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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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  8. 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.

  9. Alignment of D-state Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Lw, Robert; Krupp, Alexander; Gaj, Anita; Balewski, Jonathan; Ilzhfer, Philipp; Hofferberth, Sebastian; Kurz, Markus; Schmelcher, Peter; Pfau, Tilman

    2014-05-01

    For highly excited Rydberg atoms with principal quantum numbers n ~ 40, single ground state atoms can be trapped in the potential created by the Rydberg electron, leading to so called trilobite Rydberg molecules. Until now mostly S-states have been studied in terms of lifetime, coherence properties, dimers, trimers and polymers, permanent electric dipole moments, etc. Recently we have extended this class of molecules by D-state molecules offering more complex azimuthal structures. By choosing various magnetic substates, well separated by a magnetic offset field, we are able to address specific ro-vibronical states. A peculiar property of our excitation scheme is that the resulting Rydberg molecules are excited to stationary states with a high degree of alignment or anti-alignment.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.}

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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).

  2. Excitation of ultracold molecules to trilobite-like Rydberg states

    NASA Astrophysics Data System (ADS)

    Bellos, Michael; Carollo, Ryan; Banerjee, Jayita; Eyler, Edward; Gould, Phillip; Stwalley, William

    2013-05-01

    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 Rb2 at low principal quantum numbers and at internuclear distances below 40 bohr. We populate these states through single-photon ultraviolet transitions starting from molecules in high-lying vibrational levels. This demonstrates that long-range Rydberg molecules can also be excited through bound-bound transitions, in contrast with previous studies that used free-bound transitions. We discuss the advantages of a bound-bound pathway. Supported by the NSF and AFOSR (MURI).

  3. 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.

  4. Coherent Excitation of Lithium to Rydberg States and Application to Rydberg Atom Optics

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Widmer, M.; Tudorica, F.; Iu, C.-H.; Metcalf, H.

    1996-05-01

    We present a theoretical analysis of several schemes for coherently exciting lithium atoms in a thermal beam to Rydberg states in a four level/three laser system, previously discussed by Oreg et al.(J. Oreg et al.), Phys. Rev. A 45, 4888 (1992). The time evolution of the dressed states and their populations are calculated numerically, solving the optical Bloch equations by a fourth order Runge-Kutta integration. Our code closely models actual experimental conditions, including spontaneous decay, beam profiles, intensities and detunings. Large Rydberg populations (50%) around n=15 may be obtained by non-adiabatic excitation, with each laser power on the order of 1 mW. We discuss the effects of an externally controlled time dependent detuning in the Rydberg state, for example as produced by atoms traversing an inhomogeneous electric field. An understanding of this excitation mechanism is important for large angle reflection of coherently excited atoms using field gradients. Some primitive ideas of Stark-Rydberg atom optics are presented.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Static and dynamic polarizability for C2+ in Rydberg states

    NASA Astrophysics Data System (ADS)

    Stancalie, V.

    2015-07-01

    This work presents results from a non-perturbative calculation of dynamic polarizability of C III ions in 1s22sns (1Se) Rydberg states. We employ a two-state model for dressed atomic states to investigate the effect of the frequency-dependent polarizability of optically dressed 1s22sns(1Se) states (n = 5 - 12) on transitions to nearby states (1s22pns(1P1o)). Our model calculation results indicate that the resonance structure of the polarizabilities is entirely captured by the transition terms whereas the free electron polarizability only provides a smooth background. The resonance structure is evident in the plots and the widths increase with increasing principal quantum number. This work refers to highly excited 1s22sns (1S) Rydberg states, embedded in the electric dipole field of the 2s - 2p core transition in Li-like C3+ ion. The contributions of the individual transitions to the static polarizabilities of these Rydberg states are obtained from the use of the sum-over-state method. To this aim, both the C2+ ground state and the C3+ target state energies have been carefully calculated based on the configuration interactions method implemented in the General-purpose Relativistic Atomic Structure Package. Agreement is reasonably good with existing data wherever available. These results are believed to be the first such values for this system and will be important for ionic spectroscopy and plasma diagnostics.

  10. Stimulated adiabatic passage in a dissipative ensemble of atoms with strong Rydberg-state interactions

    NASA Astrophysics Data System (ADS)

    Petrosyan, David; Mlmer, Klaus

    2013-03-01

    We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg excitation of precisely one atom within the atomic ensemble. The quantum Zeno effect offers a lucid interpretation of this result: the Rydberg blocked atoms repetitively scattering photons effectively monitor a randomly excited atom, which therefore remains in the Rydberg state. This system can be used for deterministic creation and, possibly, extraction of Rydberg atoms or ions one at a time. The sympathetic monitoring via decay of ancilla particles may find wider applications for state preparation and probing of interactions in dissipative many-body systems.

  11. 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.

  12. 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.

  13. Theoretical investigation of state-changing thermal collisions between Rydberg atoms and ground state noble gas atoms

    SciTech Connect

    Davis, I.L.

    1983-01-01

    Two methods for calculating state-changing collisional matrix elements, and hence angular-momentum-mixing cross sections, are presented for a ground state noble gas atom colliding with a Rydberg atom at thermal energies. The first is a fully quantal method using Monte Carlo integration to perform the necessary nonseparable fifteen-dimensional collision integrals. The equations are developed for general treatment in the first and higher Born approximations, the distorted wave approximations,and several close-coupling schemes. The Monte Carlo method is carefully developed and tested for use in the types of integrals involved, and variance reduction techniques are discussed and applied. The second method uses a Gegenbauer polynomial expansion of the -1/r/sup 4/ polarization potential to find the necessary matrix elements. It also employs the elliptic functions and elliptic integrals to calculate the classical trajectory of the ground state atom as it passes the ionic Rydberg core. This semiclassical method is easily transformed into a fully quantal method, retaining only the polarization potential feature, by integrating the translational wave function of the incoming ground state atom and the matrix elements calculated via the Gegenbauer polynomials. The equations of scattering for the first quantal method are then specifically developed for ground state helium colliding with Rydberg helium, and calculation of the l-mixing cross section for He(10/sup 1/P) is performed using over a half million random fifteen-dimensional points. The result, accurate to within a factor of two, gives a result of 1600 A/sup 2/ compared to the experimental value of 2580 +/- 590 A/sup 2/. This experimental value is within the variance of the Monte Carlo calculation.

  14. Ionization of Rydberg H atoms at band-gap metal surfaces via surface and image states

    NASA Astrophysics Data System (ADS)

    So, E.; Gibbard, J. A.; Softley, T. P.

    2015-09-01

    Wavepacket propagation calculations are reported for the interaction of a Rydberg hydrogen atom (n=2-8) with Cu(111) and Cu(100) surfaces (represented by a Chulkov potential), in comparison with a Jellium surface. Both copper surfaces have a projected band gap at the surface in the energy range degenerate with some or all of the Rydberg energies. The charge transfer of the Rydberg electron to the surface is found to be enhanced for n values at which there is a near-degeneracy between the Rydberg energy level and an image state or a surface state of the surface. The enhancement is facilitated by the strong overlap of the surface image-state orbital lying outside the surface and the orbital of the incoming Rydberg atom. These calculations point to the possibility of using Rydberg-surface collisions as a probe of surface electronic structure.

  15. Evidence for a non-Rydberg molecular doubly excited state of Ca 2

    NASA Astrophysics Data System (ADS)

    Gaveau, M.-A.; Mestdagh, J.-M.; Bouissou, T.; Durand, G.; Heitz, M.-C.; Spiegelman, F.

    2009-01-01

    We report experimental and theoretical evidence of a non-Rydberg molecular doubly excited state of Ca 2 involving excited molecular orbitals mixing 4p and 3d characters. The excitation spectrum of Ca 2, carried by helium or argon clusters, is recorded experimentally in the range 25 600-27 800 cm -1, displaying a bimodal structure. The latter is interpreted from ab initio calculation and analysis of the adiabatic states of Ca 2 up to doubly excited asymptotes Ca(4p3d 1D) + Ca(4s 21S) and Ca(4s3d 3D) + Ca(4s4p 3P), and the relevant dipole transition moments. The bimodal structure is assigned as resulting from the avoided crossing between adiabatic states 3 1? u and 4 1? u, reflecting the mixing of doubly excited configurations and absorbing singly excited configurations.

  16. Auto transfer to Rydberg states during ion-atom collisions

    SciTech Connect

    Bachau, H.; Harel, C. ); Barat, M.; Roncin, P. ); Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Benoit-Cattin, P.; Gleizes, A.; Benhenni, M. )

    1993-06-05

    Electron capture by slow multiply charged ions colliding on rare-gas targets is known to populate highly excited states of the projectile. On the basis of experimental measurement of energy and angle differential cross-sections we have shown that capture to a resonant doubly excited state may lead to Autoionizing Double Capture (ADC) as well as to True Double Capture (TDC). In this model TDC appears as a two step post-collisional process, the state populated by the collision decays to (or delutes into) a dense adjacent Rydberg series, followed by radiative deexcitation of the inner electron of the (3,n) Rydberg states. We report here new experimental observations in electron spectra measured in [ital N][sup 7+]+[ital He]. Auto transfer to Rydber states has also important consequences on the determination of the lifetime of the autoionizing states, some discrepancies between theoretical width values for low [ital N][sup 5+](4,4) resonant states will be discussed and partially resolved.

  17. 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).

  18. Selective production of Rydberg-stark states of positronium.

    PubMed

    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 (1s?2p?nd/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. PMID:25978227

  19. 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.

  20. Rydberg States of Lithium and Other Systems

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    1999-01-01

    The interesting calculation of retardation corrections to excited atomic state energies is facilitated by the existence of good calculations of the nonrelativistic and nonretarded energies, to which retardation corrections can be added. Here I describe a perturbation method, applicable when the angular momentum is high enough which generates an asymptotic series for the energy. It makes use of generalized polarizabilities of the atomic or ionic core (numerically obtained) but otherwise is completely analytic. It is applied here to the lithium atom in detail, and its application to hydrogen molecular ions is outlined.

  1. Radiative transitions between Rydberg states of polar diatomic molecule. Part I: Linearly polarized light

    NASA Astrophysics Data System (ADS)

    Elfimov, Sergei V.; Dorofeev, Dmitrii L.; Zon, Boris A.

    2015-11-01

    With the help of a simple semi-analytical procedure the dipole matrix elements for Rydberg electron-rotational transitions in the SO molecule are calculated with account for dipole moment of rotating core. It results in non-zero matrix elements even for some transitions which are forbidden in conventional models of molecular Rydberg states.

  2. 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.

  3. 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.

  4. [Spectroscopic study of the 1pig Rydberg states of Na2].

    PubMed

    Xiang, J; Dai, X; Peng, S; Chen, H; Liu, Y; Li, J; Chen, D; Li, L

    1999-02-01

    Six highly excited 1pig states of the Na2 molecule have been investigated by optical-optical double resonance (OODR) flourescence excitation spectroscopy. Absolute vibrational numberings are determined and molecular constants and RKR potential curves are obtained. The lowest 10 1pig states have been relabeled according to the hydrogenic nllambda characters of the Rydberg orbital and classified into core-penetrating and core-nonpenetrating Rydberg states. PMID:15818899

  5. State-Mixing of nS Rydberg Atoms in an External Electric Field

    NASA Astrophysics Data System (ADS)

    Jiao, Yuechun; Wang, Limei; Zhang, Hao; Zhang, Linjie; Zhao, Jianming; Jia, Suotang

    2015-09-01

    State-mixing effect of ultracold nS cesium Rydberg atoms in an external electric field is investigated in a magneto-optical trap. Populated high-l Rydberg atoms due to the state-mixing through avoided crossings are measured with a state-selective field ionization technique. The measured transfer rates of high-l states increase with the electric field and get to the maximum at the field of about 3.0 V/cm for 49S1/2 Rydberg state, and show decrease behavior when the electric field increases further. The decrease behavior of the transfer rate is explained with the slower m-mixing effect caused by decreasing dipole-dipole interactions between high-l Rydberg atoms. During the m-mixing process the ultracold plasma is formed by the Penning ionization.

  6. 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.

  7. 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.

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

    SciTech Connect

    Gudmundsdttir, Hildur; Zhang, Yao; Weber, Peter M.; Jnsson, Hannes; Faculty of Physical Sciences, VR-III, University of Iceland, 107 Reykjavk

    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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    PubMed

    Bogomolov, Alexandr S; Grner, Barbara; Kochubei, Sergei A; Mudrich, Marcel; Baklanov, Alexey V

    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(-1) covering the bands of high-lying gerade Rydberg states [(2)?1/2]c6d;0g (+) and [(2)?1/2]c6d;2g has been applied. The ion signal was dominated by the atomic fragment ion I(+). Up to 5 dissociation channels yielding I(+) ions with different kinetic energies were observed when the I2 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(+) and I(-) ions with equal kinetic energy indicating predissociation of I2 via ion-pair states. The contribution of this channel was up to about 50% of the total I(+) signal. The four other channels correspond to predissociation via lower lying Rydberg states giving rise to excited iodine atoms providing I(+) 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 I2, which was previously considered to be the origin of ionic signal in this spectral range. The first-tier E0g (+) and D(')2g ion-pair states are concluded to be responsible for predissociation of Rydberg states [(2)?1/2]c6d;0g (+) and [(2)?1/2]c6d;2g, respectively. Further predissociation of these ion-pair states via lower lying Rydberg states gives rise to excited I(5s(2)5p(4)6s(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 I2 molecule. PMID:24697445

  18. 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

  19. 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.

  20. 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-? 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.

  1. 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.

  2. 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.

  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. 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).

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

    NASA Astrophysics Data System (ADS)

    Srkny, L?rinc; Fortgh, Jzsef; 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.

  6. 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.

  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. 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.

  9. Population transfer and quantum entanglement implemented in cold atoms involving two Rydberg states via an adiabatic passage

    NASA Astrophysics Data System (ADS)

    Tian, Xue-Dong; Liu, Yi-Mou; Cui, Cui-Li; Wu, Jin-Hui

    2015-12-01

    We study the adiabatic passage for a pair of interacting cold atoms driven into the ladder configuration with one ground state and two Rydberg states. We find, with proper single-photon and two-photon detunings, that it is viable to (i) achieve efficient population transfer from the ground state to either Rydberg state by fully overcoming the dipole blockade effect and (ii) implement maximal entangled states by partially overcoming the dipole blockade effect. These entangled atomic states are very stable and have purities and fidelities approaching 100%, among which one is of particular interest since it involves the simultaneous excitation of two different Rydberg states.

  10. Many-body physics of Rydberg dark-state polaritons in the strongly interacting regime

    NASA Astrophysics Data System (ADS)

    Moos, Matthias; Hning, Michael; Unanyan, Razmik; Fleischhauer, Michael

    2015-11-01

    Coupling light to Rydberg states of atoms under conditions of electromagnetically induced transparency (EIT) leads to the formation of interacting quasiparticles, termed Rydberg polaritons. We derive a one-dimensional model describing the time evolution of these polaritons under paraxial propagation conditions. Specifically, we obtain a master equation governing the dynamics of Rydberg polaritons and identify conditions when it can essentially be described by an effective Hamiltonian of a single-species polariton. We verify this Hamiltonian by numerical two-excitation simulations. Under typical stationary EIT conditions it is impossible to reach the strongly interacting regime where long-range density-density correlations emerge. In contrast, by employing the time dependence of the control field the regime of strong interactions can be reached where the polaritons attain quasicrystalline order. We provide a physical explanation for the differences between stationary and time-dependent schemes.

  11. 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.

  12. Rydberg blockade, Frster resonances, and quantum state measurements with different atomic species

    NASA Astrophysics Data System (ADS)

    Beterov, I. I.; Saffman, M.

    2015-10-01

    We calculate interspecies Rydberg-Rydberg interaction strengths for the heavy alkali metals Rb and Cs. The presence of strong Frster resonances makes interspecies coupling a promising approach for long-range entanglement generation. We also provide an overview of the strongest Frster resonances for Rb-Rb and Cs-Cs using different principal quantum numbers for the two atoms. We show how interspecies coupling can be used for high fidelity quantum nondemolition state measurements with low cross-talk in qubit arrays.

  13. 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.

  14. 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.

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

    SciTech Connect

    Sprecher, Daniel; Merkt, Frdric

    2014-03-28

    The structure and dynamics of high-n Rydberg states belonging to series converging to the (v{sup +} = 0, N{sup +} = 02) levels of the X{sup +2}?{sub g}{sup +} electronic ground state of HD{sup +} were studied by high-resolution spectroscopy from the GK{sup 1}?{sub g}{sup +} (v= 1, N = 1) state under field-free conditions. Three effects of g/u-symmetry breaking were detected: (i) Single-photon transitions from the GK?(v = 1, N = 1) state of gerade symmetry to the 30d2{sub 1} and 31g2{sub 2} Rydberg states of gerade symmetry were observed after careful compensation of the stray electric fields. (ii) The singlet 61p1{sub 2} Rydberg state of ungerade symmetry was found to autoionize to the N{sup +} = 0,?? = 2 ionization continuum of gerade symmetry with a lifetime of 77(10)?ns. (iii) Shifts of up to 20?MHz induced by g/u-symmetry mixing were measured for members of the np1{sub 1} Rydberg series which lie close to nd2{sub 1} Rydberg states. These observations were analyzed in the framework of multichannel quantum-defect theory. From the observed level shifts, the off-diagonal eigenquantum-defect element ?{sub pd} of singlet-? symmetry was determined to be 0.0023(3) and the corresponding autoionization dynamics could be characterized. The ionization energy of the GK?(v = 1, N = 1) state of HD was determined to be 12?710.544?23(10)?cm{sup ?1}.

  16. Field ionization process of Eu 4f76snp Rydberg states

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Shen, Li; Dai, Chang-Jian

    2015-11-01

    The field ionization process of the Eu 4f76snp Rydberg states, converging to the first ionization limit, 4f76s 9S4, is systematically investigated. The spectra of the Eu 4f76snp Rydberg states are populated with three-step laser excitation, and detected by electric field ionization (EFI) method. Two different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. The exact EFI ionization thresholds for the 4f76snp Rydberg states can be determined by observing the corresponding EFI spectra. In particular, some structures above the EFI threshold are found in the EFI spectra, which may be interpreted as the effect from black body radiation (BBR). Finally, the scaling law of the EFI threshold for the Eu 4f76snp Rydberg states with the effective quantum number is built. Project supported by the National Natural Science Foundation of China (Grant Nos. 11004151 and 11174218).

  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. Rydberg transitions in high angular momentum states of beryllium-like Si{sup 10+}

    SciTech Connect

    Serpa, F.G.; Livingston, A.E.; Kukla, K.W.; Galvez, E.J.

    1993-05-01

    We have studied the structures of high angular momentum Rydberg states in Be-like Si{sup 10+} using ultraviolet spectroscopy of an excited fast ion beam at the Notre Dame Tandem Accelerator. The spectra of the n = 7-8, 8-9, and 9-10 transitions are reported for angular momentum states L>4. The unperturbed highest angular momentum state energies are formulated in terms of a core polarization model of long range electron-ion interactions. The lower L states exhibit perturbations due to mixing with core excited levels. Rydberg transitions between the core excited states have also been identified, and these radiative branches are found to be partially suppressed by autoionization effects at high n. Comparisons of the measurements with multi-configuration Dirac-Fock calculations are presented. For the highest L states, comparisons with many body perturbation theory calculations are discussed.

  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. Rydberg states in multiply charged ions. Progress report, August 1, 1992--April 30, 1993

    SciTech Connect

    Livingston, A.E.

    1993-05-01

    This report summarizes research progress in accelerator-based studies of atomic structure and decay characteristics of excited states in multiply charged ions. This work involves spectroscopic measurements in visible to extreme ultraviolet wavelength regions of atomic transitions involving Rydberg states and low-lying excited states in multiply charged ions. These investigations are of both fundamental and applied interest. Of fundamental importance are trusts of long range electron-ion interactions and many-body electron correlations in Rydberg states, sensitivity to relativistic effects in the energy structures of few-electron ions, and tests of accurate many-body calculations of transition probabilities. This has application to understanding of laboratory and astrophysical plasmas and of detailed atomic structure and decay properties in highly charged ions.

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

    SciTech Connect

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

    1993-05-01

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

  8. 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.

  9. 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.

  10. 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.

  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 ? --> ? */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. Heavy Rydberg behaviour in high vibrational levels of some ion-pair states of the halogens and inter-halogens.

    PubMed

    Donovan, Robert J; Lawley, Kenneth P; Ridley, Trevor

    2015-05-28

    We report the identification of heavy Rydberg resonances in the ion-pair spectra of I2, Cl2, ICl, and IBr. Extensive vibrational progressions are analysed in terms of the energy dependence of the quantum defect ?(Eb) 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 ?(Eb), 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(-1) below dissociation. The rapid semi-classical calculation of ?(Eb) 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. PMID:26026446

  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. Quantum defects of nonpenetrating Rydberg states of the SO molecule in adiabatic and nonadiabatic regions of the spectrum

    NASA Astrophysics Data System (ADS)

    Dorofeev, Dmitry L.; Elfimov, Sergei V.; Zon, Boris A.

    2012-02-01

    This paper is dedicated to the implementation of a generalized approach for calculating quantum defects in high Rydberg states of polar molecules with an account for the dipole moment of the molecular core and l uncoupling of the Rydberg electron. Adiabatic (Born-Oppenheimer) and nonadiabatic (inverse Born-Oppenheimer) regions of the spectrum are considered. The nonadiabatic case with a nonzero projection of the core momentum on the core axis is considered and is illustrated by the example of the SO molecule.

  16. 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.

  17. 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.

  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. Signatures of Anderson localization in the ionization rates of periodically driven Rydberg states

    NASA Astrophysics Data System (ADS)

    Wimberger, Sandro; Buchleitner, Andreas

    2001-09-01

    We provide a statistical characterization of the ionization yield of one-dimensional, periodically driven Rydberg states of atomic hydrogen, in the spirit of Anderson localization theory. We find excellent agreement with predictions for the conductance across an Anderson localized, quasi-one-dimensional, disordered wire, in the semiclassical limit of highly excited atomic initial states. For the moderate atomic excitations typically encountered in state of the art laboratory experiments, finite-size effects induce significant deviations from the solid state picture. However, large-scale fluctuations of the atomic conductance prevail and are robust when averaged over a finite interval of driving field amplitudes, as inevitably done in the experiment.

  1. The role of optical transitions between ionic and Rydberg states in a KrF laser

    SciTech Connect

    Datsyuk, V V

    2001-05-31

    The upper laser level of a KrF laser is treated as a cluster containing several hundreds vibration-rotation energy levels of the electronic state B, which is mixed due to collisions with the close ionic state C. The KrF (C) state is depleted as a result of optical transitions to a higher Rydberg state. This model explains the experimental data on the picosecond dynamics of the light amplification. The possibility of using a KrF laser as an amplifier of radiation with a wavelength of 120 nm is discussed. (lasers and amplifiers)

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  3. 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.

  4. 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

  5. Rydberg atoms in ponderomotive potentials

    NASA Astrophysics Data System (ADS)

    Knuffman, Brenton J.

    In this thesis, we examine the ponderomotive interaction between an applied optical field and a highly excited Rydberg electron. An atom in a Rydberg state is essentially composed of an electron loosely bound, at a relatively large radial separation, to a positive ionic core. As such, the ponderomotive interaction for the Rydberg electron is similar to the interaction with free charges, which has been studied in context of plasma physics, new particle accelerator techniques, ion trapping, and electron diffraction among others. We are focused on using the ponderomotive interaction with the Rydberg electron to exert control over both the center-of-mass and electronic states of translationally cold Rydberg atoms. These capabilities can be adapted as tools for application in many experiments in areas such as atomic spectroscopy and quantum information processing. Our theoretical investigations have provided a well-defined parameter space for our experimental work and have allowed us to develop experimental methods appropriate for studying Rydberg atoms in ponderomotive potentials. In dense gases of cold Rydberg atoms, rich dynamics stem from electric multipole interactions among the Rydberg atoms. For example, interatomic forces between Rydberg atoms cause state-changing collisions which can significantly increase the kinetic energy of the colliding atoms. In addition to the studies of Rydberg atoms in ponderomotive potentials, we discuss collisions of cold Rydberg atoms in which internal energy of the Rydberg atoms is converted into kinetic energy.

  6. Scheme for Launching and Observing Dynamics of Cold Atoms in Rydberg States

    NASA Astrophysics Data System (ADS)

    Goodsell, Anne; Weidner, Erik; Fitzpatrick, Mattias

    2013-05-01

    We are assembling a source of laser-cooled Rb atoms that can be launched at slow, controlled velocities and excited into Rydberg states. We assess the feasibility of detecting the motion of cold Rydberg atoms around a macroscopic charged wire. The capture and ionization of cold ground-state atoms in a 1 / r -electric field has been observed previously, using a nanowire to ensure that captured atoms could move in free space at small radial distances before impacting the wire or field-ionizing near the surface. Using highly-excited atoms instead, we suggest that a macroscopic wire offers a robust system with magnified effects. The capture cross-section increases for incident atoms in high- n states. For a 20-micron-diameter wire charged to +300 V, the critical impact parameter for atoms traveling at 2 m/s with n = 50 is 30 ?m, 10 times larger than for ground-state atoms. We propose that aspects of this model can be realized experimentally. Using an estimated lifetime of 40 ns for the n = 50 state, we calculate that excitation must occur at r=100 ?m, significantly beyond the wire's surface. In this way, we are preparing to promote launched atoms into high- n states and study their dynamics.

  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. An accurate quantum expression for radiative transitions between the Stark levels of nearby Rydberg states

    NASA Astrophysics Data System (ADS)

    Dewangan, D. P.; Neerja; Basuchoudhury, K.

    2005-04-01

    The paper presents a new alternative exact quantum expression of the x-component of the dipole matrix element between the Stark states of a hydrogen atom in terms of the Jacobi polynomials by transforming the hypergeometric functions appearing in the standard quantum formula. The new quantum formula readily leads to analytic study and numerical computation for such large values of the parabolic quantum numbers for which difficulties had earlier been encountered. The paper goes on to derive an approximate but simple quantum formula of the dipole matrix element in terms of the ordinary Bessel functions and demonstrates its remarkable accuracy for transitions ranging from that between the Stark levels of the lowest lying states to that between the Stark levels of nearby Rydberg states. The formula enables accurate numerical computation to be performed over an extended range of large parabolic quantum numbers that had earlier defied evaluation. The expressions given in this paper in essence solve the problem of determination of analytic behaviour and numerical computation of the dipole matrix element for transitions between the Stark levels of nearby Rydberg states. The paper also presents, for the first time, a derivation of the formula of the correspondence principle method from the quantum expression without appealing to any classical or semiclassical argument, and clarifies the conditions of its applicability.

  9. Multiphoton spectroscopy of Rydberg states of small molecules

    SciTech Connect

    Pratt, Stephen T.; McCormack, E. F.; Dehmer, Joseph L.; Dehmer, Patricia M.

    1990-09-01

    Multiphoton ionization techniques provide a versatile means for studying highly excited states of atoms and molecules and provide a valuable complement to traditional techniques based on single-photon absorption and ionization studies. In this paper we present the results of new multiphoton ionization studies of molecular nitrogen and molecular oxygen that serve to illustrate the power of these techniques. 30 refs., 3 figs.

  10. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2002-10-01

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

  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. 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.

  14. Scaled energy analysis of the Stark effect for highly perturbed Rydberg states of Barium

    NASA Astrophysics Data System (ADS)

    Bates, Kenn; Vasilescu, Camelia; Masae, Jumpei; Schumacher, Douglass

    2001-05-01

    The electron dynamics of strongly perturbed Rydberg states in Ba have been examined in an electric field. We report an analysis of scaled absorption spectra collected for states near the strong 5d7d perturber. We select initial conditions that constrain how possible orbits can contribute by exciting via 6s^2arrow 5d6parrow 6snd (n? 27). The 5d6p state couples to the upper states principally through their configuration mixed doubly excited character. Simple classical features underly the complex system. In the time domain, the Stark recurrence spectra have periods identified with uphill/downhill orbits and Stark precessions. At very low scaled energies, \\varepsilon <= -6, we find recurring scaled action peaks at F^1/4?2| \\varepsilon | ? 1.4. This is different than alkali atoms, where scaled actions corresponding to integer and half integer values have previously been reported.

  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. Efficient production of Rydberg positronium.

    PubMed

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

    2012-01-27

    We demonstrate experimentally the production of Rydberg positronium (Ps) atoms in a two-step process, comprising incoherent laser excitation, first to the 2(3)P state and then to states with principal quantum numbers ranging from 10 to 25. We find that excitation of 2(3)P atoms to Rydberg levels occurs very efficiently (~90%) and that the ~25% overall efficiency of the production of Rydberg atoms is determined almost entirely by the spectral overlap of the primary excitation laser and the Doppler broadened width of the 1 (3)S-2(3)P transition. The observed efficiency of Rydberg Ps production can be explained if stimulated emission back to the 2P states is suppressed, for example, by intermixing of the Rydberg state Stark sublevels. The efficient production of long-lived Rydberg Ps in a high magnetic field may make it possible to perform direct measurements of the gravitational free fall of Ps. PMID:22400840

  17. Femtosecond predissociation dynamics of the methyl radical from the 3pz Rydberg state.

    PubMed

    Balerdi, Garikoitz; Woodhouse, Joanne; Zanchet, Alexander; de Nalda, Rebeca; Senent, Mara L; Garca-Vela, Alberto; Baares, Luis

    2016-01-01

    The real time dynamics of electronic predissociation of the CH3 radical (and its deuterated variant CD3) from selected vibrational states of the 3pz Rydberg state have been measured for the first time using a novel methodology based on a femtosecond three-color experiment to generate, two-photon excite and ionize methyl radicals as a function of time in combination with velocity map imaging detection. Subpicosecond lifetimes have been measured, showing a decreasing trend as vibrational excitation in the symmetric stretch and bending umbrella modes increases for both species. High-level ab initio calculations have been carried out in order to elucidate the CH3 3pz predissociation mechanism and support the lifetime measurements. The observed lifetimes are relevant for the understanding of the resonance enhanced multiphoton ionization spectroscopy of this radical. PMID:26473180

  18. 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.

  19. Long-range interaction between metastable helium and ground state helium.

    NASA Technical Reports Server (NTRS)

    Victor, G. A.; Sando, K.

    1971-01-01

    Results of analysis for the long-range interaction between ground state helium and triplet metastable helium, which shows that the long-range coefficient is the same for both gerade and ungerade states. Those terms which lead to the second term on the right hand side of a developed equation vanish through spin selection rules.

  20. Vacuum ultraviolet excitation spectroscopy of the autoionizing Rydberg states of atomic sulfur in the 73 350-84 950 cm{sup -1} frequency range

    SciTech Connect

    Yang Xueliang; Zhou Jingang; Jones, Brant; Ng, C. Y.; Jackson, William M.

    2008-02-28

    The photoionization efficiency (PIE) spectra of metastable sulfur (S) atoms in the {sup 1}D and {sup 1}S states have been recorded in the 73 350-84 950 cm{sup -1} frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S({sup 1}D) and S({sup 1}S) atoms are produced by the 193 nm photodissociation of CS{sub 2}. The observed PIE spectra of S({sup 1}D) and S({sup 1}S) shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S{sup +}({sup 4}S{sub 3/2})+e{sup -} ionization continuum. Velocity-mapped ion images of the S{sup +} at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the {sup 1}D, {sup 1}S, or {sup 3}P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes {tau} of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of {tau}(n*){proportional_to}n*{sup 3}, where n* is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.

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

    SciTech Connect

    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.

  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. 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.

  4. 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.

  5. 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 (^5?^+_g, ^5?^-_g, ^5?^-_u, ^5?_u, ^5?_g, ^5?_g) dissociating to the first dissociation limit O(^3P)+O(^3P) are reported. The four ion--pair quintet states (^5?^-_g, ^5?^-_u, ^5?_g, ^5?_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^4?_u, b^4?^-_g, f^4?_g and ^6?^+_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.

  6. A heavy Rydberg quantum defect analysis of the perturbed D (0u+) ion-pair state of Br2

    NASA Astrophysics Data System (ADS)

    Donovan, Robert J.; Lawley, Kenneth P.; Ridley, Trevor

    2015-12-01

    A quantum defect (?) analysis, based on the heavy Rydberg model of ion-pair states, is applied to existing data on the D state of Br2. A linear dependence of the mass-scaled ? on the bound energy is found between 18,000 cm-1 and at least 22,000 cm-1 below dissociation, with local vibronic perturbations. At lower bound energies there is an abrupt reversal of the gradient of the energy dependence of ? in the region of strong interaction with the 5p electronic Rydberg states. The energy dependence of ? emphasizes changes in gradient of either the inner or outer wall of the potential. An adiabatic potential energy function for the D state with a modified inner wall is proposed which accounts for the quantum defect in the anomalous region. The highest vibrational levels that were omitted from the standard polynomial fit of the vibrational term values used by previous authors are now included.

  7. Microwave Transitions Between Pair States Composed of Two rb Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghun; Gallagher, Tom

    2015-06-01

    Microwave transitions between pair states composed of two Rb Rydberg atoms in a magneto-optical trap are investigated. Our current interest is the transition from ndnd to (n+1)d(n-2)f states. This transition is allowed because the dipole-dipole induced configuration interaction between the ndnd state and the energetically close (n+2)p(n-2)f state admixes some of the latter state into the former. The resonance frequencies of the ndnd-(n+1)d(n-2)f transitions for n=35 to 42 have been measured and found to agree well with the calculated values. In addition, the power shifts of the resonance frequencies have been measured for n=35 to 42. The dependence of the fractional population transfer from the ndnd to (n+1)d(n-2)f states on the microwave field strength and atomic density has been measured and can be compared to a simple theoretical model. This work has been supported by the Air Force Office of Scientific Research.

  8. Microwave transitions between pair states composed of two Rb Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghun; Gallagher, Tom

    2015-05-01

    Microwave transitions between pair states composed of two Rb Rydberg atoms in a magneto-optical trap are investigated. Our current interest is the transition from ndnd to (n+1)d(n-2)f states. This transition is allowed because the dipole-dipole induced configuration interaction between the ndnd state and the energetically close (n+2)p(n-2)f state admixes some of the latter state into the former. The resonance frequencies of the ndnd-(n+1)d(n-2)f transitions for n = 35 to 42 have been measured and found to agree well with the calculated values. In addition, the power shifts of the resonance frequencies have been measured for n = 35 to 42. The dependence of the fractional population transfer from the ndnd to (n+1)d(n-2)f states on the microwave field strength and atomic density has been measured and can be compared to a simple theoretical model. This work has been supported by the Air Force Office of Scientific Research.

  9. Field modulation of Rydberg-state populations of NO studied by femtosecond time-resolved photoelectron imaging

    SciTech Connect

    Wang Bingxing; Liu Benkang; Wang Yanqiu; Wang Li

    2010-04-15

    Femtosecond time-resolved velocity map imaging combined with multiphoton ionization was applied to study the optical field modulation of NO Rydberg-state populations. The A {sup 2{Sigma}+}({upsilon}=2) state is populated by absorption of one 271-nm photon. Two peaks in the photoelectron kinetic energy spectra, centered at 0.82 and 2.35 eV, are caused by ionization from the A {sup 2{Sigma}+}({upsilon}=2) state by time-delayed one-color and two-color multiphoton ionization, respectively. In the overlap region of the pump and probe light, the C {sup 2{Pi}}({upsilon}=4) state is populated by a 1+1{sup '} excitation. When the pump laser intensity is increased, other Rydberg states (E {sup 2{Sigma}+}, F {sup 2{Delta}}, and D {sup 2{Sigma}+}) are moved into resonance by a laser-induced Stark shift. These states can be populated only within the temporal overlap region of the pump and probe light. When the intensity of the pump laser is higher than 2.9 x 10{sup 12} W/cm{sup 2}, Rydberg-valence coupling between the A {sup 2{Sigma}+}({upsilon}=2) and B {sup 2{Pi}}({upsilon}=4) states may play a key role, resulting in photoelectrons with kinetic energy of 0.37 eV. The coupling strength increases with increasing pump laser intensity.

  10. Coupled electronic and structural relaxation pathways in the postexcitation dynamics of Rydberg states of BaArN clusters.

    PubMed

    Masson, A; Heitz, M-C; Mestdagh, J-M; Gaveau, M-A; Poisson, L; Spiegelman, F

    2014-09-19

    We investigate, theoretically, the joint relaxation of orbital and structure in postexcitation dynamics of Rydberg states of cluster BaArN (N=250). Mixed quantum-classical dynamics is used to account for the nonadiabatic transitions among more than 160 electronic states, represented via a diatomics-in-molecules Hamiltonian. The simulation illustrates the complex multistep relaxation processes and provides detailed insight in the mechanisms contributing to the final-time experimental photoelectron spectrum. PMID:25279627

  11. Coupled Electronic and Structural Relaxation Pathways in the Postexcitation Dynamics of Rydberg States of BaArN Clusters

    NASA Astrophysics Data System (ADS)

    Masson, A.; Heitz, M.-C.; Mestdagh, J.-M.; Gaveau, M.-A.; Poisson, L.; Spiegelman, F.

    2014-09-01

    We investigate, theoretically, the joint relaxation of orbital and structure in postexcitation dynamics of Rydberg states of cluster BaArN (N =250). Mixed quantum-classical dynamics is used to account for the nonadiabatic transitions among more than 160 electronic states, represented via a diatomics-in-molecules Hamiltonian. The simulation illustrates the complex multistep relaxation processes and provides detailed insight in the mechanisms contributing to the final-time experimental photoelectron spectrum.

  12. High-resolution spectroscopy and quantum-defect model for the gerade triplet np and nf Rydberg states of He{sub 2}

    SciTech Connect

    Sprecher, D.; Liu, J.; Krhenmann, T.; Schfer, M.; Merkt, F.

    2014-02-14

    Photoionization spectra and Rydberg-state-resolved threshold-ionization spectra of the gerade triplet np Rydberg states of {sup 4}He{sub 2} located in the vicinity of the X{sup +2}?{sub u}{sup +}(?{sup +} =0) ionization threshold were recorded from the 2s?a{sup 3}?{sub u}{sup +} metastable state. An accuracy of 0.01?cm{sup ?1} was achieved for the experimental term values of the observed Rydberg states. The data were combined with spectroscopic data on low-lying triplet np and nf Rydberg states from the literature to derive energy- and internuclear-distance-dependent eigenquantum-defect parameters of multichannel quantum-defect theory (MQDT). The MQDT calculations reproduce the experimental data within their experimental uncertainties and enabled the derivation of potential-energy curves for the lowest triplet p Rydberg states (n = 25) of He{sub 2}. The eigenquantum-defect parameters describing the p?-f interaction were found to be larger than 0.002 at the energies corresponding to the high-n Rydberg states, so that the p?-f interaction plays an important role in the autoionization dynamics of np Rydberg states with ?{sup +} = 0. By extrapolating the experimental term values of triplet np Rydberg states of {sup 4}He{sub 2} in the range of principal quantum number n between 87 and 110, the positions of the (?{sup +} = 0, N{sup +} = 3) and (?{sup +} = 0, N{sup +} = 5) levels of the ground state of {sup 4}He{sub 2}{sup +} were determined to lie 70.937(3)?cm{sup ?1} and 198.369(6)?cm{sup ?1}, respectively, above the (?{sup +} = 0, N{sup +} = 1) ground rotational level.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. Quenching of low-lying Rydberg states of Na colliding with ground-state He: A semiclassical approach

    SciTech Connect

    Kumar, A.; Lane, N.F.; Kimura, M.

    1989-02-01

    The molecular expansion method within the framework of the semiclassical approximation is applied to quenching of low-lying excited states of Rydberg atoms colliding with ground-state He at thermal energies. Interactions between the colliding atoms are accounted for in terms of pseudopotentials, and their relative motion is described by a classical linear trajectory. A fairly large basis set of Slater-type orbitals is used to obtain molecular eigenstates, and subsequently a 14-state close-coupling calculation is performed to evaluate the total quenching cross sections and the contributions of individual transitions. The energy dependence of the calculated cross sections is investigated, and possible mechanisms responsible for individual transitions are explained. Finally, the collision rates are calculated and compared with experimental results.

  18. Molecule Formation and State-Changing Collisions of Single Rydberg Atoms in a Bec

    NASA Astrophysics Data System (ADS)

    Kleinbach, Kathrin Sophie; Schlagmller, Michael; Cubel Liebisch, Tara; Westphal, Karl Magnus; Bttcher, Fabian; Lw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Prez-Ros, Jess; Greene, C. H.

    2015-06-01

    A single Rydberg excitation in the high-density and low-temperature environment of a Bose-Einstein condensate (BEC) leads to a fascinating testbed of low-energy electron-neutral and ion-neutral scattering. In particular the small interparticle spacing in a BEC makes it possible to study the role of ion-neutral interactions in l-changing collisions on time scales much shorter than the Rydberg lifetime. We take advantage of the mean field density shift, caused by elastic electron-neutral collisions, to probe density dependent shells of the 87Rb BEC and thereby measure the l-changing collision time versus density and principal quantum number. We report on l-changing collisions due to inelastic scattering of the Rydberg electron with a neutral atom located near the Rydberg ionic core. We measure timescales of both the l-changing collision and the Rb2 molecule formation of less than one microsecond for n < 100 at the highest BEC densities. We extract a change in kinetic energy of the Rydberg atoms that matches well with the energy gap to the next-lowest manifold. We measure Rb2 signal that decreases with increasing principal quantum number. The mechanism and timescales of the l-changing collision are compared with simulations including the motion of the ionic core and neutral atoms, as well as the Rydberg electron.

  19. Manipulating Rydberg atoms close to surfaces at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Thiele, T.; Filipp, S.; Agner, J. A.; Schmutz, H.; Deiglmayr, J.; Stammeier, M.; Allmendinger, P.; Merkt, F.; Wallraff, A.

    2014-07-01

    Helium atoms in Rydberg states have been manipulated coherently with microwave radiation pulses near a gold surface and near a superconducting NbTiN surface at a temperature of 3K. The experiments were carried out with a skimmed supersonic beam of metastable (1s)1(2s)11S0 helium atoms excited with laser radiation to np Rydberg levels with principal quantum number n between 30 and 40. The separation between the cold surface and the center of the collimated beam is adjustable down to 250?m. Short-lived np Rydberg states were coherently transferred to the long-lived ns state to avoid radiative decay of the Rydberg atoms between the photoexcitation region and the region above the cold surfaces. Further coherent manipulation of the ns Rydberg states with pulsed microwave radiation above the surfaces enabled measurements of stray electric fields and allowed us to study the decoherence of the atomic ensemble. Adsorption of residual gas onto the surfaces and the resulting slow buildup of stray fields was minimized by controlling the temperature of the surface and monitoring the partial pressures of H2O, N2, O2, and CO2 in the experimental chamber during the cool-down procedure. Compensation of the stray electric fields to levels below 100mV /cm was achieved over a region of 6mm along the beam-propagation direction which, for the 1770-m/s beam velocity, implies the possibility to preserve the coherence of the atomic sample for several microseconds above the cold surfaces.

  20. 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.

  1. 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.

  2. Rydberg Atom Lattices

    NASA Astrophysics Data System (ADS)

    van Bijnen, R. M. W.; Vredenbregt, E. J. D.; van Leeuwen, K. A. H.; Kokkelmans, S. J. J. M. F.

    2010-03-01

    Ultracold atomic gases are used extensively to realize textbook examples of condensed matter phenomena. Typically, such experiments deal with neutral atoms interacting via short-range VdW potentials much weaker than the Coulomb interactions between electrons in solids. In contrast, we study highly excited Rydberg atoms arranged on a self-assembled lattice, representing a more accurate dilute model system for e.g. metallic conductors. Here, the interaction strengths approach Coulombic potentials, while retaining the controllability characteristical of cold atom experiments. Rydberg lattices can also cross over to the plasma regime with a quantumdegenerate electron gas by increasing the Rydberg excitation, making such systems a scientific playground for studying various fundamental phenomena. We plan an experimental and theoretical investigation of such self-assembled Rydberg lattices, following a recent proposal by T. Pohl et al. Using a tailored excitation scheme, the correlated crystal state is built up from a disordered atomic gas. We give a theoretical treatment of this scheme and the Rydberg crystal ground states, and discuss its feasibility.

  3. Rotationally resolved photoelectron spectra in resonance enhanced multiphoton ionization of Rydberg states of NH

    SciTech Connect

    Wang, K.; Stephens, J.A.; McKoy, V. ); de Beer, E.; de Lange, C.A.; Westwood, N.P.C. )

    1992-07-01

    Results of combined theoretical and experimental studies of photoelectron spectra resulting from (2+1) resonance enhanced multiphoton ionization (REMPI) via the {ital f} {sup 1}{Pi}(3{ital p}{sigma}), {ital g} {sup 1}{Delta}(3{ital p}{pi}), and {ital h} {sup 1}{Sigma}{sup +}(3{ital p}{pi}) Rydberg states of NH are reported. The overall agreement between these calculated and measured spectra is encouraging. Strong {Delta}{ital N}={ital N}{sup +}{minus}{ital N}{prime}=even peaks, particularly for {Delta}{ital N}=0, are observed in these spectra. Low-energy Cooper minima are predicted to occur in the l=2 wave of the {ital k}{pi}({sup 1}{Sigma}{sup +}), {ital k}{pi}({sup 1}{Sigma}{sup {minus}}), and {ital k}{pi}({sup 1}{Delta}) photoelectron channels for the {ital f} state, the {ital k}{pi}({sup 1}{Delta}), {ital k}{delta}({sup 1}{Pi}), and {ital k}{delta}({sup 1}{Phi}) channels for the {ital g} state, and the {ital k}{pi}({sup 1}{Sigma}{sup +}) and {ital k}{delta}({sup 1}{Pi}) channels for the {ital h} state of NH. Depletion of the {ital d} wave (l=2) contributions to the photoelectron matrix element in the vicinity of these Cooper minima subsequently enhances the relative importance of the odd l waves. The observed {Delta}{ital N} transitions are also affected by strong l mixing in the electronic continuum induced by the nonspherical molecular potential. Interference of continuum waves between degenerate ionization channels also determines the spectral pattern observed for photoionization of the {ital f} {sup 1}{Pi} state of NH. Photoelectron angular distributions and the angular momentum compositions of photoelectron matrix elements provide further insight into the origin of these Cooper minima.

  4. 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.

  5. 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

  6. Structure of the Xe 6s and 6s' Rydberg states in supercritical Ar

    NASA Astrophysics Data System (ADS)

    Li, Luxi; Shi, Xianbo; Evans, C. M.; Findley, G. L.

    2008-05-01

    In this paper, we present new absorption measurements and complete lineshape simulations (including all blue satellite bands) of the Xe 6s and 6s' Rydberg states doped into Ar from low density to the density of the triple point liquid, at both noncritical temperatures and on an isotherm near (+0.5^oC) the critical temperature of Ar. Using these simulations, as well as the known Ar induced shift of the ionization energy of a dopantootnotetextC. M. Evans and G. L. Findley, Phys. Rev. A 72, 022717 (2005)., the Ar induced shift in the Xe 6s and 6s' term energies is determined and is shown to exhibit a large critical point effect. The nature of this critical point effect is discussed. The experimental measurements reported here were performed at the University of Wisconsin Synchrotron Radiation Center (NSF DMR-0537588). This work was supported by grants from the Petroleum Research Fund, from the Professional Staff Congress--City University of New York, and from the Louisiana Board of Regents Support Fund.

  7. A comparison between Stark maps and scaled spectra of highly perturbed Rydberg states in Ba

    NASA Astrophysics Data System (ADS)

    Vasilescu, Camelia; Bates, Kenn; Masae, Jumpei; Schumacher, Douglass

    2001-05-01

    We have studied the Stark effect in Ba Rydberg states, exciting from 6s^2arrow 5d6parrow 6snd, with n near 27. Data showing energy dependent absorption strengths (spectra) were acquired in two different ways. We have measured Stark spectra (electric field F=constant) and scaled energy spectra (\\varepsilon =E/?F=constant). In the latter, the applied electric field and the excitation energy are varied simultaneously. We show that one can obtain a time domain representation by Fourier transforming the Stark spectra and that this representation is similar to the scaled spectra with comparable peak structure. The time domain data have peaks whose location is controlled by Kepler, Stark, and other characteristic times, whereas in the scaled spectra, the peaks are located at the scaled actions of contributing periodic orbits. We also show that, starting from the Stark map, one can obtain scaled energy spectra by interpolating between data taken at different fields strengths. Comparing the scaled spectra obtained by these two methods, we have found resonable agreement. This means, in principle, that past Stark maps of various systems can be converted to scaled spectra without redoing the experiment, depending on the resolution desired.

  8. Calculating helium atomic excited states in coordinate space

    NASA Astrophysics Data System (ADS)

    Hall, Shane; Siegel, P. B.

    2015-12-01

    Two coupled Schrdinger equations are used to calculate excited states of atomic helium. Using product state functions for the two-electron state, the shooting method is used to numerically determine the energies of the allowed singlet and triplet levels. The calculations agree well with the data, and the coordinate-space basis yields Schrdinger equations for helium that are familiar to students who have used similar methods for the hydrogen atom.

  9. Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr.

    PubMed

    Zaouris, Dimitris; Kartakoullis, Andreas; Glodic, Pavle; Samartzis, Peter C; Rafn Hrmarsson, Helgi; Kvaran, gst

    2015-04-28

    Photoexcitation dynamics of the E((1)?(+)) (v' = 0) Rydberg state and the V((1)?(+)) (v') ion-pair vibrational states of HBr are investigated by velocity map imaging (VMI). H(+) photoions, produced through a number of vibrational and rotational levels of the two states were imaged and kinetic energy release (KER) and angular distributions were extracted from the data. In agreement with previous work, we found the photodissociation channels forming H*(n = 2) + Br((2)P3/2)/Br*((2)P1/2) to be dominant. Autoionization pathways leading to H(+) + Br((2)P3/2)/Br*((2)P1/2) via either HBr(+)((2)?3/2) or HBr(+)*((2)?1/2) formation were also present. The analysis of KER and angular distributions and comparison with rotationally and mass resolved resonance enhanced multiphoton ionization (REMPI) spectra revealed the excitation transition mechanisms and characteristics of states involved as well as the involvement of the E-V state interactions and their v' and J' dependence. PMID:25801122

  10. Observation of ultralong-range Rydberg molecules.

    PubMed

    Bendkowsky, Vera; Butscher, Bjrn; Nipper, Johannes; Shaffer, James P; Lw, Robert; Pfau, Tilman

    2009-04-23

    Rydberg atoms have an electron in a state with a very high principal quantum number, and as a result can exhibit unusually long-range interactions. One example is the bonding of two such atoms by multipole forces to form Rydberg-Rydberg molecules with very large internuclear distances. Notably, bonding interactions can also arise from the low-energy scattering of a Rydberg electron with negative scattering length from a ground-state atom. In this case, the scattering-induced attractive interaction binds the ground-state atom to the Rydberg atom at a well-localized position within the Rydberg electron wavefunction and thereby yields giant molecules that can have internuclear separations of several thousand Bohr radii. Here we report the spectroscopic characterization of such exotic molecular states formed by rubidium Rydberg atoms that are in the spherically symmetric s state and have principal quantum numbers, n, between 34 and 40. We find that the spectra of the vibrational ground state and of the first excited state of the Rydberg molecule, the rubidium dimer Rb(5s)-Rb(ns), agree well with simple model predictions. The data allow us to extract the s-wave scattering length for scattering between the Rydberg electron and the ground-state atom, Rb(5s), in the low-energy regime (kinetic energy, <100 meV), and to determine the lifetimes and the polarizabilities of the Rydberg molecules. Given our successful characterization of s-wave bound Rydberg states, we anticipate that p-wave bound states, trimer states and bound states involving a Rydberg electron with large angular momentum-so-called trilobite molecules-will also be realized and directly probed in the near future. PMID:19396141

  11. 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}.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Schtte, Bernd; Arbeiter, Mathias; Fennel, Thomas; Jabbari, Ghazal; Gokhberg, Kirill; Kuleff, Alexander I.; Vrakking, Marc J. J.; Rouze, 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.

  18. Core-Penetrating Rydberg Series of BaF: New Electronic States in the n* ? 4 Region

    NASA Astrophysics Data System (ADS)

    Jakubek, Zygmunt J.; Field, Robert W.

    1996-09-01

    We report results of our studies of the electronic spectrum of the BaF molecule in the energy region of T0= 31 460-32 400 cm -1(3.88 < n* < 4.16). We have observed four new electronic states (all constants in cm -1): K2? 1/2( T0= 31 996), 4.08 2? +( T0= 32 166.293(2), B0= 0.2333892(17)), 3.94 2? ( T1= 32 252.426(2), B1= 0.2294684(16), A1= 0.879(13)), and J2? ( T0= 32 297.918(2), B0= 0.22952165(51), A0= 57.196(1)). In addition, the previously observed G2? +( T0= 30 969.715(2), B0= 0.2297411(13)) and H2? +( T0= 31 606.238(2), B0= 0.23031573(85)) states were rotationally analyzed for the first time. We verified by isotope analysis that the G2? +state, previously reported by J. Singh and H. Mohan [ Indian J. Pure Appl. Phys.11,918-922 (1973)], had been incorrectly assigned vibrationally. The I2? +state, which Singh and Mohan observed at low resolution, was absent from our spectra and we suspect that this state belongs to a species other than BaF. Electronic term values for the remaining seven not yet observed BaF core-penetrating Rydberg states below n* = 6 were predicted by interpolation of well-characterized Rydberg series. We suggest that the E? state, assigned by Effantin et al.as a 2? 1/2state [C. Effantin, A. Bernard, J. D'Incan, E. Andrianavalona, and R. F. Barrow, J. Mol. Spectrosc.145,456-457 (1991)] must be reassigned as a 2? state.

  19. State-to-state dynamics of high-n Rydberg H-atom scattering with H2: inelastic scattering and reactive scattering.

    PubMed

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

    2015-04-21

    The state-to-state dynamics of high-n Rydberg H-atom scattering with para-H2 at the collision energies of 0.45 and 1.07 eV have been studied using the H-atom Rydberg tagging time-of-flight technique. Both the inelastic scattering and reactive scattering are observed in the experimental time-of-flight spectra. The products H2(v', j' = odd) come only from reactive scattering and present clearly forward-backward asymmetric angular distributions, which differ from those of the corresponding ion-molecule reaction. The products H2(v', j' = even), however, come from both reactive scattering and inelastic scattering. Simulating the rotational distribution from reactive scattering, we found that most of the H2(v', j' = even) products come from inelastic scattering. The angular distributions of the product H2(v', j' = even) are consistent with what is predicted by the conventional textbook mechanism of inelastic scattering, and are a little different from those of the corresponding ion-molecule inelastic scattering. These results suggest that the effect of Rydberg electron could not be neglected in describing the differential cross sections of H* + para-H2 scattering. From the simulation, the branching ratios of the inelastic scattering channel were determined to be 66% and 79% at the collision energies of 0.45 and 1.07 eV, respectively. PMID:25162182

  20. Properties of Fr-like Th^3+ from microwave spectroscopy of high-L Rydberg states of Th^2+

    NASA Astrophysics Data System (ADS)

    Keele, Julie; Smith, Chris; Woods, Shannon; Lundeen, Stephen; Fehrenbach, Charles

    2012-06-01

    Spectroscopy of high-L n= 28 Rydberg levels of Th^2+ was recently reported using the optical RESIS method [1]. Because the ground state of Fr-like Th^3+ is a ^2F5/2 level, each (n,L) Rydberg level of Th^2+ is split into six eigenstates whose relative positions are determined by long-range e-Th^3+ interactions. Measurements of those positions can be used to determine the Th^3+ properties that control those interactions, such as polarizabilities and permanent moments. We report a much improved study of n=28 levels with 9 <= L <= 12, obtained with the microwave/RESIS method. The higher precision measurements allow improved determinations of a wider range of Th^3+ properties and a better test of theoretical calculations [2].[4pt] [1] Julie A. Keele, M.E. Hanni, Shannon L. Woods, S.R. Lundeen, and C.W. Fehrenbach, Phys. Rev. A 83, 062501 (2011)[0pt] [2] U.I. Safronova, W.R. Johnson, and M.S. Safronova, Phys. Rev. A 74, 042511 (2006)

  1. Interactions of Rydberg atoms in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Gacesa, Marko; Ct, Robin

    2014-05-01

    Recent developments in ultracold Rydberg gases led to the prediction and discovery of ultra-long-range Rydberg molecules. A Rydberg atom can interact with a ground state atom and form a bound state, the so-called ``trilobite state,'' via an oscillatory Born-Oppenheimer potential arising from Rydberg electron-ground state atom low-energy scattering. Two Rydberg atoms can also be bound via a dispersion potential, and form a ``macrodimer.'' Here we consider two Rydberg atoms immersed in a dilute Bose-Einstein condensate (BEC). The interaction between the two Rydberg atoms is studied, and the formation of a possible ultra-long-range Rydberg molecule is shown. Partially supported by DOE (JW), NSF (MG), and ARO (RC).

  2. 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.

  3. 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

  4. Wireless Network Control of Interacting Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Sanders, Jaron; van Bijnen, Rick; Vredenbregt, Edgar; Kokkelmans, Servaas

    2014-04-01

    We identify a relation between the dynamics of ultracold Rydberg gases in which atoms experience a strong dipole blockade and spontaneous emission, and a stochastic process that models certain wireless random-access networks. We then transfer insights and techniques initially developed for these wireless networks to the realm of Rydberg gases, and explain how the Rydberg gas can be driven into crystal formations using our understanding of wireless networks. Finally, we propose a method to determine Rabi frequencies (laser intensities) such that particles in the Rydberg gas are excited with specified target excitation probabilities, providing control over mixed-state populations.

  5. 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).

  6. 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…

  7. 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

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

    SciTech Connect

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

    1994-10-01

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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Falsaperla, P.; Fonte, G.

    1994-10-01

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

  11. Cs Trilobite Molecules and Rydberg Atom Interactions

    NASA Astrophysics Data System (ADS)

    Booth, Donald; Tallant, Jonathan; Zabawa, Patrick; Parker, Gregory; Shaffer, James

    2013-05-01

    We present results on our Cs ultracold Rydberg atom experiments involving trilobite molecules and Rydberg atom interactions. A novel binding mechanism arises from the attractive, low-energy scattering of a Rydberg electron from a neighboring ground state atom. The states formed by this binding mechanism are referred to as trilobite states. Trilobite molecules are predicted to have giant, body-fixed permanent dipole moments (~ 1 kD). To verify these dipole moments, it is necessary to observe the response to the molecules to an electric field. We present measurements of the Stark shifts of the trilobite states in Cs due to the application of a constant external electric field. We also will present progress on studies of anisotropic Rydberg atom interactions including collision calculations. We will compare and contrast Cs trilobite molecules and Rydberg atom macrodimers. We acknowledge funding from the NSF and the AFOSR.

  12. Rydberg atoms in ultracold plasmas

    NASA Astrophysics Data System (ADS)

    Rolston, Steven

    2009-05-01

    Ultracold plasmas are formed through the photoionization of laser-cooled atoms, or spontaneous ionization of a dense cloud of Rydberg atoms or now molecules[1]. Ultracold plasmas are inherently metastable, as the ions and electrons would be in a lower energy state bound together as atoms. The dominant process of atom formation in these plasmas is three-body recombination, a collision between two electrons and an ion that leads to the formation of a Rydberg atom. This collisional process is not only important in determining the lifetime and density of the plasma, but is also critical in determining the time evolution of the temperature. The formation of the Rydberg atoms is accompanied by an increase in electron energy for the extra electron in the collision, and is a source of heating in these plasmas. Classical three-body recombination theory scales as T-9/2, and thus as a plasma cools due to a process such as adiabatic expansion, recombination-induced heating turns on, limiting the temperature [2]. The Rydberg atoms formed live in the plasma and contribute to the temperature dynamics, as collisions with plasma electrons can change the principal quantum number of the Rydberg atom, driving it to more tightly bound states (a source of plasma heating) or to higher states (a source of plasma cooling). If the plasma is cold and dense enough to be strongly coupled, classical three-body recombination theory breaks down. Recent theoretical work [3] suggests that the rate limits as the plasma gets strongly coupled. I will review the role of Rydberg atoms in ultracold plasmas and prospects for probing Rydberg collisions in the strongly coupled environment. [4pt] [1] J. P. Morrison, et al., Phys. Rev. Lett. 101, 205005 (2008 [0pt] [2] R. S. Fletcher, X. Zhang, and S. L. Rolston, Phys. Rev. Lett. 99, 145001 (2007 [0pt] [3] T. Pohl, private communication.

  13. Coherent polyatomic dynamics studied by femtosecond time-resolved photoelectron spectroscopy: dissociation of vibrationally excited CS2 in the 6s and 4d Rydberg states.

    PubMed

    Knappenberger, Kenneth L; Lerch, Eliza-Beth W; Wen, Patrick; Leone, Stephen R

    2006-11-01

    The dissociation dynamics of the 6s and 4d Rydberg states of carbon disulfide (CS(2)*) are studied by time-resolved photoelectron spectroscopy. The CS(2) is excited by two photons of 267 nm (pump) to the 6s and 4d Rydberg states and probed by ionization with either 800 or 400 nm. The experiments can distinguish and successfully track the time dynamics of both spin [1/2] (upper) and [3/2] (lower) cores of the excited Rydberg states, which are split by 60 meV, by measuring the outgoing electron kinetic energies. Multiple mode vibrational wave packets are created within the Rydberg states and observed through recurrence interferences in the final ion state. Fourier transformation of the temporal response directly reveals the coherent population of several electronic states and vibrational modes. The composition of the wave packet is varied experimentally by tuning the excitation frequency to particular resonances between 264 and 270 nm. The work presented here shows that the decay time of the spin components exhibits sensitivity to the electronic and vibrational states accessed in the pump step. Population of the bending mode results in an excited state lifetime of as little as 530 fs, as compared to a several picosecond lifetime observed for the electronic origin bands. Experiments that probe the neutral state dynamics with 400 nm reveal a possible vibrationally mediated evolution of the wave packet to a different Franck-Condon window as a consequence of Renner-Teller splitting. Upon bending, symmetry lowering from D(infinityh) to C(2v) enables ionization to the CS(2) (+) (B (2)Pi(u)) final state. The dissociation dynamics observed are highly mode specific, as revealed by the frequency and temporal domain analysis of the photoelectron spectra. PMID:17100446

  14. 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.

  15. 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

  16. Towards exciting a Rydberg gas in optical lattices.

    NASA Astrophysics Data System (ADS)

    Manjappa, Manukumara; Han, Jingshan; Guo, Ruixiang; Vogt, Thibault; Li, Wenhui; Quantum Matter Group Team

    2013-05-01

    Rydberg atoms are highly excited atoms with principal quantum number n >10. They have exaggerated properties such as large dipole moment and high polarizability. Large dipole-dipole interactions between Rydberg atoms, which lead to Rydberg blockade and giant non linearity, provide unique opportunities for studying quantum many-body physics. Rydberg excitation of ground state quantum gas in optical lattices has already shown the formation of spatially organized structures and Rydberg dressed systems are promising for entering the strongly correlated regime. Our current project is to study the collective excitation to Rydberg states from a quantum gas of ground state atoms in an optical lattice. In this poster we present the latest development in building up the experimental apparatus and our plans on spectroscopic measurements and spatially imaging of Rydberg excitations. Centre for Quantum Technologies, National University of Singapore.

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

    PubMed

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

    2014-11-20

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

  18. 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.

  19. Two-electron excitation of an interacting cold Rydberg gas.

    PubMed

    Millen, J; Lochead, G; Jones, M P A

    2010-11-19

    We report the creation of an interacting cold Rydberg gas of strontium atoms. We show that the excitation spectrum of the inner valence electron is sensitive to the interactions in the Rydberg gas, even though they are mediated by the outer Rydberg electron. By studying the evolution of this spectrum we observe density-dependent population transfer to a state of higher angular momentum l. We determine the fraction of Rydberg atoms transferred, and identify the dominant transfer mechanism to be l-changing electron-Rydberg collisions associated with the formation of a cold plasma. PMID:21231300

  20. Observation of Rydberg blockade effects at very high n, n ~ 300 , using strontium n1F3 states

    NASA Astrophysics Data System (ADS)

    Zhang, Xinyue; Dunning, F. B.; Yoshida, Shuhei; Burgdrfer, Joachim

    2015-05-01

    Rydberg blockade at very high n, n ~ 300 , is examined using strontium n1F3 Rydberg atoms excited in a small volume defined by two tightly-focused crossed laser beams. Measurements of the number distribution of Rydberg atoms created show deviations from a Poisson distribution revealing sizeable blockade effects. The statistics of the number distribution are studied using a Monte Carlo method in which the interaction between strontium Rydberg atoms is evaluated by solving the Schrdinger equation within a two-active-electron model. The strength of blockade is analyzed in detail with respect to the alignment of two atoms relative to the laser polarizations. With careful control of the experimental parameters the probability for creating one, and only one, Rydberg atom, P(1) , in the excitation volume can be sufficiently large, P(1) > 0 . 6 , as to enable detailed studies of strongly-coupled Rydberg atom pairs. Research supported by the NSF, the Robert A. Welch Foundation, and the FWF (Austria).

  1. Cold and ultracold Rydberg atoms in strong magnetic fields

    NASA Astrophysics Data System (ADS)

    Pohl, T.; Sadeghpour, H. R.; Schmelcher, P.

    2009-12-01

    Cold Rydberg atoms exposed to strong magnetic fields possess unique properties which open the pathway for an intriguing many-body dynamics taking place in Rydberg gases, consisting of either matter or anti-matter systems. We review both the foundations and recent developments of the field in the cold and ultracold regime where trapping and cooling of Rydberg atoms have become possible. Exotic states of moving Rydberg atoms, such as giant dipole states, are discussed in detail, including their formation mechanisms in a strongly magnetized cold plasma. Inhomogeneous field configurations influence the electronic structure of Rydberg atoms, and we describe the utility of corresponding effects for achieving tightly trapped ultracold Rydberg atoms. We review recent work on large, extended cold Rydberg gases in magnetic fields and their formation in strongly magnetized ultracold plasmas through collisional recombination. Implications of these results for current antihydrogen production experiments are pointed out, and techniques for the trapping and cooling of such atoms are investigated.

  2. Spectrum and polarization of helium doubly excited triplet states

    NASA Astrophysics Data System (ADS)

    Brooks, Robert L.; Pinnington, Eric H.

    1980-08-01

    The beam-foil spectrum of helium from 2050 to 3600 has been acquired at 160-keV incident ion energy using a multiple-scan, computerized system. Eleven doubly-excited-state transitions, including two not previously observed, have been assigned, and the agreement between experimental and theoretical energy levels is excellent. The Stokes parameters as a function of foil-tilt angle have been measured for the two strongest transitions (2578 and 3013 ) from 0 to 80 in 10 increments and for two weaker transitions (2562 and 2818 ) at 0, 20, 40, and 60. The polarization patterns are quite different from those of the helium singlets and include the first measurement of negative MI (a Stokes parameter) at 0 foil tilt for helium at this energy. The lifetime of the 2578- transition has been investigated in detail. The present result, 0.109+/-0.004 ns, agrees with previous measurements and yields an upper limit to the autoionization width of the 2p3p 3D levels of 610-6 eV.

  3. 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!

  4. Coherent control of molecular Rydberg wave packets

    NASA Astrophysics Data System (ADS)

    Minns, Russell Stephen

    New experiments and theory contributing to the understanding of the dynamics and control of molecular Rydberg wave packets are presented. An intuitive scheme for controlling the rotational quantum state of a Rydberg molecule is demonstrated experimentally. We determine the accumulated phase difference between the various components of a molecular electron wave packet, and then employ a sequence of phase-locked optical pulses to selectively enhance or depopulate specific rotational states. The angular momentum composition of the resulting wave packet, and the efficiency of the control scheme, is determined by calculating the multipulse response of the time dependent Rydberg populations. The dynamics of predissociating Rydberg electron wavepackets are observed using the optical Ramsey method. The time-resolved spectra are hydrogenic and are very well modeled by assuming that only one p Rydberg series contributes to the dynamics. This is in contrast with previous observations of autoionising Rydberg electron wave packets which show quite dramatic deviations from hydrogenic behaviour above the Born-Oppenheimer limit. The origin of these deviations lies in the interplay between electronic and molecular phase. By exploiting these phases we are able to control the ratio of predissociaton to autoionisation A multichannel quantum defect theory analysis of the Rydberg state of NO is undertaken. The analysis takes into account all the accessible series with / < 3 and all documented interseries interactions. This analysis is the most complete description of NO to date and will aid in the design of future coherent control experiments.

  5. 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

  6. 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

  7. 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.

  8. Millimeter-wave spectroscopy of Zn I in 1D2, 1F3 and 1G4 Rydberg states

    NASA Astrophysics Data System (ADS)

    Kutsenko, A. S.; MacAdam, K. B.; Dyubko, S. F.; Pogrebnyak, N. L.

    2015-12-01

    We have measured the frequencies of 24 transitions between Rydberg singlet L = 24 levels of zinc in the frequency range 79285 GHz. The transitions were driven from 4snf 1F3 levels that were excited by two-step laser excitation through 4s4d 1D2. Single-photon 4snf 1F3 \\to 4s(n + 2)d 1D2, 4snf 1F3 \\to 4s(n + 3)d 1D2, 4snf 1F3 \\to 4s(n + 1)g 1G4, and two-photon 4snf 1F3 \\to 4s(n + 1)f 1F3 series for principal quantum number n = 2840 were observed. Ritz expansion coefficients in the single-channel quantum defect theory were obtained for D, F and G states by least square fitting analysis of the spectra. An estimate of the dipole polarizability of Zn+ has been obtained.

  9. 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.

  10. One-step implementation of the Rydberg-Rydberg-interaction gate

    NASA Astrophysics Data System (ADS)

    Su, Shi-Lei; Liang, Erjun; Zhang, Shou; Wen, Jing-Ji; Sun, Li-Li; Jin, Zhao; Zhu, Ai-Dong

    2016-01-01

    We propose several schemes for implementing a two-qubit quantum phase gate between two Rydberg atoms. The schemes could be realized in one step without adiabatic passage which depends on the specifical shapes and tailored pulse sequences of the laser fields. When the Rydberg-Rydberg-interaction (RRI) strength and the parameters of the driving fields satisfy some certain conditions, the effective Rabi oscillation between the two-excitation Rydberg state and the ground state would be generated, which is out of the Rydberg blockade regime and essential for our scheme. In addition, the individual addressing of the atoms is not required. And the schemes can work under strong or weak RRI strength. The imperfections induced by the variation of RRI strength and spontaneous emission are discussed through solving the master equation numerically.

  11. 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.

  12. 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.

  13. Observations and analysis with the spline-based Rydberg-Klein-Rees approach for the 3(1)?g (+) state of Rb2.

    PubMed

    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

    2016-01-14

    Ro-vibrational term values of the 3(1)?g (+) state of (85,85)Rb2 and (85,87)Rb2 and resolved fluorescence spectra to the A(1)?u (+) 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. PMID:26772572

  14. Observations and analysis with the spline-based Rydberg-Klein-Rees approach for the 3 1 ?g + 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 ?g + state of 85,85Rb2 and 85,87Rb2 and resolved fluorescence spectra to the A 1 ?u + 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.

  15. 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.

  16. Bond angle variations in XH3 [X = N, P, As, Sb, Bi]: the critical role of Rydberg orbitals exposed using a diabatic state model.

    PubMed

    Reimers, Jeffrey R; McKemmish, Laura K; McKenzie, Ross H; Hush, Noel S

    2015-10-14

    Ammonia adopts sp(3) hybridization (HNH bond angle 108) whereas the other members of the XH3 series PH3, AsH3, SbH3, and BiH3 instead prefer octahedral bond angles of 90-93. We use a recently developed general diabatic description for closed-shell chemical reactions, expanded to include Rydberg states, to understand the geometry, spectroscopy and inversion reaction profile of these molecules, fitting its parameters to results from Equation of Motion Coupled-Cluster Singles and Doubles (EOM-CCSD) calculations using large basis sets. Bands observed in the one-photon absorption spectrum of NH3 at 18.3 eV, 30 eV, and 33 eV are reassigned from Rydberg (formally forbidden) double excitations to valence single-excitation resonances. Critical to the analysis is the inclusion of all three electronic states in which two electrons are placed in the lone-pair orbital n and/or the symmetric valence ?* antibonding orbital. An illustrative effective two-state diabatic model is also developed containing just three parameters: the resonance energy driving the high-symmetry planar structure, the reorganization energy opposing it, and HXH bond angle in the absence of resonance. The diabatic orbitals are identified as sp hybrids on X; for the radical cations XH3(+) for which only 2 electronic states and one conical intersection are involved, the principle of orbital following dictates that the bond angle in the absence of resonance is acos(-1/5) = 101.5. The multiple states and associated multiple conical intersection seams controlling the ground-state structure of XH3 renormalize this to acos[3?sin(2)(2(1/2)atan(1/2))/2 - 1/2] = 86.7. Depending on the ratio of the resonance energy to the reorganization energy, equilibrium angles can vary from these limiting values up to 120, and the anomalously large bond angle in NH3 arises because the resonance energy is unexpectedly large. This occurs as the ordering of the lowest Rydberg orbital and the ?* orbital swap, allowing Rydbergization to compresses ?* to significantly increase the resonance energy. Failure of both the traditional and revised versions of the valence-shell electron-pair repulsion (VSEPR) theory to explain the ground-state structures in simple terms is attributed to exclusion of this key physical interaction. PMID:26190514

  17. 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.

  18. Helium P-State Energies and Quantum Defect Analysis

    NASA Astrophysics Data System (ADS)

    Valdez, Travis; Peck, Ryan; Drake, Gordon W. F.

    2015-05-01

    Quantum defects provide a simple and accurate method of extending known atomic energies for low principal quantum number n to higher n up to the series limit, and including the scattering phase shift beyond. We will present new calculations of improved accuracy for the 1 snp1 P and 3 P states of helium up to n = 12 , based on variational calculations in Hylleraas coordinates. The results will be used to determine accurate values for the coefficients in the quantum defect expansion, ? =?0 +?2 /n*2 +?4 /n*4 + ... , where n* = n - ? . We will also test the usual assumption that only the even powers of 1 /n* need be included. In addition, we will study the effectiveness of a unitary transformation in reducing the numerical linear dependence of the basis set for large basis sets. Research supported by the Natural Sciences and Engineering Research Council of Canada.

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

    SciTech Connect

    Schaefer, Martin; Raunhardt, Matthias; Merkt, Frederic

    2010-03-15

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

  20. 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.

  1. Cs Trilobite Molecules and Rydberg atom Interactions

    NASA Astrophysics Data System (ADS)

    Booth, Donald; Jin, Yang; Shaffer, James

    2014-05-01

    We present results on our Cs ultracold Rydberg atom experiments involving trilobite molecules and Rydberg atom interactions. Trilobite molecules are predicted to have giant, body-fixed permanent dipole moments (~ 1 kD). We present measurements of the Stark shifts of the trilobite states in Cs due to the application of a constant external electric field. We also will present progress on studies of anisotropic interactions between pairs of Rydberg atoms. We will focus on angular-dependent S-matrix calculations of collisions between 89D+89D Rydberg atom pairs in a 100 mV/cm electric field. In this field, the dipole-dipole interaction dominates over the van-der-Waals interaction, creating a large anisotropy in the potential surfaces. We acknowledge funding from the NSF and the AFOSR.

  2. 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.

  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 Schrdinger 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. EDITORIAL: Special issue on Rydberg physics

    NASA Astrophysics Data System (ADS)

    Ct, Robin; Pattard, Thomas; Weidemller, 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 fr 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.

  5. Hybridization of Rydberg Electron Orbitals by Molecule Formation

    NASA Astrophysics Data System (ADS)

    Gaj, A.; Krupp, A. T.; Ilzhfer, P.; Lw, R.; Hofferberth, S.; Pfau, T.

    2015-07-01

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

  6. Spectra of atomic sulfur {sup 1}D in transitions to autoionizing Rydberg states in the region of 75 800-89 500 cm{sup -1}

    SciTech Connect

    Pan, W.-C.; Chen, I-C.; Huang, T.-P.; Yuh, J.-Y.; Lee, Y.-Y.

    2008-10-07

    We recorded photoionization spectra of sulfur atoms in transitions from state {sup 1}D in the range of 75 800-89 500 cm{sup -1}. Dissociation of CS{sub 2} after photolysis at 193 nm produced these sulfur atoms in a singlet excited state; they were then ionized with synchrotron radiation (NSRRC, beamline U9CGM) at resolution of up to 3 cm{sup -1} and detected with a quadruple mass filter. Rydberg series 3s{sup 2}3p{sup 3}({sup 2}D{sub 3/2}{sup 0})nd[3/2] and 3s{sup 2}3p{sup 3}({sup 2}D{sub 5/2}{sup 0})ns[5/2] with n extending to 16 and 32, respectively, to limit {sup 2}D{sup 0} are assigned. New Rydberg series 3s{sup 2}3p{sup 3}({sup 2}D{sub 3/2}{sup 0})nd[1/2]{sub 1}, ({sup 2}D{sub 5/2}{sup 0})nd[5/2], and ({sup 2}D{sub 3/2}{sup 0})nd[5/2] with n from 5-9 for the former two series and 7-13 for the latter are assigned. A new Rydberg line at 85 335 cm{sup -1} is assigned to 3s{sup 2}3p{sup 3}({sup 2}D{sub 3/2}{sup 0})6d {sup 1}P.

  7. 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.

  8. Rotational Action Spectroscopy via State-Selective Helium Attachment

    NASA Astrophysics Data System (ADS)

    Kluge, Lars; Stoffels, Alexander; Brnken, Sandra; Asvany, Oskar; Schlemmer, Stephan

    2015-06-01

    Helium atoms can attach to molecular cations via ternary collision processes forming weakly bound (? 1 kcal/mol) He-M^+ complexes. We developed a novel sensitive action spectroscopic scheme for molecular ions based on an observed rotational state dependency of the He attachment process [1]. A detailed account of the underlying kinetics will be presented on the example of the CD^+ ion, where our studies indicate a decrease of around 50% for the rotational state dependent ternary He attachment rate coefficient of the J=1 level with respect to the J=0 level. Experiments are performed on mass-selected ions stored in a temperature-variable (T? 3.9~K) cryogenic rf 22-pole ion trap in the presence of a high number density of He (? 1015 cm-3) [2]. Rotational spectra of the bare ions are recorded by measuring the change in the number of formed He-M^+ complexes after a certain storage time as a function of excitation wavelength. Here we will also present the first measurements of the rotational ground state transitions of CF^+ (J=1-0, hfs resolved) and NH_3D^+ (J_K=1_0-0_0), recorded in this way. [1] Brnken et al., ApJL 783, L4 (2014) [2] Asvany et al., Applied Physics B 114, 203 (2014)

  9. 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.

  10. 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.

  11. DNA translocation measurements in solid-state nanopores fabricated using helium-ion microscope

    NASA Astrophysics Data System (ADS)

    Liu, Liping; Miao, Wang; Huynh, Chuong; Liu, Quanjun; Ling, Xinsheng

    2012-02-01

    We report high-quality DNA translocation measurements in solid-state nanopores drilled in free-standing SiN membranes by using a helium-ion beam in a Zeiss helium-ion microscope (HIM). We show that the HIM nanopores have similar performance as the TEM-drilled pores.

  12. High-order-harmonic generation from Rydberg states at fixed Keldysh parameter

    NASA Astrophysics Data System (ADS)

    Bleda, E. A.; Yavuz, I.; Altun, Z.; Topcu, T.

    2013-10-01

    Because the commonly adopted viewpoint that the Keldysh parameter ? determines the dynamical regime in strong field physics has long been demonstrated to be misleading, one can ask what happens as relevant physical parameters, such as laser intensity and frequency, are varied while ? is kept fixed. We present results from our one- and fully three-dimensional quantum simulations of high-order-harmonic generation (HHG) from various bound states of hydrogen with n up to 40, where the laser intensities and the frequencies are scaled from those for n=1 in order to maintain a fixed Keldysh parameter ?<1 for all n. We find that as we increase n while keeping ? fixed, the position of the cutoff scales in a well-defined manner. Moreover, a secondary plateau forms with a new cutoff, splitting the HHG plateau into two regions. The first of these subplateaus is composed of lower harmonics, and has a higher yield than the second one. The latter extends up to the semiclassical Ip+3.17Up cutoff. We find that this structure is universal, and the HHG spectra look the same for all n?10 when plotted as a function of the scaled harmonic order. We investigate the n, l, and momentum distributions to elucidate the physical mechanism leading to this universal structure.

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

    NASA Astrophysics Data System (ADS)

    Gill, Alexander T.

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

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

    NASA Astrophysics Data System (ADS)

    Koperski, J.; Czajkowski, M.

    2003-09-01

    The lowest E1( 3? +) 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 +( 3? +) and B1( 3? +) states were used as intermediates in the excitation process from the X0 +( 1? +) 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 De'(E1 2)=1309.0 cm -1 and second, separated by a positive PE barrier, with De'(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].

  15. 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

  16. Ultracold chemistry of a single Rydberg atom in a BEC

    NASA Astrophysics Data System (ADS)

    Liebisch, Tara Cubel; Schlagmueller, Michael; Westphal, Karl Magnus; Kleinbach, Kathrin; Hermann, Udo; Nguyen, Huan; Boettcher, Fabian; Loew, Robert; Hofferberth, Sebastian; Pfau, Tilman; Perez-Rios, Jesus; Greene, Chris

    2015-05-01

    A single Rydberg excitation in the high density and low temperature environment of a Bose-Einstein condensate (BEC) leads to a fascinating testbed of low-energy electron-neutral and ion-neutral scattering. For a Rydberg state with a principal quantum number of 100, there are thousands of ground-state atoms with which the Rydberg electron interacts. In a BEC the interparticle spacing is at approximately the same length scale as the Langevin impact parameter, making it possible to study the effect of ion-neutral collisions on time scales much faster than the Rydberg lifetime. Collisions between the Rydberg electron and the ground state atoms cause a mean field density shift of the Rydberg line. We present results on how this effect can be used to monitor phase transitions of the BEC and probe thin density shells of the BEC to monitor density-dependent, ultracold chemical reactions. We report on experimental findings, of Rydberg state-changing collisions on ?s timescales, due to collisions of the Rydberg ionic core with neutral ground state atoms. We compare our findings to simulations based on classical trajectory calculations for the motion of the ionic core and neutral atoms, whereas the dynamics of the electron is treated quantum mechanically.

  17. 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.

  18. 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.

  19. 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.

  20. Trap losses induced by Rydberg dressing of cold atomic gases

    NASA Astrophysics Data System (ADS)

    Aman, J. A.; Desalvo, B. J.; Dunning, F. B.; Killian, T. C.

    2015-05-01

    The near-resonant dressing of ultracold strontium gases and BECs contained in an optical dipole trap (ODT) with the n = 303S1 Rydberg state is investigated as a function of the effective two-photon Rabi frequency, detuning, and dressing time. The measurements demonstrate that, even when well detuned from resonance, such dressing can lead to a rapid decrease in the ground-state atom population in the ODT. This decrease is attributed to Rydberg atom excitation which can lead to direct escape from the trap and/or population of very-long-lived metastable states. The large Rydberg atom production rates are explained using a reaction model in which the initial excitation of a Rydberg atom triggers the excitation of neighboring atoms leading to rapid avalanche-like growth in the Rydberg population. Research supported by the AFOSR, the NSF and the Robert A Welch Foundation.

  1. 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.

  2. 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).

  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. 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.

  5. 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 Schrdinger 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 Schrdinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Reasons for new version: The need to take into account the fact that the negative hydrogen ion ( Z=1) has only one bound (ground) state. Summary of revisions: Minor amendments were made in Cell 2 and Cell 5 of both TwoElAtomSH and TwoElAtomSL programs. Restrictions: Firstly, the too large length of expansion (basis size) takes too much computation time and operative memory giving no perceptible improvement in accuracy. Secondly, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).

  6. 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.

  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 10dB 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. S-states of helium-like ions

    NASA Astrophysics Data System (ADS)

    Liverts, Evgeny Z.; Barnea, Nir

    2011-09-01

    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 (1958, 1959, 1962, 1965, 1971) [1-3] is applied. The basis functions are composed of the Laguerre functions. The method is based on the perimetric coordinates and specific properties of the Laguerre polynomials. Direct solution of the generalized eigenvalues and eigenvectors problem is used, distinct from the Pekeris works. No special subroutines were used, only built-in objects supported by Mathematica. The accuracy of the results and computation times depend on the basis size. The ground state and the lowest triplet state energies can be computed with a precision of 12 and 14 significant figures, respectively. The accuracy of the higher excited states calculations is slightly worse. The resultant wave functions have a simple analytical form, that enables calculation of expectation values for arbitrary physical operators without any difficulties. Only three natural parameters are required in the input. The above Mathematica code is simpler than the earlier version (Liverts and Barnea, 2010 [4]). At the same time, it is faster and more accurate. Program summaryProgram title: TwoElAtomSL(SH) Catalogue identifier: AEHY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 11 434 No. of bytes in distributed program, including test data, etc.: 540 063 Distribution format: tar.gz Programming language: Mathematica 7.0 Computer: Any PC Operating system: Any which supports Mathematica; tested under Microsoft Windows XP and Linux SUSE 11.0 RAM:?10 bytes Classification: 2.1, 2.2, 2.7, 2.9 Nature of problem: The Schrdinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or another physical attributes from quantum mechanical calculations. Solution method: The S-wave function is expanded into a triple set of basis functions which are composed of the exponentials combined with the Laguerre polynomials in the perimetric coordinates. Using specific properties of the Laguerre polynomials, solution of the two-electron Schrdinger equation reduces to solving the generalized eigenvalues and eigenvector problem for the proper Hamiltonian. The unknown exponential parameter is determined by means of minimization of the corresponding eigenvalue (energy). Restrictions: First, the too large length of expansion (basis size) takes the too large computation time and operative memory giving no perceptible improvement in accuracy. Second, the number of shells ? in the wave function expansion enables one to calculate the excited nS-states up to n=?+1 inclusive. Running time: 2-60 minutes (depends on basis size and computer speed).

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Deterministic entanglement of Rydberg ensembles by engineered dissipation

    NASA Astrophysics Data System (ADS)

    Rao, D. D. Bhaktavatsala; Mlmer, Klaus

    2014-12-01

    We propose a scheme that employs dissipation to deterministically generate entanglement in an ensemble of strongly interacting Rydberg atoms. With a combination of microwave driving between different Rydberg levels and a resonant laser coupling to a short-lived atomic state, the ensemble can be driven towards a dark steady state that entangles all atoms. The long-range resonant dipole-dipole interaction between different Rydberg states extends the entanglement beyond the van der Waals interaction range with perspectives for entangling atoms in separate ensembles.

  15. Filtering single atoms from Rydberg-blockaded mesoscopic ensembles

    NASA Astrophysics Data System (ADS)

    Petrosyan, David; Rao, D. D. Bhaktavatsala; Mlmer, 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.

  16. 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.

  17. Bound-state QED calculations for antiprotonic helium

    NASA Astrophysics Data System (ADS)

    Korobov, Vladimir I.; Hilico, Laurent; Karr, Jean-Philippe

    2015-08-01

    We present new theoretical results for the transition energies of the hydrogen isotope molecular ions and antiprotonic helium atoms. Our consideration includes corrections at the m? 7 order in the nonrecoil limit such as the one-loop self-energy, one-loop vacuum polarization, Wichman-Kroll, and complete two-loop contributions. That allowed to get transition energies for the fundamental transition in the hydrogen molecular ion with the relative theoretical uncertainty of 7?10-12 that corresponds to a fractional precision of 1.5?10-11 in determination of the electron-to-proton mass ratio, m p / m e . Correspondingly, for the two-photon transitions in the antiprotonic helium we have 4.7?10-11 as a relative uncertainty for the transition frequency and a fractional precision of 3.6?10-11 for an inferred antiproton-to-electron mass ratio.

  18. Rydberg Excitation of a Single Trapped Ion

    NASA Astrophysics Data System (ADS)

    Feldker, T.; Bachor, P.; Stappel, M.; Kolbe, D.; Gerritsma, R.; Walz, J.; Schmidt-Kaler, F.

    2015-10-01

    We demonstrate excitation of a single trapped cold 40Ca + ion to Rydberg levels by laser radiation in the vacuum ultraviolet at a wavelength of 122 nm. Observed resonances are identified as 3 d 2D3/2 to 51 F , 52 F and 3 d 2D5/2 > to 64 F . We model the line shape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.

  19. Rydberg Excitation of a Single Trapped Ion.

    PubMed

    Feldker, T; Bachor, P; Stappel, M; Kolbe, D; Gerritsma, R; Walz, J; Schmidt-Kaler, F

    2015-10-23

    We demonstrate excitation of a single trapped cold ^{40}Ca^{+} ion to Rydberg levels by laser radiation in the vacuum ultraviolet at a wavelength of 122nm. Observed resonances are identified as 3d^{2}D_{3/2} to 51F, 52F and 3d^{2}D_{5/2} to 64F. We model the line shape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps. PMID:26551109

  20. 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

  1. The 2D Rydberg series in Al I

    NASA Technical Reports Server (NTRS)

    Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1987-01-01

    High quality ab initio electonic structure calculations were performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially high accuracy than currently available values.

  2. The 2D Rydberg series in Al I

    NASA Technical Reports Server (NTRS)

    Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1988-01-01

    High-quality ab initio electronic structure calculations have been performed on the 2D Rydberg series in Al I. The configuration 3s3p2(2D) is shown to contribute substantially to the lowest four 2D Rydberg states. The same configuration also contributes substantially to a 2D state embedded in the ionization continuum. Computed oscillator strengths for the first six members of the 2D Rydberg transitions are given: these should be of substantially higher accuracy than currently available values.

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

    PubMed Central

    Gaj, A.; Krupp, A. T.; Balewski, J. B.; Lw, 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

  4. Quantum-optical nonlinearities induced by Rydberg-Rydberg interactions: A perturbative approach

    NASA Astrophysics Data System (ADS)

    Grankin, A.; Brion, E.; Bimbard, E.; Boddeda, R.; Usmani, I.; Ourjoumtsev, A.; Grangier, P.

    2015-10-01

    In this article, we theoretically study the quantum statistical properties of the light transmitted through or reflected from an optical cavity, filled by an atomic medium with strong optical nonlinearity induced by Rydberg-Rydberg van der Waals interactions. Atoms are driven on a two-photon transition from their ground state to a Rydberg level via an intermediate state by the combination of a weak signal field and a strong control beam. By using a perturbative approach, we get analytic results which remain valid in the regime of weak feeding fields, even when the intermediate state becomes resonant thus generalizing our previous results. We can thus investigate quantitatively new features associated with the resonant behavior of the system. We also propose an effective nonlinear three-boson model of the system which, in addition to leading to the same analytic results as the original problem, sheds light on the physical processes at work in the system.

  5. Dispersive optical nonlinearities using cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Ourjoumtsev, Alexei

    2013-05-01

    We study dispersive optical nonlinearities arising from Rydberg interactions in cold atomic gases. In a resonant, dispersive regime such systems have recently been used as single-photon sources, whereas in the off-resonant, dispersive case they could ultimately allow one to realize two-photon quantum logic gates. We experimentally measure the optical dispersion of a cold atomic cloud inside an optical cavity using a weak probe laser, in presence of a strong control beam driving off-resonant transitions to highly excited Rydberg states. We find that the non-linear response of the system is considerably stronger than for non-interacting atoms, and that the nonlinearity increases with the Rydberg interactions and with the atomic density following the expected scaling laws. We show that this non-linearity can be explained by a ``blockade'' phenomenon, where an excited Rydberg atom prevents the excitation of its neighbors, thereby modifying their optical response. To investigate the behavior of the system in the quantum regime, we show that in the resonant case the cloud acts as ``quantum scissors,'' deterministically transforming a weak coherent excitation in a non-classical state. We find a range of parameters where this state can be efficiently retrieved and characterized in a homodyne measurement.

  6. 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.

  7. 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.

  8. Ultrafast structural dynamics and isomerization in Rydberg-exited Quadricyclane

    SciTech Connect

    Rudakov, Fedor M

    2012-01-01

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

  9. 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}.

  10. 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

  11. 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.; Burgdrfer, J.

    2013-10-01

    The production of very-high-n (n300-500) 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 3105 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.

  12. Electronic structure of the CdKr lowest Rydberg state determined from laser-excitation spectra using supersonic beam and double optical resonance methods

    SciTech Connect

    Koperski, J.; Czajkowski, M.

    2004-04-01

    The lowest E {sup 3}{sigma}{sup +}(6 {sup 3}S{sub 1}) Rydberg state of the CdKr van der Waals complex was investigated using supersonic-expansion beam and the optical-optical double-resonance methods. Well-defined vibrational levels A {sup 3}0{sub v{sup '}}{sub {sup '}}{sub =9}{sup +}({sup 3}{pi}) and B {sup 3}1{sub v{sup '}}{sub {sup '}}{sub =1}{sup +}({sup 3}{sigma}{sup +}) were used as intermediate states being excited from the X {sup 1}0{sup +}({sup 1}{sigma}{sup +}) ground state. Two types of bound-bound excitation spectra of the E {sup 3}{sigma}{sup +}<-A {sup 3}0{sup +} and E {sup 3}{sigma}{sup +}<-B {sup 3}1 transitions were observed and recorded. The analyses of the spectra suggest an existence of two, well-defined minima in the E {sup 3}{sigma}{sup +}-state potential-energy (PE) curve: an inner PE well E{sub 1} with D{sub e}{sup '}(E{sub 1})=1656 cm{sup -1} and an outer well E{sub 2} with D{sub e}{sup '}(E{sub 2})=27 cm{sup -1}, separated from each other by a positive-energy barrier. Combination of bound-bound spectra excited from different intermediate states enabled probing of the E {sup 3}{sigma}{sup +}-state potential in a relatively large range of internuclear separations R and hence it led to a complete determination of spectroscopical parameters of the E {sup 3}{sigma}{sup +}-state PE curve. The height of the barrier and its approximate location were also determined. The experimental results of this investigation coincide well with the results of ab initio calculation of Czuchaj and co-workers [Chem. Phys. 248, 1 (1999); Theor. Chem. Acc. 105, 219 (2001)].

  13. 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.

  14. 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.

  15. Triply-excited auto-dissociating resonant states in the positron-helium system

    NASA Astrophysics Data System (ADS)

    Ho, Y. K.; Ning, Ye; Yan, Z.-C.

    2014-05-01

    An example of triply-excited auto-dissociating resonant states in the positron-helium system is when a positron is bound by the doubly-excited 2s21Se state of the helium atom, in a manner similar to that in the positronium-hydrogen system when a positron is bound to the doubly-excited 2s21Se state of the H- ion. As such states are located in the scattering continua, they would manifest themselves as resonances in positron helium and positronium hydrogen scattering, respectively. In the present work, we have carried out calculations for triply-excited resonances in positron helium scattering. Resonance parameters (both resonance position and width) for some S-wave resonances were obtained by using the method of complex-coordinate rotation, and with employing elaborated Hylleraas-type wave functions in which all six inter-particle coordinates were included (see, for example). For the e+He(2s21Se) and e+He(3s21Se) resonances, a comparison for our results with those in the literature is made. We have also found some new S-wave resonances that have not been reported in the literature, and our recent findings will be presented at the meeting. Supported by NSERC of Canada and NSC of Taiwan.

  16. Extension of the Core-Valence-Rydberg B3LYP Functional to Core-Excited-State Calculations of Third-Row Atoms.

    PubMed

    Nakata, Ayako; Imamura, Yutaka; Nakai, Hiromi

    2007-07-01

    A modified core-valence-Rydberg Becke's three-parameter exchange (B3) + Lee-Yang-Parr (LYP) correlation (CVR-B3LYP) functional is proposed in order to calculate core-excitation energies of third-row atoms with reasonable accuracy. The assessment of conventional exchange-correlation functionals shows that the appropriate portions of Hartree-Fock (HF) exchange for core-excited-state calculations depend on shells:? 70% and 50% for K-shell and L-shell excitations, respectively. Therefore, the modified CVR-B3LYP functional is designed to use the appropriate portions of HF exchange, 70%, 50%, and 20%, for K-shell, L-shell, and valence regions separately. Time-dependent density functional theory calculations with the modified CVR-B3LYP functional yield both K-shell and L-shell excitation energies with reasonable accuracy. The modified CVR-B3LYP also provides valence-excitation energies and standard enthalpies of formation accurately. Thus, the modified CVR-B3LYP describes all of the K-shell, L-shell, and valence electrons appropriately. PMID:26633203

  17. 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

  18. Rydberg atoms in hollow-core photonic crystal fibres.

    PubMed

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

  19. Observation of ultralong range Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Shaffer, James

    2009-05-01

    In 1934, Enrico Fermi described the scattering of a low energy electron from a neutral atom by using the ideas of scattering length and pseudopotential. Although the long range potential for an electron-atom interaction is always attractive, Fermi realized that the s-wave scattering length that characterizes the low energy collision can be either positive or negative. For a positive scattering length, the wavefunction of the electron is shifted away from the atom, the electron is repelled; whereas for a negative scattering length, the wavefunction of the electron is shifted to the atom, the electron is attracted. Based on Fermi's approach, Greene and co-workers predicted a novel molecular binding mechanism where a low energy Rydberg electron is scattered from a ground state atom in the case of negative scattering length. In this situation, the interaction between the electron and ground state atom is attractive and results in the formation of bound states of the ground state atom and the Rydberg atom. Molecules bound by electron scattering can have an internuclear separation of several thousand Bohr radii and are very different from molecules formed by 2 Rydberg atoms where the binding is the result of multipolar forces between the atoms alone. In this talk, we present experimental data on the observation of these exotic molecular states for Rb Rydberg atoms in S states for principal quantum numbers n between 34 and 40. The spectroscopic results for the vibrational ground and first excited state of the dimer Rb(5S)-Rb(nS) are presented and the s-wave scattering length for electron-Rb(5S) scattering in the low energy regime where the kinetic energy is less than 100 meV. Finally, we discuss and present data on the lifetimes and decay mechanisms of these molecules in a magnetic trap.

  20. Optical nanoscopy with excited state saturation at liquid helium temperatures

    NASA Astrophysics Data System (ADS)

    Yang, B.; Trebbia, J.-B.; Baby, R.; Tamarat, Ph.; Lounis, B.

    2015-10-01

    Optical resolution of solid-state single quantum emitters at the nanometre scale is a challenging step towards the control of delocalized states formed by strongly and coherently interacting emitters. We have developed a simple super-resolution optical microscopy method operating at cryogenic temperatures, which is based on optical saturation of the excited state of single fluorescent molecules with a doughnut-shaped beam. Sub-10 nm resolution is achieved with extremely low excitation intensities, a million times lower than those used in room-temperature stimulated emission depletion microscopy. Compared with super-localization approaches, our technique offers a unique opportunity to super-resolve single molecules with overlapping optical resonance frequencies and paves the way to the study of coherent interactions between single emitters and to the manipulation of their degree of entanglement.

  1. Giant Cross Section for Molecular Ion Formation in Ultracold Rydberg Gases

    NASA Astrophysics Data System (ADS)

    Niederprm, Thomas; Thomas, Oliver; Manthey, Torsten; Weber, Tobias M.; Ott, Herwig

    2015-07-01

    We have studied the associative ionization of a Rydberg atom and a ground-state atom in an ultracold Rydberg gas. The measured scattering cross section is 3 orders of magnitude larger than the geometrical size of the produced molecule. This giant enhancement of the reaction kinetics is due to an efficient directed mass transport which is accelerated by the Rydberg electron. We also find that the total inelastic scattering cross section is given by the geometrical size of the Rydberg electron's wave function.

  2. Giant Cross Section for Molecular Ion Formation in Ultracold Rydberg Gases.

    PubMed

    Niederprm, Thomas; Thomas, Oliver; Manthey, Torsten; Weber, Tobias M; Ott, Herwig

    2015-07-01

    We have studied the associative ionization of a Rydberg atom and a ground-state atom in an ultracold Rydberg gas. The measured scattering cross section is 3 orders of magnitude larger than the geometrical size of the produced molecule. This giant enhancement of the reaction kinetics is due to an efficient directed mass transport which is accelerated by the Rydberg electron. We also find that the total inelastic scattering cross section is given by the geometrical size of the Rydberg electron's wave function. PMID:26182095

  3. Some notes on the role of meta-stable excited state of helium atom in laser-induced helium gas breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Ramli, M.; Kagawa, K.; Abdulmadjid, S. N.; Idris, N.; Budi, W. S.; Marpaung, M. A.; Kurniawan, K. H.; Lie, T. J.; Suliyanti, M. M.; Hedwig, R.; Pardede, M.; Lie, Z. S.; Tjia, M. O.

    2007-03-01

    A study of the experimental results on the plasma emissions of water and ethanol vapor samples, induced by Nd:YAG laser in ambient helium and nitrogen gases at atmospheric pressure, is presented here. The result reveals distinct geometrical and spectral characteristics of the plasma emissions generated in the helium gas when compared to those observed from nitrogen gas plasma. Most remarkable is the narrow line width and low continuum background exhibited by emission lines of the analyte atoms from helium plasma, including the hydrogen emission line which is known to suffer from notorious broadening effects in conventional laser induced breakdown spectroscopy (LIBS). It is further shown on the basis of the measured spatial distributions and time profiles of the emission intensities, that the excellent spectral quality is attained by taking advantage of the meta-stable excited state of helium atoms for the delayed excitation of the hydrogen and other analyte atoms, this allows the detection of those atomic emissions to be performed under more favorable conditions. The result of this study has thus demonstrated the feasibility of achieving high-quality spectrochemical analysis, including hydrogen analysis with laser-induced helium gas breakdown spectroscopy.

  4. 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.

  5. Debye equation of state for fluid helium-3.

    PubMed

    Huang, Yonghua; Chen, Guobang; Arp, Vincent

    2006-08-01

    An equation of state for 3He using the Helmholtz potential function has been developed. The lower limit of the equation of 0.01 K is safely above the superfluid transition at 0.0026 K. The upper limit of 60 K is approximately the upper limit of available 3He property measurements. The new state equation form is based on Debye function which goes smoothly to zero in the limit of zero temperature and reduces to the ideal gas in the limit of zero density and/or very high temperature. The equation combines (a) necessary temperature-independent compressibility terms at the lowest temperatures, (b) terms describing the linear specific heat of a Fermi fluid below 1 K, (c) terms describing the phonon excitations which begin above about 1 K, and (d) terms which attempt to fit the conventional critical point thermodynamics at 3.3157 K and 114 604 Pa. State properties, e.g., p-V-T relations, specific heats, thermal expansion, sound velocity, etc., are determined from the Helmholtz energy by standard thermodynamics. Transport properties, e.g., thermal conductivity and viscosity, are not obtained in this work. PMID:16942224

  6. Debye equation of state for fluid helium-3

    SciTech Connect

    Huang Yonghua; Chen Guobang; Arp, Vincent

    2006-08-07

    An equation of state for {sup 3}He using the Helmholtz potential function has been developed. The lower limit of the equation of 0.01 K is safely above the superfluid transition at 0.0026 K. The upper limit of 60 K is approximately the upper limit of available {sup 3}He property measurements. The new state equation form is based on Debye function which goes smoothly to zero in the limit of zero temperature and reduces to the ideal gas in the limit of zero density and/or very high temperature. The equation combines (a) necessary temperature-independent compressibility terms at the lowest temperatures, (b) terms describing the linear specific heat of a Fermi fluid below 1 K, (c) terms describing the phonon excitations which begin above about 1 K, and (d) terms which attempt to fit the conventional critical point thermodynamics at 3.3157 K and 114 604 Pa. State properties, e.g., p-V-T relations, specific heats, thermal expansion, sound velocity, etc., are determined from the Helmholtz energy by standard thermodynamics. Transport properties, e.g., thermal conductivity and viscosity, are not obtained in this work.

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

    SciTech Connect

    Colombo, Anthony P.; Zhou Yan; Prozument, Kirill; Coy, Stephen L.; Field, Robert W.

    2013-01-07

    We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg-Rydberg transitions is that they have enormous electric dipole transition moments ({approx}5 kiloDebye at n*{approx} 40, where n* is the effective principal quantum number), so they interact strongly with the mm-wave radiation. After polarization by a mm-wave pulse in the 70-84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is {approx}100 kHz. Because of the large transition dipole moments, the available mm-wave power is sufficient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, we observe dynamics, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Since the waveform produced by the mm-wave source may be precisely controlled, we can populate states with high angular momentum by a sequence of pulses while recording the results of these manipulations in the time domain. We also probe the superradiant decay of the Rydberg sample using photon echoes. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed.

  8. Chirped-pulse millimeter-wave spectroscopy: spectrum, dynamics, and manipulation of Rydberg-Rydberg transitions.

    PubMed

    Colombo, Anthony P; Zhou, Yan; Prozument, Kirill; Coy, Stephen L; Field, Robert W

    2013-01-01

    We apply the chirped-pulse millimeter-wave (CPmmW) technique to transitions between Rydberg states in calcium atoms. The unique feature of Rydberg-Rydberg transitions is that they have enormous electric dipole transition moments (~5 kiloDebye at n* ~ 40, where n* is the effective principal quantum number), so they interact strongly with the mm-wave radiation. After polarization by a mm-wave pulse in the 70-84 GHz frequency region, the excited transitions re-radiate free induction decay (FID) at their resonant frequencies, and the FID is heterodyne-detected by the CPmmW spectrometer. Data collection and averaging are performed in the time domain. The spectral resolution is ~100 kHz. Because of the large transition dipole moments, the available mm-wave power is sufficient to polarize the entire bandwidth of the spectrometer (12 GHz) in each pulse, and high-resolution survey spectra may be collected. Both absorptive and emissive transitions are observed, and they are distinguished by the phase of their FID relative to that of the excitation pulse. With the combination of the large transition dipole moments and direct monitoring of transitions, we observe dynamics, such as transient nutations from the interference of the excitation pulse with the polarization that it induces in the sample. Since the waveform produced by the mm-wave source may be precisely controlled, we can populate states with high angular momentum by a sequence of pulses while recording the results of these manipulations in the time domain. We also probe the superradiant decay of the Rydberg sample using photon echoes. The application of the CPmmW technique to transitions between Rydberg states of molecules is discussed. PMID:23298035

  9. 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.

  10. Topological matter with collective encoding and Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Nielsen, Anne E. B.; Mlmer, Klaus

    2010-11-01

    We propose to use a permutation symmetric sample of multilevel atoms to simulate the properties of topologically ordered states. The Rydberg blockade interaction is used to prepare states of the sample which are equivalent to resonating valence bond states, Laughlin states, and string-net condensates and to create and study the properties of their quasi-particle-like fundamental excitations.

  11. 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.

  12. 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.

  13. 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.

  14. Quantum entanglement for doubly-excited resonance states of the helium atom

    NASA Astrophysics Data System (ADS)

    Lin, Y.-C.; Fang, T. K.; Ho, Y. K.

    2014-05-01

    It is well known that quantum entanglement is relevant to quantum information, quantum computation, quantum teleportation, and quantum cryptography. In our present work, quantum entanglement for doubly-excited resonance states are quantified by calculating the linear entropy (SL) and von Neumann entropy (SvN) for such states. The linear entropy is defined as SL = 1 - Tr?red2 and the von Neumann entropy as SvN = - Tr?redlog2?red , where ?red is the reduced density matrix, and Tr denotes the trace of the matrix. In our previous works, we calculated the linear entropy for the bound states of the helium atom in free space [1]. Here, we employ the projection operator method [2] to calculate the energies and wave functions of doubly-excited resonance states in the helium atom. Using the projection operators P and Q with P | > = (1 - Q) | > , we can evaluate the eigenvalues of < | QHQ | > =?res < | QQ | > , and such eigenvalues ?res approximate the resonance energies. Once the wave functions for the resonance states are obtained, we can use them to calculate the von Neumann and linear entropies of the doubly-excited resonance states. In the present work, we investigate the 1,3Se ,1,3Po ,1,3De , and 1,3Fo resonance series in the helium atom lying below the He+ (N = 2) threshold. Our results indicate that different series will have different behaviors for their entropies. The detail of our findings will be presented at the meeting. Supported by NSC of Taiwan.

  15. 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.

  16. Rydberg blockade effects at n 300 in strontium

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Dunning, F. B.; Yoshida, S.; Burgdrfer, 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.

  17. 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.

  18. 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.

  19. Cold Rydberg atoms in a CO2 optical dipole trap

    NASA Astrophysics Data System (ADS)

    Gonalves, Luis; Kondo, Jorge; Cabral, Jader; Marcassa, Luis

    2012-06-01

    There has been 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 built an experimental setup to investigate cold Rydberg atom collision in a CO2 optical dipole trap. Briefly, we have loaded a Rb standard magneto-optical trap from an atomic vapor provided by a dispenser. Then we turn on 100W CO2 dipole trap and we apply a loading phase, in which the repumper light intensity is reduced and the trapping frequency is detuned to the red. After this phase, the trapping and repumper laser beams are turned off and we wait 100ms for the atoms, that were not trapped, to fall off the dipole trap region due to gravity. Finally, we turn off the dipole trap and excite the Rydberg state using a two photon transition. The Rydberg atoms are detected using pulsed field ionization technique. During the presentation we shall present preliminary results involving collisions between nD states.

  20. 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.

  1. 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.

  2. 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

  3. (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)

  4. 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.

  5. 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

  6. 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).

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

    PubMed

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

    2011-07-15

    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. PMID:21659692

  8. 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.

  9. Three-body physics. Observation of the Efimov state of the helium trimer.

    PubMed

    Kunitski, Maksim; Zeller, Stefan; Voigtsberger, Jrg; Kalinin, Anton; Schmidt, Lothar Ph H; Schffler, Markus; Czasch, Achim; Schllkopf, Wieland; Grisenti, Robert E; Jahnke, Till; Blume, Drte; Drner, Reinhard

    2015-05-01

    Quantum theory dictates that upon weakening the two-body interaction in a three-body system, an infinite number of three-body bound states of a huge spatial extent emerge just before these three-body states become unbound. Three helium (He) atoms have been predicted to form a molecular system that manifests this peculiarity under natural conditions without artificial tuning of the attraction between particles by an external field. Here we report experimental observation of this long-predicted but experimentally elusive Efimov state of (4)He3 by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away. PMID:25931554

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

    NASA Astrophysics Data System (ADS)

    Shah, Syed Naseem Hussain

    2010-07-01

    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.

  11. 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.

  12. Creation, Control, and Detection of Rydberg Excitations in Ultracold Strontium

    NASA Astrophysics Data System (ADS)

    Whalen, Joseph; Ding, Roger; Camargo, Francisco; Woehl Junior, Germano; Dunning, F. Barry; Killian, Thomas; Rice University Department of Physics; Astronomy / Rice Quantum Institute Team

    2015-05-01

    We benchmark a new apparatus for studying Rydberg physics in ultracold gases by demonstrating the ability to create, control, and detect high-lying excitations. Two-photon transitions via the narrow 5s5p 3Pj intercombination line, unique to alkaline-earth-like atoms, are used to create triplet 5snl Rydberg states with enhanced lifetimes that are inaccessible in alkali systems. These Rydberg excitations have strong, long-range dipolar interactions that can be tuned with principal quantum number and Rydberg fraction. To monitor n and the number of Rydberg atoms created we employ pulsed-field ionization and a microchannel plate detector. This work serves as an important milestone toward realizing many-body phenomena such as roton physics, 3D solitons, supersolidity and long-range spin models. Research supported by the AFOSR under grant no. FA9550-12-1-0267, the NSF under grants nos. 1301773 and 1205946, and the Robert A. Welch Foundation under grant no. C-0734.

  13. 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.

  14. Helium Droplets as Nano-Cryostats for Molecular Spectroscopy: Aggregation, State Selection and Electron Spin Resonance

    NASA Astrophysics Data System (ADS)

    Ernst, Wolfgang E.

    2009-06-01

    Droplets of about 10^{4} helium atoms generated in a supersonic expansion, represent a nanometer-sized superfluid medium of 0.4 K temperature and can be doped with one or several atoms or molecules that may form complexes in this cold environment. Using two-laser excitation schemes, we were able to identify the alkali trimers K_3, Rb_3, K_2Rb and KRb_2 in their lowest quartet states formed on helium droplets loaded with potassium and rubidium atoms and assign several excited states that underlie both Jahn-Teller and spin-orbit coupling. As helium provides a gentle and only weakly perturbing matrix, it appeared desirable to look for ways to measure fine and hyperfine structure directly in the microwave or radiofrequency regime. In preparation for experiments involving optical detection of electron spin transitions in cold molecules, we studied the electronic spin relaxation in alkali atoms and molecules that reside on the surface of a droplet. Measurements of the circular dichroism in the presence of a magnetic field showed that the populations of Zeeman sublevels in alkali atoms are not thermalized, while for dimers and trimers a temperature of 0.4 K was found, implicitly providing a first determination of the droplet's surface temperature. Optical detection of spin resonance is achieved in an optical pump-probe experiment with the electron spin transition induced in a microwave cavity in a magnetic field between the pump and probe regions. With the pump laser depleting a particular spin state by desorption of the species from the droplet beam or by optical pumping, the probe laser detects the successful spin flip induced by the microwave field. Examples will be presented showing up to 50 Rabi cycles of an electron spin transition on an alkali doped helium droplet during the flight time of 57 ?s through the cavity. J. Nagl, G. Aubck, A. W. Hauser, O. Allard, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 100, 063001(2008)} G. Aubck, J. Nagl, C. Callegari, and W. E. Ernst, J. Chem. Phys. 129, 114501(2008). J. Nagl,G. Aubck, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 98, 075301 (2007). G. Aubck, J. Nagl, C. Callegari, and W. E. Ernst, J. Phys. Chem. A 111, 7404(2007). G. Aubck, J. Nagl, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 101, 035301(2008)

  15. Photoassociation of long-range nD Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Raithel, Georg

    2015-05-01

    Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. Of particular interest are a recently discovered class of long-range, homonuclear Rydberg molecules first predicted in and observed in. In rubidium, these molecules are formed via low-energy electron scattering of the Rydberg electron from a 5S1/2 ground-state atom that is present within the Rydberg atom's volume. The binding mostly arises from S-wave and P-wave triplet scattering. In recent work, we have observed long-range homonuclear diatomic nD Rydberg molecules photoassociated out of an ultracold gas of 87Rb atoms for principal quantum numbers 34 <= n <= 40. Related results have also been reported in. The measured ground-state binding energies of 87Rb(nD + 5S1 / 2) molecular states are larger than those of their 87Rb(nS + 5S1 / 2) counterparts, showing the dependence of the molecular bond on the angular momentum of the Rydberg atom. We have exhibited the transition of 87Rb(nD + 5S1 / 2) molecules from a molecular-binding-dominant regime at low n to a fine-structure-dominant regime at high n [akin to Hund's cases (a) and (c), respectively]. In our analysis, we use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom. The hyperfine structure is important because it gives rise to mixed singlet-triplet potentials. This work was supported by the AFOSR (FA9550-10-1-0453) and the NSF (PHY-1205559).

  16. 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

  17. 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.

  18. Ionization of Rydberg atoms by standing-wave light fields.

    PubMed

    Anderson, Sarah E; Raithel, Georg

    2013-01-01

    When electromagnetic radiation induces atomic transitions, the size of the atom is usually much smaller than the wavelength of the radiation, allowing the spatial variation of the radiation field's phase to be neglected in the description of transition rates. Somewhat unexpectedly, this approximation, known as the electric dipole approximation, is still valid for the ionization of micrometre-sized atoms in highly excited Rydberg states by laser light with a wavelength of about the same size. Here we employ a standing-wave laser field as a spatially resolving probe within the volume of a Rydberg atom to show that the photoionization process only occurs near the nucleus, within a volume that is small with respect to both the atom and the laser wavelength. This evidence resolves the apparent inconsistency of the electric dipole approximation's validity for photoionization of Rydberg atoms, and it verifies the theory of light-matter interaction in a limiting case. PMID:24336092

  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. 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.

  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. Microwave control of Rydberg atom interactions

    NASA Astrophysics Data System (ADS)

    Sevinli, S.; Pohl, T.

    2014-12-01

    We investigate the interaction between Rydberg atoms, whose electronic states are dressed by multiple microwave fields. Numerical calculations are used for an exact description of the microwave induced interactions, and employed to benchmark a perturbative treatment that yields simple insights into the involved mechanisms. Based on this theory, we demonstrate that microwave dressing provides a powerful approach to control dipolar as well as van der Waals interactions and even permits us to turn them off entirely. In addition, the proposed scheme also opens up possibilities for engineering dominant three-body interactions.

  3. Entangled optical clocks via Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Komar, Peter; Kessler, Eric; Topcu, Turker; Derevianko, Andrei; Lukin, Mikhail

    2015-05-01

    We present an analysis of a protocol for creating fully entangled GHZ-type states of atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze the realization of this scheme based on neutral Yb atoms.

  4. Trends in autoionization of Rydberg states converging to the 4s threshold in the Kr-Rb{sup +}-Sr{sup 2+} isoelectonic sequence: Theory and experiment

    SciTech Connect

    Neogi, A.; Kennedy, E.T.; Mosnier, J.-P.; Kampen, P. van; Costello, J.T.; O'Sullivan, G.; Mansfield, M.W.D.; Demekhin, Ph.V.; Lagutin, B.M.; Sukhorukov, V.L.

    2003-04-01

    We have measured the photoabsorption spectra of the Kr-like ions Rb{sup +} and Sr{sup 2+} at photon energies corresponding to the excitation of 4s-np resonances using, the dual laser plasma photoabsorption technique. Dramatic changes in the line profiles, with increasing ionization and also proceeding along the Rydberg series of each ion, are observed and explained by the trends in 4s-transition amplitudes computed within a framework of configuration-interaction Pauli-Fock calculations. Total photoionization cross sections show very good agreement with relative absorption data extracted from the measured spectra.

  5. Quantum Spin-Ice and Dimer Models with Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Glaetzle, A. W.; Dalmonte, M.; Nath, R.; Rousochatzakis, I.; Moessner, R.; Zoller, P.

    2014-10-01

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

  6. XUV frequency-comb metrology on the ground state of helium

    SciTech Connect

    Kandula, Dominik Z.; Gohle, Christoph; Pinkert, Tjeerd J.; Ubachs, Wim; Eikema, Kjeld S. E.

    2011-12-15

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

  7. Spectral representation of the three-body Coulomb problem. I. Nonautoionizing doubly excited states of high angular momentum in helium

    NASA Astrophysics Data System (ADS)

    Eiglsperger, Johannes; Piraux, Bernard; Madroero, Javier

    2010-04-01

    We investigate high-lying doubly excited nonautoionizing states of helium with total angular momentum L=1,2,,9 with the help of a configuration interaction approach. We provide highly precise nonrelativistic energies of these states and discuss the properties of the wave functions with respect to the particle exchange operator.

  8. Spectral representation of the three-body Coulomb problem. I. Nonautoionizing doubly excited states of high angular momentum in helium

    SciTech Connect

    Eiglsperger, Johannes; Piraux, Bernard; Madronero, Javier

    2010-04-15

    We investigate high-lying doubly excited nonautoionizing states of helium with total angular momentum L=1,2,...,9 with the help of a configuration interaction approach. We provide highly precise nonrelativistic energies of these states and discuss the properties of the wave functions with respect to the particle exchange operator.

  9. 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

  10. Photoionization rates of Cs Rydberg atoms in a 1064-nm far-off-resonance trap

    SciTech Connect

    Tallant, J.; Booth, D.; Shaffer, J. P.

    2010-12-15

    Experimental measurements of photoionization rates of nD{sub 5/2} Rydberg states of Cs (50{<=}n{<=}75) in a 1064-nm far off-resonance dipole trap are presented. The photoionization rates are obtained by measuring the lifetimes of Rydberg atoms produced inside of a 1064-nm far off-resonance trap and comparing the lifetimes to corresponding control experiments in a magneto-optical trap. Experimental results for the control experiments agree with recent theoretical predictions for Rydberg state lifetimes and measured photoionization rates are in agreement with transition rates calculated from a model potential.

  11. 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.

  12. Structure of heavy helium isotopes via the isobaric analog states in Lithium.

    NASA Astrophysics Data System (ADS)

    Rogachev, G. V.; Aprahamian, A.; Boutachkov, P.; Quinn, M.; Kolata, J. J.; Skorodumov, B.; Woehr, A.; Goldberg, V. Z.; Chubarian, G.; Fomichev, A.; Golovkov, M. S.; Oganessian, Yu. Ts.; Rodin, A.; Slepnev, R. S.; Ter-Akopian, G.; Wolski, R.; Trzaska, W. H.; Aleksandrov, D. V.; Deyoung, P. A.; Peaslee, G. F.; Mears, P. J.; Becchetti, F. D.; Chen, Y.

    2003-10-01

    Study of nuclei far removed from the valley of stability provide an opportunity to test the models of nuclear structure. In particular, heavy isotopes of helium attract much attention due to their extreme neutron to proton ratio. In this work we studied the T=5/2 states in ^9Li and T=3/2 states in ^7Li, isobaric analog states of ^9He and ^7He respectively. Experiment on investigation of T=5/2 states in ^9Li was performed on ACCULINA spectrometer in Dubna, Russia. Excitation function for ^8He+p elastic scattering was measured in the center-of-momentum (cm) energy range from 1.6 to 5.8 MeV. Three T=5/2 states in ^9Li (isobaric analogs of ^9He) were observed. Restrictions on the spin-parity assignments to these states are provided according to R-matrix calculations, and conclusions regarding the structure of ^9He are given. T=3/2 states in ^7Li was populated in interaction of ^6He with protons using the ^6He beam provided by TWINSOL RNB facility at the University of Notre Dame. Neutron decay channel of T=3/2 resonances in ^7Li (n+^6Li(T=1)) was observed in a combination of ?-ray and neutron detectors. Preliminary results of this experiment will be reported.

  13. Spectroscopic observation of resonant electric dipole-dipole interactions between cold Rydberg atoms.

    PubMed

    Afrousheh, K; Bohlouli-Zanjani, P; Vagale, D; Mugford, A; Fedorov, M; Martin, J D D

    2004-12-01

    Resonant electric dipole-dipole interactions between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled 85Rb atoms in a magneto-optical trap were optically excited to 45d(5/2) Rydberg states using a pulsed laser. A microwave pulse transferred a fraction of these Rydberg atoms to the 46p(3/2) state. A second microwave pulse then drove atoms in the 45d(5/2) state to the 46d(5/2) state, and was used as a probe of interatomic interactions. The spectral width of this two-photon probe transition was found to depend on the presence of the 46p(3/2) atoms, and is due to the resonant electric dipole-dipole interaction between 45d(5/2) and 46p(3/2) Rydberg atoms. PMID:15601153

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Efficient detection of 2^3S1m=0 states of atomic helium for improved precision measurements of helium 2^3P fine structure

    NASA Astrophysics Data System (ADS)

    Kato, K.; Beica, H.; Davidson, E. B.; Fitzakerley, D. W.; George, M. C.; Storry, C. H.; Vutha, A. C.; Weel, M.; Hessels, E. A.

    2012-06-01

    Thermal helium 2^3S metastable atoms can be detected with near unit efficiency by the electron ejected when they strike a stainless-steel surface. However, the 2^1S atoms and UV photons created in generating the metastable beam also produce ejected electrons. We remove the 2^1S atoms from our beam using 2.06-micron photons from a dc discharge lamp to drive the 2^1S atoms to the 2^1P state (which subsequently decays to the ground state). A Stern-Gerlach magnet removes the m=-1 and m=+1 2^3S atoms. Elastic collisions with argon gas scatters the 2^3S atoms out of the initial beam path, and thus away from the direction of the UV photons. The combination of these elements allows for high-efficiency detection of 2^3S1 m=0 atoms with very low background due to singlet atoms, UV photons or 2^3S1 m=1 atoms, allowing for an improved signal-to-noise ratio for precision helium fine-structure measurements.

  19. Properties of Rn-like Th^4+ from microwave spectroscopy of high-L n=37 Rydberg states of Th^3+

    NASA Astrophysics Data System (ADS)

    Smith, Chris; Keele, Julie; Lundeen, Stephen; Fehrenbach, Charles

    2012-06-01

    A recent microwave/RESIS study of n=37 Rydberg levels of Th^3+ led to the first measurements of dipole and quadrupole polarizabilities of Rn-like Th^4+ [1]. We report additional measurements that extend the data pattern to include the L=8 level and improve the precision of the L = 14 and L = 15 levels. Together these new measurements allow improved determinations of both polarizabilities and a more precise test of theoretical calculations [2].[4pt] [1] Julie A. Keele, S.R. Lundeen, and C.W. Fehrenbach, Phys. Rev. A 83, 062509 (2011)[0pt] [2] U.I Safronova and M.S. Safronova, Phys. Rev. A 84, 052515 (2011)

  20. 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.

  1. 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.

  2. Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy

    NASA Astrophysics Data System (ADS)

    Eyler, E. E.; Chieda, D. E.; Stowe, M. C.; Thorpe, M. J.; Schibli, T. R.; Ye, J.

    2008-06-01

    We analyze several possibilities for precisely measuring electronic transitions in atomic helium by the direct use of phase-stabilized femtosecond frequency combs. Because the comb is self-calibrating and can be shifted into the ultraviolet spectral region via harmonic generation, it offers the prospect of greatly improved accuracy for UV and far-UV transitions. To take advantage of this accuracy an ultracold helium sample is needed. For measurements of the triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap metastable 23S state atoms. We analyze schemes for measuring the two-photon 23S ?43S interval, and for resonant two-photon excitation to high Rydberg states, 23S ?33P ?n3S, D. We also analyze experiments on the singlet-state spectrum. To accomplish this we propose schemes for producing and trapping ultracold helium in the 11S or 21S state via intercombination transitions. A particularly intriguing scenario is the possibility of measuring the 11S ?21S transition with extremely high accuracy by use of two-photon excitation in a magic wavelength trap that operates identically for both states. We predict a triple magic wavelength at 412 nm that could facilitate numerous experiments on trapped helium atoms, because here the polarizabilities of the 11S, 21S and 23S states are all similar, small, and positive.

  3. 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.

  4. 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.

  5. 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).

  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 Magnetism and Topological Ordering via Rydberg Dressing near Frster 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 Frster-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

  8. 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

  9. 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.

  10. Double Excitations of Helium

    NASA Astrophysics Data System (ADS)

    Menzel, Alexander

    1996-05-01

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

  11. 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.

  12. 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.

  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. 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).

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

    NASA Astrophysics Data System (ADS)

    Gonzlez-Frez, 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. 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.

  17. 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.

  18. Auger transition rates for metastable states of antiprotonic helium He{sup +}{bar p}

    SciTech Connect

    Korobov, V.I.; Shimamura, I.

    1997-12-01

    The rates of Auger transitions of antiprotonic helium {sup 4}He{sup +}{bar p} and {sup 3}He{sup +}{bar p} are calculated by using a variational scattering method with an elaborate three-body trial function. The shift of the energy levels of these systems due to the coupling with the Auger-decay channels is also obtained from this calculation. Thus an improvement is made over the previously calculated nonrelativistic energies. Together with the relativistic corrections calculated elsewhere, the theoretical transition wavelength between the states (n,l)=(37,34) and (38,33) of {sup 4}He{sup +}{bar p}, for example, is significantly improved to be 713.593 nm, which compares well with the experimental value 713.578{plus_minus}0.006 nm. The calculated Auger lifetime of the level (38,33) is 3.2 ps, as compared with the value 4.1{plus_minus}0.2 ps deduced from the measured line broadening. Auger rates are calculated also using Fermi{close_quote}s golden-rule formula with a regular Coulomb function with no phase shift for the Auger electron. The results agree fairly well with the accurate variational results. {copyright} {ital 1997} {ital The American Physical Society}

  19. 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.

  20. 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.

  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. Photoinitiated collisions between cold Cs Rydberg atoms

    SciTech Connect

    Overstreet, K. Richard; Schwettmann, Arne; Tallant, Jonathan; Shaffer, James P.

    2007-07-15

    Experimental studies of a photoinitiated collision in an ultracold Cs Rydberg gas are presented. The process is characterized by measuring the laser intensity dependence of the absorption, the number of particles leaving each collision, and the recoil velocity of the collision fragments. The results of the experiment are compared to ab initio Rydberg pair interaction potentials.

  4. 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.

  5. 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.

  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. 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.

  9. 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.

  10. 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)

  11. M1 decay of the 2 sup 3 S sub 1 state of helium-like bromine

    SciTech Connect

    Dunford, R.W.; Liu, C.J.; Berry, H.G.; Raphaelian, M.L.A. ); Church, D.A. ); Hass, M. ); Curtis, L.J. )

    1990-01-01

    We have measured the lifetime of the 2 {sup 3}S{sub 1} level in helium-like bromine with the results {tau}{sup exp}(2 {sup 3}S{sub 1}) = 224.1 (7.1) ps, in agreement with theory. Our error is dominated by uncertainties in the correction for the effects of cascades from highly excited states. 7 refs., 1 fig.

  12. Spectral representation of the three-body Coulomb problem. II. Autoionizing doubly excited states of unnatural parity in helium

    NASA Astrophysics Data System (ADS)

    Eiglsperger, Johannes; Piraux, Bernard; Madroero, Javier

    2010-04-01

    A spectral approach of configuration interaction type is used to evaluate energies and widths for a wide range of singlet and triplet Pe resonance states of helium up to the eighth single ionization threshold. While the present data are in excellent agreement with existing theoretical results (below the N=3-5 ionization threshold) obtained within an explicitly correlated approach, there are substantial differences with the energies, the widths, and the number of resonances obtained with the stabilization method.

  13. Spectral representation of the three-body Coulomb problem. II. Autoionizing doubly excited states of unnatural parity in helium

    SciTech Connect

    Eiglsperger, Johannes; Piraux, Bernard; Madronero, Javier

    2010-04-15

    A spectral approach of configuration interaction type is used to evaluate energies and widths for a wide range of singlet and triplet P{sup e} resonance states of helium up to the eighth single ionization threshold. While the present data are in excellent agreement with existing theoretical results (below the N=3-5 ionization threshold) obtained within an explicitly correlated approach, there are substantial differences with the energies, the widths, and the number of resonances obtained with the stabilization method.

  14. 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.

  15. Many- and Few-Body Physics with Rydberg Polaritons in an Optical Resonator

    NASA Astrophysics Data System (ADS)

    Sommer, Ariel; Simon, Jonathan

    2014-05-01

    Under conditions of electromagnetically induced transparency (EIT) with a Rydberg state, photons propagate as Rydberg polaritons-superpositions of a photon and a Rydberg excitation. We are building an experiment to study Rydberg polaritons in an optical cavity. In a near-degenerate cavity, the manifold of cavity modes provides a transverse kinetic energy and trapping potential. In this configuration, long range interactions between Rydberg polaritons give access to the crystal to superfluid phase transition. Meanwhile, working with a single or a few cavity modes yields the Rydberg blockade as a source of non-classical light, as well as few-body physics with hopping between cavity modes. The use of a high-finesse optical cavity leads to strong atom-photon coupling, protecting the polaritons from decoherence under the action of external forces and collisions. Because the kinetic energy derives from the photons, gauge fields can be introduced by engineering the cavity modes. We describe the physics of this novel system, and provide an update on the experimental progress. We acknowledge support from the AFOSR and DARPA.

  16. HELIUM-3 Enhancements and Unusual Ion Charge State Composition in Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Ho, George Cho-Wah

    Using data from the MASS high-resolution solar wind spectrometer on the WIND spacecraft, six enhanced 3He2+/4He2+ periods were found from 1995 to 1998. The enhancements vary from a factor of five to almost a hundred times higher than average values previously reported. All enhanced 3He2+ periods were associated with the passage of CME-ejecta. The observed time periods were either within but towards the end of the CME-associated magnetic clouds or trailing the magnetic cloud by about 24 hours. Four of six events have enhanced overall densities (>30 cm-3) as well as enhanced 3He2+ abundances. All enhanced 3He2+ periods have a mixture of low (cold) iron charge states along with high (hot) oxygen charge states. Two periods have singly charged helium present with 4He+/4He2+ ratios of 1.0 0.5% and 12 6%. In addition, during one of these two periods we observed C2+, N2+, and O2+ for the first time in the solar wind. The unusual charge state composition of these enhanced 3He2+ events suggest the plasma came from a relatively cold and dense solar region. In addition one of our enhanced 3He2+ events has optical observations from SoHO to suggest it came from the prominence core within a partial halo CME. We suggest that the enhanced 3He2+ plasma in all six of our events originated from the prominence core embedded within the CME as observed from spaceborne coronagraphs. Different fractionation theories that might explain the 3He2+ enhancement will be discussed. In addition, ionic and elemental abundances were determined in -one magnetic clouds. Four of these magnetic clouds were associated with the four 3He2+-enhanced events. In general, charge states of carbon, nitrogen and oxygen indicate that the twenty-one magnetic clouds contain 'hotter' plasma than that found in the typical slow speed solar wind. Elemental abundances of other minor ions indicate that the 'FIP effect', in which the abundances of elements with low first ionization potentials is enhanced, was operating in magnetic clouds.

  17. 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.

  18. 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.

  19. 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

  20. New Theoretical Developments in Exploring Electronically Excited States: Including Localized Configuration Interaction Singles and Application to Large Helium Clusters

    NASA Astrophysics Data System (ADS)

    Closser, Kristina Danielle

    This thesis presents new developments in excited state electronic structure theory. Contrasted with the ground state, the electronically excited states of atoms and molecules often are unstable and have short lifetimes, exhibit a greater diversity of character and are generally less well understood. The very unusual excited states of helium clusters motivated much of this work. These clusters consist of large numbers of atoms (experimentally 103--109 atoms) and bands of nearly degenerate excited states. For an isolated atom the lowest energy excitation energies are from 1s ? 2s and 1s ? 2 p transitions, and in clusters describing the lowest energy band minimally requires four states per atom. In the ground state the clusters are weakly bound by van der Waals interactions, however in the excited state they can form well-defined covalent bonds. The computational cost of quantum chemical calculations rapidly becomes prohibitive as the size of the systems increase. Standard excited-state methods such as configuration interaction singles (CIS) and time-dependent density functional theory (TD-DFT) can be used with ?100 atoms, and are optimized to treat only a few states. Thus, one of our primary aims is to develop a method which can treat these large systems with large numbers of nearly degenerate excited states. Additionally, excited states are generally formed far from their equilibrium structures. Vertical excitations from the ground state induce dynamics in the excited states. Thus, another focus of this work is to explore the results of these forces and the fate of the excited states. Very little was known about helium cluster excited states when this work began, thus we first investigated the excitations in small helium clusters consisting of 7 or 25 atoms using CIS. The character of these excited states was determined using attachment/detachment density analysis and we found that in the n = 2 manifold the excitations could generally be interpreted as superpositions of atomic states with surface states appearing close to the atomic excitation energies and interior states being blue shifted by up to ?2 eV. The dynamics resulting from excitation of He_7 were subsequently explored using ab initio molecular dynamics (AIMD). These simulations were performed with classical adiabatic dynamics coupled to a new state-following algorithm on CIS potential energy surfaces. Most clusters were found to completely dissociate and resulted in a single excited atomic state (90%), however, some trajectories formed bound, He*2 (3%), and a few yielded excited trimers (<0.5%). Comparisons were made with available experimental information on much larger clusters. Various applications of this state following algorithm are also presented. In addition to AIMD, these include excited-state geometry optimization and minimal energy path finding via the growing string method. When using state following we demonstrate that more physical results can be obtained with AIMD calculations. Also, the optimized geometries of three excited states of cytosine, two of which were not found without state following, and the minimal energy path between the lowest two singlet excited states of protonated formaldimine are offered as example applications. Finally, to address large clusters, a local variation of CIS was developed. This method exploits the properties of absolutely localized molecular orbitals (ALMOs) to limit the total number of excitations to scaling only linearly with cluster size, which results in formal scaling with the third power of the system size. The derivation of the equations and design of the algorithm are discussed in detail, and computational timings as well as a pilot application to the size dependence of the helium cluster spectrum are presented.

  1. Minerals Yearbook 1989: Helium

    SciTech Connect

    Leachman, W.D.

    1989-01-01

    Grade-A helium (99.995% or better) sales volume in the United States by private industry and the Bureau of Mines was 2,083 million cubic feet (MMcf) in 1989. Grade-A helium exports by private producers were 796 MMcf, for total sales of 2,879 MMcf of U.S. helium. The price of Grade-A helium, f.o.b. plant, was about $37.50 per thousand cubic feet (Mcf) for both the Bureau and private industry. The Bureau price for bulk liquid helium was $45.00 per Mcf with additional costs for container services and rent. The liquid helium price for private industry was also about $45.00 per Mcf with some producers posting surcharges to the price.

  2. 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).

  3. Calculation of the wave functions of the ground and weakly excited states of helium II

    SciTech Connect

    Tomchenko, M. D.

    2006-01-15

    The wave functions of the ground ({psi}{sub 0}) and the first excited ({psi}{sub k}) states of He II in the second-order approximation, i.e., up to the first two corrections to the corresponding solutions for a weakly nonideal Bose gas, are determined by the collective variable method, which was proposed by Bogolyubov and Zubarev and developed in the studies by Yukhnovskii and Vakarchuk. The functions {psi}{sub 0} and {psi}{sub k} = {psi}{sub k}{psi}{sub 0} are determined as the eigenfunctions of the N-particle Schroedinger equation from a system of coupled equations for {psi}{sub 0}, {psi}{sub k}, and the quasiparticle spectrum E(k) of helium II. The results consist in the following: (1) these equations are solved numerically for a higher order approximation compared with those investigated earlier (the first-order approximation), and (2) {psi}{sub 0} and {psi}{sub k} are derived from a model potential of interaction between He{sup 4} atoms (rather than from the structure factor as earlier) in which the potential barrier is joined with the attractive potential found from experiment. The height V{sub 0} of the potential barrier is a free parameter. Except for V{sub 0}, the model does not have any free parameters or functions. The calculated values of the structure factor, the ground-state energy E{sub 0}, and the quasiparticle spectrum E(k) of He II are in agreement with the experimental values for V{sub 0} {approx} 100 K. The second-order correction to the logarithm of {psi}{sub 0} significantly affects the value of E{sub 0} and provides the asymptotics E(k {sup {yields}} 0) = ck, while the second-order correction to {psi}{sub k} slightly affects the E(k). The second-order corrections to {psi}{sub 0} and {psi}{sub k} have a smaller effect on the results compared with the first-order corrections, whereby the theory is in agreement with experiment; therefore, one may assume that the truncated {psi}{sub 0} and {psi}{sub k} well describe the microstructure of He II. Thus, the series for {psi}{sub 0} and {psi}{sub k} can be truncated in spite of the fact that the expansion parameter is not very small ({approx}1/2)

  4. 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)

  5. 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.

  6. Strongly Correlated Gases of Rydberg-Dressed Atoms: Quantum and Classical Dynamics

    SciTech Connect

    Pupillo, G.; Micheli, A.; Zoller, P.; Boninsegni, M.; Lesanovsky, I.

    2010-06-04

    We discuss techniques to generate long-range interactions in a gas of ground state alkali atoms, by weakly admixing excited Rydberg states with laser light. This provides a tool to engineer strongly correlated phases with reduced decoherence from inelastic collisions and spontaneous emission. As an illustration, we discuss the quantum phases of dressed atoms with dipole-dipole interactions confined in a harmonic potential, as relevant to experiments. We show that residual spontaneous emission from the Rydberg state acts as a heating mechanism, leading to a quantum-classical crossover.

  7. 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.

  8. Heating and cooling of an ultra-cold neutral plasma by Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Tate, Duncan; Crockett, Ethan; Newell, Ryan

    2015-05-01

    We have experimentally demonstrated a mechanism for controlling the expansion rate of an ultra-cold neutral plasma (UNP) so that it is different from the value determined by the photo-ionizing laser frequency. We achieved this by adding Rydberg atoms to the UNP 10-20 ns after its creation. Specifically, we added nd5 / 2 state atoms with n = 24- 60 to UNPs with initial electron temperatures, Te , 0, in the range 10-250 K. The evidence is both indirect, from the change in the electron evaporation rate from the UNP, and direct, from the change in the asymptotic plasma expansion velocity, v0, measured using the time-of-flight spectrum of Rb+ ions. In addition, the results strongly support the existence of a ``bottleneck'' in the state distribution of Rydberg atoms formed by three body recombination (TBR) where the binding energy of the bottleneck state is Eb ~ 2 . 3 kBTe , 0 . Finally, we show that the amount of heating or cooling is linear in the number density of Rydberg atoms added to the UNP for small Rydberg densities, but saturates at higher densities to a value that is determined solely by the Rydberg binding energy. These results are in good general agreement with Monte-Carlo calculations. Funded by NSF and Colby College.

  9. Rydberg spectroscopy of a Rb MOT in the presence of applied or ion created electric fields.

    PubMed

    Viteau, M; Radogostowicz, J; Bason, M G; Malossi, N; Ciampini, D; Morsch, O; Arimondo, E

    2011-03-28

    Rydberg spectroscopy of rubidium cold atoms trapped in a magneto-optical trap (MOT) was performed in a quartz cell. When electric fields acting on the atoms generated by a plate external to the cell were continuously applied, electric charges on the cell walls were created, as monitored on the Rydberg spectra. Avoiding accumulation of the charges and realizing good control over the applied electric field was instead obtained when the fields were applied only for a short time, typically a few microseconds. In a two-photon excitation via the 62P state to the Rydberg state, the laser resonant with the 52S-62P transition photoionizes the excited state. The photoionization-created ions produce an internal electric field which deforms the excitation spectra, as monitored on the Autler-Townes absorption spectra. PMID:21451625

  10. Dynamical processes in Rydberg-Stark deceleration and trapping of atoms and molecules.

    PubMed

    Seiler, Christian; Hogan, Stephen D; Merkt, Frdric

    2012-01-01

    The interaction between inhomogeneous electric fields and the large electric dipole moments of atoms and molecules in Rydberg states of high principal quantum number can be used to efficiently accelerate and decelerate atoms and molecules in the gas phase. We describe here how hydrogen atoms and molecules initially moving with velocities of ?600 m/s in supersonic beams can be decelerated to zero velocity and loaded into electric traps. The long observation times that are made possible by the electrostatic trapping enables one to study slow relaxation processes. Experiments are presented in which we have observed photoionization processes and transitions between Rydberg states induced by blackbody radiation at temperatures between 10 K and 300 K on a time scale of several milliseconds. Comparison of these processes in Rydberg states of H and H(2) suggests the importance, in H(2), of collisional processes and of the process of blackbody-radiation-induced predissociation. PMID:22613151

  11. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    NASA Astrophysics Data System (ADS)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. From classical to quantum non-equilibrium dynamics of Rydberg excitations in optical lattices

    NASA Astrophysics Data System (ADS)

    Mattioli, Marco; Gltzle, Alexander W.; Lechner, Wolfgang

    2015-11-01

    The glass phase and its quantum analog are prominent challenges of current non-equilibrium statistical mechanics and condensed matter physics. As a model system to study the transition from classical to quantum glassy dynamics, we propose a setup of laser driven three-level atoms trapped in an optical lattice. Tuning the strength of the laser driving to the intermediate level allows one to study the transition from a classical kinetically constrained model to the coherent regime. For strong driving, Rydberg excitations evolve analogously to defects in the one-spin facilitated model, a minimal model known to exhibit glassy dynamics. In our setup, the constraints result from the interplay between Rydberg interactions and the laser detuning from the Rydberg state. The emerging heterogeneous relaxation timescales are tuneable over several orders of magnitudes. In the opposite limit of weak driving of the intermediate level, we find an effective cluster model which describes the dynamics in a reduced subspace of the allowed number and positions of Rydberg excitations. This subspace is uniquely determined by the initial state and is characterized by a fixed number of clusters of Rydberg excitations. In addition, we investigate the influence of random fields on the classical relaxation. We find that the glassy dynamics can relax faster in the presence of weak random fields.

  17. 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.

  18. 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.

  19. Experimental investigations of the resonant dipole-dipole interaction between cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Browaeys, Antoine

    2015-05-01

    This talk will present our on-going effort to control the dipole-dipole interaction between cold Rydberg atoms. In our experiment, we trap individual atoms in two-dimensional arrays of optical tweezers separated by few micrometers and excite them to Rydberg states using lasers. The arrays are produced by a spatial light modulator, which shapes the dipole trap beam. We can create almost arbitrary geometries of the arrays. We have measured the van der Waals interaction between two individual atoms, and show efficient Rydberg blockade in arrays of three atoms. We have also demonstrated the control of the interaction between atoms with microwave and DC electric fields. We observe in particular the coherent energy exchange between two atoms resulting from their dipole-dipole interaction. This control of the interaction will find applications in quantum state engineering, quantum information and quantum simulation.

  20. 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 ?m from the wire, the displacement during the Rydberg lifetime (e.g. n = 35, ? = 30 ?s) will be 200-300 ?m 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).

  1. 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.

  2. Bound States of One-Dimensional Helium Atom by Discretization of Space and Time

    NASA Astrophysics Data System (ADS)

    Weatherford, Charles

    2001-05-01

    The computational theory for calculation of the solution of the time-dependent Schrdinger equation for two electrons [C.A. Weatherford, Computational Chemistry: Reviews of Current Trends, Vol. 5, ed. J. Leszczynski, World Scientific 2000] is reviewed and adapted to the case of the one-dimensional helium atom. This results in a new computational time-dependent exchange/correlation theory. A solution algorithm which discretizes space using a spectral discrete variable basis of synthetic cartesian polynomials, and discretizes time using a spectral element discrete variable basis of Chebyshev polynomials, is presented. Supported by NSF CREST grant HRD-9707076, and by NASA grant NAG5-10148.

  3. Shell Model Calculations of the D-State Admixture in the Ground-State Wave Functions of Tritium, HELIUM-3, and HELIUM-4 Using Various Realistic Potentials

    NASA Astrophysics Data System (ADS)

    Chiang, Pi-Chih

    Several different theoretical methods have been developed to investigate the ground-state properties of ^3H, ^3He, and ^4He nuclei. Previously, the properties of these nuclei have been investigated using variational and hyperspherical methods. However, the Faddeev method, which yields essentially exact results has been used for A = 3 and the coupled-cluster method for mass 4. The error inherent in the hyperspherical method is not known, so the development of alternative method may be useful. In this work we have developed a set of effective operators to be used in the shell-model calculations. The m-scheme shell-model method is used in a systematic study of the binding energy and D-state probability obtained for the ground state of ^3H, ^3He, and ^4He nuclei using a variety of realistic nucleon-nucleon potentials. Since the main contribution to the binding energy comes from the ^1S_0 and ^3S_1 -^3D_1 nucleon -nucleon channels, and the main contribution to the D-state probability comes from the ^3S _1-^3D_1 tensor interaction, we will include only these channels in our calculations. Furthermore, this restriction will allow us to compare our results with the Faddeev five -channel calculations in coordinate space for ^3 H and ^3He. For the trinucleon calculations, we find that our results are in substantial agreement with those of Faddeev calculations. The difference between our results and those of Faddeev calculations is found to be between -0.38 MeV and 0.19 MeV for the triton binding energy and between -0.6% and 0.0% for the triton ground-state D-state probability. For the mass 4 calculations, we compare our results with the published results of hyperspherical, variational, and coupled-cluster calculations. The agreement between this work and that of the URBANA group (48) and Goldhammer (51) is excellent for the binding energy calculations. Our systematic study shows the binding energy (without the static Coulomb contribution) of the alpha particle to be between 24.5 and 26.8 MeV for modern realistic two-body potentials (PARIS, URBANA, ARGONNE V_{14 }, and BONN-OBEPR). Further, we find the D -state probability to lie between 10 and 15% while previously published reports suggest 5% and 13%.

  4. 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.

  5. Ultralong-range Rydberg Molecules: Investigation of a Novel Binding Mechanism

    NASA Astrophysics Data System (ADS)

    Butscher, Bjrn; Bendkowsky, Vera; Nipper, Johannes; Balewski, Jonathan; Shaffer, James P.; Lw, Robert; Pfau, Tilman

    2010-03-01

    For highly excited Rydberg atoms, the scattering of the Rydberg electron from a nearby polarizable ground state atom can generate an attractive mean-field potential which is able to bind the ground state atom to the Rydberg atom within the Rydberg electron wave function at binding energies ranging from a few MHz to hundreds of MHz[1]. We present spectroscopic data on the observation of various bound states including the vibrational ground and excited states of rubidium dimers Rb(5S)-Rb(nS) as well as those of trimer states. Furthermore, we show calculations that reproduce the observed binding energies remarkably well and reveal that some of the excited states are purely bound by quantum reflection at a shape resonance for p-wave scattering [2]. To further characterize the coherent excitation of the molecular states, we performed echo experiments. [0pt] [1] V. Bendkowsky, B. Butscher, J. Nipper, J. P. Shaffer, R. Lw, T. Pfau, Nature 458, 1005 (2009); [2] V. Bendkowsky, B. Butscher, J. Nipper, J. Balewski, J. P. Shaffer, R. Lw, T. Pfau, W. Li, J. Stanojevic, T. Pohl,and J. M. Rost, arXiv:0912.4058 (2009)

  6. Rydberg bands in the near UV spectra of substituted pyrroles

    NASA Astrophysics Data System (ADS)

    Nyulszi, 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 ? orbital were found, terminating at 3 s, 3 p and 3 p', 3 d Rydberg orbitals.

  7. 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.

  8. 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 .

  9. 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.

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

    SciTech Connect

    Mudrich, M.; Heister, Ph.; Hippler, T.; Giese, Ch.; Stienkemeier, F.; Dulieu, O.

    2009-10-15

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

  11. 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.

  12. 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.

  13. 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 ^3?_u^+ state in supersonic beams with velocities tunable down to 100 m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator. The 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. Krhenmann, M. Schfer, 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).

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Opto-nanomechanics strongly coupled to a Rydberg superatom: coherent versus incoherent dynamics

    NASA Astrophysics Data System (ADS)

    Carmele, Alexander; Vogell, Berit; Stannigel, Kai; Zoller, Peter

    2014-06-01

    We propose a hybrid optomechanical quantum system consisting of a moving membrane strongly coupled to an ensemble of N atoms with a Rydberg state. Due to the strong van-der-Waals interaction between the atoms, the ensemble forms an effective two-level system, a Rydberg superatom, with a collectively enhanced atom-light coupling. Using this superatom imposed collective enhancement strong coupling between membrane and superatom is feasible for parameters within the range of current experiments. The quantum interface to couple the membrane and the superatom can be a pumped single mode cavity, or a laser field in free space, where the Rydberg superatom and the membrane are spatially separated. In addition to the coherent dynamics, we study in detail the impact of the typical dissipation processes, in particular the radiative decay as a source for incoherent superpositions of atomic excitations. We identify the conditions to suppress these incoherent dynamics and thereby a parameter regime for strong coupling. The Rydberg superatom in this hybrid system serves as a toolbox for the nanomechanical resonator allowing for a wide range of applications such as state transfer, sympathetic cooling and non-classical state preparation. As an illustration, we show that a thermally occupied membrane can be prepared in a non-classical state without the necessity of ground state cooling.

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

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

  2. Spectrum of plasma containing Ne- and Na-like ions: consistent account for Rydberg and autoionizing Rydberg series in balance equations

    NASA Astrophysics Data System (ADS)

    Ivanov, L. N.; Ivanova, E. P.; Knight, L. V.; Molchanov, A. G.

    1996-06-01

    This is a theoretical study of argon plasma under conditions, where Ne- and Na-like ionization stages are dominant. Balance equations are generalized to treat 37 3l states of Ne-like ion and 37 adjacent series of Rydberg states of Na-like ion simultaneously. This allows us to include in the kinetics a diffusion-like motion of the state of the system "Ne-like ion plus one electron" through the multitude of excited levels spread over an energy region of 50 eV. The populations Ni - i (i = (1, ..., 37)) of the Ne-like ion states are introduced explicitly; those of adjacent 37 Rydberg series are accounted for through continuous functions Ni(?). These functions describe the population distribution within each Rydberg series dependent on the Rydberg electron enegy ?. The elementary processes of the collisionalradiative model connecting all Ne- and Na-like states, as well as processes of redistribution of populations inside each Rydberg series, are accounted for. The rate coefficients for all processes within the Ne-like residue have been calculated previously, using a detailed many-body relativistic theory. The dielectric capture cross sections and autoionization probabilities are presented as analytical continuation of the collisional excitation cross sections. The excited-excited states transitions are included. The rest of the processes are treated in a simple semiclassical approximation. The Lotz formula is generalized by unambiguous analytical continuation to cover the case of bound-bound transitions between Rydberg states of Na-like ions. The radiation reabsorption in a long plasma cylinder is included through Biberman-Holstein coefficients for all transitions. The inclusion of Na-like states, accounting for diffusion-like processes, increases the population inversion for the "lasing candidates" by at least a factor of two for a wide range of plasma conditions. This is important for the ionization equilibrium too. Besides, the functions Ni(?) bear diagnostic information. Detailed calculations have been done for the homogeneous steady-state Maxwellian plasma. The role of transient processes in the population inversion creation is under discussion.

  3. 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.

  4. Transient localization in the kicked Rydberg atom

    NASA Astrophysics Data System (ADS)

    Persson, Emil; Frthauer, S.; Wimberger, S.; Burgdrfer, J.

    2006-11-01

    We investigate the long-time limit of quantum localization of the kicked Rydberg atom. The kicked Rydberg atom is shown to possess in addition to the quantum localization time ?L a second crossover time tD where quantum dynamics diverges from classical dynamics towards increased instability. The quantum localization is shown to vanish as either the strength of the kicks at fixed principal quantum number or the quantum number at fixed kick strength increases. The survival probability as a function of frequency in the transient localization regime ?L

  5. Interacting Fibonacci anyons in a Rydberg gas

    NASA Astrophysics Data System (ADS)

    Lesanovsky, Igor; Katsura, Hosho

    2012-10-01

    The physics of interacting Fibonacci anyons can be studied with strongly interacting Rydberg atoms in a lattice, when due to the dipole blockade the simultaneous laser excitation of adjacent atoms is forbidden. The Hilbert space maps then directly on the fusion space of Fibonacci anyons. Interactions between anyons are generated and controlled by the intensity and frequency of the excitation laser. Fusion outcomes of neighboring anyons can be determined experimentally via the measurement of three-point correlations among three consecutive atoms. Our work shows that a Rydberg lattice gas constitutes a natural physical platform for the experimental exploration of topological quantum liquids of non-Abelian anyons.

  6. 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.

  7. Merging of positions of zeros in dipole and quadrupole matrix elements of photoeffect from outer-shell and Rydberg states of high-Z elements

    SciTech Connect

    Wang, M.S.; Pratt, R.H.

    1984-01-01

    The zeros in dipole and quadrupole matrix elements of photoeffect from the ns/sub 1/2/ subshells of uranium approach common positions as n..-->..infinity. This is an illustration of the more general feature that for sufficiently large n/sub 0/ photoeffect cross sections and angular distributions from nJL subshells, aside from the bound-state normalization factor which scales the cross section, are the same for all n>n/sub 0/ (J,L fixed) except for energies very close to threshold. This behavior can be expected for all subshells and all elements and for all multipole matrix elements.

  8. 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.

  9. 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.

  10. Measuring the hydrogen Balmer series and Rydbergs constant with a homemade spectrophotometer

    NASA Astrophysics Data System (ADS)

    Onorato, P.; Malgieri, M.; De Ambrosis, A.

    2015-09-01

    In a recent paper (Amrani 2014 Eur. J. Phys. 35 045001), the author presented two different methods to measure the wavelength of visible lines of Balmer series from the hydrogen atomic spectrum and estimate the value of Rydbergs constant with an error difference of a few tenths of a per cent. Here we discuss how low cost spectrometers, based on the use of either transmission or reflection diffraction gratings coupled with a commercial digital camera, can be employed with the same aim. The Rydbergs constant values obtained with our spectrometers are R = 1.096 0.007 107 m-1 for the transmission grating spectrometer and R = 1.094 0.005 107 m-1 for the reflection spectrometer, with a difference of less than 0.30% from the accepted value of 1.097 373 107 m-1.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Modeling a ``Snap-shot'' of Cold Rydberg Atoms in the Field of a Charged Wire

    NASA Astrophysics Data System (ADS)

    Goodsell, Anne; Nawarat, Poomirat; Harper, Colleen

    2014-05-01

    We propose to cool a cloud of Rb atoms and to launch the cloud at 12 m/s toward a charge suspended wire with a cylindrically-symmetric electric field. The cloud expands slightly as it moves upward and will be illuminated by excitation light to promote these atoms into the desired Rydberg state (30S) in mid-flight. This requires de-tuning the excitation laser from the zero-field n = 30 transition to excite atoms in a region where the field causes a significant shift of the Rydberg energy levels (if the wire is charged to +10 V, the field is less than 1 / 3n5 a.u., without mixing Stark-shifted states yet). Immediately after excitation, the Rydberg atoms are located in a ring around the wire. Later studies will probe the dynamics of this ring of excited slow-moving atoms. As a method of detection, we model the effect of pulsing the wire potential to ionize the atoms. A ramp time of roughly 0.2 ?s for increasing the wire potential will ``freeze'' the motion of the slow atoms; for example, a speed of 12 m/s corresponds to a distance of 2.4 ?m traveled during this ramp time. This ``snap-shot'' technique may be used later to study the dynamics of Rydberg atoms around a charged wire, like previous experiments with ground-state atoms.

  18. 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}}.

  19. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  1. 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.

  2. 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.

  3. 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.

  4. Rydberg transitions in Be-like Si XI

    SciTech Connect

    Serpa, F.G.; Livingston, A.E.; Kukla, K. ); Galvez, E.J. )

    1993-06-05

    Measurements of [Delta][ital n]=1 Rydberg transition wavelengths for Be-like Si XI are presented for 1[ital s][sup 2]2[ital s]9[ital l][prime][l arrow]1[ital s][sup 2]2[ital s]10[ital l] and 1[ital s][sup 2]2[ital s]8[ital l][prime][l arrow]1[ital s][sup 2]2[ital s]9[ital l]. The large polarizability of the open core 1[ital s][sup 2]2[ital s] and configuration interaction with nearby 1[ital s][sup 2]2[ital pnl] states yield observable 1-structure that is compared with the polarization model, Multi Configurational Dirac-Fock (MCDF) and Many Body Perturbation Theory (MBPT) calculations. We discussed the high-1 structure of the [ital n]=9--10 transition previously in relation to plasma observations. The first application of MBPT calculations to Be-like Rydberg states was reported with our measurement of the 7[ital I]--8[ital K] transition in S XIII.

  5. 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 ?+/?- 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 ?s with error probability on the order of 10-3.

  6. 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

  7. 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.

  8. 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.

  9. 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}.

  10. Population coherent control of Rydberg potassium atom via adiabatic passage

    NASA Astrophysics Data System (ADS)

    Jiang, Li-Juan; Zhang, Xian-Zhou; Jia, Guang-Rui; Zhang, Yong-Hui; Xia, Li-Hua

    2013-02-01

    The time-dependent multilevel approach (TDMA) and B-spline expansion technique are used to study the coherent population transfer between the quantum states of a potassium atom by a single frequency-chirped microwave pulse. The Rydberg potassium atom energy levels of n = 6-15, l = 0-5 states in zero field are calculated and the results are in good agreement with other theoretical values. The time evolutions of the population transfer of the six states from n = 70 to n = 75 in different microwave fields are obtained. The results show that the coherent control of the population transfer from the lower states to the higher ones can be accomplished by optimizing the microwave pulse parameters.

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

    NASA Astrophysics Data System (ADS)

    Traxler, Mallory A.

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

  12. 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.

  13. Autodissociating Rydberg states of positronium hydride

    NASA Technical Reports Server (NTRS)

    Drachman, R. J.

    1979-01-01

    Consequences of the nonrelativistic Coulomb Hamiltonian with a fixed proton are considered for positronium hydride (PsH). An optical-potential method and certain simplifying assumptions are used to compute the lowest s-wave resonance parameters on the basis of the /e(+)H(-)/ configuration. Resonance parameters corresponding to a Ps scattering energy of 4.0190 eV and a width of 0.0303 eV are obtained. These results are shown to be in very close agreement with those of previous studies.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Quantification of the effects of Rydberg atoms on ultra-cold neutral plasma evolution

    NASA Astrophysics Data System (ADS)

    Tate, Duncan; Crockett, Ethan; Newell, Ryan

    2014-05-01

    We describe recent developments in our ongoing research in which Rydberg atoms are embedded into an ultra-cold neutral plasma (UNP). Atoms in a specific Rydberg state are embedded in the UNP within 10 ns of its creation using a second pulsed laser system. In such an environment, it is predicted that the plasma electrons may be heated or cooled by the Rydberg atoms (see, for example). We identified an experimental signature that correlates with the plasma electron temperature change, namely, the ``crossover'' between heating and cooling, where the UNP lifetime remains the same when Rydbergs are added. More recently, we have been working on quantifying the amount of heating or cooling that can be achieved using a passive technique. Specifically, we measure the time (t?) it takes for the UNP to shed a certain fraction of its electrons (?) as it expands in a small, externally applied, electric field. The work reported in shows that the quantity t?- 1 is a good proxy for the UNP asymptotic expansion velocity, which in turn depends on Te , 0. Research supported by Colby College and NSF.

  19. 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.

  20. a Study of Final State Effects in the Electrodisintegration of a Polarized HELIUM-3 Target

    NASA Astrophysics Data System (ADS)

    Kievsky, A.; Pace, E.; Salm, G.

    2005-02-01

    An approach for the description of the final state interaction in the evaluation of inclusive electromagnetic responses of a polarized 3He target, is briefly illustrated. Preliminary results of calculations, where the final state interaction is fully taken into account for the two-body break-up channel, are compared with experimental data, showing a very encouraging improvement with respect to the plane wave impulse approximation results.

  1. Theoretical state-selective and total cross sections for electron capture from helium atoms by fully stripped ions

    NASA Astrophysics Data System (ADS)

    Man?ev, I.; Milojevi?, N.; Belki?, D.

    2015-03-01

    The four-body boundary-corrected first Born (CB1-4B) approximation is used to compute cross sections for single electron capture from helium targets by fully stripped ions. The projectile ions are H+, He2+, Li3+, Be4+, B5+, C6+, N7+, O8+, and F9+. An extensive list of theoretical state-to-state cross sections in these collisions at energies ranging from 20 to 10 000 keV/amu is given. This list includes the state-selective cross sections Qnlm for each individual triple of the usual quantum numbers { n , l , m } of the final hydrogen-like states alongside Qnl and Qn for the pertinent sub-shells and shells where the respective summations over m and { l , m } have been carried out. The maximal value of the principal quantum number n was chosen to vary from 4 (H+) to 10 (F9+) so as to satisfy the condition n ?ZP, where ZP is the nuclear charge of the projectile. Usually, the largest cross sections stem from those values of n that match the projectile charge (n =ZP) . The total cross sections for capture summed over all the quantum numbers { n , l , m } are also tabulated. The overall goal of this study is to fill in lacunae in the existing databases of charge exchange cross sections that are needed in several inter-disciplinary fields. For example, in particle transport physics, which is of utmost importance in such emerging branches as hadron therapy, these cross sections constitute a part of the multifaceted input data for stochastic simulations of energy losses of multiply charged ions in matter, including tissue. Other significant uses of the present data are anticipated in charge exchange diagnostics within thermonuclear research project as well as in applications covering the relevant parts of plasma physics and astrophysics.

  2. 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}.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. Crystalline structures and frustration in a two-component Rydberg gas

    NASA Astrophysics Data System (ADS)

    Levi, Emanuele; Min?, Ji?; Garrahan, Juan P.; Lesanovsky, Igor

    2015-12-01

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

  16. Polarizabilities of two-electron positive ions and Rydberg levels of lithium

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Second-order sums are computed for the two-electron positive ions Li(+), Be(2+), and B(3+) by representing the intermediate states as discrete pseudostates. The Hamiltonian for the system is given and translated to semi-Jacobi variables for its derivation in reduced Rydberg units. The interaction potential is developed in its multipole form and employed in second-order perturbation theory. The perturbation is always a multipole-potential term, and the initial and intermediate states are constructed from two-particle Hylleraas basis sets. The resulting pseudostates are shown to represent the continuum with good convergence, and the asymptotic-optical-potential method is applied to the two-body quantities to determine the energy levels of three-electron systems in high Rydberg states. The method is shown to give accurate values for the polarizabilities of the two-electron isoelectronic systems.

  17. 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

  18. 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

  19. Monte Carlo Studies of the HELIUM-4 Ground State and Liquids in Porous Media.

    NASA Astrophysics Data System (ADS)

    Macfarland, Thomas Joseph

    1995-01-01

    This thesis presents the results of two Monte Carlo simulations. The first is a study of the ground state of solid and liquid ^4He, using a shadow wavefunction. A new form of trial shadow wavefunction is introduced to describe this system. Monte Carlo integration was used to optimize the parameters of this function, and a thorough analysis of the shadow description of the system has been carried out. This shows improved pair correlations, an improved condensate fraction, substantially reduced variational energies and a good equation of state. The melting and freezing transition densities are found to be in good agreement with the exact results of Green's Function Monte Carlo (GFMC). A second shadow wavefunction is introduced in which a basis set expansion is used to optimize the two particle correlations. This shadow wavefunction yields pair correlation functions in excellent agreement with GFMC, as well as a substantial reduction in the variational energies at all densities. In the second part of this work, static critical phenomena of a 3D Ising model confined in a porous medium made by spinodal decomposition have been studied using large-scale Monte-Carlo simulations. The work explores the influence of the geometry of Vycor-like materials on liquid/vapor coexistence and the species separation of binary liquid mixtures. No surface lnteractions (preference of the Vycor-like material for one phase above the other) are taken into account. It was found that the critical temperature depends on the average pore size D as T _{c}(D) = T_{c }(infty) - c/D . The universality class of the phase transition is independent of the pore size, and the critical exponents obtained from our simulation data are upsilon = 0.8 +/- 0.1, gamma = 1.4 +/- 0.1, beta = 0.65 +/- 0.13. No divergence is observed in the specific heat, strongly suggesting that alpha <= 0. All data for all pore sizes can be collapsed well with the scaling function for the magnetic susceptibility chi L^{-gamma/ nu} = ~chi((T - T_{c}(D)/T_{c}(D))L ^{1/ nu}). These critical phenomena are consistent with those computed for the randomly diluted Ising model. Experimental realizations of the numerical experiments are discussed. To speed up the simulation of the Ising model in the porous medium, three parallel algorithms for simulating that model were introduced and implemented on the KSR-1 parallel computer. These are the parallel Metropolis algorithm, the parallel Swensen-Wang algorithm and the Parallel Local Cluster Algorithm. The parallel speedup that was obtained with each algorithm is presented, and the results discussed.

  20. 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.

  1. Correlated Exciton Transport in Rydberg-Dressed-Atom Spin Chains.

    PubMed

    Schempp, H; Gnter, G; Wster, S; Weidemller, M; Whitlock, S

    2015-08-28

    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. PMID:26371647

  2. Suppression of multiphoton intrashell resonances in Li Rydberg atoms

    SciTech Connect

    Waheed, A.; Fregenal, D.; Frette, O.; Foerre, M.; Hjertaker, B. T.; Preclikova, J.; Horsdal, E.; Pilskog, I.

    2011-06-15

    Multiphoton intrashell transitions in strongly driven Li (n=25) Rydberg atoms are studied experimentally. Orthogonal dc electric and magnetic fields lift the degeneracy of the n shell and define the eccentricity e of the initial coherent elliptic states, which are formed by laser excitation and subsequent adiabatic transformation. The intrashell transitions are driven by a time-harmonic electric field linearly polarized parallel to the major axis of the ellipse. N-photon resonances with N=1-9 are studied as a function of e. All resonances with N{>=}3 are suppressed at certain e values in between 0 and 1. A similar system was analyzed by Yabuzaki et al. [Phys. Rev. A 10, 1955 (1974)] who found a simple pattern of suppressions that applies also for the present experiments. The results of these experimentally confirm that each time N is increased by two, an additional suppression is observed.

  3. Imaging single Rydberg electrons in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Karpiuk, Tomasz; Brewczyk, Miros?aw; Rz??ewski, Kazimierz; Gaj, Anita; Balewski, Jonathan B.; Krupp, Alexander T.; Schlagmller, Michael; Lw, Robert; Hofferberth, Sebastian; Pfau, Tilman

    2015-05-01

    The quantum mechanical states of electrons in atoms and molecules are distinct orbitals, which are fundamental for our understanding of atoms, molecules and solids. Electronic orbitals determine a wide range of basic atomic properties, allowing also for the explanation of many chemical processes. Here, we propose a novel technique to optically image the shape of electron orbitals of neutral atoms using electron-phonon coupling in a Bose-Einstein condensate. To validate our model we carefully analyze the impact of a single Rydberg electron onto a condensate and compare the results to experimental data. Our scheme requires only well-established experimental techniques that are readily available and allows for the direct capture of textbook-like spatial images of single electronic orbitals in a single shot experiment.

  4. Symmetry and symmetry breaking in Rydberg-atom intrashell dynamics

    SciTech Connect

    Pilskog, I.; Fregenal, D.; Frette, O.; Foerre, M.; Horsdal, E.; Waheed, A.

    2011-04-15

    We have investigated experimentally and theoretically the dynamics of Stark-Zeeman split states in Li(n=25) Rydberg atoms when they are exposed to a superposition of a slowly varying field and a harmonic RF field. Regular oscillatory structures are observed in the intrashell transitions. By solving the time-dependent Schroedinger equation for the problem it is shown that the dynamics is strongly influenced by the nonhydrogenic core which breaks the dynamical symmetry of the Coulomb problem. It is also shown that the dynamics effectively reduces to that of a two-level atom. The oscillations are remnants of interferences that arise partly due to a phase difference which develops between the two levels when they go through two consecutive one-photon resonances, and partly due to an effective change of the carrier-envelope phase of the coupling field.

  5. Symmetry and symmetry breaking in Rydberg-atom intrashell dynamics

    NASA Astrophysics Data System (ADS)

    Pilskog, I.; Fregenal, D.; Frette, .; Frre, M.; Horsdal, E.; Waheed, A.

    2011-04-01

    We have investigated experimentally and theoretically the dynamics of Stark-Zeeman split states in Li(n=25) Rydberg atoms when they are exposed to a superposition of a slowly varying field and a harmonic RF field. Regular oscillatory structures are observed in the intrashell transitions. By solving the time-dependent Schrdinger equation for the problem it is shown that the dynamics is strongly influenced by the nonhydrogenic core which breaks the dynamical symmetry of the Coulomb problem. It is also shown that the dynamics effectively reduces to that of a two-level atom. The oscillations are remnants of interferences that arise partly due to a phase difference which develops between the two levels when they go through two consecutive one-photon resonances, and partly due to an effective change of the carrier-envelope phase of the coupling field.

  6. 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

  7. 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.

  8. Electric Field Effects in the Excitation of Cold Rydberg-Atom Pairs

    SciTech Connect

    Nascimento, V. A.; Caliri, L. L.; Marcassa, L. G.; Schwettmann, A.; Shaffer, J. P.

    2009-05-29

    In this work, we study the role of the ac Stark effects on the excitation of nS{sub 1/2} cold Rydberg atoms produced in a rubidium magneto-optical trap. We have observed an atomic population in the nP{sub 3/2} state after excitation of nS{sub 1/2} for 29{<=}n{<=}37. Such an observation is normally attributed to binary collisions; however, the interaction between Rb nS{sub 1/2} atoms is repulsive. To explain our results, the dipole-dipole interaction and ac Stark shifts from the excitation laser must be considered. We find that the Rydberg-atom-pair state asymptotically correlating to nP{sub 3/2}+(n-1)P{sub 3/2} is excited directly.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  11. MHz few-body frequency shift detected in a cold {sup 85}Rb Rydberg gas

    SciTech Connect

    Han Jianing

    2011-11-15

    We have observed a density-dependent frequency shift of more than 4 MHz in a cold {sup 85}Rb Rydberg gas trapped in a magneto-optical trap. A one-dimensional linearly aligned four-body model is proposed to explain the experimental data, and the calculation matches the experimental data. The calculation also shows that if the energy detuning between the two coupled states, the nsnsns(n+1)s and nsnsnpnp states in this case, is small, the lowest level of the nsnsnpnp manifold has the maximum mixing probability, causing a frequency shift instead of line broadening. The results reported may be used for few-body blockade, Rydberg single-atom imaging, studying few-body to many-body transitions and interactions, and few-body ionization as well as quantum metrology.

  12. 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.

  13. Rydberg Electrons in a Bose-Einstein Condensate.

    PubMed

    Wang, Jia; Gacesa, Marko; Ct, R

    2015-06-19

    We investigate a hybrid system composed of ultracold Rydberg atoms immersed in an atomic Bose-Einstein condensate (BEC). The coupling between Rydberg electrons and BEC atoms leads to excitations of phonons, the exchange of which induces a Yukawa interaction between Rydberg atoms. Because of the small electron mass, the effective charge associated with this quasiparticle-mediated interaction can be large. Its range, equal to the BEC healing length, is tunable using Feshbach resonances to adjust the scattering length between BEC atoms. We find that for small healing lengths, the distortion of the BEC can "image" the Rydberg electron wave function, while for large healing lengths the induced attractive Yukawa potentials between Rydberg atoms are strong enough to bind them. PMID:26196974

  14. Observation of a Rydberg Series in H{sup +}H{sup -}: A Heavy Bohr Atom

    SciTech Connect

    Vieitez, M. O.; Ivanov, T. I.; Lange, C. A. de; Ubachs, W.; Reinhold, E.

    2008-10-17

    We report on the realization of a heavy 'Bohr atom', through the spectroscopic observation of a Rydberg series of bound quantum states at principal quantum numbers n=140 to 230. The system is made heavy by replacing an electron inside a hydrogen atom by a composite H{sup -} particle, thus forming a H{sup +}H{sup -} Coulombically bound system obeying the physical laws of a generalized atom with appropriate mass scaling.

  15. 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.

  16. 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.

  17. 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.

  18. Effect of charge polarization on inelastic scattering - Differential and integral cross sections for excitation of the 2/super 1/S state of helium by electron impact.

    NASA Technical Reports Server (NTRS)

    Rice, J. K.; Truhlar, D. G.; Cartwright, D. C.; Trajmar, S.

    1972-01-01

    Experimental differential scattering cross sections for excitation of helium by electron impact from its ground state to its 2(super 1)S state are presented at four incident electron energies in the range from 26 to 55.5 eV for scattering angles between 10 and 70 deg and at 81.6 eV for scattering angles between 10 and 80 deg. These cross sections are normalized and compared with results predicted by the Born approximation, the polarized Born approximation, and several other first-order approximations in which direct excitation is calculated in the Born approximation and exchange scattering in various Ochkur-like approximations.

  19. Photoionization cross section measurements of the 3p {sup 1,3}P excited states of helium in the near-threshold region

    SciTech Connect

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

    2006-08-15

    We present measurements of photoionization cross sections of the 3p {sup 1}P and 3p {sup 3}P excited states of helium, at threshold and near-threshold region (0-0.2 Ry). The experiments have been performed using a dc glow discharge and employed the saturation technique to determine the photoionization cross sections. A smooth frequency dependence of the cross section has been observed for both the excited states in accordance to the theoretical calculations. The measured values of the photoionization cross section, using a simple experimental setup, are in good agreement with the earlier reported theoretical and experimental values.

  20. Robust and High Fidelity Quantum Logic with the Rydberg-Dressed Blockade

    NASA Astrophysics Data System (ADS)

    Keating, Tyler; Cook, Robert; Deutsch, Ivan; Hankin, Aaron; Jau, Yuan-Yu; Biedermann, Grant

    2015-05-01

    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 adiabatically dressing the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise from atomic thermal motion. The adiabatic protocol also allows for a Doppler-free configuration with counterpropagating lasers in a ?+ /?- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in <10 ?s with error probability of order 10-3. We generalize this protocol to exploit the multi-body nature of the Rydberg blockade and go beyond two qubits. We show how one can implement a three-qubit Toffoli gate in a single-step. Finally, we consider encoding in collective states of small ensembles of atoms, and show how such a scheme can allow for scalable, robust, quantum logic.

  1. Pulsed Rydberg four-wave mixing with motion-induced dephasing in a thermal vapor

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Hsin; Ripka, Fabian; Lw, 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.

  2. 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.

  3. 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.

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

    PubMed

    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. PMID:25838380

  5. 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.

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

    PubMed

    Hori, Masaki; Str, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Friedreich, Susanne; Juhsz, Bertalan; Pask, Thomas; Widmann, Eberhard; Horvth, 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 (? = 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

  7. 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.

  8. Quantum repeaters based on Rydberg-blockade-coupled atomic ensembles

    SciTech Connect

    Han Yang; He Bing; Heshami, Khabat; Simon, Christoph; Li Chengzu

    2010-05-15

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

  9. 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.

  10. 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.

  11. 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.

  12. Heavy-Rydberg ion-pair formation in Rydberg atom collisions: Probing dissociative electron attachment

    NASA Astrophysics Data System (ADS)

    Kelley, Michael; Buathong, Sitti; Dunning, F. Barry

    2015-05-01

    While electron transfer in Rydberg atom collisions with attaching targets forms a valuable technique with which to create heavy-Rydberg ion pairs to examine their properties, we demonstrate here that measurements of their velocity distributions can also provide insights into the behavior of the excited intermediates formed through initial electron transfer. The experimental results are analyzed with the aid of a Monte Carlo collision code that models the details of electron transfer reactions. Results for a variety of targets are presented that demonstrate the use of this approach to examine the dynamics of dissociative electron attachment, the lifetimes of the intermediates created, and the channels by which they decay. Research supported by the Robert A. Welch Foundation under Grant C-0734.

  13. Fidelity of a Rydberg-blockade quantum gate from simulated quantum process tomography

    NASA Astrophysics Data System (ADS)

    Zhang, X. L.; Gill, A. T.; Isenhower, L.; Walker, T. G.; Saffman, M.

    2012-04-01

    We present a detailed error analysis of a Rydberg blockade mediated controlled-not quantum gate between two neutral atoms as demonstrated recently in Isenhower [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.104.010503 104, 010503 (2010)] and Zhang [Phys. Rev. A1050-294710.1103/PhysRevA.82.030306 82, 030306 (2010)]. Numerical solutions of a master equation for the gate dynamics, including all known sources of technical error, are shown to be in good agreement with experiments. The primary sources of gate error are identified and suggestions given for future improvements. We also present numerical simulations of quantum process tomography to find the intrinsic fidelity, neglecting technical errors, of a Rydberg blockade controlled phase gate. The gate fidelity is characterized using trace overlap and trace distance measures. We show that the trace distance is linearly sensitive to errors arising from the finite Rydberg blockade shift and introduce a modified pulse sequence which corrects the linear errors. Our analysis shows that the intrinsic gate error extracted from simulated quantum process tomography can be under 0.002 for specific states of 87Rb or Cs atoms. The relation between the process fidelity and the gate error probability used in calculations of fault tolerance thresholds is discussed.

  14. Emergence of stationary many-body entanglement in driven-dissipative Rydberg lattice gases

    NASA Astrophysics Data System (ADS)

    Lee, Sun Kyung; Cho, Jaeyoon; Choi, K. S.

    2015-11-01

    Non-equilibrium quantum dynamics represents an emerging paradigm for condensed matter physics, quantum information science, and statistical mechanics. Strongly interacting Rydberg atoms offer an attractive platform to examine driven-dissipative dynamics of quantum spin models with long-range order. Here, we explore the conditions under which stationary many-body entanglement persists with near-unit fidelity and high scalability. In our approach, coherent many-body dynamics is driven by Rydberg-mediated laser transitions, while atoms at the lattice boundary locally reduce the entropy of the many-body system. Surprisingly, the many-body entanglement is established by continuously evolving a locally dissipative Rydberg system towards the steady state, precisely as with optical pumping. We characterize the dynamics of multipartite entanglement in an one-dimensional lattice by way of quantum uncertainty relations, and demonstrate the long-range behavior of the stationary entanglement with finite-size scaling. Our work opens a route towards dissipative preparation of many-body entanglement with unprecedented scaling behavior.

  15. Borromean three-body FRET in frozen Rydberg gases

    NASA Astrophysics Data System (ADS)

    Faoro, R.; Pelle, B.; Zuliani, A.; Cheinet, P.; Arimondo, E.; Pillet, P.

    2015-09-01

    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.

  16. Borromean three-body FRET in frozen Rydberg gases.

    PubMed

    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

  17. 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

  18. 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.

  19. Population coherent control of a Rydberg sodium atom in a microwave field

    NASA Astrophysics Data System (ADS)

    Jiang, Li-Juan; Zhang, Xian-Zhou; Jia, Guang-Rui; Zhang, Yong-Hui; Xia, Li-Hua

    2012-07-01

    The B-spline expansion technique and the time-dependent multilevel approach (TDMA) are used to study the interaction between a microwave field and sodium atoms. The Rydberg sodium atom energy levels of p states in zero field are calculated, and the results are in good agreement with the other theoretical ones. The time evolutions during the population transfers of the five states from n = 75 to n = 79 in different microwave fields are obtained. The results show that the coherent control of the population transfer from the lower states to the higher ones can be accomplished by optimizing the microwave pulse parameters.

  20. 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.