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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. Excitation of Helium to Rydberg States Using STIRAP

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoxu

    2011-12-01

    Driving atoms from an initial to a final state of the same parity via an intermediate state of opposite parity is most efficiently done using STIRAP, because it does not populate the intermediate state. For optical transitions this requires appropriate pulses of light in the counter-intuitive order - first coupling the intermediate and final states. We populate Rydberg states of helium (n = 12 ˜ 30) in a beam of average velocity 1070 m/s by having the atoms cross two laser beams in a tunable dc electric field. The "red" light near lambda = 790 ~ 830 nm connects the 33P states to the Rydberg states and the "blue" beam of lambda = 389 nm connects the metastable 2 3S state atoms emitted by our source to the 33 P states. By varying the relative position of these beams we can vary both the order and the overlap encountered by the atoms. We vary either the dc electric field and fix the " red " laser frequency or vary the "red" laser frequency and fix the dc electric field to sweep across Stark states of the Rydberg manifolds. Several mm downstream of the interaction region we apply the very strong bichromatic force on the 23S → 2 3P transition at lambda = 1083 nm. It deflects the remaining 23S atoms out of the beam and the ratio of this signal measured with STIRAP beam on and off provides an absolute measure of the fraction of the atoms remaining in the 23 S state. Simple three-level models of STIRAP all predict 100% excitation probability, but our raw measurements are typically around half of this, and vary with both n and l of the Rydberg states selected for excitation by the laser frequency and electric field tuning on our Stark maps. For states with high enough Rabi frequency, after correction for the decay back to the metastable state before the deflection, the highest efficiencies are around 70%. An ion detector readily detects the presence of Rydberg atoms. We believe that the observed signals are produced by black-body ionization at a very low rate, but

  3. Rydberg States of Na-doped Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Drabbels, Marcel

    2008-03-01

    The dynamics of excited states of Na atoms deposited on the surface of helium nanodroplets has been investigated with velocity map ion imaging, photoelectron spectroscopy and time-of-flight mass-spectroscopy. For the first time, the excitation spectra of Na-doped helium nanodroplets corresponding to Rydberg states of Na atoms have been measured from the lowest excited 3p state up to the ionization threshold. All lines in the excitation spectra are shifted and broadened with respect to the corresponding atomic lines. In addition to bare Na* atoms also Na*HeN (N = 1-6) exciplexes are detected upon excitation. Photoelectron spectroscopy reveals the desorption of Na* not only in the initially excited states but also in lower lying states, indicating that relaxation plays an important role. The recorded velocity distributions show interesting characteristics: for the lowest states the mean kinetic energy of Na* increases linearly with excitation energy. The velocity distributions of Na*HeN exciplexes do not manifest such remarkable properties. The observations can be largely explained by assuming that the interaction of Na* with the helium nanodroplet can be described by the sum of Na*-He pair potentials.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  5. Asymptotic Energies and QED Shifts for Rydberg States of Helium

    NASA Technical Reports Server (NTRS)

    Drake, G.W.F.

    2007-01-01

    This paper reviews progress that has been made in obtaining essentially exact solutions to the nonrelativistic three-body problem for helium by a combination of variational and asymptotic expansion methods. The calculation of relativistic and quantum electrodynamic corrections by perturbation theory is discussed, and in particular, methods for the accurate calculation of the Bethe logarithm part of the electron self energy are presented. As an example, the results are applied to the calculation of isotope shifts for the short-lived 'halo' nucleus He-6 relative to He-4 in order to determine the nuclear charge radius of He-6 from high precision spectroscopic measurements carried out at the Argonne National Laboratory. The results demonstrate that the high precision that is now available from atomic theory is creating new opportunities to create novel measurement tools, and helium, along with hydrogen, can be regarded as a fundamental atomic system whose spectrum is well understood for all practical purposes.

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  7. Preparation of circular Rydberg states in helium using the crossed-fields method

    NASA Astrophysics Data System (ADS)

    Zhelyazkova, V.; Hogan, S. D.

    2016-08-01

    Helium atoms have been prepared in the circular |n =55 ,ℓ =54 , mℓ=+54 > Rydberg state using the crossed electric and magnetic fields method. The atoms, initially traveling in pulsed supersonic beams, were photoexcited from the metastable 1 s 2 s S31 level to the outermost, mℓ=0 Rydberg-Stark state with n =55 in the presence of a strong electric field and weak perpendicular magnetic field. Following excitation, the electric field was adiabatically switched off causing the atoms to evolve into the circular state with mℓ=+54 defined with respect to the magnetic-field quantization axis. The circular states were detected by ramped electric-field ionization along the magnetic-field axis. The dependence of the circular state production efficiency on the strength of the excitation electric field, and the electric-field switch-off time was studied, and microwave spectroscopy of the circular-to-circular |55 ,54 ,+54 >→|56 ,55 ,+55 > transition at ˜38.5 GHz was performed.

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

    NASA Astrophysics Data System (ADS)

    Argenti, L.

    2008-11-01

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

  9. Coherent manipulation of Rydberg helium atoms in inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hyun

    Coherent manipulation of atomic motion has been a subject of increased interest in atomic physics because it provides the opportunity to perform precision spectroscopy. Since the first demonstration of laser cooling techniques, exerting controlled optical forces on neutral atoms has made it possible to develop new tools for working on the near-atomic scale. While most of these tools are based on manipulating atoms with laser light, a different method which exploits the interaction of Rydberg atoms with inhomogeneous electrostatic fields to control the atomic motion was proposed in 1981. Atoms in Rydberg states have a large dipole moment because their outer electrons are located far from the core. Due to the relatively strong dipole interaction, therefore, the motion of Rydberg atoms can be affected even by weak and moderate field gradients. Ultimately, it is desirable to maximize the population in the Rydberg states to increase the intensity of the beam focused by an electrostatic lens. In a new approach to achieve a highly efficient population transfer, we take advantage of the highly efficient Stimulated Raman Adiabatic Passage (STIRAP) excitation technique. In this thesis, we first present an investigation of the Stark-shifted atomic energy levels and compare our observations to numerical calculations. Once the state with the highest transition efficiency has been identified we employ the coherent STIRAP excitation technique in order to achieve a complete population transfer from the metastable ground state to the target state via an intermediate state in the three-level ladder system 23S1 → 33 P2 → nLj of triplet helium. In order to fulfill the strict conditions for STIRAP, we also need to know the Rabi frequencies of the laser fields. For this purpose, the Autler-Townes effect is also examined. Finally, we demonstrate an example of atom optics by focusing the atomic beam with our electrostatic lens after preparing the metastable helium atoms in one of the

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

    PubMed

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

    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(2) (+) and He(3) (+) 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.

  11. Fractal dynamics in the ionization of helium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Xu, Xiulan; Zhang, Yanhui; Cai, Xiangji; Zhao, Guopeng; Kang, Lisha

    2016-11-01

    We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory. By introducing a fractal approach to describe the chaotic dynamical behavior of the ionization, we identify the fractal self-similarity structure of the escape time versus the distribution of the initial launch angles of electrons, and find that the self-similarity region shifts toward larger initial launch angles with a decrease in the scaled energy. We connect the fractal structure of the escape time plot to the escape dynamics of ionized electrons. Of particular note is that the fractal dimensions are sensitively controlled by the scaled energy and magnetic field, and exhibit excellent agreement with the chaotic extent of the ionization systems for both helium and hydrogen Rydberg atoms. It is shown that, besides the electric and magnetic fields, core scattering is a primary factor in the fractal dynamics. Project supported by the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AM030).

  12. Millimetre wave spectroscopy of high Rydberg states

    NASA Astrophysics Data System (ADS)

    Merkt, F.; Osterwalder, A.

    We have recently developed high-resolution vacuum ultraviolet laser sources and combined these with millimetre waves in double-resonance experiments to achieve a spectral resolution of up to 60 kHz in the spectra of high Rydberg states. The article describes the main features of our experimental procedure and presents studies in which we have used millimetre wave spectroscopy (a) to obtain information on the energy level structure, including the spin-orbit and hyperfine structure, of atomic Rydberg states at high principal quantum numbers n , (b) to record spectrally resolved spectra of the high Rydberg states ( n ≥100) detected in pulsed-field-ionization zero-kinetic-energy photoelectron spectra, (c) to measure stray electric fields and ion concentrations in the gas phase, (d) to test and improve the selectivity of the electric field ionization of high Rydberg states and (e) to observe for the first time the hyperfine structure in high- n , low- l molecular Rydberg states.

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

    NASA Astrophysics Data System (ADS)

    He, Liming; Cao, Wei

    2006-12-01

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

  14. Thermal ionization of Cs Rydberg states

    NASA Astrophysics Data System (ADS)

    Glukhov, I. L.; Ovsiannikov, V. D.

    2009-01-01

    Rates Pnl of photoionization from Rydberg ns-, np-, nd-states of a valence electron in Cs, induced by black-body radiation, were calculated on the basis of the modified Fues model potential method. The numerical data were approximated with a three-term expression which reproduces in a simple analytical form the dependence of Pnl on the ambient temperature T and on the principal quantum number n. The comparison between approximate and exactly calculated values of the thermal ionization rate demonstrates the applicability of the proposed approximation for highly excited states with n from 20 to 100 in a wide temperature range of T from 100 to 10,000 K. We present coefficients of this approximation for the s-, p- and d-series of Rydberg states.

  15. Preparation of Entangled and Antiferromagnetic States by Dissipative Rydberg Pumping

    NASA Astrophysics Data System (ADS)

    Carr, A. W.; Saffman, M.

    2013-07-01

    We propose and analyze an approach for preparation of high fidelity entanglement and antiferromagnetic states using Rydberg mediated interactions with dissipation. Using asymmetric Rydberg interactions the two-atom Bell singlet is a dark state of the Rydberg pumping process. Master equation simulations demonstrate Bell singlet preparation fidelity F=0.998. Antiferromagnetic states are generated on a four-spin plaquette in agreement with results found from diagonalization of the transverse field Ising Hamiltonian.

  16. 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.

  17. 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.

  18. 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).

  19. State-selective generation of molecular ions via Rydberg states

    NASA Astrophysics Data System (ADS)

    Grimes, David; Zhou, Yan; Barnum, Timothy; Coy, Stephen; Kay, Jeffrey; Field, Robert

    2014-05-01

    Autoionizing Rydberg states of molecules in the range n = 30-50 have the potential to enable the production of single quantum state selected ensembles of molecular ions, which have uses from spectroscopy to high precision measurements of fundamental constants. Multichannel Quantum Defect Theory (MQDT) fully describes the Rydberg states of molecules and the dynamics of autoionization. We have used our full MQDT description of CaF to determine optimal autoionizing resonances for producing a variety of selected rotation-vibration states of the ion. Progress towards experimental demonstrations in BaF will also be discussed. This work was supported by the NSF and an NDSEG Fellowship

  20. Cpmmw Spectroscopy of Rydberg States of Nitric Oxide

    NASA Astrophysics Data System (ADS)

    Barnum, Timothy J.; Saladrigas, Catherine A.; Grimes, David; Coy, Stephen; Eyler, Edward E.; Field, Robert W.

    2016-06-01

    The spectroscopy of Rydberg states of NO has a long history [1], stimulating both experimental and theoretical advances in our understanding of Rydberg structure and dynamics. The closed-shell ion-core (1Σ+) and small NO+ dipole moment result in regular patterns of Rydberg series in the Hund's case (d) limit, which are well-described by long-range electrostatic models (e.g., [2]). We will present preliminary data on the core-nonpenetrating Rydberg states of NO (orbital angular momentum, ℓ ≥ 3) collected by chirped-pulse millimeter-wave (CPmmW) spectroscopy. Our technique directly detects electronic free induction decay (FID) between Rydberg states with Δn* ≈ 1 in the region of n* ˜ 40-50, providing a large quantity (12 GHz bandwidth in a single shot) of high quality (resolution ˜ 350 kHz) spectra. Transitions between high-ℓ, core-nonpenetrating Rydberg states act as reporters on the subtle details of the ion-core electric structure. * * [1] Huber KP. Die Rydberg-Serien im Absorptions-spektrum des NO-Molekuuls. Helv. Phys. Acta 3, 929 (1961). * * [2] Biernacki DT, Colson SD, Eyler EE. Rotationally resolved double resonance spectra of NO Rydberg states near the first ionization limit. J. Chem. Phys. 88, 2099 (1988).

  1. Lifetimes of Rydberg states of Eu atoms

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  2. Applications of molecular Rydberg states in chemical dynamics and spectroscopy

    NASA Astrophysics Data System (ADS)

    Softley, T. P.

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

  3. Direct excitation of butterfly states in Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Lippe, Carsten; Niederpruem, Thomas; Thomas, Oliver; Eichert, Tanita; Ott, Herwig

    2016-05-01

    Since their first theoretical prediction Rydberg molecules have become an increasing field of research. These exotic states originate from the binding of a ground state atom in the electronic wave function of a highly-excited Rydberg atom mediated by a Fermi contact type interaction. A special class of long-range molecular states, the butterfly states, were first proposed by Greene et al.. These states arise from a shape resonance in the p-wave scattering channel of a ground state atom and a Rydberg electron and are characterized by an electron wavefunction whose density distribution resembles the shape of a butterfly. We report on the direct observation of deeply bound butterfly states of Rydberg molecules of 87 Rb. The butterfly states are studied by high resolution spectroscopy of UV-excited Rydberg molecules. We find states bound up to - 50 GHz from the 25 P1/2 , F = 1 state, corresponding to binding lengths of 50a0 to 500a0 and with permanent electric dipole moments of up to 500 Debye. This distinguishes the observed butterfly states from the previously observed long range Rydberg molecules in rubidium.

  4. Above-threshold ionization through Rydberg state population

    NASA Astrophysics Data System (ADS)

    Xin, Pei Pei; Yuan, Ming Hu; Wang, Han Mu; Yang, Hai Feng; Liu, Hong Ping

    2017-04-01

    We present a theoretical scenario for the atomic above-threshold ionization (ATI) in an intense laser field by investigating the Rydberg state population in real time. Rather than merely viewing the final distribution of photoelectron yield directly, we monitor the Rydberg state population by projecting the time-dependent wave function onto the bound eigen-states. The calculation shows that the population of resonant Rydberg states is closely related to the peaks in photoelectron kinetic energy spectrum (PKES). For a hydrogen atom, the highest populated Rydberg states are degenerated, exactly corresponding to the first ATI peak if one additional photon is absorbed. While for non-hydrogen atoms, e.g., Ar, the highest Rydberg states are mainly populated on specific states, e.g., 3 d (5 s) and 4f in our case, also giving exact peak positions in PKES, where the state identification is obtained by the angular momentum resolved distribution of excited Rydberg states. This method provides an easy to understand picture for the resonance-enhanced effects in ATI as well as the role of atomic core potential in strong-field ionization.

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

    NASA Astrophysics Data System (ADS)

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

    2003-09-01

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

  6. 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.

  7. A note on the assignments of Rydberg states of COS

    NASA Technical Reports Server (NTRS)

    Wu, C. Y. R.

    1982-01-01

    Assignments of the Rydberg states which converge to the respective X-tilde and B-tilde ion states of the COS(+) ion are reported. The assignments were made based on previously established orderings for the quantum defects of isoelectronic molecules. The Rydberg series I and II, which converge to the X-tilde 2 Pi state of COS(+), and the series III, IV, V, VI and VII, which converge to the B-tilde 2 Sigma + state, are assigned to molecular orbitals characterized by predominant sulfur orbitals, in contrast to those converging to the C-tilde states, which are characterized by oxygen atomic orbitals.

  8. Double Resonance Spectroscopy of BaF Autoionizing Rydberg States

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    We have studied the ν=1 Rydberg states of BaF in the energy region E=38800-39100 wn (n*=15-25) via optical-optical double resonance spectroscopy. Rydberg states excited above the first ionization potential spontaneously autoionize and 138Ba19F+ ions are detected by TOF-MS. In addition, BaF possesses a particularly low ionization potential, which allows for the study of autoionization dynamics in the absence of predissociative decay. This work extends the assignments of core-penetrating Rydberg states of BaF (Jakubek and Field, 2000) for applications to state-selective ion production schemes. Polarization and Stark spectroscopy techniques will be discussed in the context of accurate and efficient assignment of spectra.

  9. Equivalent Multipole Operators for Degenerate Rydberg States

    DTIC Science & Technology

    2006-08-23

    Equivalence of two operators means here that they yield identical matrix elements within a subspace of Hilbert space that corresponds to fixed n. Such...Rydberg atom in time -dependent electric and magnetic fields 6. For example, analytical probabilities have been derived 3–5, without the need for...any perturbative and numerical analysis, for the full array of l→ l transitions in atomic hydrogen Hnl induced by a time -varying weak electric field

  10. Long-range Rydberg molecules, Rydberg macrodimers and Rydberg aggregates in an ultracold Cs gas. Investigation of long-range interactions between atoms in electronically highly excited statesRydberg Few-Body Physics

    NASA Astrophysics Data System (ADS)

    Saßmannshausen, Heiner; Deiglmayr, Johannes; Merkt, Frédéric

    2016-12-01

    We present an overview of our recent investigations of long-range interactions in an ultracold Cs Rydberg gas. These interactions are studied by high-resolution photoassociation spectroscopy, using excitation close to one-photon transitions into np3/2 Rydberg states with pulsed and continuous-wave ultraviolet laser radiation, and lead to the formation of long-range Cs2 molecules. We observe two types of molecular resonances. The first type originates from the correlated excitation of two atoms into Rydberg-atom-pair states interacting at long range via multipole-multipole interactions. The second type results from the interaction of one atom excited to a Rydberg state with one atom in the electronic ground state. Which type of resonances is observed in the experiments depends on the laser intensity and frequency and on the pulse sequences used to prepare the Rydberg states. We obtain insights into both types of molecular resonances by modelling the interaction potentials, using a multipole expansion of the long-range interaction for the first type of resonances and a Fermi-contact pseudo-potential for the second type of resonances. We analyse the relation of these long-range molecular resonances to molecular Rydberg states and ion-pair states, and discuss their decay channels into atomic and molecular ions. In experiments carried out with a two-colour two-photon excitation scheme, we observe a large enhancement of Rydberg-excitation probability, which we interpret as a saturable autocatalytic antiblockade phenomenon.

  11. Resonant quenching of Rydberg atomic states by highly polar molecules

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The results of theoretical studies of the resonant quenching and ion-pair formation processes induced by collisions of Rydberg atoms with highly polar molecules possessing small electron affinities are reported. We elaborate an approach for describing collisional dynamics of both processes and demonstrate the predominant role of resonant quenching channel of reaction for the destruction of Rydberg states by electron-attaching molecules. The approach is based on the solution of the coupled differential equations for the transition amplitudes between the ionic and Rydberg covalent terms of a quasimolecule formed during a collision of particles. It takes into account the possibility of the dipole-bound anion decay in the Coulomb field of the positive ionic core and generalizes previous models of charge-transfer processes involving Rydberg atoms to the cases, when the multistate Landau-Zener approaches become inapplicable. Our calculations for {{Rb}}({nl}) atom perturbed by {{{C}}}2{{{H}}}4{{SO}}3, {{CH}}2{CHCN}, {{CH}}3{{NO}}2, {{CH}}3{CN}, {{{C}}}3{{{H}}}2{{{O}}}3, and {{{C}}}3{{{H}}}4{{{O}}}3 molecules show that the curves representing the dependence of the resonant quenching cross sections on the principal quantum number n are bell-shaped with the positions of maxima being shifted towards lower values of n and the peak values, {σ }{max}({{q})}, several times higher than those for the ion-pair formation, {σ }{max}({{i})}. We obtain a simple power relation between the energy of electron affinity of a molecule and the position of maximum in n-dependence of the resonant quenching cross section. It can be used as an additional means for determining small binding energies of dipole-bound anions from the experimental data on resonant quenching of Rydberg states by highly polar molecules.

  12. Selective Population of Molecular Core Nonpenetrating Rydberg States

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  13. Three-photon coherence of Rydberg atomic states

    NASA Astrophysics Data System (ADS)

    Kwak, Hyo Min; Jeong, Taek; Lee, Yoon-Seok; Moon, Han Seb

    2016-05-01

    We investigated three-photon coherence effects of the Rydberg state in a four-level ladder-type atomic system for the 5 S1/2 (F = 3) - 5 P3/2 (F' = 4) - 50 D5/2 - 51 P3/2 transition of 85 Rb atoms. By adding a resonant electric field of microwave (MW) at electromagnetically induced transparency (EIT) in Rydberg state scheme, we observed experimentally that splitting of EIT signal appears under the condition of three-photon resonance in the Doppler-broadened atomic system. Discriminating the two- and three-photon coherence terms from the calculated spectrum in a simple four-level ladder-type Doppler-broadened atomic system, we found that the physical origin of splitting of EIT was three-photon coherence effect, but not three-photon quantum interference phenomena such as three-photon electromagnetically induced absorption (TPEIA).

  14. Interaction Enhanced Imaging of Rydberg P states. Preparation and detection of Rydberg atoms for engineering long-range interactions

    NASA Astrophysics Data System (ADS)

    Gavryusev, Vladislav; Ferreira-Cao, Miguel; Kekić, Armin; Zürn, Gerhard; Signoles, Adrien

    2016-12-01

    The Interaction Enhanced Imaging technique allows to detect the spatial distribution of strongly interacting impurities embedded within a gas of background atoms used as a contrast medium [1]. Here we present a detailed study of this technique, applied to detect Rydberg P states. We experimentally realize fast and efficient three-photon excitation of P states, optimized according to the results of a theoretical effective two-level model. Few Rydberg P-state atoms, prepared in a small cloud with dimensions comparable to the blockade radius, are detected with a good sensitivity by averaging over 50 shots. The main aspects of the technique are described with a hard-sphere model, finding good agreement with experimental data. This work paves the way to a non-destructive optical detection of single Rydberg atoms with high spatial and temporal resolution.

  15. Relativistic, retardation, and radiative corrections in Rydberg states of lithium

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

    We have used third-order perturbation theory to calculate the effect of the Breit-Pauli relativistic interaction on the dipole polarizability of Li+ ions of order α2 . Results are in good agreement with the value obtained by Johnson and Cheng [Phys. Rev. A 53, 1375 (1996)]. In addition, the retardation (Casimir) corrections to singly excited (1s2 NL) states of neutral lithium have been computed. When both of these corrections are added to the previously calculated Rydberg state energies, 1σ agreement is found with experiment [N. E. Rothery et al., Phys. Rev. A 51, 2919 (1995)]. Addition of radiative (Lamb-shift) corrections produces essentially exact agreement.

  16. 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).

  17. General theory for Rydberg states of atoms: The nonrelativistic case

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Feng; Yan, Zong-Chao

    2017-02-01

    We carry out a complete derivation on nonrelativistic energies of atomic Rydberg states, including finite nuclear mass corrections. Several missing terms are found and a discrepancy is confirmed in the works of Drachman [in Long Range Casimir Forces: Theory and Recent Experiments on Atomic Systems, edited by F. S. Levin and D. A. Micha (Plenum, New York, 1993)] and Drake [Adv. At., Mol., Opt. Phys. 31, 1 (1993)]., 10.1016/S1049-250X(08)60087-7 As a benchmark, we present a detailed tabulation of different energy levels.

  18. Elliptic Rydberg states as direction indicators

    SciTech Connect

    Lindner, Netanel H.; Peres, Asher; Terno, Daniel R.

    2003-10-01

    The orientation in space of a Cartesian coordinate system can be indicated by the two vectorial constants of motion of a classical Keplerian orbit: the angular momentum and the Laplace-Runge-Lenz vector. In quantum mechanics, the states of a hydrogen atom that mimic classical elliptic orbits are the coherent states of the SO(4) rotation group. It is known how to produce these states experimentally. They have minimal dispersions of the two conserved vectors and can be used as direction indicators. We compare the fidelity of this transmission method with that of the idealized optimal method.

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

    SciTech Connect

    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 H{sub 2} and H{sub 3} 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. {copyright} {ital 1999 American Institute of Physics.}

  20. Microwave-induced three-photon coherence of Rydberg atomic states

    NASA Astrophysics Data System (ADS)

    Kwak, Hyo Min; Jeong, Taek; Lee, Yoon-Seok; Moon, Han Seb

    2016-12-01

    We investigate the three-photon coherence (TPC) effects of the Rydberg state in a Doppler-broadened four-level ladder-type atomic system for the 5S1/2(F=3)-5P3/2(F‧=4)-50D5/2-51P3/2 transition of 85Rb atoms. Upon interaction of the Rydberg Rb atom of the ladder-type electromagnetically induced transparency (EIT) scheme with a resonant microwave (MW) field, we numerically analyze the spectral features of the Rydberg TPC from two viewpoints, Autler-Townes splitting (AT-splitting) of the Rydberg EIT and three-photon electromagnetically induced absorption (TPEIA). We determine the criterion to differentiate between AT-splitting of the Rydberg EIT and TPEIA in the Doppler-broadened ladder-type atomic system.

  1. Toward the Use of Rydberg States for State-Selective Production of Molecular Ions

    NASA Astrophysics Data System (ADS)

    Grimes, David; Barnum, Timothy J.; Coy, Stephen; Field, Robert W.

    2014-06-01

    The usual simplified view of Rydberg states of molecules as consisting of a single Rydberg electron loosely bound to a molecular ion core in a well-defined rotation-vibration state suggests an attractive possibility for state-selective production of molecular ions. A Rydberg electron excited above the energy of the ground state of the ion core will spontaneously autoionize, leaving behind a molecular ion. The autoionizing states are of strongly mixed character due to the ubiquitous nonadiabatic interactions between Rydberg series associated with different states of the ion core. Using our complete Multichannel Quantum Defect Theory (MQDT) fit model for CaF, we have predicted the locations and strengths of special autoionizing resonances that decay into a single rotation-vibration state of a molecular ion. Few molecules are as well characterized as CaF, nor as elegantly simple. We additionally describe the use of core nonpenetrating states as a general method to produce an ensemble of molecular ions in a single, selectable quantum state.

  2. Tunable frequency stabilization to Zeeman sublevel transitions between an intermediate state and Rydberg states

    NASA Astrophysics Data System (ADS)

    Bao, Shanxia; Zhang, Hao; Zhou, Jian; Zhang, Linjie; Zhao, Jianming; Xiao, Liantuan; Jia, Suotang

    2017-01-01

    We demonstrate a robust method of direct laser frequency locking on the Zeeman sublevel transitions between an intermediate state and Rydberg states, with continuously tunable frequency range from  -35 MHz to  +35 MHz, which is based on electromagnetically induced transparency (EIT) spectra of nondegenerate Zeeman sublevels in a Rydberg cascade system. With a small axial magnetic field, the EIT spectrum will split into two individual sub-peaks due to the Zeeman Effect of three energy levels, including the 133Cs 6S1/2, 6P3/2 and nl Rydberg states which form the cascade system. It is shown that the coupling field, corresponding to the transitions between the Zeeman sublevels of the intermediate state and Rydberg state, can be locked arbitrarily on any one of the two EIT sub-peaks. The frequency stability of locked lasers is bounded by 0.81 MHz. The root of Allan variance of the frequency reaches a minimum of 2.06× {{10}-8} for an averaging time of 512 s.

  3. Measurements of quantum defect in Rydberg D-states for lithium atoms

    NASA Astrophysics Data System (ADS)

    Murashkin, D. A.; Saakyan, S. A.; Sautenkov, V. A.; Zelener, B. B.

    2016-11-01

    We have developed an effective spectroscopic method for measure the energy spectra of highly excited ultracold atoms using the registration of resonance fluorescence of atoms in magneto-optical trap during two-step cw excitation of Rydberg states by uv laser. Using this method it was obtained the value of the quantum defect was determined for Rydberg states nD of lithium-7 atoms δ = 0.00192(17).

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

    SciTech Connect

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

  5. 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.

    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.

  6. Creation and transfer of nonclassical states of motion using Rydberg dressing of atoms in a lattice

    NASA Astrophysics Data System (ADS)

    Buchmann, L. F.; Mølmer, K.; Petrosyan, D.

    2017-01-01

    We theoretically investigate the manipulation of the motional states of trapped ground-state atoms using Rydberg dressing via nonresonant laser fields. The forces resulting from Rydberg state interaction between dressed neighboring atoms in an array of microtraps or an optical lattice can strongly couple their motion. We show that intensity modulation of the dressing field allows us to squeeze the relative motion of a pair of atoms and generate nonclassical mechanical states. Extending this pairwise scheme to one-dimensional chains provides flexible control over the mechanical degrees of freedom of the whole system. We illustrate our findings with protocols to manipulate all motional degrees of freedom of a pair of atoms and create entangled states. We also present a method to transfer nonclassical correlations along an atomic chain of nontrivial length. The long-lived nature of motional states, together with the high tunability of Rydberg dressing, makes our proposal feasible for current experimental setups.

  7. Surface ionisation of molecular H2 and atomic H Rydberg states at doped silicon surfaces

    NASA Astrophysics Data System (ADS)

    Sashikesh, G.; So, E.; Ford, M. S.; Softley, T. P.

    2014-09-01

    The detection of ions or electrons from the surface ionisation of molecular H2 and atomic H Rydberg states incident at doped Si surfaces is investigated experimentally to analyse the effect of the dopant charge distribution on the surface-ionisation processes. In both experimental studies, the molecular H2 and atomic H Rydberg states are generated via two-colour vacuum ultraviolet--ultraviolet (VUV-UV) resonant excitation. For H2, various Stark states of the N+ = 2, n = 17 manifold are populated in the presence of an electric field. The variation of the observed surface-ionisation signal with surface dopant concentration and type, shows similar characteristics for all the Stark states. A comparison is made between these ion-detected surface-ionisation profiles and those obtained via electron detection. Different trends as a function of dopant concentration and type are observed for the two cases, explained by the greater effect of surface charges on the post-ionisation ion trajectory compared to the electron trajectory. For the atomic-H Rydberg states with principal quantum number ? populated in the absence of a Stark field, the observed behaviour is similar to the interaction of molecular H2 Rydberg states at the same surfaces, and these measurements confirm that the observed effects are attributable to the nature of the target surface rather than the specific atomic or molecular Rydberg species.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  9. Role of Rydberg states in the photostability of heterocyclic dimers: the case of pyrazole dimer.

    PubMed

    Zilberg, Shmuel; Haas, Yehuda

    2012-11-26

    A new route for the nonradiative decay of photoexcited, H-bonded, nitrogen-containing, heterocyclic dimers is offered and exemplified by a study of the pyrazole dimer. In some of these systems the N(3s) Rydberg state is the lowest excited singlet state. This state is formed by direct light absorption or by nonradiative transition from the allowed ππ* state. An isomer of this Rydberg state is formed by H atom transfer to the other component of the dimer. The newly formed H-bonded radical pair is composed of two radicals (a H-adduct of pyrazole, a heterocyclic analogue of the NH(4) radical) and the pyrazolium π-radical. It is calculated to have a shallow local minimum and is the lowest point on the PES of the H-pyrazole/pyrazolium radical pair. This species can cross back to the ground state of the original dimer through a relatively small energy gap and compete with the H-atom loss channel, known for the monomer. In both Rydberg dimers, an electron occupies a Rydberg orbital centered mostly on one of the two components of the dimer. This Rydberg Center Shift (RCS) mechanism, proposed earlier (Zilberg, S.; Kahan, A.; Haas, Y. Phys. Chem. Chem. Phys. 2012, 14, 8836), leads to deactivation of the electronically excited dimer while keeping it intact. It, thus, may explain the high photostability of the pyrazole dimer as well as other heterocyclic dimers.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.

    1998-05-01

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

  12. Possibility of triple magic trapping of clock and Rydberg states of divalent atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Topcu, T.; Derevianko, A.

    2016-07-01

    We predict the possibility of ‘triply magic’ optical lattice trapping of neutral divalent atoms. In such a lattice, the {}1{{{S}}}0 and {}3{{{P}}}0 clock states and an additional Rydberg state experience identical optical potentials, fully mitigating detrimental effects of the motional decoherence. In particular, we show that this triply magic trapping condition can be satisfied for Yb atom at optical wavelengths and for various other divalent systems (Ca, Mg, Hg and Sr) in the UV region. We assess the quality of triple magic trapping conditions by estimating the probability of excitation out of the motional ground state as a result of the excitations between the clock and the Rydberg states. We also calculate trapping laser-induced photoionization rates of divalent Rydberg atoms at magic frequencies. We find that such rates are below the radiative spontaneous-emission rates, due to the presence of Cooper minima in photoionization cross-sections.

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

    NASA Astrophysics Data System (ADS)

    Pratt, S. T.

    1998-05-01

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

  14. Perturbations in the Spectra of High Rydberg States: Channel Interactions, Stark and Zeeman Effects

    NASA Astrophysics Data System (ADS)

    Haase, Christa; Schäfer, Martin; Hogan, Stephen D.; Merkt, Frédéric

    2011-06-01

    Rydberg states of principal quantum number n≫50 have been prepared by irradiation of an atomic beam of xenon with vacuum ultraviolet (VUV) radiation. Narrowband submillimeter-wave (THz) radiation was then used to record spectra of transitions from these Rydberg states to higher or lower-lying Rydberg states. The transitions were detected by selective field ionization and recording either the electrons or the ions, the latter offering the advantage of mass selection. Rydberg states of high principal quantum number are extremely sensitive to their environment, which can be exploited to characterize the experimental conditions under which the spectroscopic measurements are carried out. The high resolution achieved in the experiments (better than 100 kHz) enabled the study of the spectral lineshapes and line positions in dependence of weak electric (down to below 100μV/cm) and magnetic fields (down to a few μT), and of the density of Rydberg atoms and ions generated in the experimental volume. The experiments rely on the use of a pulsed, broadly tunable, laser-based source of THz radiation for survey scans, and of a phase- and frequency-stabilized submillimeter-wave backward-wave oscillator-based radiation source for precision measurements. To illustrate the use of these sources, we present the results of the spectroscopic investigations of the hyperfine structure of 129Xe Rydberg states in spectral regions where s-d interactions are expected to play a role. F. Merkt and A. Osterwalder Int. Rev. Phys. Chem. 21, 385, (2002). J. Liu and F. Merkt Appl. Phys. Lett. 93, 131105, (2008). M. Schäfer, M. Andrist, H. Schmutz, F. Lewen, G. Winnewisser and F. Merkt J. Phys. B: At. Mol. Opt. Phys. 39, 831, (2006).

  15. Resonant ionization spectroscopy of autoionizing Rydberg states in cobalt and redetermination of its ionization potential

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Gottwald, T.; Mattolat, C.; Wendt, K.

    2017-04-01

    Multi-step resonance ionization spectroscopy of cobalt has been performed using a hot-cavity laser ion source and three Ti:Sapphire lasers. The photoionization spectra revealed members of five new autoionizing Rydberg series that originate from three different lower levels of 3d 74s5s h 4F9/2, 3d 74s4d f 4G11/2, and 3d 74s4d f 4H13/2 and converge to the first four excited states of singly ionized Co. The analyses of the Rydberg series yield 63 564.689 ± 0.036 cm‑1 as the first ionization potential of Co, which is an order of magnitude more accurate than the previous estimation. Using a three-step resonance ionization scheme that employs an autoinizing Rydberg state in the last transition, we obtained an overall ionization efficiency of about 18% for Co. ).

  16. CEPA calculations on open-shell molecules. IV. Electron correlation effects in B1 Rydberg states of H2O

    NASA Astrophysics Data System (ADS)

    Staemmler, Volker; Jaquet, Ralph; Jungen, Martin

    1981-01-01

    We have calculated the vertical electronic excitation energies of ten 1b1→a1 excited states of H2O belonging to different Rydberg series. The calculations have been carried out with the FRC, SCF, PNO-CI, and CEPA approximations in order to investigate the electron correlation of Rydberg states. We report on correlation contributions to the electron binding energies, to the quantum defect of Rydberg series, and to the singlet-triplet splitting energies. In addition we make predictions for the dipole moments of the Rydberg states based on SCF calculations. Comparison of our results with experiment allows the assignment of transitions belonging to a np series and two nd series and it suggests an analysis for the 1b1→ns1B1 Rydberg series.

  17. Improved efficiency of selective photoionization of palladium isotopes via autoionizing Rydberg states

    NASA Astrophysics Data System (ADS)

    Locke, Clayton R.; Kobayashi, Tohru; Midorikawa, Katsumi

    2017-01-01

    Odd-mass-selective ionization of palladium for purposes of resource recycling and management of long-lived fission products can be achieved by exploiting transition selection rules in a well-established three-step excitation process. In this conventional scheme, circularly polarized lasers of the same handedness excite isotopes via two intermediate 2D5/2 core states, and a third laser is then used for ionization via autoionizing Rydberg states. We propose an alternative excitation scheme via intermediate 2D3/2 core states before the autoionizing Rydberg state, improving ionization efficiency by over 130 times. We confirm high selectivity and measure odd-mass isotopes of >99.7(3)% of the total ionized product. We have identified and measured the relative ionization efficiency of the series of Rydberg states that converge to upper ionization limit of the 4 d 9(2D3/2) level, and identify the most efficient excitation is via the Rydberg state at 67668.18(10) cm-1.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    SciTech Connect

    Sprecher, Daniel; Merkt, Frédéric

    2014-03-28

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

  20. Quantum Halo States in Helium Tetramers.

    PubMed

    Stipanović, Petar; Vranješ Markić, Leandra; Boronat, Jordi

    2017-01-12

    The universality of quantum halo states enables a comparison of systems from different fields of physics, as demonstrated in two- and three-body clusters. In the present work, we studied weakly bound helium tetramers in order to test whether some of these four-body realistic systems qualify as halos. Their ground-state binding energies and structural properties were thoroughly estimated using the diffusion Monte Carlo method with pure estimators. Helium tetramer properties proved to be less sensitive on the potential model than previously evaluated trimer properties. We predict the existence of realistic four-body halo (4)He2(3)He2, whereas (4)He4 and (4)He3(3)He are close to the border and thus can be used as prototypes of quasi-halo systems. Our results could be tested by the experimental determination of the tetramers' structural properties using a setup similar to the one developed for the study of helium trimers.

  1. 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.

  2. Rydberg State Stark Spectroscopy and Applications to Plasma Diagnostics

    DTIC Science & Technology

    1990-03-01

    Experimental setup. A neon hollow cathode discharge lamp was used for calibration of the helium singlet spectra; for the triplet spectra an argon lamp was...effect on an argon hollow cathode lamp . The optogalvanic voltage changes of the helium discharge and the argon lamp are simultaneously recorded with...optogalvanic signal of a neon lamp using the visible output of the dye laser (DCM dye) is shown above with the 621.728 nm line present. Because of the low

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  4. A spectroscopic study of the 3(1) pi g Rydberg state of 7Li2.

    PubMed

    Song, Min; Yi, Peng; Dai, Xing-can; Liu, Yao-ming; Li, Li

    2002-06-01

    With pulsed optical-optical double resonance (OODR) fluorescence excitation spectroscopy Rydberg states of 7Li2 in the energy region of 35,500-38,000 cm-1 were studied and 146 transitions into the 3(1) pi g state of 7Li2 were measured. They were assigned to 10 vibrational levels of the 3(1) pi g state. A new set of Dunham constants, RKR potential curve, and Franck-Condon factors for the transitions form the A 1 sigma u+ state are derived. The perturbations between the 4(F)1 sigma g+, 5 (1) sigma g+, 6 (1) sigma g+, 2 (G) 1 pi g Rydberg states with the 3 (1) pi g state are discussed. The lambda-doubling splitting of the observed levels can be ignored with our accuracy (0.2 cm-1).

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

    SciTech Connect

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

    2016-01-07

    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 {sup 1}B{sub 1u} (ππ{sup ∗}) 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{sup ∗} state, supporting the theoretical predictions.

  6. Deterministic entanglement generation between a pair of atoms on different Rydberg states via chirped adiabatic passage

    NASA Astrophysics Data System (ADS)

    Qian, Jing; Zhang, Weiping

    2017-03-01

    We develop a scheme for deterministic generation of an entangled state between two atoms on different Rydberg states via a chirped adiabatic passage, which directly connects the initial ground and target entangled states and also does not request the normally needed blockade effect. The occupancy of intermediate states suffers from a strong reduction via two pulses with proper time-dependent detunings and the electromagnetically induced transparency condition. By solving the analytical expressions of eigenvalues and eigenstates of a two-atom system, we investigate the optimal parameters for guaranteeing the adiabatic condition. We present a detailed study for the effect of pulse duration, changing rate, different Rydberg interactions on the fidelity of the prepared entangled state with experimentally feasible parameters, which reveals a good agreement between the analytic and full numerical results.

  7. Helium resources of the United States, 1987. Information Circular/1988

    SciTech Connect

    Miller, R.D.

    1987-01-01

    The helium-resources base of the United States was estimated by the Bureau of Mines to be 1040 Bcf as of January 1, 1987. These resources are divided into four categories in decreasing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 265 Bcf, (2) helium in probable natural gas resources, 228 Bcf, (3) helium in possible natural gas resources, 320 Bcf, and (4) helium in speculative natural gas resources, 227 Bcf. These helium resources are further divided into depleting and nondepleting, with the helium in storage being in a separate classification.

  8. Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

    NASA Astrophysics Data System (ADS)

    Wu, Guorong; Boguslavskiy, Andrey E.; Schalk, Oliver; Schuurman, Michael S.; Stolow, Albert

    2011-10-01

    Excited state unimolecular reactions of some polyenes exhibit localization of their dynamics at a single ethylenic double bond. Here we present studies of the fundamental photophysical processes in the ethylene unit itself. Combined femtosecond time-resolved photoelectron spectroscopy (TRPES) and ab initio quantum chemical calculations was applied to the study of excited state dynamics in cis-butene, trans-butene, trimethylethylene, and tetramethylethylene, following initial excitation to their respective π3s Rydberg states. The wavelength dependence of the π3s Rydberg state dynamics of tetramethylethylene was investigated in more detail. The π3s Rydberg to ππ* valence state decay rate varies greatly with substituent: the 1,2-di- and tri-methyl substituted ethylenes (cis-butene, trans-butene, and trimethylethylene) show an ultrafast decay (˜20 fs), whereas the fully methylated tetramethylethylene shows a decay rate of 2 to 4 orders of magnitude slower. These observations are rationalized in terms of topographical trends in the relevant potential energy surfaces, as found from ab initio calculations: (1) the barrier between the π3s state and the ππ* state increases with increasing methylation, and (2) the π3s/ππ* minimum energy conical intersection displaces monotonically away from the π3s Franck-Condon region with increasing methylation. The use of systematic methylation in combination with TRPES and ab initio computation is emerging as an important tool in discerning the excited state dynamics of unsaturated hydrocarbons.

  9. Creation of two-photon states via interactions between Rydberg atoms during light storage

    NASA Astrophysics Data System (ADS)

    Ruseckas, J.; Yu, I. A.; Juzeliūnas, G.

    2017-02-01

    We propose a method to create two-photon states in a controllable way using interaction between the Rydberg atoms during the storage and retrieval of slow light. A distinctive feature of the suggested procedure is that the slow light is stored into a superposition of two atomic coherences under conditions of electromagnetically induced transparency. Interaction between the atoms during the storage period creates entangled pairs of atoms in a superposition state that is orthogonal to the initially stored state. Restoring the slow light from this new atomic state one can produce a two-photon state with a second-order correlation function determined by the atom-atom interaction and the storage time. Therefore the measurement of the restored light allows one to probe the atom-atom coupling by optical means with a sensitivity that can be increased by extending the storage time. As a realization of this idea we consider a many-body Ramsey-type technique which involves π /2 pulses creating a superposition of Rydberg states at the beginning and the end of the storage period. In that case the regenerated light is due to the resonance dipole-dipole interaction between the atoms in the Rydberg states.

  10. Classical Monte-Carlo simulation for Rydberg states ionization in strong field

    NASA Astrophysics Data System (ADS)

    Carrat, Vincent; Magnuson, Eric; Gallagher, Thomas

    2016-05-01

    The resilience of Rydberg states against ionization has fascinated physicists for a long time. One might expect that the loosely bound electron would be ionized by modest electromagnetic field. However, experiments show that a notable fraction of neutral atoms survive in Rydberg states when exposed to strong microwave or laser fields. Energy transfer between the field and the photoelectron occurs when the electron is close to the ionic core and depends on the phase of the field. Since those states have orbital times that can be larger than the field pulse duration, these energy exchanges will only occur a few times. While we can experimentally control the initial time when we create the Rydberg states and as a consequence the initial energy transfer from the field, our classical calculation suggests that the phase when the electron is returning to the ionic core on the next orbit is chaotic. Statistically the electron only has a 50% chance to gain energy which may lead to ionization. Additionally the population tends to accumulate in very high n states where ionization is less likely due to fewer rescattering events. Though incomplete, this classical Monte­-Carlo simulation provides useful insights for understanding the experimental observations. This work has been entirely performed at University of Virginia and is supported by the U. S. Department of Energy, Office of Basic energy Sciences.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  12. Transport of charge and atomic particles in Rydberg state-rich plasmas

    NASA Astrophysics Data System (ADS)

    Hagström, Magnus; Davidsson, Jan; Holmlid, Leif

    1998-02-01

    New methods make it possible to form considerable flux densities of Rydberg atoms of alkali metals. It is now possible to study the transport processes in regions where the density of Rydberg atoms is large. Examples of such studies have been given by Svensson and coworkers. In the present study, 0022-3727/31/4/013/img1 ions and Rydberg states 0022-3727/31/4/013/img2 are formed by desorption at 1300-1800 K from an Ir surface covered by a thin graphite layer. Due to the very large cross sections for collision processes involving Rydberg species, the Rydberg state-rich plasma between the Ir emitter and a cold grid electrode is not collision free, even at a pressure of 0022-3727/31/4/013/img3 mbar. Electron or 0022-3727/31/4/013/img4 emission takes place from the grid at a rate controlled by the flux of 0022-3727/31/4/013/img1 and 0022-3727/31/4/013/img2. The transition to penetration of 0022-3727/31/4/013/img1 and 0022-3727/31/4/013/img2 through the cloud of excited species between the emitter and grid is observed directly by molecular beam and ion sampling to detectors in a separate chamber. There is a space-charge limited behaviour for the positive current through the plasma as well as, in some modes, a clear positive saturation current, which shows that little gas phase ionization takes place. A current larger than expected from the saturation current as well as maxima in the voltage dependences are observed at high Rydberg densities. These effects are probably caused by space charge compensation due to a dielectric phase of condensed excited species, which means, for example, that the effective distance between the emitter and grid is decreased, as observed. The temperature variation of the space charge limited behaviour gives an activation energy of 0022-3727/31/4/013/img9, while the saturation current gives an activation energy of 0022-3727/31/4/013/img10. This agrees well with the electronic excitations 0022-3727/31/4/013/img11 at 0.90 eV and 0022

  13. Storing single photons emitted by a quantum memory on a highly excited Rydberg state

    PubMed Central

    Distante, Emanuele; Farrera, Pau; Padrón-Brito, Auxiliadora; Paredes-Barato, David; Heinze, Georg; de Riedmatten, Hugues

    2017-01-01

    Strong interaction between two single photons is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photonic quantum gates and deterministic Bell-state measurements. In the context of quantum networks, it would be important to achieve interactions between single photons from independent photon pairs storable in quantum memories. So far, most experiments showing nonlinearities at the single-photon level have used weak classical input light. Here we demonstrate the storage and retrieval of a paired single photon emitted by an ensemble quantum memory in a strongly nonlinear medium based on highly excited Rydberg atoms. We show that nonclassical correlations between the two photons persist after retrieval from the Rydberg ensemble. Our result is an important step towards deterministic photon–photon interactions, and may enable deterministic Bell-state measurements with multimode quantum memories. PMID:28102203

  14. Studying dissociative electron attachment through formation of heavy-Rydberg ion-pair states

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    Following dissociative electron transfer in collisions between Rydberg atoms and electron-attaching targets, it is possible for the resulting pair of ions to remain electrostatically bound, forming heavy-Rydberg ion-pair states. Precise measurement of the velocity distributions of such ion-pair states provides information concerning the dissociation dynamics of the excited intermediates initially created by electron transfer. Here, electric-field-induced dissociation is used to detect the product ion pairs and observe their velocity distributions. These distributions are analyzed with the aid of a Monte Carlo collision code that models the electron transfer. Measurements with a number of different target species show that through this analysis, dissociation energetics, the branching ratios into different dissociation products, and the lifetimes of the excited intermediates can be examined. Research supported by the Robert A. Welch Foundation.

  15. Storing single photons emitted by a quantum memory on a highly excited Rydberg state

    NASA Astrophysics Data System (ADS)

    Distante, Emanuele; Farrera, Pau; Padrón-Brito, Auxiliadora; Paredes-Barato, David; Heinze, Georg; de Riedmatten, Hugues

    2017-01-01

    Strong interaction between two single photons is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photonic quantum gates and deterministic Bell-state measurements. In the context of quantum networks, it would be important to achieve interactions between single photons from independent photon pairs storable in quantum memories. So far, most experiments showing nonlinearities at the single-photon level have used weak classical input light. Here we demonstrate the storage and retrieval of a paired single photon emitted by an ensemble quantum memory in a strongly nonlinear medium based on highly excited Rydberg atoms. We show that nonclassical correlations between the two photons persist after retrieval from the Rydberg ensemble. Our result is an important step towards deterministic photon-photon interactions, and may enable deterministic Bell-state measurements with multimode quantum memories.

  16. 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 δ(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 δ(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 δ(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.

  17. 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.

  18. Transition from SAMO to Rydberg State Ionization in C60 in Femtosecond Laser Fields

    PubMed Central

    2016-01-01

    The transition between two distinct ionization mechanisms in femtosecond laser fields at 785 nm is observed for C60 molecules. The transition occurs in the investigated intensity range from 3 to 20 TW/cm2 and is visualized in electron kinetic energy spectra below the one-photon energy (1.5 eV) obtained via velocity map imaging. Assignment of several observed broad spectral peaks to ionization from superatom molecular orbitals (SAMOs) and Rydberg states is based on time-dependent density functional theory simulations. We find that ionization from SAMOs dominates the spectra for intensities below 5 TW/cm2. As the intensity increases, Rydberg state ionization exceeds the prominence of SAMOs. Using short laser pulses (20 fs) allowed uncovering of distinct six-lobe photoelectron angular distributions with kinetic energies just above the threshold (below 0.2 eV), which we interpret as over-the-barrier ionization of shallow f-Rydberg states in C60. PMID:27934203

  19. Strong field radio-frequency measurements using Rydberg states in a vapor cell

    NASA Astrophysics Data System (ADS)

    Miller, Stephanie; Anderson, David; Raithel, Georg

    2016-05-01

    There has been a growing interest in using electromagnetically induced transparency with Rydberg atoms in a room-temperature vapor cell as an all-optical readout method for measuring microwave electric fields. We present results from RF-modulating the 60S1 / 2 and 58D5 / 2 Rydberg states of rubidium with 50 MHz and 100 MHz fields, respectively. Weak RF fields AC Stark-shifts the Rydberg states. As the field strength is increased, sidebands appear at even multiples of the driving frequency. When strong fields are applied, the nearby hydrogenic manifold begins to intersect with the shifted levels. Similar investigations have been performed in cesium. Due to the significant amount of state mixing and level structure, Floquet theory is required to describe the level shifts and mixing. By comparing the calculation with the experimental data, we obtain an absolute determination of the RF electric field reaching a maximum field of 296 V/m to within +/- 0 . 35 % . Additionally, we estimate the shielding of DC fields within the vapor cell.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2016-04-14

    We report an ab initio study of the quintet states of molecular oxygen. The calculations are carried out employing the multireference single and double excitation configuration interaction package. Potential energy curves of the six quintet valence states dissociating into ground state atoms and of the four quintet states dissociating to ion-pair atoms were computed. A number of bound quintet Rydberg series converging to the a(4)Πu and b(4)Σg(-) states of the O2(+) cation have been identified.

  2. Imaging the photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states

    PubMed Central

    Marggi Poullain, Sonia; Chicharro, David V.; Zanchet, Alexandre; González, Marta G.; Rubio-Lago, Luis; Senent, María L.; García-Vela, Alberto; Bañares, Luis

    2016-01-01

    The photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states have been studied using velocity map and slice ion imaging in combination with pump-probe nanosecond laser pulses. The reported translational energy and angular distributions of the H(2S) photofragment detected by (2+1) REMPI highlight different dissociation mechanisms for the 3s and 3pz Rydberg states. A narrow peak in the translational energy distribution and an anisotropic angular distribution characterizes the fast 3s photodissociation, while for the 3pz state Boltzmann-type translational energy and isotropic angular distributions are found. High level ab initio calculations have been performed in order to elucidate the photodissociation mechanisms from the two Rydberg states and to rationalize the experimental results. The calculated potential energy curves highlight a typical predissociation mechanism for the 3s state, characterized by the coupling between the 3s Rydberg state and a valence repulsive state. On the other hand, the photodissociation on the 3pz state is initiated by a predissociation process due to the coupling between the 3pz Rydberg state and a valence repulsive state and constrained, later on, by two conical intersections that allow the system to relax to lower electronic states. Such mechanism opens different reaction pathways leading to CH2 photofragments in different electronic states and inducing a transfer of energy between translational and internal modes. PMID:27296907

  3. State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Xueming

    In this review, a few examples of state-to-state dynamics studies of both unimolecular and bimolecular reactions using the H-atom Rydberg tagging TOF technique were presented. From the H2O photodissociation at 157 nm, a direction dissociation example is provided, while photodissociation of H2O at 121.6 has provided an excellent dynamical case of complicated, yet direct dissociation process through conical intersections. The studies of the O(1D) + H2 → OH + H reaction has also been reviewed here. A prototype example of state-to-state dynamics of pure insertion chemical reaction is provided. Effect of the reagent rotational excitation and the isotope effect on the dynamics of this reaction have also been investigated. The detailed mechanism for abstraction channel in this reaction has also been closely studied. The experimental investigations of the simplest chemical reaction, the H3 system, have also been described here. Through extensive collaborations between theory and experiment, the mechanism for forward scattering product at high collision energies for the H + HD reaction was clarified, which is attributed to a slow down mechanism on the top of a quantized barrier transition state. Oscillations in the product quantum state resolved different cross sections have also been observed in the H + D2 reaction, and were attributed to the interference of adiabatic transition state pathways from detailed theoretical analysis. The results reviewed here clearly show the significant advances we have made in the studies of the state-to-state molecular reaction dynamics.

  4. Electron capture into large-l Rydberg states of multiply charged ions escaping from solid surfaces

    NASA Astrophysics Data System (ADS)

    Nedeljković, N.; Nedeljković, Lj.; Mirković, M.

    2003-07-01

    We have investigated the electron capture into large-l Rydberg states of multiply charged ionic projectiles (e.g., the core charges Z=6, 7, and 8) escaping solid surfaces with intermediate velocities (v≈1 a.u.) in the normal emergence geometry. A model of the nonresonant electron capture from the solid conduction band into the moving large angular-momentum Rydberg states of the ions is developed through a generalization of our results obtained previously for the low-l cases (l=0, 1, and 2). The model is based on the two-wave-function dynamics of the Demkov-Ostrovskii type. The electron exchange process is described by a mixed flux through a moving plane (“Firsov plane”), placed between the solid surface and the ionic projectile. Due to low eccentricities of the large-l Rydberg systems, the mixed flux must be evaluated through the whole Firsov plane. It is for this purpose that a suitable asymptotic method is developed. For intermediate ionic velocities and for all relevant values of the principal quantum number n≈Z, the population probability Pnl is obtained as a nonlinear l distribution. The theoretical predictions concerning the ions S VI, Cl VII, and Ar VIII are compared with the available results of the beam-foil experiments.

  5. 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

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

    PubMed

    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 (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 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 (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.

  7. Static and dynamic polarizability for C{sup 2+} in Rydberg states

    SciTech Connect

    Stancalie, V.

    2015-07-15

    This work presents results from a non-perturbative calculation of dynamic polarizability of C III ions in 1s{sup 2}2sns ({sup 1}S{sup e}) Rydberg states. We employ a two-state model for dressed atomic states to investigate the effect of the frequency-dependent polarizability of optically dressed 1s{sup 2}2sns({sup 1}S{sup e}) states (n = 5 − 12) on transitions to nearby states (1s{sup 2}2pns({sup 1}P{sub 1}{sup o})). 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 1s{sup 2}2sns ({sup 1}S) Rydberg states, embedded in the electric dipole field of the 2s – 2p core transition in Li-like C{sup 3+} 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 C{sup 2+} ground state and the C{sup 3+} 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.

  8. Integral Cross Sections for Electron Impact Excitation of Rydberg and Valence States of Molecular Nitrogen

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    We present integral cross sections (ICSs) for electron impact excitation of N2 out of the ground state X (v=0), to the b, c3, o3, b', c'4, G, and F electronic states at incident energies ranging between 17.5 eV and 100 eV. The ICSs were derived from the differential cross sections (DCSs) of Khakoo et al. [Phys. Rev. A 77, 012704 (2008)], which were obtained by unfolding energy loss spectra in the ˜12-13.82 eV range. Recently, Heays et al. [Phys. Rev. A 85, 012705 (2012)] measured comparable higher resolution energy loss spectra, with a significantly different apparatus configuration, but in agreement with the Khakoo et al. (2008) spectra. This latter additional effort provided further confidence in the accuracy of the DCSs upon which the present ICS results are based. Of the higher-lying states studied, five are singlet states that radiate to the ground state via dipole allowed transitions. These include the b and b' valence states and the c'4 Rydberg state that give rise to the Birge-Hopfield I, II, and Carroll-Yoshino bands, respectively, all of which are observed in the atmospheres of Earth, Titan, and Triton. The c3 and o3 Rydberg states give rise to the Worley-Jenkins and Worley series of Rydberg bands, respectively. However, these emissions are not readily observed since predissociation for the c3 and o3 states approaches 100%. As such, direct electron excitation measurements, such as those presented here are superior to standard (spontaneous) emission based measurements in this case.

  9. The 3d Rydberg (3A2) electronic state observed by Herzberg and Shoosmith for methylene

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yukio; Schaefer, Henry F., III

    1997-06-01

    In 1959 and 1961 Herzberg and Shoosmith reported the vacuum ultraviolet spectrum of the triplet state of CH2. The present study focuses on a characterization of the upper state, the 3d Rydberg (3A2) state, observed at 1415 Å. The theoretical interpretation of these experiments is greatly complicated by the presence of a lower-lying 3A2 valence state with a very small equilibrium bond angle. Ab initio electronic structure methods involving self-consistent-field (SCF), configuration interaction with single and double excitations (CISD), complete active space (CAS) SCF, state-averaged (SA) CASSCF, coupled cluster with single and double excitations (CCSD), CCSD with perturbative triple excitations [CCSD(T)], CASSCF second-order (SO) CI, and SACASSCF-SOCI have been employed with six distinct basis sets. With the largest basis set, triple zeta plus triple polarization with two sets of higher angular momentum functions and three sets of diffuse functions TZ3P(2 f,2d)+3diff, the CISD level of theory predicts the equilibrium geometry of the 3d Rydberg (3A2) state to be re=1.093 Å and θe=141.3 deg. With the same basis set the energy (Te value) of the 3d Rydberg state relative to the ground (X˜ 3B1) state has been determined to be 201.6 kcal mol-1 (70 500 cm-1) at the CCSD (T) level, 200.92kcal mol-1 (70 270 cm-1) at the CASSCF-SOCI level, and 200.89kcal mol-1 (70 260 cm-1) at the SACASSCF-SOCI level of theory. These predictions are in excellent agreement with the experimental T0 value of 201.95 kcalmol-1 (70 634 cm-1) reported by Herzberg.

  10. A sensitive electrometer based on a Rydberg atom in a Schrödinger-cat state.

    PubMed

    Facon, Adrien; Dietsche, Eva-Katharina; Grosso, Dorian; Haroche, Serge; Raimond, Jean-Michel; Brune, Michel; Gleyzes, Sébastien

    2016-07-14

    Fundamental quantum fluctuations caused by the Heisenberg principle limit measurement precision. If the uncertainty is distributed equally between conjugate variables of the meter system, the measurement precision cannot exceed the standard quantum limit. When the meter is a large angular momentum, going beyond the standard quantum limit requires non-classical states such as squeezed states or Schrödinger-cat-like states. However, the metrological use of the latter has been so far restricted to meters with a relatively small total angular momentum because the experimental preparation of these non-classical states is very challenging. Here we report a measurement of an electric field based on an electrometer consisting of a large angular momentum (quantum number J ≈ 25) carried by a single atom in a high-energy Rydberg state. We show that the fundamental Heisenberg limit can be approached when the Rydberg atom undergoes a non-classical evolution through Schrödinger-cat states. Using this method, we reach a single-shot sensitivity of 1.2 millivolts per centimetre for a 100-nanosecond interaction time, corresponding to 30 microvolts per centimetre per square root hertz at our 3 kilohertz repetition rate. This highly sensitive, non-invasive space- and time-resolved field measurement extends the realm of electrometric techniques and could have important practical applications: detection of individual electrons in mesoscopic devices at a distance of about 100 micrometres with a megahertz bandwidth is within reach.

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

    NASA Astrophysics Data System (ADS)

    Cockett, Martin C.; Watkins, Mark J.

    2004-01-01

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

  12. Unexpectedly broad photoelectron spectrum as a signature of ultrafast electronic relaxation of Rydberg states of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Adachi, Shunsuke; Sato, Motoki; Suzuki, Toshinori; Grebenshchikov, Sergy Yu.

    2017-03-01

    The dynamics of CO2 excited into Rydberg states lying 0.2 eV below the ionization threshold is studied by means of time resolved photoelectron imaging. Over 3 eV broad photoelectron spectra are measured for all pump-probe delay times. Quantum mechanical calculations demonstrate that the spectral broadening is due to ultrafast electronic relaxation of Rydberg states and identify the likely relaxation pathways. Experiment and theory bracket the relaxation time between 15 and 65 fs. A weak time independent ionization signal is attributed to CO2 trapped in near-threshold triplet states.

  13. Evolution of Rydberg states in half-cycle pulses: Classical, semiclassical, and quantum dynamics

    SciTech Connect

    Burgdoerfer, J.; Reinhold, C. |

    1994-12-31

    We summarize recent theoretical advances in the description of the evolution of Rydberg atoms subject to ultrashort pulses extending only a fraction of an optical cycle. We have performed classical. semiclassical and full quantum calculations in order to delineate the classical-quantum correspondence for impulsively perturbed atomic systems. We observe classical and quantum (or semiclassical) oscillations in excitation and ionization which depend on the initial state of atoms and on the strength of the perturbation. These predictions can be experimentally tested. 4 figs.

  14. The Stark effect in atomic Rydberg states through a quantum defect approach

    NASA Astrophysics Data System (ADS)

    Menéndez, J. M.; Martín, I.; Velasco, A. M.

    A basis set of quantum defect orbitals (QDOs) has been adopted for the diagonalization of the Hamiltonian matrix of nonhydrogenic atoms in the presence of an external electric field, so that the Stark structure of the Rydberg states has been possible to determine. The presently obtained Stark maps are in excellent agreement with those resulting from theory and experiment, as reported in the literature for a few representative atoms. The adequacy of the Stark quantum defect orbital (SQDO) procedure for accurately dealing with properties related to the Stark effect in atoms is suggested.

  15. Observation of Superradiance in Mmwave Spectroscopy of Rydberg States: Bad is the New Good

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The 106 increase in spectral velocity allowed by the combination of chirped pulse millimeter-wave spectroscopy with a buffer gas cooled molecular beam source qualitatively expands the classes of possible experiments. As an example, it allows for investigation of cooperative radiation effects (such as superradiance and subradiance) in large samples of atoms in Rydberg states in a single shot. However, these same effects can present obstacles to the application of the full increase in spectral velocity to high-resolution spectroscopic experiments through both frequency (chirps, broadenings, and shifts) and intensity effects.

  16. Energy shift and state mixing of Rydberg atoms in ponderomotive optical traps

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Robicheaux, F.

    2016-08-01

    We present a degenerate perturbation analysis in the spin-orbit coupled basis for Rydberg atoms in an optical trap. The perturbation matrix is found to be nearly the same for two states with the same total angular momentum j, and orbital angular momentum number l differing by 1, The same perturbation matrices result in the same state-mixing and energy shift. We also study the dependence of state mixing and energy shift on the periodicity and symmetry of the ponderomotive potentials induced by different optical traps. State mixing in a one-dimensional lattice formed with two counterpropagating Gaussian beams is studied and yields a state-dependent trap depth. We also calculate the state-mixing in an optical trap formed by four parallel, separated and highly focused Gaussian beams.

  17. 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).

  18. Simulation study of Rydberg atomic states interacting with electromagnetic radiation for use in future technological applications

    NASA Astrophysics Data System (ADS)

    Zou, Yi

    The present work involves the study of a simplified atomic system to gain better understanding of controlling and manipulating Rydberg-like systems. Detailed simulations of the classical hydrogen atom have been carried out using, first, the nonrelativistic Lorentz-Dirac classical equation of motion for a charged point particle under the action of a Coulombic binding force, plus applied radiation, then progressing to include the effects of the classical electromagnetic zero-point (ZP) radiation spectrum. This work has been carried out under the guide of the theory called stochastic electrodynamics (SED). Many applications involving atoms in excited Rydberg states can be developed, based on the work described here, to aid in carefully controlled thin film deposition, ion implantation, etching, and sputtering in micro and nanoelectronics, as well as optical instrumentation related applications, via applied electromagnetic fields. The improved simulation code for the long-term numerical integration of non-linear differential equations for tracking particles, should be helpful for a number of other closely related areas. Specifically, investigations into astronomy, including the Kepler problem treated in satellite and planetary orbit simulations in celestial mechanics, as well as problems in such areas as atomic and molecular dynamic studies, may well find benefit from the investigations here. As shown in the present study, very nonlinear behavior occurs for such Rydberg-like system, making a numerical study of the system nearly essential. Little of this work has been explored before in the literature. Resonances, rapid transitions, very long decay times, all influenced by applied radiation, are described and analyzed in detail here. Such results are expected to have significant bearing on recent experiments reported in the literature on "kicked Rydberg" atoms. Moreover, as reported here, the ZP field was included in very lengthy numerical simulations, resulting in a

  19. Molecular detection using Rydberg, autoionizing, and cluster states. Progress report

    SciTech Connect

    Wessel, J.

    1989-08-17

    Continuing investigations of multiphoton ionization processes in naphthalene have established the geometry and spectroscopy of trimer and tetramer cluster states. A new, highly efficient ionization mechanism has been identified in the trimer. It is closely related to autoionization of 2-electron atoms by resonant 2-photon excitation and to exciton fusion in larger clusters.

  20. Prospects of charged-oscillator quantum-state generation with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Stevenson, Robin; Minář, Jiří; Hofferberth, Sebastian; Lesanovsky, Igor

    2016-10-01

    We explore the possibility of engineering quantum states of a charged mechanical oscillator by coupling it to a stream of atoms in superpositions of high-lying Rydberg states. Our scheme relies on the driving of a two-phonon resonance within the oscillator by coupling it to an atomic two-photon transition. This approach effectuates a controllable open system dynamics on the oscillator that in principle permits versatile dissipative creation of squeezed and other nonclassical states which are central to sensing applications or for studies of fundamental questions concerning the boundary between classical and quantum-mechanical descriptions of macroscopic objects. We show that these features survive thermal coupling of the oscillator with the environment. We perform a detailed feasibility study finding that current state-of-the-art parameters result in atom-oscillator couplings which are too weak to efficiently implement the proposed oscillator state preparation protocol. Finally, we comment on ways to circumvent the present limitations.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  2. Theoretical calculations on electronic transitions for H/sub 3/, including Rydberg and transition state spectra

    SciTech Connect

    Petsalakis, I.D.; Theodorakopoulos, G.; Wright, J.S.

    1988-12-01

    MRD-CI calculations have been carried out on the ground and excited electronic states of H/sub 3/ for D/sub 3//sub h/, D/sub infinity//sub h/, C/sub infinity//sub v/, and C/sub 2//sub v/ geometries. Dipole transition moments between the various electronic states have been also obtained at the different geometries calculated. The present work provides accurate theoretical information relevant to the transition state spectroscopy of H+H/sub 2/ along a collinear path and also along a perpendicular path. In addition, the present work is the first all-electron configuration interaction treatment of the Rydberg states of H/sub 3/, and the results are in excellent agreement with the observed spectra.

  3. Combined theoretical and experimental study of the valence, Rydberg and ionic states of fluorobenzene

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    New photoelectron spectra (PES) and ultra violet (UV) and vacuum UV (VUV) absorption spectra of fluorobenzene recorded at higher resolution than previously, have been combined with mass-resolved (2 + 1) and (3 + 1) resonance enhanced multiphoton ionization (REMPI) spectra; this has led to the identification of numerous Rydberg states. The PES have been compared with earlier mass-analyzed threshold ionization and photoinduced Rydberg ionization (PIRI) spectra to give an overall picture of the ionic state sequence. The analysis of these spectra using both equations of motion with coupled cluster singles and doubles (EOM-CCSD) configuration interaction and time dependent density functional theory (TDDFT) calculations have been combined with vibrational analysis of both the hot and cold bands of the spectra, in considerable detail. The results extend several earlier studies on the vibronic coupling leading to conical intersections between the X2B1 and A2A2 states, and a further trio (B, C, and D) of states. The conical intersection of the X and A states has been explicitly identified, and its structure and energetics evaluated. The energy sequence of the last group is only acceptable to the present study if given as B2B2states forces reconsideration of the nature of the PIRI spectrum. The coupling between these two states is induced by the a2 modes, ν12 and ν14 and we propose that the 141 band is observed in the B2B2 band in the PES for the first time, because of the improved resolution. This same assignment is given to the lowest energy band in the PIRI spectrum which was previously assigned as the origin band and further conclude that the entire PIRI spectrum is induced by ν12 and ν14. The relative intensities of the various Rydberg state peaks in the VUV absorption and REMPI spectra of fluorobenzene are very similar to

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

    NASA Astrophysics Data System (ADS)

    Fang, Zheng-Hua

    2016-01-01

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

  5. Where Millimeter Wave Spectra are Sensitive to Small Electric Fields: High Rydberg States of Xenon and Their Hyperfine Structures

    NASA Astrophysics Data System (ADS)

    Schäfer, Martin; Raunhardt, Matthias; Merkt, Frédéric

    2009-06-01

    In the range 0-45 cm^{-1} below the ionization limit, the separation between adjacent electronic states (Rydberg states with principal quantum number n>50) of atoms and molecules is smaller than 2 cm^{-1}. In order to resolve the fine or hyperfine structure of these states, it is necessary to combine high-resolution vacuum ultraviolet (VUV) laser radiation, which is required to access the Rydberg states from the ground state, with millimeter wave radiation. Such double-resonance experiments have been used to study the hyperfine structure of high Rydberg states of ^{83}Kr, H_2 or D_2. Millimeter wave transitions (240-350 GHz) between nℓ (52≤ n≤64, ℓ≤3) Rydberg states of different xenon isotopes were detected by pulsed field ionization followed by mass-selective detection of the cations. Because of the high polarizability of high-n Rydberg states (∝ n^7, ˜10^4 MHz cm^{2} V^{-2} for n≈ 50), it is necessary to reduce the electric stray fields to values of the order of mV/cm (or less) in order to minimize the (quadratic) Stark shift of the millimeter wave transitions. Some p and d Rydberg states of Xe are nearly degenerate and efficiently mixed by small stray fields, making it possible to observe transitions forbidden by the Δℓ=±1 selection rule or transitions exhibiting a linear Stark effect, which is typical for the degenerate high-ℓ Rydberg states. Multichannel quantum defect theory (MQDT) was used to analyze the millimeter wave data and to determine the hyperfine structures of the ^2P_{3/2} ground electronic states of ^{129}Xe^+ and ^{131}Xe^+. C. Fabre, P. Goy, S. Haroche, J. Phys. B: Atom. Mol. Phys. 10, L183-189 (1977). F. Merkt, A. Osterwalder, Int. Rev. Phys. Chem. 21, 385-403 (2002). M. Schäfer, M. Andrist, H. Schmutz, F. Lewen, G. Winnewisser, F. Merkt, J. Phys. B: At. Mol. Opt. Phys. 39, 831-845 (2006) M. Schäfer, F. Merkt, Phys. Rev. A, 74, 062506 (2006). A. Osterwalder, A. Wüest, F. Merkt, Ch. Jungen, J. Chem. Phys., 121, 11810

  6. Double-resonance spectroscopy of the high Rydberg states of HCO. I. A precise determination of the adiabatic ionization potential

    NASA Astrophysics Data System (ADS)

    Mayer, Eric; Grant, Edward R.

    1995-12-01

    We report the first spectroscopic observation of the high Rydberg states of HCO. Individual lines in a system of vibrationally autoionizing Rydberg series converging to the (010) state of HCO+ are rotationally labeled in a double-resonance excitation scheme that uses resolved levels in the (010) A' vibronic component of the 3pπ 2Π Rydberg state as intermediates. Observed high-Rydberg structure extends from the adiabatic ionization threshold—which falls just below the principal quantum number of 12 in the vibrationally excited series—to the (010) vertical threshold. Elements of a single series extending from n=12 to 50, for which the total angular momentumless spin can be assigned as N=1, are extrapolated to obtain a vertical convergence limit with respect to the 3pπ 2Π(010)A' N'=0 intermediate state of 20 296.9±0.3 cm-1. Referring this transition energy to the ground state, and subtracting the precisely known fundamental bending frequency of the cation, establishes the adiabatic ionization potential corresponding to the transition from HCO 2A'(000) J″=0, K″=0 to HCO+ J+=0 1Σ+(000). The result is 65 735.9±0.5 cm-1 or 8.150 22±0.000 06 eV.

  7. Helium resources of the United States, 1989. Information Circular/1990

    SciTech Connect

    Miller, R.D.; Hamak, J.E.

    1990-01-01

    The helium resources base of the United States was estimated by the Bureau of Mines to be 894.6 Bcf as of January 1, 1989. These resources are divided into four categories in decreasing degree of the assurance of their existence: (1) helium in storage and in proved natural gas reserves, 282.4 Bcf, (2) helium in probable natural gas resources, estimated at 237.7 Bcf, (3) helium in possible natural gas resources, estimated to be 263.1 Bcf, and (4) helium in speculative natural gas resources, 111.4 Bcf. These helium resources are further divided into depleting and nondepleting, with the helium in storage being in a separate classification. The depleting resources are those associated with natural gasfields that are, or will be, produced for the natural gas they contain. Almost all of the helium in potential (probable, possible, and speculative) natural gas resources is included in this classification. These depleting resources are estimated to contain 775 Bcf of the total helium resource base.

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

    SciTech Connect

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

    2014-12-21

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

  9. Pulsed-field ionization spectroscopy of high Rydberg states (n=50-200) of bis(ɛ6-benzene)chromium

    NASA Astrophysics Data System (ADS)

    Choi, Kyo-Won; Choi, Sunyoung; Baek, Sun Jong; Kim, Sang Kyu

    2007-01-01

    The ionization behavior of the high Rydberg states of bis(η6-benzene)chromium in the presence of ac and/or dc fields has been explored. The application of an ac scrambling field at the time of laser excitation lengthens the lifetime of the Rydberg state by almost two orders of magnitude. The lifetime enhancement by the scrambling field is much more effective for n <100 than it is for n >100 Rydberg states. The pulsed-field ionization of Rydberg states of n <100 shows the typical diabatic ionization behavior for low n. The two distinct ionization behaviors observed for the relatively low (n=50-100) and high (n=100-200) Rydberg states suggest that the former originate from the optically accessed nf Rydberg series, whereas the latter are due to np Rydberg series. Based on the understanding of the ionization behavior of bis(η6-benzene)chromium, the accurate ionization potential is deduced to give IP =5.4665±0.0003eV. Optimization of the various electric field conditions greatly enhances the spectral sensitivity of the mass-analyzed threshold ionization (MATI) spectroscopy. The high-resolution MATI spectrum of the title molecule obtained here provides precise cationic vibrational frequencies for many skeletal and benzene ring modes. A number of vibrational modes are newly identified, and the ambiguity regarding to some mode assignments is now clearly resolved through the Frank-Condon analysis based on ab initio calculations.

  10. Formation rate for Rb 2 + molecular ions created in collisions of Rb Rydberg and ground-state atoms

    NASA Astrophysics Data System (ADS)

    Stanojevic, Jovica; Côté, Robin

    2016-05-01

    We calculate the formation rate of the molecular Rb2+ion in its various bound states produced in the associative ionization of a Rydberg and a ground-state atom. Before the formation takes place, the colliding atoms are accelerated by an attractive force between the collision partners. In this way the ground-state atom is first captured by the Rydberg electron and then guided towards the positive ion-core where a molecular ion is subsequently formed. As recently demonstrated, this process results in giant collisional cross sections for the molecular ion formation, with the cross sections essentially determined by the size of the Rydberg atom. For sufficient high principal quantum numbers and atomic densities, many ground-state atoms are already located inside the Rydberg atom and ready to participate in the associative ionization. The same process can occur between a Rydberg and a ground-state atom that form a long-range Rydberg molecule, possibly contributing to the shortening of the lifetimes of Rydberg atoms and molecules. Partial support from the US Army Research Office (ARO-MURI W911NF-14-1-0378), and from NSF (Grant No. PHY-1415560).

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  12. The role of high Rydberg states in the generation of negative ions in negative-ion discharges

    SciTech Connect

    Hiskes, J.R.

    1995-11-28

    The generation of substantial yields of H{sup {minus}} ions in a laser excited H{sub 2} gas has been reported by Pinnaduwage and Christoforu. These H{sup {minus}} yields have been attributed to (2 + 1) REMP photoexcitation processes leading to dissociative attachment of doubly-excited or superexcited states (SES), or dissociative attachment of high Rydberg product states. The new feature of these experiments is the implied large dissociative attachment rates, of order 10{sup {minus}6} cm{sup 3} sec{sup {minus}1}, values that are orders-of-magnitude larger than the dissociative attachment of the vibrationally excited levels of the ground electronic state. While these laser excitations are not directly applicable to a hydrogen negative-ion discharge, the implication of large dissociative attachment rates to the high Rydberg states may affect both the total negative-ion density and the interpretation of discharge performance. Within the discharge energetic electrons will collisionally excite the higher Rydberg states, and the relative contribution of the dissociative attachment of these states when compared with the dissociative attachment to the ground state vibrational levels, is the topic of this paper.

  13. 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.

  14. Electron Capture from Linear Stark Rydberg States above the Matching Velocity

    NASA Astrophysics Data System (ADS)

    Ciocca, M.; Creasey, C.; MacAdam, K. B.

    1998-05-01

    The relative cross section for electron capture by singly charged ions from linear Stark Rydberg states of Na has been measured, both as a function of the angle of impact and of projectile velocity. The target, the topmost state of the n = 24 Stark manifold, was prepared by two-step laser excitation from the Na ground state, via 3p_3/2, in an electric field F_Stark= 160 V/cm. By means of a device perfected in our laboratory (the "Stark Barrel"), we aligned the target by adiabatically switching the electric field, after excitation, down to a preset low value and a desired direction in the plane determined by the ion and Na beams. Thermionic emission ion sources of Li and Na were operated at accelerating voltages 400-2000 V to allow study of electron capture in the reduced velocity range v = 1.0 - 2.5. This augments an earlier study by Homan footnote D. M. Homan, Ph. D. Dissertation, University of Kentucky 1997, unpublished. at lower velocities.

  15. 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.

  16. State selective Rydberg charge transfer and ionization in low energy ion-atom collisions

    NASA Astrophysics Data System (ADS)

    Perumal, A. N.; Tripathi, D. N.

    1998-10-01

    The Classical Trajectory Monte Carlo (CTMC) simulation method with a core modified interaction potential has been used to study the single charge transfer in Na +and Ar + ions colliding with a variety of state selected Na Rydberg atom targets ( n=24, 28, 33, 40 and l=2) in the reduced velocity region v=0.2-2.0. The experimentally observed structures in the total capture cross section versus reduced velocity curves are reproduced by CTMC method. The n-distribution of final capture state has got two peaks viz. first one at nf= ni and the second one at a higher nf depending on the initial angular momentum in the velocity regime 0.4-0.6. These structures have been explained in terms of quasimolecular-ion formation and a classical model proposed by Roy et al. (B.N. Roy, D.N. Tripathi, D.K. Rai, Phys. Rev. A 5 (1972) 1252). The CTMC ionization cross section results are benchmarked with the recent experimental measurement of Makarov et al. (O.P. Makarov, D.M. Homan, O.P. Sorokina, K.B. MacAdam, in: F. Aumayr, G. Betz, H.P. Winter (Eds.), Proceedings of the 20th International Conference on the Physics of Electronics and Atomic Collisions, Vienna, 1997, p. FR052) for Na +-Na(24 d).

  17. Dynamics of Bloch State Positronium Emission from MOF Targets Studied via Rydberg TOF Spectroscopy

    NASA Astrophysics Data System (ADS)

    Piñeiro Escalera, Alina; Jones, Adric; Mills, Allen

    2016-05-01

    Recent advances in the efficient production and detection of Rydberg positronium (Ps) have made it possible to perform energy- and angle- resolved time-of-flight (TOF) spectroscopy with Ps. We report here TOF measurements of Ps emission from the metal-oxide framework (MOF) targets, MOF-5 and ZIF-8. MOFs are a recently synthesized class of chemical structures, characterized by high long-range order and large surface area to volume ratios (i.e., they are highly porous and uniform, crystalline materials). Ps is found to be emitted predominantly in a series of monoenergetic peaks, providing clear evidence of Ps Bloch states. Measuring the relative populations of the monoenergetic peaks, as a function of implantation energy and target temperature, provides insight into the target-dependent dynamics of Bloch state Ps. Work supported by the U.S. National Science Foundation Grants No. PHY 1206100 and No. PHY 1040590 and the National Science Foundation Graduate Research Fellowship Progam (NSF-GRFP). DOE BES DE-FG02-13ER46972 (MOF-5 synthesis and characterization).

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

    SciTech Connect

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

    2013-06-28

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

  19. Absolute cross-section measurements for ionization of He Rydberg atoms in collisions with K

    NASA Astrophysics Data System (ADS)

    Deng, F.; Renwick, S.; Martínez, H.; Morgan, T. J.

    1995-11-01

    Absolute cross sections for ionization of 1.5-10.0 keV/amu Rydberg helium atoms in principal quantum states 12<=n<=15 due to collisions with potassium have been measured. The data are compared with the free-electron cross section at equal velocity. Our results for the collisional ionization cross sections (σi) agree both in shape and absolute magnitude with the data available for the total electron-scattering cross sections (σe) and support recent theoretical models for ionization of Rydberg atoms with neutral perturbers.

  20. Rydberg atom spectroscopy enabled by blackbody radiation ionization

    SciTech Connect

    Lu Xiaoxu; Sun Yuan; Metcalf, Harold

    2011-09-15

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

  1. Rydberg series for quartet states of Li-like sulfur ion

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Sang, CuiCui; Hu, Feng; Qian, XinYu; Liu, DongDong; Mei, MaoFei; Gou, BingCong

    2017-01-01

    The energy levels and transition parameters of Li-like quartet states 1s2snl and 1s2pnl‧ (l=s, p, d; l‧=s, p, d, f; n=2-7) pertaining to 4Po and 4Le (L=S, P, D) Rydberg series in S13+ ion are calculated using a multi-configuration Rayleigh-Ritz variation method. Relativistic effects and mass polarization contributions are taken into account by using the first-order perturbation theory. The quantum electrodynamics (QED) effects and higher-order relativistic corrections are considered to obtain accurate energy levels by the screened hydrogenic formula. The transition oscillator strengths, transition rates, and wavelengths of electric-dipole transitions for 1s2sns4Se-1s2lnl‧ 4Po and 1s2snp+1s2pns+1s2pnd4Po-1s2lnl‧ 4Le (L=S, P, D) in S13+ ion are systematically calculated and compared with available reference data. Our calculated results will provide valuable data for related experiments in the future.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    SciTech Connect

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

    2015-12-15

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

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

    SciTech Connect

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

    1994-03-14

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

  5. 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…

  6. Highly Excited States of cs Atoms on Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Lackner, F.; Theisen, M.; Koch, M.; Ernst, W. E.

    2011-06-01

    Cs atoms on the surface of helium nanodroplets have been excited to high lying nS (n = 8-11), nP (n = 8-11), and nD (n = 6-10) levels. A two-step excitation scheme via the 62P1/2(2Π1/2) state using two cw lasers was applied. This intermediate state has the advantage that a large fraction of the excited Cs atoms does not desorb from the helium nanodroplets. An absorption spectrum was recorded by detecting laser induced fluorescence light from the 62P3/2→62S1/2 transition. The pseudo-diatomic model for helium nanodroplets doped with single alkali-metal atoms holds for the observed spectrum. An investigation of spectral trends shows that the n'2P(Π)←62P1/2(2Π1/2) and n'2D(Δ)←62P1/2(2Π1/2) (n' > 9) transitions are lower in energy than the corresponding free-atom transitions. This indicates that the Cs*--HeN potential becomes attractive for these highly excited states. Our results suggest a possibility of generating an artificial super-atom with a positive ion core inside a helium nanodroplet and the electron outside, which will be subject to future experiments. M. Theisen, F. Lackner, F. Ancilotto, C. Callegari, and W.E. Ernst, Eur. Phys. J. D 61, 403-408 (2011)

  7. 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 Hróðmarsson, Helgi; Kvaran, Ágúst

    2015-04-28

    Photoexcitation dynamics of the E((1)Σ(+)) (v' = 0) Rydberg state and the V((1)Σ(+)) (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)Π3/2) or HBr(+)*((2)Π1/2) 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.

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

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rick; Hazzard, Kaden

    2015-05-01

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

  9. Electric potential invariants and ions-in-molecules effective potentials for molecular Rydberg states

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    The dependence of multipole moments and polarizabilities on external fields appears in many applications including biomolecular molecular mechanics, optical non-linearity, nanomaterial calculations, and the perturbation of spectroscopic signatures in atomic clocks. Over a wide range of distances, distributed multipole and polarizability potentials can be applied to obtain the variation of atom-centered atoms-in-molecules electric properties like bonding-quenched polarizability. For cylindrically symmetric charge distributions, we examine single-center and atom-centered effective polarization potentials in a non-relativistic approximation for Rydberg states. For ions, the multipole expansion is strongly origin-dependent, but we note that origin-independent invariants can be defined. The several families of invariants correspond to optimized representations differing by origin and number of terms. Among them, a representation at the center of dipole polarizability optimizes the accuracy of the potential with terms through 1/r4. We formulate the single-center expansion in terms of polarization-modified effective multipole moments, defining a form related to the source-multipole expansion of Brink and Satchler. Atom-centered potentials are an origin independent alternative but are limited both by the properties allowed at each center and by the neglected effects like bond polarizability and charge flow. To enable comparisons between single-center effective potentials in Cartesian or spherical form and two-center effective potentials with differing levels of mutual induction between atomic centers, we give analytical expressions for the bond-length and origin-dependence of multipole and polarizability terms projected in the multipole and polarizability expansion of Buckingham. The atom-centered potentials can then be used with experimental data and ab initio calculations to estimate atoms-in-molecules properties. Some results are given for BaF+ and HF showing the

  10. Electric potential invariants and ions-in-molecules effective potentials for molecular Rydberg states.

    PubMed

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

    2016-12-21

    The dependence of multipole moments and polarizabilities on external fields appears in many applications including biomolecular molecular mechanics, optical non-linearity, nanomaterial calculations, and the perturbation of spectroscopic signatures in atomic clocks. Over a wide range of distances, distributed multipole and polarizability potentials can be applied to obtain the variation of atom-centered atoms-in-molecules electric properties like bonding-quenched polarizability. For cylindrically symmetric charge distributions, we examine single-center and atom-centered effective polarization potentials in a non-relativistic approximation for Rydberg states. For ions, the multipole expansion is strongly origin-dependent, but we note that origin-independent invariants can be defined. The several families of invariants correspond to optimized representations differing by origin and number of terms. Among them, a representation at the center of dipole polarizability optimizes the accuracy of the potential with terms through 1/r(4). We formulate the single-center expansion in terms of polarization-modified effective multipole moments, defining a form related to the source-multipole expansion of Brink and Satchler. Atom-centered potentials are an origin independent alternative but are limited both by the properties allowed at each center and by the neglected effects like bond polarizability and charge flow. To enable comparisons between single-center effective potentials in Cartesian or spherical form and two-center effective potentials with differing levels of mutual induction between atomic centers, we give analytical expressions for the bond-length and origin-dependence of multipole and polarizability terms projected in the multipole and polarizability expansion of Buckingham. The atom-centered potentials can then be used with experimental data and ab initio calculations to estimate atoms-in-molecules properties. Some results are given for BaF(+) and HF showing the

  11. Doubly Excited Resonance States of Helium Atom: Complex Entropies

    NASA Astrophysics Data System (ADS)

    Kuroś, Arkadiusz; Kościk, Przemysław; Saha, Jayanta K.

    2016-12-01

    We provide a diagonal form of a reduced density matrix of S-symmetry resonance states of two electron systems determined under the framework of the complex scaling method. We have employed the variational Hylleraas type wavefunction to estimate the complex entropies in doubly excited resonance states of helium atom. Our results are in good agreement with the corresponding ones determined under the framework of the stabilization method (Lin and Ho in Few-Body Syst 56:157, 2015).

  12. Rovibrational-state-selected photoionization of acetylene by the two-color IR+VUV scheme: observation of rotationally resolved Rydberg transitions.

    PubMed

    Qian, X-M; Kung, A H; Zhang, Tao; Lau, K C; Ng, C Y

    2003-12-05

    We have demonstrated a rovibrational-state-selected photoionization experiment using an IR laser and high-resolution VUV-synchrotron radiation. The VUV photoionization of acetylene [C2H2(Xtilde; (1)Sigma(+)(g);nu(3)=1,J(')=8 or 10)] prepared by IR excitation reveals three strong autoionizing Rydberg series converging to C2H+2(Xtilde; (2)Pi(u);nu(+)(3)=1) with little ion background interference. Rotational transitions resolved for the Rydberg states provide an estimate of approximately 1.8 ps for their lifetimes. This experiment opens the way for state-selective photoionization studies of polyatomic molecules using VUV-synchrotron radiation.

  13. Rotationally Resolved Vacuum Ultraviolet Resonance-Enhanced Multiphoton Ionization (VUV REMPI) of Acetylene via the G̃ Rydberg State.

    PubMed

    Schmidt-May, Alice F; Grütter, Monika; Neugebohren, Jannis; Kitsopoulos, T N; Wodtke, Alec M; Harding, Dan J

    2016-07-14

    We present a 1 + 1' resonance-enhanced multiphoton ionization (REMPI) scheme for acetylene via the linear G̃ 4sσ (1)Πu Rydberg state, offering partial rotational resolution and the possibility to detect excitation in both the cis- and trans-bending modes. The resonant transition to the G̃ state is driven by a vacuum ultraviolet (VUV) photon, generated by resonant four-wave mixing (FWM) in krypton. Ionization from the short-lived G̃ state then occurs quickly, driven by the high intensity of the residual light from the FWM process. We have observed nine bands in the region between 79 200 cm(-1) and 80 500 cm(-1) in C2H2 and C2D2. We compare our results with published spectra in this region and suggest alternative assignments for some of the Renner-Teller split bands. Similar REMPI schemes should be applicable to other small molecules with picosecond lifetime Rydberg states.

  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

  15. Direct Observation of Rydberg-Rydberg Transitions via Cpmmw Spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Rydberg-Rydberg transitions of Ca atoms are directly observed by chirped-pulse millimeter-wave spectroscopy, which is a form of broadband, high-resolution, free induction decay-detected (FID) spectroscopy with accurate relative intensities. A new setup, a 20 K Neon buffer gas cooled molecular beam system, has been constructed and tested in our lab. The number density of our target molecules, BaF, is increased by a factor of >100 relative to a Smalley-type laser ablation supersonic beam source. In addition, the laboratory frame velocity is decreased by factor 10, which improves our spectroscopic resolution to better than 50 kHz FWHM at 100 GHz. The improved molecular beam source opens the door to an extension of the CPmmW spectroscopy from atomic Rydberg states to molecular Rydberg states. I expect to present preliminary data from ``pure electronic" spectra of BaF Rydberg molecules. We expect to produce 10^8 state-selected core-nonpenetrating Rydberg molecules in a single pulse of a laser-laser-mm-wave triple resonance excitation sequence.

  16. High-resolution millimeter wave spectroscopy and multichannel quantum defect theory of the hyperfine structure in high Rydberg states of molecular hydrogen H2

    NASA Astrophysics Data System (ADS)

    Osterwalder, A.; Wüest, A.; Merkt, F.; Jungen, Ch.

    2004-12-01

    Experimental and theoretical methodologies have been developed to determine the hyperfine structure of molecular ions from detailed studies of the Rydberg spectrum and have been tested on molecular hydrogen. The hyperfine structure in l=0-3 Rydberg states of H2 located below the X2Σg+(v+=0,N+=1) ground state of ortho H2+ has been measured in the range of principal quantum number n=50-65 at sub-MHz resolution by millimeter wave spectroscopy following laser excitation to np and nd Rydberg states using a variety of single-photon and multiphoton excitation sequences. The np11, nd11, and the nf10-3 Rydberg states were found to be metastable and to have lifetimes of more than 5 μs beyond n=50. Members of other series, such as the nd12, nd13, and the np10 series, were found to have lifetimes of more than 1 μs. Local perturbations induced by low-n Rydberg states belonging to series converging on rovibrationally excited levels of H2+ reduce the lifetimes in narrow ranges of n values. The hyperfine structure is strongly dependent on the value of the orbital angular momentum l. In the penetrating s and p states at n≈50 the exchange interaction dominates over the hyperfine interaction and the levels can be labeled by the total electron spin angular momentum quantum number S (S=0 or 1). In the less penetrating d and f Rydberg states, the hyperfine interaction between the core nuclear and electron spins is larger than the exchange interaction and the Rydberg states are of mixed singlet and triplet character. A procedure based on the Stark effect and on the systematic analysis of selection rules and combination differences was developed to determine the orbital and the total angular momentum quantum numbers l and F and to construct an energy map of p and f Rydberg levels between n=54 and 64 with relative positions of an accuracy of better than 1 MHz. Multichannel quantum defect theory (MQDT) was extended to treat the hyperfine structure in molecular Rydberg states and was

  17. Production of high-n strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    The photoexcitation of strontium Rydberg atoms with n ~ 300 is being examined using a crossed laser-atom beam approach to enable study of quasi-stable two-electron excited states and of strongly-coupled Rydberg systems.

  18. High-order harmonic and attosecond pulse generations from Rydberg state driven by the spatially inhomogeneous field

    NASA Astrophysics Data System (ADS)

    Feng, Liqiang; Li, Yi; Meng, Fanshun; Liu, Hang; Castle, R. S.

    2017-02-01

    High-order harmonic spectra and attosecond pulse generation from Rydberg atom (He+) driven by the spatially inhomogeneous field have been theoretically investigated. (i) Firstly, with an electron initially in a single excited Rydberg state (nth), the harmonic yield can be enhanced due to the decreased ionization potential, and a maximum enhancement can be obtained when the initial state is prepared as the third excited state (n = 3). However, the low cutoff energy from the excited state is unbeneficial to the generation of the higher photon pulse. Thus, with the further introduction of the laser chirp, not only the harmonic cutoff is extended, but also the harmonic modulation is reduced. As a result, five super-bandwidths from 63 eV to 267 eV can be found. (ii) Secondly, by preparing the initial state as a coherent superposition of excited state, the harmonic yield can be further enhanced, especially for the coherent superposition of the first and the third (n = 1 + 3) and the second and the fourth (n = 2 + 4) excited states, the harmonic yield is enhanced by 4-8 orders of magnitude compared with the case of the single ground initial state. Furthermore, by properly adding the laser pulse into the spatially inhomogeneous region (gap center x0 = 0.0 a.u.) from left (x0 < 0.0a.u.) to right (x0 > 0.0a.u.), much higher cutoff energies can be obtained in the left region. As a consequence, two super-bandwidths of 248 eV and 496 eV can be obtained. Finally, by properly superposing the harmonics, a series of sub-25-as pulses with intensity enhancement of 5-8 orders of magnitude can be produced.

  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.

  20. Effective Field Theory for Rydberg Polaritons

    NASA Astrophysics Data System (ADS)

    Gullans, M. J.; Thompson, J. D.; Wang, Y.; Liang, Q.-Y.; Vuletić, V.; Lukin, M. D.; Gorshkov, A. V.

    2016-09-01

    We develop an effective field theory (EFT) to describe the few- and many-body propagation of one-dimensional Rydberg polaritons. We show that the photonic transmission through the Rydberg medium can be found by mapping the propagation problem to a nonequilibrium quench, where the role of time and space are reversed. We include effective range corrections in the EFT and show that they dominate the dynamics near scattering resonances in the presence of deep bound states. Finally, we show how the long-range nature of the Rydberg-Rydberg interactions induces strong effective N -body interactions between Rydberg polaritons. These results pave the way towards studying nonperturbative effects in quantum field theories using Rydberg polaritons.

  1. Effective Field Theory for Rydberg Polaritons

    PubMed Central

    Gullans, M. J.; Thompson, J. D.; Wang, Y.; Liang, Q.-Y.; Vuletić, V.; Lukin, M. D.; Gorshkov, A. V.

    2016-01-01

    We develop an effective field theory (EFT) to describe the few- and many-body propagation of one dimensional Rydberg polaritons. We show that the photonic transmission through the Rydberg medium can be found by mapping the propagation problem to a non-equilibrium quench, where the role of time and space are reversed. We include effective range corrections in the EFT and show that they dominate the dynamics near scattering resonances in the presence of deep bound states. Finally, we show how the long-range nature of the Rydberg-Rydberg interactions induces strong effective N-body interactions between Rydberg polaritons. These results pave the way towards studying non-perturbative effects in quantum field theories using Rydberg polaritons. PMID:27661685

  2. Rydberg phases of Hydrogen and low energy nuclear reactions

    NASA Astrophysics Data System (ADS)

    Olafsson, Sveinn; Holmlid, Leif

    2016-03-01

    For over the last 26 years the science of cold fusion/LENR has been researched around the world with slow pace of progress. Modest quantity of excess heat and signatures of nuclear transmutation and helium production have been confirmed in experiments and theoretical work has only resulted in a large flora of inadequate theoretical scenarios. Here we review current state of research in Rydberg matter of Hydrogen that is showing strong signature of nuclear processes. In the presentation experimental behavior of Rydberg matter of hydrogen is described. An extensive collaboration effort of surface physics, catalysis, atomic physics, solid state physics, nuclear physics and quantum information is need to tackle the surprising experimental results that have so far been obtained. Rydberg matter of Hydrogen is the only known state of matter that is able to bring huge collection of protons to so short distances and for so long time that tunneling becomes a reasonable process for making low energy nuclear reactions. Nuclear quantum entanglement can also become realistic process at theses conditions.

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

    SciTech Connect

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

    2015-11-15

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

  4. Selective-field-ionization dynamics of a lithium m=2 Rydberg state: Landau-Zener model versus quantal approach

    SciTech Connect

    Foerre, M.; Hansen, J.P.

    2003-05-01

    The selective-field-ionization (SFI) dynamics of a Rydberg state of lithium with magnetic quantum number m=2 is studied in detail based on two different theoretical models: (1) a close coupling integration of the Schroedinger equation and (2) the multichannel (incoherent) Landau-Zener (MLZ) model. The m=2 states are particularly interesting, since they define a border zone between fully adiabatic (m=0,1) and fully diabatic (m>2) ionization dynamics. Both sets of calculations are performed up to, and above, the classical ionization limit. It is found that the MLZ model is excellent in the description of the fully diabatic dynamics while certain discrepancies between the time dependent quantal amplitudes appear when the dynamics become involved. Thus, in this region, the analysis of experimental SFI spectra should be performed with care.

  5. Quantum mechanical calculation of Rydberg-Rydberg autoionization rates

    NASA Astrophysics Data System (ADS)

    Kiffner, Martin; Ceresoli, Davide; Li, Wenhui; Jaksch, Dieter

    2016-10-01

    We present quantum mechanical calculations of autoionization rates for two rubidium Rydberg atoms with weakly overlapping electron clouds. We neglect exchange effects and consider tensor products of independent atom states forming an approximate basis of the two-electron state space. We consider large sets of two-atom states with randomly chosen quantum numbers and find that the charge overlap between the two Rydberg electrons allows one to characterise the magnitude of the autoionization rates. If the electron clouds overlap by more than one percent, the autoionization rates increase approximately exponentially with the charge overlap. This finding is independent of the energy of the initial state.

  6. Large energy superpositions via Rydberg dressing

    NASA Astrophysics Data System (ADS)

    Khazali, Mohammadsadegh; Lau, Hon Wai; Humeniuk, Adam; Simon, Christoph

    2016-08-01

    We propose to create superposition states of over 100 strontium atoms in a ground state or metastable optical clock state using the Kerr-type interaction due to Rydberg state dressing in an optical lattice. The two components of the superposition can differ by an order of 300 eV in energy, allowing tests of energy decoherence models with greatly improved sensitivity. We take into account the effects of higher-order nonlinearities, spatial inhomogeneity of the interaction, decay from the Rydberg state, collective many-body decoherence, atomic motion, molecular formation, and diminishing Rydberg level separation for increasing principal number.

  7. 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.

  8. 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, Ágúst

    2013-01-28

    (2 + n) resonance enhanced multiphoton ionization mass spectra for resonance excitations to diabatic E(1)Σ(+) (v') Rydberg and V (1)Σ(+) (v') ion-pair states (adiabatic B(1)Σ(+)(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)Σ(+) (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.

  9. 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.

  10. Optimizing the fast Rydberg quantum gate

    SciTech Connect

    Safronova, M.S.; Williams, Carl J.; Clark, Charles W.

    2003-04-01

    The fast phase gate scheme, in which the qubits are atoms confined in sites of an optical lattice, and gate operations are mediated by excitation of Rydberg states, was proposed by Jaksch et al. [Phys. Rev. Lett. 85, 2208 (2000)]. A potential source of decoherence in this system derives from motional heating, which occurs if the ground and Rydberg states of the atom move in different optical lattice potentials. We propose to minimize this effect by choosing the lattice photon frequency {omega}, so that the ground and Rydberg states have the same frequency-dependent polarizability {alpha}({omega}). The results are presented for the case of Rb.

  11. Rydberg and continuum states of the HeH+ molecular ion: Variational R -matrix and multichannel quantum defect theory calculations

    NASA Astrophysics Data System (ADS)

    Bouhali, I.; Bezzaouia, S.; Telmini, M.; Jungen, Ch.

    2016-08-01

    Variational ab initio R -matrix theory combined with generalized multichannel quantum defect theory is used to calculate singly excited Rydberg states of the hydrohelium molecular ion, HeH+, for Σ,3+1,Π,31,Δ,31,Φ,31, and Γ,31 symmetry. Bound levels are calculated for n values up to n ≈10 , and continuum states up to ≈3 eV above the HeH2 + threshold. The calculations span the range of internuclear distances R from 1 to 5 bohrs. The present work follows a preliminary study on the Δ,31 states of HeH+ [Bouhali, Bezzaouia, Telmini, and Jungen, EPJ Web Conf. 84, 04004 (2015), 10.1051/epjconf/20158404004] which was also based on R -matrix theory. Further—although limited to rather small R values—the present work extends the recent ab initio computations of Jungen and Jungen [Mol. Phys. 113, 2333 (2015), 10.1080/00268976.2015.1040094] to higher excitation energies which are not accessible to standard quantum-chemical methods. Where a comparison with the calculations of Jungen and Jungen and other older results can be made, namely for n ≤5 , very good agreement with previous ab initio results is obtained.

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

    NASA Astrophysics Data System (ADS)

    Ghoshal, Arijit; Ho, Y. K.

    2009-05-01

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

  13. 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; Burgdörfer, 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 Schrödinger 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).

  14. 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 |Δ 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!

  15. Photofragmentations, state interactions, and energetics of Rydberg and ion-pair states: two-dimensional resonance enhanced multiphoton ionization of HBr via singlet-, triplet-, Ω = 0 and 2 states.

    PubMed

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

    2012-06-07

    Mass spectra were recorded for one-colour resonance enhanced multiphoton ionization (REMPI) of H(i)Br (i = 79, 81) for the two-photon resonance excitation region 79,040-80,300 cm(-1) to obtain two-dimensional REMPI data. The data were analysed in terms of rotational line positions, intensities, and line-widths. Quantitative analysis of the data relevant to near-resonance interactions between the F(1)Δ(2)(v' = 1) and V(1)Σ(+)(v' = m + 7) states gives interaction strengths, fractional state mixing, and parameters relevant to dissociation of the F state. Qualitative analysis further reveals the nature of state interactions between ion-pair states and the E(1)Σ(+) (v' = 1) and H(1)Σ(+)(v' = 0) Rydberg states in terms of relative strengths and J' dependences. Large variety in line-widths, depending on electronic states and J' quantum numbers, is indicative of number of different predissociation channels. The relationship between line-widths, line-shifts, and signal intensities reveals dissociation mechanisms involving ion-pair to Rydberg state interactions prior to direct or indirect predissociations of Rydberg states. Quantum interference effects are found to be important. Moreover, observed bromine atom (2 + 1) REMPI signals support the importance of Rydberg state predissociation channels. A band system, not previously observed in REMPI, was observed and assigned to the k(3)Π(0)(v' = 0) ←← X transition with band origin 80,038 cm(-1) and rotational parameter B(v('))=7.238 cm(-1).

  16. Measurement of Rydberg positronium fluorescence lifetimes

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    We report measurements of the fluorescence lifetimes of positronium (Ps) atoms with principal quantum numbers n =10 -19 . Ps atoms in Rydberg-Stark states were produced via a two-color two-step 1 3S→2 3P→n 3S/n Rydberg levels, yielding values ranging from 3 μ s to 26 μ s . Our data are in accord with the expected radiative lifetimes of Rydberg-Stark states of Ps.

  17. Ultrafast α -CC bond cleavage of acetone upon excitation to 3p and 3d Rydberg states by femtosecond time-resolved photoelectron imaging

    NASA Astrophysics Data System (ADS)

    Hüter, O.; Temps, F.

    2016-12-01

    The radiationless electronic relaxation and α -CC bond fission dynamics of jet-cooled acetone in the S1 (n π* ) state and in high-lying 3p and 3d Rydberg states have been investigated by femtosecond time-resolved mass spectrometry and photoelectron imaging. The S1 state was accessed by absorption of a UV pump photon at selected wavelengths between λ = 320 and 250 nm. The observed acetone mass signals and the S1 photoelectron band decayed on sub-picosecond time scales, consistent with a recently proposed ultrafast structural relaxation of the molecules in the S1 state away from the Franck-Condon probe window. No direct signatures could be observed by the experiments for CC dissociation on the S1 potential energy hypersurface in up to 1 ns. The observed acetyl mass signals at all pump wavelengths turned out to be associated with absorption by the molecules of one or more additional pump and/or probe photons. In particular, absorption of a second UV pump photon by the S1 (n π* ) state was found to populate a series of high-lying states belonging to the n = 3 Rydberg manifold. The respective transitions are favored by much larger cross sections compared to the S1 ← S0 transition. The characteristic energies revealed by the photoelectron images allowed for assignments to the 3p and 3dyz states. At two-photon excitation energies higher than 8.1 eV, an ultrafast reaction pathway for breaking the α -CC bond in 50-90 fs via the 3dyz Rydberg state and the elusive π π* state was observed, explaining the formation of acetyl radicals after femtosecond laser excitation of acetone at these wavelengths.

  18. 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.

  19. Off-diagonal long-range order (ODLRO) and ground state properties of liquid helium

    SciTech Connect

    Rodriguez-Gomez, J.R.

    1983-01-01

    An independent calculation of the condensate fraction and the ground state energy of liquid helium is given. The Froehlich ansatz for the second reduced density matrix in conjunction with the ODLORO hypothesis for liquid helium below the critical temperature is used. Froehlich's ansatz is shown to be consistent with numerical calculations of the ground state properties of liquid helium. The ground state energy was -5.10/sup 0/K, close to the experimental value. The condensate fraction turned out to be about 10% which is within the margin of error of recent neutron scattering experiments and agrees with other theoretical calculations.

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

    NASA Astrophysics Data System (ADS)

    Eiles, Matthew; Greene, Chris

    2016-05-01

    A generalized class of exotic long-range Rydberg molecules consisting of a multichannel Rydberg atom bound to a distant ground state atom by the Rydberg electron is predicted. These molecules are characterized by the rich physics provided by the strongly perturbed multichannel Rydberg spectra of divalent atoms, in contrast to the regular Rydberg series of the alkali atoms used to form Rydberg molecules to date. These multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number n. In particular, the nd Rydberg state of calcium becomes nearly degenerate with states of high orbital angular momentum over the range 17 < n < 22 , promoting its admixture into the high l deeply bound ``trilobite'' molecule states and thereby circumventing the usual difficulty posed by electric dipole selection rules. Further novel molecular states are predicted to occur in the low- J states of silicon, which are strongly perturbed due to channel interactions between Rydberg series leading to the spin-orbit split ionization thresholds. These interactions manifest themselves in potential curves exhibiting two distinct length scales, providing novel opportunities for quantum manipulation. Supported in part by the National Science Foundation under Grant No. PHY-1306905.

  1. H-, He-like recombination spectra - II. l-changing collisions for He Rydberg states

    NASA Astrophysics Data System (ADS)

    Guzmán, F.; Badnell, N. R.; Williams, R. J. R.; van Hoof, P. A. M.; Chatzikos, M.; Ferland, G. J.

    2017-01-01

    Cosmological models can be constrained by determining primordial abundances. Accurate predictions of the He I spectrum are needed to determine the primordial helium abundance to a precision of <1 per cent in order to constrain big bang nucleosynthesis models. Theoretical line emissivities at least this accurate are needed if this precision is to be achieved. In the first paper of this series, which focused on H I, we showed that differences in l-changing collisional rate coefficients predicted by three different theories can translate into 10 per cent changes in predictions for H I spectra. Here, we consider the more complicated case of He atoms, where low-l subshells are not energy degenerate. A criterion for deciding when the energy separation between l subshells is small enough to apply energy-degenerate collisional theories is given. Moreover, for certain conditions, the Bethe approximation originally proposed by Pengelly & Seaton is not sufficiently accurate. We introduce a simple modification of this theory which leads to rate coefficients which agree well with those obtained from pure quantal calculations using the approach of Vrinceanu et al. We show that the l-changing rate coefficients from the different theoretical approaches lead to differences of ˜10 per cent in He I emissivities in simulations of H II regions using spectral code CLOUDY.

  2. 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.

  3. 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 σ* 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 σ* orbital swap, allowing

  4. 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.

  5. Storage Enhanced Nonlinearities in a Cold Atomic Rydberg Ensemble

    NASA Astrophysics Data System (ADS)

    Distante, E.; Padrón-Brito, A.; Cristiani, M.; Paredes-Barato, D.; de Riedmatten, H.

    2016-09-01

    The combination of electromagnetically induced transparency with the nonlinear interaction between Rydberg atoms provides an effective interaction between photons. In this Letter, we investigate the storage of optical pulses as collective Rydberg atomic excitations in a cold atomic ensemble. By measuring the dynamics of the stored Rydberg polaritons, we experimentally demonstrate that storing a probe pulse as Rydberg polaritons strongly enhances the Rydberg mediated interaction compared to the slow propagation case. We show that the process is characterized by two time scales. At short storage times, we observe a strong enhancement of the interaction due to the reduction of the Rydberg polariton group velocity down to 0. For longer storage times, we observe a further, weaker enhancement dominated by Rydberg induced dephasing of the multiparticle components of the state. In this regime, we observe a nonlinear dependence of the Rydberg polariton coherence time with the input photon number. Our results have direct consequences in Rydberg quantum optics and may enable the test of new theories of strongly interacting Rydberg systems.

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

    SciTech Connect

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

    2011-09-15

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

  7. Condensate losses and oscillations induced by Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Karpiuk, Tomasz; Brewczyk, Mirosław; Rzążewski, Kazimierz; Gaj, Anita; Krupp, Alexander T.; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman

    2017-03-01

    We numerically analyze the impact of a single Rydberg electron onto a Bose–Einstein condensate. Both S- and D-Rydberg states are studied. The radial size of S- and D-states are comparable, hence the only difference is due to the angular dependence of the wavefunctions. We find the atom losses in the condensate after the excitation of a sequence of Rydberg atoms. Additionally, we investigate the mechanical effect in which the Rydberg atoms force the condensate to oscillate. Our numerical analysis is based on the classical fields approximation. Finally, we compare numerical results to experimental data.

  8. 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

  9. Spectrum, radial wave functions, and hyperfine splittings of the Rydberg states in heavy alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Sanayei, Ali; Schopohl, Nils

    2016-07-01

    We present numerically accurate calculations of the bound-state spectrum of the highly excited valence electron in the heavy alkali-metal atoms solving the radial Schrödinger eigenvalue problem with a modern spectral collocation method that applies also for a large principal quantum number n ≫1 . As an effective single-particle potential we favor the reputable potential of Marinescu et al. [Phys. Rev. A 49, 982 (1994)], 10.1103/PhysRevA.49.982. Recent quasiclassical calculations of the quantum defect of the valence electron agree for orbital angular momentum l =0 ,1 ,2 ,... overall remarkably well with the results of the numerical calculations, but for the Rydberg states of rubidium and also cesium with l =3 this agreement is less fair. The reason for this anomaly is that in rubidium and cesium the potential acquires for l =3 deep inside the ionic core a second classical region, thus invalidating a standard Wentzel-Kramers-Brillouin (WKB) calculation with two widely spaced turning points. Comparing then our numerical solutions of the radial Schrödinger eigenvalue problem with the uniform analytic WKB approximation of Langer constructed around the remote turning point rn,j ,l (" close=")n -δ0)">+ we observe everywhere a remarkable agreement, apart from a tiny region around the inner turning point rn,j ,l (-). For s states the centrifugal barrier is absent and no inner turning point exists: rn,j ,0 (-)=0 . With the help of an ansatz proposed by Fock we obtain for the s states a second uniform analytic approximation to the radial wave function complementary to the WKB approximation of Langer, which is exact for r →0+ . From the patching condition, that is, for l =0 the Langer and Fock solutions should agree in the intermediate region 0

  10. 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 Schr

  11. Optical transitions from the lowest to higher exciton and biexciton Rydberg states in CuCl

    NASA Astrophysics Data System (ADS)

    Miyajima, K.; Sakaniwa, K.; Sugawara, M.

    2016-11-01

    We measured the optical transitions due to the internal energy levels of an exciton and biexciton in a CuCl single crystal using pump-probe spectroscopy. The transient absorption bands due to the transitions from the 1 s to 2 p and from the 1 s to 3 p exciton states were observed at 3 K, which is consistent with their reported energies. Simultaneously, the transient absorption peak due to the biexciton was observed, which corresponds to a transition from the lowest state (composed of two 1 s excitons) to higher states (composed of 1 s and 2 p excitons). The value of the observed biexciton peak energy was reasonable considering the hydrogen molecule orbitals and the electron-to-hole effective mass ratio. In addition, the transient absorption peaks were broadened at 77 K, because of the increase in the homogeneous width of the 2 p exciton state. The transient absorption spectrum was almost completely determined by this width. Our findings are of importance with regard to the optical phenomena in the infrared region related to the quantum coherence of excitons and biexcitons in semiconductors.

  12. Study of Energy Levels and Decay Mechanisms for Singlet Rydberg States of Molecular Nitrogen.

    DTIC Science & Technology

    1987-09-15

    C.4 Harvard University Holyoke Center 1350 Massachusetts Avenue Cambridge, MA 02138 C1 Final Report 1 October 1983 - 1 August 1987 15 September 1987... Holyoke Center 1350 Massachusetts Avenue Hanscom AFB, MA 01731-5000 Cambridge, MA 02138 8a. NAME OF FUNDING/SPONSORING 8b OFFICE SYMBOL 9. PROCUREMENT...INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (if applicable) F19628-84-K-0015 8c. ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NUMBERS

  13. Blockade involving high- n, n ~ 300 , strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Yoshida, Shuhei; Burgdörfer, Joachim; Zhang, Xinyue; Dunning, F. Barry

    2016-05-01

    The blockade of high- n strontium n1F3 Rydberg states contained in a hot atomic beam is investigated both theoretically and experimentally. One difficulty in such experiments is that, once created, Rydberg atoms move out of the excitation volume reducing blockade effects. While the effects of such motion are apparent, the data provide strong evidence of blockade, consistent with theoretical predictions. Because of their relatively high angular momentum (L = 3) , a pair of n1F3 Rydberg atoms have many degenerate states whose degeneracy is removed by Rydberg-Rydberg interactions yielding a high density of states near the target energy. To evaluate the effect of blockade not only the energy shifts but also the modification of the oscillator strengths for excitation have to be taken into account. The n-scaling of the interactions and the importance of high-order multipoles will also be discussed. Research supported by the NSF and Robert A. Welch Foundation.

  14. 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.

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

    SciTech Connect

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

    2013-10-15

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

  16. 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.

  17. Quasi-One-Dimensional Electronic States Inside and Outside Helium-Plated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Motta, M.; Galli, D. E.; Liebrecht, M.; Del Maestro, A.; Cole, M. W.

    2016-10-01

    About one-half a century ago, it was realized that electrons experience a repulsive barrier when approaching the surface of condensed phases of helium, hydrogen, and neon. This led to the proposal and subsequent observation of image-potential surface-bound electronic states, which exhibit intriguing quasi-two-dimensional behavior. In the present work, we report similar quasi-one-dimensional electronic states by exploring single-wall carbon nanotubes coated both inside and outside by thin helium films. Electrons near such structures are localized in the radial direction, but free to move along the nanotube axis. The many-body aspects of the system are discussed qualitatively.

  18. Progress towards a precision measurement of the n=2 triplet P fine structure of atomic helium

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We report progress on the measurement of the J = 1 to J = 2 23 P fine-structure interval of atomic helium. The measurement uses a liquid-nitrogen-cooled DC discharge source of metastable helium and the atomic beam is laser cooled in the transverse directions. The atoms are excited to 23 P by a 1083-nm diode laser, and the fine-structure transition is driven by microwaves using the frequency-offset separated oscillatory fields technique. The transition is detected by further laser excitation to a Rydberg state, followed by Stark ionization. This work is supported by NSERC, CRC.

  19. Rb ultralong-range Rydberg molecules in magnetic and electric fields

    NASA Astrophysics Data System (ADS)

    Gaj, Anita

    2016-12-01

    We review the field of ultralong-range Rydberg molecules with a focus on recent developments. We briefly revisit the binding mechanism of Rydberg molecules based on electron-atom scattering and give an overview of experimental realizations in different ultracold atomic systems. However the main focus of the manuscript is on Rb2 Rydberg molecules. We discuss different angular momenta of the excited Rydberg states ( S and D) and the interaction of the molecules with external electric and magnetic fields. Furthermore, we cover the transition from low atomic densities, where only a single atom is bound by a Rydberg electron, to high densities, where polyatomic bound states can be observed.

  20. Rydberg atom interactions from 300 K to 300 K

    NASA Astrophysics Data System (ADS)

    Pillet, P.; Gallagher, T. F.

    2016-09-01

    Cold Rydberg atoms provide novel approaches to many-body problems and quantum simulation. To introduce the recent work presented in this special issue, we present here a quick history of a half-century research activity in the Rydberg-atom field, focusing our attention on the giant interactions between Rydberg atoms and other atoms. These interactions are the origin of many effects observed with Rydberg atoms: pressure shifts, dipole-dipole energy transfer, and avalanche-ionization. These effects have led to evidence of new bound chemical states, such as trilobites states, many-body effects in frozen Rydberg gases, and the spontaneous formation of ultra-cold plasmas. They open exciting new prospects at the intersection of atomic physics, condensed matter physics, and plasma physics.

  1. Signatures of Quantum Coherences in Rydberg Excitons

    NASA Astrophysics Data System (ADS)

    Grünwald, P.; Aßmann, M.; Heckötter, J.; Fröhlich, D.; Bayer, M.; Stolz, H.; Scheel, S.

    2016-09-01

    Coherent optical control of individual particles has been demonstrated both for atoms and semiconductor quantum dots. Here we demonstrate the emergence of quantum coherent effects in semiconductor Rydberg excitons in bulk Cu2O . Because of the spectral proximity between two adjacent Rydberg exciton states, a single-frequency laser may pump both resonances with little dissipation from the detuning. As a consequence, additional resonances appear in the absorption spectrum that correspond to dressed states consisting of two Rydberg exciton levels coupled to the excitonic vacuum, forming a V -type three-level system, but driven only by one laser light source. We show that the level of pure dephasing in this system is extremely low. These observations are a crucial step towards coherently controlled quantum technologies in a bulk semiconductor.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  4. Attosecond Transient Absorption Spectroscopy of doubly-excited states in helium

    NASA Astrophysics Data System (ADS)

    Argenti, Luca; Ott, Christian; Pfeifer, Thomas; Martín, Fernando

    2014-04-01

    Theoretical calculations of the XUV attosecond transient absorption spectrum (ATAS) of helium in the doubly-excited state region reproduce recent high-precision measurements, reveal novel means of controlling the dynamics of transiently-bound electronic wavepackets in intense laser fields, and indicates a possible extension of 2D-spectroscopies to the XUV range.

  5. Analysis of 1s(2s2p {sup 3}P)nl Rydberg states in the K-shell photoionization of the Be atom

    SciTech Connect

    Yoshida, Fumiko; Matsuoka, Leo; Takashima, Ryuta; Hasegawa, Shuichi; Nagata, Tetsuo; Azuma, Yoshiro; Obara, Satoshi; Koike, Fumihiro

    2006-06-15

    We have observed inner-shell photoionization of Be using synchrotron radiation in the energy region of the 1s(2s2p {sup 3}P)nl Rydberg states. We used a time-of-flight method to distinguish singly and doubly charged photoions and obtained the Be{sup +} [ns; n=5-12 ({sup 1}P)3s] and Be{sup 2+} [ns; n=5-8, nd=5,6 ({sup 1}P)3s] ion spectra with high resolution corresponding to an instrumental bandpass of 13 meV. Detailed analysis enabled the autoionization parameters, resonance energy position E{sub 0}, resonance width {gamma}, and Fano parameter q, to be obtained. From the resonance positions of the {sup 3}Pnl series members, the series limit was determined to be 127.97 eV, which is in good agreement with previous experiments.

  6. QED shifts and solution to the Bethe logarithm problem for helium

    NASA Astrophysics Data System (ADS)

    Drake, Gordon W. F.; Goldman, S. P.

    2000-06-01

    A new method is presented for the calculation of the mean exictation energy (Bethe logarithm) for helium and other two-electron systems [1]. The method requires only a single matrix diagonalization within a correlated Hylleraas basis set extended to contain a wide range of distance scales. High precision results are obtained for the ground states of Ps^-, H^-, and all the S- and P-states of heliumlike ions up to n = 5, including finite mass corrections. The result for the ground state of helium is 4.370 160 218(3) in units of Rydbergs for the case of infinite nuclear mass. The results are used to calculate revised values for the quantum electrodynamic energy shifts for the helium S- and P-states. A comparison with high precision measurements will be presented. [1] G. W. F. Drake and S. P. Goldman, Can. J. Phys. 77, in press (1999).

  7. Equation of State and Electrical Conductivity of Helium at High Pressures and Temperatures

    NASA Astrophysics Data System (ADS)

    McWilliams, R. S.; Eggert, J. H.; Loubeyre, P.; Brygoo, S.; Collins, G.; Jeanloz, R.

    2004-12-01

    Helium, the second-most abundant element in the universe and giant planets, is expected to metallize at much higher pressures and temperatures than the most abundant element, hydrogen. The difference in chemical-bonding character, between insulator and metal, is expected to make hydrogen-helium mixtures immiscible throughout large fractions of planetary interiors, and therefore subject to gravitational separation contributing significantly to the internal dynamics of giant planets. Using laser-driven shock waves on samples pre-compressed in high-pressure cells, we have obtained the first measurements of optical reflectivity from the shock front in helium to pressures of 146 GPa. The reflectivity exceeds 5% above \\ensuremath{\\sim} 100 GPa, indicating high electrical conductivity. By varying the initial pressure (hence density) of the sample, we can access a much wider range of final pressure-temperature conditions than is possible in conventional Hugoniot experiments. Our work increases by nine-fold the pressure range of single-shock measurements, in comparison with gas-gun experiments, and yields results in agreement with the Saumon, Chabrier and Van Horn (1994) equation of state for helium. This changes the internal structures inferred for Jupiter-size planets, relative to models based on earlier equations of state (e. g., SESAME).

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

    PubMed Central

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

    2014-01-01

    In Rydberg atoms, at least one electron is excited to a state with a high principal quantum number. In an ultracold environment, this low-energy electron can scatter off a ground state atom allowing for the formation of a Rydberg molecule consisting of one Rydberg atom and several ground state atoms. Here we investigate those Rydberg molecules created by photoassociation for the spherically symmetric S-states. A step by step increase of the principal quantum number up to n=111 enables us to go beyond the previously observed dimer and trimer states up to a molecule, where four ground state atoms are bound by one Rydberg atom. The increase of bound atoms and the decreasing binding potential per atom with principal quantum number results finally in an overlap of spectral lines. The associated density-dependent line broadening sets a fundamental limit, for example, for the optical thickness per blockade volume in Rydberg quantum optics experiments. PMID:25082599

  9. Dipolar exchange induced transparency with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Petrosyan, David

    2017-03-01

    A three-level atomic medium can be made transparent to a resonant probe field in the presence of a strong control field acting on an adjacent atomic transition to a long-lived state, which can be represented by a highly excited Rydberg state. The long-range interactions between the Rydberg state atoms then translate into strong, non-local, dispersive or absorptive interactions between the probe photons, which can be used to achieve deterministic quantum logic gates and single photon sources. Here we show that long-range dipole–dipole exchange interaction with one or more spins—two-level systems represented by atoms in suitable Rydberg states—can play the role of control field for the optically dense medium of atoms. This induces transparency of the medium for a number of probe photons n p not exceeding the number of spins n s , while all the excess photons are resonantly absorbed upon propagation. In the most practical case of a single spin atom prepared in the Rydberg state, the medium is thus transparent only to a single input probe photon. For larger number of spins n s , all n p ≤ n s photon components of the probe field would experience transparency but with an n p -dependent group velocity.

  10. Logarithmic mean excitation energies: II. Helium, lithium, beryllium, and the 2s state of hydrogen

    NASA Astrophysics Data System (ADS)

    Rosendorff, S.; Schlaile, H. G.

    1993-10-01

    The four logarithmic excitation eneriges I(ν) for ν=-1, 0, 1, and 2 have been calculated for helium, lithium, beryllium, and the 2s state of hydrogen. They appear in the expressions of the total cross section, the stopping power, and the straggling effect for fast charged particles, and in the expressions of the Lamb shift of atomic energy levels. The method was introduced some years ago [Rosendorff and Birman, Phys. Rev. A 31, 612 (1985)]. For hydrogen the method is rigorous. Exact one-particle wave functions given by Clementi were used. Thus, correlation and symmetrization effects were neglected. For the nonhydrogen states, the relevant differential equations were solved by using a computer. An effective charge was defined which has interesting features. It is helpful in gaining some physical insight into the results obtained for helium and the 1s and 2s states of lithium and beryllium.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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}.

  16. 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).

  17. Anomalous excitation facilitation in inhomogeneously broadened Rydberg gases

    NASA Astrophysics Data System (ADS)

    Letscher, F.; Thomas, O.; Niederprüm, T.; Ott, H.; Fleischhauer, M.

    2017-02-01

    When atomic gases are laser driven to Rydberg states in an off-resonant way, a single Rydberg atom may enhance the excitation rate of surrounding atoms. This leads to a facilitated excitation referred to as Rydberg antiblockade. In the usual facilitation scenario, the detuning of the laser from resonance compensates the interaction shift. Here, we discuss a different excitation mechanism, which we call anomalous facilitation. This occurs on the "wrong side" of the resonance and originates from inhomogeneous broadening. The anomalous facilitation may be seen in experiments of attractively interacting atoms on the blue detuned side, where facilitation is not expected to appear.

  18. 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.

  19. Helium breakup states in 10Be and 12Be

    NASA Astrophysics Data System (ADS)

    Freer, M.; Angélique, J. C.; Axelsson, L.; Benoit, B.; Bergmann, U.; Catford, W. N.; Chappell, S. P.; Clarke, N. M.; Curtis, N.; D'arrigo, A.; de Góes Brennard, E.; Dorvaux, O.; Fulton, B. R.; Giardina, G.; Gregori, C.; Grévy, S.; Hanappe, F.; Kelly, G.; Labiche, M.; Le Brun, C.; Leenhardt, S.; Lewitowicz, M.; Markenroth, K.; Marqués, F. M.; Murgatroyd, J. T.; Nilsson, T.; Ninane, A.; Orr, N. A.; Piqueras, I.; Saint Laurent, M. G.; Singer, S. M.; Sorlin, O.; Stuttgé, L.; Watson, D. L.

    2001-03-01

    The breakup of 10,12Be into He clusters has been studied using the p,12C(12Be,6He,6He) and 12C(12Be,4He,6He) inelastic scattering and two neutron transfer reactions with a 378 MeV 12Be beam incident on 12C and (CH2)n targets. Evidence has been found for three new states in 10Be at excitation energies of 13.2, 14.8, and 16.1 MeV, which may be associated with a 4He+6He cluster structure. The evidence for He cluster states in 12Be in the excitation energy range 12 to 25 MeV is also discussed.

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

    PubMed

    Huang, Yonghua; Chen, Guobang; Arp, Vincent

    2006-08-07

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  2. Rotational branching ratios and photoelectron angular distributions in resonance enhanced multiphoton ionization of HBr via the F sup 1. Delta. sub 2 Rydberg state

    SciTech Connect

    Wang, K.; McKoy, V. )

    1991-12-01

    Results of theoretical studies of rotational ion distributions in the {ital X} {sup 2}{Pi}{sub 1/2} ground state of HBr{sup +} resulting from (2+1) resonance enhanced multiphoton ionization (REMPI) via the {ital S}(2) branch of the {ital F} {sup 1}{Delta}{sub 2} Rydberg state are reported. These results show a strongly parity-favored ion distribution with about 80% population in the ({minus}) component of the {Lambda} doublet of {ital J}{sup +} rotational levels. The 20% population in the other parity component of the {Lambda} doublet can be seen to be due to odd partial wave contributions to the photoelectron matrix elements which arise primarily from non-atomic-like behavior of the electronic continuum. This, in turn, is due to angular momentum coupling in the photoelectron orbital brought about by the torques of the nonspherical molecular ion potential. We demonstrate that the effect of alignment on these ion distributions, although not large, is important. Photoelectron angular distributions and alignment of the {ital J} levels of the HBr{sup +} ions are also presented. Rotational branching ratios and photoelectron angular distributions resulting from (2+1{prime}) REMPI of HBr via several {ital S} branches of the {ital F} {sup 1}{Delta}{sub 2} state are also shown for near-threshold photoelectron energies.

  3. 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.

  4. Dissipative stabilization of quantum-feedback-based multipartite entanglement with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Shao, Xiao-Qiang; Wu, Jin-Hui; Yi, Xue-Xi

    2017-02-01

    A quantum-feedback-based scheme is proposed for generating multipartite entanglements of Rydberg atoms in a dissipative optical cavity. The Rydberg blockade mechanism efficiently prevents double excitations of the system, which is further exploited to speed up the stabilization of an entangled state with a single Rydberg state excitation. The corresponding feedback operations are greatly simplified, since only one regular atom needs to be controlled during the whole process, irrespective of the number of particles. The form of the entangled state is also adjustable via regulating the Rabi frequencies of driving fields. Moreover, a relatively long lifetime of the high-lying Rydberg level guarantees a high fidelity in a realistic situation.

  5. Electronically excited rubidium atom in helium clusters and films. II. Second excited state and absorption spectrum.

    PubMed

    Leino, Markku; Viel, Alexandra; Zillich, Robert E

    2011-01-14

    Following our work on the study of helium droplets and film doped with one electronically excited rubidium atom Rb(∗) ((2)P) [M. Leino, A. Viel, and R. E. Zillich, J. Chem. Phys. 129, 184308 (2008)], we focus in this paper on the second excited state. We present theoretical studies of such droplets and films using quantum Monte Carlo approaches. Diffusion and path integral Monte Carlo algorithms combined with a diatomics-in-molecule scheme to model the nonpair additive potential energy surface are used to investigate the energetics and the structure of Rb(∗)He(n) clusters. Helium films as a model for the limit of large clusters are also considered. As in our work on the first electronic excited state, our present calculations find stable Rb(∗)He(n) clusters. The structures obtained are however different with a He-Rb(∗)-He exciplex core to which more helium atoms are weakly attached, preferentially on one end of the core exciplex. The electronic absorption spectrum is also presented for increasing cluster sizes as well as for the film.

  6. Coherent Rydberg Excitation in Thermal Microcells

    NASA Astrophysics Data System (ADS)

    Loew, Robert

    2011-05-01

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

  7. 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.

  8. Recent advances in Rydberg physics using alkaline-earth atoms

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    In this brief review, the opportunities that the alkaline-earth elements offer for studying new aspects of Rydberg physics are discussed. For example, the bosonic alkaline-earth isotopes have zero nuclear spin which eliminates many of the complexities present in alkali Rydberg atoms, permitting simpler and more direct comparison between theory and experiment. The presence of two valence electrons allows the production of singlet and triplet Rydberg states that can exhibit a variety of attractive or repulsive interactions. The availability of weak intercombination lines is advantageous for laser cooling and for applications such as Rydberg dressing. Excitation of one electron to a Rydberg state leaves behind an optically active core ion allowing, for high-L states, the optical imaging of Rydberg atoms and their (spatial) manipulation using light scattering. The second valence electron offers the possibility of engineering long-lived doubly excited states such as planetary atoms. Recent advances in both theory and experiment are highlighted together with a number of possible directions for the future.

  9. Interactions between Rydberg atoms and ultracold polar molecules

    NASA Astrophysics Data System (ADS)

    Jayaseelan, Maitreyi; Haruza, Marek; Bigelow, Nicholas P.

    2015-05-01

    We investigate dipolar interactions arising in a hybrid system containing both ultracold polar molecules and atomic Rydberg states. Ultracold NaCs molecules are produced by photoassociation from laser cooled mixtures of sodium and cesium atoms and detected through resonant multi-photon ionization (REMPI). Rydberg atoms with large dipole moments are excited in the atomic cloud using a multi-photon process and detected via field-ionization. We look for evidence of the interactions in the observed spectra.

  10. Production of Doubly Excited Projectile States in Collisions of 0.1 Mev/u SILVER(+4) Ions with Helium, Hydrogen, and Argon Gas Target

    NASA Astrophysics Data System (ADS)

    Underwood-Lemons, Theresa Ann

    An important problem in atomic dynamics is the structure of very high doubly excited states, in which two electrons are excited away from the rest of the electrons in the ionic core, making their mutual interaction and correlation as important as their individual interaction with the remaining core. In this work, we study the formation of doubly excited projectile states near the double escape threshold in collisions of 0.1 MeV/u Ag^{+4} ions with He, H_2, and Ar gas targets. We detect projectile states in which one electron occupies a high Rydberg state and a second electron (a cusp electron) occupies a low lying continuum state. Cusp electrons are characterized by a velocity which is nearly equal in magnitude and direction to the projectile velocity. Cusp electrons are energy analyzed with a 30 ^circ parallel plate energy analyzer, and Rydberg electrons are field ionized in a spherical ionizer before being energy analyzed in a 160^ circ^herical sector analyzer. Standard coincidence measurements between a cusp and a Rydberg electron signal the production of a doubly excited projectile state. The cross sections for producing these doubly excited projectile states are on the order of 10 ^{-20} cm^2. The production probabilities are measured as a function of cusp electron laboratory frame energy with the detected Rydberg electrons arising from a fixed band of principal quantum numbers. The laboratory frame energy distributions of cusp electrons associated with these doubly excited states are then compared to the energy distribution of cusp electrons measured without imposing a Rydberg electron coincidence requirement. For the He target, the shapes of the two energy distributions are the same. However, the width of the energy distribution of cusp electrons measured in coincidence with Rydberg electrons is smaller than the width of the cusp electron energy distribution without a coincidence requirement for the H_2 and Ar gas targets, the difference being greatest for

  11. 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

  12. Ultracold Chemical Reactions of a Single Rydberg Atom in a Dense Gas

    NASA Astrophysics Data System (ADS)

    Schlagmüller, Michael; Liebisch, Tara Cubel; Engel, Felix; Kleinbach, Kathrin S.; Böttcher, Fabian; Hermann, Udo; Westphal, Karl M.; Gaj, Anita; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Pérez-Ríos, Jesús; Greene, Chris H.

    2016-07-01

    Within a dense environment (ρ ≈1014 atoms /cm3 ) at ultracold temperatures (T <1 μ K ), a single atom excited to a Rydberg state acts as a reaction center for surrounding neutral atoms. At these temperatures, almost all neutral atoms within the Rydberg orbit are bound to the Rydberg core and interact with the Rydberg atom. We have studied the reaction rate and products for n S 87Rb Rydberg states, and we mainly observe a state change of the Rydberg electron to a high orbital angular momentum l , with the released energy being converted into kinetic energy of the Rydberg atom. Unexpectedly, the measurements show a threshold behavior at n ≈100 for the inelastic collision time leading to increased lifetimes of the Rydberg state independent of the densities investigated. Even at very high densities (ρ ≈4.8 ×1014 cm-3 ), the lifetime of a Rydberg atom exceeds 10 μ s at n >140 compared to 1 μ s at n =90 . In addition, a second observed reaction mechanism, namely, Rb2+ molecule formation, was studied. Both reaction products are equally probable for n =40 , but the fraction of Rb2+ created drops to below 10% for n ≥90 .

  13. A Rydberg impurity in a dense background gas (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liebisch, Tara; Schlagmüller, Michael; Engel, Felix; Westphal, Karl; Kleinbach, Kathrin; Böttcher, Fabian; Loew, Robert; Hofferberth, Sebastian; Pfau, Tilman; Perez-Rios, Jesus; Greene, Chris

    2016-04-01

    A single Rydberg atom impurity excited in a BEC is a system that can be utilized to measure the quantum mechanical properties of electron - neutral scattering andthe electron probability density of a Rydberg atom. The Rydberg electron - neutral atom scattering process, is a fundamental scattering process, which can be described via Fermi's pseudopotential as V{ěc{r},ěc{R} )=2pi {a}[k(R)]&delta^{(3)}(ěc{r}-ěc{R}). The scattering length is dependent on the momentum of the Rydberg electron, and therefore is dependent on the separation of the Rydberg electron from the ion core. At the classical outermost turning point of the electron, it has the slowest momentum leading to s-wave dominated scattering potentials 10's of MHz in depth for n<40 (Greene et al. PRL 85 2458 (2000), Bendkowsky et al. PRL 105 163201 (2010)). In alkali atoms there is a shape resonance for p-wave scattering, which becomes relevant at ion-neutral separations of 75nm (I.I. Fabrikant J.Phys B 19, 1527 (1985)). This shape resonance potential is several GHz deep, spanning the energy level spacing between n and n-1 principal quantum numbers. At high BEC densities of 5x10^14cm-3 the nearest neighbor spacing is less than 70nm. A Rydberg atom excited within a BEC, is an excitation of the Rydberg atom and all N neutral atoms located within the Rydberg orbit, described as nS+N x 5S. The nS+N x 5S state is density shifted from the Rydberg resonance. Not only does the distribution of atoms within the Rydberg orbit lead to a density shift, but, at these high densities, atoms excited in the nS+N x 5S state near the shape resonance potential cause large perturbations to the density shift, leading to a line broadening. Therefore the spectroscopic line shape of a Rydberg atom in a BEC allows us to probe the theoretically calculated p-wave shape resonance potential. Furthermore, we can observe and measure the dynamics of neutrals excited in the nS+N x 5S state. In the ultracold regime of a BEC, the background

  14. 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.

  15. Polarization spectra of Zeeman sublevels in Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Bao, Shanxia; Zhang, Hao; Zhou, Jian; Zhang, Linjie; Zhao, Jianming; Xiao, Liantuan; Jia, Suotang

    2016-10-01

    The polarization spectra of electromagnetically induced transparency (EIT) for Zeeman sublevels in a cascade system with Rydberg state are demonstrated. The magnitude dependence of Rydberg-EIT on the polarizations of probe and coupling laser fields is studied, and shown mainly due to the strengths of relative dipole matrix elements between degenerate Zeeman sublevels. We further investigate the polarization spectra of Rydberg-EIT in the optimal polarization combinations of left-handed and right-handed circularly polarized fields when an external magnetic field is applied. The existence of nondegenerate Zeeman sublevels in an external magnetic field results in the splitting of Rydberg-EIT. The theoretical calculations are very consistent with the experimental spectra.

  16. 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.

  17. Electron impact ionization of helium from its ground and metastable states

    NASA Astrophysics Data System (ADS)

    Zhang-jin, Chen; Ke-zun, Xu

    1999-05-01

    The triple differential cross sections for the ionization of helium from its ground state 1 1S and metastable states 2 1S and 2 3S in coplanar asymmetric geometry by 150, 250 and 400 eV electrons have been calculated in the BBK model. The present results are compared with the experimental data and/or the other theoretical ones. It has been found that the structures for the metastable states differ markedly from those for the ground state. The collision mechanisms for the new structures appearing in the cross sections for the ionization from metastable states have been analysed. And it has been shown how the intensity of recoil peak changes due to the size of the electron orbital. In addition, the optimal kinematical situations for the cross sections are explored for future experiment.

  18. (π*,σ*), (σ*,π*) and Rydberg triplet excited states of hydrogen peroxide and other molecules bearing two adjacent heteroatoms.

    PubMed

    Hill, J Grant; Bucher, Götz

    2014-03-27

    The properties of the lowest triplet excited states of a series of small molecules containing two or more adjacent heteroatoms have been investigated. High-level coupled cluster and MRCI+Q calculations were employed to probe the properties of the triplet excited states of hydrogen peroxide, hydrazine, hydroxylamine, fluoroamines, oxygen difluoride, hypofluorous acid, chlorine, fluorine, and disulfane. All of the molecules investigated except hydroxylamine are predicted to have bound lowest triplet excited states that are either (π*,σ*) or (σ*,π*) as in H2O2, HOF, OF2, H2S2, Cl2, NH2F, NHF2, or NF3, or are Rydberg states (hydrazine, also H2O2 and H2S2). The heteroatom-heteroatom bond dissociation enthalpies of the triplet states range from very small values as predicted for hydrogen peroxide or fluorine, to BDEs around 8-9 kcal mol(-1) that should allow for an experimental observation of the triplet state, such as in disulfane or monofluoroamine. For all triplet minima investigated except NF3 and F2, CCSD(T) gave results in agreement with the multireference method MRCI+Q, and in excellent agreement with available experimental data (BDEs, ground-state geometries). Due to multireference problems, CCSD(T) does not provide a good description for longer heteroatom-heteroatom distances, and in some cases (e.g., Cl2) it wrongly predicts the presence of a transition state for bond formation on the triplet spin manifold, where the reaction is known experimentally and, as predicted by MRCI+Q, is known to be barrierless. Finally, the (3)Π(u) state of F2 is poorly described by CCSD(T) theory, the equilibrium bond distance is significantly underestimated relative to MRCI+Q, and CCSD(T) places the triplet state above the energy of two fluorine atoms. The T1 diagnostic, frequently used to assess the quality of CCSD(T) calculations, does not appear to provide a valid criterion for the systems studied. The formation of H2O2 on the triplet potential energy hypersurface might

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

    NASA Astrophysics Data System (ADS)

    Lancuba, P.; Hogan, S. D.

    2016-04-01

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

  20. Fluorescence Excitation Function Produced Through Photoexcitation of the Rydberg States b, cn, and o3 of N2 in the 80-100 nm Region

    NASA Astrophysics Data System (ADS)

    Wu, R. C.; Judge, D. L.; Singh, T. S.; Mu, X. L.; Nee, J. B.; Chiang, S. Y.; Fung, H. S.

    2006-12-01

    Fluorescence excitation functions produced through photoexcitation of N2 using synchrotron radiation in the spectral region between 80 and 100 nm have been studied. Two broadband detectors were employed to simultaneously monitor fluorescence in the 115-320 nm and 300-700 nm region, respectively. The peaks in the VUV Fluorescence excitation functions are found to correspond to excitation of absorption transitions from the ground electronic state to the Rydberg states of b, cn (with n= 4-9), and o3 of N2. The relative fluorescence production cross sections for the observed peaks are determined. No fluorescence has been produced through excitation of the most dominating absorption features of the b-X transition except the (1,0), (5,0), and (6,0) bands, in excellent agreement with the recent lifetime measurements [1] and theoretical calculations [2]. In addition, fluorescence peaks correlate with the long vibrational progression of the c4 (v = 0-7) has also been observed. Weak fluorescence excitation peaks are also found to correlate with the excitation of the (1,0), (2,0), and (3,0) bands of the o3 VX transition. The present results provide important information for further unraveling of complicated and intriguing interactions among the excited electronic states of N2. Furthermore, solar photon excitation of N2 leading to the production of c4(0) may provide useful data required for evaluation and analysis of dayglow models of the c4(0) issue of the Earth's atmosphere [3]. Detailed results will be presented. This research is based on work supported by NSF grant ATM-0096761. [1] Sprengers, J. P., W. Ubachs, and K. G. H. Baldwin, J. Chem. Phys., 122, 144301 (2005). [2] Lewis, B. R., S. T. Gibson, W. Zhang, H. Lefebvre-Brion, and J.-M. Robbe, J. Chem. Phys., 122, 144302 (2005). [3] e.g., Meier, R. R., Space Sci. Rev., 58, 1 (1991).

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

    SciTech Connect

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

    2011-06-10

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

  2. Observation of pendular butterfly Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Niederprüm, Thomas; Thomas, Oliver; Eichert, Tanita; Lippe, Carsten; Pérez-Ríos, Jesús; Greene, Chris H.; Ott, Herwig

    2016-10-01

    Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron-perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance.

  3. Observation of pendular butterfly Rydberg molecules.

    PubMed

    Niederprüm, Thomas; Thomas, Oliver; Eichert, Tanita; Lippe, Carsten; Pérez-Ríos, Jesús; Greene, Chris H; Ott, Herwig

    2016-10-05

    Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron-perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance.

  4. Observation of pendular butterfly Rydberg molecules

    PubMed Central

    Niederprüm, Thomas; Thomas, Oliver; Eichert, Tanita; Lippe, Carsten; Pérez-Ríos, Jesús; Greene, Chris H.; Ott, Herwig

    2016-01-01

    Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron–perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance. PMID:27703143

  5. Electron-impact excitation and ionization cross sections for ground state and excited helium atoms

    SciTech Connect

    Ralchenko, Yu. Janev, R.K.; Kato, T.; Fursa, D.V.; Bray, I.; Heer, F.J. de

    2008-07-15

    Comprehensive and critically assessed cross sections for the electron-impact excitation and ionization of ground state and excited helium atoms are presented. All states (atomic terms) with n{<=}4 are treated individually, while the states with n{>=}5 are considered degenerate. For the processes involving transitions to and from n{>=}5 levels, suitable cross section scaling relations are presented. For a large number of transitions, from both ground and excited states, convergent close coupling calculations were performed to achieve a high accuracy of the data. The evaluated/recommended cross section data are presented by analytic fit functions, which preserve the correct asymptotic behavior of the cross sections. The cross sections are also displayed in graphical form.

  6. 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.

  7. Quantum signature for laser-driven correlated excitation of Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Wu, Huaizhi; Li, Yong; Yang, Zhen-Biao; Zheng, Shi-Biao

    2017-01-01

    The excitation dynamics of a laser-driven Rydberg-atom system exhibits a cooperative effect due to the interatomic Rydberg-Rydberg interaction, but the large many-body system with inhomogeneous Rydberg coupling is hard to exactly solve or numerically study by density-matrix equations. In this paper, we find that the laser-driven Rydberg-atom system with most of the atoms being in the ground state can be described by a simplified interaction model resembling the optical Kerr effect if the distance-dependent Rydberg-Rydberg interaction is replaced by an infinite-range coupling. We can then quantitatively study the effect of the quantum fluctuations on the Rydberg excitation with the interatomic correlation involved and analytically calculate the statistical characteristics of the excitation dynamics in the steady state, revealing the quantum signature of the driven-dissipative Rydberg-atom system. The results obtained here will be of great interest for other spin-1/2 systems with spin-spin coupling.

  8. 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 μs through the cavity. J. Nagl, G. Auböck, A. W. Hauser, O. Allard, C. Callegari, and W. E. Ernst, Phys. Rev. Lett. 100, 063001(2008)} G. Auböck, J. Nagl, C. Callegari, and

  9. 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

    2015-12-08

    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.

  10. THz Detection and Imaging using Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Wade, Christopher; Sibalic, Nikola; Kondo, Jorge; de Melo, Natalia; Adams, Charles; Weatherill, Kevin

    2016-05-01

    Atoms make excellent electromagnetic field sensors because each atom of the same isotope is identical and has well-studied, permanent properties allowing calibration to SI units. Thus far, atoms have not generally been exploited for terahertz detection because transitions from the atomic ground state are constrained to a limited selection of microwave and optical frequencies. In contrast, highly excited `Rydberg' states allow us access to many strong, electric dipole transitions from the RF to THz regimes. Recent advances in the coherent optical detection of Rydberg atoms have been exploited by a number of groups for precision microwave electrometry Here we report the demonstration of a room-temperature, cesium Rydberg gas as a THz to optical interface. We present two configurations: First, THz-induced fluorescence offers non-destructive and direct imaging of the THz field, providing real-time, single shot images. Second, we convert narrowband terahertz photons to infrared photons with 6% quantum efficiency allowing us to use nano-Watts of THz power to control micro-Watts of laser power on microsecond timescales. Exploiting hysteresis and a room-temperature phase transition in the response of the medium, we demonstrate a latching optical memory for sub pico-Joule THz pulses.

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    The lifetimes of the lower-lying vibrational states of ultralong-range strontium Rydberg molecules comprising one ground-state 5s2 1S0 atom and one Rydberg atom in the 5s 38s3S1 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 theories of molecular formation and decay. This research was supported by the AFOSR, NSF, the Robert A. Welch Foundation, the FWF (Austria), FWF-SFB049 NextLite. H.R.S. was supported by a Grant to ITAMP from the NSF.

  13. 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.

  14. 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.

  15. Two-atom Rydberg blockade using direct 6S to nP excitation

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  16. Stationary three-dimensional entanglement via dissipative Rydberg pumping

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. 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.

  18. Rydberg blockade effects at n ˜300 in strontium

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. Stretching and bending dynamics in triatomic ultralong-range Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Fey, Christian; Kurz, Markus; Schmelcher, Peter

    2016-07-01

    We investigate polyatomic ultralong-range Rydberg molecules consisting of three ground-state atoms bound to a Rydberg atom via s - and p -wave interactions. By employing the finite basis set representation of the unperturbed Rydberg electron Green's function we reduce the computational effort to solve the electronic problem substantially. This method is subsequently applied to determine the potential energy surfaces of triatomic systems in electronic s - and p -Rydberg states. Their molecular geometry and resulting vibrational structure are analyzed within an adiabatic approach that separates the vibrational bending and stretching dynamics. This procedure yields information on the radial and angular arrangement of the nuclei and indicates in particular that kinetic couplings between bending and stretching modes induce a linear structure in triatomic l =0 ultralong-range Rydberg molecules.

  20. 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.

  1. Rydberg atoms: Two to tango

    NASA Astrophysics Data System (ADS)

    Löw, Robert

    2014-12-01

    The old adage that you can't tango alone is certainly true for humans. But recent experiments show that it may also be applicable to Rydberg atoms, which keep a beat through the coherent exchange of energy.

  2. Ultralong-range Molecules in Strontium Rydberg Gases

    NASA Astrophysics Data System (ADS)

    Killian, Thomas

    2016-05-01

    Alkaline-earth metal atoms are attracting increased attention for studies of ultracold Rydberg gases because of new opportunities created by strong core transitions accessible with visible light and the presence of excited triplet states. We have created and characterized ultralong-range Sr2 molecules formed from one ground-state 5 s21 S0 atom and one atom in a 5sns 3 S1 Rydberg state. Molecules are formed in a trapped ultracold atomic gas using two-photon excitation, near resonance with the 5s5p 3 P1 intermediate state. Spectra for both a thermal gas and a Bose-Einstein condensate have been studied, and highly structured vibrational spectra are obtained for molecular dimers, trimers, and tetramers. Measured lifetimes of Rydberg atoms and molecules in dense gases of ground state atoms 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 reflects the fact that in strontium there is no p-wave resonance for electron scattering in this energy regime, unlike the situation in rubidium. The absence of a resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing theories of molecular formation and decay. Research supported by the AFOSR under Grant No. FA9550-14-1-0007, the NSF under Grants No. 1301773 and No. 1205946, and the Robert A, Welch Foundation under Grants No. C-0734 and No. C-1844.

  3. Higher-order recoil corrections for singlet states of the helium atom

    NASA Astrophysics Data System (ADS)

    Patkóš, Vojtěch; Yerokhin, Vladimir A.; Pachucki, Krzysztof

    2017-01-01

    We investigate the finite nuclear mass corrections in the helium atom in order to resolve a significant disagreement between the 2 3S -2 3P and 2 3S -2 1S transition isotope shifts. These two transitions lead to discrepant results for the nuclear charge radii difference between 4He and 3He. The accurate treatment of the finite nuclear mass effects is quite complicated and requires the use of the quantum field theoretical approach. We derive the α6m2/M correction with the help of nonrelativistic QED and dimensional regularization of the three-body Coulombic system and present accurate numerical results for low-lying states. The previously reported 4 σ discrepancy in the nuclear charge radius difference between 3He and 4He from two different atomic isotope shift transitions is confirmed, which calls for verification of experimental transition frequencies.

  4. Cold Rydberg atoms in a CO2 optical dipole trap

    NASA Astrophysics Data System (ADS)

    Gonçalves, 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.

  5. Towards Rydberg quantum optics in a hollow core fiber

    NASA Astrophysics Data System (ADS)

    Noaman, Mohammad; Langbecker, Maria; Windpassinger, Patrick

    2016-05-01

    Cold atoms inside hollow-core fibers present a promising candidate to study strongly coupled light-matter systems. Adding coherent quantum state control and the intriguing features of Rydberg atoms, i.e. long range dipolar interactions leading to a dipole blockade, to the system should allow for the generation of exotic polaritonic and photonic states. This talk will review the current status of our experimental setup where laser cooled Rubidium atoms are transported into a hollow-core fiber. We present the first measurements of Rydberg EIT in the dipole trap in front of the fiber and discuss the progress towards Rydberg physics in a quasi-one-dimensional geometry. This work is supported by FP7, Marie Curie ITN 317485, QTea.

  6. Charge-induced optical bistability in thermal Rydberg vapor

    NASA Astrophysics Data System (ADS)

    Weller, Daniel; Urvoy, Alban; Rico, Andy; Löw, Robert; Kübler, Harald

    2016-12-01

    We investigate the phenomenon of optical bistability in a driven ensemble of Rydberg atoms. By performing two experiments with thermal vapors of rubidium and cesium, we are able to shed light on the underlying interaction mechanisms causing such a nonlinear behavior. Due to the different properties of these two atomic species, we conclude that the large polarizability of Rydberg states in combination with electric fields of spontaneously ionized Rydberg atoms is the relevant interaction mechanism. In the case of rubidium, we directly measure the electric field in a bistable situation via two-species spectroscopy. In cesium, we make use of the different sign of the polarizability for different l states and the possibility of applying electric fields. Both these experiments allow us to rule out dipole-dipole interactions and support our hypothesis of a charge-induced bistability.

  7. 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. )

    1991-08-05

    We have measured the lifetime of the 2 {sup 3}S{sub 1} level in helium-like bromine with the result {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.

  8. 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.

  9. 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.

  10. Influence of structural-phase state of ferritic-martensitic steels on the helium porosity development

    NASA Astrophysics Data System (ADS)

    Chernov, I. I.; Staltsov, M. S.; Kalin, B. A.; Bogachev, I. A.; Guseva, L. Yu; Dzhumaev, P. S.; Emelyanova, O. V.; Drozhzhina, M. V.; Manukovsky, K. V.; Nikolaeva, I. D.

    2016-04-01

    Transmission electron microscopy (TEM) has been used to study the effect of the initial structural-phase state (SPhS) of ferritic-martensitic steels EK-181, EP-450 and EP-450- ODS (with 0.5 wt.% nanoparticles of Y2O3) on the of helium porosity formation and gas swelling. Different SPhS of steel EK-181 was produced by water quenching, annealing, normalizing plus tempered, intensive plastic deformation by torsion (HPDT). Irradiation was carried out by He+-40 keV ions at 923 K up to fluence of 5-1020 He+/m2. It is shown that the water quenching causes the formation of uniformly distributed small bubbles (d¯ ∼ 2 nm) of the highest density (ρ∼ 1025 m-3). After normalization followed by tempering as well as after annealing bubbles distribution is highly non-uniform both by volume and in size. Very large faceted bubbles (pre-equilibrium gas-filled voids) are formed in ferrite grains resulting in high level of gas swelling of the irradiated layer with S = 4,9 ± 1,2 and 3.8 ± 0.9% respectively. Nano- and microcrystalline structure created by HPDT completely degenerate at irradiation temperature and ion irradiation formed bubbles of the same parameters as in the annealed steel. Bubbles formed in EP-450-ODS steel are smaller in size and density, which led to a decrease of helium swelling by 4 times (S = 0.8 ± 0.2%) as compared to the swelling of the matrix steel EP-450 (S = 3.1 ± 0.7%).

  11. Anisotropic emission in quantum-beat spectroscopy of helium excited states

    NASA Astrophysics Data System (ADS)

    Lucchini, M.; Ludwig, A.; Zimmermann, T.; Kasmi, L.; Herrmann, J.; Scrinzi, A.; Landsman, A. S.; Gallmann, L.; Keller, U.

    2015-06-01

    We present quantum-beat spectroscopy of excited states of helium atoms populated selectively with high-order-harmonic emission below the atomic ionization potential by means of low-pass filtering of the pump radiation. The created electron wave packet is ionized by few-cycle infrared (IR) pulses leading to characteristic peaks in the photoelectron yield, which beat with a frequency proportional to the energy gap between the states involved in the two-color photoionization process. Minimizing the direct ionization by the extreme ultraviolet (XUV) radiation, we can follow the evolution of the electron wave packet also in the region of temporal pump-probe overlap. A detailed time-frequency analysis of the quantum beats and direct comparison with the solution of the time-dependent Schrödinger equation reveal the existence of quantum beats characterized by a final state of mixed parity. Finally, we show that by varying the carrier-envelope offset phase of the probe pulse, one can optically control the preferred direction of photoelectron emission and the contrast of such beats.

  12. Molecular Spectra in an Ultracold Strontium Rydberg Gas

    NASA Astrophysics Data System (ADS)

    Whalen, Joseph D.; Camargo, Francisco; Ding, Roger; Woehl, Germano, Jr.; Dunning, F. Barry; Killian, Thomas C.

    2016-05-01

    The interaction between a ground state atom and a highly excited Rydberg electron creates a potential that can support ultra-long-range bound molecular states comprising a Rydberg atom and several ground-state atoms. We excite these molecular states using two-photon spectroscopy in an ultracold gas of 84 Sr. In a thermal gas, we observe a highly structured spectrum of many-body bound states with one Rydberg atom and as many as three ground-state atoms in various vibrational levels. We also describe the spectrum in a dense, quantum degenerate gas, which is sensitive to the properties of the polaron formed by the binding of many atoms in the quantum gas to the Rydberg impurity. Because of the absence of a p-wave shape resonance in e-Sr scattering, the molecular spectrum in Sr provides a sensitive probe of the excitation dynamics in a quantum gas in a different regime than is accessible using Rb. Research supported by the AFOSR under Grant No. FA9550-14-1-0007, the NSF under Grants No. 1301773 and No. 1205946, the Robert A, Welch Foundation under Grants No. C-0734 and No. C-1844.

  13. Formation of Antihydrogen Rydberg atoms in strong magnetic field traps

    SciTech Connect

    Pohl, T.; Sadeghpour, H. R.

    2008-08-08

    It is shown that several features of antihydrogen production in nested Penning traps can be described with accurate and efficient Monte Carlo simulations. It is found that cold deeply-bound Rydberg states of antihydrogen (H-bar) are produced in three-body capture in the ATRAP experiments and an additional formation mechanism -Rydberg charge transfer-, particular to the nested Penning trap geometry, is responsible for the observed fast (hot) H-bar atoms. Detailed description of the numerical propagation technique for following extreme close encounters is given. An analytic derivation of the power law behavior of the field ionization spectrum is provided.

  14. Dipole-dipole induced global motion of Rydberg-dressed atom clouds

    NASA Astrophysics Data System (ADS)

    Genkin, M.; Wüster, S.; Möbius, S.; Eisfeld, A.; Rost, J. M.

    2014-05-01

    We consider two clouds of ground-state alkali atoms in two distinct hyperfine ground states. Each level is far off-resonantly coupled to a Rydberg state, which leads to dressed ground states with a weak admixture of the Rydberg state properties. Due to this admixture, for a proper choice of the Rydberg states, the atoms experience resonant dipole-dipole interactions that induce mechanical forces acting on all atoms within both clouds. This behaviour is in contrast to the dynamics predicted for bare dipole-dipole interactions between Rydberg superatoms, where only a single atom per cloud is subject to dipole-dipole induced motion (Möbius et al 2013 Phys. Rev. A 88 012716).

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

    NASA Astrophysics Data System (ADS)

    Argenti, L.; Jiménez-Galán, Á.; Marante, C.; Ott, C.; Pfeifer, T.; Martín, 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.

  16. Electro-optical properties of Rydberg excitons

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    We show how to compute the electro-optical functions (absorption, reflection, and transmission) when Rydberg exciton-polaritons appear, including the effect of the coherence between the electron-hole pair and the electromagnetic field. With the use of the real density matrix approach, numerical calculations applied for the Cu2O crystal are performed. We also examine in detail and explain the dependence of the resonance displacement on the state number and applied electric field strength. We report a fairly good agreement with recently published experimental data.

  17. Orthogonal flexible Rydberg aggregates

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  18. Quantum information with Rydberg atoms

    SciTech Connect

    Saffman, M.; Walker, T. G.; Moelmer, K.

    2010-07-15

    Rydberg atoms with principal quantum number n>>1 have exaggerated atomic properties including dipole-dipole interactions that scale as n{sup 4} and radiative lifetimes that scale as n{sup 3}. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. The availability of a strong long-range interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include long-range two-qubit gates, collective encoding of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing.

  19. 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.

  20. Quantum memory with strong and controllable Rydberg-level interactions

    NASA Astrophysics Data System (ADS)

    Li, Lin; Kuzmich, A.

    2016-11-01

    Realization of distributed quantum systems requires fast generation and long-term storage of quantum states. Ground atomic states enable memories with storage times in the range of a minute, however their relatively weak interactions do not allow fast creation of non-classical collective states. Rydberg atomic systems feature fast preparation of singly excited collective states and their efficient mapping into light, but storage times in these approaches have not yet exceeded a few microseconds. Here we demonstrate a system that combines fast quantum state generation and long-term storage. An initially prepared coherent state of an atomic memory is transformed into a non-classical collective atomic state by Rydberg-level interactions in less than a microsecond. By sheltering the quantum state in the ground atomic levels, the storage time is increased by almost two orders of magnitude. This advance opens a door to a number of quantum protocols for scalable generation and distribution of entanglement.

  1. Quantum memory with strong and controllable Rydberg-level interactions

    PubMed Central

    Li, Lin; Kuzmich, A

    2016-01-01

    Realization of distributed quantum systems requires fast generation and long-term storage of quantum states. Ground atomic states enable memories with storage times in the range of a minute, however their relatively weak interactions do not allow fast creation of non-classical collective states. Rydberg atomic systems feature fast preparation of singly excited collective states and their efficient mapping into light, but storage times in these approaches have not yet exceeded a few microseconds. Here we demonstrate a system that combines fast quantum state generation and long-term storage. An initially prepared coherent state of an atomic memory is transformed into a non-classical collective atomic state by Rydberg-level interactions in less than a microsecond. By sheltering the quantum state in the ground atomic levels, the storage time is increased by almost two orders of magnitude. This advance opens a door to a number of quantum protocols for scalable generation and distribution of entanglement. PMID:27869195

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

    NASA Astrophysics Data System (ADS)

    Ye, Shuzhen; Zhang, Xinyue; Killian, Thomas; Dunning, F.; Hiller, Moritz; Yoshida, Shuhei; Burgdoerfer, Joachim

    2013-05-01

    The production of very-high- n, n ~ 300, 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 at 461 and 413 nm. Rydberg series in the different strontium isotopes present in the beam can be selectively excited by tuning the 461 nm light allowing measurements of the isotope shifts in the series limits, that for 88Sr-86Sr being ~ + 210MHz, and that for 88Sr-84Sr being ~ + 440 MHz. Well-resolved Rydberg series can be seen for values of n approaching ~ 500. Photoexcitation spectra calculated using a two-active-electron model reproduce the relative strengths of the measured 1S0 and 1D2 lines. The surprisingly large photoexcitation rates provide new opportunities to study quasi-stable two-electron excited states and to explore the behavior of strongly coupled Rydberg systems at high n. Research supported by the NSF, the Robert A. Welch Foundation and the FWF (Austria).

  3. 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.

  4. Simulating quantum spin models using Rydberg-excited atomic ensembles in magnetic microtrap arrays

    NASA Astrophysics Data System (ADS)

    Whitlock, Shannon; Glaetzle, Alexander W.; Hannaford, Peter

    2017-04-01

    We propose a scheme to simulate lattice spin models based on strong, long-range interacting Rydberg atoms stored in a large-spacing array of magnetic microtraps. Each spin is encoded in a collective spin state involving a single nS or (n+1)S Rydberg atom excited from an ensemble of ground-state alkali atoms prepared via Rydberg blockade. After the excitation laser is switched off, the Rydberg spin states on neighbouring lattice sites interact via general XXZ spin–spin interactions. To read out the collective spin states we propose a single Rydberg atom triggered avalanche scheme in which the presence of a single Rydberg atom conditionally transfers a large number of ground-state atoms in the trap to an untrapped state which can be readily detected by site-resolved absorption imaging. Such a quantum simulator should allow the study of quantum spin systems in almost arbitrary one-dimensional and two-dimensional configurations. This paves the way towards engineering exotic spin models, such as spin models based on triangular-symmetry lattices which can give rise to frustrated-spin magnetism.

  5. Fast Rydberg antiblockade regime and its applications in quantum logic gates

    NASA Astrophysics Data System (ADS)

    Su, Shi-Lei; Gao, Ya; Liang, Erjun; Zhang, Shou

    2017-02-01

    Unlike the Rydberg blockade regime, the Rydberg antiblockade regime (RABR) allows more than one Rydberg atom to be excited, which can bring other interesting phenomena and applications. We propose an alternative scheme to quickly achieve the RABR. The proposed RABR can be implemented by adjusting the detuning of the classical driving field, which is, in turn, based on the former numbers of the excited Rydberg atoms. In contrast to the former schemes, the current one enables more than two atoms to be excited to Rydberg states in a short period of time and thus is useful for large-scale quantum information processing. The proposed RABR can be used to construct two- and multiqubit quantum logic gates. In addition, a Rydberg excitation superatom, which can decrease the blockade error and enlarge the blockade radius for Rydberg blockade-based schemes, is constructed based on the suggested RABR and used to realize a more robust quantum logic gate. The mechanical effect and the ionization are discussed, and the performance is investigated using the master-equation method. Finally, other possible applications of the present RABR are also given.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Liquid helium nanodroplets, consisting of on average 2 × 106 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 (Hen)* 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.

  7. Solid-state ring laser gyro behaving like its helium-neon counterpart at low rotation rates.

    PubMed

    Schwartz, Sylvain; Gutty, François; Feugnet, Gilles; Loil, Eric; Pocholle, Jean-Paul

    2009-12-15

    Nonlinear couplings induced by crystal diffusion and spatial inhomogeneities of the gain have been suppressed over a broad range of angular velocities in a solid-state ring laser gyro by vibrating the gain crystal at 168 kHz and 0.4 microm along the laser cavity axis. This device behaves in the same way as a typical helium-neon ring laser gyro, with a zone of frequency lock-in (or dead band) resulting from the backscattering of light on the cavity mirrors. Furthermore, it is shown that the level of angular random-walk noise in the presence of mechanical dithering depends only on the quality of the cavity mirrors, as is the case with typical helium-neon ring laser gyros.

  8. Modeling Jupiter's Interior with a Hydrogen-Helium Equation of State Derived From First Principles Computer Simulations

    NASA Astrophysics Data System (ADS)

    Militzer, B.; Vorberger, J.; Hubbard, W.

    2006-12-01

    We report results from recent investigations of the interior structure of Jupiter using state-of-the-art computer simulations of dense fluid hydrogen and helium. Thermodynamic properties used in the models were obtained using density-functional molecular dynamics (DFT-MD) simulations on a grid of temperature and density points spanning the interiors of the planets. In addition to calculations for pure hydrogen, simulation results for the different concentrations of hydrogen- helium mixtures are presented. The corrections to the commonly used linear mixing approximation are characterized, and it is demonstrated how the presence of helium increases the stability of the molecular phase of hydrogen. Our interior models update the suite of models that were based on the widely used Saumon-Chabrier-Van Horn (SCVH) equation of state for hydrogen and helium. Deviations of the DFT-EOS from SCVH are up to about ±5% depending on the pressure, and thus affect interior models at the same level as possible effects of a jovian core. Unlike SCVH, the computed DFT-EOS does not predict any first-order thermodynamic discontinuities associated with pressure-dissociation and metallization of hydrogen. Instead, the DFT-EOS predicts that the molecular dissociation leads intermediate decrease in pressure, which has profound effects on the thermodynamic properties in a zone approximately 6000 km below the 1-bar level in Jupiter. Our results will eventually aid in interpretation of data expected from the Juno orbiter mission. Supported by NASA PGG Grants NAG5-13775 and PGG04-0000-0116 and NSF Grant 0507321.

  9. 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

  10. 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.

  11. Interaction of Rydberg atoms with surfaces. Using surface ionisation as a probe for surface analysis

    NASA Astrophysics Data System (ADS)

    Kohlhoff, Mike W.

    2016-12-01

    The interface of neutral Rydberg atoms in the gas phase with a solid surface is of interest in many fields of modern research. This interface poses a particular challenge for any application in which Rydberg atoms are close to a substrate but also opens up the possibility of studying properties of the surface material itself through the atomic response. In this review the focus is on the process of electron tunneling from the excited state into the substrate that occurs when a Rydberg atom is located in front of a surface at a range of a few hundred nm and is demonstrated with a metallic surface. It is shown how variations in this ionisation mechanism can provide a powerful tool to probe image-charge effects, measure small superficial electric stray or patch fields and how charge transfer from the Rydberg atom can be in resonance with energetically discrete surface states.

  12. Accessing Rydberg-dressed interactions using many-body Ramsey dynamics

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rick; Killian, Thomas C.; Hazzard, Kaden R. A.

    2016-11-01

    We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions in a many-body system well within experimentally measured lifetimes, in contrast to previous research, which either focused on interactions near Förster resonances or on few-atom systems. We build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, which we demonstrate can be used to characterize the Rydberg-dressed interactions. Furthermore, the dynamics can differ significantly from that observed in other spin systems. As one example, spin echo can increase the rate at which coherence decays. The results also apply to bare (undressed) Rydberg states as a special case, for which we quantitatively reproduce recent ultrafast experiments without fitting.

  13. Universal Nonequilibrium Properties of Dissipative Rydberg Gases

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  14. Universal nonequilibrium properties of dissipative Rydberg gases.

    PubMed

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

    2014-11-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  16. 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)

  17. Coherent Transient Effect Studies of Rydberg Atoms.

    DTIC Science & Technology

    1982-09-01

    occurs in a Rydberg gas at the densities requil for transient experiments (NA1.2 atoms/cmut). The-decay process was studied using ion collection and...rather than in the visible. Although experiments with (visible) tunable dye lasers are therefore not possible, one can use powerful, stable cw...construction of atomic Rydberg lasers, the use of Rydberg atoms as high-sensitivity microwave detectors (already demonstrated by Figger et al), 14 and

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Metastable pionic helium (πHe+) is a three-body atom composed of a helium nucleus, an electron occupying the 1s ground state, and a negatively charged pion π- in a Rydberg state with principal and orbital angular momentum quantum numbers of n ˜ℓ+1˜16. We calculate the spin-independent energies of the π3He+ and π4He+ isotopes in the region n =15-19. These include relativistic and quantum electrodynamics corrections of orders R∞α2 and R∞α3 in atomic units, where R∞ and α denote the Rydberg and fine structure constants. The fine-structure splitting due to the coupling between the electron spin and the orbital angular momentum of the π- and the radiative and Auger decay rates of the states are also calculated. Some states (n,ℓ)=(16,15) and (17,16) retain nanosecond-scale lifetimes against π- absorption into the helium nucleus. We propose the use of laser pulses to induce π- transitions from these metastable states to states with large (˜1011 s-1) Auger rates. The πHe2+ ion that remains after Auger emission of the 1s electron undergoes Stark mixing with the s, p, and d states during collisions with the helium atoms in the experimental target. This leads to immediate nuclear absorption of the π -. The resonance condition between the laser beam and the atom is thus revealed as a sharp spike in the rates of neutrons, protons, deuterons, and tritons that emerge. A resonance curve is obtained from which the πHe+ transition frequency can in principle be determined with a fractional precision of 10-8-10-6 provided the systematic uncertainties can be controlled. By comparing the measured πHe+ frequencies with the calculated values, the π- mass may be determined with a similar precision. The πHe+ will be synthesized by allowing a high-intensity (>108 s-1) beam of π-produced by a cyclotron to come to rest in a helium target. The precise time structure of the π- beam is used to ensure a sufficient rate of coincidence between the resonant laser pulses

  19. Calculation of the Shape of S-State Electron Bubbles in Liquid Helium

    NASA Astrophysics Data System (ADS)

    Maris, Humphrey J.; Guo, Wei

    2007-08-01

    We consider the shape of electron bubbles in liquid helium. Grinfeld and Kojima (Phys. Rev. Lett. 91, 105301, 2003) have shown that the in a certain pressure range the 2S electron bubble is unstable against small distortions with l=3 and loses its spherical symmetry. We report more detailed calculations of this effect and also study the behavior of the 3S and 2P bubbles.

  20. 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.

  1. Quantum melting of two-component Rydberg crystals

    NASA Astrophysics Data System (ADS)

    Lan, Zhihao; Li, Weibin; Lesanovsky, Igor

    2016-11-01

    We investigate the quantum melting of one-dimensional crystals that are realized in an atomic lattice in which ground state atoms are laser excited to two Rydberg states. We focus on a regime where both, intra- and interstate density-density interactions as well as coherent exchange interactions contribute. We determine stable crystalline phases in the classical limit and explore their melting under quantum fluctuations introduced by the excitation laser as well as two-body exchange. We find that within a specific parameter range quantum fluctuations introduced by the laser can give rise to a devil's staircase structure which one might associate with transitions in the classical limit. The melting through exchange interactions is shown to also proceed in a steplike fashion, in the case of small crystals, due to the proliferation of Rydberg spin waves.

  2. Entropy and complexity analysis of hydrogenic Rydberg atoms

    SciTech Connect

    Lopez-Rosa, S.; Toranzo, I. V.; Dehesa, J. S.; Sanchez-Moreno, P.

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  4. Investigation of cold rubidium Rydberg atoms in a magneto-optical trap

    SciTech Connect

    Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Ryabtsev, I. I. Chapovsky, P. L.

    2009-03-15

    This paper reports on the results of experiments with cold rubidium Rydberg atoms in a magneto-optical trap. The specific feature of the experiments is the excitation of Rydberg atoms in a small volume within a cloud of cold atoms and the sorting of measured signals and spectra according to the number of detected Rydberg atoms. The effective lifetime of the 37P Rydberg state and its polarizability in a weak electric field are measured. The results obtained are in good agreement with theoretical calculations. It is demonstrated that the localization of the excitation volume in the vicinity of the zero-magnetic-field point makes it possible to improve the spectral resolution and to obtain narrow microwave resonances in Rydberg atoms without switching off the quadrupole magnetic field of the trap. The dependence of the amplitude of dipole-dipole interaction resonances in Rydberg atoms on the number of atoms is measured. This dependence exhibits a linear behavior and agrees with the theory for a weak dipole-dipole interaction.

  5. Proposal for manipulating and detecting spin and orbital States of trapped electrons on helium using cavity quantum electrodynamics.

    PubMed

    Schuster, D I; Fragner, A; Dykman, M I; Lyon, S A; Schoelkopf, R J

    2010-07-23

    We propose a hybrid architecture in which an on-chip high finesse superconducting cavity is coupled to the lateral motion and spin state of a single electron trapped on the surface of superfluid helium. We estimate the motional coherence times to exceed 15  μs, while energy will be coherently exchanged with the cavity photons in less than 10 ns for charge states and faster than 1  μs for spin states, making the system attractive for quantum information processing and strong coupling cavity quantum electrodynamics experiments. The cavity is used for nondestructive readout and as a quantum bus mediating interactions between distant electrons or an electron and a superconducting qubit.

  6. Calculation of Rydberg energy levels for the francium atom

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Zhong; Chu, Jin-Min

    2010-06-01

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

  7. 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 Schrödinger 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.

  8. Spectral backbone of excitation transport in ultracold Rydberg gases

    NASA Astrophysics Data System (ADS)

    Scholak, Torsten; Wellens, Thomas; Buchleitner, Andreas

    2014-12-01

    The spectral structure underlying excitonic energy transfer in ultracold Rydberg gases is studied numerically, in the framework of random matrix theory, and via self-consistent diagrammatic techniques. Rydberg gases are made up of randomly distributed, highly polarizable atoms that interact via strong dipolar forces. Dynamics in such a system is fundamentally different from cases in which the interactions are of short range, and is ultimately determined by the spectral and eigenvector structure. In the energy levels' spacing statistics, we find evidence for a critical energy that separates delocalized eigenstates from states that are localized at pairs or clusters of atoms separated by less than the typical nearest-neighbor distance. We argue that the dipole blockade effect in Rydberg gases can be leveraged to manipulate this transition across a wide range: As the blockade radius increases, the relative weight of localized states is reduced. At the same time, the spectral statistics, in particular, the density of states and the nearest-neighbor level-spacing statistics, exhibits a transition from approximately a 1-stable Lévy to a Gaussian orthogonal ensemble. Deviations from random matrix statistics are shown to stem from correlations between interatomic interaction strengths that lead to an asymmetry of the spectral density and profoundly affect localization properties. We discuss approximations to the self-consistent Matsubara-Toyozawa locator expansion that incorporate these effects.

  9. Observation of Rydberg-Atom Macrodimers: Micrometer-Sized Diatomic Molecules

    NASA Astrophysics Data System (ADS)

    Saßmannshausen, Heiner; Deiglmayr, Johannes

    2016-08-01

    Long-range metastable molecules consisting of two cesium atoms in high Rydberg states have been observed in an ultracold gas. A sequential three-photon two-color photoassociation scheme is employed to form these molecules in states, which correlate to n p (n +1 )s dissociation asymptotes. Spectral signatures of bound molecular states are clearly resolved at the positions of avoided crossings between long-range van der Waals potential curves. The experimental results are in agreement with simulations based on a detailed model of the long-range multipole-multipole interactions of Rydberg-atom pair states. We show that a full model is required to accurately predict the occurrence of bound Rydberg macrodimers. The macrodimers are distinguished from repulsive molecular states by their behavior with respect to spontaneous ionization and possible decay channels are discussed.

  10. Intrinsic optical bistability in a strongly driven Rydberg ensemble

    NASA Astrophysics Data System (ADS)

    de Melo, Natalia R.; Wade, Christopher G.; Šibalić, Nikola; Kondo, Jorge M.; Adams, Charles S.; Weatherill, Kevin J.

    2016-06-01

    We observe and characterize intrinsic optical bistability in a dilute Rydberg vapor. The bistability is characterized by sharp jumps between states of low and high Rydberg occupancy with jump-up and -down positions displaying hysteresis depending on the direction in which the control parameter is changed. We find that the shift in frequency of the jump point scales with the fourth power of the principal quantum number. Also, the width of the hysteresis window increases with increasing principal quantum number, before reaching a peak and then closing again. The experimental results are consistent with predictions from a simple theoretical model based on semiclassical Maxwell-Bloch equations including the effects of interaction-induced broadening and level shifts. These results provide insight into the dynamics of driven dissipative systems.

  11. Few-body quantum physics with strongly interacting Rydberg polaritons

    NASA Astrophysics Data System (ADS)

    Bienias, Przemyslaw

    2016-12-01

    We present an extension of our recent paper [Bienias et al., Phys. Rev. A 90, 053804 (2014)] in which we demonstrated the scattering properties and bound-state structure of two Rydberg polaritons, as well as the derivation of the effective low-energy many-body Hamiltonian. Here, we derive a microscopic Hamiltonian describing the propagation of Rydberg slow light polaritons in one dimension. We describe possible decoherence processes within a Master equation approach, and derive equations of motion in a Schroedinger picture by using an effective non-Hermitian Hamiltonian. We illustrate diagrammatic methods on two examples: First, we show the solution for a single polariton in an external potential by exact summation of Feynman diagrams. Secondly, we solve the two body problem in a weakly interacting regime exactly.

  12. 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.

  13. Collective excitation of Rydberg-atom ensembles beyond the superatom model.

    PubMed

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

    2014-12-05

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

  14. Electronic dynamics in helium nanodroplets studied via femtosecond XUV pump / UV probe photoelectron imaging

    NASA Astrophysics Data System (ADS)

    Ziemkiewicz, Michael; Bacellar, Camila; Leone, Stephen; Neumark, Daniel; Gessner, Oliver

    2014-05-01

    Superfluid helium nanodroplets consisting of ~ 2 × 106 atoms are examined using femtosecond time-resolved photoelectron imaging. The droplets are excited by a 23.6(2) eV extreme ultraviolet (XUV) pulse in resonance with an electronically excited band associated largely with the 1s3p Rydberg level of free He atoms. Relaxation dynamics are monitored by ionizing transient states with a 3.2 eV probe pulse and measuring the time-dependent photoelectron kinetic energy distributions using velocity map imaging (VMI). A broad, intense signal associated with the initially excited 1s3p band (Ekin ~ 2.5 eV) appears within the experimental time resolution and decays within 190(70) fs. Concomitantly, a second photoelectron feature with kinetic energies ranging from 0 to 0.5 eV appears on a time scale of ~ 200 fs. The new feature is identified as originating from the 1s2p droplet Rydberg band, indicating the direct observation of a previously suggested interband relaxation within the droplet. This feature also decays within ~ 200 fs, likely due to intraband relaxation within the 1s2p/1s2s manifold to states which are too deeply bound to be ionized by the 3.2 eV probe pulse.

  15. Cold Rydberg atom collisions in a dipole trap

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    We have built a new experimental setup to investigate cold Rydberg atom collision in a high atomic density sample in a CO2 dipole trap. Briefly, we load 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. After this phase, the trapping and repumper laser beams are turned off and we wait 100 ms 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. In this new setup, we can image the ions onto a MCP detector to study the spatial distribution. The electrons maybe detected also by another MCP. During the presentation we shall present preliminary results involving the excitation of nD+nD states. We acknowledge financial support from FAPESP, CNPq, INCT-IQ, AFOSR (FA9550-09-1-0503)

  16. Two-dimensional Rydberg gases and the quantum hard-squares model.

    PubMed

    Ji, S; Ates, C; Lesanovsky, I

    2011-08-05

    We study a two-dimensional lattice gas of atoms that are photoexcited to Rydberg states in which they interact via the van der Waals interaction. We explore the regime of dominant nearest-neighbor interaction where this system is intimately connected with a quantum version of Baxter's hard-squares model. We show that the strongly correlated ground state of the Rydberg gas can be analytically described by a projected entangled pair state that constitutes the ground state of the quantum hard-squares model. This correspondence allows us to identify a phase boundary where the Rydberg gas undergoes a transition from a disordered (liquid) phase to an ordered (solid) phase.

  17. CaH Rydberg series, oscillator strengths and photoionization cross sections from Molecular Quantum Defect and Dyson Orbital theories

    NASA Astrophysics Data System (ADS)

    Velasco, A. M.; Lavín, C.; Díaz-Tinoco, Manuel; Ortiz, J. V.

    2017-01-01

    In this work, electron-propagator methods are applied to the calculation of the ionization potential and vertical excitation energies for several Rydberg series of the CaH molecule. The present calculations cover more highly excited states than those previously reported. In particular, excitation energies for ns (n>5), np (n>5), nd (n>4) and nf Rydberg states are given. Oscillator strengths for electronic transitions involving Rydberg states of CaH, as well as photoionization cross sections for Rydberg channels, also have been determined by using the Molecular Quantum Defect Orbital approach. Good agreement has been found with the scarce comparative data that are available for oscillator strengths. To our knowledge, predictions of photoionization cross sections from the outermost orbital of CaH are made here for the first time. A Cooper minimum and mixed atomic orbital character in some of the Dyson orbitals are among the novel features of these present calculations.

  18. 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.

  19. Exploring dipole blockade using high- n strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Zhang, Xinyue; Ye, Shuzhen; Dunning, F. Barry; Hiller, Moritz; Yoshida, Shuhei; Burgdörfer, Joachim

    2014-05-01

    Studies of the production of strongly-polarized quasi-1D high- n, n ~ 300 , strontium `` nF'' Rydberg states in an atomic beam by three-photon excitation in a weak dc field suggest that (in the absence of blockade effects) densities of ~106 cm-3 might be achieved. At such densities the interparticle separation, ~ 100 μm , becomes comparable to that at which dipole blockade effects are expected to become important. Apparatus modifications are underway to allow the exploration of blockade at very high- n and the effects of the high energy level density. Blockade is also being examined through calculations of the energy spectrum for two interaction atoms. Access to the blockade regime promises creation of Rydberg atoms at well-defined separations whose interactions can be coherently controlled using electric field pulses thereby enabling study of the dynamics of strongly-coupled Rydberg systems. Research supported by the NSF, the Robert A. Welch Foundation, and the FWF (Austria).

  20. Laser frequency locking based on Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We present a laser frequency locking to Rydberg transition with electromagnetically induced transparency (EIT) spectra in a room-temperature cesium vapor cell. Cesium levels 6S1/2, 6P3/2, and the nD5/2 state, compose a cascade three-level system, where a coupling laser drives Rydberg transition, and probe laser detects the EIT signal. The error signal, obtained by demodulating the EIT signal, is used to lock the coupling laser frequency to Rydberg transition. The laser frequency fluctuation, ˜0.7 MHz, is obtained after locking on, with the minimum Allan variance to be 8.9 × 10-11. This kind of locking method can be used to stabilize the laser frequency to the excited transition. Project supported by the National Basic Research Program of China (Grant No. 2012CB921603), the National Natural Science Foundation of China (Grants Nos. 11274209, 61475090, 61378039, and 61378013), and the Research Project Supported by Shanxi Scholarship Council of China (Grant No. 2014-009).

  1. Many-body interferometry of a Rydberg-dressed spin lattice

    NASA Astrophysics Data System (ADS)

    Zeiher, Johannes; van Bijnen, Rick; Schauß, Peter; Hild, Sebastian; Choi, Jae-Yoon; Pohl, Thomas; Bloch, Immanuel; Gross, Christian

    2016-12-01

    Ultracold atoms in optical lattices are ideal to study fundamentally new quantum many-body systems including frustrated or topological magnetic phases and supersolids. However, the necessary control of strong long-range interactions between distant ground state atoms has remained a long-standing goal. Optical dressing of ground state atoms via off-resonant laser coupling to Rydberg states is one way to tailor such interactions. Here we report the realization of coherent Rydberg dressing to implement a two-dimensional synthetic spin lattice. Our single-atom-resolved interferometric measurements of the many-body dynamics enable the microscopic probing of the interactions and reveal their highly tunable range and anisotropy. Our work marks the first step towards the use of laser-controlled Rydberg interactions for the study of exotic quantum magnets in optical lattices.

  2. 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.

  3. 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.

  4. 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.

  5. Spectroscopy of cesium Rydberg atoms in strong radio-frequency fields

    NASA Astrophysics Data System (ADS)

    Jiao, Yuechun; Han, Xiaoxuan; Yang, Zhiwei; Li, Jingkui; Raithel, Georg; Zhao, Jianming; Jia, Suotang

    2016-08-01

    We study Rydberg atoms modulated by strong radio-frequency (rf) fields with a frequency of 70 MHz. The Rydberg atoms are prepared in a room-temperature cesium cell, and their level structure is probed using electromagnetically induced transparency (EIT). As the rf field increases from the weak- into the strong-field regime, the range of observed rf-induced phenomena progresses from ac level shifts through increasingly pronounced and numerous rf modulation sidebands to complex state mixing and level crossings with high - l hydrogenlike states. Weak anharmonic admixtures in the rf field generate clearly visible modifications in the Rydberg EIT spectra. A Floquet analysis is employed to model the Rydberg spectra, and good agreement with the experimental observations is found. Our results show that all-optical spectroscopy of Rydberg atoms in vapor cells can serve as an antenna-free, atom-based, and calibration-free technique to measure rf electric fields and to analyze their higher-harmonic contents.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  8. Optical techniques for Rydberg physics in lattice geometries. A technical guide

    NASA Astrophysics Data System (ADS)

    Naber, Julian B.; Vos, Jannie; Rengelink, Robert J.; Nusselder, Rosanne J.; Davtyan, David

    2016-12-01

    We address the technical challenges when performing quantum information experiments with ultracold Rydberg atoms in lattice geometries. We discuss the following key aspects: (i) the coherent manipulation of atomic ground states, (ii) the coherent excitation of Rydberg states, and (iii) spatial addressing of individual lattice sites. We briefly review methods and solutions which have been successfully implemented, and give examples based on our experimental apparatus. This includes an optical phase-locked loop, an intensity and frequency stabilization setup for lasers, and a nematic liquid-crystal spatial light modulator.

  9. 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.

  10. Storage and control of optical photons using Rydberg polaritons.

    PubMed

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

    2013-03-08

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

  11. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

    NASA Astrophysics Data System (ADS)

    Gorniaczyk, H.; Tresp, C.; Bienias, P.; Paris-Mandoki, A.; Li, W.; Mirgorodskiy, I.; Büchler, H. P.; Lesanovsky, I.; Hofferberth, S.

    2016-08-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates.

  12. Controlling the interactions between cold Rydberg atoms by a time-varying electric field

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Long-range interactions between cold Rydberg atoms are being investigated for neutral-atom quantum computing, quantum simulations, phase transitions in cold Rydberg gases and other applications. Fine tuning of the interaction strength can be implemented using Förster resonances between Rydberg atoms controlled by an electric field. The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. The application of the radio-frequency field causes additional Förster resonances between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb(nP 3/2) + Rb(nP 3/2) → Rb(nS 1/2) + Rb([n + 1]S 1/2) for two Rb Rydberg atoms interacting in a time-varying electric field.

  13. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

    PubMed Central

    Gorniaczyk, H.; Tresp, C.; Bienias, P.; Paris-Mandoki, A.; Li, W.; Mirgorodskiy, I.; Büchler, H. P.; Lesanovsky, I.; Hofferberth, S.

    2016-01-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates. PMID:27515278

  14. 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)

  15. Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology

    SciTech Connect

    Hankin, Aaron Michael

    2014-08-01

    With the advent of laser cooling and trapping, neutral atoms have become a foundational source of accuracy for applications in metrology and are showing great potential for their use as qubits in quantum information. In metrology, neutral atoms provide the most accurate references for the measurement of time and acceleration. The unsurpassed stability provided by these systems make neutral atoms an attractive avenue to explore applications in quantum information and computing. However, to fully investigate the eld of quantum information, we require a method to generate entangling interactions between neutral-atom qubits. Recent progress in the use of highly-excited Rydberg states for strong dipolar interactions has shown great promise for controlled entanglement using the Rydberg blockade phenomenon. I report the use of singly-trapped 133Cs atoms as qubits for applications in metrology and quantum information. Each atom provides a physical basis for a single qubit by encoding the required information into the ground-state hyper ne structure of 133Cs. Through the manipulation of these qubits with microwave and optical frequency sources, we demonstrate the capacity for arbitrary single-qubit control by driving qubit rotations in three orthogonal directions on the Bloch sphere. With this control, we develop an atom interferometer that far surpasses the force sensitivity of other approaches by applying the well-established technique of lightpulsed atom-matterwave interferometry to single atoms. Following this, we focus on two-qubit interactions using highly-excited Rydberg states. Through the development of a unique single-photon approach to Rydberg excitation using an ultraviolet laser at 319 nm, we observe the Rydberg blockade interaction between atoms separated by 6.6(3) m. Motivated by the observation of Rydberg blockade, we study the application of Rydberg-dressed states for a quantum controlled-phase gate. Using a realistic simulation of the

  16. 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.

  17. Sub-Poissonian Statistics of Jamming Limits in Ultracold Rydberg Gases

    NASA Astrophysics Data System (ADS)

    Sanders, Jaron; Jonckheere, Matthieu; Kokkelmans, Servaas

    2015-07-01

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

  18. Detrimental adsorbate fields in experiments with cold Rydberg gases near surfaces

    NASA Astrophysics Data System (ADS)

    Hattermann, H.; Mack, M.; Karlewski, F.; Jessen, F.; Cano, D.; Fortágh, J.

    2012-08-01

    We observe the shift of Rydberg levels of rubidium close to a copper surface when atomic clouds are repeatedly deposited on it. We measure transition frequencies of rubidium to S and D Rydberg states with principal quantum numbers n between 31 and 48 using the technique of electromagnetically induced transparency. The spectroscopic measurement shows a strong increase of electric fields towards the surface that evolves with the deposition of atoms. Starting with a clean surface, we measure the evolution of electrostatic fields in the range between 30 and 300 μm from the surface. We find that after the deposition of a few hundred atomic clouds, each containing ˜106 atoms, the field of adsorbates reaches 1 V/cm for a distance of 30 μm from the surface. This evolution of the electrostatic field sets serious limitations on cavity QED experiments proposed for Rydberg atoms on atom chips.

  19. First analysis of the B1Σ+ (υ=1) Rydberg state in the lesser-abundant 12C17O isotopologue on the basis of the 1-υ″ progression of the Ångström band system

    NASA Astrophysics Data System (ADS)

    Hakalla, Rafał; Zachwieja, Mirosław; Szajna, Wojciech

    2014-06-01

    So far unobserved in the 12C17O isotopologue, the 1-υ″ progression of the Ångström (B1Σ+-A1Π) band system was recorded under high resolution in the 17,200-22,950 cm-1 spectral region as an emission spectrum using high-accuracy dispersive optical spectroscopy. The 12C17O molecules were formed and excited in two steps in a stainless steel hollow-cathode lamp with two anodes. The emission from the discharge was observed with a plane-grating spectrograph and recorded by a photomultiplier tube. In the studied region, the full rotational structure of the 1-1 and 1-5 bands of the B-A system was observed, in total 114 spectral emission lines up to J″=21. All those lines were precisely measured with an estimated accuracy of about 0.0030 cm-1, and rotationally analyzed. As a result, many molecular constants were determined for the B1Σ+ and A1Π states in the 12C17O isotopologue. In this paper we have also presented the results of calculations concerning RKR turning points, Franck-Condon factors, relative intensities, and r-centroids for the Ångström band system in the 12C17O molecule. We have also determined the value of the ΔG1/2 vibrational quantum, the isotope shifts, as well as the main, isotopically invariant parameters of the B1Σ+ Rydberg state in the CO molecule within the Born-Oppenheimer approximation. For the A1Π, υ=5 state, considerable irregularities of the rotational structure have been observed and analyzed in detail. Suspected candidates responsible for these perturbations have been identified. The B1Σ+, υ=1 state has been thoroughly analyzed in terms of possible perturbations and it emerged to be completely regular in the 12C17O molecule up to the observed maximum J value.

  20. Nonlinear Optical Studies of Rydberg Atoms Using Degenerate Four-Wave Mixing.

    DTIC Science & Technology

    1984-08-01

    AD-Ai46 827 NONLINEAR OPTICAL STUDIES OF RYDBERG ATOMS USING 1/2 DEGENERATE FOUR -WAVE MIXING(U) HUGHES RESEARCH LABS MALIBU CA J F LAM ET AL. AUG 84...146 827 NONLINEAR OPTICAL STUDIES OF RYDBERG ATOMS USING DEGENERATE FOUR -WAVE MIXING J.F. Lam, R.A. McFarlane, and D.G. StMel Hughes Research...techniques were developed nearly degenerate four -wave mixing, polarization nearly degenerate four -wave mixing, fre- quency domain three-state

  1. Controlled long-range interactions between Rydberg atoms and ions

    NASA Astrophysics Data System (ADS)

    Secker, T.; Gerritsma, R.; Glaetzle, A. W.; Negretti, A.

    2016-07-01

    We theoretically investigate trapped ions interacting with atoms that are coupled to Rydberg states. The strong polarizabilities of the Rydberg levels increase the interaction strength between atoms and ions by many orders of magnitude, as compared to the case of ground-state atoms, and may be mediated over micrometers. We calculate that such interactions can be used to generate entanglement between an atom and the motion or internal state of an ion. Furthermore, the ion could be used as a bus for mediating spin-spin interactions between atomic spins in analogy to much employed techniques in ion-trap quantum simulation. The proposed scheme comes with attractive features as it maps the benefits of the trapped-ion quantum system onto the atomic one without obviously impeding its intrinsic scalability. No ground-state cooling of the ion or atom is required and the setup allows for full dynamical control. Moreover, the scheme is to a large extent immune to the micromotion of the ion. Our findings are of interest for developing hybrid quantum information platforms and for implementing quantum simulations of solid-state physics.

  2. Proton formation in 2+1 resonance enhanced multiphoton excitation of HCl and HBr via (Omega=0) Rydberg and ion-pair states.

    PubMed

    Romanescu, Constantin; Loock, Hans-Peter

    2007-09-28

    Molecular beam cooled HCl was state selected by two-photon excitation of the V (1) summation operator(0(+)) [v=9,11-13,15], E (1) summation operator(0(+)) [v=0], and g (3) summation operator(-)(0(+)) [v=0] states through either the Q(0) or Q(1) lines of the respective (1,3) summation operator(0(+))<--<--X (1) summation operator(0(+)) transition. Similarly, HBr was excited to the V (1) summation operator(0(+)) [v=m+3, m+5-m+8], E (1) summation operator(0(+)) [v=0], and H (1) summation operator(0(+)) [v=0] states through the Q(0) or Q(1) lines. Following absorption of a third photon, protons were formed by three different mechanisms and detected using velocity map imaging. (1) H(*)(n=2) was formed in coincidence with (2)P(i) halogen atoms and subsequently ionized. For HCl, photodissociation into H(*)(n=2)+Cl((2)P(12)) was dominant over the formation of Cl((2)P(32)) and was attributed to parallel excitation of the repulsive [(2) (2)Pi4llambda] superexcited (Omega=0) states. For HBr, the Br((2)P(32))Br((2)P(12)) ratio decreases with increasing excitation energy. This indicates that both the [(3) (2)Pi(12)5llambda] and the [B (2) summation operator5llambda] superexcited (Omega=0) states contribute to the formation of H(*)(n=2). (2) For selected intermediate states HCl was found to dissociate into the H(+)+Cl(-) ion pair with over 20% relative yield. A mechanism is proposed by which a bound [A (2) summation operatornlsigma] (1) summation operator(0(+)) superexcited state acts as a gateway state to dissociation into the ion pair. (3) For all intermediate states, protons were formed by dissociation of HX(+)[v(+)] following a parallel, DeltaOmega=0, excitation. The quantum yield for the dissociation process was obtained using previously reported photoionization efficiency data and was found to peak at v(+)=6-7 for HCl and v(+)=12 for HBr. This is consistent with excitation of the repulsive A(2) summation operator(12) and (2) (2)Pi states of HCl(+), and the (3) (2)Pi state

  3. Ground-state properties of hcp helium-4 on the basis of a cell model

    NASA Technical Reports Server (NTRS)

    Jacobi, N.; Zmuidzinas, J. S.

    1977-01-01

    A simple cell model is used to compute the ground-state energy and the volume-pressure relation for hcp He-4, in good agreement with experiments and with more sophisticated quantum mechanical calculations.

  4. Optimal control for Rydberg quantum technology building blocks

    NASA Astrophysics Data System (ADS)

    Müller, Matthias M.; Pichler, Thomas; Montangero, Simone; Calarco, Tommaso

    2016-04-01

    We consider a platform for quantum technology based on Rydberg atoms in optical lattices where each atom encodes one qubit of information and external lasers can manipulate their state. We demonstrate how optimal control theory enables the functioning of two specific building blocks on this platform: We engineer an optimal protocol to perform a two-qubit phase gate and to transfer the information within the lattice among specific sites. These two elementary operations allow to design very general operations like storage of atoms and entanglement purification as, for example, needed for quantum repeaters.

  5. 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.

  6. 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.

  7. Landau-Zener transitions in frozen pairs of Rydberg atoms.

    PubMed

    Saquet, Nicolas; Cournol, Anne; Beugnon, Jérôme; 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-->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.

  8. High-Rydberg Xenon Submillimeter-Wave Detector

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara

    1987-01-01

    Proposed detector for infrared and submillimeter-wavelength radiation uses excited xenon atoms as Rydberg sensors instead of customary beams of sodium, potassium, or cesium. Chemically inert xenon easily stored in pressurized containers, whereas beams of dangerously reactive alkali metals must be generated in cumbersome, unreliable ovens. Xenon-based detector potential for infrared astronomy and for Earth-orbiter detection of terrestrial radiation sources. Xenon atoms excited to high energy states in two stages. Doubly excited atoms sensitive to photons in submillimeter wavelength range, further excited by these photons, then ionized and counted.

  9. 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.

  10. Effect of initial-state target polarization on the single ionization of helium by 1-keV electron impact

    NASA Astrophysics Data System (ADS)

    Sun, Shi-Yan; Ma, Xiao-Yan; Li, Xia; Miao, Xiang-Yang; Jia, Xiang-Fu

    2012-07-01

    We report new results of triple differential cross sections for the single ionization of helium by 1-KeV electron impact at the ejection energy of 10 eV. Investigations have been made for both the perpendicular plane and the plane perpendicular to the momentum transfer geometries. The present calculation is based on the three-Coulomb wave function. Here we have also incorporated the effect of target polarization in the initial state. A comparison is made between the present calculation with the results of other theoretical methods and a recent experiment [Dürr M, Dimopoulou C, Najjari B, Dorn A, Bartschat K, Bray I, Fursa D V, Chen Z, Madison D H and Ullrich J 2008 Phys. Rev. A 77 032717]. At an impact energy of 1 KeV, the target polarization is found to induce a substantial change of the cross section for the ionization process. We observe that the effect of target polarization plays a dominant role in deciding the shape of triple differential cross sections.

  11. Theoretical energies for the n = 1 and 2 states of the helium isoelectronic sequence up to Z = 100

    NASA Technical Reports Server (NTRS)

    Drake, G. W.

    1988-01-01

    The unified method described previously for combining high-precision nonrelativistic variational calculations with relativistic and quantum electrodynamic corrections is applied to the 1s2 1S0, 1s2s 1S0, 1s2s 1S0, 1s2s 3S1, 1s2p 1P1, and 1s2p 3P(0.1,2) states of helium-like ions. Detailed tabulations are presented for all ions in the range Z = 2-100 and are compared with a wide range of experimental data up to (Kr-34)+. The results for (U-90)+ significantly alter the recent Lamb shift measurement of Munger and Gould (1986) from 70.4 + or - 8.3 to 71.0 + or - 8.3 eV, in comparison with a revised theoretical value of 74.3 + or - 0.4 eV. The improved agreement is due to the inclusion of higher order two-electron corrections in the present work.

  12. Entropic properties of D-dimensional Rydberg systems

    NASA Astrophysics Data System (ADS)

    Toranzo, I. V.; Puertas-Centeno, D.; Dehesa, J. S.

    2016-11-01

    The fundamental information-theoretic measures (the Rényi Rp [ ρ ] and Tsallis Tp [ ρ ] entropies, p > 0) of the highly-excited (Rydberg) quantum states of the D-dimensional (D > 1) hydrogenic systems, which include the Shannon entropy (p → 1) and the disequilibrium (p = 2), are analytically determined by use of the strong asymptotics of the Laguerre orthogonal polynomials which control the wavefunctions of these states. We first realize that these quantities are derived from the entropic moments of the quantum-mechanical probability ρ(r →) densities associated to the Rydberg hydrogenic wavefunctions Ψ n , l , { μ }(r →) , which are closely connected to the Lp-norms of the associated Laguerre polynomials. Then, we determine the (n → ∞)-asymptotics of these norms in terms of the basic parameters of our system (the dimensionality D, the nuclear charge and the hyperquantum numbers (n , l , { μ }) of the state) by use of recent techniques of approximation theory. Finally, these three entropic quantities are analytically and numerically discussed in terms of the basic parameters of the system for various particular states.

  13. 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.

  14. Helium tables.

    NASA Technical Reports Server (NTRS)

    Havill, Clinton H

    1928-01-01

    These tables are intended to provide a standard method and to facilitate the calculation of the quantity of "Standard Helium" in high pressure containers. The research data and the formulas used in the preparation of the tables were furnished by the Research Laboratory of Physical Chemistry, of the Massachusetts Institute of Technology.

  15. 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.

  16. 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.

  17. 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.

  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. Phase dependent excitation of Rydberg atoms in non-zero average fields

    NASA Astrophysics Data System (ADS)

    Magnuson, Eric; Carrat, Vincent; Gallagher, Tom

    2016-05-01

    The final energy of an electron excited to a high lying Rydberg state in the presence of a microwave (MW) field shows a dependence on the phase of the field at which the excitation occurs. This phase dependence is comparable to that seen in strong field experiments using attosecond pulses to probe systems perturbed by intense infrared (IR) fields. In zero average field, final energies exhibit a phase dependence at twice the frequency of the MW field. We show a phase dependence at the same frequency as the MW field emerges in the presence of a non-zero average field, parallel to the MW polarization. To isolate phase dependence at the MW frequency, we amplitude modulate the IR excitation laser and phase lock this modulation to the MW field. Li atoms are excited to states near the ionization limit in the presence of a MW field, and bound Rydberg states (n>150) are detected. In an applied average field, we observe modulation of the Rydberg signal at the MW frequency. This modulation vanishes as the average field is zeroed, but persists even in fields large enough to ionize most of the population. We compare these results to symmetry arguments and a model of classical Rydberg orbits. An experiment to determine the absolute phase of the modulation relative the MW field is discussed. This work is supported by the US Department of Energy.

  20. 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.

  1. 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.

  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. 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.

  4. 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.

  5. Robust quantum logic in neutral atoms via adiabatic Rydberg dressing

    DOE PAGES

    Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; ...

    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

  6. 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

  7. 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.

  8. Characterizing high- n quasi-one-dimensional strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Hiller, Moritz; Yoshida, Shuhei; Burgdörfer, Joachim; Ye, Shuzhen; Zhang, Xinyue; Dunning, F. Barry

    2014-05-01

    The production of high- n, n ~ 300 , quasi-one-dimensional strontium Rydberg atoms by two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The polarization of the product states is probed using three independent techniques which are analyzed with the aid of classical-trajectory Monte Carlo simulations that employ initial ensembles based on quantum calculations using a two-active-electron model. Comparisons between theory and experiment demonstrate that the product states have large dipole moments, ~ 1 . 0 - 1 . 2n2 a . u . and that they can be engineered using pulsed electric fields to create a wide variety of target states. Research supported by the NSF, the Robert A Welch Foundation, and the FWF (Austria).

  9. Ab initio calculation of Hubbard parameters for Rydberg-dressed atoms in a one-dimensional optical lattice

    NASA Astrophysics Data System (ADS)

    Chougale, Yashwant; Nath, Rejish

    2016-07-01

    We obtain ab initio the Hubbard parameters for Rydberg-dressed atoms in a one-dimensional (1D) sinusoidal optical lattice on the basis of maximally-localized Wannier states. Finite range, soft-core interatomic interactions become the trait of Rydberg admixed atoms, which can be extended over many neighboring lattice sites. In contrast to dipolar gases, where the interactions follow an inverse cubic law, the key feature of Rydberg-dressed interactions is the possibility of making neighboring couplings to the same magnitude as that of the onsite ones. The maximally-localized Wannier functions (MLWFs) are typically calculated via a spread-minimization procedure (Marzari N and Vanderbilt D 1997 Phys. Rev. B 56 12847) and are always found to be real functions apart from a trivial global phase when an isolated set of Bloch bands are considered. For an isolated single Bloch band, the above procedure reduces to a simple quasi-momentum-dependent unitary phase transformation. Here, instead of minimizing the spread, we employ a diagonal phase transformation which eliminates the imaginary part of the Wannier functions. The resulting Wannier states are found to be maximally localized and in exact agreement with those obtained via a spread-minimization procedure. Using these findings, we calculate the Hubbard couplings from the Rydberg admixed interactions, including dominant density-assisted tunneling (DAT) coefficients. Finally, we provide realistic lattice parameters for the state-of-the-art experimental Rydberg-dressed rubidium setup.

  10. 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.

  11. Xe2 gerade Rydberg states observed in the afterglow of a microplasma by laser spectroscopy of a^3 {Σ }_u^ + ( {1_u,O_u^ - }) absorption in the green (545-555 nm) and near-infrared (675-800 nm)

    NASA Astrophysics Data System (ADS)

    Wagner, C. J.; Galvin, T. C.; Eden, J. G.

    2014-06-01

    Bound←bound transitions of the Xe dimer at small internuclear separation (R < 4.0 Å) have been observed in the 545-555 nm and 675-800 nm spectral regions by laser spectroscopy in the afterglow of a pulsed Xe microplasma with a volume of ˜160 nl. Transient suppression of Xe2 A^1 {Σ }_u^ + ( {O_u^ + }) to X^1 {Σ }_g^ + ( {O_g^ + }) emission in the vacuum ultraviolet (˜172 nm), induced by laser excitation of {Ω }_g leftarrow a^3 {Σ }_u^ + ( {1_u,O_u^ - }) [Rydberg←Rydberg] transitions of the molecule, has confirmed the existence of structure between 720 and 770 nm (reported by Killeen and Eden [J. Chem. Phys. 84, 6048 (1986)]) but also reveals red-degraded vibrational bands extending to wavelengths beyond 800 nm. Spectral simulations based on calculations of Franck-Condon factors for assumed {Ω }_g leftarrow a^3 {Σ }_u^ + transitions involving Ω = 0±,1 gerade Rydberg states suggest that the upper level primarily responsible for the observed spectrum is an Ω = 1 state correlated, in the separated atom limit, with Xe(5p6 1S0) + Xe(5p5 6p) and built on a predominantly A2Π3/2g molecular ion core. Specifically, the spectroscopic constants for the upper state of the 1_g leftarrow 1_u,O_u^ ± absorptive transitions are determined to be Te = 13 000 ± 150 cm-1, ω _e^' = 120 ± 10 cm^{ - 1}, ω _e^' x_e^' = 1.1 ± 0.4 cm^{ - 1}, De = 3300 ± 300 cm-1, and {Δ }R_e = R_e^' - R_e^' ' } = 0.3 ± 0.1 {Å} which are in general agreement with the theoretical predictions of the pseudopotential hole-particle formalism, developed by Jonin and Spiegelmann [J. Chem. Phys. 117, 3059 (2002)], for both the (5)1g and ( 3)O_g^ + states of Xe2. These spectra exhibit the most extensive vibrational development, and provide evidence for the first molecular core-switching transition, observed to date for any of the rare gas dimers at small R (<4 Ǻ). Experiments in the green (545-555 nm) also provide improved absorption spectra, relative to data reported in 1986 and 1999

  12. Ultracold molecular Rydberg physics in a high density environment

    NASA Astrophysics Data System (ADS)

    Eiles, Matthew T.; Pérez-Ríos, Jesús; Robicheaux, F.; Greene, Chris H.

    2016-06-01

    Sufficiently high densities in Bose-Einstein condensates provide favorable conditions for the production of ultralong-range polyatomic molecules consisting of one Rydberg atom and a number of neutral ground state atoms. The chemical binding properties and electronic wave functions of these exotic molecules are investigated analytically via hybridized diatomic states. The effects of the molecular geometry on the system’s properties are studied through comparisons of the adiabatic potential curves and electronic structures for both symmetric and randomly configured molecular geometries. General properties of these molecules with increasing numbers of constituent atoms and in different geometries are presented. These polyatomic states have spectral signatures that lead to non-Lorentzian line-profiles.

  13. Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Gavryusev, V.; Signoles, A.; Ferreira-Cao, M.; Zürn, G.; Hofmann, C. S.; Günter, G.; Schempp, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.

    2016-08-01

    We present combined measurements of the spatially resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, while the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.

  14. 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.

  15. Natural widths and blackbody radiation induced shift and broadening of Rydberg levels in magnesium ions

    NASA Astrophysics Data System (ADS)

    Glukhov, Igor L.; Mokhnenko, Sergey N.; Nikitina, Elizaveta A.; Ovsiannikov, Vitaly D.

    2015-01-01

    Theoretical analysis is presented of the natural lifetimes and blackbody-radiation (BBR)-induced shifts and widths of Rydberg states with small and large angular momenta l. Asymptotic presentations in elementary functions are derived for matrix elements of bound-bound, bound-free and threshold radiative transitions from hydrogenic-type states with large angular momenta, applicable to both hydrogen-like and many-electron atoms and ions. For states with small angular momenta two numerical methods based on the quantum defects were used and corresponding data are compared with one another and with the most reliable data of the literature. Asymptotic approximations are derived for natural lifetimes, thermal shifts and broadening of Rydberg states of small and high l and principal quantum numbers n ≫ 1.

  16. Simulating the absorption spectra of helium clusters (N = 70, 150, 231, 300) using a charge transfer correction to superposition of fragment single excitations.

    PubMed

    Ge, Qinghui; Mao, Yuezhi; White, Alec F; Epifanovsky, Evgeny; Closser, Kristina D; Head-Gordon, Martin

    2017-01-28

    Simulations of the n = 2 absorption spectra of HeN (N = 70, 150, 231, 300) clusters are reported, with nuclear configurations sampled by path integral molecular dynamics. The electronic structure is treated by a new approach, ALMO-CIS+CT, which is a formulation of configuration interaction singles (CIS) based on absolutely localized molecular orbitals (ALMOs). The method generalizes the previously reported ALMO-CIS model [K. D. Closser et al. J. Chem. Theory Comput. 11, 5791 (2015)] to include spatially localized charge transfer (CT) effects. It is designed to recover large numbers of excited states in atomic and molecular clusters, such as the entire n = 2 Rydberg band in helium clusters. ALMO-CIS+CT is shown to recover most of the error caused by neglecting charge transfer in ALMO-CIS and has comparable accuracy to standard CIS for helium clusters. For the n = 2 band, CT stabilizes states towards the blue edge by up to 0.5 eV. ALMO-CIS+CT retains the formal cubic scaling of ALMO-CIS with respect to system size. With improvements to the implementation over that originally reported for ALMO-CIS, ALMO-CIS+CT is able to treat helium clusters with hundreds of atoms using modest computing resources. A detailed simulation of the absorption spectra associated with the 2s and 2p bands of helium clusters up to 300 atoms is reported, using path integral molecular dynamics with a spherical boundary condition to generate atomic configurations at 3 K. The main features of experimentally reported fluorescence excitation spectra for helium clusters are reproduced.

  17. Simulating the absorption spectra of helium clusters (N = 70, 150, 231, 300) using a charge transfer correction to superposition of fragment single excitations

    NASA Astrophysics Data System (ADS)

    Ge, Qinghui; Mao, Yuezhi; White, Alec F.; Epifanovsky, Evgeny; Closser, Kristina D.; Head-Gordon, Martin

    2017-01-01

    Simulations of the n = 2 absorption spectra of HeN (N = 70, 150, 231, 300) clusters are reported, with nuclear configurations sampled by path integral molecular dynamics. The electronic structure is treated by a new approach, ALMO-CIS+CT, which is a formulation of configuration interaction singles (CIS) based on absolutely localized molecular orbitals (ALMOs). The method generalizes the previously reported ALMO-CIS model [K. D. Closser et al. J. Chem. Theory Comput. 11, 5791 (2015)] to include spatially localized charge transfer (CT) effects. It is designed to recover large numbers of excited states in atomic and molecular clusters, such as the entire n = 2 Rydberg band in helium clusters. ALMO-CIS+CT is shown to recover most of the error caused by neglecting charge transfer in ALMO-CIS and has comparable accuracy to standard CIS for helium clusters. For the n = 2 band, CT stabilizes states towards the blue edge by up to 0.5 eV. ALMO-CIS+CT retains the formal cubic scaling of ALMO-CIS with respect to system size. With improvements to the implementation over that originally reported for ALMO-CIS, ALMO-CIS+CT is able to treat helium clusters with hundreds of atoms using modest computing resources. A detailed simulation of the absorption spectra associated with the 2s and 2p bands of helium clusters up to 300 atoms is reported, using path integral molecular dynamics with a spherical boundary condition to generate atomic configurations at 3 K. The main features of experimentally reported fluorescence excitation spectra for helium clusters are reproduced.

  18. High-resolution Rydberg tagging time-of-flight measurements of atomic photofragments by single-photon vacuum ultraviolet laser excitation

    SciTech Connect

    Jones, Brant; Zhou Jingang; Yang Lei; Ng, C. Y.

    2008-12-15

    By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF measurements of O({sup 3}P{sub 2}) and S({sup 3}P{sub 2}) formed in the photodissociation of SO{sub 2} and CS{sub 2} at 193.3 and 202.3 nm, respectively. These results are compared to those obtained by employing the VUV laser photoionization time-sliced velocity-mapped ion imaging technique. The fact that the kinetic energy resolutions achieved in the VUV laser high-n Rydberg tagging TOF measurements of O and S atoms are found to be higher than those observed in the VUV laser photoionization, time-sliced velocity-mapped ion imaging studies show that the single-photon VUV laser high-n Rydberg tagging TOF method is useful and complementary to state-of-the-art time-sliced velocity-mapped ion imaging measurements of heavier atomic photofragments, such as O and S atoms. Furthermore, the general agreement observed between the VUV laser high-n Rydberg tagging TOF and velocity-mapped ion imaging experiments supports the conclusion that the lifetimes of the tagged Rydberg states of O and S atoms are sufficiently long to allow the reliable determination of state-resolved UV photodissociation cross sections of SO{sub 2} and CS{sub 2} by using the VUV laser high-n Rydberg tagging TOF method.

  19. High-resolution Rydberg tagging time-of-flight measurements of atomic photofragments by single-photon vacuum ultraviolet laser excitation.

    PubMed

    Jones, Brant; Zhou, Jingang; Yang, Lei; Ng, C Y

    2008-12-01

    By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF measurements of O((3)P(2)) and S((3)P(2)) formed in the photodissociation of SO(2) and CS(2) at 193.3 and 202.3 nm, respectively. These results are compared to those obtained by employing the VUV laser photoionization time-sliced velocity-mapped ion imaging technique. The fact that the kinetic energy resolutions achieved in the VUV laser high-n Rydberg tagging TOF measurements of O and S atoms are found to be higher than those observed in the VUV laser photoionization, time-sliced velocity-mapped ion imaging studies show that the single-photon VUV laser high-n Rydberg tagging TOF method is useful and complementary to state-of-the-art time-sliced velocity-mapped ion imaging measurements of heavier atomic photofragments, such as O and S atoms. Furthermore, the general agreement observed between the VUV laser high-n Rydberg tagging TOF and velocity-mapped ion imaging experiments supports the conclusion that the lifetimes of the tagged Rydberg states of O and S atoms are sufficiently long to allow the reliable determination of state-resolved UV photodissociation cross sections of SO(2) and CS(2) by using the VUV laser high-n Rydberg tagging TOF method.

  20. Dipole-dipole resonance line shapes in a cold Rydberg gas

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    We have explored the dipole-dipole mediated, resonant energy transfer reaction, 32 p3 /2+32 p3 /2→32 s +33 s , in an ensemble of cold 85Rb Rydberg atoms. Stark tuning is employed to measure the population transfer probability as a function of the total electronic energy difference between the initial and final atom-pair states over a range of Rydberg densities, 2 ×108≤ρ ≤3 ×109 cm-3. The observed line shapes provide information on the role of beyond nearest-neighbor interactions, the range of Rydberg atom separations, and the electric field inhomogeneity in the sample. The widths of the resonance line shapes increase approximately linearly with the Rydberg density and are only a factor of 2 larger than expected for two-body, nearest-neighbor interactions alone. These results are in agreement with the prediction [B. Sun and F. Robicheaux, Phys. Rev. A 78, 040701(R) (2008), 10.1103/PhysRevA.78.040701] that beyond nearest-neighbor exchange interactions should not influence the population transfer process to the degree once thought. At low densities, Gaussian rather than Lorentzian line shapes are observed due to electric field inhomogeneities, allowing us to set an upper limit for the field variation across the Rydberg sample. At higher densities, non-Lorentzian, cusplike line shapes characterized by sharp central peaks and broad wings reflect the random distribution of interatomic distances within the magneto-optical trap (MOT). These line shapes are well reproduced by an analytic expression derived from a nearest-neighbor interaction model and may serve as a useful fingerprint for characterizing the position correlation function for atoms within the MOT.

  1. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Photoionisation of a helium atom involving autoionisation states coupled by a circularly polarised laser field

    NASA Astrophysics Data System (ADS)

    Gryzlova, E. V.; Magunov, A. I.; Rotter, I.; Strakhova, S. I.

    2005-01-01

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

  2. 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.

  3. Anisotropic Interactions between Cold Rydberg Atoms

    DTIC Science & Technology

    2015-09-28

    processes in an atomic sample trapped in a CO2 optical dipole trap. The process was investigated as a function of: i) atomic density; ii) dc electric...Objective: The main goal in this research is to study anisotropy in Förster resonances involving Rydberg atoms trapped in the CO2 optical dipole...of the lasers , the multi-level nature and potential of pair distribution function. The natural question is “which mechanism is responsible for the

  4. Exotic topological density waves in cold atomic Rydberg-dressed fermions.

    PubMed

    Li, Xiaopeng; Sarma, S Das

    2015-05-14

    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.

  5. 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

  6. Ultrafast relaxation dynamics of electronically excited piperidine: ionization signatures of Rydberg/valence evolution.

    PubMed

    Klein, Liv B; Thompson, James O F; Crane, Stuart W; Saalbach, Lisa; Sølling, Theis I; Paterson, Martin J; Townsend, Dave

    2016-09-14

    We have investigated the electronic relaxation dynamics of gas-phase piperidine (a secondary aliphatic amine) using time-resolved photoelectron imaging. Following 200 nm excitation, spectrally sharp and highly anisotropic photoelectron data reveal ultrafast (60 fs) internal conversion between the initially excited 3px Rydberg state and the lower-lying 3s Rydberg state, mediated by the evolution of nσ* valence character along the 3px N-C bond. This behaviour is in good agreement with previously reported findings for several tertiary aliphatic amines. In contrast to the these systems, however, much broader photoelectron signals exhibiting only very small angular anisotropy and two distinct decay timescales (180 fs and 1.7 ps) were also observed. As confirmed by our supporting calculations, this is attributable to nσ* valence character now evolving along the N-H stretching coordinate within the 3s Rydberg state as the molecule starts dissociating to yield H atom photoproducts in conjunction with ground state piperidinyl radicals. By analogy with systems such as ammonia and morpholine, we conclude this event may occur either promptly or, alternatively, via a "frustrated" process where the system repeatedly traverses the upper cone of a conical intersection with the ground state until the required region of phase space is sampled to facilitate non-adiabatic population transfer. Our findings reveal the role of several different nuclear coordinate motions in driving stepwise internal conversion across multiple potential energy surfaces and the distinct photoionization signatures that are associated with these processes.

  7. 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.

  8. Laser resonance photoionization spectroscopy of Rydberg levels in Fr

    SciTech Connect

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

    1987-09-21

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

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

    PubMed

    Schempp, H; Günter, G; Wüster, S; Weidemüller, 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.

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

    SciTech Connect

    Militzer, B.; Hubbard, W. B.

    2013-09-10

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

  11. Strong enhancement of Penning ionization for asymmetric atom pairs in cold Rydberg gases: the Tom and Jerry effect

    NASA Astrophysics Data System (ADS)

    Efimov, D. K.; Miculis, K.; Bezuglov, N. N.; Ekers, A.

    2016-06-01

    We consider Penning ionization of Rydberg atom pairs as an Auger-type process induced by the dipole-dipole interaction and employ semiclassical formulae for dipole transitions to calculate the autoionization width as a function of the principal quantum numbers, n d , n i , of both atoms. While for symmetric atom pairs with {n}d={n}i={n}0 the well-known increase of the autoionization width with increasing n 0 is obtained, the result for asymmetric pairs is counterintuitive—for a fixed n i of the ionizing atom of the pair, the autoionization width strongly increases with decreasing n d of the de-excited atom. For H Rydberg atoms this increase reaches two orders of magnitude at the maximum of the n d dependence, and the same type of counterintuitive behavior is exhibited also by Na, Rb and Cs atoms. This is a purely quantum-mechanical effect, which points towards existence of optimal (we call them ‘Tom’ and ‘Jerry’ for ‘big’ and ‘small’) pairs of Rydberg atoms with respect to autoionization efficiency. Building on the model of population redistribution in cold Rydberg gases proposed in [1], we demonstrate that population evolution following the initial laser excitation of Rydberg atoms in state n 0 would eventually lead to the formation of such Tom-Jerry pairs with {n}i\\gt {n}0\\gt {n}d which feature autoionization widths that are enhanced by several orders of magnitude compared to that of two atoms in the initial laser-excited state n 0. We also show that in the high-density regime of cold Rydberg gas experiments the ionization rate of Tom-Jerry pairs can be substantially larger than the blackbody radiation-induced photoionization rate.

  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. 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.

  14. 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.

  15. Imaging spatial correlations of Rydberg excitations in cold atom clouds

    NASA Astrophysics Data System (ADS)

    Schwarzkopf, Andrew; Sapiro, Rachel; Raithel, Georg

    2011-05-01

    Previously, Rydberg excitation blockades have been shown to cause a saturation of Rydberg excitation numbers in atom samples and a narrowing of the excitation number statistics, and they have been employed in quantum information experiments. In the experiment described in this talk, we present measurements of structures in the Rydberg pair correlation function similar to those predicted in. To achieve sufficient spatial magnification, we use the principle of field ion microscopy. A tungsten tip is placed close to a cold atom cloud in which several Rydberg excitations are prepared using a narrow-linewidth laser. To read out the sample, the tip voltage is suddenly switched to a high value. The Rydberg atoms are field-ionized, and the resultant ions are projected onto a nearby position-sensitive detector. We present the dependence of the pair correlation function on the principle quantum number and other parameters. We gratefully acknowledge support from AFOSR and NSF-FOCUS.

  16. Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR.

    PubMed

    Matsuki, Yoh; Nakamura, Shinji; Fukui, Shigeo; Suematsu, Hiroto; Fujiwara, Toshimichi

    2015-10-01

    Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (vR=4-12 kHz) at cryogenic temperatures (T=35-120 K) for over a week without consuming helium at a cost for electricity of 16 kW/h. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T=40 K and B0=16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.

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

    SciTech Connect

    Potapov, A. V. Panfilov, V. A.; Surin, L. A.; Dumesh, B. S.

    2010-11-15

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

  18. Long-range interactions between rubidium and potassium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Samboy, Nolan

    2017-03-01

    We investigate the long-range, two-body interactions between rubidium and potassium atoms in highly excited (n =70 ) Rydberg states. After establishing properly symmetrized asymptotic basis states, we diagonalize an interaction Hamiltonian consisting of the standard Coulombic potential expansion and atomic fine structure to calculate electronic potential energy curves. We find that when both atoms are excited to either the 70 s state or the 70 p state, both the Ω =0+ symmetry interactions and the Ω =0- symmetry interactions demonstrate a deep potential well capable of supporting many bound levels; the sizes of the corresponding dimer states are of the order of 2.25 μ m . We establish n -scaling relations for the equilibrium separation Re and the dissociation energy De and find these relations to be consistent with similar calculations involving the homonuclear interactions between rubidium and cesium. We discuss the specific effects of ℓ mixing and the exact composition of the calculated potential well via the expansion coefficients of the asymptotic basis states. Finally, we apply a Landau-Zener treatment to show that the dimer states are stable with respect to predissociation.

  19. The importance of Rydberg orbitals in dissociative ionization of small hydrocarbon molecules in intense few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Wells, E.; Voznyuk, A.; Mahowald, J. B.; Schmitz, D. G.; Burwitz, T. G.; Jochim, B.; Zohrabi, M.; Betsch, K. J.; Severt, T.; Berry, B.; Kling, N. G.; Ablikim, U.; Carnes, K. D.; Ben-Itzhak, I.; Siemering, R.; Kling, M. F.; de Vivie-Riedle, R.

    2015-05-01

    Much of our intuition about strong-field processes is built upon studies of diatomic molecules, which have relatively well separated electronic states. In polyatomic molecules, however, the electronic states are closer together, leading to more complex interactions. A combined experimental and theoretical investigation of strong-field ionization followed by hydrogen elimination in the hydrocarbon series C2D2, C2D4, and C2D6 reveals that the photofragment angular distributions can only be understood when ionization from Rydberg orbitals is considered. These commonly neglected Rydberg orbitals are readily populated for some orientations of the molecule relative to the laser polarization, leading to dissociation patterns and an intensity dependence consistent with significant Rydberg orbital influence. Our results suggest that Rydberg states should be routinely considered when studying polyatomic molecules in intense laser fields. Funding provided by National Science Foundation grant 1404185, the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, and the DFG.

  20. Dipole-quadrupole Förster resonance in cesium Rydberg gas

    NASA Astrophysics Data System (ADS)

    Maineult, Wilfried; Pelle, Bruno; Faoro, Riccardo; Arimondo, Ennio; Pillet, Pierre; Cheinet, Patrick

    2016-11-01

    The resonant energy transfer between two close particles, also known as Förster resonance in atomic or biological systems, is usually associated with dipole-dipole interaction. In Rydberg atoms, it is a widely used tool to enhance the interactions between particles. Here, we observe a resonant energy transfer between Rydberg atoms that cannot be attributed to a dipole-dipole interaction, owing to selection rules, and comes instead from an efficient dipole-quadrupole process. We compare the measured probability transfer with a theoretical model including quadrupolar terms and find very good agreement with our measurement. Further studies of those multipolar resonances should probe their dependences on various parameters (quantum numbers, relative orientation of the atoms), and may find some applications in quantum procedures where dipole-dipole resonance cannot be used, for instance where the states of interest have a difference in angular momentum of two.

  1. 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

    2015-04-03

    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.

  2. Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

    NASA Astrophysics Data System (ADS)

    Seiler, Ch; Agner, J. A.; Pillet, P.; Merkt, F.

    2016-05-01

    Supersonic beams of hydrogen atoms, prepared selectively in Rydberg-Stark states of principal quantum number n in the range between 25 and 35, have been deflected by {90}\\circ , decelerated and loaded into off-axis electric traps at initial densities of ≈ {10}6 atoms cm-3 and translational temperatures of 150 mK. The ability to confine the atoms spatially was exploited to study their decay by radiative and collisional processes. The evolution of the population of trapped atoms was measured for several milliseconds in dependence of the principal quantum number of the initially prepared states, the initial Rydberg-atom density in the trap, and the temperature of the environment of the trap, which could be varied between 7.5 and 300 K using a cryorefrigerator. At room temperature, the population of trapped Rydberg atoms was found to decay faster than expected on the basis of their natural lifetimes, primarily because of absorption and emission stimulated by the thermal radiation field. At the lowest temperatures investigated experimentally, the decay was found to be multiexponential, with an initial rate scaling as {n}-4 and corresponding closely to the natural lifetimes of the initially prepared Rydberg-Stark states. The decay rate was found to continually decrease over time and to reach an almost n-independent rate of more than (1 ms)-1 after 3 ms. To analyze the experimentally observed decay of the populations of trapped atoms, numerical simulations were performed which included all radiative processes, i.e., spontaneous emission as well as absorption and emission stimulated by the thermal radiation. These simulations, however, systematically underestimated the population of trapped atoms observed after several milliseconds by almost two orders of magnitude, although they reliably predicted the decay rates of the remaining atoms in the trap. The calculations revealed that the atoms that remain in the trap for the longest times have larger absolute values of the

  3. Steady state boiling crisis in a helium vertically heated natural circulation loop - Part 2: Friction pressure drop lessening

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

    2016-01-01

    Experiments were conducted on a 2-m high two-phase helium natural circulation loop operating at 4.2 K and 1 atm. Two heated sections with different internal diameter (10 and 6 mm) were tested. The power applied on the heated section wall was controlled in increasing and decreasing sequences, and temperature along the section, mass flow rate and pressure drop evolutions were registered. The post-CHF regime was studied watching simultaneously the evolution of boiling crisis onset along the test section and the evolution of pressure drop and mass flow rate. A significant lessening of friction was observed simultaneous to the development of the post-CHF regime, accompanied by a mass flow rate increase, which lets suppose that the vapor film in the film boiling regime acts as a lubricant. A model was created based on this idea and on heat transfer considerations. The predictions by this model are satisfactory for the low quality post-CHF regime.

  4. One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

    NASA Astrophysics Data System (ADS)

    Pifrader, Alexandra; Allard, Olivier; Auböck, Gerald; Callegari, Carlo; Ernst, Wolfgang E.; Huber, Robert; Ancilotto, Francesco

    2010-10-01

    Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies (≈3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n +1)p←ns transition of K, Rb, and Cs (n =4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d←5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked.

  5. High-Resolution Spectroscopy of He{_2}^+ Using Rydberg-Series Extrapolation and Zeeman-Decelerated Supersonic Beams of Metastable He_2

    NASA Astrophysics Data System (ADS)

    Jansen, Paul; Semeria, Luca; Merkt, Frederic

    2016-06-01

    Having only three electrons, He{_2}^+ represents a system for which highly accurate ab initio calculations are possible. The latest calculations of rovibrational energies in He{_2}^+ do not include relativistic or QED corrections but claim an accuracy of 120 MHz 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 metastable helium molecules 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 system 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 an unprecedented accuracy of 18 MHz, to quantify the size of the relativistic and QED corrections by comparison with the results of Tung et al. and to precisely measure the rotational structure of the metastable state for comparison with the results of Focsa et al. Here, we present an extension of these measurements in which we have measured higher rotational intervals of He{_2}^+. In addition, we have replaced the pulsed UV laser by a cw UV laser and improved the resolution of the spectra by a factor of more than five. W.-C. Tung, M. Pavanello and L. Adamowicz, J. Chem. Phys. 136, 104309 (2012). P. Jansen, L. Semeria, L. Esteban Hofer, S. Scheidegger, J.A. Agner, H. Schmutz, and F. Merkt, Phys. Rev. Lett. 115, 133202 (2015). D. Sprecher, J. Liu, T. Krähenmann, M. Schäfer, and F. Merkt, J. Chem. Phys. 140, 064304 (2014). M

  6. State-selective preparation of A r2 + and K r2 + by resonantly enhanced two-photon double ionization via intermediate Rydberg states using high-order harmonics

    NASA Astrophysics Data System (ADS)

    Yamada, Kana; Iwasaki, Atsushi; Sato, Takahiro; Midorikawa, Katsumi; Yamanouchi, Kaoru

    2016-11-01

    Simultaneous two-electron emission processes of Ar induced by high-order harmonics of near-infrared femtosecond laser pulses were investigated by coincidence photoelectron spectroscopy. Two-photon double ionization processes via the 3 s 3 p6n p (n ˜25 ) intermediate resonances of Ar were observed, which selectively created the 3 s 3 p51P state of A r2 + . The similar double ionization processes were also observed in Kr. The selective creation indicates that the core electron configuration of the doubly ionized state tends to be the same as that of the intermediate state and that the emitted two electrons tend to form the singlet state.

  7. Microwave electric field sensing with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Stack, Daniel T.; Kunz, Paul D.; Meyer, David H.; Solmeyer, Neal

    2016-05-01

    Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.

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

    USGS Publications Warehouse

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

    2011-01-01

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

  9. Fine structure and ionization energy of the 1s2s2p 4P state of the helium negative ion He-.

    PubMed

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

    2014-12-31

    The fine structure and ionization energy of the 1s2s2p (4)P state of the helium negative ion He(-) are calculated in Hylleraas coordinates, including relativistic and QED corrections up to O(α(4)mc(2)), O((μ/M)α(4)mc(2)), O(α(5)mc(2)), and O((μ/M)α(5)mc(2)). Higher order corrections are estimated for the ionization energy. A comparison is made with other calculations and experiments. We find that the present results for the fine structure splittings agree with experiment very well. However, the calculated ionization energy deviates from the experimental result by about 1 standard deviation. The estimated theoretical uncertainty in the ionization energy is much less than the experimental accuracy.

  10. Spin-forbidden radiative decay rates from the 3 {sup 3}P{sub 1,2} and 3 {sup 1}P{sub 1} states of helium

    SciTech Connect

    Morton, Donald C.; Drake, G. W. F.

    2011-04-15

    We have calculated atomic helium spontaneous decay rates and absorption oscillator strengths for the spin-forbidden transitions from 3 {sup 3}P{sub 1,2} and 3 {sup 1}P{sub 1} to all lower {sup 1}S{sub 0} and {sup 3}S{sub 1} states. In particular we found A{sub 10}=44.33(4) s{sup -1} for the E1 transition 3 {sup 3}P{sub 1}-1 {sup 1}S{sub 0} and 0.1147(1) s{sup -1} for the M2 transition 3 {sup 3}P{sub 2}-1 {sup 1}S{sub 0}.

  11. Roles of the Rydberg transitions in fast excitation transfer studied in cyclohexane and n-heptane using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Kimura, Kazuie; Hormes, Josef

    1983-09-01

    Excitation spectra of PPO (2,5-diphenyl oxazole) in cyclohexane solution show peaks at 63 000 and 78 000 cm-1, while those in n-heptane solution show a single peak near 66 000 cm-1. The 63 000 cm-1 peak for cyclohexane and 66 000 cm-1 peak for n heptane are ascribed to excitation transfer at respective valence-band absorption peaks. An extra peak at 78 000 cm-1 for cyclohexane solution is tentatively ascribable to the Rydberg transitions and it is situated near the eighth peak of the Rydberg series. The expanded reaction radius is, therefore, estimated to be about 30 Å. Taking account of the Rydberg series can explain the known fact that excitation transfer in cyclohexane is extraordinarily fast compared with that in n heptane. Kinetic analysis shows that these upper excited states at 63 000 and 78 000 cm-1 of cyclohexane make direct excitation transfer, competing with relaxation to the lowest excited state at 49 750 cm-1. It is briefly discussed that the Rydberg series, which can be observed only in cyclic (or round) alkanes, may also be one of the key processes that explain molecular structural dependence observed in the excitation transfer and electron mobilities in alkanes.

  12. Helium-Recycling Plant

    NASA Technical Reports Server (NTRS)

    Cook, Joseph

    1996-01-01

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

  13. 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.

  14. Direct observation of ultrafast many-body electron dynamics in an ultracold Rydberg gas

    PubMed Central

    Takei, Nobuyuki; Sommer, Christian; Genes, Claudiu; Pupillo, Guido; Goto, Haruka; Koyasu, Kuniaki; Chiba, Hisashi; Weidemüller, Matthias; Ohmori, Kenji

    2016-01-01

    Many-body correlations govern a variety of important quantum phenomena such as the emergence of superconductivity and magnetism. Understanding quantum many-body systems is thus one of the central goals of modern sciences. Here we demonstrate an experimental approach towards this goal by utilizing an ultracold Rydberg gas generated with a broadband picosecond laser pulse. We follow the ultrafast evolution of its electronic coherence by time-domain Ramsey interferometry with attosecond precision. The observed electronic coherence shows an ultrafast oscillation with a period of 1 femtosecond, whose phase shift on the attosecond timescale is consistent with many-body correlations among Rydberg atoms beyond mean-field approximations. This coherent and ultrafast many-body dynamics is actively controlled by tuning the orbital size and population of the Rydberg state, as well as the mean atomic distance. Our approach will offer a versatile platform to observe and manipulate non-equilibrium dynamics of quantum many-body systems on the ultrafast timescale. PMID:27849054

  15. Direct observation of ultrafast many-body electron dynamics in an ultracold Rydberg gas

    NASA Astrophysics Data System (ADS)

    Takei, Nobuyuki; Sommer, Christian; Genes, Claudiu; Pupillo, Guido; Goto, Haruka; Koyasu, Kuniaki; Chiba, Hisashi; Weidemüller, Matthias; Ohmori, Kenji

    2016-11-01

    Many-body correlations govern a variety of important quantum phenomena such as the emergence of superconductivity and magnetism. Understanding quantum many-body systems is thus one of the central goals of modern sciences. Here we demonstrate an experimental approach towards this goal by utilizing an ultracold Rydberg gas generated with a broadband picosecond laser pulse. We follow the ultrafast evolution of its electronic coherence by time-domain Ramsey interferometry with attosecond precision. The observed electronic coherence shows an ultrafast oscillation with a period of 1 femtosecond, whose phase shift on the attosecond timescale is consistent with many-body correlations among Rydberg atoms beyond mean-field approximations. This coherent and ultrafast many-body dynamics is actively controlled by tuning the orbital size and population of the Rydberg state, as well as the mean atomic distance. Our approach will offer a versatile platform to observe and manipulate non-equilibrium dynamics of quantum many-body systems on the ultrafast timescale.

  16. 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.

  17. On the adiabatic preparation of spatially-ordered Rydberg excitations of atoms in a one-dimensional optical lattice by laser frequency sweeps

    NASA Astrophysics Data System (ADS)

    Petrosyan, David; Mølmer, Klaus; Fleischhauer, Michael

    2016-04-01

    We examine the adiabatic preparation of crystalline phases of Rydberg excitations in a one-dimensional lattice gas by frequency sweep of the excitation laser, as proposed by Pohl et al (2010 Phys. Rev. Lett. 104 043002) and recently realized experimentally by Schauß et al (2015 Science 347 1455). We find that the preparation of crystals of a few Rydberg excitations in a unitary system of several tens of atoms requires exceedingly long times for the adiabatic following of the ground state of the system Hamiltonian. Using quantum stochastic (Monte Carlo) wavefunction simulations, we show that realistic decay and dephasing processes affecting the atoms during the preparation lead to a final state of the system that has only a small overlap with the target crystalline state. Yet, the final number and highly sub-Poissonian statistics of Rydberg excitations and their spatial order are little affected by the relaxations.

  18. 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

  19. 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.

  20. Theoretical model of the helium pinhole microscope

    NASA Astrophysics Data System (ADS)

    Palau, Adrià Salvador; Bracco, Gianangelo; Holst, Bodil

    2016-12-01

    In recent years, the development of neutral helium microscopes has gained increasing interest. The low energy, charge neutrality, and inertness of the helium atoms makes helium microscopy an attractive candidate for the imaging of a range of samples. The simplest neutral helium microscope is the so-called pinhole microscope. It consists of a supersonic expansion helium beam collimated by two consecutive apertures (skimmer and pinhole), which together determine the beam spot size and hence the resolution at a given working distance to the sample. Due to the high ionization potential of neutral helium atoms, it is difficult to build efficient helium detectors. Therefore, it is crucial to optimize the microscope design to maximize the intensity for a given resolution and working distance. Here we present an optimization model for the helium pinhole microscope system. We show that for a given resolution and working distance, there is a single intensity maximum. Further we show that with present-day state-of-the-art detector technology (ionization efficiency 1 ×10-3 ), a resolution of the order of 600 nm at a working distance of 3 mm is possible. In order to make this quantification, we have assumed a Lambertian reflecting surface and calculated the beam spot size that gives a signal 100 cts/s within a solid angle of 0.02 π sr, following an existing design. Reducing the working distance to the micron range leads to an improved resolution of around 40 nm.

  1. Strongly-coupled high- n Rydberg atom pairs

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Creation of pairs of high n, n ~ 300 , Rydberg atoms with well-defined initial separations enables study and control of their mutual interactions. If the atoms are initially well separated, their interactions are weak and they evolve independently. Their interactions can be dramatically increased, however, by transferring them to even higher levels using carefully-tailored sequences of one, or more, short electric field pulses, the degree of coupling being strongly influenced by the final target state. Since both atoms are subject to the same pulse(s), strongly-correlated macroscopic two-electron wave packets can be created whose subsequent dynamics can be monitored by application of further probe fields. Interest focuses on energy exchange and formation of long lived two-electron-excited states in which, due to their correlated motions, the electrons remain far apart. The production and properties of such states, which lie at the classical-quantum interface, are being explored experimentally and through classical and quantum simulations. Research supported by the NSF, the Robert A. Welch Foundation, and the FWF (Austria).

  2. Thermal desorption behavior of helium in aged titanium tritide films

    NASA Astrophysics Data System (ADS)

    Cheng, G. J.; Shi, L. Q.; Zhou, X. S.; Liang, J. H.; Wang, W. D.; Long, X. G.; Yang, B. F.; Peng, S. M.

    2015-11-01

    The desorption behavior of helium in TiT(1.5∼1.8)-x3Hex film samples (x = 0.0022-0.22) was investigated by thermal desorption technique in vacuum condition in this paper. The thermal helium desorption spectrometry (THDS) of aging titanium tritide films prepared by electron beam evaporation revealed that, depending on the decayed 3He concentration in the samples, there are more than four states of helium existing in the films. The divided four zones in THDS based on helium states represent respectively: (1) the mobile single helium atoms with low activation energy in all aging samples resulted from the interstitial sites or dissociated from interstitial clusters, loops and dislocations, (2) helium bubbles inside the grain lattices, (3) helium bubbles in the grain boundaries and interconnected networks of dislocations in the helium concentration of 3Hegen/Ti > 0.0094, and (4) helium bubbles near or linked to the film surface by interconnected channel for later aging stage with 3Hegen/Ti > 0.18. The proportion of helium desorption in each zone was estimated, and dissociated energies of helium for different trapping states were given.

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

    NASA Technical Reports Server (NTRS)

    Chutjian, A. N. (Inventor)

    1986-01-01

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

  4. Rydberg-resolved resonant inelastic soft x-ray scattering: dynamics at core ionization thresholds.

    PubMed

    Rubensson, J-E; Söderström, J; Binggeli, C; Gråsjö, J; Andersson, J; Såthe, C; Hennies, F; Bisogni, V; Huang, Y; Olalde, P; Schmitt, T; Strocov, V N; Föhlisch, A; Kennedy, B; Pietzsch, A

    2015-04-03

    Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems.

  5. Precision spectroscopy of Helium

    SciTech Connect

    Cancio, P.; Giusfredi, G.; Mazzotti, D.; De Natale, P.; De Mauro, C.; Krachmalnicoff, V.; Inguscio, M.

    2005-05-05

    Accurate Quantum-Electrodynamics (QED) tests of the simplest bound three body atomic system are performed by precise laser spectroscopic measurements in atomic Helium. In this paper, we present a review of measurements between triplet states at 1083 nm (23S-23P) and at 389 nm (23S-33P). In 4He, such data have been used to measure the fine structure of the triplet P levels and, then, to determine the fine structure constant when compared with equally accurate theoretical calculations. Moreover, the absolute frequencies of the optical transitions have been used for Lamb-shift determinations of the levels involved with unprecedented accuracy. Finally, determination of the He isotopes nuclear structure and, in particular, a measurement of the nuclear charge radius, are performed by using hyperfine structure and isotope-shift measurements.

  6. Transition of the Rydberg series from the spectroscopic to the united atom region in LiH

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Jin; Lee, Chun-Woo; Cheong, Yeon-Joo

    2016-12-01

    The behaviours of Rydberg states are studied using the multi-reference configuration interaction method for the 20 excited electronic states in the four-electron molecular system, LiH, which are greatly different from those in molecular systems with fewer electrons. The electronic structure of LiH is characterized by low-lying doubly excited states at small R but none at R > 0.7a 0. The transition from the doubly excited configuration-dominant states to the singly excited configuration-dominant states is found to take place in a narrow range of R. The Rydberg series at small R and in the spectroscopically observable region are different because of the distinct natures of the two regions. The transition of the doubly excited interlopers 2p2 1D σ and 2p2 1D δ at small R into singly excited Rydberg states in the spectral region is studied. Sharp mirror peaks in the dipole moment curves at the avoided crossing points are explained by non-adiabatic coupling.

  7. Mapping trilobite state signatures in atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Pérez-Ríos, Jesús; Eiles, Matthew T.; Greene, Chris H.

    2016-07-01

    A few-body approach relying on static line broadening theory is developed to treat the spectroscopy of a single Rydberg excitation to a trilobite-like state immersed in a high density ultracold medium. The present theoretical framework implements the recently developed compact treatment of polyatomic Rydberg molecules, allowing for an accurate treatment of a large number of perturbers within the Rydberg orbit. This system exhibits two unique spectral signatures: its lineshape depends on the Rydberg quantum number n but, strikingly, is independent of the density of the medium, and it is characterized by sharply peaked features reflecting the oscillatory structure of the potential energy landscape.

  8. Two-electron R-matrix approach to calculations of potential-energy curves of long-range Rydberg molecules

    NASA Astrophysics Data System (ADS)

    Tarana, Michal; Čurík, Roman

    2016-05-01

    We introduce a computational method developed for study of long-range molecular Rydberg states of such systems that can be approximated by two electrons in a model potential of the atomic cores. The method is based on a two-electron R-matrix approach inside a sphere centered on one of the atoms. The wave function is then connected to a Coulomb region outside the sphere via a multichannel version of the Coulomb Green's function. This approach is applied to a study of Rydberg states of Rb2 for internuclear separations R from 40 to 320 bohrs and energies corresponding to n from 7 to 30. We report bound states associated with the low-lying 3Po resonance and with the virtual state of the rubidium atom that turn into ion-pair-like bound states in the Coulomb potential of the atomic Rydberg core. The results are compared with previous calculations based on single-electron models employing a zero-range contact-potential and short-range modele potential. Czech Science Foundation (Project No. P208/14-15989P).

  9. High teleportation rates using Rydberg-based quantum repeaters

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal; Quraishi, Qudsia

    2015-05-01

    Quantum networking over long distances may be achieved using repeater protocols to generate entanglement between memory nodes. Typically, long-lived memories have low entanglement generation rates. Neutral atom memories can be long-lived, emit at visible wavelengths and can be collectively excited leading to directionally emitted entangled photons. Here, we propose a simplified Rydberg-based quantum repeater based on recent work, where we reduce the number of ground states used for entanglement generation and use only one ensemble at each node, reducing the required resources. The collective excitation allows for deterministic memory generation that is mapped into a directionally emitted photonic qubit without the use of a high finesse optical cavity. We demonstrate a protocol between multiple memories stored within a single ensemble to implement a two-qubit gate. Additionally, we predict teleportation rates of 1 Hz without the use of a high finesse optical cavity, which could be increased to kHz if efficiencies are improved over the currently realized values. We plan to explore these protocols in ultra-cold ensemble of neutral 87Rb atoms and are currently building this setup.

  10. Metastable Aluminum Atoms Floating on the Surface of Helium Nanodroplets.

    PubMed

    Jeffs, Jay; Besley, Nicholas A; Stace, Anthony J; Sarma, Gautam; Cunningham, Ethan M; Boatwright, Adrian; Yang, Shengfu; Ellis, Andrew M

    2015-06-12

    Metal atoms have proved to be sensitive probes of the properties of superfluid helium nanodroplets. To date, all experiments on the doping of helium droplets have concentrated on the attachment of metal atoms in their ground electronic states. Here we report the first examples of metal atoms in excited states becoming attached to helium nanodroplets. The atoms in question are aluminum, and they have been generated by laser ablation in a metastable quartet state, which attaches to and remains on the surface of helium droplets. Evidence for a surface location comes from electronic spectra, which consist of very narrow absorption profiles that show very small spectral shifts. Supporting ab initio calculations show there to be an energy incentive for a metastable Al atom to remain on the surface of a helium droplet rather than move to the interior. The results suggest that helium droplets may provide a method for the capture and transport of metastable excited atomic and molecular species.

  11. Resonances and thresholds in the Rydberg-level population of multiply charged ions at solid surfaces

    NASA Astrophysics Data System (ADS)

    Nedeljković, Lj. D.; Nedeljković, N. N.

    1998-12-01

    We present a theoretical study of resonances and thresholds, two specific features of Rydberg-state formation of multiply charged ions (Z=6, 7, and 8) escaping a solid surface at intermediate velocities (v~1 a.u.) in the normal emergence geometry. The resonances are recognized in pronounced maxima of the experimentally observed population curves of Ar VIII ions for resonant values of the principal quantum number n=nres=11 and for the angular momentum quantum numbers l=1 and 2. Absence of optical signals in detectors of beam-foil experiments for n>nthr of S VI and Cl VII ions (with l=0, 1, and 2) and Ar VIII for l=0 is interpreted as a threshold phenomenon. An interplay between resonance and threshold effects is established within the framework of quantum dynamics of the low angular momentum Rydberg-state formation, based on a generalization of Demkov-Ostrovskii's charge-exchange model. In the model proposed, the Ar VIII resonances appear as a consequence of electron tunneling in the very vicinity of the ion-surface potential barrier top and at some critical ion-surface distances Rc. The observed thresholds are explained by means of a decay mechanism of ionic Rydberg states formed dominantly above the Fermi level EF of a solid conduction band. The theoretically predicted resonant and threshold values, nres and nthr of the principal quantum number n, as well as the obtained population probabilities Pnl=Pnl(v,Z), are in sufficiently good agreement with all available experimental findings.

  12. AB INITIO EQUATIONS OF STATE FOR HYDROGEN (H-REOS.3) AND HELIUM (He-REOS.3) AND THEIR IMPLICATIONS FOR THE INTERIOR OF BROWN DWARFS

    SciTech Connect

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Keele, Julie Adel

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

  14. Controlling Rydberg atom excitations in dense background gases

    NASA Astrophysics Data System (ADS)

    Cubel Liebisch, Tara; Schlagmüller, Michael; Engel, Felix; Nguyen, Huan; Balewski, Jonathan; Lochead, Graham; Böttcher, Fabian; Westphal, Karl M.; Kleinbach, Kathrin S.; Schmid, Thomas; Gaj, Anita; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Pérez-Ríos, Jesús; Greene, Chris H.

    2016-09-01

    We discuss the density shift and broadening of Rydberg spectra measured in cold, dense atom clouds in the context of Rydberg atom spectroscopy done at room temperature, dating back to the experiments of Amaldi and Segrè in 1934. We discuss the theory first developed in 1934 by Fermi to model the mean-field density shift and subsequent developments of the theoretical understanding since then. In particular, we present a model whereby the density shift is calculated using a microscopic model in which the configurations of the perturber atoms within the Rydberg orbit are considered. We present spectroscopic measurements of a Rydberg atom, taken in a Bose-Einstein condensate and thermal clouds with densities varying from 5 × 1014 to 9 × 1012 cm-3. The density shift measured via the spectrum’s center of gravity is compared with the mean-field energy shift expected for the effective atom cloud density determined via a time of flight image. Lastly, we present calculations and data demonstrating the ability of localizing the Rydberg excitation via the density shift within a particular density shell for high principal quantum numbers.

  15. Review of Membranes for Helium Separation and Purification.

    PubMed

    Scholes, Colin A; Ghosh, Ujjal K

    2017-02-17

    Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

  16. Review of Membranes for Helium Separation and Purification

    PubMed Central

    Scholes, Colin A.; Ghosh, Ujjal K.

    2017-01-01

    Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources. PMID:28218644

  17. Helium Accumulation Behavior in Iron Based Model Alloys

    SciTech Connect

    Sugano, R.; Morishita, K.; Kimura, A.

    2003-09-15

    Helium desorption from Fe-based model alloys irradiated by energetic helium ions was measured during post-irradiation annealing to investigate the energetics and kinetics of formation and annihilation of helium-related defects. Desorption temperatures were observed to be widely ranged from 450 to 1500 K, indicating that helium is bound to a wide variety of trapping sites such as vacancies and dislocations at various binding states. Such a feature is also observed in fusion ferritic steel. A comparison of helium desorption spectra obtained using Fe, Fe-Cr and Fe-Cr-Ni alloys showed that helium is more strongly trapped in bcc Fe than fcc Fe. It indicates that the long distance migration of helium takes place less frequently in bcc matrix, which may reduce the probability of helium clustering. Fusion ferric steel has a lot of trapping sites for helium such as dislocations, solute atoms, the interface of precipitates, impurities and lath boundaries, and so on, and in addition, it has bct matrix, indicating that most of helium atoms must be dispersed in the matrix and therefore it is difficult for them to cluster as a bubble. This may be a reason for higher helium resistance of the steel.

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

    SciTech Connect

    Holloway, Christopher L. Gordon, Joshua A.; Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg

    2014-06-16

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

  19. Bilayers of Rydberg atoms as a quantum simulator for unconventional superconductors.

    PubMed

    Hague, J P; MacCormick, C

    2012-11-30

    In condensed matter, it is often difficult to untangle the effects of competing interactions, and this is especially problematic for superconductors. Quantum simulators may help: here we show how exploiting the properties of highly excited Rydberg states of cold fermionic atoms in a bilayer lattice can simulate electron-phonon interactions in the presence of strong correlation--a scenario found in many unconventional superconductors. We discuss the core features of the simulator, and use numerics to compare with condensed matter analogues. Finally, we illustrate how to achieve a practical, tunable implementation of the simulation using "painted spot" potentials.

  20. Classical and quantum dynamical regimes in the bound space projected dynamics of strongly driven H Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Blümel, R.; Hillermeier, C.; Smilansky, U.

    1990-12-01

    The bound space projected dynamics of the one dimensional model of H Rydberg atoms subjected to strong microwave radiation exhibits three dynamical regimes: (i) perturbatively localized, (ii) chaotic, (iii) external field dominated. This classification holds classically as well as quantum mechanically. The spectral properties of the bound space projected dipole operator dominating regime (iii) are studied analytically. A semiclassical analysis shows that its eigenfunctions, projected on the unperturbed basis states | n> of the one dimensional model, decay like n -7/3.

  1. Collisional and Radiative Processes in Adiabatic Deceleration, Deflection, and Off-Axis Trapping of a Rydberg Atom Beam

    SciTech Connect

    Seiler, Ch.; Hogan, S. D.; Schmutz, H.; Agner, J. A.; Merkt, F.

    2011-02-18

    A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 {mu}s, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.

  2. Inelastic Photon Scattering via the Intracavity Rydberg Blockade

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    Electromagnetically induced transparency (EIT) in a ladder system involving a Rydberg level is known to yield giant optical nonlinearities for the probe field, even in the few-photon regime. This enhancement is due to the strong dipole-dipole interactions between Rydberg atoms and the resulting excitation blockade phenomenon. In order to study such highly correlated media, ad hoc models or low-excitation assumptions are generally used to tackle their dynamical response to optical fields. Here, we study the behavior of a cavity Rydberg-EIT setup in the nonequilibrium quantum field formalism, and we obtain analytic expressions for elastic and inelastic components of the cavity transmission spectrum, valid up to higher excitation numbers than previously achieved. This allows us to identify and interpret a polaritonic resonance structure, to our knowledge unreported so far.

  3. Stark-assisted population control of coherent CS(2) 4f and 5p Rydberg wave packets studied by femtosecond time-resolved photoelectron spectroscopy.

    PubMed

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

    2007-09-28

    A two-color (3+1(')) pump-probe scheme is employed to investigate Rydberg wave packet dynamics in carbon disulfide (CS(2) (*)). The state superpositions are created within the 4f and 5p Rydberg manifolds by three photons of the 400 nm pump pulse, and their temporal evolution is monitored with femtosecond time-resolved photoelectron spectroscopy using an 800 nm ionizing probe pulse. The coherent behavior of the non-stationary superpositions are observed through wavepacket revivals upon ionization to either the upper (12) or lower (32) spin-orbit components of CS(2) (+). The results show clearly that the composition of the wavepacket can be efficiently controlled by the power density of the excitation pulse over a range from 500 GWcm(2) to 10 TWcm(2). The results are consistent with the anticipated ac-Stark shift for 400 nm light and demonstrate an effective method for population control in molecular systems. Moreover, it is shown that Rydberg wavepackets can be formed in CS(2) with excitation power densities up to 10 TWcm(2) without significant fragmentation. The exponential 1e population decay (T(1)) of specific excited Rydberg states are recovered by analysis of the coherent part of the signal. The dissociation lifetimes of these states are typically 1.5 ps. However, a region exhibiting a more rapid decay ( approximately 800 fs) is observed for states residing in the energy range of 74 450-74 550 cm(-1), suggestive of an enhanced surface crossing in this region.

  4. Advanced helium magnetometer for space applications

    NASA Technical Reports Server (NTRS)

    Slocum, Robert E.

    1987-01-01

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

  5. Few-body model approach to the bound states of helium-like exotic three-body systems

    NASA Astrophysics Data System (ADS)

    Khan, Md A.

    2016-10-01

    In this paper, calculated energies of the lowest bound S-state of Coulomb three-body systems containing an electron (e —), a negatively charged muon (μ—) and a nucleus (NZ+) of charge number Z are reported. The 3-body relative wave function in the resulting Schrödinger equation is expanded in the complete set of hyperspherical harmonics (HH). Use of the orthonormality of HH leads to an infinite set of coupled differential equations (CDE) which are solved numerically to get the energy E.

  6. Exotic quantum clusters and non-equilibrium dynamics of Rydberg excitations in one-dimensional optical lattices

    NASA Astrophysics Data System (ADS)

    Mattioli, Marco

    2016-12-01

    In this mini-review, we report results from M. Mattioli, et al. [Phys. Rev. Lett. 111, 165302 (2013)], M. Dalmonte, et al. [Phys. Rev. B 92, 045106 (2015)] and M. Mattioli, et al. [New J. Phys. 17, 113039 (2015)], where it is shown that Rydberg atoms trapped in one-dimensional optical lattices are a useful tool to investigate the equilibrium phase diagram and the non-equilibrium dynamics of extended Hubbard models and Kinetically Constrained Models, respectively. Atoms weakly-dressed to an high-lying Rydberg state, which interact with a constant potential extended over several lattice sites, can be in an exotic quantum liquid state, the cluster Luttinger liquid phase [42, 43]. Furthermore, we show how a many-body model of interacting three-level atoms in the V-shaped configuration, where one of the level is a Rydberg state, might relax to equilibrium according to the same rules, so-called kinetic constraints, which are known to reproduce the characteristic dynamical arrest and separation of timescales of real glass-forming materials [62].

  7. Potential energy surfaces in atomic structure: The role of Coulomb correlation in the ground state of helium

    NASA Astrophysics Data System (ADS)

    Salas, L. D.; Arce, J. C.

    2017-02-01

    For the S states of two-electron atoms, we introduce an exact and unique factorization of the internal eigenfunction in terms of a marginal amplitude, which depends functionally on the electron-nucleus distances r1 and r2, and a conditional amplitude, which depends functionally on the interelectronic distance r12 and parametrically on r1 and r2. Applying the variational principle, we derive pseudoeigenvalue equations for these two amplitudes, which cast the internal Schrödinger equation in a form akin to the Born-Oppenheimer separation of nuclear and electronic degrees of freedom in molecules. The marginal equation involves an effective radial Hamiltonian, which contains a nonadiabatic potential energy surface that takes into account all interparticle correlations in an averaged way, and whose unique eigenvalue is the internal energy. At each point (r1,r2) , such surface is, in turn, the unique eigenvalue in the conditional equation. Employing the ground state of He as prototype, we show that the nonadiabatic potential energy surface affords a molecularlike interpretation of the structure of the atom, and aids in the analysis of energetic and spatial aspects of the Coulomb correlation, in particular correlation-induced symmetry breaking and quantum phase transition.

  8. Spatial Patterns in Rydberg Excitations from Logarithmic Pair Interactions

    NASA Astrophysics Data System (ADS)

    Lechner, Wolfgang; Zoller, Peter

    2015-09-01

    The collective excitations in ensembles of dissipative, laser driven ultracold atoms exhibit crystal-like patterns, a many-body effect of the Rydberg blockade mechanism. These crystalline structures are revealed in an experiment from a postselection of configurations with fixed numbers of excitations. Here, we show that these subensembles can be well represented by ensembles of effective particles that interact via logarithmic pair potentials. This allows one to study the emergent patterns with a small number of effective particles to determine the phases of Rydberg crystals and to systematically study contributions from N -body terms.

  9. Non-Markovian dynamics in ultracold Rydberg aggregates

    NASA Astrophysics Data System (ADS)

    Genkin, M.; Schönleber, D. W.; Wüster, S.; Eisfeld, A.

    2016-07-01

    We propose a setup of an open quantum system in which the environment can be tuned such that either Markovian or non-Markovian system dynamics can be achieved. The implementation uses ultracold Rydberg atoms, relying on their strong long-range interactions. Our suggestion extends the features available for quantum simulators of molecular systems employing Rydberg aggregates and presents a new test bench for fundamental studies of the classification of system-environment interactions and the resulting system dynamics in open quantum systems.

  10. Entanglement and the Jaynes-Cummings model with Rydberg-dressed atoms

    NASA Astrophysics Data System (ADS)

    Biedermann, Grant

    2016-05-01

    Controlling quantum entanglement between parts of a many-body system is the key to unlocking the power of quantum information processing for applications such as quantum computation, high-precision sensing, and simulation of many-body physics. Spin degrees of freedom of ultracold neutral atoms in their ground electronic state provide a natural platform given their long coherence times and our ability to control them with magneto-optical fields, but creating strong coherent coupling between spins has been challenging. We demonstrate for the first time a strong and tunable Rydberg-dressed interaction between spins of individually trapped cesium atoms with energy shifts of order 1 MHz in units of Planck's constant. We spectroscopically demonstrate that this system is isomorphic to a Jaynes-Cummings Hamiltonian, and observe the √{ N} nonlinearity of the Jaynes-Cummings ladder with a single symmetric Rydberg excitation. This interaction enables a ground-state spin-flip blockade, whereby simultaneous hyperfine spin flips of two atoms are blockaded due to their mutual interaction. We employ this spin-flip blockade to rapidly produce single-step Bell-state entanglement between atoms. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories and through the National Science Foundation's Center for Quantum Information and Control NSF-1212445.

  11. Measurement of time-varying electric fields near an atom chip using cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    Inhomogeneous fluctuating electric fields near metal surfaces cause undesired heating or decoherence in devices which confine atoms or ions near such a surface (microfabricated ion traps or proposed gas-phase atom/solid-state hybrid quantum systems, for example). Heating of the motion of trapped ions has been used to measure the noise spectral density of these fields but the microscopic mechanism responsible is unknown. We have implemented a complementary measurement technique using cold atoms released from an atom chip and excited to Rydberg states. The dephasing of a coherent superposition of two Rydberg states is used to measure the inhomogeneous electric field, and spin-echo techniques are used to constrain the frequency scaling of the noise spectral density. Compared to ion trap measurements, this technique has the advantage of flexibility in varying parameters such as atom-surface distance since the atoms do not need to be trapped. Field noise at levels typical for room temperature ion traps is detectable in principle, though the frequency resolution and ultimate sensitivity are inferior to ion traps. Work performed in collaboration with O. Cherry and supported by NSERC.

  12. Non-equilibrium fluctuations and metastability arising from non-additive interactions in dissipative multi-component Rydberg gases

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Ricardo; Garrahan, Juan P.; Lesanovsky, Igor

    2016-09-01

    We study the out-of-equilibrium dynamics of dissipative gases of atoms excited to two or more high-lying Rydberg states. This situation bears interesting similarities to classical binary (in general p-ary) mixtures of particles. The effective forces between the components are determined by the inter-level and intra-level interactions of Rydberg atoms. These systems permit to explore new parameter regimes which are physically inaccessible in a classical setting, for example one in which the mixtures exhibit non-additive interactions. In this situation the out-of-equilibrium evolution is characterized by the formation of metastable domains that reach partial equilibration long before the attainment of stationarity. In experimental settings with mesoscopic sizes, this collective behavior may in fact take the appearance of dynamic symmetry breaking.

  13. Lower Rydberg series of methane: a combined coupled cluster linear response and molecular quantum defect orbital calculation.

    PubMed

    Velasco, A M; Pitarch-Ruiz, J; Sánchez de Merás, Alfredo M J; Sánchez-Marín, J; Martin, I

    2006-03-28

    Vertical excitation energies as well as related absolute photoabsorption oscillator strength data are very scarce in the literature for methane. In this study, we have characterized the three existing series of low-lying Rydberg states of CH4 by computing coupled cluster linear response (CCLR) vertical excitation energies together with oscillator strengths in the molecular-adapted quantum defect orbital formalism from a distorted Cs geometry selected on the basis of outer valence green function calculations. The present work provides a wide range of data of excitation energies and absolute oscillator strengths which correspond to the Rydberg series converging to the three lower ionization potential values of the distorted methane molecule, in energy regions for which experimentally measured data appear to be unavailable.

  14. Characterizing high-n quasi-one-dimensional strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    The production of high-n, n ˜300, quasi-one-dimensional (quasi-1D) strontium Rydberg atoms through two-photon excitation of selected extreme Stark states in the presence of a weak dc field is examined using a crossed laser-atom beam geometry. The dipolar polarization of the electron wave function in the product states is probed using two independent techniques. The experimental data are analyzed with a classical trajectory Monte Carlo simulation employing initial ensembles that are obtained with the aid of quantum calculations based on a two-active-electron model. Comparisons between theory and experiment highlight different characteristics of the product quasi-1D states, in particular, their large permanent dipole moments, ˜1.0 to 1.2n2ea0, where e is the electronic charge and a0 is the Bohr radius. Such states can be engineered using pulsed electric fields to create a wide variety of target states.

  15. Ab initio calculations of the equations of state for hydrogen, helium, and water and the relevance to the giant planets

    NASA Astrophysics Data System (ADS)

    French, Martin

    2010-11-01

    Since the interior structure of giant planets inside or outside our solar system cannot be probed directly by experiments, planetary models have been developed to gain further insight. Such models require accurate equations of state (EOS) for the major components (H, He, and heavier compounds like water) up to extreme thermodynamic conditions (pressures of several ten megabars and temperatures of more than ten thousand degrees Kelvin) [1]. Ab initio methods that combine finite temperature density functional theory (FT-DFT) for the electrons with classical molecular dynamics (MD) for the ions have proven to be a powerful tool to calculate such accurate EOS data. In addition, the FT-DFT-MD also generates structural information, transport and optical properties and, most important, information on phase diagrams and demixing regions. Based on our recently calculated ab initio data for H, He, and water, we derive interior models of Saturn and Jupiter and discuss the role of H-He demixing [2] and of the plasma phase transition in hydrogen on the planetary interiors. We also present new models for Uranus and Neptune which offer conditions to allow the formation of the exotic superionic phase of water [3]. The ab initio data can also be applied in planetary evolution scenarios and dynamo simulations of solar and extrasolar planets.[4pt] [1] J. J. Fortney, N. Nettelmann, Space Sci. Rev. 152, 423 (2010)[0pt] [2] W. Lorenzen, B. Holst, R. Redmer, Phys. Rev. Lett. 102, 115701 (2009)[0pt] [3] M. French, T. R. Mattsson, N. Nettelmann, R. Redmer, Phys. Rev. B 79, 054107 (2009)

  16. Effect of photoions on the line shape of the Foerster resonance lines and microwave transitions in cold rubidium Rydberg atoms

    SciTech Connect

    Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Yakshina, E. A.; Ryabtsev, I. I.; Dyubko, S. F.; Alekseev, E. A.; Pogrebnyak, N. L.; Bezuglov, N. N.; Arimondo, E.

    2012-01-15

    Experiments are carried out on the spectroscopy of the Foerster resonance lines Rb(37P) + Rb(37P) {yields} Rb(37S) + Rb(38S) and microwave transitions nP {yields} n Prime S, n Prime D between Rydberg states of cold rubidium atoms in a magneto-optical trap (MOT). Under ordinary conditions, all spectra exhibit a linewidth of 2-3 MHz irrespective of the interaction time between atoms or between atoms and microwave radiation, although the limit resonance width should be determined by the inverse interaction time. The analysis of experimental conditions has shown that the main source of line broadening is the inhomogeneous electric field of cold photoions that are generated under the excitation of initial nP Rydberg states by broadband pulsed laser radiation. The application of an additional electric-field pulse that rapidly extracts photoions produced by a laser pulse leads to a considerable narrowing of lines of microwave resonances and the Foerster resonance. Various sources of line broadening in cold Rydberg atoms are analyzed.

  17. High teleportation rates using cold-atom-ensemble-based quantum repeaters with Rydberg blockade

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal; Li, Xiao; Quraishi, Qudsia

    2016-04-01

    We present a simplified version of a repeater protocol in a cold neutral-atom ensemble with Rydberg excitations optimized for two-node entanglement generation and describe a protocol for quantum teleportation. Our proposal draws from previous proposals [B. Zhao et al., Phys. Rev. A 81, 052329 (2010), 10.1103/PhysRevA.81.052329; Y. Han et al., Phys. Rev. A 81, 052311 (2010), 10.1103/PhysRevA.81.052311] that described efficient and robust protocols for long-distance entanglement with many nodes. Using realistic experimental values, we predict an entanglement generation rate of ˜25 Hz and a teleportation rate of ˜5 Hz . Our predicted rates match the current state-of-the-art experiments for entanglement generation and teleportation between quantum memories. With improved efficiencies we predict entanglement generation and teleportation rates of ˜7.8 and ˜3.6 kHz, respectively, representing a two-order-of-magnitude improvement over the currently realized values. Cold-atom ensembles with Rydberg excitations are promising candidates for repeater nodes because collective effects in the ensemble can be used to deterministically generate a long-lived ground-state memory which may be efficiently mapped onto a directionally emitted single photon.

  18. Ellipticity dependence of neutral Rydberg excitation of atoms in strong laser fields

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Dong, Jingwei; Lv, Hang; Yang, Tianxiang; Lian, Yi; Jin, Mingxing; Xu, Haifeng; Ding, Dajun; Hu, Shilin; Chen, Jing

    2016-11-01

    Rydberg state excitation (RSE) of different atoms in elliptically polarized strong 800 nm laser fields is investigated experimentally, and the results are compared with calculations of the strong-field approximation (SFA) model and the semiclassical model. It is observed that the RSE probability declines with increasing laser ellipticity for all of the He, Ar, and Kr atoms. While the measured ellipticity dependence of He RSE is very consistent with the predictions of both the SFA and semiclassical calculations, the width of the ellipticity dependence for Ar and Kr atoms is wider than that of the SFA model but closer to the semiclassical calculations. Analysis indicates that unlike a tunneling-plus-rescattering process, the decline of the RSE yield with increasing ellipticity can be attributed to a decrease of electrons with low kinetic energy that could be captured in the Rydberg states by the Coulomb potential. It indicates that the atomic RSE process could be related to the very low or near-zero energy structure in the photoelectron spectrum in strong laser fields, which would stimulate further experimental and theoretical studies to reveal their underlying mechanisms.

  19. Non-equilibrium physics of Rydberg lattices in the presence of noise and dissipative processes

    NASA Astrophysics Data System (ADS)

    Abdussalam, Wildan; Gil, Laura I. R.

    2016-12-01

    We study the non-equilibrium dynamics of driven spin lattices in the presence of decoherence caused by either laser phase noise or strong decay. In the first case, we discriminate between correlated and uncorrelated noise and explore their effect on the mean density of Rydberg states and the full counting statistics (FCS). We find that while the mean density is almost identical in both cases, the FCS differ considerably. The main method employed is the Langevin equation (LE) but for the sake of efficiency in certain regimes, we use a Markovian master equation and Monte Carlo rate equations, respectively. In the second case, we consider dissipative systems with more general power-law interactions. We determine the phase diagram in the steady state and analyse its generation dynamics using Monte Carlo rate equations. In contrast to nearest-neighbour models, there is no transition to long-range-ordered phases for realistic interactions and resonant driving. Yet, for finite laser detunings, we show that Rydberg lattices can undergo a dissipative phase transition to a long-range-ordered antiferromagnetic (AF) phase. We identify the advantages of Monte Carlo rate equations over mean field (MF) predictions.

  20. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  1. The Descending Helium Balloon

    ERIC Educational Resources Information Center

    Helseth, Lars Egil

    2014-01-01

    I describe a simple and fascinating experiment wherein helium leaks out of a rubber balloon, thereby causing it to descend. An estimate of the volumetric leakage rate is made by measuring its rate of descent.

  2. Charge transfer in helium-rich supernova plasma

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.

    1994-01-01

    Charge transfer rate coefficients are estimated using Landau-Zener and modified Demkov approximations. The coefficients, augmented by those available from the literature, are used in statistical equilibrium equations describing the state of helium-rich supernova plasma. Such a plasma may describe both Type Ib and Type Ic supernova ejecta. The hypothesis that extensive mixing of metals with helium in Type Ic supernovae may provide a catalyst for rapid charge transfer that weakens the helium line emission by altering the excitation balance is tested. It is shown that charge transfer as a mechanism for suppressing helium line emission is ineffective unless the metal abundance is comparable to or larger than the helium abundance. This result supports an earlier conclusion that Type Ic supernovae must be helium poor relative to Type Ib events.

  3. Emergence of a Metallic Quantum Solid Phase in a Rydberg-Dressed Fermi Gas.

    PubMed

    Li, Wei-Han; Hsieh, Tzu-Chi; Mou, Chung-Yu; Wang, Daw-Wei

    2016-07-15

    We examine possible low-temperature phases of a repulsively Rydberg-dressed Fermi gas in a three-dimensional free space. It is shown that the collective density excitations develop a roton minimum, which is softened at a wave vector smaller than the Fermi wave vector when the particle density is above a critical value. The mean field calculation shows that, unlike the insulating density wave states often observed in conventional condensed matters, a self-assembled metallic density wave state emerges at low temperatures. In particular, the density wave state supports a Fermi surface and a body-centered-cubic crystal order at the same time with the estimated critical temperature being about one tenth of the noninteracting Fermi energy. Our results suggest the emergence of a fermionic quantum solid that should be observable in the current experimental setup.

  4. Investigations of levitated helium drops

    NASA Astrophysics Data System (ADS)

    Whitaker, Dwight Lawrence

    1999-11-01

    We report on the development of two systems capable of levitating drops of liquid helium. Helium drops of ˜20 mum have been levitated with the radiation pressure from two counter-propagating Nd:YAG laser beams. Drops are produced with a submerged piezoelectric transducer, and could be held for up to three minutes in our optical trap. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pressure of the curved drop surfaces appears to be a significant effect limiting the drop lifetimes. Helium drops as large as 2 cm in diameter have been suspended in the earth's gravitational field with a magnetic field. A commercial superconducting solenoid provides the necessary field, field-gradient product required to levitate the drops. Drops are cooled to 0.5 K with a helium-3 refrigerator, and can be held in the trap indefinitely. We have found that when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. This effect is a result of the evaporation of liquid from between the two drops, and is found to occur only for normal fluid drops. We can induce shape oscillations in charged, levitated drops with an applied ac electric field. We have measured the resonance frequencies and damping rates for the l = 2 mode of oscillation as function of temperature. We have also developed a theory to describe the small amplitude shape oscillations of a He II drop surrounded by its saturated vapor. In our theory, we have considered two sets of boundary conditions---one where the drop does not evaporate and another in which the liquid and vapor are in thermodynamic equilibrium. We have found that both solutions give a frequency that agrees well with experiment, but that the data for the damping rate agree better with the solution without evaporation.

  5. Is solid helium a supersolid?

    SciTech Connect

    Hallock, Robert

    2015-05-15

    Recent experiments suggest that helium-4 atoms can flow through an experimental cell filled with solid helium. But that incompletely understood flow is quite different from the reported superfluid-like motion that so excited physicists a decade ago.

  6. Helium-refrigeration system

    SciTech Connect

    Specht, J.R.; Millar, B.; Sutherland, A.

    1995-08-01

    The design, procurement, and preliminary construction was completed for adding two more wet expansion engines to two helium refrigerators. These will be added in mid-year FY 1995. In addition a variable speed drive will be added to an existing helium compressor. This is part of an energy conservation upgrade project to reduce operating costs from the use of electricity and liquid nitrogen. This project involves the replacement of Joule-Thompson valves in the refrigerators with expansion engines resulting in system efficiency improvements of about 30% and improved system reliability.

  7. Excitation of helium ion by positron impact

    SciTech Connect

    Khan, P.; Ghosh, A.S.

    1986-01-01

    Three (1s,2s,2p) and five (1s,2s,2p,3s-bar,3p-bar) -state close-coupling methods have been employed to calculate the n = 2 excitation cross sections of helium ion by positron impact. The effect of pseudostate is found to be very pronounced in the case of 1s-2s excitation.

  8. 30 CFR 556.11 - Helium.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Outer Continental Shelf Oil, Gas, and Sulphur Management, General... helium from all gas produced from the leased area. (b) In case the United States elects to take...

  9. 30 CFR 556.11 - Helium.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Outer Continental Shelf Oil, Gas, and Sulphur Management, General... 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, 2014 CFR

    2014-07-01

    ... BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF SULPHUR OR OIL AND GAS IN THE OUTER CONTINENTAL SHELF Outer Continental Shelf Oil, Gas, and Sulphur Management, General... helium from all gas produced from the leased area. (b) In case the United States elects to take...

  11. Superfluid helium-4 in one dimensional channel

    NASA Astrophysics Data System (ADS)

    Kim, Duk Y.; Banavar, Samhita; Chan, Moses H. W.; Hayes, John; Sazio, Pier

    2013-03-01

    Superfluidity, as superconductivity, cannot exist in a strict one-dimensional system. However, the experiments employing porous media showed that superfluid helium can flow through the pores of nanometer size. Here we report a study of the flow of liquid helium through a single hollow glass fiber of 4 cm in length with an open id of 150 nm between 1.6 and 2.3 K. We found the superfluid transition temperature was suppressed in the hollow cylinder and that there is no flow above the transition. Critical velocity at temperature below the transition temperature was determined. Our results bear some similarity to that found by Savard et. al. studying the flow of helium through a nanohole in a silicon nitrite membrane. Experimental study at Penn State is supported by NSF Grants No. DMR 1103159.

  12. Cavitation in flowing superfluid helium

    NASA Technical Reports Server (NTRS)

    Daney, D. E.

    1988-01-01

    Flowing superfluid helium cavitates much more readily than normal liquid helium, and there is a marked difference in the cavitation behavior of the two fluids as the lambda point is traversed. Examples of cavitation in a turbine meter and centrifugal pump are given, together with measurements of the cavitation strength of flowing superfluid helium. The unusual cavitation behavior of superfluid helium is attributed to its immense thermal conductivity .

  13. KAULAKYS: Inelastic collisions between hydrogen atoms and Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Barklem, Paul S.

    2017-01-01

    KAULAKYS calculates cross sections and rate coefficients for inelastic collisions between Rydberg atoms and hydrogen atoms according to the free electron model of Kaulakys (1986, 1991). It is written in IDL and requires the code MSWAVEF (ascl:1701.006) to calculate momentum-space wavefunctions. KAULAKYS can be easily adapted to collisions with perturbers other than hydrogen atoms by providing the appropriate scattering amplitudes.

  14. Interference stabilisation of Rydberg atoms in a strong laser field

    SciTech Connect

    Fedorov, Mikhail V

    1999-07-31

    A review is given of the published theoretical and experimental investigations of the interference stabilisation of Rydberg atoms by a strong optical field. The physical nature of the effect, the models used to describe it, the alternative stabilisation mechanisms, and the extent to which the theoretical results match the published experimental data are discussed. (this issue is dedicated to the memory of s a akhmanov)

  15. Time-domain Ramsey interferometry with interacting Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Sommer, Christian; Pupillo, Guido; Takei, Nobuyuki; Takeda, Shuntaro; Tanaka, Akira; Ohmori, Kenji; Genes, Claudiu

    2016-11-01

    We theoretically investigate the dynamics of a gas of strongly interacting Rydberg atoms subject to a time-domain Ramsey interferometry protocol. The many-body dynamics is governed by an Ising-type Hamiltonian with long-range interactions of tunable strength. We analyze and model the contrast degradation and phase accumulation of the Ramsey signal and identify scaling laws for varying interrogation times, ensemble densities, and ensemble dimensionalities.

  16. Detailed and simplified nonequilibrium helium ionization in the solar atmosphere

    SciTech Connect

    Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit E-mail: mats.carlsson@astro.uio.no

    2014-03-20

    Helium ionization plays an important role in the energy balance of the upper chromosphere and transition region. Helium spectral lines are also often used as diagnostics of these regions. We carry out one-dimensional radiation-hydrodynamics simulations of the solar atmosphere and find that the helium ionization is set mostly by photoionization and direct collisional ionization, counteracted by radiative recombination cascades. By introducing an additional recombination rate mimicking the recombination cascades, we construct a simplified three-level helium model atom consisting of only the ground states. This model atom is suitable for modeling nonequilibrium helium ionization in three-dimensional numerical models. We perform a brief investigation of the formation of the He I 10830 and He II 304 spectral lines. Both lines show nonequilibrium features that are not recovered with statistical equilibrium models, and caution should therefore be exercised when such models are used as a basis for interpretating observations.

  17. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Jabbour Al Maalouf, Elias; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed.

  18. Mantle Helium and Carbon Isotopes in Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon: Evidence for Renewed Volcanic Activity or a Long Term Steady State System?

    USGS Publications Warehouse

    Van Soest, M. C.; Kennedy, B.M.; Evans, William C.; Mariner, R.H.

    2002-01-01

    Here we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of strong crustal uplift currently occurring at a rate of 4-5 cm/yr (Wicks, et. al., 2001).Helium [RC/RA = 7.44 and 8.61 RA (RC/R A = (3He/4He)sample-. air corrected/(3He/4He)air))] and carbon (??13C = -11.59 to -9.03??? vs PDB) isotope data and CO2/3He (5 and 9 ?? 109) show that bubbling cold springs in the Separation Creek area near South Sister volcano carry a strong mantle signal, indicating the presence of fresh basaltic magma in the volcanic plumbing system. There is no evidence though, to directly relate this signal to the crustal uplift that is currently taking place in the area, which started in 1998. The geothermal system in the area is apparently much longer lived and shows no significant changes in chemistry compared to data from the early 1990s. Hot springs in the area, which are relatively far removed from the volcanic edifice, do not carry a strong mantle signal in helium isotope ratios (2.79 to 5.08 RA), unlike the cold springs, and also do not show any significant changes in helium isotope ratios compared to literature data for the same springs of over two decades ago. The cold springs of the Separation Creek area form a very diffuse but significant low temperature geothermal system, that should, due to its close vicinity to the center of up uplift, be more sensitive to changes in the deeper volcanic plumbing system than the far removed hot springs and therefore require much more study and consideration when dealing with volcano monitoring in the Cascade range or possibly with geothermal exploration in general.

  19. Single-shot high-resolution heterodyne detection of millimeter wave superradiance in Rydberg-Rydberg transitions

    NASA Astrophysics Data System (ADS)

    Grimes, David; Yelin, Susanne; Barnum, Timothy; Zhou, Yan; Coy, Steven; Field, Robert

    2016-05-01

    Millimeter wave (mm-wave) superradiance has been directly detected on a shot-by-shot basis in a neon buffer gas cooled beam of barium atoms. Rydberg-Rydberg transitions are well suited for the study of superradiance due to both the large transition dipole moments and long wavelengths associated with Δn = 1 transitions. We trigger the superradiant evolution of an initially 100% inverted system of Rydberg atoms (n = 30) with a weak mm-wave trigger pulse that is well-characterized in both spatial intensity distribution and phase. The resultant mm-wave emission is recorded in a heterodyne detection scheme with high resolution in both the time (20 ps) and frequency (250 kHz) domains. We observe that the width and emission delay of the time-domain intensity can be well described by a mean-field theory, but that the frequency-domain effects are not even qualitatively reproduced. In particular, a density-dependent broadening, frequency chirp, and line shift are observed. Comparisons to a two-atom master equation theoretical model will be discussed.

  20. Coupling of the coronal helium abundance to the solar wind

    NASA Technical Reports Server (NTRS)

    Hansteen, Viggo H.; Leer, Egil; Holzer, Thomas E.

    1994-01-01

    Models of the transition region-corona-solar wind system are investigated in order to find the coronal helium abundance and to study the role played by coronal helium in controlling the solar wind proton flux. The thermal force on alpha-particles in the transition region sets the flow of helium into the corona. The frictional coupling between alpha-particles and protons and/or the electric polarization field determines the proton flux in the solar wind as well as the fate of the coronal helium content. The models are constructed by solving the time-dependent population and momentum equations for all species of hydrogen and helium in an atmosphere with a given temperature profile. Several temperature profiles are considered in order to very the roles of frictional coupling and electric polarization field in the solar wind, and the thermal force in the transition region. Steady-state solutions are found for coronae with a hydrogen flux at 1 AU of 1.0 x 10(exp 9)/cm(exp 2)/sec or larger. For coronae with lower hydrogen fluxes, the helium flux into the corona is larger than the flux 'pulled out' by the solar wind protons, and solutions with increasing coronal helium content are found. The timescale for forming a helium-filled corona, that may allow for a steady outflow, is long compared to the mixing time for the corona.

  1. Tunable VUV photochemistry using Rydberg H-atom time-of-flight spectroscopy.

    PubMed

    Yuan, Kaijun; Cheng, Lina; Cheng, Yuan; Guo, Qing; Dai, Dongxu; Yang, Xueming

    2008-12-01

    In this article, we report an experimental method for studying tunable vacuum ultraviolet (VUV) photochemistry using the H-atom Rydberg tagging technique. In this method, two VUV laser light beams were generated using nonlinear four-wave mixing scheme in a single Kr gas cell: one VUV beam is fixed at the 121.6 nm wavelength to probe the H-atom product through the Lyman alpha transition, the other beam can be tunable for photodissociating molecules in the wavelength range lambda(VUV)=121-190 nm. Preliminary results on the H(2)O photodissociation in the B state are reported here. These results suggest that the experimental method is a powerful tool for investigating photodissociation dynamics in the VUV region for molecules involving H-atom processes.

  2. Steady state boiling crisis in a helium vertically heated natural circulation loop - Part 1: Critical heat flux, boiling crisis onset and hysteresis

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

    2016-01-01

    Experiments were conducted on a 2-m high two-phase helium natural circulation loop operating at 4.2 K and 1 atm. The same loop was used in two experiments with different heated section internal diameter (10 and 6 mm). The power applied on the heated section wall was controlled in increasing and decreasing sequences, and temperature along the section, mass flow rate and pressure drop evolutions were recorded. The values of critical heat flux (CHF) were found at different positions of the test section, and the post-CHF regime was studied. The predictions of CHF by existing correlations were good in the downstream portion of the section, however CHF anomalies have been observed near the entrance, in the low quality region. In resonance with this, the re-wetting of the surface has distinct hysteresis behavior in each of the two CHF regions. Furthermore, hydraulics effects of crisis, namely on friction, were studied (Part 2). This research is the starting point to future works addressing transients conducing to boiling crisis in helium natural circulation loops.

  3. Dissociation of CH4 and CD4 by electron impact - Production of metastable and high-Rydberg hydrogen and carbon fragments

    NASA Technical Reports Server (NTRS)

    Finn, T. G.; Carnahan, B. L.; Wells, W. C.; Zipf, E. C.

    1975-01-01

    Production of hydrogen and carbon atoms in metastable and high-lying Rydberg states by electron-impact dissociation of methane and deuterated methane is investigated for incident electron energies ranging from threshold values to 300 eV. Threshold energies for five different processes resulting in metastable hydrogen and carbon atoms are determined in the energy range from 20 to 70 eV, and it is shown that metastable hydrogen atoms are produced in four of these collisional processes while metastable carbon atoms are produced in the other. The nature of each collisional process is described, differential cross sections are derived for the dissociative excitation of both types of atoms to metastable and high-Rydberg states at 100 eV, and the onset energy for UV photon production is measured. Much of the data is interpreted in terms of the ion core model suggested by Kupriyanov (1968) and developed by Freund (1971).

  4. Tunable two-dimensional arrays of single Rydberg atoms for realizing quantum Ising models

    NASA Astrophysics Data System (ADS)

    Labuhn, Henning; Barredo, Daniel; Ravets, Sylvain; de Léséleuc, Sylvain; Macrì, Tommaso; Lahaye, Thierry; Browaeys, Antoine

    2016-06-01

    Spin models are the prime example of simplified many-body Hamiltonians used to model complex, strongly correlated real-world materials. However, despite the simplified character of such models, their dynamics often cannot be simulated exactly on classical computers when the number of particles exceeds a few tens. For this reason, quantum simulation of spin Hamiltonians using the tools of atomic and molecular physics has become a very active field over the past years, using ultracold atoms or molecules in optical lattices, or trapped ions. All of these approaches have their own strengths and limitations. Here we report an alternative platform for the study of spin systems, using individual atoms trapped in tunable two-dimensional arrays of optical microtraps with arbitrary geometries, where filling fractions range from 60 to 100 per cent. When excited to high-energy Rydberg D states, the atoms undergo strong interactions whose anisotropic character opens the way to simulating exotic matter. We illustrate the versatility of our system by studying the dynamics of a quantum Ising-like spin-1/2 system in a transverse field with up to 30 spins, for a variety of geometries in one and two dimensions, and for a wide range of interaction strengths. For geometries where the anisotropy is expected to have small effects on the dynamics, we find excellent agreement with ab initio simulations of the spin-1/2 system, while for strongly anisotropic situations the multilevel structure of the D states has a measurable influence. Our findings establish arrays of single Rydberg atoms as a versatile platform for the study of quantum magnetism.

  5. Tunable two-dimensional arrays of single Rydberg atoms for realizing quantum Ising models.

    PubMed

    Labuhn, Henning; Barredo, Daniel; Ravets, Sylvain; de Léséleuc, Sylvain; Macrì, Tommaso; Lahaye, Thierry; Browaeys, Antoine

    2016-06-30

    Spin models are the prime example of simplified many-body Hamiltonians used to model complex, strongly correlated real-world materials. However, despite the simplified character of such models, their dynamics often cannot be simulated exactly on classical computers when the number of particles exceeds a few tens. For this reason, quantum simulation of spin Hamiltonians using the tools of atomic and molecular physics has become a very active field over the past years, using ultracold atoms or molecules in optical lattices, or trapped ions. All of these approaches have their own strengths and limitations. Here we report an alternative platform for the study of spin systems, using individual atoms trapped in tunable two-dimensional arrays of optical microtraps with arbitrary geometries, where filling fractions range from 60 to 100 per cent. When excited to high-energy Rydberg D states, the atoms undergo strong interactions whose anisotropic character opens the way to simulating exotic matter. We illustrate the versatility of our system by studying the dynamics of a quantum Ising-like spin-1/2 system in a transverse field with up to 30 spins, for a variety of geometries in one and two dimensions, and for a wide range of interaction strengths. For geometries where the anisotropy is expected to have small effects on the dynamics, we find excellent agreement with ab initio simulations of the spin-1/2 system, while for strongly anisotropic situations the multilevel structure of the D states has a measurable influence. Our findings establish arrays of single Rydberg atoms as a versatile platform for the study of quantum magnetism.

  6. Information Storage and Processing in Rydberg Atoms

    DTIC Science & Technology

    2008-12-01

    The admixture of the orbital angular momentum states, | ITIL | = 0,1 in the two fine-structure eigenstates as well as the energy splitting, e, between...eigenstates are equal admixtures of the ITIL = 0 and | ITIL | = 1 states. Moreover, due to the spin-orbit coupling, the energy splitting between the...electron spin and orbital angular momentum and projects the wavepacket onto the | ITIL | = 0,1 eigenstates. Thus, we can specify the state vector, |vPm(T

  7. Auroral helium precipitation.

    NASA Technical Reports Server (NTRS)

    Axford, W. I.; Chivers, H. J. A.; Eberhardt, P.; Geiss, J.; Buehler, F.

    1972-01-01

    Application of the metal foil sampling technique, which has been used to measure helium, neon, and argon fluxes in the solar wind, to the problem of measuring the fluxes of these gases in the auroral primary radiation. Aluminum and platinum foils have been flown into two bright auroras and have been recovered. The foils have been analyzed for helium and neon isotopes with a mass spectrometer; so far only He4 has been detected. In the first flight the precipitating flux of He4 with particle energies above about 1 keV was approximately 1,000,000 per sq cm per sec, and the backscattered flux was smaller by about a factor of 10. In the second flight the aurora was less bright, and the He4 fluxes were lower by a factor of about 2. A rough analysis suggests that the mean energy of the incident particles was greater than 3 keV.

  8. Development and Dissemination of a Nationwide Helium Database for a National Assessment of Helium Resources.

    NASA Astrophysics Data System (ADS)

    Brennan, S. T.; East, J. A., II; Garrity, C. P.

    2015-12-01

    In 2013, Congress passed the Helium Stewardship Act requiring the U.S. Geological Survey (USGS) to undertake a national helium gas resource assessment to determine the nation's helium resources. An important initial component necessary to complete this assessment was the development of a comprehensive database of Helium (He) concentrations from petroleum exploration wells. Because Helium is often used as the carrier gas for compositional analyses for commercial and exploratory oil and gas wells, this limits the available helium concentration data. A literature search in peer-reviewed publications, state geologic survey databases, USGS energy geochemical databases, and the Bureau of Land Management databases provided approximately 16,000 data points from wells that had measurable He concentrations in the gas composition analyses. The data from these wells includes, date of sample collection, American Petroleum Institute well number, formation name, field name, depth of sample collection, and location. The gas compositional analyses, some performed as far back as 1934, do not all have the same level of precision and accuracy, therefore the date of the analysis is critical to the assessment as it indicates the relative amount of uncertainty in the analytical results. Non-proprietary data was used to create a GIS based interactive web interface that allows users to visualize, inspect, interact, and download our most current He data. The user can click on individual locations to see the available data at that location, as well as zoom in and out on a data density map. Concentrations on the map range from .04 mol% (lowest concentration of economic value) to 12% (highest naturally occurring values). This visual interface will allow users to develop a rapid appreciation of the areas with the highest potential for high helium concentrations within oil and gas fields.

  9. Quantum model of the Thomson helium atom

    NASA Astrophysics Data System (ADS)

    Kazaryan, E. M.; Shakhnazaryan, V. A.; Sarkisyan, H. A.; Gusev, A. A.

    2014-03-01

    A quantum model of the Thomson helium atom is considered within the framework of stationary perturbation theory. It is shown that from a formal point of view this problem is similar to that of two-electron states in a parabolic quantum dot. The ground state energy of the quantum Thomson helium atom is estimated on the basis of Heisenberg's uncertainty principle. The ground state energies obtained in the first order of perturbation theory and qualitative estimate provide, respectively, upper and lower estimates of eigenvalues derived by numerically solving the problem for a quantum model. The conditions under which the Kohn theorem holds in this system, when the values of resonance absorption frequencies are independent of the Coulomb interaction between electrons, are discussed.

  10. Applications of Groundwater Helium

    USGS Publications Warehouse

    Kulongoski, Justin T.; Hilton, David R.

    2011-01-01

    Helium abundance and isotope variations have widespread application in groundwater-related studies. This stems from the inert nature of this noble gas and the fact that its two isotopes ? helium-3 and helium-4 ? have distinct origins and vary widely in different terrestrial reservoirs. These attributes allow He concentrations and 3He/4He isotope ratios to be used to recognize and quantify the influence of a number of potential contributors to the total He budget of a groundwater sample. These are atmospheric components, such as air-equilibrated and air-entrained He, as well as terrigenic components, including in situ (aquifer) He, deep crustal and/or mantle He and tritiogenic 3He. Each of these components can be exploited to reveal information on a number of topics, from groundwater chronology, through degassing of the Earth?s crust to the role of faults in the transfer of mantle-derived volatiles to the surface. In this review, we present a guide to how groundwater He is collected from aquifer systems and quantitatively measured in the laboratory. We then illustrate the approach of resolving the measured He characteristics into its component structures using assumptions of endmember compositions. This is followed by a discussion of the application of groundwater He to the types of topics mentioned above using case studies from aquifers in California and Australia. Finally, we present possible future research directions involving dissolved He in groundwater.

  11. Education in Helium Refrigeration

    NASA Astrophysics Data System (ADS)

    Gistau Baguer, G. M.

    2004-06-01

    On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics… and so on. Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity.

  12. Education in Helium Refrigeration

    SciTech Connect

    Gistau Baguer, G. M.

    2004-06-23

    On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics... and so on.Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity.

  13. Rydberg-to-M -shell x-ray emission of hollow Xeq+ (q =27 - 30 ) atoms or ions above metallic surfaces

    NASA Astrophysics Data System (ADS)

    Song, Z. Y.; Yang, Z. H.; Zhang, H. Q.; Shao, J. X.; Cui, Y.; Zhang, Y. P.; Zhang, X. A.; Zhao, Y. T.; Chen, X. M.; Xiao, G. Q.

    2015-04-01

    X rays originating from transitions from high Rydberg states to the M shell (here called Rydberg-to-M -shell x rays) have been measured in the interaction of Xeq+ (q =27 - 30 ) ions with aluminum, molybdenum, and beryllium surfaces in the energy range of 350-600 keV, by using a Si(Li) detector. The transition energy calculation by Cowan's program with relativistic correlation indicates that such x rays are mainly from the transition of the higher quantum states, with the principal quantum number from 6 up to 30, directly to M shell of xenon. The yield of the x ray per vacancy in M shell decreases slightly with increasing the projectile energies and is inversely proportional to the work functions of metallic surfaces used. However, it increases rapidly with the increase of the projectile charge states. All of these experimental facts combined with the transition rate calculations indicate that the measured Rydberg-to-M -shell x rays come from the "above the surface" hollow Xe atoms or ions deexcitation, when the inner shells such as N and O have not been filled.

  14. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Maalouf, Elias Jabbour Al; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  15. Evaluation of helium cooling for fusion divertors

    SciTech Connect

    Baxi, C.B.

    1993-09-01

    The divertors of future fusion reactors will have a power throughput of several hundred MW. The peak heat flux on the diverter surface is estimated to be 5 to 15 MW/m{sup 2} at an average heat flux of 2 MW/m{sup 2}. The divertors have a requirement of both minimum temperature (100{degrees}C) and maximum temperature. The minimum temperature is dictated by the requirement to reduce the absorption of plasma, and the maximum temperature is determined by the thermo-mechanical properties of the plasma facing materials. Coolants that have been considered for fusion reactors are water, liquid metals and helium. Helium cooling has been shown to be very attractive from safety and other considerations. Helium is chemically and neutronically inert and is suitable for power conversion. The challenges associated with helium cooling are: (1) Manifold sizes; (2) Pumping power; and (3) Leak prevention. In this paper the first two of the above design issues are addressed. A variety of heat transfer enhancement techniques are considered to demonstrate that the manifold sizes and the pumping power can be reduced to acceptable levels. A helium-cooled diverter module was designed and fabricated by GA for steady-state heat flux of 10 MW/m{sup 2}. This module was recently tested at Sandia National Laboratories. At an inlet pressure of 4 MPa, the module was tested at a steady-state heat flux of 10 MW/m{sup 2}. The pumping power required was less than 1% of the power removed. These results verified the design prediction.

  16. Mantle helium and carbon isotopes in Separation Creek Geothermal Springs, Three Sisters area, Central Oregon: Evidence for renewed volcanic activity or a long term steady state system?

    SciTech Connect

    van Soest, M.C.; Kennedy, B.M.; Evans, W.C.; Mariner, R.H.

    2002-04-30

    Cold bubbling springs in the Separation Creek area, the locus of current uplift at South Sister volcano show strong mantle signatures in helium and carbon isotopes and CO{sub 2}/{sup 3}He. This suggests the presence of fresh basaltic magma in the volcanic plumbing system. Currently there is no evidence to link this system directly to the uplift, which started in 1998. To the contrary, all geochemical evidence suggests that there is a long-lived geothermal system in the Separation Creek area, which has not significantly changed since the early 1990s. There was no archived helium and carbon data, so a definite conclusion regarding the strong mantle signature observed in these tracers cannot yet be drawn. There is a distinct discrepancy between the yearly magma supply required to explain the current uplift (0.006 km{sup 3}/yr) and that required to explain the discharge of CO{sub 2} from the system (0.0005 km{sup 3}/yr). This discrepancy may imply that the chemical signal associated with the increase in magma supply has not reached the surface yet. With respect to this the small changes observed at upper Mesa Creek require further attention, due to the recent volcanic vent in that area it may be the location were the chemical signal related to the uplift can most quickly reach the surface. Occurrence of such strong mantle signals in cold/diffuse geothermal systems suggests that these systems should not be ignored during volcano monitoring or geothermal evaluation studies. Although the surface-expression of these springs in terms of heat is minimal, the chemistry carries important information concerning the size and nature of the underlying high-temperature system and any changes taking place in it.

  17. The winter helium bulge revisited

    NASA Astrophysics Data System (ADS)

    Liu, Xianjing; Wang, Wenbin; Thayer, Jeffrey P.; Burns, Alan; Sutton, Eric; Solomon, Stanley C.; Qian, Liying; Lucas, Greg

    2014-10-01

    A newly implemented helium module in the National Center for Atmospheric Research-Thermosphere Ionosphere Electrodynamics general circulation model offers the first opportunity in three decades to describe helium behavior in the context of a first principles, self-consistent model and to test early theories of wintertime helium bulge formation. This study shows general agreement with the findings of Reber and Hays (1973) but articulates the definitive role of vertical advection in the bulge formation. Our findings indicate vertical advection and molecular diffusion are the dominate processes responsible for the solstice helium distribution. Horizontal winds indirectly contribute to the helium bulge formation by their divergent wind field that leads to vertical winds in order to maintain thermosphere mass continuity. As a minor gas, thermospheric helium does not contribute to mass continuity and its distribution is dictated by more local interactions and constraints.

  18. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  19. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  20. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  1. Helium jet dispersion to atmosphere

    NASA Astrophysics Data System (ADS)

    Khan, Hasna J.

    On the event of loss of vacuum guard of superinsulated helium dewar, high rate of heat transfer into the tank occurs. The rapid boiling of liquid helium causes the burst disk to rupture at four atmospheres and consequently the helium passes to the atmosphere through vent lines. The gaseous helium forms a vertical buoyant jet as it exits the vent line into a stagnant environment. Characterization of the gaseous jet is achieved by detailed analysis of the axial and radial dependence of the flow parameters.

  2. Miscibility of hydrogen and helium mixtures at megabar pressures

    SciTech Connect

    Klepeis, J.E.; Schafer, K.J.; Barbee, T.W. III; Ross, M.

    1991-09-01

    Models of Jupiter and Saturn postulate a central rock core surrounded by a fluid mixture of hydrogen and helium. These models suggest that the mixture is undergoing phase separation in Saturn but not Jupiter. State-of-the-art total energy calculations of the enthalpy of mixing for ordered alloys of hydrogen and helium confirm that at least partial phase separation has occurred in Saturn and predict that this process has also begun in Jupiter. 15 refs., 2 figs.

  3. Tkachenko waves in rotating superfluid helium

    SciTech Connect

    Andereck, C.D.; Chalupa, J.; Glaberson, W.I.

    1980-01-07

    The resonant response of a stack of disks driven into torsional oscillation within a container of rotating superfluid helium has been observed. It is shown that the oscillation modes excited are related to Tkachenko waves, that is, vortex displacement waves in the vortex array propagating in a direction transverse to the vortex lines. In particular, the resonances occur at peaks in the vortex wave density of states.

  4. Magnetic Levitation and Noncoalescence of Liquid Helium

    SciTech Connect

    Weilert, M.; Whitaker, D.; Maris, H.; Seidel, G.

    1996-12-01

    We describe experiments in which drops of liquid helium-4, as large as 2cm in diameter, are magnetically levitated. We have found that, when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. It appears that this effect is caused by the slow evaporation of liquid from the drops. {copyright} {ital 1996 The American Physical Society.}

  5. l- and n-changing collisions during interaction of a pulsed beam of Li Rydberg atoms with CO2

    NASA Astrophysics Data System (ADS)

    Dubreuil, B.; Harnafi, M.

    1989-07-01

    The pulsed Li atomic beam produced in our experiment is based on controlled transversely-excited-atmospheric CO2 laser-induced ablation of a Li metal target. The atomic beam is propagated in vacuum or in CO2 gas at low pressure. Atoms in the beam are probed by laser-induced fluorescence spectroscopy. This allows the determination of time-of-flight and velocity distributions. Li Rydberg states (n=5-13) are populated in the beam by two-step pulsed-laser excitation. The excited atoms interact with CO2 molecules. l- and n-changing cross sections are deduced from the time evolution of the resonant or collision-induced fluorescence following this selective excitation. l-changing cross sections of the order of 104 AṦ are measured; they increase with n as opposed to the plateau observed for Li* colliding with a diatomic molecule. This behavior is qualitatively well explained in the framework of the free-electron model. n-->n' changing processes with large cross sections (10-100 AṦ) are also observed even in the case of large electronic energy change (ΔEnn'>103 cm-1). These results can be interpreted in terms of resonant-electronic to vibrational energy transfers between Li Rydberg states and CO2 vibrational modes.

  6. Rayleigh Scattering by Helium in Stellar Atmospheres

    NASA Astrophysics Data System (ADS)

    Fišák, J.; Kubát, J.; Krtička, J.

    2017-02-01

    We study the influence of Rayleigh scattering by helium on synthetic spectra and stellar atmosphere models. Rayleigh scattering by helium is often neglected in hot star atmosphere models. This approximation is justified by the small population of helium in stars with solar composition (about 10% by number) and lower Rayleigh scattering total cross section of helium with respect to neutral hydrogen. However, for stars with large helium abundances Rayleigh scattering by helium can be a significant opacity source.

  7. Handshake electron transfer from hydrogen Rydberg atoms incident at a series of metallic thin films.

    PubMed

    Gibbard, J A; Softley, T P

    2016-06-21

    Thin metallic films have a 1D quantum well along the surface normal direction, which yields particle-in-a-box style electronic quantum states. However the quantum well is not infinitely deep and the wavefunctions of these states penetrate outside the surface where the electron is bound by its own image-charge attraction. Therefore a series of discrete, vacant states reach out from the thin film into the vacuum increasing the probability of electron transfer from an external atom or molecule to the thin film, especially for the resonant case where the quantum well energy matches that of the atom. We show that "handshake" electron transfer from a highly excited Rydberg atom to these thin-film states is experimentally measurable. Thicker films have a wider 1D box, changing the energetic distribution and image-state contribution to the thin film wavefunctions, resulting in more resonances. Calculations successfully predict the number of resonances and the nature of the thin-film wavefunctions for a given film thickness.

  8. Handshake electron transfer from hydrogen Rydberg atoms incident at a series of metallic thin films

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Thin metallic films have a 1D quantum well along the surface normal direction, which yields particle-in-a-box style electronic quantum states. However the quantum well is not infinitely deep and the wavefunctions of these states penetrate outside the surface where the electron is bound by its own image-charge attraction. Therefore a series of discrete, vacant states reach out from the thin film into the vacuum increasing the probability of electron transfer from an external atom or molecule to the thin film, especially for the resonant case where the quantum well energy matches that of the atom. We show that "handshake" electron transfer from a highly excited Rydberg atom to these thin-film states is experimentally measurable. Thicker films have a wider 1D box, changing the energetic distribution and image-state contribution to the thin film wavefunctions, resulting in more resonances. Calculations successfully predict the number of resonances and the nature of the thin-film wavefunctions for a given film thickness.

  9. Quantum entanglement in helium-like ions

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    Recently, there have been considerable interests to investigate quantum entanglement in two-electron atoms [1-3]. Here we investigate quantum entanglement for the ground and excited states of helium-like ions using correlated wave functions, concentrating on the particle-particle entanglement coming from the continuous spatial degrees of freedom. We use the two-electron wave functions constructed by employing B-spline basis to calculate the linear entropy of the reduced density matrix L=1-TrA(ρA^2 ) as a measure of the spatial entanglement. HereρA=TrB(| >AB AB<|) is the one-electron reduced density matrix obtained after tracing the two-electron density matrix over the degrees of freedom of the other electron. We have investigated the spatial entanglement for the helium-like systems with Z=1 to Z=10. For the helium atoms (Z=2), we have calculated the linear entropy for the ground state and the 1sns ^1S^e (n=2-10) excited states. Results are compared with other calculations [1-3]. [4pt] [1] J. P. Coe and I. D'Amico, J. Phys.: Conf. Ser. 254, 012010 (2010) [0pt] [2] D. Manzano et. al., J. Phys. A: Math. Theor. 43, 275301 (2010) [0pt] [3] J. S. Dehesa et. al., J. Phys. B 45, 015504 (2012)

  10. Helium dilution refrigeration system

    DOEpatents

    Roach, P.R.; Gray, K.E.

    1988-09-13

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

  11. Helium dilution refrigeration system

    DOEpatents

    Roach, Patrick R.; Gray, Kenneth E.

    1988-01-01

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

  12. Helium diffusion in carbonates

    NASA Astrophysics Data System (ADS)

    Amidon, W. H.; Cherniak, D. J.; Watson, E. B.; Hobbs, D.

    2013-12-01

    The abundance and large grain size of carbonate minerals make them a potentially attractive target for 4He thermochronology and 3He cosmogenic dating, although the diffusive properties of helium in carbonates remain poorly understood. This work characterizes helium diffusion in calcite and dolomite to better understand the crystal-chemical factors controlling He transport and retentivity. Slabs of cleaved natural calcite and dolomite, and polished sections of calcite cut parallel or normal to c, were implanted with 3He at 3 MeV with a dose of 5x1015/cm2. Implanted carbonates were heated in 1-atm furnaces, and 3He distributions following diffusion anneals were profiled with Nuclear Reaction Analysis using the reaction 3He(d,p)4He. For 3He transport normal to cleavage surfaces in calcite, we obtain the following Arrhenius relation over the temperature range 78-300°C: Dcalcite = 9.0x10-9exp(-55 × 6 kJ mol-1/RT) m2sec-1. Diffusion in calcite exhibits marked anisotropy, with diffusion parallel to c about two orders of magnitude slower than diffusion normal to cleavage faces. He diffusivities for transport normal to the c-axis are similar in value to those normal to cleavage surfaces. Our findings are broadly consistent with helium diffusivities from step-heating measurements of calcite by Copeland et al. (2007); these bulk degassing data may reflect varying effects of diffusional anisotropy. Helium diffusion normal to cleavage surfaces in dolomite is significantly slower than diffusion in calcite, and has a much higher activation energy for diffusion. For dolomite, we obtain the following Arrhenius relation for He diffusion over the temperature range 150-400°C: Ddolomite = 9.0x10-8exp(-92 × 9 kJ mol-1/RT) m2sec-1. The role of crystallographic structure in influencing these differences among diffusivities was evaluated using the maximum aperture approach of Cherniak and Watson (2011), in which crystallographic structures are sectioned along possible diffusion

  13. Using PFI-ZEKE spectroscopy to study excited states of molecular ions: implications for state selection through pulsed field ionization

    NASA Astrophysics Data System (ADS)

    Martin, James D.; Alcaraz, Christian; Mank, A.; Kong, Wei; Hepburn, John W.

    1995-09-01

    The introduction of the pulsed field ionization zero kinetic energy photoelectron spectroscopy technique (referred to as PFI-ZEKE spectroscopy) has resulted in a revolution in photoelectron spectroscopy, because of the tremendous improvement in resolution. This method of threshold photoelectron spectroscopy is based on field ionization of metastable high principal quantum number Rydberg states using a pulsed electric field, delayed from the laser excitation. The detailed mechanism for stabilization of the high principal quantum number Rydberg states has been the subject of a great deal of recent discussion in the literature, and is still somewhat controversial. It is well known that Rydberg state lifetimes scale as n-3, for fluorescence, autoionization, or predissociation, under ideal conditions. This means that for a Rydberg series that can decay by autoionization, if the lifetime of a 5p Rydberg state is 10-12 s, the lifetime of a 150p state will be 10-7 s, which is an order of magnitude shorter than typical delay times used in PFI-ZEKE. The 150p state will be field ionized by an electric field of 0.7 to 1.5 V/cm, which is typical of the pulsed fields used for Stark ionization. This question about Rydberg state lifetimes becomes quite important if one wishes to carry out PFI-ZEKE spectroscopy of ion states well above the lowest ionization threshold, as many decay channels will be available to the Rydberg states converging to the high energy states, resulting in shorter lifetimes for these high energy Rydberg states. Our work in this area has focused largely on PFI-ZEKE spectroscopy at excited state thresholds in molecular ions, where problems of autoionization will be most severe. To reach these high energy thresholds, we have usually used single photon excitation with coherent vacuum ultraviolet light. This excitation method has many advantages.

  14. Line shapes and time dynamics of the Förster resonances between two Rydberg atoms in a time-varying electric field

    NASA Astrophysics Data System (ADS)

    Yakshina, E. A.; Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Andreeva, C.; Cinins, A.; Markovski, A.; Iftikhar, Z.; Ekers, A.; Ryabtsev, I. I.

    2016-10-01

    The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. In our experiments with a few cold Rb Rydberg atoms, we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the Förster resonances, since the population transfer at the resonances occurs on a time scale of ˜100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted Förster resonances, while nonsharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb (n P3 /2) +Rb (n P3 /2) →Rb (n S1 /2) +Rb ([n +1 ] S1 /2) for two Rb Rydberg atoms interacting in a time-varying electric field.

  15. Phase separation in hydrogen–helium mixtures at Mbar pressures

    PubMed Central

    Morales, Miguel A.; Schwegler, Eric; Ceperley, David; Pierleoni, Carlo; Hamel, Sebastien; Caspersen, Kyle

    2009-01-01

    The properties of hydrogen–helium mixtures at Mbar pressures and intermediate temperatures (4000 to 10000 K) are calculated with first-principles molecular dynamics simulations. We determine the equation of state as a function of density, temperature, and composition and, using thermodynamic integration, we estimate the Gibbs free energy of mixing, thereby determining the temperature, at a given pressure, when helium becomes insoluble in dense metallic hydrogen. These results are directly relevant to models of the interior structure and evolution of Jovian planets. We find that the temperatures for the demixing of helium and hydrogen are sufficiently high to cross the planetary adiabat of Saturn at pressures ≈5 Mbar; helium is partially miscible throughout a significant portion of the interior of Saturn, and to a lesser extent in Jupiter. PMID:19171896

  16. Electron-helium scattering in Debye plasmas

    SciTech Connect

    Zammit, Mark C.; Fursa, Dmitry V.; Bray, Igor; Janev, R. K.

    2011-11-15

    Electron-helium scattering in weakly coupled hot-dense (Debye) plasma has been investigated using the convergent close-coupling method. The Yukawa-type Debye-Hueckel potential has been used to describe plasma Coulomb screening effects. Benchmark results are presented for momentum transfer cross sections, excitation, ionization, and total cross sections for scattering from the ground and metastable states of helium. Calculations cover the entire energy range up to 1000 eV for the no screening case and various Debye lengths (5-100 a{sub 0}). We find that as the screening interaction increases, the excitation and total cross sections decrease, while the total ionization cross sections increase.

  17. Three Dimensional Particle Tracking in Superfluid Helium

    NASA Astrophysics Data System (ADS)

    Megson, Peter

    2016-11-01

    Superfluid helium is a macroscopic quantum state which exhibits exotic physical properties, such as flow without friction and ballistic heat transport. Superfluid flow is irrotational except about line-like topological phase defects with quantized circulation, known as quatized vortices. The presence of these vortices and their dynamics is the dominating factor of turbulence in superfluid flows. One commonly studied regime of superfluid turbulence is thermal counterflow, where a local heat flux drives the formation and growth of a tangle of vortices. This talk will present experimental studies of counterflow turbulence performed using a multi-camera three-dimensional imaging apparatus with micron-sized ice tracer particles as well as fluorescent nanoparticles. In particular, we will discuss the measurement of three-dimensional velocties and their autocorrelations. Additionally, we are developing new techniques for optical studies of bulk superfluid helium, with particular focus on characterizing tracer particles and particle dispersal mechanisms. Funding from NSF DMR-1407472.

  18. Controlling correlations in the Rydberg-dressing six-wave mixing process

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaoyang; Ma, Danmeng; Liu, Junfeng; Ahmed, Irfan; Tian, Hao; Che, Junling; Tang, Haijun; Raza, Faizan; Zhang, Yanpeng

    2017-01-01

    We report the experimental observation of intensity noise correlation between six-wave mixing (SWM), fluorescence and probe transmission signal in a coherently prepared Rydberg atomic ensemble. With the assistance of the electromagnetically induced transparency (EIT) technique, the Rydberg SWM is generated with high efficiency. Then the correlation between the probe transmission and SWM, the anti-correlation between the probe and fluorescence, and the anti-correlation between SWM and fluorescence occur, with these being caused by the enhanced dispersion and nonlinearity in the Rydberg-EIT medium. Such intensity correlation can be effectively controlled by the strong Rydberg-dressing effect. This investigation can potentially contribute to the further study of multi-field quantum correlations and anti-correlations via atomic spin coherence.

  19. Quantum controlled-phase-flip gate between a flying optical photon and a Rydberg atomic ensemble

    PubMed Central

    Hao, Y. M.; Lin, G. W.; Xia, Keyu; Lin, X. M.; Niu, Y. P.; Gong, S. Q.

    2015-01-01

    Quantum controlled-phase-flip (CPF) gate between a flying photon qubit and a stationary atomic qubit could allow the linking of distant computational nodes in a quantum network. Here we present a scheme to realize quantum CPF gate between a flying optical photon and an atomic ensemble based on cavity input-output process and Rydberg blockade. When a flying single-photon pulse is reflected off the cavity containing a Rydberg atomic ensemble, the dark resonance and Rydberg blockade induce a conditional phase shift for the photon pulse, thus we can achieve the CPF gate between the photon and the atomic ensemble. Assisted by Rydberg blockade interaction, our scheme works in the N-atoms strong-coupling regime and significantly relaxes the requirement of strong coupling of single atom to photon in the optical cavity. PMID:25966448

  20. Ultralong-Range Rb-KRb Rydberg Molecules: Selected Aspects of Electronic Structure, Orientation and Alignment

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    We investigate the structure and features of an ultralong-range triatomic Rydberg molecule formed by a Rb Rydberg atom and a KRb diatomic molecule. In our numerical description, we perform a realistic treatment of the internal rotational motion of the diatomic molecule, and take into account the Rb(n, l ≥ 3) Rydberg degenerate manifold and the energetically closest neighboring levels with principal quantum numbers n' > n and orbital quantum number l ≤ 2. We focus here on the adiabatic electronic potentials evolving from the Rb(n,l ≥ 3) and Rb(n = 26, l = 2) manifolds. The directional properties of the KRb diatomic molecule within the Rb-KRb triatomic Rydberg molecule are also analyzed in detail.