspace. This is the Quantum Zeno Dynamics (QZD). We have experimentally implemented QZD in the Stark manifold of a Rydberg atom. Under the effect of a sigma + radio-frequency field, our atom initially in the circular state behaves as a J = 25 spin, which rotates between the north pole and the south pole of a generalized Bloch sphere. By repeatedly asking the system ``have you crossed a given latitude?'', we can confine the evolution of the spin to the polar cap of the Bloch sphere. We have recorded the population of the different m sublevels as a function of the RF drive duration to see that the dynamics of the atom is confined in the first states of the spin ladder. We have measured the Q function of the spin for different interaction times, and clearly seen the phase space distribution disappearing from one side of the LL and reappearing on the other, while being transiently in a superposition of two spin coherent states with different phases. To demonstrate the quantum coherence of this superposition, we have reconstructed the full density matrix of the atom at this time.

  8. 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)

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

    2011-10-01

    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 α-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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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 .

  10. Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

    SciTech Connect

    Askeland, S.; Soerngaard, S. A.; Nepstad, R.; Foerre, M.; Pilskog, I.

    2011-09-15

    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.

  11. Stabilization of circular Rydberg atoms by circularly polarized infrared laser fields

    NASA Astrophysics Data System (ADS)

    Askeland, S.; Sørngård, S. A.; Pilskog, I.; Nepstad, R.; Førre, M.

    2011-09-01

    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 Schrödinger 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.

  12. Interpretation of the predissociation of the CO Rydberg W 1Π (v = 1) level

    NASA Astrophysics Data System (ADS)

    Lefebvre-Brion, H.; Kalemos, A.

    2016-04-01

    With the goal to interpret the experimental results obtained quite recently by Heays et al. [J. Chem. Phys. 141, 144311 (2014)] on the predissociation of the Rydberg W 1Π (v = 1) vibrational level of the CO molecule, we report herein ab initio potential energy curves of some of its valence and Rydberg states of both 1Π and 3Π symmetry. Our results confirm that the above vibrational level is perturbed by a new electronic 1Π state not observed until now. They correctly reproduce the linewidths of predissociation of the two interacting levels.

  13. Thermal equilibrium/disequilibrium features in the excited-state temperature of atomic helium in MAP-II divertor simulator

    NASA Astrophysics Data System (ADS)

    Kado, S.

    2015-08-01

    Doppler-Stark spectrometry and laser Thomson scattering diagnostics for helium plasmas were applied to the MAP-II (material and plasma) steady-state linear divertor simulator at the University of Tokyo. In recombining plasmas, as the volumetric recombination proceeded, atomic, ionic and electron temperatures converged to the same values, which indicated the achievement of thermal equilibrium. On the other hand, in ionizing plasmas, in addition to the collisional heating of bulk atoms, excess heating of atoms in the high principal quantum number states (above Griem's boundary) was observed. This disequilibrium feature can be attributed to the presence of two prevailing conditions: that the characteristic time of the charge-exchange process of the atoms with ions in the system became shorter than the lifetime of the excited atoms spent above Griem's boundary, and that the population influx from above Griem's boundary is considerably larger than that from below the boundary.

  14. Preparation for Acceleration and Deceleration of Cold Rydberg Atoms in the Field of a Charged Wire

    NASA Astrophysics Data System (ADS)

    Goodsell, Anne; Nawarat, Poomirat; Harper, W. Colleen

    2015-05-01

    We are preparing for experiments using cold Rydberg atoms in linear Stark states. We cool and launch Rb atoms at 2-12 m/s toward a charged wire with a cylindrically-symmetric electric field. The cold cloud will be illuminated in mid-flight to promote atoms into the desired Rydberg state (e.g. n = 33-40). With a three-photon sequence we will access nf states and the nearby manifolds (parabolic quantum number 0 <=n1 <= (n -4)) with linear Stark shifts. This requires specific detuning of the the excitation laser, which allows us to selectively compare states that are strongly accelerated to states that are strongly decelerated. With the wire at +10 V, atoms launched at 10 m/s, and excitation near 750 μm from the wire, the displacement during the Rydberg lifetime (e.g. n = 35, τ = 30 μs) will be 200-300 μm farther for extreme attracted states (n1 = 0) than for extreme repelled states (n1 = 31). Detection will occur by spatially-dependent field ionization. Observations of atoms with zero angular momentum around the wire can be extended to atoms with nonzero angular momentum and also to study the dynamics of Rydberg atoms with a quadratic Stark shift, building on previous work with ground-state atoms. (Current address: Rensselaer Polytechnic Institute, Troy, NY).

  15. Electron capture from Rydberg atoms by highly-charged ions

    SciTech Connect

    Wang, J.; McGuire, J.H.; Olson, R.E.; Burgdoerfer, J.

    1996-05-01

    The authors report cross sections in electron capture from circular Rydberg atoms by highly charged ions A{sup q+} for charge states q ranging from 1 to 40. The initial Rydberg state has n,l=25,24 as its principal and angular momentum quantum numbers, respectively. The collision speed is chosen between 0.4 to 4 times the electron orbital speed, corresponding in collision energies from 6.4 to 640 eV/u. Also studied are the final state distribution of the captured electron and orientation effects of the initial state. The authors find large differences in all the aspects investigated between the lowest and the highest charged states. Results from a simple classical over-barrier model are in surprisingly good agreement with the full classical simulations for large charge states. Results from a simple classical over-barrier model are in surprisingly good agreement with the full classical simulations for large charge states. For singly charged ions q = 1, the convergence of classical scalings is also investigated and found to be very slow from n = 4 to n = 100.

  16. On Helium Anions in Helium Droplets: Interpreting Recent Experiments

    NASA Astrophysics Data System (ADS)

    Mauracher, Andreas; Huber, Stefan E.

    2014-10-01

    Helium droplets provide an ideal environment to study elementary processes in atomic systems at very low temperatures. Here, we discuss properties of charged and neutral, atomic and molecular helium species formed in helium droplets upon electron impact. By studying their interaction with atomic ground state helium we find that He, He2 and excited (metastable) He*- are well bound within the helium droplet. In comparison, He* , He2* and He2* are found to be squeezed out due to energetic reasons. We also present the formation pathways of atomic and molecular helium anions in helium droplets. Transition barriers in the energetic lowest He*- - He interaction potentials prevent molecule formation at the extremely low temperatures in helium droplets. In contrast, some excited states allow a barrier-free formation of molecular helium (anions). With these theoretical results at hand we can interpret recent experiments in which the resonant formation of atomic and molecular helium anions was observed. Furthermore, we give an outlook on the implications of the presence of these anionic species in doped helium droplets with regard to charge transfer reactions. Austrian Fund Agency (FWF, I 978-N20, DK+ project Computational Interdisciplinary Modelling W1227-N16)/Austrian Ministry of Science (BMWF, Konjunkturpaket II, UniInfrastrukturprogramm of the Focal Point Scientific Computing).

  17. Comparison of Strengths of Trapping of Helium in the Solid and Liquid State of Hydrogen

    NASA Astrophysics Data System (ADS)

    Nandini Usha Roy, Alok; Scheicher, R. H.; Das, T. P.; Ishida, K.; Matsuzaki, T.; Nakamura, S. N.; Kawamura, N.; Nagamine, K.

    2001-03-01

    Using the first-principles Hartree-Fock Cluster procedure, and incorporating many-body effects, we have investigated the trapping of He^+ at the tetrahedral and octahedral interstitial sites in solid hydrogen. The binding energies of He^+ were found to increase significantly when second-nearest neighbor H2 molecules were included in the calculation as compared to the case when only first-nearest neighbors were present. Expanding the cluster to include third-nearest neighbors, we found good convergence in the binding energy of He^+. These results can be taken as evidence that He^+ is trapped more strongly in solid hydrogen than in the liquid, as suggested by recent data from Muon Catalyzed Fusion experiments(N. Kawamura et al., Phys. Lett. B465), 74 (1999). Possible implications for the trapping of other helium entities (e.g. He^0 or (He-H)^+) will be discussed.

  18. Simultaneous Measurements of Superradiance at Multiple Wavelength from Helium Excited States: II. Analysis

    NASA Astrophysics Data System (ADS)

    Ohae, Chiaki; Harries, James R.; Iwayama, Hiroshi; Kawaguchi, Kentarou; Kuma, Susumu; Miyamoto, Yuki; Nagasono, Mitsuru; Nakajima, Kyo; Nakano, Itsuo; Shigemasa, Eiji; Sasao, Noboru; Uetake, Satoshi; Wakabayashi, Tomonari; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

    2016-03-01

    Previous experimental studies of superradiance (SR) in multi-level systems have been explainable using the predictions of the well-known simple two-level SR model. However our recent study [K. Nakajima et al., J. Phys. Soc. Jpn. 84, 054301 (2015)] using EUV free-electron laser excitation of helium atoms, where SR was observed at wavelengths of 502, 668, and 728 nm, revealed behaviour which necessitates a full multi-level treatment of the SR development. In this paper, we report simulations of the initial excitation by the FEL pulses, and the subsequent development of multi-level SR. The results of the simulation reproduce the experimental findings, and reveal that competitive SR on two transitions with a common upper level plays an important role in the development of the system.

  19. Dynamical phases in a one-dimensional chain of heterospecies Rydberg atoms with next-nearest-neighbor interactions

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Zhang, Lu; Zhai, Jingjing; Zhang, Weiping

    2015-12-01

    We theoretically investigate the dynamical phase diagram of a one-dimensional chain of laser-excited two-species Rydberg atoms. The existence of a variety of unique dynamical phases in the experimentally achievable parameter region is predicted under the mean-field approximation, and the change in those phases when the effect of the next-nearest-neighbor interaction is included is further discussed. In particular, we find that the com-petition of the strong Rydberg-Rydberg interactions and the optical excitation imbalance can lead to the presence of complex multiple chaotic phases, which are highly sensitive to the initial Rydberg-state population and the strength of the next-nearest-neighbor interactions.

  20. Rydberg bands in the near UV spectra of substituted pyrroles

    NASA Astrophysics Data System (ADS)

    Nyulászi, L.

    1991-03-01

    Vapour phase and solution spectra of pyrrole and three of its derivatives were investigated in the near UV region. Band systems disappearing from the solution spectra could be assigned to Rydberg transitions if the band profiles were compared with those of the corresponding UPS bands and with other Rydbergs of the same molecule. In the case of each compound, four Rydbergs originating from the uppermost π orbital were found, terminating at 3 s, 3 p and 3 p', 3 d Rydberg orbitals.

  1. Transient intrashell resonances in Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Fregenal, D.; Førre, M.; Horsdal, E.; Fisker, C.; Kjær, N. A.

    2008-05-01

    Rydberg atoms of principal quantum number n in a superposition of a harmonic and a slowly varying field pass through several resonances with the harmonic field of frequency Ω as the splitting ω of the shell by the slow field varies. These transient resonances which are met when ω sime NΩ, where N is an integer, have been studied for the n = 25 shell of Li. Coherent elliptic states were prepared and used as initial states, and the dynamics was probed by the probability Pa for the atom to remain in the initial state. The harmonic field \\vec{E}_\\Omega was circularly polarized and had constant amplitude, and the slow field varied such that ω at first decreased, then went through a minimum and finally increased to bring the atoms into resonance at two different times. This led to interference patterns in Pa(ω0), where ω0 is the minimum splitting. These were quite regular for coherent elliptic states of low eccentricity e and for strong fields \\vec{E}_\\Omega , but less regular for large e and weak \\vec{E}_\\Omega . A few states of Li(n = 25) are not hydrogenic due to quantum defects from the (1s)2 core. Without quantum defects the dynamics can be reduced to that of two spin-\\case{1}{2} particles and this reproduces the regular patterns quite well. A full quantal treatment, which is required if quantum defects are important, shows that the more irregular patterns are the result of quite complex dynamics involving non-hydrogenic quasi-eigenstates.

  2. Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology

    NASA Astrophysics Data System (ADS)

    Hankin, Aaron Michael

    With the advent of laser cooling and trapping, neutral atoms have become a foundational source of accuracy for applications in metrology and are showing great potential for their use as qubits in quantum information. In metrology, neutral atoms provide the most accurate references for the measurement of time and acceleration. The unsurpassed stability provided by these systems make neutral atoms an attractive avenue to explore applications in quantum information and computing. However, to fully investigate the field of quantum information, we require a method to generate entangling interactions between neutral-atom qubits. Recent progress in the use of highly-excited Rydberg states for strong dipolar interactions has shown great promise for controlled entanglement using the Rydberg blockade phenomenon. I report the use of singly-trapped cesium-133 atoms as qubits for applications in metrology and quantum information. Each atom provides a physical basis for a single qubit by encoding the required information into the ground-state hyperfine structure of cesium-133. Through the manipulation of these qubits with microwave and optical frequency sources, we demonstrate the capacity for arbitrary single-qubit control by driving qubit rotations in three orthogonal directions on the Bloch sphere. With this control, we develop an atom interferometer that far surpasses the force sensitivity of other approaches by applying the well-established technique of light-pulsed atom-matterwave interferometry to single atoms. Following this, we focus on two-qubit interactions using highly-excited Rydberg states. Through the development of a unique single-photon approach to Rydberg excitation using an ultraviolet laser at 319 nm, we observe the Rydberg blockade interaction between atoms separated by 6.6(3) μm. Motivated by the observation of Rydberg blockade, we study the application of Rydberg-dressed states for a quantum controlled-phase gate. Using a realistic simulation of the dressed-state dynamics, we calculate a controlled-phase gate fidelity of 94% that is primarily limited by Doppler frequency shifts. Finally, we employ our single-photon excitation laser to measure the Rydberg-dressed interaction, thus demonstrating the viability of this approach.

  3. Electric field sensing near the surface microstructure of an atom chip using cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Martin, J. D. D.

    2013-05-01

    Rydberg atoms may enable hybrid systems that combine the benefits of gas-phase atoms with those of solid-state devices. However, these hybrid systems will require atoms to be located near a heterogeneous surface with exposed metal electrodes and dielectric insulators, which are sources of uncontrollable and unwanted electric fields. With this motivation, we have measured the electric fields near the heterogeneous metal-dielectric surface of an atom chip using cold Rydberg atoms. We have also developed a technique for reducing the influence of dc and low-frequency electric fields on Rydberg atom transitions, while retaining their sensitivity to high-frequency resonant fields. Work performed in collaboration with J. D. Carter, L. A. Jones, and O. Cherry and supported by NSERC.

  4. Electromagnetically induced transparency with cold Rydberg atoms: Superatom model beyond the weak-probe approximation

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Mou; Yan, Dong; Tian, Xue-Dong; Cui, Cui-Li; Wu, Jin-Hui

    2014-03-01

    We present an improved superatom model for examining nonlinear optical responses of cold Rydberg atoms in the regime of electromagnetically induced transparency (EIT). By going beyond the weak-probe approximation, we find that several higher-order collective states should be included to correctly describe the coherent Rydberg excitation of superatoms. Otherwise, numerical results based on the simple ladder system of superatoms will contribute wrong predictions on light intensity and photon correlation of the transmitted probe field. In particular, a great photon-bunching effect will be improperly expected somewhere out of the EIT window in one dilute atomic sample. The essence of this improved superatom model lies in that it can provide reliable predictions on the nonlinear Rydberg-EIT phenomena even in dense atomic samples and may be extended to realize lossless conditional light interactions in appropriate multilevel systems exhibiting dipole blockade.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  6. Interaction of the NO 3pπ (C {sup 2}Π) Rydberg state with RG (RG = Ne, Kr, and Xe): Potential energy surfaces and spectroscopy

    SciTech Connect

    Ershova, Olga V.; Besley, Nicholas A. Wright, Timothy G.; Kłos, Jacek

    2015-01-21

    We present new potential energy surfaces for the interaction of NO(C {sup 2}Π) 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.

  7. Rydberg-Induced Solitons: Three-Dimensional Self-Trapping of Matter Waves

    SciTech Connect

    Maucher, F.; Henkel, N.; Pohl, T.; Saffman, M.; Krolikowski, W.; Skupin, S.

    2011-04-29

    We propose a scheme for the creation of stable three-dimensional bright solitons in Bose-Einstein condensates, i.e., the matter-wave analog of so-called spatiotemporal ''light bullets.'' Off-resonant dressing to Rydberg nD states is shown to provide nonlocal attractive interactions, leading to self-trapping of mesoscopic atomic clouds by a collective excitation of a Rydberg atom pair. We present detailed potential calculations and demonstrate the existence of stable solitons under realistic experimental conditions by means of numerical simulations.

  8. Simultaneous ionization-excitation of helium to the 3s, 3p, and 3d states of He+

    NASA Astrophysics Data System (ADS)

    Zatsarinny, Oleg; Bartschat, Klaus

    2015-05-01

    We extended our work on ionization of helium with simultaneous excitation to the n = 2 states to include the n = 3 manifold of the residual ion. This requires the inclusion of pseudo-states constructed on the 3s, 3p, and 3d ionic core. We used a parallelized version of the B-spline R-matrix (BSR) package to perform a calculation with 1,254 target states, resulting in up to 3,027 coupled channels and matrices of rank up to 200,000 to be diagonalized. The triple-differential cross section (TDCS) was extracted by the projection method. We obtain excellent agreement with experiment regarding the angular dependence of the TDCS for all kinematical situations available for comparison. Some discrepancies remain for the absolute magnitude. Results for the n = 2 states are stable and closely agree with previous predictions. Work supported by the United States National Science Foundation under grants No. PHY-1212450, PHY-1430245 and the XSEDE allocation PHY-090031.

  9. Theory of two-photon double ionization of helium at the sequential threshold

    SciTech Connect

    Bachau, H.

    2011-03-15

    We analyze in this paper the process of double-electron ejection through two-photon absorption from the fundamental state of helium. We focus on the case of photon energies close to 2 a.u., which marks the threshold between direct and sequential double-ionization regimes. We demonstrate the crucial role of two-photon excitation-plus-ionization process of nlk{sup '}l{sup '} Rydberg series. We show that the latter channel must be taken into account in the theory in order to properly describe two-electron ejection. A simple expression is derived for the electron energy spectrum, leading to better insights into the physics underlying two-photon absorption close to the sequential threshold.

  10. Landau-Zener Transitions in Frozen Pairs of Rydberg Atoms

    SciTech Connect

    Saquet, Nicolas; Cournol, Anne; Beugnon, Jerome; Robert, Jacques; Pillet, Pierre; Vanhaecke, Nicolas

    2010-04-02

    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.

  11. Optimal control for Rydberg quantum technology building blocks

    NASA Astrophysics Data System (ADS)

    Müller, Matthias M.; Pichler, Thomas; Montangero, Simone; Calarco, Tommaso

    2016-04-01

    We consider a platform for quantum technology based on Rydberg atoms in optical lattices where each atom encodes one qubit of information and external lasers can manipulate their state. We demonstrate how optimal control theory enables the functioning of two specific building blocks on this platform: We engineer an optimal protocol to perform a two-qubit phase gate and to transfer the information within the lattice among specific sites. These two elementary operations allow to design very general operations like storage of atoms and entanglement purification as, for example, needed for quantum repeaters.

  12. The kicked Rydberg atom: Regular and stochastic motion

    SciTech Connect

    Burgdoerfer, J.

    1988-01-01

    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.

  13. Controlled photon-photon interactions using Rydberg polaritons

    NASA Astrophysics Data System (ADS)

    Adams, Charles

    2014-05-01

    By coupling a strong optical transition to a highly-excited Rydberg state it is possible to realise giant optical non-linearities and hence strong photon-photon interactions. A remaining challenge is to implement an interaction that does not distort the photon mode and hence to realise high-fidelity photonic quantum gates. In this talk we will discuss how to control the photon-photon interact using microwave fields and how this could be used to implement deterministic non-linear optical computation. Acknowledgements EU Marie Curie Initial Training Network coherence.

  14. Mapping the dipole-dipole interaction among ultracold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Fahey, Donald P.; Carroll, Thomas J.; Noel, Michael W.

    2014-05-01

    A long-range dipole-dipole interaction couples the atoms in an ultracold Rydberg gas. This can lead to changes in the spatial configuration of states over an extended region. We discuss the use of selective field ionization with a spatially sensitive ion detector to directly map dipole-dipole interaction induced level shifts and energy exchange over large distances in a MOT. Experimental and simulation results will be presented. This material is based upon work supported by the National Science Foundation under Grant No. 1205895.

  15. Effect of dispersion forces on squeezing with Rydberg atoms

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  16. High-Rydberg Xenon Submillimeter-Wave Detector

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara

    1987-01-01

    Proposed detector for infrared and submillimeter-wavelength radiation uses excited xenon atoms as Rydberg sensors instead of customary beams of sodium, potassium, or cesium. Chemically inert xenon easily stored in pressurized containers, whereas beams of dangerously reactive alkali metals must be generated in cumbersome, unreliable ovens. Xenon-based detector potential for infrared astronomy and for Earth-orbiter detection of terrestrial radiation sources. Xenon atoms excited to high energy states in two stages. Doubly excited atoms sensitive to photons in submillimeter wavelength range, further excited by these photons, then ionized and counted.

  17. Atomic-Orbital Close-Coupling Calculations Of Electron Capture From Hydrogen Atoms Into Highly Excited Rydberg States Of Multiply Charged Ions

    SciTech Connect

    Igenbergs, Katharina; Wallerberger, Markus; Aumayr, Friedrich

    2011-06-01

    Collisions of neutral hydrogen atoms with multiply charged ions have been studied in the past using the semi-classical atomic-orbital close-coupling method. We present total and state-resolved cross sections for charge exchange as well as ionization. The advent of supercomputers and parallel programming facilities now allow treatment of collision systems that have been out of reach before, because much larger basis sets involving high quantum numbers are now feasible.

  18. On the binary helium star DY Centauri: chemical composition and evolutionary state

    SciTech Connect

    Pandey, Gajendra; Rao, N. Kameswara; Jeffery, C. Simon; Lambert, David L. E-mail: nkrao@iiap.res.in E-mail: dll@astro.as.utexas.edu

    2014-10-01

    DY Cen has shown a steady fading of its visual light by about one magnitude in the last 40 yr, suggesting a secular increase in its effective temperature. We have conducted non-local thermodynamic equilibrium (LTE) and LTE abundance analyses to determine the star's effective temperature, surface gravity, and chemical composition using high-resolution spectra obtained over two decades. The derived stellar parameters for three epochs suggest that DY Cen has evolved at a constant luminosity and has become hotter by about 5000 K in 23 yr. We show that the derived abundances remain unchanged for the three epochs. The derived abundances of the key elements, including F and Ne, are as observed for the extreme helium stars resulting from a merger of a He white dwarf with a C-O white dwarf. Thus DY Cen by chemical composition appears to also be a product of a merger of two white dwarfs. This appearance seems to be at odds with the recent suggestion that DY Cen is a single-lined spectroscopic binary.

  19. Toward Femtosecond Time-Resolved Studies of Solvent-Solute Energy Transfer in Doped Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Bacellar, C.; Ziemkiewicz, M. P.; Leone, S. R.; Neumark, D. M.; Gessner, O.

    2015-05-01

    Superfluid helium nanodroplets provide a unique cryogenic matrix for high resolution spectroscopy and ultracold chemistry applications. With increasing photon energy and, in particular, in the increasingly important Extreme Ultraviolet (EUV) regime, the droplets become optically dense and, therefore, participate in the EUV-induced dynamics. Energy- and charge-transfer mechanisms between the host droplets and dopant atoms, however, are poorly understood. Static energy domain measurements of helium droplets doped with noble gas atoms (Xe, Kr) indicate that Penning ionization due to energy transfer from the excited droplet to dopant atoms may be a significant relaxation channel. We have set up a femtosecond time-resolved photoelectron imaging experiment to probe these dynamics directly in the time-domain. Droplets containing 104 to 106 helium atoms and a small percentage (<10-4) of dopant atoms (Xe, Kr, Ne) are excited to the 1s2p Rydberg band by 21.6 eV photons produced by high harmonic generation (HHG). Transiently populated states are probed by 1.6 eV photons, generating time-dependent photoelectron kinetic energy distributions, which are monitored by velocity map imaging (VMI). The results will provide new information about the dynamic timescales and the different relaxation channels, giving access to a more complete physical picture of solvent-solute interactions in the superfluid environment. Prospects and challenges of the novel experiment as well as preliminary experimental results will be discussed.

  20. Measurement of relative cross sections for simultaneous ionization and excitation of the helium 4 2s and 4 2p states

    NASA Technical Reports Server (NTRS)

    Sutton, J. F.

    1972-01-01

    The relative cross sections for simultaneous ionization and excitation of helium by 200-eV electrons into the 4 2s and 4 2p states were measured via a fast delayed coincidence technique. Results show good agreement with the relative cross sections for single electron excitation of helium and hydrogen. An application of the results of the measurement to the development of ultraviolet intensity standard is suggested. This technique involves the use of known branching ratios, a visible light flux reference, and the measured relative cross sections.

  1. Trapping and coherent manipulation of a Rydberg atom on a microfabricated device: a proposal

    NASA Astrophysics Data System (ADS)

    Mozley, J.; Hyafil, P.; Nogues, G.; Brune, M.; Raimond, J.-M.; Haroche, S.

    2005-08-01

    We propose to apply atom-chip techniques to the trapping of a single atom in a circular Rydberg state. The small size of microfabricated structures will allow for trap geometries with microwave cut-off frequencies high enough to inhibit the spontaneous emission of the Rydberg atom, paving the way to complete control of both external and internal degrees of freedom over very long times. Trapping is achieved using carefully designed electric fields, created by a simple pattern of electrodes. We show that it is possible to excite, and then trap, one and only one Rydberg atom from a cloud of ground state atoms confined on a magnetic atom chip, itself integrated with the Rydberg trap. Distinct internal states of the atom are simultaneously trapped, providing us with a two-level system extremely attractive for atom-surface and atom-atom interaction studies. We describe a method for reducing by three orders of magnitude dephasing due to Stark shifts, induced by the trapping field, of the internal transition frequency. This allows for, in combination with spin-echo techniques, maintenance of an internal coherence over times in the second range. This method operates via a controlled light shift rendering the two internal states' Stark shifts almost identical. We thoroughly identify and account for sources of imperfection in order to verify at each step the realism of our proposal.

  2. Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4

    NASA Astrophysics Data System (ADS)

    Gim, Yeongrok; Lee, Chun-Woo

    2014-10-01

    The 50 singlet states of LiH composed of 49 Rydberg states and one non-Rydberg ionic state derivable from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4, are studied using the multi-reference configuration interaction method combined with the Stuttgart/Köln group's effective core potential/core polarization potential method. Basis functions that can yield energy levels up to the 6g orbital of Li have been developed, and they are used with a huge number of universal Kaufmann basis functions for Rydberg states. The systematics and regularities of the physical properties such as potential energies, quantum defects, permanent dipole moments, transition dipole moments, and nonadiabatic coupling matrix elements of the Rydberg series are studied. The behaviors of potential energy curves and quantum defect curves are explained using the Fermi approximation. The permanent dipole moments of the Rydberg series reveal that they are determined by the sizes of the Rydberg orbitals, which are proportional to n2. Interesting mirror relationships of the dipole moments are observed between l-mixed Rydberg series, with the rule Δl = ±1, except for s-d mixing, which is also accompanied by n-mixing. The members of the l-mixed Rydberg series have dipole moments with opposite directions. The first derivatives of the dipole moment curves, which show the charge-transfer component, clearly show not only mirror relationships in terms of direction but also oscillations. The transition dipole moment matrix elements of the Rydberg series are determined by the small-r region, with two consequences. One is that the transition dipole moment matrix elements show n-3/2 dependence. The other is that the magnitudes of the transition dipole moment matrix elements decrease rapidly as l increases.

  3. Studies of singlet Rydberg series of LiH derived from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4

    SciTech Connect

    Gim, Yeongrok; Lee, Chun-Woo

    2014-10-14

    The 50 singlet states of LiH composed of 49 Rydberg states and one non-Rydberg ionic state derivable from Li(nl) + H(1s), with n ≤ 6 and l ≤ 4, are studied using the multi-reference configuration interaction method combined with the Stuttgart/Köln group's effective core potential/core polarization potential method. Basis functions that can yield energy levels up to the 6g orbital of Li have been developed, and they are used with a huge number of universal Kaufmann basis functions for Rydberg states. The systematics and regularities of the physical properties such as potential energies, quantum defects, permanent dipole moments, transition dipole moments, and nonadiabatic coupling matrix elements of the Rydberg series are studied. The behaviors of potential energy curves and quantum defect curves are explained using the Fermi approximation. The permanent dipole moments of the Rydberg series reveal that they are determined by the sizes of the Rydberg orbitals, which are proportional to n{sup 2}. Interesting mirror relationships of the dipole moments are observed between l-mixed Rydberg series, with the rule Δl = ±1, except for s–d mixing, which is also accompanied by n-mixing. The members of the l-mixed Rydberg series have dipole moments with opposite directions. The first derivatives of the dipole moment curves, which show the charge-transfer component, clearly show not only mirror relationships in terms of direction but also oscillations. The transition dipole moment matrix elements of the Rydberg series are determined by the small-r region, with two consequences. One is that the transition dipole moment matrix elements show n{sup −3/2} dependence. The other is that the magnitudes of the transition dipole moment matrix elements decrease rapidly as l increases.

  4. Measurement and numerical calculation of Rubidium Rydberg Stark spectra

    NASA Astrophysics Data System (ADS)

    Grimmel, Jens; Mack, Markus; Karlewski, Florian; Jessen, Florian; Reinschmidt, Malte; Sándor, Nóra; Fortágh, József

    2015-05-01

    We report on the measurement of Stark shifted energy levels of 87Rb Rydberg atoms in static electric fields by means of electromagnetically induced transparency (EIT). Electric field strengths of up to 500 V cm-1, ranging beyond the classical ionization threshold, were applied using electrodes inside a glass cell with rubidium vapour. Stark maps for principal quantum numbers n = 35 and n = 70 have been obtained with high signal-to-noise ratio for comparison with results from ab initio calculations following the method described in (Zimmerman et al 1979 Phys. Rev. A 20 2251), which was originally only verified for states around n = 15. We also calculate the dipole matrix elements between low-lying states and Stark shifted Rydberg states to give a theoretical estimate of the relative strength of the EIT signal. The present work significantly extends the experimental verification of this numerical method in the range of both high principal quantum numbers and high electric fields with an accuracy of up to 2 MHz.

  5. Dipole-dipole interaction between rubidium Rydberg atoms

    SciTech Connect

    Altiere, Emily; Fahey, Donald P.; Noel, Michael W.; Smith, Rachel J.; Carroll, Thomas J.

    2011-11-15

    Ultracold Rydberg atoms in a static electric field can exchange energy via the dipole-dipole interaction. The Stark effect shifts the energy levels of the atoms which tunes the energy exchange into resonance at specific values of the electric field (Foerster resonances). We excite rubidium atoms to Rydberg states by focusing either a 480 nm beam from a tunable dye laser or a pair of diode lasers into a magneto-optical trap. The trap lies at the center of a configuration of electrodes. We scan the electric field by controlling the voltage on the electrodes while measuring the fraction of atoms that interact. Dipole-dipole interaction spectra are presented for initially excited rubidium nd states for n=31 to 46 and for four different pairs of initially excited rubidium ns states. We also present the dipole-dipole interaction spectra for individual rubidium 32d (j, m{sub j}) fine structure levels that have been selectively excited. The data are compared to calculated spectra.

  6. Population transfer collisions involving nD Rydberg atoms in a CO2 optical dipole trap

    NASA Astrophysics Data System (ADS)

    Kondo, Jorge M.; Goncalves, Luis F.; Tallant, Jonathan E.; Marcassa, Luis G.

    2014-05-01

    There has been an increasing interest in cold Rydberg atoms over the last several years. The primary reason for this attention is that interactions between Rydberg atoms are strong and lead to many interesting and useful phenomena, which require high atomic density samples. In this work, we have loaded Rb atoms into a CO2 optical dipole trap. After the loading, we turn off the dipole trap and excite the Rydberg state using a combination of two cw laser beams at 780 nm and 480 nm respectively. Finally, the Rydberg atoms are detected using pulsed field ionization technique. By analyzing the electrons signal, we can study the population transfer from the nD state to the (n + 2)P as a function of the atomic density for 37 <= n <= 45. As the atomic density increases, the excitation of the nD state saturates, suggesting the occurrence of dipole blockade. Nevertheless, the (n + 2)P is quadratically proportional to the nD population. We have also investigated the role of a dc electrical field in such process. This work was supported by Fapesp and INCT-IQ.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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 μs 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}}.

  8. Predissociative linewidths of (4pσ) M 2Sigma + (v=1) and (3dσ,π) H 2Sigma + , Hscript 2Π (v=2) Rydberg states of NO studied by the two-color laser-induced grating technique

    NASA Astrophysics Data System (ADS)

    Ishii, Juntarou; Uehara, Kiyoji; Tsukiyama, Koichi

    1995-06-01

    The two-color laser-induced grating (TC-LIG) technique has been employed to probe the predissociative Rydberg states (4pσ) M 2Σ+ (v=1) and (3dσ,π) H 2Σ+, H' 2Π± (v=2) and the non-Rydberg B 2Π (v=26) state of nitric oxide. The ultraviolet pump laser frequency is fixed to a specific rotational line of the A 2Σ+ (v'=1 and 2)←X 2Π3/2 (v`=0) transition of NO. Interference of two pump laser beams crossing at a small angle in the gas sample forms a population grating. Then, the visible probe laser beam is diffracted off the grating as the signal beam when the probe laser frequency is resonant to a transition from the rotational level excited by the pump laser. Term values and rotational assignments of the H 2Σ+, H' 2Π± (v=2)-B 2Π3/2 (v=26) states have been established for the first time, resulting in the value of ˜1.77 cm-1 for the l-uncoupling constant. Line broadenings due to predissociation are observed in the TC-LIG spectra for the M 2Σ+ (v=1) and H 2Σ+, H' 2Π+ (v=2) states. The linewidths of the M 2Σ+ (v=1) state show no marked rotational dependence except for the N=4 level which is locally perturbed. On the other hand, the predissociative lifetimes of the H 2Σ+ and H' 2Π+ (v=2) states exhibit a significant rotational dependence: The linewidth of the former state decreases with N, while the reverse tendency is seen for the latter. The mixing between the H 2Σ+ and H' 2Π+ states caused by l-uncoupling explains the observed rotational dependence successfully.

  9. Robust quantum logic in neutral atoms via adiabatic Rydberg dressing

    DOE PAGESBeta

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

    2015-01-28

    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 σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces actingmore » on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10-3.« less

  10. Robust quantum logic in neutral atoms via adiabatic Rydberg dressing

    SciTech Connect

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

    2015-01-28

    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 σ+- 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. As a result, for reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10-3.

  11. Ionization of Rydberg atoms colliding with a metal surface

    SciTech Connect

    Sjakste, J.; Borisov, A. G.; Gauyacq, J. P.

    2006-04-15

    We report on a theoretical study of the ionization process of Xe* Rydberg atoms colliding with a metal surface, in the presence of an external electric field. The evolution of the Xe* outer electron is studied by a wave packet propagation approach, allowing to include all dynamical aspects of the collision, in particular nonadiabatic inter-Rydberg transitions. We investigate how the different Xe* Stark states formed in the external field couple together and ionize on the surface and how the different polarizations of the electronic cloud in the Xe* states are reflected in their ionization properties. We show that the presence of the external electric field can significantly perturb the dynamics of the ionization process. Our results account for recent results from Dunning et al. [Nucl. Inst. Meth. B 203, 69 (2003)]. In particular, it is explained how the external electric field present in the experimental procedure of Dunning et al. leads to the apparent absence of a polarization effect in the ionization process.

  12. The Rydberg electronic transitions of the hydrogen molecule

    SciTech Connect

    Babb, J.F.; Chang, E.S. )

    1992-01-01

    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}.

  13. Quantum interference in the field ionization of Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Feynman, Rachel; Hollingsworth, Jacob; Vennettilli, Michael; Budner, Tamas; Zmiewski, Ryan; Fahey, Donald P.; Carroll, Thomas J.; Noel, Michael W.

    2015-10-01

    We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of the three | mj| sublevels of the 37 d5 /2 Rydberg state. After some delay, during which the relative phases of the superposition components can evolve, we apply an electric field pulse to ionize the Rydberg electron and send it to a detector. The electron traverses many avoided crossings in the Stark levels as it ionizes. The net effect of the transitions at these crossings is to mix the amplitudes of the initial superposition into the same final states at ionization. Similar to a Mach-Zehnder interferometer, the three initial superposition components have multiple paths by which they can arrive at ionization and, since the phases of those paths differ, we observe quantum beats as a function of the delay time between excitation and initiation of the ionization pulse. We present a fully quantum-mechanical calculation of the electron's path to ionization and the resulting interference pattern.

  14. Molecular ions, Rydberg spectroscopy and dynamics

    SciTech Connect

    Jungen, Ch.

    2015-01-22

    Ion spectroscopy, Rydberg spectroscopy and molecular dynamics are closely related subjects. Multichannel quantum defect theory is a theoretical approach which draws on this close relationship and thereby becomes a powerful tool for the study of systems consisting of a positively charged molecular ion core interacting with an electron which may be loosely bound or freely scattering.

  15. Alignment of high Rydberg states in hydrogen

    SciTech Connect

    Berry, H.G.; DeHaes, J.C.; Neek, D.K.; Somerville, L.P.

    1984-01-01

    We have measured the light yields and polarizations of the light emitted from several Balmer transitions in atomic hydrogen following beam foil excitation of protons at energies of 50 to 150 keV. The polarizations have been measured as a function of distance downbeam from the exciter foil for several transitions. The measurements indicate a very strong initial alignment which is then perturbed by surface fields out to several mm from the surface. 8 references, 7 figures.

  16. Xe2 gerade Rydberg states observed in the afterglow of a microplasma by laser spectroscopy of a^3 {Σ }_u^ + ( {1_u,O_u^ - }) absorption in the green (545-555 nm) and near-infrared (675-800 nm)

    NASA Astrophysics Data System (ADS)

    Wagner, C. J.; Galvin, T. C.; Eden, J. G.

    2014-06-01

    Bound←bound transitions of the Xe dimer at small internuclear separation (R < 4.0 Å) have been observed in the 545-555 nm and 675-800 nm spectral regions by laser spectroscopy in the afterglow of a pulsed Xe microplasma with a volume of ˜160 nl. Transient suppression of Xe2 A^1 {Σ }_u^ + ( {O_u^ + }) to X^1 {Σ }_g^ + ( {O_g^ + }) emission in the vacuum ultraviolet (˜172 nm), induced by laser excitation of {Ω }_g leftarrow a^3 {Σ }_u^ + ( {1_u,O_u^ - }) [Rydberg←Rydberg] transitions of the molecule, has confirmed the existence of structure between 720 and 770 nm (reported by Killeen and Eden [J. Chem. Phys. 84, 6048 (1986)]) but also reveals red-degraded vibrational bands extending to wavelengths beyond 800 nm. Spectral simulations based on calculations of Franck-Condon factors for assumed {Ω }_g leftarrow a^3 {Σ }_u^ + transitions involving Ω = 0±,1 gerade Rydberg states suggest that the upper level primarily responsible for the observed spectrum is an Ω = 1 state correlated, in the separated atom limit, with Xe(5p6 1S0) + Xe(5p5 6p) and built on a predominantly A2Π3/2g molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1_g leftarrow 1_u,O_u^ ± absorptive transitions are determined to be Te = 13 000 ± 150 cm-1, ω _e^' = 120 ± 10 cm^{ - 1}, ω _e^' x_e^' = 1.1 ± 0.4 cm^{ - 1}, De = 3300 ± 300 cm-1, and {Δ }R_e = R_e^' - R_e^' ' } = 0.3 ± 0.1 {Å} which are in general agreement with the theoretical predictions of the pseudopotential hole-particle formalism, developed by Jonin and Spiegelmann [J. Chem. Phys. 117, 3059 (2002)], for both the (5)1g and ( 3)O_g^ + states of Xe2. These spectra exhibit the most extensive vibrational development, and provide evidence for the first molecular core-switching transition, observed to date for any of the rare gas dimers at small R (<4 Ǻ). Experiments in the green (545-555 nm) also provide improved absorption spectra, relative to data reported in 1986 and 1999, associated with Xe2 Rydberg states derived from the Xe(7p) orbital.

  17. Ponderomotive spectroscopy: Driving Rydberg transitions using harmonics and magic wavelengths of an intensity-modulated optical lattice

    NASA Astrophysics Data System (ADS)

    Moore, Kaitlin; Raithel, Georg

    2015-05-01

    We describe recent developments in a novel spectroscopic method that couples Rydberg states using an intensity-modulated optical lattice. The method is fundamentally different from traditional microwave spectroscopy: it engages the A . A (ponderomotive) term rather than the A . p term of the atom-field interaction Hamiltonian, allowing us to drive microwave transitions between Rydberg states with optical spatial resolution, free from electric dipole selection rules. Experimentally, cold Rb Rydberg atoms are confined in a 1064 nm optical lattice. Transitions are driven by modulating the lattice intensity using a tunable electro-optic fiber modulator. Recently we have driven dipole-forbidden transitions in third and fifth order, at frequencies up to 94 GHz, using temporal harmonics in the intensity-modulated lattice. We also demonstrate, for two separate transitions, the novel use of a magic wavelength condition in ponderomotive spectroscopy. We discuss experimental results and propose applications of this method to a precision measurement of the Rydberg constant using circular-state Rydberg atoms. Support received from NSF, NIST, NASA

  18. High-order-harmonic generation from Rydberg atoms driven by plasmon-enhanced laser fields

    NASA Astrophysics Data System (ADS)

    Tikman, Y.; Yavuz, I.; Ciappina, M. F.; Chacón, A.; Altun, Z.; Lewenstein, M.

    2016-02-01

    We theoretically investigate high-order-harmonic generation (HHG) in Rydberg atoms driven by spatially inhomogeneous laser fields, induced, for instance, by plasmonic enhancement. It is well known that the laser intensity should exceed a certain threshold in order to stimulate HHG when noble gas atoms in their ground state are used as an active medium. One way to enhance the coherent light coming from a conventional laser oscillator is to take advantage of the amplification obtained by the so-called surface plasmon polaritons, created when a low-intensity laser field is focused onto a metallic nanostructure. The main limitation of this scheme is the low damage threshold of the materials employed in the nanostructure engineering. In this work we propose the use of Rydberg atoms, driven by spatially inhomogeneous, plasmon-enhanced laser fields, for HHG. We exhaustively discuss the behavior and efficiency of these systems in the generation of coherent harmonic emission. Toward this aim we numerically solve the time-dependent Schrödinger equation for an atom, with an electron initially in a highly excited n th Rydberg state, located in the vicinity of a metallic nanostructure. In this zone the electric field changes spatially on scales relevant for the dynamics of the laser-ionized electron. We first use a one-dimensional model to investigate systematically the phenomena. We then employ a more realistic situation, in which the interaction of a plasmon-enhanced laser field with a three-dimensional hydrogen atom is modeled. We discuss the scaling of the relevant input parameters with the principal quantum number n of the Rydberg state in question and demonstrate that harmonic emission can be achieved from Rydberg atoms well below the damage threshold, thus without deterioration of the geometry and properties of the metallic nanostructure.

  19. Green's function Monte Carlo calculation for the ground state of helium trimers

    SciTech Connect

    Cabral, F.; Kalos, M.H.

    1981-02-01

    The ground state energy of weakly bound boson trimers interacting via Lennard-Jones (12,6) pair potentials is calculated using a Monte Carlo Green's Function Method. Threshold coupling constants for self binding are obtained by extrapolation to zero binding.

  20. Designing Frustrated Quantum Magnets with Laser-Dressed Rydberg Atoms

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    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.

  1. Designing frustrated quantum magnets with laser-dressed Rydberg atoms.

    PubMed

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

    2015-05-01

    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. PMID:25978228

  2. Electroproduction of strangeness on (Lambda)H-3,4 bound states on helium

    SciTech Connect

    F. Dohrmann; D. Abbott; A. Ahmidouch; P. Ambrozewicz; C. S. Armstrong; J. Arrington; R. Asaturyan; K. Assamagan; S. Avery; K. Bailey; S. Beedoe; H. Bitao; H. Breuer; D. S. Brown; R. Carlini; J. Cha; N. Chant; E. Christy; A. Cochran; L. Cole; G. Collins; C. Cothran; J. Crowder; W. J. Cummings; S. Danagoulian; F. Duncan; J. Dunne; D. Dutta; T. Eden; M. Elaasar; R. Ent; L. Ewell; H. Fenker; H. T. Fortune; Y. Fujii; L. Gan; H. Gao; K. Garrow; D. F. Geesaman; P. Gueye; K. Gustafsson; K. Hafidi; J. O. Hansen; W. Hinton; H. E. Jackson; H. Juengst; C. Keppel; A. Klein; D. Koltenuk; Y. Liang; J. H. Liu; A. Lung; D. Mack; R. Madey; P. Markowitz; C. J. Martoff; D. Meekins; J. Mitchell; T. Miyoshi; H. Mkrtchyan; R. Mohring; S. K. Mtingwa; B. Mueller; T. G. O'Neill; G. Niculescu; I. Niculescu; D. Potterveld; J. W. Price; B. A. Raue; P. E. Reimer; J. Reinhold; J. Roche; P. Roos; M. Sarsour; Y. Sato; G. Savage; R. Sawafta; R. E. Segel; A. Yu. Semenov; S. Stepanyan; V. Tadevosian; S. Tajima; L. Tang; B. Terburg; A. Uzzle; S. Wood; H. Yamaguchi; C. Yan; C. Yan; L. Yuan; M. Zeier; B. Zeidman; B. Zihlmann

    2005-05-01

    The A(e,eK+)X reaction has been investigated at Jefferson Laboratory. Data were taken for Q{sup 2} approx. 0.35 GeV{sup 2} at a beam energy of 3.245 GeV for 1H,3He and 4He targets. Evidence for Lambda-hypernuclear bound states is seen for 3,4He targets. This is the first time that the electroproduction of these hypernuclei has been observed.

  3. Guiding and Trapping of Rydberg atoms in a linear magnetic atom guide

    NASA Astrophysics Data System (ADS)

    Hempel, Cornelius; Traxler, Mallory; Vaidya, Varun; Raithel, Georg

    2009-05-01

    We describe an experimental approach and present results on the dynamics of Rydberg atoms in a high-gradient magnetic guiding and trapping apparatus. The setup consists of two parallel current-carrying wires providing a quadrupole trapping potential with a gradient of 2.7 kG.cm-1 at its center. A Ioffe-Pritchard type trap can be formed by superposition of an inhomogeneous longitudinal bias field. Rubidium Rydberg atoms are excited using the two-photon transition 5S1/2 -> 5P3/2 -> nL, where n and L are principal and angular-momentum quantum numbers. An ion-imaging insert allows for time-delayed and spatially resolved detection of the excited atoms and their motion within the trapping potential. The excitation geometry is suitable for coherent, highly efficient population of circular Rydberg levels using adiabatic transfer in crossed magnetic and time-dependent electric fields. Circular-state atoms have long radiative lifetimes and small electric polarizabilities, making them ideal for Rydberg-atom trapping experiments and for studies that require long coherence times.

  4. One-Dimensional Rydberg Atom Interaction with Half-Cycle Pulses

    SciTech Connect

    Veilande, Rita; Bersons, Imants

    2009-04-19

    Our study describes the interaction of Rydberg atoms with short half-cycle pulses, using impulse approximation and modeling of one-dimensional atoms. One-dimensional Rydberg atoms are in extremely elongated states of high principal quantum number. Half-cycle pulses are unipolar, high-power electromagnetic pulses. In our research, their duration is much shorter than the classical electron orbit period. A single electric field pulse simply delivers an impulsive momentum transfer or ''kick'' to the excited electron. Atomic transition matrix elements are found and discussed in the frame of quantum and semiclassical theories, and various approximations are used. The dynamic of THz Rydberg wave packets is investigated. Transition probabilities, calculated from derived simple analytical expressions in the case of two time-delayed weak pulses, agree well with the experimental data and calculations of other authors. Analytical expressions for the revival and fractional revival phenomena of the autocorrelation function for Gaussian and Lorentzian distribution, as well as the ionization probabilities of Rydberg atom interaction with two half-cycle pulses, are analyzed.

  5. Experiments on the self-organized critical state of helium-4

    NASA Astrophysics Data System (ADS)

    Chatto, Andrew Rosenberg

    When a heat flux is applied downwards through a sample of 4He near the superfluid transition temperature Tlambda the gradient in the temperature self-organizes to the gradient in Tlambda caused by gravity. This creates the Self-Organized Critical (SOC) state. Previous experiments have observed the state, measured the temperature TSOC vs. heat flux, and investigated a remarkable wave that only travels upwards against the flow of the heat flux [1, 2, 3]. We report the first results of the heat capacity of the SOC state, C∇T, for heat fluxes 60nW/cm2 < Q < 13 muW/cm2 and corresponding temperatures 9nK > TSOC, - T lambda > -1.1muK. We find that C ∇T static (i.e., zero beat flux) unrounded (i.e., in zero gravity) heat capacity C0 with two exceptions. The first is that within 250 nK of T lambda, C∇T is depressed relative to C0 and the maximum in C∇T is shifted to 50 nK below Tlambda. The second difference is that at high heat flux, CC∇T is again depressed relative to C0 with the departure starting at about 650 nK below 7lambda. We present the most extensive measurements of the speed and attenuation of the SOC wave to date. We report wave speed measurements taken over our full experimental range 30 nW/cm2 < Q < 13 muM/cm 2 and attenuation results over the limited range that produced enough attenuation to measure. We also report the first accurate calculation of the speed of the SOC wave.

  6. Overview of helium-like structure measurements: A focus on the N = 2 triplet states

    SciTech Connect

    Berry, H.G.; Dunford, R.W.

    1992-01-01

    We present a comprehensive analysis of existing measurements of the 1s2s [sup 3]S[sub 1] [minus] 1s2p[sup 3]P[sub 0,1,2] transition energies in heliumlike ions for nuclear charges Z=2 to Z=92. We find agreement with the standard unified calculations of [vert bar]Drake except for the transitions from the 1s2p [sup 3]P[sub o] state. We find a deviation equal to 2.3x(Z/10)[sup 4] cm[sup [minus]1] for the most precise existing measurements.

  7. Helium cluster isolation spectroscopy

    NASA Astrophysics Data System (ADS)

    Higgins, John Paul

    Clusters of helium, each containing ~103- 104 atoms, are produced in a molecular beam and are doped with alkali metal atoms (Li, Na, and K) and large organic molecules. Electronic spectroscopy in the visible and UV regions of the spectrum is carried out on the dopant species. Since large helium clusters are liquid and attain an equilibrium internal temperature of 0.4 K, they interact weakly with atoms or molecules absorbed on their surface or resident inside the cluster. The spectra that are obtained are characterized by small frequency shifts from the positions of the gas phase transitions, narrow lines, and cold vibrational temperatures. Alkali atoms aggregate on the helium cluster surface to form dimers and trimers. The spectra of singlet alkali dimers exhibit the presence of elementary excitations in the superfluid helium cluster matrix. It is found that preparation of the alkali molecules on the surface of helium clusters leads to the preferential formation of high-spin, van der Waals bound, triplet dimers and quartet trimers. Four bound-bound and two bound-free transitions are observed in the triplet manifold of the alkali dimers. The quartet trimers serve as an ideal system for the study of a simple unimolecular reaction in the cold helium cluster environment. Analysis of the lowest quartet state provides valuable insight into three-body forces in a van der Waals trimer. The wide range of atomic and molecular systems studied in this thesis constitutes a preliminary step in the development of helium cluster isolation spectroscopy, a hybrid technique combining the advantages of high resolution spectroscopy with the synthetic, low temperature environment of matrices.

  8. 30 CFR 556.11 - Helium.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false Helium. 556.11 Section 556.11 Mineral Resources... § 556.11 Helium. (a) Each lease issued or continued under these regulations shall be subject to a... helium from all gas produced from the leased area. (b) In case the United States elects to take...

  9. 30 CFR 556.11 - Helium.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false Helium. 556.11 Section 556.11 Mineral Resources... § 556.11 Helium. (a) Each lease issued or continued under these regulations shall be subject to a... helium from all gas produced from the leased area. (b) In case the United States elects to take...

  10. 30 CFR 556.11 - Helium.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false Helium. 556.11 Section 556.11 Mineral Resources... § 556.11 Helium. (a) Each lease issued or continued under these regulations shall be subject to a... helium from all gas produced from the leased area. (b) In case the United States elects to take...

  11. Theory of Highly Excited Molecular States : Some Recent Developments

    NASA Astrophysics Data System (ADS)

    Jungen, Christian

    2000-06-01

    Throughout his career Gerhard Herzberg had an interest in Rydberg states. This began with his observation of the Balmer series of hydrogen during his thesis work and led to the discovery of `Rydberg molecules' late in his career (i.e. molecules, such as H_3, which are unstable in their ground state but possess stable Rydberg states). While initially GH focussed mainly on the structural properties of Rydberg states, he later also studied their internal dynamics (uncoupling phenomena) and radiationless decay (preionization and predissociation). All of these phenomena play a crucial role in modern-day experiments where ultra-high spectral resolution resolves the hyperfine structure in high Rydberg states, while time-resolved experiments lead to the observation of Rydberg wave packets. Both these aspects, hyperfine effects and wavepacket motion in Rydberg states, will be discussed from a theoretical point of view.

  12. Quantum-defect analysis of 3p and 3d H{sub 3} Rydberg energy levels

    SciTech Connect

    Wang Jia; Greene, Chris H.

    2010-08-15

    In this work, Rydberg energy levels of the triatomic hydrogen molecule (H{sub 3}) are studied with multichannel quantum-defect theory. We extract the body-frame p-wave quantum defects from highly accurate ab initio electronic potential surfaces and calculate the quantum defects of higher angular-momentum states in a long-range multipole potential model. Laboratory-frame quantum-defect matrices emerge from a rovibrational-frame transformation carried out with accurate rovibrational states of H{sub 3}{sup +}. Finally, we use the laboratory-frame quantum defects to calculate Rydberg energy levels for the fundamental neutral triatomic molecule H{sub 3}.

  13. Trapping Rydberg Atoms in an Optical Lattice

    SciTech Connect

    Anderson, S. E.; Younge, K. C.; Raithel, G.

    2011-12-23

    Rubidium Rydberg atoms are laser excited and subsequently trapped in a one-dimensional optical lattice (wavelength 1064 nm). Efficient trapping is achieved by a lattice inversion immediately after laser excitation using an electro-optic technique. The trapping efficiency is probed via analysis of the trap-induced shift of the two-photon microwave transition 50S{yields}51S. The inversion technique allows us to reach a trapping efficiency of 90%. The dependence of the efficiency on the timing of the lattice inversion and on the trap laser power is studied. The dwell time of 50D{sub 5/2} Rydberg atoms in the lattice is analyzed using lattice-induced photoionization.

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

    NASA Astrophysics Data System (ADS)

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

    1982-09-01

    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.

  15. Magnetically Stimulated Diffusion of Rydberg Gases

    NASA Astrophysics Data System (ADS)

    Dumin, Yurii V.

    2013-01-01

    The specific kind of diffusion stimulated (rather than suppressed) by the external magnetic field, which was predicted for the first time by Schmelcher and Cederbaum in 1992, is considered here for the case of high-angular-momentum (i.e., approximately “circular”) Rydberg atoms. The coefficient of such diffusion was calculated by a purely analytical approach and was found to be very relevant to the experiments on antihydrogen formation.

  16. Dipole-dipole resonance line shapes in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Richards, B. G.; Jones, R. R.

    2016-04-01

    We have explored the dipole-dipole mediated, resonant energy transfer reaction, 32 p3 /2+32 p3 /2→32 s +33 s , in an ensemble of cold 85Rb Rydberg atoms. Stark tuning is employed to measure the population transfer probability as a function of the total electronic energy difference between the initial and final atom-pair states over a range of Rydberg densities, 2 ×108≤ρ ≤3 ×109 cm-3. The observed line shapes provide information on the role of beyond nearest-neighbor interactions, the range of Rydberg atom separations, and the electric field inhomogeneity in the sample. The widths of the resonance line shapes increase approximately linearly with the Rydberg density and are only a factor of 2 larger than expected for two-body, nearest-neighbor interactions alone. These results are in agreement with the prediction [B. Sun and F. Robicheaux, Phys. Rev. A 78, 040701(R) (2008), 10.1103/PhysRevA.78.040701] that beyond nearest-neighbor exchange interactions should not influence the population transfer process to the degree once thought. At low densities, Gaussian rather than Lorentzian line shapes are observed due to electric field inhomogeneities, allowing us to set an upper limit for the field variation across the Rydberg sample. At higher densities, non-Lorentzian, cusplike line shapes characterized by sharp central peaks and broad wings reflect the random distribution of interatomic distances within the magneto-optical trap (MOT). These line shapes are well reproduced by an analytic expression derived from a nearest-neighbor interaction model and may serve as a useful fingerprint for characterizing the position correlation function for atoms within the MOT.

  17. Theoretical Estimates of the 1(1)S and 2(1)S Lamb Shifts in Helium (volumes i and Ii)

    NASA Astrophysics Data System (ADS)

    Baker, Jonathan Dickinson

    The energies of the 1^1S and 2^1S states of the helium atom have been computed through O(alpha^3 ) Rydberg with an accuracy of 10^ {-5}cm^{-1}. The principal focus of this work has been the contribution to the O(alpha^3) Lamb shift of the Bethe Logarithm, which is calculated by an approach first developed by Charles Schwartz and later refined by Robert N. Hill, in which the resolvent is numerically integrated over the full range of photon momentum. The Bethe logarithm is then combined with the other terms in the O(alpha^3) Rydberg Lamb shift correction which have been computed by Drake and with highly accurate non-relativistic and O(alpha ^3) relativistic results to yield theoretical estimates of the energies of the 1^1S and 2^1S states of the helium atom. The value of the Bethe logarithm is computed to be 3.676975(1) a.u. for the 1^1S state and 3.673182(8) a.u. for the 2^1S state. The resulting ionization potentials are 198310.66774(4) cm^ {-1} for the 1^1S state and 32033.228862(8) cm^{-1} for the 2^1S state. Our value for the 2^{1}S ionization potential eliminates the previous 600 sigma discrepancy between experiment and the best previous estimate based on a first order 1/Z-expansion for the Bethe logarithm. Our value fully agrees with the recent measurement at NIST of 32033.228855(7) cm ^{-1} within the reported error bar, but lies about 4sigma outside the value of 32033.228830(5) cm^{-1 } measured at Yale. Thus our work has essentially eliminated the error in the O(alpha^3 ) corrections, and motivates the future calculation of the O(alpha^{4}) corrections to decide between the two experiments.

  18. Vibronic and Rydberg series assignments in the vacuum ultraviolet absorption spectrum of nitrous oxide

    NASA Astrophysics Data System (ADS)

    Shastri, Aparna; Singh, Param Jeet; Krishnakumar, Sunanda; Mandal, Anuvab; Raja Sekhar, B. N.; D'Souza, R.; Jagatap, B. N.

    2014-11-01

    We report a comprehensive photoabsorption study of nitrous oxide (N2O) in the vacuum ultraviolet (45,000-95,000 cm-1) region using synchrotron radiation. The observed spectrum comprises of a few valence transitions and low lying Rydberg series converging to the two spin-orbit components (2П1/2,3/2) of the ground state of N2O+. Spectral analysis is aided by extensive quantum chemical calculations of vertical excited states, oscillator strengths and potential energy curves using the time dependent density functional theory. Vibronic bands observed in the first absorption system (45,000-60,000 cm-1) are assigned to hot band progressions in υ2‧ originating from v″=1 or 2. New insights into the assignment of the well-formed progression of bands in the X1Σ+→C1П system (60,000-72,000 cm-1) are afforded by consideration of the Renner-Teller interaction. A set of molecular vibrational parameters (ω2=467 cm-1, x22=-2.9, ε=-0.24) for the C1П state are derived from a fitting of the experimental data. The 3pπ1Σ+ state at ~77,600 cm-1 shows a large quantum defect (0.96) which is explained as arising due to mixed valence-Rydberg character. In the 85,000-95,000 cm-1 region, a number of absorption features are observed with greater clarity than in earlier photoabsorption studies and assigned to Rydberg series of type nlλ (n=3,4; l=s,p,d; λ=σ,π,δ) and accompanying vibronic bands. This work has resulted in clarification of several discrepancies in earlier Rydberg series assignments. Additionally, the 3pπ 3Σ- Rydberg state at 85,788 cm-1, the valence transition 7σ→3π (1П) at 87,433 cm-1 and the 3dλ Rydberg series in the 91,700-92,600 cm-1 region are assigned for the first time.

  19. Exotic topological density waves in cold atomic Rydberg-dressed fermions.

    PubMed

    Li, Xiaopeng; Sarma, S Das

    2015-01-01

    Versatile controllability of interactions in ultracold atomic and molecular gases has now reached an era where quantum correlations and unconventional many-body phases can be studied with no corresponding analogues 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. By varying the spatial range of the non-local interaction, we find various chiral density waves with spontaneous time-reversal symmetry breaking, whose quasiparticles form three-dimensional quantum Hall and Weyl semimetal states. Remarkably, certain density waves even exhibit mixed topologies beyond the existing topological classification. Our results suggest gapless fermionic states could exhibit far richer topology than previously expected. PMID:25972134

  20. Exotic topological density waves in cold atomic Rydberg-dressed fermions

    PubMed Central

    Li, Xiaopeng; Sarma, S Das

    2015-01-01

    Versatile controllability of interactions in ultracold atomic and molecular gases has now reached an era where quantum correlations and unconventional many-body phases can be studied with no corresponding analogues 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. By varying the spatial range of the non-local interaction, we find various chiral density waves with spontaneous time-reversal symmetry breaking, whose quasiparticles form three-dimensional quantum Hall and Weyl semimetal states. Remarkably, certain density waves even exhibit mixed topologies beyond the existing topological classification. Our results suggest gapless fermionic states could exhibit far richer topology than previously expected. PMID:25972134

  1. Ultrafast Quantum Random Access Memory Utilizing Single Rydberg Atoms in a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Patton, Kelly R.; Fischer, Uwe R.

    2013-12-01

    We propose a long-lived and rapidly accessible quantum memory unit, for which the operational Hilbert space is spanned by states involving the two macroscopically occupied hyperfine levels of a miscible binary atomic Bose-Einstein condensate and the Rydberg state of a single atom. It is shown that an arbitrary qubit state, initially prepared using a flux qubit, can be rapidly transferred to and from the trapped atomic ensemble in approximately 10 ns and with a large fidelity of 97%, via an effective two-photon process using an external laser for the transition to the Rydberg level. The achievable ultrafast transfer of quantum information therefore enables a large number of storage and retrieval cycles from the highly controllable quantum optics setup of a dilute ultracold gas, even within the typically very short flux qubit lifetimes of the order of microseconds.

  2. On the formation of (anionic) excited helium dimers in helium droplets.

    PubMed

    Huber, Stefan E; Mauracher, Andreas

    2014-08-21

    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

  3. Nonperturbative B -spline R -matrix-with-pseudostates calculations for electron-impact ionization-excitation of helium to the n =3 states of He+

    NASA Astrophysics Data System (ADS)

    Zatsarinny, Oleg; Bartschat, Klaus

    2016-01-01

    We present fully differential cross-section ratios for electron-impact ionization of helium without excitation and with simultaneous excitation of the residual ion. The results are obtained from a nonperturbative close-coupling formalism, with the resulting equations being solved by a B -spline R -matrix-with-pseudostates approach. Very encouraging agreement is obtained with directly measured cross-section ratios for ionization leaving the residual He+ ion in either the 1 s ground state or the n =3 (3 s +3 p +3 d ) excited states.

  4. Laser resonance photoionization spectroscopy of Rydberg levels in Fr

    SciTech Connect

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

    1987-09-21

    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.

  5. Correlated Exciton Transport in Rydberg-Dressed-Atom Spin Chains

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    We investigate the transport of excitations through a chain of atoms with nonlocal 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 nontrivial dissipation, correlations, and many-body effects in recent experiments on the dipole-mediated transport of Rydberg excitations.

  6. Nuclear spin transitions in the kHz range in Rydberg matter clusters give precise values of the internal magnetic field from orbiting Rydberg electrons

    NASA Astrophysics Data System (ADS)

    Holmlid, Leif

    2009-03-01

    Clusters of the electronically excited condensed matter Rydberg matter (RM) are planar and sixfold symmetric with specific magic numbers N as shown by rotational spectroscopy of potassium K N clusters [L. Holmlid, Mol. Phys. 105 (2007) 933; L. Holmlid, J. Mol. Struct. 885 (2008) 122]. In radio frequency emission spectra from such clusters, features are observed that are due to the hyperfine interaction between the atomic nucleus 39K and two Rydberg electrons. These electrons exist in a doubly excited K atom at n″ = 5 or 6 in a "sleeping-top" type rotating cluster. Such low excited electrons were observed recently in optical intra-cavity experiments in K(RM), where the electrons in the conduction band are involved in the angular momentum conservation in the stimulated emission. Here we show that the agreement with the theoretical description of circular Rydberg states is excellent within ±0.2% in the magnetic field, invoking angular momentum conservation by electrons in the condensed phase. Sleeping-top clusters may form stacks of clusters, and it is likely that such stacks are the emitting entities involved in the two nuclear spin series observed.

  7. 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

    Mason, Rod S

    2010-04-21

    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

  8. Towards a controlled-phase gate using Rydberg-dressed atoms

    NASA Astrophysics Data System (ADS)

    Hankin, Aaron; Jau, Yuan-Yu; Biedermann, Grant

    2014-05-01

    We are implementing a controlled-phase gate based on singly trapped neutral atoms whose coupling is mediated by the dipole-dipole interaction of Rydberg states. An off-resonant laser field dresses ground state cesium atoms in a manner conditional on the Rydberg blockade mechanism, providing the required entangling interaction. We will present our progress toward implementing the controlled-phase gate with an analysis of possible sources of decoherence such as RF radiation from wireless communication devices. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  9. Negative ion formation by Rydberg electron transfer: Isotope-dependent rate constants

    SciTech Connect

    Carman, H.S. Jr.; Klots, C.E.; Compton, R.N.

    1991-01-01

    The formation of negative ions during collisions of rubidium atoms in selected ns and nd Rydberg states with carbon disulfide molecules has been studied for a range of effective principal quantum numbers (10 {le} n* {le} 25). For a narrow range of n* near n* = 17, rate constants for CS{sub 2}{sup {minus}} formation are found to depend upon the isotopic composition of the molecule, producing a negative ion isotope ratio (mass 78 to mass 76, amu) up to 10.5 times larger than the natural abundance ratio of CS{sub 2} isotopes in the reagent. The isotope ratio is found to depend strongly upon the initial quantum state of the Rydberg atom and perhaps upon the collision energy and CS{sub 2} temperature. 32 refs., 5 figs., 1 tab.

  10. Rydberg-wave-packet evolution in a frozen gas of dipole-dipole-coupled atoms

    NASA Astrophysics Data System (ADS)

    Zhou, Tao; Li, Sha; Jones, R. R.

    2014-06-01

    We have studied the evolution of Rydberg wave packets in the presence of interatomic dipole-dipole interactions in a frozen Rb gas. Rb atoms in a magneto-optical trap (MOT) are first laser excited to ns Rydberg eigenstates. A picosecond THz pulse further excites them into coherent superposition states involving the initial-level and neighboring np states. A second, identical, time-delayed THz pulse probes the wave-packet dynamics. As the wave packets evolve they are influenced by dipole-dipole interactions, predominantly pairwise excitation-exchange processes of the form |s >|p>↔|p>|s>. The coherent electronic evolution of the ensemble dephases due to the variation in dipole-dipole coupling strength between atom pairs in the MOT. The experimental results are in good agreement with numerical calculations that simulate the interactions between nearest neighbors in a frozen gas.

  11. Atomic jet with ionization detection for laser spectroscopy of Rydberg atoms under collisions and fields

    NASA Astrophysics Data System (ADS)

    Philip, G.

    2008-03-01

    An efficient atomic jet setup offering many unprecedented advantages over a conventional heat pipe setup used in multi-photon spectroscopy, mainly of alkaline-earth metals, has been constructed by a scheme in which the sample material is encapsulated in a disposable cartridge oven located inside a thermally stabilised heat-pipe and is made to effuse in to a row of atomic beams merging to form a jet target. This novel scheme combines the advantages of both high density atomic beam with convenient geometry for orthogonal excitation and high sensitive ionisation detection capabilities of thermionic diodes, besides eliminating several problems inherent in the usual heat-pipe operation. Out of various designs, typical results are presented for a linear heat-pipe with vertical atomic jet used in two-photon spectroscopy of highly excited states of Sr I. Controlled excitations of both Rydberg and non-Rydberg states, which cannot otherwise be accessed from the ground state due to parity and spectroscopic selection rules, have been achieved by employing a weak electric field complimented by collisions. The atomic jet setup is also found very useful for the study of collisional broadening and shift of excited states and time evolution of Rydberg atoms.

  12. Ionization of Rydberg atoms embedded in an ultracold plasma

    NASA Astrophysics Data System (ADS)

    Vanhaecke, Nicolas; Comparat, Daniel; Tate, Duncan A.; Pillet, Pierre

    2005-01-01

    We have studied the behavior of cold Rydberg atoms embedded in an ultracold plasma. We demonstrate that even deeply bound Rydberg atoms are completely ionized in such an environment, due to electron collisions. Using a fast pulse extraction of the electrons from the plasma we found that the number of excess positive charges, which is directly related to the electron temperature Te , is not strongly affected by the ionization of the Rydberg atoms. Assuming a Michie-King equilibrium distribution, in analogy with globular star cluster dynamics, we estimate Te . Without concluding on heating or cooling of the plasma by the Rydberg atoms, we discuss the range for changing the plasma temperature by adding Rydberg atoms.

  13. Radioactive transitions in the helium isoelectronic sequence

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1971-01-01

    The principles of the atomic spectrum theory are used to quantitatively analyze radiation transitions in two-electron helium-like atomic systems. Quantum theoretical methods, describing absorption and emission of a single photon in a radiative transition between two stationary states of an atomic system, reproduced the energy level diagram for the low lying states of helium. Reliable values are obtained from accurate variationally determined two-electron nonrelativistic wave functions for radiative transition probabilities of 2 3p states in the helium isoelectric sequence, and for the 2 1s and 2 3s1 states of the helium sequence.

  14. Nonspreading Wave Packets for Rydberg Electrons in Rotating Molecules with Electric Dipole Moments

    SciTech Connect

    Bialynicki-Birula, I.

    1996-11-01

    Nonspreading wave packets for Rydberg electrons are predicted in rotating molecules with electric dipole moments. We have named them the Trojan wave packets since their stability is due to the same mechanism that governs the motion of the Trojan asteroids in the Sun-Jupiter system. Unlike all previously predicted Trojan wave packets in atoms, molecular Trojan states do not require external fields for their existence.

  15. Ionization of Rydberg atoms by circularly and elliptically polarized microwave fields

    SciTech Connect

    Griffiths, J.A. ); Farrelly, D. Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84332-0300 )

    1992-03-01

    A classical study of the dynamics of atomic Rydberg states interacting with both elliptically and circularly polarized microwave fields is presented. In recent experiments, enhanced ionization rates were observed in elliptically as opposed to circularly polarized fields. A classical phase-space simulation provides good qualitative agreement with experimental findings. These results are explained in terms of the breakdown of almost conserved quantities as the polarization of the field is changed from circular to elliptical.

  16. Measurement of Atomic Oscillator Strength Distribution from the Excited States

    SciTech Connect

    Hussain, Shahid; Saleem, M.; Baig, M. A.

    2008-10-22

    Saturation technique has been employed to measure the oscillator strength distribution in spectra of helium lithium using an electrical discharge cell a thermionic diode ion detector respectively. The photoabsorption cross sections in the discrete or bound region (commonly known as f-values) have been determined form the Rydberg series accessed from a particular excited state calibrating it with the absolute value of the photoionization cross section measured at the ionization threshold. The extracted discrete f-values merge into the oscillator strength densities, estimated from the measured photoionization cross sections at different photon energies above the first ionization threshold. The experimental data on helium and lithium show continuity between the discrete and the continuous oscillator strengths across the ionization threshold.

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

    PubMed

    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

    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 (λ = 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

  18. Pulsed Rydberg four-wave mixing with motion-induced dephasing in a thermal vapor

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Hsin; Ripka, Fabian; Löw, Robert; Pfau, Tilman

    2016-01-01

    We report on time-resolved pulsed four-wave mixing (FWM) signals in a thermal Rubidium vapor involving a Rydberg state. We observe FWM signals with dephasing times up to 7 ns, strongly dependent on the excitation bandwidth to the Rydberg state. The excitation to the Rydberg state is driven by a pulsed two-photon transition on ns timescales. Combined with a cw de-excitation laser, a strongly directional and collective emission is generated according to a combination of the phase matching effect and averaging over Doppler classes. In contrast to a previous report (Huber et al. in Phys Rev A 90: 053806, 2014) using off-resonant FWM, at a resonant FWM scheme we observe additional revivals of the signal shortly after the incident pulse has ended. We infer that this is a revival of motion-induced constructive interference between the coherent emissions of the thermal atoms. The resonant FWM scheme reveals a richer temporal structure of the signals, compared to similar, but off-resonant excitation schemes. A simple explanation lies in the selectivity of Doppler classes. Our numerical simulations based on a four-level model including a whole Doppler ensemble can qualitatively describe the data.

  19. Thermal Casimir-Polder shifts in Rydberg atoms near metallic surfaces

    SciTech Connect

    Crosse, J. A.; Clements, Kate; Buhmann, Stefan Y.; Scheel, Stefan; Ellingsen, Simen A.

    2010-07-15

    The Casimir-Polder (CP) potential and transition rates of a Rydberg atom above a plane metal surface at finite temperature are discussed. As an example, the CP potential and transition rates of a rubidium atom above a copper surface at 300 K are computed. Close to the surface we show that the quadrupole correction to the force is significant and increases with increasing principal quantum number n. For both the CP potential and decay rates one finds that the dominant contribution comes from the longest wavelength transition and the potential is independent of temperature. We provide explicit scaling laws for potential and decay rates as functions of atom-surface distance and principal quantum number of the initial Rydberg state.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  1. The importance of Rydberg orbitals in dissociative ionization of small hydrocarbon molecules in intense few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Wells, E.; Voznyuk, A.; Mahowald, J. B.; Schmitz, D. G.; Burwitz, T. G.; Jochim, B.; Zohrabi, M.; Betsch, K. J.; Severt, T.; Berry, B.; Kling, N. G.; Ablikim, U.; Carnes, K. D.; Ben-Itzhak, I.; Siemering, R.; Kling, M. F.; de Vivie-Riedle, R.

    2015-05-01

    Much of our intuition about strong-field processes is built upon studies of diatomic molecules, which have relatively well separated electronic states. In polyatomic molecules, however, the electronic states are closer together, leading to more complex interactions. A combined experimental and theoretical investigation of strong-field ionization followed by hydrogen elimination in the hydrocarbon series C2D2, C2D4, and C2D6 reveals that the photofragment angular distributions can only be understood when ionization from Rydberg orbitals is considered. These commonly neglected Rydberg orbitals are readily populated for some orientations of the molecule relative to the laser polarization, leading to dissociation patterns and an intensity dependence consistent with significant Rydberg orbital influence. Our results suggest that Rydberg states should be routinely considered when studying polyatomic molecules in intense laser fields. Funding provided by National Science Foundation grant 1404185, the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, and the DFG.

  2. Mesoscopic Rydberg-blockaded ensembles in the superatom regime and beyond

    NASA Astrophysics Data System (ADS)

    Weber, T. M.; Höning, M.; Niederprüm, T.; Manthey, T.; Thomas, O.; Guarrera, V.; Fleischhauer, M.; Barontini, G.; Ott, H.

    2015-02-01

    The control of strongly interacting many-body systems enables the creation of tailored quantum matter with complex properties. Atomic ensembles that are optically driven to a Rydberg state provide many examples for this: atom-atom entanglement, many-body Rabi oscillations, strong photon-photon interaction and spatial pair correlations. In its most basic form Rydberg quantum matter consists of an isolated ensemble of strongly interacting atoms spatially confined to the blockade volume--a superatom. Here we demonstrate the controlled creation and characterization of an isolated mesoscopic superatom by means of accurate density engineering and excitation to Rydberg p-states. Its variable size allows the investigation of the transition from effective two-level physics to many-body phenomena. By monitoring continuous laser-induced ionization we observe a strongly anti-bunched ion emission under blockade conditions and extremely bunched ion emission under off-resonant excitation. Our measurements provide insights into both excitation statistics and dynamics. We anticipate applications in quantum optics and quantum information as well as many-body physics experiments.

  3. Xe{sub 2} gerade Rydberg states observed in the afterglow of a microplasma by laser spectroscopy of a{sup 3}Σ{sub u}{sup +}(1{sub u},O{sub u}{sup −}) absorption in the green (545–555 nm) and near-infrared (675–800 nm)

    SciTech Connect

    Wagner, C. J.; Galvin, T. C.; Eden, J. G.

    2014-06-28

    Bound←bound transitions of the Xe dimer at small internuclear separation (R < 4.0 Å) have been observed in the 545–555 nm and 675–800 nm spectral regions by laser spectroscopy in the afterglow of a pulsed Xe microplasma with a volume of ∼160 nl. Transient suppression of Xe{sub 2} A{sup 1}Σ{sub u}{sup +}(O{sub u}{sup +})→X{sup 1}Σ{sub g}{sup +}(O{sub g}{sup +}) emission in the vacuum ultraviolet (∼172 nm), induced by laser excitation of Ω{sub g}←a{sup 3}Σ{sub u}{sup +}(1{sub u},O{sub u}{sup −}) [Rydberg←Rydberg] transitions of the molecule, has confirmed the existence of structure between 720 and 770 nm (reported by Killeen and Eden [J. Chem. Phys. 84, 6048 (1986)]) but also reveals red-degraded vibrational bands extending to wavelengths beyond 800 nm. Spectral simulations based on calculations of Franck-Condon factors for assumed Ω{sub g}←a{sup 3}Σ{sub u}{sup +} transitions involving Ω = 0{sup ±},1 gerade Rydberg states suggest that the upper level primarily responsible for the observed spectrum is an Ω = 1 state correlated, in the separated atom limit, with Xe(5p{sup 6} {sup 1}S{sub 0}) + Xe(5p{sup 5} 6p) and built on a predominantly A{sup 2}Π{sub 3/2g} molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1{sub g}←1{sub u},O{sub u}{sup ±} absorptive transitions are determined to be T{sub e} = 13 000 ± 150 cm{sup −1}, ω{sub e}{sup ′}=120±10 cm{sup −1}, ω{sub e}{sup ′}x{sub e}{sup ′}=1.1±0.4 cm{sup −1}, D{sub e} = 3300 ± 300 cm{sup −1}, and ΔR{sub e}=R{sub e}{sup ′}−R{sub e}{sup ″}=0.3±0.1 Å which are in general agreement with the theoretical predictions of the pseudopotential hole-particle formalism, developed by Jonin and Spiegelmann [J. Chem. Phys. 117, 3059 (2002)], for both the (5)1{sub g} and (3)O{sub g}{sup +} states of Xe{sub 2}. These spectra exhibit the most extensive vibrational development, and provide evidence for the first molecular core-switching transition, observed to date for any of the rare gas dimers at small R (<4 Ǻ). Experiments in the green (545–555 nm) also provide improved absorption spectra, relative to data reported in 1986 and 1999, associated with Xe{sub 2} Rydberg states derived from the Xe(7p) orbital.

  4. Precision Spectroscopy in Cold Molecules: the First Rotational Intervals of He_2^+ by High-Resolution Spectroscopy and Rydberg-Series Extrapolation

    NASA Astrophysics Data System (ADS)

    Jansen, Paul; Semeria, Luca; Scheidegger, Simon; Merkt, Frederic

    2015-06-01

    Having only three electrons, He_2^+ represents a system for which highly accurate ab initio calculations are possible. The latest calculation of rovibrational energies in He_2^+ do not include relativistic or QED corrections but claim an accuracy of about 120 MHz The available experimental data on He_2^+, though accurate to 300 MHz, are not precise enough to rigorously test these calculations or reveal the magnitude of the relativistic and QED corrections. We have performed high-resolution Rydberg spectroscopy of metastable He_2 molecules and employed multichannel-quantum-defect-theory extrapolation techniques to determine the rotational energy-level structure in the He_2^+ ion. To this end we have produced samples of helium molecules in the a ^3σ_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 metastable He_2 molecules are excited to np Rydberg states using the frequency doubled output of a pulse-amplified ring dye laser. Although the bandwidth of the laser systems is too large to observe the reduction of the Doppler width resulting from deceleration, the deceleration greatly simplifies the spectral assignments because of its spin-rotational state selectivity. Our approach enabled us to determine the rotational structure of He_2^+ with unprecedented accuracy, to determine the size of the relativistic and QED corrections by comparison with the results of Ref.~a and to precisely measure the rotational structure of the metastable state for comparison with the results of Focsa~et al. 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, Phys. Rev. A 89, 043420 (2014). C. Focsa, P. F. Bernath, and R. Colin, J. Mol. Spectrosc. 191, 209 (1998).

  5. Interaction-induced stabilization of circular Rydberg atoms

    SciTech Connect

    Hezel, Bernd; Mayle, Michael; Schmelcher, Peter

    2011-12-15

    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.

  6. Interaction-induced stabilization of circular Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Hezel, Bernd; Mayle, Michael; Schmelcher, Peter

    2011-12-01

    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.

  7. Comparative studies of ion-pair formation and resonant quenching processes in collisions of Rydberg atoms with the alkaline-earth atoms

    NASA Astrophysics Data System (ADS)

    Narits, A. A.; Mironchuk, E. S.; Lebedev, V. S.

    2014-01-01

    We report the results of comparative studies of ion-pair formation and quenching processes in collisions of Rydberg Li(nl) and Cs(nl) atoms with Ca(4s2), Sr(5s2) and Ba(6s2) atoms possessing small electron affinities. Our consideration includes both the cases of selectively excited Rydberg nl-states with small orbital angular momentum (l ≪ n) and nearly circular states with l ˜ n - 1. Calculations of the electron-transfer processes are based on the semiclassical theory of nonadiabatic transitions and exact expression for the Rydberg-covalent-ionic coupling terms. Calculations of nonresonant quenching processes are carried out within the framework of the available theory of inelastic and quasielastic transitions between Rydberg-covalent states. The ion-pair formation and resonant quenching cross sections are shown to be significantly dependent not only on the principal quantum number n but also on the orbital angular momentum l and the binding energy of the alkaline-earth anion. For each system under study we find the regions of n in which either the resonant quenching or the ion-pair formation processes are predominant. The relative role of the resonant and nonresonant mechanisms of depopulation of Rydberg states is investigated.

  8. Photoionization study of doubly-excited helium at ultra-high resolution

    SciTech Connect

    Kaindl, G.; Schulz, K.; Domke, M.

    1997-04-01

    Ever since the pioneering work of Madden & Codling and Cooper, Fano & Prats on doubly-excited helium in the early sixties, this system may be considered as prototypical for the study of electron-electron correlations. More detailed insight into these states could be reached only much later, when improved theoretical calculations of the optically-excited {sup 1}P{sup 0} double-excitation states became available and sufficiently high energy resolution ({delta}E=4.0 meV) was achieved. This allowed a systematic investigation of the double-excitation resonances of He up to excitation energies close to the double-ionization threshold, I{sub infinity}=79.003 eV, which stimulated renewed theoretical interest into these correlated electron states. The authors report here on striking progress in energy resolution in this grazing-incidence photon-energy range of grating monochromators and its application to hitherto unobservable states of doubly-excited He. By monitoring an extremely narrow double-excitation resonance of He, with a theoretical lifetime width of less than or equal to 5 {mu}eV, a resolution of {delta}E=1.0 meV (FWHM) at 64.1 eV could be achieved. This ultra-high spectral resolution, combined with high photon flux, allowed the investigation of new Rydberg resonances below the N=3 ionization threshold, I{sub 3}, as well as a detailed comparison with ab-initio calculations.

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

    SciTech Connect

    Militzer, B.; Hubbard, W. B.

    2013-09-10

    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''.

  10. Ab Initio Equation of State for Hydrogen-Helium Mixtures with Recalibration of the Giant-planet Mass-Radius Relation

    NASA Astrophysics Data System (ADS)

    Militzer, B.; Hubbard, W. B.

    2013-09-01

    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, ~0.2-9 g cm-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 ~0.2 Jupiter radii at fixed entropy and for masses greater than ~0.5 Jupiter mass. This change is large enough to have possible implications for some discrepant "inflated giant exoplanets."

  11. Field shifts and lowest order QED corrections for the ground 1 {sup 1}S and 2 {sup 3}S states of the helium atoms

    SciTech Connect

    Frolov, Alexei M.

    2007-03-14

    The bound state properties of the ground 1 {sup 1}S(L=0) state and the lowest triplet 2 {sup 3}S(L=0) state of the {sup 3}He, {sup 4}He, and {sup {infinity}}He helium atoms are determined to very high accuracy from the results of direct numerical computations. To compute the bound state properties of these atoms the author applied his exponential variational expansion in relative/perimetric three-body coordinates. For the ground 1 {sup 1}S(L=0) state and the lowest triplet 2 {sup 3}S(L=0) state of the {sup 3}He, {sup 4}He, and {sup {infinity}}He atoms the author also determined the lowest order QED corrections and the field component of isotopic shift (=field shift). For the 2 {sup 3}S(L=0) state of the {sup 3}He atom the hyperfine structure splitting is evaluated. The considered properties of the ground 1 {sup 1}S state and the lowest 2 {sup 3}S state in the {sup 3}He and {sup 4}He atoms are of great interest in a number of applications.

  12. Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Nakamura, Shinji; Fukui, Shigeo; Suematsu, Hiroto; Fujiwara, Toshimichi

    2015-10-01

    Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR = 4-12 kHz) at cryogenic temperatures (T = 35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T = 40 K and B0 = 16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.

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

    SciTech Connect

    Potapov, A. V. Panfilov, V. A.; Surin, L. A.; Dumesh, B. S.

    2010-11-15

    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.

  14. Borromean three-body FRET in frozen Rydberg gases

    PubMed Central

    Faoro, R.; Pelle, B.; Zuliani, A.; Cheinet, P.; Arimondo, E.; Pillet, P.

    2015-01-01

    Controlling the interactions between ultracold atoms is crucial for quantum simulation and computation purposes. Highly excited Rydberg atoms are considered in this prospect for their strong and controllable interactions known in the dipole-dipole case to induce non-radiative energy transfers between atom pairs, similarly to fluorescence resonance energy transfer (FRET) in biological systems. Here we predict few-body FRET processes in Rydberg atoms and observe the first three-body resonance energy transfer in cold Rydberg atoms using cold caesium atoms. In these resonances, additional relay atoms carry away an energy excess preventing the two-body resonance, leading thus to a Borromean type of energy transfer. These few-body processes present strong similarities with multistep FRET between chromophores sometimes called donor-bridge-acceptor or superexchange. Most importantly, they generalize to any Rydberg atom and could lead to new implementations of few-body quantum gates or entanglement. PMID:26348821

  15. van der Waals explosion of cold Rydberg clusters

    NASA Astrophysics Data System (ADS)

    Faoro, R.; Simonelli, C.; Archimi, M.; Masella, G.; Valado, M. M.; Arimondo, E.; Mannella, R.; Ciampini, D.; Morsch, O.

    2016-03-01

    We report on the direct measurement in real space of the effect of the van der Waals forces between individual Rydberg atoms on their external degrees of freedom. Clusters of Rydberg atoms with interparticle distances of around 5 μ m are created by first generating a small number of seed excitations in a magneto-optical trap, followed by off-resonant excitation that leads to a chain of facilitated excitation events. After a variable expansion time the Rydberg atoms are field ionized, and from the arrival time distributions the size of the Rydberg cluster after expansion is calculated. Our experimental results agree well with a numerical simulation of the van der Waals explosion.

  16. Spatially Resolved Observation of Dipole-Dipole Interaction between Rydberg Atoms

    SciTech Connect

    Ditzhuijzen, C. S. E. van; Noordam, L. D.; Heuvell, H. B. van Linden van den; Koenderink, A. F.; Hernandez, J. V.; Robicheaux, F.

    2008-06-20

    We have observed resonant energy transfer between cold Rydberg atoms in spatially separated cylinders. Resonant dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. We have measured the production of the 49p state as a function of separation of the cylinders (0-80 {mu}m) and the interaction time (0-25 {mu}s). In addition, we measured the width of the electric field resonances. A full many-body quantum calculation reproduces the main features of the experiments.

  17. On the adiabatic preparation of spatially-ordered Rydberg excitations of atoms in a one-dimensional optical lattice by laser frequency sweeps

    NASA Astrophysics Data System (ADS)

    Petrosyan, David; Mølmer, Klaus; Fleischhauer, Michael

    2016-04-01

    We examine the adiabatic preparation of crystalline phases of Rydberg excitations in a one-dimensional lattice gas by frequency sweep of the excitation laser, as proposed by Pohl et al (2010 Phys. Rev. Lett. 104 043002) and recently realized experimentally by Schauß et al (2015 Science 347 1455). We find that the preparation of crystals of a few Rydberg excitations in a unitary system of several tens of atoms requires exceedingly long times for the adiabatic following of the ground state of the system Hamiltonian. Using quantum stochastic (Monte Carlo) wavefunction simulations, we show that realistic decay and dephasing processes affecting the atoms during the preparation lead to a final state of the system that has only a small overlap with the target crystalline state. Yet, the final number and highly sub-Poissonian statistics of Rydberg excitations and their spatial order are little affected by the relaxations.

  18. Oscillator Strengths and Predissociation Rates for Rydberg Transitions in 12C16O, 13C16O, and 13C18O Involving the E 1Π, B 1Σ+, and W 1Π States

    NASA Astrophysics Data System (ADS)

    Eidelsberg, M.; Sheffer, Y.; Federman, S. R.; Lemaire, J. L.; Fillion, J. H.; Rostas, F.; Ruiz, J.

    2006-08-01

    One of the processes controlling the interstellar CO abundance and the ratio of its isotopologues is photodissociation. Accurate oscillator strengths and predissociation rates for Rydberg transitions are needed for modeling this process. We present results on absorption from the E 1Π-X 1Σ+ (1-0) and B 1Σ+-X 1Σ+ (6-0) bands at 1051 and 1002 Å, respectively, and the vibrational progression W 1Π-X 1Σ+ (v'-0) bands with v'=0-3 at 972, 956, 941, and 925 Å, respectively. The corresponding spectra were acquired at the high resolution (R~30,000) SU5 beam line at the Super ACO Synchrotron in Orsay, France. Spectra were obtained for the 12C16O, 13C 16O, and 13C18O isotopologues. These represent the most complete set of measurements available. Comparison is made with earlier results, both empirical and theoretical. While earlier determinations of oscillator strengths based on absorption from synchrotron radiation tend to be somewhat smaller than ours, the suite of measurements from a variety of techniques agree for the most part, considering the mutual uncertainties. For the bands studied here, their relative weakness, or their significant line widths arising from predissociation, minimizes potential problems from large optical depths at line center in absorption measurements. Predissociating line widths could generally be extracted from the spectra thanks to the profile simulations used in the analysis. In many cases, these simulations allowed us to consider e and f parity levels separately and to determine the dependence of the width on rotational quantum number, J. Our results are consistent with earlier determinations, especially the widths inferred from laser experiments.

  19. Observation of mixed singlet-triplet Rb2 Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Böttcher, F.; Gaj, A.; Westphal, K. M.; Schlagmüller, M.; Kleinbach, K. S.; Löw, R.; Liebisch, T. Cubel; Pfau, T.; Hofferberth, S.

    2016-03-01

    We present high-resolution spectroscopy of Rb2 ultralong-range Rydberg molecules bound by mixed singlet-triplet electron-neutral atom scattering. The mixing of the scattering channels is a consequence of the hyperfine interaction in the ground-state atom, as predicted recently by Anderson et al. [Phys. Rev. A 90, 062518 (2014), 10.1103/PhysRevA.90.062518]. Our experimental data enable the determination of the effective zero-energy singlet s -wave scattering length for Rb. We show that an external magnetic field can tune the contributions of the singlet and the triplet scattering channels and therefore the binding energies of the observed molecules. This mixing of molecular states via the magnetic field results in observed shifts of the molecular line which differ from the Zeeman shift of the asymptotic atomic states. Finally, we calculate molecular potentials using a full diagonalization approach including the p -wave contribution and all orders in the relative momentum k , and compare the obtained molecular binding energies to the experimental data.

  20. Dissociative recombination of antiprotonic helium ions: e+ pmacr He2+→ pmacr +He+

    NASA Astrophysics Data System (ADS)

    Sakimoto, Kazuhiro

    2009-04-01

    Rearrangement reaction in electron scattering from antiprotonic helium ions ( pmacr He2+) in highly excited states, i.e., e+ pmacr He2+→ pmacr +He+ , is theoretically investigated by using the R -matrix method. This type of reaction can be identified as dissociative recombination (DR) which is well known in molecular physics. If the concept of the adiabatic Born-Oppenheimer separation is applied, the present exotic reaction has a similarity to the DR of HeH+ molecules in the sense that the system has no crossings of the adiabatic potential curves. The present exotic DR reaction shows a variety of resonances, which can be described as a Rydberg electron attached to a pmacr He2+ ion excited to an energetically forbidden state. The cross sections and rate coefficients for the present DR are calculated. As the bound motion of pmacr -He2+ is closer to a circular orbit, the DR reaction, which leads to the destruction of pmacr He2+ , occurs less frequently. For the antiprotonic ion pmacr He2+ , it turns out that the circular states are the most stable against electron impacts.

  1. Steady state boiling crisis in a helium vertically heated natural circulation loop - Part 2: Friction pressure drop lessening

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

    2016-01-01

    Experiments were conducted on a 2-m high two-phase helium natural circulation loop operating at 4.2 K and 1 atm. Two heated sections with different internal diameter (10 and 6 mm) were tested. The power applied on the heated section wall was controlled in increasing and decreasing sequences, and temperature along the section, mass flow rate and pressure drop evolutions were registered. The post-CHF regime was studied watching simultaneously the evolution of boiling crisis onset along the test section and the evolution of pressure drop and mass flow rate. A significant lessening of friction was observed simultaneous to the development of the post-CHF regime, accompanied by a mass flow rate increase, which lets suppose that the vapor film in the film boiling regime acts as a lubricant. A model was created based on this idea and on heat transfer considerations. The predictions by this model are satisfactory for the low quality post-CHF regime.

  2. One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

    SciTech Connect

    Pifrader, Alexandra; Allard, Olivier; Auboeck, Gerald; Callegari, Carlo; Ernst, Wolfgang E.; Huber, Robert; Ancilotto, Francesco

    2010-10-28

    Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies ({approx_equal}3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n+1)p(leftarrow)ns transition of K, Rb, and Cs (n=4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d(leftarrow)5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked.

  3. Dynamics of heavy-Rydberg ion-pair formation in K(14p,20p)-SF6, CCl4 collisions.

    PubMed

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

    2014-06-21

    The dynamics of formation of heavy-Rydberg ion-pair states through electron transfer in K(np)-SF6, CCl4 collisions is examined by measuring the velocity, angular, and binding energy distributions of the product ion pairs. The results are analyzed with the aid of a Monte Carlo collision code that models both the initial electron capture and the subsequent evolution of the ion pairs. The model simulations are in good agreement with the experimental data and highlight the factors such as Rydberg atom size, the kinetic energy of relative motion of the Rydberg atom and target particle, and (in the case of attaching targets that dissociate) the energetics of dissociation that can be used to control the properties of the product ion-pair states. PMID:24952540

  4. Dynamics of heavy-Rydberg ion-pair formation in K(14p,20p)-SF6, CCl4 collisions

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The dynamics of formation of heavy-Rydberg ion-pair states through electron transfer in K(np)-SF6, CCl4 collisions is examined by measuring the velocity, angular, and binding energy distributions of the product ion pairs. The results are analyzed with the aid of a Monte Carlo collision code that models both the initial electron capture and the subsequent evolution of the ion pairs. The model simulations are in good agreement with the experimental data and highlight the factors such as Rydberg atom size, the kinetic energy of relative motion of the Rydberg atom and target particle, and (in the case of attaching targets that dissociate) the energetics of dissociation that can be used to control the properties of the product ion-pair states.

  5. Dynamics of heavy-Rydberg ion-pair formation in K(14p,20p)-SF{sub 6}, CCl{sub 4} collisions

    SciTech Connect

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

    2014-06-21

    The dynamics of formation of heavy-Rydberg ion-pair states through electron transfer in K(np)-SF{sub 6}, CCl{sub 4} collisions is examined by measuring the velocity, angular, and binding energy distributions of the product ion pairs. The results are analyzed with the aid of a Monte Carlo collision code that models both the initial electron capture and the subsequent evolution of the ion pairs. The model simulations are in good agreement with the experimental data and highlight the factors such as Rydberg atom size, the kinetic energy of relative motion of the Rydberg atom and target particle, and (in the case of attaching targets that dissociate) the energetics of dissociation that can be used to control the properties of the product ion-pair states.

  6. Rydberg atom wavepacket dynamics in one and two-dimensions

    NASA Astrophysics Data System (ADS)

    Mestayer, Jeffery

    Atoms in high-lying Rydberg states with large values of principal quantum number n, n ≥300, form a valuable laboratory in which to explore the control and manipulation of quantum states of mesoscopic size using carefully tailored sequences of short electric field pulses whose characteristic times (duration and/or rise/fall times) are less than the classical electron orbital period. Atoms react to such pulse sequences very differently than to short laser or microwave pulses providing the foundation for a number of new approaches to engineering atomic wavefunctions. The remarkable level of control that can be achieved is illustrated with reference to the generation of localized wavepackets in Bohr-like near-circular orbits, and the production of non-dispersive wavepackets under periodic driving and their transport to targeted regions of phase space. New protocols continue to be developed that will allow even tighter control with the promise of new insights into quantum-classical correspondence, information storage in mesoscopic systems, physics in the ultra-fast ultra-intense regime, and non-linear dynamics in driven systems.

  7. Rydberg-resolved resonant inelastic soft x-ray scattering: dynamics at core ionization thresholds.

    PubMed

    Rubensson, J-E; Söderström, J; Binggeli, C; Gråsjö, J; Andersson, J; Såthe, C; Hennies, F; Bisogni, V; Huang, Y; Olalde, P; Schmitt, T; Strocov, V N; Föhlisch, A; Kennedy, B; Pietzsch, A

    2015-04-01

    Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems. PMID:25884123

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

    NASA Technical Reports Server (NTRS)

    Chutjian, A. N. (Inventor)

    1986-01-01

    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.

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

    USGS Publications Warehouse

    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

    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.

  10. Fine structure and ionization energy of the 1s2s2p 4P state of the helium negative ion He-.

    PubMed

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

    2014-12-31

    The fine structure and ionization energy of the 1s2s2p (4)P state of the helium negative ion He(-) are calculated in Hylleraas coordinates, including relativistic and QED corrections up to O(α(4)mc(2)), O((μ/M)α(4)mc(2)), O(α(5)mc(2)), and O((μ/M)α(5)mc(2)). 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. PMID:25615325

  11. High teleportation rates using Rydberg-based quantum repeaters

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal; Quraishi, Qudsia

    2015-05-01

    Quantum networking over long distances may be achieved using repeater protocols to generate entanglement between memory nodes. Typically, long-lived memories have low entanglement generation rates. Neutral atom memories can be long-lived, emit at visible wavelengths and can be collectively excited leading to directionally emitted entangled photons. Here, we propose a simplified Rydberg-based quantum repeater based on recent work, where we reduce the number of ground states used for entanglement generation and use only one ensemble at each node, reducing the required resources. The collective excitation allows for deterministic memory generation that is mapped into a directionally emitted photonic qubit without the use of a high finesse optical cavity. We demonstrate a protocol between multiple memories stored within a single ensemble to implement a two-qubit gate. Additionally, we predict teleportation rates of 1 Hz without the use of a high finesse optical cavity, which could be increased to kHz if efficiencies are improved over the currently realized values. We plan to explore these protocols in ultra-cold ensemble of neutral 87Rb atoms and are currently building this setup.

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

    NASA Astrophysics Data System (ADS)

    Keele, Julie Adel

    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.

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

    NASA Astrophysics Data System (ADS)

    Huber, B.; Kölle, A.; Pfau, T.

    2014-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Holloway, Christopher L.; Gordon, Joshua A.; Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg

    2014-06-01

    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 μm, 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.

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

    SciTech Connect

    Holloway, Christopher L. Gordon, Joshua A.; Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg

    2014-06-16

    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 μm, 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.

  16. Adiabatic potential-energy curves of long-range Rydberg molecules: Two-electron R -matrix approach

    NASA Astrophysics Data System (ADS)

    Tarana, Michal; Čurík, Roman

    2016-01-01

    We introduce a computational method developed for study of long-range molecular Rydberg states of such systems that can be approximated by two electrons in a model potential of the atomic cores. Only diatomic molecules are considered. The method is based on a two-electron R -matrix approach inside a sphere centered on one of the atoms. The wave function is then connected to a Coulomb region outside the sphere via a multichannel version of the Coulomb Green's function. This approach is put into a test by its application to a study of Rydberg states of the hydrogen molecule for internuclear distances R from 20 to 400 bohrs and energies corresponding to n from 3 to 22. The results are compared with previous quantum chemical calculations (lower quantum numbers n ) and computations based on contact-potential models (higher quantum numbers n ).

  17. Magneto-Optical Trap for Preparation and Study of Rydberg Matter

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Our goal is the preparation and study of ultracold plasma and Rydberg matter. We assembled an experimental setup for laser cooling of lithium atoms in a magneto-optical trap (MOT). Trapping of 7Li atoms in a MOT is demonstrated for a wide range of cooling laser detunings. The number density of 7Li atoms at different ground-state sublevels is measured by using a probe tunable laser. The temperature of the trapped atoms is estimated. Obtained information is important for the preparation of ultra-cold plasma and highly-excited atoms.

  18. Resonant Charge Transfer of Hydrogen Rydberg Atoms Incident on a Cu(100) Projected Band-Gap Surface.

    PubMed

    Gibbard, J A; Dethlefsen, M; Kohlhoff, M; Rennick, C J; So, E; Ford, M; Softley, T P

    2015-08-28

    The charge transfer (ionization) of hydrogen Rydberg atoms (n=25-34) incident on a Cu(100) surface is investigated. Unlike fully metallic surfaces, where the Rydberg electron energy is degenerate with the conduction band of the metal, the Cu(100) surface has a projected band gap at these energies, and only discrete image states are available through which charge transfer can take place. Resonant enhancement of charge transfer is observed for Rydberg states whose energy matches one of the image states, and the integrated surface ionization signals (signal versus applied field) show clear periodicity as a function of n as the energies come in and out of resonance with the image states. The surface ionization dynamics show a velocity dependence; decreased velocity of the incident H atom leads to a greater mean distance of ionization and a lower field required to extract the ion. The surface ionization profiles for "on resonance" n values show a changing shape as the velocity is changed, reflecting the finite field range over which resonance occurs. PMID:26371649

  19. Using Rydberg Atom Electromagnetically Induced Transparency for Microwave Electrometry Applications

    NASA Astrophysics Data System (ADS)

    Sedlacek, Jonathon; Fan, Haoquan; Daschner, Renate; Ewel, Charles; Kübler, Harald; Shaffer, James

    2013-05-01

    We present a method to probe microwave fields and atom surface interactions using Rydberg atom electromagnetically induced transparency (EIT). The basic mechanism is to couple an external microwave field or surface polariton modes to a ladder-type Rydberg atom EIT system. Our technique is sensitive to both the amplitude and the polarization of the microwave field. In addition to developing this method for a microwave electric field standard, we are applying it to study Rydberg atoms interacting with surface polaritons and near-field effects with sub-wavelength resolution. We also investigate improvements in our sensitivity based on using dispersive, rather than absorptive effects, induced in the atoms. We acknowledge funding from DARPA and NSF.

  20. Rényi, Shannon and Tsallis entropies of Rydberg hydrogenic systems

    NASA Astrophysics Data System (ADS)

    Toranzo, I. V.; Dehesa, J. S.

    2016-02-01

    The Rényi entropies Rp[ρ], 0 of the probability density ρn,l,m(r ) of a physical system completely characterize the chemical and physical properties of the quantum state described by the three integer quantum numbers (n,l,m) . The analytical determination of these quantities is practically impossible up until now, even for the very few systems where their Schrödinger equation is exactly solved. In this work, the Rényi entropies of Rydberg (highly excited) hydrogenic states are explicitly calculated in terms of the quantum numbers and the parameter p. To do that we use a methodology which first connects these quantities to the Lp -norms Nn,l(p) of the Laguerre polynomials which characterize the state's wave function. Then, the Rényi, Shannon and Tsallis entropies of the Rydberg states are determined by calculating the asymptotics (n→∞) of these Laguerre norms. Finally, these quantities are numerically examined in terms of the quantum numbers and the nuclear charge.

  1. Lineshapes of Dipole-Dipole Resonances in a Cold Rydberg Gas

    NASA Astrophysics Data System (ADS)

    Richards, B. G.; Jones, R. R.

    2015-05-01

    We have examined the lineshapes associated with Stark tuned, dipole-dipole resonances involving Rydberg atoms in a cold gas. Rb atoms in a MOT are laser excited from the 5 p level to 32p3 / 2 in the presence of a weak electric field. A fast rising electric field pulse Stark tunes the total energy of two 32 p atom pairs so it is (nearly) degenerate with that of the 32s1 / 2+33s1 / 2 states. Because of the dipole-dipole coupling, atom pairs separated by a distance R, develop 32s1 / 2+33s1 / 2 character. The maximum probability for finding atoms in s-states depends on the detuning from degeneracy and on the dipole-dipole coupling. We obtain the ``resonance'' lineshape by measuring, via state-selective field ionization, the s-state population as a function of the tuning field. The resonance width decreases with density due to R-3 dependence of the dipole-dipole coupling. In principle, the lineshape provides information about the distribution of Rydberg atom spacings in the sample. For equally spaced atoms, the lineshape should be Lorentzian while for a random nearest neighbor distribution it appears as a cusp. At low densities nearly Gaussian lineshapes are observed with widths that are too large to be the result of inhomogeneous electric or magnetic fields. Supported by the NSF.

  2. Collisional and Radiative Processes in Adiabatic Deceleration, Deflection, and Off-Axis Trapping of a Rydberg Atom Beam

    SciTech Connect

    Seiler, Ch.; Hogan, S. D.; Schmutz, H.; Agner, J. A.; Merkt, F.

    2011-02-18

    A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 {mu}s, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.

  3. Helium-Recycling Plant

    NASA Technical Reports Server (NTRS)

    Cook, Joseph

    1996-01-01

    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.

  4. Polarization-selective optical nonlinearities in cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Wu, Jin-Hui; Artoni, M.; La Rocca, G. C.

    2015-12-01

    We study the interaction between a probe and a trigger weak fields in a sample of cold rubidium atoms in the presence of a coupling and a dressing strong fields. Dipole Rydberg blockade may occur and can be set to depend on the probe and trigger polarizations giving rise to diverse regimes of electromagnetically induced transparency (EIT) with a concomitant small probe and trigger absorption and dispersion. This is shown to be relevant to the implementation of polarization conditional probe and trigger cross nonlinearities in cold Rydberg atoms.

  5. Shannon entropy as an indicator of atomic avoided crossings for Rydberg potassium atoms interacting with a static electric field

    NASA Astrophysics Data System (ADS)

    He, Yong Lin; Chen, Yan; Han, Jiu Ning; Zhu, Zhi Bin; Xiang, Geng Xiang; Liu, Huai Dong; Ma, Bao Hong; He, De Chun

    2015-12-01

    We propose a method to calculate the positions of avoided crossings for Rydberg potassium in a static electric field by using Shannon entropy. Our method can be divided into two steps. At first we made a rough estimate of the range of the static electric field strength at which the given avoided crossings occur through strength dependence of the Shannon entropies for all the related states. Next, we obtained the position of the given avoided crossing by calculating the Shannon entropies intersection field strength for the two involved states. The Shannon entropies are calculated by using the one-electron wave functions derived from a well-established diagonalization method which is based on B-spline expansion technique and a parametric one-electron model potential. We have used this method to calculate a number of positions of both s and p states of avoided crossings for Rydberg potassium. The results are in excellent agreement with observed and other calculated results by using the ionization energies. Our study proves that Shannon entropy is an efficient information-theoretic parameter for characterization and prediction of avoided crossings of Rydberg potassium in the l-mixing region.

  6. Highly excited Rydberg electron as a spectator to an ion-molecule reaction

    SciTech Connect

    Matsuzawa, Michio

    2010-11-15

    We have theoretically studied the conditions of the behavior of a high Rydberg electron as a spectator to an ion-molecule reaction in high Rydberg neutral collisions. Adoption of a circular high Rydberg atom in the initial channel of the high Rydberg neutral collisions ensures the behavior of the high Rydberg electron as the spectator to interaction between an ion core of the high Rydberg atom and an incoming neutral species; i.e., the ion-molecule reaction. This theoretical consideration leads to equivalence between the high Rydberg neutral collision and the ion-molecule reaction with high accuracy. This equivalence gives us a possibility of probing the ion-molecule reaction at low energies without space-charge effects encountered in ion-beam experiments.

  7. Measurement of time-varying electric fields near an atom chip using cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    Inhomogeneous fluctuating electric fields near metal surfaces cause undesired heating or decoherence in devices which confine atoms or ions near such a surface (microfabricated ion traps or proposed gas-phase atom/solid-state hybrid quantum systems, for example). Heating of the motion of trapped ions has been used to measure the noise spectral density of these fields but the microscopic mechanism responsible is unknown. We have implemented a complementary measurement technique using cold atoms released from an atom chip and excited to Rydberg states. The dephasing of a coherent superposition of two Rydberg states is used to measure the inhomogeneous electric field, and spin-echo techniques are used to constrain the frequency scaling of the noise spectral density. Compared to ion trap measurements, this technique has the advantage of flexibility in varying parameters such as atom-surface distance since the atoms do not need to be trapped. Field noise at levels typical for room temperature ion traps is detectable in principle, though the frequency resolution and ultimate sensitivity are inferior to ion traps. Work performed in collaboration with O. Cherry and supported by NSERC.

  8. Helium technology issues

    NASA Technical Reports Server (NTRS)

    Kittel, Peter

    1987-01-01

    A number of future space missions require liquid helium for cooling scientific payloads. These missions will require the long term storage and resupply of liquid helium at temperatures of 1.4 - 2.1 Kelvin. In addition, some of the proposed instruments will require refrigeration to temperatures as low as 50 mK. A variety of liquid helium based refrigerator systems could provide this subkelvin cooling. The status of helium storage and refrigeration technologies and of several alternative technologies is presented here along with areas where further research and development are needed. (Helium resupply technologies are the topic of another presentation at this symposium). The technologies covered include passive and dynamic liquid helium storage, alternatives to liquid helium storage, He -3 refrigerators, He -3/He -4 dilution refrigerators, and alternative sub-kelvin coolers.

  9. Stark structure and field ionization characteristics of highly excited Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Kishimoto, Yasuhiro

    2002-03-01

    The Stark structure and time evolution of highly excited 85Rb Rydberg states in a pulsed electric field have been studied experimentally as well as theoretically. The Rydberg states in 85Rb with the principal quantum number n ranging from 110 to 140 have been excited with the two step laser excitation scheme and field ionization spectra under the pulsed electric field were observed with the ionized electron detection. From the systematic measurements it was found that the in general there exist two peaks in the field ionization spectrum: the lower peak is rather broad and the field value of the peak does not depend on the excitation position in the manifold. The value of the higher peak field, on the other hand, increases with increasing bluer states in the manifold when the pulsed electric field is increased in the same direction with the initially applied static field. However when the pulsed field is increased in the reversed direction to the static field, the peak field value decreases with increasing bluer state excitations, showing the opposite behavior to the case in the same field-driving direction. In order to reveal the origin of these two peak-field values in the ionization process, theoretical calculations of the Stark structure and ionization rates in an electric field have been performed with a computational method based on the Hamiltonian diagonalization. From these calculations it was found that the excitation position dependence of the higher peaks observed in the field ionization is in good agreement with the predictions from the tunneling process. On the other hand the lower peak behavior is roughly explained from the autoionization-like process together with the effect of the blackbody-induced radiative transitions to the neighboring states from the orignally excited states. In due course of the above investigations, time evolution of the multi-level Rydberg system in a pulsed electric field was also studied to confirm the usefulness and applicabilities of the present method of theoretical calculations. Specifically the transition probabilities in the first avoided crossing at which the 113p3/2 state crosses the bluest state in the 110 manifold was measured and compared with the theoretical predictions obtained from a newly developed formalism on the time evolution of multi-level Rydberg system. The experimental results are in good agreement with the predictions. The opposite behavior in the excitation-position dependence of the higher ionization peak-field between the same and the reversed driving directions of the pulsed electric field was also found to be well explained with the present theoretical treatment in the time evolution, thus showing that the present theoretical treatment is quite satisfactory even in such highly excited Rydberg atoms.

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    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 net average field they experience is near zero irrespective of whether the HCPs, applied parallel to the atomic axis, are directed towards or away from the nucleus. The nature of this stabilization is explored using Poincaré surfaces of section. In large offset fields, direct field ionization becomes possible but it is demonstrated that this can be suppressed by application of an oppositely directed HCP train. The use of such “frustrated field ionization” to measure the polarization of Rydberg atoms is discussed.

  11. Effect of Vapor-Cell Geometry on Rydberg-Atom-Based Measurements of Radio-Frequency Electric Fields

    NASA Astrophysics Data System (ADS)

    Fan, Haoquan; Kumar, Santosh; Sheng, Jiteng; Shaffer, James P.; Holloway, Christopher L.; Gordon, Joshua A.

    2015-10-01

    A new approach to detect absolute radio-frequency (rf) electric fields (E-fields) that uses Rydberg atoms at room temperature in vapor cells has been demonstrated recently. The large-transition dipole moments between energetically adjacent Rydberg states enable this technique to make traceable E-field measurements with high sensitivity over a large frequency range from 1 GHz to 1 THz. In this paper, we experimentally investigate how the vapor-cell geometry affects the accuracy of the measurements. We find that the effects of the vapor cell on the measured rf E-field are minimized by making the vapor-cell size small compared to the wavelength of the rf E-field.

  12. Characterizing high-n quasi-one-dimensional strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Hiller, M.; Yoshida, S.; Burgdörfer, J.; Ye, S.; Zhang, X.; Dunning, F. B.

    2014-02-01

    The production of high-n, n ˜300, quasi-one-dimensional (quasi-1D) strontium Rydberg atoms through two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The dipolar polarization of the electron wave function in the product states is probed using two independent techniques. The experimental data are analyzed with a classical trajectory Monte Carlo simulation employing initial ensembles that are obtained with the aid of quantum calculations based on a two-active-electron model. Comparisons between theory and experiment highlight different characteristics of the product quasi-1D states, in particular, their large permanent dipole moments, ˜1.0 to 1.2n2ea0, where e is the electronic charge and a0 is the Bohr radius. Such states can be engineered using pulsed electric fields to create a wide variety of target states.

  13. Investigation of fine-structure quantum beats in sodium Rydberg atoms by field ionization

    NASA Astrophysics Data System (ADS)

    Jeys, T. H.; Smith, K. A.; Dunning, F. B.; Stebbings, R. F.

    1981-06-01

    Pulsed dye lasers are used to excite sodium atoms into a coherent superposition of high Rydberg nd (2D32,2D52) states. Analysis of the field ionization behavior of these atoms reveals the time evolution of the superposition state. Rapid application of a weak electric field projects different components of the superposition state onto states having identifiably different field ionization behavior. Analysis of the signal from subsequent field ionization as a function of the time of weak-field application reveals fine-structure quantum beats. These beats result from the time development of the original superposition state. Measurements of the fine-structure quantum beat frequency are presented for the principal quantum numbers n=32, 34, 35, 36, 38, and 40.

  14. Ionization of nS, nP, and nD lithium, potassium, and cesium Rydberg atoms by blackbody radiation

    SciTech Connect

    Beterov, I. I. Ryabtsev, I. I.; Tretyakov, D. B.; Bezuglov, N. N.; Ekers, A.

    2008-07-15

    The results of theoretical calculations of the blackbody ionization rates of lithium, potassium, and cesium atoms residing in Rydberg states are presented. The calculations are performed for nS, nP, and nD states in a wide range of principal quantum numbers, n = 8-65, for blackbody radiation temperatures T = 77, 300, and 600 K. The calculations are performed using the known quasi-classical formulas for the photoionization cross sections and for the radial matrix elements of transitions in the discrete spectrum. The effect of the blackbody-radiation-induced population redistribution between Rydberg states on the blackbody ionization rates measured under laboratory conditions is quantitatively analyzed. Simple analytical formulas that approximate the numerical results and that can be used to estimate the blackbody ionization rates of Rydberg atoms are presented. For the S series of lithium, the rate of population of high-lying Rydberg levels by blackbody radiation is found to anomalously behave as a function of n. This anomaly is similar to the occurrence of the Cooper minimum in the discrete spectrum.

  15. Effect of photoions on the line shape of the Foerster resonance lines and microwave transitions in cold rubidium Rydberg atoms

    SciTech Connect

    Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Yakshina, E. A.; Ryabtsev, I. I.; Dyubko, S. F.; Alekseev, E. A.; Pogrebnyak, N. L.; Bezuglov, N. N.; Arimondo, E.

    2012-01-15

    Experiments are carried out on the spectroscopy of the Foerster resonance lines Rb(37P) + Rb(37P) {yields} Rb(37S) + Rb(38S) and microwave transitions nP {yields} n Prime S, n Prime D between Rydberg states of cold rubidium atoms in a magneto-optical trap (MOT). Under ordinary conditions, all spectra exhibit a linewidth of 2-3 MHz irrespective of the interaction time between atoms or between atoms and microwave radiation, although the limit resonance width should be determined by the inverse interaction time. The analysis of experimental conditions has shown that the main source of line broadening is the inhomogeneous electric field of cold photoions that are generated under the excitation of initial nP Rydberg states by broadband pulsed laser radiation. The application of an additional electric-field pulse that rapidly extracts photoions produced by a laser pulse leads to a considerable narrowing of lines of microwave resonances and the Foerster resonance. Various sources of line broadening in cold Rydberg atoms are analyzed.

  16. Correlated Atomic Pair Functions by the e-ϱ-Method. I. Ground State 11S and Lowest Excited States n1S (n > 1) and n3S of Helium

    NASA Astrophysics Data System (ADS)

    Seelig, F. F.; Becker, G. A.

    1999-12-01

    Some low n1S and n3S states of the helium atom are computed with the aid of the e-e method which formulates the electronic wave function of the 2 electrons ψ = e-e F, where ϱ=Z(r1+r2)-½r12 and here Z = 2. Both the differential and the integral equation for F contain a pseudopotential Ṽ instead of the true potential V that contrary to V is finite. For the ground state, F = 1 yields nearly the Hartree-Fock SCF accuracy, whereas a multinomial expansion in r1, r2 , r2 yields a relative error of about 10-7 . All integrals can be computed analytically and are derived from one single "parent" integral.

  17. High-resolution spectroscopy of He2+ using Rydberg-series extrapolation and Zeeman-decelerated supersonic beams of metastable He2

    NASA Astrophysics Data System (ADS)

    Jansen, Paul; Semeria, Luca; Merkt, Frédéric

    2016-04-01

    Recently, high-resolution spectroscopy of slow beams of metastable helium molecules (He2∗) generated by multistage Zeeman deceleration was used in combination with Rydberg-series extrapolation techniques to obtain the lowest rotational interval in the molecular helium ion at a precision of 18 MHz (Jansen et al., 2015), limited by the temporal width of the Fourier-transform-limited laser pulses used to record the spectra. We present here an extension of these measurements in which we have (1) measured higher rotational intervals of He2+, (2) replaced the pulsed UV laser by a cw UV laser and improved the resolution of the spectra by a factor of more than five, and (3) studied MJ redistribution processes in regions of low magnetic fields of the Zeeman decelerator and shown how these processes can be exploited to assign transitions originating from specific spin-rotational levels (N″,J″) of He2∗ .

  18. Quantum simulation of a topological Mott insulator with Rydberg atoms in a Lieb lattice

    NASA Astrophysics Data System (ADS)

    Dauphin, A.; Müller, M.; Martin-Delgado, M. A.

    2016-04-01

    We propose a realistic scheme to quantum simulate the so-far experimentally unobserved topological Mott insulator phase—an interaction-driven topological insulator—using cold atoms in an optical Lieb lattice. To this end, we study a system of spinless fermions in a Lieb lattice, exhibiting repulsive nearest- and next-to-nearest-neighbor interactions and derive the associated zero-temperature phase diagram within mean-field approximation. In particular, we analyze how the interactions can dynamically generate a charge density wave ordered, a nematic, and a topologically nontrivial quantum anomalous Hall phase. We characterize the topology of the different phases by the Chern number and discuss the possibility of phase coexistence. Based on the identified phases, we propose a realistic implementation of this model using cold Rydberg-dressed atoms in an optical lattice. The scheme, which allows one to access, in particular, the topological Mott insulator phase, robustly and independently of its exact position in parameter space, merely requires global, always-on off-resonant laser coupling to Rydberg states and is feasible with state-of-the-art experimental techniques that have already been demonstrated in the laboratory.

  19. High teleportation rates using cold-atom-ensemble-based quantum repeaters with Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal; Li, Xiao; Quraishi, Qudsia

    2016-04-01

    We present a simplified version of a repeater protocol in a cold neutral-atom ensemble with Rydberg excitations optimized for two-node entanglement generation and describe a protocol for quantum teleportation. Our proposal draws from previous proposals [B. Zhao et al., Phys. Rev. A 81, 052329 (2010), 10.1103/PhysRevA.81.052329; Y. Han et al., Phys. Rev. A 81, 052311 (2010), 10.1103/PhysRevA.81.052311] that described efficient and robust protocols for long-distance entanglement with many nodes. Using realistic experimental values, we predict an entanglement generation rate of ˜25 Hz and a teleportation rate of ˜5 Hz . Our predicted rates match the current state-of-the-art experiments for entanglement generation and teleportation between quantum memories. With improved efficiencies we predict entanglement generation and teleportation rates of ˜7.8 and ˜3.6 kHz, respectively, representing a two-order-of-magnitude improvement over the currently realized values. Cold-atom ensembles with Rydberg excitations are promising candidates for repeater nodes because collective effects in the ensemble can be used to deterministically generate a long-lived ground-state memory which may be efficiently mapped onto a directionally emitted single photon.

  20. Thermal desorption behavior of helium in aged titanium tritide films

    NASA Astrophysics Data System (ADS)

    Cheng, G. J.; Shi, L. Q.; Zhou, X. S.; Liang, J. H.; Wang, W. D.; Long, X. G.; Yang, B. F.; Peng, S. M.

    2015-11-01

    The desorption behavior of helium in TiT(1.5∼1.8)-x3Hex film samples (x = 0.0022-0.22) was investigated by thermal desorption technique in vacuum condition in this paper. The thermal helium desorption spectrometry (THDS) of aging titanium tritide films prepared by electron beam evaporation revealed that, depending on the decayed 3He concentration in the samples, there are more than four states of helium existing in the films. The divided four zones in THDS based on helium states represent respectively: (1) the mobile single helium atoms with low activation energy in all aging samples resulted from the interstitial sites or dissociated from interstitial clusters, loops and dislocations, (2) helium bubbles inside the grain lattices, (3) helium bubbles in the grain boundaries and interconnected networks of dislocations in the helium concentration of 3Hegen/Ti > 0.0094, and (4) helium bubbles near or linked to the film surface by interconnected channel for later aging stage with 3Hegen/Ti > 0.18. The proportion of helium desorption in each zone was estimated, and dissociated energies of helium for different trapping states were given.